JPH0419255Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field] The present invention is a shock absorber, in particular, a shock absorber that uses the braking force generated on a piston moving in a fluid sealed in a cylinder to smoothly absorb dynamic load energy and stop it. This invention relates to a shock absorber that can be

[Background technology]

As this type of shock absorber, one having the following structure has been proposed.

That is, a piston that is movable in the axial direction of the cylinder and a piston rod that moves together with the piston are provided in a cylinder that is closed at one end, and after fluid is injected into the cylinder, the open end of the cylinder is closed by a sealing member. This shock absorber has a structure that applies a moving body load to a piston rod that is sealed and protrudes to the outside of the cylinder through the sealing member, and smoothly absorbs the moving body load energy.

In this case, the following structure can be considered as a structure that generates a large braking force during the load energy absorption operation and reduces the braking force when the piston rod returns to realize a quick return operation.

In other words, a pair of rod seat parts with a gap larger than the width of the piston are provided at positions sandwiching the piston that is loosely inserted into the piston rod, and the piston is configured to be able to move freely between the rod seat parts in the axial direction of the piston rod, thereby absorbing load energy. Sometimes, the piston is pressed against one rod seat part, and the fluid passes only through the narrow passage formed by the outer circumference of the piston and the inner circumference of the cylinder, generating braking force.
During the return operation, the piston is moved to the other rod seat side, and the fluid is moved through a bypass flow path composed of a plurality of grooves formed in the radial direction of the end surface of the piston and the rod seat section. Therefore, the return operation is performed without creating a large fluid resistance on the piston.

However, in the shock absorber with the above structure, the piston has a complicated shape, which requires a lot of processing time, and the bypass flow path becomes long, which increases flow path resistance and may not allow quick return operation. The present inventor discovered that there is a problem.

[Object of the invention] An object of the invention is to provide a shock absorber that has a simple structure and can perform a quick return operation.

[Structure of the idea]

The present invention provides a shock absorber that absorbs dynamic body load energy through a piston rod that is moved together with the piston by a braking force generated on the piston that is moved in a fluid sealed in a cylinder.
A flange-shaped rod seat part formed at the inner end of the piston rod and forming a predetermined gap with the inner periphery of the cylinder, a first tapered part protruding from the rod seat part, and a first tapered part formed on the first tapered part. The piston is loosely inserted and forms a first flow path without contact with the inner periphery of the cylinder, and the piston is engaged with the tip of the first tapered part and is movable in the axial direction between the rod seat part and the piston. a ring held in the piston; a through hole opened in the ring along the outer circumference of the first tapered portion; and a through hole formed in the inner circumference of the piston and having an inclination in the opposite direction to the first and a second tapered part forming a second flow path between the two.

As a result, when absorbing a load, the piston comes into close contact with the rod seat part and the second flow path between the first taper part and the second taper part is closed, so there is a gap between the piston and the inner circumference of the cylinder. The fluid moves only through the first flow path, and a braking force is applied to the piston. During the return operation to move the piston in the opposite direction, the piston is separated from the rod seat part and the second flow path is opened. , the fluid moves quickly through both the first and second fluids, and since there is no contact between the piston and the cylinder, the braking force acting on the piston is extremely small. A quick return operation is achieved with a simple structure without any formation.

[Embodiment 1] FIG. 1 is a cross-sectional view of a shock absorber according to an embodiment of the present invention, and FIG. 2 is an enlarged cross-sectional view of the main parts thereof.

In the shock absorber of this embodiment, a piston rod 2 is inserted into a cylindrical cylinder 1 with one end closed, and a piston rod 2 is inserted into the inner end of the cylinder 1.
A rod seat portion 3 is formed.

Further, at the tip of the piston rod 2, as shown in FIG. 2, a tapered part 4 (first tapered part) is formed so that the outer diameter gradually decreases toward the closed end of the cylinder 1. has been done.

A piston 5 is loosely inserted into this tapered portion 4 so as to be movable in the axial direction of the piston rod 2.
As the piston rod 2 moves in the axial direction of the piston rod 2, a flow path (second flow path) is formed between the outer circumference of the tapered portion 4 and the inner circumference of the piston 5.

In addition, a tapered seat 6 is formed on the side surface of the piston 5 facing the rod seat portion 3 of the piston rod 2, and when pressed against the rod seat portion 3, it forms a line contact and performs a sealing action, and forms a seal with the inner peripheral portion of the piston 5. The structure is such that fluid is prevented from passing through the flow path formed by the taper portion 4 of the piston rod 2.

