JPS6144492Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a vehicle height adjustment device, such as a nose dive type mechanism, which lowers the vehicle height as the vehicle speed increases, and particularly relates to a hydraulic shock absorber of an air suspension that constitutes the vehicle height adjustment device. By using a so-called variable damping force type hydraulic shock absorber in the vehicle to increase the damping force during high-speed running, it is possible to improve running stability during high-speed running.

Generally, as shown in FIG. 1, this type of vehicle height adjustment device has one end fixed to the outer periphery of a hydraulic shock absorber 1 and an outer cylinder 1A of the hydraulic shock absorber 1, and the other end fixed to a piston rod 1B with the other end folded back. A pair of left and right front side air suspensions 3, 3 consisting of a rolling tire flam 2 fixed to an outer shell 1C provided in It is equipped with an air compressor 5 that supplies compressed air to the air chambers 3, 3, 4, and 4, and when the vehicle height increases, the air compressor 5 and air tank 6 are used to supply air to the air supply valve 7, switching valve 8, 9 to compressed air to the air suspension 3, 3,
The compressed air from the air chambers of air suspensions 3, 3, 4, and 4 is supplied to the air chambers of air suspensions 3, 3, 4, and 4 to raise the vehicle height. It is designed to lower the vehicle height by exhausting the air to the outside, and when the vehicle is in the high-speed driving range, the vehicle height can be lowered by the above operation, and the front side air suspension 3, 3 can be The compressed air in the air chamber is discharged to lower the nose of the vehicle, which lowers the vehicle height on the front side. In the figure, 11 is a pressure switch provided in the air tank 6, and when the pressure in the air tank 6 is below a predetermined value, the pressure switch 11 drives the motor 5A of the air compressor 5 to supply compressed air. is supplied to the air tank 6, and when the pressure inside the air tank 6 reaches a predetermined value, the drive of the motor 5A is stopped to keep the pressure inside the air tank 6 constant. 12 is a dryer for removing moisture contained in the compressed air supplied from the air compressor 5 to the air tank 6; 13 is a dryer for preventing the compressed air from flowing back from the air tank 6 to the air compressor 5 side. 14 is the air suspension 3, 3,
4. Check valve for minimum pressure guarantee of 4, 15,
Reference numeral 16 designates cut valves interposed between the air suspensions 3 and 3 and between the air suspensions 4 and 4, respectively. Further, 17 is a front vehicle height detection sensor, 18 is a rear vehicle height detection sensor, 19 is a vehicle speed detection sensor, and 20 is a controller, which detects the vehicle height with the vehicle height detection sensors 17 and 18, and In the up range, the controller 20 opens the air supply valve 7 and the switching valves 8 and 9 to supply compressed air to the air chambers of the air suspensions 3, 3, 4, and 4 to raise the vehicle height. In the vehicle height down region, the controller 20 opens the exhaust valve 10 to discharge compressed air from the air chambers of the air suspensions 3, 3, 4, and 4 to lower the vehicle height, or the controller 20 opens the exhaust valve 10 to lower the vehicle height. 8. The exhaust valve 10 is opened to discharge compressed air from the air chambers of the front air suspensions 3, 3, thereby lowering the vehicle height on the front side.

Incidentally, in this type of vehicle height adjustment device, a conventional hydraulic shock absorber is constructed as shown in FIG.
That is, in the cylinder 1D filled with working fluid,
Communication holes 1 on the upper and lower surfaces that allow limited flow of working fluid
A piton 1H equipped with a damping force generating means 1G consisting of a valve blade 1F that always closes the communication hole 1E is slidably inserted to separate the inside of the cylinder 1D into two upper and lower chambers 1I and 1J, An outer cylinder 1 that surrounds the cylinder 1D at its bottom inside the cylinder 1D.
Reservoir chamber 1K of working liquid formed between A
are communicated through a bottom body 1 equipped with a damping force generating means 1N consisting of a communication hole 1L on the upper and lower surfaces and a valve blade 1M that always closes the communication hole 1L, preferably in the outer cylinder 1A. A pressurized gas 1P for energizing the liquid in the reservoir chamber 1K and the cylinder 1D is sealed, and a piston rod 1B fixed to the piston 1H protrudes from the top of the cylinder 1D. Note that 1Q and 1R are check plates that close the communication holes 1S and 1T, respectively, and 1U and 1V are check plates 1 for each of the communication holes 1S and 1T.
This is a spring with a weak spring force that constantly biases Q and 1R.

