JPS6349512A - Hydraulic suspension device - Google Patents

Abstract

PURPOSE:To improve the drive feeling by installing a car height sensor for detecting if the car height is in the region exceeding the neutral region or high car height region or in the region below the low car height region and controlling a spring force adjusting means and a damping force adjusting means according to the result of the detection. CONSTITUTION:A spring force adjusting solenoid valve 11 and a damping force adjusting variable throttle valve 13a are controlled by a controller 15 on the basis of the output signal of a car height sensor 18, and said car height sensor 18 is installed at the lower part of a car body 16, and operated through links 19b and 19a according to the increase and decrease of the car height. When the car height sensor 18 detects the high car height state exceeding a prescribed high car height range or the low car height state below a previously set low car height range, the valves 11 and 13a are controlled in the direction for increasing the spring force and damping force. When the car height is not set for a certain time into the region exceeding the high car height region or the region below the low car height region, the valves 11 and 13a are controlled in the direction for reducing the spring force and damping force.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a suspension system having functions of vehicle height adjustment, spring force adjustment, and damping force adjustment.

(Prior Art) FIG. 5 shows a conventional example of a hydraulic suspension system having the function of adjusting the vehicle height, spring force, and damping force of an automobile.

Reference numeral U in the figure indicates a hydraulic unit, and this hydraulic unit is composed of a pump 11, a motor 2, a filter 3, a reservoir (tank) 4, and a relief valve 5. The hydraulic pressure generated by the hydraulic unit U is stored in a gas-filled accumulator 7 via a check valve 6, and the gas-filled accumulator 7 is operated by a pressure switch 8 attached thereto. The motor 2 of said pump l by a signal
By turning on and off the oil pressure, the oil pressure can be controlled to an appropriate level.

When attempting to raise the vehicle height, the fuel filler valve 9a
Pressure oil is supplied to the suspension body (strut) 10 by opening the valve, and when lowering the vehicle height,
By opening the oil drain valve 9b, the pressure oil in the main body (strut) 10 is returned to the reservoir 4.

The spring force of the suspension device is adjusted by opening and closing the solenoid valve (switching valve) 11 to change the gas chamber volume of the gas-filled accumulators 12a, 12b, and the damping force is adjusted by: Variable throttle valve (N magnetic switching adjustment valve) 13a.

This is done by adjusting the throttle (eg, orifice) of the variable throttle valve 13a of the damping force generator 13, which is a check valve 13b, using a rotary type or latching type solenoid valve, a motor, or the like. Furthermore, the check valve 13b is provided to provide a difference in damping force between the extension direction and the contraction direction of the suspension body 1O.

In addition, the solenoid valves 9a and 9b-11, the variable throttle valve 13a
The switching and adjustment of each actuator such as
Various sensors 1 that detect roll conditions, sudden starts, sudden stops, etc.
A controller 15 receives signals from 4, processes them, and issues signals based on the results of determination of running conditions and driving conditions.
This is done by the signal.

Note that in an actual four-wheeled vehicle, the hydraulic unit U is shared, and the same control is performed for each wheel.

[Problems to be Solved by the Invention] By the way, in the suspension device configured as described above, - When driving on a boat road, in order to achieve a comfortable ride with less bumping up from the road surface, Generally, the spring force and damping force are set to low levels, but on gently undulating roads, the car body causes a large pitching motion due to the frequency of vibrations placed on the spring, resulting in a significant decrease in steering stability and a fluffy feeling. This may lead to deterioration of ride comfort.

``Means for Solving the Problems'' In order to achieve the above object, the present invention provides a means for solving problems when the vehicle height is in any of the ``neutral region'', ``region exceeding the high vehicle height region'', and ``region below the low vehicle height region''. In addition to providing a vehicle height sensor that detects whether there is a vehicle height, it also issues a control signal to increase the spring force and damping force when the vehicle enters an area that exceeds the high vehicle height area or falls below the low vehicle height area. Also, if the vehicle does not enter the "region exceeding the high vehicle height region" or "region below the low vehicle height region" for a certain period of time, a control signal is generated to reduce the spring force and damping force. It is.

"Operation" By configuring as described above, the damping force and spring force are increased to suppress vertical movement of the vehicle body when the vehicle is in the region exceeding the 1" high vehicle height region or in the region below the low vehicle height region. death,
On the other hand, when the vehicle is in the neutral vehicle height region for a certain period of time or more, the damping force and spring force can be reduced.

1 Embodiment" Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 4.

The suspension device of the present invention adds the control means provided in the conventional suspension control system to the vehicle body 16 and the axle 1.
The basic configuration is such that a detection signal from a vehicle height sensor 18 that measures the distance is input between the vehicle height sensor 18 and the vehicle height sensor 7, and control of the spring force and damping force is changed in accordance with the detection signal from the vehicle height sensor. There is.

