JP2000085599A - Hydraulic control valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively depress cavitation generated in flowing a hydraulic fluid to throttle parts aligned on the fitting peripheries between a valve body and a valve spool without being influenced by a machining error and to reduce flow noise in a rotary hydraulic control valve. SOLUTION: Oil grooves 4, 4... in a valve body 1 side and oil grooves 5, 5... of a valve spool 2 side are placed in a zigzag shape. Offset placement is made to the oil grooves 4, 4... of the valve body 1 side so that throttle parts 6a providing outward flow to the oil grooves 4 from the oil grooves 5 the throttle parts formed among oil grooves have throttle surfaces larger than throttle parts 6b providing inward flow to the oil grooves 5 from the oil grooves 4. Chamfers 7a, 7b are provided to the corner edges of the oil grooves 5 of the valve spool 2 side facing the throttle parts 6a, 6b, respectively. A tilt angle to the peripheral surface of the valve spool 2 in the chamfers 7a is larger than that in the chamfers 7b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary hydraulic control valve which performs a hydraulic control operation by using a relative angular displacement between a valve body and a valve spool fitted coaxially, and more particularly to a hydraulic hydraulic control valve. In a power steering apparatus, the present invention relates to a hydraulic control valve used to control a hydraulic pressure supplied to a power cylinder for assisting steering according to a steering operation.

[0002]

2. Description of the Related Art Hydraulic type which assists steering by a hydraulic pressure generated by a double-acting hydraulic cylinder (power cylinder) disposed in a steering mechanism and reduces a labor burden required for operating a steering wheel (steering wheel). The power steering device controls the supply and discharge of hydraulic pressure between a power pump and an oil tank storing hydraulic oil driven by an engine and the power cylinder according to the direction and magnitude of steering torque applied to the steering wheel. A hydraulic control valve is provided, and the operation of the hydraulic control valve supplies pressure oil generated by the hydraulic pump to a cylinder chamber on a corresponding side of the power cylinder.

As the hydraulic control valve, a rotary hydraulic control valve that directly uses the rotation of a steering wheel is used.
This is because an input shaft connected to a steering wheel and an output shaft connected to a steering mechanism are coaxially connected via a torsion bar, and the other connection is provided inside a cylindrical valve body engaged with one connection end. The valve spool integrally formed at the end is fitted so as to be rotatable relative to each other on the same axis, and when a steering torque is applied to the steering wheel, the torsion bar twists between the valve body and the valve spool. It is configured to generate relative angular displacement.

A plurality of oil grooves extending in the axial direction are arranged on the circumference of the fitting between the valve body and the valve spool (the inner circumference of the former and the outer circumference of the latter) so as to be substantially equally arranged in the circumferential direction. The valve body and the valve spool are positioned so that their respective oil grooves are staggered in the circumferential direction, and adjacent ones communicate with each other. Of the oil grooves on the valve body side or valve spool side, every other half is connected to the discharge side of the hydraulic pump as a hydraulic source to form an oil supply chamber, and the other half is oil drainage. The oil tank communicates with the oil tank and forms an oil discharge chamber. Furthermore, the oil groove on the valve spool side or valve body side is
The oil supply chamber is formed by alternately communicating with both cylinder chambers of the power cylinder that is the oil supply destination.

FIG. 5 is a diagram for explaining the operation of a conventional hydraulic control valve. This figure shows a valve body 1 and a valve spool 2
Of the valve body 1
The oil grooves 4, 4...
Both cylinder chambers S _R of the power cylinder (not shown) via a respective separate oil feeding holes are alternately connected to S _L, The oil grooves 5, 5 ... are arranged on the outer periphery of the valve spool 2, the separate guide Oil supply chamber 10 connected to the discharge side of hydraulic pump P through an oil hole
And an oil drain chamber 11 connected to the oil tank T through each of the oil drain holes alternately. In addition, the configuration opposite to the figure,
That is, the oil grooves 5, 5,...
13 and the oil grooves 4, 4...
A configuration in which the oil drain chamber 11 is used is also possible.

The oil grooves 4, 4... On the valve body 1 and the oil grooves 5, 5,... On the valve spool 2 communicate with equal sides on both sides. Are used to change the aperture area in accordance with the relative angular displacement.
The oil transfer chamber is actuated by the change in the throttle area.
Cylinder chamber S _R through 12 and 13, the hydraulic pressure is controlled to be fed to the S _L.

