JP2895517B2 - Suspension control device - Google Patents

Description

The present invention relates to a suspension control device used for a vehicle, and more particularly, to a vehicle having a sensor for detecting a vehicle height at each wheel position. The present invention relates to a suspension control device that performs suspension control according to high information.

[Related Art] Generally, in suspension control, a behavior of a vehicle is detected by a predetermined sensor, and a shock absorber is adjusted so that a damping force or a spring constant of the suspension changes according to the detection result.

In this type of suspension control, if a sensor that detects the behavior of the vehicle fails, abnormal control is performed or suspension control becomes impossible.

In Japanese Patent Application Laid-Open No. 63-185510, a plurality of sensors for detecting the behavior of a vehicle are provided, and when an abnormality occurs in one of the sensors, a detection value of the remaining normal sensor is used. It has been proposed that attitude control be continued.

[Problems to be Solved by the Invention] For example, vehicle height sensors are arranged at positions FL (front left), FR (front right), RL (rear left), and RR (rear right) of each of four vehicles, When obtaining attitude information using these sensors, if the vehicle is horizontal, the four vehicle height sensors output the same vehicle height value.For example, when the vehicle height sensor at the FL position fails, the If the vehicle height detected by the vehicle height sensor is used instead of the vehicle height at the FL position, for example, vehicle height adjustment can be normally performed.

However, when the vehicle is tilted and suspension control for pitch and roll is to be performed, since each vehicle height sensor detects a different vehicle height value, Japanese Patent Application Laid-Open No. 63-185510 discloses Thus, the detection values of the remaining sensors cannot be substituted.

For example, the detected vehicle height value of each sensor in the horizontal state is 5
Assuming that the detected vehicle heights of FL, FR, RL, and RR are 2, 6, 4, and 8, respectively, in a certain posture state, if the following formula is used, the pitch amount is 4, and the roll amount is 4. The amount will be -8.

Pitch amount = -HFL-HFR + HRL + HRR Roll amount = HFL-HFR + HRL-HRR HFL, HFR, HRL, HRR are detected vehicle heights at each position Here, assuming that the FL sensor has failed, the detected vehicle height is diagonal. When the position HRR is substituted, the pitch amount becomes −2 and the roll amount becomes −2, which is significantly different from the original pitch amount and roll amount. In particular, in this example, since the polarity of the pitch amount is reversed, if the suspension control is performed according to this, the suspension is adjusted in the opposite direction to the original direction, and the pitch amount is rather increased.

An object of the present invention is to prevent a vehicle body posture and a vehicle height from becoming abnormal even when an abnormality occurs in a vehicle height detecting unit.

[Structure of the Invention] [Means for Solving the Problems] In order to solve the above problems, in the present invention, a suspension mechanism including an actuator that expands and contracts in accordance with supply and discharge of fluid at each wheel position; Pressure source means for supplying fluid; a plurality of regulating valve means for controlling supply and discharge of fluid from the pressure source means to the actuator; vehicle height information that changes in accordance with expansion and contraction of the actuator near each wheel. A plurality of vehicle height detecting means for detecting; a heave, a roll, a pitch and a warp of the vehicle are calculated based on the detected vehicle heights of the plurality of vehicle height detecting means, and an actuator control of each wheel position is performed based on the calculation result. And controlling the regulating valve means in accordance with the actuator control amount, and calculating the calculated value with respect to the actuator control amount. The influence of each heave, roll, pitch and warp of the vehicle is set to a state different from at least one of the other vehicles, the presence or absence of abnormality in each of the vehicle height detection means is identified, and if an abnormality is detected, , The value of the detected vehicle height assigned to the vehicle height detecting means in which the abnormality is detected,
Electronic control means for switching to a value substantially equal to the target vehicle height in the heave attitude and continuing control of each regulating valve means;

[Operation] In the present invention, when the abnormality of the vehicle height detecting means is detected, the value of the detected vehicle height assigned to the vehicle height detecting means in which the abnormality is detected is substantially equal to the target vehicle height in the heave attitude. Control is continued by substituting the same value.

For example, as in the above-described example, the detected vehicle height values of the vehicle height sensors at the respective positions of the four wheels in the horizontal state are 5, and the detected vehicle heights of FL, FR, RL, and RR in a certain posture state are respectively Assuming that the FL sensor has failed at 2, 6, 4, and 8, the detected vehicle height of FL is substituted by 5. in this case,
The calculated pitch amount is +1 and the roll amount is -5.
become. Since the actual pitch amount is +4 and the roll amount is -8, the control result slightly changes compared to when the sensor is normal, but the polarity, that is, the control direction does not change.
There is no risk of abnormal suspension control being performed, and changes in attitude such as roll and pitch can be reliably reduced as compared to when suspension control is not performed.

In the present invention, the influence of the change in the detected attitude of heave, roll, pitch, and warp on each attitude control amount is set so that at least one of heave, roll, pitch, and warp is different from the others. It is. That is, the heave, the roll,
When detecting the vehicle attitude of the pitch and the warp and converting the attitude control amount corresponding thereto into the actuator control amount of each wheel position, if the influences are all the same, for example, the actuator control amount of the FL position Depends only on the detected vehicle height at the FL position, and is not affected at all by the detected vehicle height at the FR, RL, and RR positions (described in detail in the embodiment). In this case
When the detected vehicle height at the FL position is substituted for the target vehicle height in the heave posture, the control amount of the actuator at the FL position becomes zero, and no control is performed on the actuator at this position. However, if the influence is set so that at least one of heave, roll, pitch, and warp is different,
Even when the attitude control amounts of heave, roll, pitch, and warp are converted into, for example, an actuator control amount at the FL position, the actuator control amount includes a detected vehicle height component other than the FL. Even when the detected vehicle height is substituted by the target value, control is performed on the actuator at the FL position. Therefore, even when the vehicle height detecting means breaks down, various attitude controls can be continued normally.

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

[Embodiment] Fig. 1 shows an outline of a mechanism section of a suspension apparatus for a vehicle embodying the present invention. The hydraulic pump 1 is a radial pump, is disposed in an engine room, and is connected to a drive output of an on-vehicle engine (not shown) by a belt. The oil is discharged to the high pressure port 3 at a predetermined flow rate at the rotation speed of.

The high pressure port 3 of the radial pump for suspension pressure is connected to an attenuator 4, a main check valve 50 and a relief valve 60m for absorbing pulsation.
The 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 reverse flow of oil from the high pressure supply pipe 8 to the high pressure port 3 when the high pressure port 3 is lower than the pressure of the high pressure supply pipe 8.

When the pressure of the high-pressure port 3 becomes equal to or higher than a predetermined pressure, the relief valve 60m allows the high-pressure port 3 to flow through a reservoir return pipe 11, which is one of the oil return paths to the reservoir 2, to substantially reduce the pressure of the high-pressure port 3. Maintain the upper constant pressure.

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

A pressure control valve 80fr is connected to the front wheel high-pressure supply pipe 6 via an oil filter, and the pressure control valve 80fr controls the pressure of the front wheel high-pressure supply pipe 6 (hereinafter referred to as front wheel line pressure) to a required pressure (the electric pressure thereof). Pressure is reduced (stepped down) to the pressure corresponding to the current value of the coil: suspension support pressure) and cut valve 70fr
And give to the relief valve 60fr.

When the pressure of the front wheel high-pressure supply pipe 6 (front wheel side line pressure) is lower than a predetermined low pressure, the cut valve 70fr is connected to the output port 84 of the pressure control valve 80fr (to the suspension) and the suspension 10
0fr shock absorber 101fr hollow piston rod 10
2fr, the pressure from the piston rod 102fr (shock absorber 101fr) to the pressure control valve 80fr is prevented, and the output pressure of the pressure control valve 80fr is maintained while the front wheel side line pressure is equal to or higher than a predetermined low pressure. (Suspension support pressure) is supplied to the piston rod 102fr as it is.

The relief valve 60fr limits the internal pressure of the shock absorber 101fr to an upper limit or less. That is, the pressure control valve 80
When the pressure at the output port 84 of fr (suspension support pressure) exceeds a predetermined high pressure, the output port 84 is connected to the reservoir return pipe.
As a flow through 11, the pressure at the output port of the pressure control valve 80fr is maintained substantially below a predetermined high pressure. Further, the relief valve 60fr buffers the shock absorber 101fr when the internal pressure of the shock absorber 101fr rises due to a thrust from the road surface to the front right wheel and the shock absorber 101fr rises, and the shock absorber 101fr When the internal pressure of the shock absorber 101 rises, the internal pressure of the shock absorber 101fr is released to the reservoir return pipe 11 via the piston rod 100fr and the cut valve.

The suspension 100fr generally includes a shock absorber 101fr and a suspension coil spring 119fr. The pressure (pressure control) supplied into the shock absorber 101fr via the output port 84 of the pressure control valve 80fr and the piston rod 102fr. The vehicle body is supported at a height (with respect to the front right wheel) corresponding to the pressure adjusted by the valve 80fr: suspension support pressure.

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

A vehicle height sensor 15fr is mounted on the vehicle body near the suspension 100fr, and a link connected to the rotor of the vehicle height sensor 15fr is connected to the front right wheel. The vehicle height sensor 15fr generates an electric signal (digital data) indicating the vehicle height of the front right wheel portion (the height of the vehicle body with respect to the wheels).

The pressure control valve 80f _L , cut valve 70f _L ,
Relief valve 60f _L, height sensors 15f _L and the pressure sensor
Similarly, 13f _L is assigned to the suspension 100f _L of the front left wheel portion, and a pressure control valve 80f _L is connected to the front wheel high pressure supply pipe 6 to apply a required pressure (support pressure) to the suspension 100f _L. To the piston rod 102f _L of the shock absorber 101f _L.

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

Further, as described above, the pressure control valve 80r _L and the cut valve 70
r _L , the relief valve 60r _L , the vehicle height sensor 15r _L and the pressure sensor 13r _L are likewise connected to the front left wheel suspension 100r.
Is equipped by assigning _{L, and} the pressure control valve 80 r _L is connected to the rear wheel high pressure feed pipe 9, it gives the required pressure (supporting pressure) on the piston rod 102r _L of the shock absorber 101 r _L suspension 100r _L.

