JPH07329802A - Rotary valve and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a pressure feeding characteristic which steeply rises in accordance with rotation of a spool valve part. CONSTITUTION:This rotary valve is constituted of a sleeve valve part 1 and a spool valve part 2, and fluid pressure is adjusted by relative displacement of land parts 12, 22 in accordance with relative rotation of the spool valve part 2. An end part in the peripheral direction of the land part 22, which is in contact with a recessed strip groove 21, is formed into a control groove 23 inclined downward toward the recessed strip groove 21, and a stepped part 24 having a vertical wall surface 24a is formed in the intermediate part of slopes 23a, 23b of the control groove 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary valve,
In particular, the present invention relates to a structure improvement of a rotary valve and a manufacturing method thereof which are suitable for use in a power steering device of an automobile for switching assist hydraulic oil and adjusting supplied hydraulic pressure.

[0002]

2. Description of the Related Art FIG. 10 shows an example of a rotary valve used in a power steering device. As shown in the figure, the rotary valve has a sleeve valve portion 1 and a spool valve portion 2 that rotate relative to each other, and a plurality of groove grooves 11 and a plurality of land portions 12 are formed around the inner circumference of the sleeve valve portion 1. Are formed alternately on the outer circumference of the spool valve portion 2.
One and a plurality of land portions 22 are alternately formed in the circumferential direction, and both circumferential end portions of the land portion 22 contacting the groove groove 21 are chamfered to be inclined at a predetermined angle toward the groove groove 21. It is a control groove 23 for controlling. The relative position between the control groove 23 and the land portion 12 of the sleeve valve portion 1 is changed by the rotation of the spool valve portion 2 caused by the steering operation, and the hydraulic fluid is supplied by the throttle passage formed between them. The pressure (relief pressure) is controlled.

By the way, in order to reduce the load of the steering wheel operation, it is necessary to secure sufficient hydraulic assistance in accordance with the steering wheel operation. On the other hand, in order to maintain the stability of the steering wheel, the steering wheel operating angle is in a small range. On the contrary, the hydraulic assist should be small. Therefore, as the output characteristics of the rotary valve, it is desired that the hydraulic pressure supplied is small until the steering wheel operating angle (manual torque) exceeds a certain range, and the hydraulic pressure (steering pressure) rises sharply when the steering angle exceeds the above range.

Therefore, in order to obtain such pressure characteristics, the shape of the control groove is not a simple inclined surface, but the inclination angle is changed midway as shown in FIG.

[0005]

However, in the conventional control groove shape of the above rotary valve, the increase of the steering pressure with respect to the increase of the manual torque is slow, and the stability of the steering wheel operation and the lightness are not yet compatible with each other. There was a problem.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a rotary valve capable of obtaining a pressure supply characteristic that rises sharply and a method of manufacturing the same.

[0007]

According to a first aspect of the present invention, there is provided a tubular sleeve valve portion 1 and a spool valve portion 2 fitted in the sleeve valve portion 1 so as to be rotatable relative to each other. The land portions 12 and 22 and the concave groove portions 11 and 21 are alternately formed on the opposing peripheral surfaces of the portions 1 and 2, and the land portions 12 and 22 and the concave groove portions 11 and 21 are caused by the rotation of the spool valve portion 2. In the rotary valve that switches the supply and discharge of the fluid by the relative displacement of, the circumferential end of the land portion 22 of either the sleeve valve portion 1 or the spool valve portion 2 in contact with the groove groove 21 is formed into the groove groove 21. A stepped portion 24 having a vertical wall surface 24a is formed in the middle of the slopes 23a and 23b of the control groove 23 while forming the control groove 23 that is inclined downward.

According to the second aspect of the present invention, after the concave groove 21 is formed by cutting with the narrow cutter C1 to a predetermined depth, the concave groove 21 is widened beyond the width of the concave groove 21 by the cutter C2. A stepped portion 24 having an L-shaped cross section having a vertical wall surface is cut and formed at a shallower position, and the stepped portion 24 and the general surface of the land portion 22 are bounded to each other, and the stepped portion 24 and the concave groove 21 are formed. Chamfering and grinding the boundary areas of the above to form slopes 23a and 23b which are inclined downward toward the groove 21.

