JP2006177531A - Hydraulic draft gear - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively reduce the shock and noise at the rebounding, and to improve the durability in a hydraulic draft gear. <P>SOLUTION: A piston 3 to connect a piston rod 4 is slidably fitted in a cylinder 2 sealed by oil liquid to generate the damping force by damping force generating mechanisms 13, 14 at elongation side and contradiction side. A fixed spring retainer 15 is fixed to the piston 4, a movable spring retainer 22 is slidably guided, and a rebound spring 26 is installed between these. A plunger 19 having an orifice 21 is installed in the fixed spring retainer 15, and a cylinder part 24 is formed in the movable spring retainer 22. When the piston rod 4 extends near the stroke end, the plunger 19 is inserted in the cylinder part 24, oil liquid is discharged through the orifice 21 from an oil chamber formed inside these to generate the fluid force and reduce the shock and noise at the rebounding. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hydraulic shock absorber that can be used in a suspension device of a vehicle such as an automobile.

For example, in a hydraulic shock absorber mounted on a suspension device of an automobile vehicle, as described in Patent Document 1, a rebound spring is connected to a piston rod connected to a piston slidably fitted in a cylinder. (Compression coil spring) is wound, and when the piston rod is extended to the vicinity of its maximum extension position, the rebound spring is compressed and a spring force is applied to the extension of the piston rod, so that the piston rod is moved to the stroke end. There are some which make it difficult to reach and reduce the impact at the stroke end.
JP-A-6-101734

  In the hydraulic shock absorber with the above rebound spring, when the piston rod extends and reaches the stroke end, the rebound spring is compressed to the maximum contracted state, causing close noise between the lines, generating abnormal noise, There is a risk of damage. Therefore, a rebound stopper is attached to the piston rod, and this is collided with the inside of the cylinder, thereby restricting the extension position of the piston rod and preventing the rebound spring from being in close contact with each other.

  However, the conventional rebound stopper has a problem in that it generates an impact and noise when the rebound stopper collides with the inside of the cylinder. The shock and noise can be reduced by attaching a shock absorber made of elastic material such as rubber or synthetic resin to the rebound stopper. However, if the amount of deformation of the shock absorber is increased in order to increase the shock absorbing effect, the durability will be improved. This causes the problem of lowering.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a hydraulic shock absorber that can effectively reduce impact and noise during rebounding and has excellent durability. To do.

In order to solve the above-mentioned problems, the invention according to claim 1 is directed to a cylinder in which oil is sealed, a piston slidably fitted in the cylinder, one end connected to the piston, and the like. A piston rod whose end side extends to the outside of the cylinder, a damping force generation mechanism that generates a damping force by controlling the flow of oil and liquid caused by sliding of the piston in the cylinder, and extension of the piston rod In the hydraulic shock absorber equipped with a rebound stopper mechanism for limiting
The rebound stopper mechanism includes a fixed spring receiver fixed to the piston rod inside the cylinder and a movable spring receiver slidably provided on the piston rod and capable of contacting a stopper fixed in the cylinder. And spring means interposed between the fixed spring receiver and the movable spring receiver, and the fixed spring receiver and the movable spring receiver are engaged with each other in the vicinity of the stroke end on the extension side of the piston rod. One of a cylinder part and a plunger forming an oil chamber is provided, and at least one of the cylinder part and the plunger is provided with an orifice for communicating the oil chamber with the outside.

