JPH0676003B2 - Vehicle suspension system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to an improvement of a vehicle suspension device.

(Prior art) A suspension unit having a fluid spring chamber is provided for each wheel, and fluid is supplied to the fluid spring chamber of the suspension unit on the contraction side at the time of turning, and the amount of fluid is set from the fluid spring chamber of the suspension unit on the extension side. There is known a vehicle suspension device that reduces the roll of the vehicle body generated during turning by discharging only the vehicle suspension.

(Problems to be Solved by the Invention) In addition, a switching device that can switch the damping force of the shock absorber provided in the suspension unit in, for example, three stages (hard, medium, and soft) is provided, and the roll is applied to the vehicle body during turning. A suspension device is known in which, when it occurs, the switching device switches the damping force of the shock absorber to a higher level to reduce the roll generated in the vehicle body.

Therefore, if both the roll control by supplying and discharging the fluid and the roll control by switching the damping force can be executed at the same time, the roll of the vehicle body during turning can be more effectively reduced. However, because the damping force of the shock absorber is also increased, if roll control is performed during rough road travel, the road surface followability of the wheels will deteriorate, and not only will the vehicle body skid, but also the ride quality will deteriorate. There is a problem.

The present invention has been made in view of the above points, and an object thereof is a vehicle capable of ensuring road surface followability even when performing roll control during traveling on a rough road and preventing occurrence of skid during roll control. To provide a suspension device for a vehicle.

[Configuration of the Invention] (Means and Actions for Solving Problems) Fluid spring chambers provided for each wheel, and fluid supply means for supplying fluid to the fluid spring chambers via supply valve means, respectively. A fluid discharge means for discharging the fluid from each of the fluid spring chambers via the discharge valve means, a roll amount detection means for detecting a roll amount that may occur in the vehicle body from the motion state of the vehicle, and the roll amount detection means The control target setting means for setting the control target of the fluid supply means and the fluid discharge means according to the roll amount detected by, and the fluid to the compression side fluid spring chamber according to the control target set by the control target setting means. A suspension device provided with roll control means for controlling the supply valve means and the discharge valve means so as to supply and discharge the fluid from the fluid spring chamber on the extension side. A shock absorber capable of switching the damping force in a plurality of steps, target damping force setting means for setting the target damping force of each shock absorber higher as the roll amount detected by the roll amount detecting means increases, and the target Damping force switching means for switching the damping force of each of the shock absorbers according to the target damping force set by the damping force setting means, bad road traveling determination means for determining whether the vehicle is traveling on a bad road, and the bad road traveling determination Correction means for correcting the target damping force set by the target damping force setting means to a lower damping force level by the damping force level of the target damping force when the vehicle determines that the vehicle is traveling on a rough road. And a suspension device for a vehicle.

Embodiment An embodiment of the present invention will be described below with reference to the drawings. In Fig. 1, FS1 is the left front wheel side suspension unit, FS2 is the right wheel side suspension unit, R
S1 is the left rear wheel side suspension unit, and RS2 is the right rear wheel side suspension unit. Each of these suspension units FS1, FS2, RS1, RS2 has the same structure as each other, so the suspensions will be used except for the case of distinguishing between the front wheels and the rear wheels or the left wheels and the right wheels. The unit will be described with reference numeral S.

The suspension unit S includes a shock absorber 1. The shock absorber 1 includes a cylinder mounted on the wheel side, and a piston rod 2 having a piston fitted in the cylinder so as to be swingable and having an upper end supported on the vehicle body side. In addition, the suspension unit S is attached to the upper part of the shock absorber 1.
An air spring chamber 3 having a function of adjusting the vehicle height is provided coaxially with the piston rod 2. A part of the air spring chamber 3 is formed by a bellows 4, and air is supplied to and discharged from the air spring chamber 3 through a passage 2a provided in the piston rod 2 to raise or lower the vehicle height. Can be lowered.

Further, inside the piston rod 2, a control rod 5 having a valve 5a for adjusting the damping force at the lower end is arranged. The control rod 5 is rotated by an actuator 6 attached to the upper end of the piston rod 2 to drive the valve 5a. Due to the rotation of the valve 5a, the damping force of the suspension unit is set to three levels of hard (hard), medium (medium), and soft (soft).

The compressor 11 compresses the air taken in from the air cleaner 12 and sends it to the high pressure reserve tank 15a via the dryer 13 and the check valve 14. That is, the compressor 11 compresses the air taken in from the air cleaner 12 and supplies the compressed air to the dryer 13. Therefore, the compressed air dried by silica gel or the like in the dryer 13 is stored in the high pressure reserve tank 15
It will be stored in a. The compressor 16 has its suction port connected to the low pressure reserve tank 15b and its discharge port connected to the high pressure reserve tank 15a. Reference numeral 18 denotes a pressure switch that is turned on when the pressure in the low pressure reserve tank 15b becomes equal to or higher than a first set value (for example, atmospheric pressure). When the compressor 16 outputs an ON signal of the pressure switch 18, the compressor 16 is driven by a compressor relay 17 which is turned on by a signal from a control unit 36 described later. As a result, the pressure in the low pressure reserve tank 15b is always kept below the first set value.

