JPH11159617A - Bearing structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent oil mixing air from being left in a cylinder unit. SOLUTION: In an internal periphery of a rod unit insertion hole 1a mounted in an opening end of a cylinder unit to be formed in a shaft core part, a periphery of a rod unit R protruding/sinking relating to the cylinder unit is brought into slide contact by a bush B, a bearing main unit 1 holding the bush B, while continued to a fixing part 11 fixing the opening end of the cylinder unit, is diametrically contracted to be extended downward, and the rod unit insertion hole 1a is formed to hold the bush B by a hold part 12. In a bearing structure formed by having the hold part 12, the fixing part 11 has an air bleed groove 11a connecting a space A formed between a periphery of the hold part 12 and an internal periphery of the cylinder unit to a peripheral side of the cylinder unit, this air vent groove, when a high pressure is generated in the cylinder unit, while impeding passing of oil to the peripheral side of the cylinder unit, permits passing of air, and when a negative pressure is generated in the cylinder unit, suction of air from the peripheral side of the cylinder unit is impeded by a trap effect, so as to display the trap effect, and the groove is set.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an improvement in a bearing structure in a hydraulic shock absorber and the like.

[0002]

2. Description of the Related Art For example, a rod body such as a piston rod which is disposed at an open end of a cylinder body such as a cylinder constituting a hydraulic shock absorber and which also constitutes a hydraulic shock absorber is slid on an axis thereof. There have been various proposals for a bearing structure that can be inserted as much as possible, but in recent years, the bearing body that constitutes the bearing structure is formed not by using a conventional sintered steel but by pressing a metal material such as gunmetal. There is a proposal that it will be.

That is, as shown in FIG. 7, a bearing body 1 mounted on an open end of a cylinder body C has a thinner iron-based material such as gunmetal or steel as compared with a case where it is made of sintered steel. It is assumed that it is formed by press working on a metal material containing.

The bearing body 1 has a cylindrical bush B fixed to the inner periphery of a rod body insertion hole 1a formed in the shaft core, and a rod body R formed on the inner periphery of the cylindrical bush B. Is slid in contact with the outer periphery of the rod body R to prevent permanent eccentricity or falling of the rod body R.

Therefore, it is important that the bearing body 1 is formed so as to prevent permanent eccentricity or falling of the rod body R, that is, to have a predetermined durability. It is stated that when this is formed by pressing a metal material such as gunmetal, it can sufficiently meet the demand while reducing the weight as compared with the case where it is formed of sintered steel.

On the other hand, when the bearing body 1 is formed by pressing a metal material, a gap is provided between the outer periphery of the holding portion 12 continuous with the fixing portion 11 of the bearing body 1 and the inner periphery of the cylinder C. A is formed, which is caused by the intention of reducing the weight of the bearing body 1.

However, when the gap A is formed, the air-mixed oil is more likely to accumulate therein, and the air-mixed oil accumulates here, for example, when the oil temperature is lowered, such as below the bearing body 1. That is, the oil is mixed with the oil in the oil chamber R1 in the cylinder body C.

[0008] When air-mixed oil is mixed into the oil in the oil chamber R1, the generated damping force at the time of operation of the hydraulic shock absorber becomes unstable, and adiabatic compression occurs. This will lead to malfunctions.

Therefore, as shown in FIG.
Changing the shape of the bearing body 1 to eliminate
That is, the fixing unit 11 is made longer and
It can be proposed that the holding unit 12 be continuous.

However, in this case, not only does the weight of the bearing body 1 increase, but also, for example, in a strut-type hydraulic shock absorber, the diameter of the rod body R becomes relatively large and the cylinder body C and the cylinder body C become larger. Since there is not enough room with the rod body R, it is difficult to perform complicated press molding, and even if it is feasible, there is a problem that the cost increases.

It should be noted that the above description, that is, the formation of the air gap A in order to reduce the weight of the bearing body 1, the accumulation of oil mixed with air in the air gap A, and the formation of the air gap A The generation of unstable damping force due to the incorporation of the air-mixed oil accumulated in A into the oil in the oil chamber R1 in the cylinder body C occurs when the bearing body 1 is formed of sintered steel. It is the same even if there is.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to accumulate in a gap formed between an upper end portion of a cylinder body and a bearing body constituting a bearing. An object of the present invention is to provide a bearing structure which is optimal for discharging air to the outside of a cylinder body and preventing oil mixed with air from remaining in the cylinder body.

[0013]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the construction of the present invention is basically based on a rod body insertion hole formed in a shaft core part which is mounted on an open end of a cylinder body. A bearing body that holds a bush that slides the outer periphery of a rod body that protrudes and retracts with respect to the cylinder body around the periphery, and a fixing unit that fixes the open end of the cylinder body. In a bearing structure having a holding portion that extends and forms a rod body insertion hole to hold a bush, a fixing portion is formed between an outer periphery of the holding portion and an inner periphery of the cylinder body. The air vent groove communicates with the outer peripheral side of the cylinder body, and this air vent groove allows the passage of air while preventing the passage of oil to the outer peripheral side of the cylinder body when the pressure in the cylinder body is increased. Inside the cylinder It is set so as to exert a trap effect which prevents the suction of air from the outer peripheral side of the cylinder body at a negative pressure and comprising.

More specifically, it is preferable that the bearing body is formed by pressing a metal material such as gunmetal.

The air vent groove formed in the fixing portion is connected to the fixing portion so that the upper side of the bearing body and the outer peripheral side of the cylinder body can communicate with each other. It may be extended to an air vent groove formed in a flange having a communicating through hole.

At this time, the air vent groove formed in the flange portion is disposed so as not to interfere with the oil leakage collecting groove and the through hole formed in the flange portion.

In the case where the hydraulic shock absorber is set to a double cylinder type having an outer cylinder on the outer peripheral side of the cylinder body, the outer peripheral side of the cylinder body is a reservoir chamber, and the reservoir chamber is provided inside the cylinder body. Assume that it is communicated with the oil chamber.

[0018]

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

Incidentally, in this double cylinder type hydraulic shock absorber, an outer cylinder O is arranged on the outer peripheral side of the cylinder body C, and the cylinder body C is disposed between the outer cylinder O and the cylinder body C. (See FIG. 7), and this reservoir chamber R2 communicates with an oil chamber R1 in the cylinder body C (not shown).

First, the bearing structure according to the embodiment of the present invention, as shown in FIG. 1, basically has the same structure as the above-described conventional bearing structure. It has a bearing body 1 configured.

That is, first, in the illustrated embodiment, the bearing main body 1 is thinner than the case where it is made of sintered steel, and has no 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 or a metal tube containing an iron-based material such as gunmetal or steel, which can be expected to have sufficient durability, is selected and formed by press working.

The bearing body 1 is mounted on the open end of the cylinder body C, and is formed into a cylindrical bush B in a rod body insertion hole 1a formed in a shaft core portion thereof (a virtual line diagram in FIG. 1). (See the phantom diagram in FIG. 1) is inserted through the rod body R (see the phantom diagram in FIG. 1) with the intervention of the rod body R.

Next, the bearing body 1 includes a fixing section 11 for fixing the open end of the cylinder body C to the outer periphery thereof,
The fixing portion 11 has a holding portion 12 which is reduced in diameter while extending downward while being continuous with the fixing portion 11, forms the rod insertion hole 1 a, and holds the bush B on the inner periphery thereof.

In the bearing body 1, the fixing portion 11 has a gap A formed between the outer periphery of the holding portion 12 and the inner periphery of the cylinder C,
That is, the air vent groove 11 communicating with the reservoir chamber R2.
a.

The air vent groove 11a is basically configured to discharge the air separated from the air-mixed oil accumulated in the gap A into the reservoir chamber R2 on the outer peripheral side of the cylinder body C. But it is preferable that the cylinder C
When the pressure inside the cylinder is increased, the passage of the air is allowed while preventing the passage of oil to the reservoir chamber R2, and the cylinder body C
It is preferable to set a configuration in which a trap effect for preventing suction of air from the reservoir chamber R2 is exerted when the pressure in the inside is reduced.

Incidentally, a flange portion 13 is continuous with the fixing portion 11, and the flange portion 13 has
It is assumed that a groove 13a for collecting oil leakage which enables communication between the upper side of the bearing body 1 and the reservoir chamber R2 which is an outer peripheral side of the cylinder body C, and a through-hole 13b communicating with the groove 13a are formed. (See the right part in FIG. 1).

A connecting portion 14 is connected to the flange portion 13, and the connecting portion 14 has an outer cylinder O.
It is assumed that the upper end of (see FIG. 7) is continuously provided with the seal case S (see FIG. 7) interposed.

As shown in FIGS. 2 and 3, the air vent groove 11a is formed by cutting the outer periphery of the fixing portion 11 into a narrow groove shape, and the lower end thereof is formed in the fixing portion 11a.
The outer periphery of the holding portion 12 and the cylinder body C
Is communicated with a gap A that appears between the inner circumference of the airbag and the inner circumference of the airbag.

Further, it is assumed that the upper end of the air vent groove 11a is set so as to open toward the reservoir chamber R2 side. In the illustrated embodiment, the upper end of the flange portion 13 which is continuous with the fixing portion 11 is formed. The air vent groove 13c formed on the lower surface is extended to communicate with the air vent groove 13c.
It is stated that the opening of c into the reservoir chamber R2 results in the communication with the reservoir chamber R2.

Incidentally, the air vent groove 13c formed in the flange portion 13 is communicated with a groove 14a formed in the same manner on the so-called inner peripheral surface of the connecting portion 14, as shown by an imaginary line in FIG. It is good.

In this case, the air vent groove 11
In view of the fact that the a and 13c are formed in advance when the bearing body 1 is pressed, that is, exactly before the pressing, the groove 14a is set to extend to the air vent groove 13c. It can be said that such an operation is advantageous in that it simplifies the so-called operation and simplifies the configuration of a jig used at that time.

The air vent groove 13c formed in the flange portion 13 is of course positioned and formed so as not to interfere with the oil leakage collecting groove 13a and the through hole 13b.

On the other hand, the intermediate portion of the air vent groove 11a allows the above-mentioned air to pass while preventing the passage of oil to the reservoir chamber R2 when the pressure in the cylinder body C is increased. It is important to set a trapping effect to prevent the suction of air from the reservoir chamber R2 when the pressure in the C is reduced to a negative pressure. In the illustrated embodiment, the horizontal portion ( The length is set to be large (not shown) so that air can flow while oil does not easily flow.

That is, even when the upper end position and the lower end position of the air vent groove 11a are close to each other, if the pressure inside the cylinder body C is increased by increasing the stroke therebetween, the oil accumulated there may be removed. While allowing only the air to pass to the outside while preventing the outflow, if the pressure in the cylinder body C is reduced to a negative pressure, it is set so as to prevent the suction of the air from the outside by the oil accumulated therein. Just do it.

Therefore, instead of setting the length of the horizontal portion to be large as described above, for example, as shown in FIG. 4 and FIG. 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.

The cross-sectional shapes of the air vent grooves 11a and 13c may be set arbitrarily. For example, the cross-sectional shapes may be triangular as shown in FIG. 3 or semi-circular as shown in FIG. In this case, it is advantageous in that the configuration of the jig can be simplified, and as shown in FIG. 5, when it is formed in a square shape and its depth is adjusted, it is easy to flow oil while making it difficult for oil to flow. This is advantageous.

Therefore, in the bearing structure formed as described above, the bearing body 1 is
The gap A appears between the outer periphery of the holding portion 12 that is continuous with the fixing portion 11 of the bearing body 1 and the inner periphery of the cylinder C by being attached to the opening end of the bearing body 1.

At this time, an air vent groove 11a which enables communication between the gap A and the reservoir chamber R2, which is the outer peripheral side of the cylinder body C, on the outer periphery of the fixing unit 11 which makes the inner periphery of the open end of the cylinder body C adjacent. Is formed, the above gap A
Even if the oil mixed with air accumulates, the oil mixed with air can be discharged to the reservoir chamber R2.

However, the air release groove 11a
Allows the passage of air while preventing the passage of oil to the reservoir chamber R2 when the pressure in the cylinder body C is increased, and prevents the suction of air from the reservoir chamber R2 when the pressure in the cylinder body C is reduced to negative pressure. Since it is set so as to exhibit the trapping effect, only the air separated from the air-mixed oil accumulated in the gap A is discharged to the reservoir chamber R2.

As a result, it is possible to avoid the accumulation of oil mixed with air in the gap A, and the oil mixed with air in the oil chamber R1 in the cylinder body C below the bearing body 1. No longer mixed.

In the above-described embodiment, the air vent groove 11a formed in the fixing portion 11 is extended so as to communicate with the air vent groove 13c formed in the flange portion 13 which is continuous with the fixing portion 11, and is formed in the reservoir chamber R2. Although it is assumed that the communication is established, the formation of the air vent groove 13c may be omitted as shown in FIG.

That is, as shown in the right diagram in FIG.
Assuming that a raised portion 13d is formed partially on the lower surface of the flange portion 13, by locking the upper end of the cylinder body C to the raised portion 13d, the portion where the raised portion 13d is not formed and the cylinder body C A gap a is formed between the upper end and the air vent groove 1 formed in the fixing portion 11 in the gap a.
1a is set to open.

