JP3529611B2 - Steering valve device for vehicles running with hydrostatic transmission - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering valve device used for a vehicle running on a hydrostatic transmission, such as an agricultural vehicle or a construction vehicle. 2. Description of the Related Art Conventionally, a running fluid such as a wheel or a crawler is connected to a hydraulic motor, and the hydraulic fluid is rotated by a hydraulic fluid supplied from a variable displacement hydraulic pump through a closed hydraulic circuit. 2. Description of the Related Art Vehicles driven by a pressure transmission device are known in vehicles for agriculture and construction. In this type of vehicle, hydraulic motors are respectively connected to the left and right traveling means,
Each hydraulic motor is connected to a respective hydraulic pump by a closed hydraulic circuit, and a difference in the number of revolutions is caused between the hydraulic motors to operate the traveling direction of the vehicle. A valve operated by a steering handle is provided, and a part of the fluid supplied from one of the closed circuits to the hydraulic motor is returned to the tank via the valve to reduce the rotation speed of the one hydraulic motor. . As means for transmitting the operation of the vehicle steering handle to the valve, a means for transmitting the operation using a link or a joystick valve is known. However, the use of a link or the like complicates the vehicle structure. It is advantageous to employ a direct form of transmission using gears. [0004] When a link or a joystick valve is used, vibrations of the vehicle body are directly transmitted to the operator because the lever or the joystick valve is used, so that more accurate control may not be performed. In the case of the round handle operation, there is an advantage that operability is improved because the body can be operated with both hands fixed. SUMMARY OF THE INVENTION It is an object of the present invention to reliably and always transmit the rotational operation of a steering handle to a steering valve with a simple structure and to maintain the valve in an operating position. According to the present invention, a fluid is supplied from a variable displacement hydraulic pump, which is rotated by a prime mover mounted on a vehicle, to each of hydraulic motors for driving left and right traveling means of the vehicle. Run the vehicle and rotate the vehicle steering wheel .
Therefore, by operating the steering valve, the steering
Move the valve spool from the neutral position to both ends.
Each hydraulic pump via each pump displacement control device
By controlling the pump so that there is a difference in discharge rate
In a device for controlling the steering of a vehicle by varying the speed of each traveling means, the rotation of the vehicle is controlled by the vehicle steering handle.
And a spur of the steering valve is provided.
When the center axis of the gear is orthogonal to the rotation center axis of the driven gear,
In addition, on the side surface of the driven gear, from the rotation center axis of the driven gear
Forming a circular eccentric groove centered at biased position, the pin protrudes into the side of the scan <br/> pool engaged with eccentric grooves, of the driven gear by the vehicle steering wheel By rotation
The spool can be moved from the neutral position to both ends.
The above purpose was achieved by the ability . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS.
Denotes hydraulic motors, such as wheels and crawlers, for driving the left and right running means 2 and 2 of the vehicle, respectively, and reference numerals 3 and 3 denote variable displacement hydraulic pumps rotated by a prime mover 4 mounted on the vehicle. Each hydraulic motor 1 has a respective closed hydraulic circuit 18, 18.
The vehicle rotates by receiving the supply of fluid from each hydraulic pump 3 via the. And the traveling means 2 is driven. The same size is used for both hydraulic motors 1 and 1, and the same amount is supplied from each hydraulic pump 3 so that each hydraulic motor 1 rotates at the same speed, and the vehicle travels straight. [0008] The running direction of the vehicle is determined by a vehicle steering wheel 5.
By moving the steering valve 6, the speed of each traveling means 2 is made different, and in the illustrated example, the steering valve 6 acts on the pump displacement control device 3a of the hydraulic pump 3 in the steering direction. By reducing the command pressure from the pressure source 7 and reducing the pump capacity of the hydraulic pump 3, that is, the pump discharge amount, the flow rate of the closed hydraulic circuit 18 to the hydraulic motor 1 is made smaller than the flow rate to the other hydraulic motor. Then, a speed difference is generated between the left and right traveling means 2 and 2 so that the vehicle turns . The steering valve 6 includes a slidable spool 10 having two slits 11 and 11 formed therein.
Ports 8 , 8 connected to the tank, and slits 11, 11 connected to the respective pump displacement control devices 3 a , 3 a
Connection ports 9, which are connected to ports 8, 8 respectively through
9 in accordance with the distance that the spool 10 moves upward or downward from the neutral position shown in FIG .
The flow area between the pair of connection ports 9 and 8 increases,
Lower or upper set of connecting ports of the upper and lower moving end of Lumpur 10
When flow area of over preparative 9 and port 8 is maximized, the flow
Pressure passing area acts Pont <br/> flop capacity control device 3a which is connected to a set of connection ports became maximum is minimized, 該制
The discharge amount of the hydraulic pump 3 on the side controlled by the control device 3a is reduced most, and the difference from the discharge amount of the other hydraulic pump 3 is reduced.
And the vehicle turns at a steep angle. The rotation of the steering handle 5 is transmitted via a gear 12 to a driven gear 13 meshing therewith, and further transmitted to a spool 10. In the present invention, the rotation of the steering wheel 5 An eccentric groove 16 having a center 15 which is circular and has a center 15 deviated by a distance E from the rotation center axis 14 is formed. The spool 17 moves up and down according to the left and right rotation distance of the steering handle 5. When the gear 12 and the driven gear 13 rotate by the rotation of the steering handle 5, the spool 10 engaged with the eccentric groove 16 moves up or down within the range of the eccentric distance E, and the hydraulic pressure on the turning side is increased. The discharge of the pump 3 is reduced,
The number of rotations of the hydraulic motor 1 and the traveling means 2 on the turning side decreases,
The vehicle turns. In this case, even if the inertia force due to the vibration of the vehicle body or the vehicle speed acts on the spool 10, the pin 1 is inserted into the eccentric groove 16.
7, the spool 10 is hardly moved by the action and is located at a fixed position.
The rotation speed of the hydraulic motor 1 does not change unnecessarily, and the vehicle can be turned as the rotary steering handle 5 is operated. The rotation steering handle 5 can be operated even if it is connected to the rotation center shaft 14. As described above, according to the present invention, a driven gear meshes with a gear rotated by a vehicle steering handle, and a steering valve spool is inserted into an eccentric groove formed on a side surface of the driven gear. Since the engagement and the movement are applied to the steering valve, the operation of the steering wheel can be directly transmitted to the steering valve, so that the transmission structure is simplified, and the operation of the spool can be performed even when the vehicle vibration or inertia force acts on the valve. Since the position can be maintained, the vehicle can be turned in accordance with the operation amount of the steering wheel, and there is an effect that operability is improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view showing an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along a line 2-2 in FIG. Variable displacement hydraulic pump, 4 prime mover, 5 vehicle steering handle, 6 steering valve, 10 spool, 12 gear, 13 driven gear, 15 center, 16 eccentric groove, 17 pin,

Claims (1)

(1) Claims 1. A vehicle in which a fluid is supplied from a variable displacement hydraulic pump rotated by a prime mover mounted on a vehicle to each of hydraulic motors for driving left and right running means of the vehicle, respectively. , The steering valve is operated by rotating the vehicle steering handle , and the spool of the steering valve is moved to the neutral position.
Moving toward both ends from
The difference in discharge rate between the hydraulic pumps via the control unit may occur.
In a device for controlling the steering of a vehicle by making the speeds of the respective traveling means different by performing the following control, a driven gear rotated by the vehicle steering handle is provided, and the center axis of the spool of the steering valve is adjusted. Subordinate
A circular eccentric groove having a center at a position deviated from the rotation center axis of the driven gear is formed on a side surface of the driven gear while being orthogonal to the rotation center axis of the driving gear, and a side of the spool is formed. Bump
The pin provided out engaged with the eccentric groove, said vehicle steering
The rotation of the driven gear by the handle causes the spool to rotate.
A steering valve device for a vehicle running on a hydrostatic transmission, wherein the steering valve device is movable from a neutral position toward both ends .