Vehicle power transmission structure

Abstract

To provide a vehicle power transmission structure which can surely prevent switching from a clutch connection state to a clutch cutoff state.SOLUTION: A power transmission structure includes: a gear that engages with an axle in a relatively rotational manner; a clutch sleeve that engages with the axle in a relatively non-rotational manner and in an axially slidable manner; and a lever member that moves the clutch sleeve. The movement of the clutch sleeve switches connection and disconnection of the power transmission between the gear and the axle. The lever member is rotatable about a first rotational axis, and has a locking lever and a locking part that is provided to the locking lever and engages with a locking groove of the clutch sleeve. A reference virtual face including an axle parallel line starting from the first rotational axis is defined. When swinging the lever member in a first direction about the first rotational axis, a locking part at a position closest to a wall face on the gear side of the locking groove among the locking parts is positioned away from the reference virtual face in the first direction to be in a clutch connection state.SELECTED DRAWING: Figure 7B

Description

Technical Field

[0001] The present invention relates to a power transmission structure for a vehicle.

Background Art

[0002] Conventionally, in a vehicle such as a lawn mowing vehicle equipped with a working unit such as a lawn mowing device, it has been known that the wheels can be driven by an electric motor to enable running. Patent Document 1 describes a lawn mowing vehicle in which the left and right wheels are commonly driven by an electric motor. Patent Document 2 describes a lawn mowing vehicle in which the left and right wheels can be driven independently of each other, the left wheel is driven by a left electric motor, and the right wheel is driven by a right electric motor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a vehicle that drives the left and right wheels with one or two motors as described above, a power transmission structure that transmits the power of the electric motor to the wheels is used. At this time, it is also conceivable to use another power source such as an engine or a hydraulic motor instead of the electric motor.

[0005] On the other hand, there is a market demand to move the vehicle with a small force by traction or the like even when the static torque of the power source is large when the system power supply of the vehicle is turned off, such as when the cogging torque of the electric motor is large. For this purpose, it is conceivable to provide a clutch called a traction clutch that can disconnect and connect power in the power transmission path connecting the axle and the gear mechanism.

[0006] In such a power transmission structure with a clutch, when the user does not perform a clutch operation, it is required that the clutch does not surely switch to the disengaged state from the engaged state. For example, when the vehicle stops on an inclined surface with the clutch engaged, if the clutch switches to the disengaged state for some reason without the user performing a clutch operation, the vehicle may move along the inclined surface without being subjected to the resistance of the power source or the like. In particular, when the weight of the vehicle increases, the possibility of such inconvenience occurring increases.

[0007] The present invention provides a power transmission structure for a vehicle that can more surely prevent a switch from a clutch-engaged state, in which power transmission is possible between a gear and an axle, to a clutch-disengaged state in which power transmission is cut off when the user does not perform a clutch operation.

Means for Solving the Problem

[0008] The vehicle power transmission structure according to the present invention includes an axle that directly or indirectly drives a ground wheel, a gear that is rotatably fitted to the outside in the radial direction of the axle and to which power for driving the ground wheel is input, a clutch sleeve that is non-rotatable relative to the axle and slidable in the axial direction and is fitted adjacent to the gear, and a lever member that reciprocates the clutch sleeve in the axial direction. Engaging elements of a hole and a protrusion that can mesh with each other are provided between the opposing surfaces of the gear and the clutch sleeve to switch the connection and disconnection of power transmission between the gear and the axle by the movement of the clutch sleeve. The vehicle power transmission structure is such that a locking groove is formed over the entire outer peripheral surface of the clutch sleeve. The lever member is rotatable about a first rotation axis that is orthogonal to an axle parallel line parallel to the central axis of the axle. The lever member includes a lever shaft to which an operating tool is fixed, a locking lever provided at one end of the lever shaft and extending in a direction orthogonal to the first rotation axis, and a locking portion provided at a position of the locking lever away from the first rotation axis and locked to the locking groove. A reference virtual plane including the axle parallel line starting from the first rotation axis is defined. When the lever member swings in a first direction about the first rotation axis, the position of the locking portion closest to the wall surface on the gear side of the locking groove is positioned away from the reference virtual plane on the first direction side. Thereby, the clutch sleeve is configured to be in a clutch connection state in which it can mesh with the gear and the engaging elements. When the lever member swings in a second direction about the first rotation axis, the position of the locking portion closest to the wall surface is positioned away from the reference virtual plane on the second direction side. Thereby, the clutch sleeve is configured to be in a clutch disconnection state in which it is axially separated from the gear.

Effects of the Invention

[0009] According to the vehicle power transmission structure of the present invention, when the user does not perform a clutch operation, it is possible to more reliably prevent switching from the clutch connection state to the clutch disconnection state.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

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Figure 7A

Figure 7B

Figure 7C

Figure 8A

Figure 8B

Figure 8C

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Figure 10

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Figure 12

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Figure 16A

Figure 16B

Figure 17A

Figure 17B

Figure 18A

Figure 18B

Figure 19

Figure 20

Mode for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following, the case where the vehicle power transmission structure is mounted on a lawn mowing vehicle which is a work vehicle will be described. However, the vehicle on which the vehicle power transmission structure is mounted is not limited to this, and other work vehicles having a working part that performs any one or more of snow removal work, excavation work, civil engineering work, and agricultural work, or an off-road type multi-purpose vehicle (Utility Vehicle) having a loading platform and traveling on rough ground, or an All Terrain Vehicle (ATV) called a buggy, a Recreational Vehicle (RV), or a Recreational Off-highway Vehicle (ROV) may also be used. Further, in the following, the case where the vehicle drives two rear wheels with two motors will be described. However, the vehicle may be configured to drive two front wheels with two motors. Further, in the following, the case where a left and right lever type operator having two left and right operation levers is used will be described. However, this is an example, and a steering wheel may be used as a turning indicator, and an accelerator pedal provided in front of the seat may be used as a traveling indicator. In all the drawings below, the same elements are denoted by the same reference numerals, and duplicate explanations are omitted or simplified.

[0012] (First Embodiment) FIGS. 1 to 16B show the first embodiment. In the drawings described below, the front-rear direction is indicated by X, the left-right direction is indicated by Y, and the up-down direction is indicated by Z. Further, the front side is indicated by Fr, the left side is indicated by Lh, and the upper side is indicated by Up. X, Y, and Z are orthogonal to each other.

[0013] FIG. 1 is a perspective view of a vehicle 10 incorporating a vehicle power transmission structure according to an embodiment. FIG. 2 is a schematic configuration diagram of the vehicle 10. In the following description, the vehicle power transmission structure is referred to as the power transmission structure. The vehicle 10 is a riding self-propelled lawn mower vehicle suitable for lawn mowing. The vehicle 10 includes two left and right left wheels 12 and right wheels 13 (FIG. 2), two left and right front wheels which are caster wheels 15 and 16, a lawn mowing device 18 which is a working unit, and a left traveling motor 30 and a right traveling motor 31 (FIG. 2). The left wheel 12 and the right wheel 13 correspond to ground wheels. Further, the vehicle 10 includes three deck motors 63 (FIG. 2) which are working motors, two left and right operation levers 22 and 23, a battery 34 (FIG. 2), and a control device (not shown). The left traveling motor 30, the right traveling motor 31, and the deck motor 63 are each an electric motor. The left traveling motor 30 and the right traveling motor 31 correspond to power sources.

[0014] The left wheel 12 and the right wheel 13 are rear wheels supported on both left and right sides of the rear side of a main frame 20 which is a vehicle body, and are also main drive wheels. The main frame 20 is formed of a metal such as steel material into a beam structure or the like. The main frame 20 includes side plate portions 20a and 20b extending substantially in the front-rear direction at both left and right ends, and a connecting portion 20c connecting the side plate portions 20a and 20b on both left and right sides. Between the rear end portions of the left and right side plate portions 20a and 20b, a driver's seat 21 for a driver as a user is fixed on the upper side.

