JPH0225835B2 - - 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 back pressure.

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 is disposed on the drain port 2 and is biased toward the left in FIG. 1 by a spring.
The plate 7 is provided with small holes 8 and 9. A gap is provided between the plate 7 and the wall 2a of the drain port 2. 10 is a piston, which is disposed at right angles to the valve shaft 11 and is connected to the valve housing 1.
It moves to the right in FIG. 1 due to an increase in the working pressure inside. 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 2 communicates with the inside of the valve housing 1 through the small holes 8 and 9, 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 such a conventional power steering valve, the back pressure control valve 12
The piston 10 connected to the plate 7 is slidably inserted into the hole formed in the valve housing 1, and the plate 7 is inserted into the hole formed in the valve housing 1.
is configured to be biased by a spring. For this reason, the back pressure control valve 12 has a complicated structure and a large number of component parts, resulting in an increase in manufacturing cost, an increase in weight, and a large size.

This invention was made by focusing on such conventional problems, and a back pressure control valve is defined in the middle of a drain flow path to divide the drain flow path into an upstream side and a downstream side. a chamber that communicates with the chamber; a passage that introduces the pressure of the pressure fluid on the inlet passage side flowing from the control valve into the chamber; a first small chamber through which the upstream and downstream drain passages open the chamber; and the passage. The open ends of the upstream and downstream drain channels are partitioned into a second small chamber which is open, and when pressure fluid is introduced into the second small chamber through the passage, the volume of the second small chamber is elastically deformed to increase the volume of the second small chamber. an elastic member capable of closing the drain passage, and a bypass passage formed outside the drain passage with a diameter smaller than that of the drain passage, and communicating the upstream drain passage and the downstream drain passage. The purpose of the present invention is to provide a power steering valve to solve the above problems.

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

FIG. 4 to FIG. 6 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). An outlet port (not shown) connected to an actuator (not shown) is provided. Further, a plug 32 is screwed onto the member 24.
2 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 (downstream drain passage) formed in the member 24 and a second drain passage 27 (upstream drain passage) formed in the member 24 and the housing body 22a. road) and
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 passes through the housing main body 22a and communicates the upstream side of the control valve 36, for example, an inlet port, with the chamber 26, so that a pressure corresponding to the working pressure of the pressure fluid supplied to the power cylinder as an actuator is supplied to the chamber 26. to be introduced within. Reference numeral 29 denotes a diaphragm as an elastic member made of an elastic body such as rubber, and the periphery of the diaphragm 29 is clamped between the member 24 and the housing main body 22a to divide the chamber 26 into two small chambers 26a and 26b.
It is defined in a liquid-tight manner. This one small chamber 26a
When the hole 28 is opened, the control valve 3 is opened.
The other small chamber 26b is a first small chamber into which the first drain channel 25 and the second drain channel 27 are opened. The member 24 also includes a first drain flow path and a second drain flow path.
A bypass passage 30 having a smaller diameter than both passages 25 and 27 communicating with the drain passage 27 is formed to ensure a minimum passage area between the first drain passage 25 and the second drain passage 27. . These first drain flow path 25 and second drain flow path 27 are the drain flow path 23.
Configure. Note that 31 is a reinforcing member made of a material such as rubber that is fixed to the small chamber 26b side of the diaphragm 29;
is deformed to the right in the figure, the first drain flow path 25
It also has a function as a valve body that closes off the drain flow path 27 and the second drain flow path 27 . These chamber 26, hole 28, diaphragm 29, bypass passage 30, and reinforcing member 31 constitute a back pressure control valve 38.

As is well known, the control valve 22 has a substantially cylindrical valve body 33 that is rotatably housed in a housing main body 22a, and a valve shaft 34 is arranged coaxially with 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. . The end of the valve shaft 34 protruding from the valve housing 22 (the 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 the hollow part. The torsion bar 35 has one enlarged end (the upper end in the figure) connected to the valve shaft 34.
At the same time, the other end (bottom end in the figure) is non-rotatingly connected to a pinion gear (rack-and-pinion type power steering) that meshes with a rack that is connected to the piston of a power cylinder (actuator) not shown. Further, the diameter-reduced intermediate portion thereof is loosely inserted into the hollow portion of the valve shaft 34. 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 inlet port are steered. The valves communicate with each other at an opening degree corresponding to the force, and supply relatively high-pressure fluid to one chamber of the power cylinder. At this time, the other chamber of the power cylinder is drained. Further, 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. and communicate with the drain port. As is well known, the power cylinder has a piston that is easily fixed to the steering wheel and defines two fluid chambers in the cylinder, and pressure is supplied from the control valve 36 in response to steering of the steering wheel. A steering assist force is generated by the pressure difference between the fluid chambers into which fluid flows in or 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 FIGS. 4 and 6, the diaphragm 29 is deformed to the left in the figure, and the first drain flow path 25 and the second drain flow path 27 are connected to the small chamber 26b. The first drain channel 25 communicates with the first drain channel 25 through the
There is a sufficient flow area between the drain flow path and the second drain flow path 27. Therefore, the pressure fluid flowing from the second drain passage 27 flows into the first drain passage 25 via the small chamber 26b, and the bypass passage 3
0 to the first drain flow path 25, and does not apply an excessive load to driving equipment such as a pump that is a pressure fluid supply source.