The air supply from the high pressure reserve tank 15a to each suspension unit S is performed as shown by the solid line arrow in FIG. That is, the compressed air in the high pressure reserve tank 15a is supplied to the suspension units FS1 and FS2 via the air supply flow rate control valve 19, the front air supply solenoid valve 20, the check valve 21, the front left solenoid valve 22, and the front right solenoid valve 23. Sent to. Similarly, the compressed air in the high pressure reserve tank 15a is suspended via the air supply flow control valve 19, the rear air supply solenoid valve 24, the check valve 25, the rear left solenoid valve 26, and the rear right solenoid valve 27. It is sent to the units RS1 and RS2.

On the other hand, the exhaust from each suspension unit S is performed as shown by the broken line arrow in FIG. That is, the compressed air in the suspension units FS1 and FS2 is fed into the low pressure reserve tank 15b via the exhaust direction switching valve 28 including the solenoid valves 22 and 23 and the three-way valve.
Solenoid valves 22, 23, exhaust direction switching valve 28, check valve 29, dryer 13, exhaust solenoid valve 3
1, it may be discharged to the atmosphere via the check valve 46 and the air cleaner 12. Similarly, the compressed air in the suspension units RS1 and RS2 is
7, when it is fed into the low-pressure reserve tank 15b via the exhaust direction switching valve 32, and the solenoid valves 26, 27,
Exhaust direction switching valve 32, check valve 33, dryer 1
3, it may be discharged to the atmosphere via the exhaust solenoid valve 31, the check valve 46 and the air cleaner 12.
A passage in which a small-diameter throttle L is interposed is provided between the check valves 29 and 33 and the dryer 13 as compared with a passage which directly connects the exhaust direction switching valves 28 and 32 and the low pressure reserve tank 15b. There is.

The solenoid valves 22, 23, 26, 27, 28 and 32 described above
As shown in FIGS. 2 (A) and 2 (B), the flow of air as indicated by arrow A when ON (energized state) and the flow of air as indicated by arrow B when OFF (non-energized) are permitted. To do. Further, the air supply solenoid valves 20 and 24 and the exhaust solenoid valve 31 are ON (energized state) as shown in FIGS. 3 (A) and 3 (B).
Allows air circulation as indicated by arrow C, and prohibits air circulation when OFF (non-energized state). Further, when the air flow control valve 19 is in the off state (non-energized), air flows through the orifice o as shown in FIG. Since air flows through the orifice o and the large diameter path D as shown in (B), the air flow rate increases.

34F is a front vehicle height sensor that is mounted between the lower arm 35 of the front right suspension of the vehicle and the vehicle body to detect the front vehicle height, and 34R is mounted between the lateral rod 37 of the rear left suspension of the vehicle and the vehicle body. A rear vehicle height sensor for detecting the rear vehicle height. The signals detected by the vehicle height sensors 34F and 34R are supplied to a control unit 36 including an input circuit, an output circuit, a memory and a microcomputer.

38 is a vehicle speed sensor built into the speedometer,
The detected vehicle speed signal is supplied to the control unit 36. Reference numeral 39 is an acceleration sensor that detects the acceleration acting on the vehicle body. The detected acceleration signal is a control unit.
Supply to 36. 30 is soft roll control mode (SOF
T), auto (AUTO), and sports (SPORTS) are selected as roll control mode selection switches, and 40 is a steering sensor that detects the rotation speed of the steering wheel 41, that is, the steering angular speed. Reference numeral 42 is an access opening sensor (not shown) for detecting the depression angle of the accelerator pedal of the engine. These roll control selection switches 30, sensors 40 and 42
The signal detected by is supplied to the control unit 36. 43 is a compressor relay for driving the compressor 11, and this compressor relay 43 is controlled by a control signal from the control unit 36. 44 is
This is a pressure switch that is turned on when the pressure in the high-pressure reserve tank 15a falls below a ^second set value (for example, 7 kg / cm ² ), and the signal of this pressure switch 44 is the control unit.
Supplied to 36. And the control unit 36
Even if the pressure in the high-pressure reserve tank 15a falls below the second set value and the pressure switch 44 is on, the pressure switch 18
Is turned on, that is, when the compressor 16 is driven, the drive of the compressor 11 is prohibited. Reference numeral 4 denotes a pressure sensor provided in a passage that connects the solenoid valves 26 and 27 to each other, and detects the internal pressure of the rear suspension units RS1 and RS2.

The above solenoid valves 19, 20, 22, 23, 24, 26, 2
The control of 7, 28, 31 and 32 is performed by a control signal from the control unit 36.

Next, the operation of the embodiment of the present invention configured as above will be described. FIG. 11 is a flowchart schematically showing a series of roll controls performed by the control unit 36. First, so-called rough road determination processing is performed in a rough road determination routine (step A1) as a rough road determination means. That is, in this rough road determination routine, when the output change of the front vehicle height sensor 34F is equal to or higher than MHz (N times or more in 2 seconds), the dead zone of the G sensor 39 at this time is widened as a rough road determination, and roll control is performed. Reduces malfunctions. Then, in the roll control routine (step A2) as the roll control means, roll control is performed, that is, air is supplied to the suspension unit on the contraction side and exhausted from the suspension unit on the expansion side to prevent the vehicle body from rolling during turning. ing. Further, the air supply / exhaust time during the roll control is corrected in the air supply / exhaust correction routine (step A3) as the air supply / exhaust time correction means, and is calculated by correcting the air supply / exhaust time of the four wheels independently. Further, in the damping force switching routine (step A4) as the damping force switching means, the damping force of each suspension unit is set to the optimum one of hard (hard), medium (medium) and soft (soft). It Hereinafter, the processes of steps A1 to A4 will be described in detail.

