JPH07156811A - Hydraulic control valve - Google Patents

Abstract

PURPOSE:To prevent the rapid change of the hydraulic control characteristic by providing an auxiliary elastic member to apply the elastic force in the direction to prevent the relative rotation when the relative rotation between a pair of members to be returned to the neutral position by a main elastic member exceeds the specified value. CONSTITUTION:In a hydraulic power steering device 1, an output shaft 3 is connected to a cylindrical input shaft 2 (a first member) to be connected to a steering wheel of a vehicle through a torsion bar 6 (a main elastic member). On the other hand, the pressure oil is fed from a hydraulic control valve 30 to a hydraulic cylinder 20 to provide the auxiliary steering force according to the steering resistance. The hydraulic control valve 30 is provided with a cylindrical valve member 31 to be fitted on the outer circumference of the input shaft 2 in a relatively rotatable manner. In this constitution, a first spring 61 (a main elastic member) and a second spring 62 (an auxiliary elastic member) are mounted on the upper end surface of the output shaft 3. When required, the relative rotation of the input shaft 2 and the valve member 31 is prevented by the respective elastic forces of the torsion bar 6, the first spring 61, and the second spring 62.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve for controlling hydraulic pressure by changing the opening of a throttle according to the relative rotation amount of a first member and a second member. It is suitable for controlling the hydraulic pressure applied to the applied hydraulic actuator.

[0002]

2. Description of the Related Art An input shaft that rotates by operating a handle,
An output shaft connected to the input shaft via a torsion bar, a pinion formed on the output shaft, and a rack that meshes with the pinion are provided, and steering wheels are interlocked with the rack to rotate the input shaft. Torsion bar, output shaft,
2. Description of the Related Art A hydraulic power steering apparatus has been conventionally used in which a pinion is transmitted to a rack, steering is performed by moving the rack in an axial direction, and a steering assist force is applied by a hydraulic actuator. As a hydraulic control valve that acts on the hydraulic actuator, a tubular valve member that rotates together with the output shaft and rotates relative to the input shaft, and an oil passage formed between the valve member and the input shaft are formed. The valve member and the input shaft return to the neutral position due to the elastic force of the torsion bar, and the opening degree of the throttle part changes according to the relative rotation amount of the valve member and the input shaft from the neutral position. What controls the hydraulic pressure is used.

In the above hydraulic control valve, the valve member and the input shaft are returned to the neutral position only by the elastic force of the torsion bar. Therefore, even if the torque acting on the input shaft is not so large, the input shaft is not so large. And the valve member rotate relative to each other,
High-pressure oil is supplied to the hydraulic actuator to generate steering assist force. Then, there arises a problem that traveling stability is deteriorated when traveling straight ahead or in a range where the steering angle is small.

Therefore, in plan view C separately from the torsion bar.
There has been proposed a hydraulic power steering device that applies an elastic force that returns a valve member and an input shaft to a neutral position by using a shaped spring (see Japanese Patent Laid-Open No. 2-133283). The C-shaped spring exerts a preload in a direction that prevents the valve member and the input shaft from rotating relative to each other, so that steering assist is performed even if the input torque acting on the input shaft increases until the preload is released. By preventing high pressure oil from being supplied to the force generating hydraulic actuator, it is possible to improve traveling stability during straight traveling and in a range where the steering angle is small.

[0005]

Since the C-shaped spring of the hydraulic control valve of the above-mentioned conventional example applies an elastic force for returning the valve member and the input shaft to the neutral position, the valve member as described above is used. Although it is possible to apply a preload in the direction that prevents relative rotation of the input shaft and the input shaft, after the preload is released,
The elastic force in the direction in which the relative rotation of the valve member and the input shaft is prevented is only applied in proportion to the relative rotation amount. Further, the elastic force applied by the torsion bar in the direction of blocking the relative rotation between the valve member and the input shaft is also proportional to the relative rotation amount. That is, the relative rotation amount between the input shaft and the valve member changes in proportion to the input torque after the preload by the C-shaped spring is released. However, the hydraulic pressure acting on the steering assist force generating hydraulic actuator is not proportional to the relative rotation amount of the valve member and the input shaft, and changes abruptly when the relative rotation amount of the input shaft and the valve member exceeds a certain level. Therefore, in the conventional hydraulic power steering system using the hydraulic control valve, when the input torque exceeds a certain level, the rate of increase in the steering assist force increases rapidly, and the feeling of response when operating the steering wheel is suddenly lost, resulting in a steerable steering feel. There is a problem of lowering the ring.

