JP2001010517A - Power steering system for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a power steering to effectively function even when the feed of the oil pressure to a power cylinder from a pump driven by an engine is stopped because of the failure of the engine. SOLUTION: This power steering system comprises an emergency pump 22 driven by the torque taken out from an accelerator shaft, an emergency circuit 23 for feeding the oil discharged from the pump 22 to the upstream of a flow rate pressure control valve 14 of a circuit 15 at a pump 19 side driven by an engine, a solenoid valve 24 capable of being switched between a position (a) to close the emergency circuit 23 and a position (b) to open the emergency pump 22 side to a reverser 16 side, as a switching means for holding the emergency pump 22 in a no-load state in a normal time of the pump 19 side driven by the engine, and a check valve 37 for preventing the flowing of the oil discharged from the emergency pump 22 to the pump 19 side driven by the engine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a power steering device for a vehicle.

[0002]

2. Description of the Related Art In order to reduce a steering operation force of a vehicle such as an automobile, a power cylinder for steering wheels and a power cylinder as a means for controlling an operation direction and a boosting action of the power cylinder in accordance with an operation of a steering wheel. 2. Description of the Related Art A power steering apparatus including a control valve for switching an oil passage of a motor and a pump driven by an engine as a means for supplying oil pressure to the valve is well known.

In such an apparatus, when an abnormality occurs on the pump side driven by the engine, for example, when the operation becomes impossible due to a failure of the engine, the supply of the hydraulic pressure to the power cylinder is stopped. Power steering will not work. Therefore, in a vehicle having a large axle load (such as an all-terrain vehicle), if such a failure occurs on the road, the steering operation cannot be performed as desired, and even towing may be impossible.

[0004] As one of measures against such a problem, in a vehicle equipped with a hydraulic suspension device, the hydraulic pressure of a suspension cylinder can be supplied as hydraulic oil to a power cylinder when a pump driven by an engine fails. (Japanese Patent Laid-Open No. 10-3)
No. 5520).

[0005]

In this case, since the hydraulic pressure of the suspension cylinder can be used for emergency, the cost is reduced in comparison with the case where a dedicated electric pump for supplying the hydraulic pressure to the power cylinder in an emergency is added. Although advantageous, the suspension cylinder contracts with the supply of hydraulic pressure to the power cylinder. Therefore, the power steering is effective only by the supply of the hydraulic pressure until the suspension cylinder contracts, and the traction of the vehicle is limited to that period, and this cannot be completed (that is, the traction must be abandoned halfway). It is not possible).

The present invention has been made in view of such a problem. Even when the supply of the hydraulic pressure to the power cylinder is stopped due to a failure of the engine, the electric pump (power consumption is a problem) is provided. Regardless, it is an object of the present invention to provide a means that enables the power steering to operate without restriction when the vehicle is towed.

[0007]

According to a first aspect of the present invention, there is provided a power cylinder for steering wheels, and a means for controlling an operation direction and a boosting action of the power cylinder in accordance with operation of a steering wheel. In a power steering device for a vehicle including a control valve for switching a path and a pump driven by an engine as a means for supplying hydraulic pressure to the valve, when an abnormality occurs on a pump side driven by the engine by hydraulic pressure to the control valve. As means for supplying, an emergency pump driven by the rotational force taken out of the accelerator shaft and a switching means for holding the emergency pump in a no-load state when the pump driven by the engine is normal are added. .

According to a second aspect of the present invention, there is provided a power cylinder for steering a wheel, and a control valve for switching an oil passage to the power cylinder as a means for controlling an operation direction and a boosting action of the power cylinder in accordance with an operation of a steering wheel. A pump driven by the engine as a means for supplying oil pressure to the valve, a control valve for adjusting the flow rate and pressure of oil supplied from the pump to the control valve,
Emergency pump driven by rotational force taken out of an accelerator shaft, and an emergency circuit for supplying the discharge oil upstream of a flow pressure control valve of a pump-side circuit driven by an engine When the pump side driven by the engine is normal, the emergency pump can be switched between a position where the emergency circuit is closed and a position where the emergency pump side is opened to the reservoir side as switching means for holding the emergency pump in a no-load state. An electromagnetic valve and a check valve for preventing the discharge oil of the emergency pump from flowing toward the pump driven by the engine are added.

According to a third aspect of the present invention, in the first or second aspect, the switching means for holding the emergency pump in a no-load state when the pump driven by the engine is in a normal state includes an operation arranged in a driver's seat. It has a switch.

[0010]

According to the first aspect of the present invention, when the pump driven by the engine is normal, hydraulic pressure is supplied from the pump to the control valve, and the control valve switches the oil passage in accordance with the operation of the steering wheel. Controls the operating direction and boosting action of the power cylinder. That is, based on the hydraulic pressure supplied from the control valve, the power cylinder steers the wheels in the operating direction corresponding to the operating angle of the steering wheel with the corresponding boosting action. Emergency pump is kept in no-load condition and power take-out is fixed (intermittent does not work)
Even in such cases, there is little resistance to the axle shaft.