  According to the hydraulic shock absorber of the first aspect of the present invention, when the piston lot is extended and the movable spring receiver comes into contact with the stopper, the spring means is compressed and a spring force is applied to the extension of the piston rod. Further, when the piston rod extends to the vicinity of its stroke end, the cylinder portion of the fixed spring receiver and the movable spring receiver and the plunger are engaged with each other to form an oil chamber, and the oil chamber is compressed so that the oil liquid passes through the orifice. By flowing out to the outside, a damping force due to fluid force is applied to the piston rod. Thereby, the impact and noise at the time of rebound can be reduced effectively.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
A first embodiment of the present invention will be described with reference to FIG. As shown in FIG. 1, a hydraulic shock absorber 1 according to a first embodiment of the present invention is a single cylinder type hydraulic shock absorber mounted on a suspension device of an automobile, and is provided in a cylinder 2 in which oil is sealed. The piston 3 is slidably fitted, and the piston 3 divides the inside of the cylinder 2 into two chambers, a cylinder upper chamber 2A and a cylinder lower chamber 2B. One end of a piston rod 4 is connected to the piston 3 by a nut 5, and the other end side of the piston rod 4 is inserted into a rod guide 6 and oil seals 7 and 8 attached to the upper end portion of the cylinder 2. It is extended to the outside. A free piston 9 is slidably fitted at the lower end of the cylinder 2, a gas chamber 10 is formed at the bottom of the cylinder 2, and high pressure gas is sealed in the gas chamber 10.

  The piston 3 is provided with an extension side oil passage 11 and a contraction side oil passage 12 that communicate between the cylinder upper and lower chambers 2A, 2B. The extension side oil passage 11 and the contraction side oil passage 12 are respectively provided with an extension side damping force generation mechanism 13 (damping force generation mechanism) composed of an orifice, a disk valve and the like that control the flow of the oil to generate a damping force. A compression-side damping force generation mechanism 14 (damping force generation mechanism) is provided.

In the cylinder upper chamber 2A, the piston rod 4 is provided with a rebound stopper mechanism R for limiting the extension thereof. The cylinder stopper mechanism R will be described next.
In the cylinder upper chamber 2 </ b> A, a ring-shaped fixed spring receiver 15 is fitted on the piston 3 side of the piston rod 4 and fixed in the axial direction by a retaining ring 16. A flange portion 17 is formed on the outer peripheral portion of the lower end of the fixed spring receiver 15, and a cylindrical mounting portion 18 projects from the inner peripheral portion of the upper end. A cylindrical plunger 19 is press-fitted and fixed to the mounting portion 18 of the fixed spring receiver 15. The inner diameter of the plunger 19 is larger than the outer diameter of the piston rod 4, and an annular gap 20 is formed between them. A pair of orifices 21 are pierced in the diameter direction on the side wall near the lower end of the plunger 19.

  On the rod guide 6 side of the piston rod 4, a ring-shaped movable spring receiver 22 is slidably fitted. A flange portion 23 facing the flange portion 17 of the fixed spring receiver 15 is formed on the outer periphery of the upper end of the movable spring receiver 22, and a cylinder portion 24 into which the plunger 19 can be inserted is formed on the lower end portion. Tapered portions 19 </ b> A and 24 </ b> A are formed at the distal end portions of the plunger 19 and the cylinder portion 24 to facilitate mutual insertion. A cushion material 25 is attached to the upper end portion of the movable spring receiver 22, and this cushion material 25 also serves as a seal for the upper end portion of the cylinder portion 24.

  A rebound spring 26 (spring means), which is a compression spring, is interposed between the flange portion 17 of the fixed spring receiver 15 and the flange portion 23 of the movable spring receiver 22, and both end portions of the rebound spring 26 are fixed. The spring receiver 15 and the movable spring receiver 22 are coupled. Further, a stopper 27 capable of contacting the cushion material 25 of the movable spring receiver 22 is fixed to the upper end portion of the cylinder upper chamber 2A.

The operation of the present embodiment configured as described above will be described next.
During the extension stroke of the piston rod 4, as the piston 3 slides in the cylinder 2, the oil in the cylinder upper chamber 2 </ b> A flows to the cylinder lower chamber 2 </ b> B through the extension side oil passage 11 of the piston 3, and the extension side damping force A damping force is generated by the generation mechanism 13. At this time, the gas in the gas chamber 10 expands as much as the piston rod 4 is withdrawn from the cylinder 2 to compensate for the volume change in the cylinder 2.

