JPH0419214A - Suspension device for vehicle - Google Patents

Abstract

PURPOSE:To allow a vehicle to pass an obstruction without damaging the body lower face by detecting an obstruction on the road in front, and elongating actuators for a suspension device so as to lift the vehicle height before wheels passing the obstruction. CONSTITUTION:An obstruction in front of a vehicle and the distance to the obstruction are detected by a preview sensor 10 fitted to the front end part of a body 4, and the detected information in inputted into a controller 50. The controller 50 performs the operation corresponding to the specified program on the basis of the signals of the preview sensor 10 and the detection signal of a vehicle speed sensor 52, and controls a front wheel and a rear wheel control valves 20, 22 to elongate actuators 14, 18 so that the body 4 is lifted before wheels 6 reaching the obstruction. With this constitution, the vehicle can pass the obstruction without damaging the body lower face.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a suspension device suitable for use in vehicles, particularly automobiles.

[Conventional technology]

Conventionally, suspension devices have been configured to increase the damping force of the suspension or raise the vehicle height to improve all-terrain performance when a rough road is detected due to changes in vehicle height or vertical acceleration acting on the vehicle body. It has been known.

[The problem that the idea attempts to solve]

However, none of these methods can be used to pass obstacles that exist on a good road surface, and if the height of the obstacle is greater than the minimum height of the vehicle, the same applies. It was impossible to pass the obstacle, or damage to the underside of the vehicle body could not be avoided when passing the obstacle.

[Means to solve the problem]

The present invention was devised in view of the above, and includes an actuator that is interposed between the wheels and the vehicle body and is capable of extending the suspension, a preview sensor that detects obstacles on the road surface in front of the vehicle, and a preview sensor that enables the vehicle to move smoothly. and control means for controlling the actuator so that when an obstacle is detected in front, the suspension is extended and the vehicle body is urged upward before the wheel passes the obstacle. This is a suspension device for vehicles.

[Effect]

According to the present invention, when the preview sensor detects an obstacle in front of the vehicle, the control means extends the suspension to urge the vehicle body upward before the wheel passes the obstacle. The actuator is controlled as follows.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to FIGS. 1 to 7.

In FIG. 2, reference numeral 2 generally indicates an automobile, 4 is a vehicle body, 6 is a front wheel, 8 is a rear wheel, and 10 is a preview sensor attached to the front end of the vehicle body 2. The preview sensor 10 is a well-known sensor capable of detecting the distance to an obstacle in front of the vehicle by emitting radio waves, sound waves, or light toward the lower part in front of the vehicle and detecting the reflection thereof.

As is clear from FIG. 1, a hydraulic double-acting actuator 14 is interposed between the vehicle body 4 and the front wheels 6 in parallel with the coil spring 12. The actuator 14 includes a cylinder supported by the vehicle body 4 and a piston connected to the front wheel 6 and partitioning the inside of the cylinder into an upper chamber 14a and a lower chamber 14b. Similarly, a hydraulic double-acting actuator 18 is interposed between the vehicle body 4 and the rear wheel 8 in parallel with the coil spring 16. The actuator 18 includes a cylinder supported by the vehicle body 4 and a piston that is connected to the rear wheel 8 and partitions the inside of the cylinder into an upper chamber 18a and a lower chamber 18b.

The actuator 14 has its upper chamber 14a and lower chamber 14b connected to an electromagnetic front wheel control valve 20, and the actuator 18 has its upper chamber 18a and lower chamber 18b connected to an electromagnetic front wheel control valve 22. Oil is supplied from the reservoir 24 to the front wheel control valve 20 via the pump 26, pressure control valve 28, and front wheel supply path 30, and oil is supplied from the front wheel control valve 20 to the reservoir 24 via the front wheel discharge path 32. is discharged. Similarly, oil is supplied to the rear wheel control valve 22 from the reservoir 24 via the pump 26, the pressure control valve 28, and the rear wheel supply path 34, and from the rear wheel control valve 22 to the rear wheel exhaust path. Oil is drained to the reservoir 24 via 36.

