JPH0314643B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a suspension device for a vehicle that performs roll control to prevent rolling of a vehicle body.

An electronically controlled suspension system is being considered that improves ride comfort and handling stability by electronically controlling the damping force of a shock absorber and the spring constant of an air spring. In order to more effectively prevent rolling when turning in such an electronically controlled suspension device, for example, in US Pat. No. 3,608,925, roll displacement occurring in the vehicle body is predicted based on vehicle speed and steering condition, The system is configured to suppress roll displacement of the vehicle body by supplying fluid to the fluid spring chamber of the suspension unit and discharging fluid from the fluid spring chamber on the extension side. As shown in this US patent, predicting the roll displacement occurring in the vehicle body based on the vehicle speed and steering angle and suppressing the roll displacement has the following advantages. In other words, if the configuration is configured to detect lateral acceleration generated in the vehicle body and start control for suppressing roll, the control valves for controlling the fluid in each fluid spring chamber will actually start each fluid after receiving a control command. Since it takes a certain amount of time for the fluid in the spring chamber to be discharged, there is a problem in that even if the control is implemented, it is not possible to effectively suppress the roll that occurs in the vehicle body. However, as shown in the above US patent, By configuring the system to predict the roll displacement that occurs in the vehicle body based on the steering angle and suppress the roll displacement, each vehicle will be able to predict the roll displacement that will occur in the vehicle body before the vehicle actually starts turning and lateral acceleration is generated in the vehicle body. It is possible to start supplying and discharging fluid within the fluid spring chamber. Thereby, the fluid in each fluid spring chamber can be supplied and discharged in accordance with the timing when the vehicle body actually rolls during turning. This is because the lateral acceleration that occurs in the vehicle body during turning does not occur until the vehicle starts turning, and therefore occurs later than the steering. However, if the roll control shown by this device is performed on a road with low road resistance, such as a snowy road, even though the wheels are slipping while turning, almost no centrifugal force will act on the vehicle body. As a result, the roll control performed causes the vehicle body to roll toward the opposite side for a long time, causing a problem in which the driver and passengers no longer feel any discomfort.

This invention was made in view of the above points,
The purpose of this is to predict the roll displacement that occurs in the vehicle body based on the vehicle speed and steering angle and suppress the roll displacement, so that each fluid spring chamber By supplying and discharging fluid, it is possible to effectively reduce the roll that occurs in the vehicle body when turning, and after the roll control that prevents the vehicle body from rolling starts, roll control is performed if lateral acceleration does not occur after a set time. To provide a suspension device for a vehicle, which prohibits roll control when the wheels slip and almost no centrifugal force acts on the vehicle body while turning on a road with low road resistance such as on a snowy road. It's about doing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A vehicle suspension device according to an embodiment of the present invention will be described below with reference to the drawings.
In Figure 1, S _FR indicates a suspension unit for the right front wheel of a car, S _FL indicates a suspension unit for the left front wheel, S _RR indicates a suspension unit for the right rear wheel, and S _RL indicates a suspension unit for the left rear wheel. ing. The above suspension units S _FR , S _FL , S _RR , and S _RL are the main air spring chamber 1, respectively.
1a to 11d, auxiliary air spring chambers 12a to 12d, shock absorbers 13a to 13d, and a coil spring (not shown) used as an auxiliary spring. Further, 15a to 15d are switching devices for switching the damping force of the shock absorbers 13a to 13d to hard or soft. The switching devices 15a to 15d are controlled by the controller 16. In addition, 17a-17
d is a bellows.

Furthermore, a compressor 18 compresses the atmospheric air sent from an air cleaner (not shown) and supplies it to the dryer 19. This dryer 19 dries the supplied compressed air using silica gel or the like. The compressed air from the dryer 19 is stored in a front wheel reserve tank 20F and a rear wheel reserve tank 20R via a pipe A, respectively.
Reference numeral 21 denotes a pressure sensor provided in the reserve tank 20F. When the internal pressure of the reserve tank 20F decreases to below a set value, the compressor 18 is activated by a signal from the pressure sensor 21. When the internal pressure of the reserve tank 20F becomes equal to or higher than the set pressure, the compressor 18 is stopped by a signal from the pressure sensor 21.

The reserve tank 20F and the main air spring chamber 11a are connected via an air supply solenoid valve 220 as a supply on-off valve, and the reserve tank 20F and the main air spring chamber 11b are connected via an air supply solenoid valve 22b as a supply on-off valve. connected via.
Further, the reserve tank 20R and the main air spring chamber 11c are connected to the reserve tank 20R via an air supply solenoid valve 22c as a supply on/off valve.
and the main air spring chamber 11d are connected via an air supply solenoid valve 22d as a supply on-off valve. The solenoid valves 22a to 22d are normally closed valves.