First, referring to FIG. 12, a rough road determination routine (step A
The detailed operation of 1) is explained. First, the front vehicle height Hf detected by the front vehicle height sensor 34F is read into the control unit 36 every predetermined time (step B
1). In the main routine shown in FIG. 11,
It is assumed that various flags IT, A, B, UP, DN described later are set to "0". The flag IT is set to "1" when the rough road determination is started, and the flag A is set to "1" from the time when the front vehicle height Hf shifts from the decreasing state to the increasing state to the time when the front vehicle height Hf shifts to the decreasing state again. The flag B is set to "1" from the time when the front vehicle height Hf changes from the increasing state to the decreasing state to the time when the front vehicle height Hf changes to the increasing state again.
The flag UP is set to "1" when the front vehicle height Hf maintains a decreasing tendency, and the flag DN is set to "1" when the front vehicle height Hf shows an increasing tendency.

First, in the first determination in step B2, since the flag IT is "0", it is determined to be "ON", the flag IT is set to "1", and then the current front vehicle height Hf is set to the register HA.
And the timer Tc is reset (step B3 to
B5).

Then, the front vehicle height Hf is set to the control unit 36.
If it is read in, the determination in step B2 is "YES", and the timer Tc is incremented by the interval time INT (step B6). And the current front vehicle height Hf
Is less than the stored vehicle height HA (step B7),
Alternatively, it is determined whether or not the vehicle height HA is greater than the vehicle height HA (step B22), and the process described below is performed according to the determination. For example, as shown in FIG. 14, from the time t0, the front vehicle height signal Hf
Since the front vehicle height Hf is on the rise, if it is input, it is determined in step B22 that “AA <Hf”, and the process proceeds to step B23. Since the flag UP is set to “0” in the initial setting, “flag DN =
1 "and" flag B = 0 "are set (step B26,
B27), the current front vehicle height Hf is stored in HA (step B
13). Then, whether or not “A × B = 1”, that is, “A = B”
= 1 ”is determined (step B14). This determination is “A × B = 1” when the increase / decrease tendency is reversed when the front vehicle height Hf increases / decreases. At this stage, "A =
Since "B = 0", it is determined to be "ON" in step B14. Next, the routine proceeds to step B16, where it is determined whether or not the timer Tc is counting for 2 seconds or more. However, since 2 seconds have not elapsed at this point, the routine proceeds to the determination at step B28. In step B28, it is determined whether or not the cross-count determination is set, but it is not set yet, so the process returns.

After that, at time t1, the front vehicle height Hf starts to decrease, so that "YES" is determined in step B7 and the process proceeds to the determination in step B8. Here, "flag DN = 1" is determined, but since the flag DN has been set in step B26, it is determined to be "YES" and "flag B = 1",
"Flag DN = 0" is determined (steps B9, B10). After that, as in the case of time t0 described above, steps B13, B1
Returned via 4, B16, B28. Then, as shown in FIG. 14, between the times t1 and t2, the front vehicle height Hf continues to decrease, but when it is determined to be "YES" in step B7 again and the determination in step B8 is reached, Flag DN
= 0, so flag A = as shown in FIG.
0, UP = 1 is set (steps B11, 12).

After that, when the front vehicle height Hf starts to rise after the time t2 in FIG. 14, it is determined to be “YES” in step B22, and the process proceeds to the determination in step B23, but the flag UP has already been set here. Therefore, flag A = 1 and flag UP
= 0 (steps B24, B25).

In this way, as shown in FIG. 14, when the front vehicle height Hf rises and falls, the flag is maintained from the rising state of the front vehicle height Hf to the falling state to the rising state again. B is set to "1", and the flag A is "1" from the time when the front vehicle height Hf shifts from the lowered state to the raised state to the time when the front vehicle height Hf shifts to the lowered state again.
Is set to. Then, after passing through step B13, the process proceeds to step B14. At this stage, “A = 1” and “B =
Since it is “1”, “A × B = 1” holds, and the process proceeds to step B15. As described above, the flags A and B are both set to "1" only when the increasing / decreasing tendency of the front vehicle height Hf is reversed, and "A × B = 1" is set at each reversal. Therefore, in step B15, the counter NCNT is incremented by "+1". That is, the counter NCNT is incremented by “+1” by one increase or decrease in the front vehicle height Hf. Then, the above process is repeated until the count of the timer Tc exceeds 2 seconds,
When the count of the timer Tc exceeds 2 seconds, the timer Tc is reset and it is determined whether the count value of NCNT is N or more (steps B16 to B18). In other words, when it is detected that the front vehicle height Hf has increased or decreased more than N times within 2 seconds, it is determined that the road is bad, NCNT = 0, the bad road determination is set, and the delay timer TR = 0. Was done (steps B19-21)
It will be returned later.

By the way, if it is judged as "NO" in step B16 or B18 and the bad road judgment is set, the delay timer
When TR is incremented by the time INT and the delay timer TR becomes longer than 4 seconds, the rough road determination is reset (steps B29 to B31). In this way, the rough road determination is reset 4 seconds after the final rough road determination is set, that is, 2 seconds after it is determined that the road is not a rough road (“NO”) in step B18. As described above, in the rough road determination routine A1, the counter NCNT is incremented by "1" at step B15 each time the increase or decrease in the front vehicle height Hf is reversed.
Then, when the counter NCNT for 2 seconds is N or more, a rough road determination indicating a rough road is set (step B20). Then, this rough road determination is made in the above step B18.
Is reset 2 seconds after it is determined to be "NO" (that is, not a bad road) (step B31).