FIG. 5A shows a state where no relative angular displacement occurs between the valve body 1 and the valve spool 2. At this time, the pressure oil supplied from the hydraulic pump P to the oil supply chamber 10 is supplied to the narrowed portions 6 having equal areas on both sides of the oil supply chamber 10.
6, the oil is equally distributed and flows into the adjacent oil supply chambers 12 and 13, and flows into the oil discharge chambers 11 and 11 through the same-area narrowed portions 6 and 6 on the other side of the oil supply chambers 12 and 13. led, will follow a path that flows back to the oil tank T continuing to, oil pressure supplied to the oil supply chamber 10, the cylinder chamber S _R, not to both feed of S _L, the power cylinder of any No force is generated.

FIG. 5B shows a state in which a steering torque is applied to the steering wheel, and a relative angular displacement occurs between the valve body 1 and the valve spool 2. At this time, refueling chamber 10
As a result, the throttle area of one (oil supply chamber 12 side) of the throttle sections 6 and 6 on both sides of the oil tank increases, and the throttle area of the other (oil supply chamber 13 side) decreases. The pressurized oil is mainly introduced into the oil feed chamber 12 through the throttle section 6 having an increased throttle area, and the oil pressure is supplied between the oil feed chamber 12 and the other oil feed chamber 13 and the cylinder chambers connected to the respective oil feed chambers. A pressure difference is generated between S _R and S _L , and the power cylinder generates a hydraulic pressure (steering assist force) corresponding to the pressure difference.

The pressure difference generated at this time is the other (the oil supply chamber 13).
Side), which depends on the degree of reduction of the throttle area in the throttle section 6, and this degree of reduction corresponds to the magnitude of the relative angular displacement, that is, the magnitude of the steering torque applied to the steering wheel. Therefore, the power generated by the power cylinder has a direction and a magnitude corresponding to the steering torque applied to the steering wheel, and the steering can be assisted. At this time, the other cylinder chamber S _L interior of the oil pushed out by the operation of the power cylinder is refluxed to the other oil transfer chamber 13, the diaphragm portion 6 with an increased throttle area at one side of said transmission oil chamber 13 Through the oil discharge chamber 11
To the oil tank T connected to

The desirable increase characteristic of the steering assist force in the power steering apparatus is not a characteristic that increases in proportion to the steering torque applied to the steering wheel, but gradually increases in a range where the steering torque is small, and a predetermined limit is set. It is a characteristic that increases rapidly with exceeding. In order to obtain such characteristics, the corner of the oil groove 5 on the valve spool 2 side facing each of the throttle portions 6 has a predetermined inclination angle with respect to the peripheral surface of the valve spool 2 and A chamfered portion (chamfer 7) having a predetermined width is formed so that the change in the throttle area of each throttle portion 6 with respect to the relative angular displacement between the valve body 1 and the valve spool 2 occurs gently.

In the hydraulic control valve that operates as described above, when the relative angular displacement between the valve body 1 and the valve spool 2 is large, the hydraulic oil flows through the throttle portion 6 whose throttle area is reduced in accordance with the displacement. There is a problem that cavitation is generated when passing through with harsh flowing sounds. This flow noise is generated when the steering wheel is largely operated during stop or low-speed traveling in which the interior of the vehicle compartment is relatively quiet, and the propagation of the flow noise hinders the quietness of the interior of the vehicle compartment. Therefore, there is a possibility that the driver may be unnecessarily anxious. For these reasons, it is important to reduce the flow noise.

In Japanese Patent Application Laid-Open No. 8-230701 by the applicant of the present invention, the degree of occurrence of cavitation causing the above-mentioned flow noise varies depending on the flow direction of hydraulic oil in the throttle section 6 having a reduced throttle area. The flow noise is changed from the oil groove 5 on the valve spool 2 side to the oil groove 4 on the valve body 1 side.
(Hereinafter, this flow is referred to as outward flow), and large in the flow from the oil groove 4 on the valve body 1 side to the oil groove 5 on the valve spool 2 side (hereinafter, this flow is referred to as inward flow). Focusing attention, the oil grooves 4, 4... On the valve body 1 side or the oil grooves 5, 5. A hydraulic control valve for reducing flow noise is disclosed.

