JP2607065Y2 - 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 improvement in a small hydraulic shock absorber called a mini-buffer.

[0002]

2. Description of the Related Art In general, small hydraulic shock absorbers called mini-buffers are used for various purposes.
When this is used for a machine tool or the like, it has been pointed out that an operation failure due to intrusion of dust and a problem of oil contamination due to oil leakage.

A small hydraulic shock absorber called a mini-buffer has conventionally been formed into a structure as shown in FIG. 2, for example.

That is, the hydraulic shock absorber comprises an inner tube 2 concentrically disposed in an outer tube 1 and a lower end portion of the inner tube 2 in the inner tube 2.
A piston rod 3 having a piston portion 3a that slides inside the piston rod 3 is inserted through the spring 4 so as to be able to protrude and retract, and the upper ends of the outer tube 1 and the inner tube 2 are sealed while allowing the piston rod 3 to penetrate. And a bearing member 5 for stopping.

The bearing member 5 has a dust seal 6 interposed on the inner periphery of its outer end, which is the upper end in the figure, and an oil seal 7 on the inner periphery of its inner end, which is the lower end in the figure. It is interposed.

Therefore, in this conventional hydraulic shock absorber, when the piston rod 3 comes into and out of the inner tube 2, the dust seal 6 adheres to the outer periphery of the piston rod 3 and scrapes dust which is likely to enter the inside. Drop it,
The oil seal 7 forms an oil film on the outer periphery of the piston rod 3 to ensure the slidability of the piston rod 3 with respect to the bearing member 5.

However, in this conventional hydraulic shock absorber, effective dust scraping can be realized when the dust seal 6 has a large tightening force on the piston rod 3. In this case, however, the oil seal 7 Accordingly, the oil film formed on the outer periphery of the piston rod 3 is scraped off by the dust seal 6.

As a result, the slidability of the piston rod 3 with respect to the bearing member 5 is reduced, and oil accumulates at the projecting end of the piston rod 3 in the hydraulic shock absorber, causing a problem of causing oil contamination.

On the other hand, the piston rod 3 of the dust seal 6
If the tightening force is reduced, the problem of scraping off the oil film on the outer periphery of the piston rod 3 by the dust seal 6 can be avoided, but in this case, the dust is not effectively scraped off by the dust seal 6. In addition, there is a problem that dust invades the inside and causes malfunction of the hydraulic shock absorber.

The present invention has been made in view of the above-mentioned circumstances, and aims at increasing the tightening force of the dust seal to enable effective scraping of dust. An object of the present invention is to provide a hydraulic shock absorber which is optimal for use in a machine tool or the like by preventing oil stains caused by scraping off an oil film.

[0011]

Means for Solving the Problems In order to achieve the above object, the means of the present invention comprises an outer tube, an inner tube coaxially disposed in the outer tube, and upper ends of the outer tube and the inner tube. , A piston rod inserted through the inner tube and the bearing member so as to be able to protrude and retract through a piston portion, and disposed in the inner tube to urge the piston rod in the extension direction. In a hydraulic shock absorber having a spring, a bearing member is formed to be long in a sliding direction of a piston rod, is housed inside an upper half portion of an outer tube, and has an oil amount compensating material on an outer peripheral side of the bearing member. And a dust seal is provided on the inner periphery near the outer end of the bearing member, and the inner end of the bearing member is Oil seal is interposed on the inner periphery in the vicinity, in which spacing between the dust seal and the oil seal is characterized in that greatly set from sliding stroke of the piston part within the inner tube.

[0012]

Therefore, dust adhering to the outer peripheral surface of the piston rod and trying to enter the inside is scraped off by the dust seal, while the oil film adhered to the outer peripheral surface of the piston rod by the oil seal becomes The dust seal prevents it from being scraped off.

As a result, the phenomenon that the oil film is scraped off by the dust seal does not occur, and oil contamination due to the accumulation of oil at the protruding and retracting ends of the piston rod does not occur.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. As shown in FIG. 1, the hydraulic shock absorber according to the present invention seals an outer tube 1, an inner tube 2 coaxially arranged in the outer tube 1, and upper ends of the outer tube 1 and the inner tube 2. Bearing member 5 to be stopped, inner tube 2 and bearing member 5
A piston rod 3 is inserted through the piston portion 3a so as to be retractable via a piston portion 3a, and a spring 4 is disposed in the inner tube 2 and urges the piston rod 3 in the extending direction. Further, the bearing member 5 is formed to be long in the sliding direction of the piston rod 3 and housed inside the upper half portion of the outer tube 1, and the oil amount compensating material 9 is housed on the outer peripheral side of the bearing member 5. Bearing member 5
A dust seal 6 is interposed on the inner periphery near the outer end of the bearing member, and an oil seal 7 is interposed on the inner periphery near the inner end of the bearing member 5, so that the distance between the dust seal 6 and the oil seal 7 is increased. S is set to be larger than the sliding stroke S1 of the piston portion 3a in the inner tube 2. This will be described in detail below.

That is, the hydraulic shock absorber comprises an inner tube 2 disposed concentrically in an outer tube 1 and a lower end portion of the inner tube 2 in the inner tube 2.
A piston rod 3 having a piston portion 3a that slides inside the piston rod 3 is inserted through the spring 4 so as to be able to protrude and retract, and the upper ends of the outer tube 1 and the inner tube 2 are sealed while allowing the piston rod 3 to penetrate. And a bearing member 5 for stopping.

However, in this embodiment, the bearing member 5 is formed to be long in the sliding direction of the piston rod 3, which is the vertical direction in the figure, and is housed inside the upper half of the outer tube 1. It is said to be equipped.

As a result, in the illustrated example, the inner tube 2 is formed in a so-called short length and is disposed inside the lower half of the outer tube 1.

The bearing member 5 is provided with a dust seal 6 on the inner periphery of the outer end 5a, which is the upper end in the figure, and an oil seal 7 on the inner periphery of the inner end 5b, which is the lower end in the figure. It is interposed.

That is, in the bearing member 5 portion,
The arrangement interval between the dust seal 6 and the oil seal 7, that is, the mutual interval S is set to be larger than the sliding stroke S1 of the piston portion 3a in the inner tube 1.

The hydraulic shock absorber has the following configuration in another configuration other than the above.

That is, the lower ends of the outer tube 1 and the inner tube 2 are closed by a bottom member 8, and an annular oil chamber, that is, a reservoir chamber is provided between the inner periphery of the outer tube 1 and the outer periphery of the inner tube 2. It is assumed that R is formed.

The reservoir chamber R is provided with a cutout groove 5d formed in an inner end 5b of the bearing member 5 in an annular recess 5c formed on the outer peripheral side of the bearing member 5 in the illustrated example. It is described that the cylindrical oil amount compensating material 9 made of independent foaming urethane or the like is housed in the concave portion 5c.

The inner tube 2 has a piston 3
An oil chamber, that is, a piston-side oil chamber R1 is defined below the piston portion 3a by the accommodation of a.

The piston-side oil chamber R1 communicates with the reservoir chamber R through a plurality of ports 2a formed in the lower half of the inner tube 2 at so-called vertical intervals at appropriate intervals.

The bottom member 8 is provided with a port 8a for allowing communication between the piston side oil chamber R1 and the reservoir chamber R, and the opening end of the port 8a on the piston side oil chamber R1 side. Has a steel ball 10 functioning as a check valve
Are arranged.

In the upper half of the inner tube 2,
An annular gap (not shown) is formed when the piston portion 3a descends inside the inner tube 2, and this gap is formed through an opening 2b opened near the upper end of the inner tube 2 in the reservoir chamber. It is said that it communicates with R.

By the formation of the opening 2b, lubricating oil flows from the reservoir chamber R into the gap.

The lower end of the spring 4 is locked to the upper end of a bottom member 8 positioned inside the lower end of the inner tube 2, and biases the piston rod 3 in a direction to protrude from the inner tube 2. .

Incidentally, the upper end of the spring 4 is engaged with the inside of the upper end of the piston rod 3 by passing through a hollow portion 3b formed in the shaft core of the piston rod 3.

Further, on the outer periphery of the outer tube 1,
A thread 1a is formed over substantially the entire length, and the thread 1a is formed.
, A nut 11 (see FIG. 2) as a fastening tool is screwed therein, and a cap 12 (see FIG. 2) is interposed at a base end of the piston rod 3 which is an upper end in the drawing.

