JPH0379417A - Suspension controller - Google Patents

Abstract

PURPOSE:To prevent the generation of suspension shock by digital-filter- processing a value of detected car height so as to remove a component of predetermined high frequency variation, and by reducing a cut-off frequency of the digital filter when the abnormality of a car height detecting means is recognized. CONSTITUTION:To a high pressure supply tube 8 connected to a discharging side of an engine-driven hydraulic pump 1, through a front wheel high pressure supply tube 6, pressure control valves 80fL, 80fr, etc., front wheel suspensions 100fL, 100fr, etc., are connected. (This is also applied to rear wheel suspension, though not mentioned here.) The pressure control valves 80fL, 80fr, etc., are controlled by an ECU based on the output from car height sensor 15fL, 15r. At the time of control, the value of the detected car height is digital-filter- processed, so as to remove a component of predetermined high frequency variation, and according to the difference between processed result and an aimed value of control, the control of car height is adjusted. When abnormality of the car height sensor is recognized, a parameter for the digital filter process is adjusted, so as to reduce cut-off frequency of the process compared to that in a normal state.

Description

[Detailed Description of the Invention] [Object of the Invention] [Industrial Application Field] The present invention relates to a suspension control device used in a vehicle, and in particular, the present invention relates to a suspension control device that is equipped with a sensor that detects the vehicle height at each axle position.
The present invention relates to a suspension control device that performs suspension control according to detected vehicle height information.

[Prior Art] In the device disclosed in Japanese Patent Application Laid-Open No. 63-269709, the suspension control amount is determined based on the vehicle height detected by a vehicle height sensor, the differential value of the vehicle height, and the vertical acceleration detected by an acceleration sensor. It is determined according to the sum of each component.

[Problem to be solved by the invention] For example, in a suspension control device that is equipped with a vehicle height sensor and performs suspension control according to the detection result of the vehicle height sensor, as disclosed in Japanese Patent Application Laid-Open No. 63-269709, When a circuit short or open abnormality occurs,
Since the detected vehicle height becomes 0 or the full scale vehicle height, the detected vehicle height error becomes very large and the vehicle height changes rapidly. In other words, even when the actual vehicle height matches the nominal vehicle height, the differential component 1 corresponding to the detected vehicle height change, for example, the difference between the previously detected vehicle height and the currently detected vehicle height, may be temporarily abnormal. Since this becomes a large value, the control amount of the pressure control system becomes large corresponding to the differential component, and a shock is transmitted to the occupant due to a change in suspension pressure, that is, a change in vehicle height.

If the control gain for the differential component is made small, the shock caused by the sudden change in vehicle height described above can be reduced, but on the other hand, the ability of suspension control to follow rapid changes in vehicle height will deteriorate.

SUMMARY OF THE INVENTION An object of the present invention is to provide a suspension control device that prevents a shock from occurring when an abnormality occurs in a means for detecting vehicle height and has good high-speed response.

[Components of the invention [Means to solve the problem] In order to solve the above-mentioned problem, one aspect of the present invention is as follows.

A suspension mechanism including an actuator that expands and contracts in accordance with supply and discharge of fluid; Vehicle height detection means that detects changes in vehicle height due to expansion and contraction of the actuator; Fluid is supplied to the actuator. Pressure source means; Adjustment valve means for controlling the supply and discharge of fluid from the pressure source means to the actuator; and the detected vehicle height value detected by the vehicle height detection means is passed through digital filter processing to generate a predetermined high frequency signal. The variable component is removed, and the control amount of the regulating valve means is adjusted based on the difference between the processing result and the control target value.

It is determined whether or not there is an abnormality in the vehicle height detection means, and when it is determined that there is an abnormality, the parameters of the digital filter processing are adjusted to lower the cutoff frequency of the filter processing compared to a normal state. Electronic control means; 6 [Operation] By passing the detected value through the digital filter constituting the low-pass filter, a high frequency change component of the detected value, that is, a rapid change in the detected value can be suppressed. Therefore, by performing control according to the error between the filtered result and the target value, changes in the error become gradual. Therefore, when the cutoff frequency of the filter is low, the amount of attenuation of the differential value due to the error by the filter is large, thereby preventing an abnormally large differential value from occurring and avoiding the occurrence of sudden control pressure changes.

In the present invention, when an abnormality is detected in the vehicle height detection means, the cutoff frequency of the filter is lowered compared to when it is normal, so that the amount of attenuation of the differential component by the filter becomes larger than when it is normal. Therefore, even if there is a sudden change in the vehicle height detection value due to an open or short circuit in the vehicle height sensor circuit, the change is smoothed by passing it through the filter, and the differential component is prevented from becoming abnormally large. Shocks caused by sudden changes in vehicle height are avoided.

By the way, 1. For example, when a vehicle height sensor outputs vehicle height information in the form of an analog signal, an analog filter circuit (low-pass filter) is inserted between the output of the vehicle height sensor and the A/D converter. .

It is possible to reduce the shock that occurs when an abnormality occurs in the vehicle height sensor. However, in that case, even when attempting to obtain detection values for each of multiple attitude elements based on multiple pieces of vehicle height information obtained from multiple vehicle height sensors and perform independent attitude control for each attitude element, all Since the rate of change of the detected value for each attitude element is determined by the characteristics of the same analog filter, the response speed of attitude control is set to be the same for all attitude elements. However, it is preferable to set the response speed to an optimal condition for each posture element.

In the present invention, since digital filter processing is applied to the detected values, even when multiple vehicle height postures are detected using multiple vehicle height sensors, filter characteristics can be switched for each determined posture element. It is possible to obtain the optimal response speed for each posture element.

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

[Example] Fig. 1 shows an outline of the mechanism of an automobile suspension device embodying the present invention.A hydraulic pump 1 is a radial pump, and is disposed in an engine room, and is connected to the drive output of an on-vehicle engine (not shown). is connected by a belt, and when driven to rotate, it sucks oil from reservoir 2,
Oil is discharged at a predetermined flow rate to the high-pressure boat 3 at a rotational speed of a predetermined speed or higher.

High pressure port 3 of radial pump for suspension pressure supply
An accumulator 4° main check valve 50 and a relief valve 60+n for driving force absorption 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 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 wheel suspension 1QOfL.

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

A pressure control valve 80fr is connected to the front wheel high pressure supply pipe 6 via an oil filter 4.
However, the pressure in the front wheel high pressure supply pipe 6 (hereinafter referred to as front wheel line pressure) is regulated (pressurized) 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 valve are activated. Give 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.

Piston rod 102fr (shock absorber 10L
fr) to the pressure control valve 80fr, and when the front wheel side line pressure exceeds a predetermined low pressure, the pressure control valve 80fr
The output pressure (suspension support pressure) of 0fr 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.

Pushed up from the road to the front right wheel #! ! When the internal pressure of the shock absorber 101fr rises impulsively due to the impact, this cushions the propagation of this impact to the pressure control valve 80fr, and when the internal pressure of the shock absorber LOtfr impulsively increases, the internal pressure of the shock absorber 101fr increases. of,
It is discharged into the reservoir return pipe 11 via the piston rod LOOfr and the cut valve.

Suspension 100fr roughly consists of shock absorber 101fr and S frame coil spring 119fr.
Output port 8 of pressure control valve 80fr
4 and piston rod LO2fr into the shock absorber 101fr (pressure control valve 8
The vehicle body is supported at a height (relative to the front right wheel) 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 L5fr generates an electric signal (digital data) indicating the vehicle height of the front right wheel portion (the height of the vehicle body relative to the wheel).

Pressure control valve 80fL and cut valve 70 similar to the above
fL, a relief valve 60fL, a vehicle height sensor 15fL, and a pressure sensor 13fL are similarly installed and assigned to the suspension LOGfw on the front left axle, and the pressure control valve 30fL is connected to the front @ high pressure supply pipe 6. , the required pressure (support pressure) is applied to the shock absorber 101f of the suspension 1oofL and the piston rod 102f of L
Give to L.

Pressure control valve 80rr, cut valve 7 similar to the above
0rr, relief valve 60rr, vehicle height sensor 15
rr and pressure sensor L3rr are similarly installed and assigned to the rear right wheel suspension LOOrr, and the 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 1o1rr piston rod 102
Give to rr.

Furthermore, similar to the above, a pressure control valve 80rL, a cut valve 70r, a relief valve 60rL>"high sensor 1
5rL and pressure sensor 13rL are similarly installed and assigned to the front left wheel suspension 1oOrL, and the pressure control valve gOrL is connected to the rear @ high pressure supply pipe 9 to maintain the required pressure (support pressure). suspension 101
) to the piston rod 1102r of the shock absorber 10LrL.

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 rule
), and the piping length from the hydraulic pump 1 to the rear wheel suspension 100rr, 100rL.

