JP2021054392A - Travel transmission device of tractor - Google Patents

Abstract

To provide a travel transmission device of a tractor which can obtain a tractor capable of driving wheels at a speed and torque suitable for work.SOLUTION: A travel transmission device comprises a change gear 18, a forward/backward switching device 19 for converting the output of the change gear 18 into forward power and backward power, a rear wheel differential mechanism 20 for inputting the output of the forward/backward switching device 19 to transmit it to the rear wheel 7, and a gear transmission mechanism 95 for transmitting power of an output shaft 91 of the forward/backward switching device 19 to an input shaft 20a of the rear wheel differential mechanism 20. A transmission case 3 is configured to be divisible into a front case part 3A accommodating the change gear 18 and a rear case part 3B accommodating the forward/backward switching device 19, the rear wheel differential mechanism 20, and the gear transmission mechanism 95. The gear transmission mechanism 95 is detachably provided in a portion of the inside of the transmission case 3, which corresponds to a front end portion 3C of the rear case part 3B.SELECTED DRAWING: Figure 2

Description

The present invention relates to a traveling transmission device for a tractor.

The traveling transmission device of the tractor includes a transmission that shifts and outputs the power from the engine, a forward / backward switching device that is provided behind the transmission and converts the output of the transmission into forward power and reverse power. A rear wheel differential mechanism that is provided behind the transmission and transmits the output of the forward / backward switching device to the rear wheels, and a mission case that houses the transmission, the forward / backward switching device, and the rear wheel differential mechanism. Is provided, and there is a device that enables forward traveling or reverse traveling at a traveling speed set by the transmission, simply by switching the forward / backward switching device. As a traveling transmission device of this type of tractor, for example, there is one shown in Patent Document 1. In the one shown in Patent Document 1, a speed change transmission device as a speed change device is provided.

In addition, the traveling transmission device of the tractor is provided in a mission case in which the power from the engine is input by the input shaft and inside the mission case, the power from the input shaft is input and the input power is changed. It is equipped with a speed change transmission unit that outputs power, and a rear wheel differential mechanism that is provided inside the mission case, in which the power output by the speed change transmission unit is input and the input power is transmitted to the left and right rear wheels. There is. The traveling transmission device of this type of tractor is provided with a transmission transmission unit having a plurality of transmission units in which the power from the input shaft is changed by a gear interlocking mechanism and a multi-plate clutch and output in the front-rear direction of the transmission case. There is something that has been done.
As a traveling transmission device of this type of tractor, for example, there is a speed change transmission device of a tractor shown in Patent Document 1. The shift transmission device of the tractor shown in Patent Document 1 includes a shift output unit as a shift transmission unit and a forward / reverse advance switching device. The speed change output unit is provided with an input gear and a speed change gear as a gear interlocking mechanism, and is provided with a step division clutch as a multi-plate clutch. The forward / backward switching device is provided with a gear interlocking mechanism provided over the input shaft and the output shaft, and a forward clutch and a reverse clutch as multi-plate clutches.

JP-A-2019-95058

Since a tractor is connected to various work devices such as a fertilizer spreader, a rotary tiller, a plow, and a dozer, there is a demand for a tractor that can drive wheels at a speed and torque suitable for the work.

In the traveling transmission device of a tractor equipped with the above-mentioned speed change transmission unit, when the multi-plate clutch enters the lubricating oil stored in the mission case, the multi-plate clutch rotates while receiving the rotational resistance due to the lubricating oil and the transmission loss. Will increase. If the multi-plate clutch is prevented from entering the lubricating oil or does not enter too much so as to suppress the increase in transmission loss, the gear interlocking mechanism in the transmission also does not enter the lubricating oil or does not enter too much, and the gear interlocking. The mechanism becomes short of lubricating oil.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to avoid an increase in transmission loss due to rotational resistance of a tractor traveling transmission device or a multi-plate clutch that can meet a demand at low cost due to lubricating oil, and sufficiently lubricate the gear interlocking mechanism. Provide a traveling transmission device for a tractor that can be supplied.

The traveling transmission device for a tractor according to the present invention is
A transmission that shifts and outputs the power from the engine, a forward / backward switching device that is provided behind the transmission and converts the output of the transmission into forward power and reverse power, and behind the transmission. A rear wheel differential mechanism that inputs the output of the forward / backward switching device and transmits it to the rear wheels, and a gear that transmits the power of the output shaft of the forward / backward switching device to the input shaft of the rear wheel differential mechanism. A transmission mechanism, a transmission, a forward / backward switching device, a rear wheel differential mechanism, and a transmission case accommodating the gear transmission mechanism are provided, and the transmission case is a front case portion accommodating the transmission. And the rear wheel transmission mechanism, the rear wheel differential mechanism, and the rear case portion accommodating the gear transmission mechanism. The gear transmission mechanism is included in the inside of the transmission case. It is detachably provided at a portion corresponding to the front end portion of the rear case portion.

According to this configuration, by changing the gear ratio of the gear transmission mechanism, the maximum driveable speed of the rear wheels can be increased, and the rear wheels can be driven with high torque. When the front case and rear case are separated, you can select from multiple gear transmission mechanisms with different gear ratios while keeping the transmission, forward / backward switching device, and rear wheel differential mechanism assembled. Since the gear transmission mechanism can be assembled from the front of the rear case, a tractor capable of driving the rear wheels at a speed and torque corresponding to various operations can be obtained at low cost.

In the present invention
A front wheel transmission mechanism provided inside the mission case and outputting power from the forward / backward switching device toward the front wheels, and a portion of the inside of the mission case corresponding to the front end portion of the rear case portion. It is preferable that a second gear transmission mechanism, which is detachably provided and inputs power from the forward / backward switching device to the front wheel transmission mechanism, is provided.

According to this configuration, since the power from the forward / backward switching device is transmitted to the front wheels, not only the rear wheels but also the front wheels can be driven. The second gear transmission mechanism having a gear ratio corresponding to the gear ratio of the gear transmission mechanism can be assembled from the front of the rear case portion in the same manner as the assembly of the gear transmission mechanism, so that it can be used for various operations. You can get a tractor that can drive the rear and front wheels with speed and torque at low cost.

In the present invention
It is preferable that the second gear transmission mechanism is configured to input the power of the output shaft of the rear wheel differential mechanism to the front wheel transmission mechanism.

According to this configuration, the second gear transmission mechanism takes out the forward power and the reverse power to be input to the front wheel transmission mechanism from the input shaft of the rear wheel differential mechanism. The forward power and reverse power, which are the outputs of the device, can be easily structurally input to the front wheel transmission mechanism.

In the present invention
It is preferable that the rear case portion can be divided into the front end portion of the rear case portion and a portion of the rear case portion other than the front end portion.

According to this configuration, by removing the front end portion from the portion other than the front end portion, the assembly work space of the gear transmission mechanism can be widened, so that the gear transmission mechanism can be easily assembled.

In the present invention
In the transmission, the power of the engine is input, and the hydrostatic and hydraulic stepless transmission that shifts and outputs the input power, and the power of the engine and the output of the stepless transmission are input. The compound planetary transmission unit includes a composite planetary transmission unit that combines the input power and the output to output the combined power, and the composite planetary transmission unit includes the axis of the sun gear in the composite planetary transmission unit and the engine. It is preferable that the axis of the output shaft of the above is positioned in a straight line, and the axis of the sun gear is arranged so as to be located above the axis of the input shaft of the rear wheel differential mechanism. Is.

According to this configuration, while the rear wheel differential mechanism is allowed to enter the lubricating oil accumulated in the mission case, the composite planetary transmission part does not enter the lubricating oil and rotates without receiving resistance from the lubricating oil to efficiently power. Can be communicated.

In the present invention
A step-by-step transmission unit that outputs the combined power output by the composite planetary transmission unit in stages in a plurality of speed ranges is provided, and a lubrication unit that discharges lubricating oil toward the step-by-step transmission unit is provided. It is preferable to have it.

According to this configuration, even if the stepped transmission unit does not enter the lubricating oil in the mission case like the compound planetary transmission unit, the lubrication unit refuels the staged transmission unit, so that the staged transmission unit Can prevent seizure.

In the present invention
A stepless output gear rotatably provided at the front portion of the stepless speed change unit with the front-rear axis as the center of rotation, and a planetary input gear rotatably provided at the front portion of the composite planetary transmission unit. A power transmission mechanism for transmitting the power of the stepless output gear to the planetary input gear is provided, and the power transmission mechanism is a rotatable front-rear relay provided parallel to the front-rear axis. The shaft, the first relay gear provided so as not to rotate relative to the rear end of the relay shaft while meshing with the stepless output gear, and the front end of the relay shaft meshing with the planetary input gear It is preferable to have a second relay gear provided so as not to be possible.

According to this configuration, the continuously variable output gear and the planetary input gear can be interlocked by the first relay gear, the relay shaft, and the second relay gear, and the continuously variable output gear can be displaced rearward with respect to the planetary input gear. , The front-rear length of the stepless case part that accommodates the stepless speed change part can be shortened.

In the present invention
A rotation shaft that is interlocked with the output shaft of the engine and is passed through the shaft core portion of the composite planetary transmission portion in the front-rear direction, and rotates around the rear portion of the stepless transmission portion with the front-rear orientation shaft core as the center of rotation. A stepless input gear provided as possible and a second power transmission mechanism for transmitting the power of the rotating shaft to the stepless input gear are provided, and the second power transmission mechanism is provided on the front-rear axis. The second relay shaft, which is rotatable in parallel with the other, and the power take-out gear, which is provided behind the composite planetary transmission unit so as not to rotate relative to the rotation shaft, are engaged with the power take-out gear. 2 A third relay gear provided at the rear end of the relay shaft so as to be relatively non-rotatable, and a fourth relay gear provided at the front end of the second relay shaft so as not to be able to rotate relative to the stepless input gear. And, it is preferable to have.

According to this configuration, the continuously variable input gear can be displaced forward with respect to the power extraction gear while the power extraction gear and the continuously variable input gear are interlocked by the third relay gear, the relay shaft and the fourth relay gear. , The front-rear length of the stepless case part that accommodates the stepless speed change part can be shortened.

Another tractor travel transmission according to the present invention is
A transmission case in which power from the engine is input by an input shaft, a shift transmission unit provided inside the mission case, in which power from the input shaft is input, and the input power is changed and output, and the above. A rear wheel differential mechanism provided inside the transmission case, in which the power output by the shift transmission unit is input and the input power is transmitted to the left and right rear wheels, is provided in the transmission transmission unit. A plurality of transmission units that shift and output power from the input shaft by a gear interlocking mechanism and a multi-plate clutch are provided in a state of being lined up in the front-rear direction of the transmission case, and inside the transmission case, above the transmission transmission unit. The refueling pipe is provided so as to extend in a direction extending along the direction in which the plurality of transmissions are arranged, and the refueling pipe is connected to a portion of the refueling pipe corresponding to the gear interlocking mechanism of each of the plurality of transmissions. A discharge nozzle for discharging the lubricating oil from the pipe toward the gear interlocking mechanism is provided.

According to this configuration, the amount of lubricating oil stored in the mission case is set so that the multi-plate clutch does not enter the lubricating oil or does not enter much, so that the multi-plate clutch rotates without receiving the rotational resistance due to the lubricating oil. Therefore, the transmission loss can be reduced as compared with the case where the multi-plate clutch rotates while receiving the rotational resistance due to the lubricating oil. As a result, even if the gear interlocking mechanism does not enter the lubricating oil or enters less, the lubricating oil can be supplied to the gear interlocking mechanism from above by the oil supply pipe and the discharge nozzle, so that the lubricating oil can be sufficiently supplied to the gear interlocking mechanism. it can.

In the present invention
It is preferable that the refueling pipe is integrally molded with the mission case.

According to this configuration, the mission case and the refueling pipe can be manufactured at once, so that the refueling pipe can be easily deployed and the transmission loss can be reduced as compared with the case where the refueling pipe is retrofitted in the mission case after the mission case is manufactured. On the other hand, it is possible to obtain an inexpensive product that can sufficiently supply lubricating oil to the gear interlocking mechanism.

In the present invention
It is preferable that the output shaft of the transmission transmission unit is arranged at a position higher than the input shaft of the rear wheel differential mechanism.

According to this configuration, even if the rear wheel differential mechanism enters the lubricating oil in the transmission case, it is easy to prevent the transmission transmission part from entering the lubricating oil or to make it less likely to enter, so that the multi-plate clutch depends on the lubricating oil. It is easy to rotate without receiving rotation resistance.

In the present invention
It is preferable that the output shaft of the transmission transmission unit is arranged at a position higher than the standard oil level of the lubricating oil stored in the transmission case.

According to this configuration, even if the rear wheel differential mechanism enters the lubricating oil in the transmission case, it is easy to prevent the transmission transmission part from entering the lubricating oil or to make it less likely to enter the lubricating oil. It is easy to rotate without receiving the rotation resistance due to.

In the present invention
It is preferable that the discharge nozzle is provided with an orifice.

According to this configuration, it is easy to keep the amount of lubricating oil discharged from the discharge nozzle toward the gear interlocking mechanism to a constant amount, so that it is easy to supply the lubricating oil to the gear interlocking mechanism in a fixed amount.

The left side showing the entire tractor. It is a diagram which shows the traveling transmission device. It is sectional drawing of the stepless transmission part. It is sectional drawing which shows the gear interlocking mechanism and the 2nd gear interlocking mechanism. It is sectional drawing which shows the step division transmission part, the forward / backward changeover device, the refueling part and the second refueling part. It is sectional drawing of the planetary gear mechanism of the first row. It is sectional drawing of the planetary gear mechanism of the first row. It is a schematic diagram which shows the arrangement of a compound planetary transmission part, a continuously variable transmission part, a rear wheel differential mechanism and the like. It is a left side view of a mission case. It is a top view of a mission case. It is a block diagram which shows the speed change operation device. It is explanatory drawing which shows the relationship between the operation area of a speed change lever, and the operation state of a step-by-step transmission part. It is explanatory drawing which shows the relationship between the speed change state of a continuously variable transmission part, a speed range, and an output speed by an output shaft. It is sectional drawing which shows the refueling part which has an orifice. It is explanatory drawing which shows the output shaft and the standard oil level in the traveling transmission device provided with the refueling part which has an orifice. It is sectional drawing which shows the discharge nozzle in the refueling part which has an orifice. It is sectional drawing which shows the discharge nozzle in the refueling part which has an orifice. It is a perspective view which shows the 1st lubrication port and the 2nd lubrication port.

Hereinafter, embodiments that are an example of the present invention will be described with reference to the drawings.
In the following description, with respect to the traveling vehicle body of the tractor, the direction of arrow F shown in FIG. 1 is "front of the vehicle body", the direction of arrow B is "rear of the vehicle body", the direction of arrow U is "upper vehicle body", and arrow D. The direction of is "lower of the car body", the direction of the front side of the paper is "left of the car body", and the direction of the back side of the paper is "right of the car body".

[Overall configuration of the tractor]
As shown in FIG. 1, the traveling vehicle body of the tractor extends forward from the lower part of the engine 1, the clutch housing 2 connected to the rear part of the engine 1, the mission case 3 connected to the rear part of the clutch housing 2, and the engine 1. It includes a vehicle body frame 5 composed of a front wheel support frame 4 that has been clutched. A pair of left and right front wheels 6 can be driven and steered on the front portion of the vehicle body frame 5, and a pair of left and right rear wheels 7 can be driven and mounted on the rear portion of the vehicle body frame 5. A driving portion 8 having an engine 1 is formed at the front portion of the traveling vehicle body. At the rear of the traveling vehicle body, a driver's seat 9 and a driver's unit 11 having a steering wheel 10 for steering and operating the front wheels 6 are formed. The driver unit 11 is provided with a cabin 12 that covers the boarding space. The rear part of the vehicle body frame 5 is equipped with a link mechanism 13 that connects various work devices such as a rotary tillage device so as to be able to move up and down. At the rear of the mission case 3, a power take-out shaft 14 for transmitting power from the engine 1 to a connected working device is provided.

[Structure of traveling transmission device]
The traveling transmission device 15 that transmits the power of the engine 1 to the front wheels 6 and the rear wheels 7 is configured as shown in FIG. In the traveling transmission device 15, the power of the output shaft 1a of the engine 1 is input from the main clutch 16 to the input shaft 17, and the power of the transmission 18 for shifting the input power and the output of the transmission 18 are input and input. The forward / backward switching device 19 and the forward / backward switching device 19 output the forward power and the reverse power are input, and the input forward power and the reverse power are transmitted to the left and right rear wheels 7. The front wheel transmission mechanism 21, the front wheel transmission mechanism 21 in which the forward power and the reverse power output by the rear wheel differential mechanism 20 and the forward / backward switching device 19 are input, and the input forward power and the reverse power are output toward the front wheels 6. A front wheel differential mechanism 22 is provided in which forward power and reverse power output by are input and the input forward power and reverse power are transmitted to the left and right front wheels 6.