Furthermore, a taper part 7 (second taper part) is formed in the inner peripheral part of the piston 5 in the opposite direction to the taper part 4 formed in the piston rod 2.
formed by the outer circumference of the piston 5 and the inner circumference of the piston 5,
The cross-sectional area of the short flow path gradually increases toward the distal end of the piston rod 2.

Therefore, the flow path resistance when the fluid is moved toward the tip of the piston rod 2 in this flow path is reduced, and rapid movement of the fluid and, by extension, quick return of the piston 5 is possible.

In this case, since the shapes of the taper part 4 of the piston rod 2 and the taper part 7 of the inner peripheral part of the piston 5 are simple, machining is relatively easy and the cost required for machining is reduced.

A ring 8 is fitted and locked in the circumferential groove at the tip of the piston rod 2 to prevent the piston 5 from falling off from the tip of the piston rod 2.

Furthermore, a plurality of through holes 9 are provided in the center of the ring 8, and when the piston 5 is in contact with the ring 8, the outer circumference of the tapered portion 4 and the inner circumference of the piston 5 are formed. The structure is such that it communicates with the flow path where the

Further, a holder 10 is provided on the open end side of the cylinder 1.
is inserted into the cylinder 1, and the piston rod 2 is slidably inserted and guided in the axial direction of the cylinder 1 through the center thereof.

The holder 10 includes a spacer 11 and a retainer 1.
2 is fixed to the cylinder 1 by an O-ring 13.
This prevents the fluid 14, such as silicone oil, from leaking within the cylinder 1.

Similarly, a packing 15 is provided at a portion of the holder 10 through which the piston rod 2 is inserted, and is structured to prevent the fluid 14 sealed in the cylinder from leaking to the outside due to movement of the piston rod 2. ing.

Around the small diameter part of the holder 10, there is provided an accumulator 16 which is made of, for example, a closed-cell sponge structure and is expandable and deflated. The fluid 14 passes through the plurality of fluid passages 17 and flows into the fluid chamber 18 in which the accumulator 16 is located, and by contracting the accumulator 16, the internal pressure of the cylinder 1 is prevented from rising above a predetermined value. It is said that the structure is

A coil spring 2 is inserted between the ring 8 and an end cap 19 inserted into the closed end of the cylinder 1.
0 is provided, and a resilient force is always applied through the ring 8 in the direction of pushing the piston rod 2 out of the cylinder 1, that is, in the left direction in FIG.

A part of the inner circumference of the cylinder 1 has a tapered part 2 so that the inner diameter decreases toward the terminal end of the cylinder 1.
1 (third taper part) is formed, and when the piston rod 2 is moved in the direction of entering into the cylinder 1, a gap (first flow path) with the outer peripheral part of the piston 5 is formed.
The structure is such that the braking force generated on the piston 5 is gradually increased by gradually decreasing the braking force.

An injection hole 22 for injecting the fluid 14 and venting air is formed at the closed end of the cylinder 1. After the fluid 14 is injected into the cylinder 1, it is sealed with a sealing ball 23 and a sealing screw 24. There is.

Further, a threaded portion 25 is formed on the outer periphery of the cylinder 1, and the cylinder 1 has a structure that allows it to be easily attached to a predetermined device (not shown).

Further, a cap 26 is attached to the end of the piston rod 2 that projects outside the cylinder 1.
The moving body that comes into contact with the end of the piston rod 2 is prevented from being damaged.

Next, the operation of this embodiment will be explained.

When a dynamic load is applied to the tip of the piston rod 2 protruding to the outside of the cylinder 1, the piston rod 2 moves toward the inside of the cylinder 1, that is, to the right in FIG. 1, against the elastic force of the coil spring 20. begins to

At this time, the piston 5 is pressed by the fluid 14 present on the right side of the piston 5 and pressed against the rod seat part 3 of the piston rod 2, and the rod seat part 3 and the taper seat 6 of the piston 5 are brought into close line contact and a sealing effect is achieved. It will be done.

As a result, the fluid 14 on the right side of the piston 5 is prevented from flowing into the left side of the piston 5 through the flow path formed by the outer circumference of the tapered portion 4 of the piston rod 2 and the inner circumference of the piston 5. Therefore, the fluid 14 existing on the right side of the piston 5 flows into the left side of the piston 5 through only a gap with a small cross-sectional area, which is formed by the outer circumference of the piston 5 and the inner wall surface of the cylinder 1. .