Next, the detailed operation of the roll control routine (step A2) will be described with reference to the flowchart of FIG.
First, the vehicle speed V detected by the vehicle speed sensor 38, the lateral acceleration G output from the G sensor 39 and its differential value,
The steering wheel angular velocity H detected by the steering sensor 40 is read by the control unit 36 (steps C1 to C3).
Then, it is determined whether the steering wheel angular velocity H is larger than 30 deg / sec (step C4). That is, it is determined whether the steering wheel is steered. In step C4 above, "YES"
If it is determined that “G × H” is correct, it is determined (step C5). That is, it is determined whether the acceleration G in the left-right direction and the steering wheel angular velocity H are in the same direction. If the determination is “positive”, the steering wheel is on the cutting side, and if the determination is “negative”, the steering wheel is on the steering wheel side. Is being steered. When it is determined to be "YES" in the above step C5, it is selected according to the user's preference.
Referring to one of the V-H maps in the figure,
A control level TCH corresponding to the vehicle speed and the steering wheel angular speed is obtained (step C6). In step C6, when the roll control selection switch 30 selects the soft mode as the roll control mode, the map shown in FIG. 5 is displayed, and when the roll control mode is selected as the auto mode, the map shown in FIG. When the sports map is selected as the roll control mode, the map of FIG. 7 is selected. And the control level TC of each map
A supply / exhaust time and a damping force as shown in FIG. 9 are selected corresponding to H. The relationships among the steering wheel speeds H, vehicle speed V, control level, mode, supply / exhaust time and damping force shown in FIGS. 5 to 7 and 9 are stored in the memory in the control unit 36. Then, the air supply / exhaust correction routine, which will be described later in detail with reference to FIG. 16, corrects and calculates the air supply / exhaust times TCS and TCE of the front and rear wheels independently (step C7). Next, it is determined whether the control flag is being set or distortion (step C8). Since the roll control has not been started yet, it is determined to be "NO" and the process proceeds to step C9. In step C9, it is determined whether the supply / exhaust flag SEF is set. When the supply / exhaust flag SEF is set in the above-mentioned supply / exhaust correction routine (step C7), the control flag is set and the supply / exhaust timer T = 0.
(Steps C10 and C11). Then, the routine proceeds to step C12, where it is judged whether or not the differential pressure is being held, that is, whether or not the differential pressure holding flag described later is set. When there is a differential pressure, the front and rear exhaust direction switching valves 28, 32 are turned off so that the air discharged from the front or rear is discharged to the low pressure reserve tank 15b. This is the exhaust direction switching valve 2 when the differential pressure is being maintained.
This is because the exhaust direction switching valves 28 and 32 need to be turned off in order to perform additional supply / exhaust control because the valves 8 and 32 are on. Next, in the air supply / exhaust correction routine in step C7, it is determined whether the air supply count KS = 3 is set (step C14), and if it is not set (that is, KS = 1), the air supply flow rate control valve is set. When 19 is turned on, the large path D (Fig. 4) is opened to increase the supply air flow rate (step S15). That is, when KS = 1, as shown in FIG. 16, the control level TC is calculated from the vehicle speed-steering wheel angular velocity map.
This is because H is required, and the air flow rate is increased in order to perform the roll control quickly.

Next, the front and rear air supply valves 20 and 24 are turned on (step C16). Then, the direction of the acceleration G in the left-right direction is determined by the control unit 36 (step C1
7). That is, it is determined whether the direction of the acceleration G in the left-right direction is positive or negative. Here, when the acceleration G is positive, it is determined that the acceleration G is a right turn in the traveling direction, that is, a left turn. On the other hand, when the acceleration G is negative, it is determined that the acceleration G is a left turn in the traveling direction, that is, a right turn. Therefore, when the acceleration G is determined to be right (left turn), the front and rear left solenoid valves 22 and 26 are turned on (step C18). As a result, the air in the air spring chambers 3 of the left suspension unit is discharged into the low pressure reserve tank 15b via the valves 22 and 26 which are in the ON state, respectively, and the air spring chambers 3 of the right suspension unit 3 are discharged. Air is supplied to the inside from the high pressure reserve tank 15a via the air valves 20 and 24 in the on state and the valves 23 and 27 in the off state, respectively.

On the other hand, when it is determined that the acceleration G is on the left side (right turn), the front and rear right solenoid valves 23, 27 are turned on (step C19). As a result, the air in the air spring chambers 3 of the right suspension unit is discharged into the low pressure reserve tank 15b via the valves 23 and 27 which are in the ON state, respectively, and the air in the air spring chambers 3 of the left suspension unit is also discharged. To the air valves 20,2
Air is supplied from the high pressure reserve tank 15a through the valve 4 and the valves 22 and 26 in the off state.

