JPH085297B2 - Suspension control device - Google Patents

Description

The present invention relates to a suspension control device used in a vehicle, and more particularly to a vehicle body posture by adjusting a pressure applied to a shock absorber of each wheel. The present invention relates to a suspension control device that controls vehicle height and vehicle height.

[Prior Art] The technique disclosed in Japanese Utility Model Laid-Open No. 1-114408 is to generate system pressure (or line pressure) from high-pressure fluid generated by a pump driven by an engine in suspension pressure control. The output pressure to be applied to each shock absorber is generated based on

[Problems to be Solved by the Invention] By the way, although the system pressure is relatively stabilized,
When the engine speed is abnormally low or abnormally high, the target value may not be maintained. Further, the system pressure may include pulsation of pressure having a relatively small amplitude. Therefore, in this type of suspension control device,
The pressure of the shock absorber fluctuates according to the fluctuation of the system pressure, and there is a possibility that the vehicle height fluctuates especially when the engine is in the idling state.

Therefore, conventionally, a pressure sensor for detecting the system pressure is provided, and the detected pressure is fed back to the control amount of the pressure control valve to process the fluctuation of the system pressure.

However, for example, when the vehicle travels on a bad road, the flow rate of the fluid flowing from the high pressure line to the low pressure line (reservoir) through the pressure control valve becomes large, and the supply flow rate from the pump to the high pressure line becomes insufficient. , The system pressure in the high pressure line is lower than usual. When the control current of the pressure control valve is increased in order to compensate for this drop in pressure, the pilot chamber becomes closed in the pressure control valve, and the spool moves toward the line pressure port and The output port may always be in communication. In that case,
Since the pressure applied to the shock absorber is apt to fluctuate depending on the line pressure (system pressure), vertical vibration of the vehicle body occurs and the riding comfort deteriorates.

The reason why the line pressure port and the output port are always in communication with each other will be specifically described with an example of using the pressure control valve 80fr shown in FIG.

The pressure of the output port 84 communicating with the absorber is the high pressure port to which the line pressure is applied if the spool 90 moves to the left.
It goes up in communication with 82, and when the spool 90 moves to the right, it goes down in communication with the low pressure port 85 to which the reservoir pressure is applied.
The pressure of the output port 84 is applied to the left end surface of the spool 90. Normally, the line pressure applied to the high pressure port 87 is reduced by the fixed throttle 88f and applied as pilot pressure (line pressure> pilot pressure) to the right end surface of the spool 90. When the output pressure is lower than the pilot pressure, the spool is pushed to the left and the high pressure fluid supplied from the high pressure port 82 increases the output pressure. When the output pressure becomes higher than the pilot pressure, the spool is pushed back to the left, the fluid flows to the low pressure port 85, and the output pressure drops. Therefore, the spool moves so that the output pressure and the pilot pressure are balanced, and the output pressure is adjusted to match the pilot pressure.

If the line pressure drops below normal when traveling on a rough road, if you try to increase the pilot pressure above the line pressure by performing pressure compensation control, the needle 95 fully closes the throttle 94,
The pressure drop at 88f disappears and the pilot pressure becomes equal to the line pressure. However, since the pilot pressure does not rise any further, the output pressure (equal to the line pressure in this case) does not exceed the pilot pressure, the spool moved to the left is not pushed back to the right, and the spool has a high pressure. Port 82 and output port 84 remain in communication and do not move. Therefore, the line pressure is continuously applied to the output port 84 as it is. In this case, the absorber pressure also fluctuates according to the fluctuation of the line pressure, causing vertical vibration of the vehicle body.

An object of the present invention is to prevent a change in vehicle height due to a change in system pressure and prevent deterioration of riding comfort when traveling on a rough road.

[Configuration of the Invention] [Means for Solving the Problems] In order to solve the above problems, in the present invention, a suspension mechanism including an actuator that expands and contracts according to the supply and discharge of fluid, and a vehicle height change due to expansion and contraction of the actuator. Vehicle height detecting means for detecting, pressure source means for generating fluid pressure supplied to the actuator, command value to which pressure supplied to the actuator is inserted between the actuator and the pressure source means Pressure control valve means for adjusting the pressure to a corresponding pressure, and a target pressure of the actuator is calculated based on the actual vehicle height and the target vehicle height detected by the vehicle height detecting means, and the command value corresponding to the target pressure is controlled by the pressure control. In a suspension control device comprising a control means provided to a valve means: a vehicle speed detection means for detecting a vehicle speed, an output side of the pressure source means Pressure detection means for detecting the pressure, and the target pressure of the actuator is corrected so as to suppress the fluctuation of the vehicle height due to the change in the pressure detected by the pressure detection means, and the correction value is used as the vehicle speed detection means. And electronic control means for making the correction value substantially zero when the vehicle speed detected by the vehicle speed detection means is higher than a predetermined vehicle speed determined in advance.

In the present invention, the system pressure (line pressure) output by the pressure source means is detected by the pressure detecting means, and the target pressure of the actuator (for example, shock absorber) is corrected according to the change in the detected value, and the pressure control valve means is provided. Since the command value of the suspension is controlled, even if a sudden change in the system pressure occurs due to, for example, idling while the vehicle is stopped, the change can be absorbed by the pressure control valve means, and the pressure applied to the actuator of the suspension is You can avoid fluctuations. This prevents a change in vehicle height while the vehicle is stopped.

On the other hand, when the vehicle is traveling on a rough road, the system pressure output by the pressure source means decreases, so if the target pressure applied to the actuator changes due to the correction, the line pressure port and the output port of the pressure control valve means are changed. There is a possibility that the continuous communication state of will occur. When the line pressure port of the pressure control valve means and the output port are in continuous communication,
Fluctuations in the system pressure output by the pressure source means are directly transmitted to the actuator, causing vertical vibration of the vehicle body. In order to prevent such a problem, if the correction gain of the pressure control for compensating the decrease in the system pressure is set to be small, it becomes impossible to suppress the change in the vehicle height during the idling.

However, in the present invention, the correction value of the target pressure of the actuator is changed according to the vehicle speed detected by the vehicle speed detection means, and when the vehicle speed detected by the vehicle speed detection means is higher than a predetermined vehicle speed set in advance, the correction value is set. Is substantially zero, the correction value can be set to a sufficiently large value when the vehicle is stopped, etc., and the change in vehicle height can be reliably controlled during idling. Moreover, since the correction amount during normal traveling becomes zero, it is possible to avoid the line pressure port of the pressure control valve means and the output port from being in continuous communication even when traveling on a bad road, and the ride comfort due to vertical vibration of the vehicle body can be avoided. Of deterioration is prevented.

The idling state often occurs when the vehicle is stopped or at a low speed, and is unlikely to occur in a normal running state, for example, when the vehicle speed is 10 km / h or higher. Therefore, during normal traveling, there is no possibility that the vehicle height will change even if the correction for the system pressure fluctuation is omitted. By making the correction amount zero, it is possible to prevent the line pressure port of the pressure control valve and the output port from always communicating even when driving on a rough road, and avoiding deterioration of riding comfort. To be

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

[Embodiment] FIG. 1 shows an outline of a mechanical portion of an automobile suspension device embodying the present invention. The hydraulic pump 1, which is a radial pump, is arranged in the engine room, is connected to the drive output of an on-vehicle engine (not shown) by a belt, and when driven to rotate, sucks oil from the reservoir 2 to a predetermined level or more. The oil is discharged into the high-pressure port 3 at a predetermined flow rate at the rotation speed of.

The high pressure port 3 of the radial pump for suspension pressure supply is connected with the pulsation absorbing attenuator 4, main check valve 50 and relief valve 60m.
High-pressure oil from the high-pressure port 3 is supplied to the high-pressure supply pipe 8 through the main check valve 50.

The main check valve 50 prevents the reverse flow of oil from the high pressure supply pipe 8 to the high pressure port 3 when the pressure of the high pressure port 3 is lower than the pressure of the high pressure supply pipe 8.

The relief valve 60m is one of return oil passages for returning the high pressure port 3 to the reservoir 2 when the pressure of the high pressure port 3 becomes equal to or higher than a predetermined pressure. The pressure in the high pressure port 3 is maintained at a substantially constant pressure by flowing through the reservoir return pipe 11.

The high pressure charge pipe 8, the front wheel suspension 100f _L, a front wheel high pressure feed pipe 6 for supplying a high voltage to 100FR, rear suspension 100r _L, the wheel high pressure charge tube 9 after for supplying a high voltage to 100rr communicated An accumulator 7 (for front wheels) is provided on the front wheel high-pressure supply pipe 6, and an accumulator is provided on the rear wheel high-pressure supply pipe 9.
10 (for rear wheels) are continuous.

A pressure control valve 80fr is connected to the front wheel high pressure supply pipe 6 via an oil filter, and the pressure control valve 80fr changes the pressure of the front wheel high pressure supply pipe 6 (hereinafter referred to as front wheel line pressure) to a required pressure (electricity thereof). Pressure corresponding to the current flowing through the coil: Suspension support pressure) is adjusted (reduced) to cut valve 70fr
And give to the relief valve 60fr.

The cut valve 70fr is provided with the output port 84 (to the suspension) of the pressure control valve 80fr and the suspension 10 when the pressure of the front wheel high pressure supply pipe 6 (front wheel side line pressure) is lower than a predetermined low pressure.
0fr shock absorber 101fr hollow piston rod 10
2fr is cut off to prevent pressure loss from the piston rod 102fr (shock absorber 101fr) to the pressure control valve 80fr, and the output pressure of the pressure control valve 80fr is maintained while the front wheel side line pressure is higher than a predetermined low pressure. (Suspension support pressure) is directly supplied to the piston rod 102fr.

The relief valve 60fr limits the internal pressure of the shock absorber 101fr to the upper limit value or less. That is, the pressure control valve 80
When the pressure of the output port 84 of fr (suspension support pressure) exceeds a predetermined high pressure, the output port 84 is set to the reservoir return pipe.
As a flow through 11, the pressure of the output port of the pressure control valve 80fr is maintained substantially below a predetermined high pressure. Further, the relief valve 60fr serves to buffer the propagation of this impact to the pressure control valve 80fr when the internal pressure of the shock absorber 101fr rises due to the impact of pushing up the front right wheel from the road surface, and the shock absorber 101fr. When the internal pressure of the shock absorber rises, the internal pressure of the shock absorber 101fr is discharged to the reservoir return pipe 11 via the piston rod 100fr and the cut valve.

The suspension 100fr is roughly composed of a shock absorber 101fr and a suspension coil spring 119fr. The pressure supplied to the shock absorber 101fr via the output port 84 of the pressure control valve 80fr and the piston rod 102fr (pressure control). The body is supported at a height (relative to the front right wheel) corresponding to the pressure regulated by the valve 80fr: suspension support pressure.

The support pressure applied to the shock absorber 101fr 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 1 is installed on the vehicle body near the suspension 100fr.
5fr is installed, and the link connected to the rotor of the vehicle height 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 wheel portion (height of the vehicle body with respect to the wheel).

Similar to the above, pressure control valve 80f _L , cut valve 70f _L ,
Relief valve 60f _L , vehicle height sensor 15f _L and pressure sensor
Similarly, 13f _L is assigned to the suspension 100f _L on the front left wheel, and the pressure control valve 80f _L is connected to the front wheel high pressure supply pipe 6 to provide a required pressure (supporting pressure) to the suspension 100f _L. Shock absorber 101f _L of piston rod 102f _L of.

Similar to the above, pressure control valve 80rr, cut valve 70rr, relief valve 60rr, vehicle height sensor 15rr and pressure sensor 13r
Similarly, r is assigned to the suspension 100rr of the rear right wheel, and is equipped, and the pressure control valve 80rr is connected to the rear wheel high pressure supply pipe 9 to provide a required pressure (support pressure) to the shock absorber of the suspension 100rr. 101rr piston rod 10
Give to 2rr.

Further, as described above, the pressure control valve 80r _L and the cut valve 70
r _L, relief valve 60r _L, height sensors 15r _L and the pressure sensor 13r _L is likewise suspension of the front left wheel portion 100r
_The pressure control valve 80r _L is connected to the rear wheel high pressure supply pipe 9 to provide a required pressure (supporting pressure) to the piston rod 102r _L of the shock absorber 101r _L of the suspension 100r _L.

