JPH06239254A - Hydraulic power steering device - Google Patents

Abstract

PURPOSE:To reduce production cost by applying the constitution where the valve member of a variable throttle valve is interlocked with a member operating according to a steering angle, and the hydraulic pressure of a hydraulic actuator is changed according to a steering angle for providing auxiliary steering power without any electronic control device. CONSTITUTION:A hydraulic actuator 20 for generating steering power is provided, together with a hydraulic control valve 30 for controlling the hydraulic pressure applied to the actuator 20, according to steering resistance. Also, a variable throttle valve 60 is provided and the opening of the throttle section 66 of the valve 60 can be changed with the displacement of a valve member 62, and hydraulic pressure applied to the actuator 20 changes, according to the opening of the section 66. Furthermore, an interlock mechanism is provided for linking the operation of the valve member 62 to a member 3 operating according to a steering angle. According to this construction, the valve member 62 of the valve 60 can be displaced according to a steering angle, without use of an electronic control device, and auxiliary steering power can be provided at low cost.

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 system capable of applying a steering assist force according to a steering angle.

[0002]

2. Description of the Related Art A hydraulic actuator for generating a steering assist force and a hydraulic control valve for controlling the hydraulic pressure supplied to the hydraulic actuator according to the steering resistance are provided, and the hydraulic pressure supplied to the hydraulic actuator is increased when the steering resistance increases. 2. Description of the Related Art Conventionally, a hydraulic power steering device that increases a steering force and applies a steering assist force according to steering resistance has been used.

In such a hydraulic power steering system, the opening of the oil passage communicating with the hydraulic control valve is adjusted in order to satisfy the high steering response during turning and the steering stability during straight traveling. A variable throttle valve that changes depending on the displacement of the valve member, a solenoid that displaces the valve member according to an electromagnetic force, and an electronic control device that controls the solenoid according to operating conditions detected by a vehicle speed sensor, a steering angle sensor, or the like. The hydraulic pressure supplied to the hydraulic actuator is changed according to the opening of the oil passage.

[0004]

However, when the valve member of the variable throttle valve is controlled by the electronic control unit according to the operating condition detected by the sensor, the electronic control unit is expensive and the manufacturing cost is very high. There is a problem of becoming.

An object of the present invention is to provide a hydraulic power steering system which can solve the above-mentioned problems of the prior art.

[0006]

According to the present invention, a hydraulic actuator for generating a steering assist force, a hydraulic control valve for controlling the hydraulic pressure supplied to the hydraulic actuator according to steering resistance, and a hydraulic control valve communicating with the hydraulic control valve are provided. In a hydraulic power steering device including a variable throttle valve that changes the opening degree of the throttle section by the displacement of the valve member, and the hydraulic pressure supplied to the hydraulic actuator changes according to the opening degree of the valve section, the valve of the variable throttle valve An interlocking mechanism that interlocks the member with a member that operates according to the steering angle is provided.

[0007]

According to the structure of the present invention, by interlocking the valve member of the variable throttle valve with the member that operates according to the steering angle, the opening degree of the throttle portion communicating with the hydraulic control valve is changed according to the steering angle.
The hydraulic pressure supplied to the hydraulic actuator can be changed according to the steering angle. That is, the valve member of the variable throttle valve can be displaced according to the steering angle without using the electronic control device.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS.

A rack and pinion type hydraulic power steering system 1 shown in FIG. 1 has an input shaft 2 connected to a steering wheel (not shown) of a vehicle, and a torsion bar 6 attached to the input shaft 2.
The output shaft 3 is connected via. The torsion bar 6 is connected to the input shaft 2 via a pin 4 and is connected to the output shaft 3 via a serration 5. The input shaft 2 is supported by the valve housing 7 via a bearing 8 and is supported by the output shaft 3 via a bearing 12. The output shaft 3 has bearings 10 and 11
It is supported by the rack housing 9 via. A pinion 15 is formed on the output shaft 3, and the pinion 15
A steering wheel (not shown) is connected to the rack 16 that meshes with the. As a result, the rotation of the input shaft 2 due to steering is transmitted to the pinion 15 via the torsion bar 6, the rotation of the pinion 15 moves the rack 16 in the vehicle width direction, and the movement of the rack 16 causes steering of the vehicle. Done. Oil seals 42 and 43 are interposed between the input / output shafts 2 and 3 and the housing 7. The support yoke 40 that supports the rack 16 is pressed against the rack 16 by the elastic force of the spring 41.

