Governor Device

Abstract

To actualize a quick increase in the revolution of a stratified scavenging engine.SOLUTION: A governor device for adjusting the revolution of the stratified scavenging engine including a pilot air passage where pilot air is distributed for scavenging combustion gas from a combustion chamber and an air-fuel mixture passage where air-fuel mixture with fuel mixed is distributed, includes a fly weight connected to a crank shaft of the stratified scavenging engine for generating governor force according to the revolution of the stratified scavenging engine, a pilot air valve capable of adjusting the opening of the pilot air passage according to the governor force generated by the fly weight, and a throttle valve capable of adjusting the opening of the air-fuel mixture passage and the opening of the pilot air passage at the same time. The fly weight does not transmit the governor force to the throttle valve.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a governor device for adjusting the rotation speed of a stratified scavenging engine. [Background technology]

[0002] Conventionally, a governor device generates a force (governor force) corresponding to the rotation speed of a general-purpose engine and transmits this governor force to a throttle valve to adjust the rotation speed of the general-purpose engine (see Patent Document 1).If the general-purpose engine is a stratified scavenging engine, the throttle valve can simultaneously adjust the flow rate of lead air flowing through the lead air passage and the flow rate of the mixture flowing through the mixture passage (see Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-200471 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-111363 Summary of the Invention [Problem to be solved by the invention]

[0004] However, because the leading air has a lower density than the air-fuel mixture, it responds better to changes in the throttle valve opening than the air-fuel mixture and reaches the combustion chamber earlier than the air-fuel mixture. Therefore, when the rotation speed of the stratified scavenging engine is increased by the governor device, the air-fuel ratio temporarily becomes high (fuel becomes lean), and it may take a long time for the rotation speed of the stratified scavenging engine to increase.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a governor device that can accelerate the increase in rotation speed of a stratified scavenging engine. [Means for solving the problem]

[0006] In order to achieve the above object, a governor device according to the present disclosure is a governor device for adjusting the rotation speed of a stratified scavenging engine including a lead air passage through which lead air flows to scavenge combustion gas from a combustion chamber, and a mixture passage through which a mixture containing fuel flows, the governor device comprising: a flyweight connected to a crankshaft of the stratified scavenging engine and generating a governor force according to the rotation speed of the stratified scavenging engine; and a lead air valve capable of adjusting the opening of the lead air passage according to the governor force generated by the flyweight, wherein the governor force is not transmitted to the throttle valve. [Effects of the Invention]

[0007] According to the governor device of the present disclosure, the rotation speed of a stratified scavenging engine can be increased more quickly. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating a schematic configuration of a stratified scavenging engine equipped with a governor device according to an embodiment. [Figure 2] FIG. 1 is a diagram illustrating a configuration of a cylinder of a stratified scavenging engine according to an embodiment. [Figure 3] FIG. 1 is a diagram illustrating a schematic configuration of a governor device according to an embodiment. [Figure 4] FIG. 2 is a diagram illustrating a configuration of a leading air valve according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, a governor device according to an embodiment of the present disclosure will be described with reference to the drawings. The embodiment shows one aspect of the present disclosure, and is not intended to limit the present disclosure. Any modification can be made within the scope of the technical concept of the present disclosure.

[0010] A governor device 1 according to the present disclosure adjusts the rotation speed of a stratified scavenging engine 100. The stratified scavenging engine 100 includes a lead air passage 3 through which lead air A1 flows to scavenge combustion gas G generated by combustion of fuel F from a combustion chamber 103, as will be described later, and a mixture passage 5 through which a mixture A2 containing fuel F flows. When scavenging the combustion gas G from the combustion chamber 103, the lead air A1 forms a boundary layer between the mixture A2 and the combustion gas G, thereby preventing the mixture A2 from mixing with the combustion gas G and reducing the outflow of the mixture A2 from the combustion chamber 103. Such a stratified scavenging engine 100 is used, for example, as a power source for a work machine portable by a user, such as a lawnmower or a brush cutter.