As shown in FIG. 5, the oil grooves 4, 4... On the valve body 1 side are used as oil supply chambers 12, 13, and the oil grooves 5, 5,. In the configured hydraulic control valve, the throttle portions 6 and 6 on both sides of the oil supply chamber 10 are provided.
An outward flow is generated at the throttle portions 6 and 6 on both sides of the oil drainage chamber 11.
Because of the occurrence of inward flow, the oil grooves 4, 4... On the valve body 1 side are offsetly arranged as shown by the broken lines in FIG. 5 to reduce the occurrence of cavitation and reduce the flow noise. Can be.

On the other hand, contrary to FIG. 5, the oil grooves 5, 5... On the valve spool 2 side are used as oil supply chambers 12, 13, and the oil grooves 4, 4,. In the hydraulic control valve configured as 11, the throttle portions 6 on both sides of the oil supply chamber 10 are provided.
6, an inward flow is generated, and the throttle portions 6 on both sides of the oil drainage chamber 11 are formed.
6 generates an outward flow, the valve spool 2
The flow noise can be reduced by offset arrangement of the oil grooves 5, 5.

[0015]

However, when the offset arrangement as described above is performed, the relative angular displacement between the valve body 1 and the valve spool 2 becomes large, and the throttle on one side of the oil discharge chamber 11 having a small area. When the section 6 is in the shut-off state, the hydraulic oil is excessively concentrated in the throttle section 6 on one side of the oil supply chamber 10, and cavitation occurs despite the flow in the throttle section 6 being an outward flow. There was a problem that could not be avoided.

The problem is that the circumferential width of the chamfer 7 formed on the corner of the oil groove 5 on the valve spool 2 side facing each of the throttle portions 6 is reduced by changing both sides of the oil supply chamber 10 and both sides of the oil discharge chamber 11. This can be solved by making the cut-off timings of the throttle portion 6 on one side of the oil supply chamber 10 and the throttle portion 6 on one side of the oil discharge chamber 11 coincide. However, the difference between the widths of the chamfers 7 actually required is small, and in order to form the two types of chamfers 7 having such a difference, a large number of man-hours and advanced processing techniques are required. There is a disadvantage that it is done.

As disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 8-230701, the offset amount of the oil grooves 4, 4,... It is a small amount of about several minutes, and the centering error generated between the forming tool and the valve body 1 when forming the oil grooves 4, 4... It is affected by a centering error generated between the tool and the valve body 1. Therefore, even when the above-described offset arrangement is performed, when viewed over the entire circumference of the fitting portion between the valve body 1 and the valve spool 2, a part of the throttle portions 6, 6,. The area may be smaller than a part of the throttle portions 6, 6 on both sides of the oil discharge chamber 11.

Therefore, in order to eliminate the mismatch of the cutoff timing due to the offset arrangement, the above-described chamfer 7,
Even if the width adjustment of 7 ... is performed accurately, the effect of this is offset by the effect of the centering error when the oil grooves 4, 4 ... are formed, and the desired improvement effect cannot be obtained. there were.

The present invention has been made in view of the above circumstances, and effectively exerts the effect of suppressing cavitation due to the offset arrangement of the oil groove on the valve body side or the valve spool side, so that the hydraulic oil passing through the throttle portion can be effectively used. An object of the present invention is to provide a hydraulic control valve which is excellent in quietness and can greatly reduce flow noise.

[0020]

A hydraulic control valve according to the present invention has a valve spool fitted to the inside of a cylindrical valve body so as to be coaxially displaceable in relative angular displacement. A plurality of provided oil grooves are arranged in a staggered manner, and a hydraulic control valve comprising a plurality of throttle portions that change the throttle area according to the relative angular displacement between respective oil grooves adjacent in the circumferential direction is provided. Of the plurality of throttle portions, a half of the flow from the oil groove on the valve spool side toward the oil groove on the valve body side has a throttle area larger than the remaining half.
The oil groove on the valve body side or the valve spool side is offset, and the angle of inclination with respect to the peripheral surface of the valve spool is set at the corner of the oil groove on the valve spool side facing each throttle part. Is characterized in that a larger chamfer is formed than in a small area narrowed portion.