A hydraulic cylinder 20 is provided as a hydraulic actuator that applies a steering assist force. The hydraulic cylinder 20 includes a cylinder tube configured by the rack housing 9 and a piston 21 integrated with the rack 16. A rotary control valve 30 is provided in order to supply pressure oil to the oil chambers 22 and 23 partitioned by the piston 21 according to the steering direction and steering resistance.

The control valve 30 is a cylindrical first valve 31 which is inserted into the valve housing 7 so as to be relatively rotatable.
And a second valve 32 inserted into the first valve 31 so as to be rotatable relative to the axis. The first valve 31 is connected to the output shaft 3 via a pin 29 so as to rotate together. The second valve 32 is formed integrally with the input shaft 2, and the outer peripheral portion of the input shaft 2 serves as the second valve 32, whereby the second valve 32 rotates together with the input shaft 2.

In the valve housing 7, an inlet port 34 connected to the pump 70, a first port 37 connected to one oil chamber 22 of the hydraulic cylinder 20, and a first port 37 connected to the other oil chamber 23. Two ports 38, a first outlet port 36 directly connected to the tank 71, and a second outlet port 61 connected to the tank 71 via a variable throttle valve 60 described later are provided. Each port 34, 36, 37,
38 and 61 communicate with each other through the inter-valve flow path 27 between the inner and outer circumferences of the first valve 31 and the second valve 32. The opening degree of the intervalve flow path 27 changes due to the relative rotation of the input shaft 2 and the output shaft 3.

That is, as shown in FIGS. 3 and 4, the first
In the inner circumference of the valve 31, the first valve side recesses 50a, 50b,
Eight 50c are formed at equal intervals in the circumferential direction,
On the outer circumference of the second valve 32, the second valve side concave portions 51a, 51
b and 51c are formed at eight locations at equal intervals in the circumferential direction, and the first valve-side recesses 50a, 50b and 50c and the second valve-side recesses 51a, 51b and 51c form the inter-valve flow passage 27. There is. FIG. 4 shows a development view of the second valve 32 by a solid line, shows first valve side recesses 50a, 50b, 50c by a chain line, and the first valve side recess 50
The second valve-side concave portion 51 is provided between the peripheral portions a, 50b, 50c.
a, 51b, 51c are located.

The first valve side concave portion is composed of two right steering concave portions 50a, two left steering concave portions 50b, and four connecting concave portions 50c. The right steering recess 50a communicates with the one oil chamber 22 of the hydraulic cylinder 20 from the first port 37 through a flow passage 53 formed in the first valve 31, and is located 180 ° away from each other in the circumferential direction. However, the left steering recess 50b is formed by the first valve 31.
The second port 38 communicates with the other oil chamber 23 of the hydraulic cylinder 22 via a flow path 54 formed in the same, and they are located 180 ° apart from each other in the circumferential direction. Further, the right steering recess 50a is arranged so as to be adjacent to the left steering recess 50b and the communication recess 50c.

