JPH08104246A - Power steering device - Google Patents

Abstract

PURPOSE: To provide a constitution so as to prevent an abnormal sound due to cavitation by forming a clearance between an input side land part and an output side land part so that an outlet is formed narrower than an inlet. CONSTITUTION: A power steering device comprises a control valve, hydraulic cylinder 12, oil hydraulic pump 13 and a reservoir 14. The control valve has a rotary type servo valve part, in which a rotary valve member 31 and a sleeve valve member 33 are connected through a twistably deformable torsion bar. A plurality of land and groove parts are alternately formed respectively in the external periphery of the rotary valve member 31 and the internal periphery of the sleeve valve member 33. Throttling between angular parts of each land is formed by chamfers 53, 54 so as to form an out let narrower than an inlet with an operating oil flowing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power steering apparatus, and more particularly to a power steering apparatus which assists a steering force applied to steered wheels in response to a steering operation by a driver.

[0002]

2. Description of the Related Art Conventionally, in order to improve the steering feeling of a vehicle, various developments of a power steering device (also called a power steering device) have been made. here,
A conventional power steering apparatus has a hydraulic pump driven by an engine of a vehicle as a hydraulic pressure generation source, and uses the hydraulic pressure to assist the steering force when the steering wheel is steered.

And, in the above power steering apparatus,
A control valve for controlling the steering force on the steered wheels according to the steering operation of the driver, and a steering force assisting mechanism for assisting the steering force by the hydraulic pressure supplied from the control valve are provided. This control valve is formed by connecting an input shaft that rotates integrally with the steering shaft of the steering wheel and an output shaft that transmits the driving force to the steered wheels via a torsion bar.

The steering wheel is steered and the torsion bar is twisted to cause relative displacement between the input shaft and the output shaft. In that case, the twisting direction of the torsion bar switches the throttle formed in the oil passage formed between the input shaft and the output shaft, and the hydraulic pressure to the steering force assisting mechanism moves the steering wheel to the left or right. Is supplied so as to urge. As a conventional power steering apparatus, for example, there is an apparatus as disclosed in Japanese Patent Laid-Open No. 3-14769. In the power steering apparatus of this publication, as shown in FIG. 10, a land portion 1a and a groove portion 1b are alternately formed on an output side sleeve valve member 1, and an input side rotor valve facing the sleeve valve member 1 is provided. Lands 2a and grooves 2b are alternately formed on the member 2.

The twisting of the torsion bar forms a throttle 8 having a narrowed space between the corner of the land 1a of the sleeve valve member 1 and the corner of the land 2a of the rotor valve member 2. 8 limits the flow direction of the hydraulic oil. At the same time, the hydraulic oil supplied from the hydraulic pump 3 flows through the wider gap between the land portion 1a and the land portion 2a and is supplied to one chamber of the drive cylinder 4. Therefore, the steered wheels are steered in the steering direction by being assisted by the driving force of the driving cylinder 4. The hydraulic oil discharged from the other chamber of the drive cylinder 4 is collected in the reservoir tank 7.

[0006]

However, in the power steering apparatus of the above publication, the chamfered portion 5 for smoothing the pressure change with respect to the steering angle is provided at the corner portion of each land portion 2a of the rotor valve member 2. Therefore, as shown in an enlarged scale in FIG. 11, the hydraulic oil flows through the gap S of the throttle 8 formed between the chamfered portion 5 and the land portion 1a of the sleeve valve member 1 into the reservoir tank. become.

However, in the above-mentioned gap S when the throttle acts, the inlet Sa into which the hydraulic oil flows in is narrow and the outlet Sb into which the hydraulic oil flows out is wide. Therefore, the hydraulic oil is significantly decelerated in the process of passing through the gap S, so that a negative pressure region 6 (shown by a broken line in FIG. 11) is generated near the inlet. Therefore, the conventional power steering apparatus described above has a problem that when the hydraulic oil passes through the gap S, cavitation occurs in the negative pressure region 6, which causes abnormal noise.

