Hand-guided working instruments with cutting tools and a braking mechanism for the cutting tools

Abstract

The present invention relates to a hand-guided working instrument having a cutting tool and a braking mechanism for the cutting tool, the hand-guided working instrument having a cutting tool and a braking mechanism (15) for the cutting tool. The braking mechanism (15) has an actuating element that acts on a braking element of the braking mechanism (15). The actuating element is movable between a fixed state (41) and a released state (40), in which the cutting tool is not braked, and in the released state the braking element brakes the cutting tool. To fix the actuating element in the fixed state (41), an electromagnet (33) with a yoke (34) and a coil (35) is provided, which works in conjunction with an armature (36) at the actuating element. The armature (36) is pivotally supported at an armature bolt (55) via a pivot joint (50) about at least one pivot axis (51, 52, 53). A guide (60) is provided, which guides the armature (36) in the transverse (38) of the cantilever (7) of the working instrument relative to the yoke (34) in the fixed state (41) of the operating element by a guide member connected to the armature (36) and a guide member connected to the yoke (34).

Description

Technical Field

[0001] The present invention relates to a hand-guided working instrument with a cutting tool and a braking mechanism for the cutting tool. Background Technology

[0002] A cutting machine is known from WO2015 / 180829 A1. This cutting machine has an auslegre fixed to a motor housing, where an electromagnet for a braking mechanism is fixed. The actuating element of the braking mechanism, a lever, is supported at a distance from the electromagnet and carries an armature that acts in conjunction with the electromagnet. In a variant embodiment of WO 2015 / 180829 A1, the armature, held at the actuating element, is fixed thereto via a damping element (or buffer element). Thus, the armature can move slightly relative to the actuating element to compensate for tolerances. Summary of the Invention

[0003] The present invention aims to create a hand-guided working instrument with a cutting tool and a braking mechanism, wherein the braking is not accidentally triggered even under adverse working conditions.

[0004] As has been demonstrated, vibrations occur during operation, causing significant relative movement between the electromagnet and the operating element. The armature, fixed via damping elements as described in the prior art, even allows tilting of the armature and armature bolt relative to the operating element. However, when relative movement occurs between the operating element and the electromagnet, this tilting causes the armature to be angled relative to the electromagnet, resulting in a significant reduction in the holding force exerted by the electromagnet on the armature. Due to this angled armature relative to the electromagnet, the armature is released by the electromagnet, and the operating element is adjusted to its released state, in which the braking element brakes the tool. This causes undesirable interruptions in the workflow, which are disruptive to the operator and further lead to increased wear on the braking element.

[0005] In this invention, the armature is oscillatingly supported on the armature bolt via a sway joint about at least one sway axis. Thus, the armature can oscillate relative to the armature bolt. The tilting of the armature bolt caused by the relative movement between the electromagnet and the operating element is not necessarily caused by the sway joint. The armature maintains its orientation relative to the electromagnet even during lateral movement of the electromagnet. The armature is prevented from being released by the electromagnet. This is thus avoided in a simple way, preventing the armature from being tilted relative to the electromagnet and thereby reducing the holding force exerted by the electromagnet on the armature.

[0006] In an advantageous design, the armature is in a fixed state (where the braking element does not brake the tool) abutting against the contact surface of the yoke, and at least one swing axis is parallel to the contact surface. Here, the swing axis is the swing axis of the swing joint, through which the armature is swingably supported at the armature bolt. Thus, the tilt of the armature bolt can be compensated by the reverse swing of the armature relative to the armature bolt about the swing axis, and the orientation of the armature is maintained. However, it may also be advantageous to arrange the swing axis perpendicular to the contact surface, especially in the longitudinal direction of the armature bolt, in order to prevent the armature from twisting relative to the yoke of the electromagnet.

[0007] The working instrument is, in particular, a cutting machine with a cantilever. Advantageously, the operating element is supported in a first region of the cantilever, while the electromagnet is fixed in a second region of the cantilever. The two regions are advantageously spaced apart. Specifically, the first region is arranged closer to the drive shaft of the drive motor and further away from the driven shaft, which corresponds to the rotation axis of the tool. The second region is advantageously arranged closer to the driven shaft and further away from the drive shaft. The vibrations in the two regions may differ. Here, the first region, which is further away from the rotation axis of the driven shaft and closer to the drive shaft and more so than the second region, vibrates less than the second region. This difference in vibration between the cantilever in the support of the operating element and in the region of the electromagnet induces relative movement between the electromagnet and the operating element carrying the armature.

[0008] Due to vibration or similar factors, the yoke can be moved relative to the actuating element in a direction parallel to the contact surface. This movement is associated with the swing of the armature bolt around a swing axis at a certain swing angle. The swing angle is configured to be coordinated with the tilt angle at which the armature can tilt relative to the armature bolt about the swing axis, and at this tilt angle relative to the actuating element during the yoke's maximum movement. Here, the swing angle of the armature relative to the armature bolt is advantageously at least as large as the tilt angle of the armature bolt during the yoke and actuating element's maximum relative movement. Thus, the maximum tilt caused by the armature bolt during operation can be completely compensated by the swing of the swing joint, thereby maintaining the armature's orientation relative to the electromagnet's yoke even when the armature bolt is at its maximum tilt.

[0009] Advantageously, the yoke has free space therein accommodating the sections of the armature bolt and the sway joint that extend beyond the abutment surface. Here, the sections extending beyond the abutment surface are sections of the armature bolt and / or the sway joint that extend onto a side of the abutment surface, where the yoke is also arranged. Here, the sections of the armature bolt or the sway joint, or the sections of both the armature bolt and the sway joint, can extend beyond the abutment surface. The sections of the armature bolt and / or the sway joint extending beyond the abutment surface are fully accommodated in the free space, especially for any possible tilt angle of the armature bolt relative to the operating element. Because this free space prevents the sections of the armature bolt and / or the sway joint extending beyond the abutment surface from contacting the yoke in any position where no armature bolt is positioned, the yoke is prevented from becoming loose from the armature due to the sections of the armature bolt and / or the sway joint extending beyond the end face of the armature.

