JPH0618149U - Hydraulic control valve - Google Patents

Abstract

(57) [Summary] [Purpose] It is possible to achieve a substantially simultaneous shut-off at the throttle portion inside the hydraulic control valve without impairing the desired two-step bending characteristic as an increase characteristic of the steering assist force in the power steering device.
Suppresses flow noise and cavitation. [Structure] A cutout portion 7 is formed on a side edge of the oil groove 4 on the valve body 1 side facing a throttle portion 6, and a valve spool 2 is provided.
The chamfered portions 8 are respectively formed on the side edges of the oil grooves 5 on the side facing the narrowed portions 6. The cutout portion 7 includes a first portion 7a that is substantially parallel to the peripheral surface of the valve body 1 and a second portion 7b that intersects the first portion 7a and the peripheral surface of the valve body 1 at a substantially right angle. It consists of a valve body 1 and a valve spool 2.
With respect to the relative angular displacement with respect to, the function is to keep the diaphragm area of the diaphragm portion 6 constant. The chamfered portion 8 has a linear shape that is inclined at a predetermined crossing angle on each of the peripheral surface of the valve spool 2 and the side wall of the oil groove 5, and includes the valve body 1 and the valve spool 2.
With respect to the relative angular displacement with respect to, the function is to keep the diaphragm area of the diaphragm portion 6 constant. A two-step folding characteristic is realized by the synergistic action of both.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a rotary hydraulic control valve that controls the hydraulic pressure to be fed to a destination according to the relative angular displacement between a valve body and a valve spool that are generated coaxially, and particularly in a hydraulic power steering device. The present invention relates to a hydraulic control valve used to control the hydraulic pressure supplied to a power cylinder that generates a steering assist force according to a steering wheel operation.

[0002]

[Prior art]

 The hydraulic power steering system assists steering by the hydraulic pressure generated by the double-acting hydraulic cylinder (power cylinder) arranged in the steering mechanism, reducing the labor load required for steering wheel operation and making it comfortable. It is intended to obtain a steering feeling, both cylinder chambers of the power cylinder (oil destination), a hydraulic pump (hydraulic power source) driven by the engine, and an oil tank (drain destination) for storing hydraulic oil. A hydraulic control valve that controls the supply and discharge of hydraulic pressure according to the direction and magnitude of the steering torque applied to the steered wheels is interposed between the control valve and the control valve.

As the hydraulic control valve, a rotary hydraulic control valve that directly uses the rotation of the steering wheel is generally used. This is because an input shaft connected to the steering wheel and an output shaft connected to the steering mechanism are coaxially connected via a torsion bar, and a valve spool integrally formed at one connecting end is connected to the other connecting end. When the steering torque is applied to the steered wheels, it is fitted inside the combined tubular valve body so that it can rotate relative to each other coaxially, and the twisting of the torsion bar causes a gap between the valve body and the valve spool. It has a structure that causes relative angular displacement.

A plurality of oil grooves are equally arranged on the fitting circumference of the valve body and the valve spool, and these oil grooves are arranged in a staggered manner in the circumferential direction in a state where the torsion bar is not twisted. It is located between the oil supply chamber and the oil discharge chamber, which are in communication with the oil source and the oil discharge destination, and between the oil discharge chambers on both sides of the oil supply chamber. A pair of oil feed chambers that communicate with each other are configured. Each of these chambers communicates with the adjacent chambers via a throttle formed between the side edges of the respective oil grooves, and the throttle area of these throttles is between the valve body and the valve spool. It increases or decreases in accordance with the above-mentioned relative angular displacement, and contributes to the above-mentioned supply / discharge control.

That is, when the relative angular displacement does not occur between the valve body and the valve spool, the hydraulic pressure supplied from the hydraulic pressure source to the oil supply chamber passes through the throttle parts (control throttles) on both sides of the oil supply chamber to both sides. Of the oil supply chambers, and is not fed to the power cylinder, but is introduced into the oil discharge chamber through the throttle portion (recirculation throttle) on the other side of each oil supply chamber, and once introduced into the oil discharge chamber. The power cylinder only returns to the oil tank through the oil drain hole that opens, but the steering torque is applied to the steering wheel and the relative angular displacement is generated between the valve body and the valve spool. If there is a problem, the throttling area of the control throttling on both sides of the lubrication chamber increases on one side and decreases on the other, and as a result, the hydraulic pressure supplied to the lubrication chamber is on one side (on the side where the throttle area is increased). Mainly in one oil transfer chamber via the control throttle Is introduced as a pressure difference between the oil feed chamber and the other oil feed chamber, and between both cylinder chambers of the power cylinders communicating with each other, and the power cylinder corresponds to this pressure difference. Generates hydraulic pressure.

