Work vehicle

Abstract

To suppress malfunction of a hydraulic operation part when supplying hydraulic oil to the hydraulic operation part via a supply oil path formed inside a rotationally-driven transmission shaft.SOLUTION: A transmission shaft 38 is provided with shaft groove parts 71 to 74, inlet ports 75 to 78, and supply oil paths 81 to 84. A shaft support part 30 is provided with: external flow paths 85 to 88 that are formed in a ring shape so as to surround the shaft groove parts 71 to 74; first supply ports 30a to 30d that are provided so as to be connected to external flow paths 85 to 88, and to which hydraulic oil is supplied; and second supply ports 55 to 58 that are provided across the external flow paths 85 to 88 and inner peripheral parts 30e, 44a of the shaft support part 30, and communicate with the shaft groove parts 71 to 74.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a configuration in a work vehicle in which hydraulic oil is supplied to a hydraulic operating unit such as a hydraulic clutch through a supply oil passage formed inside a transmission shaft that is rotationally driven.

Background Art

[0002] In a configuration in which hydraulic oil from a hydraulic pump or a control valve is supplied to a hydraulic operating unit through a supply oil passage inside a transmission shaft, the configuration of a portion where the hydraulic oil from the hydraulic pump or the control valve is supplied to the supply oil passage inside the transmission shaft is disclosed in Patent Document 1.

[0003] In Patent Document 1, a supply port to which hydraulic oil is supplied is provided in a shaft support portion that rotatably supports the transmission shaft. In the transmission shaft, a shaft groove portion is formed along the circumferential direction on the outer peripheral portion of the transmission shaft, and an inlet port is formed inside the transmission shaft across the shaft groove portion and the supply oil passage. Thereby, the hydraulic oil is supplied from the supply port of the shaft support portion to the shaft groove portion of the transmission shaft, and in the transmission shaft, it is supplied from the shaft groove portion to the supply oil passage through the inlet port. Since the supply port of the shaft support portion and the shaft groove portion of the transmission shaft communicate with each other, even when the transmission shaft is rotationally driven, the hydraulic oil is supplied from the supply port of the shaft support portion to the supply oil passage of the transmission shaft.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In Patent Document 1, when the transmission shaft is rotationally driven, the inlet port of the transmission shaft is rotationally driven with respect to the supply port of the shaft support portion. Therefore, the inlet port of the transmission shaft and the supply port of the shaft support portion are repeatedly in a state of facing each other at the same position and a state of being separated from the supply port of the shaft support portion.

[0006] Focusing on the pressure loss of the hydraulic oil when the hydraulic oil enters the inlet port of the transmission shaft from the supply port of the shaft support portion, the pressure loss of the hydraulic oil tends to be relatively large at a position slightly advanced from the position where the inlet port of the transmission shaft faces the supply port of the shaft support portion at the same position. In the state where the inlet port of the transmission shaft is farthest from the supply port of the shaft support portion, the pressure loss of the hydraulic oil tends to be relatively small.

[0007] As a result, when the transmission shaft is rotationally driven, a state where the pressure of the hydraulic oil is high (a state where the pressure loss is small) and a state where the pressure of the hydraulic oil is low (a state where the pressure loss is large) are repeated. There is a concern that pulsation may occur in the pressure of the hydraulic oil, leading to malfunction of the hydraulic actuating portion to which the hydraulic oil is supplied.

[0008] An object of the present invention is to suppress malfunction of a hydraulic actuating portion when supplying hydraulic oil to the hydraulic actuating portion via a supply oil passage formed inside a transmission shaft that is rotationally driven in a work vehicle.

Means for Solving the Problem

[0009] The work vehicle of the present invention includes a transmission shaft that is rotationally driven, a shaft support portion that rotatably supports the transmission shaft, and a hydraulic actuator that operates when hydraulic oil is supplied. The transmission shaft is provided with a shaft groove portion formed along the circumferential direction of the transmission shaft and extending over the entire circumference of the outer peripheral portion of the transmission shaft, an inlet port formed inside the transmission shaft along the radial direction of the transmission shaft and connected to the shaft groove portion, and a supply oil passage formed inside the transmission shaft along the longitudinal direction of the transmission shaft and connected to the inlet port inside the transmission shaft. The shaft support portion is provided with an external flow path formed in a ring shape so as to surround the shaft groove portion, a first supply port provided so as to be connected to the external flow path and to which hydraulic oil is supplied, and a second supply port provided across the external flow path and the inner peripheral portion of the shaft support portion and communicating with the shaft groove portion. The hydraulic oil supplied to the first supply port is supplied to the hydraulic actuator through the external flow path, the second supply port, the shaft groove portion, the inlet port, and the supply oil passage from the first supply port.

[0010] According to the present invention, when hydraulic oil is supplied to the first supply port of the shaft support portion, the hydraulic oil enters the external flow path from the first supply port of the shaft support portion, and enters the shaft groove portion of the transmission shaft through the second supply port from the external flow path. The hydraulic oil that has entered the shaft groove portion of the transmission shaft is supplied to the hydraulic actuator through the inlet port and the supply oil passage from the shaft groove portion.

