JP2000227134A - Shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shock absorber with good damping and restorable performance under shock by securing high volume change response speed of an accumulator to easily follow increase and decrease of piston rod occupation volume. SOLUTION: This shock absorber includes a piston device 14 which incorporates a piston rod 12 that automatically restores by spring force after receiving shock, a housing 15A, an accumulator holding space 18 outside of a piston cylinder 16. Hydraulic oil is filled in a primary piston chamber 22 and a secondary piston chamber 24 of the piston device 14. The accumulator holding space 18. The circumferential wall of the piston cylinder 16 has an orifice 30 and a communication hole between the primary piston chamber 22 and the accumulator holding space 18. A variable volume type accumulator 21A is arranged in the accumulator holding space 18. The accumulator 21A is formed from an elastomer cord spiral body with a space S between opposing surfaces.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston cylinder type shock absorber.

[0002] The shock absorber of the present invention can be used for absorbing various impacts, and can be used for various robots, press machines, transfer machines,
It can be applied to the opening / closing section of the door.

[0003]

2. Description of the Related Art As a piston cylinder type shock absorber, there is one having a configuration as shown in FIGS.

A piston device 14 incorporating a piston rod 12 receiving an impact force, and a piston cylinder (inner cylinder)
A housing (outer cylinder) 15 that forms an accumulator holding space 18 outside of the housing 16 is provided. The piston cylinder 16 includes a first piston chamber 22 on the side of the piston rod 12 with the piston 20 interposed therebetween, and a second piston chamber 24 on the opposite side.

The accumulator holding space 18 is provided with a variable volume accumulator 21. The accumulator 21 complements the increase / decrease of the volume occupied by the piston rod 12 due to the entry / retreat of the piston rod 12 into the first piston chamber 22.

[0006] The first and second piston chambers 22, 24 and the accumulator holding space 18 are provided with a hydraulic fluid (usually hydraulic oil).
The second piston chamber 24 is provided with a piston return means (coil spring) 28. Further, the peripheral wall of the piston cylinder 16 is provided with a conduction hole 29 on the first piston chamber 22 side and an orifice 30 for shock absorption on the second piston chamber 24 side.

The accumulator 21 is formed of a ring as shown in the figure, which is a substantially closed-cell elastomer foam. At this time, in order to secure a large accumulator function, the ring body 21 is normally fitted almost closely to the accumulator holding space (annular space) 18.

A first plug block 32 for closing both ends of the housing 14 and holding the cylinder 16 is provided.
And the second plug block 34 is fitted. The plug blocks 32, 34 are locked (fixed) by first and second retaining ring plates 36, 38 made of spring steel.

The first plug block 32 for closing the piston rod side comprises a cylinder seat plate block 40 and a plug block main body 41 from the viewpoint of ease of assembly in the illustrated example. The cylinder seat plate block 40 includes a stopper protrusion 42 that fits into the cylinder 16 and regulates the front dead center of the piston rod 12. Naturally, the first plug block 32
A through hole 32a in which the piston rod 12 slides is provided at the center, and first and second O-rings 48 and 50 are mounted on the inner peripheral side and the outer peripheral side, respectively, so that oil leakage on the piston rod 12 side can be prevented. Is secured.

On the other hand, the second plug block 34 has an oil supply hole 52 at the center. And oil supply hole 5
The second plug 2 can be closed by a screw plug 56, and a third O-ring 58 is attached to the outer peripheral side of the second plug block 34, so as to secure airtightness that can prevent oil leakage on the side opposite to the piston rod 12.

In the shock absorber having the above structure, when an impact load acts on the piston rod 12, the piston 20 pressurizes the hydraulic fluid L in the second piston chamber 24, and the hydraulic fluid L
Jets from the orifice 30 into the accumulator holding space 18. At this time, the hydraulic fluid L receives resistance and generates heat, but the thermal energy is radiated from the outer periphery of the housing.
In this way, the impact energy (kinetic energy) is converted into heat energy to absorb the impact.

Conversely, the piston rod 12, from which the impact load has been removed, returns by the piston 20 being urged by the coil spring 28, and then prepares for an impact.

[0013] The absorption capacity of the shock absorber having the above structure is determined by the characteristics of the hydraulic fluid (mainly viscosity), the orifice 3
It is controlled by the specification (dimensions / number) of 0 and the spring constant of the return coil spring 28.

[0014]

However, in the case of the shock absorber having the above structure, since the pressure receiving surface of the accumulator 21 is substantially only the end face of the ring body, the volume compression (reduction) and elastic return (return) of the accumulator 21 are performed. ) The speed may not be able to follow the increase or decrease in the occupied volume of the piston rod.

