JPH0154202B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vehicle height adjustment device that is capable of changing the damping force of a hydraulic shock absorber in accordance with a loaded load.

As shown in Figure 1, air suspensions 1, 1, and 1 on the front and rear sides are used as vehicle height adjustment devices.
2,2 and these air suspensions 1,1,
It is equipped with an air compressor 3 that supplies compressed air to the air chambers 1a, 1a, 2a, 2a of 2, 2, and when the vehicle height increases, the air compressor 3 and the air tank 4 are connected to the air supply valve 5 and the switching valve. 6,7
Air suspension 1, compressed air through
1, 2, and 2 to raise the vehicle height, and when the vehicle height reaches the lower region, the air chambers 1a, 1, 2, and 2 of the air suspensions 1, 2, and 2 are supplied to
1a, 2a, and 2a which discharge compressed air to lower the vehicle height are widely used. In the figure, 9 is a pressure switch provided in the air tank 4, and when the pressure in the air tank 4 is below a predetermined value, the pressure switch 9 drives the motor 3a of the air compressor 3 to supply compressed air. Air is supplied to the air tank 4, and when the pressure within the air tank 4 reaches a predetermined value, the drive of the motor 3a is stopped to maintain the pressure within the air tank 4 constant. 10 is a dryer for removing moisture contained in the compressed air supplied from the air compressor 3 to the air tank 4, and 11 is a backflow for preventing the compressed air from flowing back from the air tank 4 to the air compressor 3 side. check valve for prevention,
12 is a check valve for ensuring the minimum pressure of air suspensions 1, 1, 2, and 2; 13 and 14 are cut valves installed between air suspensions 1, 1, 2, and 2, respectively; and 15 is a front car High detection sensor, 16 is rear vehicle height detection sensor, 17
is a controller, and the vehicle height detection sensor 1
5 and 16 detect the vehicle height, and in the vehicle height up region, the controller 17 controls the intake valve 5 and the switching valves 6 and 7.
When the air suspension is opened, compressed air is supplied to the air suspensions 1, 1, 2, and 2 to raise the vehicle height, and conversely, when the vehicle height is lowered, the controller 17 opens the exhaust valve 8 to supply compressed air to the air suspensions 1, 1, and 2. , 2 to lower the vehicle height by discharging compressed air.

By the way, in the conventional vehicle height adjustment device, the hydraulic shock absorber 19 that constitutes the air suspension 1, 1, 2, 2 together with the rolling diaphragm 18, etc. is a cylinder filled with working fluid as shown in FIGS. 2A and 2B. The piston 22 is slidably inserted into the liquid chamber 21 of 20, and the inside of the liquid chamber 21 is connected to the upper and lower chambers 21.
a and 21b, and the piston 22 is provided with a damping force generating means 23 on the extension side and a damping force generating means 24 on the compression side, which allow limited flow of the working fluid. It is formed by protruding a piston rod 25 fixed to the piston 22, and during the extension process of the piston rod 25, the upper chamber 21a becomes high pressure, and the working fluid in the upper chamber 21a is transferred to the damping force generating means 23 on the extension side. from the communication hole 23a of the valve plate 2.
3b is pushed open and flows into the lower chamber 21b while generating a damping force, and conversely, during the compression stroke of the piston rod 25, the lower chamber 21b becomes high pressure, and the working fluid in the lower chamber 21b flows into the damping force generating means 24 on the compression side. communication hole 24
Since the valve plate 24b is pushed open from the valve plate 24b and flows into the upper chamber 21a while generating a damping force, the damping force at the same operating speed of the piston rod 25 remains constant regardless of changes in the vehicle load. Yes, and the damping force setting is usually selected based on the normal live load, so when the car is empty or at maximum load, it is not necessarily the most desirable damping force according to the live load, and therefore the ride quality may be affected. Alternatively, the steering stability was not sufficiently satisfactory.

The present invention solves the above conventional drawbacks and provides a vehicle height adjustment device that can provide a small damping force depending on the live load, that is, a small damping force when the live load is small, and a large damping force when the live load is large. The main structure of this device is to arrange a plunger slidably within the piston rod, introduce the pressure of the air chamber into one end of the plunger, and apply the pressure to this pressure. The plunger slides in response to change the flow area of the orifice, thereby making the damping force variable.

