Work apparatus, throttle assembly, internal combustion engine and method for operating internal combustion engine

Abstract

A work apparatus comprises a tool and an internal combustion engine (A-11) for driving the tool. The internal combustion engine (A-11) comprises an intake duct (A-14), in which a throttle element (A-16) is pivotally mounted. The internal combustion engine (A-11) comprises an air channel (A-13) in which an air control element (A-20) is pivotally mounted. An operating element (A-5) is provided for adjusting the throttle element (A-16) in the opening direction (A-42). The internal combustion engine (A-11) has a rotational speed limiting device (A-100). The rotational speed limiting device (A-100) includes an actuator configured to adjust the throttle element (A-16) in the closing direction (A-44) to reduce a free flow cross-section of the intake passage (A-14). The working apparatus (A-1) has an unloaded state in which the tool is driven by the internal combustion engine (A-11) and is not in engagement with the workpiece. The position of the air control element (A-20) is coupled to the position of the throttle element (A-16) via a coupling device (A-58). The coupling device (A-58) has an idle stroke (A-[epsilon]), which enables a pivoting of the throttle element (A-16) relative to the air control element (A-20). The idle stroke (A-epsilon) is dimensioned in such a way that the air control element (A-20) is in its closed position (A-104) in the unloaded state regardless of the position of the operating element (A-5).

Description

Technical Field

[0001] The present invention relates to a working apparatus of the type described in the preamble of claim 1. Background Technology

[0002] A working instrument with a speed limiting device is known from US 2021 / 0254566 A1. The control device for limiting the speed is configured to act on both an air control element and a throttling element. This is relatively complex because both throttling elements must be operated. Summary of the Invention

[0003] The purpose of this invention is to provide a type of working instrument that is simple to construct and can achieve good speed limiting in a simple manner.

[0004] This task is solved by a working instrument having the features of claim 1.

[0005] The position of the air control element is connected to the position of the throttling element via a coupling device. Therefore, only an actuator for the throttling element is needed, and no additional actuator for the air control element is required. This results in a simple structure. The coupling device is configured to allow adjustment of the throttling element relative to the air control element. Therefore, the throttling element can pivot relative to the air control element until the air control element is actuated via the coupling device. Within the adjustment range where the throttling element is movable relative to the air control element without actuating the air control element, the amount of air supplied to the internal combustion engine can be sensitively set.

[0006] The unloaded travel is sized such that, under no-load conditions, the air control element is always in its closed position regardless of the position of the operating element.

[0007] The no-load state is a quasi-steady state. In the no-load state, the constant position and constant speed of the throttling element are already set. When the working machine operates in the no-load state, the constant position of the throttling element is set after a certain duration. When environmental conditions are constant, the position of the throttling element subsequently remains constant and does not change. The duration depends particularly on the working machine and can be, for example, 5 seconds. The environmental conditions and tool inertia under which the maximum adjustment angle of the throttling element is set from the closed position to the fully open position may vary depending on the working machine.

[0008] When the operator manipulates the operating element while the tool is not engaged with the workpiece, the throttling element pivots and the speed increases. If the speed increases excessively, the actuator of the speed limiting device becomes active and adjusts the throttling element in the closed direction to limit the speed. Under no-load conditions, this sets the adjustment angle of the throttling element from the closed position to the fully open position.

[0009] The free travel is sized such that, under no-load conditions, even if the operator manipulates the operating element (e.g., applies full throttle) and the throttle element has been adjusted about the adjustment angle from the closed position to the fully open position, the air control element remains in its closed position. The free travel is sized such that, under no-load conditions, the air control element remains in its closed position regardless of the position of the operating element.

[0010] Therefore, the actuator acts solely on the throttling element from its closed position to the position corresponding to the no-load condition. Adjustment of the throttling element only changes the free-flow cross-section of the intake passage, not the free-flow cross-section of the air passage. This allows for sensitive setting of the supplied air volume under no-load conditions. The engine speed can be well set and thus well limited under no-load conditions.

[0011] The adjustment angle corresponds particularly highly to the idle stroke. The working instrument is specifically designed such that the throttling element is movable relative to the air control element at least until it reaches a position corresponding to the no-load state. When the position of the throttling element changes, during the adjustment of the throttling element from the closed position to the fully open position, the air control element is not moved via the connecting device at least until the position of the throttling element associated with the no-load state is reached.

[0012] The throttling element has both a closed position and a fully open position. Under no-load conditions, the throttling element has a maximum pivot adjustment angle, particularly from the closed position to the fully open position. The connecting device is particularly capable of adjusting the throttling element relative to the air control element by a differential angle. This differential angle corresponds particularly to the no-load stroke. The adjustment angle is particularly highest relative to the differential angle.

[0013] The adjustment angle can vary in particular according to environmental conditions and the inertia of the working instrument. When environmental conditions are constant, the adjustment angle remains constant and unchanged. The adjustment angle is set primarily by the intervention of a speed limiting device, which acts on the position of the throttling element via an actuator.

[0014] The connecting device is especially a mechanical connecting device. This leads to a simple structure.

[0015] The maximum free travel is 30°. The minimum free travel is 15°. The free travel is at least 2° larger than the adjustment angle, and at least 3° larger. Therefore, sensitive speed limiting can be achieved even when the throttling element opening is 2°, and at least 3° larger than the position associated with the adjustment angle. Because the free travel is greater than the adjustment angle, sensitive setting of the desired speed can be achieved even with unsuitable manufacturing tolerances.

[0016] The internal combustion engine includes, in particular, a fuel valve for supplying fuel. The fuel valve is particularly operated by a control device. The control device also particularly controls the actuator of the speed limiting device. Specifically, a control device is provided that controls the actuator, the fuel valve, and the ignition device of the internal combustion engine. Alternatively, the control device can be configured to operate only the actuator of the speed limiting device, and other elements for fuel supply can be provided. Embodiments with multiple control devices can also be advantageous, said control devices communicating with each other and controlling different devices of the working apparatus, such as the fuel supply device, actuator, ignition device, and / or other devices of the working apparatus if necessary.

[0017] If the throttling element is a throttling gate, a simple structure is obtained. The throttling element is pivotally supported, particularly using a throttling shaft. The air control element is pivotally supported, particularly using an air control shaft. In an alternative embodiment, the throttling element and / or air control element can be configured as a control roller.

[0018] Specifically, an operating element is provided for operator control, through which the position of the throttle shaft can be adjusted. The operating element is connected, in particular, via a transmission device to an adjustable stop element for the throttle shaft. The stop element specifically restricts the possible position of the throttle element within a region from the closed position up to a position preset by the stop element. If the actuator is inactive, the throttle element specifically occupies the position preset by the stop element. A closing spring is specifically provided, which preloads the stop element in the closing direction of the throttle shaft. The operator can overcome the force of the closing spring to adjust the stop element via the operating element towards a position associated with the fully open position of the throttle element.

[0019] Specifically, an opening spring is provided, which preloads the throttling shaft toward the stop element in the opening direction. Preferably, the throttling assembly is designed such that, when the operating element and transmission device are in an unoperated state, the torque applied to the throttling shaft by the closing spring is greater than the torque applied to the throttling shaft by the opening spring. This ensures that when the transmission device is in an unoperated state, i.e., when the operator does not operate the operating element, the throttling element is closed by the closing spring. The actuator is particularly advantageously configured to overcome the force of the opening spring to disengage the throttling shaft from the stop element and to adjust the throttling element in the closing direction.

[0020] In particular, the opening spring and the connecting device act on the same end section of the throttle shaft. This allows for a compact structure.

[0021] The connecting device includes, in particular, a connecting element that is anti-rotationally connected to the throttle shaft. Through this connecting element, the movement of the throttle shaft can be easily transmitted to the air control elements, especially by means of additional elements.

[0022] In particular, the opening spring is supported at one end at the connecting element and at the other end at the base. This results in a simple and compact structure and a space-saving arrangement for the opening spring.

[0023] The motor acts specifically on the first end section of the throttle shaft, and the connecting device acts on the second end section of the throttle shaft. The first and second end sections are arranged on opposite sides of the intake passage. This allows for a compact structure.

[0024] The connecting device particularly includes a connecting rod that connects a connecting element anti-rotationally to a throttle shaft and a connecting element anti-rotationally to an air control shaft. The connection between the connecting rod and at least one of the connecting elements particularly has an elongated hole that allows for restricted relative movement of the connecting rod relative to the connecting element. This results in a simple design structure. The elongated hole is particularly configured to allow relative movement of the throttle element relative to the air control element with a free stroke.

[0025] The working equipment, especially the cutting machine, and the tool is a cutting disc. Attached Figure Description

[0026] The embodiments of the present invention will be described below with reference to the accompanying drawings. Wherein: Figure A-1 A schematic side view of a handheld working instrument is shown. Figure A-2 A schematic diagram of a two-stroke engine that utilizes scavenging pre-compression is shown. Figure A-3 Displayed for corresponding Figure A-2 A side view of the throttle assembly of a two-stroke engine. Figure A-4 Showing Figure A-3 An exploded perspective view of the components of the throttling assembly. Figure A-5 A perspective view of the throttling component is shown. Figure A-6 Showing along Figure A-3 A side view of an alternative embodiment of the throttling assembly connection device, pointing in the direction of arrow VI. Figure A-7 A cross-sectional view of the throttling component is shown. Figures A-8 to A-10 Partial sectional views of the throttling assembly in different cutting planes are shown. Figure A-11 A perspective view of the throttling assembly with the motor removed is shown. Figure A-12 The diagram shows the corresponding connection element with additional removal for the motor. Figure A-11 A partial view, Figures A-13 to A-15 A schematic diagram showing the function of the throttling component is provided. Figure A-16 The alternative implementation of the throttling component is shown in cross-sectional view. Figure A-17 and Figure A-18 This shows the removal of the cover plate element at different locations on the transfer device. Figure A-16 A partial perspective view of the throttling component in the image. Detailed Implementation

[0027] Figure A-1 An embodiment of a handheld working instrument A-1 is schematically shown. In this embodiment, the working instrument A-1 is a cutting machine. The working instrument A-1 is particularly portable and handheld during operation. The working instrument A-1 has a rear handle A-3 and a handle tube A-4. An operating element A-5 and a locking element A-6 for the operating element A-5 are arranged at the rear handle A-3. The working instrument A-1 has a cutting disc A-7 as a tool. A drive motor A-11 is used to drive the cutting disc A-7. Other working instruments A-1 with other tools can also be provided. In this embodiment, the drive motor A-11 is a two-stroke engine. The drive motor A-11 is preferably a single-cylinder engine. In this embodiment, the drive motor A-11 is a two-stroke engine that operates using scavenging air pre-compression. The drive motor A-11 is particularly a hybrid lubrication engine, especially a two-stroke engine or a hybrid lubrication four-stroke engine. In this embodiment, the drive motor A-11 can be started by hand. For this purpose, a starter handle A-9 is used.

[0028] The drive motor A-11 has an air filter A-12 through which air is drawn in during operation. Air passage A-13 and intake passage A-14 are used to supply air. It can be configured that air passage A-13 and intake passage A-14 supply pure air. Alternatively, it can be configured that fuel is supplied to intake passage A-14, thereby supplying a fuel / air mixture via intake passage A-14.

[0029] Other designs for the drive motor A-11, especially the design without an air passage A-13, can also be advantageous.

[0030] Figure A-2 The drive motor A-11 is shown in a schematic cross-sectional view. Figure A-2As shown, the drive motor A-11 has a throttling assembly A-15 for controlling the amount of air supplied. In this embodiment, the throttling assembly A-15 includes a throttling element A-16 for controlling the amount of air flowing through the intake passage A-14. The throttling assembly A-15 also has an air control element A-20 for controlling the amount of air flowing through the air passage A-13. In this embodiment, a choke element A-18 is arranged upstream of the throttling element A-16. In an advantageous alternative embodiment, the choke element A-18 may be omitted or otherwise designed. In this embodiment, the throttling element A-16, the choke element A-18, and the air control element A-20 are each pivotally supported. The throttling element A-16 is pivotally supported by a throttling shaft A-17. The choke element A-18 is pivotally supported by a choke shaft A-19. Air control element A-20 is supported by air control shaft A-21. In this embodiment, throttling element A-16, damper element A-18, and air control element A-20 are constructed as valves. However, other designs (e.g., as rollers with openings for air passage extending perpendicular to the axis of rotation) can also be advantageous. It is also possible to configure the drive motor A-11 without damper element A-18.

[0031] The drive motor A-11 includes a cylinder A-22, within which a combustion chamber A-23 is constructed. A piston A-25 is reciprocally supported within cylinder A-22. Piston A-25 drives a crankshaft A-27, rotatably supported in a crankcase A-24, via connecting rod A-26. The crankshaft A-27... Figure A-2 The image is shown schematically only. Crankshaft A-27 is rotatably supported about axis of rotation A-28.

[0032] exist Figure A-2 In the region of bottom dead center of piston A-25 shown, the interior of crankcase A-24 is fluidly connected to combustion chamber A-23 via overflow passage A-29. Overflow passage A-29 opens into combustion chamber A-23 through overflow window A-30. Overflow window A-30 is controlled by piston A-25. Spark plug A-34 extends into combustion chamber A-23, and this spark plug is used to ignite the fuel / air mixture in combustion chamber A-23. Outlet A-35 is led out of combustion chamber A-23, and this outlet is controlled by piston A-25.

[0033] Intake passage A-14 opens into the bore of cylinder A-22 via intake passage inlet A-32. Intake passage inlet A-32 is controlled by piston A-25. Intake passage inlet A-32 connects to the inner cavity of crankcase A-24 in the region of piston A-25 at top dead center. Air passage A-13 opens into the bore of cylinder A-22 via one or more air inlets A-33. Piston A-25 has one or more piston grooves A-31 in its piston skirt. Piston grooves A-31 connect air inlets A-33 to one or more overflow windows A-30 in the region of piston A-25 at top dead center. Air can thus be pre-supplied in overflow passage A-29 via air passage A-13, and this air is used to flush combustion chamber A-23.

[0034] To supply fuel, the throttling assembly A-15 may include a carburetor. Alternatively, a fuel valve A-63 may be provided for supplying fuel. Fuel valve A-63 may, for example, supply fuel to the interior of the crankcase A-24. Alternatively, a fuel valve A-63' may be provided, which supplies fuel to the intake passage A-14.

[0035] The working apparatus A-1 includes a control device A-10. The control device A-10 is used to operate fuel valves A-63 and A-63'. In particular, the control device A-10 determines the opening time and opening duration of fuel valves A-63 and A-63' and operates the fuel valves A-63 and A-63' accordingly.

[0036] The throttling assembly A-15 includes a base A-36. An intake passage section A-37 of the intake passage A-14 is constructed within the base A-36. The base A-36 is, in particular, a metal casting. An air control element A-20 is supported within an air passage section A-75. Figure A-2 In the arrangement shown, the air passage section A-75 is constructed within a separate body of the throttling assembly A-15.

[0037] The accompanying drawings show an advantageous embodiment in which an intake passage section A-37 and an air passage section A-75 are constructed within a base A-36. The base A-36 is a one-piece construction, and particularly a casting. This one-piece design results in a simplified construction.

[0038] like Figure A-3 As shown, the position of air control element A-20 is connected to the position of throttling element A-16 via connecting device A-58. Therefore, in this embodiment, throttling shaft A-17 and air control shaft A-21 are on one side of base A-36 (where...) Figure A-3(As shown on the left) are connected to each other. A connecting device A-58 is provided to connect the throttle shaft A-17 and the air control shaft A-21. The air control shaft A-21 is preloaded by an air closing spring A-64 in the direction toward the closed position of the air control element A-20. The air closing spring A-64 is constructed as a torsion spring. The air closing spring A-64 extends about the end of the air control shaft A-21 that extends from the base A-36. A connecting element A-65 is fixed at this end of the air control shaft A-21. The connecting element A-65 can be constructed, for example, as a lever or a disc.

[0039] exist Figure A-3 The end section of the invisible throttle shaft A-17 is provided with a connecting element A-59, which can be constructed, for example, as a disc or lever. Connecting elements A-59 and A-65 are connected via a connecting rod A-66. The air control shaft A-21 is pivotally supported about a rotation axis A-55. The throttle shaft A-17 is pivotally supported about a rotation axis A-54. The connecting rod A-66 is spaced apart from the rotation axis A-54 of the throttle shaft A-17 and the rotation axis A-55 of the air control shaft A-21 and connected to connecting elements A-65 and A-59. In particular, connecting element A-59 is anti-rotationally connected to the throttle shaft A-17. Connecting element A-65 is anti-rotationally connected, particularly to the air control shaft A-21.

[0040] like Figure A-4 As shown, in this embodiment, the connecting element A-65 is constructed as a lever. In this embodiment, the connecting element A-59 is constructed as a disc having multiple openings A-84.

[0041] like Figure A-3 and A-4 As shown, the throttling assembly A-15 has an opening spring A-41. The opening spring A-41 preloads the throttling shaft A-17 in the direction toward the fully open position of the throttling element A-16. The opening spring A-41 is constructed as a torsion spring. The opening spring A-41 extends about the rotation axis A-54 of the throttling shaft A-17 and is arranged outside the base A-36. The first end A-71 of the opening spring A-41 is connected to the connecting element A-59. For this purpose, the first end A-71 is engaged in one of the openings A-84. By appropriately selecting one of the openings A-84, the tolerance of the opening spring A-41 can be compensated in a simple manner. The second end A-72 of the opening spring A-41 is particularly supported at the base A-36, as... Figure A-6 As shown.

[0042] A housing A-57 is constructed on the side of the base A-36 opposite to the connecting device A-58. Figure A-3As shown in the diagram, housing A-57 is defined by housing cover A-60 and cover element A-48. In this embodiment, housing cover A-60 and base A-36 are integrally constructed. A motor A-45 is arranged on the side of housing A-57 opposite to base A-36. Motor A-45 is used to move throttling element A-16 in the closing direction, thereby reducing the free flow cross-section in intake passage section A-37. Motor A-45 constitutes the actuator of speed limiting device A-100. Figure A-5 ).

[0043] To allow operator control of the throttling element A-16, a transfer device A-38 is provided, which transfers... Figure A-3 The position of the operating element A-5, shown only partially, is transmitted to the rotational position of the throttle shaft A-17. The transmission device A-38 includes a transmission rod A-39.

[0044] like Figure A-5 As shown, the transmission rod A-39 has a first end A-61 held at the operating element A-5. The transmission rod A-39 also has a second end A-62 held at the throttle lever A-49.

[0045] Operating element A-5 has an operating section A-2, which preferably extends from the housing of the working instrument A-1, and the operator can operate operating element A-5 from this operating section. In this embodiment, operating element A-5 is pivotally supported about a pivot axis A-73. The operator can operate the operating section A-2 in the direction of arrow A-67. Thus, operating element A-5 pivots about its pivot axis A-73 and moves the first end A-61 of the transmission rod A-39 in the direction of arrow A-68. Figure A-5 In the view shown, arrow A-68 points downwards. The transmission rod A-39 is rigid. Movement of the first end A-61 along the direction of arrow A-68 causes movement of the second end A-62 along the direction of arrow A-69. Arrow A-69 in... Figure A-5 The middle point also points downwards. The engagement of the second end A-62 of the transmission rod A-39 with the throttle lever A-49—when the motor A-45 is not acting on this assembly—causes the throttle element A-16 to move in the opening direction A-42. Figure A-5 In this configuration, throttling element A-16 is positioned in the closed position A-85. When operating element A-5 is not operated by the operator, throttling element A-16 occupies the closed position A-85. Air control element A-20 is located in the closed position A-104.

[0046] The movement of the throttling element A-16 in the opening direction A-42—after overcoming the free travel A-ε, which will be described in detail below—causes the air control element A-20 to move in the opening direction A-86 due to the connecting device A-58. In this embodiment, the opening direction A-86 points in the same direction as the opening direction A-42 of the throttling element A-16.

[0047] The movement of the throttle element A-16 in the opening direction A-42 causes the intake passage A-14 ( Figure A-2 The increase in the free flow cross-section of the air control element in the opening direction A-86 causes the air passage A-13 ( Figure A-2 The increase in the free flow cross section of ).

[0048] Figure A-6 A view of the connecting device A-58 is shown. According to... Figure A-6 In this embodiment, the connecting element A-65 at the air control shaft A-21 differs from the aforementioned figures in that it is constructed as a disc having multiple openings A-99 for engaging the air closing spring A-64. According to... Figure A-6 The alternative design of the implementation scheme may correspond to the design of the aforementioned figures.

[0049] like Figure A-6 As shown, connecting element A-59 has an elongated hole A-87 into which connecting rod A-66 is engaged. If throttling element A-16 is adjusted in the opening direction A-42, connecting element A-59, which is anti-rotatably connected to throttling shaft A-17, rotates accordingly. Due to the elongated hole A-87, connecting element A-59 rotates without driving connecting rod A-66. Therefore, in its movement from the closed position A-85, connecting rod A-66 initially does not transmit the movement of throttling element A-16 to connecting element A-65 and air control element A-20. This corresponds to the operation of the operating section A-2 of operating element A-5 by the operator.

[0050] The connecting rod A-66 particularly has a pin-shaped portion A-103 that extends into an elongated hole A-87 and moves within the elongated hole A-87 during the movement of the connecting element A-59. The throttling element A-16 can move with a free stroke A-ε from the closed position A-85 toward the fully open position A-106. Figure A-14 The movement of the throttle element A-16 is adjusted in the direction of opening without transmitting the movement of the throttle element A-16 to the air control element A-20 via the connecting device A-58. The air control element A-20 is held at least in its closed position A-104 until the throttle element A-16 has been adjusted from its closed position A-85 in the opening direction A-42 with a free stroke A-ε. In particular, the free stroke A-ε is at most 30°. In particular, the free stroke A-ε is at least 15°. However, a smaller free stroke A-ε may also be advantageous.

[0051] Not only motor A-45 but also operating element A-5 can act on throttle shaft A-17. Operating element A-5 acts on throttle shaft A-17 in the opening direction A-42 via throttle lever A-49. Motor A-45 acts on throttle shaft A-17 in the closing direction A-44. This is in Figures A-7 to A-9 It is shown in detail in the text.

[0052] like Figure A-7 As shown, a throttle lever A-49 is fixed to a support shaft A-76, which is rotatably supported within a housing A-57. The throttle lever A-49 is located outside the housing A-57. The support shaft A-76 passes through an opening A-88 in the housing A-57. A seal A-77 is arranged in the opening A-88, sealing the interior of the housing A-57 relative to the environment. The support shaft A-76 and the seal A-77... Figure A-4 This is also visible in the perspective view, where housing A-57 is shown open. Seal A-77 can be constructed, for example, as a shaft seal or an O-ring. Figure A-7 As shown, a seal A-78 is arranged between the housing cover A-60 and the cover element A-48 of the housing A-57. The seal A-78 can be constructed separately from the housing components of the housing A-57. The seal A-78 can be constructed, for example, as a felt element, paper seal, profiled ring, sealing cord, or O-ring. In an alternative design, the seal A-78 can be molded onto the housing cover A-60 or the cover element A-48 of the housing A-57. The seal A-78 can be, for example, a liquid seal, preferably constructed of silicone. In another alternative construction, the housing cover A-60 and the cover element A-48 of the housing A-57 can be sealed together (e.g., welded) without the seal being inserted. The housing cover A-60 and the cover element A-48 can be sealed together, for example, by hot gas welding or friction welding.

[0053] The housing A-60 and the base A-36 of the throttling assembly A-15 are of one-piece construction. This is in Figure A-8 It can also be identified, especially in the middle.

[0054] like Figure A-7 As shown, support shaft A-76 is rotatably supported about axis A-79. A transmission mechanism A-56 is arranged on the outer periphery of support shaft A-76. Figure A-8 The drive wheel A-74 is connected to the support shaft A-76 in a rotation-resistant manner. For this purpose, the support shaft A-76 has a non-circular cross-section, such as... Figure A-4As shown. The external teeth A-95 of the drive wheel A-74 extend only a portion of the axial length of the drive wheel A-74. In the length section where the external teeth are not located, the closing spring A-43 extends at the outer periphery of the drive wheel A-74. The closing spring A-43 reacts to the throttle lever A-49 in the direction of arrow A-69 ( Figure A-5 The movement of the throttling element A-16. If the operating element A-5 is not operated by the operator, the closing spring A-43 will return the throttling element A-16 to its original position. Figure A-5 and A-7 The closed position A-85 is shown in the diagram. The opening spring A-41 and closing spring A-43 are designed such that the torque applied to the throttle shaft A-17 by the closing spring A-43 in the closing direction A-44 is greater than the torque applied by the opening spring A-41 in the opening direction A-42. Therefore, when the assembly is not operated, the throttle shaft A-17 is adjusted to the closed position A-85 by the closing spring A-43.

[0055] Figure A-8 The arrangement in a sectioning plane is shown, which includes the axis A-79 of the drive wheel A-74 and the axis of rotation A-54 of the throttle shaft A-17. (See diagram) Figure A-8 As shown, a journal A-70 is coaxially constructed at the base A-36 with the throttling shaft A-17, extending into the cavity of the housing A-57. Journal A-70... Figure A-4 As also shown in the diagram. A drive element A-46 is rotatably supported on journal A-70, as... Figure A-8 As shown. The drive component A-46 carries the external toothed portion A-94 on a portion of its periphery, the external toothed portion... Figure A-9 Also shown in the diagram. The external tooth A-94 of the drive component A-46 engages with the external tooth A-95 of the transmission wheel A-74, as shown in the diagram. Figure A-9 As shown, external gears A-94 and A-95 constitute transmission mechanism A-56. In this embodiment, transmission mechanism A-56 is a single-stage spur gear transmission mechanism. Other designs for transmission mechanism A-56 are also possible.

[0056] In this embodiment, motor A-45 has a driven shaft A-50 that can act on throttle shaft A-17 via connecting element A-89. Housing A-57 has an opening A-53 through which the drive connection between motor A-45 and throttle shaft A-17 passes. In this embodiment, driven shaft A-50 extends through opening A-53. However, other designs can also be advantageous. The housing of motor A-45 is sealed to housing A-57 outside opening A-53. Since the moving parts extend through opening A-53 arranged inside the seal, sealing of the moving parts is not required. Figure A-8 As shown, in this embodiment, a seal A-83 is arranged between the cover plate element A-48 and the motor A-45. The seal A-83... Figure A-4 As also shown in the diagram. In this embodiment, seal A-83 is an O-ring. Alternatively, seal A-83 can be constructed as a felt element, paper seal, shaped ring, or sealing cord, for example. In alternative designs, seal A-83 can be molded onto the cover element A-48 of housing A-57 or the housing of motor A-45. Seal A-83 can be a liquid seal, preferably made of silicone. Seal A-83 prevents contaminants from entering housing A-57 and prevents lubricant (especially grease) from flowing out of housing A-57. If the working instrument is a cutting machine, seal A-83 particularly prevents mineral dust and water from entering housing A-57.