[0015] On the left and right sides of the driver's seat 21, the left and right operation levers 22, 23 are separately arranged, and the rotational direction and rotational speed of the left wheel 12 or the right wheel 13 on the corresponding side are indicated by moving back and forth. Specifically, in the main frame 20, two guide panels 26, 27 are fixed on both the left and right sides of the driver's seat 21, and the left and right two operation levers 22, 23 protrude upward from each of the two guide panels 26, 27 and are supported by the main frame 20. The left operation lever 22 corresponds to a travel indicator for instructing acceleration, deceleration, stop, and forward and reverse rotation of the left travel motor 30, and the right operation lever 23 corresponds to a travel indicator for instructing acceleration, deceleration, stop, and forward and reverse rotation of the right travel motor 31. The tip of each operation lever 22, 23 is used for the driver to grasp and indicate the rotational direction and rotational speed of the left wheel 12 and the right wheel 13. The left operation lever 22 is operated to instruct the drive and stop of the left wheel 12. The right operation lever 23 is operated to instruct the drive and stop of the right wheel 13. Each operation lever 22, 23 is substantially L-shaped, and a gripping portion 24 extending in the left-right direction is formed at the upper end. The gripping portion 24 is grasped and operated by the driver. Each operation lever 22, 23 is swingable about an axis along the left-right direction at the lower end. Each operation lever 22, 23, based on the N position which is a neutral position close to the upright position, when tilted forward, the travel motor 30 (or 31) on the same side as the operation lever 22 (or 23) is instructed to be driven at the target rotational speed per unit time (sec -1 ) corresponding to forward movement. As the target rotational speed, it may be set at the target rotational speed per minute (min -1 ).

[0016] The operation levers 22, 23 indicate that the target rotation speed increases as the tilting amount increases. When the operation levers 22, 23 are tilted backward with respect to the N position, they indicate driving the traveling motor 30 (or 31) on the same side as the operation lever 22 (or 23) at a target rotation speed corresponding to reverse travel, and that the target rotation speed increases as the tilting amount increases. When the operation levers 22, 23 are moved to the N position, they indicate stopping the driving of the traveling motor 30 (or 31) on the same side as the operation lever 22 (or 23). Thus, each of the operation levers 22, 23 indicates forward travel, reverse travel, and stop of the vehicle by instructing the target rotation speed of the corresponding traveling motors 30, 31 according to the user's operation.

[0017] The tilting positions of the two left and right operation levers 22, 23 in the front-rear direction are detected by left and right lever position sensors (not shown), respectively. Each lever sensor includes, for example, a potentiometer. The detection signals of each lever sensor are transmitted to the control device.

[0018] The two left and right caster wheels 15, 16 are steering wheels supported at the front end of the main frame 20 and are also front wheels. Each caster wheel 15, 16 is provided at a distance in the front-rear direction from the left wheel 12 and the right wheel 13 in the front-rear direction of the vehicle 10. Each caster wheel 15, 16 can freely rotate by 360 degrees or more about an axis in the vertical direction (the up-down direction in FIG. 1). Note that the configuration in which two caster wheels are arranged on the vehicle is not limiting, and only one or three or more caster wheels may be arranged on the vehicle.

[0019] As shown in FIG. 2, the left traveling motor 30 is connected to the left wheel 12 via the left power transmission structure 41 supported on the rear side of the main frame 20. The right traveling motor 31 is connected to the right wheel 13 via the right power transmission structure 42 supported on the rear side of the main frame 20. As will be described later, each of the power transmission structures 41 and 42 has a gear mechanism and axles 120 and 121 connected to the gear mechanism, and is configured to enable power transmission. The left traveling motor 30 and the right traveling motor 31 are respectively supported on the left and right sides at the rear side of the main frame 20. Each traveling motor 30 and 31 is driven by a corresponding traveling inverter (not shown). The driving of each traveling inverter is controlled by the control device according to the operations of the corresponding operation levers 22 and 23. Thus, the two left and right traveling motors 30 and 31 are respectively connected to the two left and right wheels 12 and 13 and are driven independently of each other.

[0020] A battery 34 is connected to each of the traveling inverter (not shown) that drives the left traveling motor 30 and the right traveling inverter (not shown) that drives the right traveling motor 31, and power is supplied from the battery 34. The left traveling motor 30 and the right traveling motor 31 are, for example, three-phase motors. As shown in FIG. 2, the battery 34 is fixed to the upper surface side or the lower surface side of the main frame 20 behind the driver's seat 21.

[0021] As shown in FIGS. 1 and 2, the lawn mowing device 18 is supported below the middle part in the front-rear direction of the main frame 20. Thereby, the lawn mowing device 18 is arranged between the caster wheels 15, 16 and the left and right wheels 12, 13 in the front-rear direction. The lawn mowing device 18 includes three lawn mowing blades 18a, 18b, 18c (FIG. 2) which are lawn mowing rotary tools arranged inside a mower deck 19 which is a cover. The lawn mowing blades 18a, 18b, 18c are covered on the upper side by the mower deck 19. Each of the lawn mowing blades 18a, 18b, 18c has a plurality of blade elements that rotate around an axis facing in the vertical direction (the front-back direction of the paper surface of FIG. 2). Thereby, the blade elements can rotate to break and cut the grass. To each of the three lawn mowing blades 18a, 18b, 18c, a corresponding deck motor 63 out of the three deck motors 63 which are working motors is connected. To each deck motor 63, a battery 34 is connected via a deck inverter (not shown) which is an inverter for the corresponding deck motor 63, and power is supplied from the battery 34. The drive of each deck inverter is controlled by a control device according to the operation of a deck switch (not shown). Thereby, each deck motor 63 is driven. Each deck motor 63 is, for example, a three-phase motor.

[0022] As a rotary tool for mowing grass, the mowing device may be configured to have a function of mowing grass and the like by arranging, for example, a spiral blade on a rotation axis parallel to the ground surface, and include a mowing reel driven by a deck motor.

[0023] Furthermore, the two operation levers 22, 23 are configured to be tiltable so as to open outward in the vehicle width direction from the upright neutral state, and the tilted position is set as the parking brake position. The two operation levers 22, 23 have a function of instructing the operation of the parking brake by moving to the parking brake position. By forming T-shaped guide holes in the guide panels 26, 27 provided at the upper part of the vehicle, the opening of the two operation levers 22, 23 outward in the vehicle width direction may be configured to be possible only from the state where the operation levers 22, 23 are upright. The lower ends of the left and right operation levers 22, 23 are connected to the brake mechanisms 90 of the left and right power transmission structures 41, 42 described later by link mechanisms, and the brake mechanisms 90 are actuated by the outward opening of the operation levers 22, 23 to brake the left wheel 12 and the right wheel 13.

[0024] The above is the overall configuration of the vehicle 10. Next, the power transmission structures 41, 42 (FIG. 2) mounted on this vehicle 10 will be described. An axle 120 of the left power transmission structure 41 is directly or indirectly connected to the left wheel 12. An axle 121 of the right power transmission structure 42 is directly or indirectly connected to the right wheel 13. Thereby, the left and right wheels 12, 13 are directly or indirectly driven by the left and right axles. The structure of the right power transmission structure 42 is the same as that of the left power transmission structure 41 except that it is symmetric with respect to the center in the vehicle width direction. For this reason, hereinafter, the left power transmission structure 41 will be described in detail. Hereinafter, the left traveling motor 30 will be referred to as the traveling motor 30.

[0025] FIG. 3 is an enlarged view of the two left and right power transmission structures 41, 42 at the rear side shown in FIG. 2 as viewed from above. FIG. 4 is a perspective view of the left power transmission structure 41 for the left wheel 12 taken out from FIG. 3 and viewed from above. FIG. 5 is a cross-sectional view of the power transmission structure 41. The power transmission structure 41 is integrally formed by combining a case 43, a traveling motor 30, a gear mechanism 80 (FIG. 5), an axle 120, and a brake mechanism 90. The case 43 is formed by combining a transmission case 44 and a brake case 45.

[0026] As shown in FIG. 5, the transmission case 44 houses an input shaft 60, an axle 120, and a gear mechanism 80 inside. The gear mechanism 80 is a mechanism that transmits power between the input shaft 60 and the axle 120, and decelerates and transmits the power from the input shaft 60 to the axle 120. The input shaft 60 and the axle 120 are arranged in parallel. The input shaft 60 is connected to the motor shaft 32 of the traveling motor 30 as will be described later, and the input shaft 60 rotates synchronously with the motor shaft 32.

