JP7564801B2 - Transmissions and Work Vehicles - Google Patents

Description

The present invention relates to a transmission and a work vehicle equipped with the transmission.

Work vehicles such as combine harvesters are equipped with a transmission that transmits power for traveling to a pair of left and right crawler traveling devices.

The transmission is equipped with, for example, an HST (Hydro Static Transmission), a clutch for switching between transmitting and cutting off power to the crawler travel device, and a parking brake for keeping the work vehicle stationary.

The HST has a closed circuit in which hydraulic oil circulates between the hydraulic pump and the hydraulic motor. In the HST, the hydraulic pump is driven by engine power, and the hydraulic motor is driven by the oil discharged by the hydraulic pump.

The transmission is equipped with a clutch shaft rotatably supported on a case forming the outer shell of the transmission, a center gear fixed to the clutch shaft, and a clutch sleeve supported on the clutch shaft so as to be movable in the axial direction and rotatable relative to the clutch shaft. Power is input to the center gear from the hydraulic motor of the HST. Teeth are formed on the clutch sleeve side of the center gear, and teeth that mesh with the teeth of the center gear are formed on the clutch sleeve, so the clutch has a dog clutch configuration.

A clutch pedal is provided inside the cabin. When the clutch pedal is not depressed, the teeth of the center gear and the teeth of the clutch sleeve are engaged, and the power input to the center gear causes the center gear and clutch sleeve to rotate together, and the power generated by the rotation of the clutch sleeve is transmitted to the crawler traveling device. When the clutch pedal is depressed from this state, the clutch sleeve moves in the axial direction of the clutch shaft away from the center gear, and the teeth of the center gear and the teeth of the clutch sleeve are released from engagement. This cuts off the transmission of power input to the center gear to the crawler traveling device.

The parking brake has a structure in which brake discs held by the clutch shaft and brake plates held by a case are arranged alternately in the axial direction of the clutch shaft. An operating member having a cam mechanism is provided further inside the innermost brake plate. The operating member is rotatably held in the case.

For example, a parking brake pedal is provided inside the cabin. The parking brake pedal and the actuating member are mechanically connected, and when the parking brake pedal is depressed, the force is transmitted to the actuating member, causing the actuating member to rotate. When the actuating member rotates, the cam mechanism of the actuating member functions to cause the actuating member to press the innermost brake plate, bringing the clutch disc and clutch plate into pressure contact, engaging the parking brake and prohibiting rotation of the clutch shaft. With the clutch engaged and the center gear and clutch sleeve connected, the parking brake prohibits rotation of the clutch shaft, prohibiting rotation of the clutch sleeve, braking the crawler traveling device, and maintaining the work vehicle stopped.

JP 2012-61977 A

In this type of structure, in order to brake the crawler travelling device, a clutch is required to connect/disconnect the center gear and the clutch sleeve in addition to a parking brake that prohibits/allows rotation of the clutch shaft, making the transmission structure complicated.

The object of the present invention is to provide a transmission and a work vehicle that can brake a first rotating shaft and a second rotating shaft that are rotatable relative to each other with a simple configuration.

In order to achieve the above object, a transmission according to one aspect of the present invention is a transmission that is mounted on a work vehicle and transmits power to a pair of left and right traveling devices for traveling the work vehicle, and includes a first rotating shaft that is rotatable about a rotation axis that extends in a predetermined direction, a second rotating shaft that is rotatable about a common rotation axis with the first rotating shaft and rotatable relative to the first rotating shaft, a first brake that brakes/releases the first rotating shaft, a second brake that brakes/releases the second rotating shaft, and an operating member that, when activated, causes the first brake to generate a braking force that brakes the first rotating shaft and causes the second brake to generate a braking force that brakes the second rotating shaft.

According to this configuration, the first rotating shaft and the second rotating shaft are arranged to be rotatable around a common rotation axis. The first rotating shaft and the second rotating shaft are capable of relative rotation. In addition, a first brake and a second brake are provided to brake/release the first rotating shaft and the second rotating shaft, respectively. One operating member is provided for the first brake and the second brake, and by operating the one operating member, a braking force for braking the first rotating shaft is generated in the first brake, and a braking force for braking the second rotating shaft is generated in the second brake. Thus, with a simple configuration, it is possible to brake the first rotating shaft and the second rotating shaft, which are capable of relative rotation.

The transmission further includes a case forming an outer shell, the first brake has a configuration in which a first brake disc fixed to the first rotating shaft and a first brake plate fixed to the case are alternately arranged in the direction of the rotation axis, the second brake has a configuration in which a second brake disc fixed to the second rotating shaft and a second brake plate fixed to the case are alternately arranged in the direction of the rotation axis, and the actuating member may generate a braking force in the first brake by pressing the first brake disc and the first brake plate in the direction of the rotation axis, and generate a braking force in the second brake by pressing the second brake disc and the second brake plate in the direction of the rotation axis.

The first brake disc and the first brake plate are disposed adjacent to one side of the second brake disc and the second brake plate in the direction of the rotation axis, and the actuating member is actuated to press the first brake plate from one side, and the pressing force may bring the first brake disc and the first brake plate into pressure contact, and the second brake disc and the second brake plate into pressure contact.

The transmission may further include hydrostatic continuously variable transmissions provided independently on the left and right corresponding to the respective traveling devices, and the power output from the left and right hydrostatic continuously variable transmissions may be transmitted to the left and right traveling devices, respectively.

In this configuration, the power output from one hydrostatic continuously variable transmission can be transmitted to one traveling device via the first rotating shaft. Also, the power output from the other hydrostatic continuously variable transmission can be transmitted to one traveling device via the second rotating shaft.

The first rotating shaft may be formed in an axial shape, and the second rotating shaft may be formed in a cylindrical shape and inserted onto the first rotating shaft.

In this configuration, by moving the second rotating shaft closer to one end of the first rotating shaft, the first brake and the second brake can be centralized at that end. As a result, the maintenance work for the first brake and the second brake can be reduced.