[0010] Advantageously, the actuating element is a rocker arm. Advantageously, at least one swing axis of the armature relative to the armature bolt lies in a plane arranged perpendicular to the swing axis of the rocker arm. The relative movement of the yoke and armature is mostly achieved in the direction of the swing axis of the rocker arm. Movement in the direction of motion of the rocker arm, i.e., in the circumferential direction relative to the swing axis, can be compensated by the rocker arm itself. The swing motion can also be compensated laterally by the arrangement of at least one swing axis in a plane perpendicular to the swing axis of the rocker arm. Preferably, at least one swing axis lies in a plane perpendicular to the swing axis of the rocker arm and parallel to the contact surface.

[0011] Advantageously, the oscillating joint has a curved support surface. In a particularly advantageous design, this support surface is partially spherical. However, a cylindrical support surface or a support surface that is otherwise curved may also be advantageous. The ratio of the radius of the support surface to the thickness of the armature is advantageously 0.3 to 2. The diameter of the support surface is correspondingly advantageously at least as large as the thickness of the armature and, in preferred designs, even larger. In a particularly advantageous design, the radius of the support surface is 0.4 to 1, especially 0.4 to 0.8, relative to the thickness of the armature. This results in a relatively large surface area of ​​the support surface and a simple structure. Advantageously, the diameter of the support surface is larger than the diameter of the armature bolt, especially larger than the diameter of the opening through which the armature bolt extends in the armature. Thus, the support surface can be constructed immediately adjacent to the armature in an area that is radially outside the opening through which the bearing bolt extends, resulting in a simple and compact structure. The associated support surface of the armature extends particularly arched or conical.

[0012] If the swing axis of the armature is located on the side of the armature facing the yoke, a compact structure is also achieved. Advantageously, the distance between the swing axis and the contact surface is small. The distance between the swing axis and the contact surface is advantageously smaller than the radius of the support surface. Thus, the swing joint is advantageously partially immersed in the armature. The swing joint has a curved shape only on its side facing the armature. Thus, the extension of the swing joint from the armature through the contact surface can be kept small. The swing joint is advantageously only slightly immersed in the armature, and the thickness of the armature is not reduced or is only slightly reduced through the swing joint without changing the overall structural size. Thus, the magnetic flux is only slightly disturbed.

[0013] Advantageously, the armature bolt extends through the fixed section of the armature and the actuating element. The armature bolt is advantageously oscillating relative to the actuating element. The tilting of the armature caused by the tilting of the armature bolt relative to the actuating element is advantageously compensated at least partially, and especially entirely, by the oscillating joint between the armature and the armature bolt.

[0014] Another object of the present invention is to limit the relative movement between the yoke and the armature in the case of a cutting machine with a cantilever (where the yoke is fixed).

[0015] This objective is achieved by a hand-guided working instrument with a cutting tool and a braking mechanism for the cutting tool, wherein the braking mechanism has an actuating element that acts on the braking element of the braking mechanism, wherein the actuating element is movable between a fixed state in which the braking element does not brake the cutting tool and a released state in which the braking element brakes the cutting tool, wherein the braking mechanism has an electromagnet for fixing the actuating element in the fixed state, wherein the electromagnet includes a yoke and a coil, and wherein the electromagnet works in conjunction with an armature, wherein the armature is held at the actuating element by an armature bolt, wherein the working instrument is a A cutting machine has a cantilever, wherein a cutting disc constituting a cutting tool is rotatably supported on the cantilever about a rotation axis, wherein the cantilever has a longitudinal direction in which a maximum extension of the cantilever perpendicular to the rotation axis is present, and wherein the cantilever has a transverse direction extending parallel to the rotation axis and a vertical direction extending perpendicular to both the transverse and longitudinal directions, wherein a yoke is fixed at the cantilever, and wherein a guide portion is provided including a first guide member connected to an armature and a second guide member connected to the yoke, wherein the first guide member and the second guide member work together in the fixed state of the operating element and guide the armature in the transverse direction of the cantilever relative to the yoke.

[0016] To limit relative movement in the lateral direction of the cantilever, a guide portion is provided, comprising a first guide connected to the armature and a second guide connected to the yoke. In the fixed state of the operating element, the first and second guides work together to guide the armature relative to the yoke in the lateral direction of the cantilever. This allows for a simple way to limit the relative movement of the yoke and armature in the lateral direction of the cantilever. The invention is independent of the construction of a swing joint via which the armature relative to the armature bolt is swingably supported, and the invention relates to an inventive idea independent of this. Here, the lateral direction of the cantilever is advantageously parallel to the direction of the drive or driven shaft of the belt drive arranged in the cantilever. This lateral direction is advantageously parallel to the rotation axis of the tool. The lateral extension of the cantilever is generally small. Therefore, the cantilever is particularly prone to vibration in the lateral direction. The lateral extension of the cantilever is significantly smaller than its longitudinal extension.

[0017] The armature and yoke can be positioned relative to each other in a simple manner via this guide. In the event of lateral vibration of the cantilever, the operating elements can be guided together via the guide, particularly moving together due to their inherent elasticity. It can be configured to take measures to reduce wear on one or both guides. This ensures that, in the event of vibration during operation, little or no wear occurs at the guides.

[0018] If one of the guides is a pin and the other guide has an opening, a simple structure is obtained where the pin extends into the opening in the fixed state of the actuating element. This opening is preferably configured as an elongated hole. In the fixed state of the actuating element, it is advantageously arranged that a slot is formed in the transverse direction of the cantilever. The slot in the transverse direction of the cantilever is advantageously chosen such that the relative movement in the transverse direction can be fully compensated by the oscillating joint between the armature and the armature bolt. Advantageously, a slot also exists in the longitudinal direction of the cantilever between the pin and the edge of the opening. This is particularly advantageous because the actuating element is configured as a rocker arm, and movement of the pin into the opening is possible via this slot in the longitudinal direction of the cantilever.