The second valve side recesses are four pressure oil supply recesses 51a, two first pressure oil discharge recesses 51b, and
It is composed of two second pressure oil discharge recesses 51c. The pressure oil supply recess 51a communicates with the pump 70 from the inlet port 34 via the pressure oil supply passage 55 formed in the first valve 31, and is located 90 ° apart from each other in the circumferential direction. The first pressure oil discharge concave portion 51b passes between the input shaft 2 and the torsion bar 6 from the flow passage 52a formed in the input shaft 2, and the flow passage 52b formed in the input shaft 2.
Through the first outlet port 36 to the tank 71, and are located 180 ° apart from each other in the circumferential direction. The second pressure oil discharge concave portion 51 c is provided with a variable throttle valve 6 via a flow passage 59 formed in the first valve 31 via a second outlet port 61.
They are connected to each other at 0 and are located 180 ° apart from each other in the circumferential direction.

The first valve side recesses 50a, 50b, 5
0c along the axial direction and the second valve side concave portions 51a, 51
The space between the edges of the b and 51c along the axial direction is the narrowed portion A,
A ', B, B', C, C ', D, D'. The edges of the second valve side recesses 51a, 51b, 51c along the axial direction are chamfered. The recess 50c for communication
And the throttle portions B ', D'between the second pressure oil discharge concave portion 51c and
In FIG. 3, the width W of the chamfered portion of the edge (enclosed by Δ in FIG. 3) along the axial direction of the second pressure oil discharge concave portion 51 c is the edge (in FIG. 3) along the axial direction of the other second valve-side concave portion. It is made larger than the width W'of the chamfered portion (circled with circle) as shown in FIGS. As a result, under a constant steering resistance, the throttle portion between the communication recessed portion 50c and the second pressure oil discharge recessed portion 51c (hereinafter, "steering stabilization throttle portion").
The openings of B'and D'are made larger than the openings of the other throttle portions (hereinafter, "turnability improving throttle portions") A, A ', B, C, C', and D.

The input shaft 2 and the output shaft 3 relatively rotate due to the torsion of the torsion bar 6 due to the resistance transmitted from the road surface through the steering wheel. The relative rotation causes the first valve 31 and the second valve 32 to rotate relative to each other, whereby the opening degree of the inter-valve flow path 27 changes, and the hydraulic cylinder 20 that applies the steering assist force changes in accordance with the steering direction and the steering resistance. Pressure oil is supplied.

That is, FIG. 4 shows a state where steering is not performed, and the inlet port 34 and the outlet ports 36 and 61 are shown.
Are communicated with each other via the inter-valve flow path 27, the oil flowing from the pump 70 into the control valve 30 is returned to the tank 71, and no steering assist force is generated. When the first valve 31 and the second valve 32 rotate relative to each other due to the steering resistance generated by steering to the right from this state, as shown in FIG.
0 and one of the oil chambers 22 and the throttle portion A ′ between the pump 70 and the communication recess 50c adjacent to the left steering recess 50b have a large opening degree, so that the one oil chamber 22 And the first
The opening degree of the throttle portion B between the outlet port 36 and one throttle portion B ′ between the pump 70 and the second outlet port 61 is reduced, and the throttle portion between the pump 70 and the other oil chamber 23 is reduced. The opening degree of the throttle portion C'between the C and the pump 70 and the communication recess portion 50c adjacent to the right steering recess portion 50a becomes small, and the throttle portion D between the other oil chamber 23 and the first outlet port 36. And the opening degree of the other throttle portion D ′ between the pump 70 and the second outlet port 61 becomes large. As a result, the pressure oil having a pressure corresponding to the steering direction and the steering resistance is supplied to one oil chamber 22 of the hydraulic cylinder 20 by the flow of the pressure oil indicated by the arrow in the figure, and the other oil chamber 23 to the tank 71. The oil recirculates, and a steering assist force to the right of the vehicle acts on the rack 16 from the hydraulic cylinder 20. Further, when steering to the left, the input shaft 2 and the output shaft 3 relatively rotate in opposite directions, and the diaphragm A,
Since the opening of A'is small, the openings of the throttles B and B'are large, the openings of the throttles C and C'are large, and the openings of the throttles D and D'are small. The steering assisting force to the left of is applied to the rack 16 from the hydraulic cylinder 20.