A work vehicle according to another aspect of the present invention includes an engine, a pair of left and right traveling devices, and a transmission that transmits the power of the engine to the left and right traveling devices independently. The transmission is mounted on the work vehicle and transmits power to the pair of left and right traveling devices for traveling the work vehicle, and includes at least a first rotating shaft that is rotatable about a rotation axis that extends in a predetermined direction, a second rotating shaft that is rotatable about a common rotation axis with the first rotating shaft and rotatable relative to the first rotating shaft, a first brake that brakes/releases the first rotating shaft, a second brake that brakes/releases the second rotating shaft, and an operating member that, when activated, causes the first brake to generate a braking force that brakes the first rotating shaft and causes the second brake to generate a braking force that brakes the second rotating shaft.

This configuration can achieve the same effects as the transmission according to the first aspect.

According to the present invention, a simple configuration can be used to brake a first rotating shaft and a second rotating shaft that are capable of rotating relative to one another.

FIG. 2 is a right side view of a combine harvester according to one embodiment of the present invention. 1 is a cross-sectional view of a transmission showing a first gear train provided in the transmission; 2 is a cross-sectional view of the transmission showing an upper portion of a second gear train provided in the transmission. 2 is a cross-sectional view of the transmission showing the lower part of a second gear train provided in the transmission. FIG. 2 is a perspective view of the first gear train and the second gear train as viewed from one side in the left-right direction. FIG. 4 is a perspective view of the first gear train and the second gear train as viewed from the other side in the left-right direction. FIG. 2 is a cross-sectional view showing the configuration of a parking brake. FIG.

The following describes in detail an embodiment of the present invention with reference to the attached drawings.

<Combine>
FIG. 1 is a right side view of a combine harvester 1 according to an embodiment of the present invention.

The combine harvester 1 is an example of a harvesting machine that harvests and threshes stalks while traveling in a farm field. The combine harvester 1 employs a pair of left and right crawler traveling devices 2 as traveling devices capable of traveling over uneven ground such as farm fields, and a cabin 4 and a grain tank 5 are provided on a machine body 3 supported by the pair of left and right crawler traveling devices 2.

The cabin 4 is disposed on the front end of the crawler traveling device 2. The cabin 4 provides a space for the driver inside, and within this space, for example, a driver's seat where the driver sits, and operating members such as operating levers and operating pedals are disposed. An openable door 6 is provided on the right side of the cabin 4, and the driver can open the door 6 to enter the cabin 4.

The grain tank 5 is located behind the cabin 4 on the crawler running device 2.

The body 3 of the combine harvester 1 is also provided with a harvesting device 7 and a thresher (not shown). The harvesting device 7 is located in front of the crawler travel device 2, and harvests the culms planted in the field as the combine harvester 1 moves forward. The thresher is located to the left of the grain tank 5, and the base side of the culms harvested by the harvesting device 7 is transported to the rear side by a threshing feed chain, and the tip side of the culms is supplied to a threshing chamber for threshing. The grains that have fallen off the culms are then transported from the thresher to the grain tank 5, where they are stored. An unloader 8 is connected to the grain tank 5, and the grains stored in the grain tank 5 can be removed by the unloader 8 and discharged outside the machine.

<Transmission>
2A, 2B and 2C are cross-sectional views of the transmission 12.

The combine harvester 1 is equipped with a transmission 12 that transmits the power of the engine 11 to the left and right crawler driving devices 2.

The transmission 12 has a case 13 that forms its outer shell. The case 13 is divided into two parts, left and right. Each divided part 13A, 13B is formed like a container with an open side facing each other, and is butted against each other with a gasket 14 in between. Each divided part 13A, 13B and the gasket 14 are formed with a partition that extends in the front-rear direction. These partitions overlap in the left-right direction, and the inside of the case 13 is divided by the overlapping partition into an upper space 15 shown in FIG. 2A and a lower space 16 below it.

An input shaft 21 is provided in the upper space 15. The input shaft 21 extends in the left-right direction across the divided parts 13A and 13B of the case 13, and is rotatably supported by the divided parts 13A and 13B via ball bearings 22A and 22B, respectively. One end of the input shaft 21 (the end on the divided part 13A side) penetrates the divided part 13A and protrudes outside the case 13. The one end is supported outside the case 13 so that the pulley 22 rotates together with it (it cannot rotate relative to it).

Meanwhile, an engine pulley (not shown) is supported on the output shaft of the engine 11 so as to rotate integrally. An endless belt (not shown) is wound around the engine pulley and pulley 22. As a result, the power of the output shaft of the engine 11 is transmitted to the pulley 22 via the engine pulley and the belt, causing the pulley 17 and the input shaft 21 to rotate.

The other end of the input shaft 21 (the end on the split part 13B side) is connected to the inner rotor of the charge pump 23. The charge pump 23 is a fixed displacement hydraulic pump that delivers oil to the charge oil passage by the rotation of the input shaft 21 (inner rotor). A charge relief valve is connected to the charge oil passage, and the hydraulic pressure in the charge oil passage is maintained at a predetermined charge pressure by the function of the charge relief valve.

The transmission 12 also includes HSTs (Hydro Static Transmissions) 24A, 24B. Each HST 24A, 24B includes a hydraulic pump and a hydraulic motor. In each HST 24A, 24B, a closed circuit is formed between the hydraulic pump and the hydraulic motor to circulate hydraulic oil. The closed circuits of the HSTs 24A, 24B are each connected to a charge oil passage via a check valve, and the hydraulic pressure in the closed circuits of the HSTs 24A, 24B is maintained above the charge pressure by the function of the check valve.

Figure 3 is a perspective view of the first gear train 31 and the second gear train 32 as viewed from one side in the left-right direction. Figure 4 is a perspective view of the first gear train 31 and the second gear train 32 as viewed from the other side in the left-right direction.

The transmission 12 has a first gear train 31 and a second gear train 32.

The first gear train 31 is housed in the upper space 15. The first gear train 31 includes an input gear 33, an intermediate gear 34, and a pump gear 35.

As shown in FIG. 2A, the input gear 33 integrally comprises a substantially cylindrical boss portion 41, a substantially annular web portion 42 extending radially outward from the outer circumferential surface of the boss portion 41, and a substantially cylindrical rim portion 43 to which the outer circumferential end of the web portion 42 is connected. The boss portion 41 is fitted onto the input shaft 21 and is coupled to rotate integrally with the input shaft 21. Gear teeth are formed on the outer circumferential surface of the rim portion 43.

