JPS6239312A - Ground clearance adjusting device - Google Patents

Abstract

PURPOSE:To improve the safety and the riding comfort by configurating a device in such a way that, when a ground clearance detecting means is in trouble, the function of the ground clearance adjustment is suspended in case a vehicle is running, or the specified amount of a fluid is fed to shock absorbers after the fluid in the absorber has been discharged once by its own weight in case the vehicle is in a standstill. CONSTITUTION:A device as referred to the titled allows a controller 54 to control such items as a levelling valve 24, a closing valve 64, and a damping valve 66 so as to allow the ground clearance detected by a ground clearance sensor 38 which is provided for each of wheels in a system 58, to correspond with the set ground clearance. This configuration allows a pressure fluid from a pump 20 to be fed to or discharged from a cylinder 12 of a shock absorber. In this case, when the ground clearance sensor 38 is found to be out of order by a trouble detecting means in the controller 54, the levelling valve 24 is controlled so as to suspend the function of the ground clearance adjustment in case a vehicle is running, or so as to feed the specified amount of the fluid to the shock absorber after the fluid in the shock absorber has been discharged once by its own weight in case the vehicle is in a standstill.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a vehicle height adjustment device that maintains the height of a vehicle body relative to an axle at a predetermined value.

``Prior Art'' In a vehicle, a suspension device is inserted between the axle and the vehicle body in order to prevent vibrations from the axle from propagating to the vehicle body. Therefore, when the car body gFJ increases, the car body sinks, and when the car body becomes lighter, the car body rises. Furthermore, when braking suddenly, the front of the vehicle sinks, causing the nose to drop, and the rear of the vehicle tends to sink on uphill roads, and the front of the vehicle tends to sink down on downhill roads. Therefore, in the past, a vehicle height sensor was installed between the axle and the vehicle body to detect the vehicle height, and the fluid pressure of the suspension absorber was adjusted so that the detected vehicle height was within a set range. ing.

As this type of vehicle height adjustment device, for example,
No. 118907 discloses a vehicle height sensor that detects the height between the axle and the vehicle body, a compressor that provides fluid pressure for a shock absorber of a suspension system that is located between the axle and the vehicle body and supports the vehicle body, It is equipped with a valve means for controlling the hydraulic absorber fluid pressure, and an automatic vehicle height control device that compares the vehicle height detected by the vehicle height sensor with the target vehicle height and controls the energization of the compressor and the valve means in the direction that the two agree. A vehicle height adjustment device is shown. In the device disclosed in this publication, a target vehicle height is set according to the vehicle speed, and feedback control is performed so that the actual vehicle height matches the vehicle height corresponding to the vehicle speed.

"Problems to be Solved by the Invention" Conventional technologies such as the above-mentioned published patent publication do not teach at all what measures to take when a failure occurs in the vehicle height sensor.

However, if the vehicle height sensor is malfunctioning and the vehicle height is automatically controlled, problems will arise from both ride comfort and safety standpoints. For example, if the vehicle height sensor indicates a detection value that is lower than the actual vehicle height, the vehicle height will be controlled to be abnormally high, and in the opposite case, the vehicle height will be abnormally low and insufficient. The distance from the ground cannot be maintained.Furthermore, if the output of the vehicle height sensor is unstable, the vehicle height will also become unstable, causing the vehicle to repeatedly move up and down.

SUMMARY OF THE INVENTION An object of the present invention is to provide a vehicle height adjustment device that can maintain a certain level of vehicle height in a straight line even after a vehicle height sensor has failed.

"Means for Solving the Problems" The present invention provides a plurality of vehicle height detection means disposed at predetermined positions on a vehicle body to detect the height of the vehicle body relative to the axle, and a suspension system located between the axle and the vehicle body that supports the vehicle body. Seven absolutes of the device include a pump means for applying fluid pressure, a valve means for controlling shock absorber fluid pressure, and a vehicle height control for controlling the valve means in a direction to match the vehicle height detected by the vehicle height detection means with the set vehicle height. The vehicle height adjusting device which detects (+t!) is provided with a failure detection means for detecting a failure of the vehicle height detection means, and the vehicle height control means is configured such that the failure detection means detects a failure of the vehicle height detection means. When a failure is detected, the vehicle height adjustment is stopped when the vehicle is running, and when the vehicle is stopped, the fluid in the shock absorber is temporarily discharged, and then the valve means is set to supply a fixed amount of the shock absorber (handling object). It is characterized by having means for controlling.