In this embodiment, the engine is mounted on the front wheel side, and accordingly, the hydraulic pump 1 is mounted on the front wheel side (engine room), and the pipe length from the hydraulic pump 1 to the rear wheel suspension 10rr, 100r _L is increased. It is longer than the piping length from the hydraulic pump 1 to the front wheel side suspension 100fr, 100f _L.
Therefore, the pressure drop due to the pipe line is large on the rear wheel side, and if oil leakage occurs in the pipe, the pressure drop on the rear wheel side is the largest. Therefore, a pressure sensor 13rm for line pressure detection 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 tends to increase as the distance from the reservoir 2 increases. I'm trying to detect.

A bypass valve 120 is connected to the rear wheel high pressure supply pipe 9. The bypass valve 120 regulates the pressure of the high pressure supply pipe 8 (obtains a required line pressure) to a pressure corresponding to the value of the electric current flowing through the electric coil. Also, when the ignition switch is opened (engine stop: pump 1 stop), the line pressure is substantially zero (reservoir return pipe
The atmospheric pressure of the reservoir 2 is set through 11 (the drop of this line pressure turns off the cut valves 70fr, 70f _L , 70rr, 70r _L to prevent pressure loss of the shock absorber), and the engine (pump 1 ) Lighten the load when restarting.

Fig. 2 shows an enlarged vertical section of the suspension 100fr. The piston 103 fixed to the piston rod 102fr of the shock absorber 101fr is arranged in the inner cylinder 104 in the upper chamber 10 roughly.
It is divided into 5 and lower chamber 106. Suspension support pressure (hydraulic pressure) is supplied to the piston rod 102fr from the output port of the cut valve 70fr.
It joins the upper chamber 105 in the inner cylinder 104 through the side port 107 of 02fr, and further through the vertical through port 108 of the piston 103, the lower chamber 10
Join 6 A supporting pressure proportional to the product of this pressure and the cross-sectional area of the piston rod 102fr (square of rod radius × π) is applied to the piston rod 102fr.

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

When the piston rod 102fr relatively attempts to rapidly enter below the inner cylinder 104 due to the push-up of the front right wheel,
The internal pressure of the inner cylinder 104 suddenly rises, and similarly the pressure of the lower space 110 tends to suddenly become higher than the pressure of the lower chamber 112. At this time, the damping valve device 109 allows the oil to flow from the lower space 110 to the lower chamber 112 at a predetermined pressure difference or more, but prevents the oil from flowing in the reverse direction. From lower chamber 112
Flow, the piston 111 rises and buffers the impact (upward) applied from the wheel to the piston rod 102fr. That is, wheel impact on the vehicle body (upward thrust)
Is propagated.

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 inner cylinder
The internal pressure of 104 suddenly lowers, and similarly the pressure of the lower space 110 tries to suddenly become lower than the pressure of the lower chamber 112. At this time, the damping valve device 109 allows the oil to flow from the lower chamber 112 to the lower space 110 at a predetermined pressure difference or more, but prevents the oil from flowing in the reverse direction. To the lower space 110, whereby the piston 111 descends and buffers the impact (downward) applied from the wheel to the piston rod 102fr. That is, the propagation of the wheel impact (falling down) to the vehicle body is buffered.

In addition, shock absorber 101f
As the pressure applied to r rises, the pressure in the lower chamber 112 rises, the piston 111 rises, and the piston 111 comes to a position corresponding to the vehicle body load.

When there is no vertical movement of the piston rod 102fr relative to the inner cylinder 104, such as during parking, the seal between the inner cylinder 104 and the piston rod 102fr substantially prevents oil from leaking from the inner cylinder 104 into the outer cylinder 114. There is no. However, in order to reduce the vertical movement load of the piston rod 102fr, the seal has a sealing characteristic such that a slight oil leak occurs when the piston rod 102fr moves up and down. The oil leaked to the outer cylinder 114 passes through the outer cylinder 114,
It is returned to the reservoir 2 through a drain return pipe 12 (Fig. 1), which is a second return pipe, through a drain 14ft (Fig. 1) for release to the atmosphere. The reservoir 2 is equipped with a level sensor 28 (Fig. 1),
Generates a signal (oil shortage signal) indicating this when the oil level in the reservoir 2 is equal to or lower than the lower limit value.

The structures of the other suspensions 100f _L , 100rr and 100r _L are substantially the same as the structure of the suspension 100fr described above.

FIG. 3 shows an enlarged vertical cross section of the pressure control valve 80fr. The sleeve 81 has a spool accommodating hole formed in the center thereof, and a ring-shaped groove 83 communicating with the line pressure port 82 and a ring-shaped groove 86 communicating with the low pressure port 85 are formed on the inner surface of the spool accommodating hole. Has been done. These ring-shaped grooves 83
Output port 84 is open in the middle between and 86. Spool 90 inserted in the spool storage hole, in the middle of its side peripheral surface,
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 is provided. A valve housing hole is formed at the left end of the spool 90, and the valve housing hole communicates with the groove 91. The valve body 93 pushed by the compression coil spring 92 is inserted into the valve housing hole. This valve body 93 has a through orifice in the center, and this orifice communicates the space of the groove 91 (output port 84) with the space accommodating the valve body 93 and the compression coil spring 92. Therefore, the spool 90 receives the pressure of the output port 84 (regulated pressure on the suspension 100fr) at the left end thereof, and thereby receives the force that is driven to the right. Incidentally, when the pressure of the output port 84 is increased by impact, the valve body 93 moves to the left against the pressing force of the compression coil spring 92 and creates a buffer space at the right end of the valve body 93. When the output port 84 rises suddenly, this shocking upward pressure does not immediately apply to the left end face of the spool 90, but
Has the effect of buffering the right movement of the spool 90 against the buffer pressure increase of the output port 84. On the contrary, it exerts a function of buffering the leftward movement of the spool 90 against the shocking pressure drop of 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 this pressure causes the spool 90 to receive a force to be driven to the left. A line pressure is supplied to the high pressure port 87, but the target pressure space 88 communicates with the low pressure port 89 through a passage 94, and a flow passage opening of the passage 94 is defined by a needle valve 95.
When the needle valve 95 closes the flow path 94, the orifice 88
The pressure of the target pressure space 88 communicating with the high pressure port 87 via f becomes the pressure (line pressure) of the high pressure port 87,
90 is driven to the left, so that the groove 91 of the spool 90 communicates with the groove 83 (line pressure port 82), and the groove 91 (output port
The pressure of 84) rises and this is transmitted to the left side of the valve body 93, and the right driving force is given to the left end of the spool 90. When the needle valve 95 fully opens the flow path 94, the pressure in the target pressure space 88 becomes
Since it is throttled by the orifice 88f, it is significantly lower than the pressure (line pressure) of the high pressure port 87, and the spool 90 moves to the right, whereby the groove 91 of the spool 90 communicates with the groove 86 (low pressure port 85). The pressure in the groove 91 (output port 84) is reduced, and this is transmitted to the left side of the valve body 93, and the right driving force at the left end of the spool 90 is reduced. In this way, the spool 90
This is a position where the pressure in the target pressure space 80 and the pressure in the output port 84 are balanced. That is, a pressure that is substantially proportional to the pressure in the target pressure space 88 appears at the output port 84.

The pressure in the target pressure space 88 is determined by the position of the needle valve 95, and since this pressure is substantially inversely proportional to the distance of the needle valve 95 with respect to the flow path 94, the output port 84 eventually has a substantial distance to the distance of the needle valve 95. Inversely proportional pressure appears.

The needle valve 95 penetrates the fixed core 96 made of a magnetic material.
The right end of the fixed core 96 is frustoconical, and the end face of the magnetic plunger 97 having a bottomed conical hole faces the right end face. The needle valve 95 is fixed to the plunger 97. The fixed core 96 and the plunger 97 enter inside the bobbin around which the electric coil 99 is wound.

When the electric coil 99 is energized, magnetic flux flows in the loop of the fixed core 96-magnetic material yoke 98a-magnetic material 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 also receives the pressure of the target pressure space 88 as a right driving force, and the needle valve 95
Since the right end of the is the atmospheric pressure through the low pressure port 98c of the atmosphere release, the needle valve 95, due to the pressure of the target pressure space 88, the right driving force corresponding to its pressure value (which corresponds to the position of the needle valve 95). In the end, the needle valve 95 is connected to the flow path 94.
On the other hand, the distance is substantially inversely proportional to the current value of the electric coil 99. In order to make the current value-distance relationship linear, as described above, the fixed core and the plunger 97
One has a truncated cone shape and the other has a bottomed conical hole shape corresponding to this.

As a result, a pressure that is substantially proportional to the value of the current flowing through the electric coil 99 appears at the output port 84. The pressure control valve 80fr outputs, to the output port 84, a pressure proportional to an energizing current within a predetermined range.

FIG. 4 shows an enlarged cross section of the cut valve 70fr. The valve housing hole formed in the valve base 71 has a line pressure port 72, a pressure adjustment input port 73, an oil drain port 74 and an output port.
75 are in communication. Line pressure port 72 and pressure adjustment input port
The space 73 is divided by a ring-shaped first guide 76, and the space between the pressure adjusting input port 73 and the output port 75 is a cylindrical guide 77a,
Separated by 77b and 77c. The oil drain port 74 is the second
The second guide 77 communicates with the ring-shaped groove on the outer periphery of the guide 77c.
a, 77b and 77c to return oil
Return to.

A spool 78 pushed leftward by a compression coil spring 79 passes through the first and second guides 76 and 77a to 77c, and a line pressure is applied to the left end surface of the spool 78. The left end of the spool 78 has entered. The guide hole of the central protrusion of the second guide 77c communicates with the return pipe 11 through the ring-shaped groove on the outer periphery of the second guide 77c and the oil drain port 74. When the line pressure is less than the predetermined low pressure, as shown in FIG. 4, the spool 78 is driven to the leftmost side by the repulsive force of the compression coil spring 79, and the spool 78 is provided between the output port 75 and the pressure adjusting input port 73. Is closed by fully closing the inner opening of the second guide 77a. When the line pressure becomes equal to or higher than a predetermined low pressure, the spool 79 starts to be driven rightward against the repulsive force of the compression coil spring 79 by this pressure, and the spool 79 is located at the rightmost position (fully opened) at a pressure higher than the predetermined low pressure. . That is, when the spool 78 moves to the right from the inner opening of the second guide 77a, the pressure adjusting input port 73 penetrates the output port 75, and the line pressure (line pressure port 72) rises to a predetermined low pressure, the cut valve 70fr becomes , Pressure adjusting input port 73 (pressure control valve 80
fr pressure output) and output port 75 (shock absorber 10)
1 fr) and the line pressure (port 72) rises further, pressure regulating input port 73 (pressure regulating output of pressure control valve 80 fr) and output port 75 (shock absorber 101 fr)
Fully open between. When the line pressure decreases, the reverse occurs. When the line pressure becomes less than the predetermined low pressure, the output port 75 (shock absorber 101fr) is turned on by the pressure adjusting input port 7
It is completely shut off from 3 (pressure control output of pressure control valve 80fr).

FIG. 5 shows an enlarged vertical cross section of the relief valve 60fr.
An input port 62 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 in the valve housing hole, and the input port 62 communicates with the inner space of the first guide 64 through the filter 65. A valve body 66 having an orifice at its 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 of the first guide 64 accommodating the valve body 66 and the compression coil spring 66a passes through the orifice of the valve body 66, and the input port.
62, and through the opening of the spring seat 66b,
It communicates with the inner space of the second guide 67. Conical valve body 68
Is pushed to the left by the repulsive force of the compression coil spring 69,
The opening of the spring seat 66b is closed. When the pressure (control pressure) of the input port 62 is less than the predetermined high pressure, the pressure of the coil spring 66a storage space communicating with the input port 62 through the orifice of the valve body 66 is relatively higher than the repulsive force of the compression coil spring 69. Due to its low height, the valve body 68 closes the central opening of the valve seat 66b, as shown in FIG. 5, so that the output port 62 communicates with the low pressure port 63 through the hole 67a. It is cut off from the inner space of the second guide 67. That is, the output port 62 is cut off from the low pressure port 63.

