JPH07238973A - Hydraulic shock absorber - Google Patents

Abstract

PURPOSE:To eliminate any air spring effect of a hydraulic shock absorber as well as to check an outflow of hydraulic fluid content with the runoff of air. CONSTITUTION:Each of atmosphere open holes 28 and 29 opening an air chamber A1 in a slide valve 21 to the atmosphere is formed in a joint bolt 23 installed on top of this slide valve 21 and an upper spring seat 24 installed in an upper part of this joint bolt 23, and further an opening 37 adjoining the air chamber A1 is formed in an inner part of the joint bolt 23, and in this constitution, it is provided with an air guide member 33 having two ring recess parts 35 and 36 serving as an air passage guiding the air taken in from the opening 37 to the atmosphere open hole 28.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic shock absorber used in a vehicle or the like, and more particularly to a cartridge type hydraulic shock absorber.

[0002]

2. Description of the Related Art As a hydraulic shock absorber used in a vehicle or the like, as disclosed in Japanese Utility Model Publication No. 57-47485, a piston rod is inserted into a cylinder, and a tip end portion of the piston rod is attached to an inner peripheral surface of the cylinder. A hydraulic shock absorber provided with a sliding piston is made into a cartridge, the cartridge made hydraulic shock absorber is housed in a double pipe, and one end of this double pipe is attached to the vehicle body side and the other end is attached to the wheel side. There is a type in which the piston rod is fixed to the vehicle body side.

However, in this hydraulic shock absorber, the double pipe itself does not contribute to the rigidity, and the rigidity is determined only by the piston rod.
As described in Japanese Patent Publication No. 3-109047, a cylinder and a piston rod having a piston fixed in sliding contact with the inner peripheral surface of the cylinder are preassembled to form a cartridge,
There is a hydraulic shock absorber in which this cartridge is assembled in a shock absorber.

[0004]

In the hydraulic shock absorber described above, not only the piston rod but also the inner case contributes to the rigidity, but the oil chamber in the cylinder of the cartridge and the oil lock chamber in the outer case communicate with each other. Therefore, only the same hydraulic oil that generates the damping force and the hydraulic oil that generates the oil lock load can always be used, and the selection of the oil lock characteristics is limited.

Therefore, an outer case is provided on the outer circumference of the cylinder of the hydraulic shock absorber to form an oil lock chamber independent of the oil chamber in the cylinder, and a slide pipe that slides in the outer case by being driven by a piston rod is formed. Although it may be possible to provide it, in this case, the volume of the air chamber formed in the slide pipe decreases or increases with the operation of the damper, so that an air spring effect occurs during compression.

Therefore, it is conceivable to form an atmosphere opening hole which communicates with the top of the slide pipe and the upper spring seat provided on the top of the slide pipe, but in this case, the air is mixed with the air flowing out from the atmosphere opening hole. As a result, hydraulic oil that generates an oil lock load may flow out, and the hydraulic oil may decrease, so that the original oil lock characteristic may not be obtained.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention forms an atmosphere opening hole which communicates with each other at the top of a slide pipe and an upper spring seat provided at the top of the slide pipe. An air guide member having an opening facing the air chamber was formed on the inside of the top of the sheet, and an air flow path was provided to guide the air flowing in from the opening to the atmosphere opening hole.

[0008]

[Operation] Since the air chamber in the slide pipe is opened to the atmosphere through the top of the slide pipe and the air release hole of the upper spring seat, the air spring effect at the time of compression can be prevented, and the air chamber of the air pressure can be reduced during the compression stroke. The air flows into the air flow path from the opening of the air guide member and is guided to the atmosphere opening hole of the slide pipe through the air flow path. It is possible to prevent the hydraulic oil from adhering to and leaking from the atmosphere opening hole.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is a sectional view of a hydraulic shock absorber to which the present invention is applied, FIG. 2 is an enlarged sectional view of an essential part of the hydraulic shock absorber, and FIG.
4 is an enlarged plan view of a main part of the hydraulic shock absorber, FIG. 4A is a side sectional view of the air guide member, FIG. 4B is a plan view, and FIG. 5 is an explanatory view of air flow.

The damper 1 unitized is a cylinder 2
A hollow piston rod 4 is inserted from above through a rod guide 3 or the like, and a piston 5 which is in sliding contact with the inner peripheral surface of the cylinder 2 is fixed to the tip end of the piston rod 4, and a damping force is applied to the piston 5. Oil passages 6 and 7 for generation are formed, and valves 8 and 9 for opening and closing these oil passages 6 and 7 are attached.

A bottom piston holder 11 is fixed to the lower part of the cylinder 2, a bottom piston 12 is fitted in the bottom piston holder 11, and a free piston 13 is slidably fitted below the bottom piston holder 11. It is mounted to define an in-cylinder oil chamber S1 and a gas chamber A2, and constitutes an accumulator for absorbing a volume change due to the forward and backward movement of the piston rod 4. Further, a damping force adjusting adjuster rod 14 penetrating the free piston 13 and facing the bottom piston 12 is provided upright.

