JPH03200416A - Pressure controller of suspension - Google Patents

Abstract

PURPOSE:To simplify adjustment of a vehicle height by providing a needle valve for regulating flow degree of a flow port between a target pressure space and a low pressure pipe on a pressure control valve for controlling pressure to be supplied to/exhausted from a shock absorber and controlling the needle valve with a driving means. CONSTITUTION:In an apparatus wherein a vehicle height is adjusted by controlling pressure supplied to/exhausted from a shock absorber of a suspension provided on each wheel by a pressure control valve 80, a valve body of the pressure control valve 80 is formed with a line pressure port 82, a low pressure port 85, an output port 84, a high pressure port 87 and a low pressure port 89. A spool 90 which is driven with pressure of the output port 84 and a target pressure space 88 received on both ends is inserted into the valve body as well as a needle valve 95 whose tip is facing a flow port 94 between the target pressure space 88 and the low pressure port 89 and which regulates the flow degree is provided. The needle valve 95 is moved and guided by a valve supporting material 95G and drive-controlled by a driving means including an electric coil 99.

Description

DETAILED DESCRIPTION OF THE INVENTION OBJECTS OF THE INVENTION (Field of Industrial Application) The present invention relates to pressure control of vehicle suspensions, and in particular:
The present invention relates to a device for controlling suspension pressure so as to suppress changes in vehicle body posture due to changes in vehicle driving conditions, etc.

(Prior Art) For example, a pressure control valve disclosed in Japanese Unexamined Patent Publication No. 1-12717 has a line pressure port communicating with a high pressure pipe.

Low pressure port communicating with fluid return line to reservoir.

An output port that applies pressure to the suspension, a target pressure space that communicates with the line pressure port via an orifice, and a low pressure port that receives the pressure of the output port at one end and uses this pressure to lower the degree of flow between the line pressure port and the output port. The pressure in the target pressure space is received at the other end, and this pressure increases the flow rate between the line pressure port and the output port, thereby increasing the flow rate between the low pressure port and the output port. A spool that is driven in a direction that lowers the flow rate.

It has a needle valve that defines the degree of flow between the target pressure space and the fluid return pipeline to the reservoir, and a solenoid that drives the needle valve in a direction to increase or decrease the degree of flow. By controlling the energization current, the balancing force of the needle valve is determined, a corresponding required pressure is created in the target pressure space, and a pressure substantially equal to the pressure in the target pressure space is applied to the output port (suspension).

(Problem to be Solved by the Invention) By the way, the pressure in the target pressure space (target pressure) can be set by adjusting the degree of communication with the fluid return pipeline to the reservoir (hereinafter referred to as return pipeline) using a needle valve. However, in a pressure control valve that applies this pressure to one end of the spool and applies the pressure of the output port to the other end of the spool to output a pressure corresponding to the target pressure, for example, when the axle rides on a protrusion on the road surface, the suspension pressure increases. As a result, the pressure at the output port of the pressure control valve increases rapidly, and the spool moves in the direction of contracting the target pressure space (lowering the pressure at the output port), causing the pressure in the target pressure space to increase. Pressure increases. This pressure acts on the needle valve, and the needle valve is pushed in a direction that increases the degree of communication between the target pressure space and the return pipe (in a direction that lowers the pressure in the target pressure space). Due to this push, the needle valve moves (retreats) in that direction, the target pressure space communicates with the return pipe, and the pressure in the target pressure space decreases.This causes the spool to move in the direction of contracting the target pressure space, and this movement of the spool As a result, the output port communicates with the low pressure port, the pressure at the output port (suspension pressure) decreases, and an increase in suspension pressure due to the thrust of the high shaft is suppressed.

By the way, when the line pressure is less than the target pressure, the needle valve is completely closed to cut off the target pressure space and the return pipe. In this state, when the suspension pressure becomes higher than the target pressure due to the axle being pushed up by the road surface, a force acts on the spool in the direction of communicating the output port with the return pipe, and (a) the pressure in the target pressure space increases and flows back into the line pressure oil passage, increasing line pressure. When this progresses and the pressure in the target pressure space becomes higher than the target pressure, the needle valve is pushed in the opening direction by this pressure and opens, (b) the pressure in the target pressure space flows to the return pipe, and the pressure in the target pressure space and line pressure drops rapidly. This gradual pressure drop causes the spool to rapidly move in the direction of communicating the output port with the return pipe, causing the pressure at the output port to drop rapidly. Due to the sudden drop in the pressure in the target pressure space, the pressure in the target pressure space becomes less than the target pressure, the needle valve closes completely, and the spool moves in the direction of communicating the output port with the line pressure port, causing the above (a).
Return to state. In this way, the above (a) and (b) are repeated, and pressure vibrations occur in the line pressure oil passage and the output port (suspension communication).

Since the spool also vibrates, these factors combine to increase pressure vibration.

(Means for Solving the Problems) The pressure control device of the present invention supplies fluid at high pressure to a high pressure pipe (6) for supplying pressure fluid to a suspension (100 fr) that expands and contracts according to the supplied pressure. and a line pressure port (82) communicating with the high pressure pipe (6), a low pressure port (85) communicating with the low pressure pipe (11), and an output port that provides pressure to the suspension (100 fr). (84), a target pressure space (88) communicating with the line pressure port (87), which receives the pressure of the output port (84) at one end and uses this pressure to connect the line pressure port (82).
) and the output port (84) to reduce the flow rate between the low pressure port (
85) and the output port (84), the pressure of the target pressure space (88) is received at the other end, and this pressure causes the line pressure port (82) and the output port (84) to be increased.
A spool (90) that is driven in a direction to increase the flow rate of 84) and lower the flow rate of the low pressure port (85) and output port (84), the target pressure space (88) and the low pressure pipe line (11).
The tip faces the communication port (94) between the two and is movable in the opposite direction, and the optimum temperature between the target pressure space (88) and the low pressure pipe line (11) is maintained by the communication port (94). a valve support member (95G) that guides the needle valve (95) in a movable manner in the opposite directions; Drive means (96, 97, 98a, 98
b, 99), and a pressure control valve device (80fr) having a small opening communication means (95r or 94a) for releasing a part of the pressure in the target pressure space (88) to the low pressure pipe (11);
Equipped with. Note that the symbols in parentheses are attached to corresponding elements in the embodiments described later.

