JPH01103522A - Suspension for vehicle - Google Patents

Abstract

PURPOSE:To contrive to improve comfortableness in riding and road followability at the time of driving on a rough road changing damping force to 'medium' in the case where 'hard' is set to the desired damping force of a suspension, when it is judged to be the rough road. CONSTITUTION:A control unit 36 judges it to be a rough road when an output variation in a level-control sensor 34F is more than N times for two minutes, winding a dead zone of a G sensor 39, and it supplies air to the contraction side of suspension units FS1, FS2, RS1, RS2, thereby performing rolling control to be exhausted out of the expansion side. In the case of this rolling control, a shock absorber 1 of respective suspension units is set to 'hard' by a valve 5a, but when it is judged to be the rough road, the valve 5a is rotated by each motor 6, and damping force is selected to a medium. Riding quality and road followability at the time of driving on the rough road can thus be improved.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to improvements in suspension devices for vehicles.

(Prior technology) A suspension unit having an air spring chamber for each wheel is provided, and when turning, air is supplied to the air spring chamber of the suspension unit on the compression side, and air is supplied from the air spring chamber of the suspension unit on the rebound side. A suspension device for a vehicle has been proposed that discharges a set amount of air to reduce roll of the vehicle body that occurs when turning.

(Problems to be Solved by the Invention) However, in such a suspension device for a vehicle, it is desired to improve ride comfort and road followability when performing roll control while driving on a rough road.

The present invention has been made in view of the above points, and an object of the present invention is to provide a suspension device for a vehicle that can improve ride comfort while driving on rough roads and ensure road followability.

An object of the present invention is to provide a suspension device for a vehicle.

[Structure of the invention] (Means and effects for solving the problem) A fluid spring is provided for each suspension unit that can switch the damping force that supports each wheel into three stages (hard, medium, soft). a damping force switching means for switching the damping force;
a fluid supply means for supplying fluid to each of the fluid spring chambers through respective supply valve means; a fluid discharge means for discharging fluid from each of the above fluid spring chambers through respective discharge valve means; communication means for communicating the fluid spring chamber and the fluid spring chamber of the right suspension unit with each other via a communication control valve; roll amount detection means for detecting the roll amount of the vehicle body; a storage means for storing drive times of the fluid supply means and the fluid discharge means; a rough road travel determination means for determining whether the vehicle is traveling on a rough road; and when the rough road travel determination means detects that the vehicle is traveling on a rough road a switching means for switching to medium when the target damping force of the suspension is set to hard;
When a factor causing roll is detected, a set amount of fluid is supplied to the fluid spring chamber of the suspension unit on the compression side for the above driving time, and a set amount of fluid is discharged from the fluid spring chamber of the suspension unit on the extension side. and roll control means for driving the supply valve means and the discharge valve means.

(Example) An example of the present invention will be described below with reference to the drawings. In Figure 1, FSI is the suspension unit for the left front wheel, FS2 is the suspension unit for the right front wheel, R81 is the suspension unit for the left rear wheel, and R82 is the suspension unit for the left front wheel.
is the suspension unit for the right rear wheel. Each of these suspension units FSI, FS2. R8I, R8
Since the suspension units 2 have similar structures, the suspension units will be described using the reference numeral S, unless the suspension units for the front wheels and those for the rear wheels or for the left wheels and those for the right wheels are explained separately.

The suspension unit S includes a shock absorber 1. This shock absorber 1 has a cylinder attached to a wheel side, a piston slidably fitted in the cylinder, and a piston rod 2 11 whose upper end is supported on the vehicle body side. Further, the suspension unit S is provided on the upper part of this shock absorber 1.
An air spring chamber 3 having a vehicle height adjustment function is provided coaxially with the piston rod 2. This air spring chamber 3 is partially formed by a bellows 4, and by supplying and discharging air to and from this air spring chamber 3 through a passage 2a provided in the piston rod 2, the vehicle height can be increased or It can be lowered.

Further, a control rod 5 is disposed inside the piston rod 2 and has a valve 5a at its lower end for adjusting the damping force. The control rod 5 is the piston rod 2
It is rotated by an actuator 6 attached to the upper end of the valve 5a to drive the valve 5a.

By rotating the valve 5a, the damping force of the suspension unit is set to three levels: hard, medium, and soft.