When the pressure (control pressure) of the input port 62 rises to a predetermined high pressure, this pressure is applied to the central opening of the valve seat 66b through the orifice of the valve body 66, the valve body 68 starts to be driven right by this pressure, and the input port 62 When the pressure further rises, the valve element 68 is driven to the right. That is, the pressure at the input port 62 is
It is discharged to the low pressure port 63, and the control pressure is suppressed below a predetermined high pressure.

If a high pressure is applied to the input port 62 due to shock, the valve body
66 is driven right, and the input port 62 is the side opening of the first guide 64.
The valve housing space of the base 61 is communicated with the low pressure port 63 through 64a, and since the flow passage area is large, a sudden pressure increase (pressure shock) of the output port 62 is buffered.

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

FIG. 7 shows an enlarged vertical cross section of the bypass valve 120.
The input port 121 communicates with the inner space of the first guide 123, and the valve body 124a pushed leftward by the compression coil spring 124b is housed in the inner space. The valve body 124a has an orifice at the center of the left end face, and the input port 121 communicates with the inner space of the first guide 123 through this orifice. The internal space communicates with the low pressure port 122 through the flow path 122b, and the flow path 122b is opened and closed by the needle valve 125.

It consists of a needle valve 125 to an electric coil 129. The solenoid device has the same structure and size as the solenoid device consisting of the needle valve 95 to the electric coil 99 shown in FIG. 3 (designed for both the pressure control valve and the bypass valve), and the orifice
The distance of the needle valve 125 with respect to 122b is substantially inversely proportional to the value of the current flowing through the electric coil 129. Since the flow opening of the orifice 122b is inversely proportional to this distance, the oil flow rate from the input port 121, through the orifice of the valve element 124a, through the inner space of the first guide 123, through the orifice 122b, and out to the low pressure port 122 is , 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 value of the energizing current. This bypass valve 120 changes the pressure (line pressure) of the input port 121 to
The applied current is within a predetermined range and the pressure is proportional to it.
Further, when the ignition switch is off (the engine is stopped: the pump 1 is stopped), the energization of the electric coil 129 is stopped, so that the needle valve 125 moves to the rightmost position.
The input port 121 (line pressure) becomes a low pressure near the return pressure.

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

The relief valve 60m has the same structure as the relief valve 60fr described above, but has a conical valve body (68: fifth
The compression coil spring (69) that pushes the figure) has a slightly smaller spring force, and the pressure at the input port (62) (pressure at the high pressure port 3) is reduced by the relief valve 60fr. The output port (62) is disconnected from the low pressure port (63) when the pressure is lower than a predetermined high pressure, which is a little lower than the pressure discharged to the low pressure port 63.
When the pressure of the input port (62) becomes higher than a predetermined high pressure, the valve body (68) is driven to the right. That is, the pressure of the input port (62) is released to the low pressure port (63), and the pressure of the high pressure port 3 is suppressed to a predetermined high pressure or less.

With the above configuration, in the suspension 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. To do.

The relief valve 60m 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, the relief valve 60m returns it.
The shock pressure transmission to the high-pressure supply pipe 8 is buffered.

The bypass valve 120 controls the pressure of the rear wheel high pressure supply pipe 9 substantially linearly within a predetermined range, and maintains the pressure of the rear wheel high pressure supply pipe 9 at a predetermined constant pressure in a steady state. 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. Also,
When there is a shock pressure increase in the rear wheel suspension, it is released to the return pipe 11 to buffer the propagation to the high pressure supply pipe 8. Further, when the ignition switch is opened (engine stopped: pump 1 stopped), the energization is cut off and the rear wheel high pressure supply pipe 9 is made to flow to the return pipe 11, and the rear wheel high pressure supply pipe 9 (high pressure supply pipe 8 ) Release the pressure.

Pressure control valves _{80fr, 80f L, 80rr, 80r} L is the suspension pressure control, to provide the required support pressure to the suspension, the energization current value of the electrical coil (99) is controlled,
The required supporting pressure is output to the output port (84). When the shock pressure from the suspension propagates to the output port (84), it is buffered and the spool (91) for pressure control is used.
(Turbulence in output pressure) is suppressed. That is, the required pressure is stably applied to the suspension.

The cut valves 70fr, 70f _L , 70rr, 70r _L are provided for the suspension pressure supply line (the pressure control valve output port 84 and the suspension when the line pressure (front wheel high pressure supply pipe 6, rear wheel high pressure supply pipe 9) is lower than a predetermined low pressure. Between) to prevent the pressure from escaping from the suspension and fully open the pressure supply line when the line pressure is equal to or higher than a predetermined low pressure. This allows
An abnormal drop in suspension pressure when the line pressure is low is automatically prevented.

The relief valves 60fr, 60f _L , 60rr, 60r _L limit the pressure (mainly suspension pressure) in the suspension pressure line (between the output port 84 of the pressure control valve and the suspension) to below the high pressure upper limit value to prevent wheel collision. When there is a shocking pressure increase in the pressure supply line (suspension) due to lifting or throwing when mounting a heavy object, this is released to the return pipe 11 to mitigate the shock of the suspension and a hydraulic line connected to the suspension. And increase the durability of the mechanical elements connected to it.

FIG. 8a shows the configuration of an electric component part for controlling the hydraulic circuit of FIG. Referring to Figure 8a, this circuit is a control unit.
It is composed of an ECU and various switches, various sensors, various solenoids, etc. connected to its many input terminals and output terminals.

First, the sensors will be described. The vehicle height sensors 15f _L , 15fr, 15f _L and 15rr arranged near the shock absorbers at FL, FR, RL, and RR positions are the distances between the wheels at each position and the vehicle body, that is, at each position. Outputs a signal according to the vehicle height. Although each vehicle height sensor detects vehicle height information in the form of a digital signal, this information is converted into an analog voltage signal and output.

13f _L , 13fr, 13r _L and 13rr are FL, FR, RL and RR, respectively.
Is a pressure sensor arranged inside each shock absorber and outputs a voltage (analog signal) corresponding to each hydraulic pressure. 13rm and 13rt are pressure sensors arranged in the high pressure supply pipe 8 and the reservoir return pipe 11, respectively, as shown in FIG. 1, and the voltage (analog signal) corresponding to the pressure at each position.
Is output. 16p and 16r are G sensors that output a voltage (analog signal) according to acceleration (G).
p detects the longitudinal direction of the vehicle body, and 16r detects the lateral direction G of the vehicle body.

SN1 is a steering sensor that outputs a pulse signal according to the amount of rotation of the steering wheel, and outputs two-phase signals that are out of phase with each other. RG is one output terminal of the regulator that stabilizes the output voltage of the generator, and outputs a binary signal indicating whether or not the engine is rotating.
SN2 is a throttle sensor that outputs a 3-bit binary signal corresponding to the opening of the throttle valve. SW2 is a reed switch that detects the rotation of the permanent magnet connected to the speedometer cable, and outputs a pulse whose period changes according to the vehicle speed.

Further, RY, SW1, SW3, SW4, SW5 and SW6 are a main relay, an ignition switch, a stop lamp switch, a door switch, a reservoir level warning switch and a vehicle height adjusting switch, respectively. SOL1, SOL2, SOL3
And SOL4 are linear control valves (80f _L , 80fr, 80r _L , 80r) provided in hydraulic control units of FL, FR, RL and RR respectively.
r) is a solenoid, and SOL5 is a solenoid of the bypass valve 120.

FIG. 8b shows a specific configuration of the control unit ECU shown in FIG. 8a. Referring to FIG. 8b, the control unit ECU includes two CPUs (microcomputers) 17,18, an I / O expansion unit 130, a unit control unit 140, an A / D conversion unit 150, an active filter unit 160, and a duty. A control unit 170, a current detection unit 180, drivers 190 and 200, a power supply 210, a backup power supply 220, a driver 230, and an input buffer 240 are provided.

The signals applied to the input terminals IG, SPD, SS1 and SS2 of this control unit ECU meet the input buffer 240 and C
Applied to the input ports PA0, ASR0, ASR1 and ASR2 of PU17. ASR0 to ASR2 are interrupt request ports. In addition, the information of the signals applied to the input terminals ICL, L1, L2, L3, STP, DOOR, LOIL and HIGH is controlled by the CP via the I / O expansion unit 130.
Applied to input ports PA4 to PA7 of U17.

Vehicle height sensor 15f _L , 15fr, 15r _L , 15rr, pressure sensor 13f _L , 13f
The analog signals output from r, 13r _L , 13rr, 13rm, 13rt and G sensor 16p, 16r are the active filter unit 16
It is applied to each analog signal input terminal of the A / D conversion unit 150 via 0. Further, an analog signal corresponding to the current flowing through each of the solenoids SOL1 to SOL5 is generated by the current detection unit 180 and applied to each analog signal input terminal of the A / D conversion unit 150. By controlling the A / D conversion unit 150, the CPU 18 can convert the level of the signal applied to each analog signal input terminal into a digital signal and read it. CPU18 and A / D conversion unit 150
Information between and is transmitted through the serial output port So and the serial input port Si.

The value of the current flowing through the solenoids SOL1 to SOL5 of each solenoid valve is
Adjusted by pulse duty control (PWM). A pulse for controlling on / off of energization of each solenoid is generated by the duty control unit 170. By writing a predetermined instruction code and data for determining the duty value to the duty control unit 170 by the CPU 18,
The duty control unit 170 outputs a pulse having a duty corresponding to the data to each output terminal. Driver 20
0 controls ON / OFF of energization of each solenoid according to H / L of each pulse output output from the duty control unit.

By the way, in this embodiment, two C's are provided in the control unit ECU.
It is equipped with PUs 17 and 18, and these two CPUs control the operation of the entire system while exchanging information with each other. Each of the CPUs 17 and 18 is provided with an 8-bit bidirectional input / output port (data bus) PB (PB7 to PB0), and these 8-bit ports are connected to each other via a signal line group 306. In addition, in the signal line group 306, all the eight lines are connected to the power supply line (+5
When the ports PB of the two CPUs are in the input state at the same time, all the lines of the signal line 306 are fixed to the high level H.

The data transmitted between the CPUs 17 and 18 is the signal line group 306.
Via 8 bit parallel data. Also,
To match the timing of sending and receiving this data,
The CPUs 17 and 18 are further connected to each other by two control lines 307 and 308. The control line 307 is an output port PA3 of the main CPU17 and an interrupt request port input IR of the sub CPU18.
The other control line 308 connects between the output port PA4 of the CPU 18 on the sub side and the interrupt request input port IRP of the CPU 17 on the main side.

The CPUs 17 and 18 store programs that control the pressure of each suspension. According to this program, the CPU 18 mainly detects the vehicle height sensors 15f _L , 15fr, 15r _L , 15rr provided in the suspension system shown in FIG.
And pressure sensors 13f _L , 13fr, 13r _L , 13rr, 13rm, 13rt, and the vertical acceleration sensor 16p and lateral acceleration sensor 16r on the vehicle, and the pressure control valves 80f _L , 80fr, 80r.
_L , 80rr and the value of the current supplied to the electric coils (99, 129) of the bypass valve 120 are controlled.

The CPU 17 determines whether the line pressure of the suspension system (Fig. 1) is set / released, the vehicle operating state is determined, and the determination result from when the ignition switch SW1 is closed to when the ignition switch SW1 is opened. corresponding to. The required pressure (pressure to be set for each suspension) required to establish an appropriate vehicle height and body posture is calculated, and various detected values are received from the CPU 18 to determine the vehicle operating state.
The CPU 18 is supplied with the energizing current value required to set the required pressure.

Hereinafter, with reference to the flowchart shown in FIG.
The control operation of the CPUs 17 and 18 will be explained.First, for ease of understanding, the symbols assigned to the main registers assigned to the internal memory of the CPU17 and the contents of the main data written to each register are described. The summary is shown in Table 1.

In the flow chart of the drawings and the description below, the register symbol itself may mean the contents of the register.

First, refer to FIG. 9a. On-board battery 19 to itself
When power is supplied from (step 1), the CPU 17 sets internal registers, counters, timers, etc. to predetermined contents of the initial standby state, and the output port is set to the initial standby state (mechanical elements). (No electric energization) is output (Step 2: In the following parentheses, words such as step and subroutine are omitted, and only the symbols attached to them are described).

Next, the CPU 17 checks whether the ignition switch SW1 is closed (3), and when it is open, waits until it is closed. When the ignition switch SW1 is closed, the coil of the relay RY is energized to close the contact piece of the self-holding relay RY and maintain that state (4). When the relay RY turns on, the power circuit 210
Since it is connected to 9, even if the ignition switch SW1 is opened thereafter, all the electric circuit systems shown in FIG. 8 are electrically energized until the CPU 17 turns off the relay RY. To maintain.

When the relay RY is turned on, the CPU 17 permits execution of various interrupt processes executed in response to arrival of a pulse signal to the interrupt input ports ASR0 to ASR2 (5).

Here, the outline of the interrupt processing in response to the pulse signal to the input ports ASR0 to ASR2 will be described. First, the interrupt processing (input port ASR2) in response to the pulse generated by the vehicle speed sensor SW2 that generates the vehicle speed synchronization pulse will be described.
When a pulse is generated, responding to this, interrupt processing (ASR2)
Go to, read the contents of the vehicle speed clock register at that time, restart the vehicle speed clock register, calculate the vehicle speed value from the read contents (cycle of the vehicle speed synchronization pulse), and save the previous several times. The value Vs obtained by calculating the vehicle speed calculated value and the weighted average is written in the vehicle speed register VS, and the process returns to the step immediately before proceeding to this interrupt processing (return). By executing this interrupt process (ASR2), the data indicating the vehicle speed at that time (the smoothed value of the clock train of the calculated vehicle speed) is always stored in the vehicle speed register VS.
Vs is held.

The interrupt process (input port ASR0) generated by the rotary encoder SN1 for detecting the rotation direction of the steering shaft in response to the first set of generated pulses will be described below. When proceeding to interrupt processing (ASR0) and proceeding to interrupt processing (ASR0) in response to a rising edge, write H to the flag register for rotation direction discrimination, and proceeding to interrupt processing (ASR0) in response to a falling edge. , Clears the flag register (writes L), and returns to the step immediately before proceeding to this interrupt processing.

When the rising edge of the pulse of the first set of the rotary encoder SN1 (flag register = H) appears next to the rising edge of the pulse of the second set, the steering shaft is driven to rotate counterclockwise and the rising edge of the pulse of the first set. When the trailing edge of the second set of pulses appears after the trailing edge (flag register = L), the steering shaft is driven to rotate clockwise.

The interrupt process (input port ASR1) of the rotary encoder SN1 for detecting the rotation speed (steering angular velocity) of the steering shaft in response to the generated pulse of the second set will be explained. When it arrives, in response to this, it proceeds to the interrupt processing (ASR1), reads the contents of the steering clock register at that time, restarts the steering clock register, and reads the contents (the period of the steering angular velocity synchronization pulse), If the content of the flag register for discriminating the direction of rotation is H, a sign of + (left rotation) is attached, and if the content of the flag register is L, a sign of − (right rotation) is attached, and the speed value ( (Including directions + and-),
Write to the steering angular velocity register SS the value Ss obtained by taking the speed calculation value and the weighted average of the previous several times held until then, and return to the step immediately before proceeding to this interrupt processing (return),
By executing this interrupt processing (ASR1), the steering angular velocity register SS always stores data Ss indicating the steering angular velocity (time-series smoothed value of the speed calculation value) at that time (+ indicates left rotation, − indicates right rotation).
Is held.

When the above-mentioned interrupt processing is permitted, the CPU 17 checks whether or not the CPU 18 gives a ready signal. (6).

By the way, the CPU 18 executes initialization when the power is turned on to itself, sets internal registers, counters, timers, etc. to the contents of the initial standby state, and the output port has an initial standby state (mechanical elements). Signal level (data for designating all electric coils OFF) is output to the duty controller 170. Then, the duty controller 170 is supplied with the maximum current value data that causes the bypass valve 120 to be fully closed, and the energization of the bypass valve 120 is instructed. With the above settings, the pressure control valve 80f _L , 80fr, 80
r _L , 80 rr has a current value of zero and outputs the pressure of the return pipe 11 to the output port (84) of the bypass valve 120.
Is fully closed, and the pump 1 is rotationally driven while the engine is rotating, so that the high pressure supply pipe 8, the front wheel high pressure supply pipe 6 (accumulator 7) and the rear wheel high pressure supply pipe 9 (accumulator
The pressure in 10) begins to rise.

Thereafter, the CPU 18 sets the vehicle height sensor 15f _L , 15 at the first set cycle.
fr, 15r _L , 15rr, pressure sensor 13f _L , 13fr, 13r _L , 13rr, 13rm, 13
rt, the acceleration sensor 16p, 16r detection value, and the power supply detection value of each solenoid SOL1 to SOL5 are read and updated and written in the internal register.When the CPU 17 requests the transfer of detection data, The data in the internal register can be
Transfer to.

When the CPU 17 sends the energizing current target value data of each of the pressure control valves 80f _L , 80fr, 80r _L , 80rr and the bypass valve 120, each of these target values and the solenoids SOL1 to SO.
Each control duty value is generated based on the corresponding current detector of L5, and these are set to the duty controller 17
Give to 0.

When the CPU 18 gives a busy signal in the checks in steps 6 and 7 described above, the CPU 17 waits there and executes the waiting process (8 to 11). In the standby process (8), the presence / absence of abnormality is determined by referring to the pressure detection values of all the pressure sensors, the current detection values of all the solenoids, and the vehicle height detection values of all the vehicle height sensors, and the suspension control waits (while stopped). When the pressure is set (the bypass valve 120 is de-energized to be fully opened and the pressure control valve is de-energized) and an abnormality is determined, a notification and pressure setting corresponding to the abnormality (de-energization of the bypass valve 120, pressure control valve not Energize) (1
0). If no abnormality is determined, the abnormality processing is canceled (abnormality notification is cleared) (11).

Now, when the CPU 18 outputs the ready, the above-mentioned abnormal processing (which may not be executed) is canceled (12) and the standby processing (which may not be executed) is canceled (13).

Then, the CPU 17 instructs the CPU 18 to transfer the detected pressure data Dph of the pressure sensor 13rm, receives this, and receives the register DPH.
Write (14), detected pressure (pressure on the rear wheel side of high pressure supply pipe 8) Dp
Check whether h is equal to or greater than a predetermined value Pph (pressure value lower than a predetermined low pressure at which the cut valves 70f _L , 70fr, 70r _L , 70rr start to open) (whether the line pressure has risen to some extent) (1
Five). If the line pressure has not risen, the process returns to step 6.

When the line pressure rises, the CPU17
13f _L, 13fr, 13r _L, the detection pressure (initial pressure) of 13rr data Pf _L o, Pf
ro, Pr _L o, registers receives these instructs transfer of Prro PFLo, PFRo, PRLo, written into PRRo (16).

Then, the energizing current value data required to obtain the required pressure in one area (table 1) of the internal ROM is stored in the register PFL.
o, PFRo, PRLo, the contents of _{PRRo Pf L o, Pfro, Pr} L o, and access Prro, energizing current to the solenoid required to output a pressure Pf _L o to an output port 84 of the pressure control valve 80f _L Ihfr, pressure Pr _L
energizing current value necessary for outputting the o to an output port of the pressure control valve 80f _L Ihr _L, and tables the energization current value Ihrr requiring pressure Prro to the output port of the pressure control valve 80Rr 1
Read from the output registers IHf _L , IHfr, IHr _L and IH
Write to rr (17). CP the data in these output registers
Transfer to U18. The CPU 18 uses these data as the target value of the current, and based on that and the detected current value of the solenoid, generates a duty value such that they become equal,
The value is given to the duty controller 170.

The duty controller 170 generates a pulse signal of a duty corresponding to each input duty value, and controls energization of each solenoid valve via the driver 200.

Depending on the current setting (target value) at this time, the pressure control valve 80
_{f L, 80fr, 80r L,} 80rr outputs when the line pressure is a predetermined low pressure or more, substantially Pf _L o respectively, Pfro, Pr _L o, the output port pressure Prro (84), the line pressure the cut valve 70f _L in response to the rise to higher than a predetermined low pressure, 70FR, when 70r _L, 70rr is opened, then the pressure in each suspension (initial _{pressure) Pf L o, Pfro, Pr} L o, and Prro Substantially equal pressure is applied through the cut valves 70f _L , 70fr, 70r _L , 70rr to the pressure control valves 80f _L , 80f.
Suspension 100f _L , 100fr, 100r _L , 100 from r, 80r _L , 80rr
Supplied to rr.

Therefore, the ignition switch SW1 changes from open (engine stopped: pump 1 stopped) to closed (pump 1 driven),
When the cut valves 70f _L , 70fr, 70r _L , 70rr are opened for the first time (line pressure is lower than a predetermined low pressure) and the hydraulic line of the suspension communicates with the output port of the pressure control valve, the output pressure of the pressure control valve and the suspension pressure are Are substantially equal to each other, and sudden pressure fluctuations in the suspension do not occur. That is, no shocking change in the vehicle body posture occurs.

The above is the pressure control valve 80 when the ignition switch SW1 is switched from open to closed (immediately after starting the engine).
Initial output pressure setting of f _L , 80fr, 80r _L , 80rr.

 Next, the CPU 17 starts the ST timer ST.

ST is the contents of register ST, and register ST contains CPU1
Data ST indicating a second setting cycle which is longer than the first setting cycle in which the detection value 8 is read is written.

When the timer ST is started, the CPU 17 reads the status (20)
Perform In this, the ignition switch SW2
Read / write signal, brake pedal depression detection switch SW3 open / close signal, absolute encoder SN1 throttle opening data, and reservoir level detection switch SW5 signal are read and written to the internal register, and CPU 18 is instructed to transfer the detection data. Then, the vehicle height sensor 15f _L , 15fr, 15
Vehicle height detection data of r _L , 15 rr Df _L , Dfr, Dr _L , Drr, pressure sensor 1
3f _L , 13fr, 13r _L , 13rr, 13rm, 13rt pressure detection data Pf _L , Pf
_{r, Pr L, Prr, Prm} , Prt, and a pressure control valve and the bypass valve 80f _L, 80FR, 80 r _L, receives the transfer of the electric current value detection data 80Rr, 120, written into the internal register.

Then, referring to these read values, it is determined whether there is an abnormality or not, and when it is abnormal, the process proceeds to step 8.

When normal, the CPU 17 next executes line pressure control (LPC). In this case, the reference pressure (relief valve 60
Absolute value and polarity (high / low) of the deviation of the detection line pressure Prm with respect to a fixed value (slightly lower than the relief pressure of m (predetermined high pressure))
To calculate the current value of the bypass valve 120 at this time by adding a correction value to the current value of the current flowing in the bypass valve 120, which corresponds to the deviation and makes the deviation zero. Write to output register. The contents of this output register are transferred to the CPU 18 in step 36 described later.

By this "line pressure control" (LPC), the bypass valve 120 is adjusted so that the pressure of the rear wheel high pressure supply pipe 9 becomes a predetermined value slightly lower than the relief pressure (predetermined high pressure) of the relief valve 60m.
The energizing current value of is controlled.

Now referring to FIG. 9b. When the line pressure control (LPC) is finished, the CPU 17 checks whether the switch 20 is open or closed (22), and if it is open, the stop process (23) is performed and the relay 22 is turned off. Disable interrupts ASR0 to ASR2. In the stop process (23), the bypass valve 120 is first de-energized and fully opened (line pressure is returned to the return pipe 11).
Release).

Switch SW1 opened (engine stopped: pump 1 stopped, high pressure discharge of pump 1 stopped, bypass valve 120 fully opened, high pressure supply pipe 8, front wheel high pressure supply pipe 6 (accumulator 7) and rear Wheel high pressure supply pipe 9 (accumulator
The pressure of 10) becomes the pressure of the return pipe 11, and the return pipe 11
When the pressure of 1 is released to the reservoir 2, the high-pressure supply pipe 8 and the like become atmospheric pressure. The high pressure supply pipe 8 etc. is a cut valve 70f _L , 7
At the timing when the pressure falls below the specified low pressure at which 0fr, 70r _L , 70rr turns to complete shutoff, the CPU 17 sets the pressure control valves 80f _L , 80f.
Deenergize r, 80r _L and 80rr.