[0027] The transmission case 44 is integrated by coupling an inner case 46 that forms the inner side in the vehicle width direction (the right side of the paper in FIG. 5), which is one side in the axial direction, and an outer case 47 that forms the outer side in the vehicle width direction (the left side of the paper in FIG. 5), which is the other side in the axial direction, with a plurality of bolts. Here, the axial direction of the power transmission structure 41 is a direction parallel to the input shaft 60 and the axle 120, and coincides with the vehicle width direction.

[0028] The inner case 46 is a gear case that has a recess 46a on the front side on the inner side in the vehicle width direction and a recess 46b from the front side to the rear side on the outer side in the vehicle width direction. The outer case 47 has an opening on the inner side in the vehicle width direction, and a cylindrical portion 49 extends axially from a rear portion of the outer surface in the vehicle width direction. The axle 120 passes through this cylindrical portion 49. The inner case 46 and the outer case 47 are coupled so that the outer peripheral edge portions at the ends in the vehicle width direction abut against each other, and the recess 46b on the outer side in the vehicle width direction of the inner case 46 is blocked by the outer case 47. Thereby, a gear chamber S1 in which each gear of the gear mechanism 80a is arranged is formed inside the transmission case 44. On the other hand, the recess 46a on the inner side in the vehicle width direction of the transmission case 44 is blocked by the motor case 30a of the traveling motor 30. The motor shaft 32 of the traveling motor 30 and the input shaft 60 are arranged so that their respective shaft centers coincide. The motor shaft 32 corresponds to a rotating shaft.

[0029] As shown in FIG. 5, on the input shaft 60, a cylindrical portion 61 is formed at the first end on the traveling motor 30 side. An internal spline portion formed on the inner peripheral surface of the cylindrical portion 61 engages with an external spline portion formed on the outer peripheral surface of the tip end portion of the motor shaft 32. Thereby, the input shaft 60 rotates in synchronization with the motor shaft 32.

[0030] A brake rotor 91 that constitutes a brake mechanism 90 described later is fitted to the second end of the input shaft 60 on the side opposite to the traveling motor 30, and is provided so as not to be relatively rotatable with respect to the input shaft 60. The brake case 45 is coupled to the outside in the vehicle width direction of the outer case 47 with a plurality of bolts so as to cover the second end of the input shaft 60 and the brake rotor 91. Thereby, a brake chamber S2 is formed inside the brake case 45. A plurality of positions in the axial intermediate portion of the input shaft 60 are rotatably supported by the transmission case 43 via bearings 50 and 51, respectively.

[0031] On the other hand, the gear mechanism 80 includes a first spur gear 81 provided on the input shaft 60 by being directly formed on the input shaft 60, an intermediate gear shaft 82 disposed between the input shaft 60 and the axle 120 and having a second spur gear 83 locked to the outer peripheral surface thereof, and an output gear 84 externally fitted to the axle 120. The second spur gear 83 meshes with the first spur gear 81, and the output gear 84 meshes with a tooth portion on one side of an intermediate gear portion 82a directly formed on the intermediate gear shaft 82. The internal teeth of the second spur gear 83 mesh with the tooth portion on the other side of the intermediate gear portion 82a. The intermediate gear shaft 82 and the axle 120 are rotatably supported inside the transmission case 44 via bearings.

[0032] FIG. 6 is an enlarged cross-sectional view taken along line A-A of FIG. 5. As shown in FIGS. 5 and 6, the output gear 84 is relatively rotatably fitted to the outside in the radial direction of the intermediate portion of the axle 120. Power for driving the wheel 12 is input to the output gear 84 from the traveling motor 30 via the gear mechanism 80.

[0033] As shown in FIG. 6, the stepped surface 129 formed in the middle portion of the axle 120 abuts against the outer end surface in the vehicle width direction near the inner circumference of the output gear 84. On the outer peripheral surface of the middle portion of the axle 120, at a position adjacent to the inner end in the vehicle width direction of the output gear 84, a clutch sleeve 71 constituting the clutch mechanism 70 is externally fitted.

[0034] The clutch mechanism 70 includes a clutch sleeve 71, an output gear 84, an axle 120, and a lever member 74. The clutch sleeve 71 and the lever member 74 are housed in the case 43, similar to the output gear 84 and the axle 120.

[0035] On the outer peripheral surface of the portion of the inner side in the vehicle width direction of the axle 120, excluding the small-diameter end portion 120b where the diameter of the inner end in the vehicle width direction of the axle 120 is reduced, a shaft spline groove 122, which is a male spline portion, is formed. A bearing 101 for rotatably supporting the axle 120 on the inner case 46 is fitted to the small-diameter end portion 120b.

[0036] The clutch sleeve 71 has a clutch spline groove 72, which is a female spline portion, formed on its inner peripheral surface. The clutch sleeve 71 is externally fitted to the axle 120, and the clutch spline groove 72 and the shaft spline groove 122 of the axle 120 are in spline engagement. As a result, the clutch sleeve 71 is non-rotatable relative to the axle 120 and is fitted in a slidable manner in the axial direction.

[0037] The lever member 74 reciprocates the clutch sleeve 71 in the axial direction of the clutch sleeve 71. Between the opposing surfaces of the output gear 84 and the clutch sleeve 71, engaging elements of a hole and a protrusion that can mesh with each other are provided. The clutch mechanism 70 switches the connection and disconnection of power transmission between the output gear 84 and the axle 120 by the movement of the clutch sleeve 71.

[0038] For example, when the clutch sleeve 71 moves outward in the vehicle width direction, the clutch sleeve 71 is engaged with the output gear 84 so as to prevent relative rotation with respect to the output gear 84, and the clutch mechanism 70 enters a connected state where power transmission between the output gear 84 and the axle 120 is connected. In this state, the output gear 84 and the axle 120 rotate synchronously.

[0039] On the other hand, when the clutch sleeve 71 moves inward in the vehicle width direction and the engagement between the clutch sleeve 71 and the output gear 84 is released, the clutch mechanism 70 enters a disconnected state where power transmission between the output gear 84 and the axle 120 is disconnected. In this state, the output gear 84 and the axle 120 rotate relative to each other.

[0040] In the connected state of the clutch mechanism 70, the power of the traveling motor 30 is transmitted from the motor shaft 32 to the input shaft 60. The power of the input shaft 60 is decelerated by the gear mechanism 80 and then transmitted to the axle 120 via the clutch sleeve 71.

[0041] The outer end portion of the axle 120 in the vehicle width direction protrudes from the tip of the cylindrical portion 49, and a hub 52 is fixed to the protruding portion. The left wheel 12 is fixed to the hub 52. Thus, in the connected state of the clutch mechanism 70, the power of the traveling motor 30 is sequentially transmitted from the motor shaft 32 to the input shaft 60, the gear mechanism 80, and the axle 120, and the left wheel 12 rotates.

[0042] The traveling motor 30 includes a motor rotor fixed to the outer peripheral surface of the motor shaft 32, a stator core facing the outer peripheral surface of the motor rotor, and three-phase stator coils wound around the stator core. The motor rotor has permanent magnets arranged at a plurality of positions in the circumferential direction of the rotor core, for example. The stator core is fixed inside the motor case 30a. The motor shaft 32 is rotatably supported by the motor case 30a by a bearing (not shown). When three-phase AC power is supplied from a battery to the stator coils, the motor shaft 32 rotates due to the interaction between the rotating magnetic field generated in the stator core and the magnetic field generated by the motor rotor.

[0043] Next, the clutch mechanism 70 will be described in detail with reference to FIGS. 5, 6, and FIGS. 7A to 10. FIG. 7A is a view showing an upper portion of FIG. 6 and indicating a clutch connected state. FIG. 7B is a cross-sectional view taken along line B-B of FIG. 7A. FIG. 7C is an enlarged view showing a part of FIG. 7B.

[0044] The clutch sleeve 71 includes a cylindrical portion 75, a first flange 76, and a second flange 77 formed on outer peripheral surfaces of both axial ends of the cylindrical portion 75. The first flange 76 is connected to an outer end portion of the cylindrical portion 75 in the vehicle width direction. The second flange 77 is connected to an inner end portion of the cylindrical portion 75 in the vehicle width direction. On the outer peripheral surface of the cylindrical portion 75, a locking groove 78 is formed over the entire circumference between the first flange 76 and the second flange 77. A roller 130, which is a locking portion provided on a lever member 74 described later, is locked in the locking groove 78, and the clutch sleeve 71 moves axially by the movement of the lever member 74.

