Work vehicle

Abstract

To provide a work vehicle with a hybrid transmission that shifts power from an engine to output to a front traveling unit which can extend forward, while unnecessitating shape change of a transmission case and preventing circulation of lubricant between an electrically-driven transmission chamber and a gearwheel transmission chamber, a front transmission shaft from the gearwheel transmission part.SOLUTION: A work vehicle comprises: an electrically-driven transmission chamber 16; a transmission case 11 which forms a gearwheel transmission chamber 17 positioned at the rear side of the electrically-driven transmission chamber 16 and is to be a partition between the gearwheel transmission chamber 17 and the electrically-driven transmission chamber 16; a front transmission shaft 70 which extends forward from the gearwheel transmission part to perform power transmission to a front traveling device; and a cylindrical member 73 which is arranged in the transmission case 11 to form a power transmission path 74 separated from the electrically-driven transmission chamber 16 passing through the electrically-driven transmission chamber 16 in a cross direction in which the front transmission shaft 70 passes through the power transmission path 74.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a work vehicle equipped with a hybrid transmission. [Background technology]

[0002] As shown in Patent Document 1, there is a work vehicle (tractor) that includes a hybrid transmission that has an engine, an electric transmission unit having a motor generator, and a geared transmission unit having a gear transmission mechanism without a motor generator, and that changes the speed of power from the engine and outputs it to a front traveling device; a transmission case that forms an electric transmission chamber and a geared transmission chamber with the geared transmission chamber accommodating the gear transmission mechanism being located rearward of the electric transmission chamber accommodating the electric transmission unit, and that separates the geared transmission chamber from the electric transmission chamber; and a front transmission shaft (rotating shaft) that extends forward from the geared transmission unit and transmits power to the front traveling device (front wheels). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-132979 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned work vehicle, by separating the electric transmission chamber and the gear transmission chamber, it is possible to store different types of lubricating oil in the electric transmission chamber and the gear transmission chamber, for example, by storing lubricating oil suitable for cooling the motor generator in the electric transmission chamber and lubricating oil suitable for lubricating the gear transmission mechanism in the gear transmission chamber. In such a work vehicle, if the front transmission shaft is positioned so that it extends toward the front of the vehicle outside the electric transmission compartment, the front transmission shaft will not affect the partition between the electric transmission compartment and the gear transmission compartment.However, in this case, in order to provide a power transmission path through which the front transmission shaft passes outside the transmission case, it is necessary to change the shape of the transmission case, such as by reducing the outer diameter of the part of the transmission case that forms the electric transmission compartment. If the front transmission shaft is positioned so that it extends forward through the electric transmission chamber, there is no need to modify the shape of the transmission case. However, in this case, the front transmission shaft passes through a partition wall provided in the transmission case to separate the electric transmission chamber and the gear transmission chamber. Although an oil seal is interposed between the partition wall and the front transmission shaft to prevent the flow of lubricating oil between the electric transmission chamber and the gear transmission chamber, the characteristics of the oil seal make it difficult to completely prevent the flow of lubricating oil.

[0005] The present invention provides a work vehicle that can extend the front transmission shaft forward from the gear transmission mechanism while eliminating the need to change the shape of the transmission case and preventing the flow of lubricating oil between the electric transmission chamber and the gear transmission chamber. [Means for solving the problem]

[0006] The work vehicle according to the present invention comprises: The hybrid transmission has an engine, an electric transmission unit having a motor generator, and a gear transmission unit having a gear transmission mechanism without a motor generator, and changes the speed of power from the engine and outputs it toward a front traveling device, a transmission case that forms the electric transmission chamber and the gear transmission chamber with the gear transmission chamber that houses the gear transmission unit being located rearward of the electric transmission chamber that houses the electric transmission unit, and separates the gear transmission chamber from the electric transmission chamber, and a front transmission shaft that extends forward from the gear transmission unit and transmits power to the front traveling device, and the transmission case is provided with a tubular member that forms a power transmission path that passes through the electric transmission chamber in the fore-and-aft direction, separating it from the electric transmission chamber, and the front transmission shaft passes through the power transmission path.