In view of the above problems, the invention according to the present application, when the pressure oil supplied from the hydraulic pressure source flows to the reservoir tank through the narrowed portion between the land portion on the input side and the land portion on the output side, In addition, it is an object of the present invention to prevent the generation of abnormal noise due to cavitation by gradually reducing the flow passage area of the narrowed portion.

[0009]

According to a first aspect of the present invention, the steering direction is determined according to the relative operating angle between the power assisting mechanism and the input shaft connected to the steering wheel and the output shaft connected to the steering mechanism. In a power steering apparatus having a control valve for controlling the assisting force to the input shaft, the control valve is connected to an input shaft, and an input member in which grooves and lands are alternately formed on the outer periphery is connected to the output shaft. It has an output member in which grooves and lands are alternately formed so as to face the input member, and chamfers at the corners of the lands located on both sides of the groove in which the supply passage communicating with the hydraulic pressure source is opened. And chamfered portions are provided at the corners on both sides of the land portion that is arranged to face the groove portion in which the discharge passage communicating with the reservoir tank is opened.

According to a second aspect of the invention, the assisting force in the steering direction is controlled according to the relative operating angle of the power assisting mechanism and the input shaft connected to the steering wheel and the output shaft connected to the steering mechanism. In the power steering apparatus having a control valve for operating the control valve, the control valve is connected to the input shaft and has an input member having grooves and lands alternately formed on the outer periphery, and the control valve is connected to the output shaft so as to face the input member. Has a groove portion and an output member in which land portions are alternately formed, and chamfered portions are provided at corners of the land portion located on both sides of the groove portion where a supply passage communicating with a hydraulic pressure source is opened. A right-angled portion is provided at each of the corner portions on both sides of the groove portion and the land portion opposed to each other in which the discharge passage communicating with the above is opened.

According to the third aspect of the present invention, the assisting force in the steering direction is controlled according to the relative operating angle between the power assisting mechanism and the input shaft connected to the steering wheel and the output shaft connected to the steering mechanism. In the power steering apparatus having a control valve for operating the control valve, the control valve is connected to the input shaft and has an input member having grooves and lands alternately formed on the outer periphery, and the control valve is connected to the output shaft so as to face the input member. Has a groove portion and an output member in which land portions are alternately formed, and chamfered portions are provided at corners of the land portion located on both sides of the groove portion where a supply passage communicating with a hydraulic pressure source is opened. Is characterized in that a stepped portion is provided at a corner portion of the land portion located on both sides of the groove portion in which a discharge passage communicating with the.

[0012]

According to the present invention, when the pressure oil supplied from the hydraulic pressure source flows to the reservoir tank through the throttle portion (chamfered portion), the flow passage area of the throttle portion is always the inlet. Since it becomes gradually narrower, negative pressure is not generated inside the throttle portion, and it is possible to prevent generation of abnormal noise due to generation of cavitation.

Further, according to the second aspect of the present invention, the flow passage area is gradually reduced in one throttle portion, while the right-angled portions are close to each other in the other throttle portion. Therefore, almost the entire amount except for the flow rate to the cylinder flows in the flow passage with the flow passage area gradually narrowed, and the generation of cavitation and the generation of abnormal noise due to the generation of negative pressure are prevented. Further, in the other throttle portion, there is no change in the flow passage area, and therefore, there is no change in the flow velocity in the process of the hydraulic oil passing through the throttle portion, and the generation of negative pressure is prevented.
According to the invention described in claim 3, by adopting the configuration in which the step portion is provided at the corner portion of the land portion located on both sides of the groove portion where the discharge passage communicating with the reservoir tank is opened, the oil can escape even in the step portion. Therefore, the load on the chamfered portion caused by excessive concentration of the flow on the chamfered portion where the flow path becomes narrower is reduced, and the generation of abnormal noise due to cavitation can be more effectively prevented.

[0014]

1 to 5 show an embodiment of a power steering apparatus according to the invention of the present application. In each figure, the power steering system generally includes a control valve 11, a hydraulic cylinder 12 functioning as a steering force assisting mechanism, a hydraulic pump 13 as a hydraulic power source, and a reservoir tank 14 for collecting hydraulic oil. Become.

The control valve 11 has a gear housing 20 and a valve housing 21 integrally fixed to each other. The output shaft 22 is rotatably supported by bearings 23 a and 23 b provided in the gear housing 20 and the valve housing 21. Further, the pinion 22 a of the output shaft 22 meshes with the rack 24 a of the rack shaft 24 that is supported so as to reciprocate in the direction intersecting with the output shaft 22.

The rack shaft 24 has a piston 25 of the hydraulic cylinder 12 and is connected to the steered wheels via a link mechanism (not shown). An input shaft 27 rotatably supported by bearings 26a and 26b is inserted into the gear housing 20 and the valve housing 21. The input shaft 27 is coaxially supported with the output shaft 22 and has one end connected to a steering wheel (both not shown) via a steering shaft.

The output shaft 22 and the input shaft 27 are the torsion bar 2 inserted in the hollow portion 27a of the input shaft 27.
It is connected via 8 so as to be relatively rotatable. Therefore, the output shaft 22 and the input shaft 27 are connected to the torsion bar 28.
Relative rotation according to the twist angle of. The output shaft 22
Between the rotary shaft 3 and the input shaft 27.
0 (hereinafter referred to as “valve portion 30”) is provided. The valve portion 30 is rotatably fitted to a rotary valve member (input member) 31 provided on the input shaft 27, an outer peripheral surface of the rotary valve member 31 and an inner periphery 21 a of the valve housing 21, and has a coupling pin 32. And a sleeve valve member (output member) 33 connected to the output shaft 22.

The valve section 30 has a supply port 34, a discharge port 35, and a pair of supply / discharge ports 36, 37.
It constitutes a 4-port throttle switching valve. The supply port 34 is connected to the hydraulic pump 13 via a supply pipeline 46a, the hydraulic pump 13 is connected to the reservoir tank 14 via a suction pipeline 46b, and the discharge port 35 is connected to a discharge pipeline 47.
It is connected to the reservoir tank 14 via.

As shown in FIG. 4, on the inner circumference of the sleeve valve member 33, eight land portions 38 _{1 to} 38 ₈ and a groove portion 39 _{1 are provided.}
~ 39 ₈ and are formed alternately. As shown in FIG. 5, eight land portions 4 are provided on the outer periphery of the rotary valve member 31.
0 ₁ to 40 ₈ and groove portions 41 _{1 to} 41 ₈ are formed alternately. Therefore, the land portion 38 ₁ of the sleeve valve member 33 is
To 38 ₈ and the grooves 39 ₁ to 39 _8, the rotary valve member 3
The first groove portions 41 _{1 to} 41 ₈ and the land portions 40 ₁ to 40 ₈ are provided so as to face each other, and the land portions 38 _{1 to} 38
It is formed so that it can pass through a slight gap between the end portion of _{8 and} the end portions of the land portions 40 ₁ to 40 ₈ .

Land portion 38 of the sleeve valve member 33₁~ 3
8₈Every other land part 38 ₁, 38₃, 3
8_Five, 38₇A supply passage 42 is opened in the. each
The supply passage 42 is provided with hydraulic oil pumped from the hydraulic pump 13.
Is communicated with a supply port 34 to which is supplied. In addition,
Groove 41 of rotary valve member 31₁~ 41₈Every other
Groove 41₂, 41_Four, 41₆, 41₈In the discharge passage
43 is opened. The discharge passage 43 is formed by the input shaft 2
7 to the passage 44 formed between the torsion bar 28
And the passage 44 is formed in the input shaft 27.
Is connected to the discharge port 35 through the discharge hole 45.
You.