Further, the compressed air in the main air spring chamber 11a is supplied to an exhaust solenoid valve 23 as an exhaust opening/closing valve.
The compressed air in the main air spring chamber 11b passes through the exhaust solenoid valve 23b as an exhaust opening/closing valve, and the compressed air in the main air spring chamber 11c passes through the exhaust solenoid valve 23b as an exhaust opening/closing valve. 23c, the compressed air in the main air spring chamber 11d is released to the atmosphere through an exhaust pipe (not shown) via an exhaust solenoid valve 23d serving as an exhaust opening/closing valve. Above solenoid valve 2
3a to 23d are valves that are always closed.

Furthermore, the main air spring chamber 11a and the auxiliary air spring chamber 12a each have a spring constant switching solenoid valve 26.
The main air spring chamber 11b and the auxiliary air spring chamber 12b are connected to a spring constant switching solenoid valve 2 via a.
6b, the main air spring chamber 11c and the auxiliary air spring chamber 12c are connected to the spring constant switching solenoid valve 26c, and the main air spring chamber 11d and the auxiliary air spring chamber 12d are connected to the spring constant switching solenoid valve 26c. 26d.

Further, the main air spring chambers 11a and 11b are connected to the main air spring chambers 11c and 11b via a communication pipe B and a communication solenoid valve 27F as a communication control valve.
d is connected via a communication pipe C and a communication solenoid valve 27R serving as a communication control valve. The communication solenoid valves 27F and 27R are valves that are always open.

By the way, the solenoid valves 22a to 22
d, 23a-23d, 26a-26d, 27F,
Opening/closing control of 27R is performed by signals from the controller 16.

Furthermore, 30 is a steering sensor that detects the steering angle of the steering wheel, 31 is a brake sensor that detects on/off of the brake, 32 is an accelerator opening sensor that detects the opening of the accelerator, and 33 is a steering sensor that detects the steering angle of the steering wheel, 33 is an accelerator opening sensor that detects the opening of the accelerator, and 33 is a steering sensor that detects the steering angle of the steering wheel. An acceleration sensor that detects acceleration, 34 a vehicle speed sensor that detects vehicle speed, 35 a front vehicle height sensor that detects the height of the front part (front wheel part) of the car, and 36 a rear part (rear wheel part) of the car.
A rear vehicle height sensor 37 detects the vehicle height of the vehicle, and a yaw angular velocity sensor 37 detects the yaw angular velocity of the vehicle. Signals from the sensors 30 to 37 are supplied to the controller 16.

Next, the operation of an embodiment of the present invention configured as described above will be described. When the ignition key is turned on, the controller 16 performs the control shown in FIG. First, the steering wheel angle, steering wheel angular velocity, vehicle speed, which are stored in the controller 16,
All data of lateral G (acceleration) and yaw angular velocity are 0.
(step S1).

Next, flag (FLAG) 1 and flag (FLAG) 2 are set to "0" (step S2). Here, flag 1 is set to "1" when roll control is performed, and flag 2 is set to "1" when roll control is stopped. next,
A timer T, which measures the time since the start of roll control, is set to 0 (step S3). Next, open the communication solenoid valves 27F and 27R to connect the left and right main air spring chambers 11a, 11c and 11.
b, 11d are communicated with each other. If it is already open, confirm it (step S4). and,
It is determined whether flag 1 is set to "1" (step S5). Since flag 1 is set to "0" in step S1 above,
Proceed to step S6. In this step S6, timer T and _T0 are compared. Here, T ₀ is the time required for constant lateral G and yaw angular velocity to occur. Since the timer T was set to "0" in step S3, it is determined that "T<T ₀ " and the process proceeds to step S7. In this step S7, the steering wheel angle is determined by the controller 16 based on the signals from the steering sensor 30 and the vehicle speed sensor 34.
Steering wheel angular velocity and vehicle speed data are read.
Then, it is determined from the above steering wheel angle data whether the steering wheel is in the neutral position (step S8). If the determination in step S8 is ``YES'', the process returns to step S2. On the other hand, the above step S8
If the determination is "NO" in step S9, it is determined whether flag 2 is set. Here, since flag 2 was set to "0" in step S2, the flag 2 is set to "0" in step S1.
Go to 0. (If the flag 2 is determined to be "1", the process returns to step S4.) Next, in step S10, the communication solenoid valve 2
0F and 20R are closed. Here, if it has already been closed, it is checked. In other words, this step S10 shuts off the left and right main air spring chambers 11a, 11c and 11b, 11d. The process then proceeds to step S11, where roll control is performed.The details of this roll control are as follows. For example, when the steering wheel is turned to the right, the vehicle height of the left wheel decreases and the vehicle height of the right wheel increases. The exhaust solenoid valves 23a and 23c are opened for a predetermined period of time to raise the vehicle height of the left wheel and to lower the vehicle height of the right wheel. As a result, even when the steering wheel is turned to the right, the vehicle height of the left wheel is lowered, and the vehicle height of the right wheel is prevented from increasing, thereby keeping the vehicle level. On the other hand, when the steering wheel is turned to the left, the vehicle height of the right wheel decreases and the vehicle height of the left wheel increases, but in order to prevent this, the right wheel air supply solenoid valves 22a and 22c,
Left wheel exhaust solenoid valves 23b and 23d
is opened for a predetermined period of time to raise the vehicle height of the right wheel and to lower the vehicle height of the left wheel. As a result, even when the steering wheel is turned to the left, the vehicle height of the right wheel is lowered, and the vehicle height of the left wheel is prevented from increasing, thereby keeping the vehicle level.

