JP2539488Y2 - Oil lock mechanism of hydraulic shock absorber - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil lock mechanism for preventing a bottom end of a hydraulic shock absorber.

[0002]

2. Description of the Related Art In a conventional hydraulic shock absorber, a cylinder is erected in an outer tube, a piston rod is inserted into the cylinder, and a piston which is in sliding contact with the inner peripheral surface of the cylinder is fixed to the lower end of the piston rod. And a valve for forming an oil passage for generating damping force and opening and closing the oil passage.

[0003] As an oil lock mechanism in such a hydraulic shock absorber, a bottom valve mechanism is provided at the bottom of the outer tube (lower part of the cylinder), and the bottom valve mechanism is a bottomed cylindrical member facing the inside of the cylinder. A collar is provided, and an orifice that connects the lower cylinder chamber and the reservoir chamber to the collar via a bottom valve mechanism is formed on the collar. , A check valve is disposed in this piece, and some pieces have an oil hole formed therein.

In the oil lock mechanism of the above-mentioned hydraulic shock absorber, the oil is locked between the piece and the collar by fitting the piece into the collar at the end of the compression stroke of the piston rod. And
At the beginning of the extension stroke, hydraulic oil flows into the collar from the oil hole of the piece via the check valve.

[0005]

However, in the oil lock mechanism of the above-mentioned conventional hydraulic shock absorber, it is necessary to take a certain length of fitting between the piece and the collar, and the basic length becomes long. In addition, since the piece and the collar slide with each other, rust, scratches, abnormal noise, etc. occur, which lowers the durability and reliability. In addition, if the axis of the piece and the collar are misaligned, the operability deteriorates. There is a disadvantage to doing.

[0006]

According to the present invention, a free piston urged upward by a spring is slidably fitted in a bottomed cylindrical member, and a bottomed cylindrical member is provided. A center pin with a tapered tip at the top from the center of the bottom of the member is provided, a through hole is formed in the free piston through which this center pin can be inserted, and the free piston comes into contact with the free piston at the end of the compression stroke. A pressing member is provided at the lower end of the piston rod, and a hollow portion capable of housing the center pin is formed in the pressing member.

[0007]

At the end of the compression stroke, the pressing member provided on the piston rod comes into contact with the free piston and presses against the urging force of the spring, so that the free piston descends and the center pin tip facing the through hole of the free piston. Is tapered, the clearance gradually decreases, the damping force gradually increases according to the position of the piston rod, and finally the hydraulic oil is confined in the bottomed cylindrical member by the free piston. Since the oil lock is applied,
The damping force of the oil lock changes smoothly.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is a cross-sectional view of a main part of a hydraulic shock absorber provided with an oil lock mechanism to which the present invention is applied, FIG. 2 is a cross-sectional view of a main part of the same hydraulic shock absorber in an oil-locked state, and FIG. It is principal part sectional drawing of an Example.

The hydraulic shock absorber is a cylindrical outer tube 1 having a bottom.
A piston 2 is inserted into the cylinder 2 from above, a piston rod 3 is inserted into the cylinder 2 from above, and a piston 4 slidingly in contact with the inner peripheral surface of the cylinder 2 is fixed to the lower end of the piston rod 3. A compression-side oil passage 5 for generating force and an extension-side oil passage (not shown) are formed, and a compression-side valve 7 for opening and closing the compression-side oil passage 5 and an extension-side valve 8 for opening and closing the extension-side oil passage are mounted. ing.

A bottom valve mechanism 10 is provided at the bottom of the outer tube 1 (lower part of the cylinder 2). The bottom valve mechanism 10 forms a compression-side oil passage and an extension-side oil passage 13 (not shown) in the bottom piece 11. The valve 14 for opening and closing the compression-side oil passage and the valve 15 for opening and closing the extension-side oil passage 13 are fixedly mounted with bolts 16. A collar 17 which is a cylindrical member having a bottom is provided on the bottom piece 11 of the bottom valve mechanism 10, and an oil passage for communicating the lower cylinder chamber and the reservoir chamber 18 to the collar 17 via the bottom valve mechanism 10. 19 are formed.

The free piston 2 is provided in the collar 17.
1 is slidably fitted and urged upward by a spring 22 interposed between the bottom and the bottom. A spring 2 having a seal ring 23 fitted on the outer peripheral surface of the free piston 21 and an oil hole 25 formed therein, and a check valve 26 for opening and closing the oil hole 25 interposed between the lock ring 27 and the spring 2.
It is urged and worn at 8. Further, a stopper ring 30 of the free piston 21 is fitted to an upper portion inside the collar 17.

