JPS6164512A - Electronic control suspension device - Google Patents

Abstract

PURPOSE:To prevent an amount of control from being short even at rapid acceleration and at rapid damping by variably setting an amount of suspension control corresponding to the magnitude of a longitudinal acceleration of a vehicle detected by an acceleration sensor. CONSTITUTION: An acceleration sensor 36 serving as a vehicle body sensor is adapted to detect changes in vehicle attitude such as pitching, rolling, and yawing on a vehicle spring. When a longitudinal acceleration detected by the sensor 36 is more than a prescribed value, an air supply solenoid valve 19, and solenoid valves 25, 26 are switched to for a control time T being controlled by a roll unit 34. Hereby, compressed air from a reservoir task 15a is fed to the main air spring chamber 3 of front suspension units FS1 and FS2 via the valves 19, 20, and 21, whereby a vehicle height at the front is lifted in response to an amount of attitude change in a noze dive.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention is directed to, for example, the sinking of the front part of a car body (nose dive) and the drop of the rear part of the car body (sufauto) that occur when longitudinal acceleration is applied to the car body. The present invention relates to an electronically controlled suspension device that suppresses.

[Technical background of the invention and its problems]

Generally, when a forward acceleration is applied to the vehicle body when starting or accelerating a vehicle, a phenomenon occurs in which the height of the rear portion of the vehicle body decreases and the front portion of the vehicle lifts up.

On the other hand, if rearward acceleration is applied to the vehicle during braking or stopping, a nose dive phenomenon occurs in which the front of the vehicle sinks and the height of the rear of the vehicle rises. Therefore, an electronically controlled suspension device is being considered to electronically suppress such a null quote phenomenon and a nose dive phenomenon.

In other words, this electronically controlled suspension system controls the spring reaction of the suspension unit in the direction in which the vehicle body sinks when it predicts that a change in attitude will occur in the vehicle body based on the longitudinal acceleration applied to the vehicle body or the time derivative of that acceleration. This increases the force and reduces the spring reaction force of the suspension unit in the direction of lifting, absorbing the above change in attitude and keeping the vehicle level. Here, the amount of increase and amount of decrease of the spring reaction force are set in advance as predetermined control amounts.

Thereafter, when the factor (for example, acceleration) that causes the attitude change as described above is reduced, the spring reaction force is controlled in a predetermined manner in the opposite direction to that described above, and the attitude control state is released.

However, in this type of control suspension system that always raises and lowers the suspension spring reaction force by a predetermined control amount, for example, if the predetermined control amount is set in accordance with the attitude control performed during normal acceleration and braking, A problem arises in that large changes in posture that occur during sudden braking cannot be sufficiently suppressed.

[Purpose of the invention]

This invention was made in view of the problems mentioned above.
For example, even when large posture changes occur during sudden acceleration or sudden braking, the control amount will not be insufficient.
It is an object of the present invention to provide a weight control suspension device that can sufficiently suppress the above-mentioned attitude change.

[Summary of the invention]

That is, the electronically controlled suspension device according to the present invention includes a suspension unit that can adjust the spring reaction force for each wheel, and controls the spring reaction force in accordance with the magnitude of the acceleration in the predominant direction of the vehicle body detected by the acceleration sensor. This system is designed to have a variable amount of control so that appropriate posture control is always performed.

[Funny example of invention]

An electronically controlled suspension device according to an embodiment of the present invention will be described below with reference to the inner surface. In FIG. 1, air suspension units FSI, FS2. R8
Since the I and R82 have almost the same structure, below, the near suspension unit will be referred to by the code S, except when specifically explaining the front and rear suspension units.
The explanation will be made using the following figure, and only the parts necessary for vehicle height control will be illustrated and explained.

In other words, the air suspension unit S incorporates a shock absorber I, and this shock absorber I is slidably inserted into a cylinder attached to the front or rear wheel side. The cylinder is equipped with a piston and moves up and down with respect to the piston rod 2 in response to the up and down movement of the wheel, so that shock can be effectively absorbed and the damping force changes in accordance with the stroke of the wheel.