[0019] Advantageously, the guides do not act together throughout the entire operating stroke. The guides act together and are engaged with each other, at least in the fixed state of the operating element. The loosening of the armature, located on the operating element and magnetically connected to the electromagnet, due to the lateral vibration of the electromagnet, is reliably prevented by the engaged guides. In an advantageous design, the guides are arranged separately from each other in the loose state of the operating element. In the loose state of the operating element, i.e., when the armature and electromagnet are not magnetically connected, the relative orientation of the armature and electromagnet is secondary, thus eliminating the joint action of the guides and the lateral positioning of the armature and yoke. Preferably, the guides act together and guide the armature relative to the yoke only after at least half of the adjustment stroke from the loose to the fixed state. This allows for a relatively short pin construction and results in a simple structure. The adjustment stroke is the distance traveled by one of the guides relative to the other during the adjustment from the loose to the fixed state.

[0020] Advantageously, at least one of the guide members has an inlet ramp. This ensures, in a simple manner, that even when the guide members are arranged far apart from each other in the released state of the operating element, they collide to form the guide portion when the operating element is adjusted to the fixed state. In a simple design, the inlet ramp is constructed at the pin of the guide portion. This allows for a relatively large inlet ramp in a simple manner. The inlet ramp is preferably constructed as a tapered section of the pin. The width of the inlet ramp advantageously corresponds at least to the travel of the guide members relative to each other in the lateral direction.

[0021] The control element, particularly the lever, has a distance of at least 5 cm between its swing axis and the fixed point of the electromagnet at the cantilever. In a preferred design, this distance is at least 8 cm. Especially in cases where the distance between the swing axis and the fixed point of the electromagnet is relatively large, the guide portion between the control element and the electromagnet is advantageous because the relatively large length of the lever allows for a larger relative motion of the cantilever relative to the free end of the lever.

[0022] Advantageously, the braking mechanism has an elbow-lever assembly (or crank-lever assembly, Kniehebelanordnung) comprising a first lever and a second lever. The first lever is pivotally supported relative to the actuating element about a first swing axis, while the second lever is pivotally supported at the first lever about a second swing axis. The second lever is supported at a third swing axis at a third lever, which acts on the braking element. To achieve actuation of the braking mechanism with a small actuating force, the elbow-lever assembly is configured to be in an over-pressure position neither in the released nor fixed state. For this purpose, the first and third swing axes are located in the rocker arm plane, while the second swing axis is arranged on the same side of the rocker arm plane in both the released and fixed states. Thus, over-pressure of the second swing axis through the dead center is unnecessary, allowing the pre-tensioning braking mechanism's trigger spring to be applied relatively weakly.

[0023] It is advantageous for a rocker joint to be constructed of a shape-stable material. In particular, the rocker joint is not constructed as a damping element. Attached Figure Description

[0024] The embodiments of the present invention will now be described with reference to the accompanying drawings. Wherein:

[0025] Figure 1 A side view of a partial cross-section of the cutting machine is shown, where the cut plane is located within a cantilever.

[0026] Figure 2 Showing the passage according to Figure 1 A schematic cross-sectional view of the driver of the cutting machine.

[0027] Figure 3 Shown in Figure 1 Arrow III in the direction is towards the direction according to Figure 1 A top view of the cutting machine.

[0028] Figure 4 Showing according to Figure 1 An enlarged view of the cross-section of the cantilever of the cutting machine, showing the area.

[0029] Figure 5 A side view of the cantilever and protective cover is shown, in which some components of the cantilever are not shown.

[0030] Figure 6 The display shows the action of the lever in the released state. Figure 5 An enlarged cross-sectional view of the area of ​​the pendulum rod.

[0031] Figure 7 The diagram shows the basis for the rocker arm in a stationary state. Figure 6 The area

[0032] Figure 8 A top view showing a partial cross-section facing the cutter is displayed.

[0033] Figure 9 and Figure 10 A perspective view of the pendulum and the components that work together with it is shown.

[0034] Figure 11 The cross-section shown is the cross-section passing through the electromagnet and the swing arm in the transverse direction of the cutting machine.

[0035] Figure 12 The diagram shows partial cross-sections of the electromagnet, armature, and lever.

[0036] Figure 13 The diagram shows the path through the electromagnet, armature, and armature bolt. Figure 12 A diagram of a partial cross-section.

[0037] Figure 14 A schematic illustration of an embodiment of the present invention is shown.

[0038] Figure 15 A schematic diagram showing an arrangement based on existing technology is displayed.

[0039] Figure 16 A schematic diagram of the arrangement according to the present invention is shown. Detailed Implementation

[0040] Figure 1 An example of a hand-guided working instrument is shown: a cutting machine 1. The cutting machine 1 has a housing 2, on which a handle 3 and a bügelgriff 6 are fixed for guiding the cutting machine 1 in operation. In this embodiment, a throttle lever 4 and a throttle lever lock 5 are provided at the handle 3 located on the top surface of the housing 2 for operating a drive motor 10 arranged in the housing 2. The handle 3 can also be implemented as a rear handle. The drive motor 10 is preferably an internal combustion engine, especially a single-cylinder two-stroke motor. A starting device 11 is provided for starting the drive motor 1; in this embodiment, a pull-cord starter is provided. Alternatively, the drive motor 10 can be configured as an electric motor, preferably powered by a battery.

[0041] The cutting machine 1 has a cantilever 7, which in this embodiment is fixed to the housing 2. At the free end of the cantilever 7, a cutting disc 8 is rotatably supported about a rotation axis 58. The cutting disc 8 is the cutting tool of the cutting machine 1 and is driven by a drive motor 10 via a belt drive. Another driver for the cutting disc 8 may also be advantageous. In this embodiment, the belt drive is implemented as a two-stage belt drive and includes a first drive belt 12 and a second drive belt 13. A tension pulley 14 is provided to tension the drive belts 12 and 13, wherein... Figure 1 One of the tensioning pulleys is shown in the image. The belt drive is configured as a reduction gear, so that the rotational speed of the cutting disc 8 is less than that of the drive motor 10.