"Operation" The present invention is provided with a failure detection means for detecting a failure of the vehicle height detection means, and the vehicle height control means controls the vehicle when the failure detection means detects a failure of the vehicle height detection means. Sometimes, vehicle height adjustment is stopped, and when the vehicle is stopped,
It has means for controlling the flat means so that the fluid in the shock absorber is once discharged and then a fixed amount of fluid is supplied to the shock absorber. Therefore, when the vehicle height detection means fails, the vehicle height adjustment is stopped when the vehicle is running, and when the vehicle is stopped, the fluid in the shock absorber is once discharged and then a fixed amount of fluid is supplied.
It is possible to maintain a certain level of vehicle height even after the vehicle height sensor has failed.

"Example" Hereinafter, the present invention will be explained in detail based on the drawings.

FIG. 1 shows a system outline of a vehicle height adjustment device according to an embodiment.

Cylinder 10.12 and 4.16 of the shock absorber of the suspension system, which is located between the axle and the vehicle body and supports the vehicle body, are
Old friends of the car body, they are installed on the front cloth, rear left, and rear right.

The oil in the reserve tank 18 is driven by a dual pump 20, is branched off by a diversion valve 22, and flows to leveling valves 24 and 26. The oil separated by the leveling valves 24 is respectively supplied to the cylinders 10.12 via damper/accumulator units 28.30. In addition, the leveling valve 26
The separated oil is supplied to the cylinders 14.16 via respective damper/accumulator units 32.34.

2. In order to detect the height between the axle and the vehicle body, vehicle height sensors 36, 38, 40, 42 are provided at predetermined positions on the vehicle body, corresponding to the cylinders 10, 12, 14, 16. has been done.

Note that the symbols 44, 46, 48, 50, and 52 are a vehicle speed sensor, a steering angle sensor, a manual switch, an accelerator switch, and a brake oil pressure switch, respectively. Further, numeral 54 is a controller, and vehicle height sensor 36.38
．． The leveling valves 24 and 26 are controlled in a direction to match the vehicle height detected by 40 and 42 with the set vehicle height.

Next, FIG. 2 shows a block diagram of the vehicle height adjustment position A according to the embodiment.

The pump 20 is driven by the engine 56, whereby the oil in the reserve tank 18 is branched by the flow dividing valve 22 into the front side and the rear side. On the front side, the oil is separated into right and left sides by a leveling valve 24. The dash-dotted line 58 in the figure shows the front fabric system. System 58 includes damper/accumulator unit 3
0, this damper/accumulator unit 30 includes an accumulator 60, 62, an on-off valve 64, and a damping force valve 6.
6, and the cylinder 12 is connected to the damping force valve 66. Note that a vehicle height sensor 38 is provided adjacent to the cylinder 12.

The controller 54 includes a vehicle speed sensor 44, a steering angle sensor 46, a brake pressure sensor 68, and an accelerator opening sensor 70.
, the signals from the manual switch 48 are manually input, and the detected vehicle height signal from the vehicle height sensor 38 is manually input. The controller 54 controls the leveling valve 24, the on-off valve 64, and the damping force valve 66.

Note that although only the front cloth system 58 is shown in FIG. 2, the other old friends, rear left and rear right systems are also similar.

Next, FIG. 3 shows a flowchart of vehicle height adjustment by the vehicle height adjustment device.

The process starts at a start 100, and when the vehicle is stopped at step 102, data from the vehicle height sensor is sampled at a cycle T, at a step 104, and an average vehicle height value is calculated at a cycle TI at a step 106.
Proceed to step 8. In step 102, if the vehicle is not stopped,
In step 110, data from the vehicle height sensor is sampled with a period T, and in step 112, data is sampled with a period T+I.
Then, the average vehicle height value is calculated and the process proceeds to step 108.

In step 108, the calculated vehicle height value (H) is loaded, and in step 114, if it is lower than the set value, step 116
to drive the up solenoid valve, and also in step 11
If it is the set value in step 4, the solenoid valve is turned off in step 118, and if it is higher than the set value, it is turned off in step 120.
to drive the lower solenoid valve. Then proceed to return 122 from step 116.118.120.

And, in FIG. 4, steps 104 and 110 of FIG.
processing is shown.

Starts at start 200, and at step 202 timer 1
In step 204, if it is not the vehicle height sampling time, the process returns to step 202, and if it is the vehicle height sampling time, the process proceeds to step 206.

In step 206, data is loaded from the vehicle height sensor;
In step 208, data is stored in the vehicle height memory area,
Clear timer 1 in step 210, and then clear timer 1 in step 210.
Return to 02.

Further, FIG. 5 shows the processing of steps 106 and 112 in FIG. 3.