(Function) Electrically energized drive means (96, 97, 98a, 98b
, 99) drives the needle valve (95) to a certain position, the appropriate temperature defined at the communication port between the target pressure space (88) and the low pressure pipe (11) and the tip of the needle valve (95) but,
The pressure in the target pressure space (88) corresponds to the position of the needle valve (95), and the pressure in balance with this pressure is the pressure in the pressure control valve device (80fr).
) appears at the output port (84) of (suspension L
join OOfr). Drive means (96, 97, 98a,
When 98b, 99) drive the two dollar valve (95) in the direction of increasing the flow rate, the pressure in the target pressure space decreases, the pressure in the suspension (100fr) decreases, and the vehicle height decreases), resulting in an appropriate temperature. When the vehicle is driven in the direction of lowering the pressure, the pressure in the target pressure space increases and the pressure in the suspension (100 fr) increases (the vehicle height increases). Therefore, the driving means (
By changing the position of the needle valve (95) at 96°97, 98a, 98b, 99), the vehicle height can be adjusted high or low.

When the needle valve is set at a certain position (the target pressure is set at a certain value), (A) When the wheel rides on a convex part of the road surface, the wheel pushes up from the road surface and the suspension pressure increases. .

Then, the output capo of the pressure control valve device (80fr) - (8
4) The pressure increases and the spool (90) moves in the pressure decreasing direction (increasing the appropriate temperature of the output port 84 and low pressure port 85, and lowering the appropriate temperature of the output port 84 and high pressure port 85).
Move to.

This buffers the propagation of the wheel thrust impact to the vehicle body. Due to this movement of the spool (90), the pressure in the target pressure space (88) increases, and this pressure is applied to the tip of the needle valve (95) through the communication port (94), causing the needle valve (95) to retreat. , the appropriate temperature of the flow port (94) becomes higher.

That is, the appropriate temperature from the target pressure space (88) to the low pressure pipe (11) increases, and the pressure in the target pressure space (88) decreases.

(B) When the axle lifts up, the suspension pressure decreases, so the spool (90) moves in the pressure increasing direction (output port 8
4 and the low pressure port 85, and lower the appropriate temperature of the output port 84.
(to increase the appropriate temperature of the high pressure port 85).

This movement of the spool (90) lowers the pressure in the target pressure space, and a force acts on the needle valve (95) in the direction of lowering the appropriate temperature of the flow port (94).
88) and the low-pressure pipe line (11) become lower, increasing the pressure in the target pressure space (88).

When the wheel falls into a concave part of the road surface, the suspension pressure decreases and the pressure control valve device (80fr) performs the operation (B) above, and when the axle goes over the concave part, it performs the operation (A) above.

Due to this operation of the pressure control valve device (80fr),
When driving on a rough road where the axle runs over a convex part or falls into a concave part, the needle valve (95) adjusts the pressure in the target pressure space to the electrically energized driving means (96, 97, 98a, 98b, 9
The spool (90) operates to maintain a constant pressure corresponding to the position determined by the output port (9), and the spool (90) operates to maintain a constant pressure corresponding to the position determined by the output port (8).
4. Since the suspension operates to maintain a constant pressure (suspension pressure), the vertical vibration of the vehicle body due to the vertical vibration of the wheels is buffered.

Thus, when the line pressure is relatively low and less than the target pressure, the needle valve (95) closes the opening (94). At this time, when the wheel thrusts up and the suspension pressure increases rapidly, the spool (90) moves in the direction of contracting the target pressure space (88), and the needle valve (95)
Although the opening (94) is closed, the fluid in the target pressure space (88) escapes to the low pressure pipe (89-11) via the flow means (95r or 94a). This allows the spool (90
) The pressure increase in the target pressure space (88) due to the movement of the target pressure space (88) is gradual and the increase value is small, and since line pressure is added, pressure fluctuations are small.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

(Example) FIG. 1 shows an outline of the mechanism of a vehicle body support device. The hydraulic pump 1 is a radial pump, which is disposed in the engine room, is driven to rotate by the vehicle engine (not shown), sucks oil from the reservoir 2, and pumps it to the high pressure port 3 at a rotational speed higher than a predetermined speed. Discharges oil at a predetermined flow rate.

High pressure port 3 of radial pump for suspension pressure supply
A pulsation absorbing attenuator 4° main check valve 50 and a relief valve 60 are connected to the high pressure port 3 through the main check valve 50.
high pressure oil is supplied to the high pressure supply pipe 8.

The main check valve 50 prevents oil from flowing back from the high pressure supply pipe 8 to the high pressure port 3 when the pressure in the high pressure port 3 is lower than the pressure in the high pressure supply pipe 8.

The relief valve 60m connects the high pressure port 3 to the reservoir return pipe 11, which is one of the return oil passages to the reservoir 2, when the pressure in the high pressure port 3 exceeds a predetermined pressure.
The pressure in the high pressure port 3 is maintained at a substantially constant pressure.

The high pressure feed pipe 8 has a front axle suspension of 100 fL.

a front wheel high pressure supply pipe 6 for supplying high pressure to the 100fr;
A rear wheel high pressure supply pipe 9 for supplying high pressure to the rear wheel suspensions 100r L and 100rr communicates with each other, the front wheel high pressure supply pipe 6 is connected to an accumulator 7 (for front wheels), and the rear wheel high pressure supply pipe 9 is connected to an accumulator 7 (for front wheels). 10 (for 11n) is communicating.

A pressure control valve 80fr is connected to the front wheel high pressure supply pipe 6 via an oil filter.
However, the pressure in the front wheel high pressure supply pipe 6 (hereinafter referred to as front wheel line pressure) is adjusted (III pressure) to the required pressure (pressure crab suspension support pressure corresponding to the energizing current value of the electric coil) and the cut valve 70fr and the relief are adjusted. Give to valve 60fr.

When the pressure of the front wheel high pressure supply pipe 6 (front axle side line pressure) is less than a predetermined low pressure, the cut valve 70fr closes the pressure control valve 80fr.
(to the suspension) and the hollow piston rod 102fr of the shock absorber 101fr of the suspension 100fr.
The pressure control valve 80fr is prevented from leaking from the front wheel side line pressure to the pressure control valve 80fr while the front wheel side line pressure is above a predetermined low pressure.
The output pressure (suspension support pressure) is directly supplied to the piston rod 102fr.

