JP3156208B2 - Shock absorber ventilation structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shock absorber for a vehicle, and more particularly to an improvement of a ventilation structure which can prevent a viscous lubricant such as grease from leaking and falling between a bearing and a tube sliding surface. .

[0002]

2. Description of the Related Art For example, there is a shock absorber having a structure shown in FIG. In this shock absorber 40, an inner tube 42, whose lower end is also closed, is slidably inserted in the axial direction into an outer tube 41 whose lower end (right end in the drawing) is closed by an end face plate 50. A piston 44 having a damping force variable mechanism 43 is inserted and arranged in the oil chamber B of the tube 42, and the piston 44 is connected to the end plate 50 of the outer tube 41 via a piston rod 45.
It is of a structure fixed to.

[0003] Dry metals 47, 47 as sliding bearings are press-fitted and fixed to the upper end 41 a and the central portion 41 b of the inner surface of the outer tube 41, that is, to the overlapping portion of both tubes. A grease 48 is filled in a lubricating space 46 formed by the two tubes 41 and 42. Thereby, the sliding resistance between each of the dry metal 47 and the inner tube 42 is reduced. The lower half of the outer tube 41 is a sealed space A, which prevents dust and muddy water from splashing on the sliding portion and the lower end of the inner tube 42.

[0004]

In the shock absorber 40, when the sliding surface between the inner tube 42 and the dry metal 47 generates heat due to the repeated expansion and contraction, the heat reduces the viscosity of the grease 48. If the decrease in the viscosity is large, the conventional structure described above has a problem that the grease 48 easily leaks from the sliding surface between the inner tube 42 and the dry metal 47, and as a result, the sliding resistance increases and the wear tends to occur. .

Therefore, it is conceivable that a general rubber oil seal is fitted to the overlapping portion of the inner tube 42 and the outer tube 41 to prevent the grease 48 from leaking. However, when such an oil seal is provided, the air chamber A and the lubricating space 48 are completely shut off. For example, when the shock absorber 40 is extended, the pressure in the air chamber A decreases, and , The oil seal cannot withstand this pressure difference, and there is a concern that grease may be sucked into the air chamber A. In this case, if the above-mentioned sucking is prevented by increasing the tightness of the oil seal and making the oil seal firmly adhere to the sliding surface, the sliding resistance becomes excessively large.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and has a ventilation structure for a shock absorber which can prevent leakage of a viscous lubricant into an air chamber A without increasing sliding resistance. It is intended to provide.

[0007]

SUMMARY OF THE INVENTION Accordingly, the present invention provides an inner tube in which an inner tube is axially slidably inserted into an outer tube whose end is closed, and a pair of sliding bearings is provided in an overlapping portion of the two tubes. A shock absorber in which a viscous lubricant is filled in a lubricating space formed by the two bearings and the two tubes, and an air chamber formed by the outer tube and the inner tube; And a sealing member that suppresses the leakage of the viscous lubricant to the bearing portion on the air chamber side, and that allows ventilation between the air chamber and the lubricating space. It is characterized by being arranged.

Here, for the seal member of the present invention, for example, a synthetic fiber bonded with an adhesive and formed into a ring shape can be adopted, whereby the passage of grease can be suppressed while allowing air to flow. .

[0009]

According to the ventilation structure of the shock absorber according to the present invention, since a sealing member that suppresses leakage of a viscous lubricant such as grease and allows ventilation is adopted, the sliding heat between the tube and the bearing is adopted. Thus, even if the viscosity of the viscous lubricant is reduced, it can be prevented from leaking, and as a result, the sliding resistance can be increased and the tube and the like can be prevented from being worn.

Further, since the seal member of the present invention allows ventilation between the air chamber and the lubricating space, if the pressure in the air chamber decreases when the shock absorber extends, the pressure in the lubricating space also decreases, The pressure difference between the two chambers does not increase, so that the problem of sucking out the viscous lubricant due to the decrease in the air pressure in the air chamber can be avoided.

Further, since the seal member of the present invention does not need to have a very high degree of adhesion to the sliding surface, the sliding resistance does not become excessive.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIGS. 1 and 2 are views for explaining a ventilation structure of a shock absorber according to a first embodiment of the present invention. In the present embodiment, a case of a strut type shock absorber constituting a suspension system for a front wheel of an automobile will be described as an example.