Incidentally, a main air spring chamber 3 that also serves as a vehicle height adjustment fluid chamber is disposed coaxially with the piston rod 2 in the upper part of the shock absorber 1, and a part of this main air spring chamber is formed by a bellows 4. Therefore, the piston rod 2 can be moved up and down by supplying and discharging air to the main air spring chamber 3 through the passage 2a provided in the piston rod 2.

The outer wall of the shock absorber 1 is provided with a spring receiver 5a facing upward, and the outer wall of the main air spring chamber 3 is provided with a spring receiver 5b facing downward.
A coil spring 6 is loaded between these spring receivers 5a and 5b.

Thus, 11 is a compressor. This compressor 11 compresses the atmospheric air sent from the air cleaner 12 and supplies it to the dryer I3, and the compressed air dried by silica gel etc. in the dryer 13 is transferred to the high pressure in the reserve tank Z5 via the check valve I4. It is stored in the side reserve tank 15a. This reserve tank 15 is provided with a low pressure side reserve tank 15b. A compressor I6 driven by a compressor relay 17 is provided between the reserve tanks 15m and 15b. In addition, the low pressure side reserve tank 15
Pressure switch 1 that turns on when the pressure of b becomes above atmospheric pressure
8 is provided. When the pressure switch I8 is turned on, the compressor relay 17 is driven.

As a result, the reserve tank 15b is always kept below atmospheric pressure.

The route through which compressed air is supplied from the high-pressure III reserve tank 15a to the suspension unit S is indicated by a solid arrow. That is, the compressed air from the reserve tank 15a is transferred to the air supply solenoid valve 19. Supply air flow rate control barrel valve 20 consisting of 30,000 self-valves to be described later. Check valve 21, front Ishikawa solenoid valve 2
It is sent to the front Ishikawa suspension unit FS through the solenoid valve 23 for the 2° front valve and to the suspension unit 1-FS1 for the 2° front valve.

Similarly, the pressure Md air from the reserve tank 15a is supplied to an air supply solenoid valve 19, an air supply flow rate control valve 20 consisting of a three-way valve, which will be described later. Check valve 24. Solenoid valve useful for rear 25. The rear suspension unit 1 is connected to the rear suspension unit 1 through the rear pressure solenoid valve 26.
-R82, sent to suspension unit R8I for rear pressure. On the other hand, the exhaust route from the suspension unit S is indicated by a broken line arrow. In other words, the exhaust from the suspension units FS 1, FS 2 is controlled by the solenoid valves 22, 23, the exhaust flow rate control valve 27, the exhaust direction switching valve 28, and so on. It is sent to the low pressure side reserve tank 15b via the residual pressure valve 29. Furthermore, suspension unit FS1. Exhaust from FS2 is solenoid valve 22
．． 23, exhaust flow rate control valve 27, exhaust direction switching valve 28. Dryer 13. It is released to the atmosphere via the exhaust solenoid valve 3o and the air cleaner 12. The exhaust from the suspension units R8I and R82 is sent to the low pressure reserve tank 15b via the solenoid valves 25, 26, exhaust N, quantity control valve 27, exhaust direction switching valve 28, and residual pressure valve 29. When the pressure in the reserve tank I5b is lower than the pressure in the main air spring chamber 3, the residual pressure valve 29 is opened, and when the pressure in the reserve tank 15b is greater than the pressure in the main air spring chamber 3, the residual pressure valve 29 is closed. Furthermore, the exhaust from the suspension units Re 1 and rls2 is released to the atmosphere via the solenoid valves 25 and 26, the exhaust flow control valve 27, the exhaust direction switching valve 28, the dryer 13, the exhaust solenoid valve 30, and the air cleaner I2. be done.

