JPS6141457Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a dual-tube low-pressure gas-filled hydraulic shock absorber.

This type of conventional hydraulic shock absorber has a cylinder arranged concentrically with the outer tube, a piston rod is slidably inserted into the cylinder via a piston, a reservoir is defined between the cylinder and the outer tube, and the piston rod is inserted into the cylinder through a piston. The bearing section of the piston is equipped with a check valve that allows air and oil to flow from inside the cylinder into the reservoir, but conversely prevents air and oil from flowing into the cylinder from the reservoir, preventing air and oil from being sucked into the oil chamber above the piston. It is normal to try to prevent the surface from falling.

Therefore, since the check valve is interposed in the compression operation of the shock absorber,
The oil chamber above the piston may tend to have negative pressure,
If this happens, cavitation may occur in the upper oil chamber of the piston, which may cause distortion of the damping force characteristics, which is undesirable, and may also generate abnormal noise.

Therefore, the purpose of this invention is to eliminate the check valve on the bearing part, install the oil level drop prevention valve on the base valve side, and partition the oil reservoir chamber above the bearing to separate the liquid chamber above the piston and the gas chamber in the reservoir. The oil lip of the oil seal is immersed in the oil in this oil reservoir chamber to create a liquid seal structure, which ensures a gas seal.
To provide a dual-tube low-pressure gas-filled hydraulic shock absorber that simplifies the upper seal part, prevents capitation in the oil chamber above the piston, and stabilizes damping force characteristics.

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

A cylinder 2 is inserted concentrically into the outer shell 1, a bearing 3 and a packing case 4 are fixed to the heads of the outer shell 1 and the cylinder 2, and the lower end of the outer shell 1 is connected to a lower cap 5.

A piston rod 7 is slidably inserted into the cylinder 2 via a piston 6. The piston 6 defines two upper and lower liquid chambers A and B within the cylinder 2, and the piston rod 7 passes through the bearing 3.

A disk 10 serving as a valve case in the base valve device 9 is fixed to the lower end of the cylinder 2. Legs 35 provided at the lower end of the disk 10 stand up on the lower cap 5, and the disk 10 has a liquid chamber inside the lower cap 5. C is divided.

A reservoir is formed between the outer shell 1 and the cylinder 2, and this reservoir consists of a lower liquid chamber D and an upper gas chamber E.

Valve members 6a and 6b for opening and closing two upper and lower liquid chambers A and B and passages 7a and 7b are provided in the piston 6 to generate a damping force during expansion.

The liquid chamber C in the lower part of the disk and the liquid chamber D in the reservoir communicate with each other via a passage provided in the leg portion 35.

A support rod 15 is inserted and fixed in the center of the disk 10, and upper and lower flanges 16,
17 are provided. The disk 10 is provided with one or more pressure side ports 18 and expansion side suction ports 19 to connect the upper and lower liquid chambers B and C.

Valve seats 20 and 21 are protruded from the disk 10, and a check valve 22 made of a plate valve is placed on the valve seats 20 and 21 so as to be openable and closable. A spring or other similar spring member 23 is interposed,
In the stationary state, the check valve 22 is pressed against the valve seats 20 and 21 by the spring member 23 to close the port 19, and when extended, the check valve 22 closes the port 19.
The hydraulic oil from the check valve 22 pushes open the check valve 22 against the spring member 23.

A through hole 24 is formed in the check valve 22, and the pressure side port 18 is always opened to the liquid chamber B at the lower portion of the piston through the through hole 24.

At the lower end of the disk 10, an oil level drop prevention valve 27 consisting of a plate valve is provided at the mouth end of the pressure side port 18 so as to be openable and closable, thereby opening and closing the port 18 toward the liquid chamber C side. The oil level drop prevention valve 27 is supported at its base end by a valve support member 26 held by the flange 17, and is set to have an initial load at least equivalent to the weight of oil in the cylinder.

Next, a guide 28 is interposed on the inner circumference of the bearing 3, and the piston rod 7 is guided inside the guide 28.
The outer periphery of the ring is designed to make sliding contact.

An oil reservoir F is defined at the upper end of the bearing 3.
Further, a return port 29 is formed in the upper part of the oil reservoir chamber F so as to be of an overflow type, and this return port 29 allows the oil reservoir chamber F and the gas chamber E to communicate with each other.

Oil seal 30 is inside the packing case 4.
An insert metal 31 having an L-shaped cross section is embedded in the main body of the oil seal 30 to reinforce the main body. The insert metal 31 is built in in the opposite direction to the conventional one, so that the volume of the oil reservoir chamber F is formed to be large.

