JPH06247326A - Steering power controller of motive power steering control device - Google Patents

Abstract

(57) [Summary] (Correction) [Purpose] To provide a steering force control device of a power steering system capable of stabilizing hydraulic characteristics with respect to steering torque. [Configuration] A supply path connecting the pump 1 and the cylinder 3,
A discharge passage that connects the cylinder and the reservoir tank 2 is provided, first and second variable throttles are provided in the supply passage and the discharge passage, respectively, and a third variable throttle is provided on the upstream side, and a third variable throttle is provided. , The first variable throttle is configured to function after it is completely closed, and the third variable throttle and the variable throttle immediately downstream thereof are communicated with each other via the bypass flow passage 17, And when one opens, the other closes 2
Two check valves 18 _R and 18 _L are provided, and the check valves are connected to a reservoir tank by a connecting path 19 so that each check valve is allowed to flow only to the reservoir tank. 5 is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering force control device for a power steering device such as a vehicle power steering device.

[0002]

2. Description of the Related Art Conventionally, as a steering force control device for a power steering device, there is one disclosed in Japanese Patent Application Laid-Open No. 63-188570. In the rotary valve used in this steering force control device, a pair of supply passages connecting the pump and the left and right oil chambers of the cylinder, and a pair of discharge passages connecting the left and right oil chambers of the cylinder and the reservoir tank are provided. A first variable throttle and a second variable throttle that respond to steering torque are provided on the pair of supply paths and the pair of discharge paths, respectively, and at least upstream of the pair of second variable throttles. Is provided with a third variable aperture that responds to the steering torque, and the third variable aperture is
The first variable aperture is configured to function after it is completely closed. Further, the pair of third variable diaphragms and the third
The first or second variable throttle immediately downstream of the variable throttle of (1), the pair of channels is connected via a bypass channel, and an external control variable throttle is provided in the bypass channel. There is.

[0003]

However, in the steering force control device of the conventional power steering system described above, when the external control variable throttle is open, the direction in which the hydraulic oil flows in the bypass flow passage is different from that when the steering wheel is turned to the right. Since it is reversed when left-turning, there are cases where it flows from one side to the other side in the internal flow path of the external control variable throttle and cases where it flows from the other side to one side. A spool valve having one end connected thereto is slidably accommodated, and a variable throttle is constituted by a peripheral surface of the other end of the spool valve and an oil groove formed in a valve seat portion with which the spool valve comes in contact with and separates from the oil valve. Structurally, there is a problem that in the above two cases, a difference occurs in the pressure loss generated when flowing through the internal flow path, the valve characteristic changes, and the excellent hydraulic characteristic with respect to the steering torque is impaired.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a steering force control device for a power steering system, which can stabilize the hydraulic characteristics with respect to the steering torque.

[0005]

In order to achieve the above object, the present invention provides a pair of supply passages connecting a pump and left and right oil chambers of a cylinder, a left and right oil chambers of the cylinder, and a reservoir tank. And a pair of discharge passages connecting to each other, and a first variable throttle and a second variable throttle that respond to steering torque are respectively provided on the pair of supply passages and the pair of discharge passages, and at least the pair of discharge passages is provided. At least a pair of third variable throttles that respond to the steering torque are provided on the upstream side of the second variable throttle.
In a steering force control device for a power steering system, wherein the third variable throttle is configured to function after the first variable throttle is fully closed, a pair of the third variable throttle and the third variable throttle are provided. The pair of flow paths communicates with the first or second variable throttle immediately downstream of the restriction via a bypass flow path, and when one of the bypass flow paths opens, the other Is provided with two check valves that are closed, and the check valves are connected to the reservoir tank by a connecting path so that each of the check valves is arranged so as to allow only the flow to the reservoir tank. An external control variable diaphragm is provided.

[0006]

With the above configuration, when the external control variable throttle is open, when the steering is turned to the right, the hydraulic oil from the pump flows into the left chamber of the cylinder through at least the first variable throttle through one supply passage. At the same time, a part of the hydraulic oil passes through the third variable throttle and is discharged from the bypass flow path to the reservoir tank via one check valve and the external control variable throttle. Further, when the steering wheel is turned left, the hydraulic oil from the pump flows into the right chamber of the cylinder through at least the first variable throttle by the other supply passage, and a part of the hydraulic oil flows through the third variable throttle. After passing through, it is discharged from the bypass channel to the reservoir tank via the other check valve and the external control variable throttle. In this way, the direction in which the hydraulic oil flows through the external control variable throttle is always constant.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing a steering force control device of a power steering apparatus, and FIG. 2 is an enlarged transverse sectional view taken along the line AA of FIG.
FIG. 3 is a hydraulic circuit diagram schematically showing FIGS. 1 and 2, and FIG. 4 is a partially enlarged view of FIG.