[0045] Protrusions 79 are formed at a plurality of circumferentially spaced positions on the outer end face of the first flange 76. On the other hand, through holes 85 engageable with the protrusions 79 are formed at a plurality of circumferential positions of the output gear 84 at positions opposing the plurality of protrusions 79. The protrusions 79 and the through holes 85 are engaging elements engageable with each other.

[0046] When the clutch sleeve 71 moves outward in the vehicle width direction with respect to the axle 120 and the plurality of protrusions 79 are engaged with the plurality of through holes 85, the axle 120 is connected to the output gear 84 via the clutch sleeve 71, and the clutch mechanism 70 is in a connected state. On the other hand, when the clutch sleeve 71 moves inward in the vehicle width direction with respect to the axle 120 and the plurality of protrusions 79 come out of the plurality of through holes 85, a clutch disengaged state is established in which the axle 120 and the clutch sleeve 71 are relatively rotatable.

[0047] An urging member 132 is provided between the clutch sleeve 71 and the axle 120. Specifically, a retaining ring 133 is locked to the outer peripheral surface of the axle 120 near the bearing 101. An urging member 132 externally fitted to the axle 120 is provided between the retaining ring 133 and the inner end in the vehicle width direction of the clutch sleeve 71. The urging member 132 is a coil spring and elastically urges the clutch sleeve 71 in the axial direction toward the output gear 84 side. Therefore, in the clutch mechanism 70, when switching the lever member 74 from the clutch-disengaged state to the clutch-engaged state, the force required to operate the lever member 74 can be reduced.

[0048] The lever member 74 includes a lever shaft 137 to which an operating tool 135 is fixed, a locking lever 139, and a roller 130 corresponding to a locking portion. The lever shaft 137 is a columnar shaft portion extending in the vertical direction. A hole 140 is formed in the upper portion of the inner case 46 constituting the transmission case 44 so as to communicate from the outer surface to the inner space in the vertical direction. As shown in FIG. 7B, the center line O2 of the hole 140 is along the vertical direction at a position different from the central axis O1 of the axle 120 in the front-rear direction in a top view of the inner case 46. The lever shaft 137 is supported by the inner case 46 in a state of passing through this hole 140. In this state, the lever shaft 137 is rotatable about a first rotation axis L1 orthogonal to an axle parallel line La parallel to the central axis O1 of the axle 120 in the front-rear direction. The first rotation axis L1 coincides with the center line O2 of the hole 140.

[0049] The operating tool 135 is a plate portion having an oval shape in a top view that extends in the lateral direction, with one end fixed to a portion of the lever shaft 137 that protrudes upward from the upper outer surface of the inner case 46. A cylindrical portion 136 protrudes in the vertical direction on the upper surface of one end of the operating tool 135, and the upper end portion of the lever shaft 137 penetrates through the cylindrical portion 136. In this state, a pin 138 penetrates in the lateral direction through the cylindrical portion 136 and the lever shaft 137, enabling the operating tool 135 and the lever shaft 137 to rotate integrally. As a result, the operating tool 135 is fixed to the lever shaft 137. On the other hand, a locking hole 135a (FIG. 7B) that penetrates in the vertical direction is formed at the tip of the operating tool 135. The operating tool 135 is connected via a wire or a link (not shown) locked to the locking hole 135a to a clutch switching instruction unit (not shown) such as a lever provided near the driver's seat 21 of the vehicle.

[0050] As shown in FIG. 7B, the locking lever 139 is plate-shaped with a substantially parallelogram shape in a top view. One half portion (the right half portion in FIG. 7B) in the top view of the locking lever 139 is fixed to the lower end of the lever shaft 137 by welding, screwing, or the like. As a result, the locking lever 139 is provided at one end of the lever shaft 137 and extends in a direction orthogonal to the first rotation axis L1.

[0051] A hole that penetrates in the vertical direction is formed on one side in the width direction of the other half portion (the left half portion in FIG. 7B) in the top view of the locking lever 139, and a shaft portion 141 penetrates and is supported in the hole. The roller 130 is a cylindrical member rotatably supported at a position adjacent to the lower side of the locking lever 139 in the shaft portion 141. As a result, the roller 130 is provided at a position away from the first rotation axis L1 of the locking lever 139 and can rotate about a second rotation axis L2 parallel to the first rotation axis L1.

[0052] The outer diameter of the roller 130 substantially matches the lateral width of the locking groove 78 of the clutch sleeve 71. With the lever shaft 137 penetrating and supported by the hole 140 of the inner case 46, the roller 130 is locked to the locking groove 78.

[0053] When the clutch mechanism 70 is set to the clutch connection state in which power transmission is possible between the output gear 84 and the axle 120 by operating the driver's clutch switching instruction unit, the lever member 74 swings about the first rotation axis L1 in the direction of arrow A1 in FIG. 7B. In this case, a reference virtual plane Pa including the axle parallel line La starting from the first rotation axis L1 is defined. The clutch mechanism 70 is configured such that when the lever member 74 swings in the first direction A1 as described above, the second rotation axis L2, which is the rotation center of the roller 130, is positioned away from the reference virtual plane Pa toward the first direction A1 side. Thereby, the clutch mechanism 70 positions the position T1 (FIG. 7C) of the roller 130 closest to the wall surface 78a on the output gear 84 side of the locking groove 78 away from the reference virtual plane Pa toward the first direction A1 side. At the position T1, the outer peripheral surface of the roller 130 contacts or is in close proximity to the wall surface 78a on the output gear 84 side of the locking groove 78. In this state, as shown in FIG. 7A, a clutch connection state in which the clutch sleeve 71 and the output gear can mesh with each other by meshing elements of a hole and a protrusion is realized. Therefore, the clutch mechanism 70 is configured to be in the clutch connection state when the lever member 74 swings in the first direction A1 as described above.

[0054] On the other hand, FIG. 8A is a diagram corresponding to FIG. 7A showing the clutch disengaged state. FIG. 8B is a cross-sectional view taken along line C-C of FIG. 8A. FIG. 8C is an enlarged view showing a part of FIG. 8B.

[0055] When the clutch mechanism 70 is set to the clutch disengaged state in which power transmission between the output gear 84 and the axle 120 is disconnected by operating the driver's clutch switching instruction unit, the lever member 74 swings about the first axis of rotation L1 in the direction of arrow A2 in FIG. 8B. The clutch mechanism 70 is configured such that when the lever member 74 swings in the second direction A2 as described above, the second axis of rotation L2 of the roller 130 is positioned away from the reference virtual plane Pa on the second direction A2 side. Thereby, the clutch mechanism 70 positions the position T2 (FIG. 8C) of the roller 130 that is closest to the wall surface 78a on the output gear 84 side of the locking groove 78 away from the reference virtual plane Pa on the second direction A2 side. At the position T2, the outer peripheral surface of the roller 130 contacts the wall surface 78a on the output gear 84 side of the locking groove 78. In this state, as shown in FIG. 8A, a clutch disengaged state is realized in which the clutch sleeve 71 is axially separated from the output gear 84 so that the meshing elements of the hole and the protrusion are disengaged between the clutch sleeve 71 and the output gear 84. Therefore, the clutch mechanism 70 is configured to be in the clutch disengaged state when the lever member 74 swings in the second direction A2 as described above.

[0056] As described above, in the clutch engaged state, the position T1 (FIG. 7C) of the roller 130 that is closest to the wall surface 78a on the output gear 84 side of the locking groove 78 is positioned away from the reference virtual plane Pa on the first direction A1 side, so that a so-called dead center crossing state is achieved. In this case, when the position of the roller 130 that is closest to the wall surface 78a on the output gear 84 side of the locking groove 78 is located on the reference virtual plane Pa, the roller 130 is at the dead center position and the contact pressure between the roller 130 and the wall surface is the highest. In the above dead center crossing state, when a release load in the direction of separating the roller 130 from the dead center position is applied to the lever member 74, the connection state of the clutch mechanism 70 remains maintained. Therefore, when the driver does not perform the clutch operation, it is possible to more reliably prevent the clutch from switching from the engaged state to the disengaged state.

[0057] Further, in this example, the locking portion locked to the locking groove 78 of the lever member 74 is a roller 130 that can rotate about a second rotation axis L2 parallel to the first rotation axis L1. As a result, the frictional resistance between the roller 130 and the wall surface of the clutch sleeve 71 is reduced, making it difficult for the lever member 74 to move in the clutch disengagement direction.