In this embodiment, the engine is mounted on the front wheel side, and accordingly, the hydraulic pump 1 is mounted on the front wheel side (engine room), and the piping length from the hydraulic pump 1 to the rear wheel side suspension 100rr, 100r _{L is} reduced. , the front wheel suspension 100fr from the hydraulic pump 1 is longer than the pipe length to 100f _L. Therefore, the pressure drop due to the pipe passage is large on the rear wheel side, and if oil leakage or the like occurs in the pipe, the pressure drop on the rear wheel side is the largest. So, in the rear wheel high pressure supply pipe 9,
The line pressure detection 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, and the pressure tends to increase as the distance from the reservoir 2 increases. Therefore, the pressure of the reservoir return pipe 11 is also on the rear wheel side, and the pressure sensor 13rt is used. I try to detect.

A bypass valve 120 is connected to the rear wheel high pressure supply pipe 9. The bypass valve 120 adjusts the pressure of the high-pressure supply pipe 8 to a pressure corresponding to a current value of the electric coil (obtains a required line pressure). When the ignition switch is opened (the engine stops: the pump 1 stops), the line pressure is reduced to substantially zero (the atmospheric pressure of the reservoir 2 through the reservoir return pipe 11). , 70f _L , 70rr, 70r _L
Is turned off to prevent pressure loss of the shock absorber), and lighten the load when the engine (pump 1) is restarted.

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

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

When the piston rod 102fr tries to rapidly enter the lower part of the inner cylinder 104 due to the upward rise of the front right wheel,
The internal pressure of the inner cylinder 104 rapidly rises, and the pressure of the lower space 110 similarly tries to suddenly become higher than the pressure of the lower chamber 112. At this time, oil is allowed to flow from the lower space 110 to the lower chamber 112 when the pressure difference is equal to or more than the predetermined pressure difference of the damping valve device 109, but the oil flows through the lower space 110 through a check valve that prevents the flow in the reverse direction. From lower room 112
, Whereby the piston 111 rises and buffers the impact (upward) applied from the wheel to the piston rod 102fr. In other words, wheel impact on the vehicle body (upward impact)
Is propagated.

When the piston rod 102fr tries to relatively move upward from the inner cylinder 104 due to a sudden drop of the front right wheel, the inner cylinder
Similarly, the pressure in the lower space 110 is about to suddenly fall below the pressure in the lower chamber 112 because the internal pressure of the chamber 104 is rapidly reduced. At this time, the oil is allowed to flow from the lower chamber 112 to the lower space 110 at a pressure difference equal to or greater than the predetermined pressure difference of the damping valve device 109, but the oil flows through the lower chamber 112 through a check valve that prevents the flow in the reverse direction. From below flows into the lower space 110, whereby the piston 111 descends and buffers the propagation of the impact (downward) applied from the wheel to the piston rod 102fr. That is, the propagation of the wheel impact (falling down) to the vehicle body is buffered.

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

When there is no relative vertical movement of the piston rod 102fr with respect to the inner cylinder 104, such as during parking, oil leakage from the inner cylinder 104 into the outer cylinder 114 is substantially prevented by the seal between the inner cylinder 104 and the piston rod 102fr. There is no. But Pistonsudo
In order to reduce the vertical movement load of the 102fr, the seal has sealing characteristics such that a slight oil leak occurs when the piston rod 102fr moves up and down. The oil leaking to the outer cylinder 114 is returned to the reservoir 2 through the outer cylinder 114, through the drain 14fr (FIG. 1) that is open to the atmosphere, and through the drain return pipe 12 (FIG. 1) as the second return pipe. The reservoir 2 is equipped with a level sensor 28 (FIG. 1).
Generates a signal (oil shortage signal) indicating this when the oil level in the reservoir 2 is equal to or lower than the lower limit value.

Other suspension 100f _L, the structure of 100rr and 100r _L also is substantially the same as the structure of the aforementioned suspension 100FR.

FIG. 3 shows an enlarged vertical cross section of the pressure control valve 80fr. The sleeve 81 has a spool storage hole at the center thereof, and a ring-shaped groove 83 communicating with the line pressure port 82 and a ring-shaped groove 86 communicating with the low-pressure port 85 are formed on the inner surface of the spool storage hole. Have been. These ring-shaped grooves 83
The output port 84 is open between the points 86 and 86. The spool 90 inserted into the spool storage hole is in the middle of the side peripheral surface,
A ring-shaped groove 91 having a width corresponding to the distance between the right edge of the groove 83 and the left edge of the groove 86 is provided. A valve storage hole is formed in the left end of the spool 90, and the valve storage hole communicates with the groove 91. A valve body 93 pressed by a compression coil spring 92 is inserted into the valve housing hole. The valve element 93 has a through orifice at the center, and the space of the groove 91 (output port 84) communicates with the space in which the valve element 93 and the compression coil spring 92 are accommodated by the orifice. Therefore, the spool 90 receives, at its left end, the pressure of the output port 84 (pressure adjusted to the suspension 100fr), and thereby receives a force to be driven to the right. Incidentally, when the pressure of the output port 84 is increased by impact, the valve body 93 moves to the left against the pressing force of the compression coil spring 92 and creates a buffer space at the right end of the valve body 93. However, when the output port 84 is shockingly raised, the shocking rise is not immediately applied to the left end surface of the spool 90, and the valve body 93 is
The spool 90 responds to the sudden pressure increase at the output port 84.
Has the effect of buffering the rightward movement of Conversely, it has an effect of buffering the leftward movement of the spool 90 against a shocking pressure drop at the output port 84.

The right end face of the spool 90 receives the pressure of the target pressure space 88 communicating with the high-pressure port 87 via the orifice 88f, and the pressure causes the spool 90 to receive a driving force to the left. The high pressure port 87 is supplied with a line pressure. The target pressure space 88 communicates with the low pressure port 89 through a flow path 94, and a flow opening of the flow path 94 is defined by a needle valve 95.
When the needle valve 95 closes the flow path 94, the orifice 88
The pressure in the target pressure space 88 communicating with the high pressure port 87 via f becomes the pressure (line pressure) of the high pressure port 87, and the spool
90 is driven to the left, whereby the groove 91 of the spool 90 communicates with the groove 83 (line pressure port 82), and the groove 91 (output port
The pressure of 84) increases, and this is transmitted to the left of the valve body 93, and gives a right 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 becomes
Since the pressure is reduced by the orifice 88f, the pressure (line pressure) of the high-pressure port 87 drops significantly, and the spool 90 moves to the right, thereby communicating with the groove 86 (low-pressure port 85) of the groove 91 of the spool 90, The pressure in the groove 91 (output port 84) decreases, which is transmitted to the left of the valve body 93, and the right driving force at the left end of the spool 90 decreases. In this way, the spool 90
This is a position where the pressure in the target pressure space 80 and the pressure in the output port 84 are balanced. That is, a pressure that is substantially proportional to the pressure in the target pressure space 88 appears at the output port 84.

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

The needle valve 95 passes through a fixed core 96 made of a magnetic material.
The right end of the fixed core 96 has a truncated conical shape, and a bottomed conical hole-shaped end surface of the magnetic substance plunger 97 faces the right end surface. The needle valve 95 is fixed to the plunger 97. The fixed core 96 and the plunger 97 enter the inside of the bobbin around which the electric coil 99 is wound.

When the electric coil 99 is energized, magnetic flux flows in a loop of the fixed core 96, the magnetic yoke 98a, the magnetic end plate 98b, the plunger 97, and the fixed core 96, and the plunger 97 is attracted to the fixed core 96 and moves to the left. Then, 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 right driving force,
Since the right end of the valve 95 is at the atmospheric pressure through the low-pressure port 98c which is open to the atmosphere, the needle valve 95 is driven by the right pressure corresponding to the pressure value (which corresponds to the position of the needle valve 95) by the pressure of the target pressure space 88. The needle valve 95 eventually receives the force
Is a distance substantially inversely proportional to the value of the current flowing through the electric coil 99. As described above, one of the fixed core and the plunger has a truncated conical shape, and the other has a conical bottomed conical hole shape to make the relationship between the current value and the distance linear as described above.

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

FIG. 4 shows an enlarged longitudinal section of the cut valve 70fr. A line pressure port 72, a pressure adjustment input port 73, an oil discharge port 74, and an output port 75 communicate with a valve storage hole formed in the valve base 71. The line pressure port 72 and the pressure control input port 73 are separated by a ring-shaped first guide 76, and the pressure control input port 73 and the output port 75 are separated by a cylindrical guide 77a,
It is separated by 77b and 77c. Oil drain port 74 is
The second guides 77a, 7d communicate with the outer peripheral groove of the guide 77c.
The oil leaking to the outer circumference of 7b and 77c is returned to the return line 11.

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

FIG. 5 shows an enlarged longitudinal section of the relief valve 60fr.
An input port 62 and a low pressure port 63 are open in a valve housing hole of the valve base 61. A cylindrical first guide 64 and a second guide 67 are inserted into the valve housing hole, and the input port 62 communicates with the inner space of the first guide 64 through the filter 65. A valve body 66 having an orifice at the center is inserted into the first guide 64, and the valve body 66 is pressed to the left by a compression coil spring 66a. The space in which the valve body 66 and the compression coil spring 66a are accommodated in the first guide 64 passes through the orifice of the valve body 66 and the input port
62, and through the opening of the spring seat 66b,
It communicates with the inner space of the second guide 67. Conical valve body 68
Is pushed to the left by the repulsive force of the compression coil spring 69,
The opening of the spring seat 66b is closed. When the pressure (control pressure) of the input port 62 is lower than the predetermined high pressure, the pressure in the coil spring 66a storage space that communicates with the input port 62 through the orifice of the valve body 66 is relatively higher than the repulsive force of the compression coil spring 69. 5, the valve element 68 closes the center opening of the valve seat 66b, as shown in FIG. 5, so that the output port 62 communicates with the low pressure port 63 through the hole 67a in the second guide 67. It is isolated from the space. That is, the output port 62 is shut off from the low-pressure port 63.

When the pressure (control pressure) of the input port 62 rises to a predetermined high pressure, this pressure is applied to the center opening of the valve seat 66b through the orifice of the valve element 66, and the valve element 68 starts to be driven rightward by this pressure, and When the pressure further increases, the valve element 68 is driven to the rightmost. That is, the pressure of the input port 62 is
The control pressure is released to the low-pressure port 63, and is suppressed to a predetermined high pressure or less.