Next, the present invention will be explained based on the drawings from FIG. 3 onwards. In the figure, 26 is a plunger provided at the bottom of the piston rod 25. The plunger 26 consists of a large diameter shaft portion 26b having a communication hole 26a that communicates between the upper and lower surfaces, and a small diameter shaft portion 26c connected to the upper surface of the large diameter shaft portion 26b. In order to slidably attach the plunger 26 having such a configuration, the piston rod 25 has a large diameter hole 27a that opens at the bottom surface of the rod 25, and one end side that opens at the top surface of the large diameter hole 27a. Air suspension 1,
A plunger receiver part 27 is provided with a small diameter hole part 27b connected to the air chambers 1a, 2, and 2, and a large diameter shaft part 26b is connected to the large diameter hole part 27a. Also, the small diameter shaft portion 2 is inserted into the small diameter hole portion 27b.
6c is inserted into the piston rod 25, and the plunger 26 is sealed with the O-rings 28 and 29 between the large diameter hole 27a and the large diameter shaft 26b and between the small diameter hole 27b and the small diameter shaft 26c, respectively. It is slidably attached to a plunger receiver 27 provided at the lower part of the plunger. 30 is a large diameter hole 27a
A coil spring is set at the lower end and presses the large diameter shaft 26b of the plunger 26 against the upper surface of the large diameter hole 27a, 31 is oil filled in the large diameter hole 27a, and 32 is the large diameter hole. Part 27a
The cover plate 33 seals the oil inside, the cover plate 32
This is a diaphragm that forms an air chamber 34 for small-diameter shaft volume compensation between the two.

35 is a boarding house communication orifice which is opened and closed by the plunger 26. The upper and lower chamber communication orifices 35 are connected to the large diameter shaft portion 26 of the plunger 26.
an annular groove 35a formed in the circumferential surface of b; and an annular groove 35a formed in the plunger receiver 27;
It consists of an upper chamber communication groove 35b that connects (communicates with) the upper chamber 21a and the annular groove 35a, and a lower chamber communication groove 35c that connects the annular groove 35a and the lower chamber 21b. When the pressure applied to the upper end surface of the small diameter shaft portion 26c of the plunger 26 is below a predetermined value, the position of the annular groove 35a, the annular groove side port 35b' of the upper chamber communication groove 35b, and the annular groove side port of the lower chamber communication groove 35c. 35c' completely overlaps, the opening degree of the upper and lower chamber communication orifices 35 becomes the maximum, and when the pressure applied to the upper end surface of the small diameter shaft portion 26c of the plunger 26 exceeds a predetermined value, the plunger 26 will release the coil spring. 30 is gradually pushed down against the spring force, and the positions of the annular groove 35a and the ports 35b' and 35c' are shifted, and the upper,
The opening degree of the lower chamber communication orifice 35 is reduced, and the orifice 35 is finally closed. 36 and 37 are air suspension 1,
Passages 38 and 39 are provided in the passages 36 and 37 for guiding the internal pressure of the air chambers 1a, 1a, 2a, 2a to the small diameter hole 27b provided at the lower part of the piston rod 25, diaphragm 4
0 and 41 separate the passages 36 and 37 into air passages 36a and 37a and oil passages 36b and 37b;
Refueling valve provided at 6b, 37b, 44, 45, 4
6 and 47 are cut valves, and these cut valves 4
4, 45, 46, and 47 are designed to open and close in conjunction with oil supply valves 42 and 43. Note that the same parts as in FIGS. 1 and 2 are given the same reference numerals and redundant explanations will be omitted.

