JPS596106A - Controllable equipment for spring characteristic of air suspension for automobile - Google Patents

Abstract

PURPOSE:To promote the stability of driving, by providing a spring characteristic control solenoid valve for opening or closing the communication passage between the main and auxiliary sections of an air chamber to cause changeover to a large spring constant appropriate to driving on a bad road. CONSTITUTION:The signals of vehicle height sensors 19 provided at air suspension units A, B, C, D are entered into a controller 5 to regulate the opening and closing of solenoid valves L1-L6. When the air suspension unit A is lowered, the controller 5 opens the valves L1, L3 on the basis of the raising signal of the height sensor 19 to deliver air into the air chamber 13 of the suspension unit A to increase the vehicle height thereat. A passage 18 for communication between the main and auxiliary sections 13a, 13b of the air chamber 13 is opened or closed by a spring characteristic control valve S to control changeably the dynamic spring constants of the air suspension units.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for varying the spring characteristics of air suspensions for automobiles.

When the spring characteristics of an automobile suspension are softened with emphasis on ride comfort, problems arise with stability on rough roads.

Conventionally, air suspensions have been used to change vehicle height depending on heavy speed (see I Samurai Publication No. 82616/1982).
There have also been developed systems that variably open the spring reaction force according to the sprung door speed (inertial force) (see Japanese Patent Application Laid-Open No. 1983-44167), but none of them are effective when driving on rough roads. It is not possible to accurately deal with the problem of running stability.

The present invention provides a device that accurately detects rough road running conditions in an air suspension and, based on the detection, switches the spring characteristics to a high spring constant suitable for running on rough roads, thereby improving riding comfort during normal driving. The present invention is intended to improve not only the driving stability but also the driving stability when driving on rough roads.

FIG. 1 is a diagram showing an example of a control system for an air suspension according to the present invention. In FIG. 1, 1 is a compressor, 2 is a dryer, and 3 is a reserve tank. 2 and the solenoid pulp L1, it is stored in the reserve tank 3. 4 is a pressure sensor that detects the air pressure in the reserve tank 3, and the operation of the compressor 1 is controlled by the signal from the pressure sensor 4 to maintain the air pressure in the reserve tank 3 at a predetermined value. There is.

4-wheel air suspension A and B on the front, rear, left and right sides.

The air supply paths that supply air from the reserve tank 3 to the air chambers C and D are provided with supply and exhaust solenoid pulps Ls + L4 + Ls and L6, respectively. L2 is an exhaust solenoid pulp.

Each of the air suspensions A, B, C, and D is provided with a vehicle height sensor 19 (see FIG. 2), and the signal from each vehicle height sensor is input to the control device 5, and based on the signal, the control device f5 is each solenoid pulse 7”L+r L2 + L3t L4r Ls
r It is designed to control the opening and closing of L6.

That is, for example, when the air suspension in A is lowered, the vehicle height sensor in A issues an up signal, and based on the up signal, the control device it5 activates the solenoid pulp L1.
It issues an output signal to open Ls and supplies the air in the reserve tank 3 to the air chamber of the air suspension A to raise the vehicle height, and when the vehicle height reaches a predetermined value, the solenoid pulp is activated by the signal from the vehicle height sensor. l, +, close IA.

On the other hand, for example, if air suspension A is too high and smooth,
The vehicle height sensor issues a down signal, and based on that signal, the control device 5 issues an output signal to open the solenoid valves L2 and Ls, and the air in the air chamber of the air suspension A is discharged to the outside to raise the vehicle height. is lowered, and at a predetermined height, L2 and Ls are closed by the signal from the vehicle height sensor.

Similarly to the above, the vehicle heights of the B, C, and D air suspensions are controlled by their respective vehicle height sensors, so that the vehicle height of each air suspension is always maintained at a constant value.

6 is a drive system sensor that detects whether the drive system is two-wheel drive or four-wheel drive; i is a vertical acceleration sensor;
The signals from these sensors 6.7 are input to the control device 5, and when the control device 5 determines that the vehicle is traveling on a rough road based on these signals, the solenoid for controlling the spring characteristics of the air suspensions A, B, C, 1) The air suspension is configured to generate an output signal to activate the loop S and increase the spring constant of each air suspension.

An example of the spring characteristic control mechanism of the air suspension will be explained with reference to FIG. 2.

As shown in FIG. 2, the air suspension includes a lower tank 14. It has a structure in which an airtight air chamber 13 is formed by an upper tank 15, a diaphragm 16, etc., and the air chamber 13 is divided into two chambers, a main chamber 13a and a sub chamber 135, by a partition wall 17.

The air chambers 13α and 136 communicate through a communication passage 18, and the communication passage 18 is controlled to open and close by a solenoid pulp S for controlling spring characteristics.

Reference numeral 19 denotes a vehicle height sensor consisting of a drive magnet 19α attached to the outer cylinder 11i+++j and a magnetic response switch 19b housed on the rod 12 side.
As described above, the signal is input to the control device d5 and the vehicle height is automatically adjusted.

In the above configuration, when the solenoid pulp S opens the communication path 18, the main chamber 13α and the sub chamber 13b communicate with each other through the communication path 18, and the effective volume of the air chamber that acts as a spring is the volume of 13α and 13A. V which is the sum of VA and VB
It becomes A + VB.

When the solenoid valve S closes the communication passage 18, the auxiliary chamber 13
The air in A completely acts as a spring, and the effective volume of the air chamber that acts as a spring is only the volume vA of the main chamber 13α, which is smaller than when the communicating path 18 is open.