After the roll control in step S11 described above is performed, flag 1 is set to "1" in step S12, and the process returns to step S5.
In this step S5, it is determined again whether flag 1 is "1". Here, since flag 1 was set to "1" in step S12, the process advances to step S13 and the time count of timer T is incremented by "+α". α is step S5 to S12
This is the time during which processing is performed. Next, the process goes to step S6 again, where T and the set time _T0 are compared.
If it is determined in step S6 that T< _T0 , the processing in steps S7 to S12 is performed again, and the timer T is incremented by "+α" in step S13. In this way, as long as T< _T0 , the processes of steps S7 to S12 are repeated. If it is determined in step S6 that T≧T ₀ , the process advances to step S14. In this step S14, the lateral G (G _Y ) and yaw angular velocity (R _Y ) data output from the acceleration sensor 33 and the yaw angular velocity sensor 37 are read into the controller 16. and,
In step S15, the lateral G (G _Y ) and the reference lateral G (G _YO ) are compared, and the yaw angular velocity (R _Y ) and the reference yaw angular velocity (R _YO ) are compared.
In this step S15, G _Y ≧ GYO and R _Y
If it is determined that ≧R _YO , the process proceeds to step S16.
T is set to "0" and flag 2 is set to "0", and the process returns to step S7. On the other hand, the above step S1
If it is determined in step S5 that G _Y < G _YO or R _Y < R _YO , the process advances to step S17 and the process proceeds to step S11.
The roll control carried out in is stopped. Thereafter, the process advances to step S18, where T is set to "0" and flag 2 is set to "1", and then the process returns to step S7.

As detailed above, according to the present invention, the roll displacement occurring in the vehicle body is predicted based on the vehicle speed and the steering angle, and each supply on-off valve and discharge on-off valve is controlled to suppress the roll displacement. The fluid in each fluid spring chamber can be supplied and discharged in accordance with the roll displacement that actually occurs in the car body, which can effectively suppress the roll of the car body when turning, and also prevent the car from starting turning. Set time T ₀ after roll control is started to suppress vehicle body roll.
If the specified lateral acceleration does not occur afterward (i.e.
Since the roll is stopped when the vehicle is slipping), it is possible to prevent unnecessary roll control and reduce the problem of the vehicle body being in an unnatural posture and causing the occupants to feel uncomfortable.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a vehicle suspension device according to an embodiment of the present invention, and FIG. 2 is a flowchart showing the operation. 11a-11d...main air spring chamber, 22a-2
2d, 23a-23c, 26a-26c, 27
F, 27R...Solenoid valve, 20F, 20
R... Reserve tank, 33... Acceleration sensor,
37... Yaw angular velocity sensor.

Claims (1)

[Scope of Claims] 1. A suspension unit provided for each wheel and having a fluid spring chamber, and a fluid supply means capable of supplying fluid to each fluid spring chamber of each suspension unit via a supply control valve. A fluid discharge means capable of discharging fluid from each fluid spring chamber of each suspension unit via a discharge on-off valve, and a means for communicating the fluid spring chambers of each left and right suspension unit between the front wheels and between the rear wheels. A communication means that communicates via a control valve, a roll displacement prediction means that predicts the occurrence of roll displacement of the vehicle body based on the vehicle speed and steering condition, and a control valve for communication between the left and right suspensions that is normally opened by opening the communication control valve of the communication means. The fluid spring chambers of the shock absorber unit are made to communicate with each other between the front wheels and between the rear wheels.
When the roll displacement prediction means predicts the roll displacement of the vehicle body, the communication control valve of the communication means is closed, and the supply on-off valve of the fluid spring chamber on the compression side of the suspension unit is closed in the roll direction of the vehicle body. The roll displacement of the vehicle body is suppressed by supplying fluid to the fluid spring by opening the fluid spring, and by discharging fluid from the fluid spring chamber by opening the discharge on-off valve of the fluid spring chamber on the extension side. The suspension device is equipped with an acceleration detection means for detecting lateral acceleration acting on the vehicle body, and the roll control means predicts roll displacement of the vehicle body by the roll displacement prediction means. After performing the control to suppress the roll displacement, if the acceleration detected by the acceleration detection means is equal to or less than a set value after a set time has elapsed, the control to suppress the roll displacement is stopped. A vehicle suspension device featuring: