JPH08177926A - Shock absorber for vehicle - Google Patents

Abstract

PURPOSE: To simplify the structure and lighten the weight of a shock absorber for vehicles by regulating the position of a piston so that the position of a top dead center may always be in a fluid layer when the piston reaches the top dead center. CONSTITUTION: A piston 16 can be raised up to the top dead center where one end of a pipe shape member 30 abuts on the top surface of a casing 12. The piston 16 that has reached the top dead center is positioned in a fluid layer 18 and from this position it starts descending and goes into a contraction stroke. Thus the piston 16 can make a reciprocating motion in the vertical direction inside the fluid layer 18 and can infallibly prevent gas in the gas layer 20 from being dragged into the fluid layer 18 by the piston 16. For this reason, the function of a shock absorber can be stably performed. A partitioning member partitioning the gas layer 20 and the fluid layer 18 can be omitted and the casing 12 can be made of lighter weight materials such as an aluminum alloy. Thus the weight of shock absorber 10 can be lightened and treatment such as metal plating of the outer wall surface of the casing 12 can be dispensed with.

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 specifically, a liquid layer of oil or the like and a gas layer of nitrogen gas or the like are enclosed in a casing mounted vertically on the wheel side of the vehicle. The present invention relates to a shock absorber for a vehicle, in which a piston having one end attached to the other end of a rod attached to the vehicle body is reciprocally inserted in the casing in the vertical direction.

[0002]

2. Description of the Related Art As a shock absorber provided in a vehicle, for example, a monotube type shock absorber 100 shown in FIG. 2 is used. In this shock absorber 100, a liquid casing 112 of oil or the like and a gas layer 114 of nitrogen gas or the like are enclosed in a tubular casing 110 mounted vertically on the wheel side of the vehicle, and both layers are enclosed in the casing 110. It is partitioned by a piston 116 that is inserted so as to be movable in the up and down direction. A seal member 118 such as an O-ring is attached to the piston 116 to complete the seal between the liquid layer 112 and the gas layer 114. Further, in the liquid layer 112, one end of the rod 12 is attached to the vehicle body side.
A piston 122 attached to the other end portion of 0 is inserted movably in the vertical direction along the casing 110.

The piston 122 has channels 124, 1
26 is provided, a valve 128 is provided at the lower opening of the flow path 124, and a valve 130 is provided at the upper opening of the flow path 126. These valves 128, 1
In the so-called contraction process, in which the piston 122 descends toward the piston 116, the valve 128 is closed and the valve 130 is opened, and the liquid passes through the flow path 126 and the piston 1
Move to the upper part of 22. Therefore, the piston 122
Can descend. On the other hand, the piston 122 is the piston 116
In a so-called extension process in which the liquid 130 rises in the direction away from
4 and moves to the lower part of the piston 122. Therefore, the piston 122 can move up.

The shock absorber 1 shown in FIG.
00, the piston 12 in the contraction process of the piston 122
Since the pressing force of 2 can be absorbed by the gas layer 114,
A monotube type that is lightweight and easy to cool can be used.
However, when the gas in the gas layer 114 leaks into the liquid layer 112, the function of the shock absorber is significantly deteriorated, so that the piston 1 for partitioning the liquid layer 112 and the gas layer 114 is separated.
The sealability requirements of 16 are very strict. For this reason,
Since the shock absorber 100 has a large number of parts and a complicated mechanism, a failure is likely to occur.

