JPH0939825A - Traveling device of working vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cope with vehicle automatic steering in accordance with a sensor signal without trouble while securing a straight advance property of a vehicle in a traveling device provided with two sets of hydraulic drives. SOLUTION: Steering of a vehicle is carried out by giving additional rotation in the left and right reverse direction by a hydraulic motor 25 of a second hydraulic transmission 23 to left and right traveling drive shafts driven by a hydraulic motor 22 of a first hydraulic drive 20 and to travel the vehicle. An electromagnetic directional changeover valve 91 capable of selectively supplying working oil from an oil feeding and discharging circuit 81A to be the high pressure side at the time when the vehicle advances in the first hydraulic drive to each of oil feeding and discharging circuits 86A, 86B of the second hydraulic drive is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traveling device for a working vehicle such as a combine, which uses two sets of hydraulic transmission devices to drive and turn the vehicle.

[0002]

BACKGROUND OF THE INVENTION A traveling device for such a work vehicle is disclosed, for example, in Japanese Examined Patent Publication No. 54-34972 and JP-A-6-3433.
It is already known as disclosed in Japanese Patent Publication No. 2 and Japanese Patent Publication No. 7-2468. In addition, such a vehicle traveling device is combined with an automatic steering mechanism that automatically corrects the traveling direction of the work vehicle based on a signal from a sensor that detects a left-right deviation of the vehicle by contacting a row of grains and the like. The technique is also well known as disclosed in, for example, Japanese Patent Laid-Open No. 2-70597.

In these known techniques, one of two sets of hydraulic transmissions or a hydraulic motor thereof is used to drive a left-side final traveling drive means (crawler or wheel) and another set of hydraulic transmissions is used. Using the hydraulic transmission or its hydraulic motor to drive the right-hand final travel drive means (crawlers or wheels), the turning of the vehicle depends on the output speed of one set of hydraulic transmissions and the other set of hydraulic transmissions. In this case, a difference is made between the output speeds of the vehicle and the left and right final traveling drive means so as to obtain the rotation speeds. Therefore, a complicated control device is required in order to ensure the straightness of the vehicle. In other words, according to the structure in which the right and left final traveling drive means are driven by separate left and right hydraulic transmissions or their hydraulic motors, the left and right final imbalances due to the left and right imbalance of the vehicle load and the left and right imbalance of the running resistance in the field scene. It was difficult to obtain a constant speed rotation of the traveling drive means, and thus a complicated control device for detecting and correcting the difference between the left and right rotational speeds was required.

Further, according to the above-mentioned structure, it is not possible to provide another stepped transmission for setting the vehicle speed range of the vehicle. That is, the hydraulic transmission device is used in a high speed shift range that provides high output rotation, the output rotation speed is stable, and the working vehicle is relatively high speed when traveling on the road, relatively low speed when working in a field or the like, In consideration of the fact that each can be driven, it is desirable to obtain a setting of the vehicle speed range in accordance with such driving conditions with the stepped transmission, and to use the hydraulic transmission in a high speed shift range. According to the structure using the left and right hydraulic transmissions, it is not possible to provide a single stepped transmission for setting the vehicle speed range on the driven side of the two sets of hydraulic transmissions.

In view of the above, the invention is different from the prior art in that one of the two hydraulic transmissions is used for driving and the other hydraulic transmission is used for driving the vehicle. It is intended to provide a novel traveling device for a working vehicle, which is used for the purpose of solving various problems of the conventional device and being able to cope with automatic vehicle steering based on a sensor signal without any problem.

[0006]

SUMMARY OF THE INVENTION Therefore, in the traveling apparatus for a working vehicle according to the present invention, a variable displacement hydraulic pump 21 and a constant displacement hydraulic motor 22 are provided as a pair of oil supply / discharge circuits 81A, 81B.
The hydraulic motor of the first hydraulic transmission device 20 connected by means of the above is interlockingly connected to the left and right traveling drive shafts 30L and 30R that are transmitted to the left and right final traveling drive means 1. In addition, the variable displacement hydraulic pump 24 and the constant displacement hydraulic motor 25 are connected to each other by a pair of oil supply / discharge circuits 86A and 86B. , 30R are interlockingly connected to the left and right traveling drive shafts via an additional rotation transmission device 36 capable of applying additional rotations in opposite directions. Then, one of the pair of oil supply / drain circuits of the pair of oil supply / drain circuits 86A and 86B of the second hydraulic transmission 23 is connected to the pair of oil supply / drain circuit of the first hydraulic transmission 20. In the oil supply / drain circuit 81A that is on the high pressure side when the vehicle is moving forward, and the other oil supply / drain circuit of the second hydraulic transmission device 23 is connected to the vehicle forward of the pair of oil supply / drain circuits of the first hydraulic transmission device 20. Oil supply / discharge circuit 81, which is sometimes on the low pressure side
B is provided with an electromagnetic direction switching valve 91 that can be selectively connected.