Further, 31 is a vehicle height sensor, and this vehicle height sensor 31 is attached to the lower arm 32 of the front right suspension of the automobile to detect the front vehicle height of the automobile, and the front vehicle height sensor 31F is attached to the lower arm 32 of the front right suspension of the automobile, and the front vehicle height sensor 31F is attached to the lower arm 32 of the front right suspension of the automobile. The rear vehicle height sensor 31R is attached to a lateral rod 33 and detects the rear vehicle height of the vehicle, and detection signals are sent from these vehicle height sensors 31F and 31R to a control unit 34 as a vehicle height adjustment control section. is supplied.

Each sensor 31F in the vehicle height sensor 31.

31T't is adapted to detect the distance from the normal vehicle height level and the low vehicle height level or high vehicle height level, respectively.

Further, the speedometer has a built-in vehicle speed sensor 35, which detects the vehicle speed and supplies the detected signal to the control unit 34.

Further, an acceleration sensor 36 is provided as a vehicle body posture sensor that detects changes in the posture of the vehicle body. This acceleration sensor 36 is designed to detect changes in the pitch, roll, and yaw of the vehicle body posture due to the automobile spring. For example, when there is no acceleration, the weight is in a hanging state, and the light from the light emitting diode is passed through the shielding plate. The absence of acceleration is detected by the fact that the acceleration does not reach the photodiode.

Then, when acceleration acts forward and backward, left and right, or up and down,
The acceleration state of the vehicle body is detected by the tilting or movement of the weight.

Further, numeral 37 is an indicator that displays oil pressure, and the display of this indicator 37 is controlled by the control unit 34. A steering sensor 38 detects the rotational speed of the steering wheel 39, that is, the steering speed, and its detection signal is sent to the control unit 34.

Furthermore, 40 is an accelerator opening sensor (not shown) that detects the depression angle of the accelerator pedal of the engine;
The word is sent to the control unit 34 mentioned above. Further, 41 is a compressor relay for driving the compressor 11, and this combination 1/tube relay 41 is controlled by a control signal from the control unit 34. Furthermore, 42 is a pressure switch that is turned on when the pressure in the reserve tank 15a falls below a predetermined value, and its output signal is output to the control unit 34.

That is, when the pressure in the reserve tank 15a becomes below a predetermined value, the pressure switch 34 is turned on, and the compressor relay 41 is driven by the aill H of the control unit 34. As a result, the compressor 11 is driven to feed compressed air into the reserve tank 15a, and the pressure inside the reserve tank 15a is made to be equal to or higher than a predetermined value. Further, 43 is a gear position sensor that detects the shift position of a transmission (not shown), and its detection signal is supplied to the control unit 34. In addition, the above solenoid valve 19
．． 22, 23, 25, 26.30 and valves 20, 27
．． Opening/closing control of 28 is performed by control signals from the control unit 34.

In addition, the solenoid valves 22, 23, 25° 26 and valves 20, 27, 28 are three-way valves, and the two
The two states are shown in Figure 2. FIG. 2(A) shows a state in which the three-way valve is driven, and in this state compressed air moves along the path indicated by arrow A. On the other hand, Figure 2 (
B) shows a state in which the three-way valve is not driven,
In this state, compressed air moves along the path indicated by arrow B.

The solenoid valves 19 and 30 are two-way valves, and their two states are shown in FIG. Third
Figure (A) shows a state in which the solenoid valve is driven, and in this state compressed air moves in the direction of arrow C.

On the other hand, when the solenoid valve is not driven, the situation is as shown in FIG. 3(B), and in this case, there is no flow of compressed air.

Next, the operation of the present invention configured as described above will be explained. First, this device is equipped with a vehicle height adjustment function and an attitude control function, and the operation will be explained below with reference to Fig. 4. First, I will explain the vehicle height adjustment function.This device can set the target vehicle height in three stages: "high", "medium", and "low".First, the front vehicle height sensor 3
If the front vehicle height detected by 1F is lower than the target sub-height, the front vehicle height is raised. In this case, as shown in FIG. 4, the control unit 34 controls the air supply solenoid valve 19. Air supply flow control valve 20. Solenoid valve 25. Solenoid valve 26 is activated. As a result, the compressed air from the reserve tank 15a is transferred to the air supply solenoid valve 19° through the narrow pipe I.
7. Air supply flow control valve 20. Check valve 21. It is sent to the front suspension units FSI and FS2 via the solenoid valve 22 (solenoid valve 3).

This raises the front vehicle height.

On the other hand, if the rear vehicle height detected by the rear vehicle height sensor 31H is lower than the target vehicle height, the rear vehicle height is raised. In this case, the air supply solenoid valve 19 is controlled by the control unit 34 as shown in FIG. Air supply flow control valve 20. Solenoid valve 22. Solenoid valve 23 is driven. This allows the compressed air from the reserve tank 1.5a to flow through the air supply solenoid valve 1.
9. Small diameter piping, air supply flow control valve 20. Check valve 24. Rear suspension ventilation unit R8I via solenoid valve 25 (solenoid valve 26)
, sent to R82. This raises the rear vehicle height.

Next, if both the front and rear vehicle heights are lower than the target vehicle height, the front and rear vehicle heights are raised. In this case, the supply mesolenoid valve 19 and the supply air flow rate control valve 20 are driven under the control of the control unit 34.

As a result, the compressed air in the reserve tank 15a is transferred to the air supply solenoid valve 19. Piping, supply air flow control valve 20
．． Check valve 21. Suspension unit FS via solenoid valve 22 (solenoid valve 23)
I, FS2ζ is sent and the check valve 24. It is sent to the suspension units R8I and R82 via the solenoid valve 25 (solenoid valve 26). As a result, the front and rear vehicle heights are raised.

Next, if the front vehicle height detected by the front vehicle height sensor 31F is higher than the target vehicle height, the front vehicle height is lowered. In this case, the exhaust solenoid valve 30. Exhaust flow control valve 27, solenoid valve 22. Solenoid valve 23. The exhaust direction switching valve 28 is turned on. As a result, the suspension unit F S 1°F
Air is discharged from the main air spring chamber 3 of S2 through a solenoid valve 22 (solenoid valve 23).

Exhaust flow control valve 27. Small diameter piping M, exhaust direction switching valve 28. Dryer 13. Exhaust solenoid valve 30. It is released to the atmosphere via air cleaner I2. Here, the dryer 13 is regenerated by passing exhaust gas through the dryer 13 in the direction of the dashed arrow.

If the rear vehicle height detected by the rear vehicle height sensor 31R is higher than the target vehicle height, the rear vehicle height is lowered.

In this case, the exhaust solenoid valve 30. Exhaust flow control valve 27. Solenoid valve 25. Solenoid valve 26 is turned on. As a result, the air discharged from the main air spring chambers 3 of the suspension units R8I and R82 is transferred to the solenoid valve 25 (solenoid valve 26), the exhaust flow control valve 21. Small diameter piping M, exhaust direction switching valve 28. Dryer 13. Exhaust solenoid valve 30
．． It is released to the atmosphere via the air cleaner 12. Here, the dryer I3 is regenerated by passing exhaust gas through the dryer I3 in the direction of the dashed arrow.

Next, if the front and rear vehicle heights are respectively higher than the target vehicle height, the front and rear suspension units FSI, FS2, and R8I.

Exhaust from R82. In this case, the exhaust solenoid valve 30° exhaust flow control valve 27° solenoid valve 22. Solenoid valve 23° Solenoid valve 25.
Solenoid valve 26° exhaust direction switching valve 28 is turned on. Therefore, the air discharged from the main air spring chamber 3 of each suspension unit is transferred to the solenoid valve 22.
．． 113.25.26. Exhaust flow rate control valve 27, piping M, exhaust direction switching valve 28. Dryer 13. Exhaust solenoid valve 30. It is released to the atmosphere via the air cleaner 12. This lowers the front and rear vehicle heights.

Here, the dryer 13 is regenerated by passing exhaust gas through the dryer 13 in the direction of the dashed arrow.