[0007] According to this configuration, the front transmission shaft passes through a power transmission path that passes through the electric transmission chamber, eliminating the need to provide a power transmission path outside the transmission case and the need to modify the shape of the transmission case. Because the power transmission path is formed while being separated from the electric transmission chamber by the tubular member, the tubular member prevents direct communication between the electric transmission chamber and the gear transmission chamber, and communication between the electric transmission chamber and the gear transmission chamber via the power transmission path, thereby preventing the flow of lubricating oil between the electric transmission chamber and the gear transmission chamber. In other words, the front transmission shaft can be extended forward from the gear transmission mechanism while eliminating the need to modify the shape of the transmission case and preventing the flow of lubricating oil between the electric transmission chamber and the gear transmission chamber.

[0008] In the present invention, It is preferable that a partition wall separating the electric transmission chamber and the gear transmission chamber is provided with a rear support hole into which the rear portion of the tubular member is inserted for support, and that an O-ring is interposed between the tubular member and the partition wall in the rear support hole.

[0009] According to this configuration, the gap between the cylindrical member and the partition wall is sealed by the O-ring, so that it is possible to prevent the lubricating oil from flowing between the electric transmission chamber and the gear transmission chamber through the rear support hole.

[0010] In the present invention, It is preferable that a wall portion of the transmission case that forms the electric transmission chamber is provided with a front support hole into which the front portion of the tubular member is inserted to support it, and that an O-ring is interposed between the tubular member and the wall portion in the front support hole.

[0011] According to this configuration, the gap between the cylindrical member and the wall portion is sealed by the O-ring, so that leakage of lubricating oil from the electric transmission chamber through the front support hole can be prevented.

[0012] In the present invention, It is preferable that the front transmission shaft is supported by the transmission case via bearings at a rear portion located rearward of the tubular member and at a front portion located forward of the tubular member.

[0013] With this configuration, compared to when a bearing is provided between the front transmission shaft and the tubular member, the outer diameter of the tubular member can be made smaller while maintaining the required outer diameter of the front transmission shaft.By reducing the outer diameter of the tubular member, the volume required to install the tubular member in the electric transmission chamber can be reduced. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 2 is a side view of the entire tractor as seen from the left side. [Figure 2] FIG. 2 is a schematic diagram of power transmission to a front traveling device and a rear traveling device. [Figure 3] FIG. 4 is a cross-sectional view showing the arrangement of a first front transmission shaft. DETAILED DESCRIPTION OF THE INVENTION

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described with reference to the accompanying drawings. In the following explanation, with respect to the running body of a tractor (an example of a "work vehicle"), the direction of arrow F shown in Figure 1 is referred to as the "forward direction of the body," the direction of arrow B as the "rearward direction of the body," the direction of arrow U as the "upward direction of the body," the direction of arrow D as the "downward direction of the body," the direction toward the front of the page in Figure 1 as the "leftward direction of the body," and the direction toward the back of the page in Figure 1 as the "rightward direction of the body."

[0016] [Overall configuration of the tractor] As shown in FIG. 1 , the tractor includes a traveling body 4 having a body frame 1, a pair of left and right front traveling units 2 steerably and drivably mounted on the front of the body frame 1, and a pair of left and right rear traveling units 3 drivably mounted on the rear of the body frame 1. In this embodiment, the front traveling units 2 are front tires and wheels, and the rear traveling units 3 are rear tires and wheels. Mini crawler traveling units can be used instead of the tires and wheels. A driving unit 6 having an engine 5 is mounted on the front of the traveling body 4. A driver's seat 7 and a driver's unit 9 having a steering wheel 8 for steering the front traveling units 2 are mounted on the rear of the traveling body 4. The driver's unit 9 is equipped with a cabin 10 that covers the passenger space. A link mechanism (not shown) that connects a work implement such as a rotary tiller (not shown) so that it can be raised and lowered, and a power take-off shaft 44 that extracts and transmits power from the engine 5 to the connected work implement are mounted on the rear of the traveling body 4. The body frame 1 is made up of an engine 5, a transmission case 11 connected to the rear of the engine 5, and a front frame 12 connected to the lower part of the engine 5.