Note that the pressure control valve 28 returns oil to the reservoir 24 when the pressure between it and the pump 26 is equal to or higher than the set pressure. Further, reference numeral 38 is a check valve provided in the front wheel supply path 30 that allows oil to flow only to the front wheel control valve 20, and 40 is a check valve provided in the rear wheel supply path 34 and allows oil to flow only to the front wheel control valve 22.
a check valve that only allows oil to flow to 41.
42. 44 are respective accumulators. The front wheel control valve 20 has a first position where only the upper chamber 14a and lower chamber 14b of the actuator 14 communicate with each other, and a first position where only the upper chamber 14a and the lower chamber 14b of the actuator 14 communicate with each other.
4a and the supply passage 30, and a second position where the lower chamber 14b and the discharge passage 32 are communicated, and the upper chamber 14a and the discharge passage 3.
2 and a third position that communicates the lower chamber 14b with the supply passage 30, and selection of these positions is performed by a signal from the front wheel drive circuit 46. Similarly, the rear wheel control valve 22 is connected to the upper chamber 1 of the actuator 18.
a first position where only the lower chamber 8a and the lower chamber 18b communicate with each other;
The upper chamber 18a and the supply path 34 are communicated with each other, and the lower chamber 18b
and a third position where the upper chamber 18a and the discharge passage 36 are communicated and the lower chamber 18b and the supply passage 34 are communicated. The selection is made by a signal from the rear wheel drive circuit 48.

The pump is designed so that when oil is supplied to the upper chamber 14a or 18a and the actuator 14 or 18 is extended, the front or rear part of the vehicle body 4 is suddenly lifted and the front wheels 6 or rear wheels 8 are moved away from the road surface due to the inertia. 26 and the capacities of the actuators 14 and 18 are set.

Reference numeral 50 indicates a front wheel drive circuit 46 and a rear wheel drive circuit 48.
It is a controller that controls the The controller 50 receives a detection signal from the preview sensor 10 as well as a detection signal from a vehicle speed sensor 52 that detects vehicle speed.
Control is executed according to the flowchart shown in the figure. Although not shown, there are input circuits necessary for inputting detection signals of each sensor, output circuits for control signals to the drive circuits 46 and 48, and memories necessary for control, timers,
Equipped with a microprocessor.

Next, the details of the control executed by the controller 50 will be explained according to the flowchart shown in FIG.

First, as an initial setting by turning on an engine key switch (not shown), each memory is cleared in step S1, and each drive circuit 46, 48 is connected to each control valve 20.2.
A control signal is output so that each of the terminals 2 and 2 assumes the first position.

Next, in step S2, the detection signals from each sensor 10.52 are stored in a predetermined memory, and in step S3, it is determined whether a control flag, which will be described later, is "1". Since the control flag is initially set to "0", it is initially determined to be rNC)+, and the process proceeds to step S4. In step S4, it is determined whether the detection signal from the preview sensor 10 stored in step S2 indicates that there is an obstacle A on the road ahead of the vehicle. If it indicates that there is an obstacle A, rYESJ is determined and the process proceeds to step S5. In step S5, the vehicle speed stored in step S2 or the set vehicle speed (
For example, it is determined whether the speed is 20 km/h). This is because if the vehicle speed is too low, even if the front wheels 6 are lifted off the road surface, the effect cannot be expected if it takes too much time to pass the obstacle A. If the determination in step S5 is "rYES", the process advances to step S6.

In step S6, based on the vehicle speed stored in step S2, the distance from the obstacle A that is optimal for driving the front wheel actuator 14 to lift the front wheels off the road surface is determined. In other words, the higher the vehicle speed, the further the front wheel needs to be lifted from the obstacle A. Specifically, refer to the map shown in FIG. 4 (stored in the ROM in the controller 50). is required. Next, in step S7, the preview sensor 10 stored in step S2 is
It is determined whether the detection signal from has reached the optimum distance determined in step S6. If the vehicle has reached the optimum distance to the obstacle A, the determination in step S7 is "rYES" and the process proceeds to step S8.