Next, vehicle body posture control when the steering wheel is steered to the right will be explained. In this case, the vehicle height on the left side decreases and the vehicle height on the right side increases, so air is supplied to the left suspension unit and exhausted from the right suspension unit. That is, when the steering sensor 38 detects that the steering wheel is being steered to the right by more than the required foot angle, the control signal from the control unit 34 causes the air supply solenoid valve 19 to be turned. Solenoid valve 22 and solenoid valve 25 are turned on for a certain period of time. The compressed air sent from the reserve tank 15a is supplied through the air supply solenoid valve 19 and the air supply flow rate control valve 20. Air is supplied to the front left suspension unit FSI through a check valve 21° and a solenoid valve 23.

At the same time, compressed air from the 15m reserve tank is supplied to the air supply solenoid valve Z9. Air supply flow control valve 20. Check valve 24. It is sent to the rear left suspension engine unit R8I via the solenoid valve 26. On the other hand, the compressed air discharged from the main air spring chamber 3 of the front right suspension unit FS2 is supplied to the solenoid valve 22. Exhaust flow control valve 27. Exhaust direction switching valve 28. It is discharged to the reserve tank 15b via the residual pressure valve 29. Furthermore, the rear right suspension unit R
The compressed air discharged from the main air spring chamber 3 of 82 is supplied to the solenoid valve 25. Exhaust flow control valve 27. Exhaust direction switching valve 28. Reserve tank 1 via residual pressure valve 29
5b. In this way, the vehicle body can be kept level when the steering wheel is turned to the right. and,
Air supply solenoid valve 1 after the valve is opened for a certain period of time
9 is closed and that state is maintained. When the steering wheel is turned to the right, the air supply solenoid valve 19.
Solenoid valve 22. The solenoid valve 25 is turned off and attitude control is released. Here, main air spring chamber 3
When the air is exhausted, it is sent to the reserve tank 15b via the residual pressure valve 29, so the main air spring 3
The pressure of the reserve tank 15 is kept below atmospheric pressure.
The pressure will never drop below b. Therefore, it is possible to prevent the diaphragm constituting the main air spring chamber 3 from being caught between the cylinder and the shell due to an excessively large displacement for some reason and the internal pressure inside the main air spring chamber 3 dropping too much. can.

Next, vehicle body attitude control when the steering wheel is steered to the left will be explained. In this case, the vehicle height on the right side decreases and the vehicle height on the left side increases, so air is supplied to the right suspension unit and exhausted from the left suspension unit. In other words, when the steering sensor 38 detects that the steering wheel is being steered to the left by more than the required foot angle, a control signal from the control unit 34 controls the intake solenoid valve! 9. Solenoid valve 23, solenoid valve 26
is turned on for only one moment. In other words, reserve tank J
Compressed air sent from 551 is supplied to air supply solenoid valve 1
9° Air supply flow control valve 20. Air is supplied to the front right suspension unit FS2 through a check valve 21° and a solenoid valve 22.

At the same time, the compressed air from the reserve tank 15a is supplied to the air supply solenoid valve 19. Air supply flow control valve 20. Check valve 24. It is sent to the rear right suspension unit R82 via the solenoid valve 25. On the other hand, the compressed air discharged from the main air spring 3 of the front left suspension unit FSI is supplied to the solenoid valve 23. Exhaust flow rate side valve 27. Exhaust direction switching valve 28. It is discharged to the reserve tank 15b via the residual pressure valve 29. Furthermore, the compressed air discharged from the main air spring chamber 3 of the rear left suspension unit R8I is supplied to the solenoid valve 26. Exhaust flow control valve 27. Exhaust direction switching valve 28. The remaining pressure is discharged to the reserve tank ISB via the residual pressure valve 29. This allows the vehicle to remain level when the steering wheel is turned to the left. After the valve is opened for a certain period of time, the air supply solenoid valve 19 is closed and this state is maintained. When the steering wheel is turned to the left, the air supply solenoid valve 19. Solenoid valve 23. solenoid valve 2
6 is turned off and attitude control is released. Here, when air is discharged from the main air spring 3, the residual pressure valve 2
9 to the reserve tank I5b, the pressure in the main air spring chamber 3 will never drop below the pressure in the reserve tank 15b, which is kept below atmospheric pressure. Therefore, it is possible to prevent the diaphragm constituting the main air spring chamber 3 from being caught between the cylinder and the shell due to an excessively large displacement for some reason and the internal pressure in the main air spring chamber 3 dropping too much. can.