[0057] Thanks to seals A-78, A-83, and A-77, the interior of housing A-57 is completely sealed relative to the environment.

[0058] like Figure A-8 As also shown, the opening spring A-41 is arranged on the outer periphery of the support element A-97, which is supported on the throttle shaft A-17.

[0059] like Figure A-9 As shown, along the direction of arrow A-69, between support shaft A-76 and drive wheel A-74 (see also...) Figure A-5 During movement, it drives component A-46 to move in the opening direction A-42. For example... Figure A-8 As shown, the throttle shaft A-17 carries a connecting member A-80. The connecting member A-80 includes a stop portion A-81 that extends into an opening A-96 in the drive member A-46. The opening A-96 and the stop portion A-81 are arranged in the opening A-96... Figure A-9 It is shown in the sectional view. Figure A-9 and A-10 In the diagram, the unoperated position of the connecting member A-80 is shown by a dashed line. In this position, the stop portion A-81' abuts against the stop element A-40 of the driving member A-46. In this embodiment, the stop element A-40 is formed by the end face of the opening A-96. Other designs of the stop element A-40 and the stop portion A-81 can also be advantageous. If the driving member A-46 is operated in the opening direction A-42, the stop element A-40 drives the throttle shaft A-17 in the opening direction A-42 via the stop portion A-81.

[0060] Therefore, the throttle lever A-49 acts on the throttle shaft A-17 via the transmission mechanism A-56. In this embodiment, the transmission mechanism A-56 has a transmission ratio of A-1. However, other transmission ratios may also be advantageous.

[0061] like Figure A-8 and A-12As shown, the connecting member A-80 has a stop A-82 extending toward the cover element A-48. The stop A-82 cooperates with the connecting element A-89, which is configured for connection to the driven shaft A-50 of the motor A-45. This is in Figure A-10 As shown in the figure. Motor A-45 is shown only schematically and can have any conventional design. When motor A-45 is operated accordingly, driven shaft A-50 ( Figure A-8 In the closing direction A-44 ( Figure A-10 The connecting element A-89 rotates about the rotation axis A-54 of the throttle shaft A-17 in the closed direction A-44. The connecting element A-89 drives the stop portion A-82 of the connecting member A-80 in the closed direction A-44. Due to the slender design of the opening A-96 as an elongated hole extending about the rotation axis A-54, the stop portion A-81 can move relative to the driving member A-46 in the closed direction A-44. Even though the operator manipulates the operating element A-5 and the driving member A-46 has moved to the position for fully opening the throttle element A-16, the connecting member A-80 can still be moved by the motor A-45, causing the throttle element A-16 to adjust in the closed direction A-44. This reduces the free flow cross-section of the intake passage A-14.

[0062] When the throttling element A-16 is open, that is, when the stop parts A-81 and A-82 are in position Figure A-9 and A-10 When the position is shown in solid line, it is possible to adjust the throttling element A-16 by motor A-45. When the throttling element A-16 is closed or only partially open, motor A-45 only moves connecting element A-89 relative to connecting member A-80. The starting point for adjustment of the throttling element A-16 by motor A-45 in the closing direction A-44 can be structurally predetermined through the appropriate design of connecting element A-89.

[0063] like Figure A-10 As shown, two stops A-91 and A-92 are provided at housing A-57, which define the end position of connecting element A-89. Figure A-10 The arrangement of connecting element A-89 at stop A-92 is shown, which defines the fully open position. Connecting element A-89 can be adjusted in the closing direction A-44 until it abuts against another stop A-91. Stops A-91 and A-92 define the maximum adjustment stroke by which motor A-45 can close throttling element A-16.

[0064] Figure A-11An alternative design for connecting element A-89 is shown. In this embodiment, connecting element A-89 has a flange A-93 that cooperates with stops A-91 and A-92, thus determining the maximum adjustment stroke for connecting element A-89.

[0065] like Figure A-11 As also shown, connecting arms A-47 are arranged at the cover element A-48 of the throttling assembly A-15, and the motor A-45 is fixed to the base A-36 via these connecting arms through the cover element A-48. This effectively captures the relatively large weight of the motor A-45.

[0066] like Figure A-8 As shown, the throttle shaft A-17 has a first end section A-51 and a second end section A-52. The first end section A-51 extends into the housing A-57. The second end section A-52 extends from the base A-36. End sections A-51 and A-52 extend from the base A-36 on opposite sides of the intake passage section A-37. A connecting member A-80 is fixed at the first end section A-51. The operator acts on the first end section A-51 via a transmission device A-38, a throttle lever A-49, a transmission mechanism A-56, a drive member A-46 with a stop element A-40, and a connecting member A-80. A motor A-45 also acts on the first end section A-51. A closing spring A-43 preloads the drive wheel A-74 and acts on the first end section A-51 via the transmission mechanism A-56. The opening spring A-41 acts on the second end section A-52. The second end section A-52 acts on the connecting device A-58. Figure A-7 ).

[0067] like Figure A-8 As also shown, the driven shaft A-50 of motor A-45 is arranged coaxially with the throttle shaft A-17. The throttle lever A-49 is pivotally supported about axis A-79. The rotation axis A-54 of throttle shaft A-17 and the throttle lever A-49 about its pivotally supported axis A-79 are spaced apart by a distance a. The rotation axis A-54 and axis A-79 extend parallel to each other. In this embodiment, transmission mechanism A-56 is constructed as a single stage, and the two gears of transmission mechanism A-56 are respectively coaxially aligned on one of the axes. Figure A-8 As also shown, the transmission mechanism A-56 is also arranged in the sealed housing A-57.

[0068] Figures A-13 to A-15 The operation of the throttling assembly A-15 is illustrated schematically. Figure A-15 In the diagram, throttle element A-16 is shown in the closed position A-85. In the closed position A-85, throttle element A-16 is specifically positioned against the idle stop (not shown). Opening spring A-41 ( Figure A-8Preload the throttling element A-16 in the opening direction A-42, and close the spring A-43 ( Figure A-8 Pre-tighten the throttling element A-16 in the closed direction A-44, as follows: Figure A-13 As shown schematically in the diagram.

[0069] Stop A-82 ( Figure A-10 In this position, it is not engaged with the connecting element A-89, and therefore does not act on the throttling element A-16. The stop portion A-82 is located... Figure A-10 The position shown by the dashed line is A-82'.

[0070] like Figure A-13 As shown, when the throttling element A-16 is in the closed position, the air control element A-20 is in its closed position A-104.

[0071] Figure A-14 The diagram schematically shows the position of the operating element A-5 when the operator manipulates it. The operator moves the element via the transmission device A-38 and the drive mechanism A-56. Figure A-8 This causes the throttle shaft A-17 and throttle element A-16 to move in the opening direction A-42. The operator overcomes the force of the closing spring A-43 by manipulating the operating element A-5 in the opening direction A-42 to adjust the throttle element A-16 in that direction. Figure A-14 The image shows the position A-105 of the throttling element A-16 corresponding to the no-load state. The throttling element A-16 occupies position A-105 when the tool of the working instrument A-1 is not engaged with the workpiece and the operator manipulates the operating element A-5 (e.g., fully manipulates it).

[0072] To limit the rotational speed, motor A-45 causes drive component A-46 ( Figure A-9 The speed is adjusted in the closed direction A-44 until it corresponds to the desired speed under no-load conditions, especially to the desired maximum speed of the internal combustion engine A-11. For this purpose, the speed limiting device A-100 controls the motor A-45 via the control device A-10, causing the motor A-45 to move the driven shaft A-50 ( Figure A-8 The motor A-45 rotates in the closed direction A-44. The motor A-45 is connected to the connecting element A-89 ( Figure A-9 and A-10 This causes the connecting part A-80 with the stop part A-82 to move in the closing direction A-44. Figure A-9This arrangement is shown before motor A-45 becomes active. If motor A-45 now moves connecting member A-80 in the closed direction A-44 via stop A-82, stop A-81 moves in opening A-96. The operator can continue to fully manipulate operating element A-5, thereby maintaining the position of drive member A-46 with stop element A-40. Motor A-45 acts directly on throttle shaft A-17 via connecting element A-89 and connecting member A-80, adjusting throttle element A-16 in the closed direction A-44. Here, connecting member A-80 is adjusted relative to drive member A-46, such as... Figure A-15 As illustrated schematically, in the no-load state, the cutting disc A-7 is not engaged with the workpiece. The operator maintains the control element A-5. To limit the rotational speed, the speed limiting device A-100 intervenes and causes the throttling element A-16 to close by manipulating the motor A-45. If the speed drops too much, the throttling element A-16 is subsequently reopened by adjusting the motor A-45 in the opposite direction. By adjusting accordingly, the position of the throttling element A-16 is set, thereby setting the desired rotational speed. If the desired rotational speed for the no-load state has been set, the throttling element A-16 is in position A-105. The no-load state is a quasi-steady state. As long as the environmental conditions do not change, the speed limiting device A-100 does not change the position of the throttling element A-16. The idle stroke A-ε is designed such that the throttling element A-16, in the no-load, quasi-steady state, adjusts to its maximum idle stroke A-ε from the closed position A-85 in the direction toward the fully open position A-106. Fully open position A-106 Figure A-14 It is drawn with a dashed line.

[0073] In position A-105, the throttling element A-16 is adjusted relative to the closed position A-85 in the opening direction A-42 to adjust the angle A-δ. Here, the adjustment angle A-δ is the maximum adjustment angle A-δ that can be set in the working instrument A-1 under no-load conditions according to environmental conditions. The adjustment angle A-δ is coordinated with the idle stroke A-ε. The adjustment angle A-δ corresponds at most to the idle stroke A-ε. In particular, the idle stroke A-ε is at least 2° larger than the adjustment angle A-δ, and especially at least 3° larger.

[0074] When the throttle element A-16 is in position A-105, the air control element A-20 is in the closed position A-104. The adjustment angle A-δ of the throttle element A-16 corresponds at most to the free stroke A-ε. Therefore, the adjustment of the throttle element A-16 from position A-105 along the closed direction A-44 only causes a change in the free flow cross-section of the intake passage A-14, and does not cause a change in the free flow cross-section of the air passage A-13.

[0075] Figure A-15The arrangement is shown when the throttle element A-16 is adjusted from the fully closed position A-85 beyond the empty stroke A-ε. When adjusted beyond the empty stroke A-ε, the air control element A-20 is driven via the connecting device A-58 and adjusts together with the throttle element A-16.

[0076] Figures A-16 to A-18 An alternative embodiment of the arrangement is shown. In this embodiment, the opening spring A-41 and the closing spring A-43 are arranged coaxially with the rotation axis A-54 of the throttle shaft A-17. The closing spring A-43 is arranged outside the housing A-57. The driving member A-46 is supported on the throttle shaft A-17. The motor A-45 acts on the connecting member A-80 through the transmission mechanism A-90, which is configured as a two-stage spur gear transmission mechanism in this embodiment, and the connecting member itself acts on the driving member A-46. According to Figures A-16 to A-18 The arrangement functions are as described with reference to the aforementioned figures.

[0077] Figure A-17 The arrangement is shown when the operator manipulates operating element A-5 and throttling element A-16 is fully open. Figure A-18 In the middle, the motor A-45 is relative to Figure A-17 The position of the connecting member A-80 has been adjusted, thus adjusting the throttle shaft A-17 and closing the throttle element A-16. Here, the transmission wheel A-98 of the transmission mechanism A-90 has moved the connecting member A-80.

[0078] The present invention also relates to a throttling assembly of the type described in the preamble of claim 20, and a handheld working device having a throttling assembly of the type described in the preamble of claim 36.

[0079] DE 37 11 779 A1 discloses a throttle valve that can be mechanically and electrically controlled. The mechanical control presets the maximum open position of the throttle valve. Relative to this position, the electrical control can further close the throttle valve.

[0080] This invention aims to describe a throttling component of this type with a simple and robust construction. Another objective of this invention is to describe a handheld working device with an advantageous construction.

[0081] Regarding the throttling component, this task is solved by a throttling component having the features of claim 20. Regarding the handheld working instrument, this task is solved by a handheld working instrument having the features of claim 36.

[0082] To achieve a simple construction of the throttling assembly, the stop element is configured at the rotatably supported drive member. To ensure that the function of this arrangement is achieved even when used in environments subject to dirt loads (such as those found in handheld working tools such as cutters, motor saws, or the like), the drive member is configured to be arranged in a housing sealed relative to the environment.

[0083] In particular, the transmission device includes a shaft that enters the housing, wherein the shaft is sealed by a seal. Adjustment movements applied by the operator at the operating element are transmitted via this shaft. Sealing the shaft is simple and feasible due to its rotational movement. Complex sealing of the translational movement components of the transmission device can be avoided.

[0084] In particular, the motor is sealed at the opening of the housing. This protects the opening and any components extending through it from contamination. Components extending through the opening, especially those driven by the motor, such as the driven shaft, are protected from contamination. For motor-driven components, direct seals are not provided. This avoids sealing moving parts and reduces wear on sealing elements. The seal also protects the driven shaft of the motor and the inlet where it enters the motor housing from contamination.

[0085] The stop element can be adjusted by the operator overcoming the force of the closing spring via the transmission device. Preferably, the throttling assembly is designed such that, when the transmission device is in an inactive state, the torque applied to the throttling shaft by the closing spring is greater than the torque applied to the throttling shaft by the opening spring. This ensures that, when the transmission device is in an inactive state, i.e., when the operator is not operating the transmission device, the throttling element is closed by the closing spring.

[0086] Because the closing spring exerts a greater torque, especially on the throttling shaft, than the opening spring, the closing spring is particularly large. To achieve a small structural space in the housing and thus a compact overall arrangement, the closing spring is specifically positioned outside the housing. In particular, the closing spring extends helically about the rotation axis of the driving element. Here, the rotation axis of the driving element corresponds specifically to the rotation axis of the throttling element.

[0087] If the housing is defined by a base and at least one cover element, then the arrangement has a simple construction. To seal the housing, one or more seals are arranged, particularly between the base and the cover element. Shafts or similar objects extending to the outside are also securely supported within the housing.

[0088] A simple and compact structure is obtained if the throttle shaft has two end sections extending on opposite sides of the intake passage section. Here, at least one of the end sections extends from the base. Specifically, the end section extends from the base into the housing. Specifically, the motor and transmission device act on the throttle shaft at the first end section. Opening and closing springs act on the throttle shaft, specifically at different end sections. Specifically, the closing spring acts on the end section where the stop element of the throttle shaft acts. In an alternative embodiment, the opening spring can be arranged to act on the end section where the stop element of the throttle shaft acts.

[0089] The arrangement of the closing spring outside the housing is particularly advantageous when the closing spring is arranged coaxially with the rotation axis of the driving element, and especially with the rotation axis of the throttling element. In an alternative embodiment, the closing spring can be arranged helically about an axis that is spaced apart from the rotation axis of the throttling shaft. In this case, an arrangement of the closing spring inside the housing can also be advantageous.

[0090] In one implementation variant, the drive element is supported on the end section of the throttle shaft extending from the base. This results in a simple and compact construction.

[0091] To achieve good support for the drive component, in an alternative embodiment, the stop element is specifically positioned at the base. An intake passage section is constructed within the base. This results in a smaller tolerance between the position of the throttling element and the drive component.

[0092] In particular, the transmission device includes a pressure-resistant transmission rod that engages with a throttling lever connected to a drive element, located outside the housing. Here, the throttling lever is anti-rotatably connected to the drive element and pivotable thereto about the same axis. In an alternative embodiment, the throttling lever is pivotally supported about a rotational axis, which is spaced from the axis of the throttling shaft. In this embodiment, the driven shaft of the motor is particularly arranged coaxially with the throttling shaft.

[0093] Specifically, the transmission device is configured to include a transmission mechanism, particularly a spur gear transmission mechanism. This is especially configured such that when the throttle lever is pivotally supported about a rotational axis, the rotational axis is spaced from the axis of the throttle shaft. If the throttle lever is pivotally supported about the axis of the throttle shaft, then the motor is particularly configured to be connected to the throttle shaft via a transmission mechanism, particularly a spur gear transmission mechanism. Here, the motor is particularly arranged within a base. The motor housing is constructed from the base. This results in a simple and compact construction.

[0094] The transmission mechanism is housed in a sealed housing. This protects the transmission mechanism from contamination.

[0095] For handheld working instruments having at least one tool and a drive motor for driving that tool, it is particularly advantageous to arrange the drive motor as a two-stroke engine operating with scavenging preload, the engine having an intake passage and an air passage and having a throttling assembly. An air control element is provided, which is pivotally supported in the air passage by an air control shaft. The position of the air control shaft is connected, in particular, to the position of the throttling shaft via a coupling device. The motor and the coupling device act on the throttling shaft, particularly at different end sections of the throttling shaft.

[0096] In particular, the throttle shaft has a connecting element constructed to resist rotation with the throttle shaft, through which the position of the air control shaft is connected to the position of the throttle shaft. The opening spring is supported at one end at the connecting element and at the other end at the base. This results in a simple and compact construction and a space-saving arrangement of the opening spring.

[0097] The embodiments of the present invention will be described below with reference to the accompanying drawings. Wherein: Figure B-1 A schematic side view of a handheld working instrument is shown; Figure B-2 A schematic diagram of a two-stroke engine that utilizes scavenging pre-compression is shown. Figure B-3 Displayed for the corresponding Figure B-2 Side view of the throttle assembly of a two-stroke engine; Figure B-4 Showing Figure B-3 An exploded perspective view of the components of the throttling assembly in the diagram; Figure B-5 A perspective view of the throttling component is displayed; Figure B-6 Showing along Figure B-3 A side view of an alternative implementation of the throttling assembly connection device, pointing in the direction of arrow VI; Figure B-7 A cross-sectional view of the throttling component is shown; Figures B-8 to B-10 Partial cross-sectional views of the throttling assembly in different cutting planes are shown; Figure B-11 A perspective view showing the throttling assembly with the motor removed; Figure B-12 The corresponding connection element with additional removal for the motor is shown. Figure B-11 A partial view; Figures B-13 to B-15 A schematic diagram showing the function of the throttling component is provided. Figure B-16 A cross-sectional view of an alternative implementation of the throttling component is shown; Figure B-17 and Figure B-18 This shows the removal of the cover plate element at different locations on the transfer device. Figure B-16 A partial perspective view of the throttling component in the image.

[0098] Figure B-1 An embodiment of a handheld working tool B-1 is schematically shown. In this embodiment, the working tool B-1 is a motorized saw. The working tool B-1 is particularly portable and handheld during operation. The working tool B-1 has a rear handle B-3 and a handle tube B-4. An operating element B-5 and a locking element B-6 for the operating element B-5 are arranged at the rear handle B-3. The working tool B-1 has a saw chain B-8 as a tool, which is driven around a guide rail B-7. A drive motor B-11 is used to drive the saw chain B-8. In this embodiment, the drive motor B-11 is a two-stroke engine. The drive motor B-11 is preferably a single-cylinder engine. In this embodiment, the drive motor B-11 is a two-stroke engine that operates using scavenging air pre-compression. The drive motor B-11 is particularly a hybrid lubrication engine, especially a two-stroke engine or a hybrid lubrication four-stroke engine. In this embodiment, the drive motor B-11 is started by hand. A starter handle B-9 is used for this. The working instrument B-1 has a hand guard bow-shaped part B-10, which is specifically used to trigger a braking device (not shown) for the saw chain B-8.

[0099] The drive motor B-11 has an air filter B-12 through which air is drawn in during operation. An air passage B-13 and an intake passage B-14 are used to supply air. It can be configured that both air passage B-13 and intake passage B-14 supply clean air. Alternatively, it can be configured to supply fuel to the intake passage B-14, such that a fuel / air mixture is supplied via the intake passage B-14.

[0100] However, it is also possible to configure an alternative design for the drive motor B-11, particularly a design without the air passage B-13.

[0101] Figure B-2 The drive motor B-11 is shown in a schematic cross-sectional view. (As shown...) Figure B-2As shown, the drive motor B-11 has a throttling assembly B-15 for controlling the amount of air supplied. In an embodiment, the throttling assembly B-15 includes a throttling element B-16 for controlling the amount of air flowing through the intake passage B-14. The throttling assembly B-15 also has an air control element B-20 for controlling the amount of air flowing through the air passage B-13. In an embodiment, a choke element B-18 is arranged upstream of the throttling element B-16. In an alternative embodiment, the choke element B-18 may be omitted or otherwise designed. In an embodiment, the throttling element B-16, the choke element B-18, and the air control element B-20 are each pivotally supported. The throttling element B-16 has a throttling shaft B-17 for this purpose. The choke element B-18 is pivotally supported by a choke shaft B-19. The air control element B-20 is supported by an air control shaft B-21. In this embodiment, the throttling element B-16, the damper element B-18, and the air control element B-20 are configured as valves. However, they can also be configured in another way, for example as rollers with openings extending perpendicular to the axis of rotation. Alternatively, the drive motor B-11 can be configured without the damper element B-18.

[0102] The drive motor B-11 includes a cylinder B-22, within which a combustion chamber B-23 is constructed. A piston B-25 is reciprocally supported within the cylinder B-22. The piston B-25 drives a crankshaft B-27, rotatably supported in a crankcase B-24, via a connecting rod B-26. The crankshaft B-27... Figure B-2 The image is shown schematically only. The crankshaft B-27 is rotatably supported about the axis of rotation B-28.

[0103] exist Figure B-2 In the region of bottom dead center of piston B-25 shown, the interior of crankcase B-24 is connected to combustion chamber B-23 via overflow passage B-29. Overflow passage B-29 opens into combustion chamber B-23 through overflow window B-30. Overflow window B-30 is controlled by piston B-25. Spark plug B-34 extends into combustion chamber B-23 to ignite the fuel / air mixture there. Outlet B-35 exits combustion chamber B-23, and this outlet is also controlled by piston B-25.

[0104] Intake passage B-14 opens into the bore of cylinder B-22 via intake passage inlet B-32. Intake passage inlet B-32 is also controlled by piston B-25 and connects to the inner cavity of crankcase B-24 in the region of piston B-25 at top dead center. Air passage B-13 opens into the bore of cylinder B-22 via one or more air inlets B-33. Piston B-25 has one or more piston recesses B-31 in its piston skirt. In the region of piston B-25 at top dead center, piston recesses B-31 connect air inlets B-33 to one or more overflow windows B-30. Air can thus be pre-positioned in overflow passage B-29 via air passage B-13, and this air is used to flush combustion chamber B-23.

[0105] To supply fuel, the throttling assembly B-15 may include a carburetor. Alternatively, a fuel valve B-63 may be provided for supplying fuel. The fuel valve B-63 may, for example, supply fuel to the interior of the crankcase B-24. Alternatively, a fuel valve B-63' may be provided to supply fuel to the intake passage B-14.

[0106] The throttling assembly B-15 includes a base B-36. An intake passage section B-37 of the intake passage B-14 is constructed within the base B-36. The base B-36 is, in particular, a metal casting. Figure B-2 In the arrangement shown, the air control element B-20 is supported in the air passage section B-75, which is constructed in a separate body of the throttling assembly B-15.

[0107] Another figure shows an embodiment in which an intake passage section B-37 and an air passage section B-75 are constructed within a substrate B-36. The substrate B-36 is constructed as a single piece, and particularly as a casting. This single-piece design results in a simple construction.

[0108] like Figure B-3 As shown, the throttle shaft B-17 and the air control shaft B-21 are on one side of the base B-36 (this side is on...). Figure B-3 (As shown on the left) are connected to each other. A connecting device B-58 is provided to connect the throttle shaft B-17 and the air control shaft B-21. The air control shaft B-21 is preloaded by an air closing spring B-64 in the direction toward the closed position of the air control element B-20. The air closing spring B-64 is constructed as a torsion spring. The air closing spring B-64 extends about the end of the air control shaft B-21 that extends from the base B-36. A connecting element B-65 is fixed at the end of the air control shaft B-21. The connecting element B-65 can be constructed, for example, as a lever or a disc.

[0109] The throttle shaft B-17 in Figure B-3The invisible end section is provided with a connecting element B-59, which can be configured as, for example, a disc or a lever. Connecting elements B-59 and B-65 are connected via a connecting rod B-66. The air control shaft B-21 is pivotally supported about a rotation axis B-55. The throttle shaft B-17 is pivotally supported about a rotation axis B-54. The connecting rod B-66 is spaced apart from the rotation axis B-54 of the throttle shaft B-17 and the rotation axis B-55 of the air control shaft B-21 and connected to connecting elements B-65 and B-59. In particular, connecting element B-59 is anti-rotationally connected to the throttle shaft B-17. Connecting element B-65 is anti-rotationally connected, particularly to the air control shaft B-21.

[0110] like Figure B-4 As shown, in one embodiment, connecting element B-65 is constructed as a lever. In another embodiment, connecting element B-59 is constructed as a disc having a plurality of openings B-84.

[0111] like Figure B-3 and B-4 As shown, the throttling assembly B-15 has an opening spring B-41. The opening spring B-41 preloads the throttling shaft B-17 in the direction toward the fully open position of the throttling element B-16. The opening spring B-41 is constructed as a torsion spring. The opening spring B-41 extends about the rotation axis B-54 of the throttling shaft B-17 and is arranged outside the base B-36. The first end B-71 of the opening spring B-41 is connected to the connecting element B-59. For this purpose, the first end B-71 is engaged in one of the openings B-84. By appropriately selecting one of the openings B-84, the tolerance of the opening spring B-41 can be compensated in a simple manner. The second end B-72 of the opening spring B-41 is particularly supported at the base B-36, as... Figure B-6 As shown.

[0112] A housing B-57 is constructed on the side of the base B-36 opposite to the connecting device B-58. The housing B-57 is defined by a housing cover B-60 and a cover element B-48. In an embodiment, the housing cover B-60 and the base B-36 are constructed as a single piece. A motor B-45 is arranged on the side of the housing B-57 opposite to the base B-36. This motor is used to move the throttling element B-16 in the closing direction, thereby reducing the free flow cross-section in the intake passage section B-37.

[0113] To allow operator control of the throttling element B-16, a transfer device B-38 is provided, which transfers... Figure B-3 The position of the operating element B-5, which is only partially shown, is transmitted to the rotational position of the throttle shaft B-17. The transmission device B-38 includes the transmission rod B-39.