[0011] According to the present invention, in the flow of hydraulic oil, an external oil passage of the shaft support portion exists between the first supply port of the shaft support portion and the shaft groove portion of the transmission shaft. Since the external flow path of the shaft support portion is formed in a ring shape so as to surround the shaft groove portion of the transmission shaft, the circumferential length is relatively long and it has a relatively large volume. Thus, it is considered that the external oil passage of the shaft support portion functions to suppress the pressure loss of the hydraulic oil and alleviate the rapid change in the pressure of the hydraulic oil.

[0012] Therefore, in a state where the high pressure state (low pressure loss state) and the low pressure state (high pressure loss state) of the hydraulic oil are repeated, when the hydraulic oil transitions from the low pressure state (high pressure loss state) to the high pressure state (low pressure loss state), the rapid increase in the pressure of the hydraulic oil is alleviated by the external oil passage, and the high pressure state (low pressure loss state) of the hydraulic oil is suppressed. Similarly, when the hydraulic oil transitions from the high pressure state (low pressure loss state) to the low pressure state (high pressure loss state), the rapid decrease in the pressure of the hydraulic oil is alleviated by the external oil passage, and the low pressure state (high pressure loss state) of the hydraulic oil is suppressed.

[0013] According to the present invention, since the high pressure state (low pressure loss state) and the low pressure state (high pressure loss state) of the hydraulic oil are suppressed, the difference between the high pressure state (low pressure loss state) and the low pressure state (high pressure loss state) of the hydraulic oil can be reduced, so that the pulsation of the pressure of the hydraulic oil can be suppressed, and the malfunction of the hydraulic actuator can be suppressed.

[0014] In the present invention, it is preferable that the plurality of second supply ports are provided at intervals along the circumferential direction of the inner peripheral portion of the shaft support portion.

[0015] According to the present invention, since a plurality of second supply ports are provided in the shaft support portion, a state where the inlet port of the transmission shaft and the second supply port of the shaft support portion face each other at the same position occurs a plurality of times during one rotation of the transmission shaft.

[0016] Thereby, when the inlet port of the transmission shaft passes through one second supply port of the shaft support portion and the pressure of the hydraulic oil transitions from the high pressure state (low pressure loss state) to the low pressure state (high pressure loss state), before the pressure of the hydraulic oil drops too much, the inlet port of the transmission shaft faces the next second supply port of the shaft support portion, and the pressure of the hydraulic oil becomes the high pressure state (low pressure loss state).

[0017] According to the present invention, since the decrease in pressure from a state where the pressure of the hydraulic oil is high (a state where the pressure loss is small) is suppressed, the difference between the state where the pressure of the hydraulic oil is high (a state where the pressure loss is small) and the state where it is low (a state where the pressure loss is large) can be reduced. Therefore, it is advantageous in terms of suppressing the pulsation of the pressure of the hydraulic oil and in terms of suppressing malfunction of the hydraulic actuating part.

[0018] In the present invention, it is preferable that the first supply port and the second supply port are provided at different positions in the circumferential direction of the inner peripheral portion of the shaft support portion.

[0019] According to the present invention, since the first supply port and the second supply port of the shaft support portion are provided at different positions, it is possible to prevent a state in which, after the hydraulic oil enters the external oil passage from the first supply port of the shaft support portion, the hydraulic oil immediately enters the second supply port from the external oil passage.

[0020] Thereby, it is possible to easily retain the hydraulic oil that has entered the external oil passage from the first supply port of the shaft support portion, and it becomes easier to exhibit the function of alleviating a rapid change in the pressure of the hydraulic oil in the external oil passage. Therefore, it is advantageous in terms of suppressing the pulsation of the pressure of the hydraulic oil and in terms of suppressing malfunction of the hydraulic actuating part.

[0021] In the present invention, it is preferable that the cross-sectional area of the external flow path in a plane orthogonal to the circumferential direction of the inner peripheral portion of the shaft support portion is formed to be larger than the cross-sectional area of the shaft groove portion of the transmission shaft in a plane orthogonal to the circumferential direction.

[0022] According to the present invention, the cross-sectional area of the external oil passage of the shaft support portion is set to be larger than the cross-sectional area of the shaft groove portion of the transmission shaft, and the volume of the external flow path of the shaft support portion is large. Thereby, it becomes easier to exhibit the function of alleviating a rapid change in the pressure of the hydraulic oil in the external oil passage of the shaft support portion. Therefore, it is advantageous in terms of suppressing the pulsation of the pressure of the hydraulic oil and in terms of suppressing malfunction of the hydraulic actuating part.

