JP2987291B2 - Work vehicle steering control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering control device for a work vehicle having a pair of left and right traveling devices, for example, a multi-wheel type or a crawler type with four wheels on one side. A side clutch that separately interrupts transmission of shifting power to the traveling device, a turning hydraulic clutch that transmits sudden turning power to the traveling device on which the side clutch is disengaged, and a left side of a single steering lever. Or a turning hydraulic control means for turning off one of the left and right side clutches by operating to the right and increasing or decreasing the operating pressure supplied to the turning hydraulic clutch according to the lever operation amount. The present invention relates to a steering control structure.

[0002]

2. Description of the Related Art Conventionally, a steering control device for a work vehicle of this kind has been disclosed in Japanese Patent Application Laid-Open No. 4-118384, for example, when a turning hydraulic clutch is in an operating state. When the steering lever is operated for a predetermined time or more,
The hydraulic oil supply pressure to the turning hydraulic clutch is gradually increased in synchronization with the operation of the lever, that is, it is configured to linearly increase, and when the turning hydraulic clutch is fully operated. It is well-known that a traveling device for a steered inner limb is driven in a reverse direction, and a traveling device for a steered outer limb is driven in a forward direction to make a super pivot turn.

[0003]

In the state in which the working vehicle is set in such a mode as to make a sharp turn, as shown in FIG. 3, the working vehicle is moved rightward or leftward from the neutral position of the steering lever. The hydraulic oil supply pressure to the turning hydraulic clutch gradually increases, that is, increases linearly according to the amount of operation of the turning hydraulic clutch. It is quite small near the neutral position of the lever. Therefore, in the work vehicle of the conventional structure, the traveling device is not driven to travel due to friction with the ground or the like, that is, the turning hydraulic clutch is in the half-clutch state without driving the traveling device with the inner steering in reverse. When the operator makes fine adjustments to the steering lever to perform a pivot turn, the operating range in which the half-clutch state can be made is considerably small, so that the steering lever is operated beyond the operating position where the half-clutch state is established. Therefore, it is difficult to appropriately maintain the half-clutch state. SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and even when a mode is set to a sharp turning state, a simple operation of a steering lever is performed to perform a slower turning than the sharp turning state as needed. It is an object of the present invention to provide a steering control device for a work vehicle which can be displayed well in a vehicle.

[0004]

SUMMARY OF THE INVENTION In order to achieve the above object, a steering control device for a working vehicle according to the present invention includes a side-side control device for separately interrupting transmission of speed change power from a speed change mechanism for traveling to left and right traveling devices. One of the left and right side clutches is disengaged by operating the single steering lever to the left or right, and the clutch, the turning hydraulic clutch for transmitting the turning power to the traveling device on the side where the side clutch is disengaged. A turning hydraulic control means for operating and increasing or decreasing an operating pressure supplied to the turning hydraulic clutch in accordance with a lever operation amount. Of the steering lever so that the rate of change of the operating pressure supplied to the hydraulic clutch for operation is small in the operation region near the neutral position of the steering lever and large in the operation region far from the neutral position. Wherein configuration in that the change characteristic of the operating pressure to the swing hydraulic clutch is set to for. Further, the change characteristic of the operating pressure applied to the turning hydraulic clutch in response to the operation of the steering lever may be configured to be changeable. The operation and effect of this characteristic configuration are as follows.

[0005]

That is, the rate of change of the operating pressure supplied to the turning hydraulic clutch with respect to the operation of the steering lever is made small in the operation region near the neutral position of the steering lever and large in the operation region far from the neutral position. Since the change characteristic of the operating pressure applied to the turning hydraulic clutch in response to the operation of the steering lever is set, the operating range of the steering lever that can bring the turning hydraulic clutch into a half-clutch state is set to the entire operating range. Therefore, the operation area can be largely increased near the neutral position.
Therefore, since the range in which the turning hydraulic clutch is in the half-clutch state is large, it is relatively easy to operate the steering lever to maintain the half-clutch state, and the steering lever can be operated in accordance with the condition of the field. The fine adjustment of the operation to maintain the state in which the traveling device of the inward direction is braked by the friction with the ground can be performed with a relatively large operation of the steering lever, and in that respect it is also easy to adjust . Further, if the change characteristic of the operating pressure to the turning hydraulic clutch in response to the operation of the steering lever is configured to be changeable, by changing the change characteristic as appropriate, the turning that is slower than the sharp turning in the sharp turning mode can be performed. Depending on whether or not it is necessary, the state can be changed to a state in which fine adjustment of the operation of the gentle turning can be sufficiently performed or a characteristic state in which the fine adjustment can be easily performed by the operator.

