JPH10264835A - Hydraulic power steering device - Google Patents

Abstract

(57) [Problem] To provide a hydraulic power steering device which is easy to process and inexpensive. SOLUTION: A piston 10 of a hydraulic power cylinder 3 for driving a steering member such as a tie rod connected to a wheel and a steering shaft connected to a steered wheel are mutually connected by a torsion bar 24, In the hydraulic power steering apparatus for selectively supplying hydraulic oil to one of the pair of cylinder chambers 11 and 12 of the hydraulic power cylinder 3 according to the torsion direction and the torsion angle of the hydraulic power cylinder 3 for steering, the torsion bar 24 is provided. Rotary valve 2 having at least two ports 53 and 54 for detecting the torsion direction and the torsion angle of the rotary valve 2
In response to the opening and closing of the ports 53 and 54 of the rotary valve 2, the spool 33 is controlled by the pressure oil selectively supplied to one of the pressure receiving chambers 39 and 40 of the spool 33 of the spool type control valve 32. And a spool-type control valve 32 for selectively supplying hydraulic oil from the hydraulic pump 14 to one of the pair of cylinder chambers 11 and 12 of the power cylinder 3 by sliding the hydraulic cylinder 14 to one of the cylinder chambers 11 and 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art A steering reaction force when a vehicle is stopped or running at a low speed is extremely large due to a large frictional force between a tire and a road surface, and a hydraulic power steering device for reducing this is used.

Usually, in a hydraulic power steering apparatus, a steering wheel and a pinion connected to a piston of a power cylinder for changing the direction of a wheel are connected to each other via a torsion bar, and the torsion direction of the torsion bar and the pinion are changed. In order to detect the torsion angle and to selectively supply the pressure oil to one of the cylinder chambers of the power cylinder in response to the torsion angle, a rotary valve is employed as described in Japanese Patent Application Laid-Open No. H2-224267. Was.

[0004]

The rotary valve described in Japanese Patent Laid-Open No. 24267/1990 has the advantage that the mechanical structure is simple and compact since the torsion of the torsion bar is directly detected by the rotary valve. Since a plurality of axial grooves having a predetermined interval and a predetermined width are formed on the outer peripheral surface of the stub shaft and the inner peripheral surface of the stub shaft sleeve surrounding the outer periphery of the stub shaft, respectively, two shafts are formed. Directional grooving is inferior in productivity to circumferential grooving and difficult to perform with high precision.

[0005]

SUMMARY OF THE INVENTION The present invention relates to an improvement of a hydraulic power steering apparatus which overcomes such difficulties, and a first aspect of the present invention relates to a steering member such as a tie rod connected to wheels. The piston of the hydraulic power cylinder that drives the steering wheel, and the steering shaft connected to the steered wheels,
A hydraulic power steering system which is interconnected with a torsion bar and selectively supplies hydraulic oil to one of a pair of cylinder chambers of the hydraulic power cylinder according to a torsion direction and a torsion angle of the torsion bar to perform steering; In the apparatus, any one of a rotary valve having at least two ports for detecting a torsion direction and a torsion angle of the torsion bar, and a pressure-receiving chamber at both ends of a spool of a spool-type control valve according to opening and closing of the ports of the rotary valve. A spool type in which the spool is slid to one or the other by pressure oil selectively supplied to the power cylinder to selectively supply pressure oil from a hydraulic pump to one of the pair of cylinder chambers of the power cylinder. And a control valve.

According to the first aspect of the present invention, the torsion angle of the torsion bar detected by the rotary valve is increased by the spool-type control valve to drive the power cylinder. The required amount of oil can be sufficiently obtained by the spool type control valve.

Further, according to the present invention, it is possible to form a necessary minimum number of ports in a rotary valve for detecting the torsion direction and the torsion angle of the torsion bar, and to increase the height. The use of the spool type control valve, which facilitates precision processing, can greatly improve processing precision and productivity.

[0010] Further, according to the present invention, the power assist amount (steering assist force) of the power steering can be reduced in response to an increase in the vehicle speed, and an appropriate driving feeling can be obtained.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the invention described in claims 1 to 3 shown in FIGS. 1 to 3 will be described below. In the hydraulic power steering apparatus 1, as shown in FIG.
And the hydraulic power cylinder 3 are integrally assembled, and the front wheel 5 is connected to the piston rod 9 of the hydraulic power cylinder 3 via the tie rod 4. As shown in FIG. The partition 10 is divided into a left cylinder chamber 11 and a right cylinder chamber 12.