[0023] In the present invention, a cylindrical member is provided which is attached to the inner peripheral portion of the shaft support portion and rotatably supports the transmission shaft, so that the transmission shaft is rotatably supported by the shaft support portion. An external groove portion is formed in the cylindrical member along the circumferential direction of the inner peripheral portion of the shaft support portion over the entire circumference of the outer peripheral portion of the cylindrical member, and the external groove portion and the inner peripheral portion of the shaft support portion form the external flow path. It is preferable that a second supply port communicating with the shaft groove portion is provided across the external groove portion and the inner peripheral portion of the cylindrical member.

[0024] According to the present invention, a first supply port is provided in the shaft support portion, a cylindrical member which is a separate member from the shaft support portion is provided, and an external groove portion and a second supply port are provided in the cylindrical member. By attaching the cylindrical member to the inner peripheral portion of the shaft support portion, an external flow path of the shaft support portion is formed by the inner peripheral portion of the shaft support portion and the external groove portion of the cylindrical member, and the second supply port is provided in the shaft support portion. Since the external groove portion and the second supply port can be relatively easily provided in the cylindrical member, the first supply port, the second supply port, and the external oil passage can be relatively easily provided in the shaft support portion, and the production cost can be reduced.

Brief Description of the Drawings

[0025]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0026] In FIGS. 1 to 9, a tractor which is an example of a working vehicle is shown. In FIG. 1, F indicates the forward direction, B indicates the backward direction, U indicates the upward direction, and D indicates the downward direction.

[0027] (Overall Configuration of Tractor) As shown in FIG. 1, the body 5 is supported by the right and left front wheels 6 and the right and left rear wheels 7, a bonnet 8 is provided at the front part of the body 5, and a driver's cab 9 is provided at the rear part of the body 5.

[0028] The body 5 has an engine 1, a flywheel housing 2 connected to the rear part of the engine 1, a transmission case 3 connected to the rear part of the flywheel housing 2, a front frame 4 connected to the front part of the engine 1, etc.

[0029] The front wheels 6 are supported by the front frame 4, the rear wheels 7 are supported by the rear part of the transmission case 3, and the engine 1 is covered by the bonnet 8. The driver's cab 9 is covered by a cabin 12, and a driver's seat 10 and a steering wheel 11 for steering the front wheels 6 are provided in the driver's cab 9.

[0030] A link mechanism 13 capable of connecting various working devices (not shown) is provided at the rear part of the body 5, and a PTO shaft 14 for transmitting power to the working device is provided at the rear part of the transmission case 3.

[0031] (Outline of the Inside of the Transmission Case) As shown in FIG. 2, the transmission case 3 is provided with a first planetary device 50, a second planetary device 60, a continuously variable transmission 18, a transmission device 19, a forward and reverse switching device 20, a rear wheel differential device 22, a front wheel transmission device 26, a PTO clutch 15, a PTO transmission device 21, etc.

[0032] The power of the output shaft 1a of the engine 1 is transmitted to the input shaft 17 of the transmission case 3 via the clutch 16, and is transmitted from the input shaft 17 to the transmission shafts 31 and 32. The power of the transmission shaft 32 is transmitted to the PTO clutch 15, is shifted by the PTO transmission 21, and is transmitted to the PTO shaft 14.

[0033] The power of the output shaft 1a of the engine 1 is transmitted to and shifted by the first planetary gear device 50, the second planetary gear device 60, the continuously variable transmission 18, and the transmission device 19 via the clutch 16, and is transmitted to the output shaft 38 (corresponding to the transmission shaft).

[0034] The power of the output shaft 38 is transmitted from the transmission shaft 40 to the forward / reverse switching device 20, is transmitted from the cylindrical transmission shaft 42 rotatably attached to the transmission shaft 32 to the transmission shaft 23, is transmitted to the rear wheel differential device 22, and is transmitted to the right and left rear wheels 7.

[0035] The power of the transmission shaft 23 is transmitted to the transmission shaft 24 and is transmitted to the front wheel transmission 26 via the transmission shaft 43. The power of the front wheel transmission 26 is transmitted from the front wheel output shaft 45 to the front wheel differential device 28 via the transmission shaft 27, and is transmitted to the right and left front wheels 6.

[0036] (Configuration of the first planetary gear device, the second planetary gear device, and the continuously variable transmission) As shown in FIG. 2, the first planetary gear device 50 and the second planetary gear device 60 have sun gears 51, 61, 18a, a plurality of planetary gears 52, 62, ring gears 53, 63, and a common carrier 54. The planetary gear 52 of the first planetary gear device 50 and the planetary gear 62 of the second planetary gear device 60 are connected to each other by a cylindrical transmission shaft 64 attached to the carrier 54, and the first planetary gear device 50 and the second planetary gear device 60 are configured as a compound planetary gear device.

[0037] The power of the input shaft 17 is transmitted to the ring gear 53 of the first planetary gear device 50 via the transmission shaft 34. The power of the input shaft 17 is transmitted from the transmission gear 29 that connects the transmission shafts 31 and 32 to the continuously variable transmission 18 via the transmission shaft 35. The continuously variable transmission 18 is configured hydraulically and outputs forward and reverse power. The forward and reverse power of the continuously variable transmission 18 is transmitted to the sun gear 51 of the first planetary gear set 50 via the transmission shaft 36.