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. produces steering assistance to 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 communicating with the inlet port through the hole 28 increases, and as shown in FIG. 5, the diaphragm 29 is elastically deformed to the right in the figure to increase the volume of the small chamber 26a. First
The open end of the drain flow path 25 and the open end of the second drain flow path 27 are closed. Therefore, the pressure fluid in the second drain channel 27 flows from the second drain channel 27 through the bypass channel 30 to the first drain channel 25, and is then discharged to the reservoir. As a result, when the steering wheel is operated, the pressure drop that occurs when the pressure fluid passes through the control valve 36 is reduced, no fluid noise is generated, and the interior of the vehicle is kept quiet. . 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, unlike conventional power steering valves, there is no need for the piston 10, plate 7, spring, etc., making it possible to reduce manufacturing costs, and further reduce its weight and number of parts. It becomes possible.

The diaphragm 29 made of an elastic body may be formed as shown in FIG. 7 or 8.
The diaphragm 29 shown in FIG. 7 is provided with a protrusion 29a on the surface on the member 24 side. This protrusion 29a
If the diaphragm 29 is deformed during steering,
At the beginning of this deformation, the projection 29a comes into contact with the member 24 to secure a predetermined flow path area between the first drain flow path 25 and the second drain flow path 27, and then, as the pressure inside the small chamber 26a increases, the protrusion 29a is pressed and deformed, and the first
The drain flow path 25 and the second drain flow path 27 are closed. Therefore, according to this diaphragm 29, it is possible to control the flow area between the first drain flow path 25 and the second drain flow path 27, that is, the pressure of the drain port, to a desired characteristic at the initial stage of steering. It becomes possible.

Further, the diaphragm 29 shown in FIG. 8 has a sealing protrusion 29b formed on its periphery. This protrusion 29b prevents pressure fluid from leaking.

As explained above, according to this invention,
A control valve in which an inlet passage connected to a pressure fluid supply source that generates pressurized pressure fluid, an outlet passage connected to an actuator, and a drain passage that discharges the pressure fluid are connected is housed in a 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 is connected to the inlet flow path side into which the fluid flows 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, the back pressure control valve is defined in the middle of the drain flow path and connects the drain flow path to the upstream side. A chamber that is divided and communicated with the downstream side, a passage that introduces the pressure of the pressure fluid on the inlet flow path side flowing from the control valve into the chamber, and the drain flow paths on the upstream side and the downstream side open the chamber. It is divided into a first small chamber and a second small chamber into which the passage opens, and when pressure fluid is introduced into the second small chamber through the passage, the second small chamber is elastically deformed to increase the volume of the second small chamber, and the upstream side and the downstream side an elastic member capable of closing an open end of the drain flow path; and a bypass passage formed outside the chamber with a smaller diameter than the drain flow path and communicating the upstream drain flow path and the downstream drain flow path. , the elastic member is configured to reduce the flow area of the drain flow path as the operating pressure increases during steering, making it possible to reduce the manufacturing cost of the power steering valve, as well as reducing its weight and number of parts. This has the effect of making it possible to reduce

[Brief explanation of drawings]

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 a power steering valve according to an example, FIGS. 5 and 6 are sectional views showing main parts of the power steering valve shown in FIG. FIG. 7 is a cross-sectional view showing other embodiments of the elastic member of the power steering valve. 21...Power steering valve, 22...
Valve housing, 23...Drain channel, 25...
...First drain flow path (downstream drain flow path), 26
... Chamber, 26a ... Small room (second small room), 26b...
... Small chamber (first small chamber), 27... Second drain flow path (upstream drain flow path), 28... Hole (passage), 2
9...Diaphragm (elastic member), 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 pressurized fluid is installed in the valve housing. The control valve controls the flow of pressure fluid in response to steering of a steering wheel, and a back pressure control valve is provided in the drain flow path, and the back pressure control valve inflows 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 provided in the drain flow path upstream. a chamber that is divided into a side and a downstream side and communicated with each other, a passage that introduces the pressure of pressure fluid on the inlet flow path side flowing from the control valve into the chamber, and a drain flow path that connects the chamber to the upstream side and the downstream side. It is divided into a first small chamber that is open and a second small chamber that is opened by the passage, and when pressure fluid is introduced into the second small chamber through the passage, the second small chamber is elastically deformed to increase the volume of the second small chamber, and the upstream side and the downstream side are an elastic member capable of closing the open end of the side drain flow path; and a bypass formed outside the chamber to have a smaller diameter than the drain flow path and communicating the upstream drain flow path and the downstream drain flow path. A passage and
A power steering valve characterized by being equipped with.