According to the present invention, the driving drive of the vehicle is the first
Is obtained by driving the left and right traveling drive shafts 30L and 30R by the hydraulic motor 22 of the hydraulic transmission 20 of FIG. By the change control, the vehicle speed including the traveling direction of the vehicle can be continuously changed and controlled. Turning the vehicle while the vehicle is running activates the second hydraulic transmission device 23 to operate the hydraulic motor 25 of the hydraulic transmission device 23.
By performing additional rotation in the opposite directions to the left and right traveling drive shafts 30L and 30R that are rotating at a constant speed through the additional rotation transmission device 36. That is, depending on the additional rotations in the opposite directions, the left and right traveling drive shafts 30L,
Since the rotational speed of one of the 0R is increased and the rotational speed of the other is decreased, the rotational speed difference is given to the left and right traveling drive shafts 30L and 30R, and thus to the left and right final traveling drive means 1, and the vehicle is Will turn. Then, by the volume change control of the hydraulic pump 24 of the second hydraulic transmission device 23, it is possible to freely change the direction and the number of rotations of the additional rotation in the opposite directions given to the left and right traveling drive shafts 30L and 30R. It is possible to cause the vehicle to turn in any direction and with any turning radius during both forward movement and reverse movement.

The automatic steering of the vehicle as described above can be dealt with as follows. That is, while the automatic steering control is performed when the vehicle moves forward, the present invention uses the electromagnetic directional control valve 91 to cause the first hydraulic power transmission device 20 that drives the vehicle to travel so that the oil pressure becomes high when the vehicle moves forward. The supply / discharge circuit 81A is connected to one of the oil supply / discharge circuits of the second hydraulic transmission device 23, and the other oil supply / discharge circuit of the hydraulic transmission device 23 is connected to the low-pressure side of the first hydraulic transmission device 20. It is possible to connect to the oil supply / drainage circuit 81B which has become. Therefore, the hydraulic pump 24 of the second hydraulic transmission 23 is set in a neutral state, and the electromagnetic directional control valve 91 is used to change the oil supply / discharge circuit 81A from the high-pressure side oil supply / discharge circuit to either one of the second hydraulic transmission 23. When the high-pressure hydraulic oil is supplied, the hydraulic oil drives the hydraulic motor 25 of the second hydraulic transmission device 23, and then the low-pressure side oil supply / discharge circuit from the other oil supply / discharge circuit of the second hydraulic transmission system 23. It will be returned to the circuit 81B. Therefore, the hydraulic motor 25 of the second hydraulic transmission device 23 for steering is controlled by the electromagnetic directional control valve 91.
Can be driven in any direction, which allows the left and right traveling drive shafts 30L, 30 to pass through the additional rotation transmission device 36.
It is possible to correct the traveling direction of the vehicle by giving R an additional rotation in a direction opposite to the left turning direction and the right turning direction of the vehicle. That is, if the position control of the electromagnetic directional control valve 91 is performed based on the signal of the sensor that detects the left-right deviation of the vehicle, the automatic steering control of the vehicle can be dealt with.

In the present invention, the vehicle is driven and driven by the single hydraulic transmission 20, so that the left and right traveling drive shafts 30L, 30 are driven by the hydraulic transmission 20.
Since R is driven at a constant speed, the straightness of the vehicle is ensured without providing any other control mechanism. Since it is possible to provide a stepped transmission in series connection with the single hydraulic transmission 20 for driving the vehicle, there is no problem. Therefore, such a stepped transmission is provided to set the vehicle speed range. It is assumed that the first hydraulic transmission device 20 can be used in a high speed shift range where the rotation speed is stable, which is obtained by the transmission device.

As described above, the automatic steering of the vehicle based on the sensor signal can be immediately dealt with, and for the automatic steering, the oil supply / exhaust circuit 81A on the high pressure side of the first hydraulic transmission 20 is used. Since the hydraulic oil is taken out and the hydraulic motor 25 of the second hydraulic transmission device 23 is driven, it is assumed that control with high responsiveness that responds quickly to the sensor signal is achieved.