[0058] Also, as shown in FIG. 7B, a first stopper 46c for restricting the movement of the roller 130 is provided on the inner surface of the inner case 46 constituting the case 43. The first stopper 46c directly prevents the lever member 74 from moving so that when the position T1 of the roller 130 (FIG. 7C) is located on the first direction A1 side from the reference virtual surface Pa and the clutch is engaged, the lever member 74 does not further swing in the first direction A1. The first stopper 46c is a wall surface facing outward in the vehicle width direction on one side in the front-rear direction (the lower side in FIG. 7B) of the space where the locking lever 139 is disposed in the inner case 46. The side surface of the end portion on the side opposite to the support portion of the roller 130 (the right side in FIG. 7B) in the longitudinal direction of the locking lever 139 abuts against the first stopper 46c. Thereby, after the lever member 74 passes the dead point, it can be prevented from swinging excessively.

[0059] Note that, in the case, a stopper against which a member (not shown) supported by the lever member 74 abuts may be provided so that when the roller 130 is located on the first direction A1 side from the reference virtual surface Pa and the clutch is engaged, the lever member 74 does not further swing in the first direction. Thus, a configuration may be adopted in which the movement of the lever member 74 is indirectly blocked so that the lever member 74 does not further swing in the first direction.

[0060] Also, as shown in FIG. 8B, a second stopper 46d for restricting the movement of the roller 130 is provided on the inner surface of the inner case 46 that constitutes the case 43. The second stopper 46d directly blocks the movement of the lever member 74 so that when the position T2 (FIG. 8C) of the roller 130 is located on the second direction A2 side from the reference virtual surface Pa and the clutch is disengaged, the lever member 74 does not swing further in the second direction A2. The second stopper 46d is a wall surface facing outward in the vehicle width direction on the other side in the front-rear direction of the space in the inner case 46 where the locking lever 139 is disposed (the upper side in FIG. 8B). The side surface of the end portion of the second stopper 46d on the same side as the support portion of the roller 130 (the upper side in FIG. 8B) in the longitudinal direction of the locking lever 139 and on the opposite side in the short side direction from the support portion of the roller 130 (the right side in FIG. 8B) abuts against the locking lever 139. Thereby, it is possible to prevent the lever member 74 from moving excessively in the clutch disengagement direction.

[0061] Also, as shown in FIGS. 7A and 8A, a detent mechanism 144 is provided between the case 43 and the lever shaft 137. The detent mechanism 144 includes conical recesses 145 formed at two circumferentially different positions at the same axial position on the outer peripheral surface of the lever shaft 137, a ball 146 that can engage with the recesses 145 and is disposed in the lateral hole 149 of the inner case 46, and a biasing member 148 that biases the ball 146 toward the lever shaft 137. The biasing member 148 is provided between the tip of a bolt screwed and fixed to the outer end of the lateral hole 149 and the ball 146. As shown in FIG. 7A, in the clutch connected state, the ball 146 engages with one of the two recesses 145. As shown in FIG. 8A, in the clutch disengaged state, the ball 146 engages with the other of the two recesses 145. Thereby, when the lever member 74 rotates, it becomes easier to hold the rotational position of the lever member 74 at either the first rotational position that realizes the clutch connected state or the second rotational position that realizes the clutch disengaged state.

[0062] FIG. 9 is a diagram showing the relationship between the shaft spline groove 122 and the clutch spline groove 72 in part D of FIG. 6, and is a diagram showing the circumferential direction of the axle 120 and the clutch sleeve 71 extended on a plane. As shown in FIG. 9, in the clutch spline groove 72 provided on the inner peripheral surface of the clutch sleeve 71, the groove width is constant except in the vicinity of both axial ends, and in the spline groove 72 on the clutch sleeve 71 side, the groove widths at both ends are constant.

[0063] On the other hand, the shaft spline groove 122 provided on the outer peripheral surface of the axle 120 has a groove width majority portion 123, a groove width reduction portion 124, and a groove width minor portion 125, which are groove elements respectively formed to extend axially at equal circumferential intervals in the circumferential direction. The groove width reduction portion 124 is connected to the end on the inner side in the vehicle width direction (the right side in FIG. 9), which is opposite to the installation side of the output gear 84, in the groove width majority portion 123, and the groove width decreases toward the inner side in the vehicle width direction. The groove width minor portion 125 is connected to the end on the inner side in the vehicle width direction of the groove width reduction portion 124, and the groove width is smaller than that of the groove width majority portion 123. The circumferential center of each groove width reduction portion 124 substantially coincides with the circumferential center of the groove width majority portion 123 to which each groove width reduction portion 124 is connected.

[0064] Thereby, it becomes difficult for the clutch sleeve 71 to move in the direction away from the output gear 84 and for the clutch connection state to be switched to the clutch disconnection state. Therefore, when the driver does not perform a clutch operation, it is possible to more reliably prevent the clutch connection state from being switched to the clutch disconnection state.

[0065] FIG. 10 is a diagram corresponding to FIG. 9 when switching from the clutch connection state to the clutch disconnection state. As shown in FIG. 10(a), in the clutch connection state, when the vehicle is moving forward, each tooth portion 126 between the clutch spline grooves 72 is pressed against one circumferential side of the groove width majority portion 123 of the shaft spline groove 122, and the shaft spline groove 122 and the clutch spline groove 72 are engaged.

[0066] When switching from this state to the clutch disengaged state, first, as shown in Fig. 10(b), the clutch sleeve 71 moves inward in the vehicle width direction, that is, to one side in the axial direction. Due to this movement, the tooth portion 126 of the clutch sleeve 71 is pressed against one circumferential side of the major groove width portion 123 of the axial spline groove 122 while moving toward the groove width reduction portion 124. Then, as shown in Fig. 10(c), each tooth portion 126 moves from the inclined surface 124a inclined with respect to the axial direction of the groove width reduction portion 124 to the minor groove width portion 125 while receiving resistance to the movement. As a result, it becomes difficult to switch to the clutch disengaged state, so when the driver does not perform the clutch operation, it is possible to more reliably prevent switching to the clutch disengaged state.

[0067] Next, the brake mechanism 90 will be described with reference to Fig. 5 and Figs. 11 to 16A. Fig. 11 is a view taken along arrow E in Fig. 4. Fig. 12 is a sectional view taken along line F - F in Fig. 11. Fig. 13 is a sectional view taken along line H - H in Fig. 12. Fig. 14 is a view of the left side portion of Fig. 11 as seen from the same direction, showing the state where the brake case 45 is removed from the outer case 47. Fig. 15 is a sectional view taken along line I - I in Fig. 11. Fig. 16A is a perspective view taken from the traveling motor 30 side, showing the structure in which the brake shaft, brake lever, and movable brake pad are assembled to the brake case 45 and taken out from Fig. 4.

[0068] As shown in Fig. 5, the brake rotor 91 is provided on the second end portion of the input shaft 60 so as not to rotate relative to the input shaft 60 as described above. The brake rotor 91 has a cylindrical portion 92 fitted to the input shaft 60 and a disc-shaped rotor body 93 formed at one axial end of the outer peripheral surface of the cylindrical portion 92. For example, a female spline portion is formed on the inner peripheral surface of the cylindrical portion 92, and the male spline portion formed on the outer peripheral surface of the second end portion of the input shaft 60 engages with the female spline portion of the cylindrical portion 92. Thereby, the brake rotor 91 rotates in synchronization with the input shaft 60.

[0069] Also, as shown in FIG. 12, the brake mechanism 90 is mechanical and includes fixed brake pads 98 and movable brake pads 99 disposed opposite to both axial side surfaces of the brake rotor 91, and a brake shaft 106 and a brake lever 107. The brake shaft 106 is rotatably supported in an upper portion of the brake case 45 so as to extend in the front-rear direction. The brake lever 107 is fixed to a portion of the brake shaft 106 disposed outside the brake case 45.

[0070] The fixed brake pad 98 has a flat rectangular parallelepiped shape. In the outer case 47, the fixed brake pad 98 is fixed to a holding recess 104 (FIG. 14) at a portion facing the upper front portion of one side surface (the lower side surface in FIG. 12) of the rotor body 93.