The compressor 11 compresses atmospheric air taken in from the air cleaner 12 and supplies it to the high pressure reserve tank 15a via the dryer 13 and check valve 14. In other words,
Since the compressor 11 compresses the atmospheric air taken in from the air cleaner 12 and supplies it to the dryer 13, the compressed air dried by silica gel or the like in the dryer 13 is stored in the high-pressure reserve tank 15a. The compressor 16 has a suction port connected to a low pressure reserve tank 15b and a discharge port connected to a 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 exceeds a first set value (for example, atmospheric pressure). When the pressure switch 18 outputs an on signal, the compressor 16 is driven by a compressor relay 17 that is turned on in response to a signal from a control unit 36, which will be described later. As a result, the pressure within the low pressure reserve tank 15b is always maintained below the first set value.

Air is supplied from the high-pressure reserve tank 15a to each suspension unit S as shown by solid arrows in FIG. That is, the compressed air in the high pressure reserve tank 15a is supplied to 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. Suspension unit FSI via front useful solenoid valve 23.

Sent to FS2. Similarly, the compressed air in the high pressure reserve tank 15a is supplied to the suspension unit via the air supply flow control valve 19, the rear air intake solenoid valve 24, the check valve 25, the rear Tachikawa solenoid valve 26, and the rear solenoid valve 27. R81, R8
2.

On the other hand, exhaust from each suspension unit S is performed as shown by the broken line arrows in FIG. That is, the compressed air in the suspension units FSI and FS2 is fed into the low pressure reserve tank 15b via the solenoid valve 22.23 and the exhaust direction switching valve 28 consisting of a three-way valve; , exhaust direction switching valve 28, check valve 29, dryer 13
, exhaust solenoid valve 31, check valve 46, and air cleaner 12, and may be exhausted to the atmosphere. Similarly, the compressed air in the suspension units RSI and R82 is supplied into the low pressure reserve tank 15b via the solenoid valves 26, 27 and the exhaust direction switching valve 32, and when the compressed air is fed into the low pressure reserve tank 15b via the solenoid valves 26, 27 and the exhaust direction switching valve 32. Valve 32, check valve 33, dryer 13, exhaust solenoid valve 31, check valve 4
6 and air cleaner 12, and may be discharged to the atmosphere. Note that a passage is provided between the check valve 29.33 and the dryer 13, which has a smaller diameter than the passage that directly communicates the exhaust direction switching valve 28.32 and the low pressure reserve tank 15b.

In addition, the above-mentioned solenoid valve 22.23°26.2
7.28 and 32, as shown in Figures 2 (A) and (B), flow air as shown by arrow A when ON (energized state) and flow air as shown by arrow B when OFF (de-energized). The distribution of each is permitted. In addition, the air supply solenoid valve 20.24 and the exhaust solenoid valve 31 are shown in Fig. 3 (A) and (B).
As shown in the figure, when ON (energized state), air circulation is allowed as shown by arrow C, and when OFF (non-energized state), air circulation is prohibited. In addition, when the air supply flow rate control valve 19 is in the OFF state (not energized), the orifice is 0 as shown in FIG. 4(A).
Since the air flows through the valve, the air flow rate is small; in the on state (energized), the air flows through the orifice 0 and the large path, as shown in Figure 4 (B), so the air flow rate increases. .

34F is the lower arm 3 of the front right suspension of the vehicle.
5 and the vehicle body to detect the front vehicle height, and 34R is a rear vehicle height sensor installed between the lateral rod 37 of the rear left suspension of the vehicle and the vehicle body to detect the rear vehicle height. It is a sensor. Signals detected by both vehicle height sensors 34F and 34R are supplied to a control unit 36 including a microcomputer.

38 is a vehicle speed sensor built into the speedometer, and supplies a detected vehicle speed signal to the control unit 36. 39 is an acceleration sensor that detects acceleration acting on the vehicle body, and supplies the detected acceleration signal to the control unit 36.