The pressure difference generated at this time depends on the reduction degree of the throttle area in the control throttle on the other side (the side where the throttle area is reduced), and this reduction degree is the magnitude of the relative angular displacement, that is, the steering wheel. Corresponds to the amount of steering torque applied to. Therefore, the hydraulic pressure (steering assist force) generated by the power cylinder has a direction corresponding to the operating direction of the steering wheel and a strength corresponding to the magnitude of the steering torque applied to the steering wheel, and assists the steering. be able to. The oil pushed out from the other cylinder chamber due to the operation of the power cylinder flows back to the other oil feed chamber of the hydraulic control valve, and the throttle area increases on one side of the oil feed chamber. The oil is introduced into the adjacent oil discharge chambers through the reflux throttle, and is discharged to the oil tank through an oil discharge hole having one end opened in the oil discharge chambers.

The magnitude of the force required to steer an automobile depends on the magnitude of the road surface reaction force acting on the wheels. When the road surface reaction force is large, such as when the vehicle is stopped or running at low speed, While a large amount of force is required, steering can be performed with a relatively small force in a traveling state in which the road surface reaction force is small, such as during high-speed traveling. From this, as shown in FIG. 7, a desirable steering assist force increase characteristic in the power steering apparatus is a characteristic in which the degree of increase of the steering assist force with respect to the increase of the steering torque changes in two steps, so-called two-stage. It is said to have a fold characteristic.

When such a two-step bending characteristic is obtained, the steering torque applied to the steered wheels is small, and a substantially constant small steering assist force is obtained until a predetermined value T ₁ is reached (constant range). However, since the steering wheel is provided with appropriate rigidity, it is possible to improve straight running stability during high-speed traveling. Further, after the steering torque applied to the steering wheel reaches a large value T ₂ (rapid increase range), a steering assist force that sharply increases as the steering torque increases is obtained, and steering wheel operation for steering is performed. The required force can be reduced as much as possible. Further, between T ₁ and T ₂ (gradual increase region), a steering assist force that gradually increases in proportion to an increase in steering torque is obtained, and a resistance that increases in proportion to the degree of steering wheel operation. Will be experienced and a natural steering feeling will be obtained.

The steering assist force in the power steering apparatus corresponds to a pressure difference generated between both oil chambers of the power cylinder, and this pressure difference occurs in accordance with a change in the throttle area in the throttle portion of the hydraulic control valve. Therefore, in order to realize the above-described two-step bending characteristic, the throttle area of the throttle portion changes in accordance with an increase in the relative angular displacement between the valve body and the valve spool, that is, the relative angle. It is necessary to show a mode of change in which the displacement is maintained substantially constant until it reaches a predetermined magnitude, and then rapidly changes.

Therefore, conventionally, a notch is formed at a corner of a side edge of the oil groove facing the throttle portion to obtain a desired state of change of the throttle area to obtain a two-step bending characteristic in a power steering apparatus. Various hydraulic control valves have been proposed in the past, which are intended to be realized. Among these, as one that can relatively faithfully realize the above-described change mode, there is, for example, one provided with a notch portion shown in FIG.

In the figure, 4 is an oil groove formed in the valve body 1, and 5 is an oil groove formed in the valve spool 2. The valve body 1 and the valve spool 2 both have a cylindrical shape and are fitted to each other so as to be rotatable relative to each other on the same axis. FIG. 8 is a diagram in which these are expanded in a straight line. As shown in the drawing, the oil grooves 4 and 5 communicate with each other through the throttle portions 6 and 6 having equal areas on both sides in the width direction when the relative angular displacement does not occur between the valve body 1 and the valve spool 2. It is positioned so that

At the side edge of the oil groove 4 on the valve body 1 side that faces the throttle portion 6, a notch portion 40 that realizes the above-described mode of changing the throttle area is formed. As shown in the drawing, the notch 40 has a first end 40a extending from the side wall of the oil groove 4 and extending substantially parallel to the inner peripheral surface of the valve body 1, and the portion 40a. It is provided with a second portion 40b that connects the tip end and the inner peripheral surface of the valve body 1 so as to cross each other.

FIG. 9 is an explanatory diagram of a changing state of the aperture area in the aperture portion 6 having the cutout portion 40. The relative angular displacement between the valve body 1 and the valve spool 2 is caused by the valve at the intersection between the neutral position shown in FIG. 8 and the second portion 40b and the inner circumference of the valve body 1 as shown in FIG. 9 (c). It occurs between the position reached by the side edge of the oil groove 5 on the spool 2 side, a so-called shut-off position.