Such a hydraulic shock absorber is mounted on a vehicle by fixing the end of the piston rod 1B on the spring side, that is, on the vehicle body side, and the cylinder 1D on the spring side, that is, on the axle side. During the extension stroke of the piston rod 1B, the upper chamber 1I is fixed. The pressure becomes high, and the working fluid in the upper chamber 1I pushes open the valve blade 1F from the communication hole 1E and flows into the lower chamber 1J while creating a flow resistance, that is, a damping force.At the same time, the fluid pressure in the reservoir chamber 1K increases The check blade 1R is easily pushed open from the communication hole 1T and flows into the cylinder 1D to compensate for the withdrawal volume of the piston rod 1B. On the other hand, during the compression stroke of the piston rod 1B, the liquid in the lower chamber 1J pushes up the check plate 1Q from the communication hole 1S of the piston 1H and easily flows into the upper chamber 1I. The gas pushes open the valve plate 1M from the communication hole 1L of the bottom body 1, flows into the reservoir chamber 1K while generating flow resistance, that is, damping force, and further compresses the pressurized gas 1P in the reservoir chamber 1K. In this way, a desired damping force is generated in both the extension and compression strokes depending on the operating feed rate of the piston rod 1B.

Therefore, in the case of such a conventional hydraulic shock absorber, the damping force at the same operating speed of the piston rod 1B is constant regardless of changes in the running speed of the vehicle, and the damping force is normally set at the normal running speed. Therefore, when driving at low or high speeds, the damping force is not necessarily the most preferable depending on the driving speed, and therefore the ride comfort or steering stability is not fully satisfactory.

This invention was developed with the aim of solving the above-mentioned conventional drawbacks, and its gist is that the more the piston rod is pulled out of the hydraulic shock absorber of the air suspension, the lower the damping force will be. This is due to the use of a variable damping force hydraulic shock absorber.

Embodiments of the present invention will be described in detail below with reference to the drawings. Note that the same reference numerals are given to the same constituent parts as in the conventional art, and redundant explanation thereof will be omitted.

3 and 4 are cross-sectional views showing one embodiment of the hydraulic shock absorber used in the vehicle height adjustment device of the present invention. Communicating first orifice, 22
is a second orifice provided in the bottom body 1 and communicating the inside of the cylinder 1D and the reservoir chamber 1K. Further, sleeves 25 and 26 are preferably provided on the inner peripheral sides of the piston 1H and the bottom body 1, respectively, so as to form dart pots 23 and 24 whose volume changes little during high-speed movement of the piston 1H. It is slidably inserted with a gap. These sleeves 2
5 and 26 are connected to each other by receiving a spring force in the direction of separation from each other by a position detection spring 27, and
They are biased toward each other by return springs 28 and 29 loaded in the dart pots 23 and 24, respectively, and when the amount of penetration of the piston rod 1B increases, these sleeves 25 and 26 release the position detection spring 27. The first orifice 21 and the second orifice 22 are slid apart from each other by a spring force, and the first orifice 21 and the second orifice 22 are respectively closed.
When the amount of penetration of the piston rod 1B decreases during low-speed running, the spring force of the return springs 28 and 29 resists the spring force of the position detection spring 27, and the piston rods 1B are slid toward each other in the direction toward each other. , 22 are unblocked.

Since the hydraulic shock absorber of the embodiment has the above-described configuration, it is used in the air suspensions 3 and 4 of the vehicle height adjustment device as shown in FIG. When the compressed air of
Orifices 21 and 22 are closed by sleeves 25 and 26, respectively. When the vehicle runs at high speed in this state, the piston rod 1B repeatedly slides up and down in order to absorb unsprung vibrations that occur due to the unevenness of the road surface. Since this vertical movement is extremely fast, the sleeves 25 and 26 move against the piston 1H.
and the bottom body 1, the dart pots 23 and 24 respectively perform their functions,
The sleeves 25 and 26 remain at the initial position, as if they were integrally connected to the piston rod 1B and the bottom body 1. Therefore, the entire amount of the working fluid displacing and flowing between the upper and lower chambers 1I, 1J and the reservoir chamber 1K is distributed to the damping force generating means 1G of the piston 1E and the damping force generating means 1 of the bottom body 1.
Because it flows through N, a large damping force can be obtained.