[0071] On the other hand, as shown in FIG. 16A described later, the movable brake pad 99 has a block shape with an L-shaped cross section. In the brake case 45, a holding recess 105 (FIG. 13) for holding the movable brake pad 99 is formed at a portion facing the upper front portion of the other side surface (the upper side surface in FIG. 12) of the rotor body 93. The holding recess 105 is formed by a pair of vertically facing recesses with a rectangular cross section. The movable brake pad 99 is movable in the axial direction of the brake rotor 91 while being held in the holding recess 105.

[0072] The brake shaft 106 passes through a through hole 48 (FIG. 12) formed in the upper front portion of the brake case 45 and extending in the front-rear direction, and is rotatably supported by the brake case 45. A cam portion 108 having a substantially semicircular cross section is formed at the tip side of the brake shaft 106 disposed in the brake chamber S2. A protrusion 45a is formed on the inner surface of the brake case 45 at a position facing the tip of the brake shaft 106, and a holding recess 45b for rotatably holding the tip of the brake shaft 106 is formed in the protrusion 45a. The movable brake pad 99 is held in the holding recess 105 (FIG. 13) so as to be movable in the axial direction of the brake rotor 91 between the cam portion 108 and the other side surface of the rotor body 93.

[0073] When two operation levers 22 and 23 provided around the driver's seat are operated to the parking brake position, the brake lever 107 rotates in the first direction. As a result, the cam portion 108 provided on the brake shaft 106 also rotates, so that a part of the cam portion 108 protrudes from within the holding recess 104 and presses the movable brake pad 99 against the rotor body 93. Thereby, since the rotor body 93 is clamped between the movable brake pad 99 and the fixed brake pad 98, the left wheel 12 is braked. In this case, since the brake mechanism on the right wheel 13 side also acts in the same manner, the right wheel 13 is also braked.

[0074] On the other hand, when the two operation levers 22 and 23 are operated to a position different from the parking brake position, the brake lever 107 rotates in the second direction, so that the cam portion 108 provided on the brake shaft 106 also rotates and the cam portion 108 retracts into the holding recess 105. Thereby, since the movable brake pad 99 moves away from the rotor body 93, the braking of the left wheel 12 is released. In this case, since the brake mechanism on the right wheel 13 side also acts in the same manner, the braking of the right wheel 13 is also released. Thereby, the vehicle can run.

[0075] A coil spring 109 is provided between the outer surface of the brake case 45 and the brake lever 107. The coil spring 109 is biased so that the brake lever 107 rotates in the second direction.

[0076] Note that a brake pedal (not shown) that can be operated by the driver's foot is provided in front of the driver's seat 21 of the vehicle. When the brake pedal is operated, regenerative braking is performed in the left and right traveling motors 30 and 31, and the rotation of each traveling motor 30 and 31 is stopped.

[0077] Also, as shown in FIGS. 4, 11, and 14, in the outer case 47, an air breather device 110 is provided at the upper part of the portion facing the rear side portion of the brake case 45. The air breather device 110 is attached in the outer case 47 to a vertical through hole (not shown) communicating with the brake chamber S2 (FIG. 5). The air breather device 110 is provided to prevent liquids such as water and dust from entering from the upper side, and to enable the air inside the brake chamber S2 to be sucked and discharged to the outside of the case 43 when the lubricating oil in the brake chamber S2 expands. When the internal pressure of the brake chamber S2 rises, air is discharged to the outside of the case 43 through the air breather device 110, thereby preventing an excessive rise in the internal pressure.

[0078] Also, as shown in FIGS. 12 and 16A, in the rear side portion of the upper side portion of the brake case 45, at a position aligned in the front-rear direction with the through hole 48 (FIG. 12) in the front side portion, a second through hole 111 penetrating in the front-rear direction is formed so as to be symmetric with respect to the center in the front-rear direction of the through hole 48. A plug 112 is attached to the outer end portion of the second through hole 111 to prevent the oil sealed inside the brake case 45 from leaking out. Also, the brake case 45 has a symmetric shape with respect to the center in the front-rear direction. Therefore, for the brake case 45, parts having the same structure can be commonly used for the right wheel and the left wheel by reversing the front and rear directions.

[0079] FIG. 16B is a view corresponding to FIG. 16A for the right wheel 13. When using the brake case 45 for the left wheel 12 for the right wheel, as shown in FIG. 16B, a plug is attached to the outer end portion of the through hole on the rear side, and the brake shaft 106 to which the brake lever 107 is fixed penetrates and supports the second through hole 111 (FIG. 16A) on the front side.

[0080] Further, the outer case 47 and the inner case 46 are each symmetric with respect to the center in the vertical direction. For example, as shown in FIG. 14, in the outer case 47, a second through hole (not shown) is formed at a position that aligns vertically with the through hole to which the air breather device 110 is attached. By attaching a plug to the lower end of the second through hole, leakage of oil from the brake chamber is prevented.

[0081] Also, as shown in FIG. 14, in the outer case 47, a holding recess 104 for holding the fixed brake pad 98 is formed on the outer surface covered by the brake case 45 (FIG. 12), and a second holding recess 113 is formed at a symmetric position with respect to the center in the vertical direction. Therefore, for each of the outer case 47 and the inner case 46, parts with the same structure can be commonly used for the right wheel and the left wheel with the vertical orientation reversed. When using the outer case 47 for the left wheel 12 for the right wheel 13, a plug is attached to the outer end of the lower through hole, and the air breather device 110 is attached to the upper second through hole. Also, in the outer case 47, among the two holding recesses 104 and 113 for holding the fixed brake pad 98, the fixed brake pad 98 is held only in the upper second holding recess 113.

[0082] According to the vehicle power transmission structure configured as described above, when the driver does not perform a clutch operation, it is possible to more reliably prevent switching from the clutch engaged state to the clutch disengaged state.

[0083] (Second Embodiment) FIG. 17A is a cross-sectional view of a part in the circumferential direction of the output gear 84a and the clutch sleeve 71b showing the clutch disengaged state in a vehicle power transmission structure according to another example of the embodiment. FIG. 17B(a) is a view showing the upper half side surface of the clutch sleeve 71b on the output gear 84a side in another example of the embodiment. FIG. 17B(b) is a cross-sectional view taken along the line K-K of FIG. 17B(a). FIG. 17A corresponds to a cross-sectional view taken along the line J-J of FIG. 17B.

[0084] In the configuration of this example, on the surface of the first flange 76a of the clutch sleeve 71b on the side of the output gear 84a in the axial direction, projections 150 having a substantially trapezoidal cross-section are formed at a plurality of positions at equal intervals in the circumferential direction. Each projection 150 has a circumferential length that increases toward the radially outer side. The side surfaces on both sides in the radial direction of each projection 150 are curved surfaces having an arcuate cross-section centered on the central axis of the clutch sleeve 71b. The plurality of projections 150 form a projection group 151.

[0085] On the other hand, on the surface of the output gear 84a on the side of the clutch sleeve 71b in the axial direction, a plurality of through-holes 85a engageable with the plurality of projections 150 are provided. Each through-hole 85a has a main body hole portion 152 having a substantially trapezoidal cross-section and penetrating in the axial direction of the output gear 84a and being engageable with the projection 150, and two shallow recesses 153 and 154 provided at both circumferential ends of the open end on the clutch sleeve 71b side of the main body hole portion 152. One of the two shallow recesses 153 is a stepped portion having the same shape as one circumferential end portion (the left end portion in FIG. 17A) of each projection 150 and having a flat substantially trapezoidal cross-sectional shape extending in the radial direction. The other shallow recess 154 of the two shallow recesses 153 and 154 has the same shape as the other circumferential end portion (the right end portion in FIG. 17A) of each projection 150 and is a stepped portion having a flat substantially trapezoidal cross-sectional shape extending in the radial direction. A hole group 86 is provided by the plurality of through-holes 85a.

[0086] The axial depth of each of the shallow recesses 153 and 154 in the output gear 84 is smaller than the axial depth of the main body hole portion 152, which is a portion different from the shallow recesses 153 and 154 of the through-hole 85a. When the clutch sleeve 71b and the output gear 84a are in a clutch-connected state, the plurality of projections 150 enter the main body hole portions 152 of the plurality of through-holes 85a.