First, the structure of the vehicle height sensor will be explained with reference to Fig. 1.
The vehicle height sensor 18 is provided at the bottom of the vehicle body 16, and one end of a link 19a extending in the horizontal direction is rotatably attached to the center thereof. The other end of the link 19a is rotatably connected to one end of a link 19b extending in the vertical direction, and the other end of the link 19b is rotatably connected to the center portion 17a of the axle 17.

As the vehicle height increases or decreases, the link 19b moves up and down, and this up and down movement is converted into a rotational movement of the link 19a.

Therefore, when the vehicle height increases, the link 19a rotates clockwise in FIG. 1. When the link 19a crosses the boundary between the preset 1-neutral vehicle height region and the 1-high vehicle height region, the vehicle height sensor 18 outputs "l" corresponding to the high vehicle height signal SH. When the vehicle rotates further and crosses the boundary between the "high vehicle height area" and the "particularly high vehicle height area," a digital signal of "1" corresponding to the super high vehicle height signal SHH is output. Ru. Conversely, as the vehicle height decreases, the link 19a rotates counterclockwise,
When the link 19a crosses the boundary between "high vehicle height area" and 1-low vehicle height area, the vehicle height sensor 18 outputs a low vehicle height signal SL.
A digital signal of "l" corresponding to is output, and further,
When the boundary between the "low vehicle height region" and the "particularly low vehicle height region" is crossed, the vehicle height sensor 18 outputs a digital signal of 1" corresponding to the super low vehicle height signal SLL. These signals 5HSSHH, SL, and SLL representing the fifth
It is supplied to the input end of a controller (corresponding to the reference numeral 15 in the example in FIG. 5) of a hydraulic control system configured similarly to the conventional example shown in the figure.

Next, a flowchart of the control executed by the controller will be described with reference to FIG.

Note that "SPn" in the following description indicates the n-th step in the flowchart. Also, the hydraulic control system of this example has the same configuration as the example in Figure 5 except for the details of controller control, so the same reference numerals as those used in Figure 5 are used. The operation of each component will be explained below.

When the power is turned on, control operation starts.
The memory contents of the controller 15 are cleared at P +, and then the output signal of the vehicle height sensor 18 is read into the controller 15 at S P t.

Next, SP requests operation of the valves (the i-magnetic piece 11 for adjusting the spring force and the variable throttle valve 13a for adjusting the damping force) according to the determination result of the switching valve operation request subroutine described later. Further, in response to the request, a signal is output from the controller 15 to operate the switching valve in SP, and thereafter, in order to prepare for the next adjustment operation, SP.
Return to t.

Next, the switching valve operation request subroutine executed in the SP will be explained with reference to FIGS. 3 and 4.

SP. 2. Determine whether the vehicle height is not in a particularly high range, that is, whether the super high vehicle height signal 5HH = O, and select YES (
In the case of SHH=O), SP+, to, NO(SHH=
1) In the case of SPI? Proceed to.

S P , ,: Determine whether the vehicle height is in a particularly low range, that is, whether the ultra-low vehicle height signal 5LL = 0, and
If ES (SLL=O), proceed to S P w; if NO, proceed to S P , .

SP+2: Increment a timer T (not shown) built in the controller and add rlJ.

SP+3: Determine whether the fiQ timer TI has counted a predetermined time (in the embodiment, the time is counted based on the number of times the control is repeated), and if YES, go to SP, 4; If NO, proceed to SP, e.

sp, ,: Memory built into the controller (
Clear the valve switching request flags A and B (not shown) to "0"
shall be.

S P , 6: Generate a control signal to switch the solenoid valve 11 and the variable throttle valve 13a in a direction where the spring force and damping force are reduced (7 [open the magnetic piece 11 and widen the throttle of the variable throttle valve 13a]) .

SP+a: Determine whether the valve switching request flag A is "0" or not, and return to the main routine with YES as a condition.

If No, proceed to 5P18, which will be described later.

SP+? : I in the above S P , and SP ++
When it is determined that the vehicle height exceeds the high vehicle height range or the vehicle height falls below the low vehicle height range, a valve switching request flag 1 is set.

SP+s: Reset the timer T.

SPz+: Determine whether the vehicle is in the neutral vehicle height range and select YES
In the case of S P t. If NO, proceed to sp.

SP! . : After setting the valve switching request flag B to "1", return to the main routine. In this case, both valve switching request flags A and B are "I", and the vehicle height is 1.
Since the vehicle is outside the "neutral vehicle height range," a signal is output to request valve switching to increase the spring force and damping force (close the solenoid valve ! and throttle the variable throttle valve 13a).

SP,...: Determine whether "l" is set in the valve switching request flag B. If YES, return to the main routine via SP and t; if NO, return to the main routine. return.

S P 12: A signal is output to request a valve change that increases the spring force and damping force.