Next, we will explain attitude control that prevents nose dive, where the front vehicle height lowers when the brake is stepped on. When you step on the brakes, the front vehicle height lowers and the rear vehicle height increases, allowing air to be supplied to the front suspension unit and exhausted from the rear suspension unit. If the acceleration in the longitudinal direction detected by the acceleration sensor 36 is greater than or equal to a predetermined value, the control unit 3
4 controls the air supply solenoid valve 19. Solenoid valve 25. The solenoid valve 26 is turned on for a control time T determined by a map shown in FIG. 6, which will be described later. Therefore, the compressed air from the reserve tank 15a is transferred to the air supply solenoid valve 19. Air supply flow control valve 20. The air is sent to the main air spring chambers 3 of the front suspension units FS 1 and FS 2 via the check valve 21 . As a result, the front vehicle height is raised according to the amount of attitude change during nose dive. On the other hand, the compressed air discharged from the main air spring chamber 3 of the rear suspension units R81 and R82 is supplied to the solenoid valve 25. Solenoid valve 26.
Exhaust flow control valve 27. Exhaust direction switching valve 28.
It is discharged to the reserve tank 15b via the residual pressure valve 29. As a result, the rear vehicle height is lowered in accordance with the amount of attitude change ζ caused by the nose dive, and the vehicle body is kept level. After the valve is turned on for the control time T, the air supply solenoid valve 19. Solenoid valve 25. Solenoid valve 26 is turned off. Next, when the nose dive by depressing the brake is completed, the control unit 3
4 controls the air supply solenoid valve 19. Solenoid valve 22. Solenoid valve 23 is turned on. For this reason, the front suspension unit) F81, F
The compressed air in the main air spring chamber 3 of S2 is supplied to the solenoid valve 2.
2. Solenoid valve 23. Exhaust flow control valve 27.
Exhaust direction switching valve 28. It is discharged to the reserve tank 15b via the residual pressure valve 29. On the other hand, reserve tank 1
5m of compressed air is supplied through the air supply solenoid valve 19 and the air supply flow rate control valve 20. Check valve 24. Solenoid valve 25. The air is sent to the main air spring chamber 3 of the rear suspension units R8I and R82 via the solenoid valve 26.

As a result, the attitude of the vehicle body is returned to its original state. Also in this case, the residual pressure valve 29 is provided to prevent the internal pressure of the main air spring chamber 3 from dropping too much during exhaust.

Next, a description will be given of vehicle body posture control that prevents the front vehicle height from rising automatically when the accelerator is depressed when the vehicle is started. When you step on the accelerator, the front vehicle height rises and the rear vehicle height decreases, allowing air to be exhausted from the front suspension unit and supplied to the rear suspension unit. Where is the longitudinal acceleration detected by the acceleration sensor 36? (7) When the accelerator opening detected by the accelerator opening sensor 40 is above a predetermined value, the control unit 34 (7) controls the air supply solenoid valve 1.
9. Solenoid valve 22. The solenoid valve 23 is turned on for a control time T determined by a map shown in FIG. 6, which will be described later. Therefore, the compressed air from the reserve tank 15a is supplied to the air supply solenoid valve 19, the air supply flow rate control valve 20. The air is sent to the main air spring chamber 3 of the rear suspension units R8I and R82 via the check valve 24.