[0087] According to the configuration of this example, when the clutch sleeve 71b meshes with the output gear 84a, as shown in Fig. 17A, from the state where the clutch sleeve 71b and the output gear 84a are separated, the clutch sleeve 71b rotates in one circumferential direction of Fig. 18A with respect to the output gear 84a, and between the adjacent through holes 85a of the output gear 84a, the protrusion 150 of the clutch sleeve 71b and the protrusion 150 of the clutch sleeve 71b are axially opposed. From this state, the clutch sleeve 71b rotates further in one circumferential direction with respect to the output gear 84a while approaching each other axially. Then, the circumferential end portion of the protrusion 150 engages with the shallow concave portions 153 and 154 on one side. In this state, the relative rotation amount between the clutch sleeve 71b and the output gear 84a becomes small, and even when the play in the circumferential direction between the protrusion 150 of the clutch sleeve 71b and the main body hole portion 152 of the through hole 85a of the output gear 84a is reduced, the protrusion 150 and the main body hole portion 152 gradually engage in a fitted state.

[0088] In the above, the case where the clutch sleeve 71b rotates in one circumferential direction of Fig. 17A with respect to the output gear 84a has been described. However, when the clutch sleeve 71b rotates in the other circumferential direction of Fig. 17A with respect to the output gear 84a, it is the same as the case of rotating in one side except that the rotation direction is different.

[0089] As a result, the play in the circumferential direction when the clutch sleeve 71b and the output gear 84a engage can be reduced, and it becomes easier to shift from the state where the portion between the through holes 85a of the clutch sleeve 71b and the protrusion 150 face each other to the meshed state. Also, the strength of each protrusion 150 can be increased compared to the structure in which stepped surfaces are provided on both sides in the circumferential direction at the tip of each protrusion to facilitate engagement with the hole. In this example, other configurations and operations are the same as those in Figs. 1 to 16B.

[0090] (Third Embodiment) FIG. 18A is a cross-sectional view of a part of the circumferential direction of an output gear 84b and a clutch sleeve 71c, showing a clutch disengaged state, in a vehicle power transmission structure according to another example of the embodiment. FIG. 18B(a) is a view showing a side surface of the upper half portion on the output gear 84b side of the clutch sleeve 71c in another example of the embodiment. FIG. 18B(b) is a cross-sectional view taken along line M-M of FIG. 18B(a). FIG. 18A corresponds to a cross-sectional view taken along line L-L of FIG. 18B.

[0091] In the configuration of this example, in the configurations of FIGS. 17A and 17B, a stepped portion 155 is formed in the circumferentially other side portion of the tip surface of each protrusion 150a of the clutch sleeve 71c so as to have a lower height. Further, in each through hole 85b of the output gear 84b, a shallow recess 153a is provided only at one circumferential end of the open end of the main body hole portion 152 on the clutch sleeve 71 side. The circumferential length of the shallow recess 153a is larger than that of the shallow recess 153 in the configuration of FIG. 17A.

[0092] In such a configuration, when the clutch sleeve 71c rotates in one circumferential direction (the direction of arrow α in FIG. 19) with respect to the output gear 84b at the initial stage of engagement, and when it rotates in the other circumferential direction, even if the circumferential rattling between the protrusion 150a and the main body hole portion 152 of the through hole 85b is reduced, the protrusion 150a and the main body hole portion 152 are easily fitted together.

[0093] This will be described in detail with reference to FIGS. 19 and 20. First, with reference to FIG. 19, a case where the clutch sleeve 71c rotates in one circumferential direction (the direction of arrow α in FIG. 19) with respect to the output gear 84b at the initial stage of switching to the clutch engaged state will be described. FIG. 19 is a view corresponding to FIG. 18A showing the switching operation from the clutch disengaged state to the clutch engaged state when the clutch sleeve 71 rotates in one circumferential direction (the direction of arrow α) with respect to the output gear 84b at the initial stage of switching to the clutch engaged state.

[0094] In this case, as shown in Fig. 19(a), when the clutch sleeve 71c approaches the output gear 84b axially, the phase of the tip of each protrusion 150a of the clutch sleeve 71c and the tip of the column portion 156 located between the adjacent through holes 85b of the output gear 84b coincides, and the tip of the protrusion 150a and the tip of the column portion 156 may abut against each other. Even in this case, when the clutch sleeve 71c rotates a little in the direction of arrow α, as shown in Fig. 19(b), due to the stepped portion 155 provided on the protrusion 150a of the clutch sleeve 71c, the tip of the column portion 156 of the output gear 84b is displaced early from the tip of the protrusion 150a. Then, as shown in Fig. 19(c), while the tip portion of the clutch sleeve 71c is gradually fitted into the through hole 85b of the output gear 84b, the clutch sleeve 71c can continue to rotate in the direction of arrow α. Then, as shown in Fig. 19(d), the tip portion of the protrusion 150a of the clutch sleeve 71c fits into the shallow recess 153a of the output gear 84b and abuts against the column portion 156 in the circumferential direction, thereby achieving a clutch connection state.

[0095] In the state of Fig. 19(d), the clutch sleeve 71c can rotate and move in the other circumferential direction (the direction of arrow β in Fig. 19). However, since the protrusion 150a is fitted into the clutch sleeve 71c, the range of its rotatability in the other circumferential direction is small. Then, as shown in Fig. 19(e), the entire protrusion 150a of the clutch sleeve 71c faces the main body hole portion 152 of the through hole 85b. When a force in the direction toward the outside in the vehicle width direction acts on the clutch sleeve 71c based on the operating force of the driver or the like in this state, the protrusion 150a of the clutch sleeve 71c fits into the through hole 85b of the output gear 84b in the direction of arrow γ, resulting in the state of Fig. 19(f).

[0096] In this case, the circumferential gap when the protrusion 150a is fitted into the through-hole 85b is small. Even when the gap is small like this, as shown in FIGS. 19(c) to 19(e), once the clutch sleeve 71c is inserted into the output gear 84b, the range within which the clutch sleeve 71c can rotate with respect to the output gear 84b becomes small. Therefore, even when the above-mentioned gap is small, the protrusion 150a of the clutch sleeve 71c easily fits into the through-hole 85b of the output gear 84b at an early stage. Thus, even when the circumferential rattling between the main body hole portion 152 of the through-hole 85b and the protrusion 150a of the output gear 84b is reduced, it is easy to fit the protrusion 150a and the main body hole portion 152 together.

[0097] Using FIG. 20, the case where the clutch sleeve 71c rotates in the circumferential direction to the other side (in the direction of arrow β in FIG. 20) with respect to the output gear 84b at the initial stage of switching to the clutch connection state will be described. FIG. 20 is a diagram corresponding to FIG. 18A showing the switching operation from the clutch disconnection state to the clutch connection state when the clutch sleeve 71c rotates in the circumferential direction to the other side (in the direction of arrow β) with respect to the output gear 84b at the initial stage of switching to the clutch connection state.

[0098] In this case, as shown in FIG. 20(a), similar to the case shown in FIG. 19(a), the clutch sleeve 71c approaches the output gear 84b in the axial direction, and the tip of each protrusion 150a of the clutch sleeve 71c and the tip of the column portion 156 may abut against each other. Even in this case, when the clutch sleeve 71c rotates a little in the direction of arrow β, as shown in FIG. 20(b), due to the shallow recess 153a provided in the through-hole 85b of the output gear, the tip of the column portion 156 is in a state of being displaced early from the tip of the protrusion 150a. Then, as shown in FIG. 20(c), while the tip portion of the clutch sleeve 71c is gradually inserted into the through-hole 85b of the output gear 84b, the clutch sleeve 71c can continue to rotate in the direction of arrow β. And when the tip portion of the protrusion 150a of the clutch sleeve 71c enters the main body hole portion 152 of the through-hole 85b of the output gear 84b and abuts against the column portion 156 in the circumferential direction, the clutch connection state is achieved (FIG. 20(d)).

[0099] In the state of Fig. 20(d), the clutch sleeve 71c can rotate and move in the circumferential direction on one side (the direction of arrow α in Fig. 20). However, since the protrusion 150a is fitted into the clutch sleeve 71c, the range of rotatability in the circumferential direction on that one side is small. Then, as shown in Fig. 20(e), the entire protrusion 150a of the clutch sleeve 71c faces the through-hole 85b. In this state, when a force in the direction toward the outside in the vehicle width direction acts on the clutch sleeve 71c based on the operating force of the driver or the like, the protrusion 150a of the clutch sleeve 71c fits into the through-hole 85b of the output gear 84b in the direction of arrow γ, resulting in the state of Fig. 20(f).