That is, the volume reduction rate cannot compensate for the decrease in the entire working fluid filled space (the first and second piston chambers 22, 24 and the accumulator holding space 18) due to the increase in the volume occupied by the piston rod. There is a possibility that the working fluid ejected from the orifice 30 temporarily receives a back pressure, and the piston rod 12 is temporarily impacted.

Conversely, when the volume recovery speed of the accumulator 21 is low, the pressure in the accumulator holding space 18 tends to decrease, and the difference between the accumulator holding space 18 and the second piston chamber 24 due to the return of the piston rod tends to be small. As a result, the hydraulic fluid from the first piston chamber 22 to the second piston chamber 24 via the accumulator holding space 18 does not flow smoothly, and the return of the piston rod 18 due to the spring force is hindered, making it difficult to perform the operation quickly. Become.

In view of the above, an object of the present invention is to provide a shock absorber in which the volume variable speed of the accumulator is large, which can easily follow the increase / decrease in the volume occupied by the piston rod, and which has good damping performance and good piston rod return performance upon impact. The purpose is to provide.

[0018]

Means for Solving the Problems The present inventors have made intensive efforts to solve the above-mentioned problems, and as a result, have arrived at a shock absorber having the following structure.

One aspect of the present invention includes a piston device incorporating a piston rod receiving an impact force, and a housing forming an annular accumulator holding space outside a piston cylinder, wherein a cylinder of the piston device sandwiches the piston. A first piston chamber on the side of the piston rod and a second piston chamber on the opposite side are provided, and an accumulator holding space is provided with a variable-volume accumulator, and the first and second piston chambers and the accumulator holding space contain hydraulic fluid. Enclosed, the second piston chamber is provided with piston return means, the peripheral wall of the cylinder of the piston device is provided with a conduction hole on the first piston chamber side and an orifice for shock absorption on the second piston chamber side. In the shock absorber, the accumulator has a gap between the outer surface or the inner surface and an opposing surface. , And it is characterized in that it is formed by helically wound body or ring assembly of the elastomer cords.

In the above, the outer periphery and / or the inner periphery of the spirally wound body or the plurality of ring aggregates have a corrugated cross section,
It is configured to be adhesively fixed to the cylinder outer peripheral surface or the housing inner peripheral surface, and further, it is possible to use an elastomer tube as an elastomer cord body,
This is desirable because the volume variable speed of the accumulator can be more easily increased.

It is desirable to provide a one-way valve from the second piston chamber to the first piston chamber, which is opened when the piston rod returns, because the piston rod can return more quickly.

Another aspect of the present invention comprises a piston device incorporating a piston rod receiving an impact force, and a housing forming an accumulator holding space outside the piston cylinder, wherein the cylinder of the piston device sandwiches the piston. A first piston chamber on the side of the piston rod and a second piston chamber on the opposite side are provided, and an accumulator holding space is provided with a variable-volume accumulator, and the first and second piston chambers and the accumulator holding space contain hydraulic fluid. Sealed, the second piston chamber is provided with a piston return means,
The peripheral wall of the cylinder of the piston device has a conduction hole on the first piston chamber side and an orifice for shock absorption on the second piston chamber side. A one-way valve from the first piston chamber to the first piston chamber.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the shock absorber of the present invention will be described with reference to the drawings. The same portions as those in the above-described example are denoted by the same reference numerals, and all or part of the description thereof will be omitted.

A piston device 14 incorporating a piston rod 12 which receives an impact force, and a housing 15 forming an accumulator holding space 18 outside a piston cylinder 16 are provided. The piston cylinder 16 includes a first piston chamber 22 on the side of the piston rod 12 with the piston 20 interposed therebetween, and a second piston chamber 24 on the opposite side.

The accumulator holding space 18 is provided with a variable volume accumulator 21A. The accumulator 21 </ b> A complements the increase / decrease of the volume occupied by the piston rod 12 due to the penetration / retreat of the piston rod 12 into the first piston chamber 22.

The first and second piston chambers 22 and 24 and the accumulator holding space 18 contain a hydraulic fluid (usually hydraulic fluid).
The second piston chamber 24 is provided with a piston return means (coil spring) 28. Further, the peripheral wall of the piston cylinder 16 is provided with a conduction hole 29 on the first piston chamber 22 side and an orifice 30 for shock absorption on the second piston chamber 24 side. Up to this point, the configuration is substantially the same as that of the above-described example. The hydraulic fluid is usually oil,
It may be water or other viscous fluid.

The present embodiment is different from the above-described embodiment in that the housing 15A is formed of a pipe, and the outer beading 60 is formed for mounting or positioning on a bracket or the like. It is a point.