The first hydraulic transmission device 20 during automatic steering control
In order to eliminate the possibility that a sudden change in hydraulic pressure will occur due to the above-mentioned removal of hydraulic oil in the high pressure side oil supply / discharge circuit 81A, and the vehicle running state will change, the electromagnetic directional control valve 91 is used. It may be configured to have orifices 94A, 94B for narrowing the connection oil passage between the circuit 81A and the oil supply / discharge circuits 86A, 86B of the second hydraulic transmission 23.

Other features and advantages of the present invention can be clearly understood from the following description with reference to the accompanying drawings.

[0013]

FIG. 2 shows a combine equipped with an embodiment of the traveling device according to the invention. The illustrated combine is driven and driven by the left and right crawlers 1 as usual, cuts the planted grain culm in the cutting section 2 in front of the machine body, threshes the cut culm in the threshing section 3 on the machine body, and removes the grain. It is stored in the grain tank 4 on the fuselage, and the waste straw is a waste straw processing device at the rear of the fuselage (bundling, bundling, cutter device or a switchable combination thereof).
5 is performed. The engine 6 is installed near the body, and a transmission 7 that receives input power from the engine is arranged at a lower front position of the engine 6. A control unit 9 having a seat 8 is disposed on the upper front side of the engine 6. The control unit 9 includes a steering wheel 10 for steering a vehicle, a main speed change lever 11 and a sub speed change lever 12 for controlling a vehicle speed, a parking brake lever 13, and the like. In FIG. 2, 14 is an axle equipped with a crawler drive wheel 15, 16 is a cutting blade, and 17 is a grain lifting device for discharging grains from the grain tank 4.

FIG. 3 shows the transmission mechanism provided in the combine of FIG. 2 with omitting the transmission mechanism to the reaping section 2 and the threshing section 3 described above. As shown in FIG. 5, which will be described later, the transmission 7 is provided with two variable displacement hydraulic pumps 21 and 24 having an input shaft 19 driven by the engine 6 as a pump shaft. As shown, an input pulley 26 is fitted on the input shaft 19, and an input transmission from the output pulley 6a of the engine 6 to the input shaft 19 is performed by a belt 27. As shown in FIG. 3, the hydraulic pump 21 and a constant displacement hydraulic motor 22 are connected by a pair of oil supply / discharge circuits, and a first hydraulic transmission device 20, and the hydraulic pump 24 and a constant displacement hydraulic pressure are connected. A second hydraulic transmission device 2 in which a motor 25 is connected by a pair of oil supply / discharge circuits.
3 are provided. Of these, the first hydraulic transmission 2
Numeral 0 is used for traveling driving of the combine, and the second hydraulic transmission 23 is used for steering of the combine.

More specifically, similarly, as shown in FIG. 3-5, the main drive shaft 29 for traveling and the left and right traveling drive shafts 30L and 30R are provided concentrically with each other, and the left and right traveling drive shafts are provided. 30L and 30R are interlockingly connected to the left and right axles 14 via left and right gears 31 and 32 reduction mechanisms. The main drive shaft 29 is connected to the left and right traveling drive shafts 30L and 30R through left and right planetary gear units 33L and 33R for deceleration, and an output rotationally driven by the hydraulic motor 22 in the first hydraulic transmission device 20. The shaft 34 is connected to the main drive shaft 29, and the vehicle is driven to travel by the first hydraulic transmission 20. Then, the second hydraulic transmission device 23 includes an output shaft 35, which is rotationally driven by a hydraulic motor 25 in the device 23, on the left and right traveling drive shafts 30.
Left and right traveling drive shafts 30L and 30R with respect to L and 30R
Are connected to each other by an additional rotation transmission device 36 for applying additional rotations in opposite directions to each other, and the left and right traveling drive shafts 30L, 3 are rotationally driven by the main drive shaft 29 at the same speed.
The vehicle is steered by making the rotational speeds of 0R different from each other.