[0017] 2, the transmission case 11 extends rearward from the rear of the engine 5 in the longitudinal direction of the vehicle body. A hybrid transmission 13 is housed in the transmission case 11, and power from the engine 5 is shifted by the hybrid transmission 13 and output from the hybrid transmission 13 to the front traveling device 2 and the rear traveling device 3.

[0018] [Hybrid Transmission] As shown in FIG. 2, the hybrid transmission 13 includes an electric transmission section 13A and a gear transmission section 13B located rearward of the electric transmission section 13A.

[0019] As shown in Fig. 2, the electric transmission section 13A is housed in an electric transmission chamber 16 formed in the front part 11a of the transmission case 11. The gear transmission section 13B is housed in a gear transmission chamber 17 formed in the rear part 11b of the transmission case 11. The electric transmission chamber 16 is formed by a peripheral wall portion located in the front part 11a of the transmission case 11 and a partition wall 15 provided inside the transmission case 11. The gear transmission chamber 17 is formed by a peripheral wall portion located in the rear part 11b of the transmission case 11 and the partition wall 15. The gear transmission chamber 17 is formed to be located rearward of the electric transmission chamber 16. The electric transmission chamber 16 and the gear transmission chamber 17 are separated by the partition wall 15. The electric transmission chamber 16 stores lubricating oil suitable for cooling the motor generators 21 and 22, and the gear transmission chamber 17 stores lubricating oil suitable for lubricating the gear transmission mechanism 14, making it possible to store different types of lubricating oil in the electric transmission chamber 16 and the gear transmission chamber 17.

[0020] [Electric Transmission] 2, the electric transmission unit 13A has two motor generators 21 and 22. A first motor generator 21, which is one of the two motor generators 21 and 22, is connected to a battery 35 via a first inverter 36. A second motor generator 22, which is the other of the two motor generators 21 and 22, is connected to the battery 35 via a second inverter 34.

[0021] [Gear Transmission Section] 2, the gear transmission unit 13B does not have a motor generator but has a gear transmission mechanism 14. The gear transmission mechanism 14 is provided with two planetary gear transmission units 23, 24, a forward / reverse switching device 27, an auxiliary transmission device 28, and a front transmission device 30.

[0022] [Planetary gear transmission section] One planetary gear transmission unit 23 of the two planetary gear transmission units 23, 24 includes a sun gear 23a, a planet gear 23b, a carrier 23c, and an internal gear 23d. A first input gear 23f connected to the sun gear 23a is connected to a rotor gear 22b of the second motor generator 22 via a transmission gear 49, a transmission shaft 19, and a transmission gear 32. The rotor gear 22b is provided on the rotor shaft 22a of the second motor generator 22. A second input gear 23e connected to the internal gear 23d is connected to the input shaft 18 via a transmission gear 48 and a center shaft 45. The input shaft 18 is an input shaft of the hybrid transmission 13, and is connected to the output shaft 5a of the engine 5.

[0023] One of the planetary gear transmission units 23 is a low-speed planetary gear transmission unit, in which the sun gear 23a is driven by the output of the second motor generator 22 and the internal gear 23d is driven by the output of the engine 5, and the outputs of the second motor generator 22 and the engine 5 are combined and the combined power is transmitted from the carrier 23c to the low-speed output clutch 25.

[0024] The other planetary gear transmission unit 24 of the two planetary gear transmission units 23, 24 includes a sun gear 24a, planet gears 24b, a carrier 24c, and an internal gear 24d. A first input gear 24f connected to the sun gear 24a is connected to the rotor gear 22b of the second motor generator 22 via a transmission gear 49, a transmission shaft 19, and a transmission gear 32. A second input gear 24e connected to the carrier 24c is connected to the input shaft 18 via a transmission gear 48 and a center shaft 45.

[0025] The other planetary gear transmission unit 24 is a high-speed planetary gear transmission unit, in which the sun gear 24a is driven by the output of the second motor generator 22 and the carrier 24c is driven by the output of the engine 5, the outputs of the second motor generator 22 and the engine 5 are combined, and a combined power that is faster than the combined power of the planetary gear transmission unit 23 is transmitted from the internal gear 24d to the high-speed output clutch 26.

[0026] As shown in FIG. 2 , the rotor shaft 21a of the first motor generator 21 and the input shaft 18 of the hybrid transmission 13 are connected via a rotor shaft gear 21b and a transmission gear 31. When power from the engine 5 is changed in speed by the second motor generator 22 and the gear transmission mechanism 14 and output from the gear transmission mechanism 14 to the front traveling device 2 and the rear traveling device 3 to drive the front traveling device 2 and the rear traveling device 3, the first motor generator 21 is driven by the power from the engine 5 to generate electricity. However, in the planetary gear transmission unit 23, the internal gear 23d can also be driven by the output of the first motor generator 21, and in the planetary gear transmission unit 24, the carrier 24c can also be driven by the output of the first motor generator 21. In other words, the first motor generator 21 mainly functions as a generator, but can also function as an electric motor that drives the front traveling device 2 and the rear traveling device 3. The second motor generator 22 mainly functions as an electric motor that drives the front traveling device 2 and the rear traveling device 3, but also functions as a generator during deceleration.

[0027] [Forward / reverse switching device] 2, the forward / reverse switching device 27 includes an input shaft 50 and an output shaft 53 positioned parallel to the input shaft 50. A forward clutch 51 and a reverse clutch 52 are provided on the input shaft 50. A forward transmission gear mechanism 53a is provided between the forward clutch 51 and the output shaft 53, and a reverse transmission gear mechanism 53b is provided between the reverse clutch 52 and the output shaft 53. A reverse gear 54 is provided on the reverse transmission gear mechanism 53b.

[0028] In the forward / reverse switching device 27, the low-speed resultant power is input from the output gear 25a of the low-speed output clutch 25 to the input shaft 50 via the transmission gear 55, and the high-speed resultant power is input from the output gear 26a of the high-speed output clutch 26 to the input shaft 50 via the transmission gear 55. The forward clutch 51 is engaged to switch to a forward state. When switched to the forward state, the power of the input shaft 50 is converted into forward power by the forward clutch 51 and the forward transmission gear mechanism 53a and transmitted to the output shaft 53. The reverse clutch 52 is engaged to switch to a reverse state. When switched to the reverse state, the power of the input shaft 50 is converted into reverse power by the reverse clutch 52 and the reverse transmission gear mechanism 53b and transmitted to the output shaft 53.

[0029] [Sub-transmission device] 2, the auxiliary transmission 28 includes an input gear 56 provided at the end of the output shaft 53 of the forward / reverse switching device 27, and an auxiliary transmission output shaft 59 located on the same axis as the output shaft 53 of the forward / reverse switching device 27. A low-speed transmission gear mechanism 58 is provided between the input gear 56 and the auxiliary transmission output shaft 59. The low-speed transmission gear mechanism 58 includes a transmission gear 57 supported on the auxiliary transmission output shaft 59 so as to be rotatable relative to the input gear 56. A clutch gear 60 is provided between the transmission gear 57 and the input gear 56.

[0030] The sub-transmission device 28 is switched to a high-speed state by shifting the clutch gear 60 to the high-speed side. When switched to the high-speed state, the input gear 56 and the sub-transmission output shaft 59 are connected by the clutch gear 60, and the power transmitted from the forward / reverse switching device 27 to the input gear 56 is transmitted to the sub-transmission output shaft 59 via the clutch gear 60 as high-speed side power. When switched to the low-speed state, the clutch gear 60 is switched to a low-speed state. When switched to the low-speed state, the transmission gear 57 and the sub-transmission output shaft 59 are connected by the clutch gear 60, and the power transmitted from the forward / reverse switching device 27 to the input gear 56 is transmitted to the sub-transmission output shaft 59 via the low-speed transmission gear mechanism 58 and the clutch gear 60 as low-speed side power.

[0031] The power of the sub-transmission output shaft 59 is transmitted from the sub-transmission output shaft 59 to the rear differential mechanism 29. The power of the sub-transmission output shaft 59 is transmitted to the input shaft 63 of the front transmission 30 via a gear transmission mechanism 63a.