30 sets the roll control mode to soft (SOFT'),
A roll control mode selection switch selects between AUTO and 5 PORTS, and 40 is a steering sensor that detects the rotational speed of the steering wheel 41, that is, the steering angular speed. 42 is an accelerator opening sensor that detects the depression angle of an accelerator pedal of the engine (not shown). Signals detected by the roll control selection switch 30 and the sensors 40 and 42 are 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. 4
4 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, 7Kl/Ci), and a signal from this pressure switch 44 is supplied to the control unit 36. The control unit 36 controls the compressor 11 when the pressure in the high pressure reserve tank 15a is below the set value and the pressure switch 18 is on even if the pressure switch 44 is on, that is, when the compressor 16 is being driven. It is configured to prohibit driving. 45 is solenoid valve 26
．． This is a pressure sensor installed in a passage that communicates between the rear suspension units R8I and R82.
(7) Detect internal pressure.

In addition, each solenoid valve 19.20.22.2 mentioned above
3.24.26.27.28.31 and 32 are controlled by control signals from the control unit 36.

Next, the operation of an embodiment of the present invention configured as described above will be explained. Figure 11 shows control unit 3
6 is a flowchart schematically showing a series of roll controls performed in step 6. First, in the cross country determination routine (step Al), a so-called rough road determination process is performed. In other words, in this cross-country judgment routine, the output change of the front vehicle height sensor 34F is MHz or more (8 times or more in 2 seconds).
When , the G sensor 3 at this time is used as a cross-country judgment.
9's dead zone has been widened to reduce roll control errors. Then, in the roll control routine (step A2), air is supplied to the suspension unit on the compression side and exhausted from the suspension unit on the extension side, thereby preventing the vehicle body from rolling when turning. Further, the air supply and exhaust time during roll control is corrected in the air supply and exhaust correction routine (step A3), and the air supply and exhaust time for each of the four wheels is corrected and determined. Furthermore, in the damping force switching routine (step A4), the damping force of each suspension unit is set to hard (hard), medium (
set to the most appropriate one of medium) and soft. Hereinafter, the processing in steps A1 to A4 will be described in detail.

First, the detailed operation of the cross-country judgment routine (step AI) will be explained with reference to FIG. First, the front vehicle height HE detected by the front vehicle height sensor 34F is read into the control unit 36 at predetermined time intervals (step Bl). In addition, in the main routine shown in FIG. 11, various flags IT, A,
B.

It is assumed that UP and DN are set to "0".

The flag IT is set to "1" when the cross-country judgment starts, the flag A is set to "1" when the front vehicle height H" is in an increasing state, and the flag B is set to "1" when the front vehicle height H" is in a decreasing state. The flag UP is set to "1" when the front vehicle height Hr is increasing, and the flag DN is set to "1" when the front vehicle height Hf is decreasing. Set.

First, in the determination of step B2, "NO"
Therefore, the flag IT-0 is set, the current front vehicle height Hr is stored in HA, and the timer Tc is reset (steps (83 to B5)).

Then, when the front vehicle height Hf is read into the control unit 36, rYES is selected in step B2.
J is determined, and timer Tc is incremented by time INV (step B6). Then, check whether the current front vehicle height r is smaller than the stored vehicle height HA (step B
7), or is it larger than the vehicle height HA (step B22)?
) is determined, and the process described below is performed depending on the determination. For example, if the front vehicle height signal Hr has been input from time 10 as shown in FIG.
It is determined that A<HrJ, and the process proceeds to step 823. In the initial setting, flag UP is set to "0", so "flag DN-IJ, r flag B-0"
” (Steps B26 and B27), the current front vehicle height H1' is stored in the HA (Step 813).
. And whether it is rAxB-IJ, that is, rA-B-1
” (step B14). This determination is made in one cycle when the front vehicle height Hf' increases or decreases.
This is what becomes IJ. Since it is rA-B-OJ at this stage, it is determined to be rNOJ in step B14.

On the other hand, in the case of rAXB-IJ, the counter NCNT is "
+1'' (step B15).

In other words, the counter NCNT is incremented by "+1" by one increase or decrease of the front vehicle height Hf. Then, it is determined whether the count value of NCNT when 2 seconds is counted by the timer Tc is equal to or greater than N (steps 816 to B18). In other words,
When the front vehicle height Hf is increased or decreased by N times in 2 seconds, it is determined that the road is rough, and NCNT-0 and cross-country determination are set.

The delay timer is set to TR-0 (steps 819 to 21).
After that, it will be returned.