The transmission 18, the forward / backward switching device 19, the rear wheel differential mechanism 20, and the front wheel transmission mechanism 21 are housed in the transmission case 3 as shown in FIG. As shown in FIGS. 2, 3, 4, 5, 9, and 10, the mission case 3 includes a front case portion 3A accommodating the transmission 18 and the front wheel transmission mechanism 21, a forward / backward switching device 19, and a rear wheel differential. It is configured to be separable by the first dividing line L1 with the rear case portion 3B accommodating the mechanism 20. As shown in FIGS. 2, 4, 5, 9, and 10, the rear case portion 3B includes the front portion of the output shaft 91 of the forward / backward switching device 19 and the front portion of the input shaft 20a of the rear wheel differential mechanism 20. Is configured to be divisible by a second dividing line L2 into a front end portion 3C located inside and a portion 3D other than the front end portion.

[Composition of transmission]
As shown in FIG. 2, the transmission 18 includes a continuously variable transmission unit 18A to which the power of the engine 1 is input, and a composite planetary transmission unit 18B to which the output of the continuously variable transmission unit 18A and the power of the engine 1 are input. It also has a stepwise transmission unit 18C that outputs the output of the composite planetary transmission unit 18B in stages. FIG. 8 is a schematic view showing the arrangement of the composite planetary transmission unit 18B, the continuously variable transmission unit 18A, the rear wheel differential mechanism 20, and the like. The direction of the arrow U shown in FIG. 8 indicates "upper body", the direction of the arrow D indicates "lower side of the vehicle body", the direction of the arrow L is "left side of the vehicle body", and the direction of the arrow R is ". "To the right of the car body" is shown. As shown in FIG. 8, the transmission 18 is housed in the transmission case 3, in which the output shaft 75 of the stepwise transmission unit 18C and the input shaft 90 of the forward / backward switching device 19 are combined planetary transmission in the front-rear direction view. The front-rear axis 37a of the stepless output gear 35 of the continuously variable transmission 18A is located laterally to the axis X of the sun gears 51 and 54 of the portion 18B, and the axis X of the sun gears 51 and 54. It is located laterally to the other side, and the shaft core X of the sun gears 51 and 54 is located above the shaft core Y of the input shaft 20a of the rear wheel differential mechanism 20.

[Structure of continuously variable transmission]
As shown in FIGS. 2 and 3, the continuously variable transmission 18A includes a variable displacement type and axial plunger type hydraulic pump 30, a constant capacity type and axial plunger type hydraulic motor 31, and a hydraulic pump 30 and a hydraulic motor 31. A drive oil passage 32 for connecting to and is provided. The continuously variable transmission 18A is a hydrostatic type continuously variable transmission. As shown in FIG. 3, the stepless case portion 33 covering the stepless speed change portion 18A of the front case portion 3A can be attached to and detached from a portion of the front case portion 3A other than the stepless case portion. ing. As shown in FIGS. 2 and 3, the continuously variable transmission 18A has a continuously variable input gear 34 rotatably provided at the rear of the continuously variable transmission 18A and rotatable at the front of the continuously variable transmission 18A. The stepless output gear 35 provided in the above is provided. The stepless input gear 34 is provided on the pump shaft 36 so as to be relatively non-rotatable, and rotates about the front-rear axis 36a of the pump shaft 36 as the center of rotation. The stepless output gear 35 is provided on the motor shaft 37 so as to be relatively non-rotatable, and rotates about the front-rear axis 37a of the motor shaft 37 as the center of rotation.

As shown in FIGS. 2 and 3, the stepless input gear 34 and the shaft core portion of the composite planetary transmission unit 18B are located behind the composite planetary transmission unit 18B of the rotating shaft 38 passed in the front-rear direction. A second power transmission mechanism 40 is provided over the portion. As shown in FIG. 3, the front end portion 38a of the rotating shaft 38 and the rear end portion 17a of the input shaft 17 of the transmission 18 are engaged with each other in a relative non-rotatable manner by spline engagement. As shown in FIGS. 2 and 3, the second power transmission mechanism 40 includes a rotatable second relay shaft 41 provided parallel to the front-rear axial core 36a of the stepless input gear 34, and a rotary shaft 38. The power take-out gear 42 provided so as to be relatively non-rotatable, and the third relay gear 43 provided so as to be non-relatively rotatable at the rear end of the second relay shaft 41 in a state of being meshed with the power take-out gear 42, and stepless input. It has a fourth relay gear 44 provided at the front end of the second relay shaft 41 so as not to rotate relative to the gear 34 in a state of being meshed with the gear 34. The second power transmission mechanism 40 transmits the power of the rotating shaft 38 to the stepless input gear 34. As shown in FIG. 2, the rotary shaft 38 is interlocked with the power take-off shaft 14 (PTO) via the relay shaft 45 and the PTO transmission 46, and transmits the power of the engine 1 transmitted to the input shaft 17. It is transmitted to the power take-out shaft 14.

In the continuously variable transmission 18A, the power of the engine 1 transmitted from the output shaft 1a of the engine 1 to the rotating shaft 38 via the main clutch 16 and the input shaft 17 is transmitted to the stepless input gear 34 by the second power transmission mechanism 40. It is transmitted and shifted to power in the forward rotation direction and power in the reverse rotation direction by the hydraulic pump 30 and the hydraulic motor 31, and the rotation speed is changed to the power that is continuously changed in both the forward rotation direction and the reverse rotation direction. To. The power in the forward rotation direction and the power in the reverse rotation direction after shifting are output from the stepless output gear 35.

[Structure of compound planetary transmission part]
As shown in FIG. 2, the composite planetary transmission unit 18B has two sun gears 51 and 54, and the axis X of the two sun gears 51 and 54 and the axis Z of the output shaft 1a of the engine 1 are formed. It is provided so that it is located on a straight line. The compound planetary transmission unit 18B includes two rows of planetary gear mechanisms 50A and 50B arranged in the front-rear direction. As shown in FIGS. 2 and 6, the planetary gear mechanism 50A in the first row includes a sun gear 51, an internal gear 52, and three planetary gears 53.
As shown in FIGS. 2 and 7, the planetary gear mechanism 50B in the second row includes a sun gear 54, an internal gear 55, and three planetary gears 56. As shown in FIG. 6, the planetary gear mechanism 50A in the first row is provided with three interlocking gears 57 that are individually meshed with the three planetary gears 53. As shown in FIG. 2, the three interlocking gears 57 are separately interlocked and connected to the three planetary gears 56 of the planetary gear mechanism 50B in the second row. The interlocking connection between the interlocking gear 57 and the planetary gear 56 is performed by integrally forming the interlocking gear 57 and the planetary gear 56.

As shown in FIG. 2, a planet input gear 58 is provided at the front of the composite planetary transmission unit 18B, which is interlocked with the sun gear 51 of the planetary gear mechanism 50A in the first row so as not to rotate relative to each other. The planetary input gear 58 is interlocked and connected to the continuously variable output gear 35 of the continuously variable transmission 18A by a power transmission mechanism 60. As shown in FIGS. 2 and 3, the power transmission mechanism 60 meshes with the rotatable relay shaft 61 provided parallel to the front-rear axis 37a of the stepless output gear 35 and the stepless output gear 35. The first relay gear 62 provided at the rear end of the relay shaft 61 so as to be relatively non-rotatable, and the second relay gear 62 provided at the front end of the relay shaft 61 so as to be in mesh with the planetary input gear 58. It has a relay gear 63 and. The power of the stepless output gear 35 is transmitted to the planetary input gear 58 by the power transmission mechanism 60, and is input from the planetary input gear 58 to the sun gear 51.

As shown in FIG. 2, a second planet input gear 59 is provided at the front portion of the composite planetary transmission unit 18B, which is interlocked and connected to the internal gear 52 of the planetary gear mechanism 50A in the first row so as not to rotate relative to each other. .. The second planet input gear 59 is interlocked and connected to the input shaft 17 by an input transmission mechanism 65. As shown in FIG. 2, the input transmission mechanism 65 is relative to the front end portion of the third relay shaft 67 in a state of being meshed with the input shaft gear 66 provided on the input shaft 17 so as not to rotate relative to the input shaft gear 66. It has a fourth relay gear 68 that is non-rotatable and a fifth relay gear 69 that is non-rotatably provided at the rear end of the third relay shaft 67 while meshing with the second planetary input gear 59. doing. The power of the engine 1 transmitted from the output shaft 1a of the engine 1 to the input shaft 17 via the main clutch 16 is transmitted to the second planet input gear 59 by the input transmission mechanism 65, and is transmitted from the second planet input gear 59 to the internal gear. It is input to 52.

