JPH11159618A - Bearing part structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make discharging to the outside of a cylinder unit possible of only air from in air mixed oil in an oil chamber in a cylinder unit under a bush held to a bearing, prevent the air mixed oil from being left in the cylinder unit. SOLUTION: In an internal peripheral surface of a rod unit insertion hole formed in a shaft core part of a bearing mounted in an opening end of a cylinder unit, a peripheral surface of a rod unit protruding/sinking relating to the cylinder unit holding this peripheral surface in an adjacent condition is brought into slide contact by a bush 1. In a bearing part structure formed by having the bush 1, an air bleed groove 1a connecting an oil chamber in the cylinder unit under this bush 1 to an oil reservoir chamber R2 in the upward of this bush 1 is formed in a peripheral surface of the bush 1, this air bleed groove 1a, which a high pressure is generated in the cylinder unit, while impeding passing of oil to the oil reservoir chamber R2, permits passing of air, and at negative pressure time in the cylinder unit, impedes suction of air from the oil reservoir chamber R2, in a trap effect, so as to be able to display it, and the groove is set.

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 bearing structure in a hydraulic shock absorber or the like.

[0002]

2. Description of the Related Art For example, in a hydraulic shock absorber, it has been known that air may be mixed into oil inside the hydraulic shock absorber due to its operating condition and the like. Then, it is also known that there is a problem that the damping force generated during the operation of the hydraulic shock absorber becomes unstable or adiabatic compression is caused.

[0003] Therefore, there is a proposal to discharge the air to the outside, that is, for example, when the hydraulic shock absorber is of a double cylinder type, into a reservoir chamber on the outer peripheral side of the cylinder body. -28248.

In view of the above, this proposal has been proposed as a bearing structure in a hydraulic shock absorber, but the point is that the bush has an air vent groove on the outer peripheral surface thereof. It is.

[0005] To briefly explain, this bearing portion structure is, for example, as shown in FIG. 4, a rod formed on a shaft core portion of a bearing B mounted on an open end of a cylinder body C which is a cylinder constituting a hydraulic shock absorber. The bush 1 is held so that the outer peripheral surface is adjacent to the inner peripheral surface of the body insertion hole B1.

The bush 1 is configured to slide the outer peripheral surface of a rod body R, which is a piston rod, which is protruded and retracted from the cylinder body C, while also forming a hydraulic shock absorber on the inner peripheral surface.

By the way, the bush 1 is often
A flat plate having an appropriate thickness is bent into a cylindrical shape and fixed by being pressed into the rod body insertion hole B1, and the inner peripheral surface and the outer peripheral surface of the rod body R are fixed. Although not shown or shown, a small gap is set on the outer peripheral surface of the rod body R so as to be sufficient to leave an oil film for ensuring the slidability of the rod body R. I have.

In the hydraulic shock absorber, the cylinder body C
An outer cylinder O is disposed on the outer peripheral side of the cylinder. A reservoir chamber R1 is formed between the outer cylinder O and the cylinder body C,
It is assumed that a groove B3 for collecting oil leakage and a through hole B4 communicating with the groove B3 are formed in the upper end flange portion B2 of the bearing B, and the upper portion of the bush 1 through the groove B3 and the through hole B4 is formed. The communication between the oil sump chamber R2 and the reservoir chamber R1 is enabled.

Therefore, according to this bearing structure, the bearing B mounted on the open end of the cylinder body C is connected to the rod body R via the bush 1 while preventing the rod body R from being permanently eccentric or falling. In addition, the slidability of the rod body R with respect to the cylinder body C can be ensured by the bush 1.

As shown in FIG. 5, an air vent groove 1a is formed on the outer peripheral surface of the bush 1 when it is in a flat state before being bent into a cylindrical shape. By being fixed to the rod body insertion hole B1 at a predetermined position, the air vent groove 1a allows the oil chamber R3 in the cylinder body C below the bush 1 to communicate with the oil sump chamber R2 above the bush 1. Become.

As a result, the hydraulic shock absorber is located inside due to its operating condition, that is, the oil chamber R in the cylinder body C.
Even if the situation where air is mixed in the oil in the oil chamber R3, when the pressure in the oil chamber R3 is increased, the air flows through the air vent groove 1a to the oil sump chamber R2 above the bush 1.
In other words, for example, the damping force generated during the operation of the hydraulic shock absorber due to the air remaining in the oil is discharged to the reservoir chamber R1, which is the outer peripheral side of the cylinder body C. And adiabatic compression will be avoided.

[0012]

However, in the above-described conventional bearing structure, there is a possibility that oil may be discharged at the same time as air is discharged. is there.

That is, as described above, when the bush 1 is in the state of a flat plate before being bent into a tubular shape, the air bleeding groove 1a is formed. As shown in (1), not only the air circulation is improved, but also the oil circulation is improved at the same time.

Even if the air vent groove 1a is set to a fine size so as to exhibit a throttle effect like a so-called orifice, the fluidity of the oil is reduced due to the viscosity of the oil and only the air is allowed to flow. Actually, the oil is discharged in a state where it is ejected to the oil sump chamber R2 together with the air due to the high pressure in the oil chamber R3 in the cylinder C.

The oil discharged into the oil sump chamber R2 is in a state in which air is mixed therein, which is returned to the reservoir chamber R1 and the oil chamber in the cylinder body C. As a result, there is a fear that air remains in the oil chamber R3 and the generated damping force becomes unstable during the operation of the hydraulic shock absorber and adiabatic compression cannot be avoided.

Further, when the pressure in the oil chamber R3 in the cylinder body C is reduced, the air-mixed oil in the oil sump chamber R2 is returned to the oil chamber R3 via the air vent groove 1a. As a result, instability of the generated damping force and adiabatic compression cannot be avoided as described above.

The present invention has been made in view of the above circumstances, and has as its object to remove air-mixed oil that accumulates in an oil chamber inside a cylinder body below a bush held by a bearing. An object of the present invention is to provide a bearing structure which is configured to discharge only air to the outside of a cylinder body and to prevent oil containing air from remaining in the cylinder body.

[0018]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the structure of the present invention is basically changed to a rod body insertion hole formed in a shaft core of a bearing mounted on an open end of a cylinder body. A bushing having a bush that is held in a state where its outer peripheral surface is adjacent to the inner peripheral surface of the rod body and makes the outer peripheral surface of a rod body that slides in and out of the cylinder body contact the inner peripheral surface thereof; An air vent groove is formed on the outer peripheral surface of the oil chamber inside the cylinder below the bush so as to communicate with the oil chamber above the bush. It is set so as to allow the passage of air while preventing the passage of oil, and to exhibit a trapping effect of preventing suction of air from the oil reservoir chamber at the time of negative pressure in the cylinder body.

At this time, the bearing may be formed not only from the conventional sintered steel but also from a metal material such as a gunmetal.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the illustrated embodiment. The bearing structure according to the present invention has the same structure as the conventional bearing structure shown in FIG. It is embodied in a hydraulic shock absorber set to a double cylinder type.

Incidentally, in this double-cylinder type hydraulic shock absorber, the outer cylinder O has a seal case S at the connecting portion B5, the upper end of which is connected to the upper flange portion B2 of the bearing B.
(See FIG. 4).

Under the above assumption, first, the bearing structure according to the embodiment of the present invention is as follows.
Basically, it has a bush 1 held by a bearing B similarly to the bearing structure of the conventional example shown in FIG.

That is, first, the bearing B is thinner as compared with the case where it is made of sintered steel, and can be processed without fear of breaking or the like due to the pressing action from the inner and outer circumferences. It is stated that a molded product from a metal plate material or a metal tube material containing an iron-based material such as gunmetal or steel that can be expected to have sufficient durability is selected and formed by press working.

The bearing B is mounted on the open end of the cylinder C, and the rod R is inserted through the bush 1 which is press-fitted and held in a rod insertion hole B1 formed in the axis of the cylinder C. It is described that the rod body R is prevented from being permanently eccentric or falling with respect to the cylinder body C while being inserted so as to be able to protrude and retract.

Next, as in the case of the above-described conventional example, the bush 1 is formed into a flat plate having an appropriate thickness, bent into a cylindrical shape, and pressed into the rod body insertion hole B1. At this time, between the inner peripheral surface and the outer peripheral surface of the rod body R, although not shown or shown,
The outer peripheral surface of the rod body R is set such that a small gap that is sufficient to leave an oil film for ensuring the slidability of the rod body R appears.

In this bush 1, FIG.
As shown in FIG. 1, when the flat plate is maintained, an air vent groove 1a is formed on the outer peripheral surface, which is the upper surface in FIG.

However, this air release groove 1a is
Of course, the air separated from the air-mixed oil that accumulates in the oil chamber R3 in the cylinder C below the cylinder body C is discharged to the oil sump chamber R2 above the bush 1, but on the other hand,
According to the present invention, when the pressure in the cylinder body C is increased, the passage of air is permitted while preventing the passage of oil to the oil sump chamber R2, and the pressure in the cylinder body C is reduced. This is characterized in that a trapping effect of preventing suction of air from the oil sump chamber R2 is exerted.

To explain a little, first, the air vent groove 1
The upper end of a is set so as to open to the above-mentioned oil sump chamber R2. This oil sump chamber R2 is formed in the upper end flange portion B2 of the bearing B with the oil leakage collecting groove B3 and the through hole B.
By communicating with the reservoir chamber R2 via 4, the communication with the reservoir chamber R1 is consequently made.

The lower end of the air vent groove 1a is directly opened and communicates with the oil chamber R3 in the cylinder C.

Next, the intermediate portion of the air vent groove 1a allows the passage of air while preventing the passage of oil to the oil sump chamber R2 when the pressure in the cylinder body C is increased, and allows the passage of air inside the cylinder body C. It is important to set a trapping effect to prevent the suction of air from the oil sump chamber R2 at the time of negative pressure. In the illustrated embodiment, the length of the horizontal portion (not shown) is set. The height is set to be large so that the air can flow while the oil does not easily flow.

That is, even when the upper end position and the lower end position of the air vent groove 1a are close to each other as in the case of the above-described conventional example, the stroke between them is increased to increase the pressure in the cylinder body C. While allowing the passage of only air while preventing the outflow of oil accumulated there,
When the pressure in the cylinder body C is reduced to a negative pressure, it may be set so as to prevent the suction of air from the outside by the oil accumulated therein.

Therefore, instead of increasing the length of the horizontal portion as described above, for example, as shown in FIGS. 2 and 3, it is assumed that the so-called intermediate portion is set to be inclined. It can be said that setting to the trap mode is preferable in that the effect of the trapping effect can be expected without fail.

Although not shown, the cross-sectional shape of the air vent groove 1a may be set arbitrarily. For example, if the air vent groove 1a has a triangular or semicircular shape, the configuration of the jig can be simplified. In the case of forming a rectangle and adjusting its depth, it is advantageous in that it is easy to flow oil while making it difficult to flow oil.

Therefore, in the bearing part structure according to this embodiment formed as described above, the bearing B in which the bush 1 is fixed in the rod body insertion hole B1 in advance is mounted on the open end of the cylinder body C. Thus, communication between the oil chamber R3 below the bush 1 and the oil sump chamber R2 above the bush 1 via the air vent groove 1a is permitted.

[0035] Even if oil mixed with air accumulates in the oil chamber R3 in the cylinder body C due to the operation state of the hydraulic shock absorber, when the pressure in the cylinder body C is increased, this air mixed oil is reduced. The oil is discharged to the reservoir R2 via the air vent groove 1a.

At this time, the air vent groove 1a allows the passage of air while preventing the passage of oil to the oil sump chamber R2 when the pressure inside the cylinder body C is increased, while the negative pressure inside the cylinder body C is maintained. Sometimes, it is set so as to exert a trapping effect of preventing the suction of air from the oil reservoir R2, so that only the air separated from the oil mixed with the air stored in the oil chamber R3 is the air vent groove 1a. Through the oil sump chamber R
2, that is, discharged to the reservoir chamber R1.

As a result, the accumulation of oil mixed with air in the oil chamber R3 can be avoided, and the oil mixed with air is not mixed into the oil in the oil chamber R3.

[0038]

As described above, according to the present invention, the bush held by the bearing mounted on the open end of the cylinder body has the air vent groove on the outer peripheral surface thereof.
Even if oil mixed with air accumulates in the oil chamber below the bush, the air can be discharged to the oil chamber above the bush, that is, the reservoir chamber on the outer peripheral side of the cylinder body.

At this time, the air vent groove prevents the oil from flowing into the oil sump chamber when the pressure inside the cylinder is increased, and allows the air to pass therethrough, and sucks the air from the oil sump chamber when the negative pressure inside the cylinder is negative. It is set so as to exhibit a trapping effect of preventing oil from flowing out. Only the air separated from the oil mixed with the air accumulated in the oil chamber is discharged to the reservoir chamber, and the air escapes to the oil chamber. Oil will be left behind.

Since the oil mixed with the air does not mix into the oil in the oil chamber, inconveniences such as instability of the damping force generated when the hydraulic shock absorber is operated and adiabatic compression are generated. Will not be invited.

As a result, according to the present invention, the air is mixed in such a manner that the air remaining in the oil chamber below the bush held by the bearing mounted on the open end of the cylinder is discharged to the outside of the cylinder. Not only is it ideal for preventing oil from remaining in the cylinder body, it can be implemented with simple work changes without completely changing the design of the bush, and the unnecessary cost of hydraulic shock absorbers can be reduced. There is an advantage that it is most suitable for preventing an increase in the hydraulic shock absorber in expecting an increase in versatility.

[Brief description of the drawings]

FIG. 1 is a development view partially showing a bush according to an embodiment of the present invention in a flat plate state.

FIG. 2 is a view showing a bush according to another embodiment, similarly to FIG. 1;

FIG. 3 is a view showing a bush according to still another embodiment, similarly to FIG. 1;

FIG. 4 is a partial cross-sectional front view showing a hydraulic shock absorber having a bearing structure as a conventional example, partially cut away.

5 is a view showing a bush as a conventional example in FIG. 4, similarly to FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bush 1a Air release groove B Bearing B1 Rod body insertion hole B2 Upper flange part B3 Oil leakage recovery groove B4 Oil leakage recovery hole B5 Connection part C Cylinder O External cylinder R Rod body R1 Reservoir chamber R2 Oil reservoir Chamber R3 Oil Chamber S Seal Case

Claims (1)

[Claims] An inner peripheral surface of a rod body insertion hole formed in a shaft core portion of a bearing mounted on an open end of a cylinder body is held adjacent to an inner peripheral surface thereof, and the inner peripheral surface of the cylinder body is provided with a cylinder body. In a bearing portion structure having a bush for slidingly contacting an outer peripheral surface of a rod body which is protruded and retracted, an oil chamber in a cylinder body below the bush is provided on an outer peripheral surface of the bush in an oil sump chamber above the bush. An air vent groove for communication is formed, and this air vent groove prevents the passage of air while preventing the oil from flowing into the oil sump chamber when the pressure inside the cylinder is increased, and the oil sump is formed when the pressure inside the cylinder body becomes negative. The bearing structure is set so as to exhibit a trapping effect of preventing air from being sucked from the chamber.