Each groove portion 39 _{1 to} 39 of the sleeve valve member 33
_One of the distribution holes 48, 49 (shown by broken lines in FIG. 4) is alternately opened in 8, and the distribution holes 48, 49 communicate with the supply / discharge ports 36, 37 described above. Further, the supply / discharge ports 36, 37 are connected to the hydraulic cylinder 1 via the conduits 51, 52.
2 are connected to the left and right cylinder chambers 12a and 12b.

Land portion 38 ₁ of the sleeve valve member 33
To 38 _8, as shown enlarged in FIG. 4, the hydraulic pump 1
The land portions 38 ₂ , 3 of the sleeve valve member 33 in which the supply passage 42 for supplying the discharge pressure discharged from 3 is not opened.
The chamfered portions 53 are provided at both side corners of 8 ₄ , 38 ₆ and 38 ₈ . In addition, the land portion 4 of the rotary valve member 31
0 ₁ to 40 ₈ are, as shown in an enlarged view in FIG.
The chamfered portions 54 are provided only at the corner portions of the land portions located on both sides of the groove portions 41 ₁ , 41 ₃ , 41 ₅ , 41 ₇ in which 3 is not opened.

Therefore, in this embodiment, the land portion 40₁~
40₈Or land part 38₁~ 38₈Chamfer on all corners of
Discharge from the hydraulic pump 13 instead of forming
Groove portion 4 in which a supply passage 42 through which hydraulic oil is supplied is opened
1₁, 41₃, 41_Five, 41 ₇Lands located on both sides of
The chamfered part 54 communicates with the reservoir tank at the corner of the part
Groove portion 41 in which the discharge passage 43 is opened₂, 41_FourFour
1₆, 41₈Land portion 38 arranged to face₂Three
8_Four, 38₆, 38₈Chamfers 53 are provided at the corners on both sides of the
It becomes

When a steering torque is applied to the input shaft 27 by operating the steering wheel, the torsion bar 28 is twisted and the rotary valve member 31 is displaced in the A direction in FIG. In FIG. 3, one supply passage 42 and its surroundings have been described in an enlarged manner, but the other supply passages and their surroundings have the same structure, and are therefore omitted in the drawing. as a result,
The corner portion of the land portion 38 ₁ of the sleeve valve member 33 and the chamfered portion 54 of the corner portion of the land portion 40 ₈ of the rotary valve member 31 are close to each other to form the first throttle 55. At the same time, the chamfered portion 5 at the corner of the land portion 38 ₂ of the sleeve valve member 33.
3 and the corner portion of the land portion 40 ₁ of the rotary valve member 31 are close to each other to form the second throttle 56.

As shown in the enlarged view of FIG. 6A, the working oil flows in the first throttle 55 as indicated by the arrow. First
In the diaphragm 55, the chamfered portion 54 of the land portion 40 ₈
And the gap S formed between the corner of the land portion 38 ₁ is
The opening area of the inlet Sa is larger than that of the outlet Sb. Therefore, the hydraulic fluid passing through the first throttle 55 is
The flow gradually flows from the wide inlet Sa toward the narrow outlet Sb, and is not decelerated in the process of flowing from the inlet Sa to the outlet Sb. Therefore, a negative pressure region does not occur inside the first aperture 55, cavitation is prevented from occurring, and abnormal noise due to this is also prevented from occurring.