By the way, in step B14 above, it is determined that it is rNOJ,
If "2 seconds" is not counted in the timer Tc, rNOJ is determined in step B16, and the process proceeds to determination in step 828. In the determination at step 828, it is determined whether the cross-country determination has been set, but since it has not been set yet, the process returns.

Note that when the cross-country determination is set, the delay timer TR is incremented by the time INT, and when the delay timer TR becomes greater than 4 seconds, the cross-country determination is reset (steps 829 to B51). In other words, the cross-country judgment is reset 4 seconds after it is determined in step 818 that the road is rNOJ, that is, the road is not rough.

Thereafter, at time ti, the front vehicle height Hr begins to decrease, so the determination in step B7 is rYESJ, and the process proceeds to determination in step B8. Here, "Flag DN
-IJ is determined, but the flag DN is set in step B2 above.
Since it is set to 6, it is judged as rYEsJ and "
The flag B-1 and the flag DN-OJ are set (step B9.BIO).As shown in FIG. 14, the front vehicle height Hf continues to decrease between times t1 and t2. , it is determined as rYEsJ again in step B7, and when it comes to the determination in step B8, since the flag is DN-0, flags A-0 and UP-1 are set as shown in FIG. Step Bll,
12).

After that, when the front vehicle height H1' starts to rise after time t2 in FIG. 14, rYEsJ
is determined, and the process proceeds to step 823, but since the flag UP has already been set, the flag is set to A-1, and the flag is set to UP-○ (step B2).
4. B25).

In this way, as shown in FIG. 14, the front vehicle height H
When f' goes up and down, flag B is set to "1" when front vehicle height Hf' is decreasing, and flag A is set to "1" when front vehicle height Hl' is increasing.
” is set. Then, each time the front vehicle height Hr goes up or down, a counter NCNT is set in the step knob B15.
is "+1". If the counter NCNT for 2 seconds is equal to or greater than N, a cross-country determination indicating a rough road is set (step B20). and,
This cross-country judgment is made in step 818 by rNOJ.
(In other words, it is determined that the road is not bad) 4
It is reset after seconds (step B51).

Next, the detailed operation of the roll control routine (step A2) will be explained with reference to the flowchart in FIG. First, vehicle speed V% detected by vehicle speed sensor 38, horizontal acceleration G and its differential value G1 output from G sensor 39, and steering wheel angular velocity θ1 detected by steering sensor 40.
1 is read into the control unit 36 (steps 01 to C3). And the handle angular velocity 19H is 30
It is determined whether it is larger than deg/see (step C4
). In other words, it is determined whether the steering wheel was suddenly turned.

Hereinafter, the process when the steering wheel is steered to the right will be explained. In step C4, if rYEsJ is determined, it is determined whether rcxellJ is correct (step C5
). In other words, the left and right acceleration G and the steering wheel angular velocity are also 1
1 is determined whether the steering wheel is in the same direction, and if it is determined to be "positive", it means that the steering wheel is being steered toward the cutting side, and if it is determined to be "negative", it means that the steering wheel is being steered to the turning direction. There is. If rYEsJ is determined in the above step C5, the images shown in FIGS. 5 to 7 are selected according to the user's preference.
When any of the v-eH maps in the figure is referenced,
A control level TCH corresponding to the vehicle speed and the steering wheel angular velocity is determined (step C6). In this step C6, if the soft mode is selected as the roll control mode by the roll control selection switch 30, the fifth
The map shown in FIG. 6 is selected when the auto mode is selected as the roll control mode, and the map shown in FIG. 7 is selected when the sport mode is selected as the roll control mode.