Now, when the switch SW1 is closed, the parameter indicating the vehicle traveling state is calculated (25). That is, the content Ss of the steering angular velocity register SS is read to calculate [the throttle opening Tp read this time, read in subroutine 20, the throttle opening read last time] = Ts (throttle opening / closing speed), and register TS Write to.

Next, the CPU 17 executes "vehicle height deviation calculation" (31),
The suspension pressure correction amount (first correction amount: required to calculate the deviation of the vehicle body height from the target vehicle height and set it to zero)
For each suspension). For details of this content,
This will be described later with reference to FIG. 10a.

The CPU 17 executes a "pitching / rolling prediction calculation" (32) after the "vehicle height deviation calculation" (31) to determine the suspension pressure correction amount (first value) corresponding to the vertical and lateral acceleration actually applied to the vehicle body. 2 correction amount: to calculate each per suspension), [suspension initial pressure _{(Pf L o, Pfro, Pr} L o, Prr
o) + first correction amount + second correction amount] (calculation intermediate value: for each suspension). For details of this content, see Section 10b.
It will be described later with reference to the drawings.

Next, the CPU 17 executes the "pressure correction" (33) to correspond to the line pressure (high pressure) detected by the pressure sensor 13rm and the return pressure (low pressure) detected by the pressure sensor 13rt, and calculates the "calculated intermediate value". Is corrected. For details of this content, see Section 10c.
It will be described later with reference to the drawings.

Next, the CPU 17 uses the “pressure / current conversion” (34) to set the corrected “calculated intermediate value” (for each suspension) to the current value to be passed through the pressure control valves 80f _L , 80fr, 80r _L , 80rr. Convert. This content will be described later with reference to FIG. 10d.

The CPU17 then uses "warp correction" (35) to determine the lateral acceleration Rg.
And steering speed Ss. A turning warp correction value (battery correction value) is calculated, and the current value to be passed through the pressure control valve is added. For details on this content, see Section 10e
It will be described later with reference to the drawings.

The CPU 17 then calculates "output" (36) as described above. The current value to flow to the pressure control valve is transferred to the CPU 18 to each pressure control valve, and the current value to flow to the bypass valve 120 calculated by the "line pressure control" (LPC) described above is addressed to the bypass valve 120. Then, transfer to CPU18.

Here, the CPU 17 has completed all the tasks included in the suspension pressure control for one cycle. Therefore, wait until the timer ST times out (37).
When the time is over, the process returns to step 19, restarts the timer ST, and executes the task of the suspension pressure control in the next cycle.

Due to the suspension pressure control operation of the CPU 17 described above, the CPU 18 requests the CPU 18 to transfer the sensor detection value in the ST cycle (second setting cycle) (subroutine 20), and in response thereto, the CPU 18 The read values of the past several times and the sensor detection value data that has been subjected to the weighted average smoothing are read in one set cycle and transferred to the CPU 17. Further, in the ST cycle, the current value data to be passed through each of the pressure control valves and the bypass valve 120 is transferred from the CPU 17 to the CPU 18, and each time the CPU 18 receives this transfer, these current value data and the solenoid The duty value is calculated from the detected current value and the value is output to the duty controller 170. Therefore, the current value of each of the pressure control valves and the bypass valve 120 is S
It is updated to approach the target current value in the T cycle.

The contents of the “vehicle height deviation calculation” (31) will be described with reference to FIG. 10a. First, in the overview, the vehicle height sensors 15f _L , 15fr, 15
Vehicle height detection value of r _L , 15 rr Df _L , Dfr, Dr _L , Drr (Register DFL, DF
R, DRL, DRR), heave (height) DHT, pitch (difference between front wheel height and rear wheel height) DPT, roll (right wheel height and left wheel height) DRT and warp (difference between vehicle height of front right wheel and vehicle height of rear left wheel and vehicle height of front left wheel and vehicle height of rear right wheel) DWT. That is, each wheel height (contents of registers DFL, DFR, DRL, DRR)
Attitude parameters for the entire vehicle body (heave DHT, pitch DP
T, roll DRT and warp DWT).

DHT = DFL + DFR + DRL + DRR, DPT =-(DFL + DFR) + (DRL + DRR), DPT = (DFL-DFR) + (DRL-DRR), DWT = (DFL-DFR)-(DRL-DRR). This DPT calculation is performed in "Pitching error CP calculation" (51),
Calculation of DRT is executed by "calculation of rolling error CR" (52), and calculation of DWT is executed by "calculation of warp error CW" (53).

Then, in "calculation of heave error CH" (50), the target heave Ht is derived from the vehicle speed Vs, the heave error amount of the calculated heave DHT with respect to the target heave Ht is calculated, and PID (proportional, integral, derivative) control is performed. Then, the calculated heave error amount is PID-processed, and the heave correction amount CH corresponding to the heave error is
To calculate.

Similarly, in "Calculation of pitching error CP" (51), the target pitch Pt is derived from the vertical acceleration Pg, and the calculated pitch is calculated.
Calculate the pitch error amount of the DPT with respect to the target pitch Pt.
For ID (proportional, integral, derivative) control, the calculated pitch error amount is subjected to PID processing to calculate a pitch correction amount CP corresponding to the pitch error.

Similarly, in "Calculation of rolling error CR" (52), the target roll Rt is derived from the lateral acceleration Rg and the calculated roll is calculated.
Calculate the roll error amount for the DRT target roll Rt, and
For ID (proportional, integral, derivative) control, the calculated roll error amount is PID processed to calculate a roll correction amount CR corresponding to the roll error.

Similarly, in “Calculation of Warp Error CW” (53), the target warp Wt is set to zero and the calculated warp DWT
Calculate the warp error amount for t and calculate the PID (proportional, integral,
For the differential control, the calculated warp error amount is subjected to PID processing to calculate the roll correction amount CW corresponding to the warp error. When the absolute value of the calculated warp error amount (DWT because the target warp is zero) is less than or equal to a predetermined value (within the allowable range), the warp error amount for PID processing is set to zero, and when it exceeds the predetermined value. Let the amount of warp error for PID processing be −DWT.

Explaining the contents of “calculation of heave error CH” (50) in detail, the CPU 17 first determines the target heave Ht corresponding to the reference Vs.
Is read from one area (table 2H) of the content ROM and written in the heave target value register HT (39).

As shown as “Table 2H” in FIG. 10a, the vehicle speed V
The target heave Ht associated with s is that the vehicle speed Vs is VsaKm.
At low speeds below / h, the high value is Ht ₁ , and at high speeds when the vehicle speed Vs is Vsb or higher, it is low value Ht ₂ , but in the range where Vs exceeds Vsa and less than Vsb, the target value is linear to the vehicle speed Vs. (It may be a curve). In this way, changing the target value linearly means, for example, if the target value is 100 Km / h or less,
_{If the} target value is switched to Ht ₂ in steps of ₁ and 100 Km / h or more, when Vs is near 100 Km / h, the target heave greatly changes in steps due to a slight change in Vs speed. This is to prevent this because the vehicle height frequently rises and falls with the vehicle speed and the vehicle speed stability deteriorates. Above table
According to the setting of 2H, the target value changes only slightly when the vehicle speed Vs slightly changes in height, so the vehicle height target value changes only slightly and the vehicle height stability increases.

In step 40, the heave amount obtained by the calculation of DFL + DFR + DRL + DRR is stored in the register DHT.

Next, write the contents of the register EHT2 in which the previously calculated heave error amount is written to the register EHT1 (41), calculate the current heave error amount HT-DHT2, and register this.
Write to EHT2 (42). As described above, the register EHT1 stores the previous (before ST1) heave error amount, and the register EHT2 stores the current heave error amount. CPU17 then
Write the contents of the register ITH2, which has written the error integration value up to the previous time, to the register ITH1 (43), and set the PID correction amount this time to I.
Th is calculated by the following formula.

ITh = Kh ₁ / EHT ₂ + Kh ₂ / (EHT ₂ + Kh ₃ / ITH 1) + Kh ₄ / Kh _{5
· (EHT2-EHT1) Kh 1} · EHT2 is P (proportional) term of the PID operation, Kh ₁ coefficients of the proportional term, EHT2 is the content of register EHT2 (Hibuera amount of time).

Kh ₂ · (EHT2 + Kh ₃ · ITH1) is the I (integral) term,
Kh ₂ is the coefficient of the integral term, ITH 1 is the correction amount integral value up to the previous time (the integral value of the correction amount output from the initial pressure setting 16-18),
Kh ₃ is a weighting coefficient between the current error amount EHT2 and the correction amount integral value ITH1.

_{Kh 4 · Kh 5 · (EHT2} -EHT1) is a D (differential) term,
The coefficient of the differential term is Kh ₄ · Kh ₅ , but Kh ₄ uses a value associated with the vehicle speed Vs, and Kh ₅ uses a value associated with the steering angular velocity Ss. That is, the vehicle speed correction coefficient Kh ₄ associated with the vehicle speed Vs at that time is read from one area of the internal ROM (table 3H), and the steering angular velocity Vs at that time is read from one area of the internal ROM (table 4H). The associated steering angular velocity correction coefficient Kh ₅ is read and the product Kh ₄ · Kh ₅ of these is used as the coefficient of the differential term.

As shown as “Table 3H” in FIG. 10a, the vehicle speed correction coefficient Kh ₄ is generally a larger value as the vehicle speed Vs is higher, and the weight of the differential term is increased. This is a correction term in which the derivative term tries to quickly accommodate the change in the heave to the target value, and the higher the vehicle speed, the faster the vehicle height changes with respect to the disturbance, so it is increased according to the vehicle speed. . On the other hand, vehicle speed Vs
Is above a certain level (VsdKm / h or higher in Table 3H), sudden changes in the vehicle body posture occur when the brake pedal is depressed / released, the accelerator pedal accelerates / decelerates, and the steering wheel turns / turns back. However, it becomes extremely large, and the excessive differential term that quickly compensates for such a sudden change in posture deteriorates the vehicle height control stability. Therefore, more precisely, the vehicle speed correction coefficient Kh ₄ of the table 3H changes greatly with respect to changes in the vehicle speed Vs when the vehicle speed Vs is low, and changes with decreasing vehicle speed Vs. That is, when the vehicle speed Vs is low, the weight of the differential term changes greatly with respect to the vehicle speed fluctuation, but when the vehicle speed Vs is high, the weight change of the differential term with respect to the vehicle speed fluctuation is small.

As shown as “Table 4H” in FIG. 10a, the steering angular velocity correction coefficient Kh ₅ is generally a larger value as the steering angular velocity Ss is higher, and the weight of the differential term is increased. This is a correction term for the derivative term to try to fit it into the target value faster with respect to the change of the heave, and the higher the steering angular speed Ss, the faster the vehicle height change speed with respect to the disturbance. I am raising. On the other hand, when the steering angular velocity Ss is below a certain level (Ssa ° / msec or less in Table 4H), the change in the traveling direction is extremely gentle and the weighting of the differential term is small, and above Ssa and below Ssb, it is substantially proportional to the steering angular velocity Ss. Vehicle height changes appear at the speed you have set. At steering angular velocities of Ssb and above, changes in the vehicle body posture become abrupt and extremely large, and an excessive differential term that quickly compensates for such a sudden posture change will be dangerous because the stability of the vehicle height control will be lost. Therefore, the coefficient Kh ₅ of the differential term corresponding to the steering angular velocity Ss is a constant value when Ss is 50 Ssa or less, a high value that is substantially proportional to Ss when Ss exceeds Ssb, and a value at Ssb when Ssb is exceeded. Is a constant value.

With the introduction of more than differential term Kh ₄ · Kh ₅ · described (EHT2-EHT1), or even, the coefficient Kh ₄ increased in response to the vehicle speed Vs, correspondingly greater coefficient Kh ₅ to the steering angular velocity Ss By doing so, weighted differential control corresponding to the vehicle speed Vs and the steering angular speed Ss is realized, and highly stable vehicle height control is realized with respect to variations in the vehicle speed Vs and the steering angular speed Vs.

At step 44, the values of the proportional term, integral term, and derivative term of the PID calculation are added, and the result is obtained as a heave error correction amount ITh.