As shown in the enlarged view of FIG. 6B, the working oil flows in the second throttle 56 as indicated by the arrow. Second
The chamfered portion 53 of the land portion 38 ₂ also in the diaphragm 56 of
And the gap S formed between the corner of the land 40 ₁ and
The opening area of the inlet Sa is larger than that of the outlet Sb. Therefore, the hydraulic oil passing through the second throttle 56 flows from the wide inlet Sa toward the outlet Sb having a gradually narrowed passage area as in the case of the first throttle 55, and from the inlet Sa. There is no deceleration in the process of flowing to the outlet Sb. Therefore, a negative pressure region is not generated inside the second diaphragm 56, cavitation is prevented from occurring, and abnormal noise due to this is also prevented from occurring.

As described above, the torsion bar 28 is twisted in the oil passage formed between the outer circumference of the rotary valve member 31 and the inner circumference of the sleeve valve member 33.
And the second throttle 56 are formed, the flow of the working oil discharged from the supply passage 42 to the oil passage is restricted by the throttles 55 and 56, so that the distribution hole 48 opening to the groove 39 ₁ is opened. After passing through, the right cylinder chamber 12b of the hydraulic cylinder 12
To assist the steering force.

When the torsion bar 28 is twisted in the opposite direction to the above, the distribution hole 49 opening to the groove 39 ₈ is formed.
And is supplied to the left cylinder chamber 12a of the hydraulic cylinder 12. FIG. 7 shows the structure of a modification of the valve portion 30 of the above embodiment. The rotary valve member 31 and the sleeve valve member 33 of the valve unit 30 shown in FIG. 7 have basically the same structure as that shown in FIGS. 1 to 6, but a hydraulic oil supply passage 42 and a discharge passage 43 are provided. The positions of the distribution holes 48 and 49 and the chamfered positions of the corners of the lands are changed.
Therefore, in the figure, the reference numerals indicating the respective components are the same as those in FIG.
The same symbols as those shown in are used.

In the figure, the groove portion 39 of the sleeve valve member 33 is shown.₁
~ 39₈Every other groove 39 ₁, 39₃, 3
9_Five, 39₇A supply passage 42 is opened at the bottom of the
You. In addition, the land portion 40 of the rotary valve member 31₁~ 40
₈Every other land part 40 ₂, 40_Four, 40₆,
40₈A discharge passage 43 is opened at. And
Each land portion 38 of the sleeve valve member 33₁~ 38₈Has
One of the distribution holes 48 and 49 is opened alternately.

Grooves 39 _{1 to} 3 of the sleeve valve member 33
Grooves 39 ₁ and 3 of 9 ₈ in which the supply passage 42 opens
9 _3, 39 _5, 39 ₇ corners of each land portion located on both sides of the chamfered portion 53 is provided. Further, among the land portions 40 ₁ to 40 ₈ of the rotary valve member 31, the land portions 40 ₂ , 40 ₄ , 40 ₆ , 40 which the discharge passage 43 communicates with.
Chamfers 54 are provided at the corners on both sides of ₈ .

Here, when the torsion bar 28 is twisted by the operation of the steering wheel described above, the torsion bar 28 is elastically deformed, so that the rotary valve member 31 is displaced in the A direction. As a result, the corner portion of the land portion 38 ₁ of the sleeve valve member 33 and the chamfered portion 54 formed at the corner portion of the land portion 40 ₈ of the rotary valve member 31 are close to each other to form the first throttle 55. At the same time, the land portion 40 of the rotary valve member 31
_The chamfered portion 54 provided at the corner of the land valve 38 ₂ of the sleeve valve member 33 comes close to the corner of 1 and the second throttle 56.
To form.

As shown in FIGS. 6A and 6B described above,
In the first throttle 55 and the second throttle 56, the hydraulic oil flows from the wide inlet Sa toward the narrow outlet Sb, and is not decelerated in the process of flowing from the inlet Sa to the outlet Sb. Therefore, the first diaphragm 55 and the second diaphragm 5
No negative pressure region is generated inside 6, cavitation is prevented from occurring, and abnormal noise due to this is also prevented.