The outer bead digs 60 may be provided at a plurality of positions at positions where the sealing performance is not impaired, that is, at positions other than the positions where the second and third O-rings 50 and 58 are mounted. By using a metal pipe such as an electric resistance welded pipe or a seamless pipe as a material, the first and second plug blocks 32 and 34 can be used.
Can be fixed by plastic working (hemming or swaging) 62, 63 at both ends, and as compared with the case where the housing 14 is formed by cutting, not only the number of working steps is reduced, but also the stop ring plates 36, 39 at both ends. And the number of parts is reduced. Of course, the housing may be formed by cutting as in the conventional case. In the case of using an outer peripheral screw or an inner peripheral screw structure, it is usually formed by cutting.

In this embodiment, the accumulator 21A is formed by a spiral wound body of the elastomer string 66 with a gap between the outer circumference and the facing surface.

Specifically, an elastomeric tube body 66 is used as an elastomeric string body, and the tube is fixedly bonded to the outer peripheral surface of the cylinder. In addition, both ends of the tube body are closed, and the contact surfaces of the spiral winding itself may be in an adhesive state. However, in the non-adhesive state, the contact surfaces are also auxiliary pressure receiving surfaces, and the volume of the accumulator is reduced. The rate of decrease is more desirable.

In this embodiment, the elastomer tube 66 is used as the accumulator 21A from the viewpoint of assemblability and the like, and the outer periphery and the inner periphery of the spirally wound body are formed into a corrugated cross section. Although it is made easy to operate, it may be formed of an aggregate in which a plurality of rings are connected. Further, when the mutual contact surfaces of the spiral winding itself or the plurality of ring bodies are not bonded, each cross section of the elastomer string body or the plurality of ring bodies (not shown) may be rectangular.

Although the number of accumulators is two, one accumulator may be used as in the prior art, depending on the required capacity.
The material for forming the elastomeric string or the plurality of elastic rings is preferably a tube made of silicone rubber, fluorine rubber, NBR or the like. Is also good.

In this embodiment, the accumulator 21A
Is disposed in contact with the outer peripheral side of the cylinder 16, but may be disposed in contact with the inner peripheral side of the housing 15A.

Furthermore, in the present embodiment, the first piston chamber 22 is opened from the first piston chamber 22 to the rear end side of the cylinder 16, that is, the second piston chamber 24 side when the second piston chamber 24 becomes negative pressure. A one-way valve 68 to the two-piston chamber 24 is provided. Specifically, the piston rod 1 of the piston 18
(2) A plurality (usually 2 to 6) of valve holes 20a are formed at equal intervals at outer peripheral positions, and a disc-shaped valve body 70 that opens and closes the valve holes 20a.
Is held at the rear end side of the piston 20 by the valve body guide rod 72.

Next, the manner of use of the shock absorber of the above embodiment will be described. First, the outer beading 60 or the like formed on the housing 14 is used to attach the housing 14 to a site where shock absorption is required.

In a normal state (when no load is applied),
As shown in FIG. 3, the piston rod 12 protrudes. The impact is received at the distal end of the piston rod 12. When the impact is directly received at the distal end, it is desirable that a protective cap (not shown) be fitted to the distal end of the piston rod 12.

When an impact load is applied to the tip of the piston rod 12, the piston rod 12 moves to the second piston chamber 24.
Is retracted against the coil spring 28 while pressurizing the working fluid. The hydraulic fluid L is jetted into the accumulator holding space 18 through the orifice 30 by the pressurization. When the hydraulic fluid passes through the orifice, it receives heat and generates heat, but the heat energy is radiated from the outer periphery of the housing.
In this way, the impact energy (kinetic energy) is converted into heat energy to absorb the impact. Since the second piston chamber 24 is in a pressurized state, the one-way valve 68 is closed (see FIG. 3).

At this time, the piston rod 12 enters the first piston chamber 22, and the volume occupied by the piston rod in the first piston chamber 22 increases. Due to the increase in the volume occupied by the piston rod and the jet of the hydraulic fluid from the second piston chamber 24, the accumulator holding space 18 is relatively pressurized, and the volume of the accumulator 21A decreases. At this time, since the accumulator 21A is formed by a spiral wound body of the elastomer string (elastomer tube body) 66 with a gap between the outer surface or the inner surface and the opposing surface, the pressure receiving area is large. The volume quickly decreases (compresses) following the increase in the volume occupied by the rod. Therefore, the working fluid is jetted into the accumulator holding space 18 through the orifice 30 stably with the designed resistance, and the impact energy is smoothly absorbed.