During this time, the throttle area of the throttle portion 6 sharply decreases until the side edge of the oil groove 5 is aligned with the side edge of the oil groove 4 on the valve body 1 side, as shown in FIG. 9A. Then, as shown in FIG. 9 (b), until the side edge of the oil groove 5 reaches near the intersection of the first and second portions 40a, 40b, the depth dimension of the first portion 40a. Since the first portion 40a is substantially parallel to the outer peripheral surface of the valve body 1, the throttle area is maintained substantially constant regardless of an increase in relative angular displacement. A gradually increasing range of steering assist force can be obtained.

By the time the greater relative angular displacement occurs and the shut-off position shown in FIG. 9C is reached, the throttle area of the throttle portion 6 is the side edge of the oil groove 5 and the second portion 40b. Between them, the clearance s in the circumferential direction becomes dominant, and this clearance s shows a sharp decrease in accordance with an increase in the relative angular displacement, so that a steep increase range of the steering assist force in FIG. 7 can be obtained. . It should be noted that, in order to give an appropriate inclination to the sudden increase area and to mitigate a sudden change in resistance when operating the steering wheel, there is a 45 ° angle between the inner circumference of the valve body 1 and the second portion 40b. The crossing angle θ (see Fig. 10) is secured.

[0016]

[Problems to be solved by the device]

 The notch 40 having the above-described shape may be formed on the side edge of the oil groove 5 on the valve spool 2 side facing the throttle portion 6, but in reality, due to processing restrictions, the valve body is not formed. It is often formed on the side edge of the oil groove 4 on the first side. That is, the oil grooves 4, 4 on the side of the valve body 1 are conventionally formed by using a broach having a plurality of blades corresponding to the shapes of the oil grooves 4, 4, ... The broaching process is performed so that it penetrates into the inside of the cylinder that is the material of the body 1, and the cutouts 40 are formed on these oil grooves 4, 4 ... Side by forming cutouts at the corners of the corresponding blades. By using a broach having a protrusion corresponding to the shape of the portion 40, the oil grooves 4, 4 ... Can be formed simultaneously with the formation of the oil grooves 4, 5 ,. Generally, it is formed by groove processing on the outer circumference, and in order to form the cutouts 40, 40 ... Having the above-described shapes on the side edges of such oil grooves 5, 5 ,. This is because it is necessary to separately form grooves on the side edges, which requires a great deal of labor.

However, the inner peripheral surface of the valve body 1 requires high-precision finishing for fitting with the valve spool 2, and this finishing requires that the oil groove 4 and the notch 40 are formed by broaching. Since it is performed after the formation, the position of the line of intersection between the inner peripheral surface of the valve body 1 and the second portion 40b of the cutout portion 40 is displaced in the circumferential direction due to the misalignment during the both processes.

This state is shown in FIG. When the inner circumferential surface of the valve body 1 which should be at the position shown by the solid line in the formation portion of the oil groove 4 shown in the figure is displaced to the position shown by the broken line due to the misalignment of α generated during processing, the valve body 1 The line of intersection between the inner peripheral surface and the second portion 40b of the cutout 40 is displaced in the circumferential direction of the valve body 1 and the valve spool 2 by the distance indicated by β in the figure.

Further, a plurality of oil grooves 4 are equally arranged on the inner circumference of the valve body 1, and the oil groove 4 at a position radially opposed to the illustrated oil groove 4 has a size of α. Since the misalignment occurs in the radial opposite direction, the intersection line between the second portion 40b of the cutout portion 40 and the inner circumferential surface of the valve body 1 in each of these is 2β relatively in the circumferential direction. Only the distance is shifted.

That is, in the conventional hydraulic control valve, when the above-described shut-off state is obtained in some throttle portions 6 due to the relative angular displacement between the valve body 1 and the valve spool 2, the other throttle portions 6 are subject to the above-mentioned shut-off state. It is difficult to achieve simultaneous shut-off at a plurality of throttle portions 6, 6 arranged side by side in the circumferential direction, which may leave a gap due to misalignment, and the flow of hydraulic oil is part of the throttle portion 6. And the flow of oil in the throttle 6 causes annoying flow noise, which not only makes the driver uncomfortable, but also causes cavitation due to a sudden pressure reduction before and after the throttle 6. However, there is a risk that only a part of the throttle portion 6 may be damaged early and the normal operation of the hydraulic control valve may be hindered.