Relief valve 60fr is shock absorber 101
Limit the internal pressure of fr to below the upper limit. That is, when the pressure (suspension support pressure) at the output port 84 of the pressure control valve 80fr exceeds a predetermined high pressure, the output port 84 is made to flow through the reservoir return pipe 11, and the pressure control valve 80fr
maintains the pressure at the output port substantially below a predetermined high pressure.

The relief valve 60fr further operates as a pressure control valve 80 when the front right wheel is thrust up from the road surface and the internal pressure of the shock absorber 101fr rises impulsively.
When the internal pressure of the shock absorber 101fr rises impulsively, the internal pressure of the shock absorber 101fr is transferred to the piston rod 100f.
r and the reservoir return pipe 1 through the cut valve.
Release to 1.

Suspension 100fr roughly consists of shock absorber 101fr and suspension coil spring 119fr.
Output port 8 of pressure control valve 80fr
4 and the pressure supplied into the shock absorber 101fr via the piston rod 102fr (pressure control valve 8
The vehicle body is supported at a height (relative to the front right axle) corresponding to the pressure crab suspension support pressure regulated at 0fr.

The support pressure given to the shock absorber 101fr is
It is detected by the pressure sensor 13fr, and the pressure sensor 13fr generates an analog signal indicating the detected support pressure.

A vehicle height sensor 15fr is attached to the vehicle body near the suspension 100fr, and a link connected to the rotor of the axle sensor 15fr is connected to the front right wheel. The vehicle height sensor 15fr generates an electric signal (digital data) indicating the vehicle height of the front right axle (height of the vehicle body relative to the axle).
occurs.

Pressure control valve 80f L-cut valve 7 similar to the above
0fL - Relief valve 60fL, vehicle height sensor 15f
Similarly, a pressure sensor 13fL is assigned to the front left axle suspension 100fL, and a pressure control valve 80fL is connected to the front wheel high pressure supply pipe 6 to maintain the required pressure (support pressure). The suspension 100f
The L shock absorber 101f is applied to the L piston rod 102f.

Pressure control valve 80rr, cut valve 7 similar to the above
0rr l Relief valve 60rr, vehicle height sensor 1
Similarly, a pressure sensor 13rr and a pressure sensor 13rr are assigned to the rear right wheel suspension 100rr, and a pressure control valve 80rr is connected to the rear wheel high pressure supply pipe 9 to apply the required pressure (support pressure) to the suspension 100rr
Piston rod 10 of shock absorber 101rr
Give to 2rr.

Furthermore, the same pressure control valve 80r L, cut valve 70r, relief valve 60r + vehicle height sensor 1 as above
Similarly, a pressure sensor 13rL and a pressure sensor 13rL are assigned to the front left axle suspension 100rL, and a pressure control valve 80rL is connected to the rear wheel high-pressure supply pipe 9.
is connected to apply a required pressure (support pressure) to the piston rod 102rL of the shock absorber 101rL of the suspension 100rL.

In this example, the engine is installed on the front wheel side.
Along with this, the hydraulic pump 1 is moved to the front shaft side (engine room).
is equipped with, from hydraulic pump 1 to rear wheel suspension 1.
00rr, 100r The piping length from the hydraulic pump 1 to the front wheel suspension is 100fr.

It is longer than the piping length up to 100fL. Therefore, the pressure drop due to the piping is large on the rear wheel side, and if an oil leak or the like occurs in the piping, the pressure drop on the rear wheel side is the largest. Therefore, a pressure sensor 13rm for detecting line pressure is connected to the rear wheel high-pressure supply pipe 9.

On the other hand, the pressure in the reservoir return pipe 11 is lowest at the end on the reservoir 2 side, and the pressure tends to increase as the distance from the reservoir 2 increases. Therefore, the pressure in the reservoir return pipe 11 is also on the rear wheel side, and the pressure sensor 13rt I'm trying to detect it.

A bypass valve 120 is connected to the rear wheel high pressure supply pipe 9. This bypass valve 120 regulates the pressure of the high-pressure supply pipe 8 to a pressure corresponding to the current value of the electric coil (obtains the required line pressure). Also, the ignition switch is opened (engine stops: pump 1 stops)
When this occurs, the line pressure is reduced to substantially zero (atmospheric pressure in the reservoir 2 through the reservoir return pipe 11).
L.

70rr and 70rL are turned off to prevent pressure loss in the shock absorber), and lighten the load when restarting the engine (pump 1).

FIG. 2 shows an enlarged longitudinal section of the suspension 100fr. Shock absorber 101fr piston rod 1
A piston 103 fixed to the 02fr roughly divides the inside of the inner cylinder 104 into an upper chamber 105 and a lower chamber 106.

Suspension support pressure (hydraulic pressure) is supplied to the piston rod 102fr from the output port of the cut valve 70fr, and this pressure is applied to the side port 10 of the piston rod 102fr.
7 into the upper chamber 105 in the inner cylinder 104, and further through the upper and lower through holes 108 of the piston 103 into the lower chamber 10.
Join 6. A support pressure proportional to the product of this pressure and the cross-sectional area of the piston rod 102fr (rod radius squared x π) is applied to the piston rod 102fr.

The lower chamber 106 of the inner cylinder 104 communicates with the upper space 110 of the damping valve device 109 . The space above the damping valve device 109 is
It is divided into a lower chamber 112 and an upper chamber 113 by a piston 111, and oil in an upper space 110 flows through the lower chamber 112 through a damping valve device 109, while high pressure gas is sealed in the upper chamber 113.

When the piston rod 102fr tries to relatively rapidly enter the lower part of the inner cylinder 104 due to the thrust upward movement of the front right axle, the internal pressure of the inner cylinder 104 suddenly increases, and the pressure in the upper space 11.0 similarly increases. The pressure will suddenly become higher than the pressure in the lower chamber 112. At this time, the oil flows into the upper space 112 through the check valve of the damping valve device 109 that allows the oil to flow from the upper space 110 to the lower chamber 112 at a predetermined pressure difference or higher, but blocks the flow in the opposite direction. flows into the lower chamber 112, which causes the piston 111 to rise and the impact (upward) applied from the axle to the lower chamber 112.
propagation to the piston rod 102fr. That is, the propagation of the axle impact (ball thrust) to the vehicle body is buffered.

When the piston rod 102fr relatively tries to come out above the inner cylinder 104 due to the sudden fall of the front right wheel, the internal pressure of the inner cylinder 104 suddenly decreases and the upper space 1
10 is about to suddenly become lower than the pressure in the lower chamber 112. At this time, the damping valve device 109.

