JPH03144167A - Hydraulic driving device - Google Patents

Abstract

PURPOSE:To allow the idle revolution preventing function to automatically act by installing a control means for detecting the idle revolution of each axle and for shifting the capacity of a variable capacity type hydraulic motor joined with an axle on which an idle revolution state is detected, in a reduction direction. CONSTITUTION:When slip is not generated on each of wheels 3, 4, the liquid discharged from a hydraulic pump is distributed equally to the hydraulic motors 7 and 8 from a hydraulic circuit 9, and each equal driving torque is generated, and the differential function is developed through the flow rate variation of the discharged liquid in the hydraulic circuit 9. The control valve 20 of a control means 11 is kept at a neutral position when each pressure in the right and left pressure chambers 15 and 16 is equal. When the right wheel 3 idle-revolves because of slip, the pressure lowering at an orifice 13 increases over that at an orifice 14. The pressure in the pressure chamber 16 becomes higher than that in the pressure chamber 15, and the control valve 20 is moved rightward, and a control pressure is introduced into an actuator 21, and the capacity of a hydraulic motor 7 is shifted in the reduction direction, and the driving torque for the wheel 3 is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydraulic drive device suitably applicable to automobiles, general industrial vehicles, and the like.

BACKGROUND OF THE INVENTION In a front wheel drive (or rear wheel drive) vehicle, as is well known, left and right axles are coupled via a differential gear in order to absorb differences between inner wheels during cornering. A differential gear is mainly composed of a differential mechanism and can differentially distribute engine power to each axle.

Such a differential gear is also interposed between the front and rear axles of a four-wheel drive vehicle, and is used to absorb drive errors.

[Problems to be Solved by the Invention] By the way, when such a differential gear is employed, it is difficult to prevent the wheel mounted on one axle from slipping if it falls into mud or slips. Not only does this allow unilateral idling, making it no longer possible to properly transmit engine power to that axle, but due to the nature of differential gears, it becomes difficult to properly transmit power to the other axle, resulting in This results in the inconvenience of not being able to get the vehicle out of the mud. Therefore,
In order to eliminate this inconvenience, a differential lock mechanism is attached to the differential gear, and when one axle spins, the differential function unique to the differential gear is restrained and the differential lock mechanism is added to the differential gear. This is designed to prevent idling.This has resulted in problems such as the overall device becoming increasingly large-scale and requiring manual lever operation.

The present invention has been made with a focus on such problems, and employs a hydraulic power transmission system with a simple configuration.The present invention utilizes a hydraulic power transmission system with a simple configuration to exert a differential function through this transmission system, and also to prevent the axle from spinning when the axle spins. The aim is to realize a hydraulic drive device that has a more effective idling prevention function that automatically operates.

[Means for Solving the Problems] In order to achieve the above object, the present invention employs the following configuration.

That is, the hydraulic drive device according to the present invention includes a hydraulic pump driven by an engine, variable displacement hydraulic motors each coupled to a plurality of axles that are to be differentially driven, and a hydraulic pump driven by an engine. In a hydraulic drive device comprising a hydraulic circuit for supplying fluid discharged from a hydraulic pump, a detecting means for detecting idling of each axle, and a detecting means coupled to an axle whose idling state is detected through the detecting means. The present invention is characterized in that it is provided with a control means for shifting the capacity of the hydraulic motor in a decreasing direction.

[Operations] With this configuration, when none of the axles is idling, the fluid discharged from the hydraulic pump is distributed approximately evenly to each hydraulic motor to generate driving torque between roads, etc. The differential function during cornering can be easily handled by changing the flow rate of the discharged fluid in the hydraulic circuit. Moreover, if any axle spins due to slipping, the capacity of the hydraulic motor connected to that axle is shifted in the direction of decrease to reduce the driving torque generated by the discharged fluid, and the hydraulic motor connected to the other axle is shifted to reduce the capacity. Since the hydraulic motor is still supplied with a constant or higher discharge fluid to maintain effective drive torque, this hydraulic drive system quickly eliminates slippage and eliminates mud. You will be able to effectively escape from etc.