Next, the swing back flag is reset, the differential pressure holding flag described above is set, and the duty timer TD, the duty counter Tn, and the duty time counter Tmn are set to zero (steps C20 to C24). Below, above step C1
Return to processing. Then, the process proceeds to step C8 through the processes of steps C1 to C7. At this time, since the control flag is being set, it is determined to be "YES" in step C8 and the process proceeds to step C25. Then, in step C25, the timer T is updated by adding the interval time INT. Then, until the count value of the timer T becomes the air supply time TCS or more or the count value of the timer T becomes the exhaust time TCE or more, the left and right G
The roll control for supplying and exhausting air to the air spring chambers of the left and right suspension units is continuously performed according to the direction. By the way, when the count value of the timer T becomes equal to or longer than the exhaust time TCS, it is determined to be "YES" in Step C26, the flow control valve 19 is turned off, the air supply solenoid valves 20 and 24 are turned off, and the air supply operation is stopped. Yes (steps C27, C2
8). As a result, the air spring chamber 3 on the air supply side is maintained in a high pressure state in which air is supplied for the air supply time TCS. Also,
If the count value of the timer T exceeds the exhaust time TCE, step C
The exhaust direction switching valves 28, 32 are determined as YES in 29.
Is turned on and the exhaust operation is stopped (step C30).
As a result, the air spring chamber 3 on the exhaust side has an exhaust time TC.
Only E is exhausted and the low pressure is maintained. Then, the direction of the acceleration G in the left-right direction is stored in the memory Mg, and when “timer T ≧ TCS”, the control is reset, the roll control is stopped, and the state is held (step C32,
33). In this way, the roll generated on the vehicle body during turning is suppressed. The above processing has been described for the case where the steering wheel is drastically steered, but even if "H≤30 deg / sec", if "Gx" is positive (step C3
4), referring to the G sensor map in FIG. 8, control level T
The CG is obtained, and the same processing as in the case of obtaining the TCH is performed, and the roll control is performed. In Fig. 8, V1 is 30
km / h and V2 are set to 130 km / h. This control level T
The air supply / exhaust time and damping force corresponding to CG can be obtained from Fig. 10. Again, the relationship between the left and right G, the vehicle speed V, the control level, the mode, the supply / exhaust time and the damping force shown in FIGS. 8 and 10 is stored in the memory in the control unit 36. As is apparent from FIGS. 8 and 10, the air supply / exhaust time finally obtained from the G sensor map also differs depending on the mode selected by the control switch 30. Although the soft mode is not shown in FIG. 10, this means that the control level is always zero in the G sensor map when the soft mode is selected.

It should be noted that, as will be described later in detail in the supply / exhaust time correction routine C7, in the present device, the front wheel-side air supply time and the rear wheel-side supply / exhaust time are set to be different from each other.
Therefore, the supply / exhaust time is counted independently on the front wheel side and the rear wheel side based on the count of the supply / exhaust time.

By the way, when "Gx" is negative, that is, when the steering wheel is on the return side, the map of FIG. 6 is referred to and the vehicle speed-steering wheel angular velocity map on the return side is referred to (step
C36), the threshold value HM is obtained, and it is determined whether or not the steering wheel angular velocity H ≧ HM on the return side (step C3).
7). When it is determined to be "YES" in step C37, it is determined whether the temporal change of the acceleration G in the left-right direction is 0.6 g / sec or more (step C38). Here, when it is determined to be “YES” in the above steps C37 and C38, that is, when the steering wheel is rapidly returned to its neutral position when the turning traveling is changed to the straight traveling and the temporal change of the acceleration G is large. In this case, so-called rocking back occurs in which the single body passes through its neutral state and rolls to the opposite side. Therefore, in order to prevent this, the processing from step C39 is performed.

In step C39, it is determined whether the swing back flag is set. At this time, if the process returns to step S39 for the first time, the rewind flag is not set, so "N
It is determined to be "O", the rewind flag is set, and the rewind timer TY is set to "0" (steps C40, C4
1). When it is determined that the acceleration G stored in the memory Mg is left (right turn), the front and rear right solenoid valves 23, 27 are turned off, and the acceleration G is right (left turn). When the determination is made, the front and rear left solenoid valves 22 and 26 are turned off, and the air spring chambers 3 of the left and right suspension units communicate with each other (steps C42 to C44). As a result, the timing of communication between the air spring chambers 3 of the left and right suspension units is accelerated,
The differential pressure between the left and right air spring chambers 3 generated by the roll control is prevented from increasing the swing-back of the vehicle body. Further, the front and rear air supply valves 20 and 24 are turned off, the exhaust direction switching valves 28 and 32 are turned off, the differential pressure holding flag is reset, the control level CL = 0, and the control flag is also reset. Then, the process returns to the above step C1 (steps C45 to C49). When it is determined to be "YES" in steps C37 and C38 and the process proceeds to step C39, the rewind flag has already been set, so the process proceeds to the rewind routine after step C50.