When a high pressure is applied to the input port 62 in an impact, the valve
66 is driven to the right and the input port 62 is the side port of the first guide 64
The low pressure port 63 communicates with the valve housing space of the base body 61 through 64a, and since this flow passage area is large, a sudden pressure rise (pressure shock) at the output port 62 is buffered.

FIG. 6 shows an enlarged vertical cross section of the main check valve 50. An input port 52 and an output port 53 communicate with a valve storage hole formed in the valve base 51. A cylindrical valve seat 54 with a bottom is accommodated in the valve accommodating hole, and a ball valve 57 pressed through a communication port 55 of the valve seat 54 by a compression coil spring 56.
Is closed, but when the pressure of the input port 52 is higher than the pressure of the output port 53, the ball valve 57 is pushed rightward by the pressure of the input port 52 to open the communication port 55. That is, the input port
Oil flows from 52 to 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 no oil flows from the output port 53 toward the input port 52.

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

The solenoid device composed of the needle valve 125 to the electric coil 129 has the same structure and the same dimensions as the solenoid device composed of the needle valve 95 to the electric coil 99 shown in FIG. 3 (design common to the pressure control valve and the bypass valve). And the orifice
The distance between the needle valve 125 and 122b is substantially inversely proportional to the value of the current flowing through the electric coil 129. Since the flow opening of the orifice 122b is inversely proportional to this distance, the oil flow from the input port 121 through the orifice of the valve element 124a, through the inner space of the first guide 123, through the orifice 122b, and into the low pressure port 122 is reduced. Is proportional to the differential pressure across the orifice on the left end face of the valve element 124a.

As a result, the pressure of the input port 121 is
Is a pressure that is substantially proportional to the current value. The bypass valve 120 controls the pressure (line pressure) of the input port 121,
The energizing current is within a predetermined range and is set to a pressure proportional thereto.
Further, when the ignition switch is off (the engine is stopped: the pump 1 is stopped), the energization of the electric coil 129 is stopped, so that the needle valve 125 moves to the rightmost position.
The input port 121 (line pressure) has a low pressure near the return pressure.

When the pressure of the input port 121 rises suddenly,
This pressure is received on the left end surface, and the valve element 124a is driven rightward, so that the low pressure port 122a communicating with the low pressure port 122 communicates with the input port 121. Since the low-pressure port 122a has a relatively large opening, the shocking rising pressure of the input port 21 immediately escapes to the low-pressure port 122a.

The relief valve 60m has the same structure as that of the above-described relief valve 60fr, but has a conical valve body (68: 5th
The compression coil spring (69) that presses the spring has a slightly smaller spring force. The pressure at the input port (62) (the pressure at the high-pressure port 3) and the relief valve 60fr reduce the pressure at the input port 62. When the pressure is lower than a predetermined high pressure which is a pressure slightly lower than the pressure discharged to the low pressure port 63, the output port (62) is shut off from the low pressure port (63).
When the pressure of the input port (62) becomes equal to or higher than a predetermined high pressure, the valve element (68) is driven to the rightmost. That is, the pressure of the input port (62) is released to the low pressure port (63), and the pressure of the high pressure port 3 is suppressed to a predetermined high pressure or less.

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

The relief valve 60m suppresses the pressure of the high-pressure port 3, that is, the pressure of the high-pressure supply pipe 8, to a predetermined high pressure or less.
And the transmission of the shocking pressure to the high-pressure supply pipe 8 is buffered.

The bypass valve 120 controls the pressure of the rear wheel high-pressure supply pipe 9 substantially linearly within a predetermined range, and maintains the pressure of the rear wheel high-pressure supply pipe 9 at a predetermined constant pressure in a steady state. This constant pressure control is performed by controlling the energizing current value of the bypass valve 120 with reference to the detection pressure of the pressure sensor 13rm. Also,
When there is a shock pressure increase in the rear wheel suspension, it is released to the return pipe 11 to buffer the propagation to the high pressure supply pipe 8. Further, when the ignition switch is open (the engine is stopped: the pump 1 is stopped), the power is cut off, and the rear wheel high-pressure supply pipe 9 is made to flow through the return pipe 11, and the rear wheel high-pressure supply pipe 9 (the high-pressure supply pipe 8) is turned off. ) Relieve pressure.

Pressure control valves _{80fr, 80f L, 80rr, 80r} L is the suspension pressure control, to provide the required support pressure to the suspension, the energization current value of the electrical coil (99) is controlled,
The required supporting pressure is output to the output port (84). When the impact pressure from the suspension propagates to the output port (84), it is buffered and the pressure control spool (9
1) Suppression (turbulence in output pressure) is suppressed. That is, the required pressure is stably applied to the suspension.

The cut valves 70fr, 70f _L , 70rr, 70r _L are connected to the suspension pressure line (the output port 84 of the pressure control valve and the suspension) when the line pressure (the front wheel high pressure supply pipe 6, the rear wheel high pressure supply pipe 9) is lower than a predetermined low pressure. To prevent the pressure from being released from the suspension, and when the line pressure is equal to or higher than a predetermined low pressure, the supply pressure line is set to a fully open flow. This allows
Abnormal drop in suspension pressure when line pressure is low is automatically prevented.

The relief valves 60fr, 60r _L , 60rr, and 60r _L limit the pressure (mainly the suspension pressure) of the suspension pressure line (between the output port 84 of the pressure control valve and the suspension) to a value less than the high pressure upper limit value, and the If there is a shock pressure increase in the pressure supply line (suspension) due to lifting, throwing in when loading heavy objects, etc., this pressure is released to the return pipe 11 to relieve the impact of the suspension and the hydraulic line connected to the suspension And the durability of the mechanical elements connected to it.

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

First, sensors will be described. FL, FR, RL, and RR vehicle height sensor 15f _L disposed in the vicinity of the shock absorber at each position, 15fr, 15r _L and 15rr, respectively the distance between the wheel and the vehicle body at each position, i.e. in the position Outputs a signal according to the vehicle height. Each vehicle height sensor detects vehicle height information in the form of a digital signal, and this information is converted into an analog voltage signal and output.

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

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

RY, SW1, SW3, SW4, SW5 and SW6 are a main relay, an ignition switch, a stop lamp switch, a door switch, a reservoir level warning switch, and a vehicle height adjustment switch, respectively. SOL1, SOL2, SO
L3 and SOL4 are, FL respectively, FR, RL and RR linear control valve (80f _L that provided in the hydraulic control unit, 80fr, 80r _L and
80rr) solenoid, SOL5 is bypass valve 120
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, an I / O extension unit 130, a reset control unit 140, an A / D conversion unit 150, an active filter unit 160, a duty A control unit 170, a current detection unit 180, drivers 190 and 200, a power supply 210, a backup power supply 220, a driver 230, and an input buffer 240 are provided.

The signals applied to the input terminals IG, SPD, SS1 and SS2 of this control unit ECU
It is applied to input ports PA0, ASR0, ASR1 and ASR2 of PU17. ASR0 to ASR2 are interrupt request ports. Also, information on signals applied to the input terminals ICL, L1, L2, L3, STP, DOOR, LOIL, and HIGH is transmitted to the CP via the I / O extension unit 130.
It is applied to the input ports PA4 to PA7 of U17.

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

The value of the current flowing through the solenoids SOL1 to SOL5 of each solenoid valve is
Adjusted by pulse duty control (PWM). A pulse for turning on / off the energization of each solenoid is generated by the duty control unit 170. When the CPU 18 writes a predetermined instruction code and data for determining a duty value to the duty control unit 170, the duty control unit 170 outputs a pulse having a duty corresponding to the data to each output terminal. Driver 200
Is the pulse signal output from the duty control unit.
Controls ON / OFF of energization of each solenoid according to H / L.

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

The data transmitted between the CPUs 17 and 18 is a signal line group 306.
, In the form of 8-bit parallel data. Also,
In order to match the transmission / reception timing of this data, two
The CPUs 17 and 18 are further connected to each other by two control lines 307 and 308. The control line 307 is connected to the output port PA3 of the CPU 17 on the main side and the input port IR of the interrupt request port of the CPU 18 on the sub side.
The other control line 308 connects between the output port PA4 of the CPU 18 on the sub side and the interrupt request input port IRP of the CPU 17 on the main side.

The CPUs 17 and 18 store programs for controlling the pressure of each suspension. In accordance with this program, the CPU 18 mainly includes the vehicle height sensors 15f _L , 15fr, 15r _L , 15rr provided in the suspension system shown in FIG.
And the pressure sensor _{13f L, 13fr, 13r L,} 13rr, 13rm, 13rt, and the reading of the longitudinal acceleration sensor 16p and lateral acceleration sensor 16r, the detection value of the vehicle, the pressure control valve 80f _L, 80FR, 80
r _L , 80 rr and the value of the current supplied to the electric coils (99, 129) of the bypass valve 120 are controlled.

The CPU 17 sets / releases the line pressure of the suspension system (FIG. 1), determines the vehicle driving state, and determines the determination result from when the ignition switch SW1 is closed to when it is opened and immediately after the ignition switch SW1 is opened. Calculate the required pressure (pressure to be set for each suspension) required to establish the appropriate vehicle height and body posture, and receive various detected values from the CPU 18 to determine the vehicle operation state.
The current value required to set the required pressure is given to the CPU 18.

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

In the flowchart of the drawings and the following description, the register symbol itself may mean the contents of the register.

First, refer to FIG. 9A. On-board battery to itself 19
(Step 1), the CPU 17 sets the internal registers, counters, timers, and the like to the contents of the predetermined initial standby state, and outputs the initial standby state (the components of the mechanism) to the output port. Output the signal level to be "electrically non-energized" (Step 2: Hereinafter, in parentheses, words such as "step" and "subroutine" are omitted, and only symbols attached to them are described).

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

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

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

A rotary encoder SN1 for detecting the rotation direction of the steering shaft is generated. The interrupt process (input port ASR0) in response to the first set of generated pulses will be described. The interrupt process (ASR0) proceeds at the rise and fall of the first set of generated pulses, and the interrupt process (AS
R0), write H to the rotation direction discriminating flag register, and respond to the fall by interrupt processing (ASR
0), the flag register is cleared (L
), And returns to the step immediately before proceeding to the interrupt processing.

