Working vehicle

Abstract

To provide a working vehicle that can reduce stirring resistance of a gear in a transmission mechanism case provided adjacently to a speed change device housing chamber in which a hydraulic pump and a hydraulic motor are housed.SOLUTION: A working vehicle comprises: a speed change device housing chamber in which a hydraulic pump, and a hydraulic motor to be driven by oil discharged from the hydraulic pump are housed; and a transmission mechanism case provided adjacently to the speed change device housing chamber, and housing a transmission mechanism including an input gear to which power from a prime mover is inputted, and a transmission gear for transmitting the power transmitted from the input gear to the hydraulic pump. The inside of the transmission mechanism case is a chamber separated from the speed change device housing chamber.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to a work vehicle.

Background Art

[0002] Conventionally, a work vehicle disclosed in Patent Document 1 is known.

[0003] The work vehicle disclosed in Patent Document 1 includes a continuously variable transmission case and a transmission mechanism case. In the continuously variable transmission case, a transmission device accommodation chamber is formed in which a hydraulic pump and a hydraulic motor driven by oil discharged from the hydraulic pump are accommodated. The transmission mechanism case is provided adjacent to the transmission device accommodation chamber and houses a transmission mechanism (branch transmission mechanism 15A) including an input gear to which power from the prime mover is input and a transmission gear that transmits the power transmitted from the input gear to the hydraulic pump.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a conventional work vehicle, the transmission device accommodation chamber is in a state of being filled with oil, and the transmission mechanism case is in a state where there is oil flow with the transmission device accommodation chamber. Therefore, the inside of the transmission mechanism case is also in a state of being filled with oil. When the inside of the transmission mechanism case is filled with oil, there is a problem that the stirring resistance of the gears inside the transmission mechanism case is large. When the stirring resistance of the gears inside the transmission mechanism case is large, a horsepower loss occurs due to the large stirring resistance of the gears.

[0006] In view of the above problems, an object of the present invention is to provide a work vehicle capable of reducing the stirring resistance of gears in a transmission case provided adjacent to a transmission case accommodating a hydraulic pump and a hydraulic motor.

Means for Solving the Problems

[0007] A work vehicle according to an aspect of the present invention includes a transmission case accommodating a hydraulic pump and a hydraulic motor driven by oil discharged from the hydraulic pump, an input gear provided adjacent to the transmission case and into which power from a prime mover is input, and a transmission gear that transmits the power transmitted from the input gear to the hydraulic pump. The transmission case houses a transmission mechanism including the transmission gear, and the inside of the transmission case is a separate chamber from the transmission case accommodating the hydraulic pump.

[0008] The work vehicle includes an orifice that communicates the inside of the transmission case accommodating the hydraulic pump and the inside of the transmission case. In a portion other than the orifice, the inside of the transmission case accommodating the hydraulic pump and the inside of the transmission case may be partitioned so that oil in the transmission case accommodating the hydraulic pump does not flow into the inside of the transmission case.

[0009] The work vehicle includes a supply pump capable of supplying purified oil into the transmission case accommodating the hydraulic pump and an outflow passage for discharging oil inside the transmission case. The flow rate of the oil may be set so that the oil in the transmission case accommodating the hydraulic pump is full and the oil level of the oil inside the transmission case is located at a middle portion in the vertical direction inside the transmission case.

[0010] The work vehicle may include a continuously variable transmission case forming the transmission device accommodation chamber, and a transmission case connected to the opposite side of the continuously variable transmission case to the transmission mechanism case and accommodating a traveling system transmission mechanism that changes the speed of power output from the hydraulic motor and transmits it to drive wheels, and the supply pump may be configured to replenish oil from inside the transmission case sucked in through an oil filter into the transmission device accommodation chamber, and the outflow path may be configured to allow the oil from inside the transmission mechanism case to flow out into the inside of the transmission case.

[0011] The input gear may be disposed at an upper portion inside the power transmission mechanism case and above the transmission gear, and the orifice may be provided at a height within a range of a cutting edge diameter of the input gear.

[0012] The work vehicle has a through-type wall that separates the transmission housing chamber from the inside of the power transmission case. The nozzle may further include a plug for closing a through hole formed in the nozzle, the orifice being formed in the plug.

[0013] The orifice may have a small hole portion communicating with the transmission accommodating chamber, and a large hole portion having a diameter larger than that of the small hole portion and communicating with the small hole portion and the interior of the power transmission mechanism case.

[0014] The orifice may have an expanding diameter portion that connects the narrow hole portion and the large hole portion and that gradually expands in diameter from the narrow hole portion toward the large hole portion. Effect of the Invention

[0015] According to the above-mentioned work vehicle, the interior of the power transmission case adjacent to the transmission housing chamber is separated from the transmission housing chamber, so that the oil level inside the power transmission case can be lowered. This reduces the stirring resistance of the gears inside the power transmission case, and ultimately reduces horsepower loss. [Brief description of the drawings]

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Embodiments for Carrying Out the Invention

[0017] Hereinafter, an embodiment of the present invention will be described with appropriate reference to the drawings.