As shown in FIG. 2, a first output shaft 71, a second output shaft 72, and a third output shaft 73 are provided at the rear portion of the composite planetary transmission unit 18B so as to be relatively rotatable. The first output shaft 71, the second output shaft 72, and the third output shaft 73 are configured as triple shafts. The first output shaft 71 is interlocked with the internal gear 55 of the planetary gear mechanism 50B in the second row. The second output shaft 72 is interlocked and connected to the carrier 70. The carrier 70 is configured to support the planetary gear 53 of the planetary gear mechanism 50A in the first row and to support the planetary gear 56 of the planetary gear mechanism 50B in the second row. The third output shaft 73 is interlocked with the sun gear 54 of the planetary gear mechanism 50B in the second row.

In the compound planetary transmission unit 18B, the output in the forward rotation direction and the output in the reverse rotation direction output from the stepless output gear 35 by the stepless speed change unit 18A are the sun gear 51 of the planetary gear mechanism 50A in the first row by the power transmission mechanism 60. The power from the engine 1 is input to the internal gear 52 of the planetary gear mechanism 50A in the first row by the input transmission mechanism 65, and the input output of the stepless transmission 18A and the power of the engine 1 are in two rows. The planetary gear mechanisms 50A and 50B of the above are combined, and the combined power is output from the first output shaft 71, the second output shaft 72, and the third output shaft 73.

[Structure of stepped transmission unit]
As shown in FIGS. 2 and 5, the step division transmission unit 18C includes a first clutch CL1, a second clutch CL2, a third clutch CL3, and a fourth clutch CL4. The first to fourth clutches are composed of hydraulically operated multi-plate clutches. The output shaft 75 is interlocked and connected to the output-side rotating members of the first clutch CL1, the second clutch CL2, the third clutch CL3, and the fourth clutch CL4 so that they cannot rotate relative to each other. A first-speed gear interlocking mechanism 76 for setting the first-speed range is provided over the input-side rotating member of the first clutch CL1 and the first output shaft 71 of the composite planetary transmission unit 18B. A second-speed gear interlocking mechanism 77 for setting the second-speed range is provided over the input-side rotating member of the second clutch CL2 and the third output shaft 73 of the composite planetary transmission unit 18B. A third-speed gear interlocking mechanism 78 for setting the third-speed range is provided over the input-side rotating member of the third clutch CL3 and the second output shaft 72 of the composite planetary transmission unit 18B. A 4-speed gear interlocking mechanism 79 for setting the 4-speed range is provided over the input-side rotating member of the fourth clutch CL4 and the third output shaft 73 of the composite planetary transmission unit 18B.

As shown in FIG. 11, the first clutch CL1, the second clutch CL2, the third clutch CL3, the fourth clutch CL4, and the continuously variable transmission unit 18A are linked to the control device 80. The control device 80 is linked with an operation position sensor 82 that detects the operation position of the speed change lever 81 and a swash plate sensor 83 that detects the swash plate angle in the hydraulic pump 30 of the continuously variable transmission unit 18A. The control device 80 is composed of a microcomputer and includes a shift control means 84. The shift control means 84 is such that the continuously variable transmission unit 18A is in a shift state corresponding to the operation position of the shift lever 81, and the stepwise transmission unit 18C is in an operation state corresponding to the operation position of the shift lever 81. In addition, the diagonal plate of the continuously variable transmission 18A is controlled based on the detection result by the operation position sensor 82 and the detection result by the diagonal plate sensor 83, and the first clutch CL1, the second clutch CL2, and the third clutch CL3 And the fourth clutch CL4 is switched and controlled. As shown in FIG. 11, the speed change lever 81 is configured to be operable over the first operation area A1, the second operation area A2, the third operation area A3, and the fourth operation area A4.

FIG. 12 is an explanatory diagram showing the relationship between the operating range of the speed change lever 81 and the operating state of the stepwise transmission unit 18C. “○” shown in FIG. 12 indicates the engaged state of the first clutch CL1, the second clutch CL2, the third clutch CL3, and the fourth clutch CL4, and “−” indicates the first clutch CL1, the second clutch CL2, and the second clutch CL4. The disengaged state of the 3rd clutch CL3 and the 4th clutch CL4 is shown. FIG. 13 is an explanatory diagram showing the relationship between the speed change state of the continuously variable transmission unit 18A, the speed range, and the output speed V by the output shaft 75. The vertical axis of FIG. 13 indicates the output speed V by the output shaft 75. The horizontal axis of FIG. 13 indicates the shifting state of the continuously variable transmission unit 18A, “N” indicates the neutral state, and “+ MAX” indicates the maximum speed state in the state where the output direction is in the forward rotation direction. "-MAX" indicates the maximum speed state in the state where the output direction is in the reverse rotation direction.

In the transmission 18, as shown in FIGS. 12 and 13, when the shift lever 81 is operated in the first operation range A1, the first clutch Cl1 is controlled to be engaged, and the shift lever 81 is in the first operation range. As the A1 is operated from the lowest speed position to the highest speed position, the continuously variable transmission 18A is speed-shifted from the maximum speed state in the reverse rotation direction to the maximum speed state in the forward rotation direction, and the output shaft is operated. The output speed V of 75 increases steplessly from zero to V1 in the 1st speed range. When the shifting lever 81 is operated in the second operating range A2, the second clutch CL2 is controlled to be engaged, and the shifting lever 81 is operated from the lowest speed position to the highest speed position in the second operating range A2. As a result, the stepless speed change unit 18A is speed-shifted from the maximum speed state in the forward rotation direction to the maximum speed state in the reverse rotation direction, and the output speed V of the output shaft 75 is steplessly changed from V1 to V2 in the second speed range. It will accelerate to. When the shifting lever 81 is operated in the third operating range A3, the third clutch CL3 is controlled to be engaged, and the shifting lever 81 is operated from the lowest speed position to the highest speed position in the third operating range A3. As a result, the stepless speed change unit 18A is speed-shifted from the maximum speed state in the reverse rotation direction to the maximum speed state in the forward rotation direction, and the output speed V of the output shaft 75 is steplessly changed from V2 to V3 in the 3rd speed range. It will accelerate to. When the shifting lever 81 is operated in the fourth operating range A4, the fourth clutch CL4 is controlled to be engaged, and the shifting lever 81 is operated from the lowest speed position to the highest speed position in the fourth operating range A4. As a result, the stepless speed change unit 18A is speed-shifted from the maximum speed state in the forward rotation direction to the maximum speed state in the reverse rotation direction, and the output speed V of the output shaft 75 is steplessly changed from V3 to V4 in the 4-speed range. It will accelerate to.

[Structure of forward / backward switching device and rear wheel differential mechanism]
The forward / backward switching device 19 and the rear wheel differential mechanism 20 are provided behind the transmission 18 as shown in FIG. The forward / backward switching device 19 is parallel to the input shaft 90 and the input shaft 90 which are interlocked and interlocked with the output shaft 75 (output shaft of the transmission 18) of the stepwise transmission unit 18C via a connecting member 85 so as not to rotate relative to each other. It is provided with an output shaft 91 arranged in. The output shaft 91 is composed of a tubular shaft that is externally fitted to the relay shaft 45 so as to be relatively rotatable. The axis of the output shaft 91 is located on the same axis as the axes of the sun gears 51 and 54 of the composite planetary transmission unit 18B. The input side rotating members of the forward clutch CLF and the reverse clutch CLR are connected to the input shaft 90 so as not to rotate relative to each other. A forward gear mechanism 92 is provided over the output side rotating member of the forward clutch CLF and the output shaft 91. A reverse gear mechanism 93 is provided over the output side rotating member of the reverse clutch CLR and the output shaft 91. The reverse gear 93a of the reverse gear mechanism 93 is supported by the input shaft 20a of the rear wheel differential mechanism 20 so as to be relatively rotatable. A gear interlocking mechanism 95 is provided over the front portion of the output shaft 91 of the forward / backward switching device 19 and the front portion of the input shaft 20a of the rear wheel differential mechanism 20.

