JPH10100930A - Steering gear for working vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain vehicle steering by a reversible continuously variable transmission which is independent of a shift travel-driving mechanism to achieve exact vehicle steering conforming to the purpose of turning a vehicle while optionally structuring the shift travel-driving mechanism. SOLUTION: A reversible continuously variable transmission 23 which is shift operated by a steering-operating tool 10, is connected to right and left travel-driving shafts 30L, 30R through an additional rotation transmitting device 36 for transmitting right and left, reverse additional rotations. Further, a shift arm of the reversible continuously variable transmission is connected to the steering-operating tool through a connecting mechanism which decreases the ratio of turning-displacement of the shift arm to the amount of operation in the range of small amount of steering-operation, and increases the ratio of turning-displacement of the shift arm to the amount of operation, in the large range where the amount of steering-operation exceeds a set value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reversible continuously variable transmission such as a hydraulic transmission capable of continuously changing an output rotation speed including a rotation direction in a working vehicle such as a combine or the like. A steering device to be obtained.

[0002]

2. Description of the Related Art Japanese Patent Application Publication No. Sho 54-54 discloses a technique in which a working drive mechanism causes a left and right traveling means (crawlers or wheels) to be positively given a rotational speed difference by a traveling drive mechanism.
No. 34972, JP-A-6-343332 and JP-B-7-2468. The prior art disclosed in these publications is a reversible continuously variable transmission, that is, a widely used hydraulic transmission or Japanese Utility Model Publication No. 49-2603.
7, JP-A-56-18150, JP-A-59-18150
The left and right traveling means are separately driven by using two sets of other reversible continuously variable transmissions such as a friction mechanical type known from, for example, -190556.

According to this prior art, it is easy to change the output rotation speeds including the rotation directions of the left and right reversible continuously variable transmissions to obtain a turn at an arbitrary turning radius of the vehicle. In addition, since the vehicle is driven by using a reversible continuously variable transmission for each of the left and right sides, a complicated control device is required to secure the straightness of the vehicle. That is, according to the structure in which the left and right traveling means are driven by different continuously variable transmissions,
It is difficult to obtain constant rotation of the left and right traveling means due to the left and right imbalance of the vehicle load, the left and right imbalance of the running resistance in the field scene, and the like. They needed a control unit.

A turning method similar to the above-described technique cannot be applied to a working vehicle in which the vehicle speed is changed stepwise. This is because a transmission having separate stepped transmission mechanisms for each of the right and left is not practical in terms of cost.

[0005]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a reversible continuously variable transmission, such as a hydraulic transmission, which is independent of a transmission mechanism of a traveling drive system. A work vehicle that makes it easy to obtain a turn at an arbitrary turning radius of the vehicle in the same manner as in the prior art described above, even when the change control is performed or when the change control is performed stepwise. To provide a new steering device.

Another main object of the present invention is to turn the vehicle in each case, for example, to finely correct the traveling direction of the vehicle during work, or to largely change the traveling direction of the vehicle on a headland in a field, etc. An object of the present invention is to provide a steering device capable of achieving an accurate turning of the vehicle by operating a steering operation tool in accordance with the above.

[0007]

SUMMARY OF THE INVENTION A steering device for a work vehicle according to the present invention is a reversible continuously variable transmission 2 which is operated by a steering operation tool 10 for shifting.
3, the reversible continuously variable transmission 23 is provided for the left and right traveling drive shafts 30L and 30R which are rotationally driven in the same direction at a constant speed, and the reversible continuously variable transmission 23 is provided for the left and right traveling drive shafts 30L and 30R in directions opposite to each other. It is configured to be interlocked and connected via an additional rotation transmission device 36 that can apply additional rotation. Then, according to the present invention, the ratio of the rotational displacement of the speed change arm 82 to the operation amount of the speed change arm 82 of the reversible continuously variable transmission In a large range in which the direction operation amount exceeds the set value, connection is made via a connection mechanism 83 that increases the rotational displacement ratio of the speed change arm 82 to the operation amount.

The left and right traveling drive shafts 30L, 30R
May be driven steplessly or steppedly. However, the present invention relates to a driving drive system for left and right driving drive shafts 30L and 30R that are driven uniformly. The steering is obtained by imparting additional rotation in the left and right directions via the additional rotation transmitting device 36 by the reversible continuously variable transmission 23 independent of the steering device. Therefore, there is no need for a complicated control device such as detecting and correcting the difference between the left and right rotation speeds in order to secure the straightness of the vehicle. Since the reversible continuously variable transmission 23 can continuously change the output rotation speed, the turning of the vehicle can be performed in any direction and at any turning radius while the vehicle is moving forward or backward. it can.