Therefore, the valve is switched to increase the spring force and damping force on the condition that both valve switching request flags A-H are set to "l", and both flags A-B are set to "0". The valve is switched to reduce the spring force and the damping force under certain conditions.

Next, with reference to FIG. 4, the relationship between changes in vehicle height and changes in the internal pressure of the accumulators 12a and 12b will be explained.

When the vehicle height changes as shown in the figure, the time 1. when the vehicle height enters the "region exceeding the high vehicle height region". Set the valve switching request flag A to "l". Next, at time t when the vehicle height enters the "neutral vehicle height region", the valve switching request flag B is set to "1", and at time t when the vehicle height moves out of the "neutral vehicle height region", the spring force and damping are changed. A valve switching request is issued to operate the solenoid valve 11 and the variable throttle valve 13a to increase the force, and at time t4
The switching operation ends.

By controlling as described above, the internal pressure change of the accumulator 12b is delayed in phase with respect to the vehicle height change. That is, as mentioned above, when the vehicle height moves out of the neutral vehicle height range, a request to close the switching valve 11 is issued, and the gas-filled accumulator 12
The switching valve 11 is closed in a state where the pressure inside b is approximately the same as the pressure inside the strut body IO when the vehicle height is within the neutral range, and this pressure state is maintained. Therefore, when the change in vehicle height is small during subsequent driving, and an operation request to switch the spring force and damping force to a lower value is issued and the switching valve 11 is opened, the pressure is kept almost the same. There is no sudden flow of pressurized oil between the gas-filled accumulator 12b and the strut body 1o, and almost no change in vehicle height occurs.

Note that the time counting means is not limited to the one embodiment described above, and for example, the vehicle height does not fall within any of the following ranges: 1) Vehicle height exceeding the high vehicle height range 1) Vehicle height below the low vehicle height range. Counting may be performed using a timer that is started under the condition of , and is reset under the condition of entering any of the areas.

Furthermore, the specific configuration of the damping force adjustment and spring force adjustment means, such as the volume and number of accumulators, and the specific configuration of the hydraulic system, are not limited to those shown in the example in FIG. Of course, the measurement method is not limited to that shown in FIG.

[“Effects of the Invention”] As is clear from the above explanation, the present invention is capable of determining whether the vehicle height is in the “neutral region,” “the region exceeding the high vehicle height region,” or “the region below the low vehicle height region.” In addition to providing a vehicle height sensor to detect
A control signal is issued to increase the spring force and damping force when the vehicle enters a region below the low vehicle height region, and the vehicle height exceeds the 1 high vehicle height region for a certain period of time, or an I low vehicle height region. Since the control signal is generated to reduce the spring force and the damping force when the spring force and the damping force do not fall within the range below the above range, the following effects are achieved.

(a) When the vehicle body moves up and down on a road surface with gentle undulations, pitching motion can be suppressed by changing the spring force and damping force to higher settings.

(b) When switching the valve to lower the spring force and damping force, the pressure in the hydraulic system on both sides of the valve can be kept almost the same, preventing sudden changes in vehicle height when operating the valve. .

[Brief explanation of the drawing]

1 to 4 show an embodiment of the present invention,
Fig. 1 is an explanatory diagram of the mounting position of the vehicle height sensor, Fig. 2 is a flowchart showing the operation of the entire suspension system, Fig. 3 is a flowchart showing the subroutine of the switching valve operation request in Fig. 2, Figure 4 is a timing chart showing changes in vehicle height and accumulator internal pressure changes.
The figure is a hydraulic circuit diagram of a conventional suspension device. 11...Solenoid valve, 12a/12b...
Gas-filled accumulator, 13a... variable throttle valve, 15... controller (control means),
16...Vehicle body, 17...Axle, I8...
...Vehicle height sensor, 19a-19b...Link.

Claims (1)

[Claims] a vehicle height sensor that detects the height of the vehicle body relative to the axle; a vehicle height adjustment body that is provided between the vehicle body and the axle to increase or decrease the distance therebetween; and a pressure fluid that supplies pressure fluid to the vehicle height adjustment body. a generating means, a means for adjusting a spring force of a pressure fluid pipe connecting the pressure fluid generating means and the vehicle height adjusting body, a means for adjusting a damping force of the pipe, and an output signal of the vehicle height sensor. control means for controlling the spring force adjustment means and the damping force adjustment means based on the vehicle height, and the control means controls the vehicle height exceeding a preset high vehicle height region or the preset low vehicle height region. When the vehicle height sensor detects a lower vehicle height state, a signal is output to the spring force adjusting means and the damping force adjusting means to increase the spring force and damping force. A hydraulic suspension device that outputs a signal to the spring force and damping force adjusting means in order to reduce the spring force and damping force when the vehicle does not enter a region exceeding the low vehicle height region or a region below the low vehicle height region for a certain period of time or more. .