Then, the air supply/exhaust time and damping force as shown in FIG. 9 are selected corresponding to the control level TCH of each map. Then, the four-wheel independent air supply and exhaust times TC8 and TCE are corrected and calculated by an air supply and exhaust air supply correction routine, the details of which will be described later with reference to FIG. 16 (step C7). Next, it is determined whether control is being set (step C8). Since roll control has not yet been started, it is determined as rNOJ and the process proceeds to step C9. In this step C9, it is determined whether the air supply/exhaust flag SEP is set. If the supply and exhaust flag SEP is set in the above-mentioned supply and exhaust correction routine (step C7), the control is set;
The supply/exhaust timer is set to T-0 (step CIO, C11
). Then, the process proceeds to steps C1 and C2, where it is determined whether the differential pressure is being maintained, that is, whether there is a pressure difference (differential pressure) between the air spring chambers 3 of the left and right suspension units. If there is a differential pressure, change the front and rear exhaust direction, valve 28
．． 32 is turned off, so that air exhausted from the front or rear is discharged into the low pressure reserve tank 15b. This is because the air discharged from the air spring chamber 3 of the suspension unit is dry, so there is no need to dry it with the dryer 13 when using it again. Next, in the supply/exhaust correction routine of step C7, it is determined whether the supply air coefficient KS-3 is set (step C14), and if it is not set (that is, KS-1), the supply air flow rate control valve 19 is turned on to increase the air flow rate (step white 15). That is, as shown in FIG. 16, KS-1 is a case where the control level TCH is determined from the vehicle speed-steering wheel angular velocity map, so the air flow rate is increased to perform quick roll control.

Next, the front air supply valve 20.24 is turned on (step C16). Then, the control unit 36 detects the direction of the horizontal acceleration G (step C1
7). In other words, it is determined whether the direction of the left-right acceleration G is positive or negative. Here, if the acceleration G is positive, it is determined that the acceleration G indicates a right turn in the direction of travel, that is, a left turn. On the other hand, if the acceleration G is negative, it is determined that the acceleration G is from the direction of travel and the vehicle is turning to the left, that is, turning to the right. Therefore, when it is determined that the acceleration G is to the right (left turning), the front and rear left solenoid pulps 22
and 26 are turned on to prevent the left vehicle height from rising (step Cl8). On the other hand, when it is determined that the acceleration G is to the left (turning right), the front and rear right solenoid valves 23 and 27 are turned on to prevent the vehicle height on the right side from rising (step C1
9).

Next, the swing back flag is reset, the differential pressure holding flag is set, the duty timer TD starts its timing operation, the duty counter Tn starts its timing operation, and the duty time counter Tmn starts its timing operation. The operation is started (steps C20 to C24). Thereafter, the process returns to step C1. Then, the process proceeds to step C8 through the processes of steps 01 to C7. This step C8
As a result of the determination, since control is being set, it is determined to be rYEsJ, and the process proceeds to step C25. And this step C
At 25, timer T is updated. Roll control is continued until the count value of the timer T becomes equal to or greater than the air supply time 708 or until the count value of the timer T becomes equal to or greater than the exhaust time TCP. By the way, the count value of timer T is air supply time 70.
When it is 8 or more, it is determined that rYEsJ is reached in step C26, the flow control valve 19 is turned off, the air supply solenoid valve 20.24 is turned off, and the air supply operation is stopped (
Steps C27, C28). Furthermore, when the count value of the timer T becomes equal to or greater than the exhaust time TCE, rYEs is emitted in step C29.
J is determined, the exhaust direction switching valves 28 and 32 are turned on, and the exhaust operation is stopped (step C30). Then, the acceleration G in the left and right direction is stored in the memory Mg, and [
If timer T≧T C3J, the control is reset and roll control is stopped and held (step C3).
2, 33). The above processing was described for the case where the steering wheel was turned suddenly.
Even in the case of J, if rGXGJ is positive (step C34), the G sensor map in FIG. 8 is referred to and the control level TCG is determined. Control takes place. The supply/exhaust time and damping force corresponding to this control level TCG are the first
It can be found from Figure 0.