[0114] like Figure B-5 As shown, the transmission rod B-39 has a first end B-61, which is held at the operating element B-5. The transmission rod B-39 has a second end B-62, which is held at the throttle lever B-49.

[0115] Operating element B-5 has an operating section B-2, which preferably extends from the housing of the working instrument B-1, and the operator can operate operating element B-5 from this operating section. In an embodiment, operating element B-5 is pivotally supported about a pivot axis B-73. The operator can operate the operating section B-2 in the direction of arrow B-67. This pivots operating element B-5 about its pivot axis B-73 and moves the first end B-61 of the transmission rod B-39 in the direction of arrow B-68. Figure B-5 In the view shown, arrow B-68 points downwards. The transmission rod B-39 is rigid. Movement of the first end B-61 along the direction of arrow B-68 causes movement of the second end B-62 along the direction of arrow B-69. Arrow B-69 in... Figure B-5 The middle also points downwards. The engagement of the second end B-62 at the throttle lever B-49 causes the throttle element B-16 to move in the opening direction B-42 when the motor B-45 is not operated. Figure B-5 In this configuration, the throttling element B-16 is positioned in the closed position B-85. When the operating element B-5 is not operated by the operator, the throttling element B-16 occupies the closed position B-85.

[0116] The movement of the throttling element B-16 in the opening direction B-42 causes the air control element B-20 to move in the opening direction B-86 due to the connecting device B-58. In this embodiment, the opening direction B-86 is in the same direction as the opening direction B-42 of the throttling element B-16.

[0117] Figure B-6 A view of the connecting device B-58 is shown, in which, unlike the previous figures, the connecting element B-65 at the air control shaft B-21 is constructed as a disc with multiple openings for engaging the air closing spring B-64.

[0118] like Figure B-6 As shown, the connecting element B-59 has an elongated hole B-87 into which the connecting rod B-66 is engaged. If the throttling element B-16 is adjusted in the opening direction B-42, the connecting element B-59, which is anti-rotatably connected to the throttling shaft B-17, rotates accordingly. Due to the elongated hole B-87, the rotation of the connecting element B-59 does not drive the connecting rod B-66. Therefore, when moving from the closed position B-85, the connecting rod B-66 initially does not transmit the movement of the throttling element B-16 to the connecting element B-65 and the air control element B-20.

[0119] The connecting rod B-66 particularly features a pin-shaped portion B-103 that extends into an elongated hole B-87 and moves within the elongated hole B-87 during the movement of the connecting element B-59. The throttling element B-16 can travel via a free stroke B-ε from the closed position B-85 toward the fully open position B-106. Figure B-14 The direction of the throttling element B-16 is adjusted, and the movement of the throttling element B-16 is not transmitted to the air control element B-20 via the connecting device B-58. The air control element B-20 is held at least in its closed position B-104 until the throttling element B-16 is adjusted from its closed position B-85 with a free stroke B-ε along the opening direction B-42. In particular, the free stroke B-ε is at most 30°. It is particularly configured such that the free stroke B-ε is at least 15°. However, a smaller free stroke B-ε may also be configured.

[0120] like Figure B-7 As shown, a throttle lever B-49 is fixed to a support shaft B-76, which is rotatably supported within a housing B-57. The throttle lever B-49 is located outside the housing B-57. The support shaft B-76 extends through an opening B-88 in the housing. A seal B-77 is arranged in the opening B-88, sealing the interior of the housing B-57 relative to the environment. The support shaft B-76 and the seal B-77 are... Figure B-4 This is also visible in the perspective view, where housing B-57 is shown open. Seal B-77 can be configured as, for example, a shaft seal or an O-ring. Figure B-7 As shown, a seal B-78 is arranged between the housing cover B-60 and the cover element B-48 of the housing B-57. The seal B-78 can be constructed separately from the housing components of the housing B-57. The seal B-78 can be constructed, for example, as a felt element, paper seal, profiled ring, sealing cord, or O-ring. In an alternative design, the seal B-78 can be molded onto the housing cover B-60 or the cover element B-48 of the housing B-57. The seal B-78 can be, for example, a liquid seal, preferably made of silicone. In another alternative construction, the housing cover B-60 and the cover element B-48 of the housing B-57 can be sealed together without inserting a seal, for example, by welding. The housing cover B-60 and the cover element B-48 can be sealed together, for example, by hot gas welding or friction welding.

[0121] The housing B-60 and the base B-36 of the throttling assembly B-15 are constructed as a single piece. This is especially true in... Figure B-8 It is also recognizable in the middle.

[0122] like Figure B-7 As shown, support shaft B-76 is rotatably supported about axis B-79. A transmission mechanism B-56 ​​is arranged on the outer periphery of support shaft B-76. Figure B-8 The drive wheel B-74 is connected to the support shaft B-76 in a rotation-resistant manner. For this purpose, the support shaft B-76 has a non-circular cross-section, such as... Figure B-4 As shown. The external toothed portion B-95 of the drive wheel B-74 extends only along a portion of the axial length of the drive wheel B-74. In the length section where the external toothed portion is not located, the closing spring B-43 extends at the outer periphery of the drive wheel B-74. The closing spring B-43 reacts to the throttle lever B-49 along arrow B-69 ( Figure B-5 The movement is in the direction of ). If the operating element B-5 is not operated by the operator, the closing spring B-43 will return the throttling element B-16 to its original position. Figure B-5 and B-7 The closed position B-85 is shown. The opening spring B-41 and closing spring B-43 are designed such that the torque applied to the throttle shaft B-17 by the closing spring B-43 in the closing direction B-44 is greater than the torque applied by the opening spring B-41 in the opening direction B-42. Therefore, in the unoperated arrangement, the throttle shaft B-17 is adjusted to the closed position B-85 by the closing spring B-43.

[0123] Figure B-8 The arrangement is shown in a cross-section of the axis B-79 containing the drive wheel B-74 and the rotation axis B-54 containing the throttle shaft B-17. (As shown) Figure B-8 As shown, a support pin-shaped portion B-70 is coaxially constructed at the base B-36 with the throttling shaft B-17, and this support pin-shaped portion extends into the inner cavity of the housing B-57. The support pin-shaped portion B-70... Figure B-4 This is also shown in the image. For example... Figure B-8 As shown, a drive member B-46 is rotatably supported on a support pin-shaped portion B-70. The drive member B-46 carries an external toothed portion B-94 on a portion of its periphery. Figure B-9 The diagram also shows that the external toothed portion B-94 of the drive component B-46 engages with the external toothed portion B-95 of the transmission wheel B-74, as shown. Figure B-9 As shown. External gears B-94 and B-95 constitute transmission mechanism B-56. In this embodiment, transmission mechanism B-56 ​​is a single-stage spur gear transmission mechanism. Another design for transmission mechanism B-56 ​​is also possible.

[0124] In one embodiment, motor B-45 has a driven shaft B-50 that can act on throttle shaft B-17 via connecting element B-89. Housing B-57 has an opening B-53 through which the drive connection between motor B-45 and throttle shaft B-17 passes. In this embodiment, driven shaft B-50 extends through opening B-53. The housing of motor B-45 is sealingly connected to housing B-57 outside of opening B-53. Because the moving parts extend through opening B-53 arranged within a seal, sealing of the moving parts is not required. Figure B-8 As shown, in this embodiment, a seal B-83 is arranged between the cover element B-48 and the motor B-45. The seal B-83... Figure B-4 As also shown in the diagram. In an embodiment, seal B-83 is an O-ring. Seal B-83 can alternatively be constructed as a felt element, a paper seal, a shaped ring, or a sealing cord, for example. In an alternative design, seal B-83 can be molded onto the cover element B-48 of housing B-57 or onto the housing of motor B-45. Seal B-83 can be, in particular, a liquid seal, preferably made of silicone. Seal B-83 prevents contaminants from entering housing B-57 and lubricants (especially grease) from leaving housing B-57. If the working instrument is a cutting machine, seal B-83 particularly prevents mineral dust and water from entering housing B-57.

[0125] Thanks to seals B-78, B-83, and B-77, the interior of housing B-57 is completely sealed relative to the environment.

[0126] like Figure B-8 As also shown, the opening spring B-41 is arranged on the outer periphery of the support element B-97, which is supported on the throttle shaft B-17.

[0127] like Figure B-9 As shown, along arrow B-69 (see also) on support shaft B-76 and drive wheel B-74. Figure B-5 When the movement is in the direction of ), it drives component B-46 to move along the opening direction B-42. For example... Figure B-8 As shown, the throttle shaft B-17 carries the connecting member B-80. The connecting member B-80 includes a stop portion B-81 that extends into the opening B-96 of the drive member B-46. The arrangement of the opening B-96 and the stop portion B-81 within the opening B-96 is as follows: Figure B-9 Shown in the sectional view. Figure B-9 and B-10In the diagram, the unoperated position of the connecting member B-80 is shown by a dashed line. In this position, the stop portion B-81' abuts against the stop element B-40 of the driving member B-46. In this embodiment, the stop element B-40 is formed by the end face of the opening B-96. An alternative design for the stop element B-40 and the stop portion B-81 is also possible. If the driving member B-46 is operated in the opening direction B-42, the stop element B-40, via the stop portion B-81, drives the throttle shaft B-17 in the opening direction B-42.

[0128] Therefore, the throttle lever B-49 acts on the throttle shaft B-17 via the transmission mechanism B-56. In this embodiment, the transmission mechanism B-56 ​​has a transmission ratio of B-1. Another transmission ratio may also be provided.

[0129] like Figure B-8 and B-12 As shown, the connecting member B-80 has a stop portion B-82 pointing toward the cover plate element B-48. The stop portion B-82 cooperates with the connecting element B-89, which is configured for connecting the driven shaft B-50 of the motor B-45. This is in Figure B-10 The diagram shows motor B-45, which is only schematically shown and can have any conventional design. When operating motor B-45, the driven shaft B-50 (…) Figure B-8 ) along the closing direction B-44 ( Figure B-10 The connecting element B-89 is placed in a rotating position. Consequently, the connecting element B-89 rotates about the rotation axis B-54 of the throttling shaft B-17 in the closing direction B-44. The connecting element B-89 drives the stop portion B-82 of the connecting member B-80 in the closing direction B-44. Due to the slender design of the opening B-96 as an elongated hole extending about the rotation axis B-54, the stop portion B-81 can move relative to the driving member B-46 in the closing direction B-44. Even though the operator manipulates the operating element B-5 and the driving member B-46 has moved to the position for fully opening the throttling element B-16, the connecting member B-80 can still be moved by the motor B-45, causing the throttling element B-16 to adjust in the closing direction B-44.

[0130] When the throttling element B-16 is open, that is, when the stop parts B-81 and B-82 are in position... Figure B-9 and B-10 When the position is shown in solid line, the throttling element B-16 can be adjusted by motor B-45. When throttling element B-16 is closed or only partially open, motor B-45 only moves connecting element B-89 relative to connecting member B-80. The starting position of throttling element B-16 can be adjusted by motor B-45 along the closing direction B-44, and this can be structurally preset through the appropriate design of connecting element B-89.

[0131] like Figure B-10 As shown, two stops, B-91 and B-92, are provided at housing B-57, which define the end position of connecting element B-89. Figure B-10 The arrangement of connecting element B-89 at stop B-92 is shown, which defines the fully open position. Connecting element B-89 can be adjusted along the closing direction B-44 until it abuts against another stop B-91. Stops B-91 and B-92 define the maximum adjustment stroke by which motor B-45 can close throttling element B-16.

[0132] Figure B-11 An alternative design for the connecting element B-89 is shown. In this embodiment, the connecting element B-89 has a flange B-93 that cooperates with stops B-91 and B-92, thus determining the maximum adjustment stroke of the connecting element B-89.

[0133] like Figure B-11 As also shown, a connecting arm B-47 is arranged at the cover element B-48 of the throttling assembly B-15, and the motor B-45 is fixed to the base B-36 via the cover element B-48 using this connecting arm. This effectively captures the relatively large weight of the motor B-45.

[0134] like Figure B-8 As shown, the throttle shaft B-17 has a first end section B-51 and a second end section B-52. The first end section B-51 extends into the housing B-57. The second end section B-52 extends from the base B-36. End sections B-51 and B-52 extend from the base B-36 on opposite sides of the intake passage section B-37. A connecting member B-80 is fixed at the first end section B-51. The operator acts on the first end section B-51 via the transmission device B-38, the throttle lever B-49, the transmission mechanism B-56, the drive member B-46 with a stop element B-40, and the connecting member B-80. The motor B-45 also acts on the first end section B-51. A closing spring B-43 preloads the drive wheel B-74 and acts on the first end section B-51 via the transmission mechanism B-56. The opening spring B-41 acts on the second end section B-52. The second end section B-52 acts on the connecting device B-58. Figure B-7 )superior.

[0135] like Figure B-8As also shown, the driven shaft B-50 of motor B-45 is arranged coaxially with the throttle shaft B-17. The throttle lever B-49 is pivotally supported about axis B-79. The rotation axis B-54 of the throttle shaft B-17 and the throttle lever B-49 about its pivotally supported axis B-79 are spaced apart by a distance 'a'. The rotation axis B-54 and axis B-79 extend parallel to each other. In an embodiment, the transmission mechanism B-56 ​​is constructed as a single stage, and the two gears of the transmission mechanism B-56 ​​are respectively aligned coaxially with one of the axes. Figure B-8 As also shown, the transmission mechanism B-56 ​​is also arranged in the sealed housing B-57.

[0136] Figures B-13 to B-15 The operation of the throttling assembly B-15 is illustrated schematically. Figure B-15 In the diagram, the throttle element B-16 is shown in the closed position B-85. In the closed position B-85, the throttle element B-16 is particularly abutted against the idle stop (not shown). The opening spring B-41 (Fig. 8) preloads the throttle element B-16 in the opening direction B-42, and the closing spring B-43 ( Figure B-8 Pre-tighten the throttling element B-16 along the closing direction (B-44). Figure B-13 As shown schematically in the diagram.

[0137] Stop section B-82 ( Figure B-10 In this position, it is not engaged with the connecting element B-89, and therefore does not act on the throttling element B-16. The stop portion B-82 is located... Figure B-10 The position shown by the dashed line is B-82'.

[0138] like Figure B-13 As shown, with the throttling element B-16 in the closed position, the air control element B-20 is in its closed position B-104.

[0139] Figure B-14 The diagram schematically illustrates the position of the element B-5 when the operator manipulates it. The operator moves the element via the transmission device B-38 and the drive mechanism B-56. Figure B-8 This causes the throttle shaft B-17 and throttle element B-16 to move in the opening direction B-42. The operator's reaction force on the closing spring B-43 manipulates the operating element B-5 in the opening direction B-42, thereby adjusting the throttle element B-16 in the opening direction B-42. Figure B-14 The image shows the position B-105 of the throttling element B-16, which corresponds to the no-load state. The throttling element B-16 occupies position B-105 when the tool of the working instrument B-1 is not engaged with the workpiece and the operator manipulates (e.g., fully manipulates) the operating element B-5.

[0140] To limit the rotational speed, motor B-45 causes drive component B-46 ( Figure B-9 The rotational speed is adjusted along the closed direction B-44 until it corresponds to the desired speed under no-load conditions, particularly the desired maximum speed of the internal combustion engine B-11. To this end, the speed limiting device B-100 operates the motor B-45 via the control device B-10, causing the motor B-45 to drive the driven shaft B-50 (… Figure B-8 Motor B-45 rotates in the closed direction (B-44). Motor B-45 is connected to element B-89 (…). Figure B-9 and B-10 The connecting piece B-80 with the stop part B-82 is driven along the closing direction B-44. Figure B-9 This arrangement is shown before motor B-45 is activated. If motor B-45 now moves connecting member B-80 in the closing direction B-44 via stop B-82, stop B-81 moves in opening B-96. The operator can continue to keep operating element B-5 fully actuated, thereby maintaining the position of drive member B-46 with stop element B-40. Motor B-45 acts directly on throttle shaft B-17 via connecting element B-89 and connecting member B-80, adjusting throttle element B-16 in the closing direction B-44. Here, connecting member B-80 is adjusted relative to drive member B-46, as... Figure B-15 As illustrated schematically, in the no-load state, the cutting disc B-7 is not engaged with the workpiece. The operator keeps the operating element B-5 manipulated. To limit the rotational speed, the speed limiting device B-100 intervenes and causes the throttling element B-16 to close by manipulating the motor B-45. If the speed drops too much, the throttling element B-16 is subsequently reopened by adjusting the motor B-45 in the opposite direction. By adjusting accordingly, the position of the throttling element B-16 is adjusted, thereby adjusting the desired rotational speed. If the desired rotational speed for the no-load state is being adjusted, the throttling element B-16 is in position B-105. The no-load state is a quasi-steady state. As long as the environmental conditions do not change, the speed limiting device B-100 does not change the position of the throttling element B-16. The free travel B-ε is designed so that the throttling element B-16, in the no-load quasi-steady state, can be adjusted to its maximum extent from the closed position B-85 toward the fully open position B-106. The fully open position B-106 is... Figure B-14 It is drawn with a dashed line in the middle.

[0141] In position B-105, the throttling element B-16 adjusts the adjustment angle B-δ relative to the closed position B-85 along the opening direction B-42. The adjustment angle B-δ here is the maximum adjustment angle B-δ, which may be adjusted in the working instrument B-1 under no-load conditions depending on environmental conditions. The adjustment angle B-δ is coordinated with the idle stroke B-ε. The adjustment angle B-δ corresponds at most to the idle stroke B-ε. In particular, the idle stroke B-ε is at least 2° larger than the adjustment angle B-δ, and especially at least 3° larger.

[0142] When the throttle element B-16 is in position B-105, the air control element B-20 is in the closed position B-104. The adjustment angle B-δ of the throttle element B-16 corresponds to the maximum free stroke B-ε. The adjustment of the throttle element B-16 from position B-105 along the closed direction B-44 causes only a change in the free flow cross-section of the intake passage B-14, and not a change in the free flow cross-section of the air passage B-13.

[0143] Figure B-15 The arrangement is shown when the throttle element B-16 is adjusted from the fully closed position B-85 beyond the free travel B-ε. When adjusted beyond the free travel B-ε, the air control element B-20 is driven via the connecting device B-58 and adjusted together with the throttle element B-16.

[0144] Figures B-16 to B-18 An alternative embodiment of this arrangement is shown. In this embodiment, the opening spring B-41 and the closing spring B-43 are arranged coaxially with the rotation axis B-54 of the throttle shaft B-17. The closing spring B-43 is arranged outside the housing B-57. The drive member B-46 is supported on the throttle shaft B-17. The motor B-45 acts on the connecting member B-80 via the transmission mechanism B-90 (which is configured as a two-stage spur gear transmission mechanism in this embodiment), and the connecting member itself acts on the drive member B-46. According to Figures B-16 to B-18 The arrangement functions in accordance with the functions described in the foregoing figures.

[0145] Figure B-17 The arrangement is shown when the operator manipulates operating element B-5 and throttling element B-16 is fully open. Figure B-18 In the middle, the motor B-45 is relative to Figure B-17 The position adjustment of the connecting member B-80 thereby adjusts the throttle shaft B-17 and closes the throttle element B-16. Here, the drive wheel B-98 of the transmission mechanism B-90 moves the connecting member B-80.

[0146] The present invention also relates to a method for operating an internal combustion engine of the type described in the preamble of claim 38, a method for operating an internal combustion engine of the type described in the preamble of claim 40, and an internal combustion engine.

[0147] As known from DE 196 09 536 A1, the speed of an internal combustion engine is limited by adjusting a throttling element via a drive motor. A sensor is provided to detect the current speed. The throttling element is adjusted in a closed manner based on the sensor signal.

[0148] This invention aims to describe a method for operating an internal combustion engine, thereby achieving improved motor operating behavior. Another objective of this invention is to describe an internal combustion engine with improved operating behavior.

[0149] Regarding this method, the task is solved by a method having the features of claim 38. Regarding this method, the task is also solved by a method having the features of claim 40. Regarding the internal combustion engine, the task is solved by an internal combustion engine having the features of claim 49.

[0150] It has been shown that the adjustment of the throttling element should be performed in a relatively slow manner, because otherwise the adjustment system may tend to oscillate. Internal combustion engines typically have a maximum speed (at which the control device intervenes to limit the engine speed) and an intervention speed (the speed should not rise above this intervention speed during operation to avoid damage to the engine). Depending on the boundary conditions, the change in speed caused by the relatively slow adjustment of the throttling element may be too small to prevent the speed from rising above the intervention speed. The present invention is now configured to operate the throttling element in a different manner along the closed direction. This depends on whether a first or second limit value of the speed standard is exceeded. It is configured such that, if the first limit value of the speed standard is exceeded, the actuator is operated along the closed direction of the throttling element, taking into account the actual speed of the internal combustion engine as an input variable. If the second limit value of the speed standard is exceeded, the actuator is configured to be operated in the closed direction of the throttling element within at least a portion of the adjustment angle range, regardless of the actual speed of the internal combustion engine as an input variable.

[0151] By manipulating the actuator along the closing direction of the throttling element when the engine speed exceeds the second limit of the standard speed, without considering the actual speed of the internal combustion engine as an input variable, relatively rapid adjustment of the throttling element along the closing direction can be achieved. This avoids oscillations in the regulating loop when adjusting to the maximum speed in a simple way, and also prevents the speed from rising above the intervention speed in a simple way. In particular, it eliminates indirect consideration of the actual speed of the internal combustion engine, such as by considering the behavior of speed-related controls (e.g., spark cut-off).

[0152] The speed standard is specifically the speed of an internal combustion engine, particularly the actual speed or the average of actual speeds (e.g., the average speed over multiple motor cycles), or the speed gradient of the internal combustion engine (e.g., the speed gradient of actual speeds over a preset time period). Other speed standards can also be set.

[0153] In particular, the first speed standard is the first speed of the internal combustion engine, and the second speed standard is the second speed of the internal combustion engine. The second speed is significantly higher than the first speed.

[0154] The actual speed is specifically the current speed of the internal combustion engine. The actual speed can be determined here in a suitable manner based on a portion of one cycle of the internal combustion engine, one cycle of the internal combustion engine, or multiple cycles of the internal combustion engine.

[0155] Specifically, when the first limit value of the speed standard is exceeded, the actuator is operated along the closing direction of the throttle element according to the first control method. When the second limit value of the speed standard is exceeded, the actuator is operated at least within a portion of the adjustment angle range in the closing direction of the throttle element according to the second control method, regardless of the actual speed of the internal combustion engine as an input variable.

[0156] In particular, when the actuator is operated according to the second control method, the throttling element adjusts faster in the closed direction than when the actuator is operated according to the first control method. Operating the actuator faster in the closed direction according to the second control method represents an independent inventive concept that solves the proposed task regardless of whether the actual engine speed is considered in the first and / or second control methods. Operating the actuator faster in the closed direction according to the second control method can be achieved, for example, by not considering the actual engine speed as an input variable when operating the actuator. Alternatively, different adjustment speeds can be achieved through different timing stages in the control method, through preset different adjustment speeds, or through other suitable measures.

[0157] During a load reduction from full load to 30% below full load, if the actuator is controlled according to the second control method, the throttling element is adjusted along the closed direction, particularly within a partial angle range of at least 5°, and especially at least 25°. In the case of a significant load reduction and control according to the second control method, the throttling element is thus adjusted within a relatively large partial angle range. This allows for a rapid and effective speed reduction in a simple manner.

[0158] Specifically, the first and second control methods are configured to be executed independently of the position of the throttling element. Therefore, the position of the throttling element is neither related to the first nor the second control method, but rather to the input variable used for control. Here, the control method can be either a control method or a regulation method. A regulation method is a control method in which the output variable is fed back and continuously influences itself in the regulation loop. Conversely, no feedback occurs in a control method.

[0159] The actuator can be configured to operate the throttling element only in the closing direction of the throttling element. Alternatively, the actuator can be configured to operate the throttling element in both the closing and opening directions of the throttling element.

[0160] In particular, to limit the speed of the internal combustion engine, the actuator is operated according to both a first control method and a second control method. Therefore, both the first and second control methods are preferably used to limit the speed of the internal combustion engine. Alternatively or additionally, the first and second control methods can be configured for other purposes, such as preventing the internal combustion engine from remaining within the engagement speed range of the centrifugal clutch and thereby avoiding high clutch wear.

[0161] The actuator is specifically controlled by a control device to close the throttling element until at least one stop criterion is reached. In particular, the at least one stop criterion is also a speed criterion. However, it can also be configured that the stop criterion is another criterion, such as the position reached by the throttling element or the elapsed time of a preset period. The stop criterion used to control the actuator according to the first control method is particularly exceeding a second speed criterion. An alternative or supplementary stop criterion after exceeding a first limit value of the speed criterion is particularly below the first speed criterion. A stop criterion after exceeding a second limit value of the speed criterion is particularly below the second limit value of the second speed criterion.

[0162] The internal combustion engine can be configured to have a device for identifying the position of the throttle element. The position of the throttle element is determined particularly during engine operation. Specifically, after exceeding a second speed limit, the throttle element can be adjusted within a preset angle range or until a stop standard is reached. Alternatively, it can be configured to adjust the throttle element to a preset position when the second speed limit is exceeded. This preset position is particularly the position of the throttle element stored during normal operation of the internal combustion engine, during which the first or second speed standard is not exceeded. Normal operation is, in particular, a type of operation of the internal combustion engine in which less than 50% of the maximum load is applied. Specifically, when the second speed limit is exceeded, the throttle element is adjusted to the preset position. Therefore, the preset position is the position to which the throttle element is adjusted during normal operation. However, it can also be configured to have the preset position permanently stored in the control device, or to be stored in the control device according to other standards.

[0163] In particular, the control device manipulates the ignition system of the internal combustion engine in such a way that, after exceeding a second speed threshold, the ignition timing is retarded until a stop threshold is reached. Alternatively or additionally, the control device can manipulate the ignition system of the internal combustion engine such that, after exceeding a second speed threshold, ignition is interrupted within a single engine cycle until a stop threshold is reached. The stop threshold could be, for example, below the second speed threshold or below a certain speed. Because the control device manipulates both the ignition system and the throttling element to reduce the engine speed, it prevents the engine speed from rising above the intervention speed.