When the rising of the second set of pulses appears after the rising of the first set of pulses (flag register = H) of the rotary encoder SN1, the steering shaft is driven to the left, and the rising of the first set of pulses is performed. When the rising of the second set of pulses appears after the falling (flag register = L), the steering shaft is being driven to the right.

The interrupt processing (input port ASR1) of the rotary encoder SN1 for detecting the rotation speed (steering angular velocity) of the steering shaft in response to the second set of generated pulses will be described. When it arrives, in response to this, it proceeds to the interrupt processing (ASR1), reads the contents of the steering clock register at that time, restarts the steering clock register, and returns the read contents (the period of the steering angular velocity synchronization pulse) to the aforementioned If the contents of the rotation direction discriminating flag register are H, a sign of + (left rotation) is given, and if the contents of the flag register are L, a sign of-(right rotation) is given. (Including directions + and-)
The value Ss obtained by taking the average of the load calculated several times and the average of the loads held so far is written in the steering angular speed register SS, and the process returns to the step immediately before proceeding to the interrupt processing (return).
By executing this interrupt processing (ASR1), data Ss (+ indicates left rotation,-indicates right rotation) indicating the steering angular speed (time series smoothed value of the speed calculation value) at that time is always stored in the steering angular speed register SS. Is held.

When permitting the above-described interrupt processing, the CPU 17 checks whether or not the CPU 18 has given a ready signal (6).

By the way, the CPU 18 initializes itself when the power is turned on, sets internal registers, counters, timers, and the like to the contents of the initial standby state, and outputs the initial standby state (each mechanism element) to the output port. Is output (data for designating all electric coils to be off) to the duty controller 170. Then, the duty controller 170 is supplied with the maximum current value data that causes the bypass valve 120 to be fully closed, and instructs the duty controller 170 to energize the bypass valve 120. With the above settings, the pressure control valves 80f _L , 80fr, 80
r _L , 80rr has a zero conducting current value and outputs the pressure of the return pipe 11 to its output port (84).
Are fully closed, and the pump 1 is rotationally driven while the engine is rotating, so that the high-pressure supply pipe 8, the front-wheel high-pressure supply pipe 6 (accumulator 7), and the rear-wheel high-pressure supply pipe 9 (accumulator)
10) The pressure starts to rise.

Thereafter, the CPU 18 sets the vehicle height sensors 15f _L and 15f _{L in} the first set cycle.
fr, 15r _L , 15rr, pressure sensor 13f _L , 13fr, 13r _L , 13rr, 13rm, 13
rt, the detection values of the acceleration sensors 16p and 16r, and the current detection values of each of the solenoids SOL1 to SOL5 are read and updated and written to an internal register, and when the CPU 17 requests the transfer of the detection data, CPU17 data of internal register
Transfer to

Further, CPU 17 is a pressure control valve 80f _L, 80FR, 80 r _L, when coming send electric current target value data for each 80rr and the bypass valve 120, each solenoid SOL1~SO of these target values
Based on the corresponding current detection value of L5, each control duty value is generated, and these are
Give to 0.

By the way, when the CPU 18 gives the busy signal in the check in the steps 6 and 7 described above, the CPU 17 waits there and executes a waiting process (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. When the pressure is set (bypass valve 120 is de-energized and fully opened and pressure control valve is de-energized), and an abnormality is determined, a notification and pressure setting corresponding to the abnormality (by-pass valve 120 de-energized, pressure control valve de-energized) ) (10).
If no abnormality is determined, the abnormality processing is canceled (the abnormality notification is cleared) (11).

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

Then, the CPU 17 instructs the CPU 18 to transfer the detected pressure data Dph of the pressure sensor 13rm, receives the received data Dph, and
(14), detection pressure (rear wheel side pressure of high pressure supply pipe 8) Dp
h is a predetermined value Dph is checked whether now (cut valve 70f _L, 70fr, 70r _L, lower pressure value than the predetermined low pressure 70rr starts to open) or more (or the line pressure is somewhat standing up) (1
Five). If the line pressure has not risen, the process returns to step 6.

When the line pressure rises, CPU17 sends a pressure sensor to CPU18.
13f _L , 13fr, 13r _L , 13rr Detection pressure (initial pressure) data Pf _L0 , P
Instructs the transfer of fr ₀ , Pr _L0 , and Prr ₀ , receives them, and writes them in registers PFL ₀ , PFR ₀ , PRL ₀ , and PRR ₀ (16).

Then, the energization current value data required to obtain the required pressure in one area (table 1) of the internal ROM is stored in registers PFL ₀ ,
Contents of PFR ₀ , PRL ₀ , PRR ₀ The current flowing through the solenoid required to access with Pf _L0 , Pfr ₀ , Pr _L0 , Prr ₀ and output pressure Pf _L0 to output port 84 of pressure control valve 80f _L Ihf _L , pressure
Energizing current Ihfr required to output a pfr ₀ to an output port of the pressure control valve 80FR, the pressure Pr energizing current value necessary for outputting _L0 to an output port of the pressure control valve 80 r _L Ihr _L, and pressure Prr ₀
Is read from the table 1 and written into the output registers IHf _L , IHfr, IHr _L and IHrr (17), and the data of these output registers is written to the CPU 18. Transfer to The CPU 18 uses these data as a current target value, generates a duty value that makes them equal based on the target current value and the detected current value of the solenoid, and supplies the duty value to the duty controller 170.

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

Depending on the current setting (target value) at this time, the pressure control valve 80
f _L , 80fr, 80r _L , 80rr output the pressures of Pf _L0 , Pfr ₀ , Pr _L0 , Prr ₀ substantially to the output port (84) when the line pressure is equal to or higher than the predetermined low pressure, respectively. the cut valve 70f _L in response to the rise to higher than a predetermined low pressure, 70FR, 70r _L, when 70rr is opened, the pressure (initial _{pressure) Pf L0, Pfr 0, Pr} L0, Prr 0 of each suspension at that time Substantially equal pressure
Pressure control valve 80f _L , through cut valve 70f _L , 70fr, 70r _L , 70rr
80fr, 80r _L , 80rr to suspension 100f _L , 100fr, 100r _L ,
Supplied to 100rr.

Therefore, the ignition switch SW1 is changed from open (engine stop: pump 1 stop) to closed (pump 1 drive),
First time cut valve _{70f L, 70fr, 70r L,} 70rr are open (line pressure is equal to or higher than a predetermined low pressure), when the hydraulic lines of the suspension communicate with the output port of the pressure control valve, the output pressure and the suspension pressure in the pressure control valve Are substantially equal and do not cause a sudden pressure fluctuation of the suspension. That is, there is no impact change of the vehicle body posture.

The above is the description of the pressure control valve 80 when the ignition switch SW1 is switched from open to closed (immediately after the engine starts).
f _L, 80fr, a 80 r _L, initial output pressure settings 80Rr.

 Next, the CPU 17 starts a timer ST for the ST time period.

ST is the content of the register ST.
Data ST indicating a second set cycle longer than the first set cycle for reading the detected value is written.

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

Then, an abnormality / normal judgment is made with reference to these read values.

If normal, the CPU 17 executes line pressure control (LPC) next. In this case, the reference pressure (relief valve 60
Absolute value and polarity (high / low) of deviation of detection line pressure Prm with respect to m relief pressure (fixed value slightly lower than specified high pressure)
The current value of the current flowing through the bypass valve 120 is calculated by adding a correction value that makes the deviation zero in accordance with the deviation, and the current value of the current supplied to the bypass valve 120 is calculated. Write to output register. The contents of the output register are transferred to the CPU 18 in step 36 described later.

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

Next, refer to FIG. 9b. After completing the line pressure control (LPC), the CPU 17 checks whether the switch 20 is open or closed (2
2) If it is open, stop processing (23) is performed, the relay 22 is turned off, and interrupts ASR0 to ASR2 are prohibited. In the stop processing (23), first, the bypass valve
120 is de-energized and fully opened (the line pressure is released to the return pipe 11).

When the switch SW1 is opened (the engine stops: the pump 1 stops) and the high-pressure discharge of the pump 1 stops, and the bypass valve 120 is fully opened, the high-pressure supply pipe 8, the front-wheel high-pressure supply pipe 6
The pressure of the accumulator 7 and the rear wheel high-pressure supply pipe 9 (accumulator 10) becomes the pressure of the return pipe 11, and the pressure of the return pipe 11 is released to the reservoir 2, whereby the high-pressure supply pipe 8 and the like become the atmospheric pressure. The high pressure supply pipe 8 etc.
At the timing when f _L , 70fr, 70r _L , and 70rr reach a pressure equal to or lower than the predetermined low pressure at which complete shutoff is performed, the CPU 17 sets the pressure control valve 80f _L ,
80fr, 80r _L , 80rr are de-energized.

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 [Subroutine 20
, The throttle opening Tp read this time, which was read in the previous day, −the throttle opening read last time) = Ts (throttle opening / closing speed), and write it to the register TS.

Next, the CPU 17 executes “vehicle height deviation calculation” (31),
The amount of suspension pressure correction required to calculate the deviation of the vehicle body height from the target vehicle height and make it zero (first correction amount:
Is calculated for each suspension). For more information on this content,
This will be described later with reference to FIG. 10a.

The CPU 17 executes a “pitching / rolling prediction calculation” (32) after the “vehicle height deviation calculation” (31), and executes a suspension pressure correction amount (the second one) corresponding to the vertical and lateral accelerations actually applied to the vehicle body. 2 Correction amount: For each suspension), and calculate the [suspension initial pressure (Pf _L0 , Pfr ₀ , Pr _L0 , Pr
r ₀ ) + first correction amount + second correction amount] (calculated intermediate value: for each suspension). For details on this content, see Section 10b
It will be described later with reference to the drawings.

Next, the CPU 17 executes “pressure correction” (33), and performs the “calculated intermediate value” in accordance with the line pressure (high pressure) detected by the pressure sensor 13rm and the return pressure (low pressure) detected by the pressure sensor 13rt. Is corrected. For details on this content, see Chapter 10c
It will be described later with reference to the drawings.

CPU17 then is a "pressure / current conversion" (34), and the correction "calculation intermediate value" (the respective per suspension), the pressure control valve _{(80f L, 80fr, 80r L} , 80rr) current to flow in the Convert to This content will be described later with reference to FIG. 10d.