[0011] Fig. 1 is a diagram schematically showing the configuration of a stratified scavenging engine 100 including a governor device 1 according to one embodiment. Fig. 2 is a diagram for explaining the configuration of a cylinder 102 of the stratified scavenging engine 100 according to one embodiment.

[0012] As illustrated in FIG. 1, the stratified scavenging engine 100 includes a cylinder 102, a crankcase 104, a fuel tank 106 in which fuel F is stored, an air cleaner 108, a carburetor 110, an insulator 112, a muffler 114, and a governor device 1 having a flyweight 2 and a lead air valve 4.

[0013] A combustion chamber 103 is formed inside the cylinder 102, and a piston 116 is disposed inside the combustion chamber 103. A crank chamber 105 is formed inside the crankcase 104, and a crankshaft 118 is disposed inside the crank chamber 105. The crankshaft 118 is connected to the piston 116 via a connecting rod 120. The cylinder 102 and the crankcase 104 are each made of a metal such as an aluminum alloy, and are formed using a molding die (cast mold). Hereinafter, the direction in which the piston 116 reciprocates within the cylinder 102, compressing the combustion chamber 103, is referred to as an upward direction in the vertical direction D1, and the direction opposite to this compression direction is referred to as a downward direction in the vertical direction D1. A more specific configuration of the cylinder 102 will be described later.

[0014] The air cleaner 108 removes foreign matter from air drawn in from outside the stratified scavenging engine 100. The carburetor 110 mixes fuel F with the air from which foreign matter has been removed by the air cleaner 108 (hereinafter referred to as clean air A) to generate an air-fuel mixture A2. An insulator 112 is disposed between the cylinder 102 and the carburetor 110 for thermal insulation.

[0015] 1 and 2, the stratified scavenging engine 100 includes a lead air passage 3 extending from an air cleaner 108 to a combustion chamber 103. The lead air passage 3 passes through a carburetor 110 and an insulator 112 in this order. Clean air A flows through the lead air passage 3 as lead air A1 toward the combustion chamber 103. In one embodiment, a lead air valve 4, which will be described later, is provided in the lead air passage 3.

[0016] In one embodiment, the stratified scavenging engine 100 includes a mixture passage 5 extending from the air cleaner 108 to the combustion chamber 103, separate from the lead air passage 3. The mixture passage 5 passes through a carburetor 110 and an insulator 112, in that order. The mixture passage 5 is located below the lead air passage 3. As shown in FIG. 2 , the mixture passage 5 includes a lead passage 7, which is located upstream of the mixture passage 5 and into which clean air A flows from the air cleaner 108. A fuel nozzle 131 is disposed in the lead passage 7 and injects fuel F supplied from the fuel tank 106. The clean air A flowing through the lead passage 7 is mixed with the fuel F to generate a mixture A2. Note that, in one embodiment, the mixture passage 5 extends from the air cleaner 108 to the combustion chamber 103, but the present disclosure is not limited to this configuration. In some embodiments, the mixture passage 5 branches off from the lead air passage 3. In this case, the upstream end (branch position) of the mixture passage may be inside the throttle valve 150, or may be located upstream of the throttle valve 150 (on the air cleaner 108 side).

[0017] The stratified scavenging engine 100 includes a throttle valve 150 capable of simultaneously adjusting the opening degree of the mixture passage 5 and the opening degree of the lead air passage 3. In one embodiment, the throttle valve 150 is a rotary valve and is provided in the carburetor 110. The throttle valve 150 has a cylindrical shape and penetrates the lead air passage 3 and the mixture passage 5 in the up-down direction D1. The throttle valve 150 has a first through-hole 152 that constitutes a part of the lead air passage 3 and a second through-hole 154 that constitutes a part of the mixture passage 5. The throttle valve 150 is connected to a throttle lever (not shown). When a user of the work machine operates the throttle lever, the opening degree of the mixture passage 5 and the opening degree of the lead air passage 3 are simultaneously adjusted via the throttle valve 150. In one embodiment, the throttle valve 150 is configured so as not to transmit a governor force GF generated by a flyweight 2 (described later). In other words, the governor device 1 is not designed to rotate the throttle valve 150.