[0018] FIG. 1 shows a side view of the work vehicle 1 of the present embodiment. In the present embodiment, a tractor is exemplified as the work vehicle 1. Hereinafter, the work vehicle 1 will be described as being a tractor, but the work vehicle 1 is not limited to a tractor.

[0019] As shown in FIG. 1, the tractor 1 is provided with a driver's seat 2 on which the operator sits.

[0020] In the following description, the front side (in the direction of arrow A1 in FIG. 1) of the operator sitting on the driver's seat 2 is defined as the front, and the rear side (in the direction of arrow A2 in FIG. 1) of the operator is defined as the rear. Also, the left side (the near side in FIG. 1) of the operator is defined as the left, and the right side (the far side in FIG. 1) of the operator is defined as the right.

[0021] Also, the direction indicated by arrow K1 in FIG. 1 is described as the front-rear direction. Also, the horizontal direction orthogonal to the front-rear direction K1 is referred to as the vehicle width direction. Also, in the vehicle width direction, the direction from the central part of the tractor 1 toward the right part or the left part is referred to as the outer side in the vehicle width direction. Also, in the vehicle width direction, the direction from the right part or the left part of the tractor 1 toward the central part of the tractor 1 is referred to as the inner side in the vehicle width direction.

[0022] As shown in FIG. 1, the tractor 1 includes a vehicle body 3, front wheels 4 provided on the left and right of the front part of the vehicle body 3, rear wheels 5 provided on the left and right of the rear part of the vehicle body 3, and a driver's cab 7 provided above the vehicle body 3 and equipped with a steering wheel 6, a driver's seat 2, etc. The front wheels 4 are steerable wheels. Also, in this embodiment, the front wheels 4 and the rear wheels 5 are drivable drive wheels. Note that the drive wheels may be only the rear wheels 5 or only the front wheels 4. The front wheels 4 and the rear wheels 5 constitute a traveling device that supports the vehicle body 3 so as to be able to travel.

[0023] As shown in FIG. 1, the vehicle body 3 includes an engine (prime mover) 8 as a power source, a front frame connected to the engine 8 and protruding forward from the engine 8, and a power transmission case 10 connected to the rear part of the engine 8 and extending rearward from the engine 8. A PTO shaft 9 for taking out the power of the engine 8 to the outside is provided at the rear part of the power transmission case 10 (vehicle body 3).

[0024] The engine 8 is a diesel engine in this embodiment. The engine 8 may be a gasoline engine. Also, the power source may be a prime mover other than the engine. For example, it may be an electric motor.

[0025] As shown in FIG. 2, the power transmission case 10 includes a flywheel housing 11 connected to the rear part of the engine 8, a clutch housing 12 connected to the rear part of the flywheel housing 11, a continuously variable transmission case 13 connected to the rear part of the clutch housing 12, and a transmission case 14 connected to the rear part of the continuously variable transmission case 13.

[0026] The flywheel housing 11 houses a flywheel 15 that rotates integrally with the crankshaft of the engine 8. The clutch housing 12 houses a main clutch 16 that intermittently transmits the power of the engine 8 transmitted through the flywheel 15. The continuously variable transmission case 13 houses a hydraulic pump (referred to as an HST pump) 18 and a hydraulic motor (referred to as an HST motor) 19, which are components of a continuously variable transmission (HST: hydrostatic continuously variable transmission) 17 (see FIGS. 8 and 9). The transmission case 14 houses a traveling system transmission mechanism (see FIG. 3) 20 that shifts the power output from the continuously variable transmission 17 and transmits it to the drive wheels.

[0027] FIG. 3 shows a power transmission system 21 that transmits the power of the engine 8. The power transmission system 21 includes a transmission mechanism 22 that branches and transmits the power of the engine 8, a traveling system power transmission system 23 that transmits the power of the engine 8 to the drive wheels (front wheels 4 and rear wheels 5), and a PTO system power transmission system 24 that transmits the power of the engine 8 to the PTO shaft 9.

[0028] As shown in FIG. 3, the transmission mechanism 22 is configured to include an input gear 25 and a pair of transmission gears 26 and 27. As shown in FIG. 8, a shaft portion 28 extending forward from the input gear 25 is integrally formed on the input gear 25. The power of the engine 8 that has passed through the flywheel 15 and the main clutch 16 is transmitted to the input gear 25 via the shaft portion 28. As shown in FIG. 8, the input gear 25 has a supported portion 25a protruding rearward from the center of rotation.

[0029] As shown in FIG. 3, the input gear 25 meshes with the pair of transmission gears 26 and 27 and transmits power to the pair of transmission gears 26 and 27. The first transmission gear 26, which is one of the pair of transmission gears 26 and 27, rotates integrally with the first transmission shaft 29. The second transmission gear 27, which is the other of the pair of transmission gears 26 and 27, rotates integrally with the second transmission shaft 30. As shown in FIG. 12, the first transmission gear 26 has a first supported portion 26a protruding forward and a second supported portion 26b protruding rearward. As shown in FIG. 13, the second transmission gear 27 has a first supported portion 27a protruding forward and a second supported portion 27b protruding rearward.