Next, the CPU 17 executes the “warp correction” (35) to calculate the lateral acceleration Rg.
Then, a turning-time warp correction value (current correction value) corresponding to the steering speed Ss is calculated, and a current value to be supplied to the pressure control valve is added thereto. For details on this content, see Section 10e
It will be described later with reference to the drawings.

Next, the CPU 17 transfers the current value to be passed through the pressure control valve, calculated as described above, to the CPU 18 in the “output” (36) to each pressure control valve. The current value to be passed through the bypass valve 120 calculated in (LPC) is transferred to the CPU 18 to the bypass valve 120.

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

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

The contents of the "vehicle height deviation calculation" (31) will be described with reference to FIG. 10a. First, in summary, the vehicle height sensors 15f _L , 15fr, 15
r _L , 15rr vehicle height detection values Df _L , Dfr, Dr _L , Drr (registers DFL, DF
R, DRL, DRR contents), heave (height) DHT, pitch (difference between front wheel side height and rear wheel side height) DPT, roll (right wheel side height and left wheel side height) DRT and warp (difference between the sum of the front right wheel vehicle height and the rear left wheel vehicle height and the sum of the front left wheel vehicle height and the rear right wheel vehicle height) DWT are calculated. That is, each wheel height (the contents of the registers DFL, DFR, DRL, DRR) is
Attitude parameters for the entire vehicle (Heave DHT, Pitch DP
T, 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). This DPT is calculated in “Calculation of pitching error CP” (51), and DRT is calculated in “Rolling error C”.
R calculation ”(52), and DWT calculation is“ warp error
Calculation of CW ”(53).

Then, in "Calculation of Heave Error CH" (50), the vehicle speed Vs
Deriving the target heave Ht from the calculated heave DHT,
Calculate the heave error amount for the target heave Ht and calculate the PID
For the (proportional, integral, differential) control, the calculated heave error amount is subjected to PID processing to calculate a heave correction amount CH corresponding to the heave error.

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

Similarly, in “Calculation of rolling error CR” (52), the target roll Rt is derived from the lateral acceleration Rg, and the calculated roll is calculated.
Calculate roll error amount for target roll Rt of DRT and PID
For the (proportional, integral, derivative) 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 the “calculation of warp error CW” (53), the target warp Wt is set to zero, and the target warp W
Calculate the amount of warp error for t, and calculate PID (proportional, integral,
For the derivative) control, the calculated warp error amount is subjected to PID processing to calculate a warp correction amount CW corresponding to the warp error. When the absolute value of the calculated warp error amount (DWT since the target warp is zero) is equal to or less than a predetermined value (within an allowable range), the warp error amount for PID processing is set to zero, and when the absolute value exceeds the predetermined value. The amount of warp error for PID processing is -DWT.

To explain in detail the content of “calculation of heave error CH” (50), the CPU 17 firstly sets the target heave Ht corresponding to the vehicle speed Vs.
Is read from one area (table 2H) of the internal ROM and written into the heave target value register HT (39).

As shown as “Table 2H” in FIG. 10a, the vehicle speed V
The target heave Ht associated with s is such that the vehicle speed Vs is VsaKm
In / h or less high value Ht ₁ at low speed, but the vehicle speed Vs is low Ht ₂ is at a high speed of no less than Vsb, in the range of less than Vsb exceed Vs is Vsa, the target value is linear with respect to the vehicle speed Vs (It may be a curve). The reason for linearly changing the target value in this way is that, for example, if the target value is 100 km / h or less, the target value is changed to Ht.
_{If the} target value is changed to Ht ₂ stepwise at ₁ or more than 100 km / h, when Vs is near 100 km / h, the target heave changes greatly stepwise due to slight speed change of Vs. This is to prevent the height of the vehicle from increasing and decreasing frequently at a high speed and causing the vehicle height stability to deteriorate. The above table
According to the setting of 2H, a slight change in the vehicle speed Vs only slightly changes the target value, so that the change in the vehicle height target value is small and the vehicle height stability is improved.

In the next step 39B, a check is performed to determine whether or not the vehicle height sensor is abnormal, and a process for when an abnormality occurs is executed. Details of this process are shown in FIG. 10f. That is, in this process, first checks the level of the vehicle height signals DFL to the output of the vehicle height sensor 13f _L of the front left (FL) position, check for the abnormality. In this embodiment, at normal times, each of the vehicle height sensors outputs a voltage equal to or higher than VolV and lower than VohV. Therefore, for example, when an abnormality such as a short circuit or open circuit occurs inside the vehicle height sensor, the output voltage of the sensor becomes lower than Vol or higher than Voh. Then, the voltage is checked, and if it is less than Vol or more than Voh, it is regarded as a vehicle height sensor abnormality.

If the vehicle height sensor 13f _L is normal, it of the detected vehicle height DFL, but it is stored as a detected vehicle height to register TFL, if the abnormality of the vehicle height sensor 13f _L is detected, detection wheel Assuming that the height is equal to the target vehicle height, the value of Ht / 4 is substituted into the register TFL instead of the detected vehicle height.

Generally, when an abnormality occurs in the vehicle height sensor, an abnormal vehicle height value is detected. Therefore, if control is continued, abnormal suspension control such as control in a direction opposite to the original control will be performed. However, if control after abnormality detection is completely prohibited in order to avoid abnormal suspension control, for example, the pressure is maintained while maintaining a pressure difference between the right and left or the front and rear shock absorbers, It may happen that the vehicle is held in an inclined state.

However, as in this embodiment, when the detected vehicle height of the vehicle height sensor in which the abnormality has occurred is treated as being equal to the target value, the suspension control is continued as it is, and the posture control is almost the same as in the normal state. And vehicle height control is performed. There is no risk that the control in the reverse direction will be performed. Of course, if all four vehicle height sensors fail at the same time, the posture cannot be corrected or the vehicle height adjusted, but if at least the remaining two vehicle height sensors are functioning normally, the inclination of the posture is detected. This can be corrected to keep the vehicle level and adjust the vehicle height.

In the process of FIG. 10f, similarly, the other vehicle height sensors 13fr, 13r _L
For 13rr and 13rr, the presence or absence of abnormality is identified, and if normal, the actual detected vehicle height is stored, and if abnormal, the target value (Ht / 4) is stored in registers TFR, TRL, and TRR, respectively.

Returning to FIG. 10a, the description will be continued. In step 40, the heave amount is stored in the register DHT. The amount of heave is calculated from the contents of the four registers TFL, TFR, TRL, and TRR as TFL + TFR + TRL.
Calculated by + TRR.

Next, the contents of the register EHT2 in which the previously calculated heave error amount is written are written into the register EHT1 (41), and the current heave error amount HT−DHT is calculated.
Write to HT2 (42). As described above, the register EHT1 stores the previous heave error amount (before ST), and the register EHT2 stores the current heave error amount. Next, the CPU 17 writes the contents of the register ITH2 in which the previous error integrated value has been written into the register ITH1 (43), and calculates the current PID correction amount ITh by the following equation.

_{ITh = Kh 1 · EHT2 + Kh} 2 · (EHT2 + Kh 2 · ITH1) + Kh 4 · Kh 5
_{· (EHT2-EHT1) Kh 1} · EHT2 is P (proportional) term of the PID operation, Kh ₁ coefficients of the proportional term, EHT2 is the content of register EHT2 (Hibuera amount of time).

Kh ₂ · (EHT2 + Kh ₃ · ITH1) is an I (integral) term,
Kh ₂ is the coefficient of the integral term, ITH1 is the integrated value of the correction amount up to the previous time (the integrated value of the correction amount output from the initial pressure settings 16 to 18),
Kh ₃ is a weighting factor between the current error amount EHT2 and the correction quantity integration value ITH1.

Kh ₄ · Kh ₅ · (EHT2−EHT1) is a D (differential) term,
Coefficient differential term, is a Kh ₄ · Kh _5, Kh ₄ uses the mapped value for the vehicle speed Vs, Kh ₅ uses the value associated with the steering angular velocity Ss. That is, from a region of internal ROM (table 3H), reads the vehicle speed correction coefficient Kh ₄ associated with the vehicle speed Vs at that time, and, from a region of the internal ROM (table 4H), the steering angular velocity Vs at that time It reads the steering angular velocity correction coefficient Kh ₅ which is associated, these products Kh ₄ · Kh ₅ a coefficient of differential term.

As shown as “Table 3H” in FIG. 10a, the vehicle speed correction coefficient Kh ₄ is generally a larger value as the vehicle speed Vs is higher, and the weight of the differential term is increased. This is a correction term in which the derivative term tries to keep it at the target value faster with respect to the change of the heave, and the higher the vehicle speed, the faster the speed of the vehicle height change with respect to the disturbance. I have. On the other hand, vehicle height Vs
When a certain level is exceeded (VsdKm / h or more in table 3H), sudden changes in vehicle body posture occur when the brake is depressed / released, acceleration / deceleration by the accelerator pedal, turning / turning back by turning the steering wheel, etc. In addition, an excessively large differential term that rapidly compensates for such a sudden change in attitude will degrade the stability of the vehicle height control. Accordingly, the vehicle speed correction coefficient Kh ₄ of the table 3H changes more precisely when the vehicle speed Vs is low, and changes smaller when the vehicle speed Vs is higher, with respect to the change in the vehicle speed Vs. That is, when the vehicle speed Vs is low, the weight of the differential term greatly changes with respect to the change of the vehicle speed, but when the vehicle speed Vs is high, the weight change of the differential term is small with respect to the change of the vehicle speed.

As shown as "table 4H" in Figure 10a, the steering angular velocity correction coefficient Kh ₅ is generally at a larger value the higher steering angular velocity Ss, to increase the weight of the derivative term. This is a correction term in which the differential term is fast with respect to the change of the heave and tries to fall within the target value.The higher the steering angular velocity Ss, the faster the speed of the vehicle height change with respect to the disturbance, so that according to the steering angular velocity, Is increasing. On the other hand, when the steering angular speed Ss is a certain level or less (Ssa ° / msec or less in Table 4H), the change in the traveling direction is extremely gentle, and the weighting of the differential term is small. A change in vehicle height appears at the specified speed. At a steering angular velocity of Ssb or higher, the change in the vehicle body posture is rapid and extremely large, and an excessive differential term that quickly compensates for such a sudden posture change is dangerous because the stability of the vehicle height control is lost. Accordingly, the coefficient Kh ₅ of the differential term corresponding to the steering angular velocity Ss is, Ss is a constant value in the following Ssa, the higher value proportional substantially to Ss in the following Ssb beyond Ssa, value at Ssb exceeds Ssb Is a constant value.