Oil flows from the lower chamber 112 to the upper space 11O through a check valve that allows oil to flow from the lower chamber 112 to the upper space 110 at a predetermined pressure difference or higher, but prevents flow in the opposite direction. The piston 111 descends, and the impact applied from the axle (
(downward direction) to the piston rod 102fr. In other words, the axle technique for the car body! The propagation of (downturn) will be buffered.

In addition, shock absorber 101 is used to raise the vehicle height, etc.
As the pressure applied to fr increases, the lower chamber 112
The pressure increases, the piston 111 rises, and the piston 111 reaches a position corresponding to the vehicle body load.

Piston rod 102 against inner cylinder 104, such as when parked
When there is no relative vertical movement of fr, the seal between the inner cylinder 104 and the piston rod 202fr allows the inner cylinder 10
4, there is virtually no oil leakage into the outer cylinder 114. However, in order to reduce the vertical movement load on the piston rod 102fr, the seal is designed to have sealing characteristics that cause a slight oil leak when the piston rod 102fr moves up and down. The oil leaking into the outer cylinder 114 passes through the outer cylinder 114 and through the drain 14fr (Fig. 1) which is released to the atmosphere.

Drain return pipe 12 (first return pipe), which is the second return pipe
(Fig.) and is returned to the reservoir 2. The reservoir 2 is equipped with a level sensor 28 (FIG. 1), and when the oil level in the reservoir 2 is below the lower limit, the level sensor 28 generates a signal (oil shortage signal) indicating this.

The structures of the other suspensions 100f L, 100rr and 100r L are also the same as those of the suspension 100 described above.
The structure is substantially similar to that of fr.

FIG. 3a shows an enlarged longitudinal section of the pressure control valve 80fr.

A spool storage hole is bored in the center of the sleeve 81, and a line pressure port 8 is provided on the inner surface of the spool storage hole.
A ring-shaped groove 83 through which the low-pressure port 85 communicates and a ring-shaped groove 86 through which the low-pressure port 85 communicates are formed. An output port 84 is opened between these ring-shaped grooves 83 and 86. The spool 90 inserted into the spool storage hole has a ring-shaped groove 91 having a width corresponding to the distance between the right edge of the groove 83 and the left edge of the groove 86 in the middle of its side circumferential surface. A valve housing hole is formed in the left end of the spool 90, and this valve housing hole communicates with the groove 91. The valve storage 6 has
A valve body 93 pushed by a compression coil spring 92 is inserted.

This valve body 93 has a through orifice at its center, and the space of the groove 91 (output port 84) communicates with the space in which the valve body 93 and the compression coil spring 92 are accommodated. Therefore, the spool 90 receives the pressure of the output port 84 (regulated pressure, the pressure on the suspension 100fr) at its left end, and thereby receives a force that drives it to the right. Note that when the pressure of the output port 84 becomes shockingly high, the valve body 93 moves to the left against the pushing force of the compression coil spring 92, creating a buffer space at the right end of the valve body 93. , when the output port 84 rises impulsively, this impulsive rising pressure is not immediately applied to the left end face of the spool 90, and the valve body 93 responds to the impulsive pressure rise of the output port 84. , has the effect of buffering the rightward movement of the spool 90. And vice versa,
This has the effect of buffering the leftward movement of the spool 90 against an impactful pressure drop at the output port 84.

The pressure of the target pressure space 88 communicating with the high pressure port 87 via the orifice 88f is applied to the right end surface of the spool 90, and due to this pressure, the spool 90 receives a force that drives it to the left. Line pressure is supplied to the high pressure port 87, but the target pressure space 88 communicates with the low pressure port 89 through the communication port 94, and the communication opening degree of the communication port 94 is determined by
determined by needle valve 95. When the two dollar valve 95 closes the communication port 94, the pressure in the target pressure space 88 communicating with the high pressure port 87 via the orifice 88f is
7 pressure (line pressure), the spool 90 is driven to the left, and as a result, the groove 91 of the spool 90 becomes the groove 83 (
line pressure port 82), and communicates with the groove 91 (output port 82).
4) pressure increases and this is transmitted to the left side of the valve body 93,
A rightward driving force is applied to the left end of the spool 90. When the needle valve 95 fully opens the communication port 94, the target pressure space 8
8 is throttled by the orifice 88f, so it is significantly lower than the pressure (line pressure) of the high pressure port 87, and the spool 90 moves to the right.
The groove 91 communicates with the groove 86 (low pressure port 85), and the groove 91
The pressure at the output port 84 decreases, which is transmitted to the left side of the valve body 93, and the rightward driving force at the left end of the spool 90 decreases. In this way, the spool 90 is connected to the target pressure space 80.
This is the position where the pressure of the output port 84 and the pressure of the output port 84 are balanced. That is, a pressure substantially proportional to the pressure in target pressure space 88 appears at output port 84 .

The pressure in the target pressure space 88 is determined by the position of the needle valve 95.
is substantially inversely proportional to the distance between the output ports 84 and 84.
At , a pressure appears that is substantially inversely proportional to the distance of the needle valve 95.

The needle valve 95 passes through a fixed core 96 of magnetic material. The right end of the fixed core 96 is in the shape of a truncated cone, and the end face of the magnetic plunger 97 in the shape of a conical hole with a bottom is opposed to this right end face. A needle valve 95 is fixed to this plunger 97. The fixed core 96 and plunger 97 are
It enters inside the bobbin around which the electric coil 99 is wound.

When the electric coil 99 is energized, magnetic flux flows through the loop of the fixed core 96 - magnetic yoke 98a - magnetic end plate 98b - plunger 97 - fixed core 96, and the plunger 97 is attracted to the fixed core 96 and moves to the left. However, when the needle valve 95 approaches the flow path 94 (the distance becomes shorter),
The left end of the needle valve 95 receives the pressure of the target pressure space 88 as the right driving force, and the right end of the needle valve 95 is at atmospheric pressure through the low pressure port 98c that is released to the atmosphere. As a result, the needle valve 95 receives a rightward driving force corresponding to the pressure value (this corresponds to the position of the needle valve 95), and as a result, the needle valve 95 moves toward the flow port 94.
The distance is substantially inversely proportional to the value of the current flowing through the electric coil 99. In order to make the relationship between current value and distance linear, one of the fixed core and the plunger is shaped like a truncated cone, and the other one is shaped like a conical hole with a corresponding bottom, as described above.