[0164] In one implementation variation, the first and second speed standards are the maximum speed and the intervention speed. Here, the maximum speed is particularly less than the intervention speed. Alternatively, the speed standard can be a speed gradient. A combination of speed and speed gradient can also be set as the speed standard. If the speed standard is the maximum speed and the intervention speed, the intervention speed can be more than 2,000 U / min higher than the maximum speed, and more particularly less than 1,000 U / min higher. Especially when the intervention speed and the maximum speed have a relatively small gap between them (e.g., a gap of less than 2,000 U / min), a second control method is provided that enables rapid adjustment of the throttling element and thereby rapid reduction of speed.

[0165] In particular, for an internal combustion engine, the control device of the internal combustion engine stores a first control method for an actuator, the first control method being configured to control the actuator to close a throttling element when a first limit value of a speed standard is exceeded, and the control device stores a second control method, the second control method being configured to control the actuator such that the throttling element is adjusted in the closing direction within at least a portion of the adjustment angle range without considering the actual speed of the internal combustion engine as an input variable, and the control device being configured to control the actuator according to the second control method when a second limit value of a speed standard is exceeded.

[0166] When the actuator includes an electric motor, the throttling element can be easily controlled and adjusted.

[0167] Advantageously, the internal combustion engine includes a fuel valve for supplying fuel, which is operated by a control device.

[0168] In particular, internal combustion engines have exhaust mufflers with catalytic converters. Especially in the case of exhaust mufflers with catalytic converters, it is essential to ensure effective speed limiting to prevent the catalytic converter from overheating and being damaged during operation. This can be achieved in a simple way by setting two different control methods for limiting the speed.

[0169] Embodiments of the present invention are described below with reference to the accompanying drawings. Wherein: Figure C-1 A schematic diagram of a handheld working tool with an internal combustion engine is shown. Figure C-2 Showing from Figure C-1 A schematic diagram of the internal combustion engine of a working machine. Figure C-3 A schematic diagram of the throttling element in the intake passage is shown. Figure C-4 A schematic diagram of the first control method is shown. Figure C-5 Shown in accordance with Figure C-4The diagram illustrates an exemplary curve of the load at the internal combustion engine and related possible curves of the speed and throttle element position when the first control method is performed. Figure C-6 Showing for Figure C-5 The curve showing the location of the throttling element is illustrated by a schematic diagram of the air mass flow rate of an internal combustion engine as a function of engine speed. Figure C-7 A schematic diagram of the second control method is shown. Figure C-8 A schematic diagram showing exemplary curves of load at the internal combustion engine and associated possible speed and throttling element positions is provided when the engine is operated according to the first and second control methods. Figure C-9 Showing for Figure C-8 The curve showing the location of the throttling element is illustrated by a schematic example diagram of how the air mass flow rate of an internal combustion engine varies with engine speed. Figure C-10 A flowchart is shown for a method of controlling an internal combustion engine.

[0170] Figure C-1 The C-25 handheld working instrument is shown schematically. Figure C-1 In the image, the handheld working tool C-25 is shown as a motorized saw. However, the handheld working tool C-25 could also be other working tools, such as a cutter, brush cutter, lawn mower, or the like. The handheld working tool C-25 has a housing C-26 in which an internal combustion engine C-1 is arranged. To guide the working tool C-25, a handle C-27 with operating elements C-28 is mounted on the housing C-26, particularly via damping elements. In particular, one of the operating elements C-28 is a throttle pedal, which is actuated to a throttle lever C-30 via a control device C-29. The throttle lever C-30 is particularly connected to a throttle element C-17. Through this operating element C-28 and the control device C-29, the throttle element C-17 ( Figure C-2 The fuel supply can be adjusted by the operator. In this embodiment, a carburetor C-15 is provided as a fuel supply device, and a throttling element C-17 is arranged in the carburetor C-15. However, another type of fuel supply can also be provided.

[0171] The internal combustion engine C-1 has an intake passage C-14. A throttling element C-17 is arranged in a section of the intake passage C-14. The operator can thus control the free flow cross-section of the intake passage C-14 via an operating element C-28.

[0172] The internal combustion engine C-1 has a cylinder C-2, in which a piston C-5 is reciprocally supported. The piston C-5 is confined within a combustion chamber C-3 constructed in cylinder C-2. The piston C-5 drives, via a connecting rod C-6, a crankshaft C-7 pivotally supported in a crankcase C-4 about a rotational axis C-8. The rotational axis C-8... Figure C-2 As shown in the diagram, intake passage C-14 enters at cylinder C-2 via inlet opening C-9, which is controlled by piston C-5. Inlet opening C-9 opens towards crankcase C-4 in the region of piston C-5 at top dead center. Exit opening C-10 exits from combustion chamber C-3, which is constructed in the cylinder bore and controlled by piston C-5.

[0173] like Figure C-1 As shown, an exit channel C-33 is connected to an exit opening C-10, which leads into an exhaust muffler C-23. In an embodiment, the exhaust muffler C-23 has a catalyst C-24 for exhaust gas aftertreatment. The catalyst C-24 has at least a partial catalytic coating. Alternatively, or added to, a particulate filter (e.g., in the form of a mesh with an intermediate coating or no coating) may be provided instead of the catalyst C-24.

[0174] Figure C-2 An internal combustion engine C-1 is shown in detail. At least one overflow passage C-12 leads into the combustion chamber C-3 via at least one overflow window C-13. The overflow passage C-12 connects the crankcase C-4 to the combustion chamber C-3 in the region of the piston C-5's bottom dead center. The internal combustion engine C-1 draws in air through an air filter C-16 and an intake passage C-14. A section of the intake passage C-14 is constructed within a carburetor C-15. Alternatively, another type of fuel supply device can be provided instead of the carburetor C-15. In an embodiment, the carburetor C-15 includes a valve C-19 for controlling the amount of fuel supplied. The valve C-19 is connected to a fuel opening C-18 that leads into the intake passage C-14. It can be configured such that the entire amount of fuel supplied to the intake passage C-14 is controlled by the valve C-19. Alternatively, only a portion of the amount of fuel supplied can be controlled by the valve C-19. The valve C-19 is, in particular, a solenoid valve.

[0175] Valve C-19 is controlled by control device C-20. The internal combustion engine C-1 has a spark plug C-11 extending into the combustion chamber C-3. The energy required to generate a spark at spark plug C-11 is produced by ignition device C-22. Control device C-20 may be integrated into ignition device C-22 or constructed separately from it.

[0176] During the operation of the internal combustion engine C-1, air is drawn into the intake passage C-14 through the air filter C-16 in the region of top dead center of piston C-5. In an embodiment, fuel is supplied to the air in the carburetor C-15. The fuel / air mixture thus formed is drawn into the cavity of crankcase C-4 through inlet opening C-9. During the downward stroke of piston C-5, the fuel / air mixture is compressed in crankcase C-4. Piston C-5 opens at least one overflow window C-13 during its downward stroke. Once overflow window C-13 is open, the fuel / air mixture flows from crankcase C-4 into combustion chamber C-3. The fuel / air mixture in combustion chamber C-3 is compressed by the upward-moving piston C-5. In the region of top dead center of piston C-5, the mixture is ignited by spark plug C-11. Subsequent combustion accelerates piston C-5 in the direction toward crankcase C-4. Once the exit opening C-10 is opened by the downward-moving piston C-5, the exhaust gas flows from the combustion chamber C-3 through the exit passage C-33 into the exhaust muffler C-23 and then into the environment.

[0177] In this embodiment, the internal combustion engine C-1 is a two-stroke engine having only an intake passage. Alternatively, the internal combustion engine C-1 may be a two-stroke engine operating with scavenging pre-compression, which, in addition to the intake passage, also has at least one air passage for supplying scavenging pre-compressed air, or its intake passage may be divided into at least one air passage and a mixture passage downstream of the throttling element C-17.

[0178] To influence the rotational speed of the internal combustion engine C-1, the internal combustion engine C-1 has an actuator C-21 that can adjust the position of the throttling element C-17. The actuator C-21 can pivot the throttling element C-17 at least in the closed direction C-32. When the throttling element C-17 pivots in the closed direction C-32, the free flow cross-section of the intake passage C-14 decreases. In an embodiment, the actuator C-21 has an electric motor C-31 to adjust the throttling element C-17. Additionally, the actuator C-21 can be configured to operate the throttling element C-17 in an opening direction C-34, opposite to the closed direction. When the throttling element C-17 pivots in the opening direction C-34, the free flow cross-section of the intake passage C-14 increases.

[0179] The control device C-20 stores a first control method C-41 and a second control method C-42, such as Figure C-2 As shown schematically in the diagram. Figure C-2The views shown are schematic and simplified. The separate display of the first control method C-41 and the second control method C-42 is merely to illustrate that the program code stored in the control device C-20 is configured to control the actuator C-21 according to the first control method C-41, and if control is not performed according to the first control method C-41, then control is performed according to the second control method C-42. However, the first control method C-41 and the second control method C-42 do not need to be stored spatially separate or separately from each other in the program code.

[0180] Figure C-3 The arrangement of the throttling element C-17 in the intake passage C-14 is shown in detail. Figure C-3 The position of the throttle element C-17 in the fully closed position is shown in solid line. The position γ of the throttle element C-17 is described here as a pivot angle from the fully open position of the throttle element C-17. The fully open position is shown in dashed line. From the closed position to the fully open position, the throttle element C-17 can be adjusted within the adjustment angle range C-α. Typically, the adjustment angle range C-α is less than 90° and, for example, about 75°. To achieve rapid closing of the throttle element C-17, it is preferable to close a partial angle range C-β of the throttle element according to the second control method C-42, which is at least 5°, and particularly at least C-25°. These partial angle ranges C-β here involve a load reduction from the maximum load C-Pmax to 30% below the maximum load C-Pmax. 30% of the maximum load C-Pmax can, for example, be the minimum load at the internal combustion engine C-1. Load reduction is particularly relevant when the tool of workpiece C-25 disengages from the workpiece from its maximum load, for example, when the saw chain of workpiece C-25 exits the cut from full load. After adjusting the partial angle range C-β from the fully open position, the position of the throttling element C-17 is... Figure C-3 The text is displayed using dashed lines.

[0181] Figure C-4The first control method C-41 is schematically shown. Control method C-41 has a reference variable Cw(t). In this embodiment, the reference variable Cw(t) is constant. In this embodiment, the reference variable Cw(t) is the maximum speed n1. Alternatively, the reference variable Cw(t) can also be another speed standard, such as a speed gradient. If the first limit value C-g1 of the speed standard is exceeded, the actuator C-21 is controlled according to the first control method C-41 and reacts to the deviation of the reference variable Cw(t) from its rated value. The adjustment deviation Ce(t) constitutes the input variable for the control device C-20. The adjustment deviation Ce(t) is determined as the difference between the reference variable Cw(t) and the speed Cn(t). Here, the speed Cn(t) corresponds to the actual speed Cn at each moment. Other influencing variables can also be considered to determine the adjustment deviation Ce(t). Here, control device C-20 determines the regulating variable Cu(t), for example, a portion of the regulating angle range C-α, specifically angle range C-β, around which the throttling element C-17 is adjusted. Then, the throttling element C-17 is adjusted within this portion of angle range C-β in the regulating object C-35. In the regulating object C-35, a disturbance variable Cd(t) may also be considered, such as changes in the load CP at the internal combustion engine C-1.

[0182] In particular, the throttling element C-17 along the closing direction C-32 ( Figure C-2 The speed is adjusted until a stopping criterion is found. The stopping criterion could be, for example, reaching the preset position C-γ1 of the throttle element C-17, completing adjustment within a preset partial angle range C-β, falling below the first limit value g1 of the speed standard, or exceeding the second limit value g2 of the speed standard. The output variable Cy(t) of the adjusted object C-35 is the adjusted variable, for example, the actual speed n of the internal combustion engine C-1. In the first control method C-41, the actual speed n of the internal combustion engine C-1 is considered as an input variable in the reference variable Cw(t), such as... Figure C-3 As shown, feedback of the actual rotational speed n occurs. Therefore, the first control method C-41 is an adjustment method.

[0183] Figure C-5 Shown in Figure C-5In the exemplary flow of the first control method C-41 shown, the curves depicting the actual rotational speed Cn, throttle angle C-α, and load CP changing with time Ct are shown. Specifically, the control method is activated when the actual rotational speed n exceeds the activation speed C-n3. Until time C-t1, as shown by curve C-38, the load CP is at its maximum load C-Pmax. At time C-t1, the load CP decreases from the maximum load C-Pmax to the load C-Pmin (in this embodiment, it decreases to the minimum load). As shown by curve C-37, the throttle element C-17 is fully open at time C-t1. The position of the throttle element C-17 is C-γ (…). Figure C-4 This corresponds to a pivot angle of 0° relative to the fully open position. The actual rotational speed Cn is lower than the first limit value C-g1 of the first rotational speed standard (in the embodiment, it is lower than the maximum rotational speed C-n1). The load drop at time C-t1 may be due, for example, to the removal of the saw chain of a motorized saw or the cutting disc of a cutter from the cut. This will cause the load CP to drop suddenly from the maximum load C-Pmax to the minimum load Pmin. This sudden load drop will cause the rotational speed to increase, as shown by curve C-36.

[0184] In the embodiment, the first limit value C-g1 of the first speed standard is lower than the high speed C-n1.

[0185] At time C-t2, the first speed standard C-g1 (the highest speed C-n1 in this embodiment) is exceeded. Subsequently, control device C-20 begins to operate actuator C-21 according to the first control method C-41 and closes throttling element C-17 according to curve C-37. Figure C-4 As shown, the actual engine speed n is taken into account here. Because the actual engine speed n is considered, the throttle element C-17 closes gradually and relatively slowly. The engine speed Cn(t) initially continues to rise until it reaches a plateau and begins to decline at time C-t3. The actual engine speed Cn reaches its maximum speed C-n1 at time t4. At any time t, the engine speed is below the intervention speed n2. The intervention speed n2 specifically refers to the speed at which the control device C-20 begins to retard the ignition timing of the spark plug C-11 and / or interrupts ignition in a single engine cycle to prevent further increases in engine speed.

[0186] In this embodiment, the first extreme limit value C-g1 and the second limit value g2 of the first speed standard are speed values, namely the maximum speed C-n1 and the intervention speed C-n2. If the extreme limit values ​​C-g1 and C-g2 are speed values, then the first extreme limit value C-g1 is particularly smaller than the second limit value C-g2. Alternatively, the speed standard can also be other values ​​derived from the speed, such as the speed gradient.

[0187] In particular, the actuator C-21 is not always activated. Specifically, the actuator C-21 is activated only within a preset speed limit range. Outside these speed limits, the position of the throttling element C-17 is determined solely by the operator via a preset position of the operating element C-28.

[0188] In this embodiment, the actuator C-21 is activated when the activation speed C-n3 is exceeded. Specifically, the actuator C-21 is deactivated when the speed is below the deactivation speed C-n4. The activation speed C-n3 and the deactivation speed C-n4 can be the same speed. If the first speed standard C-g1 is a speed, then the activation speed C-n3 and the deactivation speed C-n4 are particularly lower than the first speed standard C-g1 (particularly lower than the maximum speed C-n1). If the second speed standard C-g2 is a speed, then the activation speed C-n3 and the deactivation speed C-n4 are particularly lower than the second speed standard C-g2 (particularly lower than the intervention speed C-n2).

[0189] If the activation speed C-n3 and the deactivation speed C-n4 are different, then the activation speed C-n3 should be set to be greater than the deactivation speed C-n4. Instead of the activation speed C-n3 and the deactivation speed C-n4, other speed standards C-g3 and C-g4 used to control the activation and deactivation of the actuator C-21 can also be set.

[0190] Figure C-6 The curve showing the air mass flow rate m as a function of rotational speed Cn(t) is displayed. Curve C-39 shows the air mass flow rate m as a function of rotational speed Cn(t) under full load. Maximum power CL is output at a speed slightly below the maximum rotational speed n1. When the maximum rotational speed C-n1 is reached, control device C-20 begins to close throttling element C-17. As a result, the air mass flow rate m decreases along curve C-40. Rotational speed Cn remains below the intervention speed C-n2 and decreases to the maximum rotational speed C-n1 as the air mass flow rate m decreases. Once the maximum rotational speed C-n1 is reached, the first control method C-41 can be terminated. Alternatively, instead of reaching the maximum rotational speed C-n1, other stopping criteria can be used to terminate the first control method C-41. Other stopping criteria could be, for example, reaching a preset speed gradient or reaching another speed (e.g., below the intervention speed C-n2 or below the shutdown speed C-n4, which is below the maximum rotational speed C-n1). In this embodiment, the actuator C-21 is deactivated when the speed is below the deactivation speed C-n4 until the activation speed C-n3 is exceeded again.

[0191] If the rotational speed Cn(t) rises to the intervention speed C-n2, especially when the second control method C-42 is activated, such as Figure C-7The diagram illustrates this. The second control method C-42 causes the throttle element C-17 to close very quickly. Therefore, the second control method C-42 is configured not to use the actual engine speed Cn of the internal combustion engine C-1 as an input variable. Thus, the second control method C-42 is a control method. In the second control method C-42, the maximum engine speed C-n1 also constitutes the reference variable Cw(t). In the second control method, the reference variable Cw(t) can also be other speed standards.

[0192] The reference variable Cw(t) constitutes the input signal for control device C-20. Control device C-20 derives the adjustment variable Cu(t) from the reference variable Cw(t). The adjustment variable Cu(t) can be, for example, the angle to be adjusted of throttling element C-17, or the preset end position of throttling element C-17. Accordingly, throttling element C-17 is adjusted in controlled object C-43 (possibly taking into account other disturbance variables Cd(t), such as load changes). The output variable Cy(t) (i.e., the control variable) is not considered when determining the preset adjustment of throttling element C-17. No feedback is provided for the output variable Cy(t).

[0193] Figure C-8 and C-9 The resulting curves C-36 to C-39 are shown. The notation here is related to... Figure C-5 and C-6 Correspondingly, at the first time point C-t1, the load CP decreases from the maximum load C-Pmax to the minimum load C-Pmin, as shown by curve C-38. Subsequently, the actual speed Cn rises to the maximum speed C-n1. The maximum speed C-n1 is reached at the second time point t2. At this second time point C-t2, the control device C-20 begins to close the throttling element C-17 according to the first control method C-41. Since the closing movement of the throttling element C-17 is relatively slow, the actual speed n may rise further and reach the intervention speed C-n2 at time C-t3. Subsequently, the control device C-20 begins to close the throttling element C-17 according to the second control method C-42 without considering the actual speed Cn. Thus, the closing movement of the throttling element C-17 can be performed very quickly. When the actuator C-21 operates according to the second control method C-42, the speed at which the throttling element C-17 is closed is greater than the speed when operated according to the first control method C-41. In particular, when the actuator is operated according to the second control method C-42, the throttling element C-17 is closed at maximum speed.

[0194] like Figure C-8As clearly shown, when operating according to the second control method C-42 (i.e., between the third time t3 and the fourth time C-t4), the adjustment speed of the throttle element C-17 is significantly greater than that when operating according to the first control method C-41 (i.e., between the second time C-t2 and the third time C-t3). Due to the rapid closing of the throttle element C-17, the air mass flow rate m through the intake passage C-14 decreases sharply, and the engine speed Cn(t) cannot increase further. As support, the spark plug C-11 can be manipulated to retard the ignition timing or interrupt ignition in a single engine cycle, thereby additionally limiting the engine speed Cn(t).

[0195] At the fourth moment C-t4, the throttling element C-17 is adjusted to the preset position C-γ1, as follows: Figure C-8 As shown. At time C-t4, actuator C-21 terminates its operation according to the second control method C-42. Here, reaching a preset position or adjusting a preset portion of the angle range C-β of the adjustment angle range C-α can be the stopping criterion for the second control method C-42. Subsequently, in the embodiment, throttling element C-17 continues to be controlled according to the first control method C-41 until the stopping criterion for the first control method C-41 is reached. In the embodiment, this is when the actual rotational speed Cn drops to the maximum rotational speed n1 at the fifth time t5.

[0196] Figure C-9 Shown in accordance with Figure C-8 The method flow chart shows the air mass flow rate m. At the second time t2, the throttling element C-17 closes. Above the maximum speed n1, the air mass flow rate m no longer extends according to curve C-39, but decreases according to curve C-40. At the third time t3, the intervention speed n2 is reached, and the throttling element C-17 is closed very quickly until the fourth time t4. Thus, the actual speed n no longer increases. At the fourth time t4, the second control method C-42 ends. The throttling element C-17 remains closed until the fifth time t5, more precisely by controlling the actuator C-21 according to the first control method C-41, until the maximum speed n1 is reached. Here, the stopping criterion for the second control method C-42 is specifically chosen so that when the second control method C-42 ends, the throttling element C-17 is closed far enough that no further speed increase beyond the intervention speed C-n2 is made.

[0197] Figure C-10A flowchart of the method flow is shown. In method step C-51, it is checked whether the actual rotational speed Cn, rotational speed gradient C-Δn, or other rotational speed standard exceeds the limit value C-g1 of that rotational speed standard. If the limit value C-g1 is exceeded, in method step C-52, the control device C-20 begins to operate the actuator C-21 to close the throttling element C-17 according to the first control method C-41. During the execution of the first control method C-41, in method step C-53, it is continuously checked whether the actual rotational speed Cn, rotational speed gradient Δn, or other rotational speed standard drops below the first limit value C-g1. Once the actual rotational speed Cn or rotational speed gradient Δn drops below the first limit value C-g1, method step C-51 is implemented and it is checked whether the rotational speed Cn or rotational speed gradient C-Δn exceeds the first limit value C-g1 again.

[0198] In method step C-54 (which is performed when the rotational speed Cn or the rotational speed gradient C-Δn remains above the first limit value C-g1), it is checked whether the rotational speed n or the rotational speed gradient C-Δn exceeds the second limit value C-g2. If this is not the case, method step C-52 is performed, i.e., the first control method C-41 for controlling the actuator C-21. If the actual rotational speed Cn or the rotational speed gradient C-Δn rises above the second limit value C-g2, the second control method C-42 for controlling the actuator C-21 is performed in method step C-55, and the throttling element C-17 closes at its maximum speed. In method step C-56, it is checked whether a stopping criterion has been met, for example, whether the actual rotational speed n or the rotational speed gradient C-Δn has fallen below the second limit value C-g2 of the interventional rotational speed C-n2, or alternatively, whether the preset position of the throttling element C-17 has been reached, or whether the throttling element C-17 has been adjusted to a preset partial angle range C-β. If the stopping criteria are met, the method returns to method step C-51.

[0199] The present invention also relates to a method for operating an internal combustion engine of the type described in the preamble of claim 51, and a working apparatus having an internal combustion engine.

[0200] A working apparatus with a speed limiting device is known from US 2021 / 0254566 A1. To limit the speed, a control device acts on both an air control element and a throttling element. The throttling element and the air control element can be opened or closed by the control device according to the engine's operating point to regulate the desired speed.

[0201] This invention describes an improved method for operating an internal combustion engine, based on the objective of providing an improved working apparatus for an internal combustion engine.

[0202] Regarding the method, the task is solved by a method having the features of claim 51. Regarding the working apparatus, the task is solved by a working apparatus having the features of claim 55.

[0203] Such internal combustion engines can be used, for example, in handheld working instruments such as motorized saws, cutters, or the like. Speed ​​limiting is particularly activated when the load on the engine is low (e.g., when the tool driven by the internal combustion engine is not cutting) and the operator is fully actuating the control (e.g., the accelerator pedal). The actuator closes the throttle element relative to a position set by the operator to regulate the speed to the desired rated final speed. When the load received by the internal combustion engine increases (e.g., because the tool intrudes into the workpiece), the engine speed may drop below the rated final speed. The actuator will then reopen the throttle element as soon as the operator actuates the control accordingly. This is at least the case within a portion of the adjustment angle range. This portion of the angle range specifically includes at least one opening angle in which the throttle element is mostly or completely closed. By opening the throttle element, the engine speed should increase again.

[0204] If the throttle element is mostly closed, the internal combustion engine responds very sensitively to changes in the throttle element's opening angle. A mostly closed throttle element (i.e., a very small opening angle) is achieved at speeds close to the rated final speed, especially when the engine is receiving only a small load. This is particularly likely in handheld working tools, where the tool does not interfere with the workpiece and the operator has full control over the operating device (e.g., by fully depressing the accelerator pedal).

[0205] If the load received by the internal combustion engine increases from this state, the engine speed drops sharply, and the actuator reacts by adjusting the throttle element in the opening direction to increase the speed again. This is especially true as long as the opening angle of the throttle element remains below the throttle angle preset by the operator via the control device. If this adjustment of the throttle element is very slow, and at the same time the load on the internal combustion engine increases relatively strongly, the engine speed may experience an undesirable sharp drop. Such a sharp drop in speed is undesirable. A sharp drop in speed is particularly undesirable when the actuator is activated only in the speed range below the rated final speed, and the speed deviates from the actuator's activation range. This may cause the throttle element to be abruptly adjusted to a larger opening angle preset by the operator. The opening of the throttle element again leads to an increase in released power, followed by a sudden acceleration of the internal combustion engine and a return to the speed range activated by the actuator. This results in unstable operating behavior and strong speed fluctuations in the internal combustion engine.

[0206] The system is configured such that, when adjusted by the actuator in the opening direction, the adjustment speed of the throttling element below a first speed limit is at least twice the adjustment speed of the throttling element when adjusted by the actuator in the opening direction and above the first speed limit. Therefore, the present invention provides two different adjustment speeds for adjusting the throttling element when adjusted by the actuator in the opening direction. A lower first adjustment speed is set for adjusting the throttling element in the opening direction between the rated final speed and the first speed limit. A larger second adjustment speed is set below the first speed limit.

[0207] Below the first speed limit, the adjustment speed of the throttling element when adjusted by the actuator in the opening direction is 2 to 10 times that of the adjustment speed of the throttling element when adjusted by the actuator in the opening direction above the first speed limit. In particular, the adjustment speed below the first speed limit is 3 to 6 times that of the adjustment speed above the first speed limit.

[0208] Specifically, below the second speed limit, the actuator is inactive, thereby adjusting the throttling element to a position corresponding to the opening angle set by the operator via the control device, wherein the second speed limit is below the first speed limit. Therefore, below the second speed limit, no adjustment of the internal combustion engine speed by the actuator occurs. The set speed is derived, in particular, from the throttling element position set by the operator and the load present at the internal combustion engine. The first speed limit is particularly located 500 U / min to 3,000 U / min below the rated final speed of the internal combustion engine, especially 500 U / min to 2,000 U / min.

[0209] To control the actuators, an internal combustion engine has a control device. This control device is connected to a mechanism for detecting the engine's rotational speed. The control device can also control other components of the internal combustion engine, such as fuel valves, ignition devices, or the like. The control device can be connected to additional sensors, such as pressure sensors for detecting engine pressure (especially crankcase pressure), and / or temperature sensors for detecting engine temperature (e.g., crankcase temperature and / or ambient temperature). The rated final speed of the internal combustion engine is particularly the speed stored in the engine's control device.

[0210] This method is particularly suited for two-stroke engines. The internal combustion engine can be configured to have only a single intake passage. Alternatively, the internal combustion engine can be configured to have an additional intake passage besides the one with the throttling element, this additional intake passage being particularly configured to supply scavenging pre-compressed air to at least one overflow passage of the internal combustion engine.

[0211] Internal combustion engines, in particular, have a fuel supply device. This fuel supply device can be a carburetor. Fuel can be metered solely based on the negative pressure in the intake manifold. Alternatively, the carburetor can be configured to have a fuel valve, particularly a solenoid-operated valve. In a carburetor with a solenoid valve, the negative pressure in the intake manifold can also influence the amount of fuel supplied via the engine's control equipment.

[0212] Instead of a carburetor, fuel supply can also be achieved via a fuel valve, particularly an electromagnetically operated fuel valve. This fuel valve can supply fuel, for example, to the intake manifold, the crankcase interior, or one or more overflow passages of the internal combustion engine. This type of fuel valve is particularly suitable for operation at lower overpressures of less than 5 bar.

[0213] The throttling element can be configured as a throttling gate. Alternatively, the throttling element can also be a control roller. This is particularly useful when fuel is supplied via a carburetor constructed as a roller carburetor.

[0214] Internal combustion engines, especially drive motors in handheld, particularly portable, working tools. Internal combustion engines, especially drive motors in motorized saws, cutters, or the like.

[0215] The working apparatus is configured to have an internal combustion engine, which is constructed to be operated according to the method according to the invention. The working apparatus is particularly a cutting machine.

[0216] Actuators include, in particular, electric motors. In particular, electric motors are configured to pivot the throttling element in both the opening and closing directions.

[0217] In particular, the throttling element is a throttling gate. Especially in the case of a throttling gate, even with a small pivoting of the throttling element, the change in the free flow cross-section is already relatively large within the region of the closed position of the throttling element. Therefore, especially for throttling elements constructed as throttling gates, a slow adjustment of the position is provided within the region of the closed position and / or within the region of fewer open positions.

[0218] The embodiments of the present invention will be described below with reference to the accompanying drawings. Wherein: Figure D-1 A schematic cross-sectional view of the working instrument is shown. Figure D-2 A schematic diagram of an internal combustion engine is shown. Figure D-3 A schematic diagram of a throttling element arranged in an intake passage is shown, along with exemplary possible angular positions of the throttling element. Figure D-4 The diagram illustrates, schematically and exemplarily, the curves of rotational speed, load, and the opening angle of the throttling element over time when the method is performed. Figure D-5A flowchart of the method is shown.

[0219] Figure D-1 The work instrument D-225 is shown schematically. In this embodiment, the work instrument D-225 is a motorized saw. The work instrument D-225 can also be other work instruments, such as a cutter or the like. In this embodiment, the work instrument D-225 has a guide rail D-235 around which a saw chain D-236 is arranged. The saw chain D-236 is the tool of the work instrument D-225. If the work instrument D-225 is a cutter, then the tool is a rotary-driven cutting disc.

[0220] The working instrument D-225 has a housing D-226, on which at least one handle is fixed. In an embodiment, a handle D-227 configured as a rear handle is provided. Additionally, an upper handle and / or handle tube may be provided. An operating element D-228 is provided at the handle D-227. The working instrument D-225 has an internal combustion engine D-201. The internal combustion engine D-201 is particularly arranged within the housing D-226.

[0221] The operating element D-228 is constructed as an accelerator pedal and forms part of the control device D-229 for controlling the internal combustion engine D-201.

[0222] In this embodiment, the internal combustion engine D-201 is configured as a two-stroke engine. The internal combustion engine D-201 has a cylinder D-202, in which a combustion chamber D-203 is constructed. A piston D-205 is reciprocally supported in cylinder D-202. The piston D-205 drives a crankshaft D-207 via a connecting rod D-206. The crankshaft D-207 is supported in a crankcase D-204 of the internal combustion engine D-201 in a manner rotatable about a rotational axis D-208.

[0223] The internal combustion engine D-201 has an inlet opening D-209 leading to the crankcase D-204. The inlet opening D-209 is controlled primarily by the piston D-205. The internal combustion engine D-201 has an exit opening D-210 leading to the combustion chamber D-203. The exit opening D-210 is also controlled primarily by the piston D-205. The spark plug D-211 extends into the combustion chamber D-203. An overflow passage D-212 opens into the combustion chamber D-203 via an overflow window D-213. The overflow passage D-212 fluidly connects the internal space of the crankcase D-204 with the combustion chamber D-203 in the region of the piston D-205's bottom dead center. The bottom dead center of the piston D-205 is the terminal position of the piston D-205 near the crankcase D-204.

[0224] An exit passage D-233 is connected to the exit opening D-210, which leads to the exhaust muffler D-223. The exhaust muffler D-223 may have a catalytic converter D-224. Alternatively, the exhaust muffler D-223 may not have a catalytic converter D-224.

[0225] The intake passage D-214 enters through the inlet opening D-209. The free-flow cross-section of the intake passage D-214 is determined by the opening angle γ of the throttling element D-217.

[0226] Figure D-2 The construction of the D-201 internal combustion engine is shown in detail. (For example...) Figure D-2 As shown, the intake passage D-214 is connected to the air filter D-216. During operation, air is drawn in through the air filter D-216. The internal combustion engine D-201 includes a carburetor D-215. In an embodiment, a fuel opening D-218 in the carburetor D-215 leads into the intake passage D-214. A throttling element D-217 is pivotally supported in the intake passage D-214, and in this embodiment, in the carburetor D-215. Instead of via the carburetor D-215, fuel supply can also be performed by other means, such as via a fuel valve. In this case, the throttling element D-217 is also supported in the intake passage D-214.

[0227] To increase the free flow cross-section, the throttling element D-217 should pivot in the opening direction D-234. To decrease the free flow cross-section, the throttling element D-217 should pivot in the closing direction D-232.

[0228] Operating device D-229 operates the throttling element D-217 in the opening direction D-234. In the closing direction, operation is primarily performed by a spring mechanism. The throttling element D-217... Figure D-2 The diagram illustrates the position of the throttling element D-217, which is connected to the position of the throttling lever D-230, which can be adjusted via the operating device D-229.

[0229] The amount of fuel supplied via at least one fuel opening D-218 is controlled by valve D-219 and also depends on the negative pressure in the intake passage D-214. Valve D-219 is connected to control device D-220 of internal combustion engine D-201, which opens and closes valve D-219.

[0230] Alternatively, fuel supply can also be made directly within the crankcase D-204 or at other locations on the internal combustion engine D-201 via the fuel valve D-219', which is shown schematically.

[0231] An actuator D-221 is provided for the throttling element D-217. The actuator D-221 can adjust the throttling element D-217 in both the opening direction D-234 and the closing direction D-232. The actuator D-221 includes an electric motor D-231 for adjusting the throttling element D-217. The actuator D-221 is connected to a control device D-220. In an embodiment, an ignition device D-222 is provided to provide energy to the control device D-220 and the spark plug D-211. Alternatively, the internal combustion engine D-201 may also have a generator for providing ignition energy.

[0232] The construction of the internal combustion engine D-201 is described and shown only by way of example and schematic representation.

[0233] The internal combustion engine D-201 can also be a two-stroke engine that operates using scavenging pre-compression. In this case, in addition to the intake passage D-214, another air passage is provided for supplying scavenging pre-compressed air. This air passage can be controlled by a throttling element D-217 or another throttling element. In this case, the position of the other throttling element can be connected with the position of the throttling element D-217 for the intake passage D-214.

[0234] Figure D-3 The diagram schematically shows the position of the throttling element D-217, which is configured as a throttling gate. A roller-configured throttling element D-217 has a corresponding position. The roller-configured throttling element particularly has an approximately cylindrical base with at least one transverse hole, wherein the transverse hole forms an intake passage section of the intake passage D-214.

[0235] The position of the throttling element D-217 is indicated by the opening angle D-γ. The opening angle D-γ is measured relative to the longitudinal axis of the intake passage D-237. The longitudinal axis of the intake passage D-237 is aligned with the main flow direction of the intake passage D-214. In the closed position D-243 of the throttling element D-217, the throttling element D-217 and the longitudinal axis of the intake passage D-237 enclose the opening angle D-γ2. In the closed position D-243 of the throttling element D-217, the free flow cross-section of the intake passage D-214 is minimized. In the closed position D-243, the throttling element D-217... Figure D-3 The text is displayed using solid lines. Figure D-3In the intermediate position D-244, indicated by a dotted line, the throttling element D-217 and the intake passage longitudinal axis D-237 enclose an opening angle D-γ1. The opening angle D-γ1 is smaller than the opening angle D-γ2. In the fully open position D-245, in this embodiment, the throttling element D-217 and the intake passage longitudinal axis D-237 enclose an opening angle D-γ of 0°. In this position, the throttling element D-217 is parallel to the intake passage longitudinal axis D-237. At this position of the throttling element D-217, the free flow cross-section of the intake passage D-214 is maximized. In this embodiment, the actuator D-221 is not activated throughout the entire adjustment angle range of the throttling element D-217. The actuator D-221 is activated particularly in the region between the intermediate position D-244 and the fully closed position D-243.

[0236] If the throttling element D-217 is near the fully open position D-245, and the rotational speed Dn is within or below the rated final rotational speed D-nsoll, then a load is received at the tool. The tool is cutting. If, at the rated final rotational speed D-nsoll, the throttling element D-217 is near the closed position D-243, then no load is received at the tool. The proposed method is particularly suitable for this situation. In the embodiment, the method is configured to be implemented, particularly within a partial angular range D-g2 between the intermediate position D-244 and the fully closed position D-243 of the throttling element D-217. To detect the position of the throttling element D-217, for example, a [missing information - likely a measurement or feature] is provided. Figure D-3 The throttling sensor D-238 is schematically shown in the diagram, which detects the rotational position of the throttling element D-217.

[0237] Figure D-4 The graph shows curves of rotational speed Dn, load DL, and opening angle D-γ over time Dt for an exemplary process of this method. Curve D-240 in graph (Da) shows the curve of rotational speed Dn. Curve D-242 in graph (Db) shows an exemplary curve of load DL, from which the rotational speed curve shown can be derived. Curve D-241 in graph (Dc) shows the curve of opening angle D-γ that can be derived from this curve of load DL. Up to time D-t0, the non-invention adjustment of the position of the throttling element D-217 for the exemplary rotational speed curve is schematically shown. The rotational speed Dn fluctuates very drastically. Accordingly, actuator D-221 ( Figure D-2 The throttling element D-217 is alternately operated to open and close, resulting in an uneven speed curve. From time D-t0, the throttling element D-217 is adjusted only in a very slow manner. This achieves a uniform drop in speed n below the rated final speed D-nsoll at time D-t1 (Figure (Da)).

[0238] At time D-t1, the speed is below the rated final speed D-nsoll. Subsequently, the throttling element D-217 remains open at a relatively slow rate of adjustment. The opening of the throttling element D-217 is so slow that when the load at the tool increases (e.g., because the operator moves the tool into the workpiece), the speed Dn may drop relatively sharply. The increase in load DL is schematically shown in the graph (Db) from time D-t2.

[0239] At time D-t3, it is below the first speed limit D-n1 (Figure (Da)). The first speed limit D-n1 is below the rated final speed D-nsoll.

[0240] Curve segments D-246 (Graph (Da)) and D-247 (Graph (Dc)) schematically show the curves of speed Dn and throttle angle D-γ when the throttle element continues to be adjusted at the same speed. As shown in curve segment D-246 in Graph (Da), a very sharp drop in speed occurs between times D-t4 and D-t5.

[0241] To prevent such a drastic drop in speed, the adjustment speed for the throttle element D-217 is increased after the speed drops below the first speed limit D-n1. This is indicated by curve D-241, shown as a solid line in graph (Dc). Because the throttle element D-217 is in the opening direction D-234 ( Figure D-2 The faster adjustment at the speed prevents a very drastic drop in speed. In this embodiment, the speed Dn is maintained above the second speed limit D-n2, as shown by the solid line in the graph (Da).

[0242] Below the second speed limit D-n2, actuator D-221 is specifically placed in an inactive state. In this inactive state, the position of throttle element D-217 is determined solely by a position preset by the operator via operating device D-229. In an embodiment, the operator has fully actuated operating element D-228, configured as an accelerator pedal, so that, according to the speed curve based on curve segment D-246, throttle element D-217 will be adjusted to the fully open position D-245 at time D-t4. Reactivation of actuator D-221 occurs specifically after exceeding the first speed limit D-n1 again. Other speed limits may also be set for the activation and inactivation of actuator D-221.

[0243] Figure D-5 The schematic diagram illustrates the process of the method. In the first method step D-251, as long as the rotational speed n is above the rated final rotational speed D-nsoll, the throttling element D-217 moves in the closing direction D-232 to adjust the rotational speed Dn.

[0244] If the rotational speed n drops below the rated final speed D-nsoll, then in method step D-252, the throttling element D-217 moves in the opening direction D-234, more precisely, at the first regulating speed D-v1. If the rotational speed subsequently rises back above the rated final speed D-nsoll, then method step D-251 is performed again.

[0245] If the rotational speed Dn continues to drop below the first rotational speed limit D-n1 (e.g., because a load is received at the tool), then in method step D-253, the throttling element D-217 adjusts in the opening direction D-234 at a higher second adjustment speed D-v2. The second adjustment speed D-v2 is at least twice the first adjustment speed v1, particularly two to ten times. In particular, the second adjustment speed D-v2 is three to six times the first adjustment speed D-v1.

[0246] If the rotational speed continues to drop below the second rotational speed limit D-n2, then in method step D-254, actuator D-221 is placed in an inactive state. The position of throttling element D-217 is determined solely by a position preset by the operator. Actuator D-221 is only reactivated when the rotational speed Dn exceeds the first rotational speed limit D-n1 again, and the rotational speed is adjusted to the rated final speed D-nsoll, as previously described.

[0247] Actuator D-221 is specifically manipulated such that the opening angle D-γ of throttling element D-217 will never be less than the opening angle D-γ preset by the operator. Therefore, actuator D-221 cannot open throttling element D-217 further than the operator presets. Adjustment in the direction toward the fully open position D-245 is limited by the operator's expectations.

[0248] The actuator D-221 is controlled primarily via a PI controller. To achieve different regulation speeds D-v1 and D-v2 for the throttling element D-217, the P and I components of the controller can be configured to be speed-dependent, for example. Alternatively or additionally, the actuator D-221 can be configured for speed-dependent control in addition to the PI controller. PI controllers with smaller P and I components are particularly suitable for tools with relatively large inertia. If no load is received at the tool location in these tools, the throttling element D-217 must be moved a considerable distance toward the fully closed position D-243 to set the rated final speed.

[0249] A slight change in the position (rotational position in this embodiment) of the throttling element D-217 will cause a very large change in the free flow cross-section of the intake passage D-214, resulting in very large speed fluctuations. Therefore, stable operation of the internal combustion engine D-201 can be achieved by slowly adjusting the throttling element D-217 between the rated final speed D-nsoll and the first speed limit D-n1, and by rapidly adjusting it between the first speed limit D-n1 and the second speed limit D-n2.

[0250] The present invention also relates to a method for operating an internal combustion engine of the type described in the preamble of claim 60, and an internal combustion engine.

[0251] An internal combustion engine is known from WO 2020 / 027708 A1, the control equipment of which is configured to adjust a throttling element arranged in the intake passage to set the desired speed of the internal combustion engine.

[0252] A carburetor for operating an internal combustion engine is known from DE 10 2009 023 964 B4, wherein it is determined whether combustion occurs in the combustion chamber in each engine cycle.

[0253] This invention aims to provide a method for operating an internal combustion engine that enables advantageous control of the engine. Another objective of this invention is to describe an internal combustion engine for performing this method.

[0254] Regarding the method, the task is solved by a method having the features of claim 60. Regarding the internal combustion engine, the task is solved by an internal combustion engine having the features of claim 70.

[0255] Whether combustion occurs in each engine cycle in an internal combustion engine depends on the fuel / air ratio in the combustion chamber. If the fuel / air mixture in the combustion chamber is too rich or too lean, combustion will not occur in each engine cycle. To eliminate this undesirable state, the amount of fuel supplied must be increased when combustion is not occurring due to an overly lean mixture. Conversely, the amount of fuel supplied must be reduced when combustion is not occurring due to an overly rich mixture.

[0256] To identify whether the lack of combustion in the combustion chamber is due to an overly rich or overly lean mixture, the present invention is configured to reduce the amount of fuel supplied when it is determined that an engine cycle without combustion has occurred in the combustion chamber. To differentiate between possible causes of the lack of combustion (i.e., an overly rich or overly lean mixture in the combustion chamber), the actuator response is evaluated.

[0257] The actuator is configured to adjust the throttling element in both the closing and opening directions to set the desired rotational speed. The actuator adjusts the throttling element in the closing direction to reduce the rotational speed and in the opening direction to increase the rotational speed.

[0258] To set the desired rotational speed, if the instantaneous rotational speed is greater than the desired speed, the actuator must adjust the throttling element in the closed direction to reduce the instantaneous rotational speed to the desired speed. If the instantaneous rotational speed is lower than the desired speed, the actuator must adjust the throttling element in the open direction to increase the instantaneous rotational speed to the desired speed.

[0259] When the amount of fuel supplied is reduced, the engine speed varies depending on whether the mixture in the combustion chamber is too rich or too lean. When the mixture is too rich, the engine speed increases due to the reduced fuel supply. When the mixture is too lean, the engine speed decreases due to the reduced fuel supply.

[0260] If the actuator adjusts the throttle element in the opening direction in response to a reduction in the amount of fuel supplied, the actuator reacts to a decrease in engine speed. Since the engine speed has already decreased in response to the reduced fuel supply, the fuel / air mixture in the combustion chamber of the internal combustion engine is excessively lean. Therefore, the λ value generated in the combustion chamber is significantly greater than 1.0. In this case, the method is set to increase the amount of fuel supplied. This can thus counteract the unburned engine cycle in the combustion chamber.

[0261] If the actuator adjusts the throttling element in the closed direction in response to a reduction in the fuel supply, the actuator reacts to an increase in engine speed. Since the engine speed has already increased in response to the reduced fuel supply, the fuel / air mixture in the combustion chamber is excessively rich. Therefore, the λ value produced in the combustion chamber is significantly less than 1.0. Thus, reducing the fuel supply as a response to the determined unburned engine cycle in the combustion chamber is the correct reaction, so as to react to further unburned engine cycles. Therefore, no further changes in the fuel quantity are needed until the next determined unburned engine cycle.

[0262] By evaluating the actuator's response, undesirable operating conditions of the internal combustion engine (where combustion does not occur in the combustion chamber in every engine cycle) can be avoided in a simple way by utilizing the always-present actuator, or in other words, the state can be reversed.

[0263] This method is repeated after each identified unburned engine cycle. If the internal combustion engine is operating in a state where an unburned engine cycle occurs in the combustion chamber due to an overly rich mixture, the amount of fuel supplied is further reduced each time this method is executed, because the actuator is not determined to adjust the throttling element in the opening direction in response to the reduced fuel supply. Thus, the mixture is continuously leanened until no more unburned engine cycles are identified in the combustion chamber. If an unburned engine cycle occurs due to an overly lean mixture in the combustion chamber, the amount of fuel supplied is increased, because the actuator is determined to adjust the throttling element in the opening direction in response to the reduced fuel supply.

[0264] The fuel quantity is specifically increased to a level greater than the fuel quantity supplied before the reduction of the fuel supply in the previous step of the method. Overall, the fuel quantity supplied is thus increased during the course of the method.

[0265] In particular, the internal combustion engine is a two-stroke engine. This is determined based on the engine cycle in which combustion does not occur in the combustion chamber, especially whether the two-stroke engine operates in four-stroke mode. This is the case when no combustion occurs in the combustion chamber every other engine cycle.

[0266] Four-stroke operation can be easily identified by assessing the pressure in the crankcase. In particular, fluctuations in crankcase pressure can be assessed. Alternatively, another method for assessing crankcase pressure can also be used. To identify four-stroke operation, engine speed can be alternatively or supplementarily assessed. Another method can also be used to determine whether combustion has occurred in the combustion chamber and / or whether a two-stroke engine is operating in four-stroke mode.

[0267] In particular, the two-stroke engine is configured to contain a fuel / air mixture in the crankcase. The fuel present in the crankcase can thus be used to lubricate the moving parts within the crankcase. Fuel is supplied, in particular, to the intake manifold or the crankcase of the two-stroke engine. An overflow manifold for supplying fuel to the two-stroke engine may also be provided.

[0268] In particular, the internal combustion engine includes control equipment. The control equipment specifically determines whether an unburned engine cycle occurs in the combustion chamber. The control equipment may specifically be equipment that monitors engine parameters and controls the amount of fuel to be supplied and / or the actuators and / or the ignition devices of the internal combustion engine. Other components of the internal combustion engine may also be controlled by the control equipment.

[0269] The evaluation of the actuator's response is sufficient to distinguish whether the actuator is adjusting the throttling element in the opening or closing direction. It can be configured to detect the actuator's rotation direction when evaluating the actuator's response to a reduction in the supplied fuel quantity. Alternatively or additionally, the position of the throttling element can be detected when evaluating the actuator's response in step (c). For this purpose, a rotational position sensor can be arranged, for example, at the throttling shaft of the throttling element. Any other method of detecting the position of the throttling element can also be configured.

[0270] An internal combustion engine configured to perform the method particularly comprises: a cylinder in which a combustion chamber is configured; and an intake passage for supplying air, wherein a throttling element is arranged in the intake passage, wherein an actuator is provided, the actuator being configured to adjust the throttling element in the opening direction to increase the free flow cross-section of the intake passage, and to adjust the throttling element in the closing direction to decrease the free flow cross-section of the intake passage, so as to set a desired speed, wherein a device for supplying fuel is provided.

[0271] The internal combustion engine particularly includes a control device configured to operate the actuator. Specifically, the control device is also configured to determine whether an unburned engine cycle has occurred in the combustion chamber. For this purpose, the control device can, for example, evaluate the signal from a pressure sensor measuring the pressure in the crankcase and / or the engine speed. In particular, the control device is configured to change the amount of fuel supplied. The control device is particularly configured to preset the ignition timing. In particular, the control device is also configured to evaluate the actuator's response when the amount of fuel supplied is changed.

[0272] In particular, the internal combustion engine is a two-stroke engine. The combustion chamber is specifically defined by a piston, whose rotation drives a crankshaft supported in the crankcase of the internal combustion engine. An intake passage specifically supplies air to the crankcase. The crankcase is fluidly connected to the combustion chamber at at least one predetermined position of the piston. The internal combustion engine specifically has a pressure sensor for determining the pressure in the crankcase. The device for supplying fuel specifically supplies fuel to the intake passage or the crankcase. For fuel supply, a fuel valve is specifically provided, particularly a solenoid valve operated by a control device.

[0273] The embodiments of the present invention will be described below with reference to the accompanying drawings. Wherein: Figure E-1 A schematic cross-sectional view of a handheld working tool is shown. Figure E-2 Showing Figure E-1 A schematic diagram of an internal combustion engine in a working machine. Figure E-3 A schematic diagram showing the throttling element of an internal combustion engine in different positions is displayed. Figure E-4The diagram shows a schematic representation of the relationship between the throttle angle and the value of λ in the fuel / air mixture in the combustion chamber for a constant engine speed curve. Figure E-5 and Figure E-6 A schematic diagram showing the possible flow of this method is provided. Figure E-7 The graphs shown exemplify the curve of average crankcase pressure and individual measured pressure values.

[0274] Figure E-1 The working instrument E-25 is shown schematically. Figure E-1 The image shows a motor saw as an embodiment of a working instrument E-25, the construction of which is illustrated exemplarily below. The working instrument E-25 is preferably a handheld, particularly portable, working instrument. The working instrument E-25 can also be other working instruments, such as a cutter, blower, or brush cutter. The working instrument E-25 includes a housing E-26, in which a handle E-27 is arranged for guiding and carrying the working instrument E-25 in operation. An operating element E-28 is arranged at the handle E-27. At least one of the operating elements E-28 is used to operate the internal combustion engine E-1 of the working instrument E-25. In an embodiment, the operating element E-28 acts on a throttle lever E-30 via an operating device E-29. To control the amount of combustion air supplied to the internal combustion engine E-1, schematically shown... Figure E-2 And supported in Figure E-1 The throttling element E-17 is shown in the throttling housing E-15. The throttling housing E-15 can be, for example, a carburetor. The throttling element E-17 is connected to the throttling lever E-30. The operator can open the throttling element E-17 via the throttling lever E-30. The resetting of the throttling element E-17 is typically achieved by a closing spring (not shown).

[0275] The internal combustion engine E-1 includes a cylinder E-2, in which a combustion chamber E-3 is constructed. The combustion chamber E-3 is defined by a piston E-5, which, via a connecting rod E-6, rotates a crankshaft E-7 rotatably supported in a crankcase E-4. Figure E-2 As shown, the crankshaft E-7 is supported in a manner rotatable about a rotation axis E-8. The internal combustion engine E-1 includes an intake passage E-14 for supplying combustion air. The intake passage E-14 opens into the cylinder bore of cylinder E-2 via an inlet opening E-9. An exit opening E-10 leads from the combustion chamber E-3. In an embodiment, the inlet opening E-9 and the exit opening E-10 are controlled by the piston E-5. Figure E-1 As shown, spark plug E-11 extends into combustion chamber E-3. Spark plug E-11 is made of... Figure E-2 The ignition device E-22, schematically shown in the diagram, is supplied with energy.

[0276] In this embodiment, the internal combustion engine E-1 is a two-stroke engine. The internal combustion engine E-1 is particularly a single-cylinder engine. The internal combustion engine E-1 has an overflow passage E-12, which connects to the combustion chamber E-3 via an overflow window E-13. Figure E-2 One of the overflow passages E-12 is schematically shown. In the region of bottom dead center of piston E-5, overflow passage E-12 fluidly connects the interior space of crankcase E-4 to combustion chamber E-3. Overflow window E-13 is controlled by piston E-5.

