JPH0370619A - Suspension control device - Google Patents

Abstract

PURPOSE:To prevent production of a rapid change in a ground clearance by a method where in a ground clearance is regulated according to an acceleration control amount based on at least the differential component of detection acceleration, and when abnormality of an acceleration detecting means is detected, the control amount is gradually decreased together with a time CONSTITUTION:In a title device, pressure control valves 80fL - 80rr are connected to front and rear wheel high pressure feed pipes 6 and 9 branched from a high pressure feed pipe 8 connected to the portion on the delivery side of a hydraulic pump 1, and a line pressure regulated by the pressure control valves is fed to front and rear wheel suspensions 100fL - 100rr through cut valves 70fL - 70rr. In this case, acceleration of a car body is detected by an acceleration detecting means, and a control amount of the pressure control valves 80fL - 80rr is determined according to an acceleration control amount based on at least the differential component of detected acceleration. When abnormality of an acceleration detecting means is detected, the value of an acceleration control amount available before the presence of abnormality is detected produces an initial value and is gradually reduced together with a time, and a value near zero is set as an acceleration control amount available after the occurrence of abnormality.

Description

[Detailed Description of the Invention] [Object of the Invention] [Industrial Field of Application] The present invention relates to a suspension control device used in a vehicle, and particularly relates to a suspension control device for use in a vehicle. The present invention relates to a suspension control device that controls the pressure of a shock absorber according to the detected posture and acceleration.

[Prior Art] For example, Japanese Patent Laid-Open No. 63-106133 discloses a method for determining a turning pattern of a vehicle from a steering angle and a steering angular velocity.

Suspension pressure control during cornering has been proposed in which the control gain is changed in response to this and the shock absorber pressure is determined in accordance with the gain and the lateral acceleration of the vehicle.

[Problems to be Solved by the Invention] In a suspension control device that performs pressure control according to the detected value of an acceleration sensor, if the acceleration sensor fails, abnormal control may be performed or the occupants of the vehicle may receive a large shock when the acceleration sensor fails. Sometimes I feel that.

For example, in a suspension control device that performs PD control in order to improve control responsiveness, a control amount (P term) proportional to the acceleration output by an acceleration sensor and a control amount (D term) corresponding to the differential value of acceleration are used. ), but if an open or short circuit occurs in the acceleration sensor circuit, the output of the sensor will suddenly drop to zero, the maximum value, or
or - change to maximum value. In this case, since the instantaneous amount of change in the detected acceleration is very large, the control amount corresponding to the D term temporarily becomes extremely large, which causes a sudden change in control pressure and transmits a shock to the occupant.

If the control gain for the value of the D term is made small, the above-mentioned shock can be reduced, but the high-speed responsiveness of suspension control will deteriorate, resulting in a decline in the performance of attitude maintenance control when sudden changes in acceleration occur. do.

The present invention provides a means for detecting acceleration when an abnormality occurs in the means for detecting acceleration.
It is an object of the present invention to provide a suspension control device that prevents the appearance of shock and has good high-speed response.

[Components of the invention [Means to solve the problem] In order to solve the above problems, in the present invention.

A suspension mechanism including an actuator that expands and contracts in accordance with supply and discharge of fluid; Acceleration detection means for detecting acceleration of a vehicle body supported by the suspension mechanism; Pressure source means for supplying fluid to the actuator; From the pressure source means to the actuator. adjustment valve means for controlling the supply of fluid to; and a control amount of the adjustment valve means in accordance with an acceleration control amount based on at least a differential component of the acceleration detected by the acceleration detection means, so that the vehicle body attitude approaches the horizontal direction; At the same time, the presence or absence of an abnormality in the acceleration detecting means is identified, and when the presence of an abnormality is identified, the value of the acceleration control amount before detecting the presence of an abnormality is set as an initial value, and gradually decreases over time until it reaches zero. Set the approaching value as the acceleration control amount after an abnormality occurs. Electronic control means: shall be provided.

[Operation] According to the present invention, when an abnormality in the acceleration detection means is detected, the subsequent acceleration control amount is generated based on the normal acceleration control amount before the abnormality is detected, and the value changes over time. It gradually decreases and approaches O. Therefore, even if the detected acceleration becomes abnormal due to an abnormality in the acceleration detection means and its differential value becomes an abnormally large value, this effect will not appear on the acceleration control amount at all. Further, in this case, the change in the acceleration control amount is gradual, and no sudden change appears in the control pressure, so there is no fear that the occupants of the vehicle will feel a shock.

Other objects and features of the present invention will become clear from the following description of an embodiment with reference to one drawing.

[Example] FIG. 1 shows an outline of the mechanism of an automobile suspension device embodying the present invention. Hydraulic pump l.

This is a radial pump, which is disposed in the engine room and connected by a belt to the drive output of the vehicle engine (not shown). When driven to rotate, it sucks oil from the reservoir 2, and at a rotational speed of a predetermined speed or higher, Oil is discharged to the high pressure port 3 at a predetermined flow rate.

High pressure port 3 of radial pump for suspension pressure supply
An accumulator 4° main check valve 50 and a relief valve 6011 for absorbing pulsation are connected to the main check valve 50, and high pressure oil in 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 oil from flowing back from the high pressure supply pipe 8 to the high pressure port 3 when the pressure in the high pressure port 3 is lower than the pressure in the high pressure supply pipe 8.

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

The high pressure feed pipe 8 has a front axle suspension 100f and 10
A front wheel high pressure supply pipe 6 for supplying high pressure to 0fr communicates with a rear wheel high pressure supply pipe 9 for supplying high pressure to the rear wheel suspension 100r and 100rr, and an accumulator 7 is connected to the front wheel high pressure supply pipe 6. (for front axle).

An accumulator 10 (for rear wheels) is connected to the rear wheel high pressure supply pipe 9.

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

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

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

The relief valve 60fr is even better.

When the front right wheel is thrust up from the road surface and the internal pressure of the shock absorber 101fr rises shockingly, this Wf shock is cushioned from propagation to the pressure control valve 80fr, and the internal pressure of the shock absorber 101fr rises shockingly. When the internal pressure of the shock absorber 101fr rises to
It is discharged into the reservoir return pipe 11 via the piston rod 100fr and the cut valve.

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

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

A vehicle height sensor 15fr is attached to the vehicle body near the suspension 100fr, and a link connected to the rotor of the 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 (the height of the vehicle body relative to the wheel).
occurs.

Pressure control valve 80fL and cut valve 70 similar to the above
fL, relief valve 60ft, y vehicle height sensor 15f
Similarly, the pressure control valve 80fL is connected to the front wheel high pressure supply pipe 6 to maintain the required pressure (support pressure). Suspension 100fL shock absorber 10], fL piston rod 10
Give it after 2f.

Pressure control valve 80rr l cut valve 7 similar to the above
0rr, relief valve 60rr, vehicle height sensor 15
Similarly, a pressure sensor 13rr and a pressure sensor 13rr are assigned to the rear right wheel suspension IQOrr, and a pressure control valve 80rr is connected to the rear wheel high pressure supply pipe 9 to apply the required pressure (support pressure) to the suspension. 100rr shock absorber 101rr piston rod 102
Give to rr.

Furthermore, the same pressure control valve 80r, cut valve 70rL, relief valve 60rt + vehicle height sensor 15 are installed.
Similarly, a pressure sensor 13rL and a pressure sensor 13rL are assigned to the front left wheel suspension 100rL, and a pressure control valve 80rL is connected to the rear wheel high-pressure supply pipe 9 to maintain the required pressure (support pressure). Suspension 100rL
Shock absorber 1.01rL piston rod 1
Give to 02rL.

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

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

On the other hand, the pressure of the reservoir return pipe 11 is lowest at the end on the reservoir 2 side, and the further away from the reservoir 2 the pressure is.

Since the pressure tends to increase, the reservoir return pipe 1
The pressure No. 1 is also detected on the rear wheel side by a pressure sensor 13rt.

A bypass valve 120 is connected to the rear wheel high pressure supply pipe 9. This bypass valve 120 regulates the pressure of the high-pressure supply pipe 8 to a pressure corresponding to the current value of the electric coil (obtains the required line pressure). Also, the ignition switch is opened (engine stops: pump 1 stops)
When this happens, the line pressure is reduced to substantially zero (atmospheric pressure in the reservoir 2 through the reservoir return pipe 11) (this decrease in line pressure causes the cut valves 70fr and 70fL to close.

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

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

Suspension support pressure (hydraulic pressure) is supplied to the piston rod 102fr from the output port of the cut valve 70fr, and this pressure is applied to the side port 10 of the piston rod 102fr.
7, it joins the upper chamber 105 in the inner cylinder 1'04, and furthermore, it joins the lower chamber 1 through the upper and lower through holes 108 of the piston 103.
Join 06. This pressure and the piston rod 102fr
A support pressure proportional to the product of the cross-sectional area (Xπ squared of the rod radius) is applied to the piston rod 102fr.

The lower chamber 106 of the inner cylinder 104 communicates with the lower chamber 110 of the damping valve assembly M2O3. The upper space of the damping valve system [109 is
It is divided into a lower chamber 112 and an upper chamber 113 by a piston 111, and oil in the lower chamber 110 flows through the lower chamber 112 through a damping valve system M2O3, but high pressure gas is sealed in the upper chamber 113. .

When the piston rod 102fr tries to relatively rapidly enter the lower part of the inner cylinder 104 due to the thrust upward movement of the front right axle, the internal pressure of the inner cylinder 104 suddenly increases, and the pressure in the lower chamber 110 similarly decreases. The pressure of the chamber 112 tends to rise rapidly. At this time, the oil is transferred to the lower chamber through the check valve of the damping valve device 109 that allows the oil to flow from the lower chamber 110 to the lower chamber 112 at a predetermined pressure difference or higher, but blocks the flow in the opposite direction. It flows from the space 110 to the lower chamber 112, which causes the piston 111 to rise and buffer the impact (upward) applied from the wheels from propagating to the piston rod 102fr. In other words, the propagation of wheel impact (improvement) to the vehicle body is buffered.

When the piston rod 102fr relatively tries to come out above the inner cylinder 104 due to the sudden fall of the front right wheel, the internal pressure of the inner cylinder 104 suddenly decreases and the lower chamber space 1
10 is about to suddenly become lower than the pressure in the lower chamber 112. At this time, oil flows into the lower chamber through a check valve of the damping valve device 109 that allows oil to flow from the lower chamber 112 to the lower chamber space 110 at a predetermined pressure difference or higher, but blocks flow in the opposite direction. Flows from 112 to the lower chamber 110.