An input gear 38 is fixedly installed on the main drive shaft 29, and the output shaft 34 of the first hydraulic transmission 20 is interlocked with the input gear 38 by the transmission mechanism shown in FIG. The transmission mechanism includes a gear 39,
The intermediate shaft 4 is driven by the clutch shaft 41 through the multi-plate clutch 42 provided on the clutch shaft 41 and the gears 43 and 44.
5, including a subtransmission 47 disposed between the intermediate shaft 45 and the subtransmission shaft 46 at the next stage. The sub-transmission 47 is provided with a shift gear 48 slidably provided on the intermediate shaft 45, two gears 49 and 50 loosely installed on the coaxial 45, and a shift gear 48 fixedly installed on the auxiliary transmission shaft 46. Meshable gear 51,
And two gears 52 and 53 which are fixedly installed on the coaxial 46 and mesh with the gears 49 and 50. A shift gear 48 is provided between the shift gear 48 and the gears 49 and 50, respectively.
, The auxiliary transmission 47 is connected to the auxiliary transmission shaft 46.
That can be switched to three speeds: a road speed for rotating the vehicle at a relatively high speed, a speed for a dry field operation at a first low speed, and a lower speed for a wet field operation at a second lower speed. It has been. The gear 53 for the shift speed at the time of wetland operation on the sub-transmission shaft 46 is
The auxiliary transmission shaft 46 is provided with a parking brake 54. The sub-transmission 47 and the parking brake 54 are respectively connected to the sub-transmission lever 12 shown in FIG.
And is operated by the parking brake lever 13. In order to operate the clutch 42, a pedal 55 shown in FIG. 2 is provided.

FIG. 4 shows the lower part of the transmission 7 in the transmission case 56, in which the left and right planetary gear units 33L, 33R connecting the main drive shaft 29 and the left and right traveling drive shafts 30L, 30R are arranged. ing. Each of the planetary gear devices 33L and 33R is fixedly supported by a sun gear 57 integrally formed with the main drive shaft 29, an internal gear 58 provided at an outer peripheral position of the sun gear 57, and each of the traveling drive shafts 30L and 30R. A plurality of (three) planetary gears 60 rotatably supported by a carrier 59 and engaged with the sun gear 57 and the internal gear 58. Each of the left and right carriers 59 has a ring 59a arranged on the input gear 38 side.
Are connected via a spacer 59b and a bolt 59c, and a pin 59d secured by a ring 59a is provided, and a planetary gear 60 is freely rotatably provided on the pin 59d.

Each inner tooth wheel 58 is formed on the inner surface of a ring 61 arranged on the outer peripheral side of the sun gear 57, and the left and right rings 61 are particularly supported as follows. That is, the left and right rings 61 are connected to the left and right traveling drive shafts 30L, 30L.
Inner teeth 61a formed on the inner peripheral surface of the ring 61 and bosses of the gear 63 are formed on the left and right gears 63, which are loosely installed on the R through a boss of the carrier 59 and a pair of ball bearings 62. The gear 63 is engaged with the external teeth 63a.
It is supported so as to be rotationally displaceable. Each ring 61
Is supported so as to be movable in the radial direction with respect to the gear 63 by making the pin 64 inserted into the ring 61 abut against the side surfaces of the internal teeth 61 a and the external teeth 63 a to prevent the ring 61 from being removed. Thereby, power is equally distributed to the plurality of planetary gears 60.

5 and 6 show the additional rotation transmission device 36 for transmitting additional rotation from the output shaft 35 of the second hydraulic transmission device 23 to the left and right traveling drive shafts 30L and 30R.
Shows. The device 36 includes an intermediate shaft 66 and a lock shaft 67 that are parallel to the output shaft 35, and the output shaft 35 and the intermediate shaft 66.
The sections are connected by rows of reduction gears 68, 69. Between the intermediate shaft 66 and the lock shaft 67, reduction gears 70, 71
Connected by columns. The left and right rings 61 are rotated at equal speeds in opposite directions by the lock shaft 67 by using the right and left gears 63 between the lock shaft 67 and the rings 61 of the left and right planetary gear units 33L and 33R. Connected. That is, the gear 63 integrally formed with the gear 71 and fitted to the lock shaft 67 meshes with the gear 63 rotating integrally with the left ring 61, and the gear 63 integrally rotates with the ring 61. Lock shaft 6
1 is meshed with an idler gear 75 on an idler shaft 74 via an idler gear 75, and the left gears 72, 63
The reduction ratio of the train and the reduction ratio of the gears 73, 75, 63 on the right side are set to be equal.

