JPH0735122B2 - Suspension pressure controller - Google Patents

Description

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

(Prior Art) For example, in Japanese Utility Model Publication No. 62-38402, the damping force or spring constant of the suspension is increased when the steering angular velocity is detected by a sensor and the vehicle speed is equal to or higher than a set value and the steering angular velocity is equal to or higher than the set value. Suspension pressure control has been proposed.

Further, for example, in Japanese Patent Laid-Open No. 63-106133, the turning pattern of the vehicle is determined from the steering angle and the steering angular velocity, the gain is changed correspondingly, and the gain and the lateral acceleration of the vehicle are dealt with. It has been proposed to control the suspension pressure at the time of turning to determine the suspension pressure.

(Problems to be Solved by the Invention) However, in these pressure controls, when the steering angular velocity is high, the proportional gain that determines the suspension pressure correction value with respect to the vehicle height deviation becomes high, and when the steering angular velocity fluctuates, the proportional gain becomes large. If there is a change in the vehicle height when there is a change in the steering angular velocity, it is presumed that the suspension pressure adjusting method for suppressing the change in the vehicle height tends to be excessive or insufficient, and hunting is likely to occur in the suspension pressure. Suspension pressure hunting leads to a cyclical rise and fall in vehicle height,
The ride quality becomes poor and the attitude control of the vehicle body is disturbed.

An object of the present invention is to further improve the riding comfort and make the vehicle body attitude control more stable.

(Means for Achieving the Object) A pressure control device according to the present invention includes a pressure source (1) for supplying a pressure fluid to a suspension (100 fr) that expands and contracts according to the supplied pressure; Suspension (10
Pressure control means (80fr) for adjusting the suspension pressure to the target pressure between 0fr); Height detection means (15f) for detecting the height of the vehicle body supported by the suspension (100fr)
r); Steering angular velocity detecting means (26) for detecting the steering angular velocity (Ss) of the steering mechanism; Height instruction information (Ht) for designating a reference height
For indicating the height (DH) detected by the height detecting means with respect to the reference height indicated by the height instruction information (Ht).
T) deviation (EHT2 = Ht−DHT) and deviation change (EHT2−
Eth1) calculating means for calculating (17); in response to changes of the deviation and the steering angular velocity (Ss), a large amount of correction when the change is high, the large steering angular velocity (Ss) is high [Kh ₄ · Kh ₅ · (EHT2- EHT
1)] and a correction amount (Kh ₁ · EHT 2) corresponding to the deviation, and a correction amount calculating means (17) for calculating the sum of the correction amount (Kh ₁ · EHT 2); Target pressure setting means (32, 33) for electrically energizing the valve;
Equipped with.

The symbols in parentheses are element symbols attached to corresponding elements in Examples described later or numerical symbols used in corresponding arithmetic expressions.

(Operation) According to this, the actual vehicle height detected by the height detecting means (15fr) becomes the reference height specified by the instructing means (17),
The pressure of the suspension is adjusted, but this pressure adjustment is generally PD (proportional, derivative) feedback control of a pressure correction value corresponding to the deviation of the actual vehicle height from the reference height. Therefore, pressure correction proportional to the deviation (Kh ₁ · EHT
2) and pressure correction [Kh ₄・
Kh ₅ · (EHT 2 − EHT 1)] is performed, and when the deviation changes, the D (differential) term [Kh ₄ · K
h ₅ · (EHT2-EHT1)] acts, and when the deviation temporarily becomes large or small, the P (proportional) term (Kh
₁・ EHT2) act to realize responsive and smooth pressure control without hunting.

In particular, D (differential) term _{[Kh 4 · Kh 5 · (EHT2} -EHT1) ] is,
Corresponding to the rotation speed (Ss) of the steering shaft, it is set so that it becomes large when it is high (the coefficient (gain) Kh _{5 of the} D term corresponds to Ss, and it is large when Ss is high and small when Ss is high) Therefore, when steering is performed and there is a possibility that the vehicle height will change due to this, the D term [Kh ₄ · Kh ₅
・ (EHT2-EHT1)] acts quickly, and when a fast and large vehicle height change due to fast steering is expected, the D term acts largely, and slow steering is expected to be small and slow. At times, the D term acts small, and the disturbance of the vehicle height due to the steering is suppressed in advance and appropriately.
Since the P term acts as a pressure correction corresponding to the current vehicle height deviation and accumulated deviation value regardless of the rotation speed (Ss) of the steering shaft, it is necessary to give an excessive or excessive pressure correction depending on the steering angular speed (Ss). There is no.

Therefore, according to the pressure control device of the present invention, the probability that hunting is generated in the suspension pressure is significantly reduced, the riding comfort is significantly improved, and the vehicle body attitude control is not disturbed.

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 the mechanism of a vehicle body support device. The hydraulic pump 1 is a radial pump, is arranged in an engine loop, is rotationally driven by an on-vehicle engine (not shown), sucks oil from the reservoir 2, and rotates to a high pressure port 3 at a rotational speed higher than a predetermined level. Discharge oil at a specified flow rate.

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

In the main check valve 50, the high pressure port 3 has a high pressure supply pipe 8
When the pressure is lower than the pressure of 1, the reverse flow of oil from the high pressure supply pipe 8 to the high pressure port 3 is blocked.

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

The high pressure supply pipe 8 is connected to a front wheel high pressure supply pipe 6 for supplying high pressure to the front wheel suspensions 100f _L and 100fr and a rear wheel high pressure supply pipe 9 for supplying high pressure to the rear wheel suspensions 100r _L and 100rr. The front wheel high pressure supply pipe 6 has an accumulator 7 (for the front wheels), and the rear wheel high pressure supply pipe 9 has an accumulator 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 this pressure control valve 80fr changes the pressure of the front wheel high pressure supply pipe 6 (hereinafter, front wheel line pressure) to a required pressure (electricity thereof). The pressure corresponding to the current value of the coil: suspension suspension pressure) is adjusted (reduced) and applied to the cut valve 70fr and the relief valve 60fr.

When the pressure of the front wheel pressure-reducing supply pipe 6 (front wheel side line pressure) is lower than a predetermined low pressure, the cut valve 70fr has a pressure control valve 80fr (to the (output port 84 and suspension 100f to the output port 84 to the suspension.
r shock absorber 101fr hollow piston rod 102f
to prevent the pressure from escaping from the piston rod 102fr (shock absorber 101fr) to the pressure control valve 80fr, and the output pressure of the pressure control valve 80fr is maintained while the front wheel side line pressure is equal to or higher than a predetermined low pressure. (Suspension support pressure) is directly supplied to the piston rod 102fr.

The relief valve 60fr limits the internal pressure of the shock absorber 101fr to the upper limit value or less. That is, the pressure control valve 80fr
When the pressure of the output port 84 (suspension supporting pressure) exceeds a predetermined high pressure, the output port 84
As a flow, the pressure at the output port of the pressure control valve 80fr is maintained substantially below a predetermined high pressure. The relief valve 60fr further cushions the propagation of this impact to the pressure control valve 80fr when the inner pressure of the shock absorber 101fr rises due to the impact from the road surface to the front right wheel.
When the internal pressure of the shock absorber 101fr rises by shock, the internal pressure of the shock absorber 101fr is changed to the piston rod 100.
reservoir return pipe 11 via fr and cut valve
To release.

Suspension 100fr is an abbreviation, shock absorber 101
It consists of fr and suspension coil spring 119fr,
Pressure control valve 80fr output port 84 and piston rod 10
The body is supported at a height (relative to the front right wheel) corresponding to the pressure (pressure adjusted by the pressure control valve 80fr: suspension support pressure) supplied into the shock absorber 101fr via 2fr.

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

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

Similar to the above, pressure control valve 80f _L , cassette valve 70f _L , relief valve 60f _L , vehicle height sensor 15f _L and pressure sensor 13f
_L is likewise, is equipped with pre-assigned to the suspension 100f _L of the left wheel portion, the pressure control valve 80f _L front wheel high pressure feed pipe 6
Suspended to the required pressure (supporting pressure) connected to 10
0f _L shock absorber 101f _L piston rod 102f _L
Give to.

Similar to the above, pressure control valve 80rr, cut valve 70rr, relief valve 60r, vehicle height sensor 15rr and pressure sensor 13rr
Is similarly assigned to the suspension 100rr of the rear right wheel, and is equipped with the pressure control valve 80rr.
Suspended to the required pressure (supporting pressure) connected to 10
0rr shock absorber 101rr piston rod 102rr
Give to.

Further, similar to the above, the pressure control valve 80r _L , the cut valve 70r _L ,
Relief valve 60r _L , vehicle height sensor 15r _L and pressure sensor 1
Similarly, 3r _L is assigned to the suspension 100r _L on the front left wheel, and is equipped with the pressure control valve 80r _L connected to the rear wheel high pressure supply pipe 9 to provide a required pressure (supporting pressure) to the suspension 100r _{L. L} shock absorber 101r _L piston rod
Give to 102r _L.

In this embodiment, the engine is mounted on the front wheel side,
Along with this, the hydraulic pump 1 is located on the front wheel side (engine room).
Equipped with hydraulic pump 1 to rear wheel suspension 10
The pipe length up to 0rr, 100r _L is longer than the pipe length from the hydraulic pump 1 to the front wheel side suspension 100fr, 100f _L. Therefore, the pressure drop due to the pipe line is large on the rear wheel side, and if oil leakage occurs in the pipe, the pressure drop on the rear wheel side is the largest. Therefore, a pressure sensor 13rm for line pressure detection is connected to the rear wheel high pressure supply pipe 9. On the other hand, the pressure in the reservoir return pipe 11 is lowest at the end on the reservoir 2 side, and tends to increase as the distance from the reservoir 2 increases. I'm trying to detect.

