JPS5819390Y2 - Dual cylinder type gas filled shock absorber - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a double-tube gas-filled shock absorber.

Generally, a double-tube type gas-filled shock absorber has an outer tube arranged in the same role as the cylinder, and a piston rod is slidably inserted into the cylinder via a piston, and the piston has two upper and lower liquid chambers inside the cylinder. The outer tube is further divided into a lower liquid chamber and an upper gas chamber, and the two lower liquid chambers are communicated with each other through an orifice of the cylinder.

Further, the piston is usually provided with damping valves for the expansion side and the compression side, and the gas chamber is normally filled with pressurized gas of about 10 kg/-.

In such a shock absorber, when the piston rod moves to the extension side, oil in the liquid chamber in the upper part of the piston is throttled by the extension-side damping valve in the piston portion and flows to the lower liquid chamber.

At this time, the pressure in the upper liquid chamber increases and a damping force is generated.

Further, as the volume of the lower liquid chamber increases, the hydraulic oil is replenished by the amount flowing from the upper liquid chamber and the amount flowing from the orifice.

During pressure-side operation, the oil in the lower liquid chamber of the piston is throttled by the pressure-side damping valve in the piston section and the orifice in the lower part of the cylinder, and flows into the upper liquid chamber and the liquid chamber below the gas chamber.

At this time, the pressure in the lower liquid chamber increases and a damping force is generated, and the replenishment of hydraulic oil accompanying the increase in the volume of the upper liquid chamber is filled by the amount flowing from the lower liquid chamber.

However, in the above-mentioned conventional shock absorber, when the compression side damping force characteristics become high, the orifice bored in the cylinder must also be made small.As a result, when the piston speed is high or the excitation cycle is high, the liquid from the lower part of the piston flows from the liquid chamber below the gas chamber. The time required to send oil into the chamber becomes shorter, resulting in insufficient oil suction and the waveform of the damping force characteristics being disturbed.

Furthermore, if the shock absorber is left stationary for a long time, the oil level in the cylinder will drop and gas will enter.

When the next operation is performed in this state, the gas in this cylinder must be immediately sent to the gas chamber to fill the cylinder with oil.

Considering the process of sending gas here, when the piston rod extends, the gas in the piston upper liquid chamber passes through the communication hole of the bearing and returns to the gas chamber, and as the volume of the piston lower liquid chamber increases, hydraulic oil is replenished at the piston upper part. This is done by drawing in from the liquid chamber below the liquid chamber and gas chamber.

However, when the orifice is small or the pressure difference between the piston lower liquid chamber and the gas chamber lower liquid chamber is small, there is a problem that the replenishment flow rate is small and it takes time to return to normal.

In order to solve this problem, it is possible to increase the pressure in the gas chamber and increase the orifice area, but on the other hand, it may cause gas leakage due to defects in gas sealing, problems in handling the shock absorber, or problems at low temperatures. When the gas pressure decreases, the damping force is affected by this gas pressure, and the waveform of the damping force characteristic is disturbed.

Therefore, in order to solve the above problem without increasing the gas pressure, a method has been considered in which a valve housing is fitted in series to the lower end of the cylinder and a check valve is provided therein so that it opens when it is extended and closes when it is on the pressure side. Since one purpose of the double-tube gas-filled shock absorber is to shorten the basic length, it is not preferable to lengthen the basic length by providing a valve housing for installing a check valve in series at the lower end of the cylinder.

An object of the present invention is to provide a double-tube gas-filled shock absorber that has improved damping force characteristics, shortens damping force return time, has a small axial dimension, and is inexpensive.

In order to achieve this objective, the present invention forms an annular valve case located inside the outer tube in the lower liquid chamber.
The inner tube is passed through the center of the valve case to support the centering of the inner tube, and a bottom side liquid chamber is defined below the valve case, and this bottom side liquid chamber is communicated with the liquid chamber below the piston, and the valve case It is characterized by communicating with the liquid chamber below the gas chamber through an orifice and a check valve provided in the gas chamber.

An example of implementing the present invention will be described below with reference to the drawings.

In the shock absorber according to the present invention, a bearing 2 is fixed to the upper end of an inner tube 1 which is a cylinder as in the conventional case, and a piston rod 3 is disposed inside the inner tube 1.
a is slidably inserted through a piston 3, and the piston 3 defines two upper and lower liquid chambers 4 and 5 within the inner tube 1.

A seal cover 6 is fitted above the bearing 2, a seal 7 is disposed within the seal cover 6, and a piston rod 3a passes through the bearing 2 and the seal 7 to the outside.

An outer tube 8, which is integral with the seal cover 6 and plays the same role as the inner tube 1, is connected to the lower part of the seal cover 6, and a gas chamber 10 and a liquid chamber 14 below the gas chamber 10 are defined between the inner tube 1 and the outer tube 8. ing.

Through holes 11 and 12 are bored in the bearing 2, and this through hole 1
1.12 communicates the liquid chamber 4 and the gas chamber 10, and the through hole 12
An elastic member 13 forming an annular oil reservoir is interposed at the side mouth end of the gas chamber 10, and oil and gas leaking from the liquid chamber 4 when the piston 3 extends passes through the oil reservoir formed by the elastic member 13 and overflows. The oil discharged into the gas chamber 10 drips down to the liquid chamber 14 below the gas chamber 10.