The intermediate gear 34 is disposed in front of the input gear 33. The intermediate gear 34 is integrally provided with a substantially cylindrical boss portion 44, a substantially annular web portion 45 extending radially outward from the outer circumferential surface of the boss portion 44, and a substantially cylindrical rim portion 46 to which the outer circumferential end of the web portion 45 is connected. The boss portion 44 extends in the left-right direction parallel to the input shaft 21, and is rotatably supported by the divided portions 13A and 13B of the case 13 via ball bearings 47A and 47B, respectively. Gear teeth are formed on the outer circumferential surface of the rim portion 46, and the gear teeth mesh with the gear teeth of the input gear 33.

The pump gear 35 is disposed in front of the intermediate gear 34. The pump gear 35 integrally comprises a substantially cylindrical boss portion 51, a substantially annular web portion 52 extending radially outward from the outer circumferential surface of the boss portion 51, and a substantially cylindrical rim portion 53 to which the outer circumferential end of the web portion 52 is connected. The boss portion 51 extends in the left-right direction parallel to the input shaft 21, and is rotatably supported by the divided portions 13A and 13B of the case 13 via ball bearings 54A and 54B, respectively. Gear teeth are formed on the outer circumferential surface of the rim portion 53, and the gear teeth mesh with the gear teeth of the intermediate gear 34.

The pump shaft 55A of the hydraulic pump of HST24A and the pump shaft 55B of HST24B are inserted into the boss portion 51 of the pump gear 35 from both the left and right sides, and the pump shafts 55A and 55B are connected so that they rotate together.

Power transmitted from the engine 11 to the input shaft 21 is transmitted to the pump shafts 55A, 55B via the input gear 33, intermediate gear 34, and pump gear 35, causing the pump shafts 55A, 55B to rotate. The rotation of the pump shafts 55A, 55B causes oil to be discharged from each hydraulic pump of the HSTs 24A, 24B, and the oil discharged from each hydraulic pump drives each hydraulic motor of the HSTs 24A, 24B.

Each hydraulic motor of the HST 24A, 24B is equipped with a motor output shaft 56A, 56B, respectively. The motor output shafts 56A, 56B extend in the left-right direction in the upper front part of the lower space 16 and are arranged to have the same central axis. The motor output shafts 56A, 56B pass through the divided parts 13A, 13B of the case 13, respectively, and are connected to the motor body of the hydraulic motor outside the case 13.

The second gear train 32 is housed in the lower space 16. The second gear train 32 includes motor output gears 61A, 61B, first intermediate gears 62A, 62B, second intermediate gears 63A, 63B, third intermediate gears 64A, 64B, fourth intermediate gears 65A, 65B, fifth intermediate gears 66A, 66B, sixth intermediate gears 67A, 67B, and final gears 68A, 68B.

As shown in FIG. 2B, the motor output gear 61A integrally comprises a substantially cylindrical boss portion 71A, a substantially annular disk-shaped web portion 72A extending radially outward from the outer circumferential surface of the boss portion 71A, and a substantially cylindrical rim portion 73A to which the outer circumferential end of the web portion 72A is connected.

The motor output gear 61B is integrally provided with a substantially cylindrical boss portion 71B, a substantially annular disk-shaped web portion 72B that extends radially outward from the outer circumferential surface of the boss portion 71B, and a substantially cylindrical rim portion 73B to which the outer circumferential end of the web portion 72B is connected.

The motor output shafts 56A and 56B are inserted into the bosses 71A and 71B from the outside in the left-right direction, and the motor output shafts 56A and 56B are connected so that they rotate together.

Gear teeth are formed on the outer circumferential surfaces of the rim portions 73A and 73B. The motor output gears 61A and 61B are formed with the same root circle diameter, tip circle diameter, and number of teeth.

The inner rings of ball bearings 74A and 74B are fitted around the motor output shafts 56A and 56B, respectively. The inner rings of ball bearings 75A and 75B are fitted around the bosses 71A and 71B, respectively. The outer rings of the ball bearings 74A and 75A are held in the divided part 13A of the case 13, and the outer rings of the ball bearings 74B and 75B are held in the divided part 13B of the case 13. As a result, the motor output shaft 56A and the motor output gear 61A are rotatably supported by the divided part 13A via the ball bearings 74A and 75A, and the motor output shaft 56B and the motor output gear 61B are rotatably supported by the divided part 13B via the ball bearings 74B and 75B. A thrust needle bearing 76 is interposed between the motor output gears 61A and 61B.

The first intermediate gears 62A and 62B are disposed rearward of the motor output gears 61A and 61B, respectively, as shown in Figures 3 and 4.

As shown in FIG. 2B, the first intermediate gear 62A integrally comprises a substantially cylindrical boss portion 81A, a substantially annular disk-shaped web portion 82A extending radially outward from the outer circumferential surface of the boss portion 81A, and a substantially cylindrical rim portion 83A to which the outer circumferential end of the web portion 82A is connected. The boss portion 81A has a reduced diameter portion at the end opposite the first intermediate gear 62B side with respect to the web portion 82A, which is reduced in diameter compared to the remaining portions. Gear teeth are formed on the outer circumferential surface of the rim portion 83A, and the gear teeth mesh with the gear teeth of the motor output gear 61A.

The first intermediate gear 62B integrally comprises a substantially cylindrical boss portion 81B, a substantially annular web portion 82B extending radially outward from the outer circumferential surface of the boss portion 81B, and a substantially cylindrical rim portion 83B to which the outer circumferential end of the web portion 82B is connected. The boss portion 81B has a reduced diameter portion at the end opposite the first intermediate gear 62A side of the web portion 82B, which is smaller in diameter than the remaining portions. Gear teeth are formed on the outer circumferential surface of the rim portion 83B, and the gear teeth mesh with the gear teeth of the motor output gear 61B.

The first intermediate gears 62A and 62B are formed with the same root diameter, tip diameter and number of teeth.

The first intermediate shaft 84 is inserted through the bosses 81A and 81B. The first intermediate shaft 84 is rotatably supported by the divided parts 13A and 13B of the case 13 via roller bearings 85A and 85B, respectively. A needle bearing 86 is interposed between the boss 81A and the first intermediate shaft 84. The boss 81B is coupled to the first intermediate shaft 84 so as to rotate integrally therewith. As a result, the first intermediate gear 62A is provided so as to be rotatable relative to the first intermediate shaft 84, and the first intermediate gear 62B is provided so as to rotate integrally with the first intermediate shaft 84.