[0018] 1 and 2, the stratified scavenging engine 100 includes an exhaust passage 11 extending from the combustion chamber 103 to a muffler 114. The exhaust passage 11 allows the combustion gas G discharged from the combustion chamber 103 to flow toward the muffler 114. The muffler 114 reduces the noise of the combustion gas G.

[0019] A specific configuration of the cylinder 102 will be described with reference to Fig. 2. In one embodiment, as illustrated in Fig. 2, the cylinder 102 is formed with an intake port 122 connected to the mixture passage 5 for introducing the mixture A2 into the combustion chamber 103, and an exhaust port 124 connected to the exhaust passage 11 for discharging the combustion gas G from the combustion chamber 103.

[0020] The cylinder 102 includes a scavenging passage 126 that connects the combustion chamber 103 and the crank chamber 105, and an air branch passage 128 that has one end connected to the scavenging passage 126 and the other end connected to the leading air passage 3. The scavenging passage 126 includes a scavenging port 130 that opens to the combustion chamber 103. The scavenging port 130 is located below the upper end of the exhaust port 124. The scavenging port 130 is located above the upper end of the intake port 122. The other end of the air branch passage 128 is formed with an inlet 128a that opens to the leading air passage 3.

[0021] In such a stratified scavenging engine 100, the crank chamber 105 is filled with the air-fuel mixture A2 during the intake stroke when the piston 116 moves toward the top dead center (upward), and at the same time, the lead air A1 is filled into the scavenging passage 126 (particularly the upper part of the scavenging passage 126). Then, during the combustion stroke when the piston 116 moves downward from the top dead center or the exhaust stroke, the scavenging ports 130 open, and the lead air A1 in the scavenging passage 126 is introduced into the combustion chamber 103 before the air-fuel mixture A2, scavenging the combustion gas G from the combustion chamber 103. Then, the air-fuel mixture A2 in the crank chamber 105 passes through the scavenging passage 126 and is introduced into the combustion chamber 103. Therefore, the stratified scavenging engine 100 is configured to reduce the outflow of the air-fuel mixture A2 from the combustion chamber 103.

[0022] (composition) The configuration of a governor 1 according to one embodiment will be described. Fig. 3 is a diagram schematically illustrating the configuration of the governor 1 according to one embodiment. As shown in Fig. 3, the governor 1 includes a flyweight 2 and a lead air valve 4. In one embodiment, the governor 1 includes a pair of flyweights 2, 2.

[0023] Hereinafter, the direction in which the axis O of the crankshaft 118 extends will be referred to as the axial direction D2. The tip side of the crankshaft 118 (the flyweight 2 side) of the axial direction D2 will be referred to as one side of the axial direction D2, and the side opposite the flyweight 2 side will be referred to as the other side of the axial direction D2.

[0024] In one embodiment, as illustrated in Fig. 3 , the governor device 1 includes a drive pulley 134 connected to a tip portion 132 including the tip of the crankshaft 118. The drive pulley 134 is also connected to a lever (not shown). A user of the work machine operates the lever to rotate the crankshaft 118 via the drive pulley 134, thereby starting the stratified scavenging engine 100.

[0025] The flyweight 2 is connected to the crankshaft 118 of the stratified scavenging engine 100. The flyweight 2 generates a governor force GF according to the rotation speed of the stratified scavenging engine 100. In the embodiment illustrated in FIG. 3 , the flyweight 2 generates the governor force GF by utilizing the centrifugal force generated when the crankshaft 118 rotates, and includes an arm portion 6, a protrusion 8, and a weight portion 10.

[0026] The arm 6 has a rod-like shape and is configured to be rotatable around a base end 12. Specifically, a hole 14 is formed in the base end 12, through which a pin 13 connected to a drive pulley 134 is inserted. The arm 6 is rotatably supported by the pin 13. The arm 6 extends from the base end 12 toward the crankshaft 118.

[0027] The protrusion 8 protrudes from the tip 16 of the arm 6 to the other side in the axial direction D2. The weight 10 is attached to the base end 12 of the arm 6. In the embodiment illustrated in Fig. 3, the base end 12 is bent, and the weight 10 is located on the other side of the base end 12 in the axial direction D2.