[0042] The cutting disc 8 is covered by a protective cover 9 on a portion of its periphery. During operation, a large amount of dust is generated when the cutting disc 8 is used to cut rock. A liquid supply device, particularly a water supply device, is provided to collect the dust and cool the cutting disc 8. The liquid supply device includes a liquid inlet 100 for connection to an external liquid delivery device. The liquid inlet 100 is connected via a liquid pipe 101 to at least one delivery valve 106 at the protective cover 9. An electrically controlled valve 102 is provided to control the amount of liquid delivered. The amount of liquid to be delivered, as desired by the operator, can be controlled via an operation panel 107 on the top surface of the housing 2. Figure 3 The valve 102 is adjusted accordingly. A control mechanism 103 is provided, which correspondingly operates the valve 102. In this embodiment, the control mechanism 103 is arranged on the bottom surface of the housing 2. In this embodiment, the control mechanism 103 is not arranged inside the housing 2, but is arranged outside the housing 2 and covered downwards by a separate cover plate 104. The control mechanism 103 is advantageously cast, thereby achieving double protection from contaminants or liquids through casting and the cover plate 104.

[0043] The cover 104 is advantageously secured to the housing 2 via a snap-fit ​​connection and / or a threaded connection. The control mechanism 103 is advantageously positioned at a distance within the cover 104. The defined distance between the control mechanism 103 and the cover 104 can be achieved, for example, via ribs between the control mechanism 103 and the cover 104. In a preferred design, the cover 104 has at least one outlet on its bottom surface, which is positioned below during normal operation, allowing moisture or contaminants to drain from the cover 104. It may be advantageous that the control mechanism 103 is supported relative to the cover 104 via at least one damping element.

[0044] An ignition module 105 is advantageously provided for controlling the drive motor 10, which is constructed separately from the control mechanism 103 and is particularly located in the upper region of the housing 2, within the drive motor 10 itself. Another arrangement of the ignition module 105 or another control mechanism for operating the drive motor 10 may also be advantageous.

[0045] The cutting machine 1 has a braking device 15. A speed sensor is advantageously provided to trigger the braking mechanism 15. In this embodiment, the speed sensor is also arranged in the control mechanism 103. Here, the speed sensor is advantageously oriented relative to the rotation axis 58 of the cutting disc 8. Preferably, the measuring axis of the speed sensor is parallel to the rotation axis 58.

[0046] The cantilever 7 has a longitudinal direction 37, which in this embodiment forms the connecting line between the drive shaft and the driven shaft of the belt drive in a side view in the direction of the drive shaft. In this embodiment, the drive shaft is connected to the crankshaft 24 of the drive motor 10. Figure 2 The driven shaft is aligned with the rotation axis 25 of the cutting disc 8, while the driven shaft is the rotation axis 58 of the cutting disc 8. A cantilever 7 has its maximum extension perpendicular to the rotation axis 58 along the longitudinal direction 37. The cantilever 7 has a vertical direction 39, which is perpendicular to the longitudinal direction 37 and oriented perpendicular to the rotation axes 25 and 58. Furthermore, the cantilever 7 has a transverse direction 38, which... Figure 1 The orientation is perpendicular to the plane of the drawing and in Figure 2 The middle section is displayed. Horizontal section 38 extends perpendicularly to vertical section 37 and perpendicularly to vertical section 39.

[0047] Figure 2 The structure of the drive unit of the cutting machine 1 is specifically shown. The drive motor 10 has a cylinder 21 in which a combustion chamber 22 is constructed. The combustion chamber 22 is confined by a piston 23, which drives the crankshaft 24 to rotate about a rotation axis 25. A fan impeller 26 for supplying cooling air is arranged on one side of the drive motor 10. In this embodiment, a centrifugal clutch 19 is arranged on the opposite side, through which the crankshaft 24 is connected to a belt-driven drive disc 18. The centrifugal clutch 19 has a clutch drum 20, and a brake band 17 of a braking mechanism 15 is arranged on its outer periphery. The braking mechanism 15 acts on the clutch drum 20 of the centrifugal clutch 19, i.e., on the driven side of the centrifugal clutch 19. A starting device 11 is arranged on the outer side of the cantilever 7.

[0048] like Figure 1 As shown, a control lever 16 is arranged on the top surface of the cantilever 7 for releasing the brake device 15, as will be further explained below.

[0049] The arrangement of joystick 16 is still in place. Figure 3 It is displayed in the middle. Furthermore... Figure 3The orientation of the transverse direction 38, which is perpendicular to the longitudinal direction 37, is shown.

[0050] Figure 4 The design of the braking device 15 is further shown. The braking device 15 has a rocker arm 28. The rocker arm 28 constitutes the operating element of the braking device 15. Figure 4 The lever 28 is shown in the fixed state 41. The braking device 15 includes an electromagnet 33, which is fixed to the cantilever 7. At the lever 28, an armature 36 is arranged adjacent to the free end of the lever 28, which abuts against the electromagnet 33 in the fixed state 41 and is fixed to the electromagnet 33 by magnetic force. The lever 28 is held in the fixed state 41 by the electromagnet 33. In the fixed state 41, the brake band 17 is loosened and loosely abuts against the periphery of the clutch drum 20. Thus, when the drive motor 10 operates and drives the cutting disc 8 via belt drive... Figure 1 When the centrifugal clutch 19 ( Figure 2 They can be coupled.