In these figures, 1 is a pump, 2 is a reservoir tank, 3 is a cylinder, 4 is a rotary valve, and 5 is a solenoid valve which constitutes an externally controlled variable throttle.

The rotary valve 4 includes a valve body 6 and a valve shaft 7 in a valve housing 8. Then, the valve shaft 7 is provided on the inner circumference of the valve body 6.
Are rotatably fitted together, and a steer rig wheel (not shown) is connected to one end of the valve shaft 7. Also, one end of the pinion shaft 9 of the power steering device is connected to one end of the valve body 6, and one end of the pinion shaft 9 and one end of the valve shaft 7 are connected via a torsion bar 10. ing.

A plurality of recessed grooves 11 and lands 12 are formed between the recessed grooves 11 on the inner peripheral surface of the valve body 6.
A plurality of concave grooves 13 and lands 14 are formed between the concave grooves 13 on the outer peripheral surface of the valve shaft 7. In addition, the groove 11 and the land 1 of the valve body 6 and the valve shaft 7
4, between the groove 13 and the land 12, the pump 1
A pump port P connected to the tank, a tank port T connected to the reservoir tank 2, left and right oil chambers 3a of the cylinder 3,
Left and right cylinder ports C _R , C _L and bypass ports B _R , B _L connected to 3b are formed.

Further, 15 ₁ and 16 ₁ are first flow paths forming a pair of supply paths, and 15 ₂ and 16 ₂ are second flow paths forming a pair of discharge paths.

The first flow path 15 ₁ is connected to the pump port P _1.
Between the right cylinder port C _R and the right cylinder port C _R
The right chamber 3a of the cylinder 3 is connected to. The first flow path 16
₁ is provided between the cylinder port C _L of the left and the pump port P, and connects the left chamber 3b of the cylinder 3 to the pump 1. The second flow path 15 ₂ is the right cylinder port C.
_The cylinder 3 is provided between the _R and the tank port T.
The right chamber 3a is communicated with the reservoir tank 2. The second flow path 16 ₂ is provided between the left cylinder port _CL and the tank port T, and connects the left chamber 3b of the cylinder 3 to the reservoir tank 2.

Further, 1R and 1L are a pair of variable orifices that form a first variable throttle, 2R and 2L are a pair of variable orifices that form a second variable throttle, 3R and 3L are third.
2 is a pair of variable orifices forming the variable throttle of FIG.

The variable orifice 1R is the first flow path 1
5 ₁ and is formed by end edges of the groove 13 and the land 12 that are adjacent to each other on the counterclockwise direction side. The variable orifice 1L is provided in the first flow path 16 ₁ and is constituted by end edges of the concave groove 13 and the land 12 which are adjacent to each other on the clockwise side. Said variable orifice 2R and the variable orifice 3R is the so variable orifice 3R is located upstream of the variable orifice 2R second passage 16 ₂
And is formed by the edge portions of the groove 11 and the land 14 that are adjacent to each other on the clockwise side. The variable orifice 2L and the variable orifice 3L are the variable orifice 2L.
Is provided in the second flow path 15 ₂ such that the variable orifice 3L is located on the upstream side with respect to the concave groove 11 and the land 1.
4 is formed by the end edge portions adjacent to each other on the counterclockwise direction side.

The variable orifices 1R, 1L, 2R, 2
L responds to the steering torque, and is for low speed only and is closed with a small steering torque. Further, the variable orifices 3R, 3L function after the variable orifices 1R, 1L, 2R, 2L are closed in response to the steering torque, and are dedicated to high speed operation for closing with a large steering torque. .

The second flow passage 15 ₂ and the second flow passage 16 ₂ are provided between the variable orifice 3L and the variable orifice 2L and between the variable orifice 3R and the variable orifice 2R.
Are communicated with each other via a bypass passage 17. The bypass port B _R constitutes a connection part of the second flow path 15 _{2 with} the bypass flow path 17, and the bypass port B _R
L constitutes a connection part of the second flow path 16 _{2 with} the bypass flow path 17.

In the bypass passage 17, two check valves 18 _R and 18 _R are closed, one of which is closed when the other is opened.
_L is provided, and the check valves 18 _R and 18 _L are connected to the reservoir tank 2 via the tank port T by a connection path 19. The check valves 18 _R and 18 _L are arranged to allow only the flow to the reservoir tank 2.

The connection valve 19 is provided with the solenoid valve 5, and the inlet port 5a of the solenoid valve 5 is provided.
Is connected to the bypass channel 17, and the outlet port 5b is connected to the tank port T.