Next, the CPU 17 writes the calculated heave error correction amount ITh in the register ITH2 (45), and adds a heave error correction amount weighting coefficient Kh ₆ (weighting to a pitch error correction amount, a roll error correction amount, and a warp error correction amount described later: Write the heave error register CH by multiplying the contribution ratio in the total correction amount).

When the calculation (50) of the heave error CH is performed as described above, the CPU 17 executes the “calculation of the pitching error CP” (51), calculates the pitch error correction amount CP in the same manner as the heave error CH, and Write to register CP. In this case, the pitch target value PT corresponding to the heave target value HT is the data Pt corresponding to the vertical acceleration Pg at that time (target corresponding to the longitudinal acceleration Pg) from one area of the internal ROM of the CPU 17 (Table 2P). Value) is read and obtained.

Fig. 11a shows the contents of table 2P. The pitch target value Pt corresponding to the vertical (forward / backward) acceleration Pg is the vertical acceleration Pg.
It is in the direction to cancel (decrease) the pitch appearing by. The region a is intended to save energy by increasing the target pitch as the vertical acceleration Pg increases (decreases). The region b is considered to be an abnormal sensor for abnormal Pg, so the pitch target value should be reduced. This is to prevent giving the pitch target value even though Pg is not actually generated. The other calculation processing operations are the same as those in the above-mentioned “calculation of heave error CH” (50), the HT and Ht of step 39 are replaced with PT and Pt, and the DHT of step 40 is replaced.
Replace the calculation formula with the above-mentioned DPT calculation formula, and EHT1,
Replace EHT2 with EPT1, EPT2 and replace EHT2, HT, DHT in step 42
Replace with EPT2, PT, DPT and replace ITH1, ITH2 in step 43 with ITP1, I
Replaced by TP2, the ITh calculation formula of the subroutine 44 is replaced by a pitch error correction amount ITp calculation formula which has a completely corresponding relationship therewith, and the table 3H is replaced by a coefficient table (3P) for pitch correction amount ITp calculation, The table 4H is also replaced with the coefficient table (4P) for calculating the pitch correction amount ITp, and the ITH at step 45 is replaced.
2, ITh is replaced by ITP2, ITp, and CH, Kh ₆ , I in step 46
By replacing Th with CP, Kp ₆ , ITp,
A flow chart showing the contents of "CP calculation" (51) appears. The CPU 17 executes the processing represented by this flowchart.

Next, the CPU 17 "calculates rolling error CR" (52)
To execute the roll error correction amount CR and the heave error CH.
Calculate in the same way as and write to the roll error register CR. In this case, the roll target value RT corresponding to the heave target value HT is the data Rt (lateral acceleration) corresponding to the lateral acceleration Rg at that time from one area of the content ROM of the CPU 17 (table 2R).
Roll target value corresponding to Rg) is read and obtained.

Figure 11b shows the contents of Table 2R. The roll target value Rt corresponding to the lateral acceleration Rg is in a direction (decreasing) for canceling the roll that appears due to the lateral acceleration Rg. The region a is intended to save energy by increasing the target roll as the lateral acceleration Rg increases (decreases). The region b is considered to be an abnormal sensor due to an abnormal Rg. This is to prevent the roll target value from being given although Rg does not actually occur. For other calculation processing operations, refer to "Calculation of heave error CH" described above.
It is the same as the content of (50), and HT and Ht of step 39 are R
Replace with T, Rt, replace the DHT calculation formula of step 40 with the DRT calculation formula described above, replace EHT1, EHT2 of step 41 with ERT1, ERT2, EHT2, HT, DHT of step 42 with ERT2, RT, Replace with DPT,
ITH1 and ITH2 in step 43 are replaced with ITR1 and ITR2, the ITh calculation formula of the subroutine 44 is replaced with a roll error correction amount ITr calculation formula that has a completely corresponding relationship with it, and the table 3H is used for calculating the roll correction amount ITr. Replace with the coefficient table (3R),
Table 4H is also a coefficient table (4
Substituted with R), the ITH2, ITh in step 45 is replaced with ITR2, ITr, and CH of the step 46, by replacing the Kh _6, ITh CR, and Kr _6, ITr, "calculation of roll error CR" A flowchart showing the contents of (51) appears. The CPU 17 executes the processing represented by this flowchart.

Next, the CPU 17 executes "calculation of warp error CW" (53), calculates the warp error correction amount CW in the same manner as the heave error CH, and writes it in the warp error register CW. In addition,
In this, the warp target value corresponding to the heave target value HT
PW is set to zero.

The other calculation processing operations are the same as those in the above-mentioned “calculation of heave error CH” (50).
Replace T, Ht with WT, O and replace the DHT calculation formula in step 40 with the above D
Replace with EWT1, EHT2 in step 41 by replacing with WT calculation formula
Replace the contents of step 42 with the absolute value of DWT, which is the predetermined value W.
When it is less than m (within the allowable range), WT is set to 0, and when it exceeds Wm, WT is converted to −DWT, and WT is converted to the contents to be written in the register EWT2, and ITH1 and IHT2 in step 43 are converted to ITW1 and ITW2.
To the warp error correction amount ITw calculation formula that has a completely corresponding relationship, and replaces Table 3H with the coefficient table (3W) for calculating the warp correction amount ITr. 4H is also replaced with the coefficient table (4W) for calculating the warp correction amount ITw, and ITH in step 45
2, ITh is replaced with ITW2, ITw, and CH, Kh ₆ , IT in step 46
Replacing h with CW, Kw ₆ ,, ITw gives the "warp error C
A flow chart appears showing the contents of "Calculation of W" (53). The CPU 17 executes the processing represented by this flowchart.

As described above, when the heave error correction amount CH, the pitch error correction amount CP, the roll error correction amount CR, and the warp error correction amount WP are calculated, the CPU 17 determines these correction amounts as the suspension pressure correction amount EHf _{L of} each wheel portion. (Suspension 100f _L addressed), EHfr (100fr addressed), EHr _L (100r _L addressed), EHrr (100rr addressed). That is, the suspension pressure correction amount is calculated as follows.

EHf _L = Kf _L · Kh ₇ · (1/4) · (CH-CP + CR + CW), EHfr = Kfr · Kh ₇ · (1/4) · (CH-CP – CR-CW), EHr _L = Kr _L · Kh ₇ · (1/4) · (CH + CP + CR-CW), EHrr = Krr · Kh ₇ · (1/4) · (CH + CP-CR + CW), coefficients Kf _L , Kfr, Kr _L , Krr are line pressure reference points For 13 rm and return pressure reference point 13 rt. Suspension 100f _L ,
This is a correction coefficient for compensating the suspension supply pressure deviation due to the difference in pipe length of 100fr, 100r _L , 100rr. Kh
Reference numeral ₇ is a coefficient for increasing / decreasing the vehicle height deviation correction amount corresponding to the steering angular velocity Ss, and is read from one area (table 5) of the internal ROM of the CPU 17 corresponding to the steering angular velocity Ss. . If the steering angular velocity Ss is large, a large change in attitude is expected, and an increase in the amount of attitude error is expected. Therefore, the coefficient Kh
₇ is generally set to be large in proportion to the steering angular velocity Ss. However, the steering angular velocity Ss is below a certain level (Table 5
At Ssc ° / msec or less), the change in the traveling direction is extremely gradual, and the attitude change is small and gradual. At over Ssc and Ssd or less, the attitude change appears at a speed substantially proportional to the steering angular speed Ss. At a steering angular velocity exceeding Ssd, the change in the vehicle body attitude becomes abrupt and extremely large, and an excessive amount of correction that quickly compensates for such a sudden attitude change impairs vehicle height control stability. Therefore, the correction coefficient Kh ₇ corresponding to the steering angular velocity Ss is a constant value when Ss is Ssc or less, and a high value that is substantially proportional to Ss when Ss exceeds Ssc and less than Ssd, and a constant value when Ssd exceeds Ssd. It has a value.

Next, with reference to FIG. 10b, the contents of the “pitching / rolling prediction calculation” (32) will be described. The above-mentioned "vehicle height deviation calculation" (31) is generally used to detect the current vehicle body posture from the current vehicle height and steering angular velocity so as to maintain the vehicle body posture at a predetermined and appropriate one, and to determine the current vehicle body posture. While the suspension pressure is adjusted (feedback control) so as to obtain the predetermined appropriate value, "pitching /
The "rolling prediction calculation" (32) is intended to suppress changes in the vehicle body posture according to vertical and lateral accelerations applied to the vehicle body.

The CPU 17 first calculates a correction amount CGT for suppressing a change in pitch due to a change in vertical acceleration Pg (55 to 58). In this case, the contents of the register GPT2 that previously wrote the correction amount corresponding to Pg are written to the register GPT1 (55),
The correction amount Gpt corresponding to Vs and Pg is read from one area of ROM (table 6) and is written in the register GPT2 (5
7). The data Gpt in Table 6 is grouped with Vs as an index, and the CPU 17 specifies the group with Vs,
Read the Pg-compatible data Gpt in the specified group. In each group, the smaller the Vs is assigned, the dead zone a width (Gpt = in Table 6 shown in FIG. 10b).
The width of 0) is set to a large value. b is a region where the gain is increased and the control performance is improved as the vertical acceleration Pg is increased, and c is a region where the control performance is reduced because more than the sensor is considered.

Next, the CPU 17 calculates the correction amount CGP for suppressing the change in the vertical acceleration Pg by the following equation and writes it in the register CGP (58).

CGP = Kgp ₃ · _{[Kgp 1 · GPT2 + Kgp 2 (} GPT2-GPT1) ] GPT2 represents the content of register GPT2, time, table 6
This is the correction amount Gpt read out. GPT1 is register GPT1
And the correction amount read out from the table 6 last time. Kgp ₁ of P (proportional) term Kgp ₁ · GPT2 is the coefficient of the proportional term.

D (differential) term Kgp Kgp ₂ of ₂ · (GPT2-GPT1) is a coefficient of differential term, this factor Kgp _2, the internal in response to the vehicle speed Vs ROM
It is read from one area (table 7). First
As shown as “Table 7” in FIG. 10b, the coefficient Kgp ₂
Is a larger value as the vehicle speed Vs is higher, and the weight of the differential term is increased. This is a correction term in which the differential term tries to suppress the change in the vertical acceleration Pg faster, and the higher the vehicle speed, the stepping / release of the brake, acceleration / deceleration by the accelerator pedal, turning / turning back by turning the steering wheel, etc. This is because the vertical acceleration Pg changes rapidly due to, so that the posture change can be quickly suppressed in response to this rapid change.
On the other hand, when the vehicle speed Vs exceeds a certain level, when the brake pedal is depressed / released, the accelerator pedal accelerates / decelerates, or the steering wheel turns / turns back, the longitudinal acceleration Pg changes rapidly and is extremely large. Therefore, an excessive differential term that quickly suppresses a sudden posture change at this time destroys the stability of suppressing the longitudinal acceleration. Therefore, more precisely, the coefficient Kgp _{2 of} Table 7 greatly changes when the vehicle speed Vs is low with respect to the change of the vehicle speed Vs.
It is constant when Vs is a predetermined value or more. That is, when the vehicle speed Vs is low, the weight of the differential term largely changes with respect to the variation of the vehicle speed, but when the vehicle speed Vs is high, the weight of the differential term does not change with respect to the variation of the vehicle speed.

The calculated correction amount CGP for suppressing the change in vertical acceleration Pg is the pitch correction amount for the suspension, and KgP ₃ is
It is a weighting coefficient for roll correction amounts CGR and GES described later.

Next, the CPU 17 calculates the correction amount CGR for suppressing the roll change due to the change of the lateral acceleration Pr (that is, suppressing the change of the lateral acceleration Pr) (59 to 62). In this case, the previous contents of the register GRT2 in which the correction amount corresponding to Rg is written is written to the register GRT1 (59), and the correction amount Grt corresponding to Vs and Rg is read from one area (table 8) of the internal ROM. Write this to register GRT2 (61). The data Grt in Table 8 is grouped using Vs as an index, and C
The PU 17 designates a group with Vs and reads the Rg-compatible data Grt in the designated group. In each group, the dead band a width (the 10th
In Table 8 shown in FIG. b, the horizontal width of Grt = 0) is set to be large. b is a region where the gain is increased and the control performance is improved as the lateral acceleration Rg is increased, and c is a region where the control performance is degraded because a sensor abnormality is considered.

