JPH03125614A - Active suspension for vehicle - Google Patents

Abstract

PURPOSE:To effectively prevent floating of a car body by a cross wind by controlling the car body to roll toward the windward side of the cross wind at the time when the size of the cross wind is detected to be more than a specific value. CONSTITUTION:Hydraulic actuators 14 in suspension units 12FL - 12RR mounted between a car body and respective wheels are supplied and discharged of hydraulic pressure through an oil pipe 15 connected to its hydraulic chamber and by control valves 16 arranged between supply oil pipes 4FL - 4RR and a discharge oil pipe 6. The control valves 16 are controlled by a controller 33 for receiving each output signal from car floor height sensors 22 - 25, a steering sensor 26, a G sensor 27 for detecting acceleration in the front, rear, right and left directions of the car body, a car speed sensor 28 and cross wind sensors 34, 35. At this time of control, when the size of the detected cross wind is detected to be more than a specific value, a control signal to roll the car body to the windward side of the cross wind is outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an active suspension for a vehicle, and particularly to one that improves the stability of a vehicle against crosswinds.

(Prior Art) Conventionally, as a suspension device that improves the stability of a vehicle against crosswinds, there is one disclosed in, for example, Japanese Patent Laid-Open No. 164214/1983.

In this conventional example, when the output of a crosswind sensor that detects the wind pressure of a crosswind acting on the vehicle body exceeds a predetermined value, control is performed to increase the damping force or spring constant of the suspension device, so that the vehicle can move straight when a crosswind is acting. This prevents the vehicle from becoming damaged and the vehicle from overturning.

(Problem to be Solved by the Invention) However, simply increasing the damping force or spring constant as in the conventional device described above does not change the fact that the vehicle body rolls to the leeward side of the crosswind. This causes the problem that the vehicle's driving performance is significantly reduced compared to when driving normally.

(Means for Solving the Problems) The present invention was devised to solve the above problems, and operates in response to a fluid pressure source and fluid pressure supplied from the fluid pressure source to adjust the vehicle height. An actuator is provided between each wheel and the vehicle body for adjustment, and an actuator is provided between each actuator and the fluid pressure source to supply and discharge fluid pressure to the actuator. A control valve provided, a crosswind detection means for detecting the direction and magnitude of the crosswind acting on the vehicle body, and a controller for independently controlling the operation of each of the control valves in response to the detection output of the crosswind detection means. In the active suspension for a vehicle, the controller is configured to output a control output that causes the vehicle body to roll toward the windward side of the crosswind when it is detected that the magnitude of the detected crosswind has exceeded a predetermined value. This is an active suspension for vehicles characterized by the following.

(Function) According to the present invention, when the controller that independently controls the operation of each control valve detects that the magnitude of the detected crosswind detected by the crosswind detection means has exceeded a predetermined value, the controller independently controls the operation of each control valve. Since it is configured to output a control output that causes the vehicle body to roll upward, it can effectively prevent the vehicle body from lifting due to crosswinds, and ensure vehicle running stability even when crosswinds are present. It is.

(Example) Hereinafter, an example of the present invention will be described in detail based on the accompanying drawings.

FIG. 1 is a system configuration diagram of this embodiment.

In FIG. 1, an oil pump 1 is provided to suck oil stored in a reserve tank 3 through an oil passage 2 and discharge the oil to a supply oil passage 4. As shown in FIG. Supply oil path 4
An accumulator 5 that absorbs the pulsation of the oil pressure supplied by the oil pump 1 is connected near the oil pump 1, and an IJ-IJ oil passage 7 is connected downstream of the accumulator 5.

This relief oil passage 7 has an oil cooler 21 interposed therein and is connected to a discharge oil passage 6 communicating with the reserve tank 3, and a relief valve 8 is interposed in the middle of the relief oil passage 7. When the upstream oil pressure of the relief valve 8 reaches a predetermined value or more, the oil discharged from the oil pump 1 is discharged to the reserve tank 3 side. Furthermore, an oil filter 9 and a check valve 10 are interposed in the supply oil passage 4 on the downstream side of the connection with the relief oil passage 7, and the check valve 10 controls the flow of oil from the downstream side to the upstream side. It is prohibited. The supply oil passage 4 branches into a front wheel side oil passage 4F and a rear wheel side oil passage 4R downstream of the check valve 10, and the oil passages 4F and 4R are connected to Akicomulators 11F and 1IR for maintaining line pressure, respectively. has been done.

Each oil passage 4F, 4R is connected to an accumulator 11F, I, respectively.
Oil passages 4FL, 4FR, and 4R for each wheel on the downstream side of the IR
It is branched into L and 4RR, each oil line 4FL and 4FR.
, 4RL, and 4RR have suspension units installed for each wheel respectively) 12PL, 12PR112RL.
, 12RR are connected to each suspension unit, and a discharge oil passage 6 is also connected to each suspension unit.

Since each suspension unit has the same structure, the left front wheel suspension unit (12FL) is provided with a suspension spring 13 and a single-acting hydraulic actuator 14 between the vehicle body and the wheel. The supply and discharge of hydraulic pressure to the hydraulic chamber of the hydraulic actuator 14 is controlled by a control valve 16 interposed between the oil passage 15 communicating with the hydraulic chamber of the actuator 14, the supply oil passage 4FL, and the discharge oil passage 6. It becomes. As the control valve 16, a proportional solenoid valve is used. That is, this control valve 16 introduces the hydraulic pressure acting from the supply oil path 4FL side through the pilot oil path 17 as pilot pressure, and the oil pressure flows out from the pilot pressure chamber through the oil path 18 to the discharge oil path 6 side. The valve opening degree is controlled by controlling the pilot pressure using a solenoid valve that controls the oil waterfall pot according to the supplied current. For this reason,
This control valve 16 is capable of controlling the pressure within the hydraulic actuator 14 in proportion to the supplied current.

Further, an accumulator 20 is connected to the oil passage 15 communicating with the hydraulic chamber of the hydraulic actuator 14 via a throttle 19, and the throttle 19 exerts a vibration damping effect, and the accumulator 20 is filled with gas. It is designed to exert a gas spring action.

On the other hand, as shown in FIG.
A bypass passage 30 that branches off on the upstream side of the J-F oil passage 7 and communicates with the reserve tank 3 side is connected to the bypass passage 30, and this bypass passage 30 is connected to a bypass passage 30 consisting of a 2-point 2-position switching valve using an electromagnetic operation method. A valve 31 is interposed. This bypass valve 31 is constituted by a normally closed valve biased to a closed position by a spring.

In addition, each suspension unit 12FL, 12FR,
In the oil passage 15 connecting the hydraulic actuator 14 and the control valve 16 in 12RL and 12RR, a pilot check valve 29 is arranged in a direction to prevent oil from flowing from the hydraulic actuator 14 side to the control valve 16 side. It is provided. A pilot passage 32 connected to each pilot check valve 29 is connected to the upstream side of the bypass valve 31 in the bypass passage 30, and when the bypass valve 31 is closed, the hydraulic pressure generated upstream of the bypass valve 31 causes each pilot check valve 29 to be The valve is actuated to open the valve. As a result, the pilot check valve 29 is opened only when the piston valve 31 is closed, and the control valve 16 can control the operation of the hydraulic actuator 14.
is driven to the valve open position when the vehicle height is maintained at a constant value.

The operation of each control valve 16 is controlled by a controller 33 comprised of a microcomputer. This controller 33 includes vehicle height sensors 22 to 25 that are provided for each wheel and detect the stroke amount of the wheel.
, the detection output of the steering sensor 26 that detects the steering angle of the steering wheel, the detection output of the G sensor 27 that detects the longitudinal and lateral acceleration acting on the vehicle body, and the detection output of the vehicle speed sensor 28 that detects the running speed of the vehicle. The controller 30 controls the operating state of each control valve 16 for each wheel based on the detection outputs of these sensors. This makes it possible to actively control the supply and discharge of hydraulic pressure to each hydraulic actuator 14 independently.

The left and right crosswind sensors 34 and 35 described above are provided on the side surfaces of the left and right door mirrors of the vehicle, respectively, as shown in FIG. 2, and are used to detect the magnitude of wind pressure acting on the vehicle body from outside in the vehicle width direction. A piezoelectric or strain type wind pressure sensor is used. And each crosswind sensor 34.3
5 is connected to the controller 33 via a comparator 36, and the comparator 36 is connected to each cross wind sensor 34, 3.
By outputting the difference between the outputs of 5 to the controller 33, a signal output corresponding to the magnitude and direction of the crosswind acting on the vehicle body is supplied to the controller 33.

Note that the cross wind sensor 34 and the 35° comparator 36 constitute cross wind detection means.

FIG. 3 shows control operations for each wheel performed within the controller 33.

In FIG. 3, control is started with the ON signal of the ignition key, and first, in step S1, it is determined whether the vehicle speed detected by the vehicle speed sensor 28 is 3 km/h or more, and if it is not 3 km/h or more. If so, the determination in step S1 is repeated, and if the speed is 3 km/h or more, the process proceeds to step S2.

In step S2, it is determined whether the steering angle θ detected by the steering sensor 26 is greater than or equal to 30°, and if it is greater than or equal to 0°, the process proceeds to step S3.