The variable throttle valve 60 communicating with the second outlet port 61 has an insertion hole 6 formed in the valve housing 7.
6 has a spool (valve member) 62 inserted so as to be vertically displaceable in the figure. Each end of the insertion hole 66 has a plug 6
A compression coil spring 69 is inserted between the spring pressure adjusting screw 79 screwed into one plug 68a and the upper end of the spool 62, which is closed by 8a and 68b. An interlocking mechanism that interlocks the spool 62 with the rack 16 that is displaced according to the steering angle is provided. That is, the rod 62 is connected to the spool 62, and one end of the rod 61 penetrates the other plug 68b and the spring 6
It is pressed against the upper surface 16a of the rack 16 by the elastic force of 9, and the contact position between one end of the rod 61 and the upper surface 16a of the rack 16 changes according to the steering angle. As shown in FIG. 2, the upper surface 16a of the rack 16 is formed as an inclined surface 16a 'which is directed upward toward the end at a position where it abuts one end of the rod 61 near the steering limit.
As a result, in the vicinity of the steering limit, the rod 61 is pushed up by the inclined surface 16a ', so that the spool 62 is displaced upward, and in the vicinity of the straight steering position, it is displaced downward.

A peripheral groove 62a is formed on the outer periphery of the spool 62, a peripheral groove 66a is formed on the inner periphery of the insertion hole 66, and a narrowed portion 67 is formed between the peripheral grooves 62a and 66a. The opening degree of the throttle portion 67 becomes smaller as the steering angle becomes larger and the spool 62 is displaced upward, and becomes larger as the steering angle becomes smaller and the spool 62 is displaced downward. The maximum value of the opening degree of the throttle portion 67 is the throttle portions A, A ′, B, C for improving the turning performance in the state where the steering resistance does not act.
The minimum value of the opening of the throttle portion 67 is set to be equal to or larger than the openings of C ′ and D, and the throttle portion A for improving the turning property in the most closed state,
The openings are set to A ', B, C, C', D or less.

A flow path 58 is formed in the valve housing 7 to connect the throttle portion 67 to the second outlet port 61, and a through hole 75 is formed in the spool 66 to connect the throttle portion 67 to the space above the spool 62. A flow path 76 that connects the upper space of the spool 62 and the first outlet port 36 is formed in the valve housing 7. As a result, the steering stabilizing throttles B ′ and D ′ communicate with the tank 71 via the throttle 67 of the variable throttle valve 60. The spool 62
A drain passage 78 that connects the lower space and the upper space is formed in the spool 62.

According to the above construction, the spool 62 is displaced downward in the figure in the range where the steering angle is small, and the displacement of the spool 62 causes the opening degree of the throttle portion 67 to turn in a state where no steering resistance acts. Improvement throttles A, A ',
More than the opening of B, C, C ', D. Therefore, the opening degree of the intervalve flow passage 27 is determined by the opening degree of the steering stabilizing throttle portions B'and D ', and when the steering wheel is turned to the right, the hydraulic cylinder 20 is provided unless the opening degree of one steering stabilizing throttle portion B'is reduced. No pressure oil is supplied, and during left steering, no pressure oil is supplied to the hydraulic cylinder 20 unless the opening degree of the other steering stabilizing throttle D'is reduced. That is, in the range where the steering angle is small as indicated by the solid line in FIG. 6, unless the steering input torque is increased to increase the relative rotation amount between the first valve 31 and the second valve 32, Since the opening degree is large and the increase rate of the hydraulic pressure that generates the steering assist force is small, the steering stability can be satisfied.