The second intermediate gear 63A is fitted onto the first intermediate shaft 84 on the side opposite the first intermediate gear 62B side with respect to the first intermediate gear 62A. The second intermediate gear 63A is formed in a substantially cylindrical shape, and has a reduced diameter portion at the end on the first intermediate gear 62A side that is smaller in diameter than the other bulging portions. Gear teeth are formed on the outer peripheral surface of the bulging portion. The outer diameter of the reduced diameter portion is equal to the outer diameter of the reduced diameter portion of the first intermediate gear 62A. A needle bearing 87 is interposed between the second intermediate gear 63A and the first intermediate shaft 84, and the second intermediate gear 63A is supported on the first intermediate shaft 84 via the needle bearing 87 so as to be capable of relative rotation.

The second intermediate gear 63B is fitted onto the first intermediate shaft 84 on the side opposite the first intermediate gear 62A side with respect to the first intermediate gear 62B. The second intermediate gear 63B is formed in a substantially cylindrical shape, and gear teeth are formed on the outer circumferential surface. A bush (slide bearing) 88 is interposed between the second intermediate gear 63B and the first intermediate shaft 84, and the second intermediate gear 63B is supported on the first intermediate shaft 84 via the bush 88 so as to be capable of relative rotation.

The second intermediate gears 63A and 63B are formed with the same root diameter, tip diameter and number of teeth.

A flat cylindrical (annular) boss 89 is fitted onto the first intermediate shaft 84 between the first intermediate gear 62B and the second intermediate gear 63B. The outer diameter of the boss 89 is equal to the outer diameter of the reduced diameter portion of the first intermediate gear 62B. The boss 89 is connected to the second intermediate gear 63B so as to rotate integrally with it.

A shifter 91A is fitted onto the reduced diameter portion of the second intermediate gear 63A. The shifter 91A is movable in the axial direction of the first intermediate shaft 84 between a neutral position where it is spline-coupled only to the reduced diameter portion of the second intermediate gear 63A, and a drive position where it is spline-coupled to both the first intermediate gear 62A and the second intermediate gear 63A, straddling the reduced diameter portion of the first intermediate gear 62A and the reduced diameter portion of the second intermediate gear 63A.

A shifter 91B is fitted onto the reduced diameter portion of the first intermediate gear 62B. The shifter 91B is movable in the axial direction of the first intermediate shaft 84 between a neutral position where it is spline-engaged only with the reduced diameter portion of the first intermediate gear 62B, and a drive position where it straddles the reduced diameter portion of the first intermediate gear 62B and the boss 89 and is spline-engaged with both the first intermediate gear 62B and the boss 89.

The third intermediate gears 64A and 64B are disposed rearward and below the second intermediate gears 63A and 63B, respectively, as shown in Figures 3 and 4.

As shown in FIG. 2B, the third intermediate gear 64A integrally comprises a substantially cylindrical boss portion 101A, a substantially annular web portion 102A extending radially outward from the outer circumferential surface of the boss portion 101A, and a substantially cylindrical rim portion 103A to which the outer circumferential end of the web portion 102A is connected. Gear teeth are formed on the outer circumferential surface of the rim portion 103A, and the gear teeth mesh with the gear teeth of the second intermediate gear 63A.

The third intermediate gear 64B integrally comprises a substantially cylindrical boss portion 101B, a substantially annular disk-shaped web portion 102B extending radially outward from the outer circumferential surface of the boss portion 101B, and a substantially cylindrical rim portion 103B to which the outer circumferential end of the web portion 102B is connected. Gear teeth are formed on the outer circumferential surface of the rim portion 103B, and the gear teeth mesh with the gear teeth of the second intermediate gear 63B.

The third intermediate gears 64A and 64B are formed with the same root diameter, tip diameter and number of teeth.

The second intermediate shaft 104 is inserted through the boss portions 101A and 101B. The second intermediate shaft 104 is formed with a relatively large diameter on the third intermediate gear 64A side with respect to the center in the left-right direction, and is formed with a relatively small diameter on the opposite side (the third intermediate gear 64B side). A substantially cylindrical boss 105 is inserted on the small diameter portion of the second intermediate shaft 104 (the portion on the third intermediate gear 64B side with respect to the center in the left-right direction), and the boss 105 is provided so as to have a common rotation axis. Needle bearings 106 and 107 are interposed between the outer peripheral surface of the second intermediate shaft 104 and the inner peripheral surface of the boss 105, and the boss 105 is provided so as to be rotatable relative to the second intermediate shaft 104.

The inner ring of a ball bearing 108 is fitted onto the large diameter end of the second intermediate shaft 104. The outer ring of the ball bearing 108 is held by the divided part 13A of the case 13. The inner ring of a ball bearing 109 is fitted onto the boss 105 on the side opposite the third intermediate gear 64A with respect to the third intermediate gear 64B. The outer ring of the ball bearing 108 is held by the divided part 13B of the case 13. As a result, the second intermediate shaft 104 and the boss 105 are rotatably supported by the divided parts 13A and 13B via the ball bearings 108 and 109, respectively.

A fourth intermediate gear 65A is fitted onto the large diameter portion of the second intermediate shaft 104 on the third intermediate gear 64B side relative to the third intermediate gear 64A, and is coupled so as to rotate integrally with the second intermediate shaft 104. The fourth intermediate gear 65A is formed in a substantially cylindrical shape, and gear teeth are formed on its outer circumferential surface.

A fourth intermediate gear 65B is fitted onto the boss 105 on the third intermediate gear 64A side relative to the third intermediate gear 64B, and the fourth intermediate gear 65B is coupled to rotate integrally with the boss 105. The fourth intermediate gear 65B is formed in a substantially cylindrical shape, and gear teeth are formed on its outer circumferential surface.

The fourth intermediate gears 65A and 65B are formed with the same root diameter, tip diameter and number of teeth.

The fifth intermediate gears 66A and 66B are disposed below and in front of the fourth intermediate gears 65A and 65B, respectively, as shown in Figures 3 and 4.

As shown in Figures 2B and 2C, the fifth intermediate gear 66A integrally comprises a substantially cylindrical boss portion 111A, a substantially annular disk-shaped web portion 112A extending radially outward from the outer circumferential surface of the boss portion 111A, and a substantially cylindrical rim portion 113A to which the outer circumferential end of the web portion 112A is connected. Gear teeth are formed on the outer circumferential surface of the rim portion 113A, and the gear teeth mesh with the gear teeth of the fourth intermediate gear 65A.