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

FIG. 2 shows an enlarged vertical sectional view of the suspension 100fr. The piston 103 fixed to the piston rod 102fr of the shock absorber 101fr is arranged in the inner cylinder 104 in the upper chamber 10 roughly.
It is divided into 5 and lower chamber 106. Suspension supporting pressure (hydraulic pressure) is supplied to the piston rod 102fr from the output port of the cut valve 70fr, and this pressure is applied to the piston rod 1
It joins the upper chamber 105 in the inner cylinder 104 through the side port 107 of 02fr, and further through the vertical through port 108 of the piston 103, the lower chamber 10
Join 6 A supporting pressure proportional to the product of this pressure and the cross-sectional area of the piston rod 102fr (square of rod radius × π) is applied to the piston rod 102fr.

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

As the front right wheel pushes up, the piston rod
When 102fr suddenly tries to enter below the inner cylinder 104, the internal pressure of the inner cylinder 104 suddenly rises, and similarly the pressure of the lower space 110 tends to suddenly become higher than the pressure of the lower chamber 112. At this time, the damping valve device 109 allows the oil to flow from the lower space 110 to the lower chamber 112 at a predetermined pressure difference or more, but prevents the oil from flowing from the lower space to the lower space 110 via a check valve. It flows into the chamber 112, whereby the piston 111 rises and damps the propagation of the impact (upward) applied from the wheel to the piston rod 102fr. That is, the propagation of the wheel impact (upward thrust) to the vehicle body is buffered.

When the piston rod 102fr relatively tries to come out above the inner cylinder 104 due to the sudden fall of the front right wheel, the inner cylinder 10
The internal pressure of 4 suddenly decreases, and similarly the pressure of the lower space 110 tends to suddenly become lower than the pressure of the lower chamber 112. At this time,
The lower space from the lower chamber 112 above the predetermined pressure difference of the damping valve device 109
Oil is allowed to flow to 110, but oil is allowed to flow from the lower chamber 112 to the lower space 110 via a check valve that prevents the oil from flowing in the reverse direction. A) to the piston rod 102fr. That is, the propagation of the wheel impact (falling down) to the vehicle body is buffered.

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

When there is no vertical movement of the piston rod 102fr relative to the inner cylinder 104, such as during parking, the seal between the inner cylinder 104 and the piston rod 102fr substantially prevents oil from leaking from the inner cylinder 104 into the outer cylinder 114. There is no. But the piston rod
In order to reduce the vertical movement load of 102fr, the seal is supposed to have a sealing characteristic such that a slight oil leak occurs when the piston rod 102fr moves up and down. The oil that has leaked to the outer cylinder 114 is returned to the reservoir 2 through the outer cylinder 114, the drain 14fr (see FIG. 1) that is open to the atmosphere, and the drain return pipe 12 (see FIG. 1) that is 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 , 100rr and 100r _L structure,
The structure is substantially the same as that of the suspension 100fr described above.

FIG. 3 shows an enlarged vertical cross section of the pressure control valve 80fr. The sleeve 81 has a spool accommodating hole formed in the center thereof, and a ring-shaped groove 83 communicating with the line pressure port 82 and a ring-shaped groove 86 communicating with the low pressure port 85 are formed on the inner surface of the spool accommodating hole. Has been done. These ring-shaped grooves 83
Output port 84 is open in the middle between and 86. Spool 90 inserted in the spool storage hole, in the middle of its side peripheral surface,
A ring-shaped groove 91 having a width corresponding to the distance between the right edge of the groove 83 and the left edge of the groove 86 is provided. A valve housing hole is formed at the left end of the spool 90, and the valve housing hole communicates with the groove 91. The valve body 93 pushed by the compression coil spring 92 is inserted into the valve housing hole. This valve body 93 has a through orifice in the center, and this orifice communicates the space of the groove 91 (output port 84) with the space accommodating the valve body 93 and the compression coil spring 92. Therefore, the spool 90 receives the pressure of the output port 84 (regulated pressure on the suspension 100fr) at the left end thereof, and thereby receives the force that is driven to the right. Note that when the pressure of the output port 84 becomes shockingly high, this causes the valve body 93 to move to the left against the pushing force of the compression coil spring 92, creating a buffer space at the right end of the valve body 93. When the output port 84 is shockedly raised, this shocked rising pressure is not immediately applied to the left end surface of the spool 90, and the valve body 93 is
Spool 90 against shocking pressure increase at output port 84
The effect of buffering the right movement of On the contrary, it exerts a function of buffering the leftward movement of the spool 90 against the shocking pressure drop of the output port 84.

The pressure of the target pressure space 88 communicating with the high pressure port 87 via the orifice 88f is applied to the right end surface of the spool 90, and this pressure causes the spool 90 to receive a force to be driven to the left. The line pressure is supplied to the high pressure port 87, but the target pressure space 88 communicates with the low pressure port 89 through the flow passage 94, and the needle valve 95 defines the flow opening of the flow passage 94.
When the needle valve 95 closes the flow path 94, the orifice 88
The pressure of the target pressure space 88 communicating with the high pressure port 87 via f becomes the pressure (line pressure) of the high pressure port 87,
90 is driven to the left, so that the groove 91 of the spool 90 communicates with the groove 83 (line pressure port 82), and the groove 91 (output port
The pressure of 84) rises and this is transmitted to the left side of the valve body 93, and the right driving force is given to the left end of the spool 90. When the needle valve 95 fully opens the flow path 94, the pressure in the target pressure space 88 is
Since it is throttled by the orifice 88f, it is significantly lower than the pressure (line pressure) of the high pressure port 87, and the spool 90 moves to the right, whereby the groove 91 of the spool 90 communicates with the groove 86 (low pressure port 85). The pressure in the groove 91 (output port 84) is reduced, and this is transmitted to the left side of the valve body 93, and the right driving force at the left end of the spool 90 is reduced. In this way, the spool 90
This is a position where the pressure in the target pressure space 80 and the pressure in the output port 84 are balanced. That is, a pressure that is substantially proportional to the pressure in the target pressure space 88 appears at the output port 84.

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

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

When the electric coil 99 is energized, a magnetic flux flows in a loop of the fixed core 96-magnetic material yoke 98a-magnetic material end plate 98a-plunger 97-fixed core 96, and the plunger 97 is attracted to the fixed core 96 and left. The needle valve 95 moves and approaches the flow path 94 (the distance is shortened). By the way, the left end of the needle valve 95 receives the pressure in the target pressure space 88 as a right driving force,
Since the right end of 95 is the atmospheric pressure through the low pressure port 98c of the atmosphere release, the needle valve 95 is driven by the pressure of the target pressure space 88 to the right drive corresponding to its pressure value (this corresponds to the position of the needle valve 95). Under the influence of force, the needle valve 95 is eventually connected to the flow path 94.
On the other hand, the distance is substantially inversely proportional to the current value of the electric coil 99. In order to make the relationship between the current value and the distance linear, as described above, one of the fixed core and the plunger has a truncated cone shape, and the other has a bottomed conical hole shape corresponding thereto.

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

FIG. 4 shows an enlarged sectional view of the cut valve 70fr. The valve housing hole formed in the valve base 71 has a line pressure port 72, a pressure adjustment input port 73, an oil drain port 74 and an output port.
75 are in communication. Line pressure port 72 and pressure adjustment input port
The space 73 is separated by a ring-shaped first guide 76, and the space between the pressure adjusting input port 73 and the output port 75 is a cylindrical guide 77a, 77.
Separated by b and 77c. The oil drain port 74 communicates with the ring-shaped groove on the outer periphery of the second guide 77c, and the second guide 77a,
The oil leaked to the outer circumferences of 7b and 77c is returned to the return line 11.

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

FIG. 5 shows an enlarged vertical cross section of the relief valve 60fr. An input port 62 and a low pressure port 63 are opened in the valve housing hole of the valve base 61. The valve housing hole has a cylindrical first
Guide 64 and second guide 67 are inserted, and input port
The filter 62 communicates with the inner space of the first guide 64 through the filter 65. A valve body 66 having an orifice at its center is inserted into the first guide 64, and the valve body 66 is pushed to the left by a compression coil spring 66a. First guide 6
The space of 4 in which the valve body 66 and the compression coil spring 66a are housed communicates with the input port 62 through the orifice of the valve body 66, and through the opening of the spring seat 66b.
It communicates with the inner space of the guide 67. The conical valve body 68 is pushed to the left by the repulsive force of the compression coil spring 69, and
The opening of 66b is closed. When the pressure (control pressure) of the input port 62 is less than the predetermined high pressure, the coil spring 66 communicating with the input port 62 through the orifice of the valve body 66.
Since the pressure in the storage space is relatively lower than the repulsive force of the compression coil spring 69, the valve body 68 closes the central opening of the valve seat 66b as shown in FIG. 62 is cut off from the inner space of the second guide 67, which communicates with the low pressure port 63 through the hole 67a. That is, the output port 62 is cut off from the low pressure port 63.

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

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

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

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

The needle valve 125 to the electric coil 129. The solenoid device has the same structure and size as the solenoid device consisting of the needle valve 95 to the electric coil 99 shown in FIG. 3 (designed commonly for the pressure control valve and the bypass valve).
The distance of the needle valve 125 with respect to 2b 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 amount of oil flowing from the input port 121, through the orifice of the valve pair 124a, through the inner space of the first guide 123, through the orifice 122b, and into the low pressure port 122 is , Is proportional to the differential pressure across the orifice on the left end surface of the valve body 124a.

