JPH02133213A - Bad road detecting device - Google Patents

Abstract

PURPOSE:To enable the discrimination of a bad road by detecting the lateral acceleration acted upon a car body as well as the frequency of the detected acceleration valve exceeding the specified band width. CONSTITUTION:A lateral acceleration sensor 2 detects the lateral acceleration acted upon a car body and inputs it to the input circuit 1a of a controller 1 as an electric signal. The input circuit 1a removes the noise of the same electric signal, converts its level and inputs it into an arithmetic circuit 1b. The arithmetic circuit 1b disposes of the signal according to a flow chart as well as performs the comparative disposal with the data in a control condition setting circuit 1c by its timer and counter function, discriminates a bad road in case of exceeding the specified band width by the specified frequency within the specified time, outputs the signal to driving circuits 1d, 1e and ultimately drives the motor 16 of the hydraulic pressure buffer 3 of a wheel so as to perform buffer action. A device for detecting a bad road accurately can be thus obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a rough road detection device that is applied to vehicles such as automobiles and detects rough roads.

(Prior Art) Conventionally, as a device capable of detecting rough roads, there is one disclosed in Japanese Patent Laid-Open No. 151111/1983.

This conventional device has a vertical vibration detector that detects the vertical vibration of the vehicle body depending on the road surface condition, and determines that the road is rough based on the levels of high frequency components and low frequency components in the detection signal of this vertical vibration detector. It was done like this.

(Problem to be Solved by the Invention) However, in the conventional device described above, the determination was made simply based on whether the detection level of the vertical vibration detector was above a predetermined level, so even if there was a large roll during steering, There was a problem in that the level of vertical vibration was too high and the road was determined to be rough.

The present invention was made in view of the above-mentioned problems, and an object of the present invention is to provide a rough road detection device that can accurately detect rough roads.

(Means for Solving the Problems) In order to achieve the above object, the suspension system of the present invention is designed to reduce lateral acceleration (hereinafter referred to as lateral acceleration) acting on the vehicle body.
A lateral acceleration sensor (hereinafter referred to as lateral acceleration sensor) that detects the lateral acceleration sensor (hereinafter referred to as lateral acceleration sensor) is input, and the signal from this lateral acceleration sensor is input, and the lateral acceleration is detected within a prescribed band width for a prescribed number of times while driving for a prescribed time or a prescribed distance. A rough road determining means is provided which determines that the road is rough if the road exceeds the limit.

(for production) The operation of the rough road detection device of the present invention will be explained.

When a vehicle travels on a rough road, the resulting vehicle body vibration includes vibration not only in the vertical direction but also in the lateral direction. Therefore, this lateral vibration is detected as lateral G by the lateral G sensor.

The rough road determining means inputs the signal from the lateral G sensor, counts how many times the lateral G exceeds a band width within a predetermined size range during a predetermined time or a predetermined traveling distance, and calculates a predetermined value. If it exceeds the number of times, it is determined that the road is rough.

In addition, when lateral G is applied due to roll, even though the lateral G exceeds the band width, the number of times it exceeds the band width is equal to the number of times the steering is performed, which is extremely small compared to the case of a rough road, and is a predetermined number of times. , and the road will not be determined to be rough due to the lateral G caused by this roll.

Note that the lateral G sensor can also be used for controlling other devices such as a four-wheel steering device, for example.

(Example) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, the configuration of the embodiment will be explained.

FIG. 1 is an overall view showing a suspension system S to which a rough road detection device according to an embodiment of the present invention is applied, FIG. 2 is a cross-sectional view showing a hydraulic shock absorber of the suspension system S of the embodiment, and FIG.
The figure is a flowchart showing the operation flow of the controller of the embodiment device, and FIG. 4 is a graph showing the relationship between lateral G detected by the lateral G sensor and time.

In FIG. 1, 1 indicates a controller. This controller 1 is provided with a lateral G sensor 2 on the input side, and a variable damping force type hydraulic shock absorber 3, 3, 3.3 on the output side.