The present invention has been made in view of such circumstances, and it is possible to achieve substantially the same time in each narrowing portion without impairing the two-step folding characteristic obtained by forming the notch portion having the above-described shape. An object of the present invention is to provide a hydraulic control valve that can be shut off and can suppress the generation of flow noise and cavitation associated with the flow of hydraulic oil.

[0022]

[Means for Solving the Problems]

 A hydraulic control valve according to the present invention has a plurality of oil grooves formed on the fitting circumference of a cylindrical valve body and a valve spool that are coaxially displaced relative to each other in a staggered arrangement, and is connected to a hydraulic source. Chamber, an oil discharge chamber connected to the oil discharge destination, and an oil feed chamber connected to the oil feed destination between the two chambers are arranged side by side. In the hydraulic control valve that controls the hydraulic pressure to be fed to the oil destination, the relative angular displacement reaches a predetermined magnitude at the side edge of the oil groove on the valve body side that faces the throttle portion. Until then, a chamfered portion having a predetermined width in the circumferential direction is provided at a side edge of the oil groove on the valve spool side facing the notched portion, the chamfered portion having a shape that keeps the throttle area substantially constant. It is characterized by including.

[0023]

[Action]

 In the present invention, a notch portion is provided at the side edge of the oil groove on the valve body side, and only a portion that acts to keep the throttle area constant is provided, and the intersection line between the inner periphery of the valve body and the notch portion is provided. Is prevented from being displaced in the circumferential direction, and a chamfered portion having a predetermined width is formed on the side edge of the oil groove on the valve spool side facing the notch portion, and the chamfered portion causes the second portion to move. That is, the drawing area is sharply reduced before the cutoff, and the two-step folding characteristic is realized by the synergistic effect of the notch and the chamfer.

[0024]

【Example】

 Hereinafter, the present invention will be described in detail with reference to the drawings showing an embodiment thereof. FIG. 1 is a transverse sectional view of a hydraulic control valve according to the present invention, which is shown together with a hydraulic circuit of a power steering device.

In the figure, 1 is a valve body and 2 is a valve spool. On the inner peripheral surface of the cylindrical valve body 1, eight oil grooves 4, 4 ... Having a predetermined width equal to each other are formed at equal intervals in the circumferential direction. Further, on the outer peripheral surface of the valve spool 2 having a thick cylindrical shape having an outer diameter substantially equal to the inner diameter of the valve body 1, similarly, eight oil grooves 5 having mutually equal predetermined widths are formed. , 5 ... Are formed so as to be evenly arranged in the circumferential direction.

The valve spool 2 is internally fitted to the valve body 1 so as to be rotatable relative to each other on the same axis, and both are mutually connected 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 drawing in a neutral state where the torsion bar 3 is not twisted. And are positioned so as to communicate with the adjacent ones through the uniform width gaps on both sides.

With the above structure, between the oil grooves 4, 4 on the valve body 1 side and the outer peripheral surface of the valve spool 2, and between the oil grooves 5, 5 on the valve spool 2 side and the inner peripheral surface of the valve body 1. The eight oil chambers respectively formed between the two chambers are alternately arranged in parallel on the fitting circumference of the valve body 1 and the valve spool 2, and the gaps communicating these chambers are formed by the torsion bar. ... function as throttle portions 6, 6 ... Which change the throttle area according to the relative angular displacement between the valve body 1 and the valve spool 2 caused by the twist of the valve 3.

Out of the eight oil chambers on the outside of the oil grooves 5, 5, ..., four oil chambers located at every other one of the eight oil chambers are hydraulically operated through respective oil guide holes penetrating the peripheral wall of the valve body 1. Connected to the discharge side of the source hydraulic pump P, the oil supply chambers 10, 10 ... To which the generated hydraulic pressure of the hydraulic pump P is supplied are configured. Further, of the remaining four oil chambers, the two located opposite to each other in the radial direction are provided with respective separate oil drain holes penetrating the valve spool 2 in the radial direction and hollow portions inside the valve spool 2. Is connected to an oil tank T which is an oil discharge destination, and constitutes oil discharge chambers 11a and 11a which are passages of the oil discharged to the oil tank T. The remaining two are a hydraulic pump P and an oil tank. T, and the cylinder chamber S _R to be described later power cylinder S, not connected to any of S _L, is simply Configure the passing oil chamber 11b, 11b which serves as a passage for oil.