[Example] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

The hydraulic drive system of this embodiment is applied to a rear wheel drive vehicle shown in FIG. A variable displacement hydraulic motor 7.8 is connected to the axle 5.6 on which the . A hydraulic circuit 9 is provided for supplying. In this hydraulic pressure circuit 9, as shown in FIG. 2, idle detection means 17, 18 and control means 11 are integrally constructed.

Specifically, the hydraulic circuit 9 divides the discharged liquid from the hydraulic pump 2 to both hydraulic motors 7.8 in equal distribution, and flows the liquid that has finished its work to the hydraulic pump 2 3F2 again. It is designed so that it can be dropped into the tank 12 for this purpose. An orifice portion 13.14 is provided upstream of both hydraulic motors 7.8,
A pressure chamber 1 is provided between the flow path between the orifice portion 13 and the hydraulic motor 7.
5, and the flow path between the orifice portion 14 and the hydraulic motor 8 is communicated with the pressure chamber 16. That is, the orifice portion 13 and the pressure chamber 15 constitute the slip detection means 17 for the axle 3, and the orifice 14 and the pressure chamber 16 constitute the idling detection means 17 for the axle 4.
18 (details will be described later).

On the other hand, the control means 11 includes a control valve 20 that can slide within the cylinder 19 according to the pressure introduced into both pressure chambers 15.16, and an actuator 21 that changes the capacity of each of the hydraulic motors 7.8. .22 and the control pressure p generated in the control valve 20 by the actuator 21.
The pressure introduction path 23 includes a pressure introduction path 23 for introducing the control pressure p generated in the control valve 20 into the actuator 22.

The control valve 20 has springs 25 installed on the left and right sides.
26, and the left and right pressure chambers 15.16
If the pressures are the same, these springs 25 and 26 will always offset them to the neutral position. Furthermore, if the left pressure chamber 16 becomes higher in pressure than the right pressure chamber 15, the control valve 20 moves to the right and introduces the control pressure p to the actuator 21, and conversely, the right pressure chamber 15 has a higher pressure than the left pressure chamber 16. When this happens, the control valve 20 moves to the left and introduces the control pressure p into the actuator 22. When the control pressure is introduced in this way, the actuator 21 resists the spring 27 and changes the capacity of the hydraulic motor 7 in a decreasing direction, and the actuator 22 resists the spring 28 and changes the capacity of the hydraulic motor 8. change in the direction of decrease. As long as the actuator 21.22 is not actuated, both hydraulic motors 7.8 are driven at the maximum displacement set by another control system (not shown) (i.e. the control system controls the hydraulic pump 2, the hydraulic The gear ratio is controlled by changing the capacity of the motor 7.8).

Next, the operation of this embodiment will be explained. When there is no slippage on both axles 3.4, the fluid discharged from the hydraulic pump 2 flows evenly into the left and right hydraulic motors 7.8, and the control pressure p
does not flow out and both hydraulic motors 7.8 are at maximum volume and the wheels 3.4
exerts an equivalent driving torque on Further, the differential function during cornering and the like is handled by changing the flow rate state of the fluid discharged from the hydraulic pump 2 flowing into both hydraulic motors 7.8 through the hydraulic circuit 9. Then, right wheel 3
If the valve slips and spins idly, the pressure drop at the orifice portion 13 becomes larger than that at the orifice portion 14, and the pressure in the pressure chamber 16 becomes relatively higher than that in the pressure chamber 15, causing the control valve 20 to move to the right. let As a result, the control pressure p is introduced into the actuator 21, and the capacity of the hydraulic motor 7 is shifted in a decreasing direction, so that the driving torque for the wheels 3 is reduced. For this reason, slippage is easily suppressed. When the slip subsides, the pressure drop at the orifice portion 13 gradually decreases and the pressure chamber 15 gradually becomes the same pressure as the pressure chamber 16, so the control valve 20
moves to the left toward the neutral position, and when the actuator 21 completely returns to the neutral position, the control pressure p introduced into the actuator 21 disappears, and the hydraulic motor 7 again reaches its maximum displacement, reaching the same level as the hydraulic motor 8. Restore drive torque. Also, contrary to the above, if the left wheel 4 slips and spins, the pressure drop at the orifice portion 14 will be larger than that at the orifice portion 13, and the pressure chamber 15 will be relatively smaller than the pressure chamber 16. The high pressure causes the control valve 20 to move to the left. As a result, the control pressure p is introduced into the actuator 22, and the capacity of the hydraulic motor 8 is shifted in a decreasing direction, so that the driving torque for the wheels 4 is reduced. For this reason, slippage is easily suppressed. When the slip subsides, the pressure drop at the orifice portion 14 gradually decreases, and the pressure horn chamber 16 gradually becomes the same pressure as the pressure chamber 15.
The control valve 20 moves to the right toward the neutral position, and when the control valve 20 completely returns to the neutral position, the control pressure introduced into the actuator 22 disappears, and the hydraulic motor 8 becomes the maximum displacement again, and the hydraulic motor 7 Restores equivalent drive torque. In these operations, the rate of volume shift due to idle rotation is adjusted through the elastic modulus of each spring 25, 26, 27, 28.