Next, the CPU 17 calculates the correction amount CGR for suppressing the change in the lateral acceleration Rg by the following equation and writes it in the register CGR (62).

CGR = Kgr ₃ · _{[Kgr 1 · GRT2 + Kgr 2 ·} (GRT2-GRT1) ] GRT
2 is the content of the register GRT2, which is the correction amount Grt read from the table 8 this time. GRT1 is the content of the register GRT1 and is the correction amount read from the table 8 last time.
P (proportional) term Kgr ₁ · Kgr ₁ of GRT ₂ is a coefficient of the proportional term.

D Kgr ₂ of (differential) term Kgr ₂ · (GRT2-GRT1) is a coefficient of differential term, this factor Kgr _2, the internal in response to the vehicle speed Vs RO
It is read from one area of M (Table 9).
As shown as “Table 9” in FIG. 10b, the coefficient Kgr
₂ is generally the larger the higher the vehicle speed Vs, the larger the weight of the differential term. This is a correction term in which the differential term tries to suppress the change in lateral acceleration Rg faster, and the higher the vehicle speed, the faster the change in lateral acceleration Rg due to turning / turning back due to rotation of the steering wheel. This is because it tries to suppress this quickly in response to. Meanwhile, vehicle speed
When Vs exceeds a certain level, the turning / returning due to the rotation of the steering is suddenly performed, and the change in the lateral acceleration Rg is abrupt and extremely large. An excessive differentiation that suppresses such an abrupt change quickly. As for the term, the stability of suppressing lateral acceleration is broken. Therefore the coefficients in Table 9
More specifically, Kgr ₂ shows that when the vehicle speed Vs changes, the vehicle speed Vs
When the vehicle speed Vs is lower than a predetermined value, it is constant when the vehicle speed is low. That is, when the vehicle speed Vs is low, the weight of the differential term changes greatly with respect to the fluctuation of the vehicle speed.
When is high, there is no change in the weight of the differential term with respect to changes in vehicle speed.

The calculated CGR is a roll correction amount for the suspension, and Kgr ₃ is a weighting coefficient for the pitch correction amount CGP and the roll correction amount GES described later,
When the vehicle speed Vs is low, the change rate of the lateral acceleration Rg is low, so the contribution ratio of this roll correction amount CGR is lowered in the low speed range.
The coefficient data Kgr ₃ corresponding to the speed Vs is stored in one area (table 10) of the internal ROM so as to have a constant value in the high speed area. The CPU 17 reads the coefficient Kgr ₃ corresponding to the vehicle speed Vs and uses it for the above-described calculation of CGR.

The lateral acceleration Rg changes due to the change of the steering position (rotational position) (steering angular velocity Ss), and the rate of this change is the vehicle speed Vs.
Also depends on. That is, the change in the lateral acceleration Rg is the steering angular velocity.
Since it also corresponds to Ss and Vs, the roll correction amount Ges required to suppress this change is written in one area (table 11) of the internal ROM of the CPU 17.

Next, the CPU 17 converts the calculated pitch correction amount CGP, roll correction amount CGR, and roll correction amount DES into a pressure correction amount for each suspension, and this pressure correction amount is first referred to as "vehicle height deviation calculation (31 ) Value calculated by EHf _L , EHfr, EHr _L , EHrr
Add to (registers EHf _L , EHfr, EHr _L , EHrr contents),
The obtained sum Ehf _L , Ehfr, Ehr _L , Ehrr is set to the register EHf _L , EHfr, EHr _L ,
Update and write to EHrr (66).

Ehf _L = EHf _L + Kgf _L · (1/4) · (-CGP + Kcgrf · CGR + Kg
ef _L・ GES) Ehfr ＝ EHfr ＋ Kgfr ・ (1/4) ・ (−CGP ＋ Kcgrf ・ CGR−Kg
eft ・ GES) Ehr _L ＝ EHr _L ＋ Kgr _L・ (1/4) ・ (CGP ＋ Kcgrr ・ CGR ＋ Kger
_L・ GES) Ehrr = Ehrr ＋ Kgrr ・ (1/4) ・ (CGP ＋ Kcgrr ・ CGR−Kger
r · GES) The first term on the right-hand side of the above equation is the value that was previously calculated in “Vehicle height deviation calculation” (31) and was written in the registers EHf _L , EHfr, EHr _L , EHrr. Yes, the second term on the right side is the above-mentioned pitch correction amount CGP, roll correction amount CGR, and roll correction amount GES.
Is converted into a pressure correction amount for each suspension. The coefficients Kgf _L , Kgfr, Kgr _L and Kg
rr is Kgf _L = Kf _L · Kgs, Kgfr = Kfr · Kgs, Kgr _L = Kr _L · Kgs, Kgrr = Krr · Kgs, and Kf _L , Kfr, Kr _L , Krr are the respective points for the pressure reference point. It is a coefficient for correcting the pressure error due to the dispersion of the pipe length of the suspension (pipe length correction coefficient), and Kgs is a coefficient that is predetermined in association with the steering angular velocity Ss, as shown in Table 12, "Vehicle height deviation calculation" mentioned above (31)
The pressure correction value calculated in “Pitching / rolling prediction calculation” (32) for the pressure correction value calculated in Step 3 to suppress acceleration change (the second term on the right side of the above equation: (1/4)
(-CGP-Kcgrf / CGR + Kgef _L / GES) etc.) is specified. If the steering angular velocity Ss is large, a rapid acceleration change is expected, and it is preferable to increase the weighting of the pressure correction value for suppressing the acceleration change. Therefore, the coefficient Kgs is generally set to be large in proportion to the steering angular velocity Ss. However, the steering angular velocity Ss is below a certain level (Sse ° /
(msec or less), the change in acceleration is extremely small, and above Sse and below Ssf, the acceleration changes at a speed substantially proportional to the steering angular speed Ss. At steering angular velocities above Ssf, the change in the turning radius is rapid and extremely large, and the acceleration change (especially lateral acceleration) is extremely large. The excessive correction amount that quickly compensates for such rapid acceleration change is The stability of control is lost. Therefore, the weighting coefficient Kgs corresponding to the steering angular velocity Ss is a constant value when Ss is Sse or less,
Above Sse and below Ssf, it is set to a high value that is substantially proportional to Ss,
When Ssf is exceeded, the value at Ssf is kept constant.

The CPU 17 then determines the initial pressure registers PFL ₀ , PFR ₀ , PRL ₀ , PRR.
_The initial pressure data written in ₀ (set in steps 16 to 18) was calculated in the subroutine 66. Calculate the pressure to be set for each suspension by adding it to the sum of the correction pressure for vehicle height deviation adjustment and the correction pressure for acceleration suppression control (contents of registers EHf _L , EHfr, EHr _L , EHrr) , Register EH
Update and write to f _L , EHfr, EHr _L , EHrr (67).

Next, the contents of the "pressure correction" (33) will be described with reference to FIG. 10c. In this process, the CPU 17 uses the pressure sensor 13rm
Fluctuations in the output pressure of the pressure control valve due to line pressure fluctuations corresponding to the detection pressure Dph (contents of register DPH), and return pressure fluctuations corresponding to the detection pressure Dp _L (contents of register DPL) of the pressure sensor 13rt The fluctuation of the output pressure of the pressure control valve due to is compensated.

The correction value PH shown in steps 70E and 70F changes according to the value of the detected pressure Dph in order to compensate for the change of the run pressure, and the table assigned to one area of the internal ROM with Dph as a parameter. It is read from 13H at any time.

Also, the correction values PLf and PLr shown in steps 70E and 70F
Are for compensating for fluctuations in the output pressure of the pressure control valve due to fluctuations in the return pressure, and are correction values for the front wheel side and the rear wheel side, respectively. These correction values PLf and PLr are stored in the internal ROM.
It is read from the table 13L assigned to one area at any time.

The correction value corresponding to the return pressure is divided into the front wheel side and the rear wheel side because the front wheel side is close to the reservoir, the rear wheel side is far from the reservoir, and the low pressure detection pressure sensor 13rt is the rear wheel side reservoir. Since the pressure is detected, the difference in return pressure between the rear wheel side and the front wheel side is relatively large, and this is to reduce the error due to this.

Further, the processing of FIG. 10c also includes a countermeasure when the pressure sensor 13rm that detects the line pressure fails. In this embodiment, the pressure sensor 13rm is designed so that its output voltage is normally within a predetermined range (between MAX and MIN of the table 13H), and when it is out of the range, the sensor malfunctions. Is considered to be.

For example, if a short circuit or a break in the circuit occurs in the pressure sensor 13rm, the output voltage thereof changes rapidly. In the process of FIG. 10c, the pressure applied to the absorber is corrected according to the pressure detected by the pressure sensor 13rm, so if the detected pressure becomes abnormal,
The pressure applied to the absorber changes and the vehicle height becomes abnormal.

Therefore, in this embodiment, when the detected pressure DPH is within the range of MIN and MAX shown in Table 13H, step 70A is executed to set the coefficient Kpa to 1. However, when DPH is out of the range, from step 69. Go to 70B, set flag Fph,
In the next step 70C, the coefficient Kpa is set to zero.

The pressure correction values PDf and PDr are calculated in steps 70E and 7E, respectively.
It is calculated by 0F, but when the coefficient Kpa is 0, the correction value PH according to the detected pressure does not affect PDf and PDr. Therefore, even if the pressure sensor 13rm should fail, the correction value PH depends on the abnormality detected value. The absorber pressure is not corrected and there is no fear that the vehicle height will rise or fall abnormally.

By the way, for example, when a vehicle runs on a bad road, the flow rate of oil flowing from the high pressure pipe (8) to the low pressure pipe (11) through the pressure control valves (80f _L , 80fr, 80r _L , 80rr) is large. Therefore, the supply flow rate from the pump 1 to the high-pressure line becomes insufficient, and the line pressure in the high-pressure line becomes lower than usual. When the control current of the pressure control valve is increased (in the process of FIG. 10c) in order to compensate for this drop in pressure, the pilot chamber (88) is closed in the pressure control valve, and the pressure in the pilot chamber is increased. May rise, the spool (90) may move toward the line pressure port (82), and the line pressure port and the output port (84) may be in communication with each other. In that case,
The pressure applied to the shock absorber tends to depend on the line pressure. Therefore, since a relatively small vertical vibration occurs in the vehicle body, if such a situation occurs while the vehicle is running,
The ride becomes uncomfortable.

The reason why the line pressure port and the output port are always in communication will be specifically described with reference to FIG.

The pressure of the output port 84 communicating with the absorber is the high pressure port to which the line pressure is applied if the spool 90 moves to the left.
It goes up in communication with 82, and when the spool 90 moves to the right, it goes down in communication with the low pressure port 85 to which the reservoir pressure is applied.
The output of the output port 84 is applied to the left end surface of the spool 90. Normally, the line pressure applied to the high pressure port 87 is reduced by the fixed throttle 88f and applied as pilot pressure (line pressure> pilot pressure) to the right end surface of the spool 90. When the output pressure is lower than the pilot pressure, the spool is pushed to the left and the high pressure fluid supplied from the high pressure port 82 increases the output pressure. When the output pressure becomes higher than the pilot pressure, the spool is pushed back to the right, the fluid flows to the low pressure port 85, and the output pressure drops. Therefore, the spool moves so that the output pressure and the pilot pressure are balanced, and the output pressure is adjusted to match the pilot pressure.

If the line pressure drops below normal when traveling on a rough road, if you try to increase the pilot pressure above the line pressure by performing pressure compensation control, the needle 95 fully closes the throttle 94,
The pressure drop at 88f disappears and the pilot pressure becomes equal to the line pressure. However, since the pilot pressure does not rise any further, the pilot pressure does not exceed the output pressure (in this case, equal to the line pressure), the spool moved to the left is not pushed back to the right, and the spool has a high pressure. Port 82 and output port 84 remain in communication and do not move. Therefore, the line pressure is continuously applied to the output port 84 as it is. In this case, the absorber pressure also fluctuates according to the fluctuation of the line pressure, causing vertical vibration of the vehicle body. Further, in that case, since the absorber pressure cannot be adjusted by suspension control, if the absorber is pushed up from the road surface, the vehicle height at which the absorber pressure changes abruptly fluctuates greatly. Furthermore, since the variable throttle 94 is fully closed or in a state close to it, the relationship between the driving force of the solenoid for adjusting the opening of the variable throttle and the pilot pressure becomes non-linear, and in addition to the minute movement of the needle 95. Also changes the pilot pressure greatly. Therefore, control of the pilot pressure becomes unstable, which causes unstable movement of the spool valve 93,
Vehicle height fluctuations and noise will occur.