When the steering angle becomes large and approaches the steering limit, the spool 62 is displaced upward in the drawing, and the displacement of the spool 62 causes the opening of the throttle portion 67 to improve the turning performance in the most closed state. Throttle parts A, A ', B, C, C',
It becomes less than the opening degree of D. Therefore, the steering stabilization throttle B ',
Even if the opening degree of D ′ is not reduced, the hydraulic oil can be supplied to the hydraulic cylinder 20 in accordance with the opening degrees of the throttle portions A, A ′, B, C, C ′, D for improving the turning performance. That is, when the steering angle becomes large and approaches the steering limit as shown by the one-dot chain line in FIG. 6, even if the steering input torque is small and the relative rotation amount between the first valve 31 and the second valve 32 is small, the valve-to-valve Since the opening degree of the flow path 27 is small and the increase rate of the hydraulic pressure for generating the steering assist force is large, it is possible to satisfy the high steering responsiveness.

A second embodiment of the present invention will be described with reference to FIGS.

A rack and pinion type hydraulic power steering system 1'shown in FIG. 7 is connected to an input shaft 2'which is connected to a steering wheel (not shown) of a vehicle and a torsion bar 6'to this input shaft 2 '. The output shaft 3'is provided. The torsion bar 6'is connected to the input shaft 2'via a pin 4'and to the output shaft 3'via a serration 5 '. The input shaft 2'is supported by a valve housing 7'via a bearing 8 ', and is supported by an output shaft 3'via a bearing 12'. The output shaft 3'is supported by a rack housing 9'via bearings 10 'and 11'. A pinion 15 'is formed on the output shaft 3', and a steering wheel (not shown) is connected to a rack 16 'meshing with the pinion 15'. As a result, the rotation of the input shaft 2'by steering is transmitted to the pinion 15 'through the torsion bar 6', and the rotation of the pinion 15 'moves the rack 16' in the vehicle width direction, so that the rack 16 'moves. The vehicle is steered by the movement. Oil seals 42 'and 43' are interposed between the input / output shafts 2'and 3'and the housing 7 '. In addition, the support yoke 4 that supports the rack 16 '
0'is pressed against the rack 16 'by the elastic force of the spring 41'.

A hydraulic cylinder 20 'is provided as a hydraulic actuator for applying a steering assist force. The hydraulic cylinder 20 'includes a cylinder tube constituted by a rack housing 9', and a piston 21 'integrated with the rack 16'. Since the pressure oil is supplied to the oil chambers 22 'and 23' partitioned by the piston 21 'according to the steering direction and the steering resistance, the rotary control valve 3
0'is provided.

The control valve 30 'includes a tubular member 26' which is inserted into the valve housing 7 'through a seal member 25' having elasticity such as an O-ring so as to be displaceable in the radial direction, and an axial member of the tubular member 26 '. A cylindrical first valve 31 'which is inserted so as to be relatively movable in the direction and rotatable relative to the axial center;
The first valve 31 'is provided with a second valve 32' which is inserted so as to be relatively movable in the axial direction and relatively rotatable about the axis. The gap between the inner peripheral surface of the valve housing 7'and the outer peripheral surface of the tubular member 26 'is defined by the input / output shafts 2', 3 '.
It is set to absorb the whirling of. The tubular member 2
The gap between the inner peripheral surface of 6'and the outer peripheral surface of the first valve 31 'is made as small as possible within the range in which the axial movement of the first valve 31' can be allowed so that oil leakage can be prevented. Set to. The first valve 31 'is connected to the output shaft 3'through a pin 29' so as to rotate together. In order to prevent the relative movement of the first valve 31 'in the axial direction with respect to the second valve 32' from being hindered, the first valve 3 of the pin 29 'is prevented.
The insertion hole into 1'is a long hole. The second valve 3
2'is integrally formed with the input shaft 2 ', and the outer peripheral portion of the input shaft 2'is made into a second valve 32', whereby the second valve 32 'rotates together with the input shaft 2'.

The pump 7 is attached to the valve housing 7 '.
The inlet port 34 'connected to 0', the outlet port 36 'connected to the tank 71', and the hydraulic cylinder 2
First port 37 'connected to one oil chamber 22' of 0 '
And a second port 38 'connected to the other oil chamber 23'. Each port 34 ', 36', 37 ',
38 'communicates with each other through an intervalve passage 27' between the inner and outer circumferences of the first valve 31 'and the second valve 32'. The opening degree of the inter-valve flow path 27 'is changed by the relative rotation of the input shaft 2'and the output shaft 3'.

That is, as shown in FIGS. 8 and 9, the first
Eight first valve-side recesses 50 'are formed in the inner circumference of the valve 31' at equal intervals in the circumferential direction.
Second valve-side concave portions 51 'are formed on the outer circumference of 2'at eight locations at equal intervals in the circumferential direction.
0'and the second valve-side recess 51 ', the inter-valve flow path 2
7'is constructed. 9 (1) and (2) show a developed view of the second valve 32 'by a solid line, a first valve side recess 50' by a chain line, and a second valve between the first valve side recesses 50 'in the circumferential direction. The side recess 51 'is located.

The first valve side concave portion 50 'is formed by the cylindrical member 2
A cylindrical member 2 which communicates with the first port 37 'through a flow path 53' formed in 6'and the first valve 31 '.
6'and one communicating with the second port 38 'via the flow path 54' formed in the first valve 31 'are alternately arranged in parallel along the circumferential direction. The second valve-side recess 51 'communicates with the inlet port 34' via a pressure oil supply passage 55 'formed in the tubular member 26' and the first valve 31 ', and the outlet port 36'. And those communicating with each other via a variable throttle valve 60 ', which will be described later, are alternately arranged in parallel along the circumferential direction.

The circumferential portions between the edge of the first valve side recess 50 'along the axial direction and the edge of the second valve side recess 51' along the axial direction are narrowed portions A, B, C, D. . The second
An edge along the axial direction of the valve-side concave portion 51 'is a chamfered portion, and the chamfered portion 51b' on the lower side in the drawing has a larger circumferential width than the chamfered portion 51a 'on the upper side.

The input shaft 2'and the output shaft 3'are relatively rotated by the torsion of the torsion bar 6'caused by the resistance transmitted from the road surface through the steering wheel. The relative rotation causes the first valve 31 'and the second valve 32' to rotate relative to each other, thereby changing the opening degree of the inter-valve flow path 27 ', and the steering direction and steering to the hydraulic cylinder 20' for applying the steering assist force. Pressure oil is supplied according to the resistance.

That is, FIGS. 8 and 9 show a state where steering is not performed, and the inlet port 34 'and the outlet port 3 are shown.
6'communicates with each other through the inter-valve flow path 27 ', and the oil flowing from the pump 70' into the control valve 30 'is returned to the tank 71', and no steering assist force is generated. When the first valve 31 'and the second valve 32' rotate relative to each other due to steering resistance generated by steering to the left or right from this state, the opening of the throttle portion A increases and the opening of the throttle portion B decreases. ,
The opening degree of the throttle section C becomes smaller and the opening degree of the throttle section D becomes larger. As a result, one of the oil chambers 2 of the hydraulic cylinder 20 'is
2'is supplied with pressure oil having a pressure corresponding to the steering direction and the steering resistance, and oil is recirculated from the other oil chamber 23 'to the tank 71', so that steering assisting force to one side of the vehicle is provided to the hydraulic cylinder. Two
Acts on rack 16 'from 0'. When the steering wheel is steered to the left or right, the input shaft 2'and the output shaft 3'are relatively rotated in opposite directions, and the opening of the throttle portion A is decreased, the opening of the throttle portion B is increased, and the opening of the throttle portion C is increased. Since the degree is increased and the opening degree of the throttle portion D is decreased, the steering assisting force to the other left and right of the vehicle acts on the rack 16 'from the hydraulic cylinder 20'.

Outlet port 36 'through variable throttle valve 60'
The second valve-side recess 51 'that communicates with the second valve-side recess 51' communicates with the space between the inner and outer circumferences of the torsion bar 6'and the input shaft 2'through the flow path 52a 'formed in the input shaft 2'. ′ And the space between the inner and outer circumferences of the input shaft 2 ′ are
Is communicated with the space below the first valve 31 'through a flow path 52b' formed in the space, and the space below the first valve 31 'is
It communicates with the variable throttle valve 60 'through the flow path 57' formed in the tubular member 26 'and the valve housing 7'. The variable throttle valve 60 'communicates with the outlet port 36' from the flow path 58 'formed in the valve housing 7'through the space above the first valve 31'.