An outer case 16 is arranged on the outer periphery of the cylinder 2 of the damper 1, and an oil lock chamber 17 independent of the cylinder oil chamber S1 is formed between the outer peripheral surface of the cylinder 2 and the inner peripheral surface of the outer case 16. The oil lock hydraulic oil 18 is put in the lower part of the oil lock chamber 17, and an oil lock piece 19 which also serves as a closing member of the cylinder 2 is provided on the outer peripheral surface of the cylinder 2 below the oil lock chamber 17.

A slide pipe 21 is slidably inserted into the outer case 16 from above, and an oil lock collar 22 fitted to an oil lock piece 19 is fitted to an inner peripheral surface of a lower end portion of the slide pipe 21. ing.

A joint bolt 23 is fixed to the upper end of the slide pipe 21, an upper spring seat 24 is fixed to the joint bolt 23 with a nut member 25, and a lower spring seat 26 is vertically moved on the outer peripheral surface of the outer case 16. A suspension spring 27 is interposed between the upper spring seat 24 and the lower spring seat 26 by screwing as possible.

Further, as shown in FIG. 2, the joint bolt 23 and the upper spring seat 24, which are the tops of the slide pipe 21, are filled with air in the air chamber A1 in the slide pipe 21 as the slide pipe 21 slides. Atmosphere opening holes 28 and 29 are formed for escape.

Here, the upper spring seat 24 is formed with an annular groove 30 facing the atmosphere opening hole 28 of the joint bolt 23, and a filter 31 is built in this annular groove 30 and further opened to the atmosphere as shown in FIG. The hole 29 is formed at a position different from the atmospheric opening hole 28 of the joint bolt 23 in the circumferential direction. The annular groove 30 is provided on the joint bolt 23 side.
May be formed.

On the other hand, inside the joint bolt 23, which is the top of the slide pipe 21, an air guide member 33 for guiding the air in the air chamber A1 to the atmosphere opening hole 28 is provided on the outer periphery of the nut member 32 for fixing the hollow rod 4. Member 3
It is fixed and attached at 4.

As shown in FIG. 4, the air guide member 33 has a double inner annular recess 35 and an outer annular recess 36 which serve as an air flow path, and the inner annular recess 35 has an air chamber A.
1 is formed in the partition wall 33a between the inner annular recess 35 and the outer annular recess 36, and the opening 37 and the circumferential direction 180 are formed.
The communication hole 38 is formed in a positional relationship of °, and the outer annular recess 36
The atmosphere opening hole 28 is exposed. Further, the inner annular recess 35 and the outer annular recess 36 have different axial depths, that is, when the air flows out from the air chamber A1, the inner annular recess 35 on the upstream side and the outer annular recess on the downstream side. It is formed to be deeper than 36.

The air guide member 33 is attached so that the opening 37 of the inner annular recess 35 is located at the same circumferential position as the atmosphere opening hole 28. The air guide member 3
The annular recessed portion of 3 may have a single layer, a triple layer or more, and the positional relationship between the opening and the communicating hole is not limited to the above positional relationship. When the concave portion is formed in n-fold (n is an odd number), the opening is in a positional relationship where the circumferential position is shifted by 180 ° from the atmosphere opening hole, and when the annular concave portion is formed in (n + 1) -fold (n + 1 is an even number), the opening is opened. Can secure the longest air passage when it is mounted in the same positional relationship as the atmospheric opening hole.

Further, a holder 41 is held above the joint bolt 23 via a spherical bearing 40, and a plate 42 attached to this holder 41 is attached to the bolt 4
3 is attached to the vehicle body 44 side.

With the above construction, when the hollow rod 4 descends during the compression stroke of the damper 1, the piston 5
A damping force is generated in the oil passage 6 and the valve 8 of
A damping force is generated by the hydraulic oil equivalent to the advancing volume of the hollow rod 4 flowing through the oil passage of the bottom piston 12 while pushing down the free piston 13, and when the piston rod 4 rises in the extension stroke, the oil of the piston 5 is increased. Road 7
And a damping force is generated in the valve 9.

The volume of the air chamber A1 in the slide pipe 21 decreases as the slide pipe 21 descends following the piston rod 4 as the damper 1 compresses. Are the annular recesses 35 and 36 of the air guide member 33 and the atmosphere opening hole 28,
Since it is opened to the atmosphere via 29, the air spring effect is suppressed because the air escapes to the atmosphere.