In step S8, a control signal is output to the front wheel drive circuit 46. The front wheel drive circuit 46 that received the control signal in step S8 holds the front wheel control valve 20 at the second position for a set time Tx (for example, 3 seconds), and then returns it to the first position. It is configured to control the front wheel control valve 20. In other words, the upper chamber 14 of the front wheel actuator 14
Oil is supplied to a for a set time TX, and the actuator 14 is extended. As a result, car 2
is in the state shown in FIG. The set time TX can be adjusted to the supply time required for the front wheels 6 to be lifted off the road surface (for example, 0.3 seconds) after the start of oil supply, but In order to reduce the shock, it is preferable to set the time according to the time from the start of oil supply until passing the obstacle A and landing.

Following the output of the control signal in step S8, step S9
The control flag of the predetermined memory in the controller 50 is set to “1”.
'' is set, a delay time timer T is started in step SIO, and the process returns to step S2. In addition,
If the determination in step S4, S5 or S7 is "NO", the process also returns to step S2.

After the control flag is set to "1" in step S9, rYEsJ is determined in step S3, and the process proceeds to step 512, where the delay time T is set. Determine if is set. Initially, the delay time is T.

Since this has not been set, the process proceeds to step 313, and the delay time T is determined from the map shown in FIG. 5 (stored in the ROM in the controller 50) based on the vehicle speed stored in step S2. is required. Note that this delay time T. The meaning of this is that it is set to lift the rear wheels 8 off the road surface at the optimal timing relative to the obstacle A after the front wheel actuator 14 is extended, and therefore it is set based on the vehicle speed at that time. That's what I do.

Next, the delay time T set by the timer T in step S14. Determine if it is above. Timer T has a delay time T. When reaching this point, a control signal is output to the rear wheel drive circuit 48 in step 515. The rear wheel drive circuit 48, which received the control signal in step S15, operates the rear wheel control valve 22 for a set time TY.
The rear wheel control valve 22 is configured to be held at the second position for a period of (for example, 3 seconds) and then returned to the first position. In other words, the rear wheel actuator 18
Oil is supplied to the upper chamber 18a for a set time T, and the actuator 18 is extended. As a result, the automobile 2 enters the state shown in FIG. Note that, as in the case of the front wheels 6, the set time T is basically the supply time (for example, 0.3 seconds) required from the start of oil supply until the rear wheels 8 are lifted off the road surface. However, in order to reduce the shock upon landing, it is preferable to set the time to match the time from the start of oil supply until passing through obstacle A and landing.

Following the output of the control signal in step 315, step S
In Step 16, the control flag of a predetermined memory in the controller 50 is set to "0", and in Step S17, the delay time timer T is reset, and the process returns to Step S2 again.
.

According to the above configuration, when the automobile 2 passes an obstacle A on the road surface while driving, the front wheels 6 and the rear wheels 8 are separated from the road surface as shown in FIG. 6 and as shown in FIG. 7, respectively. Since the car 2 floats away from the ground, it is possible to significantly increase the actual minimum height above the ground when passing the obstacle A, and this allows the car 2 to float on a road surface that is higher than the normal minimum height above the ground. The above obstacle A can be passed through without causing damage to the vehicle body 4, or damage to the vehicle body can be reduced as much as possible.

Next, a modification of the above embodiment will be explained. This modification differs from the above embodiment in the configuration of the drive circuit. That is, in the above embodiment, the front wheel drive circuit 46 receives the control signal in step S8 or step S15.
Alternatively, the rear wheel drive circuit 48 holds the front wheel control valve 20 or the rear wheel control valve 22 at the second position for a set time and then returns the front wheel control valve 20 or the rear wheel control valve 22 to the first position. It is configured to control the wheel control valve 22.