[0038] The power transmitted from the engine 1 to the sun gear 51 of the first planetary gear set 50 via the continuously variable transmission 18 and the power transmitted from the engine 1 directly to the ring gear 53 of the first planetary gear set 50 without passing through the continuously variable transmission 18 are combined by the first planetary gear set 50 and the second planetary gear set 60.

[0039] The power combined by the first planetary gear set 50 and the second planetary gear set 60 is transmitted from the ring gear 63 of the second planetary gear set 60 to the output shaft 37, from the carrier 54 to the output shaft 39, and from the sun gear 61 of the second planetary gear set 60 to the output shaft 41.

[0040] (Configuration of Transmission) As shown in FIG. 2, the transmission 19 includes a first clutch CL1 (corresponding to a hydraulic actuator), a second clutch CL2 (corresponding to a hydraulic actuator), a third clutch CL3 (corresponding to a hydraulic actuator), a fourth clutch CL4 (corresponding to a hydraulic actuator), and an output shaft 38, etc.

[0041] The power of the output shaft 37 is transmitted to the first clutch CL1, the power of the output shaft 39 is transmitted to the third clutch CL3, and the power of the output shaft 41 is transmitted to the second clutch CL2 and the fourth clutch CL4.

[0042] The first clutch CL1 to the fourth clutch CL4 are configured as hydraulic multi-plate clutches and are biased to the disengaged state, and are operated to the engaged state by the supply of hydraulic oil. When the first clutch CL1 to the fourth clutch CL4 are operated to the engaged state, the power of the first clutch CL1 to the fourth clutch CL4 is transmitted to the output shaft 38.

[0043] (Shift States by Continuously Variable Transmission and Transmission) Fig. 3 shows the relationship between the continuously variable transmission 18 and the first to fourth clutches CL1 to CL4, and shows the rotational speed V of the output shaft 38, the neutral position N of the continuously variable transmission 18, the maximum speed “+MAX” of the forward driving force of the continuously variable transmission 18, and the maximum speed “-MAX” of the reverse driving force of the continuously variable transmission 18.

[0044] As shown in Fig. 2, when the first clutch CL1 is operated in the transmission state, the power synthesized by the first planetary gear device 50 and the second planetary gear device 60 is transmitted to the output shaft 38 via the ring gear 63 of the second planetary gear device 60, the output shaft 37, and the first clutch CL1. In this state, as shown in the first gear range of Fig. 3, when the continuously variable transmission 18 is operated over the maximum speed “-MAX” of the reverse driving force and the maximum speed “+MAX” of the forward driving force, the rotational speed V of the output shaft 38 is continuously variable between the zero speed and the speed V1.

[0045] As shown in Fig. 2, when the second clutch CL2 is operated in the transmission state, the power synthesized by the first planetary gear device 50 and the second planetary gear device 60 is transmitted to the output shaft 38 via the sun gear 61 of the second planetary gear device 60, the output shaft 41, and the second clutch CL2. In this state, as shown in the second gear range of Fig. 3, when the continuously variable transmission 18 is operated over the maximum speed “-MAX” of the reverse driving force and the maximum speed “+MAX” of the forward driving force, the rotational speed V of the output shaft 38 is continuously variable between the speed V1 and the speed V2.

[0046] As shown in Fig. 2, when the third clutch CL3 is operated in the transmission state, the power synthesized by the first planetary gear device 50 and the second planetary gear device 60 is transmitted to the output shaft 38 via the carrier 54, the output shaft 39, and the third clutch CL3. In this state, as shown in the third gear range of Fig. 3, when the continuously variable transmission 18 is operated over the maximum speed “-MAX” of the reverse driving force and the maximum speed “+MAX” of the forward driving force, the rotational speed V of the output shaft 38 is continuously variable between the speed V2 and the speed V3.

[0047] As shown in FIG. 2, when the fourth clutch CL4 is operated to be in the transmission state, the power synthesized by the first planetary gear device 50 and the second planetary gear device 60 is transmitted to the output shaft 38 via the sun gear 61 of the second planetary gear device 60, the output shaft 41, and the fourth clutch CL4. In this state, as shown in the 4th speed range of FIG. 3, when the continuously variable transmission 18 is operated over the maximum reverse speed “-MAX” and the maximum forward speed “+MAX” of the reverse power, the rotational speed V of the output shaft 38 is steplessly shifted between the speed V3 and the speed V4.

[0048] (Configuration of the forward and reverse switching device) As shown in FIG. 2, the forward and reverse switching device 20 includes a forward clutch CLF, a reverse clutch CLR, transmission shafts 40 and 42, an intermediate gear 46, etc., and the power of the output shaft 38 is transmitted to the transmission shaft 40.