The variable throttle valve 60 'is a spool (valve) which is vertically displaceable in the drawing and is non-rotatably inserted about the shaft center in an insertion hole 66' formed in the valve housing 7'through a rotation stopper 80 '. Member) 62 '. One end of the insertion hole 66 'is closed by a plug 68' and the other end is closed by a rack housing 9 '. An interlocking mechanism that interlocks the spool 62 'with the output shaft 3'which rotates according to the steering angle is provided. That is, a screw shaft 61 'is coaxially connected to the lower portion of the spool 62', a gear 81 'supported by bearings 83', 84 'is screwed onto the screw shaft 61', and a gear meshing with the gear 81 '. 82 'is spline-fitted to the output shaft 3'. As a result, when the steering wheel is steered to the left or right from the straight-ahead steering position, the rotation of the output shaft 3'is transmitted to the screw shaft 61 'through the gears 81' and 82 ', and the screw shaft 61' rotates in one direction, whereby the spool 62 is rotated. ′ Is displaced downward. When the steering wheel is steered to the left or right from the straight-ahead steering position, the rotation of the output shaft 3'is transmitted to the screw shaft 61 'via the gears 81' and 82 ', and the screw shaft 61' rotates in the other direction to rotate the spool 62 '. Is displaced upwards.

A pair of circumferential grooves 6 are formed on the outer circumference of the spool 62 '.
2a ', 62b' are formed and both circumferential grooves 62a ', 62b are formed.
A peripheral groove 66a 'is formed on the inner periphery of the insertion hole 66' between b ', and one peripheral groove 62a' on the outer periphery of the spool 62 '.
The first throttle portion 67a 'is formed between the inner peripheral groove 66a' of the insertion hole 66 'and the other peripheral groove 62b' of the outer periphery of the spool 62 'and the inner peripheral groove 66a of the insertion hole 66'. The second narrowed portion 67b 'is formed between the first and second portions. Both throttle parts 67a ',
The openings of 67b 'in the straight steering state are made equal.
Further, the opening degree of the first throttle portion 67a 'becomes smaller as the steering angle to the left or right becomes larger and the spool 62' is displaced downward. Further, the opening degree of the second throttle portion 67b 'is such that the steering angle to the other of the left and right becomes large and the spool 62' is opened.
Becomes smaller when is displaced upward. That is, as the steering angle increases, the opening degree of either of the throttle portions 67a 'and 67b' decreases.

One circumferential groove 6 on the outer circumference of the spool 62 '
2a 'communicates from the flow passage 57' to the space below the first valve 31 ', and the other circumferential groove 62b' communicates from the flow passage 58 'to the outlet port 36' through the space above the first valve 31 '. To do. As a result, the hydraulic pressure on the upstream side of the first throttle portion 67a 'acts on the lower surface of the first valve 31'. Further, the hydraulic pressure in the outlet port 36 'and the elastic force of the spring 65' built into the valve housing 7'act on the upper surface of the first valve 31 '.

According to the above construction, since the vertical movement amount of the spool 62 'is small in the range where the steering angle is small, neither opening of both throttle parts 67a' and 67b 'of the variable throttle valve 60' is so small. . Therefore, the hydraulic pressure acting on the lower surface of the first valve 31 'becomes small. As a result, the first valve-side recess 50 'becomes the second valve-side recess 51'.
As shown in (1) of FIG. 9, the throttle portion A of the inter-valve flow passage 27 'is positioned below the constant steering resistance.
The opening degrees of B, C and D become large. As a result, in the range where the steering angle is small as shown by the solid line in FIG.
Unless the steering input torque is increased to increase the relative rotation amount between the first valve 31 'and the second valve 32', the opening degree of the intervalve passage 27 'is large and the increase rate of the hydraulic pressure for generating the steering assist force is large. Since it is small, the steering stability can be satisfied.