As a result of the above, a pressure substantially proportional to the current value flowing through the electric coil 99 appears at the output port 84 .

This pressure control valve 80fr is operated when the current applied is within a predetermined range.
A pressure proportional to the pressure is outputted to the output port 84.

By changing the value of the current flowing through the electric coil 99, the vehicle height can be adjusted higher or lower.

When the energizing current value is set to a certain value, that is, when the energizing current value of the electric coil is set to apply pressure to the suspension to maintain the vehicle height at a certain value, the axle may ride up on a convex part of the road surface. The wheels rise up from the road surface, and (A) the suspension 100fr pressure increases. Then, the pressure at the output port 84 of the pressure control valve 80fr increases, and the spool 90 moves in the pressure decreasing direction (to the right in FIG. 3a). This buffers the propagation of the wheel thrust impact to the vehicle body. This movement of the spool 90 increases the pressure in the target pressure space 88 and applies this pressure to the tip of the needle valve 95 through the communication port 94.
moves backward (moves to the right), and the degree of flow through the flow port 94 increases. That is, the degree of flow from the target pressure space 88 to the return pipe 11 through the orifice 88f and the low pressure port 87 increases, and the pressure in the target pressure space 88 decreases. When the axle is pushed up, (B) the suspension pressure decreases, so the spool 90 moves in the pressure increasing direction (leftward in FIG. 3a). This movement of the spool (90) lowers the pressure in the target pressure space 88, and a force acts on the needle valve 95 in a direction (to the left) that lowers the degree of flow in the flow port 94, thereby reducing the pressure in the target pressure space 88. The degree of communication with the return pipe 11 decreases, and the pressure in the target pressure space 88 increases.

When the axle falls into a concave part of the road surface, the suspension pressure decreases and the pressure control valve 80fr performs the operation described in (B) above, and when the axle goes over the concave part, it operates as described in (A) above.
Perform the following actions.

Due to this operation of the pressure control valve 80fr, the needle valve 95 adjusts the pressure in the target pressure space 88 to the electric coil 9 when driving on a rough road where the axle rides on a convex part or falls into a concave part.
It operates to maintain the pressure determined by the current value of 9,
In addition, the spool 90 operates to maintain the pressure at the output port 84 (suspension pressure) at a constant pressure despite fluctuations in suspension pressure due to vertical movement of the wheels, so vertical vibration of the vehicle body due to vertical vibration of the axle is reduced. Buffered.

FIG. 3b shows an enlarged cross section of the needle valve 95 taken along line IIIB-I [[[B] in FIG. 3a. Referring to FIGS. 3a and 3b, a pressure wave groove 95r is carved in the conical tapered surface at the tip of the needle valve 95, extending from the apex of the conical tapered surface to the cylindrical surface at the end of the tapered surface. ,
This pressure wave allows pressure to escape from the target pressure space 88 to the low pressure port 89 when the one-conical tapered surface of the groove 95r is in complete contact with the opening 94.

When the conical tapered surface at the tip of the needle valve 95 is away from the opening 94, the flow rate of this pressure wave between the target pressure space 88 and the low pressure port 89 due to the groove 95r is such that the conical tapered surface is separated from the opening 94. Since the flow rate is extremely small compared to the flow rate, it does not make a particular contribution to determining the pressure in the target pressure space 88. However, when the conical tapered surface of the needle valve 95 is very close to the edge of the opening 94, the contribution is large, and especially when the conical tapered surface is close to the edge of the opening 95, the low pressure port from the target pressure space 88 89
The fluid is drained only through this groove 95r.

When the line pressure is higher than the pressure in the target pressure space 88 (target pressure), the conical tapered surface of the needle valve 95 is separated (retracted) from the edge of the opening 94, and the pressure in the output port 84 increases due to the increase in suspension pressure. rises and spool 84
moves to the right and the pressure in the target pressure space 88 increases, and in conjunction with this, the needle valve 95 moves further away from the opening 94. Since this movement of the needle valve is linear, it does not cause a sudden pressure change in the pressure in the target pressure space 88.

However, when the line pressure is lower than the target pressure, the pressure at the output port 84 is lower than the target pressure, so the needle valve 95 moves to the left to further increase the pressure at the output port 84, and its conical taper surface is in close contact with the edge of the opening 94. In this state, if the suspension pressure (pressure at the output port 84) suddenly increases due to a wheel running onto a convex part of the road surface, the spool 80 moves to the right and the pressure in the target pressure space 88 increases rapidly.

If the pressure wave does not have the groove 95r, the target pressure space 88
Target pressure space 8 where the pressure rise rate is high and the pressure value is high.
This pressure increase at 8 propagates to line pressure port 82 through orifice 88f. On the other hand, due to a sudden increase in the pressure in the target pressure space, the needle valve 95 suddenly (impulsively) moves to the right when the suspension pressure exceeds the target pressure.
Sudden (impulsive = binary) in the target pressure space 88
This creates a pressure fluctuation (drop) that propagates to line pressure port 82 through orifice 88f. Due to the sudden pressure drop in the target pressure space 88, the target pressure space 88 suddenly moves to the right, and as a result, the output port 84 communicates with the low pressure port 85, and the pressure in the output port 84 suddenly and excessively drops. This causes spool 9
0 is now moved to the left, and accordingly, the needle valve 95 is moved to the left so that its conical tapered surface comes into close contact with the edge of the opening 94. As the spool 90 moves to the left, the output port 84 is cut off from the low pressure port 85, and the pressure in the output port 84 increases rapidly due to suspension pressure. Thereafter, as a result of such repetition, the needle valve 95 and the spool 90 move left and right, and the pressure in the line pressure port 82 (line pressure) vibrates due to the pressure vibration in the target pressure space 88. FIG. 9 shows the relationship between such suspension pressure and line pressure. Cut valve 70f where the lower peak of the pressure (line pressure) of line pressure port 82 is less than the cutoff pressure of cut valve 70fr
r will also undergo closing/opening vibration.

However, in this embodiment, since the pressure wave has the groove 95r, the spool 90 moves to the right at a slow rising speed, and as a result, the pressure in the output port 84 (suspension) is released to the low pressure port 85, and the spool 90 smoothly returns to the target pressure. It moves to a position where the pressure in the space and the pressure at the output port are balanced, and there is virtually no overshoot. As a result, the pressure fluctuations in the output port 84 are small, and the line pressure fluctuations are also small, so the cut valve 70fr does not open and close. FIG. 8 shows the relationship between suspension pressure and line pressure.

In the above embodiment, a groove 95r is formed as a communication means in the conical tapered surface at the tip of the needle valve 95, but this is used to communicate between the target pressure space 88 and the low pressure port 89 through a small opening. An example of this, which may be a fixed small channel, is shown in FIG. 3c.

In the embodiment shown in FIG. 3c, a small opening 94a connecting the target pressure space 88 and the low pressure port 89 is opened in parallel with the opening 94. In this embodiment as well, the same operation and effect as in the case of using the groove 95r described above can be obtained.

FIG. 4 shows an enlarged longitudinal section of the cut valve 70fr.

A line pressure port 72. is provided in the valve storage hole drilled in the valve base 7I. Pressure adjustment capo door 3. The oil drain port 74 and the output port door 5 are in communication. Line pressure port 7
2 and the pressure regulation input port door 3 is a ring-shaped first guide 7.
6, and the pressure regulating input port door 3 and output port door 5 are separated by a cylindrical guide 77a having a circular flow lower portion 7ao at the center. The oil drain port 74 is the second
It communicates with a ring-shaped groove on the outer periphery of the guide 77c, and returns oil leaked to the outer periphery of the second guides 77a, 77b, and 77c to the return pipe 11.

A spool 78 pushed leftward by a compression coil spring 79 passes through the first and second guides 76, 77a to 77c. The left end head of the spool 78 passes through a backup ring 76b in an airtight manner. The backup ring 76b passes through the O-ring 76o and is inserted into the valve guide opening of the second guide 76 together with the O-ring 760. 0
A ring 76o provides a seal between the backup ring 76b and the second guide 76. The space on the left side of the left end of the spool 78 in the valve guide opening of the second guide 76 is the control pressure chamber 7.
2a, and communicates with the line pressure port 72 through a groove carved in the left end surface of the second guide 76. Therefore, the pressure of the line pressure port 72 is applied to the left end surface of the spool 78.

The surface of the spool 78 that faces the opening lower portion 7ao of the second guide 77a is a spherical surface 78a, and when the spool 78 moves to the left, this spherical surface 78a closes the opening lower portion 7ao, as shown in FIG. As a result, the input port door 3a and the output port door 5 are cut off.

The second guide 77c has a central protrusion 77dp having a guide hole 77dh for receiving the tail end of the spool 78, a flow lower part 7ds that allows fluid to flow between the inner space of the second guide 77b and the output port door 5, and an oxygen 77dr. Guide hole 77
The bottom of c communicates with the oil drain port 74 through a side port.

A leg of the spool 78 is inserted into this guide hole 77c, and an O-ring 77dO attached to this leg seals between the leg and the inner wall surface of the guide hole 77c, so that the fluid in the second guide 77b is This prevents the oil from flowing out through the guide hole 77dh to the drain port 77dh that communicates with the return pipe 11.

When the line pressure is less than a predetermined low pressure, the spool 78 is driven to the leftmost side by the repulsive force of the compression coil spring 79, as shown in FIG. The spherical surface 78a is the second guide 77
It is blocked by fully closing the lower part 7ao between the circles of a. When the line pressure exceeds a predetermined low pressure, this pressure begins to drive the spool 79 to the right against the repulsive force of the compression coil spring 79, and at a pressure higher than the predetermined low pressure, the spool 79 is positioned at the rightmost position (fully opened). . That is, the spherical surface (78a) of the spool 78 is the second guide 77a.
When the pressure regulating input port door 3 communicates with the output port door 5 and the line pressure (line pressure port 72) rises to a predetermined low pressure, the cut valve 70 moves to the right from the circular lower part 7ao.
fr is the pressure regulation input port door 3 (pressure regulation output of the pressure control valve 80fr) and the output port door 5 (shock absorber 101).
fr), and when the line pressure (port 72) further increases, the pressure regulating input port door 3 (pressure control valve 80
The area between the output port door 5 (shock absorber 101fr) and the output port door 5 (shock absorber 101fr) is fully opened.

When the line pressure decreases, the opposite is true, and when the line pressure falls below a predetermined low pressure, the output port door 5 (shock absorber 101fr) is completely cut off from the pressure regulation input port door 3 (pressure regulation output of the pressure control valve 80fr). Ru. That is, the pressure in the control pressure port 72 decreases, and the force of the compression coil spring 79 causes the spool 78 to move to the left (
When the spool 78 is driven in the blocking direction), the spherical surface 78a of the spool 78
is in contact with the opening edge of the lower circular portion 7ao of the second guide 77a. At this time, the spherical surface 78a hits the circular edge of the inter-circular lower 7ao, and since the spherical surface 78a is inclined from a position far from the opening lower 7ao to a point close to the opening lower 7aO, the entire circumference of the spherical surface 78a is initially opened. If it does not contact the entire circumference of the edge, the contact area will cause the spool 78 to move (left and right).
A force acts to align the fineness of the direction with the center of the opening lower 7ao,
This is connected to the backup ring 76b via the spool 78.
and 0-ring 760. Since the O-ring 76o is elastic, the portions to which this force is applied contract and the other portions expand, allowing the spool 78 to be displaced in the direction in which the force is applied while maintaining sealing performance. As a result, the entire circumference of the spherical surface 78a comes into close contact with the opening of the inter-circular lower portion 7ao, and the input port door 3 and the output port door 5 are completely cut off. Since the backup ring 76b is displaced together with the spool 78, the sliding resistance between the backup ring 76b and the spool 78 does not substantially change, so the movement of the spool 78 is smooth.

FIG. 5 shows an enlarged longitudinal section of the relief valve 60fr. An input port 2 and a low pressure port 63 are opened in the valve housing hole of the valve base 61. A cylindrical first guide 64 and a second guide 67 are inserted into the valve storage hole, and the input port 2 communicates with the inner space of the first guide 64 through the filter 65. A valve body 66 having an orifice in the center is inserted into the first guide 64, and the valve body 66 is pushed to the left by a compression coil spring 66a. The space in the first guide 64 that accommodates the valve body 66 and the compression coil spring 66a is
It communicates with the input port 2 through the orifice of the spring seat 66b, and also communicates with the second guide 6 through the opening of the spring seat 66b.
It communicates with the inner space of 7. The conical valve body 68 is pushed to the left by the repulsive force of the compression coil spring 69, and the spring seat 6
6b (77 the opening is closed. When the pressure (control pressure) of the input port 2 is less than a predetermined high pressure, the pressure in the storage space of the coil spring 66a, which communicates with the input port 2 through the orifice of the valve body 66, Since the repulsive force of the spring 69 is relatively lower than that of the spring 69, the valve body 68 closes the center opening of the valve seat 66b, as shown in FIG.
The inner space of the second guide 67, which communicates with the inner space through the hole 67a, is cut off from the inner space of the second guide 67. That is, the output port 2 is cut off from the low pressure port 63.

When the pressure (control pressure) of the input port 2 rises to a predetermined high pressure, this pressure passes through the orifice of the valve body 66 and reaches the valve seat 66.
b, the valve body 68 begins to be driven to the right by this pressure, and when the pressure of the input port 2 further increases, the valve body 68 is driven to the rightmost side. That is, the pressure of the input port 2 is released to the low pressure port 63, and the control pressure is suppressed to a predetermined high pressure level or less.

Furthermore, if a shocking high pressure is applied to the input port 2.

When the valve body 66 is driven to the right, the input port 2 communicates with the valve housing space of the base body 61 through the side port 64a of the first guide 64 and communicates with the low pressure port 63. Since this passage area is large, the output port 2 sudden pressure rise (pressure shock)
is buffered.

FIG. 6 shows an enlarged longitudinal section of the main check valve 50. An input port 52 and an output port 53 communicate with a valve housing hole formed in the valve base 51. A cylindrical valve seat 54 with a bottom is housed in the valve housing hole, and a ball valve 57 pushed by a compression coil spring 56 closes a communication port 55 of the valve seat 54. When the pressure is higher than the pressure at the output port 53, the ball valve 57
is pushed to the right by the pressure of the input port 52 to open the communication port 55. That is, oil flows from the input port 52 toward the output port 53. However, when the pressure at the output port 53 is higher than the pressure at the input port 52, the ball valve 57 closes the communication port, so that oil does not flow from the output port 53 to the input port 52.

FIG. 7 shows an enlarged longitudinal section of the bypass valve 120.

The input port 121 communicates with the inner space of the first guide 123, and a compression coil spring 124b is connected to the inner space.
The valve body 124a pushed to the left is housed. This valve body 124a has an orifice at the center of the left end surface, and the input port 121 is connected to the first guide 1 through this orifice.
It communicates with 23 inner spaces. The inner space has a flow path 122
It communicates with the low pressure port 122 through b, but this flow path 1
22b is opened and closed by a needle valve 125.

The solenoid device consisting of the needle valve 125 to the electric coil 129 includes the needle valve 95 to the electric coil 9 shown in FIG.
The solenoid device has the same structure and dimensions as the solenoid device No. 9 (common design for the pressure control valve and the bypass valve), and the distance of the needle valve 125 with respect to the orifice 122b is substantially inversely proportional to the energizing current value of the electric coil 129. Since the flow opening degree of the orifice 122b is inversely proportional to this distance, the flow from the input port 121 passes through the orifice of the valve body 124a, passes through the inner space of the first guide 123, and enters the orifice 12.
The oil flow rate passing through 2b to the low pressure port 122 is
It is proportional to the differential pressure across the orifice on the left end surface of the valve body 124a.

As a result of the above, the pressure at the input port 121 is
The pressure is substantially proportional to the current value of 29. This bypass valve 120 sets the pressure (line pressure) at the input port 121 to a pressure proportional to the supplied current within a predetermined range. Also, when the ignition switch is off (engine stopped: pump 1 stopped), the electric coil 129
By stopping the energization, the needle valve 125 moves to the rightmost position, and the input port 121 (line pressure) becomes low pressure near the return pressure.

When the pressure of the input port 121 rises shockingly,
The valve body 124a is driven to the right by receiving this pressure on the left end face, and the low pressure port 122a communicates with the low pressure port 122.
communicates with the input port 121. Low pressure port 122a
Since is a relatively large opening, the impulsive rising pressure in the input port 21 immediately escapes to the low pressure port 122a.

The relief valve 60m is the relief valve 60f mentioned above.
It has the same structure as r, but has a conical valve body (68:
The compression coil spring (69) that presses the input port (62) has a slightly small spring force.
pressure (pressure at high pressure port 3) is the pressure at the relief valve 60
When fr is less than a predetermined high pressure, which is a pressure slightly lower than the pressure that releases the pressure of the input port 2 to the low pressure port 63, the output port (62) is cut off from the low pressure port (63). When the pressure at the input port (62) exceeds a predetermined high pressure, the valve body (68) is driven to the rightmost direction.

In other words, the pressure at the input port (62) is lower than that at the low pressure port (
63), and the pressure in the high pressure port 3 is suppressed to a predetermined high pressure or less.

With the above configuration, in the vehicle body support device shown in FIG. 1, the main check valve 50 supplies oil from the high pressure port 3 to the high pressure supply pipe 8, but prevents backflow from the high pressure supply pipe 8 to the high pressure port 3. do.

The relief valve 60I11 suppresses the pressure of the high pressure port 3, that is, the pressure of the high pressure supply pipe 8, to a predetermined high pressure or less, and when the pressure of the high pressure port 3 rises impulsively, it releases it to the return pipe 11, and buffering the propagation of impulsive pressure to 8.

The bypass valve 120 substantially linearly controls the pressure in the rear wheel high pressure supply pipe 9 within a predetermined range, and maintains the pressure in the rear wheel high pressure supply pipe 9 at a predetermined constant pressure during normal operation. This constant pressure control is performed by controlling the energizing current value of the bypass valve 120 with reference to the pressure detected by the pressure sensor 13rm.

Furthermore, when there is an impactful pressure increase in the rear wheel suspension, it is released to the return pipe 11 to buffer its propagation to the high pressure supply pipe 8. Furthermore, when the ignition switch is open (engine stopped: pump 1 stopped), electricity is cut off, and the rear wheel high-pressure supply pipe 9 is connected to the return pipe 11, and 1. Release the pressure from the rear wheel high pressure supply pipe 9 (high pressure supply pipe 8).

Pressure control valve 130fr, 80f L, 80rr, 80
rL is an electric coil (99
) is controlled, and the required support pressure is output to the output port (84). When impact pressure from the suspension propagates to the output port (84), it is buffered to suppress disturbances in the pressure control spool (91) (disturbances in the output pressure). In other words, the required pressure is stably applied to the suspension.

