JP2024063553A - Vehicle shock absorbers - Google Patents

Abstract

[Problem] To prevent foreign matter from entering a shock absorber. [Solution] A shock absorber 10 includes a casing 11 with a working fluid 17 sealed inside the cylinder, a rod 12 having a piston 12A slidably housed in the casing 11 and extending from one end of the casing 11 at its tip, a seal 13 for sealing the working fluid 17 between the rod 12 and the casing 11, a cylindrical cover 14 attached to the tip of the rod 12, extending from the tip in the direction in which the rod 12 extends, and covering a part of the casing 11 and the rod 12 from the outside, and an annular ring 20 having a mesh portion disposed in the space between the casing 11 and the cover 12, fixed to one of the outer peripheral surface of the casing 11 and the inner peripheral surface of the cover 12 and slidably disposed relative to the other. [Selected Figure] Figure 1

Description

This case concerns shock absorbers for vehicles such as trucks.

2. Description of the Related Art Conventionally, in suspension devices mounted on vehicles such as trucks, shock absorbers are used to absorb vibrations input from the road surface.
This shock absorber has a casing with a cylinder filled with oil and a rod that slides inside the cylinder. The rod slides inside the cylinder, and the structure uses the oil flow resistance to dampen vibrations.

In such shock absorbers, it is known to provide a sealing member between the casing and the rod to prevent foreign matter from entering the casing (for example, Patent Document 1), or to provide an outer cover on the outside of the casing to prevent foreign matter from entering from the outside (for example, Patent Document 2).
The outer cover as disclosed in Patent Document 2 is attached to the outer circumferential surface of the casing with a gap so that it can move relative to the casing together with the rod in response to the expansion and contraction of the shock absorber. Note that shock absorbers mounted on vehicles such as trucks and dump trucks are often provided with outer covers in consideration of driving on rough roads.

Utility Model Registration No. 3157500 JP 2016-133191 A

As described above, the outer cover is attached to the outer circumferential surface of the casing with a gap therebetween. Therefore, when negative pressure is generated between the casing and the outer cover due to the expansion and contraction of the shock absorber, there is a risk that foreign matter may enter the inside of the outer cover from the outside through the gap. If foreign matter enters the inside of the outer cover, for example, the foreign matter may damage the sealing member, leading to an oil leak. Therefore, there is room for improvement in preventing foreign matter from entering the inside of a vehicle shock absorber.
The present invention has been devised in view of the above-mentioned problems, and one of its objects is to prevent foreign matter from entering the interior of a vehicle shock absorber.

The present invention has been made to solve at least part of the above problems, and can be realized as the following aspects or application examples.
The vehicle shock absorber according to the application example includes a cylindrical casing portion having a working fluid sealed inside a cylinder, a rod portion formed of a rod-shaped member having a piston slidably stored within the casing portion, the rod portion having a tip side opposite to the piston extending from one end of the casing portion, a seal portion provided on the one end of the casing portion for sealing the working fluid between the rod portion and the casing portion, a cover portion attached to the tip side of the rod portion and formed of a hollow cylindrical member extending from the tip side in the extending direction of the rod portion, the cover portion for covering the casing portion and a part of the rod portion from the outside, and a ring portion formed of an annular member having a mesh portion disposed in a space formed between an outer circumferential surface of the casing portion and an inner circumferential surface of the cover portion, the ring portion being fixed to one of the outer circumferential surface of the casing portion and the inner circumferential surface of the cover portion and being slidably provided relative to the other of the outer circumferential surface of the casing portion and the inner circumferential surface of the cover portion.

In the vehicle shock absorber according to the application example, the ring portion is fixed to one of the outer peripheral surface of the casing portion and the inner peripheral surface of the cover portion and is provided slidably relative to the other of the outer peripheral surface of the casing portion and the inner peripheral surface of the cover portion. Therefore, even if negative pressure is generated between the casing portion and the cover portion due to the expansion and contraction of the shock absorber, the ring portion prevents foreign matter from entering the cover portion.
Therefore, it is possible to effectively prevent foreign matter from entering the inside of the shock absorber.

The vehicle shock absorber according to the application example can prevent foreign objects from entering the interior.