Hydraulic pump 1 to front wheel suspension 100fr.

It is longer than the piping length up to 100fL. Therefore, the pressure drop due to the piping is large on the rear wheel side, and if an oil leak occurs in the piping, the pressure drop on the rear wheel will be the largest. A pressure sensor 13rm is connected.

On the other hand, the pressure of the reservoir return pipe 11 is the lowest at the end on the reservoir 2 side, so much so that it is far away from the reservoir 2.

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

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). 1 stop), the line pressure becomes substantially atmospheric (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
.

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 the piston rod 1 of the shock absorber LOLfr, showing an enlarged longitudinal section of the suspension 100fr.
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 several ports of the piston rod 102fr.
7, joins the upper chamber 105 in the inner cylinder 104, and further.

The lower chamber 106 passes through the upper and lower through holes 108 of the piston 103.
join. A support pressure proportional to the product of this pressure and the cross-sectional area of the piston rod 102fr (the square of the rod radius Xπ) is applied to the piston rod 102fr.

The lower chamber 106 of the inner cylinder 104 communicates with the upper space 110 of the damping valve device 109 . The space above the damping valve device 109 is.

It is divided into a lower chamber 112 and an upper chamber 113 by a piston 111, and oil in an upper space 110 flows through the lower chamber 112 through a damping valve device 109, while high pressure gas is sealed in the upper chamber 113.

When the piston rod 102fr tries to relatively rapidly enter the lower part of the inner cylinder 104 due to the thrust upward movement of the front right wheel, the internal pressure of the inner cylinder 104 increases rapidly, and the pressure in the upper space 110 also decreases to the lower chamber. The pressure is about to rise sharply higher than that of 112. At this time, the oil flows into the upper space 112 through the check valve of the damping valve device 109 that allows the oil to flow from the upper space 110 to the lower chamber 112 at a predetermined pressure difference or higher, but blocks the flow in the opposite direction. This causes the piston 111 to rise and buffer the impact (upward) applied from the wheels from propagating to the piston rod LO2fr. In other words, to the car body, in front of the wheels! ! The propagation of (advancement) 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 axle, the internal pressure of the inner cylinder 104 suddenly decreases (and similarly, the upper space 1
10 is about to suddenly become lower than the pressure in the lower chamber 112. At this time, the oil flows into the lower chamber 110 through the check valve of the damping valve device +o9, which allows oil to flow from the lower chamber 112 to the upper space 110 at a predetermined pressure difference or higher, but blocks flow in the opposite direction. This causes the piston 111 to descend, thereby buffering the propagation of the force applied from the wheels (my<downward) to the piston rod 102fr. That is,
The propagation of wheel *M- (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 pressure in the lower chamber 112 increases, causing the piston 111 to rise.

The pistons 111 are arranged in positions 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 such that only a small amount of oil leaks when the piston rod 102fr moves up and down. It is said to have the sealing properties of 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 level sensor 28 (
1), and the level sensor 28 generates a signal (oil shortage signal) indicating this when the oil level in the reservoir 2 is below the lower limit value.

The structures of the other suspensions 100fL, t 100rr and 100rL are also similar to the suspension 100fr described above.
The structure is substantially similar to that of .

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

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

A valve housing hole is formed, and this valve housing hole communicates with the groove 91. A compression coil spring 9 is installed in the valve housing 6.
The valve body 93 pushed in step 2 has been inserted.

This valve body 93 has a through orifice in the center, and this orifice allows the space of the groove 91 (output port 84).

The valve body 93 and the space in which the compression coil spring 92 is accommodated are in communication. Therefore, the spool 90 receives the pressure of the output port 84 (regulated pressure, the pressure on the suspension 100fr) at its left end, and thereby receives a force that drives it to the right. In addition, the output port 84
When the pressure increases impulsively, the valve body 93 moves to the left against the pushing force of the compression coil spring 92 and moves to the right end of the valve body 93; a buffer space is created, so the output port 84 When the pressure rises shockingly, this shocking rising pressure is not immediately applied to the left end surface of the spool 90, and the valve body 9
3 has the effect of buffering the rightward movement of the spool 90 against an impulsive pressure increase in the output port 84, and conversely, the left movement of the spool 90 against an impulsive pressure drop in the output port 84. This provides a buffering effect.

The pressure of the target pressure space 88 communicating with the high pressure port 87 via the orifice 88f is applied to the right end surface of the spool 90, and due to this pressure, the spool 90 receives a force that drives it to the left. Line pressure is supplied to the high pressure port 87, and the target pressure space 88 communicates with the low pressure port 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 boat 82). death.

The pressure in the groove 91 (output port 84) increases and is transmitted to the left side of the valve body 93, giving rightward driving force to the left end of the spool 90. When the needle valve 95 fully opens the flow path 94, the pressure in the target pressure space 88 is narrowed by the orifice 88f, so it is significantly lower than the pressure (line pressure) in the high pressure boat 87, and the spool 90 moves to the right. This causes the groove 91 of the spool 90 to align with the groove 86 (low pressure boat 85
), the pressure in the groove 91 (output port 84) decreases, this is transmitted to the left side of the valve body 93, and the rightward driving force at the left end of the spool 90 decreases. In this way, the spool 90
is 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 a fixed core 96 of magnetic material. The right end of the fixed core 96 has a truncated conical shape, and the end face of the magnetic plunger 97, which has a large conical shape with a bottom, is opposed to this right end face. A needle valve 95 is fixed to this plunger 97. The fixed core 96 and plunger 97 are
It enters inside the bobbin around which the electric coil 99 is wound.

When the electric coil 99 is energized, magnetic flux flows through the loop of the fixed core 96 - magnetic yoke 98a - magnetic end plate 98b - plunger 97 - fixed core 96, and the plunger 97 is attracted to the fixed core 96 and moves to the left. However, 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 rightward 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 effectively changes the flow value of the electric coil 99 to the flow R''l with respect to the flow path 94. The distance m is inversely proportional.In order to make the relationship between the current value and the distance linear, as described above, one of the fixed core and the plunger is shaped like a truncated cone, and the other one is shaped like a truncated cone. It has a conical hole shape with a bottom.

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

This pressure control valve 80fr has an energized 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.

In the valve storage hole drilled in the valve base 71.

Line pressure boat 72. Pressure adjustment capo door 3. The oil drain boat 74 and the output port door 5 are in communication. The line pressure port 72 and the pressure regulation input port door 3 are separated by a ring-shaped first guide 76, and the pressure regulation input port door 3 and the output port door 5 are separated by cylindrical guides 77a, 77b, and 77c. There is. The oil drain port 74 communicates with a ring-shaped groove on the outer periphery of the second guide 77c.
The oil leaking around the outer peripheries of a, 77b and 77c is returned to the return pipe 11.

A spool 78 pushed leftward by a compression coil spring 79 passes through the first and second guides 76, 77a to 77c, 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
It is blocked by completely closing the inner port 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 moves to the rightmost position (fully open) at a pressure higher than the predetermined low pressure, that is, the spool 78 moves to the right from the inner opening of the second guide 77a, and the pressure regulation input port door is moved to the right. 3 communicates with the output port door 5, and when the line pressure (line pressure boat 72) rises to a predetermined low pressure, the caputo valve 70fr connects the pressure regulation input port door 3 (pressure regulation output of the pressure control valve 80fr) and the output port door 5 (shock absorber). 101fr), and when the line pressure (boat 72) further increases, the pressure regulation input port door 3
(pressure regulation output of pressure control valve 80fr) and output port door 5 (
The shock absorber 101fr) is fully opened. When the line pressure goes down, the opposite is true, and when the line pressure becomes less than a predetermined low pressure, the bottom door 5 (shock absorber 1o1fr) is completely shut off from the pressure regulation input port door 3 (pressure regulation output of the pressure control valve 80fr). be done.

FIG. 5 shows an enlarged longitudinal section of the relief valve 60fr, and the input port 2 and the 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 inserted into the valve storage hole, and the input port 2 communicates with the inner space of the first guide 64 through the filter 65. A valve body 66 having an orifice in the center is inserted into the first guide 64, and the valve body 66 is pushed to the left by a compression coil spring 66a. The space in the first guide 64 that accommodates the valve body 66 and the compression coil spring 66a is
It communicates with the input port 2 through the orifice of the spring seat 66b, and also communicates with the second guide 6 through the opening of the spring seat 66b.
It communicates with the inner space of 7. The conical valve body 68 is pushed to the left by the repulsive force of the compression coil spring 69, and the spring seat 6
The opening of 6b is closed. Input Portro 2 pressure (
When the control pressure) was less than a predetermined high pressure, it communicated with the input port 2 through the orifice of the valve body 66. The pressure in the coil spring 66a storage space causes the compression coil spring 6
Since the repulsive force of the fifth valve body 68 is relatively lower than that of the fifth valve body 68,
As shown in the figure, the central opening of the valve 156b is closed, and the output port 2 is therefore cut off from the inner space of the second guide 67, which communicates through the low pressure port 63 and the valve 67a. That is, the output port 2 is cut off from the low pressure port 63.

When the pressure (control pressure) of the input port 2 rises to a predetermined high pressure, this pressure passes through the orifice of the valve body 66 and is applied to the valve seat 6.
6b, the valve body 68 begins to be driven to the right by this pressure, and when the pressure of the input port 2 further increases,
The valve body 68 is driven to the rightmost side. That is, the pressure of the input port 2 is released to the low pressure port 63, and the control pressure is suppressed to a predetermined high pressure level or less.

In addition, when high pressure is applied to the input port 2 in a manner similar to 251.

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

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

FIG. 7 shows an enlarged longitudinal section of the bypass valve 120.
The input port 121 communicates with the inner space of the first guide 123, and a compression coil spring 124b is connected to the inner space.
The valve body 124a pushed to the left is housed. This valve body 124a has an orifice at the center of the left end surface, and the input port 121 is connected to the first guide 1 through this orifice.
It communicates with 23 inner spaces. The inner space has a flow path 122
It communicates with the low pressure port 122 through b, but this flow path 1
22b is opened and closed by a needle valve 125.

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

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

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

The relief valve 60m is the relief valve 60f mentioned above.
The structure is the same as that of r, but the valve body has a conical shape (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 at the input port (62) is lower than the low pressure boat (
63), and the pressure in the high pressure port 3 is suppressed to a predetermined high pressure or less.

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

The relief valve 60m suppresses the pressure in the high pressure port 3, that is, the pressure in the high pressure supply pipe 8, to a predetermined high pressure or less, and when the pressure in the high pressure port 3 rises impulsively, the pressure in 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 1 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 is stopped). ) to release the pressure.

The pressure control valves 80fr, 80fL, 80rr, and 80rL control the energizing current value of the electric coil (99) so as to apply the required support pressure to the suspension by suspension pressure control, and apply the required support pressure to the output port ( 84
). When shock pressure from the suspension propagates to the output port (84), turn it >IN,
Disturbance of the spool (91) of the pressure control layer (disturbance of output pressure)
suppress. In other words, the required pressure is stably applied to the suspension.

Cut valve 70fr, 70fL, 70rr, 70rL
When the line pressure (front wheel high-pressure supply pipe 6, rear wheel high-pressure supply pipe 9) is less than a predetermined low pressure, the suspension supply pressure line (between the output port 84 of the pressure control valve and the suspension) is shut off and the suspension is removed. To prevent pressure leakage and to fully open the supply pressure line when the line pressure is higher than a predetermined low pressure. This automatically prevents an abnormal drop in suspension pressure when line pressure is low.

Relief valve 60fr, 60fL, 60rr, 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 controller) 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 relieve the FRM of the suspension and also to the hydraulic line connected to the suspension. 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 15fL and L5fr are arranged near the shock absorbers at each position of RL and RR.

15rL and 15rr each output a signal corresponding to the direct projection of the wheels and the vehicle body at each position, 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.

13fL, 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.

13rI11 and 13rSe 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 a voltage (analog signal) according to the pressure at each position. In addition, 16P and 16" are G output voltages (analog signals) according to acceleration (G).
A sensor 16p detects G in the longitudinal direction of the vehicle body, and a sensor 16r detects G in the lateral direction of the vehicle body.

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

RG is one output terminal of 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 FL, FR, and RL, respectively.
and linear control valves (80fL, 80fr, 80rL, 80rr) installed in the hydraulic control unit of RR.
5OL5 is a bypass valve 120.
This is a solenoid.

FIG. 8b shows a specific configuration of the control unit ECU of FIG. 8a. Referring to FIG. 8b, this control unit ECU includes two CPUs (microcomputers).
17.18. I10 expansion unit 130. Reset control unit 140. A/D conversion unit 150. Active filter unit 160. Duty control unit 1
70° current detection unit 180. Driver 190, 20
0, power supply 21O, backup power supply 220. driver 2
30. 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 input buffers 7240, respectively.
Applied to RO, ASRI and ASR2. Furthermore, ASR
O to ASR2 are interrupt request ports. Also, an input terminal ICL.

LL, L2. L3. STP, DOOR, LOIL and H
Information on the signal applied to IGH is sent to input ports PA4 to PA7 of the CPU 17 via the r/○ expansion unit 130.
is applied to

Vehicle height sensor 15fLt 15fr, 15rLy
L 5rr.

Pressure sensor 13fLv 13fry 13rL, L
3rr.

Analog signals output from the G sensors 13rm, 13rt, and the G sensors 16p and 16r are applied to each analog signal input terminal of the A/D conversion unit 150 via the active filter unit 160.

Further, analog signals corresponding to the currents flowing through the solenoids 5QL1 to 5QL1 to OL5 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 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 SQL1-5OL5 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 into the duty control unit 170, the duty control unit 170 outputs duty pulses corresponding to the data 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 (PB
7 to PBO), and these 8-bit ports are connected to each other via a group of 7 signal lines 306. Also,
All eight lines of this signal line group 306 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, All lines of the signal line 306 are fixed at high level H.

Data transmitted between the CPUs 17 and 18 is sent in the form of 8-bit parallel data via the signal line group 306. In addition, in order to synchronize the timing of transmitting and receiving this data, the two CPUs 17 and 18 are further connected to two control lines 307.
and 308 are connected to each other. The control line 307 is
The output port PA3 of the main CPU 17 and the interrupt request port IRP of the sub CPU 18 are connected, and the other control! 308 is the CPU on the sub side
The CPU 18 output port PA4 is connected to the interrupt request input port IRP of the main CPU 17.

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 15f provided in the suspension system shown in FIG.
5fr, 15r, 15rr and pressure sensor 13fL
, 13fr, 13rL, 13rr, 13rm, 13rt
,.

Also, reading the detected values of the longitudinal acceleration sensor 16p and the lateral acceleration sensor 16r on the vehicle, and the pressure control valve 80f.
L, 80fr, 80rL, 80rr and bypass valve 1
The current value applied to the electric coils (99, 129) of No. 20 is controlled.

The CPU 17 sets/cancels the line pressure of the suspension system (Fig. 1), determines the vehicle operating state, and responds to the determination results from when the ignition switch is closed to when it is opened, and immediately after the ignition switch is opened. did. Calculate the required pressure (pressure that should be set for each suspension) required to establish an appropriate vehicle height and body posture, receive various detected values from the CPU 18 to determine the vehicle driving state, and set the required pressure. The current value is sent to the CPU
Give to 18.

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. , are summarized in Table 1 below.

register symbol P.F.L.

F.R.O. PRL.

P.R.R.

P.H. DPL S P S T S G G DPL F.R. R.L. R.R. T T T T write data symbol pfL.

frO PrL.

Prr.

ph D.P.L.

S p s T s g g k fr DPL rr H Pse Rt.

L Table 1 Write data contents Initial pressure of shock absorber lo1 Initial pressure of shock absorber 101fr Initial pressure of shock absorber 1o1rL Initial pressure of shock absorber 10Lrr
Initial pressure of high pressure line 8 Rear wheel side pressure of rear wheel side pressure return pipe 11 Steering angular speed Throttle opening Throttle opening/closing speed CPU 17 reads detected values Periodic vehicle speed Longitudinal acceleration (sensor 16p) Lateral acceleration (sensor 16r) Vehicle height of the front left axle Vehicle height of the front right axle Vehicle height of the rear left wheel Vehicle height of the rear right axle Heap target value Pitching target value Rolling target value Warp target value In addition, in the flow chart of the drawing and the explanation below. In some cases, the register symbol itself means 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 SW1 is closed (3), and if it is open, waits for it to close. When the ignition switch SW1 is closed, it energizes the coil of the relay RY. Then, the contact piece of self-holding relay RY is closed and maintained in that state (4).

When relay RY is turned on, f! Since the 4-source circuit 210 is connected to the battery 19, even if the ignition switch SWI is opened, the C
Until the PU 17 turns off the relay RY, all of the electrical circuits shown in FIG. 8 are electrically energized and remain in operation.

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 pulse signals to the interrupt input ports ASRO to ASR2 (5).

Here, an overview of interrupt processing in response to pulse signals to input ports ASrlO to ASR2 will be explained. First, we will 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), and 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 vsS, and proceed to the step immediately before proceeding to this separate processing. 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 vs.

A rotary encoder SNI is generated to detect the direction of rotation of the steering shaft. To explain the interrupt processing (input port ASRO) in response to the first set of generated pulses, the interrupt processing (ASRO) is started at the rising and falling edges of the first set of generated pulses, and the interrupt processing (ASRO) is started in response to the rising edge. ), write H to the flag register for determining the rotation direction, and when proceeding to interrupt processing (ASRO) in response to the falling edge, clear the flag register (write L) and start this interrupt processing. Go back to the previous step.

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 driven to rotate counterclockwise, and the rising edge of the first set of pulses appears. When the rising edge of the second set of pulses appears next to the falling edge (flag register L), the steering shaft is being driven clockwise.

Rotary encoder SNI for detecting the rotational speed (steering angular speed) of the steering shaft.

To explain the interrupt processing (input port AsR1) in response to the second set of generated pulses, when the second set of pulses (falling edge) arrives, the interrupt processing (ASRI) is performed in response to the second set of pulses.
, reads the contents of the steering timing register at that time, restarts the steering timing register, and determines that the content of the flag register for determining the rotation direction is H in the read contents (period of the steering angular velocity synchronization pulse). If the contents of the flag register contain a + (counterclockwise rotation) sign, a - (right rotation) sign is added, and then a speed value (direction +
, -), and write the value Ss obtained by taking the weighted average with the previous speed calculation values held up to that point into the steering angle speed register SS, and proceed to the step immediately before proceeding to this interrupt processing. Go back (return). This interrupt processing (ASRI
), data Ss (+ indicates counterclockwise rotation) always indicates the current steering angular velocity (time-series smoothed value of the speed calculation value) in the steering angular velocity register SS.

− indicates clockwise rotation) is maintained.

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

By the way, the CPU 18 initializes itself when it is powered on, 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.
Due to the setting of 0 or more, which instructs the notification to be sent to the
pressure is output, but the bypass valve 120 is fully open,
Also, when the pump 1 is rotationally driven while the engine is rotating, the high pressure supply pipe 8. Front wheel high pressure supply pipe 6 (accumulator 7
) and the pressure in the rear wheel high pressure supply pipe 9 (accumulator 10) begins to rise.

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

13fr, 13rL, 13rr, 13rmJ3rt,,
Acceleration sensor 16ρ.

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 80ft- and 80fr.
.

80r, 80rr and bypass valve 120, each control duty value is determined based on each of these target values and the corresponding current detection values of solenoids 5QLI to 5OL5. generate,
These are given to the duty controller 170.

Now, when the CPU 18 is giving a busy signal in the check at step 6.7, the CPU 17 waits there and executes the standby processing (8 to 11). In the standby process (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 (clearing the abnormality notification) (11) Now, when the CPU 18 outputs READY, the above-mentioned abnormality processing (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).

The CPU 17 then sends the CPU 18 to the pressure sensor L3.
Instructs to transfer the detected pressure data DPh of rm, receives it, and writes it to the register DPH (14).

The detected pressure (rear wheel side pressure of the high pressure supply pipe 8) Dph is set to a predetermined value P
ph (cut valve 70fL, 70fr, 70rL, 7
Check whether the line pressure has risen to a certain degree (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+PrLo of the pressure sensors 13fL, 13fr, 13rL, and 13rr to the CPU 18.
Instruct the transfer of rPrr□, receive them, and transfer them to registers P F Lo , P F Ro , P RL
o, write to PRRO (16).

Then, an area of the internal ROM (table 1).

The general current value data required to obtain the required pressure is stored in the registers PFLO, PFRo, PRLo,
, P RRo contents PfLo, Pfro , PrLo,
Prr (accessed with 1, current value to the solenoid required to output the pressure Pfco to the output boat 84 of the pressure control valve 8GfL, hfL, required to output the pressure PfrO to the output boat of the pressure control valve 80fr) Passing current 1st Ihfr, pressure PrLo through pressure control valve 80rL
The current value IhrL required to output to the output boat of
- and pressure Prr, ) to the output port of pressure control valve 80rr, read from Table 1 the flow value r hrr, 12.

Output registers I HfL, r Hfr, It (write to rL and IHrr (17), and transfer the data of these output registers to the CPU 18. The CPU 18 uses these data as the target value of the current, and also the current value of the detected solenoid. Based on these, a duty value is generated such that they are equal, and this value is provided 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, 80rL, and 80rr are each substantially PfLO when the line pressure is higher than the predetermined low pressure.
.

PfrO, PrLOI Output pressure of Prro boat (
84), and in response to the rise in line pressure to a predetermined low pressure or higher, cut valves 70fL+70fr, 70rLl
When 70rr is opened, the pressure (initial pressure) of each suspension at that time PfLo, Pfro, PrLOrP
A pressure substantially equal to rra is applied to cut valve 70f, and 7
0fr, 70r.

Pressure control valve 80fL through 70rr, BOfr+
8Or, suspension 100f from 80rr,
100fr, LOOrL.

Supplied to 100rr.

Therefore, only when the ignition switch SWI changes from open (engine stop: pump 1 stop) to close (pump 1 drive'!jJ) does the cut valve 70f open, 70fr, 70r.
+-.

70r is opened (the 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 the sudden pressure of the suspension is No fluctuations occur, that is, no shocking changes in the vehicle body posture occur.

The above is the 6th pressure control well 8 when the ignition switch SWI is switched from open to closed (immediately after the engine starts).
The initial output pressure settings are 0fL+80fr and 80'rL+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 sensors 15fL, 15fr, L5r, and 15rr.
Vehicle height detection data DfLt Dfr, DrLj Dr
ry pressure gas sensor 13fLfr, 13rL+ 1
Pressure detection data P of 3rr, 13rm, 13rt
fL, Pfr, PrLp Prr, PrIIIt
Prt, and pressure control valve and bypass valve 1
3ofshi,! 30 fr.

80rL, 80rr, and 120 receive the current value output data and write it into the internal register.

Then, a determination is made as to whether it is abnormal or normal by referring to the read value of Niku et al. If it is abnormal, the process proceeds to step 8.

In the normal case, the CPU 17 performs primary line control J (L
PG). In this case, the absolute value and polarity (high/low) of the deviation of the detection line pressure Prm 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 A correction value corresponding to the deviation to make the deviation zero is added to the energizing current value flowing through the bypass valve 120 to calculate the current energizing current value of the bypass valve 120, and this is written in the output register. Note that the contents of this output register are determined by -CPU in step 36, which will be described later.
Transfer to 18.

By this line pressure control J (LPC), the bypass valve 120 is operated 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. The value will have to be controlled.

Reference is now made to Figure 9b. Above line pressure control (LPC)
To finish the process, the CPU 17 checks whether the switch 20 is open or closed (22), and if it is open, it starts the stop process (22).
23), turn off the relay 22, and turn off the interrupt AS.
Prohibit RO to ASR2. In addition, in the stop processing (23), first the bypass valve 120 is set to non-quadruple current 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,
As the pressure in the return pipe 11 is released to the reservoir 2, the high pressure supply pipe 8 and the like become atmospheric pressure. High pressure supply pipe 8 etc. are cut valves 70fL, 70fr, 70rL, 70r
At the timing when the pressure r reaches a predetermined low pressure or lower, which causes complete shutoff.

The CPU 17 has pressure control valves 80fL, 80fr, 8
0rL.

Let 80rr be a non-carrying 1.

Now, when the switch SW1 is closed, a parameter indicating the vehicle running state is 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 pre-moisture calculation J (32)'' after ``vehicle height deviation calculation J (31)''.
The suspension pressure correction amount (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 (P f L
O7P f r Or P r L Or P rr
o) Calculate "first correction amount 10 second correction amount" (calculated intermediate value: for each suspension). Details of 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 13rm and the return pressure (low pressure) that is laterally compared by the pressure sensor 13rt. Details of this will be described later with reference to FIG. 10c.

Next, the CPU 17 converts the corrected "calculated intermediate value" (for each suspension) into the pressure control valve (80f, 80fr, 80rL) using the "pressure/current conversion J (34)."

+10rr) to the current value that should be passed. The details will be described later with reference to FIG. 10d.

Next, CP'U17 "corresponds to lateral acceleration Rg and steering speed Ss with warp correction J (35). Calculate the warp correction value (current correction value) during turning and send it to the pressure control valve. Add the power current value.

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

Next, the CPU 17 outputs the current value that should be passed through the pressure control valve, calculated as above, using the output J (36).
It is addressed to each pressure control valve and transferred to the CPU 18, and at the same time, the above-mentioned "value of current to be passed through the bypass valve 120 calculated by line pressure control J (LPG)" is transferred to the CPU 18, addressed 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 time has elapsed, the process returns to step 19, restarts the timer ST, and executes the suspension pressure control task for the next cycle.

Due to the suspension pressure control operation of the CPU 17 explained above, the CPU 17 requests the transfer of the sensor detection value (subroutine 20) in the ST same period (second set period), and in response to However, the sensor detection [direct data] which is read at the first set cycle and smoothed with the past several read values and the weighted average is transferred to the CPU 17. In addition, the CPU 18 is transferred from the CPU 17 with current value data that should flow through the ST same cycle, each of the pressure control valves, and the bypass valve 120, and each time the CPU 8 receives this transfer, the CPU 8 transfers these current value data and the solenoid data. A duty value is calculated from the detected current value, and the value is output to the duty controller 170. Therefore, the current value of each of the pressure control valves and the bypass valve 120 is updated in srRM so as to approach the target current value.

Referring to FIG. 10a, to explain the contents of "vehicle height deviation calculation J (31)," first, the outline is as follows.
+15fr, 15rL+15rr vehicle height detection value D
fL.

Dfr+ DrL, Drr (Register 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 right wheel side vehicle height) difference)D
Calculate RT and warp (difference between the sum of the front right axle height and the rear left wheel height and the sum of the front left axle height and the rear right wheel height) DWT. Sunarichi, 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
). The calculation of this DPT is based on the pitching error CP
Calculation of DRT is executed by Calculation of Rolling Error CR (52), and calculation of DWT is executed by Calculation of Warp Error CW (53).

Then, in "Calculation of heap error CH (50), the target heap H 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 amount CH corresponding to the heap error. .

Similarly, in "Calculation of pitching error CP J (51),
Deriving the target pitch pH from the longitudinal acceleration pg, calculating the pitch error amount of the calculated pitch DPT with respect to the target pitch pt, and performing PID processing on the calculated pitch error amount for PID (proportional, integral, differential) control. Then, the pitch correction amount CP corresponding to the pitch error is calculated.

Similarly, in "Calculation of rolling roll CR" (52), derive the 80-ru RI1. from the lateral acceleration Rg, calculate the roll roll amount for the target roll R of the calculated roll DR, For proportional, integral, and differential) control, the calculated roll error amount is subjected to PID processing to calculate a roll correction amount CR corresponding to the roll error.

Similarly, in "Calculation of warp error CW (53), the amount of warp error of the calculated warp DWT with respect to the target warp Wt is calculated by setting the target warp Whi to zero, and
For (proportional, integral, differential) control, the calculated warp error amount is subjected to PID processing to calculate a warp correction fcW corresponding to the warp error. In addition.

Calculated warp error amount (since the target warp is zero,
When the absolute value of D W T ) is less than a predetermined value (within an allowable range), the warb error to be PID processed is set to zero, and when it exceeds the predetermined value, the amount of warb error to be PID processed is set to -DldT.

To explain in detail the contents of ``heap nilla-CH calculation J (50), the CPU 17 first calculates the target heap Ht corresponding to the vehicle speed Vs in one area of the internal ROM (table 2
H) and writes it to the heap number e-register HT (39).

During the 10th session, “As shown in Table 2HJ,
The target heap H associated with the vehicle speed Vs is a high value He1 when the vehicle speed Vs is low speed below VsaKm/h, and a low value H when the vehicle speed Vs is high speed above VsbKm/h.
t2, but in the range where Vs exceeds Vsa and is less than Vsb, the target value is linear (a curve may be used) with respect to the vehicle speed Vs.
is changing. To change the target value linearly in this way, for example, if the target value is set to H at 1100 K/h or less,
If J is set so that the target value is switched to Hhi2 in one step above 1100K/h, when Vs is around 1100K/h, the target heap will change in large steps due to a slight speed change in V5. hand.

This is to prevent the vehicle height from frequently rising and falling at high speeds, resulting in poor vehicle height stability. Above table 2H
According to the setting, the target value changes only slightly due to a slight change in the vehicle speed Vs, so the change in the vehicle height target value becomes small and the vehicle height stability becomes high.

In step 40, DFL + DFR + DRL +
The heap amount obtained by calculating DRR is stored in register DHT.

In the next step 40B, a filter processing subroutine is executed. The details of this process will be explained with reference to FIG. 10f. The contents of each symbol in Fig. 10f are as follows.

Fhf: Vehicle height sensor abnormality flag KF) (: Register KF that holds filter variables
HH: Filter constant when vehicle height sensor is normal KFHL: Filter constant when vehicle height sensor is abnormal (KF'HH>KFHL
) In step 92, the voltage (H) obtained from the hide sensor (vehicle height sensor) is monitored and it is within a predetermined range (VHIIIax and VHmi in the graph in Figure 10f).
n), and if the supination is N, it is determined whether there is an abnormality in the sensor. Normally, when there is no abnormality in the vehicle height sensor, a constant KFHH is stored in KFH, but when an abnormality in the vehicle height sensor is detected, a constant KFHL is stored in KFH.

The heap amount held in the DHT is subjected to digital filter processing in a processing step not shown, and during the filter processing, the contents of the KFH are used as a parameter to determine the cutoff frequency of the filter characteristics. Nine. In this embodiment, KFHH>KFHL is set, and when an abnormality occurs in the vehicle height sensor, KFHL
is selected, the cutoff frequency of the filter is switched to a value sufficiently lower than the normal value.

When the cutoff frequency of the filter is high, even if the detected heap amount (DHT) changes relatively quickly, the heap amount equivalent to the input can be obtained at the output of the filter processing.
When the cutoff frequency is low, the output of the filter is smoothed and the change becomes gradual. In other words, when a sudden change occurs in the DHT value, that change appears in the filter output in a significantly attenuated manner.

If you set the filter cutoff frequency low.

Since the responsiveness of control to heap errors will deteriorate, in order to perform preferable suspension control, it is necessary to set the cutoff frequency of the filter high. In this embodiment, when the vehicle height sensor is considered normal, the cutoff frequency is relatively high (corresponding to KFHH).
is set, and when an abnormality is detected in the vehicle height sensor, a relatively low cutoff frequency (equivalent to KFHL) is set, so unless an abnormality occurs in the vehicle height sensor, the responsiveness of suspension control will be deteriorated by filter processing. There's nothing to do.

In addition, for example, if a malfunction occurs in the vehicle height sensor such as an open circuit or a short circuit, a sudden change will occur in the vehicle height sensor output VH. The differential term, ie, the value corresponding to the heap change (EHT2-EHTI), becomes extremely large at times, causing sudden pressure control to be performed, causing a sudden change in vehicle height and transmitting a shock to the occupants. However, in this embodiment, since an abnormality in the vehicle height sensor is detected in such a case, the cutoff frequency for filter processing is switched to a low value (KFHL). Therefore, even if there is a sudden change in the detected heap ffi (DHT), the filtered heap amount (DI(T)
2) Change in heap, that is, change in heap (EHT2- EHT
I) will not become abnormally large, and it is possible to avoid shocks caused by sudden changes in vehicle height.

Although not shown in the figure, in reality, the past N points detected at regular intervals and the latest DHT values are stored in memory, and in digital filter processing, these DH
The values of T are averaged. For example, by averaging the latest 100 DHTs obtained every 1 m5 ec, a heap amount averaged every 100 m5 ec can be obtained. Among the frequency components included in the DHT, components with a longer period (lower frequency) than the period of the average f-hi pass through the filter without attenuation and appear in the output (DHT2), but in the averaging period On the other hand, components with short periods (high frequencies) are attenuated and do not appear in the value of DHT2. In this example, the period of this averaging is stored in register KFH.
[! Determined by L.

For example, if the detection period of the heap amount by the vehicle height sensor is ΔT and the averaging period of filter processing is N・ΔT, even if the instantaneous value change amount of DHT is Varax, - control period The change in DHT2 around Vmax/N
If N is sufficiently large, it is possible to suppress the increase in the change in the filter output.

Next, write the contents of register EHT2 in which the previously calculated heap niller amount is written to register EHT1 (41
), Calculate the current heap error amount HT - DHT2 and write it to register EHT2 (42). As a result of the above, the previous heap error amount (before ST) is stored in register EHTI, and register EHT2 is stored. The current heap error amount is stored. Next, the CPU 17 writes the error integral value up to the previous time and writes the contents of the register ITH2 to the register ITH1 (43), and calculates the current PID correction amount ITh using the following equation.

ITh = Kh1 ・EHT2 +Kh2
・(EHd2+Kh3 ・ITH1)+Kha ・K
h, .(EHT2-EHTI)Kh, .EHT2 is the P (proportional) term of the PID operation, Kh is the coefficient of the proportional term, and EHT2 is the content of the register EHT2 (current heap error amount).

Kh2・(EHT2 + Kh3・ITHI) is I(
Kh2 is the coefficient of the integral term, and IT old is the previous correction amount integral value (from initial pressure settings 16 to 18,
(integral value of correction amount output), Kh3 is the current error amount E
Weighting between HT2 and correction amount integral value ITH is a coefficient.

Kh4・Kh5・(EHT2−EHTI) is a D (differential) term, and the coefficients of the differential term are Kh4・Kh5.
, uses a value associated with the steering angular velocity Ss. That is, from one area (table 3H) of the internal ROM, the vehicle speed correction coefficient Kh that is associated with the vehicle speed vs at that time.
a, and an area of the internal ROM (Table 4
H), the steering angular velocity correction coefficient Kh5 corresponding to the steering angular velocity Vs at that time is read out, and the product Kh of these is read out.
Let 4·Kh be the coefficient of the differential term.

As shown in Table 3HJ in FIG. 10a, the vehicle speed correction coefficient Kha is roughly a larger value as the vehicle speed Vs is higher, and the weight of the differential term is increased. This is a correction term that tries to quickly bring this to the target value, and the faster the vehicle speed is, the faster the vehicle height changes in response to disturbances, so it is increased according to the vehicle speed.
Vehicle speed Vs is above a certain level (VsdKm in Table 3H)
/h), if the brake is pressed/released, the accelerator pedal is used to accelerate/decelerate, the steering wheel is rotated to turn/unturn, etc., the change in the vehicle's attitude becomes sudden and extremely large. An excessively large differential term that quickly compensates for a sudden change in attitude will degrade the stability of vehicle height control.
When the vehicle speed Vs is low, the change is large, and as the vehicle speed Vs is high, the change is small. That is, when the vehicle speed Vs is low,
However, the weight of the differential term changes greatly as the vehicle speed changes.

When the vehicle speed Vs is high, the weight change of the differential term is small with respect to fluctuations in the vehicle speed.

As shown as F table 4HJ in FIG. 10a, the steering angular velocity correction coefficient Kh5 generally has a larger value as the steering angular velocity Ss becomes higher, and increases the weight of the 'p1 component. This is a correction term in which the differential term tries to quickly adjust the heap change to the target value, and the higher the steering angular speed Ss, the faster the speed of the vehicle height change in response to disturbance. It's increasing. On the other hand, when the steering angular velocity Ss is below a certain level (Ssa'/m5ec or below in Table 4H), the change in the traveling direction is extremely gradual and the weighting of the differential term is small.

Beyond Ssa and below Ssb'/m5ec, the vehicle height changes at a speed substantially proportional to the steering angular speed Ss. 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 rapid attitude change is dangerous because the vehicle height control stability deteriorates. therefore.

The coefficient Kh5 of the differential term corresponding to the steering angular speed 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 Ssb, and a constant value of the value when Ssb exceeds Ssb. It is said that

The differential term Kha・Kh5・(EHT 2−
With the introduction of EHT 1 ), and furthermore, its coefficient K
By increasing h4 in accordance with vehicle speed Vs and increasing @Kh5 in accordance with steering angular speed Ss, weighted differential control corresponding to vehicle speed Vs and steering angular speed Ss is realized, and vehicle speed Vg and steering angular speed Vs are Highly stable vehicle height control is achieved in response to fluctuations in vehicle height.

At step 44, the values of the proportional term, integral term, and differential term of the PID calculation are added, and the result is:

It is determined as heap error correction 1k ITh.

Next, the CPU 17 calculates the calculated heap error correction amount ITh.
is written in 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). , writes to heap error register CH.

When the heap error CH calculation (50) is executed as described above, CPtJL7 executes the pitching error CP calculation J (51) to calculate the pitch error correction amount CP.
It is calculated in the same way as the heap error CH and written to the pitch error register CP. In this case, the heap target value H
The pitch target value PT corresponding to T is the internal R of CPUL7.
Data Pt corresponding to the longitudinal acceleration pg at that time (target value according to the longitudinal acceleration Pg) is read out from one area of the OM (table 2P).

In pitch error calculation, vehicle height sensor 15fL,
l 5fr+ In order to prevent shock in the event of failure of 15rL and 15rr, the detected pitching amount DPT
The same digital filter processing as for the heap amount is applied to the heap amount.

FIG. 11a shows the contents of table 2P. The pitch target value P corresponding to the longitudinal (post-acid direction) acceleration Pg is in the 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)'', and the HT and Hl of step 39 are the same.

is replaced with PT, Pt, the DHT calculation formula in step 40 is replaced with the above-mentioned DPTg output formula, and the EHT in step 41 is
L, EHT2 is replaced with EPTI, EPT2, and EHT2. HT, DHT to EPT2. P.T., D.P.
Replace ITHI and ITH2 in step 43 with T.
PI and ITP2, the ITh calculation formula of subroutine 44 is replaced with a pitch error correction amount ITP calculation formula that has a completely corresponding relationship, and table 3H is replaced with a coefficient table (3P) for calculating pitch correction amount ITP. However, table 4H also has pitch correction amount ITpE1. ITH2 and ITh in step 45 are replaced with ITP2. CH in step 46,
By replacing Kh,,ITh with CP r KPs 1ITp, "Pitch error CP operation J (51)
A flowchart showing the contents will appear. The CPU 17 executes the processing 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.
write to. In this case, the roll target value RT corresponding to the heap target value HT is obtained from an area (table 2R) of the internal ROM of the CPU 17 as data R+ corresponding to the lateral acceleration Rg at that time, and (roll corresponding to the lateral acceleration Rg). target value).

Also in the roll error calculation, the vehicle height sensor 15fL+
In order to prevent shock in the event of failure of 15fr, 15rL, and 15rr, the detected rolling amount DRT is subjected to digital filter processing similar to that for the heap amount.

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. a
In the area b, the target roll is increased (decreased) as the lateral acceleration Rg increases (decreases) in order to save energy.For the area b, the abnormal Rg may indicate an abnormality in the sensor, so the roll target value is decreased. 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 Hhi of step 39 are RT.

Rt, and the DHT calculation formula in step 40 is replaced with the above-mentioned C.
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.
Substitute r, or step 46 (7) CH, Khs,
CR I Th.

By replacing Kr6 and ITr, a flowchart showing the contents of "Roll error CR calculation J (51)" appears.The CPU 17 executes the process shown in this flowchart.

Next, the CPU 17 executes “warp error CW't* EC”.
Execute J(53) to perform warp error correction ffi CW
of.

It is calculated in the same way as heap nilla-CH and written to the warp error register CW. In this case, the heap target value H
The warp target value Pw corresponding to T is set in the atmosphere.

In the warp error calculation, vehicle height sensor 15fL,
In order to prevent a shock when L5fr, 15rL, and 15rr fail, the detected warp amount DWT is subjected to digital filter processing similar to that for the heap amount.

The other arithmetic processing operations are the same as the above-mentioned "heap error CH operation J (50)," and step 39
Replace HT, Ht with WT, O, and DH in step 40
Replace the T calculation formula with the above-mentioned DWT calculation formula, and step 41
EHTI and EHT2 of are replaced with EWTl and EWT2, and the contents of step 42 are changed so that the absolute value of DWT is a predetermined mWl.
When the value is below (within the allowable range), WT is set to 0, and when it exceeds Wm, WT is set to -DWT, and WT is written to register EVT2.
l, lTR2 are replaced with ITWL, ITW2, and the ITh calculation formula of subroutine 44 is replaced with a warp error correction amount ITw calculation formula that has a completely corresponding relationship, and Table 3
H is expressed as a coefficient table for calculating the warp correction amount ITr (3w
), table 4H is also replaced with coefficient tape/L7 (4w) for calculating the warp correction amount ITti, and step 45 (7) lTR2°ITh is replaced with ITW2. IT- and step 46171CH,Kh, , r
By replacing Th with CW, Kw6, and IT11, a flowchart showing the contents of "computation of warp error cw" (53) appears.

The CPU 7 executes the processing shown in this flowchart.

As described above, after calculating the heap error correction amount c [(, pitch error correction zcp, roll error correction amount CR, and warp error correction amount WP), the CPU 17 converts these correction amounts into suspension pressure correction amounts for each axle. EHf
+- (suspension 100f L), E Hf
r (to LOOfr), E HrL (to 100rL).

E Convert back to Hrr (addressed to 100rr). That is, the suspension pressure correction amount is calculated as follows.

E HfL=KfL-Kh7・(1/4)・(CH-C
P+CR+CW).

EHfr =Kfr-Kh741/4)・(C1(-C
P-CRCW).

E HrL=Kr+-・Kh7・(1/4)・(CH+
CP+CRCW).