According to the third aspect of the present invention, the sleeve valve portion 1 having a tubular shape and the spool valve portion 2 fitted in the sleeve valve portion 1 so as to be rotatable relative to each other are provided, and the valve portions 1 and 2 face each other. The land portions 12 and 22 and the concave groove portions 11 and 21 are alternately formed on the peripheral surface of the fluid, and the relative displacement of the land portions 12 and 22 and the concave groove portions 11 and 21 due to the rotation of the spool valve portion 2 causes the fluid to flow. In a rotary valve that switches between supply and discharge, one of the land portion 2 of the sleeve valve portion 1 or the spool valve portion 2 is
The end of the groove 2 in the circumferential direction which is in contact with the groove 21 is formed as a control groove 23 which is inclined downward toward the groove 21, and the lengths of the slopes 23c and 23d of the control groove 23 are set to the length of the land 22. Make different steps at predetermined positions in the width direction.

[0010]

According to the first aspect of the present invention, when the spool valve portion rotates, the land portion and the concave groove provided on both the spool valve portion and the sleeve valve portion are displaced relative to each other, and the control groove and the control groove move. The flow passage area of the throttle flow passage formed between the land portion and the land portion that faces is changed. The supply pressure of the fluid is controlled by the change in the flow passage area. Here, in the configuration of the present claim, since the stepped portion having the vertical wall surface is formed in the middle of the slope of the control groove, the flow channel area of the throttle channel is such that When it approaches, the pressure suddenly decreases and the fluid supply pressure rises sharply.

According to the method of the second aspect, the flow passage area of the throttle flow passage is gentle at first, and is rapidly reduced when the vertical wall surface of the stepped portion approaches the land portion, and the fluid supply pressure is reduced. It is possible to easily and reliably manufacture a rotary valve that can obtain steering characteristics such as a steep rise.

Also in the configuration of claim 3, the fluid supply pressure is controlled by changing the flow passage area of the throttle flow passage formed between the moving control groove and the land portion facing the control groove. Since the lengths of the slopes of the control groove are made different in the width direction of the land portion, the position where the slope surface of the control groove approaches the facing land portion is displaced in the width direction due to the relative movement of the spool valve portion. Therefore, when the slope having a long length first approaches the land portion and the slope having a short length reaches the land portion thereafter, the flow passage area of the throttle passage is sharply reduced, and the fluid supply pressure rises sharply.

[0013]

First Embodiment In FIG. 1, reference numeral 3 denotes a housing body of a power steering device, and a control shaft 4 and a pinion shaft 5 are rotatably supported by the housing body 3. The control shaft 4 and the pinion shaft 5 are flexibly rotatably connected via a torsion bar 6, and a rack shaft (not shown) is meshed with the pinion shaft 5. The power cylinder 6 shown in FIG. 2 and wheels (not shown) are connected to the rack shaft. A rotary valve is housed in the valve hole 31 (FIG. 1) of the housing body 3, and this rotary valve is composed of a sleeve valve portion 1 and a spool valve portion 2 which are relatively rotatable.

The control shaft 4 is connected to a handle (not shown), and a part of the control shaft 4 serves as a spool valve portion 2. The sleeve valve portion 1 is integrally connected to the pinion shaft 5 by a connecting pin 51. As shown in FIG. 2, a plurality of groove grooves 11 are formed in the circumferential direction on the inner circumference of the sleeve valve portion 1, and a land portion 12 is formed between the groove grooves 11. Every other one of these land portions 12 is opened with a supply passage 13 leading to the pump 7. Further, in each groove 11, the distribution passages 14 leading to the left and right pressure chambers 61, 62 of the power cylinder 6 are alternately provided. 15 is open.

A plurality of groove grooves 21 are formed in the circumferential direction on the outer circumference of the spool valve portion 2, and land portions 22 are formed between the groove grooves 21. And these groove 21
In every other, a discharge passage 25 communicating with the tank 8 is formed. When the spool valve portion 2 rotates counterclockwise in FIG. 2, the hydraulic oil in the supply passage 13 is supplied to the left pressure chamber 61 of the power cylinder 6 via the distribution passage 14, and the supply pressure at this time is A in the figure. Is controlled by the flow passage area of the throttle flow passage formed between the two land portions 12 and 22. When the spool valve portion 2 rotates clockwise, the hydraulic oil in the supply passage 13 is supplied to the right pressure chamber 62 via the distribution passage 15,
The supply pressure at this time is as shown in the portion B of FIG.
It is controlled by the flow passage area of the throttle flow passage formed between 22.