[0032] [Front transmission] 2, the front transmission device 30 includes an input shaft 63 connected to the sub-transmission output shaft 59 via a gear transmission mechanism 63a, and an output shaft 64 positioned parallel to the input shaft 63. A constant speed clutch 61 and an increasing speed clutch 62 are provided on the input shaft 63. A constant speed transmission gear mechanism 64a is provided between the constant speed clutch 61 and the output shaft 64, and a increasing speed transmission gear mechanism 64b is provided between the increasing speed clutch 62 and the output shaft 64.

[0033] In the front transmission 30, when the constant speed clutch 61 is engaged, the transmission is switched to constant speed transmission. When switched to constant speed transmission, the power transmitted from the auxiliary transmission 28 to the input shaft 63 is transmitted to the output shaft 64 via the constant speed clutch 61 and the constant speed transmission gear mechanism 64a and is output from the output shaft 64 toward the front traveling device 2. The output in this case is power that makes the peripheral speed of the front traveling device 2 the same as the peripheral speed of the rear traveling device 3. When the speed-up clutch 62 is engaged, the transmission is switched to an accelerating state. When switched to the speed-up state, the power transmitted from the auxiliary transmission 28 to the input shaft 63 is transmitted to the output shaft 64 via the speed-up clutch 62 and the speed-up transmission gear mechanism 64b and is output from the output shaft 64 toward the front traveling device 2. The output in this case is power that makes the peripheral speed of the front traveling device 2 faster than the peripheral speed of the rear traveling device 3.

[0034] [Front transmission shaft] As shown in Figure 2, a first front transmission shaft 70 extending forward from the gear transmission section 13B is provided in the transmission case 11, and the first front transmission shaft 70 and the input shaft 20a of the front differential mechanism 20 are connected by a second front transmission shaft 71 located outside the transmission case 11, and the power output by the gear transmission section 13B toward the front traveling device 2 is transmitted to the front differential mechanism 20 by the first front transmission shaft 70 and the second front transmission shaft 71.

[0035] 3, the first front transmission shaft 70 is made up of the output shaft 64 of the front transmission device 30 and an extended output shaft 64c connected to the output shaft 64 by a connecting member 72. A rear portion 70R of the first front transmission shaft 70 is formed by the output shaft 64.

[0036] 3, a tubular member 73 that passes through the electric transmission chamber 16 in the front-rear direction is provided in the transmission case 11, and a power transmission path 74 that is separated from the electric transmission chamber 16 is formed by the tubular member 73. In this embodiment, the tubular member 73 is a tubular member that has a circular cross section and is made of metal. The tubular member 73 may have a non-circular cross section, such as a hexagonal or rectangular shape. The tubular member 73 may also be made of a non-metallic material, such as resin.

[0037] 3, a partition wall 15 provided in the transmission case 11 is provided with a rear support hole 15a penetrating the partition wall 15 in the front-to-rear direction, and a rear portion 73r of the tubular member 73 is inserted into the rear support hole 15a, thereby supporting the rear portion 73r by the partition wall 15. A wall portion 11c of the transmission case 11 that forms the electric transmission chamber 16 is provided with a front support hole 11d penetrating the wall portion 11c in the front-to-rear direction, and a front portion 73f of the tubular member 73 is inserted into the front support hole 11d, thereby supporting the front portion 73f by the wall portion 11c. As a result, the tubular member 73 forms a power transmission path 74 that is separated from the electric transmission chamber 16. Furthermore, the electric transmission chamber 16 and the gear transmission chamber 17 are separated by the tubular member 73.

[0038] As shown in Figure 3, the first front transmission shaft 70 is arranged to pass from the gear transmission chamber 17 through the rear support hole 15a into the power transmission path 74, pass through the power transmission path 74 and exit forward from the front support hole 11d to the outside of the transmission case 11 and connect to the second front transmission shaft 71.

[0039] 3, in the rear support hole 15a, a sealing O-ring 75 is interposed between the cylindrical member 73 and the partition wall 15. In the front support hole 11d, a sealing O-ring 75 is interposed between the cylindrical member 73 and the wall portion 11c.