In the present invention, a plurality of oil grooves arranged side by side on the inner peripheral surface of the valve body or the outer peripheral surface of the valve spool are offsetly arranged so that half of the throttle portions that generate outward flow have an inward flow. The valve spool side facing the large-area throttle portion while having a throttle area larger than the remaining half of the throttle portion to be generated, and concentrating the flow of hydraulic oil on an outward flow advantageous to the occurrence of cavitation. A chamfer having a relatively large inclination angle with respect to the peripheral surface of the valve spool is formed at the edge of the oil groove of the oil groove, and the oil is applied to the large area throttle section which keeps the opening degree after the small area throttle section reaches the shut-off state. The excessive concentration of the flow is alleviated by the action of the chamfer having a large inclination, and the occurrence of cavitation is suppressed to reduce the flow noise.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing embodiments thereof. FIG. 1 is a cross-sectional view of a hydraulic control valve according to the present invention, together with a hydraulic circuit of a power steering device.

In the figure, reference numeral 1 denotes a valve body, and 2 denotes a valve spool. On the inner peripheral surface of the cylindrical valve body 1, eight oil grooves 4, 4,... Having the same width are arranged in the circumferential direction, and have an outer diameter substantially equal to the inner diameter of the valve body 1. Similarly, on the outer peripheral surface of the thick cylindrical valve spool 2, eight oil grooves 5, 5,.
Are arranged side by side in the circumferential direction.

In the present invention, the oil grooves 5, 5,... On the valve spool 2 side are equally arranged in the circumferential direction and are juxtaposed.
The oil grooves 4, 4... On the valve body 1 side are oil grooves 4, 4,.
Of the eight lands in between, the widths of four lands located every other one are narrowed, and the widths of the remaining four lands are increased in reverse, and are offset in the circumferential direction. In FIG. 1, in order to clearly show the offset state, each oil groove 4,
Although the offset amount of 4... Is emphasized, the actual offset amount is a few minutes to several tens of minutes when converted to the central angle of the valve body 1.

Each of the oil grooves 4, 4... On the valve body 1 side has a size corresponding to the inner diameter of the valve body 1 and uses a broach having a plurality of cutting blades on the outer periphery. It is general that they are formed collectively by broach cutting to be inserted. In this case, the offset arrangement of the oil grooves 4, 4,... As described above uses a broach in which the cutting blades are unequally arranged on the circumference. Is easily realized.

The hydraulic control valve according to the present invention uses the valve body 1 and the valve spool 2 configured as described above, and fits the valve spool 2 inside the valve body 1 so as to be relatively rotatable coaxially. Both are connected to each other by a torsion bar 3 inserted inside the valve spool 2. The oil grooves 4, 4 on the valve body 1 side and the oil grooves 5, 5,... On the valve spool 2 side are staggered in the circumferential direction as shown in the figure in a neutral state where the torsion bar 3 is not twisted. Each side is positioned so as to communicate with its neighbor.

With the above construction, each of the oil grooves 4, 4... On the valve body 1 side is
Each of the oil grooves 5, 5... On the valve spool 2 side is opposed to the land between 5.
4 are opposed to the land between the valve body 1 and the valve spool 2, and the inside of the oil grooves 4, 4.
The oil chambers and the eight oil chambers outside the oil grooves 5, 5,... Are arranged alternately with a communicating portion between them.

The valve body 1 and the valve spool 2 are capable of relative angular displacement within the range of torsion of the torsion bar 3 connecting the valve body 1 and the valve spool 2, and the communicating portion between the oil chambers has a relative angular displacement. It acts as a restricting portion that increases or decreases each communication area (restricted area) accordingly. In the hydraulic control valve according to the present invention, the oil grooves 4, 4 on the valve body 1 side are provided.
Are offset as described above, the throttle areas of the throttle portions arranged on the fitting periphery with the valve spool 2 are not uniform, and the narrow land between the oil grooves 4, 4 and the valve spool 4 formed by the oil grooves 5, 5.
The eight throttle parts 6a, 6a ... located on both sides of the two oil chambers
It has a larger drawing area than the other eight drawing parts 6b.

That is, the oil grooves 5, 5...
Of the eight oil chambers formed by the above, four located at every other one will have wide narrowed portions 6a, 6a on both sides, which penetrate the peripheral wall of the valve body 1 and Oil supply chambers 10, which are connected to the discharge side of a hydraulic pump P serving as a hydraulic pressure source via respective oil guide holes having openings outside the oil grooves 5, 5, and from which hydraulic oil is supplied from the hydraulic pump P, 10…. On the other hand, on both sides, narrow narrowed portions 6b, 6b
, The other four oil chambers penetrating the valve spool 2 in the radial direction, through separate oil drain holes having openings at the bottoms of the respective oil grooves 5, 5. Connected to the oil tank T to which the oil is to be drained.
Are configured as oil discharge chambers 11, 11,.