The fifth intermediate gear 66B is integrally provided with a substantially cylindrical boss portion 111B, a substantially annular disk-shaped web portion 112B extending radially outward from the outer circumferential surface of the boss portion 111B, and a substantially cylindrical rim portion 113B to which the outer circumferential end of the web portion 112B is connected. Gear teeth are formed on the outer circumferential surface of the rim portion 113B, and the gear teeth mesh with the gear teeth of the fourth intermediate gear 65B.

The fifth intermediate gears 66A and 66B are formed with the same root diameter, tip diameter and number of teeth.

A third intermediate shaft 114 is inserted through the bosses 111A and 111B. The third intermediate shaft 114 has a relatively large cylindrical large diameter portion 114A on the fifth intermediate gear 66A side relative to the center in the left-right direction, and a relatively small cylindrical small diameter portion 114B on the opposite side, the fifth intermediate gear 66B side. A step is formed midway in the axial direction on the small diameter portion 114B of the third intermediate shaft 114, and a spline 115 is formed across the step.

A sixth intermediate gear 67A is provided on the large diameter portion 114A of the third intermediate shaft 114. The sixth intermediate gear 67A is formed in a substantially cylindrical shape and is fitted onto the third intermediate shaft 114. Needle bearings 116, 117 are interposed between the inner peripheral surface of the sixth intermediate gear 67A and the outer peripheral surface of the third intermediate shaft 114. As a result, the sixth intermediate gear 67A is rotatably supported by the third intermediate shaft 114 via the needle bearings 116, 117. Gear teeth are formed on the outer peripheral surface of the sixth intermediate gear 67A.

A sixth intermediate gear 67B is provided on the small diameter portion 114B of the third intermediate shaft 114. The sixth intermediate gear 67B is formed in a substantially cylindrical shape and is fitted onto the third intermediate shaft 114. A spline 118 is formed on the inner peripheral surface of the sixth intermediate gear 67B, and the spline 118 engages with the spline 115 of the third intermediate shaft 114, so that the sixth intermediate gear 67B rotates integrally with the third intermediate shaft 114 (is not rotatable relative to the third intermediate shaft 114). Gear teeth are formed on the outer peripheral surface of the sixth intermediate gear 67B.

The sixth intermediate gears 67A and 67B are formed with the same root diameter, tip diameter, tooth width and number of teeth.

The inner peripheral surface of the boss portion 111A of the fifth intermediate gear 66A has gear teeth that mesh with the sixth intermediate gear 67A. The gear teeth of the boss portion 111A mesh with the sixth intermediate gear 67A, causing the fifth intermediate gear 66A and the sixth intermediate gear 67A to rotate together. An annular stopper 119A is provided across the outer peripheral surface of the sixth intermediate gear 67A and the inner peripheral surface of the boss portion 111A, fixing the fifth intermediate gear 66A and the sixth intermediate gear 67A to each other in the direction of the rotation axis.

The inner peripheral surface of the boss portion 111B of the fifth intermediate gear 66B has gear teeth that mesh with the sixth intermediate gear 67B. The gear teeth of the boss portion 111B mesh with the sixth intermediate gear 67B, causing the fifth intermediate gear 66B and the sixth intermediate gear 67B to rotate together. An annular stopper 119B is provided across the outer peripheral surface of the sixth intermediate gear 67B and the inner peripheral surface of the boss portion 111B, fixing the fifth intermediate gear 66B and the sixth intermediate gear 67B to each other in the direction of the rotation axis.

The end 121A of the third intermediate shaft 114 on the sixth intermediate gear 67A side is cylindrical with an outer circumferential surface with a smaller diameter than the small diameter portion 114B of the third intermediate shaft 114, and protrudes outward from the sixth intermediate gear 67A. On the other hand, the end 121B of the third intermediate shaft 114 on the sixth intermediate gear 67B side is cylindrical with an outer circumferential surface and axial dimensions of the same diameter as the end 121A, and protrudes outward from the sixth intermediate gear 67B.

The inner rings of ball bearings 122A and 122B are fitted around the ends 121A and 121B of the third intermediate shaft 114. The outer rings of the ball bearings 122A and 122B are held in the divided parts 13A and 13B of the case 13, respectively. As a result, the assembly formed by assembling the sixth intermediate gears 67A and 67B and the needle bearings 116 and 117 to the third intermediate shaft 114 is rotatably supported on the case 13 via the ball bearings 122A and 122B. Annular plate-shaped thrust collars 123 and 124 fixed to the third intermediate shaft 114 are interposed between the ball bearing 122A and the sixth intermediate gear 67A, and between the sixth intermediate gear 67A and the sixth intermediate gear 67B, respectively.

As shown in Figures 3 and 4, the final gears 68A and 68B are located below and rearward of the sixth intermediate gears 67A and 67B, respectively.

As shown in FIG. 2C, the final gear 68A integrally comprises a substantially cylindrical boss portion 131A, a substantially annular disk-shaped web portion 132A extending radially outward from the outer circumferential surface of the boss portion 131A, and a substantially cylindrical rim portion 133A to which the outer circumferential end of the web portion 132A is connected. Gear teeth are formed on the outer circumferential surface of the rim portion 133A, and the gear teeth mesh with the gear teeth of the sixth intermediate gear 67A.

The final gear 68B is integrally provided with a substantially cylindrical boss portion 131B, a substantially annular disk-shaped web portion 132B extending radially outward from the outer circumferential surface of the boss portion 131B, and a substantially cylindrical rim portion 133A to which the outer circumferential end of the web portion 132B is connected. Gear teeth are formed on the outer circumferential surface of the rim portion 133B, and the gear teeth mesh with the gear teeth of the sixth intermediate gear 67B.

An assembly formed by assembling the final shafts 134A and 134B together is inserted into the bosses 131A and 131B. The final shaft 134A is formed in a substantially cylindrical shape. The boss 131A is splined to the final shaft 134A so as to rotate integrally with the final shaft 134A. The final shaft 134B integrally has a substantially cylindrical main body 135, a substantially cylindrical inserting portion 136 extending from the main body 135 to the divided portion 13A side of the case 13, and a substantially cylindrical inserted portion 137 extending from the main body 135 to the divided portion 13B side of the case 13. The boss 131B is splined to the main body 135 so as to rotate integrally with the final shaft 134B.