E Hrr = Krr - Kh7. (l/4)・(C1
(+CP-CR+C'j) coefficients KfL, Kfr, KrL
, Krr is the suspension 100k with respect to the line pressure reference point 13ri and the return pressure reference point 13rt,
], 0Ofr, 100r, and 100rr due to the difference in piping length. This is a correction coefficient for compensating for suspension supply pressure deviation. Kh7 is a coefficient for increasing or decreasing the rJ height deviation correction amount in accordance with the steering angular speed Ss, and CP
This is read out from one area (Table 5) of the internal ROM of U17 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 set large in proportion to the steering angular speed Ss.

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 extremely gradual and the attitude change is small and gradual. Attitude changes occur at proportional speeds. At a steering angular velocity exceeding Ssd, the change in vehicle body attitude becomes rapid and extremely large, and an excessive correction amount that quickly compensates for such a sudden attitude change is necessary if the vehicle height is 1. II stability will deteriorate. Therefore, the correction coefficient Kh7 corresponding to the steering angular speed J￥iS s is a constant short value when -Ss is less than Ssc, a large value that is substantially proportional to Ss when it exceeds Ssc and less than Ssd, and when it exceeds Ssd, when Ssd The value of is set as a constant value.

Next, the contents of the pitching/rolling prediction calculation J (32) will be explained with reference to FIG. This system detects the current vehicle body posture based on the current vehicle deflection 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 CGT for suppressing a change in pitch due to a change in longitudinal acceleration pg (55 to
58). In this case, write the previous correction amount for 2g and transfer the contents of register GPT2 to register GPTI.
(55), 1 area of internal ROM (Table 6)
Then, the correction amount Qpt corresponding to Vs and pg is read out and written in the register GPT2 (57). The data Gpt in table 6 is grouped as a Vsti-index, and the CPU 17 specifies the group by Vs. Then, the 2g compatible data ape in the specified group is read. For each group, the smaller the Vs is assigned, the larger the insensitive fa width (@ next to Gρ and 20 in Table 6 shown in FIG. 10b) is set. b is a region where the gain is increased as the longitudinal acceleration Pg increases and control performance is improved, and C is a region where control performance is degraded because it is considered to be more than the sensor.

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

CGP = KgP 3・(Kgpt・GPT2+K
gPz.(GPT2-GPTI))GPT2 is the content of register GPT2, and is the correction amount Gpt read out from table 6 this time.

GPTI is the content of register GPTI, and is the correction amount read out from table 6 last time. P (proportional) term Kg
KgPl of P1·GPT2 is a coefficient of the proportional term.

D (differential) term KgP2・(GPT2-GPTI) Kg
P2 is a coefficient of the differential term, and this coefficient KgP2 is read out from an area of the internal ROM (Table 7) corresponding to the vehicle speed Vs. "Table 7" in Figure tab.
As shown by J, the coefficient KgP 2 has a larger value as the second vehicle speed Vs is higher, and increases the weight of the differential term. This is a correction term in which the differential term tries to quickly suppress changes in the longitudinal acceleration Pg, and the higher the vehicle speed, the more the brake is depressed/released, the accelerator pedal is used to accelerate/decelerate, the steering wheel is rotated to turn/unturn, etc. The longitudinal acceleration P due to
This is because the change in g is fast, so the attitude change is quickly suppressed in response to this fast change. On the other hand, when the vehicle speed Vs exceeds a certain level, if the brake is depressed/released, the accelerator pedal is used to accelerate/decelerate, the steering wheel is rotated to turn/unturn, etc., the change in the longitudinal acceleration pg becomes rapid and extremely large. 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 Kgρ2 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, vehicle speed V
When s 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 a pitch correction amount for the suspension, and Kg
P3 is a weighting coefficient for roll correction amounts CGR and GES, which will be described later.

Next, the CPU 17 calculates a correction amount CGR for suppressing changes in roll due to changes in lateral acceleration Pg (that is, suppressing changes in lateral acceleration Pg) (59 to 62). In this case, the contents of the register CRT2 in which the previous correction amount corresponding to Rg was written are written to the register GRTI (59).
, read out the correction amount Gre corresponding to Vs and Rg from one area (table 8) of the internal ROM and store it in register C.
The data Crt of table 8 written to RT2 (61) is grouped using Vs as an index, and the data Crt of table 8 is written to RT2 (61).
specifies a group with Vs and reads out the data Crt corresponding to Rg within the specified group.Each group is as follows.
The smaller the Vs assigned, the dead band a width (
Next to Crt=O in table 8 shown in Figure 10b @)
is set large. b is a region where the gain is increased as the lateral acceleration Rg increases and control performance is improved, and C is a region where gender performance is degraded because it is considered to be more than a sensor.

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・CKgrl−GRT2+Kgr2
(GRT2-GRTI)] GRT2 is register GRT2
This is the content of the correction amount G read out from Table 8 this time.
r11. It is. GRTl is the content of register GRTI, and is the correction amount read from table 8 last time. P
Kgr 1 of the (proportional) term Kgr1/GRT2 is a coefficient of the proportional term.

D (differential) term Kgr2 ・Kgr2 of (GRT2 GRTI) is a coefficient of the differential term, and this coefficient grz is
An area of internal ROM corresponding to vehicle speed Vg (Table 9)
This is what was read from. As shown in "Table 9" in Fig. TOB, the coefficient Kgr2 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 is a correction term that tries to quickly suppress changes in lateral acceleration Rg, and the higher the vehicle speed, the faster the change in lateral acceleration R4 due to turning/returning due to steering rotation. This is to quickly suppress this problem. On the other hand, when the vehicle speed Vs exceeds a certain level, when turning/returning due to steering rotation is performed rapidly, the change in lateral acceleration Rg becomes sudden and extremely large. An excessively large differential term degrades the stability of lateral acceleration suppression. Therefore, the coefficient Kgr2 in Table 9 changes significantly when the vehicle speed Vs is low, and remains constant when the vehicle speed Vs is equal to or higher than a predetermined room. 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 1cGP described above and the roll correction ff1GEs described below, but when the vehicle speed ■S is low, the amount of lateral acceleration Rg is Since the rate of change is low, this roll correction amount CGR
In order to reduce the contribution ratio of
Coefficient data Kgr3 is stored in one area of OM (table 10) in correspondence with the speed Vs. The CPU 17 has a speed V
The coefficient Kgr3 corresponding to s is read out and the above-mentioned CGR
Used to calculate.

Next, the CPU 17 converts the calculated pitch correction amount CGP, roll correction amount CGR, and roll correction amount DES&-1 into pressure correction amounts addressed to each suspension, and applies these pressure correction amounts to "vehicle height deviation calculation J ( The value EH calculated in 31)
fL, EHfr+ EHrLyEHrr (contents of registers EHfL, EHfr, EHrL, EHr+-) to obtain the sum [EhfLr Ehfr, E
hrL, Ehrr in register EHfL, Et(fr
, EHrL, El (write update to rr (66)
.

EhfL=EIIfL+KgfL□(1/4>・(−C
CP+Kt4rfCGn+KgefL・GES)Ehf
r ==EIIfr +Kgfr・(1/4)・(CG
P-Kcgrf-CGR+KgefrGES)EhrL
=EHrL+KgrL・(1/su・(CGP+Kcgr
r-CGR+KgerL-GES)Ehrr==EH
rr +Kgrr (1/4)・(CGP+Kcgrr
-C(lR+KgerrGEs) The first term on the right side of the above equation is
The value calculated using vehicle height deviation calculation J (31) as previously described,
Registers EHf L, EHfr.

EHrLr EHrr, 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 1GEs into pressure correction values for each suspension.

In addition, the coefficient KgfL+ Kgfr, Kg of the second term on the right side
rL and Kgrr are: KgfL = KfL 4gs.

Kgfr = Kfr - Kgs.

KgrL = KrL - Kgst Kgrr = Krr°Kgs where KfL, Kfr, KrL, 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. , gs is the steering angular velocity S as shown in Table 12.
It is a predetermined coefficient associated with s, and is
R pitching/rolling pre-calculation J (32) for the pressure correction value calculated in vehicle height deviation calculation J (31)
It was calculated by Pressure correction for suppressing acceleration changes (second term on the right side of equation 4 above: (1/4) - (-CGP + K
(cgrf-CGR+Kgef L-GES) etc.) If the steering angle modulus 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 acceleration changes. 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''/rasec or less in Table 12), the change in acceleration is extremely small, exceeding Sse and Sd' 7m5ec.
Below, the acceleration changes at a speed substantially proportional to the steering angular speed Ss. At steering angular speeds greater than Ssf, the change in turning radius becomes rapid and extremely large, resulting in a change in acceleration (
In particular, when the lateral acceleration is extremely large, an excessive correction amount that quickly compensates for such a sudden change in acceleration deteriorates the stability of acceleration control. Therefore, the weighting coefficient Kgs corresponding to the steering angular speed Ss is a constant value when Ss is less than Sse, a high value that is substantially proportional to Ss when it exceeds Sse and less than Ssf, and a constant value directly proportional to Ss when it exceeds Ssf. It is said that

Next, the CPU 17 registers the initial pressure register P F L or
Write initial pressure data to P F R () r P R Lo and P RRO (set in steps 16 to 18)
is added to the sum of the correction pressure for vehicle height deviation adjustment and the correction pressure for acceleration suppression control (contents of registers EHfL, EHfr, EHrL, and EHrr) calculated in subroutine 66, and set for each suspension. Calculate the power pressure and register EHfL* EHfr, EHrL
, updates are written to EHrr (67).