First, the hydraulic shock absorber 3 will be explained. The hydraulic shock absorber 3 is provided between each of the four wheels of the vehicle body and the vehicle body 4. Then, this hydraulic shock absorber 3
As shown in the figure, there is a sealed outer cylinder 5, a cylinder 6 built into the outer cylinder 5, a piston rod 7 inserted from one end of the cylinder 6, and an inner wall of the cylinder 6 provided at the tip of the piston rod 7. A piston 8 that slides in the axial direction, a bottom valve (not shown) provided at the lower end of the cylinder 6, a reservoir chamber 9 formed by the inner wall of the outer cylinder 5 and the cylinder 6, and a rod that supports the piston rod 7. Guide 1
0.

The piston 8 connects the inside of the cylinder 6 to the hydraulic shock absorber 3.
It is divided into an extension side liquid chamber 11 whose internal volume is reduced during the extension stroke, and a compression liquid chamber 12 whose internal volume is reduced during the compression stroke. The piston 8 is provided with communication holes 8a and 8b that communicate the expansion side liquid chamber 11 and the compression side liquid chamber 12, and the both speed communication holes 8a and 8b are connected to the expansion side damping valve 8c and the compression side, respectively. It is opened and closed by a damping valve 8d.

Further, a communication passage 13 is formed in the piston rod 7 to communicate the expansion side liquid chamber 11 and the pressure side liquid chamber 12, and in the middle of this communication passage 13, there are two orifice holes 14a ( An adjuster 14 is rotatably provided, and the cross-sectional area of the communicating passage 13 changes based on the rotation of the adjuster 14, thereby changing the mode between the low damping force characteristic mode and the medium damping force characteristic mode. The damping force can be changed in three ways: damping force characteristic mode and high damping force characteristic mode.

The adjuster 14 is connected via an operating rod 15 to a motor 16 provided at the base end of the piston rod 7 on the vehicle body 4 side, and is rotated by the drive of the motor 16.

Next, the entire system will be explained based on FIG.

The lateral G sensor 2 detects the lateral acceleration (lateral G) acting on the vehicle body 4 and outputs an acceleration signal (lateral G signal g) which is an electric signal proportional to the detection tank G. For example,
A device that includes a pendulum that can swing in response to lateral G and generates a voltage according to the amount of swing of the pendulum is used. The lateral G sensor 2 is also used to control a four-wheel steering device (not shown).

The controller 1 is a so-called microcomputer, and has an input circuit 1a as shown in the figure.

It is comprised of an arithmetic circuit 1b, a control condition setting circuit 1c, a front wheel drive circuit 1d, and a rear wheel drive circuit 1e.

The input circuit 1a has the function of converting the lateral G signal g to a signal level that can be received by the arithmetic circuit lb, and also removing noise contained in the signal g.

The arithmetic circuit 1b receives a signal from the input circuit 1a,
In accordance with the flowchart shown in FIG. 3, which will be described later, the signal is processed and compared with data in the control condition setting circuit lc, and both drive circuits 1d and 1e are processed as necessary.
It has the function of outputting a drive signal to. Further, this arithmetic circuit 1b has a timer function and a counter function.

The control condition setting circuit 1c previously stores comparison values and actuator control conditions for the results of the processing signals of the arithmetic processing circuit 1b, and is capable of reading and writing data by the arithmetic processing circuit 1b. .

Both drive circuits 1d and 1e receive a voltage signal V that drives the motor 16 of the front wheel side hydraulic shock absorber 3 and the motor 16 of the rear wheel side hydraulic pressure shock absorber 3, respectively, in accordance with the drive signal from the calculation circuit 1b. It has a power amplification function that outputs.

Next, the operation of the embodiment will be explained based on FIGS. 3 and 4.

In the arithmetic circuit 1b of the controller 1, the flow shown in FIG. 3 is performed. That is, in step 101,
A process of reading the lateral G signal g from the lateral G sensor 2 is performed.

Next, in step 102, it is determined whether the lateral G signal g exceeds the upper limit of the predetermined bandwidth B. In other words,
When a vehicle travels, lateral G acts on the vehicle body. For this lateral G, the control condition setting circuit 1c is set with a band width B that indicates driving on a rough road, as shown in FIG. Band width B
is called and compared with the input lateral G signal g. If it is determined in step 102 that the bandwidth B has been exceeded (Yes), the process proceeds to step 103, and if it has not been exceeded (No).
If it is judged as such, it will be returned.