When an abnormality occurs in the pump driven by the engine (for example, the supply of oil pressure to the control valve is stopped due to a failure of the engine), the emergency pump is switched from a no-load state to a load state,
Hydraulic pressure can be supplied from the emergency pump to the control valve. Even if the engine stops, when you pull the vehicle,
During this traveling, the emergency pump is driven by the rotation of the axle shaft, and hydraulic pressure is supplied to the control valve. Based on this hydraulic pressure, the power cylinder responds to the operation angle input from the steering wheel via the control valve. The wheels are steered with a corresponding booster in the direction of operation. Therefore, even if the supply of the hydraulic pressure from the pump driven by the engine to the control valve is stopped, the emergency pump is operated by the traction of the vehicle, so that the power steering can function effectively until the traction is completed. .

In the second aspect of the invention, when the pump driven by the engine is normal, hydraulic pressure is supplied from the pump to the control valve via the flow rate pressure control valve, and based on the hydraulic pressure, the power cylinder is driven by the first power cylinder. The steering wheel is steered in the same manner as in the invention of (1). The emergency pump is maintained in a no-load state by switching the solenoid valve to the open side, and hardly exerts any resistance on the axle shaft even when the power is taken out fixedly (intermittently does not work).

When an abnormality occurs on the pump driven by the engine (for example, the supply of oil pressure to the control valve is stopped due to a failure of the engine), the emergency circuit is switched to the closed state by the solenoid valve, Hydraulic pressure can be supplied from the emergency pump to the control valve via the flow pressure control valve. Even if the engine stops,
When the vehicle is towed, the emergency pump is driven by the rotation of the axle shaft during traveling, and hydraulic pressure is supplied to the control valve. Based on this hydraulic pressure, the power cylinder steers wheels as in the first invention. I will let you. At this time, the check valve prevents the discharge oil of the emergency pump from flowing to the pump connected to the engine.
The hydraulic pressure from the emergency pump is supplied to the control valve without waste. Therefore, even if the supply of the hydraulic pressure from the pump driven by the engine to the control valve is stopped, the emergency pump is operated by the traction of the vehicle, so that the power steering can function effectively until the traction is completed. .

In the third invention, in addition to the effects of the first invention or the second invention, the emergency pump is operated in a no-load state when the pump driven by the engine is operating normally by the operation switch in the driver's seat. Can be easily controlled.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an embodiment for explaining an example of application to an all terrain vehicle. FIG. 1 is a configuration diagram of a hydraulic circuit, and FIG. 2 is a side view of an all terrain vehicle (four-axle vehicle). It is. Reference numerals 10a to 10d denote power cylinders for steering the wheels, respectively, which are respectively disposed on the left and right wheels 11a of the first shaft and the left and right wheels 11b of the second shaft in the all terrain vehicle. Each of the cylinders 10a to 10d is internally partitioned into two chambers via a piston. Each of the cylinders 10a to 10d has a base end (head) supported on an axle (axle) side, and is connected to a knuckle arm (not shown) of a wheel at a tip end of a piston rod.

A first circuit 12 connecting the head side chamber of the cylinder 10a of the first shaft to the rod side chamber of the cylinder 10b and the head side chamber of the cylinder 10c of the second shaft to the rod side chamber of the cylinder 10d; The second circuit 13 connects the head side chamber of the cylinder 10b and the rod side chamber of the second shaft cylinder 10c as well as the rod side chamber of the cylinder 10c. A pump circuit 15 supplied via the control valve 14 and a tank circuit 17 for returning hydraulic pressure from the cylinders 10a to 10d to the reservoir 16 are also provided.

The first circuit 12 and the second circuit 13 are connected via a control valve 18 to a pump circuit 15 and a tank circuit 17.
Connected to. The control valve 18 is connected to the first circuit 1
A first operating position a communicating the pump circuit 15 and the tank circuit 17 in parallel with the second circuit 13 and the second circuit 13, a second operating position b communicating the same in an intersecting state, and a neutral position interrupting these communications. c, the oil passage (position) is switched in accordance with the operation angle of the steering wheel 20 in conjunction with the steering wheel 20 in the driver's seat,
The operation direction and boosting action of the power cylinders 10a to 10d are controlled.

The flow pressure control valve 14 of the pump circuit 15
An excessive discharge pressure of the pump 19 driven by the engine is released from the relief valve 14b, and an excessive flow rate is released from the orifice 14a to the drain circuit 21. The orifice 14a and the relief valve 14b. The pump 19 driven by the engine supplies hydraulic pressure to the control valve 18.
Emergency means driven by a rotational force taken out of an accelerator shaft (drive shaft) as a means for supplying when an abnormality occurs on the side (for example, when the supply of hydraulic pressure to the control valve 18 is stopped due to a failure of the engine). A pump 22, an emergency circuit 23 that guides the discharge oil upstream of the flow pressure control valve 14 of the pump circuit 15, and a switch that keeps the emergency pump 22 in a no-load state when the pump 19 driven by the engine is normal. Solenoid valve 24 as a means
And are provided.