As a result, the rear vehicle height is raised according to the amount of change in the stance of the SF auto. On the other hand, the compressed air discharged from the main air spring chambers 3 of the front suspension ventilation units 1-FS1 and FS2 is supplied to the solenoid valve 22. Solenoid valve 23. Exhaust flow control valve 27. Exhaust direction switching valve 28. It is discharged to the reserve tank 15h via the residual pressure valve 29. As a result, the front vehicle height is lowered according to the amount of change in attitude caused by the SF Auto, keeping the vehicle level.

After the valve is turned on for the control time T, the air supply valve 1/noid valve 19. Solenoid valve 23 is turned off.

When the auto mode due to depressing the accelerator is completed, the air supply solenoid valve 19 is controlled by the control unit 34. Solenoid valve 25. Solenoid valve 26 is turned on.

For this reason, the rear suspension unit R8I.

The compressed air in the main air spring chamber 3 of R82 is supplied to the solenoid valve 25. Solenoid valve 26. Exhaust flow control valve 27
．． It is discharged to the reserve tank tsb via the exhaust direction switching valve 28 and the residual pressure valve 29. On the other hand, the compressed air in the 15 m reserve tank is supplied to the air supply solenoid valve 19. Air supply flow control valve 20. Check valve 21. Solenoid valve 22. Front suspension ventilation unit FSI via solenoid valve 23.

It is sent to the main air spring chamber 3 of FS2. As a result, the attitude of the vehicle body is returned to its original state. In this case, the residual pressure valve 2
9 prevents the internal pressure of the main air spring chamber 3 from dropping too much during exhaustion.

Next, with reference to the flowchart shown in FIG. 5, an explanation will be given of the attitude control operation that performs anti-nose dive control or anti-splash auto control in accordance with the control time T set in accordance with the magnitude of the longitudinal acceleration applied to the vehicle body. do.

First, in step S1, the control unit 3
The map memory in 4 is reset and O cleared ('rM
= o) be done. Next, the process proceeds to step S2, where the detection signal vG of the vehicle body longitudinal direction acceleration G detected by the acceleration sensor 36 is supplied to the control unit 34 and read therein, and its time differential value vG is calculated and read. Then, the process proceeds to step S3, and the control time TP%, that is, the driving time of the solenoid valve is determined from the acceleration map vG shown in FIG. 6 created based on the time differential value vG of the acceleration detection signal calculated in step S2. It will be done. This control time TP is from t1 to t3 in FIG.
4. In other words, as the time differential value of acceleration +G increases to A - D, the control time T
P is also gradually set to be longer, from t to ts (5ee). After this, the process proceeds to step S4, where the control time T (=
Tp-TM) is calculated. Then, the process proceeds to step S5, where it is determined whether the control time T is greater than O or not. If the determination in step S5 is "NO", the process returns to step S2. That is, in this case, as shown in the map of FIG. 6, the time differential value of the acceleration applied to the vehicle body is very small, ie, O≦*G<A, so that no vehicle attitude control is performed. On the other hand, the above step S5
If it is determined that rYEsJ, that is, the time differential value of the acceleration shown in the map of FIG. 6 above, is A≦*G, and that an acceleration that causes a change in attitude of the vehicle body has been applied, the process proceeds to step S6. In step S6, the opening/closing control of the solenoid valve is performed based on the control time T. For example, if the acceleration read in step S2 is the rearward acceleration during braking, the fourth
Attitude control to prevent the nose dive, which has already been explained in the figure, is performed based on the control time T. In this case, for example, sudden braking may cause a large change in vehicle body posture.
Even so, the control amount adapted to the amount of change is obtained, so that the above-mentioned attitude change is reliably suppressed regardless of its magnitude.

Further, for example, if the acceleration read in step S2 is the forward acceleration at the time of starting or accelerating, the attitude control to prevent the suffocation already explained in FIG. 4 is performed based on the control time T. In this case, even if a large change in vehicle body attitude occurs due to sudden acceleration, for example, a control amount that is adapted to the amount of change will be obtained, so the above attitude change will be reliably suppressed regardless of its size. .