On the other hand, the eight oil chambers formed inside the oil grooves 4, 4... Each have a wide throttle portion 6a on one side and a narrow throttle portion 6b on the other side. Of these, four oil chambers adjacent to the oil supply chambers 10 on the same side in the circumferential direction penetrate the peripheral wall of the valve body 1 and have respective oil grooves 4, 4.
The cylinder chamber S _R of one of the power cylinders S to which hydraulic pressure is to be supplied through respective oil guide holes having an opening at the bottom of the cylinder 4.
It is connected to constitute the oil transfer chambers 12, 12 ... to the cylinder chamber S _R, the remaining four, via the same pressure guide hole in the other cylinder chamber S _L of the power cylinder S are connected to constitute oil transfer chambers 13, 13 a to the cylinder chamber S _L.

FIG. 2 is an explanatory view of the operation of the hydraulic control valve according to the present invention, in which the chambers arranged on the fitting circumference of the valve body 1 and the valve spool 2 are linearly developed. In the hydraulic control valve according to the present invention, the above-described connection between the respective chambers and the cylinder chambers S _R and S _L of the hydraulic pump P, the oil tank T and the power cylinder S allows the oil supply chamber 10 shown in the center of FIG. On both sides, through the oil transfer chamber 12 or oil transfer chamber 13, the oil discharge chamber
Each of the oil passages reaching 11 has a valve body 1
Are arranged in an offset manner as described above, the oil supply chamber 10 and the oil supply chambers 12 and 13 communicate with each other through wide-width narrowed portions 6a and 6a. 12, 13 and oil drain chamber
11 is in a state of being communicated via the narrowed narrow portions 6b, 6b.

In the hydraulic control valve according to the present invention,
Valve spool 2 facing each of wide squeezed parts 6a, 6a ...
Are formed at the corners of the oil grooves 5, 5,... For adjusting the area of the diaphragm.
b, 6b ... oil grooves 5 on the valve spool 2 side facing each
Similar chamfers 7b, 7b,... Are formed at the corners of 5.
7b has a different form as described below.

FIG. 3 is an enlarged view of a main part showing a difference between the forms of the chamfers 7a and 7b. In this figure, a land between the oil grooves 5 and 5 on the valve spool 2 side is shown, and a chamfer 7a is formed on one side and a chamfer 7b is formed on the other side.
As shown, the chamfer 7a which is provided facing the throttle portion 6a having a large area which communicates with the oil supply chamber 10, while having ₁ comprising inclination angle α with respect to the circumferential surface of the valve body 2, the oil discharge chamber
Chamfer 7b provided facing the aperture portion 6b of the small area that communicates with the 11 has a same alpha ₂ consisting tilt angle, these, α _1> α ₂ become as magnitude relationship is obtained It has been set.

Further, the chamfer facing the large-area narrowed portion 6a
7a, compared to have W ₁ becomes the width in the circumferential direction of the valve body 2, chamfer 7b facing the diaphragm portion 6b of the small area
Also have a circumferential width of W ₂ ,
It is set so that a magnitude relation satisfying W ₁ <W ₂ is obtained. Note that the magnitude relation is such that the throttle portion 6a and the throttle portion 6b are almost simultaneously shut off in accordance with the relative angular displacement between the valve body 1 and the valve spool 2 which will occur as described later. .. Are set corresponding to the offset amounts of the grooves 4, 4,.

In FIGS. 2 and 3, chamfers 7a,
In order to clearly show the difference in the form of 7b, the inclination angles α ₁ and α ₂
, And the dimensional differences between the circumferential widths W ₁ and W ₂ are emphasized, but the actual angular differences and dimensional differences are slight.

FIG. 2A shows a state where a relative angular displacement does not occur between the valve body 1 and the valve spool 2 (neutral state). At this time, the throttle portions 6a, 6a on both sides of the oil supply chamber 10 have the same throttle area as each other, and the throttle portions 6b on the other side of the oil feed chambers 12, 13, which communicate with each other via these throttle portions 6a, 6a. , 6b also have the same throttle area, and the hydraulic oil supplied from the hydraulic pump P to the oil supply chamber 10 is equally distributed to the oil passages on both sides, and is discharged through the oil supply chamber 12 or 13. The oil reaches the oil chamber 11 and flows into the hollow inside the valve spool 2 through the oil drain holes that are respectively opened, and merges in the hollow to return to the oil tank T.