Next, its effect will be explained. When the vehicle height reaches the high range, the vehicle height detection sensors 15 and 16 detect this, and the controller 17 closes the exhaust valve 8.
47 to supply compressed air from the air compressor 3 and air tank 4 to the air suspension 1,
The air is supplied to the air chambers 1a, 1a, 2a, 2a of 1, 2, 2 to raise the vehicle height, and when the vehicle height is in the lower region, the vehicle height detection sensors 15 and 16 detect this, and the controller 17 controls the air supply valve. 5 is closed, the selector valves 6, 7, cut valves 44, 45, 46, 47, and exhaust valve 8 are opened to release compressed air from the air chambers 1a, 1a, 2a, 2a of the air suspensions 1, 1, 2, 2 to the outside. to lower the vehicle height. When the cut valves 44, 45, 46, and 47 open during supply and exhaust as described above, the fuel supply valves 42 and 43 also open in conjunction with this.
The air pressure in the air chambers 1a, 1a, 2a, 2a is converted into hydraulic pressure by the accumulators 38, 39 and introduced into the small diameter hole 27b, and applied to the upper end surface of the small diameter shaft 26c of the plunger 26. When the pressure in the air chambers 1a, 1a, 2a, 2a is high and the load is large, the plunger 26 is pushed down against the spring force of the coil spring 30.
Since the diameters of the upper and lower chamber communication orifices 35 are reduced, the damping force of the hydraulic shock absorber 19 is increased. Further, when the pressure in the air chambers 1a, 1a, 2a, 2a is small and the load is small, the plunger 26 is pushed up by the spring force of the coil spring 30.
By enlarging the diameters of the upper and lower chamber communication orifices 35, the damping force of the hydraulic shock absorber 19 is reduced, making it possible to obtain a damping force corresponding to the load.

In the embodiment shown in the drawings, the upper and lower chamber communication orifices 35 are connected to the circular groove 35a and the upper chamber communication groove 35.
b and the lower chamber communication groove 35c are formed by forming a so-called spool mechanism with these grooves 35a, 35b, 35c, so that the upper and lower chambers 21a, 21
This is to ensure that the sliding movement of the plunger 26 is not affected by the pressure fluctuations shown in FIG. Further, the accumulators 38 and 39 are connected to the diaphragm 4 as shown in FIG.
Metal bellows 48, 49 may be used instead of 0,41.

As explained above, the present invention is characterized in that the liquid chambers in the cylinder are separated by a piston, and an orifice is provided between each of these liquid chambers to control the limited displacement flow of the working liquid, and a piston rod fixed to the piston is provided. It comprises a hydraulic shock absorber whose tip sealingly penetrates the cylinder, and an air chamber installed in parallel with the hydraulic shock absorber, and adjusts the vehicle height by supplying and discharging compressed air to the air chamber. In the vehicle height adjustment device, a plunger is slidably disposed within the piston rod, and the pressure of the air chamber is introduced into one end of the plunger, and the plunger slides in response to this pressure to open the orifice. By changing the flow area and making the damping force variable, it is possible to obtain a small damping force depending on the live load, that is, a small damping force when the live load is small, and a large damping force when the live load is large. Therefore, there is an effect that the riding comfort or steering stability of the automobile can be further improved.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a conventional vehicle height adjustment device, Fig. 2 A and B are sectional views of main parts of a conventional hydraulic shock absorber,
Fig. 3 is a sectional view of the main parts of the hydraulic shock absorber of the present invention, Fig. 4 is a block diagram of a vehicle height adjustment device using the hydraulic shock absorber of Fig. 3, and Fig. 5 is a cross-sectional view of the main parts of the hydraulic shock absorber of the present invention. FIG. 1, 1, 2, 2...Air suspension, 1
a, 1a, 2a, 2a...air chamber, 3...air compressor, 19...hydraulic shock absorber, 25...piston rod, 26...plunger, 35...upper and lower chamber communication orifice.

Claims (1)

[Claims] 1 Liquid chambers in the cylinder are separated by a piston, and an orifice is provided between each liquid chamber to control the limited displacement flow of the working liquid, and the tip of the piston rod fixed to the piston seals the cylinder. A vehicle height adjustment device comprising a hydraulic shock absorber penetrating through the hydraulic shock absorber and an air chamber arranged in parallel with the hydraulic shock absorber, and adjusting the vehicle height by supplying and discharging compressed air to the air chamber, A plunger is slidably disposed within the piston rod, and the pressure of the air chamber is introduced into one end of the plunger, and the plunger slides in response to this pressure to change the flow area of the orifice and dampen the plunger. A vehicle height adjustment device characterized by variable force.