Therefore, in the hydraulic shock absorber according to this embodiment formed as described above, the piston rod 3 is immersed in the outer tube 1 and the piston portion 3a descends in the inner tube 2. In the pressure side operation, oil in the piston side oil chamber R1 flows into the reservoir chamber R via the port 2a opened in the inner tube 2.

At this time, as the piston portion 3a moves down in the inner tube 2, the number of ports 2a opening from the piston side oil chamber R1 to the reservoir chamber R side decreases, and accordingly, the piston portion 3a The lowering in the inner tube 2 is gradually restricted, so that a so-called damping function is exhibited.

In addition, the piston rod 3 is protruded from the outer tube 1 by the urging force of the spring 4 and the piston portion 3a rises in the inner tube 2 in reverse operation from the above-mentioned pressure side operation. The oil from the reservoir chamber R flows into the piston side oil chamber R1 via the port 8a so as to lift the steel ball 10 functioning as a check valve.

When the piston rod 3 comes into and out of the inner tube 2, the dust seal 6 adheres to the outer periphery of the piston rod 3 to scrape off dust that tends to enter the interior, and the oil seal 7 moves the piston rod 3.
An oil film is formed on the outer periphery of the piston rod 3 to ensure the slidability of the piston rod 3 with respect to the bearing member 5.

At this time, the dust seal 6 does not scrape off the oil film adhered to the outer peripheral surface of the piston rod 3 by the oil seal 7.

That is, the arrangement interval between the dust seal 6 and the oil seal 7, that is, the mutual interval S is set so as to be larger than the stroke in which the piston portion 3a moves in the inner tube 2, that is, the sliding stroke S1. Because it is.

As a result, scraping of dust by the dust seal 6 is reliably realized, while the dust seal 6
This prevents the oil film from being scraped off, and prevents oil contamination due to accumulation of oil at the protruding and retracting ends of the piston rod 3.

[0038]

As described above, according to the present invention, the distance between the dust seal and the oil seal interposed on the inner periphery of the bearing member and slidably in contact with the outer periphery of the piston rod is determined by the sliding of the piston portion in the inner tube. Since it is assumed that it is set to be larger than the dynamic stroke, while increasing the tightening force in the dust seal to enable effective dust scraping, it is necessary not to exhibit the oil film scraping phenomenon itself due to the dust seal This makes it possible to prevent oil contamination on the protruding and retracting end portions of the piston rod in the hydraulic shock absorber, which is advantageous in that the hydraulic shock absorber is optimally used for machine tools and the like. .

Further, according to the present invention, the chance that the oil film adhered to the outer periphery of the piston rod comes into contact with the dust seal is greatly reduced, so that the deterioration phenomenon of the dust seal due to oil does not occur, and the durability of the dust seal is improved. This has the advantage of improving the durability of the hydraulic shock absorber itself.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a hydraulic shock absorber according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing a hydraulic shock absorber as a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outer tube 2 Inner tube 3 Piston rod 3a Piston part 4 Spring 5 Bearing member 5a External end 5b Internal end 6 Dust seal 7 Oil seal S Mutual interval S1 Sliding stroke

Continued on the front page (56) References Japanese Utility Model Showa 60-1773734 (JP, U) Japanese Utility Model Showa 59-37449 (JP, U) Japanese Utility Model Showa 57-164336 (JP, U) Japanese Utility Model Showa 4-39342 (JP) , U) Japanese Utility Model Showa 63-185936 (JP, U) Japanese Utility Model Utility Model Hei 2-47448 (JP, U)

Claims (1)

(57) [Scope of request for utility model registration] 1. An outer tube, an inner tube disposed concentrically in the outer tube, a bearing member for sealing upper ends of the outer tube and the inner tube, and a piston inside the inner tube and the bearing member. A hydraulic shock absorber comprising: a piston rod inserted so as to be able to protrude and retract through a portion; and a spring disposed in the inner tube to bias the piston rod in an extending direction. It is formed long in the sliding direction and housed inside the upper half of the outer tube, the oil amount compensating material is housed on the outer peripheral side of the bearing member, and further on the inner periphery near the outer end of the bearing member. A dust seal is interposed, and an oil seal is interposed on the inner periphery near the inner end of the bearing member. A hydraulic shock absorber characterized in that an interval between the oil seal and the oil seal is set to be larger than a sliding stroke of a piston portion in the inner tube.