Starts at start 300 and starts at step 302 with timer 2
In step 304, if it is not the average vehicle height calculation time, the process returns to step 302, and if it is the average vehicle height calculation time, the process proceeds to step 306. In step 306, data is loaded from the vehicle height memory area, in step 308 the loaded data is averaged, in step 310 a new calculated vehicle height value (H) is stored in memory, in step 312 timer 2 is cleared, Step 3
Return to 02.

Next, FIG. 6 shows the configuration of the controller 54 of FIG. 2.

The detected vehicle height from the vehicle height sensor 38 is supplied to a vehicle height calculation section 402 to calculate a vehicle height value, and this vehicle height value is sent to the control section 4.
04. The control unit 404 drives the actuator drive unit 406 to control the leveling valve 24 in a direction that matches the detected vehicle height value with the set vehicle height value. Note that the control unit 404 is supplied with a vehicle speed signal and an engine rotation speed signal from a vehicle speed sensor.

A sensor failure detection section 410 that detects a failure of the sensor 38 is connected to the vehicle height sensor 38, the detection section 410 is connected to a nonvolatile memory 412, and the memory 412 is connected to the control section 404. .

When the sensor failure detection unit 410 detects a failure in the vehicle height sensor 38, the failure code is stored in the non-volatile generation memory 410.
write to. The control unit 404 includes a non-volatile memo IJ 41
If a fault code is written in 2, the vehicle height adjustment will be stopped when the vehicle is running, and when the vehicle is stopped, the fluid in the shock absorber will be drained due to the weight of the vehicle, and then the fluid will be pumped into the shock absorber. The actuator drive unit 406 is driven to control the leveling valve 24 so as to supply a constant amount.

Next, FIG. 7.8 shows a flowchart of processing by the controller 54 of FIG. 6.

In FIG. 7, when it is determined in step 500 that the vehicle height sensor is malfunctioning, a failure code is written into the non-volatile memory in step 502.

In FIG. 8, the routine starts at START 504, and at step 506, if no failure code is written to the nonvolatile memory, the routine goes to the normal routine, and if there is, the routine goes to step 508.

In step 508, if the car is not stopped but is running)
If the vehicle height adjustment is stopped at step 510 and the vehicle is stopped, the process proceeds to step 512.

In step 512, the vehicle height is lowered, and in step 514, if the count-up of timer 3 is not completed, the process returns to step 512, and if the count-up is completed, the process proceeds to step 516. In step 516, the vehicle height is increased,
In step 518, if the count-up of timer 4 is not completed, the process returns to step 516, and if the count-up is completed, the vehicle height adjustment is stopped in step 520.

Note that the time until the timer 4 count up in step 518 ends is determined according to the engine speed, and even if the engine speed is different, a certain amount of oil is supplied to the cylinder of the shock absorber. It has become so.

"Effects of the Invention" As explained above, according to the present invention, a certain level of vehicle height can be maintained even after the vehicle height sensor has failed.

[Brief explanation of the drawing]

Fig. 1 is a system schematic diagram of the vehicle height adjustment device according to the embodiment, Fig. 2 is a block diagram of the vehicle height adjustment device according to the embodiment, and Fig. 3 is a flowchart of vehicle height adjustment by the vehicle height adjustment device. 4.5 is a flowchart showing the processing of some steps in FIG. 3; FIG. 6 is an explanatory diagram of the configuration of the controller in FIG. 2; and FIG. 7.
FIG. 8 is a flowchart of processing by the controller of FIG. 6. 10.12.14.16... Shock absorber cylinder, 24.26... Leveling valve,
36.38.40.42...Vehicle height sensor, 54
...Controller, 402...Vehicle height calculation section, 404...Control section, 406...
Actuator drive unit, 410...Sensor failure detection unit, 412...Nonvolatile memory. Ward change diagram 6 rotation speed

Claims (1)

[Scope of Claims] A plurality of vehicle height detection means disposed at predetermined positions on the vehicle body to detect the height of the vehicle body relative to the axle; and a shock absorber fluid pressure of a suspension system that is located between the axle and the vehicle body and supports the vehicle body. A vehicle height adjustment device comprising: a pump means; a valve means for controlling shock absorber fluid pressure; and a vehicle height control means for controlling the valve means in a direction to make the detected vehicle height by the vehicle height detection means coincide with a set vehicle height. , failure detection means for detecting a failure of the vehicle height detection means is provided, and the vehicle height control means adjusts the vehicle height when the vehicle is running when the failure detection means detects a failure of the vehicle height detection means. A vehicle height adjustment device characterized by having means for controlling a valve means such that when the vehicle is stopped, the fluid in the shock absorber is once discharged and then a fixed amount of fluid is supplied to the shock absorber.