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

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

The relief valve 60m has the same structure as the relief valve 60fr described above, but has a conical valve body (68: Fig. 5).
The compression coil spring (69) that presses is made to have a slightly small spring force, and the pressure of the input port (62) (pressure of the high pressure port 3) and the relief valve 60fr change the pressure of the input port 62 to the low pressure port. The output port (62) is blocked from the low pressure port (63) when the pressure is less than a predetermined high pressure, which is slightly lower than the pressure discharged to 63. When the pressure of the input port (62) becomes higher than a predetermined high pressure, the valve disc (6
8) is driven to the far right. Input port (6
The pressure of 2) is discharged to the low pressure port (63), and the pressure of the high pressure port 3 is controlled to a predetermined high pressure or less.

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

The relief valve 60m suppresses the pressure of the high pressure port 3, that is, the pressure of the high pressure supply pipe 8 to a predetermined high pressure or less,
When the pressure of the shock absorber rises, it is released to the return pipe 11 to buffer the shock pressure transmission to the high pressure supply pipe 8.

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

The pressure control valves 80fr, 80f _L , 80rr, 80r _L output the required supporting pressure by controlling the energizing current value of the electric coil (99) so that the suspension pressure control gives the required supporting pressure to the suspension. Output to port (84). When the shock pressure from the suspension propagates to the output port (84), it is buffered and the spool (91) for pressure control is used.
Suppresses turbulence (turbulence in output pressure). That is, the required pressure is stably applied to the suspension.

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

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

FIG. 8 shows the operating conditions, postures, etc. of the vehicle corresponding to the states of various switches and sensors mounted on the vehicle, and the required pressure of each suspension shown in FIG. The following is an outline of the configuration of an electrically controlled type that limits what is desired.

A low-pass filter 31 ₁ is connected to the vehicle height sensors 15f _L , 15fr, 15r _L and 15rr described above, and the low-pass filter 31 _1
1 cuts off high frequency (noise) components of the vehicle height detection signals (analog signals) of the vehicle height sensors and smoothes vibration components having a relatively high frequency, and amplifies the vehicle height signals shaped in this way. 30 ₁ amplifies it to a predetermined level range and supplies it to the A / D converter (IC) 29 ₁ .

Pressure sensors 13f _L and 13f that detect the hydraulic pressure of each suspension
r, 13r _L, the 13rr, and the low-pass filter 31 ₂ is connected, the low-pass filter 31 _2, blocks the high frequency (noise) component of each of the pressure detection signal pressure sensor (analog signal), and relatively The high-frequency vibration component is smoothed, and the pressure signal shaped in this way is amplified by the amplifier 30 ₂ to a predetermined level range and given to the A / D converter (IC) 29 ₂ .

Pressure sensor 13rm for detecting the pressure of the rear wheel high pressure supply pipe 9 and pressure sensor 13rt for detecting the pressure of the rear wheel side of the return pipe 11
The low pass filter 31 ₃ are connected, the low-pass filter 31 _3, blocks the high frequency (noise) component of each of the pressure detection signal pressure sensor (analog signal),
Further, the vibration component having a relatively high frequency is smoothed, and the pressure signal shaped in this way is amplified by the amplifier 30 ₃ to a predetermined level range and given to the A / D converter (IC) 29 ₃ .

In addition, the longitudinal acceleration (+:
The vertical acceleration sensor 16p that detects acceleration, −: deceleration) and the lateral acceleration sensor 16r that detects lateral acceleration in the lateral direction of the vehicle (+: left-to-right acceleration, −right-to-left acceleration) also have low-pass. A filter 31 ₃ is connected, and this low-pass filter 31 ₃ blocks high-frequency (noise) components of the pressure detection signals (analog signals) of the acceleration sensors and smoothes vibration components of relatively high frequency. The thus shaped acceleration signal is amplified by the amplifier 30 ₃ to a predetermined level range and given to the A / D converter (IC) 29 ₃ .

A coil driver is installed in the electric coil 99 of the pressure control valve 80f _L , 80fr, 80r _L , 80rr and the electric coil 129 of the bypass valve 120.
33 is connected. The coil driver 33 has a switching circuit that energizes each of the electric coils, and a current detection circuit that detects the energization current value of each electric coil and generates an analog signal indicating the current value. ) In response to the on (energization) / off (non-energization) instruction from 32, when the on instruction is given, the electric coil and the output terminal of the constant current circuit are electrically connected (on), and the off instruction is given. And shut off. Then, providing an analog voltage indicating the detected current value at all times A / D converter (IC) 29 _3.

The duty controller 32 stores (latches) the energizing current value designation data given from the microprocessor (hereinafter referred to as CPU) 18 to each of the electric coils (each of the pressure control valve and the bypass valve), and feeds back the detection. From the current value to A / D converter (IC) 29 ₃ CPU18
Is input to the coil driver 33, and the CPU 18 adjusts the on / off duty so that the specified current value is obtained, and gives a time series on / off instruction corresponding to this duty to the coil driver 33.

The A / D converters 29 _{1 to} 29 ₃ have four input ports (however, 29 ₃ receives the analog voltage indicating the detected current value of the pressure control valve and the bypass valve from the coil averaging 33) and holds the sample. It is an A / D conversion IC with a built-in circuit, and a CPU
When there is a conversion instruction from 18, the analog voltage of the input port is held in the sample hold circuit and converted into digital data (vehicle height data, pressure data, acceleration data), and the digital data is clock pulse synchronized by the CPU 18. Then, it is serially transferred to the CPU 18. Hold of this analog voltage, digital conversion and transfer of digital data,
The input ports 1 to 4 are sequentially performed. Ie CPU1
When 8 instructs A / D conversion once, the analog voltages of the four input ports are sequentially digital-converted, and the digital data are sequentially transferred to the CPU 18.

The CPU 18 is connected to the CPU 17 in a data transmission / reception relationship. The CPU 17 has a signal indicating that the instruction switch SCS for instructing suspension pressure control is open (L: no pressure control instruction) / closed (H: instruction), and brake pedal is depressed (H) / absent (L). Signal indicating, ignition switch 20
Signal indicating the open (L) / close (H) of the vehicle, a pulse generated by the vehicle speed synchronizing pulse generator 25 for generating an electric signal of one pulse for rotation of the output shaft of the on-vehicle transmission by a predetermined small angle, and coupled to the steering shaft. 1 for each rotation of the specified small angle
The first and second sets of pulses of a rotary encoder 26 for generating a first set of pulses and a second set of pulses that are 90 degrees out of phase, coupled to the rotary shaft of an engine throttle valve. Absolute encoder 27 that generates 3-bit data that indicates the throttle valve opening
And the signal of the level sensor 28 for detecting the oil level of the reservoir 2 (H: lower limit level or less, L: higher than lower limit level), and signals from other sensors not shown, It is supplied from the input / output circuit 34. An indicator such as a warning light is connected to the input / output circuit 34, and when an abnormality is determined in the pressure control of the suspension, the CPU 17 instructs the input / output circuit 34 to display the abnormality. A low-capacity backup power supply circuit 23 is connected to the on-vehicle battery 19, which supplies a constant voltage to the CPU1.
Since it is given to 7, the CPU 17 is always in the operating state and holds the data in its internal memory while the voltage of the battery 19 is equal to or higher than a predetermined value.

A high-capacity constant voltage power supply circuit 21 is connected to the on-vehicle battery 19 via an ignition switch 20, and this power supply circuit 21 gives a low constant voltage to a weak electric element and a circuit such as the CPU 18, and a low-pass filter. 31 _{1 to} 31 ₃ and ON /
A high constant voltage is applied to circuits such as the output circuit 34.

To the ignition switch 20, the contact piece of the self-holding relay 22 is connected in parallel, and the relay 22 is turned on (closed).
/ OFF (open) by CPU17.

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

The CPU 17 handles the line pressure setting / release of the suspension system (Fig. 1), the determination of the vehicle operating state, and the determination result from when the ignition switch 20 is closed to when it is opened, and immediately after the ignition switch 20 is opened. Also, the required pressure (pressure to be set for each suspension) required to establish an appropriate vehicle height and body posture is calculated, and various detected values are determined from the CPU 18 to determine the vehicle acceleration state. The CPU1 with the current value required to set the required pressure.
Give to eight.

Below, referring to the flowchart shown in FIG.
The control operation of U17 and U18 will be explained.First, for ease of understanding, the symbols assigned to the main registers assigned to the internal memory of CPU17 and the contents of the main data written to each register are described. The summary is shown in Table 1.

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

First, refer to FIG. 9a. When the power is supplied to itself (step 1: the backup power supply circuit 23 generates a constant current: the battery 19 is mounted on the vehicle body), the CPU 17 causes the internal registers, counter, timer, etc. to be in the initial standby state. Set the output port to the output port and output the signal level to the initial standby state (electrical energization of each element of the mechanism) (Step 2: In the following parentheses, omit the steps and subroutines, Only the symbols attached to them are noted).
Next, the CPU 17 checks whether the ignition switch 20 is closed (3), and when it is open, waits until it is closed.

When the ignition switch 20 is closed, the coil of the relay 22 is energized to close the contact piece of the self-holding relay 22 (4). When the ignition switch 20 is closed, the high-capacity constant-voltage power supply circuit 21 is connected to the battery 19, and the power supply circuit 21 gives a low constant voltage to the weak electric elements and electric circuits such as the CPU 18, and the high-constant voltage is low-passed. Filter 31 _{1 to} 31 ₃
Since it is given to circuits such as the input / output circuit 34, the CPU1
8 and the like are also electrically energized and are in operation, but when the relay 22 is turned on, the power circuit 21
Since it is connected to the battery 19, even if the ignition switch 20 opens after that, the CPU 17
Until the switch is turned off, the electric circuit system shown in FIG. 8 is electrically energized to maintain the operating state.