In FIG. 1, reference numeral 1 denotes a shock absorber having the structure of the present embodiment, which is a lower end (right end in the drawing).
Is closed, an upper tube and a lower end are closed, an inner tube 3 slidably inserted into the outer tube 2, a piston 10 inserted into the tube 3, and a piston 10 10 is the outer tube 2
And a piston rod 6 fixed to the piston rod. The upper end member 3a of the inner tube 3 is supported by a vehicle body frame via a support bracket, and the lower end of the outer tube 2 is supported by a front wheel via a bracket 4 welded thereto.

In the inner tube 3, a free piston 5 that slides on an inner peripheral surface of the inner tube 3 via an O-ring 5a is slidably disposed in the axial direction. It is divided into a gas chamber C and an oil chamber B. Further, the oil chamber B is divided by the piston 10 into an upper oil chamber B1 and a lower oil chamber B2.

The piston rod 6 is arranged on the axis of the outer tube 2. The lower end 6a of the piston rod 6 is fixedly fastened to an end plate 7a welded to the lower end of the outer tube 2 by a nut 7b. ing. Reference numeral 22 denotes a bound stopper that is fitted to the lower end 6a of the piston rod 6 and absorbs an impact load from the inner tube 3. The upper end 6b of the piston rod 6 is inserted into the oil chamber B through the cap 8 and the stopper member 9 attached to the lower end 3b of the inner tube 3. The stopper member 9 is fixed to the inner surface of the inner tube 3 by a circlip 9a, and a seal ring 9b is mounted on the outer peripheral surface and the inner peripheral surface of the stopper member 9.

A stopper member 21 is fixed to the upper end 6b of the piston rod 6 with a circlip, and the piston 10 is further fixed by a nut 11. Oil holes 10a and 10b are formed in the piston 10, and the oil holes 10a and 10b are closed by valve plates 10c and 10d that generate a damping force when expanded and compressed. A spherical valve element 14 is disposed in an oil hole 12a formed in the axis of the piston rod 6 so as to be urged in a closing direction by a spring. Reference numeral 13a denotes a valve body for adjusting the passage area of the oil hole 12a, which is led out of the lower end of the outer tube 2 by the adjustment shaft 13 and can be adjusted from the outside.

Bearings 17a and 17b are press-fitted and fixed to the upper end 2a and the center 2c of the outer tube 2 so as to slide on the outer peripheral surface of the inner tube 3. A grease 16 is filled in a lubricating space 15 surrounded by the tubes 2 and 3 and the bearings 17a and 17b.

The upper end 2a of the outer tube 2
, A sleeve 18 is screwed, and a gap between the sleeve 18 and the inner tube 3 is sealed with a rubber seal 19. The seal 19 has an upwardly extending dust lip and a downwardly extending grease lip to prevent dust from entering the interior and to be surrounded by the inner tube 3, the sleeve 18, and the bearing 17a. Grease 16 is prevented from leaking. The upper projecting portion of the inner tube 3 is surrounded by a dust cover 20.

The lower bearing 17b of the outer tube 2
A seal member 25 which is a feature of the present embodiment is provided
Which is in sliding contact with the outer peripheral surface of the inner tube 3. As shown in FIG. 1, the seal member 25 has a stepped portion 2b formed on the inner peripheral wall of the outer tube 2 fitted with an annular support plate 26 made of resin or metal. It is fixed by being sandwiched between the bearings 17b. Note that the seal member 25 may be bonded and fixed to the support plate 26.

The seal member 25 is formed by, for example, combining synthetic fibers with an adhesive and forming the same into a ring shape. Specifically, a commercially available New Fabric Seal (registered trademark) is used. ing. This sealing member 2
Reference numeral 5 has air permeability and a function of inhibiting the passage of grease.

Next, the operation and effect of this embodiment will be described. In the shock absorber 1 of the present embodiment, when the outer and inner tubes 2 and 3 are repeatedly expanded and contracted due to irregularities on the road surface, the viscosity of the grease 16 is reduced due to sliding heat or the like. In this embodiment, since the seal member 25 is disposed below the lower bearing 17b, even if the viscosity of the grease 16 is significantly reduced, the leakage of the grease 16 into the air chamber A is prevented by the seal member 25. Can be stopped.

In the extension stroke of the shock absorber 1, when the volume of the air chamber A increases and the internal pressure starts to decrease, the sealing member 25 has air permeability. The pressure also drops and there is almost no pressure difference between the two chambers. Therefore grease 16
Is not sucked into the air chamber A, and the grease 16 can be prevented from leaking from this point as well.