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

[0007]

The present invention comprises a first member,
A second member that is rotatable relative to the first member; a main elastic member that exerts an elastic force that returns both members to a neutral position; and a throttle portion that is formed in an oil passage between both members, In a valve that controls the hydraulic pressure by changing the opening of the throttle according to the amount of relative rotation from the neutral position of both members, the elastic force in the direction that prevents relative rotation of both members exceeds a certain amount. It is characterized in that an auxiliary elastic member for actuating is provided.

[0008]

According to the structure of the present invention, until the relative rotation amount of the first member and the second member becomes constant, the main elastic member exerts the elastic force in the direction to prevent the relative rotation, and the relative rotation amount is When it becomes a certain value or more, not only the main elastic member but also the auxiliary elastic member exerts the elastic force in the direction of preventing the relative rotation, so that the hydraulic control characteristic can be changed according to the relative rotation amount.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

The rack and pinion type hydraulic power steering system 1 shown in FIG. 2 has a cylindrical input shaft (first member) 2 connected to a steering wheel (not shown) of a vehicle, and the input shaft 2.
And an output shaft 3 connected via a torsion bar (main elastic member) 6. 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 a valve housing 7
Is supported by bearings 8 and the output shaft 3 is supported by rack housing 9 by 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 that meshes with the pinion 15. As a result, the rotation of the input shaft 2 due to the steering wheel operation is transmitted from the torsion bar 6, the output shaft 3, and the pinion 15 to the rack 16, and steering is performed by the axial movement of the rack 16. The rack 16
Is a support yoke 40 that is movable left and right in FIG.
And a rack housing 9 through the inner peripheral surface of a bush (not shown) having a diameter slightly larger than that of the rack 16, and its support yoke 40 is supported by a spring 41.
The pinion 15 and the rack 16 are pressed against each other to absorb the bending of the rack 16 and the like, thereby facilitating smooth engagement between the pinion 15 and the rack 16.

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. An oil pressure control valve 30 that supplies pressure oil according to the magnitude and direction of the steering resistance is provided in the oil chambers 22 and 23 partitioned by the piston 21.

The hydraulic control valve 30 is a cylindrical valve member (second member) 31 which is inserted into the valve housing 7 in a relatively rotatable manner and is fitted in the outer periphery of the input shaft 2 in a relatively rotatable manner. Is equipped with. As shown in FIG. 3, the valve member 31 is connected to the output shaft 3 via a pin 32 so as to rotate together. Further, as shown in FIG. 2, in the valve housing 7, an inlet port 34 connected to the pump 33, an outlet port 36 connected to the tank 35,
A first port 37 connected to one oil chamber 22 of the hydraulic cylinder 20 and a second port 38 connected to the other oil chamber 23 are arranged. As shown in FIG. 4, the ports 34, 36, 37, 38 communicate with each other via an oil passage 27 between the input shaft 2 and the valve member 31. In the oil passage 27, throttle portions A, B, C, and D whose opening degree changes according to the relative rotation amount of the input shaft 2 and the valve member 31 from the neutral position due to the torsion of the torsion bar 6 are formed. .

That is, the first recesses 50 along the axial direction are formed on the inner circumference of the valve member 31 at eight locations at equal intervals in the circumferential direction. Eight second recesses 51 are formed in the outer circumference of the input shaft 2 at equal intervals in the circumferential direction so as to face each other in the circumferential direction of the first recess 50. The first recess 50 is provided in the flow path 5 of the valve member 31.
The one communicating with the first port 37 via 3 and the one communicating with the second port 38 via the flow path 54 of the valve member 31 are alternately arranged in parallel in the circumferential direction. The second recess 51 communicates with the inlet port 34 via the flow passage 55 of the valve member 31, and the flow passage 52c between the inner and outer circumferences of the torsion bar 6 and the input shaft 2 from the lower flow passage 52a of the input shaft 2. 2 communicating with the outlet port 36 from the upper flow path 52b of the input shaft 2 shown in FIG. The first recess 5
0 and the second recessed portion 51 in the circumferential direction are the narrowed portions A, B, C, D.
It is said that.

FIG. 4 shows a state in which steering is not performed, in which state the input shaft 2 and the valve member 31 are in the neutral position, the inlet port 34 and the outlet port 36 communicate with each other, and the pump 33
The oil supplied from the hydraulic control valve 30 to the tank 35 flows back to the tank 35, and no steering assist force is generated. When the torsion bar 6 is twisted by the steering resistance generated by steering to the left or right and the valve member 31 and the input shaft 2 relatively rotate in one direction, the relative position between the first recess 50 and the second recess 51 changes. Throttling section A between the inlet port 34 and the first port 37
Opening of the first port 37 and the outlet port 36
The opening of the throttle portion B between the inlet port 34 and
The opening degree of the throttle portion C between the second port 38 and the second port 38 is reduced, and the throttle portion D between the second port 38 and the outlet port 36 is reduced.
The opening degree of becomes large. As a result, pressure oil having a pressure corresponding to the magnitude and direction of the steering resistance is supplied to one oil chamber 22 of the hydraulic cylinder 20, and the oil flows back from the other oil chamber 23 to the tank 35, so that the left and right of the vehicle The steering assist force to one side acts on the rack 16 from the hydraulic cylinder 20. When steered to the other left or right, the valve member 31 and the input shaft 2 relatively rotate in the other direction contrary to the case where steered to the left or right, and the opening degree of the throttle portion C between the inlet port 34 and the second port 38 is increased. Getting bigger,
The opening degree of the throttle portion D between the second port 38 and the outlet port 36 becomes smaller, the opening degree of the throttle portion A between the inlet port 34 and the first port 37 becomes smaller, and the first port 37 and the outlet The opening degree of the narrowed portion B with the port 36 becomes large. As a result, a steering assist force to the other of the left and right of the vehicle acts on the rack 16 from the hydraulic cylinder 20.

As shown in FIGS. 1 to 3, a first spring (main elastic member) 61 and a second spring (auxiliary elastic member) 62 are attached to the upper end surface of the output shaft 3. The first spring 61
The second spring 62 and the second spring 62 are formed in a C shape in plan view by cutting a part of an annular leaf spring material, and the center thereof is arranged so as to coincide with the center of the output shaft 3. 61a and 62a are superposed so that the positions thereof are coincident with each other, and a portion opposite to each cutout portion 61a and 62a is fixed to the output shaft 3 by a fixing pin 63. Both notches 61
Pin-shaped first and second engaging members 65 and 64 having the same diameter are arranged between the opposed end surfaces of a and 62a. The first engaging member 65
Is fixed to a tubular member 66 so as to project downward in the drawing, and the tubular member 66 is concentrically fitted to the input shaft 2 so as to be relatively rotatable and fixed by a set screw 67. The second engaging member 64 is fixed to the output shaft 3 so as to project upward in the drawing. The centers of both engaging members 65, 64 are arranged on the same diameter of the output shaft 3. The opening width W1 of the cutout portion 61a of the first spring 61 is equal to the opening width W1 of the first and second engaging members 6.
The diameters of the first and second engaging members 65 and 64 are equal to the diameters of the first and second engaging members 65 and 64.
The first spring 61 contacts the input shaft 2 and the valve member 31.
Is applied to restore the neutral position to the neutral position, and in the present embodiment, a preset preload in a direction that prevents relative rotation of the input shaft 2 and the valve member 31 is applied. The notch portions 62a and 62a 'of the second spring 62 have an opening width W.
There are two stages of 2 and W1, and the cutout portion 62a 'is formed.
Has a width equal to the diameter of the first and second engaging members 65 and 64, so that the facing end surface of the cutout portion 62a 'abuts the outer surface of the second engaging member 64. Further, the width of the cutout portion 62a is made larger than the diameter dimension of the first and second engaging members 65, 64, whereby the facing end surface of the cutout portion 62a is preset from the outer surface of the first engaging member 65. The second spring 62 is separated by the fixed gap δ and the relative rotation amount of the input shaft 2 and the valve member 31 becomes a certain amount or more, and the notch portion 62a is formed.
When the opposite end surface of the contact member comes into contact with the outer surface of the first engaging member 65, an elastic force is applied in a direction that prevents relative rotation between the input shaft 2 and the valve member 31.

FIG. 5 shows the relationship between the relative rotation amount between the input shaft 2 and the valve member 31 and the input torque acting on the input shaft 2.
When the relative rotation amount is near zero, the elastic force of the torsion bar 6, the elastic force of the first spring 61, and the preload by the first spring 61 act in a direction to prevent the relative rotation of the input shaft 2 and the valve member 31. Trying to return both members 2, 31 to the neutral position,
The increase rate of the relative rotation amount with respect to the input torque becomes the minimum (almost zero). When the relative rotation amount is within the range of ± θa, the preload by the first spring 61 is released, and the elastic force of the torsion bar 6 and the elastic force of the first spring 61 cause the input shaft 2 and the valve member 3 to move.
1 acting to prevent relative rotation of the two members 2, 31
To increase the relative rotation amount with respect to the input torque, the increase rate becomes maximum. The relative rotation amount is ±
In the range exceeding θa, the elastic force of the torsion bar 6 and the elastic force of the first spring 61 act in a direction to prevent the relative rotation of the input shaft 2 and the valve member 31, and return both members 2, 31 to the neutral position. The second spring 62 and the cutout portion 6 of the second spring 62.
The opposing end surface of 2a abuts the outer surface of the first engaging member 65, and the elastic force of the second spring 62 acts in a direction to prevent relative rotation between the input shaft 2 and the valve member 31. The increase rate is between the maximum and minimum.

FIG. 6 shows the relationship between the input torque corresponding to the steering resistance acting on the input shaft 2 and the hydraulic pressure acting on the hydraulic cylinder 20. In a straight traveling state or a traveling state in which the steering angle is small, the amount of relative rotation between the input shaft 2 and the valve member 31 is small, and the preload in the direction that prevents the input shaft 2 and the valve member 31 from rotating relative to each other by the first spring 61. Since high pressure oil is not supplied to the hydraulic cylinder 20 even if the input torque becomes large and the steering assist force does not become large, the running stability can be improved. After the preload is released, the increase rate of the relative rotation amount of the input shaft 2 and the valve member 31 with respect to the input torque increases, so the increase rate of the hydraulic pressure acting on the hydraulic cylinder 20 with respect to the input torque increases, and the steering assist is increased. The force gradually increases, but when the amount of relative rotation becomes a certain amount or more, the second spring 62 causes the input shaft 2 and the valve member 3 to move.
Since the elastic force in the direction of blocking the relative rotation of 1 is applied, the rate of increase in the steering assist force does not suddenly increase. That is, the broken line in FIG. 5 shows the relationship between the input shaft 2 and the input torque when the second spring 62 is not provided,
In this case, as shown by the broken line in FIG. 6, the increase rate of the steering assist force rapidly increases when the input torque becomes equal to or higher than a certain value, whereas the increase rate of the steering assist force does not increase rapidly in the above embodiment. Since there is no steering wheel, the feeling of response when operating the steering wheel is not suddenly lost, and the steering feeling can be improved.

In the above embodiment, the input shaft 2 and the output shaft 3 are
The torsion bar 6 inserted in and is connected to the output shaft 3 via the serrations 5, the valve member 31 is connected to the output shaft 3 via the pins 32, and the throttle portions A, B, C at the neutral position,
After adjusting the relative rotational positions of the input shaft 2 and the valve member 31 so that the opening degree of D becomes uniform, the insertion hole for the pin 4 is formed in the torsion bar 6 and the input shaft 2, and the torsion bar 6 is formed by the pin 4. And the input shaft 2 are connected to each other, and then the tubular member 66 to which the first engaging member 65 is fixed is fixed to the input shaft 2 by the set screw 67. Thereby, the first engaging member 65
The relative rotational position of the tubular member 66 with respect to the input shaft 2 can be adjusted so that the center of the second engaging member 64 and the output shaft 3 have the same diameter. It is possible to prevent a discrepancy between the ring and the steering feeling when steering to the left.