[0051] The braking device 15 has an elbow assembly 31 that acts on the brake band 17. The elbow assembly 31 is used to move the lever 28 from the brake band 17. Figure 4 The fixed state 41 shown in the image swings to the position shown in the image. Figure 5 In the case of the released state 40 shown, the brake band 17 is pulled around the clutch drum 20, thereby braking the cutting disc 8. Figure 4 As shown, the elbow lever assembly 31 includes a lever 44, which is pivotally held at the lever 28 about a pivot axis 48. At one end of the lever 44, a trigger spring 32 is attached. Figure 4 At the second end covered by the lever 28, the brake band 17 is secured at one end. The second end of the brake band 17 is fixedly fastened relative to the housing. To tighten the brake band 17 around the clutch drum 20, the lever 44... Figure 4 The diagram shows that the rocker arm 28 must swing counterclockwise around the swing axis 48. At rod 44, rod 43 is oscillably supported around the swing axis 47 between the swing axis 48 and the engagement point of the trigger spring 32. At the second end of rod 43, rod 42 is oscillably supported around the swing axis 46. Rod 42 is oscillably supported at its other end around the swing axis 45. In this embodiment, the swing axis 45 is such that the rocker arm 28 is oscillably supported relative to the cantilever 7 around this swing axis. However, it can also be configured such that rod 42 is oscillably supported relative to the rocker arm 28 around a swing axis spaced from the swing axis 45. Swing axes 45, 46, 47, and 48 are parallel to each other. Swing axes 45 and 47 define the rocker arm plane 49. A swing axis 46 exists between swing axes 45 and 47, which constitutes an elbow joint. Swing axis 46 is in a fixed state 41 with a smaller gap relative to the rocker arm plane 49. Figure 4The belt-driven intermediate disc 64 can also be identified, around which the first drive belt 12 is guided.

[0052] To operate the braking mechanism 15, the electromagnet 33 is turned off. As a result, the armature 36 is released from the electromagnet 33, and the lever 28 swings to its position. Figure 5 and 6 The image shows the released state 40. In the fixed state 41, the elbow assembly 31 is pre-tightened, as shown. Figure 4 As shown. By placing the swing axis 46, where the levers 42 and 43 are connected to each other, and the trigger spring 32 at the attachment point at the lever 44 on opposite sides of the elbow plane 49, the force of the trigger spring 32 acts in the direction of adjustment toward the elbow assembly 31 and toward the released state 40. The electromagnet 33 reacts to this force in the fixed state 41. In the fixed state 41, the angle of transmission of the spring force to the elbow is reduced due to the almost extended elbow joint constructed at the axis 46, i.e., the magnetic force of the electromagnet 33 is sufficient to keep the lever 28 in the kinematically unstable fixed state 41 against the acting spring tension of the trigger spring 32.

[0053] If electromagnet 33 is turned off, spring 32 is triggered to adjust lever 44. Lever 44 is in the position of lever 28. Figure 6 The lever 28 slides down at the control contour 65, which is schematically shown in the diagram. Based on the orientation of the control contour 65, the lever 28 swings about the swing axis 45 to... Figure 5 and 6 In the released state 40 shown, the swing axis 46 is away from the elbow plane 49. The elbow joint is bent, and the trigger spring 32 swings the lever 44, thereby tensioning the brake band 17. Similarly, in the released state 40, the attachment points of the swing axis 46 and the trigger spring 32 at the lever 44 are on opposite sides of the elbow plane 49. In this embodiment, the swing axis 46 is always in a state independent of the state of the braking mechanism 15. Figure 4 The elbow assembly 31 is located on the side below the elbow plane 49 in the diagram. Therefore, the elbow joint operates non-lockingly, meaning it never presses against the opposite side of the elbow plane 49. There is no need for a return spring to unlock the elbow assembly 31. In the fixed state 41 of the lever 28, the elbow assembly 31 is held in its unstable orientation solely by means of the electromagnet 33.

[0054] exist Figure 5 The image also shows the driven disc 27 of the belt drive.

[0055] In order to release the braking mechanism 15 from the rocker arm 28 Figure 5 and 6 The released state 40 shown in the image (in which the brake band 17 is tightened around the clutch drum 20) is adjusted to the position shown in the image. Figure 4In the fixed state 41 shown (where the brake is not acting on the clutch drum 20), the operator swings the control lever 16 upwards. At the control lever 16 ( Figure 5 Hanging in the same place Figure 6 The control stick 29 is shown in the image. The control stick 29 is secured to the guide bolt 30 of the lever 28 and swings the lever 28 to the fixed state 41. The control stick 29 is secured with an elongated hole in the guide bolt 30, so that the control lever 16 can be moved relative to the lever 28 and can be returned to its starting position, while the brake device 15 is not returned to the released state 40 of the lever 28.

[0056] During operation, the cantilever 7 vibrates due to vibrations generated by the drive motor 10, particularly an internal combustion engine, and / or due to vibrations caused by the engagement of the cutting disc 8 with the workpiece. Based on its shape, the cantilever 7 is particularly prone to vibration in the transverse direction 38. Here, the extension of the cantilever 7 in the transverse direction 38 in this embodiment is smaller than its extension in the other spatial direction, especially smaller than its extension in the longitudinal direction 37. Due to the relatively small spatial extension of the cantilever 7 in the transverse direction 37 relative to its extension in the other spatial direction, the cantilever 7 is particularly prone to vibration in the transverse direction 37. By fixing the armature 36 and the electromagnet 33 to the cantilever 7 at a distance from each other in the longitudinal direction 37, the armature 36 and the electromagnet 33 vibrate with different intensities. In this embodiment, the electromagnet 33 vibrates with an amplitude greater than that of the armature 36. Once the armature 36 can no longer follow the movement of the yoke 34, this relative movement in the transverse direction 38 causes the armature 36 to tilt relative to the yoke 34 of the electromagnet 33. Due to this tilt, the holding force of the electromagnet 33 may become too small to hold the lever 28 in the fixed state 41. A guide portion 60 is provided to limit this relative movement. The guide portion 60 is located in... Figure 7 and 8 The guide portion 60 is specifically shown. The guide portion 60 includes a pin 61 that extends through an opening 62 in the guide plate 66. In this embodiment, the guide plate 66 is L-shaped and fixed to the electromagnet 33. The opening 62 and the pin 61 restrict the relative movement of the electromagnet 33 relative to the armature 36 in the transverse direction 38.

[0057] exist Figure 7 The position of pin 61 in the loosened state 40 is indicated by a dashed line. For example... Figure 7 As shown, pin 61 is adjusted between the loosened state 40 and the fixed state 41 to adjust the stroke g. Figure 7 As also shown, when the pin 61 is adjusted from the loose state 40 to the fixed state 41, it only reaches the area of ​​the opening 62 approximately at the end of the swing stroke g. Figure 8In the middle, the pin 61 travels at least half its swing stroke g before reaching the area of ​​the guide plate 66. The pin 61 and the opening 62 constitute the guide of the guide portion 60. Similarly, another design with a guide can be provided. Figure 8 The same shows the operating profile 65 of the elbow lever assembly 31.