Cut valve 70fr, 70f L, 70rr, 70
r L is line pressure (front axle high pressure supply pipe 6. rear axle high pressure supply pipe 9)
) is below a predetermined low pressure, the suspension supply pressure line (between the output port 84 of the pressure control valve and the suspension) is shut off to prevent pressure from escaping from the suspension, and when the line pressure is above the predetermined low pressure, Fully open the supply pressure line. This automatically prevents an abnormal drop in suspension pressure when line pressure is low.

Relief valve 60fr, 60f L, 60rr, 6
0rL limits the pressure (mainly suspension pressure) in the suspension supply pressure line (between the output port 84 of the pressure control valve and the suspension) to below the high pressure upper limit, and prevents the axle from rising or when heavy objects are loaded. When there is a shocking pressure increase in the supply pressure line (suspension) due to throwing, etc., this is released to the return pipe 11, which alleviates the impact on the suspension and improves the durability of the hydraulic line connected to the suspension and the mechanical elements connected to it. enhance sex.

〔Effect of the invention〕

As described above, according to the pressure control device of the present invention, the driving means (
96, 97, 98a, 98b, 99) and the needle valve (9
By changing the position of 5), the vehicle height can be adjusted higher or lower.

When driving on a rough road where the wheel runs over a convex part or falls into a concave part, the needle valve (95) controls the pressure in the target pressure space by the electrically energized driving means (96, 97, 98a,
98b.

The spool (90) operates to maintain a constant pressure corresponding to the position determined by the output port (99), and the spool (90) maintains the pressure at the output port (
84, suspension pressure) is maintained at a constant pressure, the vertical vibration of the vehicle body due to the vertical vibration of the axle is damped.

The needle valve (95) opens (94) when the suspension pressure (pressure at the output port 84) decreases below the target pressure.
However, since the communication means (95r or 94a) allows the target pressure space (88) to flow through the low pressure pipe (89-11), a relatively large amount of water flows into the target pressure space (88) at this time as well. Since no pressure change occurs, the operation of the spool (90) is stable.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a suspension pressure supply system according to an embodiment of the present invention. FIG. 2 is an enlarged longitudinal sectional view of the suspension 100fr shown in FIG. 1. FIG. 3a is an enlarged longitudinal sectional view of the pressure control valve 80fr shown in FIG. 1. FIG. 3b is an enlarged sectional view of the needle valve 95 taken along the line mB-mB shown in FIG. 3a. FIG. 3c is an enlarged sectional view of a modified portion of a pressure control valve according to another embodiment of the present invention. FIG. 4 is an enlarged longitudinal sectional view of the cut valve 70fr shown in FIG. 1. FIG. 5 is an enlarged longitudinal sectional view of the relief valve 60fr shown in FIG. 1. FIG. 6 is an enlarged longitudinal sectional view of the main check valve 50 shown in FIG. FIG. 7 is an enlarged longitudinal sectional view of the bypass valve 120 shown in FIG. 1. 1: Pump 2: Reservoir 3: High pressure port 4: Attenuator 6: Front shaft high pressure supply pipe 7
: Accumulator 8: High pressure supply pipe 9: Rear shaft high pressure supply pipe 10: Accumulator 11: Reservoir return pipe 12 Nidrain return pipe 13fL, 13
fr, 13rw, 13rr, 13rmJ3rt: Pressure sensor 14, 14fr, 14rw, 14rr: Atmosphere release drain 15fL, 15fr, 15rc, 15
rr: Vehicle height sensor 50: Main check valve
51: Valve base 52: Input port 53: Output port 54: Valve seat 55: Communication port 56:
Compression coil spring 57: ball valve 60fr,
60f L, 60rr 60r L: Relief valve 61: Valve base 62: Input port 63:
Low pressure port 64: First guide 65: Filter
66: Valve body 67: Second guide 68: Valve body 69: Compression coil spring 71: Valve base 72 Niline pressure port 74: Oil drain port 75: Output port door 7: Under guide
78 Nispool 79: Compression coil spring 80fr, 80f L +80rr, 80r L: Pressure control valve 81 Nisleeve 82 Niline pressure port 84: Output port 85: Low pressure port 87: High pressure port 88: Target pressure space 89: Low pressure port 9
0 Nispool 92: Compression coil spring 94: Communication port 95: Needle valve 95r: Pressure relief groove (flow means) 73: Pressure adjustment input port door 6: First guide 83: Groove 86: Groove 88f Niorifice 91: Groove 93 : Valve body 94a: Small opening (flow means) 95G=Support member 95h: Hole 96:
Fixed core 97: Plunge'v 98a: Yoke
98b: End plate 98c: Low pressure port 99: Electric coil 102fr, 102f, , , 102rr, 10
2rL: Piston condo 103: Piston 104
: Inner cylinder 105: Upper chamber 106: Lower chamber
107: Side port 108: Vertical through hole 109: Valve damping valve device 110: Upper space 111: Piston 112: Lower chamber 113: Upper chamber 114
: Outer cylinder 120 : Bypass valve 12
1: Input port 122: Low pressure port 122a: Low pressure port 122b: Flow path 123: First guide 124
a: Valve body 124b: Compression coil spring
125: Two Dollar Valve 129: Electric Coil East 6 Figure March 13, 1991

Claims (1)

[Scope of Claims] A pressure source that supplies fluid at high pressure to a high-pressure pipeline for supplying pressure fluid to a suspension that expands and contracts in accordance with the supplied pressure; and a line pressure port that communicates with the high-pressure pipeline; A low pressure port that communicates with the low pressure pipe, an output port that applies pressure to the suspension, a target pressure space that communicates with the line pressure port, and receives the pressure of the output port at one end and uses this pressure to adjust the degree of flow between the line pressure port and the output port. The pressure in the target pressure space is received at the other end, and this pressure increases the flow rate between the line pressure port and the output port. A spool that is driven in a direction to lower the flow rate of the output port, a tip of which faces a communication port between the target pressure space and the low pressure pipe line, and is movable in the opposite direction; a needle valve that defines the degree of flow between the target pressure space and the low-pressure pipe, a valve support member that guides the needle valve movably in the opposing directions, and drives the needle valve in a direction that increases or decreases the degree of flow. 1. A pressure control device for a suspension, comprising: a pressure control valve device having an electrically energized drive means for discharging a part of the pressure in a target pressure space to a low pressure pipe.