[0049] In the forward and reverse switching device 20, when the forward clutch CLF is operated to be in the transmission state, the power of the transmission shaft 40 is transmitted to the transmission shaft 42 in the forward state via the forward clutch CLF, and is transmitted from the transmission shaft 42 to the rear wheel differential device 22 via the transmission shaft 23.

[0050] In the forward and reverse switching device 20, when the reverse clutch CLR is operated to be in the transmission state, the power of the transmission shaft 40 is transmitted to the transmission shaft 42 in the reverse state via the reverse clutch CLR and the intermediate gear 46, and is transmitted from the transmission shaft 42 to the rear wheel differential device 22 via the transmission shaft 23.

[0051] (Configuration of the front wheel transmission device) As shown in FIG. 2, the front wheel transmission device 26 includes a standard clutch CLT, a speed increasing clutch CLH, a transmission shaft 43, a front wheel output shaft 45, etc.

[0052] When the front wheels 6 are operated within the range of the set angles to the right and left from the straight-ahead position, in the front wheel transmission device 26, the standard clutch CLT is operated to be in the transmission state. The power of the transmission shaft 23 is transmitted to the front wheel output shaft 45 via the transmission shafts 24, 43 and the standard clutch CLT, and is transmitted to the front wheels 6 via the transmission shaft 27 and the front wheel differential device 28, so that the front wheels 6 and the rear wheels 7 are driven at the same speed.

[0053] When the front wheels 6 are steered right or left beyond the right and left set angles, in the front wheel transmission 26, the speed increasing clutch CLH is operated in the engaged state. The power of the transmission shaft 23 is transmitted to the front wheel output shaft 45 via the transmission shafts 24, 43 and the speed increasing clutch CLH, and is transmitted to the front wheels 6 via the transmission shaft 27 and the front wheel differential device 28, so that the front wheels 6 are driven at a higher speed than the rear wheels 7.

[0054] (Configuration of the shaft support portion for supporting the output shaft) As shown in FIGS. 2, 4, and 5, the output shaft 38 and the transmission shaft 40 are connected by a cylindrical connecting member 25, and a shaft support portion 30 is provided near the end of the output shaft 38.

[0055] Along the longitudinal direction of the output shaft 38, a cylindrical opening is formed in the shaft support portion 30, and four supply ports 30a, 30b, 30c, 30d (corresponding to the first supply port) are opened in the shaft support portion 30 and face the inner peripheral portion 30e of the opening of the shaft support portion 30.

[0056] In the shaft support portion 30, the supply ports 30a to 30d are provided at equal intervals along the longitudinal direction of the inner peripheral portion 30e of the shaft support portion 30. In the circumferential direction of the inner peripheral portion 30e of the shaft support portion 30, the supply ports 30a and 30c are provided at the same phase, the supply ports 30b and 30d are provided at the same phase, and the supply ports 30a, 30c and the supply ports 30b, 30d are provided at different phases.

[0057] (Configuration of the cylindrical member for supporting the output shaft) As shown in FIGS. 4 and 5, the cylindrical member 33 is attached to the inner peripheral portion 30e of the opening of the shaft support portion 30. As shown in FIGS. 6 and 7, the cylindrical member 33 has a main body portion 44, a ring portion 47, supply ports 55, 56, 57, 58 (corresponding to the second supply ports), and the like.

[0058] As shown in FIGS. 6 and 7, in the cylindrical member 33, the main body portion 44 is formed in a cylindrical shape. A plurality of ring portions 47 are formed on the outer peripheral portion of the main body portion 44 at intervals along the longitudinal direction, and a plurality of external groove portions 65, 66, 67, 68 are formed over the entire circumference of the outer peripheral portion of the cylindrical member 33 by the outer peripheral portion of the main body portion 44 and the lateral surface portions of the ring portions 47.

[0059] Four supply ports 55 are provided in the external groove portion 65, and the four supply ports 55 are arranged at equal intervals along the circumferential direction of the main body portion 44 and are opened across the external groove portion 65 and the inner peripheral portion 44a of the main body portion 44.

[0060] Similar to the supply port 55, four supply ports 56 are provided in the external groove portion 66, four supply ports 57 are provided in the external groove portion 67, and four supply ports 58 are provided in the external groove portion 68. The supply ports 55 to 58 are provided at the same phase as each other along the circumferential direction of the main body portion 44.

[0061] As shown in FIGS. 4 and 5, when the cylindrical member 33 is attached to the inner peripheral portion 30e of the shaft support portion 30, the supply port 30a of the shaft support portion 30 is connected to the external groove portion 65 of the cylindrical member 33 and is arranged between adjacent supply ports 55 of the cylindrical member 33 in the circumferential direction of the cylindrical member 33.