The steering operating tool 10 and the reversible continuously variable transmission 23
The connection mechanism 83 between the transmission arm 82 and the transmission arm 82 is configured such that the ratio of the rotational displacement of the transmission arm 82 to the operation amount differs between the small range and the large range of the steering operation amount as described above. Accordingly, it is possible to obtain a vehicle turning that appropriately corresponds to the vehicle turning purpose. That is, when the steering operation tool is operated within the range of the small operation amount in order to obtain a turn of the vehicle with a small turning radius, the ratio of the rotational displacement of the speed change arm is reduced, so that the reversible continuously variable transmission 23 is controlled. The speed ratio is finely changed and controlled, so that, for example, when the traveling direction of the vehicle is finely corrected during work, the correction can be performed precisely. Conversely, when the steering operation tool is operated to a large operation range to turn the vehicle largely, the rotational displacement ratio of the transmission arm is increased, and the output rotation speed of the reversible continuously variable transmission 23 is rapidly increased. As a result, a sharp turn of the vehicle is obtained, so that when the traveling direction of the vehicle is to be largely changed, for example, on a headland in a field, the traveling direction can be changed quickly.

The connection mechanism 83 is provided with the steering operation tool 10.
It is preferable that the larger the amount of operation in a large range in which the steering operation amount exceeds the set value, the larger the rate of rotation displacement of the speed change arm 82 is. In other words, in this case, the larger the steering operation tool is operated to make a large turn of the vehicle, the more the shift arm can be rotated and displaced at a larger rate, so that the vehicle can be quickly turned with a large turning radius. Can be achieved.

The connection mechanism 83 is provided with a control lever 86 which is rotatably supported about a fulcrum shaft 85 and is rotated and displaced by the steering operation tool 10, for example. A connecting member 87 for rotating and displacing the arm 82 is connected to the control lever 86 by the fulcrum shaft 85.
Movably supported in a direction toward and away from the
7 is connected to the steering operation tool 10 such that when the steering operation amount of the steering operation tool exceeds the set value, the connection tool is moved away from the fulcrum shaft 85. (Claim 3). According to this connection mechanism 83, when the steering operation tool is operated to an operation range exceeding the set value, the connection tool 87 is moved away from the fulcrum shaft 85 of the control lever 86, so that the control lever 86 Therefore, the amount of displacement of the connecting member 87 with respect to the unit rotational displacement amount is increased, and accordingly, the amount of rotational displacement of the speed change arm 82 is also increased. This connection mechanism has a simple structure with a small number of parts.

The reversible continuously variable transmission used in the steering device for a work vehicle according to the present invention is widely used, has high reliability, and is relatively inexpensive. It is preferable that the hydraulic transmission device 23 be provided with a variable displacement hydraulic pump 24 whose inclination angle of the plate 24a is controlled to be changed (claim 4).

[0013] Other features and advantages of the present invention will be apparent from the following description with reference to the accompanying drawings.

[0014]

FIG. 2 shows a combine equipped with an embodiment of the steering 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, and threshed the harvested grain culm in the threshing section 3 on the machine body. 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 steering section 9 includes a steering wheel 10 for vehicle steering, which is an example of a steering operation tool, a main shift lever 11 and a sub shift lever 12 for controlling a vehicle speed, a parking brake lever 13, and the like. In FIG. 2, 14 is an axle equipped with crawler drive wheels 15, 16 is a cutting blade, 17
Is a frying apparatus for carrying out grains from the grain tank 4.