  During the contraction stroke, as the piston 3 in the cylinder 2 slides, the oil in the cylinder lower chamber 2B flows into the cylinder upper chamber 2A through the contraction-side oil passage 12 of the piston 3, and the compression-side damping force of the piston 3 is generated. A damping force is generated by the mechanism 14. At this time, the gas in the gas chamber is compressed as much as the piston rod 4 enters the cylinder 2 to compensate for the volume change in the cylinder 2.

  When the piston rod 4 is extended to a predetermined position, the cushion material 25 of the movable spring receiver 22 comes into contact with a stopper 27 fixed to the upper end portion of the cylinder upper chamber 2A, and the rebound spring 26 is further expanded against the further extension of the piston rod 4. Is compressed to absorb the force acting on the piston rod 4 by applying the spring force.

  When the piston rod 4 further extends and reaches the vicinity of the extended stroke end, the tip of the plunger 19 of the fixed spring receiver 15 is fitted into the cylinder portion 24 of the movable spring receiver 22 as shown in FIG. The oil chamber 28 is formed by the gap 20 between the inside of the cylinder portion 24 and the plunger 19. In this state, when the piston rod 4 further expands, the oil chamber 28 is compressed, and the oil in the oil chamber 28 flows out through the orifice 21 on the side wall of the plunger 19 to the cylinder upper chamber 2A. At this time, due to the flow resistance of the orifice 21, a large damping force due to the fluid force acts on the extension of the piston rod 4, thereby reducing the impact and noise when reaching the stroke end.

  In this way, the impact and noise when the hydraulic shock absorber 1 is rebounded can be effectively reduced by the fluid force. At this time, since the fluid force acting on the piston rod 4 can be changed by changing the diameter of the orifice 21, tuning can be easily performed. In addition, since an elastic body having a large deformation amount is not used as the cushioning material, it is excellent in durability.

  In the above embodiment, the plunger 19 is provided on the fixed spring receiver 15 and the cylinder portion 24 is provided on the movable spring receiver 22, but conversely, the cylinder portion is provided on the fixed spring receiver 15 to provide the movable spring receiver with the cylinder portion 24. A plunger can also be provided. In addition, the orifice 21 may be provided in the cylinder part 24 or may be provided in both the plunger 19 and the cylinder part 24.

1 is a longitudinal sectional view of a hydraulic shock absorber according to an embodiment of the present invention. It is a figure which expands and shows the rebound spring part which is the principal part of the hydraulic shock absorber shown in FIG. In the hydraulic shock absorber shown in FIG. 1, it is an enlarged view of the rebound spring part which shows the state which the piston rod extended to near stroke end.

Explanation of symbols

1 Hydraulic shock absorber, 2 cylinders, 3 pistons, 4 piston rods, 13 expansion side damping force generation mechanism (damping force generation mechanism), 14 contraction side damping force generation mechanism (damping force generation mechanism), 15 fixed spring holder, 19 plunger , 21 Orifice, 22 Movable spring receiver, 24 Cylinder, 26 Rebound spring (spring means), 27 Stopper, 28 Oil chamber, R Rebound stopper mechanism

Claims (1)

A cylinder filled with oil, a piston slidably fitted in the cylinder, a piston rod having one end connected to the piston and the other end extending outside the cylinder, and the cylinder In a hydraulic shock absorber provided with a damping force generation mechanism that generates a damping force by controlling the flow of oil liquid generated by sliding of the piston in the inside, and a rebound stopper mechanism that limits the extension of the piston rod,
The rebound stopper mechanism includes a fixed spring receiver fixed to the piston rod inside the cylinder and a movable spring receiver slidably provided on the piston rod and capable of contacting a stopper fixed in the cylinder. And spring means interposed between the fixed spring receiver and the movable spring receiver, and the fixed spring receiver and the movable spring receiver are engaged with each other in the vicinity of the stroke end on the extension side of the piston rod. One of a cylinder part and a plunger forming an oil chamber is provided, and at least one of the cylinder part and the plunger is provided with an orifice for communicating the oil chamber to the outside. Shock absorber.

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