When the relay 22 is turned on, the CPU 17 permits the interrupt processing executed in response to the arrival of the pulse signal to the interrupt input ports ASR0 to ASR2 (5).

Here, the outline of the interrupt processing in response to the pulse signal to the input ports ASR0 to ASR2 will be described. First, interrupt processing in response to the pulse generated by the vehicle speed synchronization pulse generator 25 (input port AS
Explaining R2), when the generator 25 generates one pulse,
In response to this, it proceeds to the interrupt process (ASR2), reads the contents of the vehicle speed clock register at that time, restarts the vehicle speed clock register, and calculates the vehicle speed value from the read contents (cycle of vehicle speed synchronization pulse). The value Vs obtained by calculating the weighted average and the vehicle speed calculation value that was held several times before is used as the vehicle speed register VS.
, And returns to the step immediately before proceeding to this interrupt processing (return). By executing this interrupt processing (ASR2),
The vehicle speed register VS always holds the data Vs of the vehicle speed at that time (the time-series smoothed value of the vehicle speed calculation value).

The interrupt processing (input port ASR0) of the rotary encoder 36 for controlling the rotation direction of the steering shaft in response to the first set of generated pulses will be described. This interrupt processing is performed at the rising and falling edges of the first set of generated pulses. When the operation proceeds to (ASR0) and proceeds to the interrupt processing (ASR0) in response to the rising edge, H is written in the flag register for rotation direction determination, and when the interrupt processing (ASRO) proceeds in response to the falling edge, The flag register is cleared (L is written) and the process returns to the step immediately before proceeding to this interrupt processing.

When the rising edge of the second set of pulses appears after the rising edge of the first set of pulses (flag register = H) of the rotary encoder 26, the steering shaft is driven to rotate counterclockwise and the rising edge of the first set of pulses is rising. When the rising edge of the second set of pulses appears next to (flag register = L), the steering shaft is driven to rotate clockwise.

The interrupt processing (input port ASR1) in response to the second set of generated pulses of the rotary encoder 36 for detecting the rotation speed (steering angular speed) of the steer gear shift will be described.
When the second set of pulses (falling edge) arrives, in response to this, the processing proceeds to interrupt processing (ASR1), the contents of the steering clock register at that time are read, the steering clock register is restarted, and the read contents. When the content of the flag register for discriminating the rotation direction is H, the sign of + (counterclockwise rotation) is given, and when the content of the flag register is L, it is denoted as-(clockwise rotation). With a sign
The speed value (including directions + and-) is calculated from it, and the value Ss obtained by taking the speed average value and the weighted average held several times before is written in the steering angular velocity register SS. Return to the step immediately before proceeding to the processing (return). By executing this interrupt processing (ASR1), the steering angular velocity register SS
The data Ss (+ indicates left rotation, − indicates right rotation) indicating the steering angular velocity (time-series smoothed value of velocity calculation value) at that time is always held.

When the CPU 17 permits the above-mentioned interrupt processing, it checks whether the CPU 18 gives a ready signal (6) and also checks whether suspension pressure control is instructed (SCS on) or not (SCS off). Yes (7).

By the way, the CPU 18 executes initialization when the power is supplied to itself (the ignition switch 20 is closed: the power supply circuit 21 outputs Vc = 5V), and the internal registers, counters, timers, etc. are initialized. The contents of the state are set, and the signal level (data designating all electric coil OFF to the duty controller 32) for setting the initial standby state (no electrical energization of each mechanism element) is output to the output port.
Then, the duty controller 32 is connected to the bypass valve 120.
The maximum current value data for fully closing the valve is given to instruct the bypass valve 120 to be energized. With the above settings, the pressure control valves 80f _L , 80fr, 80r _L , and 80rr have zero energization current value, and the pressure of the return pipe 11 is output to the output port (84) of the pressure control valve, but the bypass valve 120 is fully closed. Since the ignition switch 20 is closed (engine rotation), the pump 1
The rotational pressure of 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) starts to increase. Then CPU18
At the first setting cycle, vehicle height sensor 15f _L , 15fr, 15r _L , 15rr, pressure sensor 13f _L , 13fr, 13r _L , 13rr, 13rm, 13rt, longitudinal acceleration sensor
When the 16p and lateral acceleration sensor 16r detection values and the coil driver 33 current detection value are read and updated and written in the internal register, and the CPU 17 requests the transfer of the detected data, the data in the internal register at that time is read. To CPU17. Further, the CPU 17 causes the pressure control valve 80f _L , 80fr, 80r _L , 80rr
And, when the energizing current value data of the bypass valve 120 is sent, these are given to the duty controller 32.

By the way, CPU17, in the check of steps 6 and 7 above,
When the CPU 18 gives a busy signal or the SCS is off, the CPU 18 waits there and executes the waiting process (8 to 11). Even after proceeding to the suspension pressure control of step 14 and subsequent steps, which will be described later, the on / off state of the SCS is checked in step 21 to be described later, and if there is an off (instruction to stop the suspension pressure control), a standby process (8- In step (8), the pressure detection values of all pressure sensors,
The coil driver 33 refers to the current detection values of all electric coils and the vehicle height detection values of all vehicle height sensors to determine whether or not there is an abnormality, and sets the pressure during suspension control standby (while stopped) (bypass valve 120 not energized). As a result, the pressure control valve is fully opened and the pressure control valve is de-energized, and if an abnormality is determined, notification and pressure setting (de-energization of the bypass valve 120, de-energization of the pressure control valve) corresponding to the abnormality are performed (10). If no abnormality is determined, the abnormality processing is canceled (abnormality notification is cleared) (1
1).

Now, when the CPU 18 notifies the ready and the switch SCS is on (instructing suspension pressure control), or in such a case, the above-mentioned abnormality processing (which may not be executed) is released (12), and Cancels the standby process of (may not be executed) (13).

Then, the CPU 17 instructs the CPU 18 to transfer the detection pressure data Dph of the pressure sensor 13rm, receives it, and writes it in the register DPH (14), and the detection pressure (pressure on the rear wheel of the high pressure supply pipe 8) Dph.
However, check if the value exceeds a predetermined value Pph (pressure value lower than 70 kg / cm ^{2 at} which the cut valves 70f _L , 70fr, 70r _L , 70rr start to open) (line pressure rises to a certain degree) (1
Five). If the line pressure has not risen, the process returns to step 6.

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

Then, the energizing current value data required to obtain the required pressure in one area (table 1) of the internal ROM is stored in the registers PFL ₀ and PFR.
₀ , PRL ₀ , PRR ₀ contents Pf _L0 , Pfr ₀ , Pr _L0 , Prr ₀ access to output Pf _L0 to output port 84 of pressure control valve 80f _L Ihf _L , pressure Pfr ₀ energizing current value required to output pressure control valve 80fr output port Ihfr, pressure Pr _L0 energizing current value required to output pressure control valve 80r _L output port Ihr _L , and pressure Energizing current value required to output Prr ₀ to the output port of pressure control valve 80rr
Ihrr, is read from table 1 and output register IH
Write to f _L , IHfr, IHr _L and IHrr (17) and transfer the data of these output registers to the CPU 18. When the CPU 18 receives these data, it gives them to the duty controller 32.

The duty controller 32 uses the energizing current value data Ihf _L , I
The electric coil of the pressure control valve 80f _L is set so that the energizing current value (detection value) of the pressure control valve 80f _L , which is fed back by the CPU 18 by storing (latching) hfr, Ihr _L and Ihrr, becomes Ihf _L.
The ON (energization) / OFF (non-energization) duty of 99 is adjusted, and the time series ON / OFF corresponding to the adjusted duty is adjusted.
An instruction to turn off is given to the coil driver 33 to the pressure control valve 80f _{L, and} to the other pressure control valves 80fr, 80r _L , 80rr, the same duty control is performed so that the time series on / off is performed. An instruction is given to the coil driver 33. With such a current setting, the pressure control valves 80f _L , 80fr, 80r _L , 80rr are substantially Pf _L0 , Pfr respectively when the line pressure is equal to or higher than a predetermined low pressure.
The pressure of ₀ , Pr _L0 , Prr ₀ is output to the output port (84), and the cut valve 70 responds to the rise of the line pressure to a predetermined low pressure or more.
When f _L , 70fr, 70r _L , 70rr is opened, the pressure which is substantially equal to the pressure (initial pressure) Pf _L0 , Pfr ₀ , Pr _L0 , Prr ₀ of each suspension at that time is the cut valve 70f _L , 70fr, 70r. _L, 80f pressure control valve through 70rr _L, 80fr, 80r _L, suspension 100f from 80rr _L, 100fr, 100r _L, supplied to 100RR. Therefore, the ignition switch 20 is opened (engine stopped: pump 1 stopped) to closed (pump 1 driven), and the cut valves 70f _L , 70fr, 70r _L , 70rr are opened (line pressure is a predetermined low pressure or more) for the first time. When the hydraulic line of the suspension communicates with the output port of the pressure control valve, the output pressure of the pressure control valve and the suspension pressure are substantially equal to each other, and a sudden pressure fluctuation of the suspension does not occur. That is, no shocking change in the vehicle body posture occurs.

The above is the pressure control valve 80f _L , 8 when the ignition switch 20 is switched from open to closed (immediately after starting the engine).
This is the initial output pressure setting of 0fr, 80r _L , 80rr.