The hydraulic control valve provided with such oil passage chambers 11b and 11b was proposed by the applicant of the present application in order to reduce internal flow noise, and is disclosed in Japanese Utility Model Laid-Open No. 2-26974. However, the present invention can be applied to a general hydraulic control valve that does not include these oil passage chambers 11b and 11b.

On the other hand, among the eight oil chambers inside the oil grooves 4, 4, ..., four adjacent to the oil supply chambers 10, 10 ... from the same side in the circumferential direction are the peripheral walls of the valve body 1. The oil supply chambers 12, 12, ... To the cylinder chamber S _{R are connected} to one cylinder chamber S _R of the power cylinder S, which is the destination of the hydraulic pressure, through the respective oil passage holes penetrating therethrough. The remaining four oil chambers also constitute oil feed chambers 13, 13 ... Which are connected to the other cylinder chamber S _L of the power cylinder S.

FIG. 2 is an explanatory view showing the respective chambers lined up on the fitting circumference of the valve body 1 and the valve spool 2 by linearly expanding them. With the configuration described above, the oil passage extending from the oil feed chamber 12 (or the oil feed chamber 13) to the oil drain chamber 11a is provided on one side of the oil feed chamber 10, and the oil feed chamber 13 (or the oil feed chamber 13 is provided on the other side). Through the chamber 12) to the oil passage chamber 11b, and further to the other oil supply chamber 10 via the oil feed chamber 12 (or the oil feed chamber 13) adjacent to the other side of the oil passage chamber 11b. , The respective chambers are communicated with each other by the narrowed portions 6, 6 ...

The throttle portions 6 and 6 on both sides of each chamber open and close in opposite directions with respect to the relative angular displacement between the valve body 1 and the valve spool 2 due to their respective forming positions. That is, when the throttle area of the throttle portion 6 between the oil supply chamber 12 (or the oil supply chamber 13) and the oil supply chamber 10, the oil discharge chamber 11a or the oil passage chamber 11b decreases, the other oil supply chamber The throttle area of the throttle portion 6 of the same type in 13 (or the oil supply chamber 12) increases.

In the hydraulic control valve according to the present invention, the notch is formed in the side edge of the oil groove 4 on the valve body 1 side facing the throttle portions 6 and 6 between the oil passage chamber 11b and the oil feed chambers 12 and 13. The chamfered portion 8 is formed on the side edge of the oil groove 5 facing the cutout portion 7, and the side edge of the oil groove 5 on the valve spool 2 side facing the remaining throttle portions 6, 6 ... A notch 9 is formed on the bottom.

FIG. 3 is an enlarged view of the cutout portion 7. As shown in the drawing, the cutout portion 7 has a base end that extends from the side wall of the oil groove 4 and extends substantially parallel to the inner peripheral surface of the valve body 1, as with the cutout portion 40 in the conventional hydraulic control valve. Further, it is provided with a first portion 7a and a second portion 7b which connects the tip of the portion 7a and the inner peripheral surface of the valve body 1 so as to cross each other. The crossing angle θ between the inner circumference of the valve body 1 and the second portion 7b is different from the conventional cutout 40, and is an angle close to a right angle, specifically, an angle of about 75 °.

The notch 7 as described above is formed at the same time as the formation of the oil grooves 4, 4, ... By broaching, as in the conventional case, and as described above, thereafter, for fitting with the valve spool 2. The inner peripheral surface of the valve body 1 is finished. Therefore, also in the hydraulic control valve according to the present invention, as shown in FIG. 3, due to the center misalignment α generated during both processes, the crossing line between the inner peripheral surface of the valve body 1 and the second portion 7b is A positional deviation of β is generated in the circumferential direction.

However, since the second portion 7b of the cutout portion 7 intersects with the inner circumference of the valve body 1 with a crossing angle θ close to a right angle, the above-mentioned positional deviation β is kept extremely small. Can be done. This is clear from the comparison between FIG. 3 and FIG. It is desirable that the crossing angle θ be a right angle (= 90 °) in order to minimize the amount of positional deviation β, but the actual crossing angle θ is smaller than the right angle due to processing restrictions. It is unavoidable that the angle is small, and it is set to around 75 ° as described above.

On the other hand, the chamfered portion 8 formed on the side edge of the oil groove 5 facing the cutout portion 7 has a predetermined width b in the circumferential direction, and has a side wall of the oil groove 5 and the outer periphery of the valve spool 2. It is a linear notch that intersects the surface at an angle of 45 ° before and after, and a notch formed on the side edge of the oil groove 5 that faces the throttle 6 without the notch 7. Reference numeral 9 is a linear or arcuate notch having a depth and a circumferential width B in which the notch 7 and the chamfer 8 are combined. After the oil grooves 5, 5, ... Are bored on the outer circumference of the spool 2, the corner portions on both sides of these oil grooves are ground, so that the width dimensions b and B in the circumferential direction can be easily formed while accurately controlling them.