A center pin 3 having a tapered tip portion 31a at the center of the bottom of the collar 17 is provided.
On the other hand, a through hole 32 is formed in the center of the free piston 21, and a bush 33 is fitted on the inner peripheral surface of the free piston 21, and the end 31 a of the center pin 31 faces the bush 33. Not.

On the other hand, a lower end of the piston rod 3 is extended to form a pressing portion 35 which presses against the free piston 21 at the end of the compression stroke, and a rubber ring 36 is fitted on the outer peripheral surface of the lower end of the pressing portion 35. At the same time, a hollow portion 37 that can accommodate the center pin 31 is formed in the pressing portion 35,
An oil passage 38 that communicates the inner portion of the hollow portion 37 with the lower chamber of the cylinder.
Is formed.

The operation of the oil lock mechanism of the shock absorber configured as described above will be described. When the piston rod 3 descends from the state shown in FIG. 1 during the compression stroke, hydraulic oil equivalent to the volume of the piston rod 3 entering from the lower chamber of the cylinder passes through the oil passage 19, the compression-side oil passage (not shown) of the bottom valve mechanism 10, and the reservoir. It flows into the chamber 18.

At this time, the pressing portion 35 descends with the lowering of the piston rod 3, and at the end of the compression stroke of the piston rod 3, the rubber ring 36 of the pressing portion 35 comes into contact with the upper surface of the free piston 21 to further push the piston. As shown in FIG. 2, the center pin 31 is housed in the hollow portion 37 of the pressing portion 35 while the free piston 21 is pressed down against the urging force of the spring 22 by the lowering of the rod 3.

As the free piston 21 descends as described above, the hydraulic oil in the collar 17 firstly receives the bush 33 of the free piston 21 and the tip 3 of the center pin 31.
Although it flows into the cylinder lower chamber from the clearance with 1a, the tip 31a of the center pin 31 is formed in a tapered shape, so that the clearance gradually decreases according to the position of the piston rod 3 and the damping force gradually increases. When the free piston 21 descends beyond the tapered tip portion 31a of the center pin 31, hydraulic oil is sealed in the collar 17 and the oil lock state is established. As a result, the oil lock does not abruptly lock, but the oil lock smoothly locks, and the feeling is improved.

Then, from this state, the piston rod 3 rises in the rebound direction and the pressing portion 35 separates from the free piston 21.
At this time, the check valve 26 is opened and the working oil is replenished into the collar 17 through the oil hole 25.

Next, in another embodiment shown in FIG. 3, the center pin 31 is formed integrally with the bolt 16 of the bottom valve mechanism 10, and is provided upward through the collar 17. is there. By doing so, the bottom valve mechanism 10 can be made into a cartridge.

[0019]

[Effects of the Invention] As described above, according to the present invention,
A free piston is slidably fitted in the bottomed cylindrical member, and at the end of the compression stroke, the free piston is pressed to lock the oil, and a tapered center pin is formed in the through hole of the free piston. , The damping force gradually increases at the time of oil lock, and a sharp rise of the damping force is prevented, so that the feeling is improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a hydraulic shock absorber having an oil lock mechanism to which the present invention is applied.

FIG. 2 is a sectional view of an essential part of the hydraulic shock absorber in an oil locked state.

FIG. 3 is a sectional view of a main part of another embodiment of the present invention.

[Explanation of symbols]

1 ... tube, 2 ... cylinder, 3 ... piston rod, 4
... Piston, 10 ... Bottom valve mechanism, 11 ... Bottom piece, 17 ... Collar (bottomed cylindrical member), 21 ... Free piston, 22 ... Spring, 31 ... Center pin, 32
... through-hole, 35 ... pressing part, 37 ... hollow part.

Claims (2)

(57) [Scope of request for utility model registration] 1. A shock absorber in which a bottomed tubular member is disposed at the bottom of a cylinder lower chamber, and at the end of a compression stroke of a piston rod, hydraulic oil is sealed in the bottomed tubular member and an oil lock is applied. In the oil lock mechanism of the absorber, a free piston urged upward by a spring is slidably fitted in the bottomed tubular member, and the free piston is slid upward from the center of the bottom of the bottomed tubular member. A center pin having a tapered tip is provided, and a free piston is formed with a through hole through which the center pin can be inserted.
Further, at the end of the compression stroke, a pressing member is provided at the lower end of the piston rod for pressing against the free piston.
An oil lock mechanism for a hydraulic shock absorber, wherein a hollow portion capable of housing a center pin is formed in the pressing member. 2. An oil lock mechanism for a hydraulic shock absorber according to claim 1, wherein said center pin is formed integrally with a bolt of a bottom valve.