Next, the CPU 17 starts the ST timer ST. ST
Is the contents of the register ST, and the data ST indicating the second setting cycle, which is longer than the first setting cycle in which the CPU 18 reads the detection value, is written in the register ST.

When the timer ST is started, the CPU 17 reads the state (20). In this case, the open / close signal of the ignition switch 20, the open / close signal of the suspension pressure control instruction switch SCS, the open / close signal of the brake pedal depression detection switch BPS, the throttle opening data of the absolute encoder 27, and the signal of the reservoir level detection switch 28 are transmitted. While reading and writing to the internal register, it instructs the CPU 18 to transfer the detection data, and the vehicle speed sensor 15f _L , 15fr, 15r _L , 15rr
Vehicle height detection data Df _L , Dfr, Dr _L , Drr, pressure sensor 13f _L , 13f
r, 13r _L , 13rr, 13rm, 13rt pressure detection data Pf _L , Pfr, Pr _L , P
rr, Prm, Prt, and pressure control and bypass valves 80
Transfer the energizing current value detection data of f _L , 80fr, 80r _L , 80rr, 120 and write it to the internal register. Then, referring to these read values, it is determined whether there is an abnormality or not, and when it is abnormal, the process proceeds to step 8.

When normal, the CPU 17 next executes line pressure control (LPC). In this, the reference pressure (relief valve 60m
The absolute value and polarity (high / low) of the deviation of the detection line pressure Prm from the relief pressure (a fixed value slightly lower than the relief pressure (predetermined high pressure)) are calculated, and the deviation is added to the current value flowing in the bypass valve 120 at present. Then, a correction value for making the deviation zero is added corresponding to the above, the current value of the bypass valve 120 energization current is calculated, and this is written in the output register. The contents of this output register are transferred to the CPU 18 in step 36 described later. By this "line pressure control" (LPC), the energizing current value of the bypass valve 120 is controlled 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. Will be done.

Now referring to FIG. 9b. When the line pressure control (LPC) is completed, the CPU 17 checks the open / close signal of the switch SCS (21), and if it is open, the process proceeds to step 8. If it is closed, the open / close state of the switch 20 is checked (22), and 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 process (23), the bypass valve 120 is first de-energized to be fully opened (line pressure is released to the return pipe 11). Since the switch 20 is opened (engine stopped: pump 1 stopped), high-pressure discharge of the pump 1 is stopped, and the bypass valve 120 is fully opened, the high-pressure supply pipe 8, the front wheel high-pressure supply pipe 6 (accumulator 7) and Rear wheel high pressure supply pipe 9 (accumulator 1
The pressure of 0) becomes the pressure of the return pipe 11 and the return pipe 11
When the pressure of 1 is released to the reservoir 2, the high-pressure supply pipe 8 and the like become atmospheric pressure. The high pressure supply pipe 8 etc. is a cut valve 70f _L , 7
At the timing when the pressure falls below the specified low pressure at which 0fr, 70r _L , 70rr turns to complete shutoff, the CPU 17 sets the pressure control valves 80f _L , 80f.
Deenergize r, 80r _L and 80rr.

Now, when the switch SCS is closed and the switch 20 is closed, the parameter indicating the vehicle traveling state is calculated (25).
That is, by reading the content Ss of the steering angular velocity register SS,
[The value read this time Ss-the value read last time] / DT1 / Sa (steering angular acceleration) is calculated and written in the register SA, and [the throttle opening Tp read this time, read by subroutine 20, Tp-read last time] Throttle opening] = Ts (throttle opening / closing speed) is calculated and written in the register TS, [subroutine
The vertical acceleration Pg read this time in 20 minus the vertical acceleration read last time] = Pa (change rate of vertical acceleration) is calculated and written in the register PA, and the [read in subroutine 20 read this time Lateral acceleration Rg-Lateral acceleration read last time] = Ra (rate of change in lateral acceleration), and write it to register RA.

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

The CPU 17 executes a "pitching / rolling prediction calculation" (32) after the "vehicle height deviation calculation" (31) to determine the suspension pressure correction amount (first value) corresponding to the vertical and lateral acceleration actually applied to the vehicle body. 2 Correction amount: for each suspension) and calculate [Suspension initial pressure (Pf _L0 , Pfr ₀ , Pr _L0 , Prr ₀ )
+ First correction amount + second correction amount] (calculation intermediate value: for each suspension) is calculated. The details of this content will be described later with reference to FIG. 10b.

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

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

Next, the CPU 17 calculates the warp correction value (current correction value) at the time of turning corresponding to the lateral acceleration Rg and the steering speed Ss in the "warp correction" (35), and supplies this to the pressure control valve. Add value. Details of this content will be described later with reference to FIG. 10e.

Next, the CPU 17 transfers the current value that should be passed through the pressure control valve calculated in the above “output” (36) to each pressure control valve to the CPU 18, and at the same time as the above “line pressure control”. (LPC), the current value to be passed through the bypass valve 120 is transferred to the CPU 18 to the bypass valve 120.

Here, the CPU 17 has completed all the tasks included in the suspension pressure control for one cycle. Therefore, after waiting for the timer ST to time out (37), when the timer ST times out, the process returns to step 19, the timer ST is restarted, and the task of suspension pressure control in the next cycle is executed.

Due to the suspension pressure control operation of the CPU 17 described above, the CPU 18 requests the CPU 18 to transfer the sensor detection value in the ST cycle (second setting cycle) (subroutine 20), and in response thereto, the CPU 18 1 Set cycle is read, and the read values of the past several times and the sensor detection value data for which the weighted average is smoothed are transferred to the CPU 17. Further, in the ST cycle, the current value data to be passed through each of the pressure control valves and the bypass valve 120 is transferred from the CPU 17 to the CPU 18, and the CPU 18 receives the current value data every time the transfer is performed by the duty controller. Output (latch) to 32. Therefore,
The duty controller 32 updates the target current value data in the ST cycle while
The energization duty is controlled so that the current value of 120 (current value detected by the coil driver 33) becomes the target current value.

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

DHT = DFL + DFR + DRL + DRR, DPT =-(DFL + DFR) + (DRL + DRR), DRT = (DFL-DFR) + (DRL-DRR), DWT = (DFL-DFR)-(DRL-DRR). This DPT is calculated in "Pitching error CP calculation" (51), and DRT is calculated in "Rolling error C".
Calculation of R ”(52) and calculation of DWT is“ Warp error ”
Calculation of CW ”(53).

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

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

Similarly, in “Calculation of Warp Error CW” (53), the target warp Wt is set to zero, and the calculated warp DWT is set to the target warp Wt.
The amount of warp error for PID (proportional, integral,
For differential 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 because the target warp is zero) is within the predetermined value (within the allowable range), the warp error amount for PID processing is set to zero, and when it exceeds the predetermined value. Let the amount of warp error for PID processing be −DWT.

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

As shown as "Table 2H" in Fig. 10a, the vehicle speed Vs
The target heave Ht associated with the vehicle speed Vs is 80 Km / h
At low speeds below, high value Ht _{1 and} at high speeds above 120Km / h vehicle speed Vs are low value Ht ₂ , but Vs exceeds 80Km / h 1
In the range of less than 20km / h, the target value is linearly changed with the vehicle speed Vs (curve may be used). In this way, the target value is changed linearly, for example, if 100 Km / h or less, the target value is changed to Ht ₁ , and if 100 Km / h or more, the target value is changed to Ht _2. In the vicinity of 100 km / h, the target heave changes in large steps due to slight changes in Vs, and the vehicle height frequently fluctuates rapidly at high speeds, resulting in poor vehicle height stability.To prevent this, Is.

According to the setting of the above table 2H, the target value changes only slightly when the vehicle speed Vs changes slightly, so the vehicle height target value changes only slightly and the vehicle height stability increases.

The CPU 17 then calculates the aforementioned heave DHT (40). Then, write the contents of the register EHT2 in which the heave error amount calculated last time is written to the register EHT1 (41), calculate the heave error amount HT-DHT this time, and store this in the register EHT2.
Write on (42). As described above, the register EHT1 stores the previous (before ST1) heave error amount, and the register EHT2 stores the current heave error amount. Next, the CPU 17 writes the content of the register ITH2 in which the previous error integrated value is written into the register ITH1 (43), and calculates the current PID correction amount ITh by the following formula.

ITh = Kh ₁ · EHT ₂ + Kh ₂ · (EHT ₂ + Kh ₂ · ITH 1) + Kh ₄ · Kh ₅ · (EHT 2 − EHT ₁ ) Kh ₁ · EHT 2 is the P (proportional) term of the PID operation, Kh ₁ is the coefficient of the proportional term, EHT2 is the content of the register EHT (the amount of heave error this time).

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

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

As shown as “Table 3H” in FIG. 10a, the vehicle speed correction coefficient Kh ₄ is generally a larger value as the vehicle speed Vs is higher, and the weight of the differential term is increased. This is a correction term in which the derivative term tries to quickly accommodate the change in the heave to the target value, and the higher the vehicle speed, the faster the vehicle height changes with respect to the disturbance, so it is increased according to the vehicle speed. . On the other hand, vehicle speed Vs
Above a certain level (40 km / h or more in Table 3H), sudden changes in the vehicle body posture occur when the brake pedal is depressed / released, the accelerator pedal accelerates / decelerates, and the steering wheel turns / turns back. However, it becomes extremely large, and the excessive differential term that quickly compensates for such a sudden change in posture deteriorates the vehicle height control stability. Therefore, more precisely, the vehicle speed correction coefficient Kh ₄ of the table 3H changes greatly with respect to the change of the vehicle speed Vs when the vehicle speed Vs is low, and decreases with increasing vehicle speed Vs. That is, when the vehicle speed Vs is low, the weight of the differential term largely changes with respect to the vehicle speed variation, but when the vehicle speed Vs is high, the weighting of the differential term with respect to the vehicle speed variation is small.