That is, the count value of the timer TY is incremented, and it is determined whether the count value of the timer TY is 0.25 seconds or more (steps C50, C5
1). In this step C51, when it is determined to be "NO", the process returns to the process of the above step C1 and the timer TY is stepped through the subsequent processes and when the count value of the timer TY becomes 0.25 seconds or more, the timer TY is restarted. It is determined whether the count value is 2.25 seconds or more (step C52). Therefore, the tire TY count is
If 0.25 seconds or more and less than 2.25, then step C5 above.
In step 2, it is determined to be "NO" and the process proceeds to step 53 and thereafter. In this step C53, the lateral acceleration G is determined, and when it is determined that the memory Mg is in the right direction, the front and rear left solenoid valves 22 and 26 are turned on, and the lateral acceleration G is determined. Is determined to be left, the front and rear right solenoid valves 23 and 27 are turned on. Further, the exhaust direction switching valves 28 and 32 are turned on (steps C53 to C56). By the process of step C54, the spring constants of the front and rear suspension units can be increased. In this way, when the steering wheel angular velocity H is equal to or greater than the threshold value in FIG. 6 and the temporal change in the left-right acceleration G on the return side is equal to or greater than 0.6 g / sec, the left and right air spring chambers 3 are immediately moved to each other. To prevent the differential pressure between the left and right air spring chambers 3 generated by the roll control from increasing the rolling back of the vehicle body. Further, 0.25 seconds after that, the left-right communication is closed for 2 seconds, so that when the vehicle body returns to its neutral state, the spring constant of each air spring chamber 3 increases and the rolling of the vehicle body to the opposite side is reduced. After 2.25 seconds, step C5 above
In step 2, it is determined to be "YES", the swing back flag is reset, and the swing back processing is ended. (Step C5
7).

Hereinafter, the processing of the step C42 and the subsequent steps is performed, and then the processing of the step C1 and the subsequent steps are performed.

By the way, when it is determined to be "NO" in the above step C37 or C38, that is, when the steering wheel is slowly returned when the turning traveling is changed to the straight traveling, or the time change G of the acceleration G is small, Since the control relating to the shaking back is not suitable, the control described below is performed. That is, first, it is determined whether or not the swing back flag is set (step C58), and if it is set, the process proceeds to step C50 and subsequent steps. This may actually be the case in the control process for rollback.

On the other hand, since the swing-back flag is not set when the above-mentioned turning traveling is slowly changed to straight traveling, it is determined to be "NO" in step C58, and then the lateral acceleration G is at the dead zone level. That is, "G ≤ G0"
Is determined (step C59), and if the dead zone level is reached, it is determined whether the differential pressure is being maintained (step C6).
0) If the differential pressure is being maintained, the process proceeds to step C61 and subsequent steps to gradually release the differential pressure duty control between the left and right air spring chambers 3.

Hereinafter, the processing of the duty control routine performed after step C61 will be described. First, it is determined whether the duty control count Tn is 3 or more (step C61). Then, it is determined whether the duty timer Td is equal to or more than Tmn (step C62). Here, since both TD and Tmn are initially “0”, it is determined to be “YES”. However, if “NO” in the step C62, the duty timer Td
Is stepped (step C63), and the processing for making the damping force of the shock absorber 1 one step harder is performed by steps C64 to 67. Although not shown in the figure, between steps C63 and C64, after the damping force of the shock absorber 1 is established in step C66 or C67 in one control for releasing the differential pressure between the left and right air spring chambers 3, There is a step to return after finishing the process of C63.

By the way, when it is determined to be "YES" in the determination in step C62, that is, when the duty timer Td becomes Tmn, step C
Proceeding to the processing from 68 onward, the processing of intermittently communicating between the left and right air spring chambers 3 is started. First, above step C31
The direction Mg of the acceleration G in the left-right direction stored in is determined (step C68). When the direction of the acceleration G in the left-right direction is the left side, it is determined in step C69 whether the front and rear right solenoid valves 23, 27 are off. Initially, these valves 23 and 27 are turned on (that is, in the differential pressure state), so they are turned off in step C71. As a result, the left and right air spring chambers 3 communicate with each other, and the air in the left air spring chamber 3 flows into the right air spring chamber 3. Further, in steps C72 and C73, the duty counter Tn is incremented, and the duty timer Tmn is set to "Tmn + T
m "(Tn is a constant of about 0.1 second) is set, and the process returns to step C1. Then, after Tm seconds, in step C62, `` Y
ES, C68 is judged to be "left" and C69 is reached. Step C6
In 9, the right solenoid valves 23 and 27 have already been turned off, so it is determined to be “YES”, and the process proceeds to step C70, where the solenoid valves 23 and 27 are turned on. Next, the routine proceeds to step C73, where "Tmn + Tm" is set to the duty timer Tmn. In this way, when the process of opening the solenoid valves 23 and 27 for Tm seconds is performed three times, that is, the left and right air spring chambers 3
When the communication between them is executed three times, it is determined to be "YES" in step C61. Then, in steps C74, C75, C76, C82, the front and rear exhaust direction switching valves 28, 32 are turned off, the differential pressure holding flag is reset, the control level CL = 0 is set, and the series duty control is ended.

By the way, if it is determined in step C68 that the position is "right", the same processing as steps C69 to C71 is performed on the left solenoid valves 22 and 26. When this process is also performed three times, the process proceeds to the process of step C74, and the series of processes is ended.

As described above, when the steering wheel is slowly returned when transitioning from turning to straight traveling, or when the temporal change G of the acceleration G is small, the series of duty controls described above is performed between the left and right air spring chambers 3. Since the differential pressure is gradually eliminated, the inside of each air spring chamber 3 can return to the pre-control state very smoothly.