[0062] The supply port 30b of the shaft support portion 30 is connected to the external groove portion 66 of the cylindrical member 33 and is arranged between adjacent supply ports 56 of the cylindrical member 33 in the circumferential direction of the cylindrical member 33. The supply port 30c of the shaft support portion 30 is connected to the external groove portion 67 of the cylindrical member 33 and is arranged between adjacent supply ports 57 of the cylindrical member 33 in the circumferential direction of the cylindrical member 33. The supply port 30d of the shaft support portion 30 is connected to the outer groove portion 68 of the cylindrical member 33, and is arranged between adjacent supply ports 58 of the cylindrical member 33 in the circumferential direction of the cylindrical member 33.

[0063] (Configuration of the output shaft) As shown in FIGS. 8 and 9, at the end of the output shaft 38, a plurality of ring portions 48 are formed on the outer peripheral portion of the output shaft 38 at intervals along the longitudinal direction of the output shaft 38. By the ring portions 48, a plurality of shaft groove portions 71, 72, 73, 74 are formed along the circumferential direction of the output shaft 38 over the entire circumference of the outer peripheral portion of the output shaft 38.

[0064] As shown in FIGS. 4, 8, and 9, a plurality of inlet ports 75, 76, 77, 78 are formed inside the output shaft 38 along the radial direction of the output shaft 38. The inlet port 75 is connected to the shaft groove portion 71, the inlet port 76 is connected to the shaft groove portion 72, the inlet port 77 is connected to the shaft groove portion 73, and the inlet port 78 is connected to the shaft groove portion 74.

[0065] As shown in FIGS. 4 and 5, the inlet ports 75, 76 are provided in phases close to each other with a small interval in the circumferential direction of the output shaft 38. The inlet ports 77, 78 are provided in phases close to each other with a small interval in the circumferential direction of the output shaft 38. The inlet ports 75, 78 are provided in opposite phases in the circumferential direction of the output shaft 38, and the inlet ports 76, 77 are provided in opposite phases in the circumferential direction of the output shaft 38.

[0066] As shown in FIGS. 4 and 5, an oil passage 49 for supplying lubricating oil to each part is formed inside the output shaft 38 along the longitudinal direction of the output shaft 38. A plurality of supply oil passages 81, 82, 83, 84 are formed inside the output shaft 38 along the longitudinal direction of the output shaft 38. The supply oil passage 81 is connected to the inlet port 75 inside the output shaft 38 and is connected to the first clutch CL1 (see FIG. 2).

[0067] The supply oil passage 82 is connected to the inlet port 76 inside the output shaft 38 and is connected to the fourth clutch CL4 (see FIG. 2). The supply oil passage 83 is connected to the inlet port 77 inside the output shaft 38 and is connected to the second clutch CL2 (see FIG. 2). The supply oil passage 84 is connected to the inlet port 78 inside the output shaft 38 and is connected to the third clutch CL3 (see FIG. 2).

[0068] (Relationship among the output shaft, the shaft support portion, and the cylindrical member) As shown in FIGS. 6 and 7, in the cylindrical member 33, external groove portions 65 to 68 are formed along the circumferential direction of the inner peripheral portion 30e of the shaft support portion 30 over the entire circumference of the outer peripheral portion of the cylindrical member 33.

[0069] As shown in FIGS. 4 and 5, when the cylindrical member 33 is attached to the inner peripheral portion 30e of the shaft support portion 30, a plurality of external flow paths 85, 86, 87, and 88 are formed by the inner peripheral portion 30e of the shaft support portion 30 and the external groove portions 65 to 68 of the cylindrical member 33. Thereby, the external flow paths 85 to 88 are formed in a ring shape so as to surround the shaft groove portions 71 to 74 of the output shaft 38 (transmission shaft) and are provided in the shaft support portion 30.

[0070] The supply ports 30a to 30d (first supply ports) of the shaft support portion 30 are connected to the external flow paths 85 to 88 (external groove portions 65 to 68 of the cylindrical member 33). The supply ports 55 to 58 (second supply ports) of the cylindrical member 33 are provided across the external flow paths 85 to 88 (external groove portions 65 to 68 of the cylindrical member 33) and the inner peripheral portion 44a of the cylindrical member 33 (main body portion 44).

[0071] When the cylindrical member 33 is attached to the inner peripheral portion 30e of the shaft support portion 30, the inner peripheral portion 44a (see FIG. 7) of the cylindrical member 33 (main body portion 44) becomes the inner peripheral portion 30e of the shaft support portion 30. As a result, the supply ports 55 to 58 (second supply ports) of the cylindrical member 33 are provided across the external flow paths 85 to 88 (external groove portions 65 to 68 of the cylindrical member 33) and the inner peripheral portion 30e of the shaft support portion 30 (inner peripheral portion 44a of the cylindrical member 33 (main body portion 44)).

[0072] The supply port 55 (second supply port) of the cylindrical member 33 communicates with the shaft groove portion 71 of the output shaft 38 (transmission shaft). The supply port 56 (second supply port) of the cylindrical member 33 communicates with the shaft groove portion 72 of the output shaft 38 (transmission shaft).