Therefore, there is no pressure difference between the oil supply chambers 12 and 13 and between the two cylinder chambers S _R and S _{L of} the power cylinder S connected to these oil cylinders.
Does not generate any power. At this time, the throttle portions 6a and 6b interposed in the middle of the oil path both have a sufficiently large throttle area, and a portion having a large flow resistance between the hydraulic pump P and the oil tank T. Does not exist, the driving load of the hydraulic pump P is kept small.

On the other hand, if a steering torque is applied to a steering wheel (not shown) and a relative angular displacement occurs between the valve body 1 and the valve spool 2 with the torsion of the torsion bar 3, the oil supply chamber 10 and the oil supply Restrictor 6 between chambers 12 and 13
a, 6a, and a throttle 6 between the oil supply chambers 12, 13 and the oil discharge chamber 11
The aperture area of b, 6b changes.

This change occurs on both sides of the oil supply chambers 12 and 13 in opposite directions. For example, when the relative rotation of the valve spool 2 with respect to the valve body 1 occurs clockwise in FIG. 1, the valve spool 2 relatively moves in the direction shown by the white arrow in FIG. On both sides of the oil transfer chamber 12, the throttle area of the throttle section 6a on the oil supply chamber 10 side increases, and the throttle area of the throttle section 6b on the oil discharge chamber 11 side decreases, while the throttle area of the other oil transfer chamber 13 On both sides, on the contrary,
The throttle area of the throttle section 6a on the 10 side decreases, and the throttle area of the throttle section 6b on the oil discharge chamber 11 side increases.

Accordingly, most of the pressure oil supplied to the oil supply chamber 10 is introduced into the oil supply chamber 12 through the throttle portion 6a having an increased throttle area on one side, and the cylinder chamber communicates with the oil supply chamber 12. S
Sent to _R. On the other hand, a part of the pressure oil supplied to the oil supply chamber 10 flows out to the oil supply chamber 13 through the throttle section 6a having a reduced throttle area, and this spilled oil reduces the throttle area on the other side of the oil supply chamber 13. The oil is introduced into the oil drainage chamber 11 through the increased throttle portion 6b. A part of the oil introduced into the oil feed chamber 12 is also introduced into the oil discharge chamber 11 through the throttle portion 6b having a reduced throttle area on the other side.

When the flow of the hydraulic oil as described above occurs, the internal pressure of the oil supply chamber 12 is kept substantially equal to that of the oil supply chamber 10,
The internal pressure of the oil supply chamber 13 is reduced by an amount corresponding to the reduced pressure caused by the flow of the throttle portion 6a having a reduced throttle area between the oil supply chamber 10 and the oil supply chamber 10, and between the oil supply chambers 12 and 13 and between each of them. A pressure difference occurs between the connected cylinder chambers S _R and S _L , and the power cylinder S
Generates hydraulic force directed to the S _L from the cylinder chamber S _R (steering assist force).

Further, with the operation of the power cylinder S, hydraulic oil inside the cylinder chamber S _L is pushed out, and refluxed to the oil transfer chamber 13 connected to the cylinder chamber S _L,
It joins with the hydraulic oil from the oil supply chamber 10, and is introduced into the oil discharge chamber 11 through the throttle portion 6 b having an increased throttle area on the other side of the oil supply chamber 13, and passes through the hollow portion of the valve spool 2 to the oil tank T. Is discharged.

The steering assist force generated by the power cylinder S by the above operation is applied to the throttle section between the oil supply chamber 10 and the oil supply chamber 13.
6a, and the degree of reduction of the throttle area in the throttle portion 6b between the oil drainage chamber 11 and the oil feed chamber 12 depends on the reduction degree. Here, the squeezing sections 6a, 6b
The degree of reduction of the throttle area corresponds to the relative angular displacement between the valve body 1 and the valve spool 2, and this relative angular displacement causes the torsion bar 3 connecting the valve body 1 and the valve spool 2 to twist. It corresponds to the magnitude of the steering torque applied to the steering wheel to tighten. Therefore, the power cylinder S generates a steering assist force corresponding to the magnitude of the steering torque applied to the steering wheel.

