JP2002227900A - Bottom structure of hydraulic shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure a large passage area in a drawing side passage while easily enabling forming of a mold of a bottom piece, and to dispense with a centering plate. SOLUTION: In this bottom structure of the hydraulic shock absorber 10, the drawing side passage 46 connecting a reservoir chamber 41 between an outer cylinder 12 and an inner cylinder 13 to a damper chamber 29A inside the inner cylinder 13 is formed in a plurality of round holes 46A arranged between a plurality of leg parts 51 projected on a bottom surface of the bottom piece 17, and a centering projection is integrally formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a bottom structure of a hydraulic shock absorber.

[0002]

2. Description of the Related Art Conventionally, as a hydraulic shock absorber, a Japanese Utility Model Application No.
As described in Japanese Patent Application Publication No. 3 (1999), there is an apparatus in which an inner cylinder is erected in an outer cylinder, and a lower end of the inner cylinder is supported on a bottom of the outer cylinder via a bottom piece. The bottom piece has a plurality of legs protruding from the bottom surface seated on the bottom of the outer cylinder, and a push-side flow path that connects the reservoir chamber between the outer cylinder and the inner cylinder to the damper chamber inside the inner cylinder. A side channel is provided. The push-side flow path is a flow path that can generate a compression-side damping force when the hydraulic shock absorber is compressed together with the disk valve, and is formed by a plurality of round holes. The pull-side flow path is a flow path that, together with a check valve, sucks and replenishes the oil in the reservoir chamber into the damper chamber when the hydraulic shock absorber is extended.The flow path area is formed as a square hole to improve suction performance. I'm making it big.

Further, in the prior art, a centering member as a separate member is jointly fastened to the bottom piece to secure centering of the inner cylinder with respect to the outer cylinder.

[0004]

Since the bottom piece is usually made of a sintered metal or the like, a mold is required.
The square hole constituting the pull-side flow path is formed by a square pin of a mold. However, square pins do not have general-purpose pins and must be prepared by cutting, making it difficult to create dies, making it difficult to modify or break them, and requiring a long time for maintenance. Impedes the production line efficiency of the shock absorber.

Since the centering member, which is a separate member from the bottom piece, is used, the number of parts and the number of assembling steps are increased, and the productivity of the hydraulic shock absorber is hindered.

An object of the present invention is to ensure a large flow passage area in a pull-side flow passage while easily making a bottom piece mold.

Another object of the present invention is to eliminate the centering member which is a separate member from the bottom piece.

[0008]

According to a first aspect of the present invention, there is provided a hydraulic shock absorber in which an inner cylinder is erected in an outer cylinder, and a lower end of the inner cylinder is supported on a bottom of the outer cylinder via a bottom piece. In the structure, a plurality of circles provided between a plurality of legs protruding from the bottom surface of the bottom piece, a pull-side flow path connecting the reservoir chamber between the outer cylinder and the inner cylinder to a damper chamber inside the inner cylinder. It was formed with holes.

According to a second aspect of the present invention, the centering projection is further formed at a plurality of circumferential positions on the outer periphery of the bottom piece.

According to a third aspect of the present invention, the centering projection is further formed on an outer periphery between a plurality of legs of the bottom piece.

[0011]

According to the first aspect of the present invention, the following operations are provided. Because the pull-side flow path provided in the bottom piece is a round hole,
In the mold for forming the bottom piece with a sintered metal or the like, a portion for forming the pull-side flow path can be formed by a round pin.
Round pins are easy to process and general-purpose pins are also available, making it easy to create molds, easy to repair and replace when damaged, shortening maintenance time, and improving hydraulic shock absorber production line efficiency. Can be improved.

[0012] If the above-mentioned round hole hits the leg portion of the bottom piece, the leg portion is shaved and the stability of the seating of the bottom piece is impaired. Therefore, the hole diameter of the round hole must be made as small as possible. . In the present invention, since the round hole is provided between the legs, the large size can be stabilized without shaving the legs, and the hole diameter of the round hole is increased to secure a large flow passage area in the pull-side flow passage. As a result, it is possible to form a pull-side flow path having good suction performance. In addition, the round pin can be enlarged, and the durability of the mold can be improved.

According to the second aspect of the present invention, the following operations are provided. Since the centering projection is formed on the outer periphery of the bottom piece, the centering property of the inner cylinder with respect to the outer cylinder can be secured while eliminating the centering member separate from the bottom piece. It is possible to reduce the number and improve the productivity of the hydraulic shock absorber.

According to the third aspect of the present invention, the following operations are provided. Since the centering projection is formed on the outer periphery of the thin portion between the legs of the bottom piece, the centering projection is formed on the material such as sintered powder as compared with the case where it is formed on the outer periphery of the thick leg. The filling property of the projection can be improved, and the molding quality of the centering projection can be improved.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a half sectional view showing a hydraulic shock absorber, FIG. 2 is an enlarged sectional view showing a piston valve device, and FIG.
Is an enlarged sectional view showing a bottom valve device, FIG. 4 is a sectional view showing a bottom piece assembly, FIG. 5 shows a bottom piece,
(A) is a sectional view, (B) is a plan view, and (C) is a bottom view.