When the impact load is removed from the piston rod 12, the piston rod 12 is restored by the bias of the piston 20 by the coil spring 28, and prepares for the next impact. That is, the operation of the coil spring 28 causes the piston rod 12 to return, so that the first piston chamber 22 is pressurized and the second piston chamber 24 tends to depressurize. An attempt is made to flow back from the space 18 to the second piston chamber 24. At this time, the occupied volume of the first piston chamber is reduced due to the retraction of the piston rod, and the accumulator holding space 18 also tends to be depressurized, contrary to the impact load. And since the accumulator 21A which exists in the accumulator holding space 18 has the gap S between the opposing surfaces, especially when the tube bodies are in the non-adhered state,
The restoration of the tube body 66 is quickly performed. Thus,
The volume of the accumulator 21 </ b> A is restored, and the tendency of the decompression of the accumulator holding space 18 is prevented.

In this embodiment, the second piston chamber 2
4 is reduced in pressure, so as shown in FIG.
Is opened, and the second piston chamber 2
4 is more smoothly flowed.

Therefore, the return movement of the piston is performed quickly, and it is easy to reliably respond to the next impact load.

In the present embodiment, the one-way valve is combined with the specific accumulator, but the return movement of the piston is quickly performed only with the one-way valve, and the combination of the conventional accumulator 21 and the one-way valve 68 is also possible. It is.

[0043]

As described above, in the shock absorber according to the present invention, the accumulator has a gap between the outer surface or the inner surface of the shock absorber and the opposing surface so that the spiral wound body or the plurality of elastomer strings can be formed. Due to the structure formed by the ring assembly, the volume variable speed of the accumulator is large, it can easily follow the increase or decrease in the volume occupied by the piston rod, and the damping performance and the piston rod return performance at impact are good. To play.

Further, the shock absorber according to another aspect of the present invention is provided with a one-way valve from the second piston chamber to the first piston chamber which is opened when the piston is returned, so that the piston rod return performance can be improved. Can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a shock absorber when no load is applied.

FIG. 2 is a schematic sectional view of the shock absorber of FIG. 1 when receiving an impact load.

FIG. 3 is a schematic cross-sectional view at the time of no load in one embodiment of the shock absorber of the present invention.

FIG. 4 is a schematic sectional view of the shock absorber of FIG. 3 when receiving an impact load;

FIG. 5 is an enlarged cross-sectional view of the piston part of FIG. 3;

[Explanation of symbols]

 Reference Signs List 12 piston apparatus 14 housing (outer cylinder) 16 cylinder 18 piston 20a valve hole 20 piston rod 22 first piston chamber 24 second piston chamber 18 accumulator holding space 28 piston return means (coil spring) 30 orifice 29 conduction hole 21 accumulator 62 plastic Processing (swaging) 21A Accumulator 66 Elastomer string 68 One-way valve

Claims (5)

[Claims] 1. A piston device incorporating a piston rod receiving an impact force, and a housing forming an annular accumulator holding space outside a piston cylinder, wherein a cylinder of the piston device is located on the piston rod side with the piston interposed therebetween. A first piston chamber and a second piston chamber opposite to the first piston chamber; a variable volume accumulator is disposed in the accumulator holding space; and a working fluid is sealed in the first and second piston chambers and the accumulator holding space. The second piston chamber is provided with piston return means, and the peripheral wall of the cylinder of the piston device is provided with a conduction hole on the first piston chamber side and an orifice for shock absorption on the second piston chamber side. In the shock absorber of the above, the accumulator is between an outer peripheral side or an inner peripheral side and an opposing surface. With a gap, a shock absorber, characterized by being formed by helically wound body or ring assembly of the elastomer cords. 2. An outer periphery and / or inner periphery of the spirally wound body or the plurality of ring assemblies has a corrugated cross section, and is bonded and fixed to the outer peripheral surface of the cylinder or the inner peripheral surface of the housing. The shock absorber according to claim 1. 3. The shock absorber according to claim 2, wherein said elastomer string is an elastomer tube. 4. The shock absorber according to claim 1, further comprising a one-way valve from the second piston chamber to the first piston chamber, which is opened when the piston returns. 5. A piston device incorporating a piston rod receiving an impact force, and a housing forming an accumulator holding space outside a piston cylinder, wherein a cylinder of the piston device is located on a piston rod side with a piston interposed therebetween. A piston chamber and a second piston chamber on the opposite side, a variable volume accumulator is arranged in the accumulator holding space, and a working fluid is sealed in the first and second piston chambers and the accumulator holding space, The second piston chamber is provided with a piston return means, and the peripheral wall of the cylinder of the piston device is provided with a conduction hole on the first piston chamber side and an orifice for absorbing shock on the second piston chamber side. In the absorber, the first piston is moved from the second piston chamber opened when the piston returns. Shock absorber, characterized in that it comprises a one-way valve to.