[0277] like Figure E-1 As shown, exit opening E-10 leads to exhaust muffler E-23 via exit passage E-33. Catalyst E-24 or other equipment for exhaust aftertreatment may be arranged in exhaust muffler E-23.

[0278] Figure E-2 The construction of the internal combustion engine E-1 is shown in detail. An intake passage E-14 draws in ambient air through an air filter E-16. In an embodiment, at least one fuel opening E-18 in a throttle housing E-15 leads into the intake passage E-14. In an embodiment, the fuel opening E-18 is controlled by a valve E-19. Valve E-19 is particularly an electrically operated valve, especially a solenoid valve. It can also be configured that valve E-19 directly supplies fuel to the interior space of the intake passage E-14. Figure E-2 The diagram schematically shows valve E-19' at crankcase E-4, which can be used to supply fuel directly to the interior space of crankcase E-4, alternatively to valve E-19.

[0279] In this embodiment, the throttling element E-17 is configured as a throttling gate. The throttling element E-17 can be in the closed position E-56 (where it is in...). Figure E-2 (marked with a solid line in the middle) and the opening position E-57 (which is in Figure E-2 Adjustment is made between the following positions (marked with dashed lines): To adjust the throttling element E-17 from the closed position E-56 toward the open position E-57, the throttling element needs to be pivoted in the open direction E-34. To adjust from the open position E-57 toward the closed position E-56, the throttling element E-17 should be pivoted in the closed direction E-32. In the closed direction E-32, the throttling element E-17 is preloaded by a closing spring (not shown).

[0280] The open position E-57 of the throttling element E-17 is the position where the throttling element E-17 essentially releases the flow cross-section in the intake passage E-14. In the closed position E-56, the throttling element E-17 closes the flow cross-section of the intake passage E-14 to a predetermined remaining cross-section. Therefore, in the open position E-57, the flow cross-section of the intake passage E-14 is larger than that in the closed position E-56.

[0281] The internal combustion engine E-1 includes a control device E-20. The control device E-20 operates the ignition device E-22 and presets the ignition timing for the spark plug E-11. The control device E-20 also controls valves E-19, 19', and thus controls the amount of fuel supplied to the internal space of the crankcase E-4 through the intake passage E-14. In an embodiment, the control device E-20 also operates an actuator E-21. The actuator E-21 is configured to adjust the throttling element E-17 in the closed direction E-32 and the open direction E-34. For this purpose, in an embodiment, the actuator E-21 includes an electric motor E-31. However, other actuator configurations for adjusting the position of the throttling element E-17 may also be provided.

[0282] Figure E-3 The arrangement of the throttle element E-17 in the intake passage E-14 is schematically shown. Here, the closed position E-56 is schematically shown with a solid line, the open position E-57 with a dashed line, and the intermediate position E-58 with a dotted line. Between the closed position E-56 and the open position E-57, the throttle element E-17 can be adjusted within the adjustment angle range α. The position of the throttle element E-17 can be described by the throttle angle γ, where the fully closed position E-56 corresponds to a throttle angle γ of E-0°. The fully open position E-57 can, for example, correspond to a throttle angle γ of E-50° to E-80°.

[0283] The throttling angle γ can be determined, for example, by a throttling shaft sensor E-35, as it is located in... Figure E-3 As illustrated in the diagram.

[0284] Control device E-20 is configured to set a desired speed for at least one operating state. This operating state may be, for example, an unloaded final speed state. To this end, control device E-20 can change the throttle angle γ via actuator E-21, and thus regulate the amount of air supplied to internal combustion engine E-1. Figure E-4The constant speed curve E-60 shows the relationship between the throttle angle γ and the excess air coefficient λ in the combustion chamber. The maximum power for this operating condition occurs at point E-59. In a two-stroke engine, the maximum power is obtained when the excess air coefficient λ in the combustion chamber E-3 is slightly lower than that in E-1. This corresponds to a relatively large throttle element E-17 closed for this operating condition. If the throttle element E-17 is further adjusted in the closing direction E-32 from its position at point E-59, the speed will drop below the speed set in curve E-60.

[0285] In zone E-37, four-stroke operation is generally not observed. In zones E-38 and E-39, internal combustion engines of E-1 may fall into four-stroke operation, where no combustion occurs in the combustion chamber every other engine cycle. This operating condition should be avoided. Control device E-20 can, for example, be used to assess... Figure E-7 The pressure Ep in crankcase E-4 is schematically shown, or this operating condition can be determined by assessing the engine speed in engine E-1. Zone E-40 represents the intermediate region where four-stroke operation may occur.

[0286] If four-stroke operation or an unburned engine cycle is detected in combustion chamber E-3, the control device E-20 is configured to first assume that the fuel / air mixture in combustion chamber E-3 is too rich. In this case, the internal combustion engine E-1 can, for example, be in a state of... Figure E-4 The point E-45 is shown on curve E-60. The method flow in this case is... Figure E-5 As shown in [the diagram]. If at that run point in method step E-41 ( Figure E-5 If it is determined in process step E-42 that an unburned engine cycle has occurred in combustion chamber E-3, then the process is configured to reduce the amount of fuel supplied, i.e., lean the fuel / air mixture in combustion chamber E-3. In an embodiment, it is exemplary configured to lean the mixture to... Figure E-4Point E-46. Leaning out when the mixture is rich in combustion chamber E-3 causes an increase in the speed of internal combustion engine E-1. Therefore, control device E-20 will adjust actuator E-21 in the closed direction E-32 to point E-47 to reduce the speed back to the desired speed. Therefore, reducing the amount of fuel supplied is the correct response to prevent an unburned engine cycle in combustion chamber E-3 under this operating state of internal combustion engine E-1. Therefore, the method restarts to determine whether an unburned engine cycle has occurred in the combustion chamber. If another unburned engine cycle has occurred, the amount of fuel supplied is reduced again, for example, to point E-48. In response to the reduction in the amount of fuel supplied, actuator E-21 further adjusts throttle element E-17 in the closed direction E-32 to counteract the increase in speed due to the reduction in fuel supply, for example, to point E-49. At point E-49, internal combustion engine E-1 is in the region where the excess air coefficient λ does not normally occur during four-stroke.

[0287] If an engine cycle without combustion occurs in combustion chamber E-3 at point E-50, where the internal combustion engine E-1 operates with a lean fuel / air mixture in combustion chamber E-3 (i.e., the excess air coefficient λ is significantly greater than E-1.0), then the supplied fuel quantity will also be leaned first, for example, up to point E-51. This is in Figure E-6 The process is carried out in step E-41 of the method shown. In response to this reduction in fuel supply, the speed of the internal combustion engine E-1 decreases. Actuator E-21 then adjusts the throttle element E-17 in the opening direction E-34 to restore the speed to the desired value. This can proceed, for example, to point E-52. If it is recognized in step E-42 that actuator E-21 has adjusted the throttle element E-17 in the opening direction E-34 in response to the reduction in fuel supply, then in step E-43... Figure E-6 Increase the amount of fuel supplied, for example to Figure E-4 Point E-53. Here, the amount of fuel supplied is specifically increased to a quantity greater than the amount supplied before the reduction of the fuel supply in method step E-41. Thus, as in the same way... Figure E-4 As shown, relative to the initial state at point E-50, a total increase in the amount of fuel supplied is achieved. Due to the increase in the amount of fuel supplied, the speed increases, and actuator E-21 adjusts the throttling element E-17 in the closed direction E-32 until curve E-60 is reached. In this embodiment, this is the case at point E-54. Point E-54 is located in region E-37 where four-stroke operation does not normally occur.

[0288] By evaluating the response of actuator E-21 to a reduction in the amount of fuel supplied, the internal combustion engine E-1 can be determined in a simple manner. Figure E-4The graph E-60 indicates whether the engine is operating on the left or right branch of curve E-60, i.e., whether combustion chamber E-3 is operating with a lean or rich mixture. The fuel supply can be adjusted accordingly until no unburned engine cycles occur in combustion chamber E-3. This is the case when the mixture in combustion chamber E-3 is in region E-37.

[0289] Figure E-7 The measured crankcase pressure during a continuous engine cycle is shown as an example. The crankcase pressure p can be used to determine whether combustion occurred in each engine cycle. Figure E-7 This displays a single measured pressure value for the crankcase pressure Ep as a function of time Et. Due to limitations, the pressure values ​​for crankcase pressure p fluctuate very dramatically. From time E-t3, the pressure values ​​remain approximately constant. Before time E-t3, the internal combustion engine E-1 operates as a four-stroke engine, meaning that combustion occurs only once in the combustion chamber E-3 every engine cycle.

[0290] Pressure value E-p1 represents the crankcase pressure Ep at time E-t1 after combustion has occurred in combustion chamber E-3. Pressure value E-p2 represents the crankcase pressure Ep at time t2 after an engine cycle in combustion chamber E-3 in which no combustion has occurred. Figure E-7 The average value Ep for crankcase pressure Ep is also indicated. M To determine whether combustion has occurred in combustion chamber E-3, or whether a two-stroke engine is operating as a four-stroke engine, it is necessary to calculate the pressure value E-p1 and the average value Ep. M The pressure difference E-Δp1 is calculated between the two values. Corresponding pressure differences E-Δp2 and E-Δp3 are determined for the pressure values ​​E-p2 and E-p3. If combustion does not occur in combustion chamber E-3 for every engine cycle, the differences E-Δp1 and E-Δp2 are relatively large. If combustion occurs in combustion chamber E-3 for every engine cycle, the difference E-Δp3 is relatively small. By evaluating the fluctuations in the pressure Ep in the crankcase, it is possible to determine in a simple way whether an engine cycle without combustion has occurred in combustion chamber E-3.

[0291] If combustion occurs in combustion chamber E-3, piston E-5 and crankshaft E-4 accelerate relatively strongly. By evaluating the engine speed n, the acceleration of crankshaft E-4 between the top dead center and bottom dead center of piston E-5 can be used to determine whether combustion has occurred in combustion chamber E-3. Other methods can also be used to determine whether combustion has occurred in combustion chamber E-3.

[0292] The present invention also relates to a carburetor having a carburetor housing and a throttle valve, wherein the throttle valve is held at a rotatable support on a throttle valve shaft. The throttle valve occupies an idle position in a first rotational position and a terminal position corresponding to a full-load position in a second rotational position. In the full-load position, the throttle valve is aligned along the direction of combustion air flow. A switch is provided for identifying the throttle valve's position in the full-load position, which outputs a signal at a preset rotational position of the throttle valve.

[0293] The final position of the throttle valve is determined by a mechanical stop. The switch is mounted in a rotational position relative to the throttle valve shaft, and therefore outputs an output signal at a preset rotational position corresponding to the full load position of the throttle valve.

[0294] The output signal of the switch is supplied to the control electronics, which, after processing the output signal, other parameters, and boundary conditions given from the environment at the corresponding time, determines the fuel distribution at the full load position of the throttle valve so as to supply the internal combustion engine with a rich mixture corresponding to the full load position through the intake passage of the carburetor controlled by the throttle valve in the flow cross section.

[0295] There are tolerances in the stop portion at the end position of the throttle rotation, and the contact elements of the switch undergo wear during operation. This can lead to wear progressing to such an extent, after a long period of carburetor operation, that the switch used to indicate the full-load position of the throttle cannot be reliably operated. As a result, the control equipment fails to recognize the presence of full load, leading to incorrect selection of regulating variables (such as ignition timing) and / or insufficient fuel delivery under full-load conditions. Internal combustion engines equipped with this carburetor (especially two-stroke engines) may exhibit a significant power reduction.

[0296] The present invention is based on the following objective: to construct a carburetor with a switch for identifying the rotational position of the throttle valve, so that a reliable output signal is generated to identify the full-load position even after long operating time and wear.

[0297] The task is solved according to the features of claim 73.

[0298] According to the present invention, a switch is configured to operate at a preset rotation position of the throttle valve and generate an output signal indicating the full load position. According to the present invention, the preset rotation position of the throttle valve is located within a rotation angle range of 5° to 12° before the throttle valve reaches its actual end position. The output signal indicating the full load position of the throttle valve is issued at least once before the throttle valve reaches its actual end stop. A pre-set mechanical end stop in the throttle valve structure corresponds to the full load position in the throttle valve structure. The switching time of the switch according to the present invention is located in a preset wear zone (rotation angle degree) before the end position of the throttle valve or throttle valve shaft. At the preset rotation position before the end position of the throttle valve, an output signal indicating the full load position of the throttle valve is issued at least once. Issuing a continuous output signal within the preset rotation angle range may be advantageous.

[0299] It has been found that switching the switch ahead of the actual end position reached by the throttle structure and displaying the full-load position does not adversely affect the operation of a two-stroke engine equipped with this carburetor. On the contrary, by operating the switch in advance and issuing an output signal for the full-load position within a rotation angle range of 5° to 12° before the end position of the throttle structure, even after long operating times, reliable identification of the full-load position is ensured, thus ensuring that the control unit reliably calculates the regulation variables under full load conditions.

[0300] In an improved embodiment of the invention, the output signal for the full-load position is issued at least once within a rotation angle between 7° and 10° prior to the throttle valve's terminal position. Preferably, the switch is operated and the output signal for the full-load position is issued within a rotation angle range between 8° and 9° prior to the nominal terminal position of the throttle valve. The mechanical terminal position of the throttle valve is within a tolerance of 90° + / - 3°, i.e., within the nominal 90°. The switching timing for issuing the output signal is independent of this and is suitably specified within a preset 81.5° with a tolerance of approximately 0.5°.

[0301] A rotatable throttle shaft with a throttle valve fixed therein is suitably supported in the carburetor housing, wherein a switch for identifying a preset position of the throttle valve is held in the carburetor housing.

[0302] The switch is advantageously constructed as a "closer" and has a closing contact that closes when a preset position of the throttle is reached. Alternatively, the switch can be suitably constructed as an "opener," i.e., the switch has an opening contact that opens when a preset position of the throttle is reached.

[0303] In a specific design of the switch, it has a first electrical contact element and a second electrical contact element. Here, one of the contact elements is formed by a throttle valve shaft, particularly by an end section of the throttle valve shaft. Alternatively, the contact element may suitably be formed by an element fixed to the throttle valve shaft (e.g., by an element fixed to the end section of the throttle valve shaft).

[0304] In the improved switch design, the first electrical contact element is held within a component to be installed in the carburetor housing. A spool section of the throttle shaft (particularly the end section of the throttle shaft) extends into this component, with the spool section of the throttle shaft forming the second electrical contact element. Switches constructed in this manner operate more reliably than commercially available switches.

[0305] To construct the second electrical contact element, a control edge is formed in the axial section of the throttle valve shaft. This control edge is specifically designed through the edge of the flat portion of the throttle valve shaft. This control edge works in conjunction with the first electrical contact element held in the component. Advantageously, the control edge is constructed in the form of a chamfer mounted on the throttle valve shaft. The chamfer design reduces wear.

[0306] The switch is constructed such that, in the preset rotation position of the throttle valve shaft, the control edge of the throttle valve shaft abuts against the first contact element located in the component and closes the electrical contact of the switch.

[0307] In a particular embodiment of the present invention, the throttle valve shaft itself is constructed as an electrical conductor. In particular, the throttle valve shaft is made of a conductive material.

[0308] The carburetor housing (with the throttle valve shaft rotatably supported within it) is advantageously constructed as an electrical conductor. In particular, the carburetor housing is made of a conductive material.

[0309] If the throttle valve shaft is constructed to be an electrical conductor and rotatably supported within a carburetor housing made of a conductive material, electrical contact of the switch can be achieved in a simple manner. The first contact element of the switch is insulatedly held in a member held at the carburetor housing, wherein the member is formed of a non-conductive material, particularly an electrically insulating material. The member is preferably made of plastic.

[0310] Carburetors with full-load switches are particularly suitable for two-stroke engines. The ignition of the mixture drawn into the combustion chamber of the two-stroke engine and / or the fuel dispensing to the intake passage leading to the combustion chamber are advantageously implemented by a control unit, to which an output signal for the switch is supplied. Independent of tolerances and the occurrence of mechanical wear, the teachings according to the invention ensure that the full-load position of the throttle valve can be reliably identified during the long operating duration of the carburetor, and that the control unit of the internal combustion engine can determine the adjustment variables associated with the operating conditions in order to perform ignition and fuel dispensing adapted to the load conditions of the internal combustion engine, especially the two-stroke engine.

[0311] In an improved embodiment of the invention, or as a separate invention, a carburetor is provided, comprising a carburetor housing, an intake passage constructed within the carburetor housing, and a throttle valve disposed within the intake passage, the throttle valve being held at a throttle valve shaft. A switch is provided that closes electrical contact between a first electrical contact element and a second electrical contact element in a predetermined rotational position of the throttle valve. The first contact element is connected to a lead signal line via at least one diode. The first contact element is held in a socket, and at least one electrical connection wire of the diode is held in another socket. The sockets are positioned adjacent to each other and geometrically intersecting such that the connection wire held in one socket is electrically contacted against a contact element located in the other socket in the intersecting area. Reliable electrical contact between the diode and the contact element is achieved in a simple manner. The connection wire is constructed in a circular, particularly cylindrical, configuration. The socket for the connection wire is correspondingly constructed, particularly cylindrical, in a cylindrical configuration.

[0312] In an improved embodiment of the invention, two diodes inserted into diode sockets are held in the housing of the switch, and their connecting wires located at the bottom of the sockets are in electrical contact with each other.

[0313] In an improved embodiment of the invention, or as a separate invention, a circuit assembly for a switch arranged in a carburetor is also provided. An intake passage is constructed within the carburetor housing. An electrically operated fuel valve, supplying fuel to the internal combustion engine, is also provided, preferably opening into the intake passage. A choke is arranged in the intake passage and held at a choke shaft. A first switch outputs a position signal as a position signal at a preset rotation position of the choke. The first switch is arranged in a first electrically parallel branch relative to the electric fuel valve. In the first electrically parallel branch, a diode is connected in series with the switch, which is electrically switched in the off direction. A throttle valve is arranged in the intake passage and held at a throttle shaft. A second switch outputs a position signal as a position signal at a preset rotation position of the throttle valve. The second switch is located in a second electrically parallel branch relative to the electric fuel valve. In the second electrically parallel branch, a first diode and a second diode are connected in series with the second switch. In particular, one diode is electrically switched in the off direction, and the other diode is electrically switched in the on direction. Different types of diodes are arranged in parallel branches, especially Zener diodes, Schottky diodes, LED diodes, rectifier diodes or similar diodes.

[0314] Further features of the invention are derived from the additional claims, description, and drawings. Features disclosed in the embodiments are alternatives or supplementary features to the teachings of claim 73. Features disclosed in the claims, description, and drawings can be combined freely with each other within the scope of the invention. In the drawings: Figure F-1 A schematic diagram of a carburetor with a choke, a throttle, and control devices is shown as an example. Figure F-2 A perspective view of a carburetor with a structured configuration according to the invention, featuring a switch for identifying the full-load position of the throttle valve, is shown. Tu F-3 A perspective view of the throttle valve shaft is shown. Figure F-4 shows a perspective view of the components used to hold the first contact element of the switch for identifying the full load position. Figure F-4a shows a magnified view of a portion of Figure F-4. Tu-5 This shows a perspective view of the component used to hold the first contact element in the idle or partial load position, with the shaft section of the throttle valve shaft extending in. Tu F-6 A perspective view shows the component used to hold the first contact element in the full-load position, with the shaft section of the throttle valve shaft extending in. Tu-7 A schematic diagram showing the rotation angle of the switching moment relative to the throttle valve shaft is displayed. Tu-8 A schematic overview of a circuit assembly with multiple switches in parallel branches relative to the fuel valve is shown.

[0315] According to Figure F-1 The schematic diagram shows a carburetor F-1 with a carburetor housing F-10. An intake passage F-2 is constructed within the carburetor housing F-10, in which at least one throttle valve F-4 is arranged. The throttle valve F-4 is held at a throttle valve shaft F-3, which is rotatably supported. In the illustrated embodiment, the throttle valve shaft F-3 is rotatably held within the carburetor housing F-10. The throttle valve shaft F-3 and / or the carburetor housing F-10 are preferably constructed as electrical conductors. The throttle valve shaft F-3 and / or the carburetor housing F-10 are formed of a conductive material, particularly a metal or metal alloy.

[0316] The exemplary carburetor F-1 also has a choke F-6, which is held at a choke shaft F-5. The choke shaft F-5 is rotatably supported. In the illustrated embodiment, the choke shaft F-5 is rotatably held within the carburetor housing F-10 of the carburetor F-1.

[0317] In the direction of airflow F-40 of the intake combustion air, the choke F-6 and the throttle valve F-4 are placed successively. Preferably, the choke F-6 in its open position F-16 and the throttle valve F-4 in its full-load position F-14 are approximately located in the same plane. Preferably, the throttle valve F-4 in its full-load position F-14 and the choke F-6 in its open position F-16 are located on the longitudinal central axis F-7 of the intake passage F-2.

[0318] An electromagnetic fuel valve F-8 is introduced into the intake passage F-2, and this electromagnetic fuel valve is controlled by a control unit F-9. The control unit F-9 determines the opening time of the fuel valve F-8, and thus determines the amount of fuel supplied to the intake passage F-2. Combustion air flowing in the flow direction F-40 creates a negative pressure in the intake passage F-2, causing fuel to enter the intake passage F-2 when the fuel valve F-8 opens. The resulting fuel / air mixture F-41 is supplied to the combustion chamber F-22 of the internal combustion engine F-20, particularly a two-stroke engine. The combustion chamber F-22 is defined by a reciprocating piston F-23, which drives the crankshaft (not shown in more detail) of the internal combustion engine F-20 via a connecting rod F-25. As the piston F-23 moves upward, the fuel / air mixture F-41 present in the combustion chamber F-22 is compressed and ignited by the spark plug F-21. Combustion drives the piston F-23 downward, thereby rotating the crankshaft.

[0319] The ignition spark, triggered at spark plug F-21, is used to ignite the fuel / air mixture F-41 compressed in combustion chamber F-22. This spark is triggered by control unit F-9 based on the crankshaft angle. Depending on the load conditions of the internal combustion engine F-20 (idle, partial load, full load), spark plug F-21 is controlled at different crankshaft angles to trigger the ignition spark.

[0320] Switches F-11 and F-17 are provided to report the rotational positions of the choke valve F-6 and / or the throttle valve F-4 to the control unit F-9. Switches F-11 or F-17 send output signals F-12 or F-18 to the control unit F-9 via signal lines F-13 or F-19. The control unit F-9 processes the output signals F-12 or F-18 and accordingly, for example, controls the fuel valve F-8 to dispense fuel to the intake passage F-2 and / or controls the spark plug F-21 to trigger the ignition spark, based on the rotational position of the crankshaft of the internal combustion engine F-20.

[0321] like Figure F-2 As shown, switch F-11, associated with choke F-6, is fixed to carburetor housing F-10. Switch F-17, associated with throttle valve F-4, is fixed to carburetor housing F-10 of carburetor F-1 by fixing screw F-15. Switch F-17 consists of a housing F-30, which is particularly a two-piece housing. Housing F-30 consists of a first component F-31, which is closed by a second component F-32. The second component F-32 forms a housing cover. The first component F-31, fixed to carburetor housing F-10, is shown in more detail in Figures F-4 to F-6.

[0322] Throttle shaft F-3 is rotatably supported in carburetor housing F-10 and pivots throttle valve F-4 arranged in intake passage F-2. Throttle shaft F-3 has a preferably central fixed section F-26 where throttle valve F-4 is anti-rotatably fixed. Fixed section F-26 is located between two support sections F-27 of throttle shaft F-3. Retaining devices for levers (not shown in more detail) are provided at the ends F-28 and F-29 of throttle shaft F-3. Preferably, the end F-28 of throttle shaft F-3 located on the side of switch F-17 is axially positioned from switch F-17 (… Figure F-2 It extends out from within. Figure F-2 As shown, a lever F-45 is anti-rotatably mounted on the end F-28 of the throttle shaft F-3 and is suitably secured by a fixing screw F-44, a riveting connection, or other fixing method (e.g., adhesive bonding). Between the support section F-27 and the end F-28 lies the shaft section F-33 of the throttle shaft F-3. A flat portion F-34 is constructed within the shaft section F-33, its bottom F-35 (as shown) Tu-5(As shown) forms a secant line relative to the diameter of the circle of the throttle valve shaft F-3. At least one of the edges extending axially relative to the throttle valve shaft F-3 constitutes a control edge F-37 of the second electrical contact element F-61. Advantageously, the control edge F-37 is chamfered, such that the control edge F-37 itself is formed by chamfering.

[0323] The first component F-31 of the housing F-30 of switch F-17 is shown in Figure F-4. A through-hole F-36 is provided at the bottom of the housing, configured to match the diameter D of the throttle shaft F-3. The throttle shaft F-3 is pushed into the first component F-31 of housing F-30 through the through-hole F-36. A first contact element F-51 is held in the first component F-31, extending into a diameter circle F-39 with diameter D of the through-hole F-36 via a contact section F-52. The throttle shaft F-3, and preferably the shaft section F-33 of the throttle shaft, constitute a second contact element F-61, which, together with the first contact element F-51, constitutes switch F-17.

[0324] The first component F-31 also contains a connecting terminal F-42 with a suitable sleeve-shaped end F-57. A signal line F-19 is connected to the connecting terminal F-42, through which the status of the switch F-17 is reported. Electronic components F-48 and F-49 are arranged in electrical contact between the connecting terminal F-42 and the first contact element F-51, which is particularly configured as a leaf spring, and an electrical connection is established between the connecting terminal F-42 and the first contact element F-51 through these electronic components. Here, the electronic components F-48 and F-49 are preferably in a series circuit. The connecting wires F-46 and F-47 of the electronic components F-48 and F-49 are constructed in a circular shape. The connecting wires F-46 and F-47 have a pre-set length, particularly cylindrical shape. The socket F-50 for the connecting wires F-46 and F-47 is correspondingly constructed, particularly cylindrical.

[0325] The special design of the electrical connection is a separate invention independent of the technical teachings mentioned in the claims, or as an improvement to and combination with the technical teachings mentioned in the claims.

[0326] Thus, for the electrical connection of electronic components F-48 and F-49, it is particularly arranged that the connecting wire F-46 of electronic component F-48 is inserted into a socket F-50, which is particularly constructed as a cylindrical type. The cylindrical socket F-50 is suitably constructed within the first component F-31. The diameter of the cylindrical socket F-50 is configured to precisely match the diameter of the connecting wire F-46. Precise matching means that the connecting wire F-46 can be flush-push into the cylindrical socket F-50 and, particularly, held therein in a way that prevents loss. The second socket F-50 is placed adjacent to another first socket F-59, which may in particular have a shape that accommodates a slot F-54. According to one invention, the sockets F-50 and F-59 are arranged adjacent to each other and geometrically intersecting. This overlap is constructed such that the connecting wire F-46 held in a connector F-50 is electrically contacted in the intersection area F-53 at the contact element F-51 located in an adjacent connector F-59, particularly configured as a receiving slot F-54. This is schematically illustrated in Figure F-4a, taking the intersection F-53 between the second connector F-50 and the receiving slot F-54, which is the first connector F-59, as an example. The receiving slot F-54 for accommodating the first contact element F-51, particularly configured as a leaf spring, is constructed as a partially arc-shaped receiving slot F-54. Other orientations of the receiving slot F-54 are also suitable. The connector F-50 for the connecting wire F-46 of the electronic component F-48 is arranged such that its diameter circle F-55 is located in the receiving slot F-54 or the first connector F-59 in part of its periphery, as shown by the dashed line in Figure 4. This leads to the intersection F-53 of the second connector F-50 with the first connector F-59 or the receiving slot F-54.

[0327] As shown in Figure F-4, a leaf-spring shaped contact element F-51 is inserted into a socket F-59, specifically configured to receive a slot F-54, for fixing within a component F-31 of the housing F-30. Since the second socket F-50 and the receiving slot F-54 of the first socket F-59 have a geometrical intersection F-53, the contact element F-51, via a contact section F-56, is located within the diameter circle F-55 of the receiving sleeve F-50. If the connecting wire F-46 of the electronic component F-48 is now pushed into the socket F-50, the cylindrical connecting wire F-46 is clamped between the contact section F-56 of the contact element F-51 and the socket F-50, thereby establishing a reliable electrical contact between the connecting wire F-46 of the electronic component F-48 and the first contact element F-51. This electrical plug-in contact is particularly suitable for the simple assembly of electronic components F-48 and F-49.

[0328] In the same manner, the connecting wire F-47 of electronic component F-49 can make electrical contact with the sleeve-shaped end of connecting terminal F-42 by inserting it into cylindrical socket F-50.

[0329] The electronic components are, in particular, diodes F-101, F-102, and F-112, wherein two diodes with identical geometries are suitably used, and these diodes have different forward voltages, especially electrically. The diodes are axially pushed into diode holders F-124 and F-125 of component F-31, with connecting wires F-46 or F-47 pushed into corresponding sockets F-50. Connecting wires (not shown in more detail) on the other connecting side of diodes F-101, F-102, and F-112 are located in intersecting channels, where electrical contact between other connecting wires is ensured at the intersection points. Two diode holders F-124 and F-125 are constructed in the same component F-31 into which pre-inserted diodes F-112 and F-122 are inserted, respectively. Connecting wires F-114 and F-115 located at the bottom of diode holders F-124 and F-125 cross each other, thereby achieving electrical contact. Diodes of different structural types, such as F-111, F-112, and F-122, can be used, especially Zener diodes, Schottky diodes, LED diodes, rectifier diodes, or similar diodes.

[0330] exist Tu-5 The image shows the idling position F-24 of the throttle valve F-4, where the throttle valve shaft is pushed into the component F-31 of the housing F-30. The axial position of the throttle valve shaft F-3 is such that the flat portion F-34 of the shaft section F-33 is opposite the contact section F-52 of the first contact element F-51. In particular, the flat portion F-34 in the shaft section F-33 has a width B, which is at least slightly wider than the leaf spring-shaped first contact element F-51 in the component F-31. The contact section F-52, extending into the diameter circle D, is guided in the axial direction of the throttle valve shaft F-3 between the shoulders F-38 of the flat portion F-34. Tu-5 As shown, the bottom F-35 of the flat portion F-34 is placed at a sufficient distance A from the contact section F-52 of the first contact element F-51, such that the shaft section F-33 or the flat portion F-34 does not touch the contact section F-52. There is no electrical contact between the throttle valve shaft F-3 and the contact section F-52 of the first contact element F-51. Switch F-17 is turned on.

[0331] If the throttle valve shaft F-3 rotates in the direction of rotation F-43, and the throttle valve F-4 rotates from... Tu-5When the idle position shown is pivoted toward the full load position, the control edge F-37 rotates toward the contact section F-52. If the throttle valve F-4 approaches the end position associated with the full load position, the control edge F-37 contacts the contact section F-52 of the first contact element F-51, as... Tu F-6 As shown in the figure, an electrical contact is provided between the throttle valve shaft F-3, which serves as the second contact element F-61, and the first contact element F-51 to indicate the full-load position of the throttle valve F-4.

[0332] According to the present invention, an output signal F-18 is emitted via switch F-17 in a preset rotation position of the throttle valve F-4, and this output signal can be supplied to the control unit F-9. The preset rotation position is within a range of 5° to 12° before the structural end position of the throttle valve F-4 corresponding to the full load position F-14.

[0333] exist Tu-7 This is illustrated schematically. Assuming the throttle valve F-4 is in the full-load position with a rotation angle (DW) of 90°, according to the invention, switch F-17 is operated at a rotation angle of 5 to 12° (particularly 8 to 9°) before the full-load position of 90° in the throttle valve's preset rotation position to issue an output signal indicating the full-load position. Tu-7 Curve F-70 illustrates how the switching timing is defined by the adjustment process of switch F-17 in the new state. As shown, reliable switching of switch F-17 and thus a precise output signal F-18 can be provided within a bandwidth of a preferred 1° rotation angle of the throttle shaft F-3. If wear is minimal, the tolerance bandwidth can also be up to 2°. The switching range in the new state then falls within a rotation angle range of 81° to 83°.

[0334] Tu-7 Curve F-80 is shown, which represents the statistical distribution of the full-load stop position of the throttle shaft in a large number of carburetors. In the embodiment of curve 80, the mechanical end position of the throttle is within a tolerance of 90° + / - 2°, i.e., nominal 90°.

[0335] By utilizing the arrangement of switch F-17 according to the invention for generating output signal F-18 and the operation of switch F-17 within a rotation angle range of 5° to 12° before the nominal terminal position of the throttle valve, a reliable output signal for the full-load position of the throttle valve is achieved over a long operating period. The distribution of the switching points of the switch in the new state is reproduced by curve F-70. Due to wear, the switching points of switch F-17 arranged in the new state shift from a rotation angle of 81° to 82° on the throttle valve shaft to a maximum rotation angle of 88°.

[0336] Preferably, the rotation angle range according to the invention is between 80° and 83° of the rotation angle of the throttle valve shaft F-3, and more particularly between 81° and 82° of the rotation angle of the throttle valve shaft F-3.

[0337] If possible Tu-7 As derived from curve F-70, the switching moment of switch F-17 is located before the mechanical or structural end position of the nominal 90° throttle shaft F-3. A wear zone FV is placed between the possible switching moments of switch F-17 within the range of the 90° structural end position of the throttle shaft F-3 according to curve F-80 and the switching moment of switch F-17 according to the invention. Even when the switching moment selected according to the invention in mechanical wear curve F-70 deviates, the output signal F-18 of switch F-17 for indicating the full load position is still guaranteed.

[0338] exist Tu-8 The diagram shows a circuit assembly for switches F-11 and F-17 arranged at carburetor F-1. This circuit assembly illustrates another invention teaching, which is either an independent invention in itself or, in combination with other features disclosed in the foregoing invention, discloses the subject matter of another invention.

[0339] like Figure F-1 As shown, switches F-11 and F-17 indicate the preset rotation positions of the choke F-6 or the throttle valve F-4. An electrically operated fuel valve F-8 is located at the carburetor housing F-10. The fuel valve F-8 is controlled by the control unit F-9 to supply the amount of fuel required for the operation of the internal combustion engine.

[0340] Control unit F-9 is connected to short-circuit switch F-75, which is specifically implemented as a push button. If short-circuit switch F-75 is closed, control unit F-9 stops the operation of the internal combustion engine. First switch F-11 is used to identify a preset rotation position of choke valve F-6, which can specifically correspond to the closed position of choke valve F-6. First switch F-11 and diode F-111 are connected in series in parallel branch F-101 in parallel with fuel valve F-8. Diode F-111 and switch F-11 are located in a common switch housing F-92. Diode F-111 is electrically switched in the cut-off direction, so that fuel valve F-8 can be electrically operated when switch F-11 is closed. Diode F-111 can be a Zener diode, Schottky diode, LED diode, rectifier diode, or similar diode. In the illustrated embodiment, diode F-111 is a Zener diode.

[0341] The circuit assembly F-100 shown has a second parallel branch F-102 relative to the fuel valve F-8. This second parallel branch is formed by connecting a first diode F-112 and a second diode F-122 in series via a second switch F-17. The first diode F-112 is electrically switched in the off direction, allowing the fuel valve F-8 to be controlled. Opening signals (current pulses, voltage pulses) applied to the fuel valve F-8 are not short-circuited through either the first parallel branch F-101 or the second parallel branch F-102.

[0342] The second diode F-122, preferably configured as a Zener diode, switches along the conduction direction. The second parallel branch F-102, consisting of switch F-17 and diodes F-112 and F-122, is located in a common switch housing F-94.

[0343] Fuel valve F-8 is an electromagnetic fuel valve that is subjected to a pulse sequence. The electromagnetic regulating element of fuel valve F-8 is switched on and off by the pulse sequence, and an induced voltage is generated each time it is switched off. This induced voltage can also be referred to as a reverse voltage. To protect this type of electromagnetic regulating element, the reverse voltage is mostly eliminated by a diode.

[0344] In the illustrated embodiment, when switch F-11 is closed, the voltage induced when the fuel valve F-8 is shut off will drop across diode F-111, resulting in a forward voltage of diode F-111 at input terminal F-96 of control unit F-9. The forward voltage at input terminal F-96 depends on the diode F-111 used. Diode F-111 has a preset first forward voltage.

[0345] If switch F-11 is open and switch F-17, which indicates the rotation position of throttle valve F-4, is closed, a series circuit consisting of switch F-17 and diodes F-112 and F-122 connected with opposite polarities is placed relative to fuel valve F-8. Diode F-122 switches in the off direction, while diode F-112 switches in the on direction. Therefore, preferably, the breakdown voltage of diode F-122, which is configured as a Zener diode, is added to the forward voltage of diode F-112, which is directed against reverse voltage, resulting in a voltage level at input terminal F-96 that is greater than the forward voltage of diode F-111 in switch housing F-92 of the first switch F-11.

[0346] When switch F-11 is closed, a first signal voltage exists at input terminal F-96, and when switch F-17 is closed, a second signal voltage exists. Since two diodes F-112 and F-122 are located in switch housing F-94, their on-state voltages are added together to form the second signal voltage. Only diode F-111 is located in switch housing F-92, and its on-state voltage constitutes the first signal voltage. Control unit F-9 detects the signal voltage present at signal input terminal F-96 and can distinguish, at its analog variable, whether it is switch F-11 of choke valve F-5 or switch F-17 of throttle valve F-4 that is closed. Control unit F-9 controls fuel valve F-8 based on the detected signal voltage.

[0347] The input terminal F-96 of the control unit is preferably a control / diagnostic interface, and an external diagnostic device F-98 can also be connected to this control / diagnostic interface.

[0348] The present invention also relates to a switch for detecting the rotational position of a shaft, particularly a preset rotational position of the shaft, having a control edge, preferably a cam or the like, that moves with the shaft for operating electrical contacts. The electrical contacts are arranged in a switch housing, wherein the switch housing is adjustablely supported about a pivot axis. To adjust the rotational position of the switch housing relative to the rotational position of the shaft, a fixed, adjustable stop is provided, which also serves to fix the position of the pivotable switch housing.

[0349] Such a switch can be, for example, installed as a throttle switch at the carburetor of an internal combustion engine. This switch generates a switching signal, which is supplied to a control device, such as an electronic device, for controlling fuel supply. The switching signal can, for example, indicate the full-load position of the throttle. For this purpose, the throttle shaft actuates the electrical contacts of the switch when the full-load position is reached. During switch assembly, its rotational position relative to the throttle shaft must be adjusted and fixed so that, independent of assembly tolerances, the switching signal is reliably triggered at the full-load position of the throttle and supplied to the engine control device.

[0350] When assembling the switch, pivot it at the stop and screw in or out the stop screw until the switch housing is positioned such that the switching signal can be reliably triggered at the full load position of the throttle shaft.

[0351] Based on the objective of this invention, we describe a simple position adjustment of the switch housing for a switch used to detect a particularly preset rotational position of a shaft, which ensures simple and precise adjustment of the switch for the purpose of triggering a switching signal.

[0352] The task is solved according to claim 88 by the following method: a spring-loaded elastic element acts on the switch housing. The spring-loaded elastic element is pre-tightened and applies a pre-tightening force to the switch housing. Due to the pre-tightening force, the switch housing is held at the stop without clearance, so that for precise adjustment of the switch, only the stop screw of the stop needs to be screwed in or out.

[0353] According to a preferred embodiment of the invention, the spring elastic element is constructed as a spring, such as a helical spring or a tension spring, but particularly as a torsion spring.

[0354] Advantageously, the pivot axis is at least parallel to the axis of rotation of the shaft, and in particular, the pivot axis of the switch housing is coaxial with the axis of rotation of the shaft. This ensures simple adjustment.

[0355] In the design of this invention, the valve of the carburetor is rotatably supported by the shaft in the carburetor housing, and the valve is located in the flow channel of the carburetor housing and controls its effective channel cross-section.

[0356] In a particular application of the invention, the shaft is the throttle shaft of the carburetor, and the valve is the throttle valve of the carburetor. This switch allows for precise identification of the full-load position of the throttle valve, and closes the switch contacts at the full-load position, causing the throttle shaft to send a switching signal to the engine control unit at a precisely adjustable rotational position.

[0357] A spring acts on the throttle valve hinge. The throttle valve hinge can overcome the spring force to adjust to the open position of the throttle valve. Preferably, the preload applied by the spring elastic element is greater than the spring force acting on the throttle valve hinge.

[0358] The pivotable switch housing is secured against rotation by a retaining screw. First, loosen the retaining screw, allowing the elastic element, particularly a torsion spring, to press the switch housing against the stop using preload. If the precise rotational position of the switch has been adjusted by screwing in or out the stop screw, tighten the retaining screw to secure the switch housing in the correctly adjusted pivot position against rotation. The retaining screw is specifically engaged in the carburetor housing.

[0359] According to a method for adjusting a switch to detect the full-load position of a carburetor's throttle shaft, which has a control edge for actuation contact that moves with the throttle shaft, the method comprises an arrangement of contacts within a switch housing, the switch housing being adjustablely supported about a pivot axis. When assembling the switch housing, it is first pivoted to a fixed, adjustable stop for positioning the pivotable switch housing. To adjust the rotational position of the switch housing abutting the stop, a stop screw is screwed in or out. The stop screw is continuously screwed in or out until the switch housing is positioned such that a switching signal is reliably triggered at the full-load position of the throttle shaft. To secure the adjusted switch housing at the stop, a spring-loaded element can act on the switch housing, the spring being preloaded and applying a preload force to the switch housing. The switch housing, adjusted in its rotational position, is held at the stop by the preload force.

[0360] Further features of the invention are derived from the claims, description, and drawings. Features mentioned in a single claim, as well as features mentioned in the description and shown in the drawings, can be individually combined with each other to define the subject matter of the invention. Features can also be grouped into feature groups in any manner.

[0361] This invention generally relates to the arrangement of a switch at a shaft so as to trigger contact at a predetermined rotational position of the shaft to send a switching signal to a control device. This general concept is described in embodiments using a throttle valve shaft as an example.

[0362] An embodiment of the present invention is shown in the accompanying drawings and described in detail below. Wherein: Figure G-1 The image shows a perspective view of a carburetor having a throttle valve supported at a throttle shaft and a choke valve supported at a choke shaft. Figure G-2 A side view of a carburetor with a switch arranged at the throttle shaft is shown. Figure G-3 The image shows a front view of the mixture passage facing the coupling side of the carburetor. Figure G-4 Shows the orientation corresponding to Figure G-2 A side view of the carburetor, with the throttle switch removed.

[0363] In the diagram, a carburetor is typically indicated by reference numeral G-1, which has a carburetor housing G-2 and a flow passage G-3 constructed therein. This carburetor is a diaphragm carburetor, which has a fuel pump located below the housing cover G-4, to which fuel is supplied via a connecting pipe G-5. A regulating chamber is constructed on the side of the carburetor housing G-2 opposite the fuel pump, and its dry side has an interface G-6 for ambient pressure, particularly for the clean air side of the air filter.

[0364] A choke G-7 and a throttle valve G-9 are arranged in the flow passage G-3 of the carburetor housing G-2. Figure G-4 The choke G-7 is held at the choke shaft G-8. The throttle valve G-9 is held at the throttle shaft G-10. The throttle shaft G-10 is exemplarily a general shaft G-50. The invention is not limited to the arrangement of the switch G-20 at the throttle shaft G-10, but generally relates to the arrangement of the switch G-20 at the shaft G-50.

[0365] The choke shaft G-8 and the throttle shaft G-10 extend from both sides of the carburetor housing G-2. On the carburetor side, their ends carry levers G-47 and G-48, which form part of the automatic starting device G-49, which is not further described.

[0366] A switch G-20 is arranged at shaft G-50 (in this embodiment, a throttle shaft G-10). Switch G-20 is located on the end section of shaft G-50. Preferably, shaft G-50 passes through the switch housing G-21 of switch G-20.

[0367] The switch G-20 is configured as a position sensor, which is preferably formed by electrical contacts. The electrical contacts are located inside the switch housing G-21. The position sensor can also be an optical sensor, a capacitive sensor, or an inductive sensor.

[0368] The control edge G-22 of shaft G-50 (not shown in detail) Figure G-4 For example, a cam or similar element, located inside the switch housing G-21, manipulates the electrical contacts in the switch housing G-21 in a predetermined rotational position of the shaft G-50 (or throttle shaft G-10 in the embodiment).

[0369] According to the present invention, the spring elastic element G-30 ( Figure G-3 (G-4) acts on the switch housing G-21, and the spring elastic element applies G-33 (in the direction of the arrow) to the switch housing G-21. Figure G-1 The preload force G-35 of the spring elastic element G-30 causes the switch housing G-21 and thus the switch G-20 to abut against the stop G-40, which is preferably fixed in a fixed position, particularly the stop G-40 where the housing is fixed. For this purpose, the switch housing G-21 can pivot about the pivot axis G-23 in the direction of arrow G-32. The pivot axis G-23 of the switch housing G-21 (i.e., the pivot axis G-23 of the switch G-20) is at least parallel to the rotation axis G-11 of the shaft G-50 (in this embodiment, the throttle shaft G-10). Preferably, the pivot axis G-23 of the switch G-20 is coaxial with the rotation axis G-11 of the throttle shaft G-10. Figure G-3 ).

[0370] In a particular design, shaft G-50 (in this embodiment, throttle shaft G-10) passes through switch housing G-21, allowing switch housing G-21 to pivot about the rotation axis G-11 of throttle shaft G-10.

[0371] Spring G-12 acts on throttle valve shaft G-10. Throttle valve shaft G-10 can overcome the spring force of spring G-12 and adjust to the open position of throttle valve G-9. This spring can be a helical spring G-12 held on throttle valve shaft G-10, whose spring force acts in the open position of throttle valve G-10. The preload force applied to switch housing G-21 via spring elastic element G-30 is configured to be greater than the spring force acting on the throttle valve shaft in the opposite direction. This ensures that the spring force acting on throttle valve shaft G-10 does not counteract the preload force G-35 of elastic spring element G-30.

[0372] In the illustrated embodiment, a torsion spring G-31 is shown as the spring elastic element G-30, which is supported at the carburetor housing G-2 by one spring end and grips the switch housing G-21 of the switch G-20 from the rear by the other spring end G-37. Thus, as Figure G-4 As shown, an application of force G-33 (in the direction of the arrow) was applied to the switch housing G-21. Figure G-2 The preload force G-35 applied to the switch housing G-21 in the direction of arrow G-33 causes the switch housing G-21 or the switch G-20 to be pressed against the stop G-40 in the direction of arrow G-32.

[0373] Preferably, a step plate G-25 is provided at the switch housing G-21, opposite to the stop portion G-40. An adjusting screw G-41 is held in the stop portion G-40. By screwing in or out the adjusting screw G-41, the pivot position of the switch G-20 relative to the shaft G-50 (throttle valve shaft G-10 in the embodiment) changes in the direction of arrow G-32 or in the opposite direction of arrow G-32. In this way, the pivot position of the switch G-20 can be adjusted so precisely that the contacts in the switch housing G-21 are operated and a switching signal is generated precisely at a preset rotational position of the shaft G-50 (throttle valve shaft G-10 in the embodiment). When the switch according to the invention is used at the carburetor G-1, adjustment can be made so that a switching signal is issued precisely at the full load position of the throttle valve G-9.

[0374] like Figure G-1As schematically shown, the retaining screw G-28 passes through the slot G-27 in the switch housing G-21. After loosening the retaining screw G-28, the switch housing G-21 can move in the direction of arrow G-32 and against arrow G-32 without completely unscrewing the retaining screw G-28. If the adjustment of switch G-21 is completed by correspondingly correcting the pivot position of switch G-21 relative to the preset rotational position of shaft G-50 (throttle shaft G-10 in the embodiment), then tighten the retaining screw G-28 and fix switch G-20 in a rotationally resistant manner. According to... Figure G-1 In the embodiment shown, after tightening the fixing screw G-28, the switch housing G-21 and the carburetor housing G-2 are connected by a housing fixing method.

Claims

1. A working apparatus having a tool and an internal combustion engine (A-11) for driving said tool, wherein, The internal combustion engine (A-11) includes an intake passage (A-14) in which a throttling element (A-16) is pivotally supported, and wherein the internal combustion engine (A-11) includes an air passage (A-13) in which an air control element (A-20) is pivotally supported, the working instrument having an operating element (A-5) for adjusting the throttling element (A-16) in the opening direction (A-42), and wherein the internal combustion engine (A-11) has a speed limiting device (A-100), wherein the speed limiting device (A-100) includes an actuator. The actuator is configured to adjust the throttling element (A-16) in the closed direction (A-44) to reduce the free flow cross-section of the intake passage (A-14), and wherein the working instrument (A-1) has an unloaded state in which the tool is driven by the internal combustion engine (A-11) and is not engaged with the workpiece. The air control element (A-20) is characterized in that its position is connected to the position of the throttling element (A-16) via a connecting device (A-58), wherein the connecting device (A-58) has a free travel (A-ε) that enables the throttling element (A-16) to pivot relative to the air control element (A-20), and the free travel (A-ε) is sized such that, under no-load conditions, the air control element (A-20) is in its closed position (A-104) regardless of the position of the operating element (A-5).

2. The working apparatus according to claim 1, characterized in that, The connecting device (A-58) is a mechanical connecting device (A-58).

3. The working apparatus according to claim 1, characterized in that, The maximum idle travel (A-ε) is 30°.

4. The working apparatus according to claim 1, characterized in that, The idle travel (A-ε) is at least 15°.

5. The working apparatus according to any one of claims 1 to 4, characterized in that, The idle travel (A-ε) is at least 2° greater than the adjustment angle (A-δ).

6. The working apparatus according to any one of claims 1 to 5, characterized in that, The internal combustion engine (A-11) includes fuel valves (A-63, A-63') for supplying fuel, which are operated by a control device (A-10).

7. The working apparatus according to claim 6, characterized in that, The control device (A-10) operates the actuator of the speed limiting device (A-100).

8. The working apparatus according to any one of claims 1 to 7, characterized in that, The throttling element (A-16) is a throttling gate.

9. The working apparatus according to any one of claims 1 to 8, characterized in that, The throttling element (A-16) is pivotally supported by a throttling shaft (A-17), and the air control element (A-20) is pivotally supported by an air control shaft (A-21).

10. The working apparatus according to claim 9, characterized in that, The position of the throttle shaft (A-17) can be adjusted via the operating element (A-5), wherein the operating element (A-5) is connected via a transmission device (A-38) to an adjustable stop element (A-40) for the throttle shaft (A-17), wherein the stop element (A-40) presets the maximum opening position of the throttle element (A-16).

11. The working apparatus according to claim 10, characterized in that, A closing spring (A-43) is provided to preload the stop element (A-40) in the closing direction (A-44) of the throttle shaft (A-17).

12. The working apparatus according to claim 10 or 11, characterized in that, An opening spring (A-41) is provided to preload the throttle shaft (A-17) in the opening direction (A-42) toward the stop element (A-40).

13. The working apparatus according to claim 12, characterized in that, The actuator is configured to overcome the force of the opening spring (A-41) to disengage the throttle shaft (A-17) from the stop element (A-40) and to adjust the throttle element (A-16) in the closing direction (A-44).

14. The working apparatus according to claim 12 or 13, characterized in that, The opening spring (A-41) and the connecting device (A-58) act on the same end section (A-52) of the throttle shaft (A-17).

15. The working apparatus according to claim 14, characterized in that, The connecting device (A-58) includes a connecting element (A-59) that is anti-rotatably connected to the throttle shaft (A-17), and the opening spring (A-41) is supported at one end (A-71) at the connecting element (A-59) and at the other end (A-72) at the base (A-36).

16. The working apparatus according to any one of claims 9 to 15, characterized in that, The motor (A-45) acts on the first end section (A-51) of the throttle shaft (A-17), and the coupling device (A-58) acts on the second end section (A-52) of the throttle shaft (A-17), wherein the first end section (A-51) and the second end section (A-52) are arranged on opposite sides of the intake passage (A-14).

17. The working apparatus according to any one of claims 9 to 16, characterized in that, The connecting device (A-58) includes a connecting rod (A-66) that connects to a connecting element (A-59) that is anti-rotatably connected to the throttle shaft (A-17) and a connecting element (A-65) that is anti-rotatably connected to the air control shaft (A-21).

18. The working apparatus according to claim 17, characterized in that, The connection portion of the connecting rod (A-66) and at least one of the connecting elements (A-59, A-65) has an elongated hole, which allows for restricted relative movement of the connecting rod (A-66) relative to the connecting element (A-59, A-65).

19. The working apparatus according to any one of claims 1 to 18, characterized in that, The working instrument (A-1) is a cutting machine and the tool (A-7) is a cutting disc.