In step S3, the vehicle speed V detected by the vehicle speed sensor 28, the lateral G detected by the G sensor 27, and the steering sensor 26
The steering angle θ detected from the vehicle speed V, lateral G, tff
i Yaw rate calculated from steering angle θ.

The center of gravity slip angle β of the vehicle is calculated based on the vehicle specifications. In the subsequent step S4, it is determined whether the center of gravity slip angle β calculated in step S3 is between the lower limit value βL and the upper limit value βH, and whether the center of gravity slip angle β is between the lower limit value βL and the upper limit value βH. If it is determined that there is, the vehicle is in a normal turning state, so the process advances to step S5.
Anti-roll control is performed. That is, since the state leading to steps 81 to 5 is a case where the vehicle is normally turning, anti-roll control is executed to reduce the roll of the vehicle body that occurs when the vehicle turns. Step S
The control in step 5 is executed based on the control gain read from the map shown in FIG. 4 according to the output of the G sensor 27, and reduces the control amount for the inner wheel in the turn and increases the control amount for the outer wheel in the turn, thereby causing the vehicle body to roll. Each control valve 16 is driven so that almost no occurrence occurs. This improves the steering stability when the vehicle turns, and after passing through step S5, the process returns to step S1.

In addition, in step S4 described above, the center of gravity slip angle β
If it is determined that the vehicle height is not between the lower limit value β and the upper limit value βH, the process proceeds to step S6 and the vehicle height is increased by 50 m+n from the reference vehicle height.
Each control valve 16 is driven to lower the vehicle height, and after the vehicle height lowering process in step S6 is completed, the process proceeds to step S7 to open the bypass valve 31 and maintain the vehicle height in a low vehicle height state. end. The state leading to step 86.7 is a state in which an abnormal center of gravity slip angle β has occurred in the vehicle;
In other words, the vehicle is not in a normal turning state and is in an unstable state where it is spinning or drifting out.
In such a state, if anti-roll control is performed as in step S5 above, there is a risk that the behavior of the vehicle will diverge, so anti-roll control is not performed. If the vehicle falls into such a state, there is a high possibility that an accident will occur, and in order to prevent the vehicle from overturning and ensure stability in the event of an accident, the vehicle height is lowered in step S6. The height of the center of gravity is lowered and the height of the vehicle is maintained in step S7. Note that step S7
When the bypass valve 31 is opened by the above process, the pilot check valve 29 is closed, so that the vehicle height is maintained.

On the other hand, in step S2 described above, if it is determined that the steering angle θ detected by the steering sensor 26 is not 30 degrees or more, the process proceeds to step S8, and the lateral G detected by the G sensor 27 is 0.1 g. It is determined whether or not the
If the lateral G is less than 0.1 g, the process returns to step S1.

If it is determined that the lateral G is 0.1 g or more, step S9
and comparator 36 connected to crosswind sensor 34.35.
It is determined whether the wind pressure WP output from
Go to 0. In step S10, it is determined whether the vehicle speed ■ detected by the vehicle speed sensor 28 is 60 km/h or more, and if it is 60 km/h or more, the process proceeds to step S1, and if it is less than 60 km/h, the process proceeds to step SL. return. In step Sll, the control force of the windward wheel is decreased and the control force of the leeward wheel is increased according to the detected lateral G, wind pressure, and vehicle speed, so that the vehicle body rolls toward the windward side. Control valve 16 is activated. In this case, the control amount given to each control valve is set to be sufficient to roll the vehicle body to the windward side, and the lateral G and wind pressure,
It is read from the map according to the vehicle speed. As a result, the vehicle body rolls in the opposite direction to that of a normal vehicle, effectively preventing the vehicle body from lifting due to crosswinds, and also ensuring the running stability of the vehicle even when crosswinds are present. Note that the reverse roll control in step Sll is not executed in the event of an abnormality in which the direction of lateral G and the direction of crosswind do not match. Furthermore, the vehicle speed condition in step S10 takes into consideration the fact that crosswinds have a large effect on the vehicle's driving performance when traveling at relatively high speeds. Furthermore, the vehicle speed condition may be abolished. After the process of step Sll described above has passed, the process returns to step S1.