[0100] Also in this case, similar to the case of Fig. 19, even when the circumferential clearance at the time of fitting between the protrusion 150a and the through-hole 85b is small, once the clutch sleeve 71c fits into the output gear 84b, the range of rotatability of the clutch sleeve 71c with respect to the output gear 84b becomes small. Therefore, even when the rattling in the circumferential direction between the main body hole portion 152 of the through-hole 85b and the protrusion 150a of the output gear 84b is reduced, it is easy to fit the protrusion 150a and the main body hole portion 152. In this example, the other configurations and operations are the same as those of the configurations in Figs. 1 to 16B or the configurations in Figs. 17A and 17B.

[0101] Note that in the configurations of the above examples, the locking portion is the rotatable roller 130. However, the locking portion may have a structure that is fixed and does not rotate with respect to the locking lever of the lever member. Even in this case, the power transmission structure positions the position of the locking portion that is closest to the gear-side wall surface of the locking groove among the locking portions when the lever member swings in the first direction about the first rotation axis, away from the reference virtual plane Pa on the first direction side. Thereby, the clutch sleeve 71c can be configured to be in the clutch connection state. Also, when the lever member swings in the second direction about the first rotation axis, the position of the locking portion that is closest to the wall surface among the locking portions is positioned away from the reference virtual plane on the second direction side. Thereby, the clutch can be configured to be in the disengaged state.

[0102] In addition, in the configurations of the above examples, a configuration is adopted in which a plurality of protrusions of the clutch sleeve are engaged with a plurality of through holes formed in the output gear. However, the through hole may be a recess which is a hole with one end closed. Further, a configuration may be adopted in which a protrusion formed on the output gear is engaged with a through hole or a recess formed in the clutch sleeve. For example, in the configurations of the examples shown in FIGS. 17A to 20, a protrusion group having a plurality of protrusions is provided on the axial side surface of the clutch sleeve of the output gear, which axially faces the output gear. In the clutch sleeve, a hole group having a plurality of through holes or recesses may be provided on the axial side surface which axially faces the output gear.

[0103] In addition, in the configurations of the above examples, a configuration has been described in which the left and right wheels can be driven independently of each other, the left wheel is driven by the left electric motor, and the right wheel is driven by the right electric motor. On the other hand, the present invention can also be applied to a vehicle in which the left and right wheels are commonly driven by an electric motor.

[0104] In addition, in the configurations of the above examples, the case of a traveling motor in which the power source is an electric motor has been described. However, the present invention can also be applied to a configuration in which the power source is another drive source such as an engine or a hydraulic motor.

Explanation of Reference Numerals

[0105] 10 Vehicle, 12 Left wheel, 13 Right wheel, 15, 16 Caster wheels, 18 Lawn mowing device, 18a - 18c Lawn mowing blades, 18d Discharge duct, 19 Mower deck, 20 Main frame, 20a, 20b Side plate parts, 20c Connecting part, 21 Driver's seat, 22, 23 Operating levers, 24 Gripping part, 26, 27 Guide panels, 30 Left traveling motor (traveling motor), 31 Right traveling motor, 32 Motor shaft, 34 Battery, 41, 42 Power transmission structure, 43 Case, 44 Transmission case, 45 Brake case, 46 Inner case, 47 Outer case, 48 Through - hole, 49 Cylindrical part, 50, 51 Bearings, 52 Hub, 60 Input shaft, 61 Cylindrical part, 63 Deck motor, 70 Clutch mechanism, 71, 71a, 71b, 71c Clutch sleeves, 72, 72a Clutch spline grooves, 74 Lever member, 75 Cylindrical part, 76 First flange, 77 Second flange, 78 Locking groove, 79 Protrusion, 80 Gear mechanism, 81 First spur gear, 82 Intermediate gear shaft, 83 Second spur gear, 84, 84a, 84b Output gears, 85, 85a Through - holes, 86 Hole group, 90 Brake mechanism, 91 Brake rotor, 92 Cylindrical part, 93 Rotor body, 98 Fixed brake pad, 99 Movable brake pad, 100 Cylindrical part, 101 Bearing, 104, 105 Holding recesses, 106 Brake shaft, 107 Brake lever, 108 Cam part, 109 Coil spring, 110 Air breather device, 111 Second through - hole, 112 Plug, 113 Second holding recess, 120, 121 Axles, 122, 122a Axle spline grooves, 123, 123a Wide groove parts, 124 Groove width reduction part, 125, 125a Narrow groove parts, 126, 126a Tooth parts, 127, 128 Groove width reduction parts, 130 Roller, 132 Biasing member, 133 Retaining ring, 135 Operating tool, 137 Lever shaft, 139 Locking lever, 140 Hole, 141 Shaft part, 142 Second stopper, 144 Detent mechanism, 145 Recess, 146 Ball, 148 Biasing member, 149 Lateral hole, 150, 150a Protrusions, 151 Protrusion group, 152 Body hole part, 153, 154 Shallow recesses, 155 Step part, 156 Column part

Claims

1. An axle that directly or indirectly drives a ground wheel, A gear that is rotatably fitted to the outside in the radial direction of the axle and to which power for driving the ground wheel is input, A clutch sleeve that is non-rotatable relative to the axle and is slidably fitted axially adjacent to the gear, A lever member that reciprocates the clutch sleeve axially, Comprising, Engaging elements of holes and protrusions that can mesh with each other are provided between the opposing surfaces of the gear and the clutch sleeve, and a power transmission structure for a vehicle that switches the connection and disconnection of power transmission between the gear and the axle by the movement of the clutch sleeve, A locking groove is formed over the entire outer peripheral surface of the clutch sleeve, The lever member is rotatable about a first rotation axis orthogonal to an axle parallel line parallel to the central axis of the axle, a lever shaft to which an operating tool is fixed, a locking lever provided at one end of the lever shaft and extending in a direction orthogonal to the first rotation axis, and a locking portion provided at a position of the locking lever away from the first rotation axis and locked to the locking groove, A reference virtual plane including the axle parallel line starting from the first rotation axis is defined, When the lever member swings in a first direction about the first rotation axis, among the locking portions, the position closest to the wall surface on the gear side of the locking groove is positioned away from the reference virtual plane toward the first direction side, whereby the clutch sleeve is configured to be in a clutch connection state in which it can mesh with the gear and the meshing elements, and when the lever member swings in a second direction about the first rotation axis, among the locking portions, the position closest to the wall surface is positioned away from the reference virtual plane toward the second direction side, whereby the clutch sleeve is configured to be in a clutch disconnection state in which it is axially separated from the gear, Power transmission structure for a vehicle.

2. The locking portion is a roller that is provided at a position of the locking lever away from the first rotation axis and is rotatable about a second rotation axis parallel to the first rotation axis and is locked to the locking groove, The power transmission structure for a vehicle according to Claim 1.

3. Comprising a case that houses the axle, the gear, the clutch sleeve, and the lever member, In the case, a stopper is provided in the case to directly or indirectly prevent the movement of the lever member so that when the locking portion is located on the first direction side of the reference virtual plane and clutch-connected, the lever member does not further swing in the first direction. The vehicle power transmission structure according to claim 1.

4. A shaft spline groove provided on the outer peripheral surface of the axle and a clutch spline groove provided on the inner peripheral surface of the clutch sleeve are in spline engagement. The shaft spline groove has a groove width reduction portion in which the groove width decreases toward the side opposite to the installation side of the gear in the axial direction. The vehicle power transmission structure according to claim 1.

5. On one of the clutch sleeve and the gear, a group of protrusions is provided on the axial side surface axially opposed to the other. On the other of the clutch sleeve and the gear, a group of holes is provided on the axial side surface axially opposed to the one. At least one circumferential one-side end of each of the holes in the group of holes is provided with a shallow recess, and the axial depth of the shallow recess is smaller than the axial depth of a portion of the hole different from the shallow recess. When the clutch sleeve and the gear are in the clutch-connected state, the plurality of protrusions enter into portions of the plurality of holes that are axially deeper than the shallow recesses. The vehicle power transmission structure according to claim 1.

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