[0073] The supply port 57 (second supply port) of the cylindrical member 33 communicates with the shaft groove portion 73 of the output shaft 38 (transmission shaft). The supply port 58 (second supply port) of the cylindrical member 33 communicates with the shaft groove portion 74 of the output shaft 38 (transmission shaft).

[0074] As shown in FIGS. 5, 6, and 7, in the cylindrical member 33, a plurality of supply ports 55 to 58 (second supply ports) are provided at intervals along the circumferential direction of the inner peripheral portion 30e of the shaft support portion 30.

[0075] As shown in FIG. 5, the supply ports 30a to 30d (first supply ports) of the shaft support portion 30 are arranged between the adjacent supply ports 55 to 58 (second supply ports) of the cylindrical member 33 in the circumferential direction of the cylindrical member 33, so that the supply ports 30a to 30d (first supply ports) of the shaft support portion 30 and the supply ports 55 to 58 (second supply ports) of the cylindrical member 33 are provided at different positions in the circumferential direction of the inner peripheral portion 30e of the shaft support portion 30.

[0076] As shown in FIG. 4, the cross-sectional area of the external flow paths 85 to 88 (external groove portions 65 to 68 of the cylindrical member 33) on the plane orthogonal to the circumferential direction of the inner peripheral portion 30e of the shaft support portion 30 is formed to be larger than the cross-sectional area of the shaft groove portions 71 to 74 of the output shaft 38 on the plane orthogonal to the circumferential direction of the output shaft 38 (transmission shaft).

[0077] (Supply state of hydraulic oil to the first clutch to the fourth clutch) As shown in FIGS. 4 and 5, when hydraulic oil is supplied to the supply ports 30a to 30d (first supply ports) of the shaft support portion 30, the following state is obtained.

[0078] The hydraulic oil supplied to the supply port 30a (first supply port) of the shaft support portion 30 flows from the supply port 30a (first supply port) of the shaft support portion 30 through the external flow path 85 (external groove portion 65 of the cylindrical member 33), the plurality of supply ports 55 (second supply ports) of the cylindrical member 33, the shaft groove portion 71 of the output shaft 38 (transmission shaft), the inlet port 75, and the supply oil path 81, and is supplied to the first clutch CL1 (hydraulic operating portion) (see FIG. 2), and the first clutch CL1 is operated to the transmission state.

[0079] The hydraulic oil supplied to the supply port 30b (first supply port) of the shaft support portion 30 flows from the supply port 30b (first supply port) of the shaft support portion 30 through the external flow path 86 (external groove portion 66 of the cylindrical member 33), the plurality of supply ports 56 (second supply ports) of the cylindrical member 33, the shaft groove portion 72 of the output shaft 38 (transmission shaft), the inlet port 76, and the supply oil path 82, and is supplied to the fourth clutch CL4 (hydraulic operating portion) (see FIG. 2), and the fourth clutch CL4 is operated to the transmission state.

[0080] The hydraulic oil supplied to the supply port 30c (first supply port) of the shaft support portion 30 flows from the supply port 30c (first supply port) of the shaft support portion 30 through the external flow path 87 (external groove portion 67 of the cylindrical member 33), the plurality of supply ports 57 (second supply ports) of the cylindrical member 33, the shaft groove portion 73 of the output shaft 38 (transmission shaft), the inlet port 77, and the supply oil path 83, and is supplied to the second clutch CL2 (hydraulic operating portion) (see FIG. 2), and the second clutch CL2 is operated to the transmission state.

[0081] The hydraulic oil supplied to the supply port 30d (first supply port) of the shaft support portion 30 is from the supply port 30d (first supply port) of the shaft support portion 30, through the external flow path 88 (external groove portion 68 of the cylindrical member 33), a plurality of supply ports 58 (second supply ports) of the cylindrical member 33, the shaft groove portion 74 of the output shaft 38 (transmission shaft), the inlet port 78, and the supply oil path 84, and is supplied to the third clutch CL3 (hydraulic operating portion) (see FIG. 2), and the third clutch CL3 is operated in a transmission state.

[0082] (First alternative form of the invention's implementation) In the cylindrical member 33, two or three supply ports 55 to 58 may be provided for one external groove portion 65 to 68 (external flow path 85 to 88), or five or six supply ports may be provided.

[0083] (Second alternative form of the invention's implementation) In each of the external groove portions 65 to 68 (external flow paths 85 to 88) of the cylindrical member 33, the number of supply ports 55 to 58 may be different. In each of the external groove portions 65 to 68 (external flow paths 85 to 88) of the cylindrical member 33, the supply ports 55 to 58 may be provided at different phases in the circumferential direction of the cylindrical member 33. The supply ports 55 to 58 of the cylindrical member 33 may be provided at unequal intervals in the circumferential direction of the cylindrical member 33.