As shown as “Table 4H” in FIG. 10a, the steering angular velocity correction coefficient Kh ₅ is generally a larger value as the steering angular velocity Ss is higher, and the weight of the differential term is increased. This is a correction term for the derivative term to try to fit it into the target value faster with respect to the change of the heave, and the higher the steering angular velocity Ss, the faster the vehicle height change speed with respect to the disturbance. I am raising it. On the other hand, when the steering angular velocity Ss is below a certain level (50 ° / msec or less in Table 4H), the change in the traveling direction is extremely gentle and the weighting of the differential term is small, exceeding 50 ° / msec and 400 ° / 400 °.
Below / msec, the vehicle speed changes at a speed substantially proportional to the steering angular speed Ss. At a steering angular velocity of 400 ° / msec or more, the change in the vehicle body posture becomes abrupt and extremely large, and an excessive differential term that quickly compensates for such a sudden posture change may damage the vehicle height control stability and cause a danger. Becomes Therefore, the coefficient Kh ₅ of the differential term corresponding to the steering angular velocity Ss is Ss 50
400 ° / ms over 50 ° / msec as a constant value below ° / msec
Below ec, a high value that is substantially proportional to Ss, 400 ° / msec
When it exceeds, the value at 400 ° / msec is a constant value.

With the introduction of more than differential term Kh ₄ · Kh ₅ · described (EHT2-EHT1), also further increased correspondingly the coefficient Kh4 in the vehicle speed Vs, is correspondingly greater the coefficient Kh ₅ to the steering angular velocity Ss As a result, weighted differential control corresponding to the vehicle end Vs and the steering angular speed Ss is realized, and highly stable vehicle height control is realized with respect to variations in the vehicle speed Vs and the steering angular speed Vs.

As described above, PID calculation of heave error correction amount ITh (44)
CPU17 calculates the calculated heave error correction amount I
Write Th to the register ITH2 (45), and multiply by the heave error correction amount weighting coefficient Kh6 (weighting for pitch error correction amount, roll error correction amount, and warp error correction amount, which will be described later: contribution ratio in the total correction amount) , Write to the heave error register CH.

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

Fig. 11a shows the contents of table 2P. The pitch target value Pt corresponding to the vertical acceleration Pg is in a direction (decrease) that cancels the pitch appearing by the vertical acceleration Pg. The region a is intended to save energy by increasing the target pitch as the vertical acceleration Pg increases (decreases). The region b is considered to be an abnormal sensor due to abnormal Pg, so the pitch target value should be made smaller. This is to prevent the pitch target value from being given even though Pg is not actually generated. The other operation processing operations are the same as the contents of the above-mentioned “operation of heave error CH” (50), and HT, H
Replace t with PT and Pt, and replace the DHT calculation formula in step 40 with the above-mentioned DPT.
Replace with EPT1, EPT2 in step 41, replace EHT2, HT, DHT in step 42 with EPT2, PT, DPT, replace ITH1, ITH2 in step 43 with ITP1, ITP2 , The ITh calculation formula of the subroutine 44 is replaced with the pitch error correction amount ITp calculation formula which has a completely corresponding relationship, and the table 3H
Is replaced with the coefficient table (3P) for calculating the pitch correction amount ITp, and the table 4H is also replaced with the coefficient table (4P) for calculating the pitch correction amount ITp, and ITH2 and ITh in step 45 are replaced with ITP2 and ITp.
, And CH, Kh ₆ , ITh in step 46 with CP, Kp ₆ , ITp, to calculate "pitch error CP" (51).
A flowchart showing the contents of is displayed. The CPU 17 executes the processing represented by this flowchart.

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

Figure 11b shows the contents of Table 2R. The roll target value Rt corresponding to the lateral acceleration Rg is in a direction (decreasing) for canceling the roll that appears due to the lateral acceleration Rg. The region a is intended to save energy by increasing the target roll as the lateral acceleration Rg increases (decreases). The region b is considered to be an abnormal sensor due to an abnormal Rg. This is to prevent the roll target value from being given even if Rg has not actually occurred. For other calculation processing operations, refer to "Calculation of heave error CH" (5
0) is the same as that in step 39, and HT, Ht in step 39 is changed to RT, R
Substitute t, replace the DHT calculation formula in step 40 with the above DRT calculation formula, replace EHT1, EHT2 in step 41 with ERT1, ERT2, replace EHT2, HT, DHT in step 42 with ERT2, RT, DPT , ITH1 and ITH2 in step 43 are replaced with ITR1 and ITR2, and the ITh calculation formula of the subroutine 44 is replaced with a roller error correction amount ITr calculation formula that has a completely corresponding relationship therewith, and the table 3H
Is replaced with a coefficient table (3R) for calculating the roll correction amount ITr, and table 4H is also replaced with a coefficient table (4R) for calculating the roll correction amount ITp, and ITH2 and ITh in step 45 are replaced with ITR2 and I
Replace Tr, and replace CH, Kh ₆ , ITh in step 46 with CR, Kr ₆ , ITr
By replacing with, "roll error calculation" (5
A flow chart showing the contents of 1) appears. The CPU 17 executes the processing represented by this flowchart.

Next, the CPU 17 executes "calculation of warp error CW" (53), calculates the warp error correction amount CW in the same manner as the heave error CH, and writes it in the warp error register CW. In addition, in this, the warb target value PW corresponding to the heave target value HT
Is set to zero. The other operation processing operations are the same as the content of the above-mentioned "operation of heave error CH" (50),
Replace HT, Ht in step 39 with WT, 0, and replace D in step 40 with
Replace the HT formula with the above DWT formula and
Replace 1, EHT2 with EWT1, EWT2 and replace the contents of step 42 with DWT
When the absolute value of is less than the predetermined value Wm (within the allowable range)
When WT is set to 0 and Wm is provided, -DWT is set to WT, and WT is changed to the content to be written in the register EWT2.
Replace ITH2 with ITW1 and ITW2, and use the ITh calculation formula of subroutine 44 to calculate the warp error correction amount IT
w Replace with the calculation formula, replace Table 3H with the coefficient table (3W) for calculating the warp correction amount ITr, and replace Table 4H with the coefficient table (4W) for calculating the warp correction amount ITw. , ITh with ITW2, ITw, and step 46
Replacing CH, Kh ₆ ,, ITh with CW, Kw ₆ , ITw, a flowchart showing the contents of "Operation of warp error CW" (53) appears. The CPU 17 executes the processing represented by this flowchart.

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

EHf _L = Kf _L · Kh ₇ · (1/4) · (CH-CP + CR + CW), EHfr = Kfr · Kh ₇ · (1/4) · (CH-CP – CR-CW), EHr _L = Kr _L · Kh ₇ · (1/4) · (CH + CP + CR-CW), EHrr = Krr · Kh ₇ · (1/4) · (CH + CP-CR + CW) Coefficients Kf _L , Kfr, Kr _L , Krr are line pressure reference point 13rm And return pressure reference point 13rt, suspension 100f _L , 10
This is a correction coefficient for compensating the suspension supply pressure deviation due to the difference in pipe length of 0fr, 100r _L , 100rr. Kh ₇
Is a coefficient for increasing / decreasing the maximum deviation correction amount corresponding to the steering angular velocity Ss, and is read from one area (table 5) of the internal ROM of the CPU 17 corresponding to the steering angular velocity Ss. When the steering angular velocity Ss is large, a large attitude change is expected and the attitude error amount is expected to increase. Therefore, the coefficient Kh ₇
Is roughly set to be large in proportion to the steering angular velocity Ss. However, when the steering angular velocity Ss is below a certain level (50 ° / msec or less in Table 5), the change in the traveling direction is extremely gentle, and the posture change is small, and it exceeds 400 ° / msec.
At ° / msec or less, the posture change appears at a speed substantially proportional to the steering angular speed Ss. At steering angular velocities exceeding 400 ° / msec, the change in the vehicle body posture becomes abrupt and extremely large, and an excessive amount of correction that quickly compensates for such a sudden posture change impairs vehicle height control stability. Therefore, the correction coefficient Kh ₇ corresponding to the steering angular velocity Ss is Ss of 50 ° / ms.
A constant value is maintained below ec, a high value that is substantially proportional to Ss above 50 ° / msec and 400 ° / msec, and a constant value at 400 ° / msec above 400 ° / msec.

Next, the content of the "pitching / rolling prediction calculation" (32) will be described with reference to FIG. 10b. The above-mentioned "vehicle height deviation calculation" (31) roughly determines the current vehicle body attitude from the current vehicle height, vertical acceleration, and lateral acceleration so as to maintain the vehicle body attitude at a predetermined appropriate value (feedback). do it),
While the suspension pressure is adjusted (feedback control) so that the current vehicle body attitude becomes the predetermined appropriate one, the "pitching / rolling prediction calculation" (32) is roughly It is intended to control longitudinal and lateral acceleration. That is, it is intended to suppress changes in the vertical acceleration Pg and the lateral acceleration Rg of the vehicle body.