Therefore, in this embodiment, the pressure correction value according to the change of the line pressure is changed according to the vehicle speed. That is, when the vehicle speed is close to zero, for example, a racing condition may occur, and in that case, the line pressure becomes abnormally large. Therefore, the vehicle height may change significantly unless the line pressure is sufficiently compensated. There is. However, in a normal running state, that is, when the vehicle speed is equal to or higher than a predetermined value, there is no fear of becoming a racing state. Conversely, if the compensation amount for the fluctuation of the line pressure is large, the problem when driving on a bad road as described above is caused. Occurs.

In this example, in steps 70E and 70F, the coefficients
Kpb is provided to adjust the influence of the correction value PH on the control output, and the value of the coefficient Kpb is changed as shown in Table 13V according to the vehicle speed Vs. The contents of this table 13V are stored in one area of the ROM. Therefore, the compensation amount according to the fluctuation of the line pressure becomes zero when the vehicle speed Vs is 10 Km / h or more.

When the CPU 17 calculates the correction values PDf and PDr in steps 70E and 70F, these correction values are registered in the registers EHf _L , EHfr, EHr _L , EHrr.
In addition to the contents of, the registers EHf _L , EHfr, EHr _L , and EHrr are updated and written. (70).

According to this embodiment, during normal driving, for example, the vehicle speed is 40 km / h.
Since the amount of control compensation for the line pressure change becomes zero when the vehicle is traveling at, even when traveling on a bad road, the high pressure port 82 and the output port 84 do not always communicate with the pressure control valve. . Therefore, for example, when the shock absorber is pushed up from the road surface, the pressure at the output port 84 (absorber pressure) becomes higher than the pilot pressure, the spool 90 moves to the right side in FIG. 3, and the pressure control valve Since the oil that has flowed in from the output port 84 flows out to the low pressure port 85, the sudden increase in absorber pressure is mitigated, and fluctuations in vehicle height are suppressed. Also, the variable diaphragm 94 is not fully closed,
Since it is used at an intermediate opening, the opening is substantially proportional to the energizing current of the solenoid, and the pilot pressure control does not become unstable.

Explaining the contents of the "pressure / current conversion" (34) with reference to Fig. 10d, the CPU 17 determines the pressure indicated by the data EHf _L , EHfr, EHr _L and EHrr of the registers EHf _L , EHfr, EHr _L and EHrr. Pressure control valves 80f _L , 80fr, 80r _L and 80
The current values Ihf _L , Ihfr, Ihr _L and Ihrr to be passed to rr are read from the pressure / current conversion table 1 and written in the current output registers IHf _L , IHfr, IHr _L and IHrr, respectively (34).

The content of the warp correction (35) will be described with reference to FIG. 10e. This warp correction (35) is applied to lateral acceleration Rg and steering angular velocity.
Calculate the appropriate target warp DWT from Ss (73), and
Calculate the warp that appears when the contents of the above-mentioned registers IHf _L , IHfr, IHr _L , and IHrr are output, and calculate the target warp
Calculating the error warp amount for DWT (74 to 76), the error warp amount required to zero, the current correction value dIf _L, d
Ifr, dIr _L, calculates the DIRR (77), registers these current correction value IHf _L, IHfr, IHr _L, and added to the contents of IHrr, updates writes the sum to these registers (78).

The warp target value Idr corresponding to the lateral acceleration Rg is written in one area (table 14) of the internal ROM of the CPU 17, and the word processor target value Ids corresponding to the snake angular velocity Ss is written in the table 15. , Table 16 is written with the warp correction amount Idrs corresponding to the vehicle longitudinal inclination and lateral acceleration Rg (lateral inclination) defined by the values of the registers IHf _L , IHfr, IHr _L , and IHrr to be output. There is. The front-back inclination is expressed by K = | (Ihf _L + Ihfr) / (Ihr _L + Ihrr) |, and the data group corresponding to this K is written in Table 16, and each data of each data group is It is associated with the acceleration Rg.

The CPU 17 reads the warp target value Idr corresponding to the lateral acceleration Rg from the table 14, the warp target value Idr corresponding to the steering angular velocity Ss, and the registers IHf _L , IHfr, IHr.
Vehicle longitudinal inclination and lateral acceleration specified by the values of _L and IHrr
Table 16 shows the warp correction amount Idrs corresponding to Rg (lateral inclination).
Then, the warp target value DWT is calculated from the following equation (73).

_{DWT = Kdw 1 · Idr + Kdw} 2 · Ids + Kdw 3 · Idrs CPU17 then the register IHf _L, IHfr, IHr _L, the content of IHrr Ih
Calculate the warp (Ihf _L −Ihfr) − (Ihr _L −Ihrr) specified by f _L , Ihfr, Ihr _L , Ihrr and check whether it is within the allowable range (dead zone) ( 74), if it is out of the allowable range, calculated from the target warp WDT Warp (Ihf _L −Ihfr) − (Ihr _L −Ihr
r) is subtracted and the value is written to the warp error correction amount register DWT (75). When it is within the allowable range, the content (DWT) of the register DWT is not changed. Then, the warp error correction amount D
WT (contents of register DWT) is multiplied by the weighting coefficient Kdw ₄ and the product is updated and written in the register DWT (76), and this warp error correction amount DWT is set to each suspension pressure correction amount (correctly, pressure correction). The pressure control valve energization current correction value corresponding to the amount) is converted (77), and the correction is added to the contents of the current output registers IHf _L , IHfr, IHr _L and IHrr (78).

These current output registers IHf _L , IHfr, IHr _L and IHrr
Data is transferred to the CPU 18 by the "output" (36) subroutine addressed to the pressure control valves 80f _L , 80fr, 80rr and 80rr, and the CPU 18 gives it to the duty controller 32.

[Effect] As described above, according to the present invention, the pressure detecting means (13rm)
Since the control amount (EHf _L , EHfr, EHr _L , EHrr) is corrected according to the system pressure (line pressure: Dph) detected by, it is possible to suppress the fluctuation of the vehicle height due to the system pressure change such as during idling. . Further, since the correction value is changed according to the vehicle speed, the correction value can be made small during normal traveling, and for example, even when traveling on a rough road, the pressure control valve means (80f _L , 80fr, 80r _L , 8
0rr) inside the line pressure port (82) and output port (8
4) It is possible to prevent communication with and. This allows
It is possible to avoid deterioration in riding comfort, and it is possible to suppress fluctuations in vehicle height even if the vehicle is pushed up from the road surface during traveling. Furthermore, since the variable throttle (94) can be used in a range that does not approach the fully closed state, the relationship between the urging amount of the pressure adjusting valve means and the pilot pressure can be maintained linearly and the unstable pilot pressure can be prevented. By doing so, it is possible to avoid vehicle height variation and noise generation due to abnormal operation of the spool valve (93).

[Brief description of drawings]

FIG. 1 is a block diagram showing a hydraulic circuit of a suspension control device according to an embodiment of the present invention. 2, 3, 4, 5, 6 and 7 are respectively the suspension 100fr, pressure control valve 80fr, cut valve 70fr, relief valve 60fr and main check shown in FIG. FIG. 3 is an enlarged vertical sectional view of a valve 50 and a bypass valve 120. 8a and 8b are block diagrams showing a configuration of an electric control system for controlling the suspension control device shown in FIG. 9a and 9b are flowcharts showing the control operation of the microprocessor 17 shown in FIG. Figures 10a, 10b, 10c, 10d and 10e
9 is a flowchart showing the contents of the subroutine shown in FIG. 9b. 11a and 11b are graphs showing the contents of data written in the internal ROM of the CPU 17. 1: Pump, 2: Reservoir, 3: High pressure port 4: Attenuator, 6: Front wheel high pressure supply pipe, 7: Accumulator 8: High pressure supply pipe, 9: Rear wheel high pressure supply pipe, 10: Accumulator 11: Reservoir return pipe, 12 : Drain return pipe 13f _L , 13fr, 13r _L , 13rr, 13rm, 13rt: Pressure sensor 14f _L , 14fr, 14r _L , 14rr: Air release drain 15f _L , 15fr, 15r _L , 15rr: Vehicle height sensor, 16p, 16r: Accelerometer 17, 18: Microprocessor, 19: Battery 50: Main check valve 51: Valve base, 52: Input port, 52: Output port 54: Valve seat, 55: Flow 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: 1st guide 65: Filter, 66: Valve body, 67: 2nd guide 68 : Valve body, 69: Compression coil spring 60m: Main relief valve 70fr, 70f _L , 70rr, 70r _L : Cut valve 71: Valve base, 72: Line pressure port, 7 3: Pressure adjusting input port 74: Oil discharge port, 75: Output port, 76: 1st guide 77: Guide, 78: Spool 79: Compression coil spring 80fr, 80f _L , 80rr, 80r _L : Pressure control valve 81: Sleeve , 82: Line pressure port, 83: Groove 84: Output port, 85: Low pressure port, 86: Groove 87: High pressure port, 88: Target pressure space, 88f: Orifice 89: Low pressure port, 90: Spool, 91: Groove 92 : Compression coil spring, 93: Valve body 94: Flow path, 95: Needle valve, 96: Fixed core 97: Plunger, 98a: Yoke, 98b: End plate 98c: Low pressure port, 100fr, 100f _L , 100rr, 100r _L : Suspension 101fr, 101f _L , 101rr, 101r _L : Shock absorber 102fr, 102f _L , 102rr, 102r _L : Piston rod 103: Piston, 104: Inner cylinder, 105: Upper chamber 106: Lower chamber, 107: Side opening, 108: Vertical through port 109: Damping valve device, 110: Lower space, 111: Piston 112: Lower chamber, 113: Upper chamber, 114: Outer cylinder 120: Bypass valve, 121: Input port 122: Low pressure port, 122a: Low pressure port , 122b: flow path 123: first guide, 124a: valve body 124b: compression coil spring, 125: needle valve 150: A / D conversion unit 170: duty control unit (duty controller) 180: current detection unit, 190.200: driver RY: Relay, SW1: Ignition switch SW2: Vehicle speed sensor (lead switch) SW3: Stop lamp switch, SW4: Door switch SW5: Reservoir level warning switch SW6: Vehicle height adjustment switch, SN1: Steering sensor SN2: Throttle sensor SOL1 ~ SOL5: Solenoid

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kunihito Sato 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd. (72) Inventor Toshio Yutani, 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd. (72) Inventor Takashi Yonekawa 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. (72) Inventor Shuichi Takeuma 1 Toyota Town, Toyota City, Aichi Toyota Motor Co., Ltd. Shogo Oshima (56) References JP-A-63-212116 (JP, A) JP-A-63-46910 (JP, A) JP-A 1-249509 (JP, A)

Claims (1)

[Claims] 1. A suspension mechanism including an actuator that expands and contracts according to the supply and discharge of fluid, a vehicle height detecting unit that detects a vehicle height change due to expansion and contraction of the actuator, and a pressure source unit that generates a fluid pressure supplied to the actuator. ，
Pressure control valve means interposed between the actuator and the pressure source means for adjusting the pressure supplied to the actuator to a pressure corresponding to a command value to be applied, and an actual vehicle detected by the vehicle height detection means In a suspension control device, which comprises a control means for calculating a target pressure of the actuator based on a height and a target vehicle height and applying a command value corresponding to the target pressure to the pressure control valve means: a vehicle speed detecting means for detecting a vehicle speed A pressure detecting means for detecting the pressure on the output side of the pressure source means, and correcting the target pressure of the actuator so as to suppress a variation in vehicle height due to a change in the pressure detected by the pressure detecting means. , The correction value is changed according to the vehicle speed detected by the vehicle speed detecting means, and the vehicle speed detected by the vehicle speed detecting means is greater than a predetermined vehicle speed. A suspension control device comprising: an electronic control means for making the correction value substantially zero when the value is large.