FIG. 7 shows a modification, which is different from the above embodiment in that a friction reducing member 71 is interposed between the first spring 61 and the second spring 62, and the first spring 61 and the second spring 62 are different from each other. The first and second engaging members are arranged so that a component force in a direction that prevents the member 62 from bending in the axial direction acts on the first and second springs 61 and 62 from the first and second engaging members 65 and 64. The outer peripheral surfaces of the coupling members 65 and 64 are conical surfaces, and further, an elastic force that prevents the first and second springs 61 and 62 from axially bending between the tubular member 66 and the second spring 62. The disc spring 73 that acts on the above is interposed. As a result, it is possible to reduce the hysteresis that causes the hydraulic control characteristics of the hydraulic control valve 30 to be different depending on whether the steering angle is increased or decreased. A Teflon sheet or a thrust bearing can be used as the friction reducing member 71. Others are the same as the above-mentioned embodiment, and the same portions are denoted by the same reference numerals.

The present invention is not limited to the above embodiments and modifications. For example, although the main elastic member is composed of the torsion bar 6 and the first spring 61 in the above-described embodiment, it is formed into a C shape in plan view by only not forming the torsion bar or by cutting a part of the annular leaf spring material. The main elastic member may be composed of only the spring. Further, although the auxiliary elastic member is constituted by the single second spring 62 in the above-mentioned embodiment, it is formed in a C shape in plan view by cutting a part of the annular leaf spring material, and the opening width of the cut portion. May be composed of a plurality of springs different from each other. The elastic members may have the same or different spring constants, or may be linear characteristic springs or non-linear characteristic springs. Alternatively, the first spring and the second spring may be formed in a C shape in plan view by cutting out a part of a tubular spring material. In the above embodiment, the input shaft 2 is the first member and the valve member 31 is the second member, but the output shaft is the first member.
As a member, an oil passage between the output shaft and the valve member may be provided with a throttle portion whose opening degree is changed by the relative rotation of the output shaft and the valve member. Further, the present invention can be applied to a ball screw type hydraulic power steering device having the same hydraulic control valve as in the above embodiment.

[0021]

According to the hydraulic control valve of the present invention, it is possible to obtain a desired hydraulic control characteristic according to the relative rotation amount of the first member and the second member. It is possible to prevent a sudden change in the assisting force and improve the steering feeling.

[Brief description of drawings]

FIG. 1 is a plan sectional view of a hydraulic control valve according to an embodiment of the present invention (see FIG.
(II line cross section)

FIG. 2 is a sectional view of a hydraulic power steering device according to an embodiment of the present invention.

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

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

FIG. 5 is a diagram showing the relationship between the relative rotation amount of the input shaft of the hydraulic control valve and the valve member and the input torque of the embodiment of the present invention.

FIG. 6 is a diagram showing a relationship between an input torque and a hydraulic pressure for generating a steering assist force of the hydraulic power steering system according to the embodiment of the present invention.

FIG. 7 is a front view of a main part of (1) of a hydraulic control valve according to a modification of the present invention, and (2) is a sectional view taken along line (2)-(2) of (1).

[Explanation of symbols]

 2 input shaft (first member) 6 torsion bar (main elastic member) 31 valve member (second member) 61 first spring (main elastic member) 62 second spring (auxiliary elastic member) A, B, C, D throttle Department

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Noboru Minamoto 3-5-8 Minamisenba, Chuo-ku, Osaka City, Osaka Prefecture Koyo Seiko Co., Ltd.

Claims (1)

[Claims] 1. A first member, a second member that is rotatable relative to the first member, a main elastic member that applies an elastic force that returns both members to a neutral position, and an oil passage between both members. A valve that controls the hydraulic pressure by changing the opening of the throttle depending on the amount of relative rotation from the neutral position of both members, the elastic force in the direction that prevents relative rotation of both members. A hydraulic control valve, characterized in that an auxiliary elastic member is provided which acts when the relative rotation amount of both members exceeds a certain level.