A steering column shaft 7 integrated with the steering wheel 6 is connected via a steering joint 8 to a stub shaft 22 as an input shaft of the rotary servo valve 2.
When the stub shaft 22 is rotated clockwise or counterclockwise, the stub shaft 22 is driven to rotate correspondingly, and in response to the rotation of the stub shaft 22, the pressure oil is supplied to the right cylinder chamber 12 or the left cylinder chamber 12 of the hydraulic power cylinder 3. Pressure oil is supplied to the cylinder chamber 11, and the piston rod 9 is driven leftward or rightward,
The front wheel 5 can change its direction to the right or left.

As further shown in FIG. 2, in the rotary servo valve 2, a valve housing 20 and a gear housing 21 are integrally connected to each other, and an input terminal of the valve housing 20 is provided in the valve housing 20. A stub shaft 22 serving as an input shaft rotatably fitted on a side via a bearing 26, a torsion bar 24 for relatively twistably connecting the stub shaft 22 and a pinion 23 serving as an output shaft, a valve housing 20 and A stub shaft sleeve 25 serving as an input shaft sleeve that is coaxially and rotatably fitted between the stub shafts 22 is provided, and the pinion 23 is rotatably fitted to the gear housing 21 via a bearing 27, The pinion 23 meshes with a rack 13 integral with the piston rod 9, and the pinion 23 is moved by the rack 13 that moves integrally with the left and right sliding of the piston 10. Pinion 23 is adapted to be rotatably driven.

Further, the valve housing 20 has an oil supply port communicating with the discharge port 15 of the hydraulic pump 14 and the suction port 16 or the reserve tank 17 of the hydraulic pump 14 respectively.
28 and an oil discharge port 29 are formed, and a left cylinder port that communicates with the left cylinder chamber 11 and the right cylinder chamber 12 of the hydraulic power cylinder 3 through communication passages 60 and 61, respectively.
30 and a right cylinder port 31 are formed.

In the valve housing 20, there is formed a spool accommodating hole 34 into which the spool 33 of the spool type flow control valve 32 can be slidably fitted. As shown in FIG. A pair of left and right lands 35 are formed at a central portion of the spool 33 at predetermined intervals, and pressure receiving portions 36 are formed at both left and right ends of the spool 33, respectively. In the center position, the spool housing hole is formed so as to have a gap (underlap) s between both ends 35a of the pair of lands 35.
Circumferential grooves 37 and 38 are formed in 34, and the left cylinder port 30 and the right cylinder port 31 are opened in the circumferential grooves 37 and 38, respectively.

The pressure receiving chambers 39 and 40 at both ends in the spool storage hole 34 located outside the both ends of the spool storage hole 34 communicate with the outflow portions 41 and 42 on the outer end side of the spool 33 from both lands 35. Communication holes 43 and 44 are formed in the spool 33, and compression coil springs 45 are interposed in the pressure receiving chambers 39 and 40, respectively. The spool 33 is accommodated by the spring force of the two compression coil springs 45. The hole 34 is located at the center in the axial direction.

Further, in the rotary servo valve 2, as shown in FIG. 2, a circumferential groove communicating with the pressure receiving chambers 39 and 40 through communication passages 47 and 48 is formed on the outer peripheral surface of the stub shaft sleeve 25. 49 and 50 are formed, and in the stub shaft sleeve 25, a passage 51 opened in the circumferential groove 49 and a passage 52 opened in the circumferential groove 50 are directed in the diameter direction of the stub shaft sleeve 25. On the inner peripheral surface of the stub shaft sleeve 25, there are formed axial grooves 53 and 54 communicating with the passages 51 and 52, respectively.

Further, an axial groove 55 is formed on the outer peripheral surface of the stub shaft 22 so as to overlap with the axial grooves 53 and 54 of the stub shaft sleeve 25. A drain passage 56 communicating the two axial grooves 55 with each other is formed. The drain passage 56 is opened to the drain port 29 through the drain passage 57, and the drain flowing into the axial groove 55 is formed. Oil is drained to oil drain passages 56 and 57 and oil drain port 29
The oil is discharged to the reserve tank 17 via the oil drain passage 58.

Further, the communication passages 47 and 48 are communicated with each other via a bypass passage 46, and a solenoid valve 59 is provided in the bypass passage 46. The solenoid valve 59 increases the throttle opening in response to an increase in vehicle speed. .