The main body of the oil seal 30 is provided with a dust lip 32 and an oil lip 33 in the vertical direction, and these lips 32 and 33 are pressed by rings 34 and 35 on the outer periphery to come into close contact with the outer periphery of the piston rod 7, and the dust lip 32 is It prevents dust from entering, and the oil lip 33 prevents oil from leaking to the outside.

Oil is stored in the oil reservoir chamber F, and an oil lip 33 is immersed in the oil surface, which prevents gas from the gas chamber E from entering the liquid chamber A in a liquid-sealing manner. There is.

Next, we will discuss the operation.

In a stationary state, the outlet of the pressure side port 18 is closed by the oil level drop prevention valve 27, so the hydraulic oil in the liquid chamber B at the bottom of the piston does not escape to the liquid chambers C and D, so the oil level does not drop. do not have.

Further, during extension, the piston 6 rises, and at this time, the damping force generator inside the piston 6 generates an extension-side damping force, and at the same time, the liquid chamber B expands, so that the spring member 2
3, the check valve 22 opens to prevent negative pressure from being sucked into the hydraulic fluid in the fluid chambers C and D through the expansion side suction port 19. In this case, the valve 27 is closed and does not participate in the extension stroke. Furthermore, during compression, the piston 6 descends and the liquid chamber B is reduced, but at this time, when the compression starts, the internal pressure of the liquid chamber B increases and the hydraulic oil flows out from the pressure side port 18, and this pressure causes the oil level drop prevention valve 27 to flow out.
is pushed open against the spring force. When the compression speed increases, a normal compression side damping force is generated due to the flow resistance of the hydraulic oil from the compression side port 18.

That is, during compression, oil in chamber B moves to chamber A, and at the same time, oil approximately equivalent to the volume entered by the piston rod is throttled by port 18 of base valve 9 and flows into liquid chambers C and D.

Furthermore, in a stationary state, conventionally, the pressure in the liquid chambers A and B and the reservoir chambers D and E is the same, so oil flows into the reservoir through the pressure side port of the base valve due to the weight of the oil in the cylinder, causing the oil to flow into the reservoir through the pressure side port of the base valve. Normally, the oil level in the reservoir becomes the same, but in the case of the present invention, the oil level is maintained by the oil level fall prevention valve 27 provided at the mouth end of the pressure side port 18 of the base valve section 9. Falling is prevented, and since the oil lip 33 of the oil seal 30 is also submerged in oil due to the oil reservoir chamber F above the bearing 3, it becomes an oil-immersed seal for both the liquid chamber A inside the cylinder and the outside of the cylinder. Gas sealing can be achieved reliably, and stable damping force characteristics can be obtained without disturbance of damping force characteristics due to gas leakage or gas incorporation.

Next, FIGS. 4 and 5 relate to other embodiments of the present invention in which the base valve portion is modified, but the functions and effects thereof are exactly the same as in the case of FIG. 1.

That is, a support rod 15 is inserted and fixed in the center of the disk 10, and this support rod 15 is provided with upper and lower flanges 16 and 17. The disk 10 is provided with one or more pressure side ports 18 and expansion side suction ports 19 to connect the upper and lower liquid chambers B and C.

Valve seats 20 and 21 are protruded from the disk 10, and a check valve 22 made of a plate valve is placed on the valve seats 20 and 21 so as to be openable and closable. A spring or other similar spring member 23 is interposed,
In a stationary state, the check valve 22 is pressed against the valve seats 20 and 21 by the spring member 23 to close the port 19, and when extended, the check valve 22 closes the port 19.
The hydraulic oil from the check valve 22 pushes open the check valve 22 against the spring member 23.

A through hole 24 is formed in the check valve 22, and the pressure side port 18 is always opened to the liquid chamber C at the lower part of the piston through the through hole 24.

On the lower side of the disk 10, a valve seat 36 is provided to protrude downward from the mouth end of the opening 18a communicating with the pressure side port 18, and a pressure side damping valve 37 consisting of a plate valve is disposed on this valve seat 36 so as to be openable and closable. The port 18 and the opening 18a are opened and closed.

On the flange 17 of the support rod 15, a support plate 38, a spacer 39, and an oil level fall prevention valve 27 are held in an overlapping manner, and the base end of the valve 27 is supported on the spacer 39.