In FIG. 7, the periphery of one supply passage 42 has been described in an enlarged manner, but since the periphery of the other supply passages has the same structure, it is omitted in the drawing. FIG. 8 shows the structure of each valve member of the control valve of another embodiment of the power steering apparatus according to the invention of the present application. The valve portion according to the present embodiment also has a structure basically similar to that shown in FIG. 3, but the positions of the chamfered portions formed at the corners of each land portion are changed. Therefore, also in FIG. 8, the same reference numerals as those in FIG.

In the figure, the land portion 3 of the sleeve valve member 33 is shown.
Every other land portion 38 ₁ and 3 of 8 _{1 to} 38 ₈
A supply passage 42 is formed in each of 8 ₃ , 38 ₅ and 38 ₇ . Further, the grooves 39 ₁ to 39 ₈ of the sleeve valve member 33
One of the distribution holes 48 and 49 is opened alternately. Then, the groove portions 41 _{1 to} 41 ₈ of the rotary valve member 31.
Every other groove portion 41 ₂ , 41 ₄ , 41 ₆ , 41 ₈
A discharge passage 43 is opened at the bottom of the.

Groove portion 41 of the rotary valve member 31₁~ 4
1₈Of the groove portion 41 in which the supply passage 42 opens₁, 4
1₃, 41_Five, 41₇Corner of each land located on both sides of
The part is provided with a chamfered part 54. Therefore,
In this embodiment, the supply passage 42 communicating with the oil pressure generation source 13
Only the corners of the land located on both sides of the groove where the
A chamfered portion 54 is provided on the discharge port for communicating with the reservoir tank.
Groove 41 in which passage 43 is opened₂, 41_Four, 41₆Four
1 ₈And the land portion 38 arranged to face them₂, 38
_Four, 38₆, 38₈The corners on both sides of the
You. Here, the operation of the steering wheel described above
When the torsion bar 28 is twisted, it is elastically deformed.
Therefore, the rotary valve member 31 is displaced in the A direction.

As a result, the corner portion of the land portion 38 ₁ of the sleeve valve member 33 and the land portion 40 ₈ of the rotary valve member 31.
The chamfered portions 54 formed at the corners of the above are close to each other to form the first diaphragm 55. At the same time, the corner right angle portion 57 of the land portion 40 ₁ of the rotary valve member 31 and the corner right angle portion 57 of the land portion 38 ₂ of the sleeve valve member 33 are close to each other to form the second throttle 56. .

As a result, the throttle portion 55 of the groove portion 41 ₁ communicating with the hydraulic pressure source 13 gradually narrows the flow passage area, while
The throttle portion 56 of the groove portion 41 ₂ communicating with the reservoir tank 14.
Becomes a right angle and the flow is restricted. Therefore, according to the present embodiment, the flow rate from the hydraulic pressure generation source 13 is
Almost the entire amount except for the flow rate to 2 is narrowed and passes through the chamfered portion, there is no spreading flow, and abnormal noise due to cavitation can be prevented.

Further, according to the present embodiment, the chamfered portion provided on the land portion is provided only on the rotor valve member side and not on the sleeve valve member, so that each valve member can be easily manufactured.
Further, when forming the chamfered portion on the sleeve valve member side, it is difficult to make the chamfering start point with high precision. According to the present embodiment, the chamfering is performed only on the rotor valve member side, so the precision is improved. The control valve can have uniform characteristics.

FIG. 9 shows another embodiment according to the invention of the present application.
In the embodiment shown in FIG.
Discharge passage communicating with the reservoir tank 14 of the valve member 31
Groove portion 41 in which 43 is opened₂, 41_Four, 41₆, 41₈
Provided with stepped portions 58 at the corners of the lands located on both sides of the
Things. Therefore, in the valve portion of this embodiment, the oil
A groove portion in which a supply passage 42 communicating with the pressure generation source 13 is opened
41₁, 41₃, 41 _Five, 41₇Runs located on both sides of
The chamfered portion 54 is provided at the corner of the reservoir portion,
The discharge passage 43 communicating with the
A stepped portion 58 is provided at the corner of the land portion.
You.

In this embodiment, it is assumed that the rotary valve member 31 is displaced in the A direction by operating the steering wheel. As a result, the land portion 38 of the sleeve valve member 33 is
The corner portion ₁ and the chamfered portion 54 provided on the land portion 40 ₈ of the rotary valve member 31 are close to each other to form the first throttle 55. At the same time, the land portion 38 ₂ of the sleeve valve member 33 is
And the stepped portion 58 of the land portion 40 ₁ of the rotary valve member 31 are close to each other to form the second throttle 56.

Here, in the first diaphragm 55, a flow passage having a gradually narrowing flow passage area is formed to prevent the occurrence of cavitation as in the above-described embodiment, thereby preventing the generation of abnormal noise. It Further, in the second throttle 56, since the stepped portion 58 is provided at the corner of the land portion 40 ₁ of the rotary valve member 31, a gap S ′ through which the hydraulic oil flows is formed.

In the embodiment of FIG. 8, the hydraulic oil is almost blocked at the throttle 56, so that the flow may be excessively concentrated on the throttle 55 having a narrowed flow passage area, which is a hydraulic pressure generation source. In the case of a system in which the discharge amount of the pump 13 is large, cavitation may occur even though the flow path area is narrowed. In the present embodiment, by letting a predetermined amount of hydraulic oil escape in the throttle 56, the load on the throttle 55 is reduced, and cavitation can be prevented.

In the embodiment of FIGS. 8 and 9, the supply passage 42 communicating with the pressure generating source 13 has the sleeve valve member 33.
Land portions 38 _1, 38 _3, 38 _5, 38 but but on the _7, as in the embodiment of FIG. 7, the groove 39 ₁ of the sleeve valve member 33 the opening of the supply passage 42, 39 _3, Three
It is also possible to provide in 9 ₅ and 39 ₇ . Further, although the rotary type control valve has been described as an example in the above-described embodiment, the present invention is not limited to this, and the present invention can be applied to a spool type control valve for sliding a spool.

[0044]

According to the first aspect of the present invention, when the pressure oil supplied from the hydraulic pressure source flows into the reservoir tank through the throttle of the control valve, the area of the flow passage of the throttle is always wide. Since it becomes gradually narrower, negative pressure is not generated inside the throttle portion, and it is possible to prevent abnormal noise due to cavitation.

According to the second aspect of the present invention, the flow passages of the groove portion and the narrowed portion of the land portion connected to the hydraulic pressure generation source of the control valve are gradually narrowed, and similar to the first aspect, abnormal noise due to the occurrence of cavitation is generated. Can be prevented. Further, since the groove portion communicating with the reservoir and the narrowed portion of the land portion are formed at right angles, it is possible to prevent generation of cavitation and abnormal noise due to the generation of negative pressure. It is not necessary to apply the above, and the manufacturing becomes easy. Further, the steering angle-hydraulic pressure (θ-P) characteristic, which is the characteristic of the control valve, is adjusted by the chamfer,
In this case, the adjustment can be performed only by adjusting the chamfered portion of the input member, and the manufacturing cost can be reduced.

According to the third aspect of the invention, the chamfered portions are provided at the corners of the lands located on both sides of the groove where the supply passage communicating with the hydraulic pressure source is opened, and the discharge passage communicating with the reservoir tank is provided. By providing the stepped portions at the corners of the lands located on both sides of the opened groove portion, the hydraulic oil can be released at the stepped portion in one throttle portion, and as a result, the other flow passage gradually narrows. Since the load on the diaphragm portion is reduced as compared with the case of claim 2, it is possible to prevent the generation of abnormal noise due to the generation of cavitation. Further, in manufacturing the valve member, it is not necessary to provide the output member with the chamfered portion and the stepped portion, and the manufacturing is facilitated.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a main part of an embodiment of a power steering apparatus according to the present invention.