FIG. 1 shows a transmission mechanism provided in the combine in FIG. 2 omitting the transmission mechanism to the cutting unit 2 and the threshing unit 3 described above. As shown in FIG. 4 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 power is transmitted from the output pulley 6a of the engine 6 to the input shaft 19 by a belt 27. As shown in FIG. 1, a first hydraulic power transmission device 20 in which the hydraulic pump 21 and a constant displacement hydraulic motor 22 are connected by a pair of oil supply / discharge circuits, and a hydraulic pump 24 and a constant displacement hydraulic pressure Second hydraulic power transmission 2 having motor 25 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, as shown in FIGS. 1, 3 and 4, the main drive shaft 29 for traveling and the left and right traveling drive shafts 30L and 30R are provided concentrically with each other.
The left and right traveling drive shafts 30L, 30R are connected to the left and right gears 31, 3
It is linked to the left and right axles 14 via a two-speed reduction mechanism. The main drive shaft 29 includes left and right traveling drive shafts 30L, 3
Left and right planetary gear units 33L, 33R for reduction with respect to 0R
An output shaft 34, which is rotationally driven by the hydraulic motor 22 in the first hydraulic transmission 20, is connected to the main drive shaft 29, and the first hydraulic transmission 20 drives the vehicle to travel. There are things. And the second
The hydraulic transmission device 23 has an output shaft 35, which is rotationally driven by the hydraulic motor 25 in the device 23, with respect to the left and right traveling drive shafts 30L, 30R.
The left and right traveling drive shafts 30R, which are connected to each other by an additional rotation transmitting device 36 that applies additional rotations in the opposite directions to each other, and are rotationally driven at a constant speed by the main drive shaft 29.
By making the rotation speeds of L and 30R different from each other,
It is assumed that the vehicle is steered.

An input gear 38 is fixedly mounted on the main drive shaft 29, and an output shaft 34 of the first hydraulic transmission 20 is linked to the input gear 38 by a 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. 3 shows a lower portion 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 of the internal toothed wheels 58 is formed on the inner surface of a ring 61 disposed on the outer peripheral side of the sun gear 57. The left and right rings 61 are supported in particular 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.

FIGS. 4 and 5 show the additional rotation transmitting 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.
Is shown. 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 in the row and the reduction ratio in the right gears 73, 75, 63 are set equal.

As described above, the left and right rings 61 can be rotated in opposite directions, so that they are rotationally driven by the main drive shaft 29 via the left and right planetary gear units 33L and 33R as described later. The left and right traveling drive shafts 30L and 30R can be additionally rotated in the left and right opposite directions, so that the vehicle can be turned by varying 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. 4, a thick plate member 77 protruding upward is mounted on one side of the upper end of the transmission case 56, and housings 78 and 79 are provided on one side and the other side of the plate member 77. Is attached. The transmission input shaft 19 is provided so as to penetrate both housings 78 and 79 and the plate member 77, and as described above, the hydraulic pump 21,
24 is mounted on the plate member 77 in the housings 78 and 79. These hydraulic pumps 21 and
The four pump swash plates 21a and 24a are tilted by the main transmission lever 11 and the steering wheel 10 shown in FIG. The hydraulic motors 22 and 2
5 is mounted on a plate member 77 in a housing 79 as shown in FIG.

The hydraulic pump 24 of the second hydraulic transmission 23
As shown in FIG. 6, a rotary operation shaft 81 for rotating and operating the pump swash plate 24a to change the inclination angle thereof penetrates one side wall of the housing 79 and faces the outside of the housing 79. Outside, a speed change arm 82 that rotates integrally with the pump swash plate 24a is attached. FIG. 6 shows a connection mechanism 83 between the speed change arm 82 and the steering wheel 10. The connection mechanism 83 has a control lever 86 supported by a bracket 84 on the outer surface of the housing 79 so as to be rotatable around a fulcrum shaft 85 parallel to the rotation operation shaft 81. The control lever 86 has a rotation operation shaft 81.
And an arc-shaped long hole 86a whose center is on the axis of. A rod-shaped connecting member 8 is provided between the control lever 86 and the shifting arm 82.
7, the shift arm 8 with the rotation of the control lever 86.
2 are connected so that they can be rotated. The connector 87 is provided with a pin portion 8a at the base end by slidably fitting the pin portion 87a into the elongated hole 86a of the control lever 86.
The fulcrum shaft 85 is caused by sliding displacement in the long hole 86a of 7a.
Control lever 8 so that it can move in the direction
7 is supported. Pin 87b at the tip of connector 87
Are pivotally attached to the shifting arm 82.

Similarly, as shown in FIG. 6, the output shaft 88 of the gear box 88 operated by the steering wheel 10
a has a first arm 89 and a second arm 90, each of which is rotationally displaced by the rotational displacement of the output shaft 88a.
Is fixed. The first arm 89 is connected to the control lever 86 by a rod 91 having connection fittings 91a and 91b pivotally mounted at both ends thereof at a longitudinal middle point of the lever 86, and is controlled by the rotational displacement of the output shaft 88a. The lever 86 is to be turned. The second arm 90 is provided with an arc-shaped long hole 90a centered on the axis of the output shaft 88a.
Are fitted so as to be relatively slidable. An operation cable 93 having the end of an inner wire 93a fixed to the pin 92 and the base end pin portion 86a of the connector 87 is provided. An outer stop 86b at the distal end of the operation cable 93 is integrally formed on the upper end of the control lever 86. It is bent. A coil spring 94 is arranged on the inner wire 93a between the outer receptacle 86b and the pin portion 86a of the connector 86. With the operation cable 93, the arm 90 is further rotated in the same direction by the output shaft 88a from the state in which the second arm 90 is rotationally displaced until the pin 92 reaches one end or the other end of the elongated hole 90a. When pressed, the pin 92 is pushed by the arm 90 and moved to apply tension to the inner wire 93a, thereby moving the pin portion 87a of the connector 87 away from the fulcrum shaft 85 in the elongated hole 86a of the control lever 86. It is supposed to be moved away. Coil spring 94
Is compressed by the movement of the pin portion 87a.

FIGS. 6 and 7 (a) show a state in which the steering wheel 10 is at a neutral position for moving the vehicle straight, and FIGS. 7 (b) and 7 (c) show that the steering wheel 10 is in one position. It shows a state change when the operation is performed in the direction. FIG. 8 shows the relationship between the operation angle θ from the neutral position of the steering wheel 10 in one direction and the rotation angle or the inclination angle α of the transmission arm 82 and the pump swash plate 24a from the neutral position. . In the neutral position of the steering wheel 10 as shown in FIG. 6, the pin 92 is located at the center position of the elongated hole 90a of the second arm 90, and is connected at the neutral position as shown in FIGS. The pin portion 87a of the tool 87 is located at the lowermost end in the long hole 86a of the control lever 86 and is designed to be as close as possible to the fulcrum shaft 85. The point a on the graph of FIG. 8 corresponds to the neutral position of the steering hand 10.

When the steering wheel 10 is turned in one direction from the neutral position, the inner wire 93a of the operation cable 93 is pulled until the pin 92 reaches one end of the long hole 90a of the second arm 90. Without being provided, the pin portion 87a of the connector 87 is kept at the closest position to the fulcrum shaft 85. Therefore, the first arm 89
The pin portion 87a when the control lever 86 is rotated and displaced around the fulcrum shaft 85 via the rod 91 by the rotation of
Is kept small. Therefore, the rotation rate or the angular velocity of the shifting arm 82 via the connecting member 87 is also kept small, and the pump swash plate 24a is gradually tilted from the neutral position. Operating angle theta ₁ of the steering wheel 10 shown in FIG. 8 is a set angle pin 92 is to reach the long hole 90a end of the second arm 90, until the angle theta ₁ to the fulcrum shaft 85 since the distance between the pin portion 87a is kept to a minimum constant value, tilt angle alpha is gradually increased at a small constant rate from zero to alpha _1.

When the operation angle θ of the steering wheel 10 exceeds θ ₁ , the inner wire 93 a is pulled as described above, and the proximal end pin portion 87 a of the connecting member 87 is far from the fulcrum shaft 85 in the elongated hole 86 a of the control lever 86. It is moved in the direction to leave. FIG. 7B shows a state in which the pin portion 87a is moved in such a manner and is slightly away from the fulcrum shaft 85, and FIG. 7C shows the pin portion 87a.
Has been moved to the upper end position of the long hole 86a of the control lever 86, and has been moved as far away from the fulcrum shaft 85 as possible. Points b and c on the graph of FIG. 8 correspond to (b) and (c) of FIG. 7, respectively, and the steering wheel operation angle corresponding to (c) of FIG. 7 is θ ₂ shown in FIG. is there. While the operation angle θ is increased from θ ₁ to θ ₂ , the pin portion 87 a is gradually moved away from the fulcrum shaft 85 and the distance therebetween gradually increases, so that the first arm 89 rotates through the rod 91. Although the angular velocity of the control lever 86 is the same as that in the range up to the operation angle θ ₁ , the movement rate of the pin 87 a accompanying the rotational displacement of the control lever 86 gradually increases. As a result, the rotation angular velocity of the speed change arm 82 is gradually increased, and as shown in FIG. 8, the swash plate inclination angle α increases almost in a parabolic relationship while the operation angle is increased from θ ₁ to θ _2. the increase from the inclination angle α ₁ to α ₂ while increasing. While the operation angle θ is increased from θ ₂ to the maximum angle θ ₃ , the distance between the fulcrum shaft 85 and the pin portion 87 a is maintained at the maximum constant value. It will increase at a high constant rate up to ₃ .

The above description is for the case where the steering wheel 10 is operated in one direction from the neutral position. However, when the steering wheel 10 is operated in the other direction, the turning directions of the control lever 86 and the speed change arm 82 are changed as shown in FIG. (B) and (c) are the same as those shown in FIG. In any case, the original position return of the pin portion 87a when the steering wheel 10 is returned to the neutral position is as follows.
It is obtained by the biasing force of the compressed coil spring 94.

The combine transmission shown in FIG. 1 is operated by the auxiliary transmission lever 12 in accordance with the running conditions.
A first low-speed gear stage is selectively set when traveling on roads, a first low-speed stage when working in dry fields, and a second low-speed stage that is lower when working in wet fields. The first transmission 20 shown in FIGS. By operating the pump swash plate 21a, the vehicle speed is continuously changed including the control of the traveling direction, and the vehicle is driven. When the vehicle travels straight, the steering wheel 10 does not operate the pump swash plate 24a of the second hydraulic transmission 23 shown in FIGS. 1 and 4, and the hydraulic transmission 23 is maintained in a neutral state. The rings 61 of the left and right planetary gear units 33L, 33R are restrained by a lock shaft 67 so as not to be rotationally displaceable. In addition, the lock in which the left and right rings 61 are not rotationally displaceable is, for example, provided with a worm transmission mechanism in the left and right transmission mechanisms transmitting to the left and right rings 61 to disable the rotation transmission from the left and right rings 61 in the opposite direction,
For example, it can also be obtained by providing a brake that is arranged on the motor output shaft 35 and that performs a braking operation when the vehicle travels straight.

FIGS. 9 (L) and 9 (R) schematically show 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.

During the forward movement of the vehicle, the steering wheel 10
FIGS. 1 and 4 show the operation of rotating the hydraulic motor 25 in the forward direction by tilting the pump swash plate 24a of the second hydraulic power transmission 23 through the connection mechanism 83 shown in FIG. By the additional rotation transmitting device 36, the left gears 72, 63
Given rotation of the arrow D ₁ direction in the ring 61 of the planetary gear unit 33L of the left through the column, also right gear 73,7
Ring 6 of planetary gear set 33R on the right through 5,63 rows
It is given the rotation of the arrow D ₂ direction to 1. Depending rotation in the arrow D ₁ direction in which the left of the ring 61 rpm in the arrow C direction of the planetary gear 60 by the rotation speed minute, therefore the rotational speed of the left carrier 59 and the traveling drive shaft 30L is reduced, the right to reverse of the rotation in the arrow D ₂ direction of the ring 61 rpm in the arrow C direction of the planetary gear 60 by the rotation speed component, thus the rotational speed of the right carrier 59 and the traveling drive shaft 30R is increased. Therefore, the vehicle is turned left. 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.

When the steering wheel 10 is operated within a small operation amount up to the operation angle θ ₁ in FIG.
The tilt angle α of the pump swash plate 24a of the second hydraulic transmission 23 is finely increased or decreased by increasing or decreasing the operation amount. Therefore, for example, when finely correcting the traveling direction of the vehicle during work,
The correction can be made precisely. Conversely when the steering wheel 10 in order to increase turn the vehicle to the range of the operation angle θ larger operation amount than ₁ in FIG. 8, the inclination angle α of the pump swash plate 24a is Masa greatly with increasing amount of operation For example, when the traveling direction of the vehicle is largely changed on a headland in a field or the like, the traveling direction can be quickly changed.

As in the above embodiment, the additional rotation transmitting device 36 is configured to apply additional rotations in opposite directions to the left and right traveling drive shafts 30L, 30R via the left and right planetary gear units 33L, 33R. In this case, the rotation of the hydraulic motor 25 is transmitted to the left and right internal toothed wheels 58 or the ring 61 thereof as described above, 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. 10 shows such another example in a mechanism diagram.

In the embodiment shown in FIG. 10, the left and right planetary gear units 33L and 33R disposed between the main drive shaft 29 and the left and right traveling drive shafts 30L and 30R respectively drive the ring 61 on which the internal gear 58 is formed. A carrier 59 fixed to the shaft 29 and supporting the plurality of planetary gears 60 is mounted on each traveling drive shaft 30.
L, 30R, and the sun gear 57
A gear 63 corresponding to the gear 63 is provided so as to be loosely fitted on the L, 30R and integrated with the sun gear 57. A lock shaft 67 corresponding to the lock shaft 67 is interlocked to the left and right gears 63 by a gear train similar to that described above in which the rotation is reversed between left and right. In this embodiment, the left and right sun gears 5
7, the rotation of the hydraulic motor 25 is greatly reduced by the additional rotation of the hydraulic motor 25. 30L and 30R, the gear 68 on the output shaft 35 of the second hydraulic transmission 23 meshes with the gear 72 on the lock shaft 67, and the intermediate shaft 66 for deceleration is omitted. I have.
A stepped sub-transmission 47 similar to the sub-transmission 47 is provided.
Are shown as blocks.

[Brief description of the drawings]

FIG. 1 is a mechanism diagram showing a transmission mechanism provided in a combine equipped with a first embodiment.

FIG. 2 is a schematic side view of the combine.

FIG. 3 is a longitudinal sectional view showing a part of a transmission provided in the combine.

FIG. 4 is a partially expanded longitudinal sectional view of a main part of the transmission.

FIG. 5 is a vertical sectional view of the transmission.

FIG. 6 is a schematic perspective view showing a connection mechanism between a steering operation tool and a speed change arm.

FIG. 7 is a side view for explaining the operation of the connection mechanism shown in FIG. 6;

FIG. 8 is a schematic graph showing an operation obtained by the connection mechanism of FIG. 6;

FIG. 9 is a schematic diagram for explaining the operation of the planetary gear device provided in the combine.

FIG. 10 is a mechanism diagram showing a transmission mechanism provided in a combine equipped with the second embodiment.

[Explanation of symbols]

Reference Signs List 6 engine 10 steering wheel (steering operation tool) 19 input shaft 20 first hydraulic transmission device 23 second hydraulic transmission device (reversible continuously variable transmission) 24 hydraulic motor 24a pump swash plate 25 hydraulic motor 29 main drive shaft 30L, 30R Traveling drive shaft 33L, 33R Planetary gear device 35 Output shaft 36 Additional rotation transmission device 57 Sun gear 58 Internal toothed wheel 59 Carrier 61 Ring 63 Gear 66 Intermediate shaft 67 Lock shaft 72 Gear 73 Gear 75 Idler gear 81 Rotation operation Shaft 82 Transmission arm 83 Connection mechanism 85 Support shaft 86 Control lever 86a Slot 86b Outer receptacle 87 Connector 87a Pin section 89 First arm 90 Second arm 90a Slot 91 Rod 92 Pin 93 Operation cable 93a Inner wire 94 Coil spring

Claims (4)

[Claims] A left and right traveling drive shaft (30L, 3) that is provided with a reversible continuously variable transmission (23) that is operated by a steering operation tool (10) to perform a speed change operation.
0R), the reversible continuously variable transmission is interlocked via an additional rotation transmission device (36) capable of imparting additional rotations in opposite directions to the left and right traveling drive shafts. Transmission arm (82) of transmission (23)
In the range where the steering operation amount is small, the ratio of the rotational displacement of the speed change arm to the operation amount is reduced with respect to the steering operation tool (10), and in the large range where the steering operation amount exceeds the set value, the operation amount is reduced. A steering device for a working vehicle, wherein the steering device is connected via a connection mechanism (83) for increasing a rotational displacement ratio of the speed change arm with respect to the speed change arm. 2. The connecting mechanism (83) is operated by rotating the speed change arm (82) as the steering operation amount of the steering operation tool (10) increases in a large range exceeding the set value. 2. The method according to claim 1, wherein the dynamic displacement ratio is increased.
Work vehicle steering device. 3. A fulcrum shaft (8) is connected to the connection mechanism (83).
5) A control lever (86) rotatably supported around and rotatably displaced by the steering operation tool (10) is provided.
A connector (87) for rotating and displacing the transmission arm (82) by the rotational displacement of the control lever is connected to the control lever (86).
The connecting tool (87) is movably supported in a direction approaching or away from the fulcrum shaft (85), and the steering operation amount of the steering operation tool is set to the set value with respect to the steering operation tool (10). 3. The steering apparatus for a work vehicle according to claim 2, wherein the connecting tool is connected so as to be moved away from the fulcrum axis when the distance exceeds the fulcrum axis. 4. A hydraulic transmission device comprising a variable displacement hydraulic pump (24) in which the reversible continuously variable transmission is controlled to change the inclination of a pump swash plate (24a) via the transmission arm (82). The steering device for a work vehicle according to any one of claims 1 to 3, wherein the steering device is a steering device.