The recessed groove 2 formed in the spool valve portion 2
1 and the land portion 22 will be described in detail below. FIG. 3 shows a spool valve portion 2 formed on a part of the control shaft 4.
Is seen from the outside in the radial direction, and FIG. 4 shows IV- of FIG.
It is sectional drawing which follows the IV line. In FIG. 3, the spool valve portion 2 has a plurality of outer circumferential portions (one of which is shown in the figure) that is recessed in a rectangular shape in the axial direction to form recessed grooves 21, and both circumferential edges thereof are stepped. Then, it rises up (FIG. 4) and continues to the land portion 22 which is flush with the general outer peripheral surface of the spool valve portion 2.

An end portion of the land portion 22 which is in contact with the groove groove 21 is a control groove 23 which inclines downward toward the groove groove 21. The control groove 23 has slopes 23a having different angles, A stepped portion 24 is formed at an intermediate position of 23b. The stepped portion 24 has a right-angled triangular cross section having a wall surface 24a that rises vertically, and extends in the width direction of the land portion 22 (vertical direction in FIG. 3). At the neutral position of the rotary valve, as shown in FIG.
From the end surface of the land portion 12 of the
The angles are θ1, θ2, and θ3, respectively, from the rising position of 2, the position of the wall surface 24a, and the starting position of the outer peripheral general surface of the land portion 22.

The procedure for molding the spool valve portion 2 will be described with reference to FIG. 5. The peripheral surface of the spool valve portion 2 is formed by the narrow rotary cutter C1 provided on the rotary shaft arranged so as to be orthogonal to the control shaft 4. Width direction (shaft axis direction)
A groove having a deep rectangular cross section extending to is formed by cutting to form a groove 21. Subsequently, a shallow L-shaped groove is formed on both side edges (one side edge is shown in the figure) of the groove 21 by the wide rotary cutter C2 to form the stepped portion 24. Then, by a rotary grindstone G provided on a rotary shaft arranged in parallel with the control shaft 4, a slope 23b on the side closer to the general surface of the land 22 and a slope 23a on the side closer to the groove 21 are chamfered by grinding. To do.

According to the rotary valve having the control groove 23 as described above, the flow passage area of the throttle flow passage F formed between the opposing land portions 12 and 22 (FIG. 4) has the rotation angles θ1 to θ.
Between 2 and 2, the wall diameter 24a of the stepped portion 24 approaches the land portion 12, and the wall surface 24a of the stepped portion 24 rapidly becomes smaller between the rotation angles θ2 and θ3. As a result, the steering pressure rises sharply when the manual torque proportional to the steering wheel operating angle exceeds a predetermined value, as indicated by the line x in FIG. The line y in the figure indicates the stepped portion 24.
It shows the characteristics of a conventional rotary valve that does not have, and the steering pressure rises slowly.

Therefore, according to the rotary valve of the present invention, the steering pressure is sufficiently small in the range where the steering wheel operating angle is small, and the stability of the steering wheel is maintained. Further, as the steering wheel operation angle increases, the steering pressure rapidly increases, and a light steering wheel operation is guaranteed. According to the present embodiment, the steering pressure characteristic can be variously adjusted by changing the height of the wall surface 24a of the stepped portion 24.

[0021]

[Embodiment 2] In FIG. 7, a concave groove 21 formed on the outer periphery of the spool valve portion 2 is formed in a rectangular shape in the range of L2 in the axial direction of the control shaft 4, and in the range of L1 at an intermediate position. The width is wide with steps. Both side edges of the groove 21 are stepped up toward the land 22 (FIGS. 8 and 9), and then the land 22 is inclined at a constant upslope.
It is a control groove 23 continuing to the general surface. This control groove 23
In the region where the groove 21 is wide (L1 in the figure), the length of the slope 23c is short (FIG. 8), and in the region where it is narrow (L2 in the figure), the length of the slope 23d is long. It is getting longer (Fig. 9). Then, the land portion 12 of the sleeve valve portion 1
From the end face to the lower end position of each of the slopes 23d and 23c and the start position of the general surface of the land portion 22, the angle θ is formed.
They are 1, θ2, and θ3 apart.

In order to form the spool valve portion 2 as described above, a narrow rotary cutter provided on a rotary shaft arranged so as to be orthogonal to the control shaft 4 is used to form a width direction (shaft axial direction) on the circumferential surface of the spool valve portion 2. ), A rectangular groove extending L2 in length is formed, and then a rectangular groove extending L1 in length is formed in the middle of the rectangular groove by a wide rotary cutter to form a groove 21. After that, with a rotary grindstone provided on a rotary shaft arranged in parallel with the control shaft 4, the slopes 23c, 2 are inclined at a constant angle from the general surface of the land portion 22 toward the end surface of the groove 21.
3d is chamfered by grinding to form a control groove 23.