Note that the elastic member 13 is provided through the through hole 1 instead of the illustrated embodiment.
It may be a one-way valve that only opens and closes at the gas chamber mouth end of the second gas chamber.

A well-known damping force generating device on the extension side is built into the piston 3.

Next, as a gist of the present invention, an annular valve case 15 is integrally attached to the lower inner side of the outer tube 8 and is located in the annular liquid chamber and serves as a radial support member for the inner tube. An inner tube 1 passes through the center of the tube and extends to the bottom end.

A liquid chamber 16 is defined below the valve case 15, and a communication hole 17 with low resistance is bored in the inner tube 1.
The two liquid chambers 5 and 16 communicate with each other through the communication hole 17.

The valve case 15 has an orifice 18 and a through hole 1 in the axial direction.
A check valve 20 is provided in the through hole 19 so as to be openable and closable, and this check valve 20 allows oil in the liquid chamber 16 to flow to the liquid chamber 14 above. When the pressure in the liquid chamber 16 becomes negative, a check valve 20 is opened to allow oil from the liquid chamber 14 to be sucked in through the through hole 19.

In the above-mentioned shock absorber, when the piston 3 descends and compresses, the liquid chamber 4 expands, but the oil in the liquid chamber 5 is refilled by the increased volume because the oil in the liquid chamber 5 flows out through the valve mechanism inside the piston 3. At this time, the lower liquid chamber 5 contracts and the internal pressure rises, and part of the oil in the liquid chamber 5 flows out into the liquid chamber 16 through the communication hole 17, and the oil in the liquid chamber 16 flows through the orifice 18. The liquid flows out to the outer liquid chamber 14 through the orifice 1.
The damping force on the compression side can be obtained by the action of 8.

On the other hand, when the piston 3 rises and is on the rebound side, the liquid chamber 4 contracts, and at this time, the oil inside flows out to the liquid chamber 5 side through the valve mechanism inside the piston 3, and the valve mechanism reduces the damping during the rebound side. force is generated.

Also, at this time, the liquid chamber 5 expands, but in this case, the oil in the outer liquid chamber 14 is absorbed and flows from the orifice 18 to the liquid chambers 16, 5.
At the same time, the check valve 20 is opened against the spring and the oil flows out from the through hole 19 to the liquid chamber 5 side, and the amount of oil corresponding to the increased volume of the liquid chamber 5 is compensated for, thereby preventing insufficient suction.

As described above, in the shock absorber of the present invention, an annular valve case is formed by being positioned inside the outer tube in the lower liquid chamber, and the inner tube is sealed and penetrated through the center of the valve case, so that the centering of the inner tube can be supported. .

Furthermore, since the check valve is built into the valve case, the sliding stroke of the piston 3 in the inner tube 1 can be made large, and the basic length of the shock absorber can be shortened.

Furthermore, since the damping force on the pressure side is generated by the orifice 18, it is not affected by the gas pressure in the gas chamber 10, and even if there is a gas leak, the waveform of the damping force characteristic will not be disturbed.

Furthermore, during the expansion side operation, good oil suction performance by the check valve 20 can be ensured, and cavitation will not occur.

Furthermore, the valve case 15 itself in which the check valve 20 and the like are built-in has a compact structure and is only installed on the outer tube 8 side, so it is economically inexpensive.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway vertical side view of a shock absorber according to an embodiment of the present invention, and FIG. 2 is a vertical side view of the shock absorber. 1... Inner tube, 3... Piston, 4,5
...Liquid chamber, 8...Outer tube, 10...Gas chamber, 14...Liquid chamber, 15...Valve case, 16
...liquid chamber, 17...communication hole, 18...oris,
19...Through hole, 20...Check valve.

Claims (3)

[Scope of utility model registration request] (1) A shock absorber in which an outer tube is installed in the same role as the inner tube, two liquid chambers are defined within the inner tube via a piston, and an upper gas chamber and a lower liquid chamber are defined within the outer tube. An annular valve case is formed by being positioned inside the outer tube in the lower liquid chamber, and an inner tube is closely passed through the center of this valve case to support centering of the inner tube, and the annular valve case is A bottom side liquid chamber is defined below, and this bottom side liquid chamber communicates with the liquid chamber below the piston through a communication hole bored in the inner tube, and is connected to an orifice for generating a compression side damping force cut in the valve case. It communicates with the liquid chamber below the gas chamber through the side suction hole, and a check valve is installed in the hole so that it can be opened and closed freely to prevent the oil in the bottom side liquid chamber from flowing back into the liquid chamber below the gas chamber. A double-tube gas-filled shock absorber. (2) A double-tube gas-filled shock absorber according to claim (1) of the patent registration, wherein the communication hole is sized to reduce resistance. (3) A dual-tube gas-filled shock absorber according to claim (1) of the utility model registration, in which the valve case is integrally formed with the outer tube.