The CPU 17 first calculates a correction amount CGT for suppressing a change in pitch due to a change in vertical acceleration Pg (55 to 58). In this case, the contents of the register GPT2 that previously wrote the correction amount corresponding to Pg are written to the register GPT1 (55), and the internal ROM
Correction area for Vs and Pg from 1 area (Table 6)
Read Gpt and write it to register GPT2 (57).
The data Gpt in the table 6 is grouped by using Vs as an index, and the CPU 17 specifies a group by Vs and reads the data Gpt corresponding to Pg in the specified group. In each group, the smaller the Vs is assigned, the larger the dead zone a width (width of Gpt = 0 in the cable 6 shown in FIG. 10b) is set. b is a region where the gain is increased and the control performance is improved as the vertical acceleration Pg is increased, and c is a region where the control performance is reduced because more than the sensor is considered.

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

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

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

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 a weighting coefficient for the roll correction amounts CGR and GES described later.

Next, the CPU 17 calculates a correction amount CGR for suppressing the roll change due to the change of the lateral acceleration Pg (that is, suppressing the change of the lateral acceleration Pg) (59 to 62). In this, the previous R
The contents of the register GRT2 in which the correction amount corresponding to g is written are written in the register GRT1 (59), the correction amount Grt corresponding to Vs and Rg is read from one area (table 8) of the internal ROM, and this is stored in the register GRT2. Write (61). The data Grt in Table 8 is grouped using Vs as an index.
Specifies the group with Vs, and within the specified group,
Read the data Grt corresponding to Rg. Each group has a small V
The width of the dead zone a (the horizontal width of Grt = 0 in the table 8 shown in FIG. 10b) is set to be larger as it is assigned to s. b is a region where the gain is increased and the control performance is improved as the lateral acceleration Rg is increased, and c is a region where the sex control performance is deteriorated because more than the sensor is considered.

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

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

D (differential) term Kgr Kgr ₂ of ₂ · (GRT2-GRT1) is a coefficient of differential term, this factor Kgr _2, the internal in response to the vehicle speed Vs ROM
It is read from one area (table 9). First
As shown as “Table 9” in FIG. 10b, the coefficient Kgr 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 rule that the differential term tries to suppress the change in the lateral acceleration Rg faster, and the higher the vehicle speed, the faster the change in the lateral acceleration Rg due to turning / turning back due to rotation of the steering wheel. This is because it is intended to quickly suppress this by correspondingly. On the other hand, when the vehicle speed Vs exceeds a certain level, when the turning / turning back by the rotation of the steering is suddenly performed, the change of the lateral acceleration Rg becomes rapid and extremely large. An excessive differential term impairs the stability of lateral acceleration control. Therefore, the coefficient Kgr _{2 in} Table 9
In more detail, with respect to the change in the vehicle speed Vs, the change is large when the vehicle speed Vs is low, and is constant when the vehicle speed Vs is equal to or higher than a predetermined value. That is, when the vehicle speed Vs is low, the weight of the differential term largely changes with respect to the vehicle speed variation, but when the vehicle speed Vs is high, the differential term weight does not change with respect to the vehicle speed variation.

The calculated CGR is a roll correction amount for the suspension, and Kgr ₃ is a weighting coefficient for the above-described pitch correction amount CGP and a roll correction amount GES described later, but when the vehicle speed Vs is low, the lateral acceleration Rg Since the rate of change is low,
In the low speed range, the contribution ratio of this roll correction amount CGR is lowered, and in the high speed range, it becomes a constant value, so that it is a region of the internal ROM (Table 1
The coefficient data Kgr ₃ corresponding to the vehicle speed Vs is stored in 0). C
The PU 17 reads the coefficient Kgr ₃ corresponding to the speed Vs and uses it for the above-described calculation of CGR.

Changes in steering position (rotational position) (steering angular velocity
Ss) changes the lateral acceleration Rg, and the rate of change also depends on the vehicle speed Vs. That is, the change in the lateral acceleration Rg is the steering angular velocity 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. The CPU 17 checks whether the steering angular velocity Ss is substantially zero (64), and if it is not substantially zero, reads the roller correction amount Ges corresponding to the combination of Vs and Ss from the table 11 and registers GES. Write to (6
Five). When it is substantially zero (the previous steering angular velocity and the current steering angular velocity are equal: the roll correction amount Ges read out last time can be directly used as the current roll correction amount), and the register GES
The update write to (65) is not executed.

The CPU 17 then calculates the calculated pitch correction amount CGP and roll correction amount C.
The GR and roll correction amount DES are converted to the pressure correction amount for each suspension, and this pressure correction amount is the value EHf _L , EHfr, EHr _L , EHrr calculated in "Vehicle height deviation calculation" (31) previously.
Add to (registers EHf _L , EHfr, EHr _L , EHrr contents),
The obtained sum Ehf _L , Ehfr, Ehr _L , Ehrr is set to the register EHf _L , EHfr, EHr _L ,
Update and write to EHrr (66).

Ehf _L = EHf _L + Kgf _L · (1/4) · (-CGP + Kcgrf · CGR + Kgef _L · GES) Ehfr = EHfr + Kgfr · (1/4) · (-CGP − Kcgrf · CGR + Kgefr · GES) Ehr _L = EHr _L + Kgr _L・ (1/4) ・ (CGP ＋ Kcgrr ・ CGR ＋ Kger _L・ GES) Ehrr ＝ EHrr ＋ Kgrr ・ (1/4) ・ (CGP ＋ Kcgrr ・ CGR ＋ Kgerr ・ GES) The first term on the right side of the above formula is the “vehicle height deviation calculation” first. The value calculated in (31) and written in the registers EHf _L , EHfr, EHr _L , and EHrr. The second term on the right side is the above-mentioned pitch correction amount CGP, roll correction amount CGR and Roll correction amount GES,
It is a value converted into a pressure correction value for each suspension. Note that the coefficients of the second term on the right side Kgf _L , Kgfr, Kgr _L and Kgrr
Is Kgf _L ＝ Kf _L・ Kgs, Kgfr ＝ Kfr ・ Kgs, Kgr _L ＝ Kr _L・ Kgs, Kgrr ＝ Krr ・ Kgs, and Kf _L , Kfr, Kr _L , Krr are of each suspension with respect to the pressure reference point. A coefficient for correcting a pressure error due to a variation in the pipe length (a pipe length correction coefficient), and Kgs is a coefficient that is predetermined in association with the steering angular velocity Ss, as shown in Table 12. "Vehicle height deviation calculation" (31)
The pressure correction value calculated in “Pitching / rolling prediction calculation” (32) for the pressure correction value calculated in Step 3 to suppress acceleration change (the second term on the right side of the above equation: (1/4)
(-CGP + Kcgrf / CGR + Kgef _L / GES) etc.) is specified. If the steering angular velocity Ss is large, a rapid acceleration change is expected, and it is preferable to increase the weighting of the pressure correction value for suppressing the acceleration change. Therefore, the coefficient Kgs is roughly
It is set to a large value in proportion to the steering angular velocity Ss. But,
The steering angular velocity Ss is below a certain level (50 ° / msec in Table 12)
In the following), the change in acceleration is extremely small, and when it exceeds 50 ° / msec and 400 ° / msec or less, the acceleration changes at a speed substantially proportional to the steering angular speed Ss. At a steering angular velocity of 400 ° / msec or more, the turning radius changes rapidly and becomes extremely large, and the acceleration change (especially lateral acceleration) is extremely large. An excessive correction amount that quickly compensates for such a sudden acceleration change. , The stability of acceleration control deteriorates. Therefore,
The weighting coefficient Kgs corresponding to the steering angular velocity Ss is a constant value when Ss is 50 ° / msec or less, and a high value substantially proportional to Ss when Ss is more than 50 ° / msec and 400 ° / msec or less, and 400 ° / msec is set. If it exceeds 400 ° / msec, the value is constant.

Next, the CPU 17 sets the initial pressure data (set in steps 16 to 18) written in the initial pressure registers PFL ₀ , PFR ₀ , PRL ₀ , PRR ₀ ,
The sum of the corrected pressure for adjusting the vehicle height deviation and the corrected pressure for the acceleration suppression control calculated by the subroutine 66 (register EH
f _L , EHfr, EHr _L , EHrr)) to calculate the pressure to be set for each suspension and register EHf _L , EHfr,
Update and write to EHr _L and EHrr (67).

Explaining the contents of the “pressure correction” (33) with reference to FIG. 10c, the CPU 17 determines that the detected pressure Dph of the pressure sensor 13rm (register
The correction value PH for compensating the fluctuation of the output pressure of the pressure control valve due to the fluctuation of the line pressure corresponding to the contents of DPH) is read from one area (table 13H) of the internal ROM, and the pressure sensor 13r
Compensation values PLf (front wheel side correction value) and PLr (rear wheel side correction value) that correspond to the detected pressure Dp _L (contents of register DPL) of t and compensate for the fluctuation of the output pressure of the pressure control valve due to the fluctuation of the return pressure.
Is read from one area of the internal ROM (table 13L), and the pressure correction value PDf = P that compensates for fluctuations in the pressure control valve output pressure due to fluctuations in the line pressure and return pressure applied to the pressure control valve.
Calculate H-PLf and PDr = PH-PLr (68,69). The correction value corresponding to the return pressure is divided into the front wheel side and the rear wheel side because the front wheel side is close to the reservoir, the rear wheel side is far from the reservoir, and the pressure sensor 13rt for low pressure detection is the rear wheel side return. Since the pressure is detected, the return pressure reduction is relatively large on the rear wheel side and the front wheel side, so that the error due to this is reduced. Table 13L stores two groups, a correction value data group assigned to the rear wheel side and a correction value data group assigned to the front wheel side, the latter data for the front wheel side suspension and the former data for the rear wheel side suspension. A correction value corresponding to the pressure detected by the pressure sensor 13rt at that time is read from the group.