Next, in step 103, a process of operating a timer in the arithmetic circuit lb is performed. Note that the operating time of this timer may be adjusted depending on the vehicle speed, such that it becomes shorter when the vehicle speed is faster and becomes longer when the vehicle speed is slower.

Next, in step 104, a counting process is performed to set the counter in the arithmetic circuit 1b to +l, and the process proceeds to step 105.

In step 105, it is determined whether the lateral G signal g exceeds the bandwidth B or not. If the judgment is YES, proceed to step 106; if NO, step 107
Proceed to.

In step 106, the counter is incremented by 1, and the process proceeds to step 107.

In step 107, it is determined whether or not the timer has timed up. If this judgment is Yes, step l
Proceed to O8, and if No, turn around.

In step 10B, it is determined whether the count by the counter exceeds a predetermined value.

That is, as shown in FIG. 4, when the vehicle is traveling on a rough road, the lateral G signal g has a high frequency swing as shown by g-1, and the band changes within a predetermined short time. The upper and lower limits of width B are alternately and repeatedly exceeded. On the other hand, when the vehicle rolls due to steering, the lateral G signal has a peak equal to the number of times the steering is performed, as shown in g-2 in the figure. Therefore, in the case of a rough road, the number of counts on the counter increases based on the judgments in step 102 and step 105 before the timer times out. Therefore, by the determination in step 108, it is possible to determine whether the lateral G signal g exceeding the band width B is due to the vehicle traveling on a rough road with more than a predetermined level of unevenness or due to mere roll.

If YES is determined in this step 108, the process proceeds to step 109, and if NO is determined, step 11
Go to 0.

In step 109, a process is performed to output a signal V for driving the motor 16 in order to set the damping force of the hydraulic shock absorber 3 to the medium damping force characteristic mode. Therefore, when driving on a rough road, the mode is set to the medium damping force characteristic mode, and the Achieves both comfort and wheel ground contact (steering stability). Furthermore, when driving on a flat road surface, the damping force characteristics are controlled based on other control conditions such as vehicle speed, such as a low damping force characteristic mode at low speeds and a high damping force characteristic mode at high speeds. Ru.

In step 110, the process returns after performing processing to reset the counter/timer.

As described above, in the device of this embodiment, it is possible to accurately determine a rough road based only on the lateral G signal g from the lateral G sensor 2 without mistaking it for lateral G due to roll.

In addition, since the decision is made based on the signal from only the lateral G sensor 2, it is easier to secure the mounting area, easier to route the harness, and the number of input ports for the controller can be reduced. The overall system can be simplified.

Although the embodiments of the present invention have been described above based on the drawings, the specific configuration is not limited to these embodiments, and even if there is a design change or the like within the scope of the invention, the present invention include.

For example, in the embodiment, when detecting a rough road, the judgment is made based on whether the number of counts within a predetermined time exceeds a predetermined value. A rough road may be determined based on whether the road is above or below.

(Effects of the Invention) As explained above, in the rough road detection device of the present invention, the signal from the lateral acceleration sensor is input, and the lateral acceleration is within a predetermined band width while traveling for a predetermined time or a predetermined distance. Since a rough road determining means is provided that determines that the road is bad when the number of times exceeds a predetermined number, the road is not determined to be bad depending on the lateral acceleration caused by the roll (it is possible to accurately determine the rough road).

[Brief explanation of the drawing]

FIG. 1 is an overall view showing a suspension system S to which a rough road detection device according to an embodiment of the present invention is applied, FIG. 2 is a cross-sectional view showing a hydraulic shock absorber of the suspension system S of the embodiment, and FIG.
The figure is a flowchart showing the operation flow of the controller of the embodiment device, and FIG. 4 is a graph showing the relationship between lateral G detected by the lateral G sensor and time. l...Controller (bad road judgment means) 2...Lateral acceleration sensor 4...Vehicle body Fig. 4

Claims (1)

[Claims] 1) A lateral acceleration sensor that detects lateral acceleration acting on the vehicle body; and a signal from the lateral acceleration sensor is input, and the lateral acceleration reaches a predetermined value while traveling for a predetermined time or a predetermined distance. A rough road detection device comprising: a rough road determining means that determines that the road is rough when the bandwidth of the road exceeds a predetermined number of times or more.