A shock absorber 200 shown in FIG. 3 is also used, in which the piston 116 for partitioning the liquid layer 112 and the gas layer 114 provided in the shock absorber 100 shown in FIG. 2 is removed. The shock absorber 200 of FIG. 3 is enclosed in a tubular casing 210 mounted upright on the vehicle body side with a gas layer 212 and a liquid layer 210 in contact with each other at their interfaces. A piston 218 attached to the other end of a rod 216 whose part is attached to the wheel side of the vehicle is inserted along the casing 214 so as to be movable in the vertical direction. Like the piston 122 of the shock absorber 100 shown in FIG. 2, the piston 218 is provided with valves 224 and 226 at one of the openings of the channels 220 and 222 formed as liquid channels. There is. Further, the shock absorber 200 shown in FIG. 3 has a cylindrical body 22 to protect the rod 216, which is constantly vibrated by the wheels.
8 is fixed to the wheel side of the vehicle. The cylindrical body 228 is provided with a sliding contact portion that is in sliding contact with the outer wall surface of the casing 210, and the casing 210 moves up and down while slidingly contacting the sliding contact portion of the cylindrical body 228. It should be noted that dust and the like from the wheels may cause the cylindrical body 22.
A seal member 230 is provided in the cylindrical body 228 in order to prevent it from adhering to the sliding contact surface of No. 8.

[0006]

The shock absorber 200 shown in FIG. 3 does not require a partition member such as a piston for partitioning the gas layer 212 and the liquid layer 214, so that the shock absorber 100 shown in FIG. The structure can be simplified and the number of parts can be reduced. However, the shock absorber 200
Since the outer wall surface of the casing 210 is in sliding contact with the sliding contact portion of the cylindrical body 228, the outer wall surface of the casing 210 needs to be plated, and the casing 210 cannot be formed of a lightweight aluminum alloy or the like. , I have no choice but to form with iron material. Further, in order to protect the rod 216, the cylindrical body 22
Since 8 is fixed to the wheel side, it is difficult to reduce the unsprung weight of the vehicle. Also, the rod 216 is
Although it is protected by 8, the vibration from the wheel is always concentrated in the vicinity of the connecting portion between the rod 216 and the piston 218, so there is a problem in strength. Therefore, the present invention is
An object of the present invention is to provide a shock absorber for a vehicle, which has a simple structure and can be reduced in weight.

[0007]

Means for Solving the Problems The present inventor has studied to achieve the above-mentioned object. As a result, the shock absorber 200 shown in FIG. As shown, it has been found that using the casing 210 in an upright state is effective from the viewpoint of simplifying the structure and reducing the weight of the shock absorber. In other words, since the cylindrical body 228 can be eliminated, the plating process applied to the outer wall surface of the casing 210 'can be eliminated, the casing 210' can be formed of a lightweight aluminum alloy, etc., and the vibration from the wheel side can be generated by the casing 210 '. This is because it can be received and the strength problem in the vicinity of the connecting portion between the rod 216 and the piston 218 can be solved.

However, in the shock absorber using the casing 210 'in the upright state, the liquid layer 21
Since the gas layer 212 is formed on the piston 4, the piston 2 provided at the other end of the rod 216 as shown in FIG.
When 18 reaches the top dead center in the stretching process, the gas layer 212
A piston 218 may be located therein. Like this
When the piston 218 located in the gas layer 212 re-enters the liquid layer 214 in the contraction step, as shown in FIG. 4B, the gas is entrained in the liquid layer 214 and a large number of bubbles 240, 240 ... To form. The bubbles 240, 240, ... Formed in the liquid layer 214 are easily reduced in volume by liquid pressure, so that the liquid layer 214 and the piston 2 are
The damping property with 18 is significantly impaired, and the function of the shock absorber is significantly reduced. Therefore, the shock absorber having a possibility that bubbles 240, 240, ... Are formed in the liquid motion 214 has poor reliability and cannot be used at all for vehicles.

In view of this point, the present inventor has conducted further studies and found that when the piston 218 reaches the top dead center in the extension process, the position of the top dead center is always present in the liquid layer 214. In addition, the inventors have found that by regulating the position of the piston 218, it is possible to prevent the gas in the gas layer 212 from being caught in the liquid layer 214 as the piston 218 descends.

That is, according to the present invention, a liquid layer of oil or the like and a gas layer of nitrogen gas or the like are enclosed in a casing mounted vertically on the wheel side of a vehicle, and one end of the casing is mounted on the vehicle body side. In a shock absorber for a vehicle in which a piston attached to the other end of the rod is inserted into the casing so that the piston can reciprocate in the vertical direction, in a passage of the piston that reciprocates in the casing,
The liquid layer and the gas layer are sealed with the interface in contact with each other, and when the piston reaches the top dead center, a positioning member that comes into contact with a predetermined position in the casing is provided so that the piston exists in the liquid layer. A shock absorber for a vehicle, wherein the shock absorber is provided on a rod extending from a piston. In the present invention having such a configuration, a pipe-shaped member is used as the positioning member, and the rod is inserted through the pipe-shaped member, whereby the top dead center position of the piston can be easily regulated. Also, by making the shock absorber a monotube type,
The liquid layer and the like can be easily cooled.

[0011]

According to the present invention, the piston provided at the lower end of the rod attached to the vehicle body reciprocates in the vertical direction in the casing attached to the wheel side of the vehicle in an upright state. It is not necessary to protect the rod by slidingly contacting the outer wall surface of the casing with the sliding contact portion of the cylindrical body fixed to the wheel side of the vehicle, and the casing can be formed of a lightweight material such as aluminum alloy. Further, it is possible to reduce the number of parts of the shock absorber in combination with eliminating the need for a partition member such as a piston that separates the liquid layer and the gas layer enclosed in the casing, and to reduce the weight of the shock absorber. it can. Moreover, when the piston reaches the top dead center, the rod is provided with a positioning member that comes into contact with a predetermined position in the casing so that the piston exists in the liquid layer. As a result, it is possible to reliably prevent the function of the shock absorber from being deteriorated due to the gas in the gas layer being entrained in the liquid layer by the piston.

[0012]

The present invention will be described in more detail with reference to the drawings.
FIG. 1 shows an example of a vehicle shock absorber according to the present invention.
Shown in The shock absorber 10 shown in FIG. 1 has a piston 16 that is screwed to the other end of a rod 14 that is attached to the vehicle body side in a tubular casing 12 that is attached to the vehicle wheel side in an upright state. Is reciprocally inserted in the vertical direction. This casing 12
In the passage through which the piston 16 passes, a gas layer 20 of nitrogen gas or the like is enclosed in contact with an interface of a liquid layer 18 of oil or the like. Further, the piston 16 is provided with flow paths 22 and 24 through which the liquid of the liquid layer 18 passes, and the flow path 2
A valve 26 is provided in the vicinity of the lower opening of the second passage 2, and a valve 28 is provided in the vicinity of the upper opening of the flow path 24.

In the present embodiment, the position of the piston 16 is regulated so that its top dead center and bottom dead center are in the liquid layer 18. Particularly, the top dead center of the piston 16 is the gas layer 2
The positioning member of the piston 16 is attached to the rod 14 in the casing 12 so that the piston 16 does not come to zero.
The top dead center is regulated to be in the liquid layer 18. In this embodiment, the pipe-shaped member 30 is used as the positioning member.
, The rod 14 extending from the piston 16 is inserted into the pipe-shaped member 30. Such a pipe-shaped member 30
Is inserted into the rod 14 so that one end contacts the upper surface of the piston 16, and when the piston 16 moves upward and the other end of the pipe-shaped member 30 contacts the inner wall surface of the casing 12, the piston 16 Top dead center is determined. Therefore, by adjusting the length of the pipe-shaped member 30,
The piston 16 that has reached the top dead center can be reliably present in the liquid layer 18.

On the other hand, the bottom dead center of the piston 16 is always inside the liquid layer 18 because the liquid layer 18 is enclosed below the gas layer 20 in the casing 12. However, piston 1
Since the position of the top dead center of No. 6 is regulated by the pipe-shaped member 30, the lengths of the casing 12 and the liquid layer 18 are adjusted in advance so that the maximum stroke length of the piston 16 can be sufficiently secured.

In the shock absorber 10 shown in FIG. 1, in the so-called contraction step in which the piston 16 descends toward the bottom surface of the casing 12, the flow path 22 of the piston 16 is reduced.
The valve 26 provided near the lower opening of the
The valve 28 provided in the vicinity of the opening of the upper opening of the valve opens. Therefore, the liquid in the lower chamber of the piston 16 flows into the upper chamber via the flow path 24, and the piston 16 descends. In the so-called extension step in which the piston 16 moves in the gas layer 20 direction after the piston 16 descending in this way reaches the bottom dead center, a valve provided near the upper opening of the flow path 24 of the piston 16 28 is closed, and the valve 28 provided near the lower opening of the flow path 22 is opened. Therefore, the liquid in the upper chamber of the piston 16 flows into the lower chamber via the flow path 22, and the piston 16 rises.

When the piston 16 is lifted, the pipe-shaped member 30
The other end of can reach the top dead center where it abuts on the upper surface of the casing 12. When the piston 16 reaches the top dead center, it is positioned in the liquid layer 18, and starts descending again from this position to shift to the contracting step. As described above, in the shock absorber 10 of the present embodiment, the piston 16 can reciprocate in the vertical direction in the liquid layer 18, so that the gas in the gas layer 20 is surely drawn into the liquid layer 18 by the piston 16. It can be prevented. Therefore, the function of the shock absorber can be stably exhibited, and the shock absorber 10 can be sufficiently used for vehicles such as passenger cars. Furthermore,
Since the partition member for partitioning the gas layer 20 and the liquid layer 18 can be omitted, and the casing 12 can be made of a lightweight material such as an aluminum alloy, the weight of the shock absorber 10 can be reduced. Further, since the outer wall surface of the casing 12 does not need to be plated, the shock absorber manufacturing process can be simplified.

The shock absorber 1 described above
In No. 0, the pipe-shaped member 30 is used as the positioning member for the piston 16, but a protrusion or an annular protrusion may be formed at a predetermined position of the rod 14. Also, casing 1
A coating process may be applied to the outer wall surface of 2 to prevent corrosion, and an elastic member 34 such as a spring may be mounted between the casing 12 and the vehicle body mounting portion 32 of the rod 14. .

[0018]

According to the present invention, the weight of the shock absorber can be reduced, and the unsprung weight of the vehicle can be reduced. Therefore, the riding comfort of the vehicle can be expected to be improved. Furthermore, since the manufacturing process of the shock absorber can be simplified, cost reduction of the shock absorber can be expected.

[Brief description of drawings]

FIG. 1 is a sectional view according to an embodiment of the present invention.

FIG. 2 is a sectional view for explaining a conventional shock absorber.

FIG. 3 is a cross-sectional view for explaining another conventional shock absorber.

FIG. 4 is an explanatory diagram for explaining a problem when the top dead center of the piston constituting the shock absorber is located in the gas layer.

[Explanation of symbols]

 10 Shock Absorber 12 Casing 14 Rod 16 Piston 18 Liquid Layer 20 Gas Layer 22, 24 Flow Path 26, 28 Valve 30 Pipe-shaped Member (Positioning Member)

Claims (3)

[Claims] 1. A rod that has a liquid layer such as oil and a gas layer such as nitrogen gas enclosed in a casing that is vertically installed on the wheel side of a vehicle and has one end attached to the vehicle body side. In a shock absorber for a vehicle, in which a piston attached to an end is reciprocally inserted in the casing in a vertical direction, a liquid layer and a gas layer are formed in a passage of the piston that reciprocates in the casing. A rod extending from the piston is provided with a positioning member that contacts the interface and is in contact with a predetermined position in the casing so that the piston exists in the liquid layer when the piston reaches the top dead center. A shock absorber for vehicles characterized by 2. The positioning member is a pipe-shaped member,
The shock absorber for a vehicle according to claim 1, wherein a rod is inserted through the pipe-shaped member. 3. The shock absorber for a vehicle according to claim 1, wherein the shock absorber is a monotube type.