FIG. 2 is a vertical cross-sectional view showing a configuration of a control valve of the power steering apparatus.

FIG. 3 is an enlarged vertical cross-sectional view showing a part of an oil passage and a throttle formed between a sleeve valve member and a rotary valve member.

FIG. 4 is an enlarged vertical sectional view showing a sleeve valve member.

FIG. 5 is an enlarged vertical sectional view of a rotary valve member.

FIG. 6 is an enlarged vertical sectional view showing a first diaphragm and a second diaphragm.

FIG. 7 is a longitudinal sectional view showing a part of a modified example of the present invention in an enlarged manner.

FIG. 8 is an enlarged vertical cross-sectional view showing a part of a valve member according to another embodiment of the present invention.

FIG. 9 is an enlarged vertical sectional view showing a part of a valve member of another embodiment of the present invention.

FIG. 10 is a vertical sectional view for explaining a conventional configuration.

FIG. 11 is a vertical cross-sectional view for explaining a conventional diaphragm shape.

[Explanation of symbols]

11 control valve 12 hydraulic cylinder 13 hydraulic pump 14 reservoir tank 22 the output shaft 24 the rack shaft 25 piston 27 the input shaft 28 a torsion bar 30 rotary type servo valve 31 rotary valve member 33 sleeve valve member 38 _{1-38 8} land portions 39 ₁ ~ 39 ₈ Grooves 40 ₁ to 40 ₈ Lands 41 _{1 to} 41 ₈ Grooves 42 Supply Passages 43 Discharge Passages 46a Supply Pipelines 46b Suction Pipelines 47 Discharge Pipelines 53, 54 Chamfers 57 Right Angles 58 Steps

Claims (3)

[Claims] 1. A power assisting mechanism and a control valve for controlling the assisting force in the steering direction according to the relative operating angle between an input shaft connected to the steering wheel and an output shaft connected to the steering mechanism. In the power steering apparatus having, the control valve has an input member connected to an input shaft and having grooves and lands alternately formed on an outer periphery thereof, and a groove and a land part connected to the output shaft so as to face the input member. And an output member formed alternately, and chamfered portions are provided at corners of lands located on both sides of the groove portion where a supply passage communicating with a hydraulic pressure source is opened, and a discharge passage communicating with a reservoir tank. A power steering apparatus, wherein chamfered portions are provided at corners on both sides of a land portion that is arranged to face the groove portion that is opened. 2. A power assisting mechanism and a control valve for controlling the assisting force in the steering direction according to the relative operating angle between the input shaft connected to the steering wheel and the output shaft connected to the steering mechanism. In the power steering apparatus having, the control valve has an input member connected to an input shaft and having grooves and lands alternately formed on an outer periphery thereof, and a groove and a land part connected to the output shaft so as to face the input member. And an output member formed alternately, and chamfered portions are provided at corners of lands located on both sides of the groove portion where a supply passage communicating with a hydraulic pressure source is opened, and a discharge passage communicating with a reservoir tank. A power steering device, wherein right-angled portions are provided at corners on both sides of the groove portion having an opening and a land portion arranged to face each other. 3. A power assisting mechanism and a control valve for controlling the assisting force in the steering direction according to the relative operating angle between the input shaft connected to the steering wheel and the output shaft connected to the steering mechanism. In the power steering apparatus having, the control valve has an input member connected to an input shaft and having grooves and lands alternately formed on an outer periphery thereof, and a groove and a land part connected to the output shaft so as to face the input member. And an output member formed alternately, and chamfered portions are provided at corners of lands located on both sides of the groove portion where a supply passage communicating with a hydraulic pressure source is opened, and a discharge passage communicating with a reservoir tank. A power steering apparatus, wherein stepped portions are provided at corners of a land portion located on both sides of the groove portion having an opening.