1 is a cross-sectional view of a shock absorber for a vehicle according to an application example. FIG. 2 is an explanatory view of the ring portion of FIG. 1 as viewed along the axis. 3 is a cross-sectional view of the ring portion of FIG. 2 taken along line AA.

The following describes the platform height adjustment device according to the application examples of the present invention with reference to the drawings. The following application examples are merely illustrative, and are not intended to exclude the application of various modifications or techniques not explicitly stated in these application examples. The configurations of the following application examples can be modified in various ways without departing from the spirit of the application examples. The configurations of the following application examples can be selected as necessary, or can be appropriately combined with various configurations included in publicly known technology.

[1. Configuration]
FIG. 1 is a cross-sectional view of a shock absorber for a vehicle according to the present embodiment.
A vehicle shock absorber (hereinafter, also referred to as a "shock absorber") 10 is used in a suspension device mounted on a vehicle (not shown) such as a truck, and is a device for attenuating vibrations input from the road surface to the vehicle. The shock absorber 10 is interposed, for example, between the frame (not shown) and the axle (not shown) of the vehicle.

Specifically, the shock absorber 10 shown in FIG. 1 has one axial end (left end in the figure) attached to a frame (not shown) via a bush 5L, and the other axial end (right end in the figure) attached to an axle (not shown) via a bush 5R. The other end of the shock absorber 10 moves relative to one end (the vehicle frame side) of the shock absorber 10, causing the entire shock absorber 10 to expand and contract, thereby damping vibrations using the flow resistance of oil, which will be described later. The open double arrows in the figure indicate the direction in which the shock absorber 10 expands and contracts. The direction in which the shock absorber 10 expands and contracts is a straight line along the axis of the shock absorber 10.

The shock absorber 10 in FIG. 1 includes a casing portion 11, a rod portion 12, a seal portion 13, and an outer cover (cover portion) 14.
The casing 11 is the main body of the shock absorber 10 and is formed of a cylindrical member (cylinder). Figure 1 shows an example of a twin-tube shock absorber 10 in which the casing 11 is formed of a double-structure cylinder consisting of an inner tube 11A and an outer tube 11B. Oil 17 used as the working fluid of the shock absorber 10 is sealed inside the inner tube 11A and the outer tube 11B, and a reservoir chamber 18 in which gas or air is sealed is also provided.

The inner tube 11A and the outer tube 11B are arranged coaxially along the axis of the shock absorber 10, with the inner tube 11A housed inside the outer tube 11B and the outer tube 11B being arranged outside the inner tube 11A.
A first cap 11C that slidably supports the rod portion 12 is provided on each of the left ends (one end of the casing portion 11) of the inner cylinder 11A and the outer cylinder 11B.
A base valve 15 is provided at the right end of the inner cylinder 11A (the other end of the casing part 11). Oil 17 can move between the inner cylinder 11A and the outer cylinder 11B through the base valve 15. A second cap 16 is provided at the right end of the outer cylinder 11B. A bush 5R is fixed to the second cap 16.

The rod portion 12 is formed of a rod-shaped member having a piston 12A slidably housed in an inner cylinder 11A (casing portion 11). The rod portion 12 is slidably supported relative to the casing portion 11 via a first cap 11C.
The tip side (left side in the figure) of the rod portion 12 located opposite the piston 12A extends from one end (left end in the figure) of the casing portion 11.
A piston valve (not shown) is provided in the piston 12A. Oil 17 can move between one side and the other side of the piston 12A in the axial direction through the piston valve.

The rod portion 12 is provided so as to be capable of reciprocating relative to the casing portion 11 along the axis of the shock absorber 10 .
When the rod portion 12 moves to the left in the figure relative to the casing portion 11, the shock absorber 10 expands. When the rod portion 12 moves to the right in the figure relative to the casing portion 11, the shock absorber 10 contracts.
As the shock absorber 10 expands and contracts, the oil 17 passes through the piston valve and base valve 15, which creates a damping force. That is, when the shock absorber 10 expands, the oil 17 in the chamber on the left side of the piston 12A is pressed by the piston 12A and tries to move to the chamber on the right side of the piston 12A, and as the oil passes through a piston valve (not shown), it creates a flow resistance, which creates a damping force. When the shock absorber 10 contracts, the oil 17 in the chamber on the right side of the piston 12A is pressed by the piston 12A and tries to move to the chamber between the inner cylinder 11A and the outer cylinder 11B, and as the oil passes through the base valve 15, it creates a flow resistance, which creates a damping force.

A seal portion 13 is provided at one end (the left end in the figure) of the casing portion 11 .
The seal portion 13 is a sealing member for sealing the oil 17 between the casing portion 11 and the rod portion 12. Specifically, the seal portion 13 includes an annular seal member 13A made of an elastic body and a housing 13B that covers the seal member 13A. The seal member 13A is fixed to the housing 13B on its outer periphery side and is provided so that its inner periphery side contacts the outer periphery surface of the rod portion 12, thereby preventing oil leakage from the gap between the first cap 11C (casing portion 11) and the rod portion 12.

An outer cover 14 is attached to the tip (left end in the figure) of the rod portion 12 .
The outer cover 14 is provided to protect the outer periphery of the rod portion 12 and to prevent foreign matter from entering the vicinity of the seal portion 13 .
1, the outer cover 14 is formed of a hollow cylindrical member with one end (the left end in the figure) closed and the other end (the right end in the figure) open. The outer cover 14 is disposed coaxially with the casing portion 11 and the rod portion 12, with the outer cover 14 extending from the tip side of the rod portion 12 in the direction in which the rod portion 12 extends (to the right in the figure).

The outer cover 14 is positioned so as to overlap a portion of the casing 11 and the rod 12 (a portion on the left side in the figure), and covers the casing 11 and a portion of the rod 12 from the outside. Therefore, the portion of the rod 12 that extends from the casing 11 and the seal 13 provided at the left end (one end) of the casing 11 are housed inside the outer cover 14 and are protected by the outer cover 14.

The outer cover 14 is provided integrally with the rod portion 12 so as to be capable of reciprocating relative to the casing portion 11 in order to enable the shock absorber 10 to expand and contract. Therefore, the inner diameter of the outer cover 14 is set to be larger than the outer diameter of the casing portion 11. As a result, a space 14A is formed between the inner peripheral surface of the outer cover 14 and the outer peripheral surface of the casing portion 11.
The dimension of the outer cover 14 in the direction along the axis may be set to an appropriate dimension based on the reciprocating range W of the outer cover 14 so that the shock absorber 10 can exhibit a predetermined protective performance even when it expands and contracts.

A ring portion 20 is provided between the outer peripheral surface of the outer cylinder 11B (casing portion 11) and the inner peripheral surface of the outer cover 14.
The ring portion 20 is an annular member made of an elastic body that is attached by press-fitting (insertion) onto the outer peripheral surface of the outer cylinder 11B, and is provided to prevent foreign matter from entering the inside of the outer cover 14 from the space 14A. Examples of foreign matter include sand grains, stone grains, and other dust particles.

The ring portion 20 is attached at a position where the casing portion 11 and the outer cover 14 overlap.
The attachment position of the ring portion 20 relative to the casing portion 11 is set within the reciprocating range W of the outer cover 14 so that a predetermined anti-entrapment performance can be exhibited even when the shock absorber 10 expands and contracts. From the viewpoint of preventing foreign matter from entering the outer cover 14, it is preferable that the attachment position of the ring portion 20 relative to the casing portion 11 be set within the reciprocating range W and on the opening side of the outer cover 14 (the right side in FIG. 1 ).

Fig. 2 is a view of the ring portion 20 in Fig. 1 as viewed in a direction along the axis of the shock absorber 10. Fig. 3 is a cross-sectional view of the ring portion 20 as viewed from the line AA in Fig. 2.
As shown in Figures 1 to 3, the ring portion 20 is fixed to the outer peripheral surface of the casing portion 11 at its inner peripheral edge portion 20A, and is arranged so as to be in slidable contact with the inner peripheral surface of the outer cover 14 at its outer peripheral edge portion 20B.

As shown in FIG. 2, the ring portion 20 has a mesh portion 20C between the inner peripheral edge portion 20A and the outer peripheral edge portion 20B. The mesh portion 20C is disposed in the space 14A and is a mesh-like portion that allows air to flow while preventing the flow of foreign matter. Specifically, the mesh portion 20C extends on a surface along the radial direction from the base portion 20D on the inner peripheral side toward the outer peripheral edge portion 20B.

The mesh size (openings) of the mesh portion 20C is set to a size that allows air to pass through while preventing the passage of foreign matter.
3, the base portion 20D protrudes in a flange-like shape relative to the other portions other than the base portion 20D and is formed to be thicker than the other portions. Since the base portion 20D is thick, the strength is ensured such that the ring portion 20 can be press-fitted onto the outer peripheral surface of the casing portion 11.

[2. Actions and Effects]
In the shock absorber 10 according to the above application example, the ring portion 20 is attached to the outer circumferential surface of the casing portion 11. Therefore, even if negative pressure is generated between the casing portion 11 and the outer cover 14 due to the expansion and contraction of the shock absorber 10, the portion of the ring portion 20 disposed within the space 14A is formed by the mesh portion 20C, allowing good air circulation, and therefore negative pressure is unlikely to occur. Furthermore, even if negative pressure is generated, the ring portion 20 prevents foreign matter from entering the outer cover 14.
This effectively prevents foreign matter from entering the shock absorber 10. As a result, the rod portion 12 and the seal portion 13 inside the outer cover 14 are appropriately protected from foreign matter, thereby preventing oil leakage.

In the above application example, the ring portion 20 has the mesh portion 20C disposed within the space 14A, so that the ring portion 20 prevents foreign matter from entering while not impeding air circulation during the expansion and contraction of the shock absorber 10. Therefore, even in a structure in which the ring portion 20 is provided on the outer circumferential surface of the casing portion 11, the sliding resistance between the casing portion 11 and the outer cover 14 is unlikely to deteriorate.
In addition, in the above application example, since the ring portion 20 is formed as an elastic annular member, the fixing force of the ring portion 20 to the casing portion 11 is ensured by the elastic force of the ring portion 20. Therefore, no fixture or structure for fixing the ring portion 20 is required. Therefore, the mounting structure of the ring portion 20 is simple.

[3. Other]
In the above application example, the ring portion 20 has a structure in which the inner peripheral edge portion 20A is fixed to the outer peripheral surface of the casing portion 11 and the outer peripheral edge portion 20B slides against the inner peripheral surface of the outer cover 14. However, the ring portion may have a structure in which the outer peripheral edge portion is fixed to the inner peripheral surface of the outer cover 14 and the inner peripheral edge portion slides against the outer peripheral surface of the casing portion 11. In this case, the ring portion has a thick base portion on the outer peripheral side, and a mesh portion is provided from the base portion toward the inner peripheral side.
Further, in the above application example, the twin-tube shock absorber 10 has been taken as an example for explanation, but the present invention is not limited to this, and may be a single-tube shock absorber or a shock absorber provided with a spring inside.

REFERENCE SIGNS LIST 10 Shock absorber 11 Casing portion 11A Inner cylinder 11B Outer cylinder 11C First cap 12 Rod portion 12A Piston 13 Seal portion 13A Seal member 13B Housing 14 Outer cover 14A Space 15 Base valve 16 Second cap 17 Oil 18 Reservoir chamber 20 Ring portion 20A Inner peripheral edge portion 20B Outer peripheral edge portion 20C Mesh portion 20D Base portion 5L, 5R Bushing

Claims (1)

A cylindrical casing portion having a working fluid sealed inside a cylinder;
a rod portion formed of a rod-shaped member having a piston slidably housed within the casing portion, the rod portion having a tip end side opposite to the piston extending from one end of the casing portion;
a seal portion provided at the one end of the casing portion for sealing the working fluid between the rod portion and the casing portion;
a cover portion that is attached to the tip side of the rod portion and is formed of a hollow cylindrical member extending from the tip side in the extending direction of the rod portion, and that covers the casing portion and a part of the rod portion from the outside;
a ring portion formed of an annular member having a mesh portion arranged in a space formed between the outer peripheral surface of the casing portion and the inner peripheral surface of the cover portion, the ring portion being fixed to one of the outer peripheral surface of the casing portion and the inner peripheral surface of the cover portion and being slidably disposed relative to the other of the outer peripheral surface of the casing portion and the inner peripheral surface of the cover portion.

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