As a result, the piston 111 descends and the impact is applied from the wheels! ! ! 6J to (downward) piston rod 102fr
Multiply t by 1t1. That is, the propagation of the wheel impact (falling down) to the vehicle body is buffered.

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

Piston rod 102 against inner cylinder 104, such as when parked
When there is no relative vertical movement of fr, the seal between the inner cylinder 104 and the piston rod 102fr allows the inner cylinder 10
4, there is virtually no oil leakage into the outer cylinder 114. However, in order to reduce the vertical movement load on the piston rod 102fr, the seal is designed to have sealing characteristics that cause a slight oil leak when the piston rod 102fr moves up and down. The oil leaking into the outer cylinder 114 is returned to the reservoir 2 through the outer cylinder 114, through the drain 14fr (Fig. 1) which is open to the atmosphere, and through the drain return pipe 12 (Fig. 1) which is a second return pipe. The reservoir 2 is equipped with a level sensor 28 (FIG. 1), and when the oil level in the reservoir 2 is below the lower limit, the level sensor 28 generates a signal (oil shortage signal) indicating this.

Other suspensions 100fLs 100rr and 1
The structure of 00rL is also substantially the same as that of the suspension 100fr described above.

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

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

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

The pressure of the target pressure space 88 communicating with the high pressure boat 87 via the orifice 88f is applied to the right end surface of the spool 90, and due to this pressure, the spool 90 receives a force that drives it to the left. Line pressure is supplied to the high pressure port 87 , and the target pressure space 88 communicates with the low pressure boat 89 through a flow path 94 , and a needle valve 95 defines a communication opening of this flow path 94 . When the needle valve 95 closes the flow path 94, the high pressure port 87 is opened via the orifice 88f.
The pressure in the target pressure space 88 communicated with the high pressure port 87 becomes the pressure (line pressure), and the spool 90 is driven to the left, whereby the groove 91 of the spool 90 communicates with the groove 83 (line pressure port 82). and groove 91 (output port 84)
The pressure increases, and this is transmitted to the left side of the valve body 93, giving a rightward driving force to the left end of the spool 90. needle valve 95
When the flow path 94 is fully opened, the pressure in the target pressure space 88 is narrowed by the orifice 88f, so it is significantly lower than the pressure (line pressure) in the high pressure port 87, and the spool 90 moves to the right. Accordingly, the groove 9 of the spool 90
1 communicates with the groove 86 (low-pressure boat 85), the pressure in the groove 91 (output port 84) decreases, this is transmitted to the left of the valve body 93, and the rightward driving force of the left end of the spool 90 decreases. In this way, the spool 90 is at 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 substantially proportional to the pressure in target pressure space 88 appears at output port 84 .

The pressure in the target pressure space 88 is determined by the position of the needle valve 95 and is substantially inversely proportional to the distance of the needle valve 95 with respect to the flow path 94. An inversely proportional pressure appears.

The needle valve 95 passes through the magnetic fixed core 9G. The right end of the fixed core 96 has a truncated conical shape.

A bottomed conical hole-shaped end surface of the magnetic plunger 97 faces this right end surface. A needle valve 95 is fixed to this plunger 97. The fixed core 96 and plunger 97 are inserted into the bobbin around which the electric coil 99 is wound.

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

As a result of the above, a pressure appears at the output port 84 that is substantially proportional to the WLm flow value of the electric coil 99.

This pressure control valve 80fr has one energizing current within a predetermined range.

A pressure proportional to the pressure is outputted to the output port 84.

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

A line pressure boat 72. Pressure regulation input boat 73. The oil drain boat 74 and the output port 75 are in communication. Line pressure port 7
2 and the pressure regulation input port 73 is a ring-shaped first guide 7.
6, and the pressure regulating input port 73 and output port 75 are separated by cylindrical guides 77a, 77b, and 77c. The oil drain boat 74 communicates with a ring-shaped groove on the outer periphery of the second guide 77c, and connects the second guides 77a, 77b.
and 77c, the return pipe 11
Return to

A spool 78 pushed leftward by a compression coil spring 79 passes through the first and second guides 76, 77a to 77c, and 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 projection 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 boat 74. When the line pressure is less than a predetermined low pressure, the spool 78 is driven to the leftmost side by the repulsive force of the compression coil spring 79, as shown in FIG. is the second guide 7
This is blocked by fully closing the inner opening of 7a. When the line pressure exceeds a predetermined low pressure, this pressure causes the spool 79 to resist the repulsive force of the compression coil spring 79.
begins to be driven to the right, and the spool 79 is positioned 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 regulation input port 73 communicates with the output port 75, and the line pressure (line pressure boat 72) rises to a predetermined low pressure, the cut valve 70fr is activated. , when the line pressure (boat 72) increases further by starting communication between the pressure regulation input port 73 (pressure regulation output of the pressure control valve 80fr) and the output port 75 (shock absorber z<1otfr), the pressure regulation input port 73
(pressure regulation output of pressure control valve 80fr) and output port 75 (
The shock absorber 101fr) is fully opened. When the line pressure decreases, the opposite is true, and when the line pressure falls below a predetermined low pressure, the output port 75 (shock absorber 101fr) is completely cut off from the pressure regulation input port 73 (pressure regulation output of the pressure control valve 80fr). Ru.

FIG. 5 shows an enlarged longitudinal section of the relief valve 60fr. An input port 2 and a low pressure boat 63 are opened in the valve housing hole of the valve base 61. A cylindrical first guide 64 and a second guide 67 are pushed into the valve storage hole, and the input port 2 communicates with the inner space of the first guide 64 through the filter 65. A valve body 66 having an orifice in the center is inserted into the first guide 64, and the valve body 66 is pushed to the left by a compression coil spring 66a. The space in the first guide 64 that accommodates the valve body 66 and the compression coil spring 66a is
It communicates with the input port 2 through the orifice of the spring seat 66b, and also communicates with the second guide 6 through the opening of the spring seat 66b.
It communicates with the inner space of 7. The conical valve body 68 is pushed to the left by the repulsive force of the compression coil spring 69, and the spring seat 6
The pressure (
When the control pressure) is less than a predetermined high pressure, the pressure in the storage space of the coil spring 66a, which communicates with the input port 2 through the orifice of the valve body 66,
Since the repulsion force of valve body 68 is relatively lower than that of valve body 9.

As shown in FIG. 5, the central opening of the valve seat 66b is closed, and therefore the output port 2 is cut off from the inner space of the second guide 67, which communicates with the low pressure boat 63 through the hole 67a. That is, the output port 2 is cut off from the low pressure boat 63.

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

In addition, if high pressure is applied to the input port 2.

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

FIG. 6 shows an enlarged longitudinal section of the main check valve 50. An input port 52 and an output port 53 communicate with a valve housing hole formed in the valve base 51. A cylindrical valve seat 54 with a bottom is housed in the valve housing hole, and a communication port 55 of the valve seat 54 is inserted into the valve seat 54.

The ball valve 57 pushed by the compression coil spring 56 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 and the flow is allowed to flow. Open the mouth 55. That is, oil flows from the input port 52 toward the output boat 53. However, when the pressure at the output port 53 is higher than the pressure at the input port 52, the ball valve 57 closes the communication port, so that oil does not flow from the output port 53 to the input port 52.

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

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

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

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

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

The relief valve 60m is the relief valve 60f mentioned above.
It has the same structure as r, but has a conical valve body (68:
The compression coil spring (69) that presses the input port (62) has a slightly small spring force.
(the pressure of the high pressure boat 3) is the pressure of the relief valve 60
The output port (62) is cut off from the low pressure boat (63) when fr is less than a predetermined high pressure, which is a pressure slightly lower than the pressure that releases the pressure of its input port 2 to the low pressure boat 63. When the pressure at the input port (62) exceeds a predetermined high pressure, the valve body (68) is driven to the rightmost direction. That is, the pressure of the input boat (62) is released to the low pressure port (63), and the pressure of the high pressure boat 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 boat 3 to the high pressure supply pipe 8, but prevents backflow from the high pressure supply pipe 8 to the high pressure boat 3. .

The relief valve 60m suppresses the pressure of the high-pressure boat 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 boat 3 rises shockingly, the pressure is suppressed to the return pipe 1
1 to buffer the propagation of impactive pressure to the high-pressure supply pipe 8.

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

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

The pressure control valves 80fr, 80ft-, 80rr, and 80r control the current value of the electric coil (99) so as to provide the required support pressure to the suspension by suspension pressure control, and output the required support pressure. Port (8
4) Output. When impact pressure from the suspension propagates to the output port (84), it is buffered and
Disturbance of the pressure control spool (91) (disturbance of output pressure)
suppress. In other words, the required pressure is stably applied to the suspension.

The cut valves 70fr, 70fL, 70rr, and 70r cut the suspension supply pressure line (the output port 84 of the pressure control valve and the suspension (between) to prevent pressure from escaping from the suspension, and when the line pressure is above a predetermined low pressure, the supply pressure line is fully open to flow. This automatically prevents an abnormal drop in suspension pressure when line pressure is low.

Relief valve 60fr, 60fL, 6Qrr, 60r
L limits the pressure (mainly suspension pressure) of the suspension supply pressure line (between the output port 84 of the pressure control valve and the suspension) to below the high pressure upper limit, and raises the wheel.
When there is a shocking pressure increase in the supply pressure line (suspension) due to loading heavy objects, etc., this pressure is released to the return pipe 11 to alleviate the shock of the suspension and also to the hydraulic line connected to the suspension and the Increase the durability of connected mechanical elements.

FIG. 8a shows the configuration of an electrical component that controls the hydraulic circuit shown in FIG. 1. Referring to FIG. 8a, this circuit is composed of a control unit ECU, various switches, various sensors, various solenoids, etc. connected to a large number of input terminals and output terminals of the control unit ECU.

First, the sensors will be explained. FL, FR.

Vehicle height sensors 15f and 15fr are placed near the shock absorbers at each position of RL and RR.

15rL and 15rr each output a signal according to the distance between the wheel at each position and the vehicle body, that is, the vehicle height at each position. Note that each vehicle height sensor detects vehicle height information in the form of a digital signal, but this information is converted into an analog voltage signal and output.

13fLy 13fr, 13rL and 13rr are pressure sensors arranged inside each of the shock absorbers FL, FR, RL and RR, respectively.

Outputs voltage (analog signal) according to each oil pressure.

13pm 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 output voltages (analog signals) according to the pressure at each position. Further, 16p and 16r are G sensors that output a voltage (analog signal) according to acceleration (G), 16p detects G in the longitudinal direction of the vehicle body, and 16r detects G in the lateral direction of the vehicle body, respectively.

SNI is the steering wheel time! This is a steering sensor that outputs a pulse signal according to the amount of lI, and outputs two-phase signals that are out of phase with each other.

RG is one output terminal of a regulator that stabilizes the output voltage of one 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 depending on the opening degree of the throttle valve. SW2 is a reed switch that detects the rotation of a permanent magnet connected to the speedometer cable.
Outputs pulses whose cycle changes according to vehicle speed.

Also, RY, SWI, SW3. SW4. SW5 and SW
6 are the main relay, ignition switch, stop lamp switch, door switch, and reservoir level warning switch, respectively.

and a vehicle height adjustment switch. 5OLI, 5OL2.
5OL3 and 5OL4 are the solenoids of the linear control valves (80fL, 80fr, 80r, and 80rr) provided in the hydraulic control units of FL, FR, RL, and RR, respectively, and 5OL5 is the 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, this control unit ECU includes two CPUs (microcomputers).
17,180. I10 expansion unit 130. Reset control unit 140. A/D conversion unit 150. Active filter unit 160. Duty control unit 170° Current detection unit 180. Driver 190,2
03, TL source 210. Backup power supply 220. Driver 230. and an input buffer 240.

Input terminals IG, SPD, SS of this control unit ECU
The signals applied to I and SS2 are input to the input ports PAO and AS of the CPU 17 via the input buffer 240, respectively.
Applied to RO, ASRI and ASR2. Furthermore, ASR
O-ASR2 is an interrupt request boat. In addition, input terminal IC:L.

LL, L2. L3. STP, DOOR, LOI
Information on the signals applied to L and HIGH is I10
The input port P of the CPU 17 via the expansion unit 130
Applied to A4 to PA7.

Vehicle height sensor 15fL, 15fr, 15rL, 15
rr.

Pressure sensor 13fL, 13fr, 13rLt
13rr.

13rm, 13rt:, and G sensor 16p, 16
Each analog signal outputted by r is passed through an active filter unit 160 to an A/D conversion unit 150.
is applied to each analog signal second input terminal.

Further, analog signals corresponding to the currents flowing through each of the solenoids SQL 1 to 5 OL 5 are 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 the digital signal. Information between CPU 18 and A/D conversion unit 150 is transmitted through serial output port SO and serial input port Si.

The value of the current flowing through the solenoids 5QL1 to 5OL5 of each electromagnetic valve is adjusted by pulse duty control (PWM). Pulses that control energization/off of each solenoid are generated by duty control unit 170. When the CPU 18 writes a predetermined instruction code and data for determining a duty value to the duty control unit 170, the duty control unit 170
A pulse with a duty according to the data is output to each output terminal. The driver 200 controls energization/off of each solenoid according to the H/L level of each pulse signal output by the duty control unit.

By the way, in this embodiment, the control unit ECU is equipped with two CPUs 17 and 18, and these two CPUs
control the operation of the entire system while exchanging information with each other. The CPUs 17 and 18 each have an 8-bit bidirectional input/output port (data bus) PB (PB7
~PBO), and these 8-bit ports are connected to each other via a signal line group 306. In addition, in this group of transmission lines 306, all eight lines are pulled up to the power supply line (+5 V) via the resistor array 305, and when the ports PB of two CPUs are in the input state at the same time. In this case, each line of the signal line 306 is all fixed at a high level H.

Data transmitted between CPUs 17 and 18 is.

The data is sent via the signal line group 306 in the form of 8-bit parallel data. Also, in order to synchronize the timing of sending and receiving this data, the two CPUs 17 and 18.

Furthermore, they are connected to each other by two control lines 307 and 308. The control line 307 connects the output port PA3 of the main side CPtJ17 and the interrupt request boat input IRP of the sub side CPU1B, and the other control line 307 connects the output port PA4 of the sub side CPU18. ,
Main side CPU 17 interrupt request input port IRP
connecting between.

The CPUs 17 and 18 store programs for controlling the pressure of each suspension. According to this program, the CPU 18 mainly controls the vehicle height sensor 15fL provided in the suspension system shown in FIG.
15fr, 15rL, 15rr and pressure sensor 13f
, 13fr, 13rL, 13rr, 13rm, 13r
t, reading of the detected values of the longitudinal acceleration sensor 16p and the lateral acceleration sensor 16r on the vehicle, and the pressure control valve 8.
The values of the current flowing to the electric coils (99, 129) of 0fL, 80fr, 80r, 80rr and the bypass valve 120 are controlled.

From when the ignition switch 20 is closed until it is opened and immediately after the ignition switch 20 is opened, the CPU 17 sets/cancels the line pressure of the suspension system (Fig. 1), determines the vehicle operating state, and processes the determination results. The system calculates the required pressure (the pressure that should be set for each suspension) to establish the corresponding appropriate vehicle height and body posture, receives various detected values from the CPU 18 in order to determine the vehicle driving state, and calculates the required pressure. The energizing current required for setting is CP
Give to U18.

Hereinafter, with reference to the flowcharts shown in Figure 9a et seq.
The control operations of the CPUs 17 and 18 will be explained. First, in order to make it easier to understand, we will explain the symbols assigned to the main registers allocated to the internal memory of the CPU 17 and the contents of the main data written to each register. A summary is shown in Table 1 below.

T t Warp target value Note that in the flowchart of the first drawing and the description below, the register symbol itself may mean the contents of the register.

Referring first to FIG. 9a. On-board battery 1 on its own
When power is supplied from 9 (step 1), CPU 17
sets internal registers, counters, timers, etc. to predetermined initial standby state contents, and outputs a signal level to the output port to set the initial standby state (no electrical energization of each mechanism element). (Step 2: Below in parentheses, words such as step and subroutine are omitted and only the symbols attached to them are written).

Next, the CPU 17 checks whether the ignition switch SWI is closed (3), and if it is open, waits for it to be closed. When the ignition switch SWl 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 relay RY is turned on, power supply circuit 2 is connected via the relay contact.
10 is connected to the battery 19, from then on, even if the ignition switch SWI is opened, the CPU 1
7 turns off relay RY, all of the electrical circuitry shown in FIG. 8 remains electrically energized and operational.

When the CPU 17 turns on the relay RY, it permits the execution of various interrupt processes that are executed in response to the arrival of the pulse signal to the interrupt input port ASRO-ASR2 (5).

Here, an outline of the pulse signal input to the input ports ASRO to ASR2 and the response interrupt processing will be explained. To explain 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,
When sensor SW2 generates one pulse, in response to this, the process proceeds to interrupt processing (ASR2), reads the contents of the vehicle speed clock register at that time, restarts the vehicle speed clock register, and calculates the read contents (vehicle speed synchronization pulse). Calculate the vehicle speed value based on the cycle), write the value Vs obtained by taking the weighted average with the previous vehicle speed calculation values held so far into the vehicle speed register vs, and return to the step immediately before proceeding to this interrupt process. (return). By executing this interrupt process (ASR2), data Vs indicating the vehicle speed at that time (time-series smoothed value of the vehicle speed calculation value) is always held in the vehicle speed register (S).

To explain the interrupt processing (input port ASRO) in response to the first set of generated pulses generated by the rotary encoder SNI for detecting the rotational direction of the steering shaft, this interrupt processing occurs at the rising and falling edges of the first set of generated pulses. Proceed to interrupt processing (ASRO).

When proceeding to interrupt processing (ASRO) in response to the rising edge, H is written to the flag register for determining the rotation direction,
When proceeding to interrupt processing (ASRO) in response to a falling edge, the flag register is cleared (note L) and the process returns to the step immediately before proceeding to this interrupt processing.

Note that when the rising edge of the second set of pulses appears next to the rising edge of the first set of pulses of the rotary encoder SNI (flag register H), the steering shaft is being driven to the left and the falling edge of the first set of pulses appears. When the rising edge of the second set of pulses appears next to (flag register=L), the steering shaft is driven to rotate clockwise.

To explain the interrupt processing (input port ASR1,) of the rotary encoder SNI for detecting the rotation speed (steering angular speed) of the steering shaft in response to the second set of generated pulses, the second set of pulses (falling edge) When this arrives, in response to this, proceed to interrupt processing (ASRl), read the contents of the steering timing register at that time, restart the steering timing register, and execute the read contents (period of the steering angular velocity synchronization pulse). If the content of the flag register for determining the rotation direction is H, a + (clockwise rotation) sign is added, and if the content of the flag register is L, a - (clockwise rotation) sign is added, and from there, Calculate the speed value (including directions + and -), and take the weighted average with the previous speed calculation values held up to that point, and enter the value Ss in the steering angular speed register S.
Write to S and return to the step immediately before proceeding to this interrupt process (return). By executing this interrupt processing (ASRI), data Ss(
+ means left rotation.

− indicates clockwise rotation) is maintained.

When the CPU 17 allows the above-mentioned interrupt processing, the CPU 17
18 is giving a ready signal (
6).

By the way, when the CPU 18 is powered on, it initializes itself, sets internal registers, counters, timers, etc. to the contents of the initial standby state, and outputs the initial standby state (each element of the mechanism) to the output port. (no electrical energization) (to the duty controller 170, data specifying that all electric coils are off) is output. Then, the highest current value data that causes the bypass valve 120 to be fully closed is given to the duty controller 170, and the bypass valve 120 is closed.
Instructs to energize. With the above settings, pressure control valve 8
For 0fL, 80fr, 80r, and 80rr, the current value is zero, and the pressure of the return pipe 11 is output to the output port (84), but the bypass valve 120 is fully open, and the pump l is not running while the engine is rotating. The high pressure supply pipe 8. is driven to rotate. Front wheel high pressure supply pipe 6 (accumulator 7)
And the pressure in the rear wheel high pressure supply pipe 9 (Accu I, L/-310) begins to rise.

Thereafter, the CPU 18 controls the vehicle height sensor 15 at the first setting cycle.
f, 15fr, 15rL, 15rr, pressure sensor 1
3fL.

13fr, 13rL, 13rr, 13rm, 13rt,
Acceleration sensor 16p.

Detection value of 16r and solenoid 5QLI to 5O
Each current detection value of L5 is read and updated and written to the internal register, and when the CPU 17 requests transfer of the detection data, the data in the internal register at that time is transferred to the CPU 17.
Transfer to.

In addition, the CPU 17 controls the pressure control valves 80fL and 80fr.
.

When energizing current target value data for each of 80rL, 80rr and bypass valve 120 is sent, each control duty value is generated based on each of these target values and the corresponding current detection value of solenoids 5QLI to 5OL5. death,
These are given to the duty controller 170.

Now, when the CPU 18 has given a busy signal in the check at step 6.7, the CPU 17 waits there and executes the standby processing (8 to 11). In standby processing (8), the presence or absence of an abnormality is determined by referring to the pressure detection values of all pressure sensors, the current detection values of all solenoids, and the vehicle height detection values of all vehicle height sensors, and suspension control is performed during standby (stopping). Perform pressure settings (de-energize the bypass valve 120 and fully open it, de-energize the pressure control valve),
When an abnormality is determined, notification and pressure settings corresponding to the abnormality (bypass valve 120 de-energized, pressure control valve de-energized) are performed (10). If no abnormality is determined, the abnormality processing is canceled (the abnormality notification is cleared) (11).

Now, when the CPU 18 outputs ready, the above-mentioned abnormal process (which may not be executed) should be canceled.12)
, the above-mentioned standby process (which may not be executed in some cases) is canceled (13).

Then, the CPU 17 sends the pressure sensor 13 to the CPU 18.
Instruct the transfer of the detected pressure data Dph of rm, receive it, and write it to the register DPH (14), so that the detected pressure (rear wheel side pressure of high pressure supply pipe 8) Dph is set to a predetermined value Pph (cut valve 70fL, 70fr, Check whether the line pressure has risen to a certain extent (15),
If the line pressure has not risen, return to step 6.

When the line pressure rises, the CPU 17 sends the detected pressure (initial pressure) data PfLO, Pfro tPrLo of the pressure sensors 13fL, 13fr, 13rL, and 13rr to the CPU 18.
Instruct the transfer of +PrrO, receive these, and register P F L 6 # P F Rot P R L o
*Write to PRRo (16).

And one area (table 1) of the internal ROM.

The N1 current value data required to obtain the required pressure is stored in the register P F LO t P F RO # P RL (
1r P RRo contents PfLt3 , Pfro , P
r1- o , Prr (accessed with 1, pressure PfL
The flow value ILFt to the solenoid (1hfL) required to output o to the output port 84 of the pressure control valve 80fL, the flow value Ihfr (fftR flow value Ihfr, the pressure PrLl) required to output the pressure Pfrq to the output port of the pressure control valve 80fr. The current value IhrL required to output the pressure Prro to the output port of the pressure control valve 80rL, and the current value I required to output the pressure Prro to the output port of the pressure control valve 80rr.
hrr, is read from table 1 and written to output registers IHfL, IHfr, IHr and IHrr (17), and the data of these output registers are written to CP.
Transfer to U18. The CPU 18 uses these data as a current target value, generates a duty value that makes them equal based on this data and the detected solenoid current value, and provides the value to the duty controller 170.

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

Depending on the current setting (target value) at this time, the pressure control valve 80f
L, 80fr, 80r, and 80rr are each substantially PfLo when the line pressure is higher than the predetermined low pressure.
.

The pressure of PfropPrLo*Prro is output to the output port)-(84), and in response to the rise of the line pressure to a predetermined low pressure or higher, the cut valve 70f is activated.
, 70r, and when 70rr opens, the pressure (initial pressure) of each suspension at that time PfLo +Pfr
A pressure substantially equal to o +PrLo tPrro applies to cut valves 70f, 70fr, and 70r.

Pressure control valve 80fL through 70rr, 80fr,
80rL, suspension 100fL from 80rr,
100fr, 100r.

Supplied to 100rr.

Therefore, the ignition switch SWI changes from a state (engine stopped: pump 1 stopped) to a closed state (pump 1 driven),
First cut valve 70f, 70fr, 70rc.

70rr is opened (line pressure is above 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 substantially equal, and sudden pressure fluctuations in the suspension occur. does not occur. In other words, no shocking change in the vehicle body attitude occurs.

The above is the pressure control valve 8 when the ignition switch SWI is switched from open to closed (immediately after starting the engine).
The initial output pressure settings are 0fL, 80fr, 80r, and 80rr.

Next, the CPU 17 starts a timer ST with an ST time limit.

ST is the contents of register ST, and register ST contains:
Data ST indicating a second set cycle that is longer than the first set cycle in which the CPU 18 reads detected values is written.

When the timer ST is started, the CPU 17 reads the status (
20). In this case, the open/close signal of the ignition switch SW2, the open/close signal of the brake pedal depression detection switch SW3, the absolute encoder SNI
The throttle opening data and the signal from the reservoir level detection switch SW5 are read and written to the internal register, and the CPU 18 is instructed to transfer the detection data to the vehicle height sensor 15f, 154r, 15rL, 15rr.
Vehicle height detection data DfL, Dfr, DrL, Dr
r, pressure sensor 13fL.

13fr, 13rL, 13rr, 13rm, 1
3rt pressure detection data PfL, Pfr, PrL,
Prr, Prm, PrL, and pressure control valve and bypass valve 80fLg 80fr.

Receives the transfer of the current value detection data of 80rL, 80rr, and 120 and writes it to the internal register.

Then, by referring to these read values, it is determined whether it is abnormal or normal, and if it is abnormal, the process proceeds to step 8.

In the case of normality, the CPU 17 performs primary line pressure control (LP
Execute C). In this case, the absolute value and polarity (high/low) of the deviation of the detection line pressure Prra from the reference pressure (a fixed value slightly lower than the relief pressure (predetermined high pressure) of the relief valve 60m) are calculated, and the current bypass valve 120 is A correction value corresponding to the deviation to make the deviation zero is added to the flowing current value of 1 tft to calculate the current value of current energizing the bypass valve 120, and this is written in the output register. In addition,
The contents of this output register are determined in step 36, which will be described later.
Transfer to CPU 18.

By this line pressure control J (LPG), the flow value of the bypass valve 120 is adjusted so that the pressure in the rear wheel high pressure supply pipe 9 becomes a predetermined value that is slightly lower than the relief pressure (predetermined high pressure) of the relief valve 60m. It will have to be controlled.

Reference is now made to Figure 9b. Above line pressure control (LPC)
After completing the process, the CPU 17 checks whether the switch 20 is open or closed (22), and if it is open, the CPU 17 executes the stop process (22).
23), turn off the relay 22, and turn off the interrupt AS.
RO~^SR2 is prohibited. In the stop process (23), first the bypass valve 120 is de-energized and fully opened (
line pressure is released to the return pipe 11).

Switch SW1 opens (engine stops: pump 1 stops), high pressure discharge from pump 1 stops, and bypass valve 120
As the high pressure supply pipe 8. is fully opened, the high pressure supply pipe 8. The pressure of the front wheel high pressure supply pipe 6 (accumulator 7) and the rear wheel high pressure supply pipe 9 (accumulator 10) becomes the pressure of the return pipe 11, and the pressure of the return pipe 11 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. has cut valves 70fL, 70fr, 70r, and 70rr.
At the timing when the pressure reaches a predetermined low pressure or lower that changes to complete shutoff, the CPU 17 closes the pressure control valve 80fLg 80f.
rt 80rL*80rr is de-energized.

Now, when the switch SWI is closed, parameters indicating the vehicle running state are calculated (25).

That is, the content SS of the steering angular speed register SS is read and [throttle opening degree TP read this time, read in subroutine 20 - throttle opening degree read last time)=Ts(
throttle opening/closing speed) is calculated and written to register TS.

Next, the CPU 17 executes the vehicle height deviation calculation J (31) to calculate the suspension pressure correction amount (first correction amount: each (for each suspension).The details of this will be described later with reference to FIG. 10a.

The CPU 17 executes "Pitching/Rolling Prediction Calculation J (32)" next to "Vehicle Height Deviation Calculation J (31)",
The suspension pressure correction amount (first and second correction amount: for each suspension) corresponding to the vertical and lateral acceleration actually applied to the vehicle body is calculated, and [suspension initial pressure (Pfl-0
, Pfr(1+PrLo,Prr+))+first correction amount 10 second correction amount) (!Output intermediate value: for each suspension) is calculated. Details of this content.

This will be described later with reference to FIG. 10b.

Next, the CPU 17 executes "pressure correction J (33),
The "calculated intermediate value" is corrected in accordance with the line pressure (high pressure) detected by the pressure sensor 13r1m and the return pressure (low pressure) detected by the pressure sensor 13rt. Details of this will be described later with reference to FIG. 10c.

Next, the CPU 17 uses the pressure/current conversion J (34) to convert the corrected "calculated intermediate value" (for each suspension) into the pressure control valve (80f L t 80fr + 80r
L 180rr ). The details will be described later with reference to FIG. 10d.

Next, the CPU 17 calculates the warp correction value (35) corresponding to the lateral acceleration Rg and the steering speed Ss. Add value.

Details of this will be described later with reference to FIG. 10e.

Next, the CPU 17 transfers the current value that should be passed through the pressure control valves, which is calculated as 1 or more at the output J (36), to the CPU 18 for each pressure control valve. The current value to be passed through the bypass valve 120 calculated by J (LPC) is transferred to the CPU 18 as directed to the bypass valve 120.

At this point, the CPU 17 has completed all tasks included in one cycle of suspension pressure control.

Therefore, we wait for the timer ST to time out (3
7), when the tie is 11 over.

Return to step 19, restart timer ST,
Perform the task of suspension pressure control for the next cycle.

As a result of the suspension pressure control operation of the CPU 17 described above, the CPU 1g is requested (subroutine 20) to transfer the sensor detection value at the ST same period 21a fixed period), and in response, the CPU 18 The sensor detection value data, which is read at one set cycle and has been read several times in the past and has been smoothed with a weighted average, is transferred to the CPU 17. In addition, the CPU 18 is transferred from the CPU 17 with the current value data to be passed through the ST same cycle, each of the pressure control valves, and the bypass valve 120, and each time the CPU 18 receives this transfer, the current value data and the current value data of the solenoid are transferred. A duty value is calculated from the detected current value and outputted to the duty controller 170. Therefore, the current value of each of the pressure control valves and the bypass valve 120 is S
Update T to approach the target current value in the same period.

Referring to FIG. 10a, to explain the contents of "vehicle height deviation calculation J (31)," first, the outline is as follows: The vehicle height sensor 15f calculates the detected vehicle height values D of 15fr, 15rL, and 15rr.
fL.

Dfr, Dr+-, Drr (registers DFL, DF
R.

DRL, DRR contents), heap (height) DHT, pitch (difference between front wheel side vehicle height and rear wheel side vehicle height) DPT, roll (right wheel side vehicle height and left wheel side vehicle height) of the entire vehicle body. Difference)D
RT and warp (the difference between the sum of the front right wheel vehicle height and the rear left wheel vehicle height and the sum of the front right wheel vehicle height and the rear right wheel vehicle height) DWT are calculated. In other words, each wheel vehicle height (register DFL, DFR
, D.R.L.

DRR contents) and attitude parameters for the entire vehicle body (
Heap DHT, Pitch DPT, Roll DRT and Warp DWT).

DHT = DFL + DFR + DRL + DRR.

DPT=-(DFL+DFR)+(DRL+DRR).

DRT= (DFL-DFR)+(DRL-DRR)
.

DWT= (DFL-DFR)-(DRL-DRR)
It is. The calculation of DPT is executed by "Calculation of pitching error cp J (51), the calculation of DRT is executed by "Calculation of rolling error CR (52), and the calculation of DWT is executed by calculation of r warp knee y - CW (7) Execute with J(53).

Then, in "Calculation of heap error CH (50), the target heap Ht is derived from the vehicle speed Vs, and the calculated heap D
Calculate the heap error amount for the target heap H of HT, perform PID processing on the calculated heap error amount for PID (proportional, integral, differential) control, and calculate the heap correction @cH corresponding to the heap error. .

Similarly, in "Calculation of pitching error CP J (51),
Deriving the target pitch Pt from the longitudinal acceleration Pg, calculating the pitch error amount of the calculated pitch DPT with respect to the target pitch P. For PID (proportional, integral, differential) control, calculate the calculated pitch error amount as PID. Processing is performed to calculate the pitch correction amount CP corresponding to the pitch error.

Similarly, in "Calculation of rolling error CR (52), the target roll R is derived from the lateral acceleration Rg, and the roll error amount of the calculated roll DRT with respect to the target roll Rt is calculated and PID (proportional, integral, differential ) for control,
The calculated roll error amount is subjected to PID processing to calculate a roll correction ff1CR corresponding to the roll error.

Similarly, in "Warp error-corresponding calculation J (53), the target warp Wt is set to zero, and the calculated two 10111 guns,
Calculate the warp error amount for the target warp WL, and
D (proportional, integral, ?I1 minute) For control, the calculated warp error amount is subjected to PIDID processing, and a warp correction amount CW corresponding to the warp error is calculated. Note that when the absolute value of the calculated warp error amount (DWT because the target warp is zero) is less than a predetermined value (within the allowable range), the PID
The amount of warp error to be processed is set to zero, and the amount of warp error to be processed by PID when it exceeds a predetermined value is set to -DVT.

To explain in detail the contents of "Heap error correspondence calculation J (50)," the CPU 17 first reads the target heap HI' corresponding to the vehicle speed Vs from one area (table 2H) of the internal ROM and registers it in the heap target value register. Write to HT (39).

In Fig. 10a, "As shown in Table 2HJ, the target heap Ht4 associated with the vehicle speed Vs is a high value Hel at low speeds when the vehicle speed Vs is VsaKm/h or less, and when the vehicle speed Vs is VsbKm/h or more, Low value K at high speeds
h2, but in the range where Vg exceeds Vsa and is less than Vsb, the target value is linear with respect to vehicle speed Vs (a curve may be used)
is changing. Changing the target value linearly in this way is 1. For example, if the target value is below 1100 K/h, the target value is changed to H.
tj, 100m/h or higher, set the target value to t-rt, 2
If the switching is done in stages, Vs will reach 100 m.
/h, the target heap changes in large steps due to a slight speed change in Vs, and the vehicle height increases at high speed.
This is to prevent the vehicle from moving up and down significantly, resulting in poor vehicle height stability.

According to the settings in Table 2H above, the target value changes only slightly with a slight change in the vehicle speed Vs.
Changes in the vehicle height target value are slight, and vehicle height stability is improved.

In step 40, DFL + DFR + DRL +
Store the heap amount obtained by calculating DRR' in register D)IT.

Next, write the previously calculated heap error amount and write the contents of register EHT2 to register EHTI (41
), calculates the current heap error amount HT-DRT2, and writes this to register EHT2 (42). As described above, the previous heap error amount (before ST) is stored in the register EHTI, and the current heap error amount is stored in the register EHT2. Next, the CPU 17 writes the contents of the register ITH2, in which the error integral value up to the previous time has been written, to the register THI (43), and calculates the current PID correction amount ITh using the following equation.

ITh = Kh 1・EHT2 +Kh2・(EH
T2+Kh3・ITHI)+Kh4・Kh5・(EHT
2-EHTI)Khl・EHT2 is P of PID operation.
(proportional) term, Khl is the coefficient of the proportional term, E) IT2
is the content of register EHT2 (current heap error amount).

Kh2・(EHT2+Kh3・ITHI) is the I (integral) term, Kh2 is the coefficient of the integral term, and IT old is the integral value of the correction amount up to the previous time (the integral of the correction amount output from initial pressure settings 16 to 18) value), Kh3 is the current error amount EH
The weighting between T2 and the correction amount integral value ITold is a coefficient.

Kh4・Kh,・(EHT2− El+T1) is D(
The coefficients of the differential term are Kh4 and Kh5, but Kh4 uses a value associated with the vehicle speed Vg, and K
hs uses a value associated with the steering angular velocity Ss.

That is, from one area of the internal ROM (table 3H),
Vehicle speed correction coefficient K associated with the vehicle speed Vs at that time
h4, and read out the steering angular velocity correction coefficient Kh5 corresponding to the current steering angular velocity 'Js from an area of the internal ROM (table 4H), and calculate the product Kh4 and Kh5 as the coefficient of the differential term. do.

1st. As shown in Table 3HJ in the Oa diagram, the vehicle speed correction coefficient Kh4 has a larger value as the vehicle speed Vs becomes higher, and increases the weight of the differential term.This is because the differential term This is a correction term that tries to quickly bring it within the target value.

The higher the vehicle speed, the faster the vehicle height changes in response to disturbances.
It increases depending on the vehicle speed. On the other hand, when the vehicle speed Vs exceeds a certain level (Vsd Km/h or higher in Table 3H), the brake pedal is pressed/released and the accelerator pedal is pressed/released.
When deceleration, turning/returning due to steering wheel rotation, etc. occur suddenly, the change in the vehicle attitude becomes rapid and extremely large, and an excessive differential term that quickly compensates for such sudden attitude changes High control stability collapses. Therefore, the vehicle speed correction coefficient Kh4 in the table 3H changes more precisely when the vehicle speed Vs is low, and changes smaller as the vehicle speed Vs becomes higher.

That is, when the vehicle speed Vs is low, the weight of the differential term changes greatly with respect to changes in vehicle speed, but when the vehicle speed Vs is high, the weight of the differential term changes with respect to changes in vehicle speed.

As shown in "Table 4HJ" in FIG. This is a correction term that attempts to quickly bring the change into the target value with respect to changes in the steering angle speed Ss.The higher the steering angular speed Ss is, the faster the vehicle height changes in response to disturbances, so it is increased according to the steering angular speed. When the angular velocity Ss is below a certain level (Ssa"/■sec in Table 4H), the change in the direction of travel is extremely gradual and the weighting of the differential term is small; when it exceeds Ssa and Ssb" is below 7m5ec, it is substantially proportional to the steering angular velocity Ss. A change in vehicle height appears at the same speed.S
At steering angular speeds greater than sb, the change in vehicle body attitude becomes rapid and extremely large, and an excessively large differential term that quickly compensates for such a sudden attitude change is dangerous because the vehicle height control stability deteriorates6. Therefore, the coefficient Kh5 of the differential term corresponding to the steering angular velocity Ss is a constant value when Ss is less than Ssa, a high value that is substantially proportional to Ss when it exceeds Ssa and less than Sab, and when it exceeds Ssb, it is the same value as when Ssb. It is set as a constant value.

The differential term Kh, ・Kh5・(HHT2−
With the introduction of EHTI), the coefficient Kh4
By increasing the coefficient Kh corresponding to the vehicle speed Vs and increasing the coefficient Kh corresponding to the steering angular speed Ss, differential control with weighting corresponding to the vehicle speed Vg and the steering angular speed Ss is realized.
Highly stable vehicle height control is achieved with respect to fluctuations in vehicle speed Vg and steering angular speed Vs.

In step 44, the values of the proportional term, integral term, and differential term of the PTD calculation are added, and the result is determined as the heap error correction amount ITh.

Next, the CPU 17 calculates the calculated heap error correction amount ITh.
is written to the register ITH2 (45), and is multiplied by the weighting coefficient Kh6 of the heap error correction amount (weighting for the pitch error correction amount, roll error correction amount, and warp error correction amount described later: contribution ratio in the total correction amount). and writes it to the heap error register CH.

When the heap error CH calculation W (50) is executed as described above, the CPU 17 executes the "pitching error CP calculation J".
Execute (51), calculate the pitch error correction amount CP in the same way as the heap error CH, and calculate the pitch error correction amount CP in the pitch error register C.
Write to P. In this case, the pitch target value PT corresponding to the heap target value HT is stored in the internal ROM of the CPU 17.
From one area (table 2P), the longitudinal acceleration Pg at that time
The data Pt (target value according to the longitudinal acceleration pg) corresponding to the acceleration pg is read out and obtained.

FIG. 11a shows the contents of table 2P. The pitch target value Pt corresponding to the longitudinal (front-back direction) acceleration Pg is set in a direction (decrease) that offsets the pitch appearing due to the longitudinal acceleration Pg.
It is in. Area a aims at energy saving by increasing the target pitch as the longitudinal acceleration Pg increases (decreases), and area b
In this area, abnormal Pg is considered to be due to sensor abnormality, so the pitch target value is made small to prevent the pitch target value from being given even though no Pg actually occurs. be. The other arithmetic processing operations are the same as the above-mentioned ``heap error CH operation J (50)'', in which HT and Ht in step 39 are replaced with PT and Pt, and DHT13 in step 40: DP of
Replace it with the T calculation formula and use EHTI and EHT2 in step 41.
Convert to EPTI, EPT2, and EHT in step 42.
2. HT, DHT to EPT2. Replace with PT, DPT,
Step 43 ITHI, I-TH2 to ITPI, IT
P2, the ITh calculation formula of the subroutine 44 is replaced with a pitch error correction amount ITpg output formula that has a completely corresponding relationship thereto, and table 3H is replaced with a coefficient table (3P) for calculating the pitch correction amount ITp, The table 4H is also replaced with a coefficient table (4P) for calculating the pitch correction amount ITρ, and lTR2 and ITh in step 45 are replaced with rTP2. IT
p and CH, Khs, I in step 46
By replacing Th with CP, Kpe pTTp, a flowchart showing the contents of "Pitch error CP calculation J (51)" appears. The CPU 17 executes the process shown in this flowchart.

Next, the CPU 17 executes “Rolling error CR calculation J (
52), calculate the roll error correction amount CR in the same way as the heap error CH, and register it in the roll error register CR.
In this case, the roll target value RT corresponding to the heap target value HT is written in the internal ROM of C:PU17.
From one area (table 2R), the lateral acceleration Rg at that time
The data Pt (roll target value according to the lateral acceleration Rg) corresponding to the lateral acceleration Rg is read out and obtained.

FIG. 11b shows the contents of table 2R. Lateral acceleration R
The roll target value Rt corresponding to g is in the direction of canceling out (decreasing) the roll appearing due to the lateral acceleration Rg. In the area a, the target roll is increased (decreased) as the lateral acceleration Rg increases (decreases) in order to save energy, and in the area b, the roll target value is decreased because abnormal Rg may indicate a sensor abnormality. This is to prevent the roll target value from being given even though Rg has not actually occurred. The other arithmetic processing operations are the same as the above-mentioned "heap error CH operation J (50)," and the HT and HttrRT in step 39.

Re, and the DHT calculation formula in step 40 is replaced with the above D
Replace with RT calculation formula, EHTI, EHT in step 41
2 to ERTI, ERT2, and EH in step 42.
T2. HT, DHT to ERT2. RT, DPT and replace ITHI, lTR2 in step 43 with ITRI, lT
R2, 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 thereto, and table 3H is replaced with a coefficient table (3R) for calculating the roll correction amount ITr, Table 4H is also replaced with a coefficient table (4R) for calculating the roll correction amount ITp, and lTR2, ITh in step 45 is replaced with lTR2, IT.
CH,Khg in step 46,
CR I Th.

By replacing it with ``e y r Tr, the flowchart showing the contents of the calculation J(51) of the roll error CR is cursed.The CPU 17 executes the process represented by this flowchart.

Next, the CPU 17 “calculates the warp error CW” (53
) to calculate the warp error correction icw in the same way as the heap error CH and write it into the warp error register CW. In this case, the warp target value PW corresponding to the heap target value HT is set to zero.

The other arithmetic processing operations are the same as the contents of the above-mentioned "heave error-CH operation J (50)," and step 39
Replace HT and Hj with WT and O, replace the DHT calculation formula in step 40 with the above-mentioned DV/T calculation formula, replace EHTI and EHT2 in step 41 with EWT l and EWT2, and change the contents of step 42. , when the absolute value of DWT is less than the predetermined value Wm (within the allowable range), WT is set to O,
When exceeding Wm, -DWT is set to WT, WT is changed to the content written to register EVT2, ITHl and rTH2 in step 43 are replaced with ITWI and ITW2, and IThf! in subroutine 44 is changed. The equation is replaced with a warp error correction i1Tw calculation formula that has a completely corresponding relationship, table 3H is replaced with a coefficient table (3W) for calculating the warp correction amount ITr, and table 4H is also used to calculate the warp correction amount ITr.
Coefficient table for Tw calculation (4W) 2 Replacement, Step 45 (7) ITH2°ITh is ITW2. ITw, and CH, Khs, I T in step 46
By replacing h with CW, Kw6, and I Tw, a flowchart showing the contents of "operation before warp error C" (53) appears.

The CPU 17 executes the processing shown in this flowchart.

As described above, after calculating the heap error correction fitcH, the pitch error correction amount CP, the roll error correction amount CR, and the warp error correction amount WP, the CPU 17 converts these correction amounts into the suspension pressure correction amount EH of each wheel section.
fL (addressed to suspension 100f), E Hf
r (addressed to 100fr L E HrL (addressed to 100rL), E ) (reverse converted to rr (addressed to 100rr).

That is, the suspension pressure correction amount is calculated as follows.

E Hfshi ::KfL -Khv ・(1/4)・
(cH-cp+cR+cv).

EHfr =Kfr-Khz ・(1/4)・(CI(
CP-CR(J).

E HrL=KrL4h741/4)・(CH+CP+
CR-CW).

E Hrr =Krr-Kh7・(1/4)lcH+c
P-CR+(J) coefficient KfL, Kfr, KrL, Krr
are line pressure reference point 13rm and return pressure reference point 1
Suspension 100f for 3rt, 100f
Due to the difference in piping length between r, 100r and 100rr,
This is a correction coefficient for compensating for suspension supply pressure deviation. Kh7 is a coefficient for increasing or decreasing the vehicle height deviation correction amount in accordance with the steering angular speed Ss, and
It should be read out from one area of OM (Table 5) in correspondence with 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 Kh7 is approximately the steering angular speed S
It is set large in proportion to s.

However, when the steering angular speed Ss is below a certain level (Ssc' 1m5ec or less in Table 5), the change in the direction of travel is very gradual and the attitude change is small and gradual. Attitude changes appear at proportional speeds. At steering angle speeds exceeding Ssd, the changes in vehicle body attitude become sudden and extremely large. Stability deteriorates.

Therefore, the correction coefficient Kh7 corresponding to the steering angular speed Ss is a constant value when Ss is below Ssc, and when Ss exceeds Ssc
Below sd, it is a high value that is substantially proportional to Ss, and Ssd
When the value exceeds the value of Ssd, it is set to a constant value.

Next, the contents of the pitching/rolling prediction calculation J (32) will be explained with reference to Fig. 10b. This system detects the current vehicle body posture based on the current vehicle height and steering angle speed, and adjusts the suspension pressure (feedback control) to maintain the current vehicle body posture at a predetermined appropriate level. On the other hand, "Pitching/rolling prediction calculation J (32) is a vertical motion applied to the vehicle body.

This is intended to suppress changes in vehicle body posture in response to lateral acceleration.

The CPU 17 first calculates a correction amount CGP for suppressing a change in pitch due to a change in longitudinal acceleration pg (55 to
58). In this case, the contents of register GPT2 in which the previous pg-compatible correction amount is written are transferred to register GPTI.
(55), 1 area of internal ROM (Table 6)
Then, the correction amount Gpt corresponding to Vs and Pg is read out and written in the register GPT2 (57). The data Gpt in table 6 is grouped using Vs as an index, and the CPU 37 specifies a group using Vs and reads out data Gpt corresponding to Pg in the specified group. For each group, the smaller the Vs assigned to the group, the wider the dead zone a (in Table 6 shown in Figure 10b).
Gpt, = horizontal width of O) is set large. b is a region in which the gain is increased as the longitudinal acceleration pg increases to improve control performance, and C is a region in which control performance is degraded because a sensor abnormality is considered.

Next, the CPU 17 calculates a correction ff1cGP for suppressing a change in the longitudinal acceleration pg using the following formula and writes it into the register CGP (58).

CGP=KgP3・(Kgpt・GPT2+KgP2
1GPT2-GPTI)] GPT2 is register GPT2
This time, the correction i read from Table 6 is
t Gp t.

GPTI is the content of register GPTI, and is the correction amount read out from table 6 last time. P (proportional) term Kg
KgP 1 of P l·GPT2 is the coefficient of the proportional term.

D CW minute) ]J'fKgpz iGPT2-GPT
I) (7) Kgp2 is the coefficient of the differential term, and this coefficient K
gP2 is read from an area (table 7) of the internal ROM corresponding to the vehicle speed Vs. As shown in "Table 7" in FIG. 10b, the coefficient KgP2 generally has a larger value as the vehicle speed Vs becomes higher, and increases the weight of the differential term. This is a amendment that the differential section is to quickly suppress the change in vertical speed PG. This is because the longitudinal acceleration Pg changes rapidly due to the change in the vertical acceleration Pg, so the posture change is quickly suppressed in response to this fast change.

On the other hand, when the vehicle speed Vs exceeds a certain level, changes in the longitudinal acceleration Pg are rapid and extremely large as the brake is pressed/released, the accelerator pedal is used to accelerate/decelerate, the steering wheel is rotated to turn/unturn, etc. Therefore, an excessively large differential term that quickly suppresses the sudden attitude change at this time destroys the stability of longitudinal acceleration suppression. Therefore, in more detail, the coefficient KgP2 in Table 7 changes greatly when the vehicle speed Vs is low, and remains constant when the vehicle speed Vs is equal to or higher than a predetermined value. That is, when the vehicle speed Vs is low, the weight of the differential term changes greatly with respect to changes in vehicle speed, but when the vehicle speed Vs is high, the weight of the differential term does not change with respect to changes in vehicle speed.

The calculated correction amount CGP for suppressing changes in longitudinal acceleration Pg is
For the suspension, it is the pitch correction amount, KgP
3 is a weighting coefficient for roll correction amounts CGR and GES, which will be described later.

In step 55G, it is determined whether the value of acceleration Pg detected by acceleration sensor 16p that detects acceleration in the longitudinal (vertical) direction is normal. For example, if Pg shows an abnormal acceleration due to a short circuit or disconnection of the acceleration sensor 16p, it is determined that the acceleration sensor 16p is abnormal in step 55C. In this embodiment, the output voltage of the acceleration sensor 16p is Vggmin.
~V (A range of 5gmax is considered normal, and output values other than the above are considered abnormal.

If Pg is abnormal in step 55C, step 55D
Set flag Fgg with . Further, if the absolute value of CGP is not less than Kgg, that is, substantially 0, step 55
Execute G or 55H. In step 55G, the correction f
The minute value Kgg is subtracted from the value of icGP, and the result is set as the updated CGP. In step 55 (2), Kgg is added. When an abnormality is detected, the flag Fgg is set, so step 55G or 551 is executed every time the process shown in FIG.

For example, when a short circuit or disconnection occurs in the acceleration sensor 16p, the value of the detected acceleration pg changes rapidly. In that case - in time a large difference occurs between GPTI and GPT2, and in step 58 an abnormally large value appears as CGP. If this CGP is used as is for suspension control, rapid pressure change control will be implemented, causing a sudden change in vehicle height of the vehicle body supported by the suspension.

However, in this embodiment, when Pg becomes an abnormal value, step 55
Each time G or 55H is executed, that is, as time passes, the value of CGP gradually decreases and finally reaches O (
(See time chart in Figure 10b). Therefore, even if the acceleration sensor 16p fails, sudden pressure change control will not be performed and no shock will occur.

In this example, when Pg is abnormal, the entire correction amount CGP is adjusted in step 55G or 55H.
Since the abnormal CGP value at the time of failure of the acceleration sensor is caused by the component of the differential term in the equation of step 58, processing may be performed such that only the value of this differential term is gradually decreased.

See Figure 10f. Next, the CPU 17 calculates the lateral acceleration P
Suppress roll changes due to changes in r (that is, lateral acceleration P
Calculate the correction amount CGR to suppress the change in r (
59-62). In this case, write the previous correction amount corresponding to Rg and transfer the contents of register CRT2 to register G.
Write to RTI (59), read the correction amount Crt corresponding to Vs and Rg from one area (table 8) of the internal ROM, and write it to register GRT2 (61). The data Crt in table 8 is grouped using Vs as an index, and the CPU 17 specifies a group using Vs and reads out the data Crt corresponding to Rg in the specified group. Each group is assigned a smaller VS, the dead band a (Table 8 shown in Figure 10b)
The horizontal width of Grt=O inside) is set large. b
C is a region where the control performance is improved by increasing the gain as the lateral acceleration Rg increases, and C is a region where the control performance is degraded because a sensor abnormality is considered.

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

CGR=Kgr3(Kgrt・GRT2+Kgr2
・(CRT2-GRTI)) CRT2 is register GRT
2, which is the correction amount Crt read out from table 8 this time. GRTI is the content of the register GRTI, and is the correction amount read from the table 8 last time. P(
Proportional) term Kgr 1・Kgr 1 of GRT2 is the 6D (differential) term Kgr+ ・(GRT2-G
Kgr2 of the internal ROM (RTI) is a coefficient of the differential term, and this coefficient Kgr2 corresponds to the vehicle speed Vs.
This is what was read from Table 9). As shown as "Table 9" in FIG. 10b, the coefficient Kgr2 is
Roughly speaking, the higher the vehicle speed Vg is, the larger the value is, and the weight of the differential term is increased. This is because the differential term is a correction term that attempts to quickly suppress changes in lateral acceleration Rg, and the higher the vehicle speed, the faster the change in lateral acceleration Rg due to turning/returning due to steering rotation. This is to quickly suppress this problem. On the other hand, vehicle speed V
When s exceeds a certain level, the change in lateral acceleration Rg becomes sudden and extremely large when turning/returning due to steering rotation, and excessive differentiation is required to quickly suppress such sudden changes. In this case, the stability of lateral acceleration suppression deteriorates. Therefore, in more detail, the coefficient Kgr2 in Table 9 changes greatly when the vehicle speed Vg is low with respect to changes in the vehicle speed Vs, and remains constant when the vehicle speed Vs is equal to or higher than a predetermined value. That is, when the vehicle speed Vs is low, the weight of the differential term changes greatly with respect to changes in vehicle speed, but when the vehicle speed Vs is high, the weight of the differential term does not change with respect to changes in vehicle speed.

The calculated CGR is a roll correction amount for the suspension, and Kgr3 is a weighting coefficient for the pitch correction amount CGP described above and the roll correction amount GES described below, but when the vehicle speed Vs is low, the lateral acceleration Rg Since the rate of change of CGR is low, the contribution ratio of this roll correction amount CGR is lowered in the low speed range, and the internal ROM is adjusted so that it remains constant in the high speed range.
Coefficient data Kgr3 is stored in one area (table 10) corresponding to the speed Vs. The CPU 17 reads out the coefficient Kgr3 corresponding to the speed Vs, and uses it for calculating the above-mentioned CGR.

In step 58C, it is determined whether the value of the acceleration Pr detected by the acceleration sensor 16r that detects acceleration in the left and right (lateral) direction is normal. For example, if Pr shows an abnormal acceleration due to a short circuit or disconnection of the acceleration sensor 16r, it is determined to be abnormal in step 58C. In this embodiment, the output voltage of the acceleration sensor 16r is V grmi
The range of n - V grmax is considered normal, and any other output value is considered abnormal.

If Pr is abnormal in step 58C, step 58D
Set the flag Fgt. If the absolute value of CGH is less than Kgt, that is, it is not substantially Ol, step 5
Run 8G or 58H. In step 58G, the micro-route Kgt is subtracted from the value of the correction amount CGR, and the result is set as the updated CGR. In step 58H, Kgt is added. When an abnormality is detected, the flag Fgt is set, so step 58G or 58N is executed every time the process shown in Figure 1 Ob is executed.

For example, if a short circuit or disconnection occurs in the acceleration sensor 16r, the value of the detected acceleration Pr will change rapidly. In that case - a large difference in time occurs between GRTI and GRT2, and in step 62 an abnormally large value appears as CGR. If this CGR is used as is for suspension control, rapid pressure change control will be performed, causing a sudden change in vehicle height of the vehicle body supported by the suspension.

However, in this embodiment, when Pr becomes an abnormal value.

Using the value of CGR calculated immediately before as a base, the absolute value of CGR gradually decreases each time step 58G or 58H is executed, that is, as time passes, and finally reaches O. Therefore, even if the acceleration sensor 16r fails, sudden pressure change control will not be performed and no shock will occur.

In this example, when Pr is abnormal, the entire correction amount CGR is adjusted in step 58G or 58■4, but the abnormal value of CGR when the acceleration sensor fails is determined by the differential term in the equation of step 62. Because it is caused by the ingredients,
Processing may be performed such that only the value of this differential term is gradually decreased.

The lateral acceleration Rg changes due to a change in the steering position (rotational position) (steering angular velocity Ss), and the rate of change also depends on the vehicle speed Vs. That is, since a change in the lateral acceleration Rg also corresponds to the steering angular velocity Ss and Vs, the roll correction amount aes required to suppress this change is written in an area (table 11) of the internal ROM of the CPU 17. C.P.
U17 checks whether the steering angle acceleration Sa is actually a passenger (64), and if it is not actually a passenger, table 1 is displayed.
1, read the roll correction fLGes corresponding to the combination of Vs and Ss and write it to the register GES (65)
. If you are actually a passenger (the previous steering angular velocity and the current steering angular velocity are equal: the roll correction amount Ges read last time can be used as the current roll correction amount), the register GES
Update writing to (65) is not executed.

Next, the CPU 17 converts the calculated pitch correction amount CGP, roll correction amount CGR, and roll correction amount DBS into pressure correction amounts addressed to each suspension, and applies these pressure correction amounts to the "vehicle height deviation calculation J ( The value EH calculated by 31,)
fL, EHfr, EllrL.

HHrr (registers EHft, EHfr, El
lrL, contents of EHrr) to obtain the sum Eh
Update and write fL, Ehfr, EhrL, and Ehrr to register Et (fL, RHfr, EHrL+EHrr) (G6).

EhfL=EI+fL+KgfL・(1/4)・(−C
GP+Kcgrf-CGR+KHefL-GIES)E
hfr =EIIfr +Kgft” (1/4)・(
-CGP-Kcgrf-CGR+KgefrG[ES]
EhrL = IEIlr+KgrL ・(1/4)
(CGP+Kcgrr-CGR+Kgershi ・GES
)Ehrr = [E+Irr +Kgrr・(1/4)
(CGP+Kcgrt"CGR+KgerrGES) The first term on the right side of the above equation is the value previously calculated by "vehicle height deviation calculation J (31), register EHft, E)If
r.

[This was written in EHrL and IEHrr, and the second term on the right side is the value obtained by converting the pitch correction amount CGP, roll correction amount CGR, and roll correction amount GES into pressure correction values for each suspension. be.

In addition, the coefficient Kgft-I Kgfr, K of the second term on the right-hand side
grL and Kgrr are: Kgfr = KfL - Kgs.

Kgfr = Kfr - Kgs.

Kgrc = l(rl--Kgs.

Kgrr = Krt - Kgs where KfL, Kfr, Krc, and Krr are coefficients (piping length correction coefficients) for correcting pressure errors due to variations in piping length of each suspension with respect to the pressure reference point, and Kgs is a table As shown in 12, it is a predetermined coefficient associated with the steering angular speed Ss, and is a coefficient that is used for the pitching/rolling prediction calculation J (32) for the pressure correction value calculated in the vehicle height deviation calculation J (31) described above. )
Pressure correction value for suppressing acceleration change calculated by
cgrf-CGR+Kgef L-GES), etc.). If the steering angular velocity Ss is large, a rapid change in acceleration is expected, and it is preferable to increase the weighting of the pressure correction value for suppressing the change in acceleration. Therefore, the coefficient Kg
Roughly, s is set to be large in proportion to the steering angular speed Ss. However, when the steering angular speed Ss is below a certain level (Sse''/m5ec or less in Table 12), the change in acceleration is extremely small, exceeding Sse and reaching 5sfa/ll5.
Below ec, the acceleration changes at a speed substantially proportional to the steering angular speed Ss. At steering angular speeds greater than or equal to Ssf, the change in turning radius becomes rapid and extremely large, resulting in extremely large changes in acceleration (especially lateral acceleration). Control stability deteriorates. Therefore, the steering angular speed Ss
The weighting coefficient Kgs corresponding to is a constant value when Ss is less than Sse, a high value substantially proportional to Ss when it exceeds Ssc and less than Ssf, and a constant value when Ssf is exceeded.