By the way, when rGXGJ is negative, that is, when the steering wheel is on the return side, the map in FIG. Then, it is determined whether the handle angular velocity on the return side is eH; zenM (step C37). If rYESJ is determined in this step C37, the temporal change G in the left and right acceleration G is 0.
It is determined whether the weight is 6g or more (step C38). If rYESJ is determined in steps C37 and C38, it is determined whether the reversal flag is set (step C39). Here, when this step S39 is reached for the first time, the rewind flag is not set, so it is determined that rNOJ, the rewind flag is set, and the rewind timer TY is set to "0" (step C40). , C41). When it is determined that the acceleration G is to the left (turning right), the front and rear right solenoid valves 23 and 27 are turned off, and the acceleration G
When it is determined that the vehicle is turning to the right (left turn), the front and rear left solenoid valves 22, 26 are turned off, and the air spring chambers 3 of the left and right suspension units are communicated with each other (steps C42 to C44). Then, the front and rear intake valves 20.24 are turned off, the exhaust direction switching valve 28.32 is turned off, the control level is set to CL-0, the control is reset, and the process returns to step C1 (steps C45 to C49). And the above step C
37 and C38, it is determined to be rYEsJ, and step C
If the process advances to step C39, the rewind flag has already been set, so the process proceeds to the rewind routine starting from 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 and C51). In this step C51, rN
If it is determined that the
When the count value of V becomes 0.25 seconds or more, it is determined again whether the count value of timer TY is 2.25 seconds or more (step C52). Therefore, if the count value of timer TV is 0.25 seconds or more and smaller than 2.25, step C52
Then, it is determined that the result is rNOJ, and the process proceeds to step 53 and subsequent steps. In the determination at step C53, the left and right acceleration G
When it is determined that the acceleration G in the left-right direction is right (left turning), the front and rear right solenoid valves 23,27 are turned on, and the acceleration G in the left-right direction is turned to the left (turning left).
If it is determined that the vehicle is turning to the right (right turn), the front and rear left solenoid valves 22 and 26 are turned on. Furthermore, the exhaust direction switching valves 28, 32 are turned on (steps C53 to C55). Through the process of step C54, the spring constants of the front and rear right suspension units can be increased. In this way, when the handle angular velocity eH is equal to or greater than the threshold shown in FIG. 6 and the time elapsed time of the acceleration G in the left and right direction on the return side becomes equal to or greater than 0.6 g, communication between the left and right treasure chests is immediately opened; After 0.25 seconds, the left and right communication is closed for 2 seconds. And 2.25
After seconds have elapsed, rYEsJ is determined in step C57, the reversing flag is reset, and the reversing process is completed. (Step C57). Thereafter, the processing from step C42 onwards is performed, and then the processing from step C1 onwards is performed.

By the way, in step C37 or C38 above, rNO
If it is determined to be J, it is determined whether the reversing flag is set (step C58), and if it is set, the process proceeds to step C50 and subsequent steps.

On the other hand, if the yuri return refrag is not set,
Is the acceleration G in the left and right direction at the dead band level, that is, r
It is determined whether G:=Go J (step C59),
If the differential pressure is at the dead zone level, it is determined whether the differential pressure is being maintained (step C60), and if the differential pressure is being maintained, the process proceeds to step C61 and subsequent steps to cancel the differential pressure by duty control. .

The processing of the duty control routine performed from step C61 onwards will be described below. First, it is determined whether the duty control number Tn is 3 or more (step C61
). Then, it is determined whether the duty timer Td is greater than or equal to TlIn (step C62). Here, "N
O”, the duty timer Td is incremented (
In step C63), processing to make the damping force even harder is performed in steps C64 to C67.

By the way, if the determination in step C6 is rYESJ, that is, the duty timer Td reaches T■n, the process proceeds to step C68 and subsequent steps, and the process of intermittently communicating between the left and right air spring chambers 3 is started. be done. First, the direction of the horizontal acceleration G stored in step C31 is determined (step C68). If the direction of the left-right acceleration G is to the left, it is determined that the front and rear right solenoid valves 23, 27 are turned off, and if they are turned off, they are turned on (step C70).
. On the other hand, if it is on, it is turned off, the duty counter Tn is incremented, and the duty timer Tl1n is set to T.
mn+Tm is set and the process returns to step C1 (steps C71 to C73). And 111
The process of step C70 or C71 will be performed again after a second. When this process is performed three times, the determination in step C61 is rYEsJ, the front and rear exhaust direction switching valves 28.32 are turned off, the differential pressure holding flag is reset, and the control level is set to CL-0. , the series of duty control is completed.

By the way, if it is determined in step C6g that it is on the "right side", the same process as in steps C69 to C71 is performed on the solenoid valves 22 and 26. When this process is also performed three times, the process proceeds to step C74, and the series of processes ends.