A circular plate-shaped thrust collar 141 is fitted onto the insert 136. The outer diameter of the insert 136 is smaller than the inner diameter of the final shaft 134A, and the insert 136 is inserted into the final shaft 134A. Needle bearings 142 and 143 are interposed between the inner peripheral surface of the final shaft 134A and the outer peripheral surface of the insert 136.

The outer diameter of the main body 135 is larger than the inner diameter of the final shaft 134A and is equal to the outer diameter of the end of the final shaft 134A on the divided part 13B side. The outer diameter of the thrust collar 141 is equal to the outer diameter of the main body 135. As a result, the surface of the main body 135 that is created by the difference in outer diameter with the insertion part 136 faces the end face of the final shaft 134A on the divided part 13B side, and the thrust collar 141 is sandwiched between these opposing surfaces.

The assembly of the final shafts 134A and 134B is rotatably supported on the case 13 via ball bearings 144 and 145. The same ball bearings are used for the ball bearings 144 and 145. The inner ring of the ball bearing 144 is fitted onto the final shaft 134A, and the outer ring of the ball bearing 144 is held by the divided part 13A of the case 13. The inner ring of the ball bearing 145 is fitted onto the final shaft 134B, and the outer ring of the ball bearing 145 is held by the divided part 13B of the case 13.

An axle shaft 146A is inserted through the divided portion 13A of the case 13. One end of the axle shaft 146A is connected to a drive roller (drive sprocket) 147A, which serves as a drive wheel for the crawler traveling device 2 (see FIG. 1). The other end of the axle shaft 146A is inserted into the final shaft 134A and splined to the final shaft 134A so that the final shaft 134A and the axle shaft 146A rotate integrally.

An axle shaft 146B is inserted through the divided portion 13B of the case 13. One end of the axle shaft 146B is connected to a drive roller (drive sprocket) 147B, which serves as a drive wheel for the crawler traveling device 2 (see FIG. 1). The other end of the axle shaft 146B is inserted into the final shaft 134B and splined to the final shaft 134B so that the final shaft 134B and the axle shaft 146B rotate integrally.

The power of the hydraulic motor of the HST24A (see FIG. 1) is transmitted from the motor output shaft 56A via the motor output gear 61A to the first intermediate gear 62A. When the shifter 91A is in the neutral position where it is spline-connected only to the second intermediate gear 63A, the first intermediate gear 62A rotates freely and no power is transmitted to the second intermediate gear 63A. When the shifter 91A is spline-connected to both the first intermediate gear 62A and the second intermediate gear 63A, the power of the first intermediate gear 62A is transmitted to the second intermediate gear 63A via the shifter 91A. The power transmitted to the second intermediate gear 63A is transmitted to the axle shaft 146A via the third intermediate gear 64A, the second intermediate shaft 104, the fourth intermediate gear 65A, the fifth intermediate gear 66A, the sixth intermediate gear 67A, the final gear 68A, and the final shaft 134A. This causes the drive roller 147A of the crawler traveling device 2 to rotate integrally with the axle shaft 146A.

The power of the hydraulic motor of the HST24B (see FIG. 1) is transmitted from the motor output shaft 56B to the first intermediate gear 62B via the motor output gear 61B. When the shifter 91B is in the neutral position where it is splined only to the first intermediate gear 62B, the first intermediate gear 62B and the first intermediate shaft 84 rotate freely and no power is transmitted to the second intermediate gear 63B. When the shifter 91A is splined to both the first intermediate gear 62B and the boss 89, the power of the first intermediate gear 62B is transmitted to the second intermediate gear 63B via the shifter 91A and the boss 89. The power transmitted to the second intermediate gear 63B is transmitted to the axle shaft 146B via the third intermediate gear 64B, the boss 105, the fourth intermediate gear 65B, the fifth intermediate gear 66B, the sixth intermediate gear 67B, the final gear 68B, and the final shaft 134B. This causes the drive roller 147B of the crawler traveling device 2 to rotate integrally with the axle shaft 146B.

<Parking brake>
Fig. 5 is a cross-sectional view showing the configuration of the parking brake 151. Fig. 6 is a perspective view of the parking brake 151.

The transmission 12 is equipped with a parking brake 151 to keep the combine 1 stationary.

As shown in FIG. 2B and FIG. 5, the parking brake 151 is provided inside the case 13 on the opposite side of the ball bearing 109 supporting the boss 105 from the ball bearing 108 supporting the second intermediate shaft 104. The parking brake 151 includes a shaft brake 152 that brakes/releases the second intermediate shaft 104, a boss brake 153 that brakes/releases the boss 105, and an operating member 154 that generates braking forces in the shaft brake 152 and the boss brake 153 to brake the second intermediate shaft 104 and the boss 105, respectively.

The end of the small diameter portion of the second intermediate shaft 104 protrudes outward from the boss 105 in the direction of the rotation axis, and the boss 155 is fitted onto the protruding portion so that it cannot rotate relative to the boss. The shaft brake 152 includes a plurality of annular brake discs 161 and a plurality of annular brake plates 162. The brake discs 161 are held at their inner peripheral ends by the boss 155 and are arranged at intervals in the direction of the rotation axis of the second intermediate shaft 104. The brake plates 162 are held at their outer peripheral ends by the case 13 and are arranged at intervals in the direction of the rotation axis of the second intermediate shaft 104. The brake discs 161 and the brake plates 162 are arranged so as to be alternately arranged in the direction of the rotation axis of the second intermediate shaft 104.

The boss brake 153 includes a plurality of annular brake discs 163 and a plurality of annular brake plates 164. The brake discs 163 are held by the boss 155 at their inner circumferential ends and are spaced apart in the direction of the rotation axis of the boss 105. The brake plates 164 are held by the case 13 at their outer circumferential ends and are spaced apart in the direction of the rotation axis of the boss 105. The brake discs 163 and the brake plates 164 are arranged alternately in the direction of the rotation axis of the boss 105.