On the other hand, when the relative rotation of the valve spool 2 with respect to the valve body 1 occurs counterclockwise in FIG. 1, the throttle portions 6a, 6a on both sides of the oil supply chamber 10 and the throttle portions 6b on both sides of the oil discharge chamber 11 are provided. , 6b, the pressure change supplied to the oil supply chamber 10 is mainly introduced into the oil supply chamber 13 through the throttle portion 6b having an increased throttle area.
It is supplied to the cylinder chamber S _L communicating with the power cylinder S generates hydraulic force toward the S _R from the cylinder chamber S _L (steering assist force).

Now, in the operation state shown in FIG. 2B, the throttle portion 6a having a reduced throttle area between the oil supply chamber 10 and the oil supply chamber 13 and the connection between the oil supply chamber 12 and the oil discharge chamber 11 Hydraulic oil flows at a high speed through the action of the pressure difference between the two sides of the throttle portion 6b having a reduced throttle area in between, and cavitation occurs at this time.

In the hydraulic control valve according to the present invention, the above-mentioned offset arrangement of the oil grooves 4, 4... On the valve body 1 causes the throttle portions 6a, 6a on both sides of the oil supply chamber 10 to be on both sides of the oil discharge chamber 11. Since the throttle area is larger than the throttle sections 6b, 6b, the flow of the hydraulic oil described above is concentrated on the throttle section 6a between the oil supply chamber 10 and the oil supply chamber 13, so that the oil supply chamber
It flows outward from 10 toward the oil supply chamber 13, that is, from the valve spool 2 side to the valve body 1 side. As described above, such an outward flow is an advantageous flow for the occurrence of cavitation, and can effectively suppress the occurrence of cavitation. On the other hand, even if cavitation occurs in the inward flow in the constricted portion 6b, the generation of flow noise can be significantly reduced because the flow rate of the hydraulic oil related thereto is small.

Further, in the hydraulic control valve according to the present invention, as shown in FIG. 3, the shapes of the chamfers 7a and 7b formed on the corners of the oil grooves 5 and 5 facing the respective throttle portions 6a and 6b are as shown in FIG. The former inclination angle α ₁ is different from the latter inclination angle α ₂
Greater than. Therefore, the relative angular displacement between the valve body 1 and the valve spool 2 becomes large the throttle portion 6a, even when 6b approaches the deadline state, the throttle portion 6a, the chamfer 7a having an inclination angle alpha ₁ of the large consisting By action
In a state where a relatively large throttle area is secured, it is possible to effectively suppress the occurrence of cavitation in the flow of the hydraulic oil concentrated on the throttle portion 6a.

The circumferential width W ₁ of the chamfer 7a facing the throttle portion 6a is smaller than the circumferential width W ₂ of the chamfer 7b facing the throttle portion 6b. .. Are set corresponding to the offset amounts of the oil grooves 4, 4,. Therefore, the valve body 1 and the valve spool 2
When the relative angular displacement with respect to
Are almost simultaneously shut off, so that excessive concentration of the flow to the constricted portion 6a after the constriction of the constricted portion 6b can be reduced, and the occurrence of cavitation due to this can be suppressed.

Simultaneous shutoff by setting the width of the chamfers 7a and 7b is accurately realized by the offset processing of the oil grooves 4, 4... And the centering error in the inner surface grinding of the valve body 1 as described above. Difficult to do. However, in the hydraulic control valve according to the present invention, the throttle portion 6b
Simultaneous deadline and can not be accurately realized, even the concentration of flow to the throttle portion 6a occurs, cavitation by the above-described action of the chamfer 7a having an inclination angle alpha ₁ made large formed in the narrowed portion 6a Generation is suppressed. Therefore, the formation of the oil grooves 4, 4... Of the valve body 1, the chamfers 7a,
It is possible to effectively suppress cavitation and the accompanying flow noise without requiring high processing accuracy for the formation of the 7b and the inner surface grinding of the valve body 1.

The hydraulic control valve according to the present invention is shown in FIGS.
The oil grooves 4, 4... On the valve body 1 side are used as an oil supply chamber 10 and an oil discharge chamber 11, and the oil grooves 5, 5,. It can also be realized in the configuration described above.

FIG. 4 is an operation explanatory view showing this embodiment. As in FIG. 2, the chambers arranged on the fitting periphery of the valve body 1 and the valve spool 2 are linearly developed. In this case, an inward flow from the valve body 1 toward the valve spool 2 is generated between the oil supply chambers 12 and 13 adjacent to each other on both sides of the oil supply chamber 10. An outward flow from the valve spool 2 toward the valve body 1 is generated between the adjacent oil supply chambers 12 and 13.

