JP2585337Y2 - shock absorber - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a shock absorber having a rebound spring in a piston rod stopper mechanism.

[0002]

2. Description of the Related Art Conventionally, a piston rod in a cylinder is extended, for example, to the outer peripheral side of the piston rod between the piston and the cylinder end in order to make the piston rod gently move before strongly hitting the cylinder end. A rebound spring is arranged. As a method for setting such a rebound spring in a cylinder, for example, as disclosed in Japanese Patent Publication No. 61-42135,
A method of directly press-fitting the above-mentioned rebound spring (coil spring) having the same pitch over the entire length to the inner peripheral surface of the cylinder is widely adopted. Further, no member or the like for restricting the movement of the rebound spring in the inner diameter direction is provided inside the rebound spring or on the outer peripheral side of the piston rod.

[0003]

[Problems to be Solved by the Invention] Since the conventional shock absorber is configured as described above, the rebound spring is pressed into the inner periphery of the cylinder and is not firmly fixed to the seal guide unit or the like. When the piston rod reciprocates, it moves between the collar attached to the piston or piston rod and the metal seal guide unit at the cylinder end, causing the rebound spring to make metal contact with the collar and the seal guide unit. In addition to the above, there has been a problem that the outer periphery of the piston rod is damaged due to the radial expansion and contraction of the rebound spring, which causes oil leakage from the cylinder end.

The present invention has been made in view of the above-mentioned conventional problems, and aims to prevent the piston rod from being damaged when the rebound spring is deformed and to stabilize the axial position of the end of the rebound spring. It is another object of the present invention to provide a shock absorber that can avoid generation of noise due to metal contact between a rebound spring and a collar or a seal guide unit.

[0005]

A shock absorber according to the present invention closes a cylinder end and guides a piston rod slidably in a sealed state, and a seal guide unit covering the outer circumference of the piston rod. An upper collar which is attached to the seal guide unit via a reinforcing metal fitting and has a spiral groove of a small pitch on the outer periphery, and the upper cylinder which is inserted into the outer periphery of the piston rod and extends together with the piston rod when the piston rod extends over a set length. And a lower collar having a spiral groove with a small pitch on the outer periphery, and screw both ends of a rebound spring wound at a smaller pitch than the other part into each of the turning grooves of the upper collar and the lower collar. It is configured as follows.

[0006]

Since the rebound spring in the present invention is on the upper collar and the lower collar on the outer peripheral side of the piston rod, it does not come into contact with the outer periphery of the piston rod even when deformed during compression, so that the piston rod is damaged. No more. Also, since this rebound spring has a smaller pitch at both ends than the other part (about 2 to 3 turns may contact at a pitch of 0) and is screwed into the spiral grooves of the upper collar and the lower collar,
Both ends of the spring are securely held by the respective collars, so that the axial position is stabilized, and in particular, when compressed, they act so as to bite into the respective spiral grooves, and the removal from the respective collars is reliably prevented. For this reason, it is possible to avoid the conventional problem that the rebound spring collides with each collar and generates abnormal noise.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 denotes a piston rod inserted into a cylinder 2; 3, a piston for mounting a compression-side damping force which is attached to the piston rod 1 and slides in the cylinder 2; A rod-side chamber and a piston-side chamber separated inside, 6 is a bottom valve for generating an extension-side damping force, 7 is an outer tube that forms a passage 8 for hydraulic oil outside the cylinder 2, and 9 is a rod-side end of the cylinder 2 A seal guide unit 10 for closing the portion, a cap 10 for closing the rod-side end of the outer tube 7 via an oil seal 11 or the like, and a flange 12 is sandwiched between the end of the cylinder 2 and one side of the seal guide unit 9. A ring-shaped reinforcing metal member 13 is an upper collar attached to the reinforcing metal member 12. The upper collar 13 is a cylindrical body 13 with a plastic flange 13a as a whole.
The piston rod 1 is movable or slidable in the cylindrical body 13b. The inner peripheral portion of the reinforcing metal fitting 12 is embedded in the flange 13a. Reference numeral 14 denotes a spiral groove formed on the outer periphery of the cylindrical body 13b of the upper collar 13, and its pitch is relatively narrow. One end of a rebound spring described later can be screwed between the spiral groove 14 and the cylinder 2. It has become.
Reference numeral 15 denotes a plastic lower collar in which a center hole is inserted through the piston rod 1, which is composed of a cylindrical body 15b with a flange 15a, and a spiral groove 16 having a narrow pitch is formed on the outer periphery of the cylindrical body 15a. I have. The other end of a rebound spring described later can be screwed between the spiral groove 16 and the cylinder 2. The rebound spring 17 has a smaller pitch at both ends than at other ends (between both ends), and preferably a couple of turns are in contact with each other. Reference numeral 18 denotes an operation piece attached to the piston rod 1 between the lower collar 15 and the piston 3. When the amount of expansion of the piston rod 1 exceeds a set value, the lower collar 15 is pushed up against the rebound spring 17. Function.