In the forward / backward switching device 19, the forward clutch CLF and the reverse clutch CLR are switched by operating the forward / backward lever 98 (see FIG. 10). When the forward clutch CLF is switched to the engaged state and the reverse clutch CLR is switched to the disengaged state, the power input from the output shaft 75 of the transmission 18 to the input shaft 90 is forward power by the forward clutch CLF and the forward gear mechanism 92. Is converted to and transmitted to the output shaft 91. When the forward clutch CLF is switched to the disengaged state and the reverse clutch CLR is switched to the on state, the power input from the output shaft 75 of the transmission 18 to the input shaft 90 is transferred to the reverse power by the reverse clutch CLR and the reverse gear mechanism 93. Is converted to and transmitted to the output shaft 91.

As shown in FIGS. 2 and 4, the forward power and reverse power output from the output shaft 91 by the forward / backward switching device 19 are transmitted to the input shaft 20a of the rear wheel differential mechanism 20 by the gear interlocking mechanism 95, and the rear wheel difference. It is transmitted to the left and right rear wheels 7 by the moving mechanism 20. As shown in FIG. 2, the power transmission from the rear wheel differential mechanism 20 to the left and right rear wheels 7 is a planetary gear type provided between the output shaft 20b of the rear wheel differential mechanism 20 and the rear axle 7a. It is performed via the final deceleration mechanism 96 of the above. A steering brake 97 is provided on the output shaft 20b of the rear wheel differential mechanism 20.

[Construction of front wheel transmission mechanism]
As shown in FIG. 2, the front wheel transmission mechanism 21 is interlocked and connected to the front portion of the input shaft 20a of the rear wheel differential mechanism 20 via the second gear interlocking mechanism 100, the relay shaft 101, and the connecting member 102. It includes a shaft 103 and an output shaft 104 arranged parallel to the input shaft 103. The input side rotating members of the constant velocity clutch 105 and the speed increasing clutch 106 are connected to the input shaft 103 so as to be relatively non-rotatable. A constant velocity gear mechanism 107 is provided across the output side rotating member of the constant velocity clutch 105 and the output shaft 104 to transmit the rotational speed of the input shaft 103 to the output shaft 104 by transmission at a substantially constant velocity. A speed-increasing gear mechanism 108 is provided across the output-side rotating member of the speed-increasing clutch 106 and the output shaft 104 to increase the rotational speed of the input shaft 103 and transmit it to the output shaft 104. The output shaft 104 is interlocked with the input shaft 22a of the front wheel differential mechanism 22 via the rotating shaft 109, and outputs toward the left and right front wheels 6.

In the second gear interlocking mechanism 100, the power of the output shaft 91 is transmitted by the gear interlocking mechanism 95, and the power of the input shaft 20a is transmitted to the relay shaft 101. Power and reverse power are transmitted to the input shaft 103 by the second gear interlocking mechanism 100.

In the front wheel transmission mechanism 21, the constant velocity clutch 105 is switched to the engaged state, and the speed increasing clutch 106 is switched to the disengaged state, so that the forward / backward switching device 19 transmitted by the second gear interlocking mechanism 100 and the relay shaft 101. The power of the input shaft 103, which is rotated by the power from the above, is transmitted to the output shaft 104 by the constant velocity clutch 105 and the constant velocity gear mechanism 107, and is output from the output shaft 104 toward the front wheel 6. In this case, the front wheels 6 and the rear wheels 7 are driven in a state where the input shaft 103 transmits the output shaft 104 at a constant speed and the average peripheral speeds of the left and right front wheels 6 are substantially equal to the average peripheral speeds of the left and right rear wheels 7. The four-wheel drive state to be performed appears.

In the front wheel transmission mechanism 21, the constant velocity clutch 105 is switched to the disengaged state, and the speed increasing clutch 106 is switched to the engaged state, so that the forward / backward switching device 19 transmitted by the second gear interlocking mechanism 100 and the relay shaft 101. The power of the input shaft 103, which is rotated by the power from the above, is transmitted to the output shaft 104 by the speed-up clutch 106 and the speed-up gear mechanism 108, and is output from the output shaft 104 toward the front wheels 6. In this case, the speed is transmitted from the input shaft 103 to the output shaft 104, and the front wheels 6 and the rear wheels 7 are driven in a state where the average peripheral speeds of the left and right front wheels 6 are faster than the average peripheral speeds of the left and right rear wheels 7. The four-wheel drive state of speeding up the front wheels is revealed.

In the front wheel transmission mechanism 21, the constant velocity clutch 105 and the acceleration clutch 106 are both switched to the disengaged state, so that the transmission from the input shaft 103 to the output shaft 104 is stopped, and the output toward the front wheels 6 is stopped. Will be done. In this case, a two-wheel drive state appears in which the left and right front wheels 6 are not driven and the left and right rear wheels 7 are driven.

As shown in FIG. 4, the gear interlocking mechanism 95 that transmits the power of the output shaft 91 of the forward / backward switching device 19 to the input shaft 20a of the rear wheel differential mechanism 20 is a rear case portion of the inside of the transmission case 3. It is detachably provided at a portion corresponding to the front end portion 3C of 3B. Specifically, the gear interlocking mechanism 95 is a rear wheel differential mechanism in a state where the first gear 95a, which is detachably provided at the front end of the output shaft 91 of the forward / backward switching device 19, and the first gear 95a are meshed with each other. It has a second gear 95b that is detachably provided at the front end of the input shaft 20a of 20.

As shown in FIG. 4, the second gear interlocking mechanism 100 that inputs the power from the forward / backward switching device 19 to the input shaft 103 of the front wheel transmission mechanism 21 is the front end of the rear case portion 3B in the inside of the mission case 3. It is detachably provided at the portion corresponding to the portion 3C. Specifically, the third gear 100a, which is detachably provided at the front end of the input shaft 20a of the rear wheel differential mechanism 20, and the relay shaft 101, which is in mesh with the third gear 100a, are detachably provided. It has a fourth gear 100b. The relay shaft 101 is detachably linked to the input shaft 103 of the front wheel transmission mechanism 21 by a connecting member 102. A parking brake 101A is mounted on the relay shaft 101.

When obtaining a tractor having different maximum vehicle speeds and torques that can be transmitted to the front wheels 6 and the rear wheels 7, a gear interlocking mechanism 95 having a corresponding gear ratio is selected from a plurality of gear interlocking mechanisms 95 having different gear ratios, and A second gear interlocking mechanism 100 having a gear ratio corresponding to the selected gear interlocking mechanism 95 is selected from a plurality of second gear interlocking mechanisms 100 having different gear ratios, and the selected gear interlocking mechanism 95 and the second gear interlocking mechanism 100 are selected. Assemble. This assembly can be performed from the front of the rear case portion 3B in a state where the front end portion 3C is separated from the front case portion 3A. For example, when newly assembling the traveling transmission device 15, after assembling the transmission 18, the forward / backward switching device 19, and the rear wheel differential mechanism 20, the selected gear interlocking mechanism 95 and the second gear interlocking mechanism 100 are assembled. Can be done. When replacing the gear interlocking mechanism 95 and the second gear interlocking mechanism 100, the selected gear interlocking mechanism 95 and the second gear interlocking mechanism 95 and the second gear interlocking mechanism are not removed without removing the transmission 18, the forward / backward switching device 19, and the rear wheel differential mechanism 20. The mechanism 100 can be assembled.

Inside the mission case 3, as shown in FIG. 5, a first refueling unit 110 that supplies lubricating oil to the stepwise transmission unit 18C and a second refueling unit that supplies lubricating oil to the forward / backward switching device 19 114 and are provided. In the present embodiment, the first refueling unit 110 and the second refueling unit 114 are provided, but a refueling unit that supplies lubricating oil to the composite planetary transmission unit 18B may be provided.

Specifically, as shown in FIGS. 5 and 8, the first refueling unit 110 is a refueling pipe 111 provided above the stepwise transmission unit 18C in a front-rear direction, and a refueling pipe 111. , 1st gear interlocking mechanism 76 in the stepwise transmission unit 18C, 2nd gear interlocking mechanism 77, 3rd gear interlocking mechanism 78 and 4th gear interlocking mechanism 79, respectively. doing. The oil supply pipe 111 is integrally formed with the front case portion 3A. A refueling pump 113 is connected to the refueling pipe 111.

In the first refueling unit 110, the lubricating oil stored in the mission case 3 is taken out by the refueling pump 113 and supplied to the refueling pipe 111, and the supplied lubricating oil is the corresponding first gear from each discharge nozzle 112. It is discharged from above toward the interlocking mechanism 76, the 2nd gear interlocking mechanism 77, the 3rd gear interlocking mechanism 78, or the 4th gear interlocking mechanism 79.

Specifically, as shown in FIG. 5, the second refueling unit 114 is a refueling pipe 115 provided above the forward / backward switching device 19 in a front-rear direction, and a front-rear refueling pipe 115. It has a forward gear mechanism 92 in the advance switching device 19 and a discharge nozzle 116 formed at a portion corresponding to the reverse gear mechanism 93. The oil supply pipe 115 is integrally formed with the rear case portion 3B. Although not shown, a refueling pump 113 is connected to the refueling pipe 115.

In the second refueling unit 114, the lubricating oil stored in the mission case 3 is taken out by the refueling pump 113 and supplied to the refueling pipe 115, and the supplied lubricating oil is a forward gear mechanism corresponding to each discharge nozzle 116. It is discharged from above toward 92 or the reverse gear mechanism 93.

Hereinafter, the refueling units 110 and 114 will be described in more detail with reference to FIG. 14 and the like.

As shown in FIG. 2, the traveling transmission device 15 includes a mission case 3 in which power from the engine 1 is input by an input shaft 17. Power transmission from the engine 1 to the input shaft 17 is performed by connecting the input shaft 17 to the output shaft 1a of the engine 1 via the main clutch 16. Inside the transmission case 3, a speed change transmission unit composed of a stepwise transmission unit 18C, a speed change transmission unit composed of a forward / backward switching device 19, a front wheel transmission mechanism 21 that outputs to the front wheel differential mechanism 22, and left and right A rear wheel differential mechanism 20 that transmits power to the rear wheels 7 is provided.

In the following, the speed change transmission unit composed of the stepwise transmission unit 18C will be referred to as a first speed change transmission unit 18C, and the speed change transmission unit composed of the forward / backward switching device 19 will be referred to as a second speed change transmission unit 19. explain.

Power from the input shaft 17 is input to the first transmission transmission unit 18C. Specifically, as shown in FIG. 2, the power of the input shaft 17 is input to the pump shaft 36 of the continuously variable transmission unit 18A via the rotating shaft 38 and the second power transmission mechanism 40. In the stepless speed change unit 18A, the input power is steplessly changed by the hydraulic pump 30 and the hydraulic motor 31 and output from the motor shaft 37. The output of the stepless speed change unit 18A is input to the sun gear 51 of the planetary gear mechanism 50A in the first row in the compound planetary transmission unit 18B via the power transmission mechanism 60, and the power of the input shaft 17 is input to the sun gear 51 via the input transmission mechanism 65 in a row. It is input to the internal gear 52 of the planetary gear mechanism 50A of the eye, and in the compound planetary transmission unit 18B, the power from the input shaft 17 and the power from the stepless speed change unit 18A are the first row planetary gear mechanism 50A and the second row. It is synthesized by the planetary gear mechanism 50B of. The combined power synthesized by the composite planetary transmission unit 18B is input to the first transmission transmission unit 18C.

As shown in FIG. 2, the first transmission transmission unit 18C includes four transmission units 23 arranged in the front-rear direction of the mission case 3 and an output shaft 75, and has four combined powers from the composite planetary transmission unit 18B. The speed is changed by the speed change unit 23, and the changed power is output from the output shaft 75 to the rear wheel differential mechanism 20 and the front wheel transmission mechanism 21.

Specifically, as shown in FIG. 2, the first transmission 23a of the four transmissions 23 includes the first gear interlocking mechanism 76 of the four gear interlocking mechanisms and the four multi-plate clutches. The first clutch CL1 of the above is provided. The second transmission 23b of the four transmissions 23 includes a second gear interlocking mechanism 77 of the four gear interlocking mechanisms and a second clutch CL2 of the four multi-plate clutches. The third transmission 23c of the four transmissions 23 includes a third gear interlocking mechanism 78 of the four gear interlocking mechanisms and a third clutch CL3 of the four multi-plate clutches. The fourth transmission 23d of the four transmissions 23 includes a fourth gear interlocking mechanism 79 of the four gear interlocking mechanisms and a fourth clutch CL4 of the four multi-plate clutches.

The first to fourth clutches CL1, CL2, CL3, and CL4 are provided on the output shaft 75. The first-speed gear interlocking mechanism 76 is provided over the first output shaft 71 of the composite planetary transmission unit 18B and the input side member of the first clutch CL1. The second gear interlocking mechanism 77 is provided over the third output shaft 73 of the composite planetary transmission unit 18B and the input side member of the second clutch CL2. The third-speed gear interlocking mechanism 78 is provided over the second output shaft 72 of the composite planetary transmission unit 18B and the input side member of the third clutch CL3. The 4-speed gear interlocking mechanism 79 is provided over the third output shaft 73 of the composite planetary transmission unit 18B and the input side member of the fourth clutch CL4.

In the first transmission transmission unit 18C, when the first clutch CL1 of only the first transmission unit 23a of the four transmission units 23 is operated in the engaged state, the combined power output by the composite planetary transmission unit 18B is the first speed. The gear interlocking mechanism 76 and the first clutch CL1 shift gears so as to have a driving force in the first speed range (see FIG. 13) and transmit the gears to the output shaft 75, from the output shaft 75 to the input shaft 90 of the second gear shifting transmission unit 19. Be transmitted. When the second clutch CL2 of only the second transmission 23b of the four transmissions 23 is operated in the engaged state, the combined power output by the composite planetary transmission unit 18B is the second gear interlocking mechanism 77 and the second clutch CL2. The gear is changed so as to have a driving force in the second speed range (see FIG. 13) and is transmitted to the output shaft 75, and is transmitted from the output shaft 75 to the input shaft 90 of the second speed change transmission unit 19. When the third clutch CL3 of only the third transmission 23c of the four transmissions 23 is operated in the engaged state, the combined power output by the composite planetary transmission unit 18B is the third gear interlocking mechanism 78 and the third clutch CL3. The gear is changed so as to have a driving force in the third speed range (see FIG. 13) and is transmitted to the output shaft 75, and is transmitted from the output shaft 75 to the input shaft 90 of the second transmission transmission unit 19. When the 4th clutch CL4 of only the 4th transmission 23d of the 4 transmissions 23 is operated in the engaged state, the combined power output by the composite planetary transmission 18B is the 4th gear interlocking mechanism 79 and the 4th clutch CL4. The gear is changed so as to have a driving force in the 4-speed range (see FIG. 13) and is transmitted to the output shaft 75, and is transmitted from the output shaft 75 to the input shaft 90 of the second transmission transmission unit 19.

As shown in FIG. 8, the first transmission transmission unit 18C is configured such that the output shaft 75 is located at a position higher than the input shaft 20a of the rear wheel differential mechanism 20. As shown in FIG. 15, the first transmission transmission unit 18C is configured such that the output shaft 75 is located at a position higher than the standard oil level OS of the lubricating oil stored in the transmission case 3. The first to fourth clutches CL1, CL2, CL3, and CL4 in the four transmission units 23 do not enter the lubricating oil so much and rotate without receiving much rotational resistance due to the lubricating oil.

As shown in FIG. 14, inside the transmission case 3, a refueling pipe 111 extending in a direction along the direction in which the four transmission units 23 are lined up is provided above the first transmission transmission unit 18C. The refueling pipe 111 has the same configuration as the refueling pipe 111 provided in the refueling unit 110 shown in FIG. The refueling pipe 111 is integrally molded with the mission case 3. The gears of the 1st to 4th gear interlocking mechanisms 76, 77, 78, 79 are located in the parts of the lubrication pipe 111 corresponding to the 1st to 4th gear interlocking mechanisms 76, 77, 78, 79. A discharge nozzle 117 for discharging lubricating oil toward the interlocking mechanism 76, 77, 78, 79 is connected. Out of the four gear interlocking mechanisms 76, 77, 78, 79, the discharge nozzle 117 corresponding to each gear interlocking mechanism 76, 78, 79 of the 1st gear interlocking mechanism 76, the 3rd gear interlocking mechanism 78, and the 4th gear interlocking mechanism 79. Has a discharge port that is opened downward toward each gear interlocking mechanism 76, 78, 79 as shown in FIGS. 14 and 16, and is a lubricating oil directly toward the gear interlocking mechanism 76, 78, 79. Is discharged. Of the four gear interlocking mechanisms 76, 77, 78, 79, the discharge nozzle 117 for discharging the lubricating oil to the second gear interlocking mechanism 77 has a discharge port opened backward as shown in FIGS. Have. A tilt guide 118 is provided in the transmission case 3 behind the discharge nozzle 117 corresponding to the second gear interlocking mechanism 77. The discharge nozzle 117 corresponding to the 2nd gear interlocking mechanism 77 discharges the lubricating oil toward the inclined guide 118, and the inclined guide so that the lubricating oil hitting the inclined guide 118 flows down toward the 2nd gear interlocking mechanism 77. Guided by 118. The discharge nozzle 117 corresponding to the second-speed gear interlocking mechanism 77 indirectly discharges the lubricating oil toward the second-speed gear interlocking mechanism 77. As shown in FIG. 16, an orifice 117a is provided in the discharge nozzle 117 corresponding to each gear interlocking mechanism 76, 77, 78, 79 of the four gear interlocking mechanisms 76, 77, 78, 79.

As shown in FIG. 18, the first lubrication port 119 is opened in the wall portion of the mission case 3. The first lubrication port 119 is communicated with the oil supply pipe 111 via a communication passage 120 (see FIG. 14). When the lubrication pump 121 is connected to the first lubrication port 119 and the lubricating oil is supplied to the lubrication pipe 111 through the first lubrication port 119 and the communication passage 120 by the lubrication pump 121, the supplied lubricating oil is from the first gear. Lubricating oil is discharged by the discharge nozzle 117 toward each of the four-speed gear interlocking mechanisms 76, 77, 78, and 79. Regardless of the change in the oil pressure in the oil supply pipe 111, the discharge amount is quantified by the orifice 117a, and the lubricating oil is supplied to the 1st to 4th gear interlocking mechanisms 76, 77, 78, 79 from above. The output shaft 75 is located higher than the standard oil level OS, and the 1st to 4th gear interlocking mechanisms 76, 77, 7, 8 and 79 do not enter the lubricating oil so much, but the 1st to 4th gear interlocking mechanisms A certain amount of lubricating oil is supplied to 76, 77, 78, and 79 by the oil supply pipe 111 and the discharge nozzle 117 with the orifice 117a.

As shown in FIG. 2, the second speed change transmission unit 19 has an input shaft 90 interlocked with the output shaft 75 of the first speed change transmission unit 18C via a connecting member 85, and the first speed change transmission unit 18C The output of is input by the input shaft 17.

As shown in FIG. 2, the second speed change transmission unit 19 includes two speed change units 25 arranged in the front-rear direction of the transmission case 3 and an output shaft 91, and transmits from the first speed change transmission unit 18C to the input shaft 90. The generated power is changed by the two transmission units 25, and the changed power is output from the output shaft 91 to the rear wheel differential mechanism 20 and the front wheel transmission mechanism 21.

Specifically, as shown in FIG. 2, one of the two transmissions 25, the forward transmission 25a, includes a forward gear mechanism 92 and a forward clutch CLF. The reverse speed change unit 25b of the other of the two speed change units 25 includes a reverse gear mechanism 93 and a reverse clutch CLR. The forward clutch CLF and the reverse clutch CLR are composed of a multi-plate clutch and are provided on the input shaft 90. The forward gear mechanism 92 is provided over the output side member of the forward clutch CLF and the output shaft 91. The reverse gear mechanism 93 is provided over the output side member of the reverse clutch CLR and the output shaft 91.

In the second speed change transmission unit 19, when the forward clutch CLF is operated in the engaged state, the power of the input shaft 90 transmitted from the first speed change transmission unit 18C is changed to the forward power by the forward clutch CLF and the forward gear mechanism 92. Then, it is transmitted to the output shaft 91, and the forward power of the output shaft 91 is transmitted to the input shaft 20a of the rear wheel differential mechanism 20 via the gear interlocking mechanism 95. Further, the forward power of the output shaft 91 is transmitted to the input shaft 103 of the front wheel transmission mechanism 21 via the gear interlocking mechanism 95, the input shaft 20a, and the second gear interlocking mechanism 100. When the reverse clutch CLR is operated in the engaged state, the power of the input shaft 90 is changed to the reverse power by the reverse clutch CLR and the reverse gear mechanism 93 and transmitted to the output shaft 91, and the reverse power of the output shaft 91 is transmitted to the gear interlocking mechanism. It is transmitted to the input shaft 20a of the rear wheel differential mechanism 20 via 95. Further, the reverse power of the output shaft 91 is transmitted to the input shaft 103 of the front wheel transmission mechanism 21 via the gear interlocking mechanism 95, the input shaft 20a and the second gear interlocking mechanism 100.

In the second transmission transmission unit 19, as shown in FIG. 15, the input shaft 90 and the output shaft 91 are located at positions higher than the input shaft 20a of the rear wheel differential mechanism 20, and the output shaft 91 is set. It is configured to be located at a position higher than the standard oil level OS of the lubricating oil stored in the mission case 3. The forward clutch CLF and the reverse clutch CLR do not penetrate much into the lubricating oil and rotate without receiving much rotational resistance due to the lubricating oil.

As shown in FIG. 14, inside the transmission case 3, a refueling pipe 115 extending in a direction along the direction in which the two transmission units 25 are lined up is provided above the second transmission transmission unit 19. The refueling pipe 115 has the same configuration as the refueling pipe 115 provided in the refueling unit 110 shown in FIG. The refueling pipe 115 is integrally molded with the mission case 3. A discharge nozzle 122 for discharging lubricating oil toward the gear mechanisms 92 and 93 is connected to a portion of the oil supply pipe 115 corresponding to the gear mechanisms 92 and 93 of the forward gear mechanism 92 and the reverse gear mechanism 93. .. As shown in FIGS. 14 and 17, the discharge nozzle 122 corresponding to the forward gear mechanism 92 has a discharge port opened downward toward the forward gear mechanism 92 and lubricates directly toward the forward gear mechanism 92. Discharge oil. The discharge nozzle 122 corresponding to the reverse gear mechanism 93 has a discharge port opened forward as shown in FIGS. 14 and 17. A tilt guide 123 is provided in the transmission case 3 in front of the discharge nozzle 122 corresponding to the reverse gear mechanism 93. The discharge nozzle 122 corresponding to the reverse gear mechanism 93 discharges lubricating oil toward the tilt guide 123, and the lubricating oil that hits the tilt guide 123 is guided by the tilt guide 123 so as to flow down toward the reverse gear mechanism 93. Lubrication. The discharge nozzle 122 corresponding to the reverse gear mechanism 93 indirectly discharges the lubricating oil toward the reverse gear mechanism 93. As shown in FIG. 17, an orifice 122a is provided in the discharge nozzle 122 corresponding to each gear mechanism 92.93 of the forward gear mechanism 92 and the reverse gear mechanism 93.

As shown in FIG. 18, the second lubrication port 124 is opened in the wall portion of the mission case 3. The second lubrication port 124 communicates with the oil supply pipe 115 via a communication passage 125 (see FIG. 14). When the lubrication pump 126 is connected to the second lubrication port 124 and the lubricating oil is supplied to the lubrication pipe 115 through the second lubrication port 124 and the communication passage 125 by the lubrication pump 126, the supplied lubricating oil is transferred to the forward gear mechanism. It is discharged by the discharge nozzle 122 toward the 92 and the reverse gear mechanism 93. Regardless of the change in the oil pressure in the oil supply pipe 115, the discharge amount is quantified by the orifice 122a, and the quantified lubricating oil is supplied to the forward gear mechanism 92 and the reverse gear mechanism 93 from above. Although the forward gear mechanism 92 and the reverse gear mechanism 93 do not enter the lubricating oil very much, a certain amount of lubricating oil is supplied to the forward gear mechanism 92 and the reverse gear mechanism 93 by the oil supply pipe 115 and the discharge nozzle 122 with the orifice 122a.

[Another Embodiment]
(1) In the above-described embodiment, the transmission 18 includes, but is not limited to, the continuously variable transmission 18A, the compound planetary transmission unit 18B, and the stepwise transmission unit 18C. For example, it may be a transmission having a continuously variable transmission unit and a planetary transmission unit and not having a stepwise transmission unit, or a transmission gear that shifts gears in a plurality of stages by shifting gears or switching clutches.

(2) In the above-described embodiment, an example in which the front wheels 6 and the rear wheels 7 can be driven is shown, but only the rear wheels 7 may be driven.

(3) In the above-described embodiment, an example is shown in which the power of the input shaft 20a of the rear wheel differential mechanism 20 is input to the front wheel transmission mechanism 21 as the second gear interlocking mechanism 100. The power of the output shaft 91 of the device 19 may be directly input to the front wheel transmission mechanism 21.

(4) In the above embodiment, an example is shown in which the rear case portion 3B can be divided into a front end portion 3C and a portion 3D other than the front end portion, but the rear case portion 3B is divided into a front end portion 3C and a portion 3D other than the front end portion. It may not be possible.

The present invention includes a transmission, a forward / backward switching device provided behind the transmission, a rear wheel differential mechanism provided behind the transmission, a transmission, a forward / backward switching device, and a rear wheel differential mechanism. It can be applied to a mission case for accommodating and a traveling transmission device of a tractor equipped with.

1 Engine 1a Output shaft 2 Jikushin 3 Mission case 3A Front case part 3B Rear case part 3C Front end part 3D Parts other than front end part 6 Front wheel 7 Rear wheel 18 Transmission 18A Continuously variable transmission 18B Combined planetary transmission 18C Stage division Transmission unit, transmission transmission unit (first transmission transmission unit)
19 Forward / backward switching device, speed change transmission unit (second speed change transmission unit)
20 Rear wheel differential mechanism 20a Input shaft 21 Front wheel transmission mechanism 23 Transmission (1st transmission, 2nd transmission, 3rd transmission, 4th transmission)
25 Transmission (forward transmission, reverse transmission)
34 Stepless input gear 35 Stepless output gear 36a Front-rear shaft core 37a Front-rear shaft core 38 Rotating shaft 40 Second power transmission mechanism 41 Second relay shaft 42 Power take-out gear 43 Third relay gear 44 Fourth relay gear 51 Sun Gear 54 Sun gear 58 Planetary input gear 60 Power transmission mechanism 61 Relay shaft 62 1st relay gear 63 2nd relay gear 91 Output shaft 95 Gear interlocking mechanism 75 Output shaft 76 Gear interlocking mechanism (1st gear interlocking mechanism)
77 Gear interlocking mechanism (2nd gear interlocking mechanism)
78 Gear interlocking mechanism (3rd gear interlocking mechanism)
79 Gear interlocking mechanism (4th gear interlocking mechanism)
91 Output shaft 92 Gear interlocking mechanism (forward gear mechanism)
93 Gear interlocking mechanism (reverse gear mechanism)
110 Refueling section (first refueling section)
111 Refueling pipe 117 Discharge nozzle 117a Orifice 115 Refueling pipe 122 Discharge nozzle 122a Orifice CL1 Multi-plate clutch (first clutch)
CL2 multi-plate clutch (second clutch)
CL3 multi-plate clutch (3rd clutch)
CL4 multi-plate clutch (4th clutch)
CLF multi-plate clutch (forward clutch)
CLR multi-plate clutch (reverse clutch)
OS standard oil level X axis core Y axis core

Claims (13)

A transmission that shifts and outputs the power from the engine,
A forward / backward switching device provided behind the transmission and converting the output of the transmission into forward power and reverse power.
A rear wheel differential mechanism provided behind the transmission and transmitting the output of the forward / backward switching device to the rear wheels.
A gear transmission mechanism that transmits the power of the output shaft of the forward / backward switching device to the input shaft of the rear wheel differential mechanism, and
A transmission, a forward / backward switching device, a rear wheel differential mechanism, and a transmission case for accommodating the gear transmission mechanism are provided.
The mission case is configured to be separable into a front case portion accommodating the transmission and a rear case portion accommodating the forward / backward switching device, the rear wheel differential mechanism, and the gear transmission mechanism.
The gear transmission mechanism is a traveling transmission device for a tractor that is detachably provided in a portion of the inside of the mission case corresponding to the front end portion of the rear case portion. A front wheel transmission mechanism provided inside the mission case and outputting power from the forward / backward switching device toward the front wheels.
A second gear transmission mechanism, which is detachably provided at a portion of the inside of the transmission case corresponding to the front end portion of the rear case portion and inputs power from the forward / backward switching device to the front wheel transmission mechanism, is used. The traveling transmission device for a tractor according to claim 1. The traveling transmission device for a tractor according to claim 2, wherein the second gear transmission mechanism is configured to input the power of the output shaft of the rear wheel differential mechanism to the front wheel transmission mechanism. The method according to any one of claims 1 to 3, wherein the rear case portion can be divided into a front end portion of the rear case portion and a portion of the rear case portion other than the front end portion. Tractor travel transmission. In the transmission, the power of the engine is input, and the hydrostatic type stepless speed change unit that shifts and outputs the input power, and the power of the engine and the output of the stepless speed change unit are input. , A compound planetary transmission unit that combines the input power and the output to output the combined power.
In the compound planetary transmission unit, the axis of the sun gear in the compound planetary transmission unit and the axis of the output shaft of the engine are located in a straight line, and the axis of the sun gear is the rear wheel differential mechanism. The traveling transmission device for a tractor according to claim 1, which is arranged so as to be located above the axis of the input shaft of the above. A stepwise transmission unit is provided which outputs the combined power output by the composite planetary transmission unit in stages in a plurality of speed ranges.
The traveling transmission device for a tractor according to claim 5, further comprising a lubrication unit that discharges lubricating oil toward the stepwise transmission unit. A continuously variable output gear rotatably provided at the front of the continuously variable transmission with the front-rear axis as the center of rotation.
A planetary input gear rotatably provided at the front of the composite planetary transmission unit,
A power transmission mechanism for transmitting the power of the stepless output gear to the planetary input gear is provided.
The power transmission mechanism makes it impossible to rotate relative to the rear end portion of the relay shaft in a state of being meshed with the rotatable front-rear relay shaft provided parallel to the front-rear shaft core and the stepless output gear. The fifth or sixth aspect of claim 5 or 6, further comprising a first relay gear provided and a second relay gear provided at the front end of the relay shaft so as not to rotate relative to the front end of the relay shaft in a state of meshing with the planetary input gear. Travel transmission device for tractors. A rotating shaft that is interlocked with the output shaft of the engine and is passed through the shaft core of the composite planetary transmission unit in the front-rear direction.
A continuously variable input gear rotatably provided at the rear of the continuously variable transmission with the front-rear axis as the center of rotation.
A second power transmission mechanism that transmits the power of the rotating shaft to the stepless input gear is provided.
The second power transmission mechanism includes a rotatable second relay shaft provided parallel to the front-rear axis and a power provided behind the composite planetary transmission portion so as not to rotate relative to the rotation shaft. The take-out gear, the third relay gear provided at the rear end of the second relay shaft so as not to rotate relative to the power take-out gear, and the second relay shaft in a state of meshing with the stepless input gear. The traveling transmission device for a tractor according to any one of claims 5 to 7, further comprising a fourth relay gear provided at a front end portion so as not to rotate relative to each other. A mission case where the power from the engine is input by the input shaft,
A speed change transmission unit provided inside the mission case, in which power from the input shaft is input, and the input power is changed and output.
A rear wheel differential mechanism provided inside the transmission case, in which power output from the transmission transmission unit is input and the input power is transmitted to the left and right rear wheels is provided.
The transmission transmission unit is provided with a plurality of transmission units that shift and output power from the input shaft by a gear interlocking mechanism and a multi-plate clutch in a state of being lined up in the front-rear direction of the transmission case.
An oil supply pipe provided inside the transmission case so as to extend in a direction extending in a direction in which the plurality of transmission units are lined up above the transmission transmission unit.
The oil supply pipe is provided with a discharge nozzle that is connected to a portion of each of the plurality of transmissions corresponding to the gear interlocking mechanism and discharges lubricating oil from the oil supply pipe toward the gear interlocking mechanism. The running transmission device of the tractor. The traveling transmission device for a tractor according to claim 9, wherein the refueling pipe is integrally molded with the mission case. The traveling transmission device for a tractor according to claim 9 or 10, wherein the output shaft of the speed change transmission unit is arranged at a position higher than the input shaft of the rear wheel differential mechanism. The traveling transmission device for a tractor according to any one of claims 9 to 11, wherein the output shaft of the transmission transmission unit is arranged at a position higher than the standard oil level of the lubricating oil stored in the mission case. The traveling transmission device for a tractor according to any one of claims 9 to 12, wherein the discharge nozzle is provided with an orifice.

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