20. A throttling assembly, comprising a base (B-36) in which an intake passage section (B-37) is formed, wherein, In the intake passage section (B-37), a throttling element (B-16) is pivotally supported by a throttling shaft (B-17). An operating element (B-5) for operator use is provided, which is connected via a transmission device (B-38) to an adjustable stop element (B-40) for the throttling shaft (B-17). The stop element (B-40) presets the maximum opening position of the throttling element (B-16), and a position is provided along the opening direction (B-42) towards the stop element (B-40). An opening spring (B-41) preloads the throttle shaft (B-17) in the direction of opening (B-41), and a closing spring (B-43) preloads the stop element (B-40) in the closing direction (B-44) of the throttle shaft (B-17). A motor (B-45) is provided, configured to overcome the force of the opening spring (B-41) to disengage the throttle shaft (B-17) from the stop element (B-40), and to adjust the throttle element (B-16) in the closing direction (B-44). The stop element (B-40) is characterized in that it is constructed at a rotatably supported drive member (B-46), which is arranged in a housing (B-57) that is sealed relative to the environment.

21. The throttling component according to claim 20, characterized in that, The transfer device (B-38) includes a shaft that enters the housing (B-57), wherein the shaft is sealed by a seal (B-77).

22. The throttling component according to claim 20 or 21, characterized in that, The motor (B-45) is hermetically arranged at an opening (B-53) in the housing (B-57), wherein an element driven by the motor (B-45) extends through the opening (B-53).

23. The throttling component according to any one of claims 20 to 22, characterized in that, The stop element (B-40) can be adjusted by the operator via the transmission device (B-38) against the force of the closing spring (B-43).

24. The throttling component according to any one of claims 20 to 23, characterized in that, The throttling assembly (B-15) is designed such that, in the unoperated state of the transmission device (B-38), the torque applied to the throttling shaft (B-17) by the closing spring (B-43) is greater than the torque applied to the throttling shaft (B-17) by the opening spring (B-41).

25. The throttling component according to any one of claims 20 to 24, characterized in that, The closing spring (B-43) is arranged outside the housing (B-57) and extends in a helical shape about the rotation axis of the drive member (B-46).

26. The throttling component according to any one of claims 20 to 25, characterized in that, The housing (B-57) is defined by the base (B-36) and at least one cover element (B-48).

27. The throttling component according to any one of claims 20 to 26, characterized in that, The throttle shaft (B-17) has two end sections (B-51, B-52) extending on opposite sides of the intake passage section (B-37). The motor (B-45) and the transmission device (B-38) act on the throttle shaft (B-17) at the first end section (B-51). The opening spring (B-41) and the closing spring (B-43) act on the throttle shaft (B-17) at different end sections (B-51, B-52).

28. The throttling component according to claim 27, characterized in that, The closing spring (B-43) acts on the end section (B-51) of the throttle shaft (B-17), and the stop element (B-40) acts on the end section.

29. The throttling component according to any one of claims 20 to 28, characterized in that, The drive element (B-46) is supported on the end section (B-51) of the throttle shaft (B-17) extending from the base (B-36).

30. The throttling component according to any one of claims 20 to 28, characterized in that, The drive component (B-46) is supported on the base (B-36).

31. The throttling component according to any one of claims 20 to 30, characterized in that, The transmission device (B-38) includes a bending-resistant transmission rod (B-39) suspended on a throttling lever (B-49) disposed outside the housing (B-57) and connected to the drive member (B-46).

32. The throttling component according to any one of claims 20 to 31, characterized in that, The transmission device (B-38) includes a transmission mechanism (B-56), particularly a spur gear transmission mechanism.

33. The throttling component according to any one of claims 20 to 32, characterized in that, The motor (B-45) is connected to the throttle shaft (B-17) via a transmission mechanism (B-90).

34. The throttling component according to claim 32, characterized in that, The motor (B-45) is arranged in the base (B-36).

35. The throttling component according to claim 32 or 33, characterized in that, The transmission mechanism (B-56, B-90) is arranged in a sealed housing (B-57).

36. A handheld working instrument comprising at least one tool and a drive motor (B-11) for driving said at least one tool, wherein, The drive motor (B-11) is a two-stroke engine that operates using scavenging pre-compression. The two-stroke engine has an intake passage (B-14) and an air passage (B-13), and includes a throttling assembly (B-15) according to any one of claims 20 to 35, and an air control element (B-20) pivotally supported in the air passage (B-13) by an air control shaft (B-21), wherein the position of the air control shaft (B-21) is connected to the position of the throttling shaft (B-17) via a connecting device (B-58), and wherein the motor (B-45) and the transmission device (B-38) act on the throttling shaft (B-17) at different end sections (B-51, B-52).

37. The handheld working device according to claim 36, characterized in that, The throttle shaft (B-17) has a coupling element (B-59) configured to resist rotation, via which the position of the air control shaft (B-21) is connected to the position of the throttle shaft (B-17), and the opening spring (B-41) is supported at one end (B-71) at the coupling element (B-59) and at the other end (B-72) at the base (B-36).

38. A method for operating an internal combustion engine, - in, The internal combustion engine (C-1) has an intake passage (C-14) in which a throttling element (C-17) is pivotally supported within an adjustment angle range (C-α). - Wherein, the position (C-γ) of the throttling element (C-17) within the adjustment angle range (C-α) can be adjusted by the operator via the operating device (C-29), and - An actuator (C-21) is provided to pivot the throttling element (C-17) in the closing direction (C-32) to reduce the free flow cross-section of the intake passage (C-14). - Includes a control device (C-20) configured to manipulate the actuator (C-21). - Wherein, when the first limit value (C-g1) of the speed standard is exceeded, taking into account the actual speed (Cn) of the internal combustion engine (C-1) as an input variable, the actuator (C-21) is operated in the closing direction (C-32) of the throttle element (C-17). - Wherein, when the second limit value (C-g2) of the speed standard is exceeded, without considering the actual speed (Cn) of the internal combustion engine (C-1) as an input variable, the actuator (C-21) is operated in the closing direction (C-32) of the throttling element (C-17) within at least a partial angle range (C-β) of the adjustment angle range (C-α).

39. The method according to claim 38, characterized in that, When the first limit value (C-g1) of the speed standard is exceeded, the actuator (C-21) is operated in the closing direction (C-32) of the throttling element (C-17) according to the first control method (C-41), taking the actual speed (Cn) of the internal combustion engine (C-1) as an input variable. And when the second limit value (C-g2) of the speed standard is exceeded, the actuator (C-21) is operated in at least one part angle range (C-β) of the adjustment angle range (C-α) in the closing direction (C-32) of the throttling element (C-17) without taking the actual speed (Cn) of the internal combustion engine (C-1) as an input variable, according to the second control method (C-42).

40. A method for operating an internal combustion engine, - in, The internal combustion engine (C-1) has an intake passage (C-14) in which a throttling element (C-17) is pivotally supported within an adjustment angle range (C-α). - Wherein, the position (C-γ) of the throttling element (C-17) within the adjustment angle range (C-α) can be adjusted by the operator via the operating device (C-29), and - An actuator (C-21) is provided to pivot the throttling element (C-17) in the closing direction (C-32) to reduce the free flow cross-section of the intake passage (C-14). - Includes a control device (C-20) configured to manipulate the actuator (C-21). - Wherein, when the first limit value (C-g1) of the speed standard is exceeded, the actuator (C-21) is controlled in the closing direction (C-32) of the throttling element (C-17) according to the first control method (C-41). - Wherein, when the second limit value (C-g2) of the speed standard is exceeded, the actuator (C-21) is operated in the closing direction (C-32) of the throttling element (C-17) within at least one portion angle range (C-β) of the adjustment angle range (C-α) according to the second control method (C-42), wherein, when the actuator (C-21) is operated according to the second control method (C-42), the throttling element (C-17) is adjusted in the closing direction (C-32) to be faster than when the actuator (C-21) is operated according to the first control method (C-41).

41. The method according to claim 39 or 40, characterized in that, From maximum load (CP) max ) to below the maximum load (CP) max In the event of a 30% load drop, if the actuator (C-21) is operated according to the second control method (C-42), the throttling element (C-17) is adjusted in the closing direction (C-32) within a partial angular range (C-β) of at least 5°, particularly at least 25°.

42. The method according to any one of claims 39 to 41, characterized in that, The first control method (C-41) and the second control method (C-42) are executed regardless of the position of the throttling element (C-17).

43. The method according to any one of claims 39 to 42, characterized in that, The actuator (C-21) is also configured to pivot the throttling element (C-17) in the opening direction (C-34) to increase the free flow cross-section of the intake passage (C-14), and the actuator (C-21) is controlled according to the first control method (C-41) to adjust to the desired speed (C-n1) of the internal combustion engine (C-1) by pivoting the throttling element (C-17) in the opening direction (C-34) and in the closing direction (C-32).

44. The method according to claim 43, characterized in that, When the rotational speed is lower than the off-speed (C-n4), the control according to the first control method (C-41) is deactivated.

45. The method according to any one of claims 38 to 44, characterized in that, The actuator (C-21) is operated by the control device (C-20) to close the throttling element (C-17) until at least one interruption criterion is reached, wherein the interruption criterion after exceeding the second limit value (C-g2) of the speed standard is a second limit value (C-g2) lower than the speed standard.

46. ​​The method according to any one of claims 38 to 45, characterized in that, The internal combustion engine (C-1) has a device for identifying the position (C-γ) of the throttle element (C-17), wherein the position (C-γ) of the throttle element (C-17) is identified, and when the second limit value (C-g2) of the speed standard is exceeded, the throttle element (C-17) is adjusted to a preset position (C-γ1).

47. The method according to claim 46, characterized in that, During the regulated operation of the internal combustion engine (C-1), if the first speed standard (C-g1) and the second speed standard (C-g2) are not exceeded, the current position (C-γ) of the throttling element (C-17) is stored as a preset position (C-γ1), and when the second limit value (C-g2) of the speed standard is exceeded, the throttling element (C-17) is adjusted to the preset position (C-γ1).

48. The method according to any one of claims 38 to 47, characterized in that, The first speed standard (C-g1) is the maximum speed (C-n1) and the second speed standard (C-g2) is the intervention speed (C-n2), wherein the maximum speed (C-n1) is less than the intervention speed (C-n2), and the intervention speed (C-n2) is more than 2,000 U / min higher than the maximum speed (C-n1), and more particularly less than 1,000 U / min higher.

49. An internal combustion engine having an intake passage (C-14) in which a throttling element (C-17) is pivotally supported within an adjustment angle range (C-α), wherein, An operating device (C-29) is provided for adjusting the position (C-γ) of the throttling element (C-17) by an operator within the adjustment angle range (C-α), including an actuator (C-21) configured to pivot the throttling element (C-17) in the closing direction (C-32) to reduce the free flow cross-section of the intake passage (C-14), and a control device (C-20) configured to operate the actuator (C-21), wherein, in The control device (C-20) stores a first control method (C-41) for the actuator (C-21), wherein the first control method (C-41) is configured to control the actuator (C-21) to close the throttling element (C-17) when a first limit value (C-g1) of the speed standard is exceeded, wherein the first control method (C-41) is configured to take the speed standard, taking the actual speed (Cn) of the internal combustion engine (C-1) as an input variable. The control device (C-20) is characterized by storing a second control method (C-42), wherein the second control method (C-42) is configured to control the actuator (C-21) such that the throttling element (C-17) is adjusted in the closed direction (C-32) within at least a portion of its adjustment angle range (C-α) in its adjustment angle range (C-β) without considering the actual speed (Cn) of the internal combustion engine (C-1) as an input variable, wherein the control device (C-20) is configured to control the actuator (C-21) according to the second control method (C-42) when a second limit value (C-g2) of the speed standard is exceeded.

50. The internal combustion engine according to claim 49, characterized in that, The actuator (C-21) includes an electric motor (C-31) and / or the internal combustion engine (C-1) has an exhaust muffler (C-23) with a catalytic converter (C-24).

51. A method for operating an internal combustion engine, - in, The internal combustion engine (D-201) has an intake passage (D-214) in which a throttling element (D-217) is pivotally supported within an adjustment angle range (D-α). - Wherein, the opening angle (D-γ) of the throttling element (D-217) within the adjustment angle range (D-α) can be adjusted by the operator via the operating device (D-229), and - An actuator (D-221) is provided to pivot the throttling element (D-217) in the closing direction (D-232) to reduce the free flow cross-section of the intake passage (D-214), and to pivot the throttling element (D-217) in the opening direction (D-234) to increase the free flow cross-section of the intake passage (D-214). - Includes a control device (D-220) configured to operate the actuator (D-221). - Wherein, at the rated final speed (Dn) soll The actuator (D-221) is operated above to close the throttling element (D-217) in order to adjust the rated final speed (Dn). soll ), - Wherein, when below the rated final speed (Dn) soll When the throttling element (D-217) is in the opening direction (D-234) of the throttling element (D-217), the actuator (D-221) is operated within at least one portion of the angle range (D-β) of the adjustment angle range (D-α). Wherein, when the actuator (D-221) adjusts the throttling element (D-217) in the opening direction (D-234) after the speed is below the first speed limit (D-n1), the adjustment speed of the throttling element (D-217) is at least twice the adjustment speed of the throttling element (D-217) when the actuator (D-221) adjusts it in the opening direction (D-234) above the first speed limit (D-n1).

52. The method according to claim 51, characterized in that, When the actuator (D-221) adjusts the throttling element (D-217) in the opening direction (D-234) below the first speed limit (D-n1), the adjustment speed of the throttling element (D-217) is 2 to 10 times that of the adjustment speed of the throttling element (D-217) when the actuator (D-221) adjusts it in the opening direction (D-234) above the first speed limit (D-n1).

53. The method according to claim 51 or 52, characterized in that, When the speed is below the second speed limit (D-n2), the actuator (D-221) is deactivated, thereby adjusting the throttling element (D-217) to a position corresponding to the opening angle (D-γ), which is set by the operator via the control device (D-229), wherein the second speed limit (D-n2) is below the first speed limit (D-n1).

54. The method according to any one of claims 51 to 53, characterized in that, The first speed limit (D-n1) is located at the rated final speed (Dn) of the internal combustion engine. soll Below 500 U / min to 3,000 U / min, especially 500 U / min to 2,000 U / min.

55. A working apparatus with an internal combustion engine, said internal combustion engine being configured to be operated by the method according to any one of claims 51 to 54.

56. The working apparatus according to claim 55, characterized in that, The working instrument is a cutting machine.

57. The working apparatus according to claim 55 or 56, characterized in that, The actuator (D-221) includes an electric motor (D-231).

58. The working apparatus according to any one of claims 55 to 57, characterized in that, The throttling element (D-217) is a throttling gate.

59. The working apparatus according to any one of claims 55 to 58, characterized in that, The rated final speed (Dn) soll The internal combustion engine (D-201) is stored in the control device (D-220).

60. A method for operating an internal combustion engine (E-1) with cylinder (E-2), wherein, A combustion chamber (E-3) is constructed in the cylinder (E-2). The internal combustion engine has an intake passage (E-14) for supplying air, a throttling element (E-17) arranged in the intake passage (E-14), and an actuator (E-21) configured to adjust the throttling element (E-17) in the opening direction (E-32) to increase the free flow cross-section of the intake passage (E-14) and in the closing direction (E-34) to decrease the free flow cross-section of the intake passage (E-14) to set a desired speed. The engine also includes a device for supplying fuel. The method includes the following steps: (Ea) Determine whether an unburned engine cycle has occurred in the combustion chamber (E-3). (Eb) When an engine cycle without combustion is identified, reduce the amount of fuel supplied. (Ec) Evaluate the response of the actuator (E-21). (Ed) If the actuator (E-21) adjusts the throttling element (E-17) in the opening direction (E-34) in response to a reduction in the amount of fuel supplied, the amount of fuel supplied is increased.

61. The method according to claim 60, characterized in that, In step (Ed), the fuel quantity is increased to a greater amount than the fuel quantity supplied before the fuel quantity was reduced in step (Eb).

62. The method according to claim 60 or 61, characterized in that, The internal combustion engine (E-1) is a two-stroke engine.

63. The method according to claim 62, characterized in that, Whether the two-stroke engine operates as a four-stroke engine is determined based on the engine cycle in which no combustion occurs in the combustion chamber (E-3).

64. The method according to claim 63, characterized in that, To identify the four-stroke operation, the pressure (Ep) in the crankcase (E-4) is evaluated.

65. The method according to claim 64, characterized in that, In order to identify the four-stroke operation, the speed of the internal combustion engine (E-1) is evaluated.

66. The method according to any one of claims 60 to 65, characterized in that, The fuel is supplied to the intake passage (E-14) or to the crankcase (E-4) of the two-stroke engine.

67. The method according to any one of claims 60 to 66, characterized in that, The internal combustion engine (E-1) includes a control device (E-20), and in step (Ea), the control device (E-20) determines whether an unburned engine cycle has occurred in the combustion chamber (E-3).

68. The method according to any one of claims 60 to 67, characterized in that, When evaluating the response of the actuator (E-21) in step (Eb), the rotation direction of the actuator (E-21) is detected.

69. The method according to any one of claims 60 to 68, characterized in that, When evaluating the response of the actuator (E-21) in step (Eb), the position of the throttling element (E-17) is detected.

70. An internal combustion engine having cylinder (E-2), wherein, The cylinder (E-2) is configured with a combustion chamber (E-3), an intake passage (E-14) for supplying air, a throttling element (E-17) arranged in the intake passage (E-14), an actuator (E-21) configured to adjust the throttling element (E-17) in an opening direction (E-32) for increasing the free flow cross-section of the intake passage (E-14) and in a closing direction (E-34) for decreasing the free flow cross-section of the intake passage (E-14) to set a desired speed, and a device for supplying fuel, wherein the internal combustion engine is configured to perform the method according to any one of claims 60 to 69.

71. The internal combustion engine according to claim 70, characterized in that, The internal combustion engine (E-1) includes a control device (E-20) configured to operate the actuator (E-21).

72. The internal combustion engine according to claim 70 or 71, characterized in that, The internal combustion engine (E-1) is a two-stroke engine, wherein the combustion chamber (E-3) is defined by a piston (E-5), which rotatably drives a crankshaft (E-7) supported in a crankcase (E-4) of the internal combustion engine (E-1), wherein an intake passage (E-14) supplies air to the crankcase (E-4), wherein the crankcase (E-4) is fluidly connected to the combustion chamber (E-3) at at least one predetermined position of the piston (E-5), wherein the internal combustion engine (E-1) has a pressure sensor (E-36) for determining the pressure (Ep) in the crankcase (E-4), and wherein a fuel supply device supplies fuel to the intake passage (E-14) or the crankcase (E-4).

73. A carburetor comprising a carburetor housing (F-10) and a throttle valve (F-4), - Wherein, the throttle valve (F-4) is held at the rotatably supported throttle valve shaft (F-3), - Furthermore, the throttle valve (F-4) occupies the idle position (F-14) in the first rotation position and the terminal position in the second rotation position. - And includes a switch (F-17) adapted to output at least one output signal (F-18) from a preset rotational position of the throttle valve (F-4) with respect to the full-load position (F-24) of the throttle valve (F-4). Its features are, - The preset rotation position of the throttle valve (F-4) is located before the terminal position of the throttle valve (F-4). - The preset rotation position is located before the end position of the throttle valve (F-4) with a rotation angle of 5° to 12° (F-DW). - And at least once, the output signal (F-18) is issued at the preset rotation position before the end position of the throttle valve (F-4) for the full load position (F-24) of the throttle valve (F-4).

74. The carburetor according to claim 73, characterized in that, At a rotation angle (F-DW) between 7° and 10° before the end position of the throttle valve (F-4), especially when the rotation angle (F-DW) is between 8° and 9°, the output signal (F-18) is issued at least once for the full load position (F-24) of the throttle valve (F-4).

75. The carburetor according to any one of claims 73 to 74, characterized in that, The throttle valve shaft (F-3) is supported in the carburetor housing (F-10), and the switch (F-17) is held in the carburetor housing (F-10).

76. The carburetor according to any one of claims 73 to 75, characterized in that, The switch (F-17) has a closed contact consisting of two contact elements (F-51, 61).

77. The carburetor according to any one of claims 73 to 76, characterized in that, The switch (F-17) is formed by a first electrical contact element (F-51) and a second electrical contact element (F-61), wherein the contact element (F-61) is formed by the throttle valve shaft (F-4).

78. The carburetor according to claim 77, characterized in that, The first electrical contact element (F-51) is held in a component (F-31) to be installed in the carburetor housing (F-10), a shaft section (F-33) of the throttle valve shaft (F-3) extends into the component, and the shaft section (F-33) of the throttle valve shaft (F-3) extending into the component (F-31) forms the second electrical contact element (F-61).

79. The carburetor according to claim 78, characterized in that, The throttle valve shaft (F-4) has a control edge (F-37) that forms the second mechanical contact element (F-61).

80. The carburetor according to claim 79, characterized in that, The control edge (F-37) is formed by a chamfer installed at the throttle valve shaft (F-3).

81. The carburetor according to claim 79 or 80, characterized in that, At the preset rotation position of the throttle valve shaft (F-3), the control edge (F-37) of the throttle valve shaft (F-3) abuts against the first contact element (F-51) located in the component (F-31) and closes the electrical contact of the switch (F-17).

82. The carburetor according to any one of claims 73 to 81, characterized in that, The throttle valve shaft (F-3) and / or the carburetor housing (F-10) are configured as electrical conductors.

83. A carburetor, particularly a carburetor according to any one of claims 73 to 82, comprising a carburetor housing (F-10) and an intake passage (F-2) with a throttle valve (F-4), the throttle valve being held at a throttle valve shaft (F-3) and having a switch (F-17) adapted to close electrical contact between a first contact element (F-51) and a second contact element (F-61) at a predetermined rotational position of the throttle valve (F-4), wherein, The first contact element (F-51) is connected to the lead signal line (F-19) via at least one diode (F-112, F-122), and the first contact element (F-51) is held in a socket (F-59), and at least one electrical connection wire (F-46) of the diode (F-112) is held in another socket (F-50), wherein the sockets (F-50, F-59) are adjacent to each other and geometrically intersecting such that the connection wire (F-46) held in one of the sockets (F-50) is electrically contacted with the contact element (F-51) located in the other socket (F-59) in the intersecting area.

84. The carburetor according to claim 83, characterized in that, The housing (F-30) of the switch (F-17) contains two diodes (F-112, F-122) inserted into diode sockets (F-124, F-125), and the connecting wires of the two diodes located at the bottom of the sockets (F-124, F-125) are in electrical contact with each other.

85. A circuit assembly for a switch (F-11, F-17) arranged in a carburetor, particularly in a carburetor according to any one of claims 73 to 84, comprising a carburetor housing (F-10) and an intake passage (F-2), and an electrically operated fuel valve (F-8) opening into the intake passage (F-2), and having a choke (F-6) held in the intake passage (F-2) by a choke shaft (F-5), and having a first switch (F-11) adapted to give the choke (F-6) a preset rotational position, wherein, The first switch (F-11) is arranged in a first parallel branch (F-101) relative to the electric fuel valve (F-8), and a diode (F-111) is arranged in series with the switch (F-11) in the first parallel branch (F-101), and a throttle valve (F-4) is arranged in the intake passage (F-2), wherein the throttle valve (F-4) is held at the throttle valve shaft (F-3), and a second switch (F-17) is arranged to give a preset rotation position of the throttle valve (F-4), wherein the second switch (F-17) is arranged in a second parallel branch (F-102) relative to the electric fuel valve (F-8), and a first diode (F-112) and a second diode (F-122) are arranged in series with the second switch (F-17) in the second parallel branch (F-102).

86. The circuit assembly according to claim 85, characterized in that, The parallel branches (F-101, F-102) are equipped with diodes of different structural types (F-111, F-112, F-122), especially Zener diodes, Schottky diodes, LED diodes, rectifier diodes or similar diodes.

87. A two-stroke engine with a carburetor according to any one of claims 73 to 86.

88. A switch for detecting the rotational position of a shaft (G-50), comprising a control edge (G-22) for actuating contacts that moves with said shaft (G-50), wherein, The contacts are arranged in the switch housing (G-21) of the switch (G-20), and the switch housing (G-21) is adjustablely supported about a pivot axis (G-23), and has an adjustable stop (G-40) for fixing the position of the pivotable switch housing (G-21). The switch housing (G-21) is characterized by having a spring elastic element (G-30) acting on it, the spring elastic element (G-30) being pre-tightened and applying a pre-tightening force (G-35) to the switch housing (G-21), and the switch housing (G-21) being held at the stop portion (G-40) by means of the pre-tightening force (G-35).

89. The switch according to claim 88, characterized in that, The spring elastic element (G-30) is a spring, especially a torsion spring (G-31).

90. The switch according to claim 88 or 89, characterized in that, The pivot axis (G-23) of the switch housing is the rotation axis (G-11) of the shaft (G-50).

91. The switch according to any one of claims 88 to 90, characterized in that, The shaft (G-50) carries the valve (G-9) of the carburetor (G-1), the shaft (G-50) is rotatably supported in the carburetor housing (G-2) of the carburetor (G-1), and the valve (G-9) is located in the flow channel (G-3) of the carburetor (G-1) and controls the channel cross-section of the flow channel (G-3).

92. The switch according to claim 91, characterized in that, The shaft (G-50) is a throttle shaft (G-10) and the valve is a throttle valve (G-9) of the carburetor (G-1).

93. The switch according to claim 91 or 92, characterized in that, A spring (G-12) acts at the throttle valve shaft (G-10), and the throttle valve shaft (G-10) can overcome the spring force of the spring (G-12) and be adjusted to the open position of the throttle valve (G-9).

94. The switch according to claim 93, characterized in that, The preload force (G-35) applied by the spring elastic element (G-30) is greater than the spring force acting on the throttle valve shaft (G-10) through the spring (G-12).

95. The switch according to claim 88, characterized in that, The switch housing (G-21) can be fixed in a rotation-resistant manner by means of fastening screws (G-28).

96. A method for adjusting a switch for detecting the full-load position of a throttle shaft (G-50) of a carburetor (G-1), said switch having a control edge (G-22) for operating contacts that moves with said throttle shaft (G-50), wherein, The contacts are arranged in the switch housing (G-21) of the switch (G-20), and the switch housing (G-21) is adjustablely supported about a pivot axis (G-23), and has an adjustable stop (G-40) for fixing the position of the pivotable switch housing (G-21). Its features are, When assembling the switch housing (G-21), first pivot it to the stop (G-40). Screw in or out the stop screw (G-41) to adjust the rotational position of the switch housing (G-21) that rests against the stop portion (G-40). Continue screwing in or out the stop screw (G-41) until the switch housing (G-21) is positioned such that the switch signal is reliably triggered at the full load position of the throttle shaft (G-50).

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