Next, the supply / exhaust correction routine of step A3 described above will be described in detail with reference to FIG. First, the pressure sensor
Rear suspension unit RS1, depending on signal from 45
The internal pressure of RS2 is detected (step D2). Next, the control level TCG obtained from the G sensor map of FIG. 8 or the control level TCH obtained from one of the steering wheel angular velocity-vehicle speed maps of FIGS. 5 to 7 is compared with the control level CL ( If a control level TCG or TCH higher than the control level CL is obtained (steps D3, D4), it is stored in the control level CL (steps D8, D17). The control level register CL is set to "0" as an initial value.

On the other hand, when it is determined that either the control level TCG or TCH is smaller than the control level CL, the supply / exhaust flag SEF is reset, the damping force switching position is reset, and the dead band level is set to the control levels TCG and TCH. "1" is set (steps D5 to D7).

By the way, after the control level TCG is set to the control level CL in step D8, if “TCH ≦ 1” (that is, if the lateral acceleration acting on the vehicle body is small), the supply coefficient Ks is set to “3”. Is set (step D10). on the other hand,
When “TCH> 1” (that is, when the lateral acceleration acting on the vehicle body is small), the air supply coefficient Ks is set to “1” (step D11). When the control level DL is set to the control level DL in step D17, the air supply coefficient Ks is set to "1" (step D11).

Then, after the step D10 or D11, the supply / exhaust flag SEF indicating that the supply / exhaust control needs to be performed is set (step D12), and supply / exhaust is performed by the roll control routine of FIG. Then, it is determined whether the rough road determination set by the rough road determination routine of FIG. 12 is set (step D13). In this step D13, when it is determined that the rough road determination is set, it is determined whether the control level TCG is "2" (step D14), and when the control level is "2", the salary is determined. The exhaust flag SEF is reset, and the dead band level "1" is set in the control level TCG (steps D15, D16). That is,
As shown in Fig. 13, when the control level TCG is "2" at the time of rough road determination, the roll control is performed during the supply / exhaust time of 150 ms in the normal time, but the supply / exhaust time is set to "0". Roll control is not performed. In other words, when a rough road is determined, such as when driving on a rough road, the dead zone width of the G sensor is widened to prevent the roll control from malfunctioning on a rough road.

By the way, after the processing of the steps D7, D13, D14, D16 is completed, the control level TCH, TC is referred to from the obtained control level TCH or TCG with reference to FIG. 9 or FIG.
The basic time Tc of supply and exhaust according to G is calculated (step D
18). Next, the pressure sensor 45 detects the internal pressure (rear internal pressure) of the suspension units RS1 and RS2 on the rear side, and the front internal pressure is estimated from this rear internal pressure by referring to the front internal pressure-rear internal pressure characteristic diagram of FIG. . The front internal pressure-rear internal pressure characteristic diagram will be described in more detail as follows. That is, in a typical passenger car, one passenger in the front seat and two passengers in the rear seat,
Strictly speaking, this characteristic diagram does not match the case of two passengers in the front seat and one passenger in the rear seat. However, it has been confirmed by experiments that the approximate value of the actual front internal pressure can be obtained from the rear internal pressure by creating a characteristic diagram that approximates each riding pattern in consideration of all riding patterns. Further, in the characteristic diagram of FIG. 17, three characteristics of high vehicle height, normal vehicle height and low vehicle height are shown.
This is because the relationship between the rear internal pressure and the front internal pressure differs depending on the high vehicle height, the normal vehicle height, and the low vehicle height. As a matter of course, this characteristic diagram is used that is suitable for the vehicle height at that time. Based on the front internal pressure thus estimated and the rear internal pressure obtained from the pressure sensor 45, the air supply / exhaust correction coefficient characteristic diagram of FIG. 18 is referred to. Also, the supply air correction coefficient PE on the rear side is obtained (step D19).
In FIG. 18, when the internal pressure of the suspension is high, the air supply time is required to supply the same amount of air longer than when the internal pressure is low, so the correction coefficient PS is set to the internal pressure P0. Since the exhaust time is proportional to the internal pressure of the suspension and the time required to exhaust the same amount of air is shorter than when the internal pressure of the suspension is low, the correction coefficient PE is inversely proportional to the internal pressure P0. There is.

Next, it is determined whether or not the compressor 16 (return pump) is stopped (step D20), and when it is stopped, that is, when the pressure difference between the high pressure reserve tank 15a and the low pressure reserve tank 15b is large, the suspension Air supply / exhaust has a large air flow rate even in a short time, so the initial coefficient FK = 0.8
(Step D21). On the other hand, if not stopped,
That is, the high pressure reserve tank 15a and the low pressure reserve tank 15b
When the pressure difference between and is small, the initial coefficient FK = 1 is set and the supply / exhaust time is not corrected (step D22).

Next, the already calculated basic time Tc of the air supply is multiplied by the air supply correction coefficient PS, the air supply coefficient KS and the initial coefficient FK to obtain the corrected air supply time TCS (step D23). Further, the exhaust time TCE already obtained is multiplied by the exhaust correction coefficient PE and the initial coefficient FK to obtain the corrected exhaust time TCE (step D24). The air supply time TCS and the exhaust time TCE have different correction coefficients on the front wheel side and the rear wheel side, and are therefore individually calculated.

Next, referring to FIGS. 9 and 10, the control levels TCG, TC
The damping force switching position corresponding to H is calculated, and the damping force target value DST
The position is set to (step D25). Next, when the rough road judgment is set, if the damping force target value DST is hard, it is changed to medium (step D2
6-D28: These steps correspond to damping force control means). In this way, the control target value of the damping force set in the roll control is supplemented to the low damping force stage when driving on a rough road, so that both proper roll control and prevention of deterioration of riding comfort can be achieved. it can.