By providing the left and right rings 61 with rotations in opposite directions to each other, the main drive shaft 29 is rotationally driven by the left and right planetary gear units 33L and 33R as will be described later. Since the left and right traveling drive shafts 30L and 30R can be additionally rotated in the left and right directions, the vehicle can be turned by changing the rotational speeds of the left and right traveling drive shafts 30L and 30R. It will be. When the second hydraulic transmission device 23 or its hydraulic pump 24 is in a neutral state and the output shaft 35 is not rotated, if the left and right rings 61 are to be rotationally displaced at the same speed in the same direction, the rotational displacement is locked. Axis 67
To the lock shaft 6
7 does not rotate in any direction, and conversely, the left and right rings 61 are non-rotatably locked by the lock shaft 67.

As shown in FIG. 5, the mission case 5
A thick plate member 77 projecting upward is attached to one side surface of the upper end portion of 6, and housings 78 and 79 are attached to one side surface and the other side surface of the plate member 77.
The transmission input shaft 19 includes both housings 78 and 7.
9 and the plate member 77 are provided so as to penetrate therethrough, and the hydraulic pump 2 using the input shaft 19 as a pump shaft as described above.
1, 24 are arranged in housings 78, 79 and mounted on the plate member 77. These hydraulic pumps 2
The pump swash plates 21a and 24a of Nos. 1 and 24 are respectively shown in FIG.
The tilting operation is performed by the main shift lever 11 and the steering wheel 10 described above. The hydraulic motor 2
2, 25 are arranged in the housing 79 and mounted on the plate member 77, as shown for the hydraulic motor 25 in FIG.

FIG. 1 shows first and second hydraulic transmissions 20,
23 is shown in a hydraulic circuit diagram. 81 in FIG.
A and 81B are the hydraulic pump 21 of the first hydraulic transmission device 20.
And a pair of oil supply / discharge circuits for connecting the hydraulic motor 22 and the hydraulic motor 22,
Is a charge pump connected to the circuits 81A and 81B through a pair of check valves 83 to replenish the working oil, 84 is a relief valve for setting the hydraulic pressure of the replenished working oil, and 85 is a pair of oil supply / discharge. It is a relief valve that sets the hydraulic pressure of the circuit on the high pressure side of the circuits 81A and 81B. Also 86A, 86B
Is a pair of oil supply / discharge circuits connecting the hydraulic pump 24 and the hydraulic motor 25 of the second hydraulic transmission 23, and 87 is the circuit 8
6A, 86B is connected via a pair of check valves 88 to replenish the working oil, 89 is a relief valve for setting the hydraulic pressure of the replenished working oil, 90 is a pair of oil supply / discharge circuits 86A, It is a relief valve for setting the hydraulic pressure of the circuit on the high pressure side of 86B.

In the first hydraulic transmission 20, when the vehicle is driven to travel in the forward direction by the transmission 20, the high pressure side is the oil supply / discharge circuit 81A, and the low pressure side is the oil supply / discharge circuit 81B. However, the automatic steering based on the sensor signal during forward traveling of the combine drives the hydraulic motor 25 of the second hydraulic transmission device 23 by the hydraulic pressure of the high-pressure side oil supply / discharge circuit 81A of the first hydraulic transmission device 20. In order to obtain this, an electromagnetic directional control valve 91 is provided as shown in FIG. The electromagnetic direction switching valve 91 is configured as a 4-port / 3-position valve, and the oil supply port provided on the first hydraulic transmission 20 side is connected to the oil supply / discharge circuit 81A by the oil supply circuit 92A, and the oil discharge port is connected to the oil supply port. The return circuit 92B is connected to the oil supply / discharge circuit 81B. The pair of oil supply / discharge ports provided on the second hydraulic transmission 23 side are connected to the pair of oil supply / discharge circuits 86A, 86B of the transmission 23 by a pair of connection circuits 93A, 93B. is there.