As described above, according to the present embodiment, since the seal member 25 for preventing the grease from leaking is provided in the lower bearing 17b of the outer tube 2, the grease 16 can be prevented from leaking, and the lubrication failure is caused. This can prevent an increase in sliding resistance and the occurrence of wear.

Further, since the seal member 25 of this embodiment has a function of ensuring the flow of air, the air chamber A
The pressure difference between the oil and the lubrication space 15 can be suppressed, and leakage of the grease 16 into the air chamber A due to the pressure difference can be prevented. In addition, since the seal member 25 does not need to be strongly adhered to the sliding surface, the sliding resistance does not become excessive.

FIGS. 3 and 4 are views for explaining a shock absorber according to a second embodiment of the present invention. In the drawing, the same reference numerals as those in FIGS. 1 and 2 indicate the same or corresponding parts.

The shock absorber 30 of this embodiment is used for a front wheel suspension device of a scooter, and has the following structure. Outer tube 31 whose lower end is closed
The inner tube 32 whose upper end is closed is slidably inserted into the inside, and a coil spring is provided between a free plate 33 disposed on a lower end surface 32 a of the inner tube 32 and the bottom surface of the outer tube 31. The inner tube 32 is constantly urged by the spring 34 to an extended state. Here, the insides of the two tubes are defined by the free plate 33 into a first air chamber A and a second air chamber A ′ which are hermetically closed.

A pair of bearings 17a and 17b are disposed and fixed at the insertion overlap portion between the inner tube 32 and the outer tube 31, and the lubrication space 15 between the bearings 17a and 17b is filled with grease 16. ing. Here, the upper bearing 17a is fixed to the outer tube 31, and the lower bearing 17b is fixed to the inner tube 32, respectively. Therefore, the volume of the lubrication space 15 changes according to the expansion and contraction of the shock absorber 30.

At the lower end of the inner tube 32, a seal member 35 which is a feature of the present embodiment is provided. This seal member 35 is formed by bonding synthetic fibers with an adhesive in the same manner as in the first embodiment, has air permeability,
In addition, it has a function of stopping the passage of grease, and is fixed as follows. As shown in FIG. 4, a stepped portion 32b is formed at the lower end of the inner tube 32, the seal member 35 is fitted to the stepped portion 32b, and the support plate 36 is brought into contact with the lower surface of the seal member 35. Clip 37
It is fixed by retaining. Note that the seal member 35 may be bonded to the support plate 36.

In the shock absorber 30 of this embodiment, the leakage of the grease 16 can be reliably prevented because the seal member 35 prevents the leakage of the grease. Moreover, since it has air permeability, the pressure difference between the air chamber A and the lubricating space 15 can be suppressed, and suction of the grease 16 can be avoided. In the case of the present embodiment, the volume of the lubricating space 15 decreases as the volume of the air chamber A increases in the extension stroke. Therefore, arranging the seal member 35 having air permeability is more effective.

[0030]

As described above, according to the ventilation structure of the shock absorber according to the present invention, the sealing member for preventing the leakage of the viscous lubricant to the bearing portion on the air chamber side and for allowing the air chamber and the lubricating space to ventilate. Has the effect of preventing the leakage of the viscous lubricant, suppressing the pressure difference between the air chamber and the lubricating space, avoiding the suction of the viscous lubricant into the air chamber, and has the effect of reducing the sliding resistance. It won't be too big.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a main part for explaining a ventilation structure of a shock absorber according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the shock absorber of the first embodiment.

FIG. 3 is a cross-sectional view illustrating a ventilation structure of a shock absorber according to a second embodiment of the present invention.

FIG. 4 is an enlarged sectional view of a main part of the shock absorber of the second embodiment.

FIG. 5 is a cross-sectional view showing a general shock absorber.

[Explanation of symbols]

 1,30 Shock absorber 2,31 Outer tube 3,32 Inner tube 15 Lubrication space 16 Grease (viscous lubricant) 17a, 17b Bearing 25,35 Seal member A Air chamber

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16F 9/16 F16F 9/32

Claims (1)

(57) [Claims] An inner tube is axially slidably inserted into an outer tube whose end is closed, and a pair of slide bearings is disposed at an insertion overlapping portion of both tubes.
In a shock absorber in which a viscous lubricant is filled in a lubricating space formed by the two bearings and the two tubes, an air chamber formed by the outer tube and the inner tube and the lubricating space are ventilated. In the ventilation structure, a sealing member that suppresses leakage of the viscous lubricant in the bearing portion on the air chamber side and that allows ventilation between the air chamber and the lubricating space is provided. Characteristic shock absorber ventilation structure.