Here, as shown in FIG. 5, the air in the air chamber A1 flows into the inner annular recess 35 from the opening 37 of the air guide member 33, and through the inner annular recess 35 into the outer annular recess 36 from the communication hole 38. Inflow and outer annular recess 3
6 is introduced into the atmosphere opening hole 28 through 6 and is opened to the atmosphere through the annular groove 30, the filter 31, and the atmosphere opening hole 29,
Since a sufficient air flow path length is secured from the air chamber A1 to the atmosphere opening hole 28, while the air passes through the annular recesses 35 and 36 of the air guide member 33, the hydraulic oil contained in the air adheres to its wall surface. However, the outflow to the outside through the atmosphere opening hole 28 and the like is suppressed.

Moreover, since the inner annular recess 35 and the outer annular recess 36 of the air guide member 33 are formed with axially different depths, and the upstream annular recess 35 is deepened to provide a step, the air It is possible to further suppress the outflow of the hydraulic oil contained in.

Further, the volume of the air chamber A1 in the slide pipe 21 increases as the slide pipe 21 moves up along with the hollow rod 4 as the damper 1 expands. At this time, the air chamber A1 Is an atmosphere opening hole 28,
Since it is open to the atmosphere via 29 and the air guide member 33, air is sucked from the atmosphere. In this case, since the filter 31 is interposed between the atmosphere opening holes 28 and 29, it is possible to prevent dust from entering and causing malfunction.

Further, the joint bolt 23 side which is the top of the slide pipe 21 or the upper spring seat 2
By forming the annular groove 30 on the fourth side and incorporating the filter 31 in this annular groove 30, the atmosphere opening holes 28, 2
9 does not need to be aligned, and processing of the atmosphere opening holes 28 and 29 and the filter 31 becomes easy.

Moreover, the atmosphere opening hole 28 and the atmosphere opening hole 29
Since it is possible to change the position in the circumferential direction, the working oil in the oil lock chamber 17 can be dog-legged so as not to come out directly from the atmosphere opening hole. Further, by providing the atmosphere opening hole 28 of the slide pipe 21 at the top,
The dead stroke is eliminated and the stroke can be effectively taken.

[0028]

As described above, according to the present invention,
Atmospheres that communicate with each other are formed in the top of the slide pipe and the upper spring seats provided at the top of the slide pipe, and an opening facing the air chamber is formed inside the top of the slide pipe. Since an air guide member with an air flow path that guides air to the atmosphere opening hole is provided, the air spring effect can be suppressed and the outflow of hydraulic oil contained in the air when the air in the air chamber is released to the atmosphere. It is possible to prevent the decrease of hydraulic oil.

In this case, since the air guide member has the annular recess that forms the air flow path, the air flow path can be lengthened, and the more the number of annular recesses, the more the hydraulic oil can be prevented from flowing out. can do. Further, when a plurality of annular recesses are formed, the axial recesses of the annular recesses are formed differently so as to become deeper toward the upstream side, whereby it is possible to further suppress the outflow of hydraulic oil.

[Brief description of drawings]

FIG. 1 is a sectional view of a hydraulic shock absorber to which the present invention is applied.

FIG. 2 is an enlarged sectional view of a main part of the hydraulic shock absorber.

FIG. 3 is an enlarged plan view of an essential part of the hydraulic shock absorber.

FIG. 4A is a side sectional view of an air guide member, and FIG.
Is a plan view of the air guide member

FIG. 5 is an explanatory diagram of an outflow path of air in a compression stroke.

[Explanation of symbols]

1 ... Damper, 2 ... Cylinder, 4 ... Piston rod, 5
... Piston, 12 ... Bottom piston, 13 ... Free piston, 16 ... Outer case, 17 ... Oil lock chamber, 1
9 ... Oil lock piece, 21 ... Slide pipe, 22
… Oil lock collar, 23… Joint bolt, 24
… Upper spring seats, 27… Suspension springs, 28,
29 ... Atmosphere opening hole, 30 ... Annular groove, 31 ... Filter, 3
3 ... Air guide member, 35 ... Inner annular recess, 36 ... Outer annular recess, 37 ... Opening, 38 ... Communication hole.

Claims (3)

[Claims] 1. A hydraulic shock absorber in which a slide pipe is slidably fitted in an outer case, unit dampers are built in the outer case and the slide pipe, and an upper part of the slide pipe is an air chamber. Atmospheres that communicate with each other are formed in the top of the slide pipe and an upper spring seat provided at the top of the slide pipe, and an air guide member is provided inside the top of the slide pipe. A hydraulic shock absorber, characterized in that an opening facing an internal air chamber and an air flow path for guiding the air flowing in from the opening to the atmosphere opening hole are formed. 2. The hydraulic shock absorber according to claim 1,
The hydraulic shock absorber, wherein the air guide member has an annular recess that forms an air flow path. 3. The hydraulic shock absorber according to claim 2, wherein
A hydraulic shock absorber, wherein the annular recesses are provided in double or more, and the annular recesses have different axial depths.