The electromagnetic directional control valve 91 connects the oil supply circuit 92A, the oil return circuit 92B and the connecting circuit 93A with the neutral position N shown in FIG. To the oil return circuit 92B and a left turn position L to connect the oil supply circuit 92A to the connection circuit 93B and to connect the connection circuit 93A to the oil return circuit 92B.
And Therefore, while the vehicle is traveling forward, the second
When the electromagnetic directional control valve 91 is displaced to the right turning position R while the pump swash plate 24a of the hydraulic transmission 23 is kept at the neutral position, the high pressure in the oil supply / discharge circuit 81A of the first hydraulic transmission 20 is increased. The hydraulic oil is supplied to the oil supply / discharge circuit 86A of the second hydraulic transmission device 23, the hydraulic motor 25 is rotationally driven in one direction (the vehicle turning right direction), and the oil flows out to the oil supply / discharge circuit 86B. The oil is returned to the oil supply / discharge circuit 81B on the low pressure side of the first hydraulic transmission 20. Similarly, when the electromagnetic direction switching valve 91 is displaced to the left turning position L, the oil supply / discharge circuit 81
The high-pressure hydraulic oil in A is supplied to the oil supply / discharge circuit 86B of the second hydraulic transmission device 23, the hydraulic motor 25 is driven in the other direction (the vehicle left turn direction), and the first oil supply / discharge circuit 86A is operated. Oil is returned to the oil supply / discharge circuit 81B of the hydraulic transmission 20. The electromagnetic directional control valve 91 is provided with orifices 94A and 94B (which may be combined into one orifice) for appropriately narrowing the oil passage that connects the oil supply circuit 92A and the connection circuits 93A and 93B. The sudden oil pressure fluctuation is prevented from occurring in the oil supply / discharge circuit 81A of the first hydraulic transmission device 20.

The electromagnetic directional control valve 91 includes a solenoid 91a,
The solenoids 91a, 9a are moved to the right turning position R and the left turning position L by excitation of 91b.
1b is to be excited and demagnetized depending on the presence or absence of a sensor signal. That is, as schematically shown in FIG. 2, the left and right steering sensor switches 95 are attached to the right and left grass bodies of the mowing unit 2.
L and 95R are provided, and these sensor switches 95
When L and 95R come into contact with the left and right planted culms, they are turned on to detect the deviation of the combine in the left and right direction. When the left steering sensor switch 95L is turned on, the solenoid 91a is excited to displace the electromagnetic directional control valve 91 to the right turning position R, and the solenoid 91a.
b is excited when the right steering sensor switch 95R is turned on to displace the electromagnetic directional control valve 91 to the left turning position L.

FIG. 7 shows an outline of the steering control mechanism.
The steering sensor switch 95 is provided on the input side of the controller 96.
In addition to L and 95R, a manual steering switch 97, an automatic steering selection switch 98 and an alignment switch 99 are connected, and an swash plate operating actuator 100 is connected to the output side in addition to the solenoids 91a and 91b. . Of these, the manual steering switch 97 detects that the steering wheel 10 has been operated in order to prioritize the manual steering, and is attached to the handle shaft of the wheel 10 as shown in FIG. The automatic steering selection switch 98 is turned on by the operator to select the automatic steering control, and is arranged in the steering section 9 as shown in FIG. As shown in FIG. 2, the alignment switch 99 is used for the steering wheel 10
When the aircraft is not properly traveling along the planted grain culm after turning the combine on the headland etc. in the field, the operator can operate in one direction or the other direction. It is used to correct the direction of travel. The swash plate operating actuator 100 tilts the pump swash plate 24a of the second hydraulic transmission 23 by operating the steering wheel 10. As shown in FIG.
a.

In the control device 96 shown in FIG. 7, first, when the manual steering switch 97 is turned on, the solenoid 91a,
Unless the automatic steering selection switch 98 is turned on, the solenoids 91a and 91b are de-energized unless demagnetized. When the automatic steering selection switch 98 is turned on, the control device 96 operates the swash plate operating actuator 100 so that the pump swash plate 24a returns to the neutral position, and the steering sensor switch 95L,
The solenoids 91a and 91b are subjected to the demagnetization control as described above by the signal from the 95R. Further, the control device 96 causes the solenoid 91a to operate when the alignment switch 99 is operated in one direction while the automatic steering is selected.
Is excited, and the solenoid 91b is excited when operated in the other direction.

The combine shown in FIG. 2 is operated by the auxiliary transmission lever 12 in accordance with the traveling conditions of the combine, and the auxiliary transmission 47 shown in FIG.
A high speed is selected when traveling on the road, a first low speed is selected during dry field work, and a second lower speed is selected during wet field work, and the first hydraulic transmission device 20 shown in FIGS. The vehicle swash plate 21a is operated to continuously change and control the vehicle speed including the control of the traveling direction so that the vehicle can travel. When the vehicle goes straight, the pump swash plate 24a of the second hydraulic transmission 23 shown in FIGS. 1 and 5 is not operated by the steering wheel 10, and the hydraulic transmission 23 is maintained in the neutral state. The rings 61 of the left and right planetary gear units 33L and 33R are constrained by a lock shaft 67 so that they cannot be rotationally displaced. For the lock of the left and right rings 61 that cannot be rotationally displaced, a worm transmission mechanism is provided in the left and right transmission mechanisms that are transmitted to the left and right rings 61 to disable reverse rotation transmission from the left and right rings 61. Can also be obtained by

