JPH0692249A - Power steering gear - Google Patents

Abstract

PURPOSE:To provide a large steering force in stoppage and low speed travelling by preventing the occurrence of noises in a hydraulic controlling valve and changing an auxiliary steering force according to vehicle speed. CONSTITUTION:Oil supply chambers 24 communicating to a hydraulic pump 40, oil supply chambers 28, 29 respectively communicating to two cylinder chambers 2a, 2b of a power cylinder 2 at both circumferential sides of the oil supply chamber 24, drain oil chambers 25 communicating to an oil tank 36 and intermediate pressure chambers 26, 39, 27, 31 between the drain oil chamber 25 and oil supply chambers 28, 29 are juxtaposed on the periphery of a tubular valve body 15 and valve sleeve 16 angularly coaxially displaced relative to each other. A hydraulic controlling valve for controlling oil pressure supplied to two cylinder chambers 2a, 2b of the power cylinder 2 according to a change in a throttle area caused by relative angular displacement in a throttle part interposed between these respective chambers is provided. A variable throttle path 50 for affording communication between the intermediate pressure chambers 26, 27 and the oil tank 36 is provided to be throttled along with the increase of vehicle speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power steering device for an automobile or the like.

[0002]

2. Description of the Related Art Motor vehicles are often equipped with a hydraulic power steering apparatus to assist the steering force of a driver. This type of power steering apparatus generally includes a hydraulic cylinder (power cylinder) for assisting a steering force and a rotary hydraulic control valve that switches the direction of pressure oil supplied thereto according to the steering direction.

As a hydraulic control valve for such a power steering apparatus, conventionally, a cylindrical valve body which is relatively angularly displaced on the same axis and an oil supply chamber connected to a hydraulic pump which is a hydraulic pressure source are provided on the circumference of a valve sleeve. The oil supply chambers connected to the two cylinder chambers of the power cylinder, which are different oil supply destinations, and the oil discharge chambers connected to the oil tank, which is the oil discharge destination, are arranged in parallel on both sides of the oil supply chamber in the circumferential direction. What was known was. In this hydraulic control valve, the first oil feed chamber is the first of the power cylinder.
The second oil supply chamber is the second cylinder of the power cylinder.
Are connected to each cylinder chamber. Then, when the steering wheel (steering wheel) is steered in the first direction, the first oil supply chamber becomes high in pressure and the second oil supply chamber becomes low in pressure, so that the first oil supply chamber The pressure oil is supplied to the first cylinder chamber, and the oil in the second cylinder chamber returns from the second oil supply chamber to the tank through the oil discharge chamber, thereby steering in the first direction. Power assistance is provided. Conversely, when the steering wheel is steered in the second direction,
While the second oil supply chamber has a high pressure and the first oil supply chamber has a low pressure, pressure oil is supplied from the second oil supply chamber to the second cylinder chamber, and at the same time, the first cylinder chamber The existing oil returns from the first oil supply chamber to the tank through the oil discharge chamber, thereby assisting the steering force in the second direction.

Such a conventional hydraulic control valve has a problem that noise is generated at the time of operation, and in order to solve this, for example, as disclosed in Japanese Utility Model Publication No. 63-30613, drainage oil is used. Intermediate pressure chambers are arranged side by side between the chambers and the oil feed chambers, and due to the change in the throttle area that occurs due to the relative angular displacement between the valve body and the valve sleeve in the throttles interposed between these chambers, There has been proposed a hydraulic control valve adapted to control the delivery hydraulic pressure.

[0005]

In such a conventional hydraulic control valve, for example, when the steering wheel is steered in the first direction, the first oil feed chamber becomes a high pressure and the first cylinder chamber moves to the first cylinder chamber. While the pressure oil is supplied, the oil in the second cylinder chamber returns from the second oil supply chamber to the tank through the intermediate pressure chamber and the oil discharge chamber, but the hydraulic pressure in the intermediate pressure chamber drops sharply. Therefore, some reaction force acts from the second oil feed chamber to the second cylinder chamber. Therefore, the auxiliary steering force generated in the power cylinder is always the difference between the hydraulic pressure acting on the first cylinder chamber and the hydraulic pressure acting on the second cylinder chamber,
Therefore, there is a problem that the auxiliary steering force cannot be changed depending on the vehicle speed, and a large steering force cannot be obtained even when a large steering force is required, for example, when the vehicle is stopped or running at low speed.