Next, the above-described air supply/exhaust correction routine of step A3 will be explained in detail with reference to FIG. First, the control level CL is initially set to "0" (step DI). Next, the internal pressure of the rear suspension units R8I and R82 is detected based on a signal from the pressure sensor 45 (step D2). Next, the control level TCG obtained from the G sensor map in FIG. 8 or the control level TCH obtained from the steering wheel angular velocity-vehicle speed map in FIGS. 5 to 7 is compared with the control level CL (steps D3 and D4). ), if a control level TCG or TCH greater than the control level CL is determined, it is stored in the control level CL (steps D8 and DL7).

On the other hand, if it is determined that either the control level TCG or TCH is smaller than the control level CL,
The air supply/exhaust flag SEP is reset, the damping force switching position is reset, and the control levels TCG and TCH are set to the dead zone level "1" (steps D5 to D'7).

By the way, after the control level TCG is set to the control level CL in step D8, r T C8≦1.”
If so, the air supply coefficient Ks is set to "3" (step D10). On the other hand, if rTCH>IJ, the air supply coefficient Ks is set to "1" (step D11)
. Further, after the control level TCII is set to the control level CL in step D17, the air supply coefficient Ks is set to "
1'' is set (step D11).

Then, after the above step DIO or Dll, the supply and exhaust flag SEP is set (step D12), and the first
Air supply and exhaust are performed by the roll control routine shown in FIG.

Then, it is determined whether the cross-country determination routine set by the cross-country determination routine shown in FIG. 12 is set (step D1B).

In this step D1B, if it is determined that the cross-country determination is set, the control level TCG is set to "2".
” (Step D14), and if the control level is “2”, the air supply/exhaust flag SEP is reset and the control level TCG is set to the dead zone level “1” (Steps D15 and D16). . In other words, as shown in FIG.
'', the roll control would normally be performed during the supply and exhaust time of 150a+s, but the supply and exhaust time is set to "0" and the roll control is not performed. That is, when a cross-country determination is made, such as when driving on a rough road, the width of the dead zone of the G sensor is widened to prevent erroneous operation of roll control on a rough road.

By the way, step D7. D13. ．． D14゜D1
After the process in step 6 is completed, the control level TC determined
With reference to FIG. 9 or 10 from H or TCG, the basic air supply/exhaust time Tc corresponding to the control level TC)I and TCG is determined (step D18). Next, the internal pressure (rear internal pressure) of the rear suspension units RSI and RS2 is detected by the pressure sensor 45, and the front internal pressure is estimated from this rear internal pressure by referring to the front internal pressure-rear internal pressure characteristic diagram shown in FIG. . Based on the front internal pressure estimated in this way and the rear internal pressure obtained from the pressure sensor 45, the intake air exhaust correction coefficient characteristic diagram in FIG. And the rear side exhaust correction coefficient PE is determined (step D19). In Fig. 18, when the internal pressure of the suspension is high, the air supply time is required to be longer than when the internal pressure is low, so the correction coefficient PS is adjusted to the internal pressure PO. When the internal pressure of the suspension is high, the evacuation time is shorter than when the internal pressure is low, so the correction coefficient PE is inversely proportional to the internal pressure PO. There is.

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

Next, the already determined air supply basic time Tc 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 TC8 (step D23). Furthermore, the already determined basic exhaust time Tc is multiplied by the exhaust correction coefficient PE and the initial coefficient "FK" to determine the corrected exhaust time TC3 (step D24).

Next, with reference to FIGS. 9 and 10, the control level TC
The damping force switching position corresponding to G and TCll is determined, and the position is set to the damping force target value DST (step 5).
25). Next, when cross-country determination is set, if the damping force target value DST is hard, it is changed to medium (steps D26 to D28).

Next, the damping force switching routine (step A4) will be explained with reference to FIGS. 19 and 20. First, the damping force target value DST is the damping force value MD set manually.
It is determined whether the damping force is larger than ST (step E1), and if it is larger, the damping force is switched so that the damping force target value DST becomes equal to the damping force current value DDST, and the timer TDS is reset (steps E2 to E4). ). Then, when the damping force target value DST becomes equal to the damping force current value DDST, the timer TDS is counted until the timer TD'3 counts 2 seconds (steps E5 and E6).
). Then, when 2 seconds are counted by timer TDS,
Timer TDS is reset (step E7). If the differential pressure is not maintained, the manually set damping force value MDST is set to the current damping force value DDST (
Step E9).