8L and 8R schematically show the left and right planetary gear units 33L and 33R. When the hydraulic motor 22 of the first hydraulic transmission 20 is rotating forward, the sun gear 57 rotates in the direction of arrow A, whereby each planetary gear 60 rotates in the direction of arrow B while rotating in the direction of arrow C. At 9, the carrier 59 rotates while rotating the carrier 59 (not shown). In this case, the number of rotations R given to the carrier and each of the traveling drive shafts 30L and 30R is assumed to be 1 with respect to the number of rotations of the sun gear 57.
The number of teeth of the sun gear 57 is N ₁ , and the number of teeth of the internal toothed wheel 58 is N ₂
Then, since R = N ₁ / (N ₁ + N ₂ ), a large deceleration can be obtained by appropriately setting the number of teeth N ₂ . When the hydraulic motor 22 rotates in the reverse direction, only the rotation direction is reversed, and the situation is the same as described above.

While the vehicle is moving forward, the steering wheel 10
Is operated to rotate the actuator 100, and the actuator 100 shown in FIGS.
When the pump swash plate 24a of the second hydraulic transmission device 23 is tilted and the hydraulic motor 25 is rotated in the normal rotation direction, the additional rotation transmission device 36 shown in FIGS. The ring 61 of the left planetary gear set 33L is rotated in the direction of the arrow D ₁ via the right side planetary gear set 33L via the right gears 73, 75 and 63 rows.
The R ring 61 is given rotation in the direction of arrow D ₂ .
Depending on the rotation of the left ring 61 in the direction of the arrow D ₁ , the number of rotations of the planetary gear 60 in the direction of the arrow C by the rotation speed thereof, that is, the left carrier 59 and the traveling drive shaft 30L.
The number of rotations is reduced, and conversely the arrow D ₂ on the right ring 61
Depending on the rotation in the direction, the planetary gear 6
0 in the direction of arrow C, and thus the right carrier 5
9 and the rotational speed of the traveling drive shaft 30R are increased. Therefore, the vehicle is turned to the left, and its turning radius can be freely selected by adjusting the operation amount of the steering wheel 10 and controlling the rotational speed of the hydraulic motor 25. A right turn while the vehicle is moving forward and a left or right turn while moving backward can be obtained in a similar manner.

The automatic steering selection switch 98 shown in FIGS.
When the automatic steering control is selected by, the pump swash plate 24a of the second hydraulic transmission device 23 is moved to the neutral position, and
Solenoids 91a, 91b due to the left-right bias of the combine sensed by the steering sensor switches 95L, 95R.
Is selectively excited, the electromagnetic directional control valve 91 is moved to the right turning position R or the left turning position L, and the first hydraulic power transmission device 20
The hydraulic motor 25 of the second hydraulic transmission device 23 is rotationally driven in one direction or the other direction by the high pressure hydraulic oil supplied from the oil supply / discharge circuit 81A on the high pressure side in FIG. Left and right traveling drive shafts 30L, 30
Since the additional rotations in opposite directions are given to R, the traveling direction of the combine is automatically corrected by this. This correction is performed by the oil supply / discharge circuit 8 of the first hydraulic transmission 20.
The second hydraulic power transmission device 2 is configured to take out high-pressure hydraulic oil from 1A.
3 to drive the motor 25 by supplying it to the hydraulic motor 25, the steering sensor switches 95L, 95
It is performed promptly in response to the signal input from R.

The operation at the time of alignment performed by selectively exciting the solenoids 91a and 91b by the alignment switch 99 shown in FIGS. 2 and 7 is also exactly the same as described above.

As in the above-described embodiment, the additional rotation transmission device 36 is configured to give additional rotation in opposite directions to the left and right traveling drive shafts 30L and 30R via the left and right planetary gear units 33L and 33R. In this case, as described above, the rotation of the hydraulic motor 25 is transmitted to the left and right internal tooth wheels 58 or the rings 61 thereof, and the hydraulic motor 25 is transmitted to the left and right sun gears 57 or the left and right carriers 59.
May be transmitted. FIG. 9 schematically shows such another example.

In the embodiment of FIG. 9, the left and right planetary gear units 33L, 33R arranged between the main drive shaft 29 and the left and right traveling drive shafts 30L, 30R respectively drive the ring 61 forming the internal tooth wheel 58. A carrier 59 that is fixed to the shaft 29 and that supports a plurality of planetary gears 60 is mounted on each traveling drive shaft 30L,
Fixed to 30R, the sun gear 57 is attached to each traveling drive shaft 30L,
A gear 63 corresponding to the gear 63 is provided integrally with the sun gear 57 by being loosely fitted on the 30R. The intermediate shaft 66
And the additional rotation transmission device 36 shown without the gear 69 above the lock shaft 6
It is configured to be transmitted to the left and right gears 63 by a gear train that reverses rotation from 7 to the left and right. In the present embodiment, the left and right sun gears 57 are rotated in opposite directions to give additional rotations in opposite directions to the left and right traveling drive shafts 30L and 30R. The additional rotation that has been greatly decelerated is given to the traveling drive shafts 30L and 30R, and there is a real advantage that the vehicle can gradually make a sharp turn from a gentle turn according to the turning angle of the steering wheel 10. The stepped transmission 4 provided in the same manner as in the above embodiment
7 is shown only as a block.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram showing an embodiment.

FIG. 2 is a schematic side view of a combine equipped with the embodiment.

FIG. 3 is a mechanism diagram showing a transmission mechanism provided in the combine.

FIG. 4 is a longitudinal sectional rear view showing a part of a transmission provided in the combine.

FIG. 5 is a partially omitted vertical sectional rear view of the transmission cut along another vertical section.

FIG. 6 is a longitudinal sectional view showing a part of the transmission.

FIG. 7 is a block diagram showing an outline of a steering control mechanism.

FIG. 8 is a schematic diagram for explaining the operation of the planetary gear device provided in the embodiment.

FIG. 9 is a mechanism diagram schematically showing an embodiment according to some modifications.

[Explanation of symbols]

 1 Crawler 6 Engine 19 Input Shaft 20 First Hydraulic Transmission Device 21 Hydraulic Pump 22 Hydraulic Motor 23 Second Hydraulic Transmission Device 24 Hydraulic Pump 25 Hydraulic Motor 29 Main Drive Shaft 30L, 30R Traveling Drive Shaft 33L, 33R Planetary Gear Device 34 Output shaft 35 Output shaft 36 Additional rotation transmission device 63 Gear 67 Lock shaft 72 Gear 73 Gear 74 Idler gear 81A, 81B Oil supply / discharge circuit 91 Electromagnetic directional control valve 91a, 91b Solenoid 92A Oil supply circuit 92B Oil return circuit 93A, 93B Connection circuit 94A, 94B Orifice 95L, 95R Steering sensor switch

Claims (2)

[Claims] 1. A variable displacement hydraulic pump (21) and a constant displacement hydraulic motor (22) as a pair of oil supply / discharge circuits (81A,
81B) connects the first hydraulic transmission device (2
The left and right traveling drive shafts (30L, 30R) for transmitting the hydraulic motor of 0) to the left and right final traveling drive means (1)
A second hydraulic transmission device (a hydraulic displacement pump (24) and a constant displacement hydraulic motor (25) are connected to each other by a pair of oil supply / discharge circuits (86A, 86B). The hydraulic motor of 23) is interlockingly connected to the left and right traveling drive shafts via an additional rotation transmission device (36) capable of imparting opposite rotations to the left and right traveling drive shafts. The pair of oil supply / discharge circuits (86A,
86B), one of the oil supply / exhaust circuits is connected to the oil supply / exhaust circuit (81A) which becomes the high pressure side when the vehicle is moving forward, of the pair of oil supply / exhaust circuits of the first hydraulic transmission, and the second oil supply / exhaust circuit. The other oil supply / exhaust circuit of the hydraulic transmission of No. 1 is selectively connected to the oil supply / exhaust circuit (81B) of the pair of oil supply / exhaust circuits of the first hydraulic transmission that is on the low pressure side when the vehicle travels forward. A traveling device for a work vehicle provided with an electromagnetic directional control valve (91) that enables it. 2. The electromagnetic directional control valve (91) is connected to the high pressure side oil supply / discharge circuit (81A) and a second hydraulic power transmission device (2).
The traveling apparatus for a work vehicle according to claim 1, which is configured to have an orifice (94A, 94B) for narrowing a connection oil passage between the oil supply / discharge circuits (86A, 86B) of 3).