The solenoid valve 5 has an internal flow passage 20 which connects the inlet port 5a and the outlet port 5b in a valve housing 21, and a spool valve 23 is slidably accommodated in the internal flow passage 20. , A solenoid 24 provided on the valve housing 8 at one end of the spool valve 23.
While connecting the plungers 24a of the
Further, a valve seat portion 22 on which the other end of the spool valve 23 can be seated is formed. Then, the solenoid 24 is excited by an exciting current value output from a control unit (not shown) in response to a detection signal from a vehicle speed sensor (not shown), and the spool valve 23 is moved by the solenoid 24 to come into contact with or separate from the valve seat portion 22. By doing so, the internal flow path 20 is opened and closed.

Further, the valve housing 8 is formed with a pair of communication holes 25 _R , 25 _L respectively connected to the bypass ports B _R , B _L. Each communication hole 25 _R ,
As shown in FIG. 4, 25 _L has a large diameter hole 25 b continuously provided on the outer opening side of the small diameter hole 25 a, and a connection plug 26 is screwed into the opening of the large diameter hole 25 b. Small hole 2
5a and the large-diameter hole 25b are continuously connected to the valve seat portion 2
5c is formed. A ball valve body 27 is seated on the valve seat portion 25c, and the ball valve body 27 is held by a retainer 28 and is urged by a spring 29 provided between the connecting plug 26 and the retainer 28.
As described above, the check valve 18 is provided in the communication hole 25 _R.
A check valve 18 _L is attached to each of the _R and communication holes 25 _L. Then, when the solenoid valve 5 is opened, for example, when a pressure rises in the bypass port B _R , the ball valve element 27 of the check valve 18 _R overcomes the spring force of the spring 29 and opens apart from the valve seat portion 25c. Valve and the hydraulic oil in the second flow path 15 ₂ passes through the communication hole 25 _R
From the small diameter hole 25a to the large diameter hole 25b and the retainer 28
Communication hole 26 of the connection plug 26 through a gap with the outer peripheral surface of the
It is designed to flow from a to the bypass channel 17.

In the above construction, when the steering wheel is not rotated while the vehicle is stopped,
Variable orifices 1L, 1R to 3L of the rotary valve 4,
3R is in an open state, and the solenoid valve 5 is completely closed so that the bypass passage 17 is not in communication with the reservoir tank 2. For this reason, the hydraulic oil from the pump 1 is diverted at a flow rate equal to that of the first flow passage 15 ₁ and the first flow passage 16 ₁ and supplied to the right chamber 3a and the left chamber 3b of the cylinder 3, and the left and right oil chambers 3a, Since no differential pressure is generated between 3b and no steering assist force is generated in the cylinder 3,
The steering wheel remains straight.

When the steering wheel is turned to the right with respect to the steering resistance acting on the pinion shaft 9 when the vehicle is stopped and running, the torsion bar 10 is twisted, as shown by the arrow in FIG. Further, the valve shaft 7 relatively rotates in the clockwise direction with respect to the valve body 6, and the variable orifices 1R, 3R, 2R are each throttled according to the steering torque. Variable orifice 1L, 3L, 2
L is open. Therefore, the hydraulic oil from the pump 1 is supplied to the left chamber 3b of the cylinder 3 via the variable orifice 1L, and part of the hydraulic oil is discharged to the reservoir tank 2 via the variable orifice 3R and the variable orifice 2R. , The hydraulic fluid in the right chamber 3a of the cylinder 3 is the variable orifice 3
Since it is discharged to the reservoir tank 2 via L and the variable orifice 2L, the supply pressure to the cylinder 3 is throttled by the variable orifices 3R, 2R and becomes high. Therefore, the maximum steering assist force can be obtained with a relatively small steering torque, and thus a light steering feeling can be obtained.

On the other hand, when the steering wheel is not rotated while the vehicle is traveling at high speed, the variable orifices 1L, 1R to 3L and 3R of the rotary valve 4 are in the open state and the left and right oil chambers 3a of the cylinder 3 are Since there is no differential pressure generated between 3b and no steering assist force is generated in the cylinder 3, the steering wheel maintains a straight traveling state.

When the steering wheel is turned to the right, for example, while the vehicle is traveling at a high speed, the bypass valve 1 is opened when the solenoid valve 5 is completely open in the high-speed traveling state.
Since 7 communicates with the reservoir tank 2, this bypass flow path 17 bypasses the variable orifice 2R, and the supply pressure to the cylinder 3 is variable orifice 3R.
It will be squeezed with only one and it will become low. Therefore, a minimum steering assist force is obtained, which results in a heavy steering feeling.

When the solenoid valve 5 is completely open, the hydraulic oil from the pump 1 passes through the variable orifice 3R when the steering wheel is turned to the right, and the bypass flow passage 17 causes one of the check valves 18 _L and the solenoid valve. It is discharged to the reservoir tank 2 via 5. Further, when the steering wheel is turned left, the hydraulic oil from the pump 1 is supplied to the variable orifice 3
Check valve 1 from the bypass passage 17 through L
It is discharged to the reservoir tank 2 via 8 _R and the solenoid valve 5. In this way, the direction in which the hydraulic oil flows through the solenoid valve 5 is always constant.