[0030] As shown in FIG. 3, the traveling system power transmission system 23 includes a continuously variable transmission 17 to which the power from the engine 8 is transmitted, and a traveling system transmission mechanism 20 that shifts the power output from the continuously variable transmission 17 and transmits it to the drive wheels.

[0031] First, the continuously variable transmission 17 will be described.

[0032] As described above, the continuously variable transmission 17 includes an HST pump 18 and an HST motor 19. The HST pump 18 is driven by the power from the engine 8. The HST motor 19 is rotationally driven by the oil discharged from the HST pump 18.

[0033] As shown in FIG. 4, the HST pump 18 is constituted by an inclined plate type variable displacement pump. Further, power from the engine 8 is transmitted to the HST pump 18 via the first transmission shaft 29, and the HST pump 18 is driven by the rotational power of the first transmission shaft 29. When a cylinder 31 interlocked with the inclined plate of the HST pump 18 is operated, the angle of the inclined plate is changed by the cylinder 31, and the discharge amount and the discharge direction can be changed. The HST motor 19 is connected in a closed circuit with the HST pump 18 by a pair of speed change oil passages 32a and 32b. The HST motor 19 is rotationally driven in the forward rotation direction or the reverse rotation direction by the oil discharged from the HST pump 18, and outputs rotational power continuously variable in either the forward rotation direction or the reverse rotation direction from the motor shaft 33.

[0034] Note that the continuously variable transmission 17 can be set to a neutral state positioned between the forward rotation state and the reverse rotation state by changing the angle of the inclined plate of the HST pump 18.

[0035] As shown in FIG. 4, of the pair of speed change oil passages 32a and 32b, oil can be replenished to the low-pressure side speed change oil passages 32a and 32b via a charge circuit 34. The charge circuit 34 has high-pressure relief valves 35a and 35b that release oil to the low-pressure side speed change oil passages 32a and 32b when the pressure in the high-pressure side speed change oil passages 32a and 32b becomes equal to or higher than a set value, an oil passage 36 between the high-pressure relief valve 35a and the high-pressure relief valve 35b, and a replenishment oil passage 39 connected to the oil passage 36. Discharge oil from a supply pump (charge pump) 37 is supplied to the oil passage 36. Specifically, the supply pump 87 is driven by the first transmission shaft 29, sucks in and discharges oil (transmission oil) in the transmission case 14 via an oil filter 37. The oil discharged from the supply pump 87 flows through an oil filter 38 and the replenishment oil passage 39 into the oil passage 36. Further, the charge circuit 34 has a charge relief valve 40 that sets the circuit pressure of the charge circuit 34, and the charge relief valve 40 communicates with the replenishment oil passage 39.

[0036] As shown in FIGS. 8 and 9, the continuously variable transmission case 13 forms a transmission housing chamber 41 that houses the HST pump 18 and the HST motor 19. The transmission housing chamber 41 includes a front wall 42 that constitutes the front part of the transmission housing chamber 41, an upper wall 43 that constitutes the upper part, a bottom wall 44 that constitutes the bottom part, left and right side walls 45a and 45b that constitute the left and right side parts, and a port plate 46 that constitutes the rear part.

[0037] The transmission housing chamber 41 is in a state where its interior is filled with oil. Oil (purified oil) from the supply pump 87 can be supplied into the transmission housing chamber 41. For example, oil can be replenished from the replenishment oil passage 39 into the transmission housing chamber 41.

[0038] Next, the traveling system transmission mechanism 20 will be described.

[0039] As shown in FIG. 3, the traveling system transmission mechanism 20 includes a planetary gear mechanism 47, a forward and reverse switching mechanism 48, and a sub-transmission mechanism 49. The planetary gear mechanism 47 includes a sun gear 47a, a plurality of planetary gears 47b provided around the sun gear 47a, a carrier 47c that rotatably supports each planetary gear 47b, a ring gear 47d that meshes with the plurality of planetary gears 47b, and an output shaft 47e that outputs power.

[0040] The rotational power output from the motor shaft 33 of the HST motor 19 is input to the sun gear 47a. The rotational power of the second transmission shaft 30 is input to the carrier 47c. The planetary gear mechanism 47 combines the driving force from the continuously variable transmission 17 and the driving force from the engine 8 that is not subject to the speed change action of the continuously variable transmission 17, and outputs the combined driving force from the output shaft 47e to the input shaft 48a of the forward and reverse switching mechanism 48.

[0041] The forward and reverse switching mechanism 48 outputs the driving force transmitted to the input shaft 48a from either the forward output gear train 48b that transmits forward driving force or the reverse gear train 48c that transmits reverse driving force. The forward and reverse switching mechanism 48 has a switching clutch 48d that switches the power transmission state between a state of transmitting forward driving force and a state of transmitting reverse driving force.

[0042] The auxiliary transmission mechanism 49 switches the power output from the output shaft 48e of the forward and reverse switching mechanism 48 and outputs it in either a low speed state, a medium speed state, or a high speed state. The power output from the auxiliary transmission mechanism 49 is transmitted to the rear wheels 5 via the rear wheel differential mechanism 50. Also, the power output from the auxiliary transmission mechanism 49 is transmitted to the front wheels 4 via the front wheel power take-off gear train 51, the clutch mechanism 52, the front wheel power transmission shaft 53, the front wheel differential mechanism 54, and the like.

[0043] As shown in FIG. 5, on the front side of the front wall 42 of the continuously variable transmission case 13, a transmission mechanism case 55 for housing the transmission mechanism 22 is attached. Therefore, the transmission case 14 is connected to the side of the continuously variable transmission case 13 opposite to the transmission mechanism case 55.

[0044] As shown in FIG. 6, on the front side of the front wall 42 of the continuously variable transmission case 13, an annular mounting seat portion 56 is formed to protrude forward. As shown in FIG. 7, the transmission mechanism case 55 has a case front wall 55a and an outer peripheral wall portion 55b extending rearward from the outer peripheral portion of the case front wall 55a. As shown in FIG. 8, the transmission mechanism case 55 is attached to the front wall 42 of the continuously variable transmission case 13 by overlapping the rear surface of the outer peripheral wall portion 55b with the front surface of the mounting seat portion 56 of the continuously variable transmission case 13 and fixing the outer peripheral wall portion 55b to the mounting seat portion 56 with bolts. As described above, the front wall 42 constitutes the front portion of the transmission device housing chamber 41. Therefore, the transmission mechanism case 55 is provided adjacent to the transmission device housing chamber 41.

[0045] As shown in FIG. 10, the input gear 25 is disposed at the upper part of the substantially central portion in the vehicle body width direction inside the transmission mechanism case 55. The first transmission gear 26 is disposed diagonally downward to the right of the input gear 25. The second transmission gear 27 is disposed diagonally downward to the left of the input gear 25. The second transmission gear 27 is disposed such that the upper end is at a position higher than the upper end of the first transmission gear 26.

[0046] As shown in FIGS. 8, 12, and 13, each gear constituting the transmission mechanism 22 is disposed across the inside of the transmission mechanism case 55 and the inside of the mounting seat portion 56. Accordingly, a transmission mechanism housing chamber for housing the transmission mechanism 22 is formed by the space inside the transmission mechanism case 55 and the space inside the mounting seat portion 56 (by the transmission mechanism case 55 and a partition wall 57 described later).

[0047] As shown in FIG. 7, a support hole 58, a first recess 59, and a second recess 60 are formed in the case front wall 55a. The support hole 58 is formed at a position corresponding to the input gear 25 (see FIG. 11). The first recess 59 is formed at a position corresponding to the first transmission gear 26 (see FIG. 12). The second recess 60 is formed at a position corresponding to the second transmission gear 27 (see FIG. 13). The first recess 59 and the second recess 60 are formed by being recessed forward from the rear surface of the case front wall 55a.

[0048] As shown in FIGS. 8 and 11, a shaft portion 28 integrally formed with the input gear 25 is inserted into the support hole 58. The support hole 58 has a first fitting hole portion 58a, a second fitting hole portion 58b, and a small-diameter hole portion 58c. The first fitting hole portion 58a, the second fitting hole portion 58b, and the small-diameter hole portion 58c are formed in order from the rear portion to the front portion of the transmission mechanism case 55. A bearing 61 for rotatably supporting the shaft portion 28 (input gear 25) is fitted into the first fitting hole portion 58a. An oil seal 62 for preventing the oil inside the transmission mechanism case 55 from leaking to the outside of the transmission mechanism case 55 through the bearing is fitted into the second fitting hole portion 58b. The small-diameter hole portion 58c is formed to have a smaller hole diameter than the second fitting hole portion 58b. Thereby, the oil seal 62 is prevented from coming off.

[0049] As shown in FIG. 12, a bearing 63 for rotatably supporting the first transmission gear 26 (first supported portion 26a) is fitted into the first recess 59. As shown in FIG. 13, a bearing 64 for rotatably supporting the second transmission gear 27 (first supported portion 27a) is fitted into the second recess 60.

[0050] As shown in FIGS. 6 and 8, the inner portion of the mounting seat portion 56 on the front wall 42 of the continuously variable transmission case 13 is a partition wall 57 which is a wall portion that partitions the transmission device accommodation chamber 41 and the inside of the transmission mechanism case 55. The partition wall 57 is configured to include a main wall portion 65 and a closing member 66. As shown in FIG. 6, the main wall portion 65 has an opening portion 67, a first insertion hole 68, and a second insertion hole 69. The opening portion 67, the first insertion hole 68, and the second insertion hole 69 are formed so as to penetrate the main wall portion 65.