The operating member 154 is provided on the opposite side of the boss brake 153 with respect to the shaft brake 152. The operating member 154 is formed in a substantially cylindrical shape centered on the common rotation axis of the second intermediate shaft 104 and the boss 105. The end face of the operating member 154 opposite the shaft brake 152 side faces the inner surface of the case 13, and a plurality of cam grooves 165 are formed at equal angular intervals on the end face, as shown in FIG. 6. The cam grooves 165 extend in the circumferential direction of the operating member 154, and the depth of the cam grooves 165 is shallower toward one side in the circumferential direction. Each cam groove 165 is provided with a spherical cam ball 166. On the other hand, on the inner surface of the case 13, as shown in FIG. 2 and FIG. 5, a substantially hemispherical holding portion 167 that receives the cam ball 166 and holds the cam ball 166 between the operating member 154 is formed as a recess recessed outward in a portion facing the operating member 154.

An operating mechanism 171 is provided on the portion of the case 13 facing the actuating member 154. The operating mechanism 171 includes an arm support shaft 172. The arm support shaft 172 is rotatably supported on the case 13 and is provided straddling the inside and outside of the case 13. One end of an operating arm 173 is connected to the portion of the arm support shaft 172 that protrudes outside the case 13. A columnar operating section 174 is provided on the portion of the arm support shaft 172 that is housed inside the case 13, offset from the center line of the arm support shaft 172. The tip of the operating section 174 is inserted into a notch 175 formed in the actuating member 154, as shown in FIG. 5.

In addition, a substantially cylindrical spacer 176 is provided between the brake plate 162 of the shaft brake 152 and the brake plate 164 of the boss brake 153.

A parking brake pedal is provided inside the cabin 4. The parking brake pedal and the operating arm 173 are mechanically connected via a rod or the like. When the parking brake pedal is depressed, the force is transmitted to the operating arm 173, which rotates around the arm support shaft 172 as a fulcrum. When the arm support shaft 172 rotates, the operating part 174 moves in the rotation direction, and the notch 175 is pressed by the operating part 174, causing the operating member 154 to rotate. At this time, the rotation direction of the operating member 154 is set in the direction in which the cam ball 166 moves to the shallow side within the cam groove 165. As the cam ball 166 moves to the shallow side within the cam groove 165, the operating member 154 moves to the side away from the inner surface of the case 13, that is, toward the shaft brake 152.

This movement causes the operating member 154 to press the brake plate 162 of the shaft brake 152, and the brake disc 161 and the brake plate 162 are pressed together, engaging the shaft brake 152. As a result, a braking force acts on the second intermediate shaft 104, and rotation of the second intermediate shaft 104 is prohibited. By prohibiting rotation of the second intermediate shaft 104, rotation of the fourth intermediate gear 65A, the fifth intermediate gear 66A, the sixth intermediate gear 67A, the final gear 68A, the axle shaft 146A, and the drive roller 147A of the crawler traveling device 2 is prohibited (blocked).

In addition, the pressing force of the operating member 154 pressing the brake plate 162 is transmitted to the brake plate 164 of the boss brake 153 via the spacer 176. As a result, the brake plate 164 of the boss brake 153 is pressed, the brake disc 163 and the brake plate 164 are pressed together, and the boss brake 152 is engaged. As a result, a braking force is applied to the boss 105, and the boss 105 is prohibited from rotating. By prohibiting the boss 105 from rotating, the fourth intermediate gear 65B, the third intermediate shaft 114, the fifth intermediate gear 66B, the sixth intermediate gear 67B, the final gear 68B, the axle shaft 146B, and the drive roller 147B of the crawler traveling device 2 are prohibited (blocked) from rotating.

By prohibiting the drive rollers 147A and 147B of the crawler travel device 2 from rotating, the combine harvester 1 is maintained in a stopped state.

When the parking brake pedal is released from the depressed state, the operating arm 173 rotates due to the elastic force of the coil spring inserted on the arm support shaft 172 outside the case 13, returning to the original non-operated state. As the operating arm 173 rotates, the operating member 154 rotates, and the cam ball 166 moves deeper inside the cam groove 165. The operating member 154 is biased by a spring (not shown) in the direction away from the shaft brake 152, and when the cam ball 166 moves deeper inside the cam groove 165, the operating member 154 moves away from the shaft brake 152. As a result, the pressure on the brake plate 162 by the operating member 154 is released, the shaft brake 152 and the boss brake 153 are released, and the second intermediate shaft 104 and the boss 105 return to a state in which no braking force is applied.

＜Effects＞
As described above, the second intermediate shaft 104 and the boss 105 are provided rotatably about a common rotation axis. The second intermediate shaft 104 and the boss 105 are rotatable relative to each other. In addition, a shaft brake 152 and a boss brake 153 are provided for braking/releasing the second intermediate shaft 104 and the boss 105, respectively. One operating member 154 is provided for the shaft brake 152 and the boss brake 153, and by operation of the one operating member 154, a braking force for braking the second intermediate shaft 104 is generated in the shaft brake 152, and a braking force for braking the boss 105 is generated in the boss brake 153. Thus, the second intermediate shaft 104 and the boss 105, which are rotatable relative to each other, can be braked with a simple configuration.

The second intermediate shaft 104 is formed in an axial shape, and the boss 105 is formed in a cylindrical shape and is inserted onto the second intermediate shaft 104. The boss 105 is moved toward one end of the second intermediate shaft 104, and the shaft brake 152 and the boss brake 153 are provided together on that end. This makes it possible to reduce the amount of maintenance work required for the shaft brake 152 and the boss brake 153.

As is clear from the above description and FIG. 2C, the assembly formed by assembling the sixth intermediate gears 67A, 67B and the needle bearings 116, 117 to the third intermediate shaft 114 has an asymmetric internal structure and a symmetric external shape. By making the internal structure of the assembly asymmetric, it is possible to create a difference in durability between the left and right sides of the assembly. On the other hand, by making the external shape of the assembly symmetric, the assembly can be installed in the transmission 12 with the left and right sides reversed.

That is, the sixth intermediate gear 67A is mounted on the third intermediate shaft 114 via needle bearings 116 and 117, and is arranged to be rotatable around the central axis of the third intermediate shaft 114. On the other hand, the sixth intermediate gear 67B is fitted onto the third intermediate shaft 114 and spline-coupled to the third intermediate shaft 114. This makes the durability (strength) of the sixth intermediate gear 67B side higher than that of the sixth intermediate gear 67A side.