Since the embodiment shown in FIGS. 1 to 3 is configured as described above, the steering wheel 6
When no steering force acts on the stub shaft 22 and the stub shaft 22 is in a neutral position, no external force acts on the front wheel 5 and the stub shaft 22 is directed straight, the stub shaft 22 and the stub shaft sleeve 25 Figure 3
The stub shaft sleeve is set as shown in the illustration
The overlap of the axial grooves 55 with respect to the 25 axial grooves 53 and 54 is equal, and the spool 33 of the spool type flow control valve 32 is also located at the axial center of the spool housing hole 34 by the spring force of both compression coil springs 45. As a result, both underlaps of the land 35 with respect to the respective circumferential grooves 37 and 38 are equal, so that the pressure oil discharged from the oil supply port 28 from the discharge port 15 of the hydraulic pump 14 is equally distributed in the circumferential grooves 37 and 38. While flowing, they also flow into the left cylinder chamber 11 and the right cylinder chamber 12 from the circumferential grooves 37 and 38 via the communication passages 60 and 61, respectively, and flow out from the circumferential grooves 37 and 38 to the outlets 41 and 42. Holes 43, 44, pressure receiving chamber 3
9, 40, compression coil spring 46, communication passage 48, passage 51, 5
2, axial grooves 53, 54, 55, oil drain passages 56, 57, oil drain port 2
The oil is discharged to the reserve tank 17 through the oil passage 9 and the oil discharge passage 58, and the pressure oil pressure in the pressure receiving chambers 39 and 40 is equalized. Therefore, the hydraulic pressures in both the left cylinder chamber 11 and the right cylinder chamber 12 are also equal, so that the front wheel 5
May maintain a straight-ahead state.

When the steering wheel 6 is turned clockwise to turn the automobile clockwise, only the stub shaft 22 is rotated clockwise and the overlap of the axial groove 55 with the axial groove 53 is The pressure receiving chamber 40 is larger than the overlap of the axial groove 55 with the
The pressure oil pressure in the pressure receiving chamber 39 increases more than the pressure oil pressure in the pressure receiving chamber 39, the spool 33 moves to the left, and the pressure from the oil supply port 28 to the left cylinder chamber 11 through the left cylinder port 30 and the communication passage 60. As the oil flows in, the oil in the right cylinder chamber 12 communicates with the communication passage 61,
Right cylinder port 31, circumferential groove 38, communication hole 44, pressure receiving chamber
40, the communication passage 48, the passage 52, the axial groove 54, the axial groove 55, are discharged to the reserve tank 17 through the oil drain passages 56, 57, 58,
As a result, the piston 10 and the piston rod 9 move rightward, the front wheel 5 turns rightward, and the vehicle can turn right.

When the vehicle stops, the solenoid valve 59 is fully opened, and there is no mutual flow of the pressure oil between the communication passages 47 and 48. The pressure difference between the pressure receiving chambers 39 and 40 is large in response to the change of the overlap of the direction groove 55, and the power assist amount is large.

However, as the vehicle travels and its traveling speed increases, the throttle opening of the solenoid valve 59 increases, and there is mutual flow of pressure oil between the communication passages 47 and 48. With respect to the change in the overlap of the axial groove 55 with the pressure groove 54, the pressure difference between the pressure receiving chambers 39 and 40 does not increase to the left, and the power assist amount gradually decreases.

In the illustrated embodiment, the high-pressure oil discharged from the hydraulic pump 14 passes through the spool type flow control valve 32 and does not flow through the rotary servo valve 2. It is easier than the processing of 54 and 55, and it is easy to improve the processing accuracy, so that productivity is good and cost can be reduced.

Further, since high-pressure oil does not flow through the rotary servo valve 2, the rotational resistance of the rotary servo valve 2 is small, and the operation of the steering wheel 6 is easy.

In the embodiment shown in FIGS. 1 to 3, the same hydraulic pump 14 is used to supply the pressurized oil to the rotary servo valve 2 and the spool type flow control valve, but as shown in FIG. The low-pressure hydraulic pump 62 and the high-pressure hydraulic pump 63 may supply hydraulic oil to the rotary servo valve 2 and the spool-type flow control valve 32. The same operation as the embodiment shown in FIGS. The effect can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic front view of an automobile provided with a hydraulic power steering apparatus according to the present invention.