Referring to FIG. 10c, the contents of the pressure correction J (33) will be explained. The correction value PH that compensates for the fluctuation of
(contents of register DPt).

The correction value PLfC front @ what correction (direct) and PLr (rear shaft correction fii
A pressure correction value FDP = PH - PLf and P Dr read from L) to compensate for fluctuations in the pressure control valve output pressure due to fluctuations in the line pressure and return pressure applied to the pressure control valve.
= Calculate P H−P Lr (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 close to the reservoir and the rear wheel side is far from the reservoir, and the pressure sensor 13r for low pressure detection is on the rear wheel side. Since the return pressure is detected, the return pressure difference between the rear wheel side and the front wheel side is relatively large, so this is to reduce errors caused by this. Table 13L lists 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 is for the front wheel suspension, and the former is for the rear wheel suspension. From the data group, a correction value corresponding to the pressure detected by the pressure sensor 13r at that time is read out.

After calculating the correction values PDf and PDr, the CPU 17 stores these correction values in registers EIIfL and EHfr.

In addition to the contents of EllrL, EHrr, register EH
fL, [EIIfr, EtlrL, ['Update to Hrr (70).

Referring to FIG. 10d, to explain the contents of "pressure/current conversion J (34), the CPU 17
L y EHfr p EHr L and EHrr data EHfL.

Pressure control valve 80fL+80frt to generate the pressure indicated by EHfr, Ellr L and EHrr
Current value I hfL to be applied to 80r and 80rr
tIhfr, IhrL and Ihrr are read from the pressure/current conversion table 1 and input to the current output registers IHfL, l1lfr, respectively.

IHr L and I) Write to Irr (34).

The details of warp correction (35) will be explained with reference to FIG. 108. This warp correction (35) calculates an appropriate target warp DWT from the lateral acceleration Rg and the steering angular velocity Ss.
3), and the aforementioned register IHfL+IHfr,
It is necessary to calculate the warp that appears when the contents of IHrL+Hlrr are output, and calculate the error warp amount with respect to the target warp DWT (74 to 76), to make this error warp amount zero. Current value dIfL, dI
fr, dIrL, and dIrr (77), and store these current correction values in registers IHk, I) Ifr,
If(rL, is added to the contents of l1lrr, and the sum is updated and written to these registers (78).

A warp target value dr corresponding to the lateral acceleration Rg is written in one area (table 14) of the internal ROM of the CPU 17, and a warp target value Ids corresponding to the steering angular velocity Ss is written in the table 15. Ori.

In the table 16, warp correction amounts Idrs corresponding to the vehicle body longitudinal inclination and lateral acceleration Rg (lateral inclination) defined by the values of the registers IHfL, IHfr, IHr, and IHrr to be output are written.

In addition, the longitudinal inclination is K= l (IhfL+Ihfr)/(IhrL+Ih
rr) 1, data groups corresponding to this are written in the table 16, and each data of 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 from the table 14, reads the warp target value Idr corresponding to the steering angular velocity Ss, and sets the values of the registers IHfL, IHfr, IHrL, and Irr. The warp correction amount IdrS corresponding to the specified vehicle body longitudinal inclination and 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=Kdw14dr+Kdw2 ・Ids+Kdw
3 ・IdrsCPU17 next registers IHfL,
IHfr, IHrL.

Contents of IHrr IhfL, Ihfr, IhrL, Ihr
Warp defined by r (IhfL Ihfr) (IhrL −1hrr
) 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 (IhfL-Ihfr
) - (IhrL - Ihrr) is written to the warp error correction amount register DWT (75), and if it is within the allowable range, the contents of the register DWT (DWT) are not changed, and the warp error correction amount DWT (register The content of DWT) is multiplied by the weighting coefficient Kdν4, the product is updated and written to the register DWT (76), and this warp error correction amount DWT is applied to each suspension pressure correction amount (more precisely, it corresponds to the pressure correction amount). Pressure control valve energizing current correction value) (77), and the correction value is converted to current output register It (fL*IHfr, IHr and IHr).
Add to the contents of r (78).

These current output registers IHf L , IHfr
, IHr L and IHr r data are determined by "output J (36) subroutine, pressure control valve 80f,
To 80fr, 80rr and 80rr, CP10
8 and the CPU 18 transfers it to the duty controller 3.
Give to 2.

[Effect] As described above, according to the present invention, detected vehicle height information (
Digital filter processing is applied to the vehicle height detection means (15fL, 15fr, 15rL).

15rr) fails, the cutoff frequency of the filter is lowered, so even when a sudden change appears in DHT, the change is smoothed and affects the value of the differential term, so an abnormally large value of the differential term will not occur. Therefore, it is possible to prevent shock from occurring in the suspension.

[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. Figures 2, 3, 4, 5, 6 and 7 respectively show the suspension 100fr shown in Figure 1.
, pressure control valve 80fr, cut valve 70fr!
Relief valve 60fr, main check valve 50
2 and an enlarged longitudinal 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. 10a, 10b, 10c, 10d, 10e, and 10k are flow charts 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. 1: Pump 2: Reservoir 3: High pressure port 4: Attenuator 6: Front wheel high pressure supply pipe 7
: Accumulator 8: High pressure supply pipe 9: Rear wheel high pressure supply pipe 10: Accumulator 11: Reservoir return pipe 12 Nidrain return pipe 13k, 13fr
, 13rL, 13rr, 13rm, 13rt: Pressure sensor 14k, 14fr, 14rL, 14rr: Drain of atmospheric release 15k + 15fr, 15rL+
15rr: Vehicle height sensor 16p, 16r: Acceleration sensor 17.18: Microprocessor 19: Battery 50: Main check valve 51: Valve base 52: Input boat 53: Output boat 54: Valve seat 55: Flow port 56: Compression coil Spring 57: Ball valve 60fr, 60k, 60rr, 60rL: Relief valve 61: Valve 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 6011
: Main relief valve 70fr, 70k, 70rr, 70rL: Cut valve 71: Valve body 72 Line pressure boat 73:
Pressure regulation input port door 4: Drain port 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 92: Compression coil spring 93: Valve body 94: Flow path 95: Two dollar valve 96:
Fixed core 97: Plunger 98a: E-ri 98
b = End plate 98c: Low pressure port 100fr, 100k JOOrrJOOrL: Suspension 101fr, 101k, 101rr, 101
rL: Shock absorber 102fr, 102k JO
2rr, 102rL: Piston rod 103: Piston, 104: Inner cylinder 1o5: Upper chamber 106: Lower chamber
107: Side entrance 1o8: Upper and lower through hole 1
09: Damping valve device 110: Upper space 111:
Piston 112: Lower chamber 113: Upper chamber
114: Outer cylinder 120: Bypass valve
121: Input port 122: Low pressure boat 122a:
Low pressure boat 122b: Channel 123: First guide 12
4a: Valve body 1211b: Compression coil spring 1
25: Two dollar valve 150: A/D conversion unit 170: Duty control unit (duty controller) 180: Current detection unit 1 0.20
0: Driver RV: Relay 5I
JI: Ignition switch SW2: Vehicle speed sensor (
Reed switch) SW3 Nistop lamp switch
5Ii14: Door switch 5tys: Reservoir level warning switch SW6: Vehicle height: A adjustment switch SNI steering sensor SN2: Throttle sensor 5QLI to 5OL5: Solenoid patent inventor Toyota Motor Corporation

Claims (1)

[Scope of Claims] A suspension mechanism including an actuator that expands and contracts in accordance with supply and discharge of fluid; Vehicle height detection means that detects changes in vehicle height due to expansion and contraction of the actuator; Pressure source means that supplies fluid to the actuator; Adjustment valve means for controlling the supply and discharge of fluid from the pressure source means to the actuator; and the detected vehicle height value detected by the vehicle height detection means are passed through digital filter processing to remove a predetermined high frequency change component. , based on the difference between the processing result and the control target value, adjusts the control amount of the regulating valve means, and also identifies whether or not there is an abnormality in the vehicle height detecting means, and when it is determined that there is an abnormality, the digital filter A suspension control device comprising: electronic control means for adjusting a processing parameter and lowering a cutoff frequency of the filter processing compared to a normal state.