With the introduction of the differential term Kh ₄ · Kh ₅ · (EHT2−EHT1) described above, the coefficient Kh ₄ is further increased corresponding to the vehicle speed Vs, and the coefficient Kh ₅ is increased corresponding to the steering angular velocity Ss. By doing so, differential control of weighting corresponding to the vehicle speed Vs and the steering angular speed Ss is realized, and vehicle height control with high stability is realized with respect to fluctuations in the vehicle speed Vs and the steering angular speed Vs.

As described above, the heave error correction amount ITh is calculated by the PID calculation (4
When calculated in 4), the CPU 17 writes the calculated heave error correction amount ITh into the register ITH2 (45), and furthermore, the weight coefficient Kh ₆ of the heave error correction amount (pitch error correction amount, roll error correction amount, and warp error correction described later). Weighted to the amount: contribution ratio in the total correction amount), and written in the heave error register CH.

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

In calculating the pitch error, the vehicle height sensors 13f _L and 13f
When r, 13r _L and 13rr are abnormal, TFL, TFR, TRL,
And TRR, Ht / 4, that is, the heave target value, is substituted for each detected vehicle height.

FIG. 11a shows the contents of table 2P. The pitch target value Pt corresponding to the vertical (longitudinal) acceleration Pg is the vertical acceleration Pg
In the direction (decrease) to cancel the pitch that appears. In the area a, the target pitch is increased as the longitudinal acceleration Pg increases (decreases) to aim at energy saving. In the area b, the sensor target is considered to be abnormal for abnormal Pg. This is to prevent the pitch target value from being given even though Pg has not actually occurred. Other arithmetic processing operations are the same as the contents of the above-described “calculation of heave error CH” (50), and replace HT and Ht in step 39 with PT and Pt, and
The calculation formula is replaced with the DPT calculation formula described above, and EHT1,
Replace EHT2 with EPT1 and EPT2, and replace EHT2, HT and DHT in step 42.
Replace EPT2, PT, DPT with ITH1, ITH2 in step 43, ITP1, I
Replaced with TP2, replaced the Ith calculation formula of subroutine 44 with the pitch error correction amount ITp that has a completely corresponding relationship with it, and replaced table 3H with a coefficient table (3P) for calculating the pitch correction amount ITp. , Table 4H also pitch correction amount ITp
Replace with the coefficient table for calculation (4P)
H2, ITh is replaced with ITP2, ITp, and CH, Kh ₆ , I
By replacing Th with CP, KP ₆ and ITp, the “pitch error
A flowchart showing the contents of "CP calculation" (51) appears. The CPU 17 executes the processing shown in this flowchart.

Next, the CPU 17 calculates “rolling error CR” (52)
To set the roll error correction amount CR and the heave error CH.
Calculated in the same manner as above and written in the roll error register CR. In this case, the roll target value RT corresponding to the heave target value HT is obtained from one area (table 2R) of the internal ROM of the CPU 17 by the data Rt (lateral acceleration) corresponding to the lateral acceleration Rg at that time.
(Roll target value according to Rg).

In calculating the roll error, the vehicle height sensors 13f _L and 13f
If r, 13r _L , 13rr is abnormal, TFL, TFR, TRL, TRR respectively
Ht / 4, that is, the heave target value, is substituted for each detected vehicle height.

FIG. 11b shows the contents of table 2R. The roll target value Rt corresponding to the lateral acceleration Rg is in a direction (decrease) to cancel the roll appearing by the lateral acceleration Rg. In the area a, the target roll is increased as the lateral acceleration Rg increases (decreases) to aim at energy saving, and in the area b, the sensor target is considered to be abnormal for abnormal Rg. In practice, this is to prevent the roll target value from being given even though Rg has not occurred. Other arithmetic processing operations are described in the above “Heave error CH calculation” (5
The contents are the same as the contents of 0), and the HT and Ht of step 39 are replaced with RT and R
Replace with t, replace the DHT calculation formula in step 40 with the above DRT calculation formula, replace EHT1, EHT2 in step 41 with ERT1, ERT2, and replace EHT2, HT, DHT in step 42 with ERT2, RT, DRT. Replace
In step 43, ITH1 and ITH2 are replaced with ITR1 and ITR2, and the ITh calculation formula of the subroutine 44 is replaced with a roll error correction amount ITr calculation formula that has a completely corresponding relationship with it, and the table 3H is used to calculate the roll correction amount ITr. Replace with coefficient table (3R),
Table 4H is also a coefficient table (4
Substituted with R), the ITH2, ITh in step 45 is replaced with ITR2, ITr, and CH of the step 46, by replacing the Kh _6, ITh CR, and Kr _6, ITr, "calculation of roll error CR" A flowchart showing the contents of (51) appears. The CPU 17 executes the processing shown in this flowchart.

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

Accordingly, when any of the vehicle height sensors 13f _L , 13fr, 13r _L and 13rr is detected, the register TFL,
Store Ht / 4, ie, heave, in TFR, TRL and TRR.

Other arithmetic processing operations are the same as the contents of the above-described “calculation of heave error CH” (50).
T, Ht is replaced with WT, 0, and the DHT calculation formula in
Replace the EHT1 and EHT2 in step 41 with EWT1 and EWT2
And replace the contents of step 42 with the absolute value of DWT equal to the predetermined value W.
m is within the allowable range, WT is set to 0, and when it exceeds Wm, WT is set to -DWT, and WT is changed to the contents to be written in the register EWT2, and ITH1 and ITH2 in step 43 are changed to IWT1 and ITW2.
And replace the ITh calculation formula of the subroutine 44 with the warp error correction amount ITw calculation formula that has a completely corresponding relationship with it, and replace the table 3H with a coefficient table (3W) for calculating the warp correction amount ITr, and 4H is also replaced by a coefficient table (4W) for calculating the warp correction amount ITw, and the ITH of step 45 is replaced.
2, replacing the ITh in ITW2, ITW, and CH of the step 46, Kh _6, IT
By replacing h with CW, Kw ₆ , ITw, the “warp error C
A flowchart showing the contents of "calculation of W" (53) appears. The CPU 17 executes the processing shown in this flowchart.

As described above, when the heave error correction amount CH, the pitch error correction amount CP, the roll error correction amount CR, and the warp error correction amount WP are calculated, the CPU 17 calculates these correction amounts as the suspension pressure correction amounts EHf _L (To suspension 100f _L ), EHfr (to 100fr), EHr _L (to 100r _L ), EHrr (to 100rr). That is, the suspension pressure correction amount is calculated as follows.

EHf _L = Kf _L · Kh ₇ · (1/4) · (CH-CP + CR + CW), EHfr = Kfr · Kh ₇ · (1/4) · (CH-CP-CR-CW), EHr _L = Kr _L · Kh ₇ · (1/4) · (CH + CP + CR−CW), EHrr = Krr · Kh ₇ · (1/4) · (CH + CP−CR + CW) Coefficients Kf _L , Kfr, Kr _L , and Krr are the line pressure reference points 13 rm And the suspension 100f _L for the return pressure reference point 13rt,
100fr, 100r _L, due to the different pipe lengths 100RR, a correction coefficient for compensating the suspension supply pressure deviation. Kh
Reference numeral ₇ denotes a coefficient for increasing or decreasing the vehicle height deviation correction amount in accordance with the steering angular speed Ss, which is read from one area (table 5) of the internal ROM of the CPU 17 in accordance with the steering angular speed Ss. . If the steering angular velocity Ss is large, a large change in attitude is expected, and an increase in the amount of attitude error is expected. Therefore, the coefficient Kh
₇ is roughly set to be large in proportion to the steering angular velocity Ss. However, the steering angular speed Ss is somewhat lower (Table 5
In Ssc ° / msec or less), the change in the traveling direction is extremely gradual, and the posture change is small and gradual. In the case of exceeding Ssc and Ssd or less, the posture change appears at a speed substantially proportional to the steering angular velocity Ss. At a steering angular velocity exceeding Ssd, a change in the vehicle body posture is rapid and extremely large, and an excessive correction amount for quickly compensating for such a sudden posture change degrades the vehicle height control stability. Accordingly, the correction coefficient Kh ₇ corresponding to the steering angular velocity Ss is, Ss is a constant value in the following Ssc, and a high value of substantially proportional to Ss in the following Ssd beyond Ssc, constant value when the Ssd exceeds Ssd Value.

By the way, in the calculation of the heave error, the calculation of the pitching error, the calculation of the rolling error, and the calculation of the warp error shown in FIG. 10a, the heave attitude control amount CH and the pitch attitude control amount with respect to the unit change of the vehicle height detected by the vehicle height sensor. It is necessary to set the control gain or the frequency characteristic so that the changes of the CP, the roll attitude control amount CR, and the warp attitude control amount CW are not all the same, and in this embodiment,
The control gain for warp is set to be smaller than that for heave, pitch and roll.

That is, if the heave attitude control amount CH, the pitch attitude control amount CP, the roll attitude control amount CR, and the warp attitude control amount CW with respect to the unit change of the vehicle height detected by the vehicle height sensor, the degree of influence on the final output of each attitude. When the (control contribution ratios) are the same, when the attitude control amounts of heave, pitch, roll, and warp are converted into control amounts of the respective absorbers in step 54, the control amounts of the respective absorbers are set to a single value. Only affected by vehicle height sensor.

That is, heave attitude control amount CH, pitch attitude control amount CP, the roll attitude control amount CR, and warp attitude control amount CW, respectively, heave DHT = D FL + D FR + D RL + D RR, pitch DPT = - D FL- D FR + D RL + D RR, a roll DRT = D FL- D FR + D RL- D RR, and warp DWT = D FL- D FR- D RL- D RR, since affected, it is assumed the control gain and the like is equal to if, for example, it affects the absorber control amount EHfr, heating
Pitch attitude control amount CH, pitch attitude control amount CP, roll attitude
A value CH-CP- from which the control amount CR and the warp attitude control amount CW are subtracted.
Calculation results for CR-CW is a function of four times the value of the vehicle height D FR, which is affected only by the detection vehicle height DFR of vehicle height sensors 15Fr, affected by other vehicle height sensor Absent. In this case, if the vehicle height sensor 15fr breaks down and the vehicle height at the FR position is replaced by the heave target value (Ht / 4), the detected vehicle height always matches the target value, so that the absorber control amount EHfr is always 0. , Suspension control is not performed for the absorber at the FR position.