In this hydraulic control valve, the oil grooves 5, 5... On the valve spool 2 side are offset so that large-diameter throttle portions 6a, 6a are formed on both sides of the oil discharge chamber 11 where outward flow occurs.
However, narrowing portions 6b, 6b having small areas are formed on both sides of the refueling chamber 10 where an inward flow occurs, respectively. As a result, FIG.
As shown in (b), when the relative angular displacement occurs between the valve body 1 and the valve spool 2, the oil discharge chamber 11
The flow of the hydraulic oil is concentrated on the narrowed portion 6a on one side, and cavitation and the generation of flow noise due to the cavitation can be suppressed.

Further, chamfers 7a and 7b are formed at the corners of the oil groove 5 on the valve spool 2 side facing the throttle portions 6a and 6b, respectively, and the former chamfer 7a is compared with the latter chamfer 7b. The valve spool 2 has such a shape that its inclination angle with respect to the peripheral surface is large and its width in the circumferential direction is small. As a result, simultaneous closing of the squeezed portions 6a and 6b is realized, and a shift in the closing timing due to the influence of the processing error is absorbed, so that the occurrence of cavitation can be more effectively suppressed.

In the above embodiment, an example of using the power steering device as a hydraulic control valve for controlling the oil pressure supplied to the power cylinder has been described. However, the scope of the present invention is not limited to this. The present invention can be applied to all rotary hydraulic control valves having a plurality of throttle portions on the fitting periphery of the valve body 1 and the valve spool 2 and changing the throttle area in accordance with the relative angular displacement between the two. Needless to say.

[0055]

As described above in detail, in the hydraulic control valve according to the present invention, the throttle portion in which the outward flow occurs due to the offset arrangement of the plurality of oil grooves arranged on the inner peripheral surface of the valve body or the outer peripheral surface of the valve spool. Has a larger throttle area than the throttle part where inflow occurs, so that the flow of hydraulic oil concentrates on the outward flow, which is advantageous for the occurrence of cavitation, and effectively reduces the occurrence of cavitation. Since a chamfer having a large inclination angle with respect to the peripheral surface of the valve spool is formed at the corner of the oil groove on the valve spool side facing the large-area throttle section, the oil can be suppressed to the large-area throttle section. The present invention is advantageous in that excessive concentration of flow can be mitigated, the effect of suppressing cavitation can be enhanced, and the flow noise associated therewith can be reduced, contributing to improved quietness. It was an effect.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a hydraulic control valve according to the present invention.

FIG. 2 is an operation explanatory view of a hydraulic control valve according to the present invention.

FIG. 3 is an enlarged view of a main part showing a difference in the form of a chamfer.

FIG. 4 is an operation explanatory view showing another embodiment of the hydraulic control valve according to the present invention.

FIG. 5 is a diagram illustrating the operation of a conventional hydraulic control valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Valve body 2 Valve spool 4 Oil groove 5 Oil groove 6a, 6b Throttle part 7a, 7b Chamfer 10 Oil supply chamber 11 Drainage chamber 12 Oil transfer chamber 13 Oil transfer chamber P Hydraulic pump S Power cylinder

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3D033 FD06 FD09 3H053 AA12 AA33 BA04 BB03 DA11 3H067 AA12 CC12 CC15 DD03 DD12 DD23 EA14 EB02 FF11 GG15 GG22

Claims (1)

[Claims] 1. A valve spool is fitted inside a cylindrical valve body so as to be coaxially displaceable in relative angle,
A plurality of oil grooves arranged side by side on the fitting circumference of the two are arranged in a staggered manner, and between the oil grooves adjacent to each other in the circumferential direction, a plurality of throttle portions that change the throttle area according to the relative angular displacement are formed. In the hydraulic control valve configured, half of the plurality of throttle portions in which a flow from the oil groove on the valve spool side to the oil groove on the valve body side has a throttle area larger than the remaining half. The oil groove on the valve body side or the valve spool side is offset, and the angle of inclination with respect to the peripheral surface of the valve spool is reduced by a large area at the corner of the oil groove on the valve spool side facing each throttle part. A hydraulic control valve, characterized in that a larger chamfer is formed in a portion than in a narrow portion having a small area.