On the other hand, if it is determined in step E8 that the differential pressure is being maintained, that is, that the roll control is being maintained, the damping force is lowered by one step in steps EIO to E12 of processing ash. That is, if the current damping force value DDST is hard, the current damping force value DDST is set to medium, and if the current damping force value DDST is not hard, the current damping force value DDST is set to soft.

As described above, if the damping force target value DST is set to a higher damping force than the manually set damping force MDST, as shown in the m20 diagram, after switching to the higher damping force for 2 seconds, roll control is performed. During the hold period, the damping force is reduced by one step.

[Effects of the Invention] As detailed above, according to the present invention, if the target damping force of the suspension is set to hard when a rough road is determined, the target damping force of the suspension is set to medium. It is possible to provide a vehicle suspension device that can improve ride comfort and road followability during driving.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a vehicle suspension device according to an embodiment of the present invention, FIG. 2 is a diagram showing the driving and non-driving states of the three-way valve, and FIG. 3 is a diagram showing the driving and non-driving states of the solenoid valve.
Figure 4 is a diagram showing the drive and non-drive states of the intake air flow control valve. Figure 5 is a map of vehicle speed vs. steering wheel angular velocity in 5OFT mode. Figure 6 is a map of vehicle speed vs. steering wheel angular velocity in AUTO mode. Map, Figure 7 is 5
Vehicle speed-steering wheel angular velocity map in PORT mode,
Figure 8 is a G sensor map, Figure g749 is a diagram showing the relationship between the control level and air supply and exhaust time based on the vehicle speed-steering wheel angular velocity map, Figure 10 is a diagram showing the relationship between the control level and air supply and exhaust time based on the G sensor map, and Figure 11. 12 is a detailed flowchart showing the operation of an embodiment of the present invention, FIG. 12 is a detailed flowchart showing the cross-country judgment routine, FIG. 13 is a diagram showing the G sensor map during normal time and cross-country judgment, and FIG. 14 is a diagram showing the G sensor map during normal and cross-country judgment. Figure 15 is a detailed flowchart of the roll control routine, Figure 16 is a detailed flowchart of the air supply and exhaust correction routine, and Figure 17 is the rear internal pressure vs. front internal pressure characteristic. 18 is a characteristic diagram of air suspension internal pressure Po and air supply/exhaust correction coefficients, FIG. 19 is a detailed flowchart of the damping force switching routine, and FIG. 20 is a diagram showing changes in damping force over time. 15a...High pressure reserve tank, 15b...Low pressure reserve tank, 19...Air supply flow rate control valve, 22゜23.26.27...Solenoid valve, 36...
Control unit, 45...pressure sensor. Applicant's agent Patent attorney Takehiko Suzue (A)
(B) Figure 2 (A') (B) Figure 3 Figure 4 5 OFT7. , F'AO
TO MA NOFU. Figure 5 Figure 6 Gt Nsamanov. Figure 7 Figure 8 Figure 9 Figure 10 Figure 11

Claims (1)

[Claims] A fluid spring chamber provided for each suspension unit capable of switching the damping force that supports each wheel into three stages (hard, medium, soft), a damping force switching means for switching the damping force, and each of the above-mentioned fluid springs. a fluid supply means for supplying fluid to the chambers through respective supply valve means; a fluid discharge means for discharging fluid from each of the fluid spring chambers through respective discharge valve means; and a fluid spring chamber of the left suspension unit. a communication means for communicating the fluid spring chamber of the right suspension unit with each other via a communication control valve; a roll amount detection means for detecting the roll amount of the vehicle body; the fluid supply means according to the roll amount; a memory means for storing the drive time of the fluid discharge means; a rough road travel determination means for determining whether the vehicle is traveling on a rough road; and a target for the suspension when the rough road travel determination means detects that the vehicle is traveling on a rough road. A switching means switches the damping force to medium when the damping force is set to hard, and when a factor causing roll is detected, a set amount of fluid is supplied to the fluid spring chamber of the suspension unit on the compression side for the above driving time, and the damping force is also set to the medium. A suspension device for a vehicle, comprising roll control means for driving the supply valve means and the discharge valve means so as to discharge a set amount of fluid from a fluid spring chamber of a side suspension unit.