Therefore, in the case of this embodiment, it is obvious that predetermined air bleeding is realized by the air bleeding groove 11a. By setting it to be formed below the groove 13a, it is possible to avoid the possibility that the flange portion 13 is weakened by the formation of the groove 13a.

The above description has been made by taking as an example the case where the bearing body 1 is formed by pressing a metal material such as gunmetal. However, from the point of view of the present invention, the bearing body Even when 1 is made of sintered steel, the same configuration can be achieved, and
Needless to say, the same function and effect can be expected.

[0045]

As described above, according to the present invention, the fixing portion of the bearing body mounted on the open end of the cylinder body has the air vent groove on the outer periphery adjacent to the inner periphery of the cylinder body. Therefore, even when oil mixed with air accumulates in a gap that appears between the outer periphery of the lower holding portion continuous to the fixing portion and the inner periphery of the cylinder body when fixing the bearing body to a predetermined position, The cylinder body can be discharged to a reservoir chamber on the outer peripheral side.

At this time, the air vent groove prevents the passage of oil to the reservoir chamber when the pressure inside the cylinder is increased, and allows the air to pass therethrough. At the same time, when the pressure inside the cylinder is reduced, the air is sucked from the reservoir. Since it is set so as to exhibit the trapping effect of preventing, only the air separated from the oil mixed with the air that accumulates in the gap is discharged to the reservoir chamber, and the inside of the cylinder body below the bearing body is removed. The oil that has escaped the air will return to the oil chamber,
Then, since air-mixed oil is not mixed with the oil in the oil chamber, the mixed damping oil becomes unstable due to the mixing of the air-mixed oil, and the adiabatic compression is developed. No troubles such as inconvenience will be caused.

As a result, according to the present invention, the air trapped in the gap formed between the upper end portion of the cylinder body and the bearing body constituting the bearing is discharged to the outside of the cylinder body to mix the air. Not only do not allow the remaining oil to remain in the cylinder body, but also can be carried out with simple incidental work without any new design of the bearing body. There is the advantage that the increase in cost is prevented and the versatility of the hydraulic shock absorber is expected to be improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a bearing structure according to an embodiment of the present invention together with a cylinder body.

FIG. 2 is an enlarged partial longitudinal sectional view showing a main part in FIG. 1;

FIG. 3 is a partial cross-sectional development view showing an air vent groove viewed at the position of line YY in FIG. 2;

FIG. 4 is a view showing an air vent groove according to another embodiment, similarly to FIG. 3;

FIG. 5 shows an air vent groove according to still another embodiment in FIG.
FIG.

FIG. 6 is a partial longitudinal sectional view showing a bearing structure according to another embodiment of the present invention, similarly to FIG.

FIG. 7 is a partially sectional front view showing a hydraulic shock absorber having a bearing structure as a conventional example, partially cut away.

FIG. 8 is a longitudinal sectional view showing another conventional bearing structure, similarly to FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bearing main body 1a Rod body insertion hole 11 Fixing part 11a, 13c Air vent groove 12 Holding part 13 Flange part 13a Oil leakage collecting groove 13b Oil leakage collecting hole 13d Raised part 14 Connecting part 14a Groove a Gap A Gap B Bush C Cylinder O Outer cylinder R Rod R1 Oil chamber R2 Reservoir chamber S Seal case

Claims (2)

[Claims] 1. A bearing body for holding a bush attached to an open end of a cylinder body and slidingly contacting an outer periphery of a rod body which is protruded and retracted from the cylinder body with an inner periphery of a rod body insertion hole formed in a shaft core. Has a fixing portion for fixing the opening end of the cylinder body, and a holding portion for reducing the diameter and extending downward while being continuous with the fixing portion and forming a rod body insertion hole to hold the bush. In the bearing structure, the fixing portion has an air vent groove for communicating a gap formed between the outer periphery of the holding portion and the inner periphery of the cylinder body with the outer peripheral side of the cylinder body. A trapping effect that prevents the passage of oil to the outer periphery of the cylinder body when the pressure inside the body is increased and allows air to pass, and prevents the suction of air from the outer periphery of the cylinder body when the pressure inside the cylinder is reduced to negative pressure. Departure Bearing structure characterized by being set to be able to perform 2. The bearing structure according to claim 1, wherein the bearing body is formed by pressing a metal material such as gunmetal.