Next, the damping force switching routine (step A4) will be described with reference to FIGS. 19 and 20. First, the control level
The damping force target value DST obtained from Fig. 9 or 10 based on TCH or TCG is the damping force value M set manually.
If it is larger than DST (step E1), if it is larger, the damping force is switched so that the damping force current value DDST becomes equal to the damping force target value DST, and the timer TDS is reset (steps E2 to E4). ). The damping force value MDST
Is set to "SOFT" in SOFT mode and AUTO mode, and "HARD" in SPORT mode. And the damping force present value DDST
Is equal to the damping force target value DST, 2 is set by the timer TDS.
The timer TDS is counted until the seconds are counted (steps E5 and E6). When the timer TDS counts 2 seconds, the timer TDS is reset (step E7).
Then, if the differential pressure is being maintained, the damping force value MDST set manually is restored (step E9).

On the other hand, if it is determined in step E8 that the differential pressure is being held, that is, if the roll control is being held, a process of reducing the damping force by one step is performed in steps E10 to E12. That is, if the damping force current value DDST is hard, the damping force is made medium, and if the damping force current value DDST is not hard, the damping force is made soft. In addition, with step E8
Although not shown in the figure between E10 and E10, after the damping force is changed in step E11 or E12 in the period during which a series of differential pressures are being held, step E10 when it is determined to be `` YES '' in step E8, E11 and E12 have steps to return without going through.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to effectively reduce the roll generated in the vehicle body by supplying and discharging the fluid in the fluid spring chamber and switching to a high damping force, and execute roll control. At this time, when the vehicle is traveling on a rough road, a lower target damping force is set as compared with the case where the vehicle is not traveling on a rough road, so that both proper roll control and prevention of deterioration of riding comfort can be achieved. A vehicle suspension device can be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing a vehicle suspension device according to an embodiment of the present invention, FIG. 2 is a diagram showing a three-way valve driven / non-driven state, and FIG. 3 is a solenoid valve driven / non-driving state. Fig. 4 is a diagram showing the drive and non-drive states of the supply air flow control valve, Fig. 5 is a vehicle speed-steering wheel angular velocity map in SOFT mode, Fig. 6 is a vehicle speed-steering wheel angular velocity map in AUTO mode, and Fig. 7 The figure shows the vehicle speed-wheel angular velocity map in SPORT mode, Fig. 8 shows the G sensor map, Fig. 9 shows the relationship between the control level and air supply / exhaust time based on the vehicle velocity-wheel angular velocity map, and Fig. 10 shows the G sensor map. Diagram showing the relationship between control level and air supply / exhaust time,
FIG. 11 is a schematic flow chart showing the operation of one embodiment of the present invention, FIG. 12 is a detailed flow chart showing a rough road determination routine, and FIG. 13 is a diagram showing a G sensor map at the time of normal and rough road determination. , FIG. 14 is a diagram showing a change in state due to output change of the vehicle height sensor, FIG. 15 is a detailed flow chart of a roll control routine, FIG. 16 is a detailed flow chart of a supply / exhaust correction routine, and FIG. 17 is a rear view. Internal pressure-front internal pressure characteristic diagram, FIG. 18 is a characteristic diagram of air suspension internal pressure Po and supply / exhaust correction coefficient, FIG. 19 is a detailed flowchart of a damping force switching routine, and FIG. 20 is a diagram showing changes with time of damping force. is there. 15a …… High pressure reserve tank, 15b …… Low pressure reserve tank, 19 …… Supply flow control valve, 22,23,26,27 …… Solenoid valve, 36 …… Control unit, 36 …… Control unit, 45 …… Pressure sensor.

Front page continuation (72) Inventor Shozo Takizawa 5-3-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation (72) Inventor Minoru Tatemoto 5-33-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Kogyo Co., Ltd. (56) Reference JP 62-74703 (JP, A) JP 61-64517 (JP, A) JP 61-1518 (JP, A)

Claims (1)

[Claims] 1. A fluid spring chamber provided for each wheel, a fluid supply means for supplying a fluid to each fluid spring chamber via a supply valve means, and a discharge valve means for each fluid spring chamber. Fluid discharging means for discharging fluid through the roll, roll amount detecting means for detecting a roll amount that may occur in the vehicle body from the motion state of the vehicle, and fluid supply according to the roll amount detected by the roll amount detecting means Means and a control target setting means for setting a control target of the fluid discharge means, and the fluid is supplied from the expansion side fluid spring chamber to the contraction side fluid spring chamber according to the control target set by the control target setting means. In a suspension device provided with roll control means for controlling the supply valve means and the discharge valve means so as to discharge, a shock absorber provided for each wheel and capable of switching damping force in a plurality of steps. Absorber, target damping force setting means for setting the target damping force of each shock absorber higher as the roll amount detected by the roll amount detecting means increases, and target damping force set by the target damping force setting means. According to the above, the damping force switching means for switching the damping force of each shock absorber, the bad road traveling determination means for determining whether or not the vehicle is traveling on a bad road, and the bad road traveling determination means are determined to be traveling on a bad road. In this case, there is provided a correction means for correcting the target damping force set by the target damping force setting means so that the target damping force becomes a lower damping force step by the water reducing force step of the target damping force. Suspension device.