[0058] Figure 9 The design scheme of the guide section 60 is shown in detail. Figure 9 The arrangement consisting of an electromagnet 33, a rocker arm 28, and a lever 16 is shown, with the rocker arm 28 in a fixed state 41. An armature 36 rests against and is held by the yoke 34 of the electromagnet 33. A pin 61 extends into an opening 62. Here, the pin 61 has a gap h in the transverse direction 38. The gap h is relatively small. The opening 62 is constructed as an elongated hole, wherein the opening 62 has its minimum radial extension in the transverse direction 38. Perpendicular to the swing axis 45 of the rocker arm 28, the opening 32 has a significantly larger gap f relative to the pin 61. The gap f... Figure 9 The same is also schematically indicated. Advantageously, the gap h in the transverse direction 38 is 0.05 mm to 0.7 mm, especially to 0.5 mm. A gap h in the transverse direction 38 of 0.1 mm to 0.4 mm has proven to be particularly advantageous. The gap f in the longitudinal direction 37 is advantageously at least 1 mm, especially at least 2 mm, and is coordinated with the length of the pin 31 and the distance between the pin 31 and the swing axis 45.

[0059] like Figure 9 As also shown, the pin 61 has an entry ramp 77 in the form of a tapered section 73. Here, the taper is constructed relatively large and extends over more than half the diameter of the pin 61. This ensures that the pin 61 reaches the opening 62 and is as centered as possible within the opening 62, even with a lateral gap between the center of the pin 61 and the center of the opening 62. Measures to reduce wear due to vibrations occurring during operation can be provided at the pin 61 and / or the opening 62. For this purpose, the pin 61 may be hardened and / or the guide plate 66 may be implemented with increased thickness, at least in the region of the opening 62. Figure 9 As also shown, electromagnet 33 is connected to connector 67 via wire 68 for connection to a control mechanism. The control mechanism is preferably control mechanism 103, which also has a speed sensor so that electromagnet 33 can be released when the speed of the cutter 1 exceeds a predetermined value.

[0060] like Figure 10As shown, the swing axis 45 of the pendulum 28 has a distance 'a' relative to the fixed point of the electromagnet 33 at the cantilever 7. In this embodiment, the electromagnet 33 is fixed to the cantilever 7 by two fixed threads 76. Here, the distance 'a' is measured up to one of the fixed threads 76 closest to the swing axis 45, i.e., up to its central axis. The distance 'a' is advantageously greater than 5 cm, and particularly greater than 8 cm. Under certain operating conditions, lateral vibrations may occur at the cantilever 7, which, at a distance of at least 5 cm, cause relative motion of the electromagnet 33 relative to the free end of the pendulum 28, i.e., the armature 36 ( Figure 11 It may unintentionally become loose from the yoke 34 of the electromagnet 33. Figure 10 The shape of the elbow assembly 31 can also be seen. The rod 44 is arranged in the notch 75 of the lever 28, and the operating profile 65 is constructed on its peripheral wall. Figure 9 ).

[0061] Figure 11 The armature 36 is shown being secured at the lever 28. The armature 36 is secured to the fixed section 69 of the lever 28 via an armature bolt 55. In this embodiment, a pin 61 is also arranged at the fixed section 69. The pin 61 and the armature bolt 55 are arranged side-by-side in the same cross-section, i.e., about the transverse direction 38. The armature bolt 55 extends through the fixed section 69 of the lever 28 and the armature 36. A swing joint 50 is constructed on the side of the armature 36 facing away from the fixed section 69, via which the armature 36 is swingably supported relative to the armature bolt 55. In this embodiment, the swing joint 50 has a partially spherical section 56, which is secured to the armature bolt 55. In this embodiment, the armature bolt 55 extends through the partially spherical section 56. In this embodiment, the partially spherical section 56 is formed of a hemisphere and has a central opening for receiving the armature bolt 55. A portion of the spherical segment 56 abuts against the armature 36 on the side of the armature 36 opposite to the fixed segment 69. An armature bolt 55 extends through the opening 61 of the fixed segment 69 and the opening 72 of the armature 36. In this embodiment, a recess is constructed on the side of the armature 36 opposite to the fixed segment 69 in the area surrounding the opening 72, supporting the portion of the spherical segment 56 therein.

[0062] A damping element 70, such as a foam or rubber element, is arranged on the side of the fixed section 69 opposite to the armature 36, and the armature bolt 55 extends through this damping element. When the operator manipulates the operating lever 16 and then suddenly releases it, the damping element 70 suppresses the impact force. In this embodiment, the head of the armature bolt 55 rests against the damping element 70. Figure 11 The opening 62 of the guide portion 60 is also shown. (For example...) Figure 11 As also shown, electromagnet 33 has coil 35, which in Figure 11The diagram is schematically shown through the structural space occupied by coil 35.

[0063] like Figure 12 As shown, the armature 36 rests against the abutment surface 57 at the end face of the yoke 34. In this embodiment, the electromagnet 33 is constructed with a U-shaped yoke and a flat armature. However, it can also be configured such that the armature is an immersed armature and immersed in the yoke of the coil. The structural shape of the electromagnet 33 is independent of the present invention. The swing joint 50 allows the armature 36 to move relative to the armature bolt 55 about swing axes 51, 52, and 53. The swing axis 53 is the longitudinal central axis of the armature bolt 55. The swing axes 51 and 52 are oriented parallel to the abutment surface 57, while the swing axis 53 is perpendicular to the abutment surface 57. Here, the swing axis 52 is oriented parallel to the transverse 38 and in Figure 12 The axis 51 is perpendicular to the plane of the drawing. The oscillation axis 51 is perpendicular to the orientation of oscillation axes 52 and 53 and lies in the plane extended by the longitudinal axis 37 and the vertical axis 39 of the cantilever 7. (Example) Figure 11 As shown, the cantilever 7 has a plane 59 extending perpendicular to the lateral axis 38 and, consequently, perpendicular to the swing axis 45 of the lever 28. The swing axes 51 and 53 are located at... Figure 12 The corresponding plane 59 in the cross-section plane.