[0028] 3, the governor device 1 further includes a governor sleeve 136, a wire 138, and a spring 140. The governor sleeve 136 has a cylindrical shape and is disposed around the outer periphery of the crankshaft 118. The governor sleeve 136 is disposed on a path through which the protrusion 8 passes when the arm 6 rotates. Therefore, the governor sleeve 136 is pressed by the flyweight 2 with a governor force GF, and is configured to move to the other side in the axial direction D2.

[0029] A wire 138 connects the governor sleeve 136 and the lead air valve 4. The wire 138 rotates the lead air valve 4 by the tension force generated by the movement of the governor sleeve 136. One end of the spring 140 is fixed to a fixed wall 142, and the other end is connected to the end face of the governor sleeve 136 on the other side in the axial direction D2. The fixed wall 142 fixes the position of one end of the spring 140 in the axial direction D2. The fixed wall 142 is, for example, an inner wall within the crankcase 104 that is integrally connected to the crankcase 104.

[0030] The lead air valve 4 adjusts the opening of the lead air passage 3 in response to the governor force GF generated by the flyweight 2. In one embodiment, as shown in FIG. 3, the lead air valve 4 is located downstream of the throttle valve 150 in the lead air passage 3. As shown in FIG. 2, the lead air valve 4 is provided in the cylinder 102. In some embodiments, the lead air valve 4 is provided in the insulator 112. In another embodiment, the lead air valve 4 is located upstream of the throttle valve 150 in the lead air passage 3.

[0031] Next, an example of a specific configuration of the lead air valve 4 will be described. Fig. 4 is a diagram schematically showing the configuration of the lead air valve 4 according to one embodiment, in which the lead air passage 3 is viewed from the combustion chamber 103 side in the extension direction of the lead air passage 3.

[0032] As illustrated in FIG. 4, in one embodiment, the lead air valve 4 is a butterfly valve and includes a valve element 20 and a pivot shaft 22 that rotatably holds the valve element 20. In the embodiment illustrated in FIG. 4, the valve element 20 has a disk shape and is connected to the pivot shaft 22 by a fastener 24 such as a bolt. More specifically, the valve element 20 has an elliptical shape, eliminating the need for a stopper to prevent the valve element 20 from opening beyond the fully closed position when the valve is closed. In addition, the pulling stroke of the wire 138 required when closing the valve can be shortened, allowing the governor device 1 to be made more compact.

[0033] The rotating shaft 22 has a rod shape and extends along a transverse direction D3 that intersects with the extension direction of an imaginary straight line L that passes through the center C1 of the leading air passage 3 and the center C2 of the mixture passage 5. In one embodiment, this extension direction extends along the vertical direction D1, and the transverse direction D3 is a left-right direction that is perpendicular to the vertical direction D1. The rotating shaft 22 extends along the left-right direction so that the right end is located higher than the left end. In some embodiments, the rotating shaft 22 is D-cut so that the cross section of the assembly portion to which the valve body 20 is attached has a D-shape. This configuration makes it possible to reduce the opening area when the valve is closed and increase the opening area when the valve is open.

[0034] 4, the governor device 1 further includes a connecting member 26 that connects the rotating shaft 22 and a wire 138. The wire 138 extends in the vertical direction D1. The connecting member 26 is connected to the right side of the rotating shaft 22 in the intersecting direction D3, and the tensile force of the wire 138 rotates the rotating shaft 22. When the rotating shaft 22 rotates, the valve body 20 rotates, and the opening degree of the lead air passage 3 changes.

[0035] (Actions and Effects) The operation and effect of the governor device 1 according to one embodiment will be described. The lead air A1 has a lower density than the air-fuel mixture A2 and a higher flow velocity than the air-fuel mixture A2. Therefore, in a conventional governor device that adjusts the opening of the throttle valve 150, when the rotation speed of the stratified scavenging engine 100 is increased, both the opening of the lead air passage 3 and the opening of the mixture passage 5 increase, temporarily increasing the air-fuel ratio in the combustion chamber 103 (leaning the fuel F). Therefore, it may take a long time for the rotation speed of the stratified scavenging engine 100 to increase.