On the other hand, when driving at low speeds, if compressed air is supplied to the air chambers of the air suspensions 3 and 4 to raise the vehicle height, the amount of penetration of the piston rod 1B is reduced, and the piston rod 1B returns against the spring force of the position detection spring 27 as described above. The spring forces of the springs 28, 29 cause the sleeves 25, 26 to slide toward each other, and the first and second orifices 21, 22 are no longer blocked by the sleeves 25, 26. When the piston rod 1B moves up and down at high speed in this state, the dart pots 23 and 24 perform their functions and the sleeves 25 and 26 are held at their initial positions, that is, the positions where the first and second orifices are unoccluded. This is the same as in the previous case. Therefore,
A part of the working fluid bypasses not only the damping force generating means 1G and 1N but also the first and second orifices 21 and 22 and is displaced into each chamber 1I, 1J and 1K, thereby obtaining a small damping force. .

In this way, the damping force is changed according to the increase or decrease in the traveling speed, and an appropriate damping force corresponding to the traveling speed can be obtained.

Although FIGS. 3 and 4 show examples in which one first and second orifices 21 and 22 are provided, it is not within the scope of the present invention to arrange a plurality of these in the axial direction. By doing so, the damping force can be changed in multiple stages according to changes in the traveling speed, and a more appropriate damping force can be selected according to the traveling speed. Further, the variable damping force type hydraulic shock absorber is not limited to the one having the above-mentioned structure, but any type may be used as long as the damping force decreases as the amount of piston rod 1B that is extracted increases.

In summary, the present invention includes a hydraulic shock absorber 1, and a roller whose one end is fixed to the outer periphery of the cylinder 1D of the hydraulic shock absorber 1, and whose other end is folded back and fixed to an outer shell 1C provided on a piston rod 1B. It is equipped with a pair of left and right front air suspensions 3, 3 and rear air suspensions 4, 4 that are connected to the tire flam 2, and when driving at high speeds, compression is applied from at least the front air suspensions 3, 3. In a vehicle height adjustment device that lowers the vehicle height by discharging air, at least the hydraulic shock absorber 1 of the front air suspension 3, 3 has the following features:
Since it uses a variable damping force hydraulic shock absorber that reduces the damping force as the piston rod 1B is pulled out, it increases the damping force of the hydraulic shock absorber during high-speed running, thereby reducing the damping force during high-speed running. This has an excellent practical effect of improving running stability.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the vehicle height adjustment device, Fig. 2 is a sectional view of a conventional hydraulic shock absorber, Fig. 3 is a sectional view of the hydraulic shock absorber of the present invention when running at high speed, and Fig. 4 is the same. FIG. 3 is a cross-sectional view when running at low speed. 1...Hydraulic shock absorber, 1A...Outer cylinder, 1B...Piston rod, 1C...Outer shell, 2...
Rolling tire flam, 3, 4...air suspension.

Claims (1)

[Scope of utility model registration request] A hydraulic shock absorber 1, and a rolling tire flam 2 whose one end is fixed to the outer periphery of the outer cylinder 1A of the hydraulic shock absorber 1, and whose other end is folded back and fixed to an outer shell 1C provided on the piston rod 1B.
The vehicle is equipped with a pair of left and right front air suspensions 3, 3 and rear air suspensions 4, 4, and in a high speed driving range, compressed air is discharged from at least the front air suspensions 3, 3. In a vehicle height adjustment device which is designed to lower the vehicle height, the hydraulic shock absorber 1 of at least the front side air suspensions 3, 3 has a damping force that increases as the piston rod 1B is pulled out. A vehicle height adjustment device characterized by using a variable damping force hydraulic shock absorber.