According to the rotary valve having the control groove 23 as described above, the flow passage area of the throttle flow passage F formed between the opposing land portions 12 and 22 (FIGS. 8 and 9) has a rotation angle θ.
Between 1 and θ2, the inclined surface 23d having a width of (L2-L1) approaches the land portion 12, and becomes gradually smaller with the relative rotation of the spool valve portion 2. When the spool valve portion 2 further rotates to reach the rotation angle θ2 to θ3, the slope 23c having a width of L1 approaches the land portion 12 in addition to the slope 23d. Suddenly becomes smaller. As a result, as described in the first embodiment, when the manual torque exceeds the predetermined value, the desired characteristic that the steering pressure sharply rises is obtained.

In the present embodiment, the above L1, L
The steering pressure characteristics can be adjusted in various ways by changing the ratio of 2.

In each of the above embodiments, the control groove is formed in the land portion of the spool valve portion, but it may be formed in the land portion of the sleeve valve portion.

[0026]

As described above, according to the present invention, the rotary valve can be provided with a pressure supply characteristic that steeply rises, and such a rotary valve can be easily manufactured, and a power steering device for an automobile can be obtained. Can be used and get excellent effect.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a main part of a power steering device incorporating a rotary valve of the present invention.

FIG. 2 is a cross-sectional view taken along the line II-II of FIG.

FIG. 3 is a plan view of the spool valve portion according to the embodiment of the present invention as viewed from the outer peripheral direction.

FIG. 4 is an enlarged sectional view taken along line IV-IV in FIG.

FIG. 5 is a sectional view illustrating a procedure for forming a control groove.

FIG. 6 is a graph showing steering pressure characteristics.

FIG. 7 is a plan view of a spool valve portion according to another embodiment of the present invention as viewed from the outer peripheral direction.

8 is a cross-sectional view taken along the line VIII-VIII of FIG.

9 is a sectional view taken along line IX-IX in FIG.

FIG. 10 is a partial cross-sectional view of a rotary valve showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sleeve valve part 11 Recessed groove 12 Land part 2 Spool valve part 21 Recessed groove 22 Land part 23 Control groove 23a, 23b, 23c, 23d Slope 24 Stepped part 24a Wall surface

Claims (3)

[Claims] 1. A cylindrical sleeve valve portion and a spool valve portion fitted in the sleeve valve portion so as to be rotatable relative to each other, and a land portion and a concave groove are alternately arranged on opposing circumferential surfaces of these valve portions. In the rotary valve which is formed on the rotary valve for switching the supply and discharge of the fluid by the relative displacement of the land portion and the groove groove as the spool valve portion rotates, the concave portion of the land portion of either the sleeve valve portion or the spool valve portion is It is characterized in that the end in the circumferential direction in contact with the groove is formed as a control groove which inclines downward toward the groove, and a stepped portion having a vertical wall surface is formed in the middle of the slope of the control groove. Rotary valve. 2. A cylindrical sleeve valve portion and a spool valve portion fitted in the sleeve valve portion so as to be rotatable relative to each other, and a land portion and a concave groove are alternately arranged on opposing circumferential surfaces of these valve portions. In the method for manufacturing a rotary valve in which fluid supply and discharge are switched by relative displacement between the land portion and the groove groove formed by rotation of the spool valve portion, the groove groove is formed at a predetermined depth by a narrow cutter. After cutting and forming, a stepped portion having an L-shaped cross section having a vertical wall surface is formed at a position shallower than the groove by a cutter having a width exceeding the width of the groove.
A boundary area between the stepped portion and the general surface of the land portion and a boundary area between the stepped portion and the groove groove are chamfered and ground to form a slope inclined downward toward the groove groove. And a method for manufacturing a rotary valve. 3. A cylindrical sleeve valve portion and a spool valve portion fitted in the sleeve valve portion so as to be rotatable relative to each other, and a land portion and a concave groove are alternately arranged on opposing circumferential surfaces of these valve portions. In the rotary valve which is formed on the rotary valve for switching the supply and discharge of the fluid by the relative displacement of the land portion and the groove groove as the spool valve portion rotates, the concave portion of the land portion of either the sleeve valve portion or the spool valve portion is The end of the groove in contact with the groove is formed as a control groove that is inclined downward toward the groove, and the length of the slope of the control groove is stepped at predetermined positions in the width direction of the land. A rotary valve characterized by that.