[0051] As shown in FIG. 11, the opening portion 67 has a fitting hole portion 70 at the front portion and a stepped hole portion 71 at the rear portion. A bearing 72 for rotatably supporting the input gear 25 (supported portion 25a) is fitted into the fitting hole portion 70. The stepped hole portion 71 has a large-diameter portion formed at the front portion and a small-diameter portion formed smaller than the front portion at the rear portion. The closing member 66 is fitted into the stepped hole portion 71. The closing member 66 has a disk-shaped disk portion 66a fitted into the small-diameter portion 71a of the stepped hole portion 71 and an annular flange portion 66b fitted into the large-diameter portion 71b of the stepped hole portion 71. An O-ring 73 for preventing the oil in the transmission device accommodation chamber 41 from flowing into the inside of the transmission mechanism case 55 through between the disk portion 66a and the small-diameter portion 71a of the stepped hole portion 71 is fitted on the outer peripheral surface of the disk portion 66a.

[0052] As shown in FIG. 11, the closing member 66 has a through-hole 74 formed so as to penetrate in the front-rear direction K1. The through-hole 74 is formed at the center portion of the disk portion 66a. A plug 75 is inserted and fitted into the through-hole 74. The plug 75 is fitted into the rear portion of the through-hole.

[0053] As shown in FIG. 11, an orifice 76 is formed in the plug 75 so as to penetrate in the front-rear direction. The orifice 76 communicates the transmission device accommodation chamber 41 and the inside of the transmission mechanism case 55 with each other. Therefore, oil flows from the transmission device accommodation chamber 41 into the inside of the transmission mechanism case 55 through the orifice 76.

[0054] As shown in FIG. 11, the orifice 76 has a pore portion 76a communicating with the transmission housing chamber 41, a large-diameter hole portion 76b having a diameter larger than that of the pore portion 76a and communicating with the inside of the pore portion 76a and the transmission mechanism case 55, and a diameter-expanding hole portion 76c that is a hole connecting the pore portion 76a and the large-diameter hole portion 76b and whose diameter gradually increases from the pore portion 76a toward the large-diameter hole portion 76b.

[0055] The transmission housing chamber 41 is filled with oil and oil is supplied from the supply pump 87, so the oil in the transmission housing chamber 41 is under pressure. The oil passing through the orifice 76 flows into the transmission mechanism case 55 through the pore portion 76a, the diameter-expanding hole portion 76c, and the large-diameter hole portion 76b, so the flow rate of the oil flowing out from the orifice 76 can be moderated.

[0056] As shown in FIG. 11, the orifice 76 is provided at the height position of the rotation center of the input gear 25. An oil passage 77 penetrating in the front-rear direction K1 is formed at the rotation center portion of the input gear 25 and the shaft portion 28 to supply oil to the front side of the shaft portion 28. Therefore, the orifice 76 is provided at a position corresponding to the oil passage 77.

[0057] As shown in FIG. 12, the first insertion hole 68 has a first fitting hole portion 68a, a second fitting hole portion 68b, and a third fitting hole portion 68c. The first fitting hole portion 68a is formed at the front portion of the first insertion hole 68. The second fitting hole portion 68b is formed at the middle portion of the first insertion hole 68. The second fitting hole portion 68b is formed to have a smaller diameter than the first fitting hole portion 68a. The third fitting hole portion 68c is formed at the rear portion of the first insertion hole 68. The third fitting hole portion 68c is formed to have a smaller diameter than the first fitting hole portion 68a and a larger diameter than the second fitting hole portion 68b.

[0058] In the first fitting hole portion 68a, a bearing 78 that rotatably supports the first transmission gear 26 (second supported portion 26b) is fitted. In the second fitting hole portion 68b, an oil seal 79 is fitted. In the third fitting hole portion 68c, a bearing 80 that rotatably supports the first transmission shaft 29 is fitted. The oil seal 79 stops the oil from flowing from the bearing 80 side (transmission gear housing chamber 41 side) to the transmission mechanism case 55 side.

[0059] As shown in FIG. 13, the second insertion hole 69 has a first fitting hole portion 69a, a second fitting hole portion 69b, and a third fitting hole portion 69c. The first fitting hole portion 69a is formed at the front portion of the second insertion hole 69. The second fitting hole portion 69b is formed at the middle portion of the second insertion hole 69. The second fitting hole portion 69b is formed to have a smaller diameter than the first fitting hole portion 69a. The third fitting hole portion 69c is formed at the rear portion of the second insertion hole 69. The third fitting hole portion 69c is formed to have a smaller diameter than the first fitting hole portion 69a and a larger diameter than the second fitting hole portion 69b.

[0060] In the first fitting hole portion 69a, a bearing 81 that rotatably supports the second transmission gear 27 (second supported portion 27b) is fitted. In the second fitting hole portion 69b, an oil seal 82 is fitted. In the third fitting hole portion 69c, a bearing 83 that rotatably supports the second transmission shaft 30 is fitted. The oil seal 82 stops the oil from flowing from the bearing 83 side (transmission gear housing chamber 41 side) to the transmission mechanism case 55 side.

[0061] In the present embodiment, the transmission gear housing chamber 41 and the inside of the transmission mechanism case 55 are partitioned by a partition wall 57, an opening 67 formed in the main wall portion 65 of the partition wall 57 is closed by a closing member 66, an O-ring 73 is provided on the outer peripheral surface of the disk portion 66a of the closing member 66, and the O-ring 73, the oil seal 79, and the oil seal 82 are used to stop the oil from flowing from the transmission gear housing chamber 41 side to the transmission mechanism case 55 side, whereby the inside of the transmission mechanism case 55 can be made into a separate chamber from the transmission gear housing chamber 41. Also, the transmission gear housing chamber 41 and the inside of the transmission mechanism case 55 can be partitioned so that the oil in the transmission gear housing chamber 41 does not flow into the inside of the transmission mechanism case 55 except at the orifice 76.

[0062] For example, when the inside of the transmission case 55 is in a state where there is oil flow in the transmission gear housing 41 and is filled with oil, the stirring resistance of the gears inside the transmission case 55 is large. When the stirring resistance of the gears inside the transmission case 55 is large, a horsepower loss occurs due to the large stirring resistance of the gears.

[0063] In contrast, in the present embodiment, by making the inside of the transmission case 55 a separate chamber from the transmission gear housing 41, as shown in FIG. 10, the oil level 84 of the oil inside the transmission case 55 can be lowered so as to be located in the middle part in the vertical direction. Thereby, the stirring resistance of the gears inside the transmission case 55 can be reduced. Consequently, the horsepower loss can be reduced. As shown in FIGS. 14 and 15, an outflow passage 85 for allowing the oil inside the transmission case 55 to flow out is formed in the continuously variable transmission case 13. The outflow passage 85 is configured to allow the oil inside the transmission case 55 to flow out into the inside of the transmission case 14. Specifically, the outflow passage 85 has a first oil passage 85a extending in the vertical direction and a second oil passage 85b extending rearward from the middle part of the first oil passage 85a. The upper end of the first oil passage 85a opens inside the mounting seat portion 56. Therefore, the first oil passage 85a (outflow passage 85) communicates with the inside of the transmission case 55.

[0064] As shown in FIGS. 14 and 15, an outflow passage 85 for allowing the oil inside the transmission case 55 to flow out is formed in the continuously variable transmission case 13. The outflow passage 85 is configured to allow the oil inside the transmission case 55 to flow out into the inside of the transmission case 14. Specifically, the outflow passage 85 has a first oil passage 85a extending in the vertical direction and a second oil passage 85b extending rearward from the middle part of the first oil passage 85a. The upper end of the first oil passage 85a opens inside the mounting seat portion 56. Therefore, the first oil passage 85a (outflow passage 85) communicates with the inside of the transmission case 55.

[0065] As shown in FIG. 15, the upper end opening of the first oil passage 85a is at substantially the same height position as the height position of the bottom of the transmission case 55. Therefore, the outflow passage 85 is configured to allow the oil inside the transmission case 55 to flow out from the bottom side.

[0066] As shown in FIG. 15, the second oil passage 85b communicates the first oil passage 85a with a cavity 86 formed in the continuously variable transmission case 13. The cavity 86 is formed below a bottom wall 44 that constitutes the bottom of the transmission device housing chamber 41 in the continuously variable transmission case 13. The cavity 86 is open to the rear and communicates with the inside of the transmission case 14.

[0067] Therefore, the oil inside the transmission mechanism case 55 flows through the outflow passage 85 and the cavity 86 from the bottom side of the transmission mechanism case 55 and into the inside of the transmission case 14. Since the inside of the transmission mechanism case 55 communicates with the inside of the transmission case 14, the height of the oil level 84 of the oil inside the transmission mechanism case 55 becomes substantially the same as the height of the oil level inside the transmission case 14. That is, the outflow passage 85 and the cavity 86 form a communication passage that communicates the inside of the transmission mechanism case 55 with the inside of the transmission case 14, whereby the height of the oil level 84 of the oil inside the transmission mechanism case 55 can be set to the height at the middle part in the vertical direction of the transmission mechanism case 55.

[0068] And the orifice 76 is set with the oil flow rate (hole diameter) such that the oil fills the transmission device housing chamber 41 and the oil level 84 of the oil inside the transmission mechanism case 55 is located at the middle part in the vertical direction inside the transmission mechanism case 55.

[0069] Since the purified oil discharged from the supply pump 87 is supplied to the transmission device housing chamber 41, the cleanliness of the oil inside the transmission device housing chamber 41 can be improved. Further, by supplying the oil that has been discharged from the supply pump 87 and passed through the oil filter 38 to the transmission device housing chamber 41, the cleanliness of the oil inside the transmission device housing chamber 41 can be further improved.

[0070] Also, by flowing the oil inside the transmission mechanism case 55 (transmission mechanism housing chamber) from the bottom side of the transmission mechanism case 55 to the transmission case 14 and flowing the oil in the transmission device housing chamber 41 from the orifice 76 into the transmission mechanism case 55, the purification of the oil inside the transmission mechanism case 55 can be achieved.

[0071] The structure for providing the above-described orifice 76 is not limited to the structure of this embodiment. For example, the orifice 76 may not be formed in the plug 75 and may be directly formed in the wall portion that partitions the transmission device accommodation chamber 41 and the inside of the transmission mechanism case 55.

[0072] Also, in the above embodiment, the orifice 76 is provided at the height position of the rotation center of the input gear 25, but the position where the orifice 76 is provided is not limited. For example, the orifice 76 may be provided above the height of the oil level 84 of the oil inside the transmission mechanism case 55. Further, the orifice 76 may be provided at a height position within the range of the cutting edge diameter D1 (see FIG. 10) of the input gear 25.

[0073] Also, the opening 67 only needs to have the fitting hole 70, and the stepped hole 71 does not have to be formed. That is, the rear part of the opening 67 may be closed. In this case, the closing member 66 is not provided.

[0074] A preferred embodiment of the present invention provides the work vehicle 1 described in the following items. (Item 1) A transmission device accommodation chamber 41 that houses a hydraulic pump 18 and a hydraulic motor 19 driven by the oil discharged from the hydraulic pump 18, an input gear 25 that is provided adjacent to the transmission device accommodation chamber 41 and to which power from the prime mover 8 is input, and a transmission mechanism 22 that includes a transmission gear 26 that transmits the power transmitted from the input gear 25 to the hydraulic pump 18, and a transmission mechanism case 55 that houses the transmission mechanism 22, and the inside of the transmission mechanism case 55 is a separate chamber from the transmission device accommodation chamber 41.

[0075] According to the work vehicle 1 according to this Item 1, by making the inside of the transmission mechanism case 55 adjacent to the transmission device accommodation chamber 41 a separate chamber from the transmission device accommodation chamber 41, the height of the oil level 84 inside the transmission mechanism case 55 can be lowered. Thereby, the stirring resistance of the gears inside the transmission mechanism case 55 can be reduced. Consequently, the horsepower loss can be reduced. (Item 2) It is provided with an orifice 76 that communicates the inside of the transmission housing chamber 41 and the inside of the transmission mechanism case 55, and in parts other than the orifice 76, the transmission housing chamber 41 and the inside of the transmission mechanism case 55 are partitioned so that oil in the transmission housing chamber 41 does not flow into the inside of the transmission mechanism case 55. The work vehicle 1 according to Item 1.

[0076] Also by the work vehicle 1 according to this item, the height of the oil level 84 inside the transmission mechanism case 55 can be lowered, and the stirring resistance of the gears inside the transmission mechanism case 55 can be reduced. (Item 3) It is provided with a supply pump 87 capable of replenishing purified oil into the transmission housing chamber 41 and an outflow passage 85 for discharging oil inside the transmission mechanism case 55. The orifice 76 is set with the oil flow rate so that the transmission housing chamber 41 is full of oil and the oil level of the oil inside the transmission mechanism case 55 is located at the middle part in the vertical direction inside the transmission mechanism case 55. The work vehicle 1 according to Item 2.

[0077] According to the work vehicle 1 according to this Item 3, the cleanliness of the oil in the transmission housing chamber 41 and the transmission mechanism case 55 can be improved. Also, even if the transmission housing chamber 41 and the inside of the transmission mechanism case 55 are communicated by the orifice 76, the height of the oil level inside the transmission mechanism case 55 can be maintained at the height position of the middle part in the vertical direction. (Item 4) It is provided with a continuously variable transmission case 13 that forms the transmission housing chamber 41 and a mission case 14 that is connected to the side of the continuously variable transmission case 13 opposite to the transmission mechanism case 55 and houses a traveling system transmission mechanism 20 that shifts the power output from the hydraulic motor 19 and transmits it to the drive wheels. The supply pump 87 replenishes the oil inside the mission case 14 sucked through the oil filter 37 into the transmission housing chamber 41, and the outflow passage 85 is configured to discharge the oil inside the transmission mechanism case 55 into the inside of the mission case 14. The work vehicle 1 according to Item 3.

[0078] According to the work vehicle 1 related to this item 4, by purifying and circulating the oil in the transmission case 14, the cleanliness of the oil in the transmission housing 41 and the transmission mechanism case 55 can be maintained. (Item 5) The input gear 25 is disposed above the transmission gear 26 at the upper part inside the transmission mechanism case 55, and the orifice 76 is provided at a height within the range of the cutting edge diameter D1 of the input gear 25. The work vehicle 1 according to any one of Items 2 to 4.

[0079] According to the work vehicle 1 related to this item 5, since the oil flowing out from the orifice 76 flows out of the transmission mechanism case 55 from the upper part of the transmission mechanism case 55, the oil can be preferably supplied into the transmission mechanism case 55 in which the height of the oil level 84 is set midway in the vertical direction. (Item 6) The work vehicle 1 according to any one of Items 2 to 5 includes a plug 75 that closes a through hole 74 formed through a wall portion (partition wall 57) that partitions the inside of the transmission housing 41 and the inside of the transmission mechanism case 55, and the orifice 76 is formed in the plug 75.

[0080] According to the work vehicle 1 related to this item 6, when the hole diameter of the orifice 76 is not appropriate, it can be dealt with by replacing the plug 75, and the setting of the oil flow rate of the orifice 76 can be easily performed. (Item 7) The work vehicle 1 according to any one of Items 2 to 6 includes a small hole portion 76a communicating with the transmission housing 41, and a large hole portion 76b having a diameter larger than that of the small hole portion 76a and communicating with the inside of the small hole portion 76a and the transmission mechanism case 55.

[0081] According to the work vehicle 1 related to this item, the flow velocity of the oil flowing out from the small hole portion 76a can be alleviated. (Item 8) The orifice 76 according to item 7 of the work vehicle 1 described above is a hole connecting the pore portion 76a and the large hole portion 76b, and has a diameter increasing hole portion 76c that gradually increases in diameter from the pore portion 76a toward the large hole portion 76b.

[0082] Also with the work vehicle 1 according to this item, the flow rate of the oil flowing out from the pore portion 76a can be alleviated.

[0083] As described above, although one embodiment of the present invention has been described, it should be considered that the embodiments disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and it is intended that all modifications within the meaning and scope equivalent to the claims are included.

Explanation of Signs

[0084] 1 Work vehicle 8 Prime mover 13 Continuously variable transmission case 14 Transmission case 18 Hydraulic pump 19 Hydraulic motor 20 Traveling system transmission mechanism 22 Transmission mechanism 25 Input gear 26 Transmission gear 37 Oil filter 41 Transmission device housing chamber 55 Transmission mechanism case 57 Wall portion (partition wall) 74 Through hole 75 Plug 76 Orifice 76a Pore portion 76b Large hole portion 76c Diameter increasing hole portion 85 Outflow path 87 Supply pump D1 Cutting edge diameter

Claims

1. A hydraulic pump and a transmission housing chamber that houses a hydraulic motor driven by oil discharged from the hydraulic pump, A transmission mechanism case that houses a transmission mechanism including an input gear provided adjacent to the transmission housing chamber and receiving power from a prime mover, and a transmission gear that transmits the power transmitted from the input gear to the hydraulic pump. A work vehicle in which the inside of the transmission mechanism case is a separate chamber from the transmission housing chamber.

2. An orifice that communicates the transmission housing chamber and the inside of the transmission mechanism case, The work vehicle according to claim 1, wherein the transmission housing chamber and the inside of the transmission mechanism case are partitioned so that oil in the transmission housing chamber does not flow into the inside of the transmission mechanism case except at the orifice.

3. A supply pump capable of supplying purified oil into the transmission housing chamber, An outflow passage for discharging oil inside the transmission mechanism case, Comprising, The work vehicle according to claim 2, wherein the orifice is set with an oil flow rate such that the transmission housing chamber is full of oil and the oil level of the oil inside the transmission mechanism case is located at a middle portion in the vertical direction inside the transmission mechanism case.

4. A continuously variable transmission case forming the transmission housing chamber, A mission case that is connected to the opposite side of the continuously variable transmission case from the transmission mechanism case and houses a traveling system transmission mechanism that shifts the power output from the hydraulic motor and transmits it to drive wheels. Comprising, The supply pump supplies the oil inside the mission case sucked through an oil filter into the transmission housing chamber, The work vehicle according to claim 3, wherein the outflow passage is configured to discharge the oil inside the transmission mechanism case into the inside of the mission case.

5. The input gear is disposed at an upper portion inside the transmission mechanism case and above the transmission gear, The work vehicle according to any one of claims 2 to 4, wherein the orifice is provided at a height within the range of the cutting edge diameter of the input gear.

6. A plug that closes a through hole formed through a wall portion partitioning the transmission housing chamber and the inside of the transmission mechanism case, The work vehicle according to any one of claims 2 to 4, wherein the orifice is formed in the plug.

7. The orifice is A pore portion communicating with the transmission housing chamber, A large-diameter hole portion that is larger in diameter than the pore portion and communicates with the inside of the pore portion and the transmission mechanism case, The work vehicle according to any one of claims 2 to 4, which has the above.

8. The work vehicle according to claim 7, wherein the orifice is a hole connecting the pore portion and the large-diameter hole portion and has an enlarged-diameter hole portion whose diameter gradually increases from the pore portion toward the large-diameter hole portion.

Images