In this way, a braking force is generated in the piston 5 due to the viscous resistance of the fluid.

In this case, a tapered portion 21 is formed on the inner circumference of the cylinder 1.
As a result, the gap between the outer circumferential portion of the piston 5 and the tapered portion 21 of the cylinder 1 gradually decreases as the piston rod 2 enters the cylinder 1.
The braking force generated is gradually increased.

Therefore, even when a sudden dynamic load is applied to the piston rod 2, the braking force generated on the piston rod 2 is not suddenly increased at the beginning of the movement of the piston rod 2, and smooth dynamic load energy absorption operation is possible. It will be done.

Next, when the dynamic load is released, the piston rod 2 begins to move in the direction of protruding outside the cylinder 1, that is, to the left in FIG. 1, due to the elastic force of the coil spring 20.

At this time, the piston 5 is separated from the rod seat portion 3 of the piston rod 2 and is moved to a position where it comes into contact with the opposing side surface of the ring 8, as shown by the two-dot chain line in FIG.

As a result, the fluid 1 present on the left side of the piston 5
4 passes through both a channel with a large cross-sectional area and a short length, which is composed of the inner periphery of the piston 5 and the tapered portion 4 of the piston rod 2, and the gap between the outer periphery of the piston 5 and the inner periphery of the cylinder 8. Piston 5 easily
flows into the right side of the piston 5 and the cylinder 8.
Since there is no contact with the inner periphery of the piston 5, no large fluid resistance or sliding resistance force is generated on the piston 5, and the piston rod 2 is quickly returned to its unloaded position.

Note that the present invention is not limited to the above-mentioned embodiments; for example, it is also possible to form a tapered seat in the rod seat portion 3 and to make the side surface of the piston 5 simply flat.

[Effects] (1) When absorbing a load, the piston comes into close contact with the rod seat part and the second flow path between the first taper part and the second taper part is closed, so the connection between the piston and the inner circumference of the cylinder is reduced. The fluid moves only through the first flow path between the two rods, and a braking force is applied to the piston.At the time of return operation to move the piston in the opposite direction, the piston separates from the rod seat part and the second flow path acts on the piston. Opened, first
The fluid moves quickly through both the first fluid and the second fluid, and since there is no contact between the piston and the cylinder, the braking force acting on the piston is extremely small, making it difficult to form complex through holes in the piston. A quick return operation is achieved with a simple structure.

(2) By forming a tapered part on the inner circumference of the cylinder so that the inner diameter decreases in the direction of movement of the piston rod during dynamic load energy absorption operation, the braking force increases gradually, and the braking force is suppressed at the beginning of the movement of the piston rod. A sudden increase in power can be prevented, and dynamic body load energy absorption operation becomes smooth.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a shock absorber according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of the main parts thereof. 1...Cylinder, 2...Piston rod, 3...
...rod seat part, 4...tapered part, 5...piston, 6...tapered seat, 7...tapered part, 8
...Ring, 9...Through hole, 10...Holder, 1
1... Spacer, 12... Retainer, 13... O
Ring, 14...Fluid, 15...Patzkin, 16
...Accumulator, 17...Fluid passage, 18...
...fluid chamber, 19 ... end cap, 20 ... spring, 21 ... taper part, 22 ... injection hole,
23... Sealing ball, 24... Sealing screw, 25... Threaded portion, 26... Cap.

Claims (1)

[Claims for Utility Model Registration] (1) A shock absorber that absorbs dynamic body load energy through a piston rod that moves together with the piston due to the braking force generated on the piston that moves in the fluid sealed in the cylinder. A flange-shaped rod seat portion formed at the inner end of the piston rod and forming a predetermined gap with the inner periphery of the cylinder; a first tapered portion protruding from the rod seat portion; A piston that is loosely inserted into the first tapered part and forms a first flow path without contact with the inner periphery of the cylinder, and a piston that is engaged with the tip of the first tapered part and is connected to the rod seat part. a ring that holds the piston movably in the axial direction; a through hole opened in the ring along the outer circumference of the first tapered portion; and a through hole formed in the inner circumference of the piston and the first A shock absorber comprising: a second tapered part having an inclination in a direction opposite to that of the tapered part and forming a second flow path between the first tapered part and the second tapered part. (2) The shock absorber according to claim 1, wherein a third tapered portion is formed on the inner peripheral portion of the cylinder.