However, in the modified example, the front wheel drive circuit 46 or the rear wheel drive circuit 48 that receives the control signal in step S8 or step S15 operates the front wheel control valve 20 or the rear wheel control valve 22 for the first set time. After holding the third position for a second set time, the rear wheel control valve 22 is controlled to hold the rear wheel control valve 22 at the second position for a second set time, and then return to the first position. . Note that the first set time is set shorter than the second set time. This is achieved by forcibly contracting the coil springs 12 or 16 provided in parallel by contracting the actuators 14 or 18, and by configuring the actuators 14 or 18 to be extended. 4 is applied upward, and even if the same effect is obtained compared to the above embodiment, the capacity of each actuator 14, 18 and pump 26 can be reduced. .

In addition, in the above embodiments and modifications, while the front wheels 6 or the rear wheels 8 are separated from the road surface by control, the control valve 20
or 22 is held in the third position to retract the actuator 14 or 18, and before the front wheels 6 or rear wheels 8 touch the ground, the control valve 20 or 22 is held in the second position again to extend the actuator 14 or 18. It is also possible to configure the control valve 20 or 22 to return to the first position after the vehicle has touched the ground and absorbed the impact.

Further, in the above embodiment and modification, the front wheels 6 are first lifted off the road surface when passing the obstacle A, and then the rear wheels 8 are lifted off the road surface after a set time.
It is also possible to configure the vehicle and rear wheel 8 to be lifted off the road surface at the same time.

Further, in the above embodiments and modifications, the front wheels 6 and the rear wheels 8 are configured to be separated from the road surface, but when passing the obstacle A, the front wheels 6 and the rear wheels 8 may come into contact with the road surface. Even if the actuators 14 and 18 are configured to extend while maintaining the vehicle body 4, the vehicle body 4, which is urged upward, is still able to pass the obstacle while maintaining a higher than normal ground clearance due to its inertia. , it is possible to obtain an effect similar to that of the above embodiment. Conversely, from the viewpoint that the front wheels 6 and the rear wheels 8 maintain contact with the road surface, there are advantages in that the impact is small and the maneuverability is not significantly impaired.

Furthermore, in the above embodiment, if the preview sensor 10 is configured to be able to identify the height of an obstacle, the above-mentioned control will not be executed for small obstacles below a predetermined height; It is also possible to control the wheels to be lifted, that is, to reduce the size of the actuator, in accordance with the timing of passing the small obstacle.

Note that the present invention provides a vehicle height adjustment function that adjusts the vehicle height to a target vehicle height, or, for example, a system that supplies fluid to a fluid spring chamber on the outside of the turn and discharges fluid from a fluid spring chamber on the inside of the turn during cornering. Of course, even a suspension device with an attitude control function can be adopted.

〔Effect of the invention〕

According to the above configuration, when an obstacle is detected on the road surface in front by the preview sensor while driving, the control means controls the actuator to move the vehicle upward when passing the obstacle. energized, it is possible to significantly increase the effective ground clearance of the vehicle when passing obstacles, which allows the vehicle to clear obstacles on the road surface that are higher than the vehicle's normal ground clearance. 4 can pass through the vehicle without causing damage, or damage to the vehicle body can be reduced as much as possible.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the entire system showing one embodiment of the present invention;
2 is a side view of the automobile according to the embodiment of FIG. 1, FIG. 3 is a flowchart showing the control of the controller 50 of FIG. 1, and FIG. 4 is the relationship between vehicle speed and optimal distance in the flowchart of FIG. 3. FIG. 5 is a map showing the relationship between vehicle speed and delay time in the flowchart of FIG. 3, and FIG. FIG. 7 is a side view showing a state in which the rear wheel 8 of the automobile 2 according to the above embodiment is located just in front of a protrusion on the road surface. 4...Vehicle body, 6-...Front wheel, 8...Rear wheel, 10...
・Preview sensor, 14.18... Actuator, 50... Controller Applicant Mitsubishi Motors Corporation Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] An actuator that is interposed between the wheels and the vehicle body and can extend the suspension; a preview sensor that detects an obstacle on the road in front of the vehicle; and a preview sensor that detects an obstacle on the road in front of the vehicle. A vehicle suspension device comprising: control means for controlling the actuator to extend the suspension and urge the vehicle body upward before passing the obstacle.