[0084] (Third alternative form of the invention's implementation) The configurations shown in FIGS. 4 to 9, (the first alternative form of the invention's implementation) (the second alternative form of the invention's implementation) may be applied to the forward clutch CLF and the reverse clutch CLR of the forward and reverse switching device 20, and may also be applied to the standard clutch CLT and the overdrive clutch CLH of the front-wheel transmission device 26.

[0085] In this case, since there are two hydraulic operating portions, two supply ports 30a and 30b are provided in the shaft support portion 30. Two external groove portions 65 and 66 (external flow paths 85 and 86) and two sets of supply ports 55 and 56 are provided in the cylindrical member 33. Two shaft groove portions 71 and 72, two inlet ports 75 and 76, and two supply oil paths 81 and 82 are provided in the transmission shafts 40 and 43.

[0086] (Fourth Alternative Embodiment of the Invention) The configurations shown in FIGS. 4 to 9, (First Alternative Embodiment of the Invention) (Second Alternative Embodiment of the Invention), may be applied to the PTO clutch 15.

[0087] In this case, since there is one hydraulic operating part, one supply port 30a is provided in the shaft support part 30. One external groove part 65 (external flow path 85) and one set of supply ports 55 are provided in the cylindrical member 33. One shaft groove part 71, one inlet port 75, and one supply oil path 81 are provided in the transmission shaft 32.

[0088] (Fifth Alternative Embodiment of the Invention) The cylindrical member 33 may be abolished. According to this configuration, in addition to the supply ports 30a to 30d being provided in the shaft support part 30, the external flow paths 85 to 88 and the supply ports 55 to 58 are directly opened to the shaft support part 30.

[0089] Instead of the configuration of supplying the hydraulic oil from the supply oil paths 81 to 84 to the hydraulic clutch, it may be configured to supply the hydraulic oil to the hydraulic operation part (corresponding to the hydraulic operating part) that slide-operates the shift gears of the gear transmission device via the supply oil paths 81 to 84.

Industrial Applicability

[0090] The present invention can be applied not only to tractors, but also to agricultural work vehicles such as combines and ride-on rice transplanters, and can also be applied to construction work vehicles such as backhoes and wheel loaders.

Explanation of Signs

[0091] 30 Shaft support part 30a to 30d Supply port (First supply port) 30e Inner peripheral part 33 Cylindrical member 38 Output shaft (Transmission shaft) 44a Inner peripheral part 55 to 58 Supply port (Second supply port) 65 to 68 External groove part 71 - 74 Shaft groove part 75 - 78 Inlet port 81 - 84 Supply oil passage 85 - 88 External flow path CL1 First clutch (hydraulic actuator) CL2 Second clutch (hydraulic actuator) CL3 Third clutch (hydraulic actuator) CL4 Fourth clutch (hydraulic actuator)

Claims

1. A work vehicle comprising a transmission shaft that is rotationally driven, a shaft support portion that rotatably supports the transmission shaft, and a hydraulic actuator that operates when hydraulic oil is supplied. On the transmission shaft, an axial groove portion formed along the circumferential direction of the transmission shaft and extending over the entire outer peripheral portion of the transmission shaft; an inlet port formed inside the transmission shaft along the radial direction of the transmission shaft and connected to the axial groove portion; a supply oil passage formed inside the transmission shaft along the longitudinal direction of the transmission shaft and connected to the inlet port inside the transmission shaft. On the shaft support portion, an external flow path formed in a ring shape so as to surround the axial groove portion; a first supply port provided so as to be connected to the external flow path and to which hydraulic oil is supplied; a second supply port provided across the external flow path and the inner peripheral portion of the shaft support portion and communicating with the axial groove portion. A work vehicle in which the hydraulic oil supplied to the first supply port is supplied to the hydraulic actuator through the external flow path, the second supply port, the axial groove portion, the inlet port, and the supply oil passage from the first supply port.

2. The work vehicle according to claim 1, wherein a plurality of the second supply ports are provided at intervals along the circumferential direction of the inner peripheral portion of the shaft support portion.

3. The work vehicle according to claim 2, wherein the first supply port and the second supply port are provided at different positions in the circumferential direction of the inner peripheral portion of the shaft support portion.

4. The work vehicle according to claim 3, wherein a cross-sectional area of the external flow path in a plane orthogonal to the circumferential direction of the inner peripheral portion of the shaft support portion is formed to be larger than a cross-sectional area of the axial groove portion in a plane orthogonal to the circumferential direction of the transmission shaft.

5. A cylindrical member is provided that is attached to the inner peripheral portion of the shaft support portion and rotatably supports the transmission shaft so that the transmission shaft is rotatably supported by the shaft support portion. On the cylindrical member, an external groove portion formed along the circumferential direction of the inner peripheral portion of the shaft support portion and extending over the entire outer peripheral portion of the cylindrical member, and forming the external flow path together with the inner peripheral portion of the shaft support portion; The work vehicle according to any one of claims 1 to 4, wherein the second supply port is provided across the external groove portion and the inner peripheral portion of the cylindrical member and communicates with the axial groove portion.

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