However, in this example, heave DFT , pitch DPT and roll
Since the control gain for the warp DWT is set smaller than that of the DRT , even if the detected vehicle height is replaced with the heave target value due to the failure of the vehicle height sensor, the control for the relevant absorber in step 54 is performed. The control amount does not become 0, and the control is performed for all the absorbers.

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

First, the CPU 17 calculates a correction amount CGT for suppressing a change in pitch due to a change in the vertical acceleration Pg (55 to 58). In this case, the contents of the register GPT2 in which the correction amount corresponding to Pg was previously written are written in the register GPT1 (55),
The correction amount Gpt corresponding to Vs and Pg is read from one area of the ROM (Table 6) and written into the register GPT2 (5
7). The data Gpt of Table 6 is grouped using Vs as an index, and the CPU 17 specifies a group with Vs,
Reads the data Gpt corresponding to Pg in the specified group. The smaller the Vs is assigned to each group, the smaller the dead zone a width (Gpt = in the table 6 shown in FIG. 10b).
(Width of 0) is set large. b is a region in which the control performance is increased by increasing the gain as the longitudinal acceleration Pg increases, and c is a region in which the control performance is reduced due to a possible sensor abnormality.

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

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

D Kgp ₂ of (differential) term Kgp ₂ · (GPT2-GPT1) is a coefficient of differential term, this factor Kgp _2, the internal in response to the vehicle speed Vs RO
It is read from one area of M (Table 7).
As shown as “Table 7” in FIG. 10b, the coefficient Kgp
_In general, ₂ is a larger value as the vehicle speed Vs is higher, and the weight of the differential term is increased. This is a correction term in which the differential term tries to suppress the change in the longitudinal acceleration Pg quickly. As the vehicle speed increases, the brake is depressed / released, and the acceleration / deceleration by the accelerator pedal is increased.
This is because the change in the vertical acceleration Pg due to deceleration, turning / turning back by turning of the steering, and the like is fast, and the attitude change is to be quickly suppressed in response to the fast change. On the other hand, when the vehicle speed Vs exceeds a certain level, when the brake is depressed / released, acceleration / deceleration by the accelerator pedal, turning / turning back by turning the steering, etc. are performed rapidly, the change in the longitudinal acceleration Pg is rapid and extremely large. In this case, an excessive differential term that quickly suppresses a sudden change in attitude degrades the stability of longitudinal acceleration suppression. Therefore, the coefficient Kgp _{2 in the} table 7 changes more precisely when the vehicle speed Vs is low, and is constant when the vehicle speed Vs is equal to or higher than a predetermined value, with respect to the change in the vehicle speed Vs. That is, the vehicle speed Vs
When the vehicle speed is low, the weight of the differential term greatly changes with respect to the fluctuation of the vehicle speed. However, when the vehicle speed Vs is high, the weight of the differential term does not change with the fluctuation of the vehicle speed.

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

Next, the CPU 17 calculates a correction amount CGR for suppressing a roll change due to a change in the lateral acceleration Pg (that is, suppressing a change in the lateral acceleration Pg) (59 to 62). In this case, the contents of the register GRT2 in which the correction amount corresponding to the Rg was previously written are written into the register GRT1 (59), and the correction amount Grt corresponding to the Vs and the Rg is read from one area (table 8) of the internal ROM. This is written into the register GRT2 (61). The data Grt in Table 8 is grouped using Vs as an index, and C
The PU 17 specifies a group with Vs, and reads out the data Grt corresponding to Rg in the specified group. In each group, the smaller the Vs is, the smaller the dead zone a width (10th
The width of Grt = 0 in the table 8 shown in FIG. b is a region where the control performance is increased by increasing the gain as the lateral acceleration Rg is increased, and c is a region where the control performance is reduced due to a possible sensor abnormality.

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

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

D Kgr ₂ of (differential) term Kgr ₂ · (GRT2-GRT1) is a coefficient of differential term, this factor Kgr _2, the internal in response to the vehicle speed Vs RO
It is read from one area of M (Table 9).
As shown as “Table 9” in FIG. 10b, the coefficient Kgr
_In general, ₂ is a larger value as the vehicle speed Vs is higher, and the weight of the differential term is increased. This is a correction term in which the differential term tries to suppress the change in the lateral acceleration Rg quickly. The higher the vehicle speed, the faster the change in the lateral acceleration Rg due to turning / turning back by turning the steering wheel. The reason is to try to suppress this quickly in response. On the other hand, the vehicle speed Vs
When the steering angle exceeds a certain level, turning / turning back by turning of the steering is performed abruptly, and the change in the lateral acceleration Rg becomes sharp and extremely large, and an excessive differential term that suppresses such a sudden change quickly. Means that the stability of suppressing the lateral acceleration is lost. Therefore, the coefficient Kg in Table 9
r ₂ is more finely, to changes in vehicle speed Vs, largely changed when the vehicle speed Vs is low, the vehicle speed Vs is set to be constant at a predetermined value or more. That is, when the vehicle speed Vs is low, the weight of the differential term greatly changes with respect to the fluctuation of the vehicle speed, but when the vehicle speed Vs is high, the weight of the differential term does not change with respect to the fluctuation of the vehicle speed.

The calculated CGR is a roll correction amount for the suspension, and Kgr ₃ has a weighting coefficient for the aforementioned pitch correction amount CGP and a roll correction amount GES described later,
When the vehicle speed Vs is low, the rate of change of the lateral acceleration Rg is low.
As a constant value in the high speed range, to a region (table 10) of the internal ROM, and stores the coefficient data Kgr ₃ at a speed Vs corresponding. CPU17 reads the coefficient Kgr ₃ corresponding to the velocity Vs, used to calculate the above CGR.

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

Next, the CPU 17 converts the calculated pick correction amount CGP, roll correction amount CGR, and roll correction amount DES into a pressure correction amount addressed to each suspension, and then converts this pressure correction amount into a “vehicle height deviation calculation” ( 31) Values calculated in EHf _L , EHfr, EHr _L , EHrr
(Contents of registers EHf _L , EHfr, EHr _L , EHrr)
The obtained sums Ehf _L , Ehfr, Ehr _L , and Ehrr are stored in registers EHf _L , EHfr, EHr _L ,
Update and write to EHrr (66).

Ehf _L = EHf _L + Kgf _L · (1/4) · (-CGP + Kcgrf · CGR + Kg
ef _L · GES) Ehfr = EHfr + Kgfr · (1/4) · (-CGP + Kcgrf · CGR + Kg
efr · GES) Ehr _L = EHr _L + Kgr _L · (1/4) · (CGP + Kcgrr · CGR + Kger
_L · GES) Ehrr = EHrr + Kgrr · (1/4) · (CGP + Kcgrr · CGR + Kger
r · GES) The first term on the right side of the above equation is the value previously calculated in the “vehicle height deviation calculation” (31), which has been written to the registers EHf _L , EHfr, EHr _L , EHrr. The second term on the right side is the pitch correction amount CGP, roll correction amount CGR, and roll correction amount GES described above.
Is converted into a pressure correction value for each suspension. The coefficients Kgf _L , Kgfr, Kgr _L and Kg
rr _{is, Kgf L = Kf L · Kgs} , Kgfr = Kfr · Kgs, Kgr L = Kr L · Kgs, a _{Kgrr = Krr · Kgs Kf L,} Kfr, Kr L, Krr are each suspension to pressure reference point A coefficient for correcting a pressure error due to a variation in pipe length (pipe length correction coefficient), and Kgs is a coefficient that is predetermined in association with the steering angular velocity Ss, as shown in Table 12, and "Vehicle height deviation calculation" (31)
The pressure correction value for suppressing the acceleration change calculated in “Pitching / rolling prediction calculation” (32) with respect to the pressure correction value calculated in (2) (the second term on the right side of the above equation: (1/4) ·
(-CGP + Kcgrf · CGR + Kgef _L · GES) etc.). If the steering angular velocity Ss is large, a rapid acceleration change is expected, and it is preferable to increase the weight of the pressure correction value for suppressing the acceleration change. Therefore, the coefficient Kgs is roughly set to be large in proportion to the steering angular velocity Ss. However, the steering angular speed Ss is somewhat lower (Sse ° /
(msec or less), the change in acceleration is extremely small, and if it exceeds Sse and is Ssf or less, the acceleration changes at a speed substantially proportional to the steering angular speed Ss. At a steering angular velocity of Ssf or more, the change of the turning radius is rapid and extremely large, and the change of acceleration (particularly lateral acceleration) is extremely large. Control stability is lost. Therefore, the weight coefficient Kgs corresponding to the steering angular velocity Ss is a constant value when Ss is equal to or less than Sse,
Above Sse and below Ssf, a high value that is substantially proportional to Ss,
When Ssf is exceeded, the value at the time of Ssf is a constant value.

The CPU 17 then sets the initial pressure registers PFL ₀ , PFR ₀ , PRL ₀ , PRR
_The initial pressure data written in ₀ (set in steps 16 to 18) is calculated by the sum of the correction pressure for adjusting the vehicle height deviation and the correction pressure for acceleration suppression control (register EHf _L , EHfr, EHr _L , and EHrr) to calculate the pressure to be set for each suspension.
Update and write to f _L , EHfr, EHr _L , EHrr (67).