1 and 2 show a state (neutral state) in which relative angular displacement is not generated between the valve body 1 and the valve spool 2. In this case, the throttle portions 6, 6 between the chambers have the same throttle area and are in an open state as shown in the drawing, and the pressure oil supplied from the hydraulic pump P to the oil supply chamber 10 is on both sides. The oil is evenly distributed to the oil passages, reaches the oil discharge chamber 11a via the oil supply chamber 12 or 13, and flows into the hollow portion of the valve spool 2 through the oil discharge holes opening to each of them, and joins in the hollow portion. Then, the oil is returned to the oil tank T.

Therefore, at this time, no pressure difference is generated between the oil feed chambers 12 and 13 and between both cylinder chambers S _R and S _{L of the} power cylinder S connected to each of them, and the power cylinder S is The power of does not occur. Further, since there is no portion that generates a great flow resistance in the oil passage from the hydraulic pump P to the oil tank T, the driving load of the hydraulic pump P is kept small.

On the other hand, when the valve spool 2 rotates relative to the valve body 1 in the clockwise direction in FIG. 1, for example, one of the oil supply chamber 12 and the oil supply chamber 10 increases in accordance with an increase in relative angular displacement between the two. Between the oil supply chamber 10 and the oil supply chamber 13 and between the oil supply chamber 13 and the oil discharge chamber 11a. The throttle areas of the throttle portions 6 and 6 between the chamber 12 and the oil discharge chamber 11a respectively decrease. Further, between the oil feed chambers 12 and 13 and the oil feed chamber 11b, the throttling area of the throttle portion 6 on the oil feed chamber 13 side increases and the oil feed chamber 12 side increases, as on both sides of the oil drain chamber 11a. The squeezing area of the squeezing portion 6 is reduced.

At this time, most of the oil supplied to the oil supply chamber 10 is introduced into the oil supply chamber 12 via the throttle portion 6 on the side where the throttle area is increased, and the remaining part is on the side where the throttle area is decreased. The oil leaks into the oil supply chamber 13 through the throttle portion 6 of the. On the other hand, a part of the oil introduced into the oil feed chamber 12 leaks into the oil feed chamber 11b and the oil feed chamber 13 via the throttle portion 6 having a reduced throttle area on the other side. Therefore, the internal pressure of the oil feed chamber 12 is maintained substantially equal to that of the oil feed chamber 5, while the internal pressure of the oil feed chamber 13 is set between the oil feed chamber 13 and the oil feed chamber 10 and between the oil feed chamber 5 and the oil feed chamber 10. Between the chamber 12 and the oil passage chamber 11b, the pressure is reduced by the amount of pressure reduction due to the oil passage of the throttle portion 6 in which the throttle area is reduced. between been cylinder chamber S _R, S _L, caused a pressure difference corresponding to the pressure reduction amount in the throttle portion 6, 6 ... minus the stop surface product is, the power cylinder S from the cylinder chamber S _R to S _L Generates an oncoming hydraulic pressure.

The hydraulic pressure generated by the power cylinder S depends on the degree of reduction of the throttle area that occurs in each of the throttle portions 6, and the reduction of the throttle area causes the relative reduction between the valve body 1 and the valve spool 2. While occurring in response to the angular displacement, this relative angular displacement corresponds to the magnitude of the force applied to the torsion bar 3 connecting the valve body 1 and the valve spool 2 so as to twist the torsion bar 3. Therefore, when the steering torque applied to the steered wheels is applied to the torsion bar 3, the steering assist force generated by the power cylinder S corresponds to the direction and magnitude of the steering torque applied to the steered wheels. .

Note that, with the above-described operation of the power cylinder S, the enclosed oil in one cylinder chamber S _L is pushed out, but this oil is returned to the oil feed chamber 13 communicating with the cylinder chamber S _L. , Joins the oil leaking from the oil supply chamber 10 and flows into the oil discharge chamber 11a without resistance through the throttle portion 6 on the other side of the oil supply chamber 13 where the throttle area is increased. The oil is discharged to the oil tank T through the hollow portion of the lube spool 2.

The changing state of the aperture area of the aperture section 6 during the above-described operation is shown in FIGS. 4, 5 and 6 which is linearly expanded as in FIG. The white arrow in each drawing indicates the moving direction of the valve spool 2 with respect to the valve body 1.