Then, when the process of step s6 is completed, step S
Proceed to step 7, the map memory is updated, and TP is set to TM. Thereafter, the process proceeds to step 884, where it is determined whether the detection signal v□ of the acceleration in the longitudinal direction of the vehicle body read in step s2 has fallen below a predetermined value. Here rNOJ.

That is, if it is determined that the acceleration that causes an attitude change is still being applied to the vehicle body, the processes of steps 82 to S7 are performed again, and the attitude control for the control time T is performed again. In this case, the second and subsequent attitude controls are performed for the control time 'r newly determined from the map in step s3.
This is performed based on the valve control time T, which is the difference between p and the previous control time TM. This prevents posture control from being performed more than the actual amount of posture change.

Then, in step S8, it is determined that rYEsJ, that is, the longitudinal acceleration applied to the vehicle body, has decreased to a value that does not cause a posture change, and step S9
Proceeding to step 86, posture return control is performed for a control time TM corresponding to the amount of posture control performed in the soldering iron control time T. In this case as well, the fourth
The return control of the nose dive or the auto in the figure is performed based on the control time TM. When the process in step s9 is completed and the attitude control of the nose dive or SF auto is canceled, the process proceeds to step 810, where the map memory TM is reset and cleared to 0 (TM=
O) To be done.

Similarly, the map for determining the valve control time TP in Figure i6 of the above embodiment includes the time differential value 9 of the acceleration detection signal vG.
Although a map based on G is used, for example, a map based on the detection signal vG itself or both (Vo+α*G: α is a constant) may also be used.

In the above embodiment, the return control means in step S9 is set to a value v proportional to the acceleration in step S8ζ.
Although this is performed when G reaches a required value or less, the above-mentioned return control may be performed, for example, when the number of posture displacements with respect to the basic fishing posture reaches a set value or less.

〔Effect of the invention〕

As described above, according to the present invention, the suspension control amount is variably set in accordance with the magnitude of the longitudinal acceleration of the vehicle body detected by the acceleration sensor, and appropriate posture control is always performed. Even during heavy braking and sudden braking, it is possible to sufficiently suppress even large posture changes without causing problems such as insufficient control amounts. Therefore, posture changes caused by longitudinal acceleration applied to the vehicle body are always effectively suppressed, regardless of their magnitude.

[Brief explanation of drawings]

FIG. 1 shows an electronically controlled suspension device according to the present invention, FIGS. 2(A) and (B) show the opening and closing operation of a three-way solenoid valve, and FIGS. 3(A) and (B) show an electronically controlled suspension device according to the present invention. FIG. 4 is a diagram showing the opening/closing operation of the two-way solenoid valve, FIG. 4 is a diagram showing the opening/closing state of each solenoid valve during vehicle height adjustment and attitude control, and FIG. 5 is an embodiment of the present invention.
A flowchart showing an attitude control operation in which control 1 is varied according to the amount of attitude change of the electronically controlled suspension device to perform anti-nose buoy control or anti-swell auto control. FIG. 6 is a diagram showing an acceleration map used when determining a control amount according to a change amount. FSl,,FS2. R8I, R82...Suspension unit, 3...Air spring chamber %Z5a+15b・
... Reserve tank, 19 ... Air supply solenoid valve, 22.23, 25.26 ... Solenoid valve, 2
8... Exhaust direction switching valve, 30... Exhaust solenoid valve, 34... Control unit, 36...
...Acceleration sensor.

Claims (1)

[Claims] In an electronically controlled suspension device equipped with a vehicle height adjustment function and a posture control function, a suspension unit provided for each wheel using a combination of a fluid spring chamber and a coil spring;
A control valve that is individually connected to the fluid spring chamber of each suspension unit and controls the supply and discharge of fluid, an acceleration sensor that detects longitudinal acceleration applied to the vehicle body, and a forward acceleration detected by the acceleration sensor. or control means for controlling the opening of the front wheel side control valve or the rear wheel side control valve in accordance with the control time corresponding to the magnitude of the rear acceleration to perform posture control in a direction to counter the change in the posture of the vehicle body. An electronically controlled suspension device featuring: