JPH032110B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power steering valve for a power steering device used in a vehicle that uses pressure fluid to assist manual steering force, and particularly to a power steering valve designed to eliminate fluid noise.

A power steering device includes a pressure fluid generation source, a power steering valve, and a power cylinder. The pressure fluid generated by the pressure fluid generation source is controlled by the power steering valve and transmitted to the power cylinder, and the power of the power cylinder is used to control the steering wheels. This is to assist manual steering force by moving the steering wheel. The power steering valve of this power steering device has a narrow part of the flow path, so when the power steering is activated, when the pressurized fluid passes through the power steering valve, a fluid sound such as hissing is generated, which impairs the quietness of the car interior. . In order to eliminate this fluid noise, the flow path on the drain side of the power steering valve has been constricted during power steering operation to increase the back pressure fluid.

Conventional power steering valves of this type include those shown in FIGS. 1 to 3, for example. 1 is a valve housing, and 2 is a drain port provided protruding from the valve housing 1. 3 is a plug for drain port 2. 4 is a valve body, 5 is a torsion bar, and 6 is a pinion gear. A plate 7 that is urged leftward in FIG. 1 by a spring is arranged in the drain port 2, and holes 8 and 9 are provided in the plate 7. A gap is provided between the plate 7 and the wall 2a of the drain port 2. 10 is a piston, and a valve shaft 11
1, and moves to the right in FIG. 1 as the operating pressure within the valve housing 1 increases. These plate 7, piston 10, spring, etc. constitute a back pressure control valve 12.

In this conventional power steering valve, when a steering wheel (not shown) is operated and the internal operating pressure increases, the piston 10 moves to the right in the figure, as shown in FIG. to block drain port 2. As a result, the drain port 5 communicates with the inside of the valve housing 1 through the small holes 8 and 9, thereby increasing the back pressure inside the valve housing 1. Therefore, it is possible to eliminate fluid noise when pressure fluid passes through the power steering valve.

Further, when the steering wheel is not operated, as shown in FIG. 3, the plate 7 is urged by the elastic force of the spring and moves to the left in the figure. As a result, the pressure fluid flows through a relatively large flow path area as shown by the arrow in the figure, so that no large load is applied to the pump.

However, in the case of such a conventional power steering valve, the back pressure control valve 12 is configured by slidingly inserting the piston 10 connected to the plate 7 into a hole formed in the valve housing 1. It is configured to be biased by a spring. As described above, the structure of the back pressure control valve 12 becomes complicated and the number of component parts increases, so the shape of the power steering valve becomes large, which further increases manufacturing cost and weight. There was a problem.

The present invention has been made by focusing on such conventional problems, and includes a back pressure control valve that includes a chamber defined in the middle of a drain flow path to open the drain flow path, and a chamber that opens the drain flow path to the chamber. a passage for introducing the pressure of the pressure fluid in the inlet passage flowing from the control valve; the chamber is defined into a small chamber into which the drain passage opens; and a small chamber into which the passage opens; An elastic member having a plurality of protrusions and capable of closing the open end of the drain flow path, and a bypass flow path communicating the drain flow path upstream and downstream of the chamber. The present invention aims to solve the above problems by providing a power steering valve configured with the following.

The present invention will be explained below based on the drawings.

4 and 5 are diagrams showing an embodiment of the present invention.

First, the configuration will be described. Reference numeral 21 indicates a power steering valve as a whole, and a control valve 36 and a back pressure control valve 38 are housed in a valve housing 22 of the power steering valve. The valve housing 22 consists of a generally cylindrical housing body 22a and a member 24 fixed to the housing body 22a.The housing body 22a has an inlet port (not shown) connected to a pressure fluid supply source (not shown) and There is an outlet port (not shown) connected to an external actuator. Further, a plug 32 is screwed onto the member 24, and this plug 32
is provided with a drain port 37 connected to a reservoir (not shown) on the pressure fluid supply source side. The member 24 has a recess on the side of the housing body 22a, and defines a chamber 26 together with the housing body 22a. This chamber 26 includes a first drain passage 25 formed in the member 24, a second drain passage 27 formed in the member 24 and the housing body 22a,
is open. The chamber 26, the first drain passage 25, and the second drain passage 27 communicate with the drain port 37 and the control valve 36 side. Further, a hole 28 (passage) formed in the housing body 22a opens into the chamber 26. This hole 28 penetrates through the housing main body 22a and communicates the upstream side of the control valve 36, for example, the inlet port, with the chamber 26, and transmits a pressure corresponding to the working pressure of the pressure fluid supplied to the power cylinder as an actuator into the chamber. 26. 29 is a diaphragm made of an elastic body such as rubber, and the periphery of this diaphragm 29 is connected to the member 2.
4 and the housing body 22a,
The chamber 26 is liquid-tightly defined into two small chambers 26a and 26b. The hole 28 is opened in one of the small chambers 26a, and the pressure on the upstream side of the control valve 36 is introduced into the other small chamber 26b.
Drain channel 25 and second drain channel 27 are open. In addition, a relatively small diameter bypass passage 30 is formed in the member 24 and communicates the first drain passage 25 and the second drain passage 27. A minimum flow path area is ensured between the two. These first drain passages 2
5 and the second drain channel 27 constitute the drain channel 23. A reinforcing material 31 made of a material such as hard rubber is embedded in the center of the diaphragm 29, and this reinforcing material 31 protects the drain channel 23 of the diaphragm 29 when the diaphragm 29 is displaced to the right in the figure.
A first drain passage 25 and a second drain passage 2 are provided on the side surface.
7 and securely close it. A plurality of, for example, three, annular projections 29a are formed on the side surface of the diaphragm 29 on the side of the drain passage 23 between the peripheral edge and the center. These chambers 26, holes 28, diaphragms 29, bypass passages 30 and reinforcements 31
constitutes the back pressure control valve 38.

As is well known, the control valve 36 has a substantially cylindrical valve body 33 that is rotatably housed in a housing body 22a, and a valve shaft 34 is coaxially connected to the valve body 33 in a hollow portion of the valve body 33. It is inserted so that it can rotate freely. The valve body 33 has grooves on its outer periphery that communicate with the inner peripheral wall surface of the housing body 22a and the outlet port, inlet port, and drain port, and holes that penetrate from these grooves to the hollow portion. . Valve shaft 34 protruding from valve housing 22
An end portion (upper end in the figure) is connected to a steering wheel (not shown) via a steering shaft (not shown), and a torsion bar 35 is coaxially inserted into a hollow portion of the valve shaft 34. The torsion bar 35 has an enlarged diameter end (upper end in the figure).
is non-rotatably connected to the valve shaft 34, and the other end (lower end in the figure) meshes with a rack connected to the piston of a power cylinder (actuator) not shown, for example. ), and its diameter-reduced intermediate portion is loosely inserted into the hollow portion of the valve shaft 34. In this control valve 36, when a steering force exceeding a predetermined value is applied to the steering wheel, a relative rotational displacement corresponding to this steering force occurs between the valve body 33 and the valve shaft 34, and the outlet port and intake The let port is communicated with the valve opening degree corresponding to the operating force, and relatively high pressure fluid is supplied to one chamber of the power cylinder. At this time, the other chamber of the power cylinder is drained. Also,
These valve body 33, valve shaft 34, and torsion bar 35 can block the inlet port from the outlet port without causing any relative rotational displacement between the valve body 33 and the valve shaft 34 when the steering wheel is not steered. Connects to the drain port. In addition,
As is well known, a power cylinder has a piston connected to a steering wheel, which is easily fixed, and defines two fluid chambers in the cylinder.
A steering assist force is generated by the pressure difference between the fluid chambers into which pressurized fluid flows in and out.

Next, the action will be explained.

If the steering wheel (not shown) is not steered and no steering force is applied to the valve shaft 34 from the steering shaft (not shown), no relative rotation will occur between the valve shaft 34 and the valve body 33. Therefore, the control valve 36 blocks the inlet port and the outlet port, and communicates the inlet port and the drain port, as described above. Therefore, the pressure fluid flowing into the inlet port from the pressure fluid supply source (not shown) does not flow into the outlet port, that is, the power cylinder, but flows from the second drain flow path 27 to the back pressure control valve 38 and the first drain flow path. via channel 25 into a reservoir. At this time, in the back pressure control valve 38, as shown in FIG. 4, the diaphragm 29 is displaced to the left in the figure, and the first drain flow path 25 and the second drain flow path 27 are connected via the small chamber 26b. The first drain flow path 25 and the second drain flow path 27 communicate with each other and have a sufficient flow area. Therefore, the pressure fluid flowing from the second drain flow path 27 flows into the first drain flow path 25 through the small chamber 26b, and also flows into the first drain flow path 25 through the bypass path 30, and the pressure fluid flows into the first drain flow path 25 through the small chamber 26b. There is no need to apply an excessive load to drive equipment such as pumps.

Next, when the steering wheel is steered and a steering force is applied from the steering shaft to the valve shaft 34, a relative rotational displacement occurs between the valve shaft 34 and the valve body 33. Therefore, the control valve 36 has an inlet port and an outlet port, as described above.
The inlet port and drain port 37 are communicated with each other with a valve opening corresponding to the steering force. Therefore, the pressure fluid flowing into the inlet port from the pressure fluid supply source flows into the outlet port, that is, the power cylinder, and is discharged from the drain port 37, corresponding to the opening degree of each valve of the control valve 36, and is discharged from the drain port 37. A cylinder provides steering assistance to the steering of the steering wheel.
By the way, the pressure of the pressure fluid supplied from the pressure fluid supply source increases due to the throttling action of the control valve 36 when the steering wheel is steered. Therefore, the pressure inside the small chamber 26a that communicates with the inlet port through the hole 28 increases, and the fifth
As shown in the figure, after the diaphragm 29 is displaced to the right in the figure and the protrusion 29a is crushed, the first drain passage 25 and the second drain passage 27 are closed. Therefore, the pressure fluid flowing out from the second drain passage 27 is transferred from the second drain passage 27 to the bypass passage 30.
It flows to the first drain flow path 25 through the drain flow path 25, and is then discharged to the reservoir. As a result, when the steering wheel is steered, the pressure drop that occurs when the pressure fluid passes through the control valve 36 is reduced, and no fluid noise is generated.
The quietness inside the vehicle is maintained. In this way, the back pressure control valve 38 has a diaphragm 29 made of an elastic body, and this diaphragm 29 closes the flow path between the first and second drain flow paths 25 and 27 due to an increase in the operating pressure of the control valve 36. By reducing the area, the pressure on the downstream side of the control valve 36 during steering of the steering wheel is increased. Therefore, like a conventional power steering valve,
There is no need for the piston 10, plate 7, spring, etc., and the structure of the back pressure control valve is simplified and the number of parts is reduced, so the power steering valve becomes smaller, and the manufacturing cost is lower. , the weight becomes lighter. Moreover, the diaphragm 29 between the peripheral portion and the center portion is
The elastic force generated by the crushing of the projection 29a prevents excessive displacement toward the small chamber 26b as much as possible. Therefore, it is possible to suppress the internal stress generated in the elastic body,
As a result, the fatigue life of the diaphragm 29 is extended.

Next, when the steering wheel is returned to its original state, the pressure fluid flowing into the inlet port from the pressure fluid supply source is discharged from the drain port 37 without flowing into the outlet port. Then, the pressure in the small chamber 26a decreases.
Therefore, the diaphragm 29 can be
It is displaced to the left in the figure and restored to its original state. At this time, a reaction force toward the small chamber 26a due to the elastic restoring force of the protrusion 29a also acts on the diaphragm 29.
The restoration of the diaphragm 29 is ensured. Moreover,
The increased rigidity provided by the projections 29a prevents the diaphragm 29 from being excessively displaced and extends its fatigue life, thereby improving the durability of the power steering valve.

FIG. 6 shows another embodiment of the drain channel side small chamber defined by the diaphragm 29. The bottom surface of the small chamber 40 in this embodiment is closer to the protrusion 29a than the bottom surface of the small chamber 26a in the previous embodiment. Furthermore, a protrusion 40a is formed on the bottom surface of the protrusion 40a, and the first and second drain channels 25, 27 are opened at the tip end surface. In the case of this embodiment, since the displacement of the diaphragm 29 to the right in the figure is small, the fatigue life of the diaphragm 29 is further extended.

As explained above, according to this invention,
A back pressure control valve is a control valve that selectively connects an inlet flow path connected to a pressure fluid supply source that generates pressurized pressure fluid to an outlet flow path connected to an actuator and a drain flow path that discharges the pressure fluid. The control valve is housed in a housing and controls the flow of pressure fluid in response to steering of the steering wheel, and a back pressure control valve is provided in the drain flow path, and the back pressure control valve is configured to In the power steering valve that changes the flow area of the drain flow path according to the pressure of the pressure fluid on the side of the inlet flow path, the back pressure control valve is defined in the middle of the drain flow path and controls the drain flow. a chamber into which the passage is opened; a passage into which the pressure of pressure fluid on the inlet passage side flowing from the control valve is introduced; the chamber into a small chamber into which the drain passage opens and a small chamber into which the passage opens; an elastic member defining an elastic member having one or more protrusions on a side surface of the drain flow path and capable of closing an opening of the drain flow path; and a drain flow path on an upstream side and a drain flow path on a downstream side of the chamber. The structure includes a communicating bypass passage and an elastic member that reduces the flow area of the drain flow path as the operating pressure increases during steering, making the power steering valve smaller and further reducing the manufacturing cost of the power steering valve. The benefits include lower cost, lighter weight, and improved durability.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a conventional power steering valve, Figs. 2 and 3 are sectional views of essential parts showing the flow of pressure fluid in the power steering valve shown in Fig. 1, and Fig. 4 is an embodiment of the present invention. A sectional view showing the power steering valve according to the example, FIG. 5 is a sectional view of the main part showing the flow of pressure fluid of the fourth power steering valve, and FIG. 6 is another embodiment of the chamber of the power steering valve according to the present invention. FIG. 21...Power steering valve, 22...
Valve housing, 23...Drain channel, 25...
...First drain passage, 26... Chamber, 26a, 26
b, 40...Small chamber, 27...Second drain passage, 2
8...hole (passage), 29...diaphragm (elastic member), 29a...protrusion, 30...bypass passage,
36...control valve, 37...drain port, 38...back pressure control valve.

Claims (1)

[Claims] 1. A control valve that selectively connects an inlet passage connected to a pressure fluid supply source that generates pressurized pressure fluid to an outlet passage connected to an actuator and a drain passage that discharges the pressure fluid is attached to the valve housing. The control valve controls the flow of pressure fluid in accordance with the steering of the steering wheel, and the drain flow path is provided with a back pressure control valve, and the back pressure control valve controls the flow of pressure fluid from the control valve. In the power steering valve that changes the flow area of the drain flow path according to the pressure of the pressure fluid on the inlet flow path side, the back pressure control valve is defined in the middle of the drain flow path, and the back pressure control valve is defined in the middle of the drain flow path. a chamber into which the drain flow path is opened; a passage into which the pressure of pressure fluid on the inlet flow path side flowing from the control valve is introduced; and the chamber is divided into a small chamber into which the drain flow path opens and a small chamber into which the passage opens. an elastic member having one or more protrusions on a side surface of the drain flow path and capable of closing an open end of the drain flow path; and a drain flow path on the upstream side and the drain flow path on the downstream side of the chamber. A power steering valve characterized by having a communicating bypass passage.