On the other hand, the external shape of the assembly is formed symmetrically, and the shapes of the ends 121A and 121B of the third intermediate shaft 114 are identical. Therefore, it is possible to adopt a configuration in which the end 121A is supported by the divided part 13A of the case 13 via a ball bearing 122A, and the end 121B is supported by the divided part 13B of the case 13 via a ball bearing 122B, or a configuration in which the left and right of the assembly are reversed, and the end 121A is supported by the divided part 13B via a ball bearing 122B, and the end 121B is supported by the divided part 13A via a ball bearing 122A.

Therefore, by installing the assembly formed by assembling the sixth intermediate gears 67A, 67B and the needle bearings 116, 117 to the third intermediate shaft 114 in the transmission 12 in a left-right inverted manner according to the mounting position of the transmission 12 in the combine harvester 1, the side of the assembly with relatively high durability can be positioned on the outside of the left turning of the combine harvester 1. As a result, even if the mounting mode of the transmission 12 on the combine harvester 1 is changed, the left-right balance of the durability of the rotating body structure including the assembly can be appropriately maintained.

In addition, in the configuration shown in FIG. 2C, the internal structure of the assembly formed by assembling the final shafts 134A, 134B and the needle bearings 142, 143 is asymmetrical, and the external shape is symmetrical.

That is, the insertion portion 136 of the final shaft 134B is inserted into the final shaft 134A, and needle bearings 142, 143 are interposed between the inner peripheral surface of the final shaft 134A and the outer peripheral surface of the insertion portion 136.

On the other hand, the external shape of the assembly formed by assembling the final shafts 134A, 134B and the needle bearings 142, 143 is formed symmetrically. Therefore, it is possible to adopt a configuration in which the final shaft 134A is supported by the divided part 13A of the case 13 via the ball bearing 144, and the final shaft 134B is supported by the divided part 13B of the case 13 via the ball bearing 145, or a configuration in which the left and right of the assembly are reversed, and the final shaft 134A is supported by the divided part 13B via the ball bearing 145, and the final shaft 134B is supported by the divided part 13A via the ball bearing 144.

Therefore, by installing the assembly formed by assembling the final shafts 134A, 134B and the needle bearings 142, 143 in the transmission 12 in a left-right inverted manner according to the mounting position of the transmission 12 in the combine harvester 1, the side of the assembly with relatively high durability can be positioned on the outside of the left turning of the combine harvester 1. As a result, even if the mounting mode of the transmission 12 on the combine harvester 1 is changed, the left-right balance of the durability of the rotating body structure including the assembly can be appropriately maintained.

As a result, the transmission 12 can be installed in a variety of combine harvesters 1, making the transmission 12 versatile. As a result, the cost of the combine harvester 1 can be reduced.

<Modification>
Although the embodiment of the present invention has been described above, the present invention can be embodied in other forms.

For example, the sixth intermediate gear 67A is mounted to the third intermediate shaft 114 via needle bearings 116 and 117, but the sixth intermediate gear 67A may also be mounted to the third intermediate shaft 114 via a bush.

Although a combine harvester 1 equipped with a harvesting device 7 and a threshing device as working devices has been given as an example of a work vehicle, the present invention can be applied to various work vehicles, such as a harvester equipped with a harvesting and transporting device as a working device for harvesting and transporting vegetables such as carrots, radishes, green soybeans, and cabbage, a rice transplanter equipped with a seedling planting device as a working device, a direct seeding machine equipped with a sowing device as a working device, a tractor equipped with a plow as a working device, and a construction work vehicle equipped with a bucket as a working device.

Furthermore, the present invention is not limited to work vehicles that use crawler travelling devices 2, but can also be applied to work vehicles that use wheels.

In addition, various design modifications may be made to the above-mentioned configuration within the scope of the claims.

1. Combine (work vehicle)
2: Crawler travelling device 11: Engine 12: Transmission 13: Case 104: Second intermediate shaft (first rotating shaft)
105: Boss (second rotation axis)
152: Shaft brake (first brake)
153: Boss brake (second brake)
154: Operating member 161: Brake disc (first brake disc)
162: Brake plate (first brake plate)
163: Brake disc (second brake disc)
164: Brake plate (second brake plate)

Claims (6)

A transmission mounted on a work vehicle and transmitting power to a pair of left and right traveling devices for traveling the work vehicle,
A first rotation shaft that is rotatably provided around a rotation axis that extends in a predetermined direction;
a second rotation shaft provided to be rotatable about the rotation axis common to the first rotation shaft and to be rotatable relative to the first rotation shaft;
a first brake for braking/releasing the first rotating shaft;
a second brake for braking/releasing the second rotating shaft;
an actuating member that, when actuated, causes the first brake to generate a braking force for braking the first rotating shaft and causes the second brake to generate a braking force for braking the second rotating shaft,
The first rotation shaft is formed in a shaft shape,
The second rotating shaft is formed in a cylindrical shape and is fitted onto the first rotating shaft . a case forming an outer shell;
The first brake has a configuration in which a first brake disk fixedly provided with respect to the first rotating shaft and a first brake plate fixedly provided with respect to the case are alternately arranged in the direction of the rotation axis,
The second brake has a configuration in which a second brake disc fixed to the second rotation shaft and a second brake plate fixed to the case are alternately arranged in the direction of the rotation axis,
2. The transmission of claim 1, wherein the actuating member generates a braking force in the first brake by pressing the first brake disc and the first brake plate together in the direction of the rotation axis, and generates a braking force in the second brake by pressing the second brake disc and the second brake plate together in the direction of the rotation axis. The first brake disc and the first brake plate are disposed adjacent to one side of the second brake disc and the second brake plate in the direction of the rotation axis,
3. The transmission according to claim 2, wherein the actuating member presses the first brake plate from the one side when actuated, and the pressing force brings the first brake disc and the first brake plate into pressure contact, and brings the second brake disc and the second brake plate into pressure contact. Further including a hydrostatic continuously variable transmission provided independently on the left and right sides corresponding to each of the traveling devices,
The transmission according to any one of claims 1 to 3, wherein power output from the left and right hydrostatic continuously variable transmissions is transmitted to the left and right traveling devices, respectively. The second rotating shaft is moved toward one end side of the first rotating shaft,
5. The transmission according to claim 1, wherein the first brake and the second brake are collectively provided on the one end side . The engine,
A pair of left and right running devices;
A transmission that transmits the power of the engine to the left and right traveling devices independently,
A work vehicle employing the transmission according to any one of claims 1 to 5 as the transmission.

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