As the steering angle increases, the vertical movement amount of the spool 62 'also increases, so that the opening of either of the throttle portions 67a' and 67b 'of the variable throttle valve 60' decreases. Therefore, the hydraulic pressure acting on the lower surface of the first valve 31 'increases as the steering angle decreases. As a result, as shown in (2) of FIG. 9, the first valve-side recessed portion 50 'is displaced upward with respect to the second valve-side recessed portion 51', and the inter-valve flow path 27 'under the constant steering resistance. The apertures of the throttles A, B, C, D become smaller. As a result, in the range where the steering angle is large as indicated by the one-dot chain line in FIG. 6, even if the steering input torque is small and the relative rotation amount between the first valve 31 'and the second valve 32' is small, the inter-valve flow path 27 Since the opening of ′ is small and the rate of increase of the hydraulic pressure for generating the steering assist force is large, it is possible to satisfy the high responsiveness of steering.

According to the structure of the second embodiment, the input / output shafts 2 ', 3'because of the radial displacement of the tubular member 26' inserted into the housing 7'through the elastic sealing member 25 '. It is possible to absorb the whirling. Since the first valve 31 'is inserted into the tubular member 26' so as to be movable in the axial direction, the axial movement of the first valve 31 'according to the steering angle is not hindered by the seal member 25', and the steering is performed. It is possible to obtain optimum steering characteristics according to the angle. Also, the second
Since it is not necessary to move the valve 32 ′ in the axial direction, a portion such as a spline that causes rattling due to long-term use is not required, and an appropriate steering assist force can be applied according to steering resistance.

The present invention is not limited to the above embodiment. For example, although the present invention is applied to the rack and pinion type hydraulic power steering device in the above-described embodiments, it can be applied to, for example, a ball screw type hydraulic power steering device.

[0042]

According to the hydraulic power steering system of the present invention, it is possible to apply a steering assist force according to the steering angle without using an electronic control unit, and it is possible to greatly reduce the manufacturing cost.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a hydraulic power steering device according to a first embodiment of the present invention.

FIG. 2 is a structural explanatory view of a main part of the hydraulic power steering device according to the first embodiment of the present invention.

FIG. 3 is an explanatory view of a cross-sectional structure of the control valve of the first embodiment of the present invention.

FIG. 4 is a development view of the control valve according to the first embodiment of the present invention.

FIG. 5 is an enlarged view of a main part of the control valve according to the first embodiment of the present invention.

FIG. 6 is a diagram showing a relationship between an input torque and an oil pressure and a relationship between an input shaft torsion angle and an oil pressure in the hydraulic power steering system according to the embodiment of the present invention.

FIG. 7 is a vertical sectional view of a hydraulic power steering device according to a second embodiment of the present invention.

FIG. 8 is an explanatory view of a cross sectional structure of a control valve according to a second embodiment of the present invention.

FIG. 9 is a development view of a control valve according to a second embodiment of the present invention.

[Explanation of symbols]

 3'output shaft 16 'rack 20, 20' hydraulic cylinder 30, 30 'control valve 60, 60' variable throttle valve 62, 62 'spool 67, 67' throttle section

Claims (1)

[Claims] 1. A hydraulic actuator for generating steering assist force, a hydraulic control valve for controlling hydraulic pressure supplied to the hydraulic actuator according to steering resistance, and an opening of a throttle portion communicating with the hydraulic control valve. In a hydraulic power steering device in which the hydraulic pressure supplied to the hydraulic actuator changes in accordance with the opening of the throttle portion, the valve member of the variable throttle valve is operated in accordance with the steering angle. The hydraulic power steering device is characterized in that an interlocking mechanism for interlocking with the member to be operated is provided.