Referring to FIG. 10c, the content of the "pressure correction" (33) will be described. The CPU 17 determines the output pressure of the pressure control valve due to the line pressure fluctuation corresponding to the detection pressure Dph of the pressure sensor 13rm (the content of the register DPH). 1 of the internal ROM of the correction value PH for correcting the fluctuation of
Read from the area (table 13H) and pressure sensor 1
The correction values PLf (front-wheel correction value) and Plr (rear-wheel correction value) that compensate for the fluctuation of the output pressure of the pressure control valve due to the return pressure fluctuation corresponding to the detection pressure Dp _L (contents of the register DPL) of 3rt A pressure correction value read from one area of the internal ROM (Table 13L) to compensate for fluctuations in the output pressure of the pressure control valve due to fluctuations in the line pressure and return pressure applied to the pressure control valve
Calculate PDf = PH−PLf and PDr = PH−PLr (68,6
9). The reason why the correction value corresponding to the return pressure is divided into the front wheel side and the rear wheel side is that the front wheel side is close to the reservoir and the rear wheel side is far from the reservoir, and the pressure sensor 13rt for low pressure detection is the return value of the rear wheel side. Since the pressure is detected, the return pressure difference between the rear wheel side and the front wheel side is relatively large, so that an error due to this is reduced. Table 13L stores two groups of correction value data groups to be allocated to the rear wheel side and correction value data groups to be allocated to the front wheel side. The latter data is for the front wheel side suspension, and the former is for the rear wheel side suspension. A correction value corresponding to the detected pressure of the pressure sensor 13rt at that time is read from the group.

CPU17, when calculating the correction amount PDf and PDr, by adding these correction value register EHf _L, EHfr, EHr _L, the content of EHRR, register EHf _L, EHfr, EHr _L, updates written to EHRR (7
0).

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

The contents of the warp correction (35) will be described with reference to FIG. 10e. This warp correction (35) is based on lateral acceleration Rg and steering angular velocity.
From Ss, calculate an appropriate target warp DWT (73),
Calculate the warp that appears when the contents of the above registers IHf _L , IHfr, IHr _L , IHrr are output, and calculate the target warp.
An error warp amount for the DWT is calculated (74 to 76), and current correction values dIf _L and d required to make the error warp amount zero.
Ifr, dIr _L, calculates the DIRR (77), registers these current correction value IHF _L, adds IHfr, IHr _L, the content of IHrr, updates writes the sum of these can register (78).

A warp target value Idr corresponding to the lateral acceleration Rg is written in one area (table 14) of the internal ROM of the CPU 17, and a warp target value Ids corresponding to the steering angular acceleration Ss is written in the table 15. In the table 16, the warp correction amount Idrs corresponding to the vehicle body longitudinal inclination and the lateral acceleration Rg (lateral inclination) specified by the values of the registers IHf _L , IHfr, IHr _L , and IHrr to be output is written. ing. Incidentally, the longitudinal _{inclination, K = | (Ihf L +} Ihfr) / (Ihr L + Ihrr) | expressed in has been written data group of K correspondence written in the table 16, the data in each data group, horizontal It is associated with the acceleration Rg.

CPU17, from table 14, reads warp target value Idr corresponding to the lateral acceleration Rg, reads warp target value Idr corresponding to the steering angular velocity Ss, and register IHf _L, IHfr, IHr
Vehicle longitudinal inclination and lateral acceleration specified by the values of _L and IHrr
Table 16 shows the warp correction amount Idrs corresponding to Rg (lateral inclination).
And calculates the warp target value DWT as follows (73).

DWT = Kdw ₁ · Idr + Kdw ₂ · Ids + Kdw ₃ · Idrs The CPU 17 then proceeds to the contents Ih of the registers IHf _L , IHfr, IHr _L and IHrr
f _L, Ihfr, Ihr _L, warp defined by _{Ihrr (Ihf L -Ihfr) - (} Ihr L -Ihrr) was calculated, by checking whether it is within an acceptable range (dead zone) ( 74), when being out of the allowable range, the target Hope DWT than calculated warp _{(Ihf L -Ihfr) - (Ihr} L -Ihr
The value obtained by subtracting r) is written into the warp error correction amount register DWT (75), and when the value is within the allowable range, the contents (DWT) of the register DWT are not changed. Then, the warp error correction amount D
WT (contents of the register DWT) is multiplied by the weighting coefficient Kdw ₄ and the product is updated and written to the register DWT (76), and the warp error correction amount DWT is calculated for each suspension pressure correction amount (exactly, the pressure correction amount). (77), and the corresponding correction is added to the contents of the current output registers IHf _L , IHfr, IHr _L and IHrr (78).

These current output registers IHf _L , IHfr, IHr _L and IHrr
The data, in the subroutine of "output" (36), the pressure control valve 80f _L, 80FR, in 80rr and 80rr addressed, are transferred to the CPU 18, CPU 18 gives the duty controller 32.

According to the suspension control apparatus of the street present invention more [Effect of the Invention], the vehicle height detecting means _{(13f L, 13fr, 13r L} , 13rr) if an abnormality occurs in, its detection vehicle height, target vehicle Since the control is continued by replacing the height with the height (see FIG. 10f), the error of the vehicle height and the attitude is always zero at the position of the vehicle height detecting means where the abnormality has occurred. However, the error in the vehicle height and posture is detected by the remaining normal vehicle height detecting means by converting the detected vehicle height into each of the heave, pitch, roll, and warp postures. Since the pressure is adjusted, the failure of the vehicle height detecting means does not significantly affect the attitude and vehicle height control. There is no danger of the control direction being reversed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a hydraulic circuit of a suspension control device according to one embodiment of the present invention. FIGS. 2, 3, 4, 5, 6, and 7 show the suspension 100fr, the pressure control valve 80fr, the cut valve 70fr, the relief valve 60fr, and the main check shown in FIG. 1, respectively. FIG. 3 is an enlarged vertical sectional view of a valve 50 and a bypass valve 120. 8a and 8b are block diagrams showing a configuration of an electric control system for controlling the suspension control device shown in FIG. 9a and 9b are flowcharts showing the control operation of the microprocessor 17 shown in FIG. Figures 10a, 10b, 10c, 10d, 10e and 1
FIG. 0f is a flowchart showing the contents of the subroutine shown in FIG. 9b. FIGS. 11a and 11b are graphs showing the contents of data written in the internal ROM of CPU 17. FIG. DESCRIPTION OF SYMBOLS 1 ... Pump 2 ... Reservoir 3 ... High pressure port 4 ... Attenuator 6 ... Front wheel high pressure supply pipe 7 ... Accumulator 8 ... High pressure supply pipe 9 ... Rear wheel high pressure supply pipe 10 … Accumulator 11… Reservoir return pipe, 12… Drain return pipe 13f _L , 13fr, 13r _L , 13rr, 13rm, 13rt …… Pressure sensor 14f _L , 14fr, 14r _L , 14rr …… Drain of air release 15f _L , 15fr, 15r _L , 15rr… Vehicle height sensor, 16p, 16r… Acceleration sensor 17,18… Microprocessor, 19 …… Battery 50 …… Main check valve 51 …… Valve base, 52 …… Input port, 53 …… Output port 54 …… Valve seat, 55 …… Communication port 56 …… Compression coil spring, 57 …… Ball valve 60fr, 60f _L , 60rr, 60r _L … Relief valve, 61 …… Valve base 62 …… Input port, 63: Low pressure port, 64: First guide 65: Filter, 66: Valve, 67: Second guide 68 … Valve, 69… Compression coil spring 60m… Main relief valve 70fr, 70f _L , 70rr, 70r _L … Cut valve 71… Valve base, 72… Line pressure port, 73… Pressure adjustment input port 74 Oil drain port, 75 Output port, 76 First guide 77 Guide, 78 Spool 79 Compression coil spring 80fr, 80f _L , 80rr, 80r _L Pressure control valve 81 … Sleeve, 82… Line pressure port, 83… Groove 84… Output port, 85… Low pressure port, 86… Groove 87… High pressure port, 88… Target pressure space, 88 f… Orifice 89… Low pressure port, 90… Spool, 91… Groove 92… Compression coil spring, 93… Valve element 94… Flow path, 95… Needle valve, 96… Fixed core 97… Plunger, 98a… Yoke , 98b ...... end plate 98c ...... low pressure port _{100fr, 100f L, 100rr, 100r} L ...... suspension _{101fr, 101f L, 101rr, 101r} L ...... Shi Kkuabusoba _{102fr, 102f L, 102rr, 102r} L ...... piston rod 103 ...... piston 104 ...... inner cylinder, 105 ...... upper chamber 106 ...... lower chamber, 107 ...... side port 108 ...... vertical through holes 109 ... ... damping valve device, 110 ... lower space, 111 ... piston 112 ... lower chamber, 113 ... upper chamber, 114 ... outer cylinder 120 ... bypass valve, 121 ... input port 122 ... ... low pressure port, 122a …… Low pressure port, 122b …… Flow path 123 …… First guide, 124a …… Valve 124b …… Compression coil spring, 125 …… Needle valve 150 …… A / D conversion unit 170 …… Duty control unit (Duty 180) Current detection unit, 190.200 Driver RY Relay, SW1 Ignition switch SW2 Vehicle speed sensor (lead switch) SW3 Stop lamp switch, SW4 Door switch SW5 Reservoir level warning Switch SW6 ... Vehicle height Sei switch, SN1 ...... steering sensor SN2 ...... throttle sensor SOL1~SOL5 ...... solenoid

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masaki Kasai 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Kunihito 1 Toyota Town Toyota City, Toyota City 1 Toyota Motor Corporation (72) Inventor Toshio Aburaya 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Takashi Yonekawa 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Shuichi Takema 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (56) References JP-A-63-11408 (JP, A) JP-A-63-188510 (JP, A) JP-A-61-261113 (JP, A) A) (58) Field surveyed (Int. Cl. ⁶ , DB name) B60G 17/015

Claims (1)

(57) [Claims] A suspension mechanism provided at each wheel position with an actuator that expands and contracts in accordance with supply and discharge of fluid; pressure source means for supplying fluid to the actuator; supply and discharge of fluid from the pressure source means to the actuator A plurality of regulating valve means for controlling vehicle height; a plurality of vehicle height detecting means for detecting vehicle height information that changes in accordance with the expansion and contraction of the actuator in the vicinity of each wheel; and a vehicle height detected by the plurality of vehicle height detecting means. The heave, roll, pitch and warp of the vehicle are calculated on the basis of the above, the actuator control amounts of the respective wheel positions are calculated based on the calculation results, and the control valve means is controlled in accordance with the actuator control amounts. At least one of the calculated degrees of influence of each heave, roll, pitch, and warp of the vehicle on the actuator control amount is determined by the other. Set to a different state, to identify the presence or absence of each abnormality of the vehicle height detection means, if an abnormality is detected, the value of the detected vehicle height assigned to the vehicle height detection means where the abnormality was detected, Electronic control means for changing over to a value substantially equal to the target vehicle height in the heave attitude and continuing control of each regulating valve means.