[0064] Sections of the armature bolt 55 and the pivot joint 50 extend via the abutment surface 57 to the side of the abutment surface 57, where the yoke 34 is also arranged. These sections are fully accommodated within the free space 80 of the yoke 34 for all provided tilt angles of the armature bolt 55. In this embodiment, the yoke 34 is U-shaped, and the free space 80 is formed between the two legs of the U. In this embodiment, the sections extending beyond the abutment surface 57 include the section of the armature bolt 55, the section of the partially spherical section 56, and the fastening element 81, by which the partially spherical section 56 is held on the armature bolt 55.

[0065] like Figure 13As shown, the opening 71 in the armature 36 has a diameter c, which is larger than the diameter b of the armature bolt 55. Here, the diameter b is measured in the area where the armature bolt 55 is arranged in the opening 71. The diameter c can be, for example, about 1 mm to 1.5 mm larger than the diameter b. The armature 36 has a thickness d measured perpendicular to the abutment surface 57. The partially spherical section 56 has a support surface 54, in which the partially spherical section 56 abuts against the armature 36 and forms a swing joint 50 with it. The support surface 54 has a radius r. The ratio of the radius r of the support surface 54 to the thickness d of the armature 36 is advantageously 0.3 to 2, particularly 0.4 to 1, preferably 0.4 to 0.8. The radius of the support surface 54 is correspondingly up to twice the thickness d of the armature 36. The radius r of the support surface 54 is advantageously smaller than the thickness d of the armature 36. Twice the radius r is advantageously significantly larger than the diameter c of the opening 71. By arranging the swing joint 50 on the side of the armature 36 facing the electromagnet 33 and having an extension larger than the opening 71, the armature 36 is fastened to the armature bolt 55 by a partially spherical section 56 fixed to the armature bolt 55. The armature 36 is arranged in the fixed section 69 of the swing arm 28. Figure 12 It is fixed between and to the swing joint 50 and thus in the longitudinal direction of the armature bolt 55.

[0066] In this embodiment, a portion of the spherical section 56 extends beyond the end face of the armature 36 facing the electromagnet 33 and into the free space formed between the legs of the yoke 34. This results in relatively less influence on the magnetic flux in the armature 36 and a smaller structural height. The armature 36 is fixed to the armature bolt 55 without additional fixing devices. However, it may also be suitable to arrange the swing axes 51, 52 of the armature 36 in the contact surface 57 or on the side of the contact surface 57 opposite to the yoke 34.

[0067] It may be advantageous to provide a ball, roller, or partial roller as an alternative to the partially spherical section 56. In the case of rollers and partial rollers, the armature 36 can only tilt about an axis parallel to the contact surface 57, while in the case of a ball and partial ball, tilting about all axes extending through the center point of the ball and parallel to the contact surface 57 can be achieved. The aforementioned features of the partially spherical section 56 and the arrangement of the swing axes 51 and 52 (in a matched form if necessary) are also advantageous for the ball, roller, or partial roller. Figure 14 An embodiment of the swing joint 50 is shown, wherein the swing joint is constituted by a partially spherical segment 56'. The partially spherical segment 56' is a sphere through which the armature bolt 55 extends. The center point of the partially spherical segment 56' is approximately located in the contact surface 57. According to... Figure 13In this embodiment, the center point of the partial spherical segment 56, i.e., the second swing axis 52, is located on the side of the contact surface 57 opposite to the armature 36. The distance between the swing axis 52 and the contact surface 57 is less than the radius r. Accordingly, the partial spherical segment 56 is at least partially immersed in the recess of the armature 36. Figure 14 The arrangement is shown after the yoke 34 moves relative to the rocker arm 28 in the transverse direction 38.

[0068] Due to this movement, the armature bolt 55 is positioned at an angle. The swing joint 50 causes the armature 36 to swing in the opposite direction relative to the armature bolt 55, thus preventing the armature 36 from being dislodged from the yoke 34 at the contact surface 57. This maintains the holding force and prevents it from being reduced. The side of the armature 6 facing the yoke 34 is located within the contact surface 57.

[0069] Figure 15 An arrangement according to the prior art is shown, wherein the same reference numerals are used for components corresponding to the present invention. In the prior art, the armature bolt 55 is pivotally supported relative to the rocker arm 28. However, the armature 36 is torsionally fixed to the armature bolt 55. If the armature bolt 55 tilts due to the relative movement of the armature 36 and the electromagnet 33 relative to the rocker arm 38, the armature 36 also tilts relative to the contact surface 57 and is thus disengaged from the yoke 34. Thus, the holding force of the electromagnet 33 can be overcome, and the rocker arm 38 is adjusted to its released state.

[0070] Figure 16 The arrangement according to the invention is shown. In order to follow the movement of the electromagnet 33 in the transverse direction 38, the armature bolt 55 is inclined relative to the fixed section 69 of the rocker arm 28 and the armature 36 can swing in the opposite direction relative to the armature bolt 55. Thus, the armature 36 is kept in contact with the yoke 34 at both longitudinal sides in the contact surface 57, and the armature 36 is not removed from the yoke 34. Figure 16 The diagram shows the arrangement after the electromagnet 33, together with the yoke 34, has moved laterally 38 to the maximum displacement e that occurs during operation. Due to this movement, the armature bolt 55 tilts relative to its neutral position at an angle α. This angle α can be, for example, 5º to 20º, particularly 8º to 15º. The armature 36 oscillates relative to the armature bolt 55 in the opposite direction at an angle β. The oscillation angle β of the armature 36 relative to the armature bolt 55, particularly about the oscillation axis 52, is coordinated with and at least as large as the tilt angle α. In this way, it is ensured that the tilt of the armature bolt 55 is always (i.e., until the maximum displacement e) fully compensated by the oscillation joint 50. Here, the oscillation angle β depends not only on the design of the oscillation joint 50, but also on the geometry of the openings 71 and 72, the diameter b of the armature bolt 55, and the thickness d of the armature 36.