The object of the present invention is to solve the above problems,
It is an object of the present invention to provide a hydraulic control valve for a power steering device that generates little noise in the hydraulic control valve, can change the auxiliary steering force depending on the vehicle speed, and can obtain a large steering force when the vehicle is stopped or traveling at low speed. .

[0007]

SUMMARY OF THE INVENTION A power steering apparatus according to the present invention comprises a cylindrical valve body which is coaxially displaced relative to one another and a valve sleeve, and an oil supply chamber which is connected to a hydraulic pressure source.
The oil supply chambers connected to different oil destinations on both sides in the circumferential direction of the oil supply chamber, the oil discharge chambers connected to the oil discharge destinations, and the intermediate pressure chamber between the oil discharge chambers and the oil supply chambers, respectively. In a power steering apparatus provided with a hydraulic control valve that is arranged in parallel and that controls a hydraulic pressure to be fed to the oil destination by a change in the throttle area caused by the relative angular displacement in a throttle portion interposed between these chambers. A variable throttle passage that connects the intermediate pressure chamber to the oil discharge destination is provided,
The variable throttle passage is narrowed as the vehicle speed increases.

[0008]

For example, when the steering wheel is steered in the first direction, the auxiliary steering force generated in the power cylinder is connected to the hydraulic pressure acting on the first cylinder chamber and the second cylinder chamber through the first oil feed chamber. This is the difference from the oil pressure in the intermediate pressure chamber. As the vehicle speed increases, the variable throttle passage that connects the intermediate pressure chamber to the oil discharge destination is throttled. Therefore, during high speed traveling, the resistance of the oil flowing from the intermediate pressure chamber connected to the second cylinder chamber to the oil discharge destination is large. Therefore, the hydraulic pressure in the intermediate pressure chamber connected to the second cylinder chamber increases and the auxiliary steering force decreases. When stopped or running at low speed, the variable throttle passage is opened, and the resistance of the oil flowing from the intermediate pressure chamber connected to the second cylinder chamber to the oil discharge destination becomes small. Therefore, the hydraulic pressure in the intermediate pressure chamber connected to the second cylinder chamber becomes small, and the auxiliary steering force becomes large.

When the steering wheel is steered in the second direction,
It is similar to this.

Thus, the auxiliary steering force can be changed depending on the vehicle speed. When the vehicle is traveling at high speed, the auxiliary steering force can be reduced to obtain a heavy steering characteristic, and when the vehicle is stopped or traveling at a low speed, the auxiliary steering force can be increased to obtain a light steering characteristic.

Further, since the intermediate pressure chamber is provided between the oil feed chamber and the oil drain chamber, it is possible to prevent noise from being generated.

[0012]

2. Description of the Related Art An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a main part of a power steering apparatus for an automobile, and FIG. 2 shows an enlarged vertical cross section of a hydraulic control valve and a hydraulic circuit thereof. 3 to 7 show enlarged cross-sections of various parts of the hydraulic control valve, and FIG. 8 schematically shows the cross-section of the hydraulic control valve and its hydraulic circuit. In addition, in the following description, up, down, left and right refer to FIG. The rotation direction is the direction viewed from above, the clockwise direction is the right direction, and the counterclockwise direction is the left direction.

A power cylinder (2) extending horizontally in the left-right direction is integrally formed in the gear housing (1) of the power steering device. The power cylinder (2) penetrates through the power cylinder (2) to horizontally extend in the left-right direction. The rack bar (3) that extends to the gear housing
It is held in (1) so that it can move axially (left and right).
A piston (4) is provided on the rack rod (3) inside the power cylinder (2) .The piston (4) allows the inside of the power cylinder (2) to move between the right cylinder chamber (2a) and the left cylinder chamber (2a). It is divided into 2b).