[0036] To address this concern, according to one embodiment, the governor device 1 rotates the lead air valve 4 with a governor force GF generated in accordance with the rotational speed of the stratified scavenging engine 100, thereby adjusting the opening of the lead air passage 3. Therefore, when the governor device 1 operates to increase the rotational speed of the stratified scavenging engine 100, the governor device 1 does not adjust the opening of the throttle valve 150, and therefore, an amount of fuel required for increasing the rotational speed flows through the mixture passage 5 regardless of the governor device 1. This makes it possible to suppress a temporary increase in the air-fuel ratio in the combustion chamber 103. This makes it possible to accelerate the increase in the rotational speed of the stratified scavenging engine 100. For example, if the stratified scavenging engine 100 is mounted on a grass cutter or brush cutter, the rotational speed of the stratified scavenging engine 100 can be restored more quickly when the driver goes to cut grass (after the rotational speed of the stratified scavenging engine 100 has been temporarily reduced).

[0037] According to one embodiment, the lead air valve 4 is provided independently of the throttle valve 150. This eliminates the need for a mechanism for transmitting the governor force GF to the throttle valve 150, and the governor device 1 can be attached to the stratified scavenging engine 100 without modifying the structure of an existing carburetor.

[0038] Usually, in the stratified scavenging engine 100, a heat insulating member is provided between the cylinder 102 and the carburetor 110 to prevent heat from being transferred from the cylinder 102 to the carburetor 110. For this reason, the lead air passage 3 is longer on the downstream side of the throttle valve 150 than on the upstream side of the throttle valve 150. Therefore, by positioning the lead air valve 4 downstream of the throttle valve 150 in the lead air passage 3, it is possible to prevent the size of the stratified scavenging engine 100 from increasing. Furthermore, by shortening the distance from the lead air valve 4 to the combustion chamber 103, it is possible to improve the sensitivity of the responsiveness of the lead air A1.

[0039] According to one embodiment, a butterfly valve is used as the lead air valve 4, thereby suppressing an increase in costs due to the installation of the lead air valve 4. According to one embodiment, by extending the rotating shaft 22 along the intersecting direction D3, the axial direction of the rotating shaft 22 is set at an angle nearly perpendicular to the pulling direction of the wire 138 (the up-down direction D1), thereby suppressing loss of the governor force GF transmitted from the flyweight 2 to the rotating shaft 22. In addition, interference of the rotating shaft 22 with the mixture passage 5 can be suppressed.

[0040] The contents described in each of the above embodiments can be understood, for example, as follows.

[0041] [1] The governor device (1) according to the present disclosure includes: A governor device for adjusting the rotation speed of a stratified scavenging engine (100) including a lead air passage (3) through which lead air (A1) flows for scavenging combustion gas (G) from a combustion chamber (103), and a mixture passage (5) through which a mixture (A2) containing fuel (F) flows, a flyweight (2) connected to a crankshaft (118) of the stratified scavenging engine and generating a governor force (GF) corresponding to the rotation speed of the stratified scavenging engine; a lead air valve (4) capable of adjusting the opening degree of the lead air passage in accordance with the governor force generated by the flyweight; a throttle valve (150) capable of simultaneously adjusting the opening degree of the mixture passage and the opening degree of the lead air passage; The flyweight does not transmit the governor force to the throttle valve.

[0042] Because the lead air has a lower density than the air-fuel mixture, it reaches the combustion chamber earlier than the air-fuel mixture when the rotation speed of the stratified scavenging engine is increased. This temporarily increases the air-fuel ratio (leaning the fuel), which may cause the stratified scavenging engine to take a long time to increase its rotation speed. To address this issue, the configuration described in [1] above allows the lead air valve to adjust the opening of the lead air passage in accordance with the governor force generated by the flyweight. This prevents the air-fuel ratio from temporarily increasing when the rotation speed of the stratified scavenging engine is increased, thereby enabling the rotation speed of the stratified scavenging engine to increase more quickly.