Further, if it is determined in step S9 that the wind pressure WP is less than the reference value PL, the process proceeds to step S12 and the wind pressure WP is lower than the reference value PL.
The IG output from the sensor is set to a predetermined value (for example, O, I
g) It is determined whether the above condition continues for a predetermined time (for example, 2 seconds) or more, and if it does not continue, the process returns to step S1. If it is determined in step 512 that it has continued for a predetermined time or longer, the vehicle is rolling due to lateral G acting on the vehicle even though the vehicle is not turning and is not experiencing a large crosswind. In such a state, it is determined that the vehicle is traveling on a slope where the road surface is inclined in the road width direction, such as a rutted road or a canted road (driving state as shown in Fig. 5). Proceeding to S13, ramp control is executed. In step 513,
The control is executed based on the control gain read from the map shown in FIG. 6 in accordance with the output of the G sensor 27, and the hydraulic actuator in the direction of lateral G generation increases the pressure, while the hydraulic actuator on the opposite side decreases the pressure, so that the vehicle body is almost horizontal. Each control valve 16 is driven so that. In this case, the G sensor 27
The control gain for the output is set higher than in the case of the anti-roll control described above, and the vehicle body can be effectively kept level even when traveling on a slope. That is, the fifth
As shown in the figure, the lateral G that occurs when driving on a slope is smaller than the lateral G that occurs when the vehicle turns, and even if the control is performed at a sensitivity of 1, which is the same as in the case of anti-roll control, the vehicle body can be effectively leveled. However, by setting a high control gain for the G sensor output, it is possible to efficiently maintain the vehicle body posture horizontally. And step 5
After passing step S13, the process returns to step S1.

The control content shown in FIG. 3 is a process related to attitude control performed within the controller 33. In addition, the controller 33 performs processing according to the vehicle height and the speed of change of the vehicle height based on the detected value of each vehicle height sensor. Ride comfort control and vehicle height adjustment control based on the time average value of the detected values of each vehicle height sensor are also performed at the same time, and the outputs of each control are added to control the operation of the control valve 14. .

According to the above embodiment, when the turning state of the vehicle is normal, the anti-roll control is executed to effectively reduce the roll occurring in the vehicle body, thereby achieving the effect of improving the steering stability when the vehicle turns.

In addition, in unstable conditions such as when the center of gravity slip angle is abnormal when the vehicle turns, anti-roll control is not executed, and anti-roll control is performed to prevent the vehicle's behavior from diverging, and at the same time to lower the vehicle height. By maintaining a low vehicle height state, the height of the center of gravity of the vehicle is lowered and the vehicle body is prevented from overturning in the event of an accident, which has the effect of improving safety.

Furthermore, by rolling the vehicle body toward the windward side when a crosswind occurs while traveling straight, the vehicle body is effectively prevented from being lifted up by the crosswind, and the running stability of the vehicle is reliably ensured.

Further, when traveling on a slope, by executing attitude control in which the control gain for the G sensor output is set high, it is possible to efficiently keep the vehicle body attitude horizontal.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but reverse roll control can be performed by using a normal suspension link mechanism in which the suspension alignment change characteristics are set to bump side toe-out and rebound side toe-in. As a result, crosswind disturbances can be canceled out by toe changes, further improving vehicle stability. It goes without saying that various other modifications can be made without departing from the gist of the present invention.

(Effects of the Invention) As described above in detail with the embodiments, according to the present invention, when the magnitude of the crosswind exceeds a predetermined value, the vehicle body is rolled toward the windward side of the crosswind. To provide an active suspension for a vehicle that can effectively prevent lifting and ensure running stability of the vehicle even when a crosswind is applied.

[Brief explanation of the drawing]

Fig. 1 is a system configuration diagram showing one embodiment of the present invention;
Figure 3 is a plan view of the vehicle showing the arrangement of the crosswind sensor, Figure 3 is a flow chart diagram showing the control operation within the controller 33, Figure 4 is a map diagram of control coefficients for lateral G in anti-roll control, and Figure 5 is a map diagram of control coefficients for lateral G in anti-roll control. FIG. 6 is a conceptual diagram showing the slope running state of the vehicle, and is a map diagram of control coefficients for lateral G in slope control. 1... Oil pump, 14... Actuator. 16...Control valve, 27...G sensor. 33...Controller, 34.33...Cross wind sensor insect condyle Artificial Rhythm Jikan Car Industry Co., Ltd. Figure 2 Figure 4 Figure Figure Figure

Claims (1)

[Claims] A fluid pressure source, an actuator provided between each wheel and the vehicle body so as to operate in response to fluid pressure supplied from the fluid pressure source and adjust the vehicle height, and each actuator and the fluid pressure source a control valve provided for each actuator to supply and discharge fluid pressure to the actuator, and a crosswind detection means for detecting the direction and magnitude of the crosswind acting on the vehicle body; In a vehicle active suspension comprising a controller that independently controls the operation of each of the control valves in response to the detection output of the crosswind detection means, the controller is configured to detect when the magnitude of the detected crosswind has exceeded a predetermined value. An active suspension for a vehicle, characterized in that the active suspension for a vehicle is configured to output a control output that causes the vehicle body to roll toward the windward side of a crosswind when the vehicle body is detected.