FIG. 1 shows a double-cylinder hydraulic shock absorber 10 constituting a strut-type suspension, in which a damper tube 11 is a double pipe composed of an outer cylinder 12 and an inner cylinder 13.
In the hydraulic shock absorber 10, a piston rod 14 is inserted into an inner cylinder 13 built in the outer cylinder 12, a vehicle body-side mounting bracket (not shown) is connected to an upper end of the piston rod 14, and a lower end of the outer cylinder 12 is knuckled. The vehicle is connected to the wheel side by a bracket 15 to form a vehicle suspension system.

The hydraulic shock absorber 10 includes a suspension spring (not shown) between a lower spring seat 16 on the outer periphery of the outer cylinder 12 and an upper spring seat (not shown) supported by a mounting bracket at the upper end of the piston rod 14. To absorb the impact force when the vehicle is running.

The hydraulic shock absorber 10 supports the lower end of the inner cylinder 13 centered on the bottom of the outer cylinder 12 via the bottom piece 17 when the inner cylinder 13 is erected and built in the outer cylinder 12. The upper end of the inner cylinder 13 is centered and supported at the upper end opening of the outer cylinder 12 via the rod guide 18. The hydraulic shock absorber 10 has a shaft seal 19 such as an oil seal through which the piston rod 14 penetrates above the rod guide 18.
The shaft sealing portion 19,
The rod guide 18, the inner cylinder 13, and the bottom piece 17 are held between the outer cylinder 12 and the bottom.

The hydraulic shock absorber 10 has a piston valve device (extension-side damping force generator) 20 and a bottom valve device (compression-side damping force generator) 40, and a damper tube accompanying absorption of an impact force by a suspension spring. The elastic vibration of the piston rod 11 and the piston rod 14 is damped.

(Piston Valve Device 20) As shown in FIG. 2, the piston valve device 20 includes a valve stopper 21, a valve seat 22, a check valve 23, a piston 24, a disc valve 25, a valve seat 26, and a valve stopper. 27 are attached, and these are fixed with nuts 28. The piston 24 includes a piston side damper chamber 29A and a rod side damper chamber 29
B, and a push-side flow path 30A and a pull-side flow path 30B that connect the damper chambers 29A and 29B are formed. A check valve 23 is provided in the push-side flow path 30A, and a disc valve 25 is provided in the pull-side flow path 30B. It is provided.

When the hydraulic shock absorber 10 is compressed, the oil in the piston-side damper chamber 29A passes through the push-side flow path 30A to deflect and open the check valve 23, and is guided to the rod-side damper chamber 29B. At the time of extension, the rod-side damper chamber 2
9B passes through the pull-side flow path 30B and the disc valve 2
5 is deformed and opened, and the piston side damper chamber 29A is opened.
To generate an extension-side damping force.

(Bottom valve device 40) Hydraulic shock absorber 10
Has a reservoir chamber 41 between the outer cylinder 12 and the inner cylinder 13, and partitions the interior of the reservoir chamber 41 into an oil chamber and a gas chamber. The bottom valve device 40 is, as shown in FIG.
The piston-side damper chamber 29A and the reservoir chamber 41 are formed by the bottom piece 17 provided between the bottom of the second cylinder 2 and the lower end of the inner cylinder 13.
As shown in FIG. 4, a bolt 42 (nut 42A) is inserted into the bottom piece 17 and a spring 43, a check valve 44, the bottom piece 17, and a disc valve 45 are sandwiched between the bolt 42 and the nut 42A. At the same time, a pull-side flow path 46 and a push-side flow path 47 that connect the piston-side damper chamber 29A and the reservoir chamber 41 to the bottom piece 17 are formed. A disc valve 45 is provided in the passage 47.

When the hydraulic shock absorber 10 is compressed, oil corresponding to the volume of the piston rod 14 that enters the inner cylinder 13 flows from the piston-side damper chamber 29A to the push-side flow path 4 of the bottom piece 17.
7, the disk valve 45 is bent and opened, and is pushed out into the reservoir chamber 41 to generate a compression damping force.

When the hydraulic shock absorber 10 is extended, the oil corresponding to the withdrawal volume of the piston rod 14 withdrawing from the inner cylinder 13 pushes and opens the check valve 44 from the reservoir chamber 41 through the pull-side flow path 46 of the bottom piece 17. Is sucked into the piston side damper chamber 29A and supplied.

However, in the hydraulic shock absorber 10, as shown in FIGS. 4 and 5, the push-side flow path 47 provided in the bottom piece 17 is formed by a plurality of round holes 47A.
6 is also formed by a plurality of round holes 46A. The pull-side flow path 46 is opened at a plurality of positions between the inner and outer annular valve seats 48A and 48B for the check valve 44 provided on the upper surface of the bottom piece 17 (FIG. 5B). Opening is made at a plurality of positions between the inner and outer annular valve seats 49A and 49B for the disc valve 45 provided on the lower surface of the bottom piece 17 (FIG. 5C). Note that the distance from the center of the bottom piece 17 to the push-side flow path 47 is equal to the distance of the bottom piece 1.
7 is set to be smaller than the distance from the center to the pull-side flow path 46, and the pressure-side damping force based on the bending deformation of the disc valve 45 is set to be large.

Here, the bottom piece 17 is a compact formed by filling the mold with a sintered powder and molding the same, and has a plurality (for example, 4 pieces) for sitting on the bottom of the outer cylinder 12.
And a plurality of (for example, three) circular holes 46 </ b> A between the adjacent leg portions 51 in the circumferential direction. A road 46 is provided.

Therefore, in the mold for forming the bottom piece 17, the round holes 4 of the pull-side flow path 46 and the push-side flow path 47 are formed.
6A and 47A are each formed by a round pin having an appropriate outer diameter.

The bottom piece 17 has an annular stepped portion 52 into which the lower end of the inner cylinder 13 is press-fitted, on the outer peripheral side of the upper surface, and protrudes toward the outer cylinder 12 to connect the inner cylinder 13 to the outer cylinder 1.
Centering projection 5 for centering with respect to 2
3 are formed at a plurality of positions (for example, four positions) on the outer periphery in the circumferential direction. The centering projection 53 is preferably formed on the outer periphery between the plurality of legs 51 of the bottom piece 17.

According to this embodiment, the following operations are provided. The pull-side flow path 46 provided in the bottom piece 17 is
Since it is set to A, a portion for forming the pull-side flow path 46 in a mold for forming the bottom piece 17 from a sintered metal or the like can be formed by a round pin. Round pins are easy to process and general-purpose pins are also available, making it easy to create molds, easy to repair and replace when damaged, shortening maintenance time, and improving hydraulic shock absorber production line efficiency. Can be improved.

The above-mentioned round hole 46A is provided in the bottom piece 17
Since the leg 51 is cut off, the leg 51 is shaved and the stability of the seating of the bottom piece 17 is impaired.
The hole diameter of the round hole 46A must be made as small as possible. In the present invention, since the round hole 46A is provided between the leg 51 and the leg 51, it is possible to stabilize the large size without shaving the leg 51 and to make the hole diameter of the round hole 46A large so that the pull-side flow path 4
6, a large flow path area can be secured, and a pull-side flow path 46 with good suction performance can be formed. In addition, the round pin can be enlarged, and the durability of the mold can be improved.

Since the centering projection 53 is formed on the outer periphery of the bottom piece 17, the centering property of the inner cylinder with respect to the outer cylinder can be secured while eliminating the centering member separate from the bottom piece 17, and the number of parts of the hydraulic shock absorber is reduced. And the number of assembling steps are reduced, and the productivity of the hydraulic shock absorber can be improved.

Since the centering projection 53 is formed on the outer periphery of the thin portion between the leg portions 51 of the bottom piece 17, the centering projection 53 is formed on the outer periphery of the thick leg portion 51 as compared with the case where the centering projection 53 is formed on the outer periphery of the thick leg portion 51. It is possible to improve the filling property of a material such as a sintered powder into the projection, and to improve the molding quality of the centering projection 53.

In the bottom piece 17, since all the flow paths of the pull-side flow path 46 and the push-side flow path 47 are formed by the round holes 46A and 47A, a mold for forming the bottom piece 17 can be formed extremely easily.

The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration of the present invention is not limited to this embodiment, and the design can be changed without departing from the scope of the present invention. The present invention is also included in the present invention.

[0035]

As described above, according to the present invention, it is possible to secure a large flow passage area in the pull-side flow passage while easily making a mold for the bottom piece. Further, according to the present invention, the centering member, which is a member separate from the bottom piece, can be eliminated.

[Brief description of the drawings]

FIG. 1 is a half sectional view showing a hydraulic shock absorber.

FIG. 2 is an enlarged sectional view showing a piston valve device.

FIG. 3 is an enlarged sectional view showing a bottom valve device.

FIG. 4 is a sectional view showing a bottom piece assembly.

FIG. 5 shows a bottom piece, (A) is a sectional view,
(B) is a plan view, and (C) is a bottom view.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Hydraulic shock absorber 12 Outer cylinder 13 Inner cylinder 17 Bottom piece 29A, 29B Damper room 41 Reservoir room 46 Pulling side channel 46A Round hole 51 Leg 53 Centering projection

Claims (3)

[Claims] 1. A bottom structure of a hydraulic shock absorber in which an inner cylinder is erected in an outer cylinder and a lower end of the inner cylinder is supported on a bottom of the outer cylinder via a bottom piece. A hydraulic system characterized in that a pull-side flow path connecting the reservoir chamber to a damper chamber inside the inner cylinder is formed by a plurality of round holes provided between a plurality of legs protruding from the bottom surface of the bottom piece. Bottom structure of shock absorber. 2. The bottom structure of a hydraulic shock absorber according to claim 1, wherein centering projections are formed at a plurality of circumferential positions on an outer periphery of the bottom piece. 3. The bottom structure of a hydraulic shock absorber according to claim 2, wherein the centering projection is formed on an outer periphery between a plurality of legs of the bottom piece.