FIG. 2 is a longitudinal sectional front view showing an embodiment of the hydraulic power steering apparatus shown in FIG. 1;

FIG. 3 is an explanatory diagram illustrating a circuit configuration of the hydraulic power steering device illustrated in FIG. 2;

FIG. 4 is an explanatory diagram of another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Hydraulic power steering device, 2 ... Rotary servo valve, 3 ... Hydraulic power cylinder, 4 ... Tie rod, 5
... Front wheel, 6 ... Steering wheel, 7 ...
Steering column shaft, 8 steering joint, 9 piston rod, 10 piston, 11 left cylinder chamber, 12 right cylinder chamber, 13 rack, 14 hydraulic pump,
15 ... discharge port, 16 ... suction port, 17 ... reserve tank, 20 ... valve housing, 21 ... gear housing, 22 ... stub shaft, 23 ... pinion, 24 ... torsion bar, 25 ... stub shaft sleeve, 26 ... bearing, 27 …bearing,
28 ... oil supply port, 29 ... oil discharge port, 30 ... left cylinder port, 31 ... right cylinder port, 32 ... spool type flow control valve, 33 ... spool, 34 ... spool storage hole, 35 ... land, 36 ... pressure receiving Part, 37 ... circumferential groove, 38 ... circumferential groove, 39 ...
Pressure receiving chamber, 40: Pressure receiving chamber, 41: Outflow section, 42: Outflow section, 43: Communication hole, 44: Communication hole, 45: Compression coil spring, 46: Bypass passage, 47: Communication hole, 48: Communication hole, 49 ... circumferential groove,
50: circumferential groove, 51: passage, 52: passage, 53: axial groove, 54
... Axial groove, 55 ... Axial groove, 56 ... Drain passage, 57 ... Drain passage, 59 ... Solenoid valve, 60 ... Communication passage, 61 ... Communication passage, 62 ... Low pressure hydraulic pump, 63… High pressure hydraulic pump.

Claims (3)

[Claims] 1. A torsion bar for connecting a piston of a hydraulic power cylinder for driving a steering member such as a tie rod connected to a wheel and a steering shaft connected to a steered wheel with a torsion bar. In a hydraulic power steering device that selectively supplies hydraulic oil to one of a pair of cylinder chambers of the hydraulic power cylinder according to a direction and a torsion angle to perform steering, a torsion bar torsion direction and a torsion angle are detected. A rotary valve having at least two ports, and pressurized oil selectively supplied to one of pressure-receiving chambers at both ends of a spool of a spool-type control valve according to opening and closing of the port of the rotary valve. To one of the pair of cylinder chambers of the power cylinder to selectively pressurize the hydraulic oil from the hydraulic pump. A hydraulic power steering device comprising a spool type control valve for supplying. 2. A compression coil spring is inserted into each of the pressure receiving chambers at both ends of the spool. The spool of the spool type control valve has two lands, and is located on the outer periphery of each land in a neutral state of the spool. Two circumferential grooves wider than the width of the land are respectively formed on the inner peripheral surface of the bubble sleeve, and a hydraulic discharge port communicated with a discharge port of the hydraulic pump is provided between the two circumferential grooves. And a cylinder chamber port communicated with a pair of cylinder chambers of the hydraulic power cylinder, the cylinder chamber port is opened in the two circumferential grooves, and has a small diameter portion located outside the two lands. The two-end pressure receiving chamber is communicated with each other through a communication passage in the spool, and the rotary valve includes a stub shaft connected to one end of the torsion bar, and a stub shaft. A stub shaft sleeve that is relatively rotatably fitted to the outer periphery of the stub shaft and is connected to the other end of the torsion bar, and at least one shaft axial groove is formed on the outer peripheral surface of the stub shaft. At least one pair of sleeve axial grooves is formed on the inner peripheral surface of the stub shaft sleeve at both sides of the shaft axial groove, and the shaft axial groove communicates with a suction port of the hydraulic pump. 3. The power steering apparatus according to claim 2, wherein the pair of sleeve axial grooves communicate with the pressure receiving chambers at both ends. 3. A hydraulic passage communicating the pair of sleeve axial grooves and the pressure receiving chambers at both ends is communicated via a short-circuit oil passage.
3. The hydraulic power steering apparatus according to claim 2, wherein a vehicle speed-responsive variable throttle whose opening degree increases with increasing vehicle speed is interposed in the short-circuit oil passage.