The solenoid valve 24 has an operating position a for closing the emergency circuit 23 and an initial position b for opening the emergency pump 22 side to the reservoir 16 side (drain circuit 31). Driver's seat operation switch 35
When the power supply to the solenoid unit is turned on and off by the switch, these positions a and b are selectively switched. The emergency circuit 23 includes a check valve 36 for preventing the discharge oil of the pump 19 driven by the engine from flowing to the electromagnetic valve 24 (high pressure is applied) in order to ensure good operability of the electromagnetic valve 24. Interposed. The pump circuit 15 has a check valve for preventing the oil discharged from the emergency pump 22 from flowing to the pump 19 so that the oil pressure from the emergency pump 22 can be supplied to the control valve 18 without waste when the pump 19 is abnormal. 37 is interposed.

FIG. 3 is an explanatory view showing an assembled state of the emergency pump 22. The ring gear 25 of the differential 29 is shown in FIG.
A pinion 26 is provided which meshes with the
(The take-out axis orthogonal to the axle shaft 28)
The two drive shafts 30 are connected to each other via the flanges 30a and 27a.

With this configuration, when the pump 19 driven by the engine is normal, hydraulic pressure is supplied from the pump 19 to the control valve 18 via the flow pressure control valve 14, and the operation of the steering wheel 20 is controlled. Thus, the control valve 18 switches the oil passage to control the operation direction and the boosting action of the power cylinders 10a to 10d. That is, the power cylinders 10a to 10b
Based on the hydraulic pressure supplied from the control valve 18, the wheels 11 a, 1 have the same boosting action in the operating direction corresponding to the operation angle of the steering wheel 20.
1b is steered. The emergency pump 22 does not have the intermittent means on the take-out shaft 27 (see FIG. 3) by holding the solenoid valve 24 on the open side (no load state), but the resistance exerted on the axle shaft 28 is suppressed to a small value. .

If an abnormality occurs on the pump 19 driven by the engine (for example, the supply of oil pressure to the control valve 18 is stopped due to a failure of the engine), the emergency circuit 23 is closed by the solenoid valve 24. When switched, hydraulic pressure can be supplied from the emergency pump 22 to the control valve 18 via the flow pressure control valve 14. Even if the engine is stopped, when the vehicle is towed, the emergency pump 22
Are driven to supply hydraulic pressure to the control valve 18, and the power cylinders 10a-1
0d is the same as when the pump 19 side is normal.
11b is steered. Therefore, even if the supply of the hydraulic pressure from the pump 19 driven by the engine to the control valve 18 is stopped, the emergency pump 22 is operated by towing the vehicle so that the power steering can function effectively until the towing is completed. Can be.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a hydraulic circuit representing an embodiment of the present invention.

FIG. 2 is a side view of the all-terrain vehicle.

FIG. 3 is an explanatory view showing an assembled state of the emergency pump.

[Explanation of symbols]

 10a to 10d Power cylinder 12 First circuit 13 Second circuit 14 Flow pressure control valve 15 Pump circuit 16 Reservoir 17 Tank circuit 18 Control valve 19 Engine driven pump 20 Steering wheel 21, 31 Drain circuit 22 Emergency pump 23 Emergency circuit 24 Solenoid valve 28 Axle shaft 35 Operation switch 36, 37 Check valve

Claims (3)

[Claims] 1. A power cylinder for steering wheels, a control valve for switching an oil path to a power cylinder as means for controlling an operation direction and a boosting action of the power cylinder in accordance with an operation of a steering wheel, and And a pump driven by the engine as a means for supplying the hydraulic pressure of the vehicle. A power steering apparatus for a vehicle, comprising: an emergency pump driven by the taken-out rotational force; and switching means for holding the emergency pump in a no-load state when the pump driven by the engine is normal. . 2. A power cylinder for steering a wheel, a control valve for switching an oil path to the power cylinder as means for controlling an operation direction and a boosting action of the power cylinder in accordance with an operation of a steering wheel, and A pump driven by an engine as a means for supplying hydraulic pressure, a control valve for adjusting a flow rate and a pressure of supply oil from the pump to a control valve, and a rotational force taken out of an accelerator shaft in a power steering device of a vehicle provided with the pump. An emergency pump driven by
Emergency circuit for supplying the discharge oil upstream of the flow pressure control valve of the pump-side circuit driven by the engine, and switching means for holding the emergency pump in a no-load state when the engine-driven pump is normal A solenoid valve switchable between a position where the emergency circuit is closed and a position where the emergency pump side is opened to the reservoir side, and prevents the discharge oil of the emergency pump from flowing to the pump side driven by the engine. A power steering device for a vehicle, characterized by adding a check valve. 3. The switching means for maintaining the emergency pump in a no-load state when the pump driven by the engine is normal includes an operation switch disposed in a driver's seat. 3. The power steering device according to 2.