[0040] 3, a bearing 76 is provided between a front portion 70a of the first front transmission shaft 70 located forward of the cylindrical member 73 and a wall portion 11c of the transmission case 11. The bearing 76 is provided between a rear portion 70b of the first front transmission shaft 70 located rearward of the cylindrical member 73 and a support portion 11e provided on the transmission case 11. The first front transmission shaft 70 is supported by the transmission case 11 via the bearings 76 at the front portion 70a located forward of the cylindrical member 73 and the rear portion 70b located rearward of the cylindrical member 73.

[0041] [Work power transmission device] As shown in Fig. 1, a power take-off shaft 44 that takes power from the engine 5 and transmits it to a connected working device is provided at the rear of the transmission case 11. As shown in Fig. 2, the power of the output shaft 5a of the engine 5 is configured to be transmitted to the power take-off shaft 44 via the input shaft 18, a center shaft 45, a work clutch 46, and a work transmission 47.

[0042] [Another embodiment] (1) In the above embodiment, an example in which two motor generators 21 and 22 are provided is shown, but only one motor generator or three or more motor generators may be provided.

[0043] (2) In the above embodiment, the gear transmission mechanism 14 includes two planetary gear transmission units 23, 24. However, the gear transmission mechanism 14 may include only one planetary gear transmission unit or three or more planetary gear transmission units. Also, the gear transmission mechanism 14 may not include a planetary gear transmission unit.

[0044] (3) In the above embodiment, an example in which the O-ring 75 is provided is shown, but the O-ring 75 may not be provided.

[0045] (4) In the above embodiment, an example is shown in which bearings 76 are provided in the front portion 70a and the rear portion 70b of the first front transmission shaft 70, but this is not limited to this. It is also possible to provide bearings between the tubular member 73 and the first front transmission shaft 70 without providing bearings 76 in the front portion 70a and the rear portion 70b. [Industrial Applicability]

[0046] The present invention can be applied to a work vehicle equipped with a hybrid transmission having an electric transmission section and a gear transmission section. [Explanation of symbols]

[0047] 2 Front running gear 5 Engine 11 Mission case 11c wall 11d Front support hole 13b Blocking wall 13 Hybrid Transmission 13A Electric Transmission 13B Gear transmission section 14 Gear transmission mechanism 15 Partition Wall 15a Rear support hole 16 Electric Transmission Section 17 Gear Transmission Section 21 Motor generator 22 Motor generator 70 First front transmission shaft (front transmission shaft) 70a Anterior part 70b Posterior part 73 Cylinder member 73r rear 73f front 75 O-rings 76 Bearings

Claims

1. The engine and a hybrid transmission that includes an electric transmission unit having a motor generator and a gear transmission unit having a gear transmission mechanism without a motor generator, and that changes the speed of power from the engine and outputs it to a front traveling device; a transmission case that defines the electric transmission chamber and the gear transmission chamber with the gear transmission chamber accommodating the gear transmission section positioned rearward relative to the electric transmission chamber accommodating the electric transmission section, and that separates the gear transmission chamber from the electric transmission chamber; a front transmission shaft extending forward from the gear transmission unit and transmitting power to the front traveling device; a cylindrical member that forms a power transmission path that passes through the electric transmission chamber in a front-rear direction while separating the electric transmission chamber from the power transmission case; A work vehicle in which the front transmission shaft passes through the power transmission path.

2. a partition wall separating the electric transmission chamber from the gear transmission chamber is provided with a rear support hole into which a rear portion of the cylindrical member is inserted for support; 2. A work vehicle according to claim 1, wherein an O-ring is interposed between the cylindrical member and the partition wall in the rear support hole.

3. a wall portion of the transmission case that forms the electric transmission chamber is provided with a front support hole into which a front portion of the cylindrical member is inserted to support the front portion; 2. The work vehicle according to claim 1, wherein an O-ring is interposed between the cylindrical member and the wall portion in the front support hole.

4. 2. The work vehicle according to claim 1, wherein the front transmission shaft is supported by the transmission case via bearings at a rear portion located rearward of the tubular member and at a front portion located forward of the tubular member.

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