The relative angular displacement between the valve body 1 and the valve spool 2 is calculated from the neutral position shown in FIGS. 1 and 2 through the first intermediate position shown in FIG. 4 and the second intermediate position shown in FIG. As shown in FIG. 4, the throttle portion 6 between the oil supply chamber 13 and the oil supply chamber 10 and the throttle portion 6 between the oil supply chamber 12 and the oil passage chamber 11b reach a position (closed position) to be closed. Occurs. During this time, the throttle area of the throttle portion 6 between the oil supply chamber 13 having the cutout portion 9 and the oil supply chamber 10 decreases substantially proportionally as the relative angular displacement increases. The throttle area of the throttle portion 6 between the oil supply chamber 12 having the cutout portion 7 on the valve body 1 side and the chamfered portion 8 on the valve spool 2 side and the oil passage chamber 11b depends on the relative angular displacement. The following changes are shown.

The first intermediate position shown in FIG. 4 is a position where the side wall of the oil groove 5 on the valve spool 2 side is substantially aligned with the side wall of the oil groove 4 on the valve body 1 side in the circumferential direction. The second intermediate position shown in is the position where the side wall of the oil groove 5 on the valve spool 2 side is aligned with the intersection line of the first portion 7a and the second portion 7b in the cutout portion 7. From the neutral position to the first intermediate position, the aperture area of the aperture section 6 decreases sharply, but from the first intermediate position to the second intermediate position, the aperture area of the aperture section 6 decreases. The depth dimension a of the first portion 7a of the cutout portion 7 is dominated, and the first portion 7a is substantially parallel to the outer circumference of the valve body 1. The squeezing area is maintained substantially constant.

Until the relative angular displacement further increases and reaches the shut-off position beyond the second intermediate position, the throttle area of the throttle portion 6 is the same as that of the second portion 7b of the notch portion 7 and the valve body. 1 is controlled by the gap s in the circumferential direction between the line of intersection with the inner peripheral surface of No. 1 and the line of intersection between the chamfered portion 8 on the side edge of the oil groove 5 and the outer periphery of the valve spool 2, and relative angular displacement Shows a sharp decrease with increasing.

The pressure difference between the left and right cylinder chambers S _R, S _L of the power cylinder S is a reduction of such restriction area at the throttle portion 6 between the oil supply chamber 12 and the oil passage chamber 11b, the oil feed The steering torque is increased between the first intermediate position and the second intermediate position because it is governed by the substantially proportional reduction of the throttle area in the throttle portion 6 between the chamber 13 and the fuel supply chamber 10. A small increase rate is shown, and the gradual increase region of the steering assist force in Fig. 7 is obtained, and between the second intermediate position and the dead position, between the oil supply chamber 12 and the oil passage chamber 11b. As the throttle area in the throttle section 6 decreases sharply, a large increase rate is exhibited, and a steep increase area of the steering assist force in FIG. 7 is obtained.

In the hydraulic control valve according to the present invention, the second portion 7b of the cutout portion 7 formed on the valve body 1 side and the inner circumference of the valve body 1 intersect at a substantially right angle, The notch 7 and the notch 9 on the valve spool 2 side are not affected by misalignment at the time of machining the inner peripheral surface of the valve body 1 at the circumferential position of the crossover line. The widths b and B in the circumferential direction can be accurately managed and formed. Therefore, in all the throttle portions 6, 6 ... Arranged side by side on the fitting circumference of the valve body 1 and the valve spool 2 as shown in FIG. 1, the shut-off state as shown in FIG. 6 can be obtained almost simultaneously. .

Further, since the chamfered portion 8 is provided on the side edge of the oil groove 5 on the valve spool 2 side facing the cutout portion 7, it is possible to impart an appropriate change rate to the throttle area before the shutoff position. It is possible to secure a predetermined inclination in the area where the steering assist force is rapidly increased during this period, and to mitigate a sudden change in resistance during steering wheel operation.

That is, in the hydraulic control valve according to the present invention, the two-step folding characteristic as shown in FIG. 7 can be achieved by the synergistic action of the notch portion 7 and the chamfer portion 8 which are provided so as to face the throttle portion 6. At the same time, the chamfered portion 8 on the side of the valve spool 2 can secure the inclination in the sudden increase area. Therefore, the second portion 7b of the cutout portion 7 intersects the inner periphery of the valve body 1 at a substantially right angle. By doing so, it is possible to avoid the positional deviation caused by the inner peripheral processing of the valve body 1 on the intersection line of both, and the simultaneous closing at the multiple throttle parts 6, 6 ... In addition, the flow does not concentrate in a part of the throttle portions 6, and it is possible to mitigate the risk of flow noise and cavitation caused by this concentration.