[0043] Furthermore, according to the configuration described in [1] above, the lead air valve is provided independently of the throttle valve, which eliminates the need for a mechanism to transmit the governor force to the throttle valve, simplifying the governor device design.

[0044] [2] In some embodiments, in the configuration described in [1] above, The lead air valve is located downstream of the throttle valve in the lead air passage.

[0045] Typically, in a stratified scavenging engine, a heat insulating member is provided between the cylinder (inside which a combustion chamber is formed) and the carburetor (where a throttle valve is provided) to prevent heat from being transmitted. Therefore, the lead air passage downstream of the throttle valve is longer than the lead air passage upstream of the throttle valve. Therefore, according to the configuration described in [2] above, the lead air valve can be provided without increasing the dimensions of the stratified scavenging engine. In addition, by shortening the distance from the lead air valve to the combustion chamber, the sensitivity of the lead air response can be improved.

[0046] [3] In some embodiments, in the configuration described in [1] or [2] above, The leading air valve is a butterfly valve.

[0047] According to the configuration described in [3] above, it is possible to suppress the increase in costs due to the installation of a lead air valve.

[0048] [4] In some embodiments, in the configuration described in [3] above, The butterfly valve includes a valve body (20) and a rotary shaft (22) that rotatably holds the valve body, When the leading air passage is viewed from the extension direction of the leading air passage, the rotation axis extends along an intersecting direction that intersects with the extension direction (D1) of an imaginary straight line (L) that passes through the center (C1) of the leading air passage and the center (C2) of the mixture passage.

[0049] According to the configuration described in [4] above, it is possible to suppress loss of the governor force transmitted from the flyweight to the rotating shaft, and also to suppress interference of the rotating shaft with the mixture passage. [Explanation of symbols]

[0050] 1 Governor device 2 Flyweight 3 Leading air passage 4 Leading Air Valve 5 mixture passage 20 Valve body 22 Rotating shaft 24 Fasteners 26 Connecting member 100 Stratified Scavenging Engine 102 cylinders 103 Combustion chamber 104 Crankcase 105 Crankcase 106 Fuel Tank 108 Air cleaner 110 Carburetor 112 Insulator 114 Muffler 116 Piston 118 Crankshaft 120 connecting rod 122 Intake port 124 Exhaust port 126 Scavenging passage 128 Air branch passage 130 Scavenging port 131 Fuel nozzle 134 Drive pulley 136 Governor Sleeve 138 Wire 140 Spring 142 Fixed wall 150 throttle valve 152 First through hole 154 Second Through Hole A. Clean air A1 Leading Air A2 mixture C1 Center of leading air passage C2 Center of mixture passage D1 Vertical direction D2 Axial direction D3 Crossing direction F fuel G Combustion gas GF Governor Force L straight line O axis

Claims

1. A governor device for adjusting the rotation speed of a stratified scavenging engine including a lead air passage through which lead air flows for scavenging combustion gas from a combustion chamber, and a mixture passage through which a mixture containing fuel flows, a flyweight connected to a crankshaft of the stratified scavenging engine and configured to generate a governor force according to the rotation speed of the stratified scavenging engine; a lead air valve capable of adjusting the opening degree of the lead air passage in accordance with the governor force generated by the flyweight; a throttle valve capable of simultaneously adjusting the opening degree of the mixture passage and the opening degree of the lead air passage, the flyweight does not transmit the governor force to the throttle valve; Governor device.

2. The lead air valve is located downstream of the throttle valve in the lead air passage. The governor device according to claim 1 .

3. The leading air valve is a butterfly valve. The governor device according to claim 1 or 2.

4. The butterfly valve includes a valve body and a rotary shaft that rotatably holds the valve body, when the leading air passage is viewed from an extension direction of the leading air passage, the rotation axis extends along an intersecting direction that intersects with a direction in which an imaginary straight line that passes through a center of the leading air passage and a center of the mixture passage extends. The governor device according to claim 3 .

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