[0006]

Accordingly, the half-clutch operation of the transmission to the traveling device in the gentle turning during the sharp turning can be performed by
Since the operation range of the steering lever with respect to the half clutch is increased, the steering lever can be easily adjusted, and the turning operation can be favorably and easily performed. Since the characteristics of the rate of change can be changed, it is possible to set a characteristic state in which the operator can easily operate the vehicle depending on conditions such as a field or the like, so that maneuverability can be improved as appropriate.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows a structure inside a transmission case 8 of a traveling system of a combine, which is an example of a work vehicle, in which power from an engine (not shown) is connected to a belt transmission mechanism (not shown) having a tension clutch. Through the continuously variable transmission 1
Of the output shaft 3 of the continuously variable transmission 1
Is transmitted via a first transmission shaft 4 to a cutting section (not shown) at the front of the machine body.

[0008] The power from the first transmission shaft 4 is transmitted to the second transmission shaft 11 via the first gear 9 and the second gear 10.
A shift gear 14 is externally slidably fitted to the second transmission shaft 11 in a spline structure.
A high-speed gear 16, a medium-speed gear 17 and a low-speed gear 6 are fixed to the transmission shaft 15. With the above structure, the shift gear 14 is slid and engaged with the high-speed gear 7, the medium-speed gear 17 or the low-speed gear 6 that meshes with the high-speed gear 16, thereby shifting the forward rotation power for straight traveling into three stages of high, medium and low. Can be
This forward rotation power is transmitted to the first transmission gear 1 meshing with the middle speed gear 17.
9 is transmitted. As described above, the shift gear 14, the high-speed gear 7, and the like constitute the gear shift type transmission 13 as a traveling transmission mechanism.

A right side gear 21R and a left side gear 21L are rotatably fitted on a support shaft 20 supporting the first transmission gear 19, and input gears 23, 23 of left and right axles 22 are connected to left and right. It is always engaged with the side gears 21R and 21L. Thereby, the right or left side gear 2
1R and 21L are slid with respect to the first transmission gear 19 to engage and disengage to perform power transmission and transmission cutoff operations to the pair of left and right traveling devices 24 of the crawler type. And left and right side gears 21R, 2
Side clutches 25R and 25L are formed between the clutches 1L and 1L.

Next, a description will be given of a structure in which one of the traveling devices 24 is rotated in reverse to perform a pivot turn (corresponding to a sharp turn). As shown in FIG. 2, the high-speed gear 1 of the third transmission shaft 15
The third gear 37 meshing with the sixth gear 6 is externally fitted to the fourth transmission shaft 27 so as to be relatively rotatable, and the reverse rotation clutch 30 (corresponding to a turning hydraulic clutch) is provided between the third gear 37 and the fourth transmission shaft 27.
Is provided. The second transmission gears 26R and 26L are supported by bearings on both left and right ends of the support shaft 20, and each of the fourth transmission gears 29 fixed to both ends of the fourth transmission shaft 27 engages with the second transmission gears 26R and 26L. doing.

As a result, the right side gear 21R or the left side gear 21L is connected to the right or left second transmission gear 26.
When the reverse clutch 30 is engaged in the state of being engaged with R and 26L, the power from the high-speed gear 16 is transmitted to one traveling device 24 in the reverse state and reduced to one third. In this case, the other side gears 21R, 21L
Is engaged with the first transmission gear 19 and is driven to rotate forward, so that the airframe makes a super pivot turn due to a large speed difference between the left and right traveling devices 24.

Next, a description will be given of a structure in which one of the traveling devices 24 rotates forward at a lower speed than the other to make a gentle turn. As shown in FIG. 2, a small-diameter output gear 38 is fixed to the boss portion of the first transmission gear 19, and a large-diameter third transmission gear 40 is fitted around the fourth transmission shaft 27 so as to be relatively rotatable. The three transmission gears 40 are engaged with the output gear 38. The gentle turning clutch 12 is disposed between the third transmission gear 40 and the fourth transmission shaft 27.
Is provided.

As a result, the right or left side gear 21
When the gentle turning clutch 12 is engaged while the right and left second transmission gears 26R and 26L are engaged with the right and left second transmission gears 26R and 26L, the straight forward power transmitted to the first transmission gear 19 is output to the output gear 38. Forward power reduced to one-third via the third transmission gear 40, the gentle turning clutch 12, the fourth transmission shaft 27, the fourth transmission gear 29, and the right or left second transmission gear 26R, 26L. Is transmitted to one traveling device 24. In this case, the other side gears 21R and 21L are engaged with the first transmission gear 19 and are driven to rotate forward at a predetermined speed, so that the aircraft slowly turns due to a small speed difference between the left and right traveling devices 24. .

Next, the left and right side clutches 21R, 21R
Hydraulic cylinders 31R and 31L for performing the sliding operation of L
A structure for supplying hydraulic oil to the gentle turning and reverse rotation clutches 12 and 30 will be described. As shown in FIG. 1, hydraulic oil from a pump 32 is supplied to hydraulic cylinders 31R, 31L for left and right side gears 21R, 21L via a first switching valve 33, and an oil passage from the side of the hydraulic cylinders 31R, 31L. 34 is a second rotation to the gentle rotation and reverse rotation clutches 12 and 30.
It is connected to the switching valve 35. Further, in the oil passage 34,
A variable relief valve 36 as a hydraulic pressure control means for turning to the gentle turning and reverse rotation clutches 12 and 30 is connected.

A switching lever 18 is provided in the control section of the fuselage, and the switching lever 18 and the second switching valve 35 are mechanically linked to each other.
5 is switched to a gentle turning position 35a for supplying hydraulic oil to the gentle turning clutch 12 and a super pivot position 35b for supplying hydraulic oil to the reverse rotation clutch 30. Then, a steering lever 39 provided in a control section of the fuselage, a first switching valve 33 and a variable relief valve 36 are connected to a control circuit 52 and a wire 42.
Are linked through. That is, the operation state of the steering lever 39 is detected by a potentiometer or the like, and based on the detection result, each of the first switching valve 33 is set according to whether the steering lever 39 is in the forward operation state or the reverse operation state. The switching of the oil passage to the hydraulic cylinders 31R and 31L is performed based on the drive signal from the control circuit 52, and the closing of the oil passage of the variable relief valve 36 is controlled according to the displacement of the steering lever 39 from the neutral position. The operation is performed via the cam mechanism 43.

Then, one of the side clutches 24R, 25L is selected and disengaged from the neutral position of the steering lever 39, and the reverse clutch 30 is connected to the side gears 21R, 21L of the traveling device for steering. FIG. 3 shows a relationship between the axle torque corresponding to the supply pressure to the reverse clutch 30 and the operation amount of the steering lever 39 after the state. That is, since the rate of change of the axle torque near the neutral position N of the steering lever 39 is small, the gradient is gentle, but the axle near the maximum operating position of the steering lever 39 is small. The rate of change of the torque is large, and the gradient is steep. Therefore, the reverse rotation clutch 3
Since the operation range of the steering lever 39 corresponding to the range in which the brake can be turned in which 0 is in the half-clutch state becomes relatively large, fine adjustment of the operation for performing the steering while maintaining the half-clutch state in this manner is performed. It is easy to do. In order to obtain such a relationship between the axle torque and the operation amount of the steering lever 39, the shape of the cam in the cam mechanism 43 is set.

[Other Embodiment] FIG. 4 shows a hydraulic circuit configuration and the like of another embodiment. Note that the same reference numerals are given to the same structures as those in the above embodiment. That is, the cam mechanism 4
Numeral 3 designates that the relationship between the relief pressure of the variable relief valve 36 and the operation amount from the neutral position N of the steering lever 39 is set to change substantially linearly.
, A third switching valve 50 is connected. The third switching valve 50 connects the oil passage 34 to the hydraulic oil tank to reduce the pressure in the oil passage 34 to a low pressure state, and prevents the connection between the oil passage 34 and the hydraulic oil tank. The oil passage can be switched to a second state in which the pressure of the hydraulic oil in the oil passage 34 is maintained. The switching operation of the third switching valve 50 is performed depending on whether or not the solenoid is energized. An electric signal for driving the solenoid is output as a periodic pulse signal from the control circuit 52. A command signal for outputting the electric signal is provided at the top of the grip 39a of the steering lever 39. The instruction signal is generated by pushing a push button type switch 51 as an artificial switching operation tool, and the command signal is input to the control circuit 52. Further, the limit switch 5 for detecting that the switching lever 18 has been switched to the pivot turn.
3 is input to the control circuit 52. In the control circuit 52, when the limit switch 53 is turned on, that is, when the switch is switched to the super turning state,
Is input to the control circuit 52, the detection signal from the potentiometer 54 for detecting the operation position of the steering lever 39 is input to the control circuit 52, and based on the detection signal, the steering lever 39 is As the operation range is closer to the neutral position N, the duty ratio of the pulse signal is increased, and the range in which the reverse clutch 30 is in the half-clutch state is increased as shown in FIG. The duty ratio of the pulse signal becomes smaller as the distance becomes closer, so that the pressure set by the variable relief valve 36 is applied to the reverse clutch 30. Also according to this configuration, the rate of change of the operating pressure supplied to the reverse clutch 30 with respect to the operation of the steering lever 39 is small in the operation region near the neutral position of the steering lever 39 and large in the operation region far from the neutral position. To
A change characteristic of the operating pressure applied to the reverse clutch 30 in response to the operation of the steering lever 39 is set.

As shown by a broken line in FIG. 3, the change characteristic of the operating pressure applied to the reverse clutch 30 in response to the operation of the steering lever 39 may be changed stepwise or steplessly. This change is made in the above embodiment by the cam mechanism 4.
3 is performed by changing the shape of the cam, that is, by changing the cam, and in the case of electrically controlling the cam as in another embodiment, the period of the pulse signal for driving the third switching valve 50 is changed. Is appropriately adjusted by volume adjustment or the like.

In the claims, reference numerals are provided for convenience of comparison with the drawings, but the present invention is not limited to the configuration shown in the attached drawings.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram for a side clutch, a gentle turning clutch, and a reverse rotation clutch.

FIG. 2 is a schematic view showing a transmission system in a transmission case.

FIG. 3 is a graph showing a relationship between an operation amount of a steering lever and an axle torque.

FIG. 4 is a hydraulic circuit diagram for a side clutch, a gentle turning clutch, and a reverse rotation clutch according to another embodiment.

[Explanation of symbols]

 13 Transmission Traveling Mechanism 24 Traveling Device 25L, 25R Side Clutch 30 Turning Hydraulic Clutch 36 Turning Hydraulic Control Means 39 Steering Lever

Claims (2)

(57) [Claims] 1. Side clutches (25R) and (25L) for separately interrupting transmission of shifting power from a traveling transmission mechanism (13) to left and right traveling devices (24) and (24), and a side clutch (25R). , (25L) transmits a sudden turning power to the traveling device (24) on the side where the turning operation is performed, and a left or right operation of a single steering lever (39). Left and right side clutch (25
R) and (25L) are turned off and the hydraulic pressure control means (3) for increasing or decreasing the operating pressure supplied to the hydraulic pressure clutch (30) in accordance with the lever operation amount.
6) The steering control device for a work vehicle, comprising: a change rate of the operating pressure supplied to the turning hydraulic clutch (30) with respect to the operation of the steering lever (39). The turning hydraulic clutch (30) for the operation of the steering lever (39) is set so as to be small in an operation region near the neutral position and large in an operation region far from the neutral position.
A steering control device for a working vehicle, wherein a change characteristic of the operating pressure to the working vehicle is set. 2. The work vehicle according to claim 1, wherein a change characteristic of a working pressure applied to the turning hydraulic clutch (30) in response to an operation of the steering lever (39) can be set and changed. Steering control device.