According to the illustrated device configured in this manner, a proper differential function is ensured and normal driving is not hindered, and even if the wheels 3.4 slip, the slip prevention function is automatically activated. Slips are effectively eliminated and normal driving conditions can be quickly restored.

Moreover, its anti-slip mechanism has a simpler structure than conventional differential lock mechanisms, and is handled by proactively changing the torque distribution rather than simply canceling the differential. Therefore, it becomes possible to escape from the slip more effectively.

Note that such a hydraulic drive device can also be applied to a four-wheel drive vehicle. FIG. 3 shows an example, in which a hydraulic pump 32 driven by an engine 31 and a front wheel 3
Variable displacement hydraulic motors 39.40 are coupled to the axle 34 of the rear wheel 3 and the axle 36 of the rear wheel 35 via differential gears 37.38, respectively, and these hydraulic motors 3
9.40, it is composed of a hydraulic circuit 41 for feeding the liquid discharged from the hydraulic pump 32, and a detection means (not shown) and a control means 42 having the same configuration as in the above embodiment. As a result, torque can be distributed to the front and rear wheels 33, 34 in a timely and appropriate manner, and early escape from slippage can be effectively achieved. It is also possible to independently provide hydraulic motors for each of the four wheels, and individually detect idling and control the capacity. Further, the configurations of the detection means and control means are not limited to those shown in the drawings, and various modifications can be made without departing from the spirit of the present invention.

[Effects of the Invention] As explained above, the hydraulic drive device of the present invention is able to properly perform the differential function through the hydraulic transmission system, and when the axle is idling, the hydraulic drive device of the present invention is able to properly perform the differential function. Therefore, a more effective anti-slip function can be automatically exerted, and the configuration can be made more compact. Therefore, if this device is applied to vehicles, it will be possible to prevent or quickly eliminate wheel spin, improve running stability, reduce weight, and reduce tire wear, among other excellent effects. become.

[Brief explanation of the drawing]

1 and 2 show one embodiment of the present invention, FIG. 1 is a schematic diagram of a rear wheel drive vehicle equipped with a hydraulic drive device, and FIG.
The figure is a schematic circuit diagram. FIG. 3 is a schematic diagram corresponding to FIG. 1 showing another embodiment in which the present invention is applied to a four-wheel drive vehicle. 1.31... Engine 2.32... Hydraulic pump 5.6.34.36... Axle 7.8.39.40... Variable displacement hydraulic motor 9.4
1... Hydraulic pressure circuit 17.18... Detection means 11.42... Control means

Claims (1)

[Claims] A hydraulic pump driven by an engine, variable displacement hydraulic motors each connected to a plurality of axles that should be differentially driven, and a fluid that supplies discharged fluid from the hydraulic pump to these hydraulic motors. a hydraulic drive device comprising: a detection means for detecting idling of each axle; and a hydraulic motor coupled to an axle for which idling is detected through the detection means, and a displacement of the hydraulic motor coupled to the axle is shifted in a direction to decrease the capacity of the hydraulic motor. A hydraulic drive device, characterized in that it is provided with a control means for controlling.