CPU] 7 then inputs the initial pressure register PFLo.

The initial pressure data (set in steps 16 to 18) written to PFR, PRLo, and PRRO is transferred to subroutine 6.
6, the sum of the correction pressure for vehicle height deviation adjustment and the correction pressure for acceleration suppression control (register IEHft-, E
Hfr, EHrL, EHrr contents),
Calculate the pressure to be set for each suspension and set the registers Tl1f, EHfr, EHrL, IEHrr.
An update is written to (67).

To explain the contents of "Pressure correction J (33)" with reference to FIG. The correction value P H for compensating for fluctuations in output pressure is stored in one area of the internal ROM (Table 13I-1).
) and the detected pressure D of the pressure sensor 13rt.
Corresponds to ρL (contents of register DPL).

The correction values PLf (front wheel side correction value) and PLr (rear wheel side correction value) that compensate for fluctuations in the output pressure of the pressure control valve due to return pressure fluctuations are read from an area of the internal ROM (table 13L), and the pressure control valve Pressure correction value PDf that compensates for fluctuations in pressure control valve output pressure due to fluctuations in line pressure and return pressure applied to P H - P L f and PDr
=PH-PLr is calculated (68.69). 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 closer to the reservoir and the rear wheel side is farther from the reservoir, and the pressure sensor 1.3 r t for low pressure detection is located at the rear wheel side. Since the return pressure on the wheel side is detected, the return pressure difference between the rear wheel side and the front wheel side is relatively large, so this is to reduce the error caused by this. Table 13 L stores two groups of correction value data to be assigned to the rear wheel side and a correction value data group to be assigned to the front wheel side, the latter for the front wheel suspension and the former for the rear wheel suspension. Based on the data value, a correction value corresponding to the pressure detected by the pressure sensor 13rj at that time is read out.

After calculating the correction values PDf and PDr, the CPU 17 stores these correction values in registers EHf L and Etlf
r.

In addition to the contents of HllrL, EHrr, register El
(f L, EHfr, Ellr L, Ell
An update is written to rr (70).

Referring to FIG. 10d, to explain the contents of "pressure/current conversion J (34), the CPU 17
L, Ellfr, IEtlr L and Et
(r r data EHfL.

Pressure control valves 80f and 80fr for generating the pressures indicated by IEIlfr, Ellrt and Et(rr)
, the current value r hf that should be passed through 80rL and 80rr
L, Ihfr, IhrL and Thrr, pressure/
Read from current conversion table 1 and input current output registers HfL and IHfr, respectively.

111r and writes to l1lrr (34).

The details of warp correction (35) will be explained with reference to FIG. 10e. This warp correction (35) calculates an appropriate target warp DWT from the lateral acceleration Rg and the steering angular velocity Ss.
3), and the above-mentioned registers Tl1f and l1lfr
, l1lrL, and IHrr, and calculate the amount of error warp with respect to the target warp DWT (74-76), and calculate the current correction step required to make this error warp amount zero. Direct dIf
Calculate L, dfr + dIrL, dIrr (7
7), these current correction values are stored in registers IHfL, l1
It is added to the contents of lfr, IHrL, and IHrr, and the sum is updated and written to these registers (78).

The warp target value 1dr corresponding to the lateral acceleration Rg is written in the first area Vi (table 14) of the internal ROM of the CPU 17, and the word processor target value Ids corresponding to the steering angular velocity Ss is written in the table 15. In table 16,
Registers IHfL and IHf that are about to be output
A warp correction amount 1drs corresponding to the longitudinal inclination of the vehicle body and the lateral acceleration Rg (lateral inclination) defined by the values of r, IHr, and Hlrr is written. In addition, the longitudinal inclination is K= l (IhfL +1hfr)/(Ihr
The corresponding data groups are written in the table 16, and each data group is associated with the lateral acceleration Rg.

The CPU 17 reads the warp target value Idr corresponding to the lateral acceleration Rg and the warp target value Idr corresponding to the steering angular velocity Ss from the table 14, and registers IHft HIHfr, IHr(t). The warp correction amount Idrs corresponding to the longitudinal inclination and the lateral acceleration Rg (lateral inclination) is read out from the table 16, and the warp target value DWT is calculated as shown in the following equation (73).

DWT=Kdw1・Idr+Kdw2−Ids+Kdw
3 ・IDrsCPU 17 next registers IHf L
+ IHfr + IHr L Warp defined by the contents of IIHrr (IhfL Ihfr) (Ihrt - Ihrr
) and check whether it is within the permissible range (dead band) (74). If it is outside the permissible range,
Warp calculated from target warp DWT (ThfL-Ihfr
) The value obtained by subtracting (IhrL-Ihrr) is written as the warp error correction amount to the register DWT (75), and when it is within the allowable range, the contents of the register DWT (DWT) are not changed. Then, the warp error correction amount DWT (contents of the register DWT) is multiplied by the weighting coefficient Kdw4 and the product is updated and written to the register DWT (76), and this warp error correction amount DWT (contents of the register DWT) is applied to each suspension pressure correction amount (more precisely, , the pressure control valve energizing current correction value corresponding to the pressure correction amount) (77), and the correction is converted to the 'company output register l1lf L I Itlfr , II
! r Add to the contents of L and l1lrr (78).

These current output registers IHfL, l1lfr,
The data of IHrL and IHrr is "output J (36)
In the subroutine, pressure control valves 80k, 80fr, 8
Addressed to 0rr and 80rr, transferred to CPU 18,
CPU], 8 provides to the duty controller 32.

[Effects] As described above, according to the present invention, when an abnormality in the acceleration detection means (16p, 16r) is detected, the acceleration control amount (CGP in FIG. 10b) is changed.

CGR) is gradually reduced over time based on the acceleration control amount before an abnormality is detected, and approaches 0, so even if a short circuit or disconnection occurs in the acceleration detection means, the control system will not suddenly respond. Therefore, sudden pressure change control is not performed, and sudden small changes in the suspension can be prevented.

[Brief explanation 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. FIG. 2, FIG. 3, FIG. 4, FIG. 5, FIG. 6, and FIG. 7 respectively show the suspension 100f shown in FIG.
Pressure control valve 80f and cut valve 70fL. Relief valve 60fL, main check valve 50,
and an enlarged vertical cross-sectional view of the bypass valve 120. FIGS. 8a and 8b are block diagrams showing the configuration of an electrical control system that controls the suspension control device shown in FIG. 1. FIGS. 9a and 9b are flowcharts showing the control operation of the microprocessor 17 shown in FIG. 8. 1Oa, 10b, 10c, 10d, 10e, and 10f are flowcharts showing the contents of the subroutine shown in FIG. 9b. FIG. 11a and FIG. 11b show the internal RO of the CPU 17.
It is a graph showing the contents of data written in M. l: Pump 2: Reservoir 3: High pressure port 4: Accumulator 6: Front wheel high pressure supply pipe 7
: Accumulator 8: High pressure supply pipe 9: Rear wheel high pressure supply pipe lO: Accumulator 11: Reservoir return pipe 12 Nidrain return pipe 13k, 13fr, 13r
L, 13rr, 13rm, 13rt: Pressure sensor 14k
, 14fr, 14rL, 14rr: Drain 15f for atmospheric release, 15fr, 15rL, 15rr: Vehicle height sensor 16p, 16r: Acceleration sensor 17.18: Microprocessor 19: Battery 50: Main check valve 51: Valve base 52: Input Port 53: Output boat 54: Valve seat 55: Communication port 56: Compression coil spring 57: Ball valve 60fr, 60fL, 60rr, 60r: Relief valve 61: Pulbu base 62: Input port 6
3: Low pressure port 64: First guide 65: Filter
66: Valve body 67: Second guide 68:
Valve body 69: Compression coil spring 60■:
Main relief valves 70fr, 70k, 70rr, 70rL: Cut valve 71: Valve body 72 Line pressure boat 73:
Pressure regulation input port 74: Discharge port 75: 75
:Output port 76:First guide 77:Guide
78 Nispool 79: Compression coil spring 80fr, 80k, 80rr, 80rL: Pressure control valve 81 Nisleeve 82 Niline pressure port 83: Groove 84: Output port 85: Low pressure port 86: Groove 87: High pressure port 88: Target pressure space 88f Niorifice 89 :Low pressure port 90 varnish spool
91: Groove 2: Compression coil spring
93: Valve body 94: Flow path 95: Two dollar valve
96: Fixed core 97: Plunger 98a: Yoke
98b: End plate 98c: Low pressure port 100fr, 100k, 100rr, 100rL: Suspension 101fr, tolk, 101rr, 1
01rt: Shock absorber 102fr, 102k
, 102rr, 102rL: Piston rod 103:
Piston 104: Inner cylinder 105: Upper chamber 1
06: Lower chamber 107: Side entrance 108
: Vertical through hole 109 : Damping valve device 110 : Lower space 111 : Piston 112 : Lower chamber 1
13: Upper chamber 114: Outer cylinder 120: Bypass valve 121: Input port 122: Low pressure boat 122a: Low pressure port 122b: Channel 1
23: First guide 124a: Valve body 124b: Compression coil spring 125: Two dollar valve 150: A/
D conversion unit 170: Duty control unit (duty controller) 180: ffi flow detection unit 19
0.200: Driver RY: Relay
SVt: Ignition switch 5M2: Vehicle speed sensor (reed switch) ST13 Nistop lamp switch 5114: Door switch SWS: Reservoir level warning switch 5116: Vehicle height adjustment switch SNI steering sensor SN2: Throttle sensor

Claims (1)

[Scope of Claims] A suspension mechanism including an actuator that expands and contracts in accordance with supply and discharge of fluid; Acceleration detection means for detecting acceleration of a vehicle body supported by the suspension mechanism; Pressure source means for supplying fluid to the actuator; Adjustment valve means for controlling supply and discharge of fluid from the pressure source means to the actuator; and a control amount of the adjustment valve means is adjusted according to an acceleration control amount based on at least a differential component of the acceleration detected by the acceleration detection means; Controlling the posture in a direction that approaches horizontality, and identifying whether or not there is an abnormality in the acceleration detection means,
When the presence of an abnormality is identified, the electronic control means sets the value of the acceleration control amount before detecting the presence of the abnormality as an initial value, and sets the value that gradually decreases over time and approaches zero as the acceleration control amount after the occurrence of the abnormality. A suspension control device comprising;