The valve 27 is a cup-shaped elastic leaf valve that is initially loaded with at least the weight of oil in the cylinder, and this valve 27 is opened and closed at the outlet end of the pressure side port 18, that is, on the upstream side of the pressure side damping valve 37. It is freely disposed, and when it is at rest, it closes the pressure side port 18 by its own elasticity, and prevents the hydraulic oil from flowing out from the pressure side port 18 to the opening 18a and the liquid chamber C side.

In a stationary state, the outlet of the pressure side port 18 is closed by the oil level drop prevention valve 27, so the hydraulic oil in the liquid chamber B at the bottom of the piston does not escape to the liquid chambers C and D, so the oil level does not drop. do not have.

Therefore, even if a stamped orifice is formed in the valve seat 36 and the opening 18a is always communicated with the liquid chamber C, the oil level does not drop.

Also, during extension, the piston 6 rises, and at this time, the damping force generator inside the piston 6 generates an extension-side damping force, and the liquid chamber B expands, so the check valve 22 opens against the spring member 23, and the liquid Hydraulic oil in chambers C and D is sucked in through the extension side suction port 19 to prevent load. In this case, the valve 27 is closed and does not participate in the extension process. Furthermore, during compression, the piston 6 descends and the liquid chamber B is reduced, but at this time, when the compression starts, the internal pressure of the liquid chamber B increases and the hydraulic oil flows out from the pressure side port 18, and this pressure causes the valve 27 to respond to the spring force. It resists and is pushed open. When the compression speed increases, the hydraulic oil from the compression side port 18 pushes open the compression side damping valve 37, and the compression side damping valve 37 generates a normal compression side damping force.

As described above, the present invention provides the oil level drop prevention valve 27 in the base valve part 9, and also divides the oil reservoir chamber F above the bearing 3, and divides the oil reservoir chamber into a liquid chamber above the piston and a gas chamber in the reservoir. The oil lip 33 of the oil seal is immersed in this oil reservoir chamber F, and the check valve from above the bearing 3 is eliminated. By eliminating the check valve, the upper seal part can be simplified, and cavitation in the liquid chamber A above the piston can be prevented, and abnormal noise can be prevented from occurring due to this. This makes it possible to ensure the stability of the damping force characteristics immediately after the start of operation.
Furthermore, by immersing the oil lip in the oil reservoir chamber, gas can be reliably sealed in a liquid-sealing manner.

[Brief explanation of the drawing]

Fig. 1 is a vertical side view of a hydraulic shock absorber according to an embodiment of the present invention, Fig. 2 is an enlarged sectional view of the bearing section, Fig. 3 is an enlarged sectional view of the base valve section, and Fig. 4 is an enlarged sectional view of the base valve section.
5 is a vertical sectional side view of a hydraulic shock absorber according to another embodiment of the present invention, and FIG. 5 is an enlarged sectional view of the base valve portion of FIG. 4. 1...Outer shell, 2...Cylinder, 3...
... Bearing, 6 ... Piston, 7 ... Piston rod, 9 ... Base valve, 18 ... Port,
23...Check valve, 27...Oil level drop prevention valve,
29...Return port, 33...Oil lip, 37...Valve, D, E...Reservoir, F...Oil sump chamber.

Claims (1)

[Scope of claim for utility model registration] (1) A cylinder is arranged concentrically within an outer shell, a reservoir is defined between the outer shell and the cylinder, and a piston rod is slidably inserted into the cylinder via a piston. In a hydraulic shock absorber, the piston rod passes through a bearing at the upper end of the cylinder, and a base valve equipped at the lower end of the cylinder is equipped with compression side damping force generating means and a check valve for suction during extension operation. An oil reservoir is partitioned into the oil reservoir, the oil reservoir is interposed between the liquid chamber above the piston and the gas chamber of the reservoir, and the oil lip of the oil seal is immersed in the oil reservoir, and the damping force generating means is A dual-tube low-pressure gas-filled hydraulic shock absorber, in which an oil level fall prevention valve having an initial load equivalent to at least the weight of the oil in the cylinder is disposed on the reservoir side port surface of the cylinder so as to be openable and closable. (2) The dual-tube low-pressure gas-filled hydraulic shock absorber according to claim 1, wherein the damping force generating means is a valve or a port. (3) The dual-tube low-pressure gas-filled hydraulic shock absorber according to claim 1, wherein the liquid chamber above the piston communicates with the gas chamber of the reservoir via an overflow oil storage chamber. (4) A dual-tube low-pressure gas-filled hydraulic shock absorber as set forth in claim 1 or 4 of the utility model registration claim, which is provided with a return port above the oil reservoir chamber.