[0071] The pivot joint 50 is advantageously made of a shape-stable material. The armature 36 is made of metal. Advantageously, the support surface 54 at the armature 36 is made of the metal of the armature 36. The partially spherical section 56 constituting the reaction support surface is advantageously made of metal or shape-stable plastic.

[0072] The design of the support connecting the armature and the armature bolt via the swing joint and the guide between the swing arm and the electromagnet are independent and advantageous designs. Combining the two inventions yields further advantages.

Claims

1. A hand-guided working instrument with a cutting tool and a braking mechanism (15) for said cutting tool, wherein, The braking mechanism (15) has an actuating element that acts on the braking element of the braking mechanism (15), wherein the actuating element is movable between a fixed state (41) and a released state (40), wherein in the fixed state the braking element does not brake the tool, and in the released state the braking element brakes the tool, wherein the braking mechanism (15) has an electromagnet (33) for fixing the actuating element in the fixed state (41), wherein the electromagnet (33) includes a yoke (34) and a coil (35), and wherein the electromagnet (33) works together with an armature (36), wherein the armature (36) is held at the actuating element by an armature bolt (55), characterized in that the armature (36) is via a swing joint. (50) The armature (36) is pivotally supported at the armature bolt (55) about at least one pivot axis (51, 52, 53), the armature (36) abutting against the abutment surface (57) of the yoke (34) in the fixed state (41) and at least one pivot axis (51, 52) is parallel to the abutment surface (57), and the yoke (34) is movable relative to the actuating element in a direction parallel to the abutment surface (57), and the pivot angle (β) is at least as large as the tilt angle (α), the armature (36) is tilted relative to the armature bolt (55) about the pivot axis (51, 52) at the pivot angle (β), and the armature bolt (55) is tilted relative to the actuating element at the tilt angle (α) in the case of the maximum displacement (e) of the yoke (34).

2. The working apparatus according to claim 1, characterized in that, The yoke (34) has a free space (80) in which the armature bolt (55) and the section of the swing joint (50) extending beyond the abutment surface (57) are accommodated.

3. The working apparatus according to claim 1, characterized in that, The control element is a lever (28), and at least one swing axis (51, 53) is located in a plane (59) arranged perpendicular to the swing axis (45) of the lever (28).

4. The working apparatus according to claim 1, characterized in that, The swing joint (50) has a curved support surface (54).

5. The working apparatus according to claim 4, characterized in that, The ratio of the radius (r) of the support surface (54) to the thickness (d) of the armature (36) is 0.3 to 2.

6. The working apparatus according to claim 1, characterized in that, The swing axis (51, 52) of the armature (36) is located on the side of the armature (36) facing the yoke (34).

7. The working apparatus according to claim 1, characterized in that, The armature bolt (55) extends through the fixed section (69) of the armature (36) and the operating element, and the armature bolt (55) is oscillating relative to the operating element.

8. A hand-guided working instrument with a cutting tool and a braking mechanism (15) for said cutting tool, wherein, The braking mechanism (15) has an actuating element that acts on the braking element of the braking mechanism (15), wherein the actuating element is movable between a fixed state (41) and a released state (40), wherein in the fixed state the braking element does not brake the tool, and in the released state the braking element brakes the tool, wherein the braking mechanism (15) has an electromagnet (33) for fixing the actuating element in the fixed state (41), wherein the electromagnet (33) includes a yoke (34) and a coil (35), and wherein the electromagnet (33) works together with an armature (36), wherein the armature (36) is held at the actuating element by an armature bolt (55), wherein the working instrument is a cutting machine (1) having a cantilever (7), wherein the cutting disc (8) constituting the tool is rotatably supported at the cantilever about a rotation axis (58), wherein the cantilever (7) has a longitudinal direction (37). The cantilever (7) has its maximum extension perpendicular to the rotation axis (58) in the longitudinal direction, and the cantilever (7) has a transverse (38) extending parallel to the rotation axis (58) and a vertical (39) extending perpendicular to the transverse (38) and perpendicular to the longitudinal direction (37), wherein the yoke (34) is fixed at the cantilever, wherein a guide (60) is provided, which includes a first guide connected to the armature (36) and a second guide connected to the yoke (34), wherein the first guide and the second guide work together in the fixed state (41) of the operating element and guide the armature (36) relative to the yoke (34) in the transverse (38) of the cantilever (7), and wherein the guides are arranged far apart from each other in the released state (40) of the operating element and only work together after at least half of the adjustment stroke (g) from the released state (40) to the fixed state (41).

9. The working apparatus according to claim 8, characterized in that, One of the guides is a pin (61) and the other guide has an opening (62), wherein the pin (61) extends into the opening (62) in the fixed state (41) of the actuating element.

10. The working apparatus according to claim 9, characterized in that, In the fixed state (41) of the operating element, a gap is formed on the transverse side (38) of the cantilever (7) between the edge of the pin (61) and the opening (62).

11. The working apparatus according to claim 8, characterized in that, At least one of the guide members has an inlet ramp (77).

12. The working apparatus according to claim 8, characterized in that, The control element is a swing arm (28), and the distance (a) between the swing axis (45) of the swing arm (28) and the fixed point (a) of the electromagnet (33) at the cantilever (7) is at least 5 cm.

13. The working apparatus according to claim 1, characterized in that, The braking mechanism (15) has an elbow assembly (31) comprising a first rod (42) and a second rod (43), wherein the first rod (42) is pivotally supported relative to the actuating element about a first swing axis (45), wherein the second rod (43) is pivotally supported at the first rod (42) about a second swing axis (46), wherein the second rod (43) is supported at a third swing axis (47) at a third rod (44), wherein the third rod (44) acts on the braking element, wherein the first swing axis (45) and the third swing axis (47) are located in a rocker arm plane (49), and wherein the second swing axis (46) is arranged on the same side of the rocker arm plane (49) in the released state (40) and the fixed state (41).

14. The working apparatus according to claim 1, characterized in that, The swing joint (50) is made of a shape-stable material.

Images