[0052] In the present embodiment, constituted by the oil grooves 4, 4 ... valve body 1, two cylinder chambers S _R of the power cylinder S serving as the oil supply destination, the oil transfer chambers 12 and 13 communicating with the S _L Then, the oil grooves 5, 5 on the side of the valve spool 2 constitute the oil supply chamber 10, the oil discharge chamber 11a, and the oil communication chamber 11b, which communicate with the hydraulic pump P and the oil tank T, respectively. The oil supply chamber 10, the oil discharge chamber 11a and the oil passage chamber 11b may be configured by the grooves 4, 4, ... And the oil supply chambers 12, 13 may be configured by the oil grooves 5, 5 ,.

Further, in the present embodiment, among the throttle portions 6, 6 ... Lined up on the fitting circumference of the valve body 1 and the valve spool 2, a part of the throttle portions 6, 6 ,. The cutouts 7 and the chamfered portions 8 are provided only on both sides of the chamber 11b, but the cutouts 7 and the chamfered portions 8 may be provided on all the throttled portions 6, 6 ...

Further, in the present embodiment, the hydraulic control valve for controlling the hydraulic pressure to be fed to the power cylinder of the power steering apparatus has been described. The hydraulic control valve according to the present invention has the hydraulic pressure control valve as shown in FIG. It goes without saying that it can be applied to applications in which increased characteristics are required.

[0055]

[Effect of device]

 As described above in detail, in the hydraulic control valve according to the present invention, the notch provided on the side edge of the oil groove on the valve body side facing the throttle has a predetermined relative angular displacement between the valve body and the valve spool. It only acts to keep the throttle area of the throttle part constant until it reaches the limit, and the chamfered part provided on the side edge of the oil groove on the valve spool side facing the throttle part reduces the throttle area before shutting off. Since it has the effect of sharply reducing it, it is possible to achieve a practical simultaneous shutoff at each throttle by controlling the width of the chamfered portion without deteriorating the desired two-step fold characteristic, and it occurs with the flow of hydraulic oil. The present invention has excellent effects such as reducing the jarring flowing sound, suppressing the occurrence of cavitation, and preventing characteristic changes due to damage to some of the throttles.

[Brief description of drawings]

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

FIG. 2 is a diagram in which an oil passage inside a hydraulic control valve according to the present invention is linearly developed.

FIG. 3 is an enlarged view of a cutout portion in the hydraulic control valve according to the present invention.

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

FIG. 5 is an operation explanatory view of the hydraulic control valve according to the present invention.

FIG. 6 is an explanatory view of the operation of the hydraulic control valve according to the present invention.

FIG. 7 is a graph showing a desirable increase characteristic of steering assist force in the power steering apparatus.

FIG. 8 is a view showing a manner of forming a notch portion in a conventional hydraulic control valve.

FIG. 9 is an operation explanatory diagram of a conventional hydraulic control valve.

FIG. 10 is an explanatory diagram of a problem of the conventional hydraulic control valve.

[Explanation of symbols]

 1 Valve Body 2 Valve Spool 4 Oil Groove 5 Oil Groove 6 Throttling Part 7 Notch 8 Chamfer 10 Lubrication Chamber 11 Oil Discharge Chamber 12 Oil Feed Chamber 13 Oil Feed Chamber 50 Notch P Hydraulic Pump S Power Cylinder

Claims (1)

[Scope of utility model registration request] 1. A plurality of oil grooves formed on a fitting periphery of a cylindrical valve body and a valve spool, which are coaxially displaced relative to each other in a relative angle, are arranged in a staggered manner, and an oil supply chamber connected to a hydraulic pressure source and a drainage chamber are provided. An oil discharge chamber connected to the oil destination and an oil supply chamber connected to the oil destination between both chambers are installed side by side, and the throttle area of the throttle unit that connects these chambers is increased or decreased according to the relative angular displacement. In the hydraulic control valve for controlling the hydraulic pressure to be fed to the oil destination, on the side edge of the oil groove on the valve body side facing the throttle portion, until the relative angular displacement reaches a predetermined magnitude, A cutout portion having a shape that keeps the throttle area substantially constant is provided, and a chamfered portion having a predetermined width in the circumferential direction is provided at a side edge of the oil groove on the valve spool side facing the cutout portion. And hydraulic control valve.