CPU17, when calculating the correction value 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).

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

The content of the warp correction (35) will be described with reference to FIG. 10e. This warp correction (35) is applied to lateral acceleration Rg and steering angular velocity Ss.
From this, calculate the appropriate target warp DWT (73), and also calculate the warp that appears when the contents of the aforementioned registers IHf _L , IHfr, IHr _L , and IHrr are output, and calculate the target warp DW of this.
The current correction values dIf _L , dIf required to calculate the error warp amount for T (74 to 76) and set this error warp amount to zero.
r, dIr _L , dIrr are calculated (77), these current correction values are added to the contents of the registers IHf _L , IHfr, IHr _L , IHrr, and the sum is updated and written in these registers (78).

In one area (table 14) of internal ROM of CPU17, lateral acceleration
The warp target value Idr corresponding to Rg is written, the warp target value Ids corresponding to the steering angular velocity Ss is written in the table 15, and the register IHf _L , IHfr to be output is written in the table 16 in the table 16. , IHr _L , IHrr The warp correction amount Idrs corresponding to the vehicle body longitudinal inclination and lateral acceleration Rg (lateral inclination) defined by the values is written. The front-back inclination is expressed by K = | (Ihf _L + Ihfr) / (Ihr _L + Ihrr) |, and the data group corresponding to this K is written in Table 16, and each data of each data group is It is associated with the acceleration Rg.

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

_{DWT = Kdw 1 · Idr + Kdw} 2 · Ids + Kdw 3 · IDrs CPU17 then the register IHf _L, IHfr, IHr _L, the content of IHrr Ih
Calculate the warp (Ihf _L −Ihfr) − (Ihr _L −Ihrr) specified by f _L , Ihfr, Ihr _L , Ihrr and check whether it is within the allowable range (dead zone) ( 74), if out of the allowable range, calculated from target warp DWT Warp (Ihf _L −Ihfr) − (Ihr _L −Ihr
The value obtained by subtracting r) is written to the warp error correction amount register DWT (75), and when it is within the allowable range, the content (DWT) of the register DWT is not changed. Then, the warp error correction amount D
WT (contents of register DWT) is multiplied by the weighting coefficient Kdw ₄ and the product is updated and written in the register DWT (76), and this warp-awa correction amount DWT is set to each suspension pressure correction amount (correctly, 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, data IHR _L and IHrr is a subroutine "output" (36), the pressure control valve 80f _L, 80FR, in 80rr and 80rr addressed, are transferred to the CPU 18, CPU 18 is duty Give to the controller 32.

〔The invention's effect〕

As described above, according to the pressure control device of the present invention, the pressure of the suspension is adjusted so that the actual vehicle height detected by the height detecting means (15fr) becomes the reference height designated by the indicating means (17). However, this pressure adjustment is generally PD (proportional, derivative) feedback control of the pressure correction value corresponding to the deviation of the actual vehicle height from the reference height. Therefore, pressure correction (Kh ₁ · EHT2) proportional to the deviation, and deviation change (differentiation)
Pressure compensation proportional to _{[Kh 4 · Kh 5 · (EHT2} -EHT1 )] is performed, D (differential) term to suppress the change when the deviation is changed _{[Kh 4 · Kh 5 · (EHT2} -EHT1 )] Acts and when the deviation temporarily becomes large or small, the P (proportional) term (Kh ₁ · EHT2) acts so as to suppress it, and as a result, there is no hunting, high responsiveness and Smooth pressure control is realized.

In particular, D (differential) term _{[Kh 4 · Kh 5 · (EHT2} -EHT1) ] is,
Corresponding to the rotation speed (Ss) of the steering shaft, it is set so that it becomes large when it is high (the coefficient (gain) Kh _{5 of the} D term corresponds to Ss, and it is large when Ss is high and small when Ss is high) Therefore, when steering is performed and there is a possibility that the vehicle height will change due to this, the D term [Kh ₄ · Kh ₅ ·
(EHT2-EHT1)] acts quickly, and when a fast and large vehicle height change due to fast steering is expected, the D term acts greatly, and slow steering is expected to result in a small and small vehicle height change. At times, the D term acts small, and the disturbance of the vehicle height due to the steering is suppressed in advance and appropriately.
Since the P term acts as a pressure correction corresponding to the current vehicle height deviation and accumulated deviation value regardless of the rotation speed (Ss) of the steering shaft, an excessive or excessive pressure may be generated depending on the rotation speed (Ss) of the steering shaft. No correction is given.

Therefore, according to the pressure control device of the present invention, the probability of hunting in the suspension pressure is significantly reduced, the riding comfort is significantly improved, and the vehicle body attitude control is not disturbed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a suspension pressure supply system according to an embodiment of the present invention. FIG. 2 is an enlarged vertical sectional view of the suspension 100f _L shown in FIG. FIG. 3 is an enlarged vertical sectional view of the pressure control valve 80f _L shown in FIG. FIG. 4 is an enlarged vertical sectional view of the cut valve 70f _L shown in FIG. FIG. 5 is an enlarged vertical sectional view of the relief valve 60f _L shown in FIG. FIG. 6 is an enlarged vertical sectional view of the main check valve 50 shown in FIG. FIG. 7 is an enlarged vertical sectional view of the bypass valve 120 shown in FIG. FIG. 8 is a block diagram showing the configuration of an electric control system that controls the suspension pressure in accordance with the detected values of the vehicle height sensor, the pressure sensor, etc. of the suspension pressure supply system shown in FIG. 9a and 9b are flowcharts showing the control operation of the microprocessor 17 shown in FIG. 10a, 10b, 10c, 10d and 10e are flowcharts showing the contents of the subroutine shown in FIG. 9b. 11a and 11b are graphs showing the contents of data written in the internal ROM of the CPU 17. 1: Pump, 2: Reservoir, 3: High pressure port 4: Accumulator, 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 13f _L , 13fr, 13r _L , 13rr: Air release drain 15f _L , 15fr, 15r _L , 15rr: Vehicle height sensor 16p: Vertical Accelerometer, 16r: Lateral accelerometer 17: Microprocessor, 18: Microprocessor 19: Battery, 20: Ignition switch 21: Constant voltage power circuit, 22: Relay, 23: Backup power circuit 24: Brake lamp, 25: Vehicle speed synchronization Pulse generator 26: Rotary encoder 27: Absolute encoder 28: Liquid level detection switch, 29 _{1 to} 29 ₃ : A / D converter 30 ₁ to 30 ₃ : Signal processing circuit, 31: Low-pass filter 32: Duty controller, 33: Coil driver 34: Input / output circuit, 50: Main check Valve 51: valve base, 52: input port, 53: output port 54: valve seat, 55: flow port 56: compression coil spring, 57: ball valve 60fr, 60f _L , 60rr, 60r _L : relief valve, 61: valve Base 62: Input port, 63: Low pressure port, 64: First guide 65: Filter, 66: Valve body, 67: Second guide 68: Valve body, 69: Compression coil spring 60m: Main relief valve 70fr, 70f _L , 70rr, 70r _L : Cut valve 71: Valve base, 72: Line pressure port, 73: Pressure adjusting input port 74: Oil drain port, 75: Output port, 76: 1st guide 77: Guide, 78: Spool 79: Compression Coil spring 80fr, 80f _L , 80rr, 80r _L : Pressure control valve 81: Sleeve, 82: Line pressure port, 83: Groove 84: Output port, 85: Low pressure port, 86: Groove 87: High pressure port, 88: Target pressure Space, 88f: Orifice 89: Low pressure port, 90: Spool, 91: Groove 92: Compression coil spring, 93: Valve body 94: Flow path, 95: Needle valve, 96: Fixed core 97: Plunger, 98a: York, 98b: end plate 98c: low pressure port, 99: electric coils _{100fr, 100f L, 100rr, 100r} L: suspension _{101fr, 101f L, 101rr, 101r} L: shock absorber 102fr, 102f _L, 102rr, 102r _L : Piston rod 103: Piston, 104: Inner cylinder, 105: Upper chamber 106: Lower chamber, 107: Side port, 108: Vertical through port 109: Valve damping device, 110: Lower space, 111: Piston 112: Lower Chamber, 113: Upper chamber, 114: Outer cylinder 120: Bypass valve, 121: Input port 122: Low pressure port, 122a: Low pressure port, 122b: Flow path 123: First guide, 124a: Valve body 124b: Compression coil spring, 125: Needle valve 129: Electric coil

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshio Yutani, 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Corporation (72) Inventor, Toshio Onuma 1, Toyota Town, Aichi Prefecture Toyota Motor Corporation ( 72) Inventor Takashi Yonekawa 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Co., Ltd. Examiner Shogo Oshima (56) References JP 63-106133 (JP, A) JP 54-155522 (JP, A) ) JP-A-62-96114 (JP, A)

Claims (1)

[Claims] 1. A pressure source for supplying a pressure fluid to a suspension which expands and contracts according to the supplied pressure; a pressure control means between the pressure source and the suspension, which sets a suspension pressure to a target pressure; Height detecting means for detecting the height of the supported vehicle body; Steering angular velocity detecting means for detecting the steering angular velocity of the steering mechanism; Instructing means for generating height instruction information for specifying a reference height; Calculating means for calculating the deviation of the height detected by the height detecting means with respect to the reference height and the change of the deviation; the steering angular velocity is large when the change is high corresponding to the change of the deviation and the steering angular velocity. A correction amount calculation means for calculating a sum of a correction amount that is large when the correction amount is high and a correction amount that corresponds to the deviation; And a target pressure setting means for electrically energizing the pressure control means so as to apply to the suspension pressure control device.