A vertical cylindrical valve housing (5) is fixed on the gear housing (1).
A hydraulic control valve (6) is provided in (5). In addition, the input shaft (7) and output shaft (8) that extend in the vertical direction are connected to the torsion bar.
The components connected in a straight line by (9) are rotatably supported inside the gear housing (1) and the valve housing (5). The input shaft (7) is hollow and the torsion bar (9) is inserted inside. The upper end of the torsion bar (9) is closely fitted to the upper end of the input shaft (7) and fixed so as not to rotate relative to each other. Torsion bar (9)
The lower end of the shaft protrudes slightly below the input shaft (7), and the part of the torsion bar (9) near the lower end is tightly fitted to the lower end of the input shaft (7) so that they can rotate relative to each other. . An annular oil drain passage (10) is formed between the input shaft (7) and a portion of the torsion bar (9) excluding upper and lower ends. Input shaft (7)
The upper half of the is hollow, and the lower end of the input shaft (7) is fitted inside the upper part of the hollow so that they can rotate relative to each other. Then, the lower end of the torsion bar (9) protruding below the input shaft (7) is tightly fitted to the lower end of the hollow part of the input shaft (7) and fixed so that they do not rotate relative to each other. ing. The upper end of the input shaft (7) projects above the valve housing (5) and is connected to a handle (not shown). The upper middle portion of the input shaft (7) is rotatably supported by the ball bearing (11) on the upper housing portion of the valve housing (5). The lower part of the output shaft (8) is the gear housing
(1) It extends inside, and its lower end is rotatably supported by a ball bearing (not shown). A pinion (12) is formed in the middle of the output shaft (8) located in the gear housing (1), which engages with the rack part of the rack rod (3). A seal (13) is provided between the upper end of the valve housing (5) and the middle of the input shaft (7). A seal (14) is provided between the lower end of the valve housing (5) and the upper part of the output shaft (8).

Input shaft (7) in the valve housing (5)
The lower part of the cylinder constitutes a cylindrical valve body (15).
A cylindrical valve sleeve (16) is fitted between the valve body (15) and the peripheral wall (5a) of the valve housing (5) so that they can rotate relative to each other and is integral with the output shaft (8). It is fixedly connected at its lower end to the output shaft (8) for rotation. Between the upper end of the valve sleeve (16) and the valve body (15) and between the lower end of the valve sleeve (16) and the valve body (15), there are bushes (17) that concentrically rotate and support them. It is provided. The outer peripheral surface of the valve sleeve (16) is in close contact with the inner peripheral surface of the valve housing peripheral wall (5a). And this valve body (15) and valve sleeve (1
6) constitutes the main part of the hydraulic control valve (6).

As shown in detail in FIG. 2, the valve sleeve
An annular oil drain passage (18) is formed between the valve housing peripheral wall (5a) between the (16) and the seal (13) above it and the input shaft (7). On the outer peripheral surface of the valve sleeve (16)
One seal (19) is provided and these seals
Annular groove-shaped passages (20), (21), (22) and (23) are formed in the upper and lower four parts divided by (19).

As shown in FIGS. 4 to 8, the valve body (1
Eight axial (vertical) groove-shaped chambers (24) (25) (26) (27) with both upper and lower ends closed on the outer peripheral surface of 5) are formed at equal intervals in the circumferential direction. On the inner surface of the valve sleeve (16) corresponding to the portion between the chambers (24) to (27), eight similar chambers (2
8), (29), (30) and (31) are formed at equal intervals in the circumferential direction. Of the eight chambers (24) to (27) of the valve body (15),
The chambers (24) at the two symmetrical locations are the oil supply chambers, the chambers (25) at the two symmetrical locations that are 90 degrees apart from these are the oil discharge chambers, and the remaining four chambers (26) (27) are the intermediate pressure chambers. Has become. Valve sleeve
Among the eight chambers (28) to (31) of (16), the four chambers (28) and (29) on both sides of the fueling chamber (24) are the oil feeding chamber and the remaining four chambers (30) (3).
1) is an intermediate pressure chamber. And the adjacent room (24) ~
Valve body (15) and valve sleeve (16) between (31)
The gap between and is the narrowed portion.

As shown in detail in FIG. 5, the valve body (1
A lower communication hole (32) for communicating the oil discharge passage (10) inside the oil discharge chamber (25) is formed in (5). As shown in detail in FIG. 3, the valve body (15) has an oil drain passage (18) above the valve sleeve (16) and an oil drain passage (1) inside the valve body (15).
An upper communication hole (33) for communicating with the (0) is formed, and the valve housing peripheral wall (5a) is provided with a first oil discharge port (34) communicating with the oil discharge passage (18) inside thereof. The first oil discharge port (34) is connected to the oil tank (36), which is the oil discharge destination, via the first oil discharge pipe (35).

As shown in detail in FIG. 5, the valve sleeve
A communication hole (37) is formed in (16) to connect the annular oil supply passage (20) on the outer peripheral surface thereof to the oil supply chamber (24), and the valve housing peripheral wall (5a) is connected to this oil supply passage (20). A refueling port (38) is formed. And this refueling port (38) is the refueling pipe (39)
Is connected to a hydraulic pump (40) which is a hydraulic power source.

As shown in detail in FIG. 4, the valve sleeve
(16), the annular right side oil passage (21) and the oil supply chamber (2
Communication hole that communicates with the right oil transfer chamber (28) on the right of the rotation direction of 4)
(41) is formed, and the right side oil feed port (42) communicating with the right side oil feed passage (21) is formed in the valve housing peripheral wall (5a). Then, the right side oil supply port (42) is connected to the right side oil supply pipe (43).
Through the right cylinder chamber (2a) of the power cylinder (2).

As shown in detail in FIG. 7, the valve sleeve
A communication hole (44) that connects the left side oil supply passage (22) on the outer peripheral surface thereof to the left side oil supply chamber (29) on the left side in the rotation direction of the oil supply chamber (24) in (16).
And a left oil feed port (45) communicating with the left oil feed passage (22) is formed in the valve housing peripheral wall (5a). The left oil feed port (45) is connected to the left cylinder chamber (2b) of the power cylinder (2) via the left oil feed pipe (46).

As shown in detail in FIG. 6, the valve sleeve
In (16), the annular oil drain passage (23) on the outer peripheral surface and the right oil transfer chamber (2
1) A right side first intermediate pressure chamber (26) adjacent to the right in the rotational direction and a left side first left intermediate pressure chamber (27) adjacent to the left side in the rotational direction of the left oil feed chamber (22). 48) are respectively formed, and a second oil discharge port (49) communicating with the oil discharge passage (23) is formed in the valve housing peripheral wall (5a). Then, the second oil discharge port (4
9) is connected to the tank (36) via the variable throttle passage (50). The throttle passage (50) has a second drain port (49) and a tank (3
It is composed of a second oil discharge pipe (51) connecting to 6) and a variable throttle valve (52) provided in the middle thereof.

FIG. 8 shows a valve body (15) and a valve sleeve (16) which constitute the hydraulic control valve (6), and a tank (36), a pump (41) and a power cylinder (2) with them.
Shows the connection relationship with. As is clear from the above description, the communication holes (37) (41) (44) of the valve sleeve (16).
Although (47) and (48) are formed at different positions in the axial direction depending on the type, they are shown in the same cross section in FIG. 8 for convenience of explanation. In addition, annular passages (20) (21) (22) (23)
Is also formed by changing the axial position on the same diameter, but in FIG. 8, these are indicated by circles having different diameters.

An actuator (53) for adjusting the throttle opening of the throttle valve (52) is connected to a control device (54) using a microcomputer or the like, and the control device (54) has an appropriate vehicle speed sensor. (55) is connected. Then, the control device (54) responds to the vehicle speed detected by the vehicle speed sensor (55) through the actuator (53) as follows in the throttle passage (5
The throttle opening of 0) is adjusted. That is,
When stopped and traveling at a low speed lower than a predetermined speed, the throttle valve (52) is opened to the maximum and the throttle opening is maximized. When traveling at a higher speed than the specified speed, throttle the throttle valve (52) to the maximum to minimize the throttle opening, or
Close (52) completely. Then, at an intermediate vehicle speed between these, the throttle opening degree is reduced as the vehicle speed increases.

In the above power steering apparatus, when the steering wheel is steered to the right, the input shaft (7) is rotated to the right, and the rotation of the input shaft (7) twists the torsion bar (9). While being transmitted to the output shaft (8), the output shaft (8) is also rotated to the right with respect to the valve housing (5). Therefore, the pinion (12) rotates to the right, which moves the rack rod (3) to the left and steers the wheels (not shown) to the right. at the same time,
By twisting the torsion bar (9), the input shaft
(7) rotates to the right with respect to the output shaft (8) and the valve body (1
5) will rotate to the right relative to the valve sleeve (16). Therefore, the space between the fuel supply chamber (24) and the right side oil supply chamber (28) is opened, and the space between the oil supply chamber (24) and the left side oil supply chamber (29) is closed. Therefore, the pressure oil supplied from the pump (41) to the oil supply chamber (24) is
From the right oil transfer chamber (28) to the right oil transfer passage (21) and right oil transfer pipe
Through (43), right cylinder chamber (2a) of power cylinder (2)
Sent to. Then, as a result of this, a leftward assisting steering force equal to the difference between the hydraulic pressure acting on the right cylinder chamber (2a) and the hydraulic pressure acting on the left cylinder chamber (2b) as described later is applied to the rack rod (3).
And the movement of the rack bar (3) to the left by steering the steering wheel is assisted. By moving the rack rod (3) to the left in this way, the oil in the left cylinder chamber (2b) is transferred to the left oil pipe.
(46) and the left side oil supply passage (22), and enters the left side oil supply chamber (29), the left side first intermediate pressure chamber (27), the left side second intermediate pressure chamber (31),
Oil drainage chamber (25), lower communication hole (32) of valve body (15), oil drain passage (10) in valve body (15), upper communication hole (33) of valve body (15), valve body ( 15) Oil drain passage around (1
8), the first oil discharge port (34) and the first oil discharge pipe (35) in order,
Returned to tank (36). A part of the oil that has flowed from the left oil feed chamber (29) to the left first intermediate pressure chamber (27) is returned to the tank (36) through the oil drain passage (23) and the throttle passage (50). . At this time, depending on the opening degree of the throttle passage (50), the first oil discharge pipe (35)
The ratio of the amount of oil returning to the tank (36) through the throttle passage (50) and the amount of oil returning to the tank (36) changes, and the hydraulic pressure in the first left intermediate pressure chamber (27) changes. That is, when the throttle opening is small, the resistance of the throttle passage (50) is large, so that the amount of oil returning to the tank (36) through the throttle passage (50) is small. At this time, the oil is gradually depressurized while passing through the intermediate pressure chambers (27) and (31), and is not suddenly depressurized. Therefore, the first left
The hydraulic pressure in the intermediate pressure chamber (27) becomes high. On the other hand, when the throttle opening is large, the resistance of the throttle passage (50) is small, so that the amount of oil returning to the tank (36) through the throttle passage (50) is large. Therefore, the hydraulic pressure in the left first intermediate pressure chamber (27) becomes low. As described above, when the vehicle travels at high speed, the throttle opening of the throttle passage (40) becomes small, so that the hydraulic pressure in the left first intermediate pressure chamber (27) becomes high. Therefore, from the left first intermediate pressure chamber (27) to the left oil feed chamber (2
The hydraulic pressure acting on the left cylinder chamber (2b) through 9) becomes high, and the auxiliary steering force acting on the rack rod (3) becomes small.
Then, by reducing the auxiliary steering force, heavy steering characteristics suitable for steering during high speed traveling can be obtained. On the contrary, when the vehicle is stopped or running at low speed, the throttle opening of the throttle passage (50) becomes large, so that the hydraulic pressure in the left first intermediate pressure chamber (27) becomes small. Therefore, the hydraulic pressure acting on the left cylinder chamber (2b) is lowered, and the auxiliary steering force acting on the rack rod (3) is increased. Then, by increasing the auxiliary steering force, a light steering characteristic suitable for steering at the time of stop or low speed traveling can be obtained. Further, at these intermediate vehicle speeds, an intermediate auxiliary steering force corresponding to the vehicle speed is generated, and an intermediate steering characteristic is obtained.

When the steering wheel is steered to the left, the output shaft (8)
Is rotated to the left, the rack bar (3) is moved to the right, and the wheels are steered to the right. At the same time, the torsion of the torsion bar (9) causes the valve body (15) to rotate counterclockwise with respect to the valve sleeve (16), opening the space between the oil supply chamber (24) and the left oil supply chamber (29), The space between the chamber (24) and the right oil transfer chamber (28) is closed.
Therefore, the pressure oil supplied from the pump (41) to the oil supply chamber (24) is sent to the left cylinder chamber (2b) of the power cylinder (2),
As a result, the hydraulic pressure acting on the left cylinder chamber (2b) and the right side first
From the intermediate pressure chamber (26) through the right side oil feed chamber (28) to the right cylinder chamber
A rightward auxiliary steering force, which is equal to the difference in hydraulic pressure acting on (2a), acts on the rack rod (3), and the rack rod is steered by the steering wheel.
The movement of (3) to the right is assisted. Others are the same as when the steering wheel is steered to the right.

[0028]

As described above, according to the power steering system of the present invention, it is possible to prevent the generation of noise in the hydraulic control valve and to change the auxiliary steering force depending on the vehicle speed. A heavy steering characteristic with a small steering force can be obtained, and a light steering characteristic with a large auxiliary steering force can be obtained when the vehicle is stopped or traveling at a low speed.

[Brief description of drawings]

FIG. 1 is a drawing showing an embodiment of the present invention, which is a drawing showing a longitudinal section of a main part of a power steering apparatus and its hydraulic circuit.

FIG. 2 is a drawing showing a longitudinal section of a hydraulic control valve portion of the power steering apparatus of FIG. 1 and a hydraulic circuit thereof.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a sectional view taken along line IV-IV in FIG.

5 is a cross-sectional view taken along line VV of FIG.

6 is a cross-sectional view taken along the line VI-VI of FIG.

7 is a sectional view taken along line VII-VII of FIG.

FIG. 8 is a drawing schematically showing a cross section of a hydraulic control valve and its hydraulic circuit.

[Explanation of symbols]

 (2) Power cylinder (2a) Right cylinder chamber (2b) Left cylinder chamber (3) Rack rod (4) Piston (6) Hydraulic control valve (7) Input shaft (8) Output shaft (9) Torsion bar (12) Pinion (15) Valve body (16) Valve sleeve (24) Oil supply chamber (25) Oil drainage chamber (26) (27) Intermediate pressure chamber (28) (29) Oil delivery chamber (30) (31) Intermediate pressure chamber ( 36) Oil tank (40) Hydraulic pump (50) Variable throttle circuit

Claims (1)

[Claims] 1. An oil supply chamber connected to a hydraulic pressure source on the circumference of a cylindrical valve body and a valve sleeve which are coaxially displaced relative to each other, and to different destinations on both sides in the circumferential direction of the oil supply chamber. An oil feed chamber connected to each of the oil feed chambers, an oil drain chamber connected to the oil drain destination, and an intermediate pressure chamber between the oil drain chamber and the oil feed chamber are arranged side by side, and the above-mentioned relative relation is provided to a throttle portion interposed between these chambers. In a power steering system including a hydraulic control valve that controls the hydraulic pressure to be fed to the oil destination by a change in the throttle area that occurs with angular displacement, a variable throttle passage that connects the intermediate pressure chamber to the oil destination. Is provided, and the variable throttle passage is throttled as the vehicle speed increases.