In this embodiment, the variable orifice 3
L and the variable orifice 2L are provided in the second flow passage 15 ₂ , and the variable orifice 3R and the variable orifice 2R are provided in the second flow passage 16 ₂ , respectively. As shown in FIG. 5, the variable orifice 3L and the variable orifice 2L are the first passage 15 _1, the variable orifice 3R and the variable orifice 2R may be respectively provided in the first passage 16 _1. Further, in the above-mentioned pair of embodiments, the variable orifice 3R and the variable orifice 3L are provided one by one, but two or more pairs may be provided as shown in FIG.

[0028]

As described above, the present invention has a pair of supply passages connecting the pump and the left and right oil chambers of the cylinder, and a pair of discharge passages connecting the left and right oil chambers of the cylinder and the reservoir tank. And a pair of supply paths and a pair of discharge paths,
A first variable diaphragm and a second variable diaphragm that respond to the steering torque are respectively provided, and at least the third variable diaphragm that responds to the steering torque is provided at least upstream of the pair of second variable throttles. A pair of third variable throttles and a pair of the third variable throttles are provided in the steering force control device of the power steering system, wherein the pair of third variable throttles is configured to function after the first variable throttle is completely closed. The pair of flow paths communicate with each other via the bypass flow path between the first variable flow restrictor and the second variable restrictor immediately downstream of the third variable restrictor, and one of the bypass flow paths is opened. When the two check valves are closed, the other one is closed, and the check valves are connected to the reservoir tank by a connection path so that each check valve is arranged to allow only the flow to the reservoir tank. An external control variable diaphragm is provided in the connection path. As a result, the direction in which the hydraulic oil flows through the externally controlled variable throttle can always be kept constant, so there is no difference in valve characteristics when the steering wheel is turned to the right and left, and the hydraulic characteristics are stabilized against steering torque. Can be achieved.

Further, since the external control variable throttle can adjust the throttle area with an external signal other than the steering torque to control the hydraulic pressure supplied to the cylinder in a wide range, the hydraulic pressure is generated in the cylinder together with the stabilization of the hydraulic characteristic. The controllability of the steering assist force is improved.

Further, since the first variable throttle and the second variable throttle can surely perform a stepwise pressure drop in the flow passage and reduce the pressure to the extent that cavitation does not occur, the generation of fluid noise due to cavitation is also prevented. Can be achieved.

Further, a pair of check valves are provided in the bypass flow passage, and a simple structure in which the bypass flow passage is connected to the reservoir tank via one check valve of the check valve and the external control variable throttle is sufficient. Can be significantly reduced and can be easily applied to existing ones.

[Brief description of drawings]

FIG. 1 is a sectional view showing a steering force control device of a power steering system according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view taken along the line AA of FIG.

FIG. 3 is a hydraulic circuit diagram schematically showing FIGS. 1 and 2.

FIG. 4 is a partially enlarged view of FIG.

FIG. 5 is a hydraulic circuit diagram corresponding to FIG. 3, showing a steering force control device for a power steering device according to another embodiment of the present invention.

FIG. 6 is a hydraulic circuit diagram corresponding to FIG. 3 showing a steering force control device for a power steering system according to still another embodiment of the present invention.

[Explanation of symbols]

1 Pump 2 Reservoir Tank 3 Cylinder 3a, 3b Oil Chamber 5 Solenoid Valve (External Control Variable Throttle) 15 ₁ , 16 ₁ First Flow Path (Supply Path) 15 ₂ , 16 ₂ Second Flow Path (Drain Path) 1R, 2R 1L, 2L Variable orifice (first variable throttle) 3R, 3L Variable orifice (second variable throttle) 17 Bypass flow path 18 _R , 18 _L Check valve 19 Connection path

Claims (1)

[Claims] 1. A pair of supply paths comprising: a pair of supply paths that connect a pump and left and right oil chambers of a cylinder; and a pair of discharge paths that connect a left and right oil chambers of the cylinder and a reservoir tank. A first variable throttle and a second variable throttle, which respond to the steering torque, are provided on the pair of discharge passages, respectively, and respond to the steering torque at least upstream of the pair of second variable throttles. In the steering force control device for a power steering system, wherein at least one pair of third variable throttles are provided, and the third variable throttles are configured to function after the first variable throttle is completely closed, The pair of flow paths are communicated via a bypass flow path between a third variable throttle and the first or second variable throttle immediately downstream of the third variable throttle,
The bypass flow path is provided with two check valves whose one is opened and the other closed, and the check valves are connected to the reservoir tank through a connection path to connect the check valves to the reservoir tank. A steering force control device for a power steering device, which is arranged so as to allow only a flow, and an external control variable throttle is provided in the connection path.