In the damping force adjusting device having such a configuration, it is suspended between the vehicle body side and the axle side of the vehicle, and the piston 3 slides in the cylinder 2 by receiving the compression side load and the extension side load received by the piston rod 1. Move. At this time, from one side of the rod side chamber 4 and the piston side chamber 5 separated by the piston 3 to the other, and from one side of the piston side chamber 5 and the passage 8 to the other, the piston 3 and the bottom valve 6
The hydraulic oil gradually flows through each of them. For this reason,
The compression side damping force and the extension side damping force are generated.

On the other hand, in the extension stroke of the piston rod 1, at the time of a continuous extension load, the action piece 18 moves with a stroke that does not contact the lower collar 15, and generates an intended extension-side damping force. However, when an extension load exceeding the set level is received, the lower collar 15 contacts one surface,
Further, this is pushed up against the repulsive force of the rebound spring 17. For this reason, the force which suppresses the movement in the extension direction acts on the piston rod 1, and the excessive extension load is rapidly attenuated, so that the impact on the vehicle body based on the extension load can be suppressed. Then, at this time, the lower collar 15 slides along the outer periphery of the piston rod 1, so that the rebound spring 17 is compressed, and the diameter of the rebound spring 17 is changed by this compression. However, the deformation of the rebound spring 17 is restricted by the inner peripheral surface of the cylinder 2 and eventually bends toward the piston rod 1. However, since there is a dimensional allowance between the rebound spring 17 and the piston rod 1 by the thickness of the cylindrical bodies 13b, 15b of the upper collar 13 and the lower collar 15, the bending causes the inside of the rebound spring 17 to move. There is no contact with the outer periphery of the peripheral piston rod 1. As a result, the outer peripheral surface of the piston rod 1 is not damaged, and an accident that the hydraulic oil leaks out of the rod side chamber 4 via the seal guide unit 9 due to the damage can be avoided.

The pitch of the rebound spring 17 is smaller at both ends than at the other portions.
6, the collision action between the rebound spring 17 and each of the collars 13 and 15 is eliminated, so that the generation of abnormal noise due to the collision action can be avoided, and the engagement with each of the collars 13 and 15 is prevented. Can be prevented.
In addition, the rebound spring 17
Of the helical grooves 14, 1
6 and rebound spring 1
7 is securely held in the axial direction. The upper collar 13 is securely attached to the end of the cylinder 2 by the reinforcing metal fitting 12.

[0011]

As described above, according to the present invention, the seal guide unit for closing the cylinder end and guiding the piston rod slidably in a sealed state, and the seal guide unit so as to cover the outer periphery of the piston rod An upper collar which is attached to the unit via a reinforcing bracket and has a spiral groove of a small pitch on the outer periphery, and which is inserted through the outer periphery of the piston rod and extends inside the cylinder together with the piston rod when the piston rod extends over a set length. A lower collar having a helical groove with a small pitch on the outer periphery that moves, and screwing both ends of a rebound spring wound at a smaller pitch than the other part into each helical groove of the upper collar and the lower collar. With this configuration, it is possible to reliably prevent the piston rod from being damaged by the rebound spring. The collision action between the ring and the upper and lower collars is eliminated, preventing the generation of abnormal noise due to metal contact as in the past, and effectively damping the extension side load above the set level, reducing the impact on the vehicle body The practical effect of being able to relax is obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a shock absorber according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piston rod 2 Cylinder 3 Piston 4 Rod side chamber 5 Piston side chamber 9 Seal guide unit 13 Upper collar 14 Spiral groove 15 Lower collar 16 Spiral groove 17 Rebound spring

Claims (1)

(57) [Scope of request for utility model registration] 1. A piston rod inserted into a cylinder, a piston attached to the piston rod and separating a piston side chamber and a rod side chamber in the cylinder, and sealing the piston rod by closing an end of the cylinder. A seal guide unit slidably guided in a state, and an upper collar having a small pitch spiral groove attached to the seal guide unit via a reinforcement while being arranged so as to cover the outer periphery of the piston rod. A lower collar, which is inserted into the outer periphery of the piston rod and moves in the cylinder together with the piston rod when the piston rod extends for a set length or more and has a spiral groove with a small pitch on the outer periphery, Both ends wound at a pitch are screwed into the spiral grooves of the upper and lower collars. Shock absorber with bound spring.