Generally, the dynamic spring constant of an air suspension is lower as the effective volume of the air chamber becomes larger, and higher as the effective volume becomes smaller.

Therefore, as mentioned above, the communication passage 18 is connected to the solenoid valve S.
By controlling the opening and closing of the air suspension, the dynamic spring constant of the air suspension can be variably controlled.

On the other hand, in cars that are designed to switch between two-wheel drive (referred to as 2WD) and four-wheel drive (referred to as '4WD), 2WD is used during normal driving, and when driving on rough roads, rainy days, on packed snow roads, or on icy roads. When it is necessary to prevent slips such as burns, it is common to switch to 4WD.

Therefore, in the present invention, as shown in FIG.
When the drive system is 4WD and the vertical acceleration of the vehicle is above a predetermined value, it is determined that the vehicle is traveling on a rough road, and the solenoid valve S for controlling the spring characteristics is actuated. By providing a rough road judgment circuit in the control device 5 that closes the passage 18, the communication passage 18 is opened when driving on a good road, increasing the effective volume of the air chamber and providing soft spring characteristics to improve riding comfort. At the same time, on rough roads, the communication passage 18 is closed, the effective volume of the air chamber is reduced, and stiff spring characteristics are used to significantly improve running stability and running performance on rough roads.

An example of the rough road determining circuit is shown in FIG. 6.

In FIG. 3, the signal of the vertical acceleration sensor γ is converted into a voltage, and the signal is converted into a voltage between the reference voltage generating circuit 80 and the reference voltage and the comparator COMP.
When the vertical acceleration is smaller than a predetermined value, the output signal of the comparator COMP becomes 0. When the output signal is 1
shall be. It is also assumed that the drive system sensor 6 emits a signal of 1° when the vehicle is in 4WD and 0 when the vehicle is in 2WD.

If the vertical acceleration is below the predetermined value when driving in 4WD,
The output signal of the comparator COMP is O, which is the knot N
The output of the AND circuit ANDI becomes 1 and is input to the bistable multivibrator BM since the signal from the drive system sensor 6 is 1.

On the other hand, the output signal 0 of the comparator COMP is directly input to the bistable multivibrator BM, and in this state, the output of the bistable multivibrator BM is Ot.

The output signal of the bistable multivibrator BM is inputted to the second AND circuit AND2, ANDed with the signal of the drive method sensor 6, and the output of the AND circuit AND2 is inputted to the spring characteristic switching circuit 9. When the output of the bistable multivibrator BM is 00 as in the case of Mizuho Kamioka, the output of AND2 is 0, and the solenoid valve S for controlling the spring characteristics maintains the communication path 18 open.

When the signal from the drive system sensor 6 is 00, that is, when the drive mode is 2WD, the output of AND2 is 0 regardless of whether the output of the bistable multivibrator BM is 0 or 1, and the solenoid valve S for controlling spring characteristics is connected to the communication path 18 as described above. It is in an open state.

In the 4WD state, when the vertical acceleration exceeds a predetermined value and the output signal of the comparator COMP becomes 1, the input signal of the bistable multivibrator BM changes from 1, 0 to 0, 1, and its output becomes 1. The output of AND2 becomes 1,
The spring characteristic control solenoid valve S is operated, the communication passage 18 is closed, and the spring constant is switched to a high value.

As described above, according to the present invention, it is possible to accurately judge the driving condition on a rough road, soften the spring characteristics of the suspension on roads other than rough roads to improve riding comfort, and switch to harder spring characteristics on rough roads to stabilize driving. It is possible to significantly improve the vehicle's performance and ability to travel on rough roads, and together with its simple structure and reliable functionality, it can bring about great practical effects.

Although the embodiment shown in FIG. 2 shows an example in which the interior of the lower tank 14 is partitioned to form the auxiliary chambers 13 and 6 within the lower tank 14, the auxiliary chamber 13b may be formed within the upper tank 15.

[Brief explanation of the drawing]

Fig. 1 is an air suspension control system diagram showing an embodiment of the present invention, and Fig. 2 is a diagram showing an example of the structure of the air suspension according to the present invention.
b) It is an enlarged sectional view of the X section in the figure. FIG. 6 is a block diagram showing an example of a rough road determination circuit. A, B, C, l)...Air suspension, S...
Spring characteristic control valve, 6... Drive system sensor, 7... Vertical acceleration sensor, 9... Spring characteristic switching circuit, 10... Telescopic member, 11... Cylindrical body, 12...
...Rod, 13...Air chamber, 13α...Main chamber, 13h...Sub-chamber, 1T...Division wall, 18...
Communication path, 19...Vehicle height sensor. 1. Leap (I) 2.

Claims (1)

[Claims] Using an air suspension, an air chamber with air sealed inside is formed on the outer periphery of an extensible member consisting of a cylinder and a rod fitted so as to be able to slide in the axial direction.
In an automobile capable of switching between two-wheel drive and four-wheel drive, the air chamber of the air suspension is divided into a main chamber and a sub-chamber, and a communication passage connecting the main chamber and the sub-chamber and a communication passage are provided. A solenoid pulp for controlling spring characteristics is provided to control opening and closing, and when the vertical acceleration is greater than a predetermined value in four-wheel drive, it is determined that the vehicle is traveling on a rough road, and the solenoid pulp for controlling spring characteristics is switched to the communication path closed state. A spring characteristic variable device for an air suspension for an automobile, characterized by being provided with a rough road judgment circuit.