GB2086004A - Shock absorber with rotatable coil spring seat - Google Patents

Abstract

A spring seat 5 for receiving the end of a coil spring 1 in a shock absorber is made rotatable by the inclusion of a low friction member located between the seat 5 and a plate 9 and comprising a ring-shaped frame 7 formed with holes containing ball bearings 6. <IMAGE>

Description

SPECIFICATION Shock absorber This invention relates to shock absorbers including coiled compression springs.

In such shock absorbers, in which a piston is slidably fitted in a cylinder and a coil spring surrounding the rod of the piston acts against the cylinder, the spring seat of the coil spring is normally fixed. Especially when the spring seat is fixed to an end member screwed into the end of a tube, the screwed portion of the end member is so constructed that it is made more secure by the torsion established when the coil spring is compressed. As a result, metal chips are generated by the friction between the curled end of the coil spring and the spring seat due to the relative movement caused by the torsion resulting from the compression and these chips clog the oil ports, thereby reducing the shock absorbing effect.

In addition the coil spring and the inner surface of the tube of the shock absorber contact each other, when the former bulges outwardly under the compression, thereby adversely affecting the operating characteristics and performance of the shock absorber and shortening its life.

According to the present invention, these disadvantages are overcome by making at least one of the spring seats for the ends of the coil spring rotatable by means of a low friction member.

An example of a shock absorber according to the present invention will now be described, with reference to the accompanying drawing which is a longitudinal section.

In the shock absorber illustrated a coiled compression spring 1 is interposed between an end member 3 supporting one end of a piston rod 2 and the corresponding cylinder portion (not shown) which is located at the other end of the piston rod 2. The spring 1 is enclosed by a tube 4 and end of the spring is retained by a spring seat 5 which is arranged to rotate through a number of low friction members 6 at the rear of the pressure receiving surface and which are shown as supported by a seat plate 9, which may not be necessary in all constructions.

The low friction members 6 have the function of reducing the rolling friction, being, for example, in the forum of ball bearings or rollers, which are fitted to rotate in holes or recesses 8 formed in a ring-shaped supporting frame or cage 7. As a result, the spring seat 5 engaging with these low friction members is allowed to rotate with the end of the coil spring 1 by the rolling friction resulting from the low friction members 6, in accordance with the torsion which is established when the coil spring 1 is compressed.

A similar spring receiving structure can also be applied to the spring seat at the other end (i.e. the cylinder end) of the coil spring. Thus, the spring seats at one or both ends of the coil spring are constructed as described.

As a result of the reduction of friction between the coil spring and the seat or seats the generation of metal chips and the deformation of the spring to engage the tube are prevented so that the performance of the shock absorber can be maintained at a high level.

1. A shock absorber including a piston slidably fitted in a cylinder and a coiled compression spring surrounding the rod of the piston and acting against the cylinder, and in which one end of the coil spring is received by a seat capable of rotation through a low friction member.

2. A shock absorber according to claim 1 in which both ends of the coil spring are received by such rotary seats.

3. A shock absorber according to claim 1 or claim 2 in which the or each low friction member includes a ring-shaped supporting frame formed with holes or recesses enclosing ball bearings or rollers.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (3)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Shock absorber This invention relates to shock absorbers including coiled compression springs. In such shock absorbers, in which a piston is slidably fitted in a cylinder and a coil spring surrounding the rod of the piston acts against the cylinder, the spring seat of the coil spring is normally fixed. Especially when the spring seat is fixed to an end member screwed into the end of a tube, the screwed portion of the end member is so constructed that it is made more secure by the torsion established when the coil spring is compressed. As a result, metal chips are generated by the friction between the curled end of the coil spring and the spring seat due to the relative movement caused by the torsion resulting from the compression and these chips clog the oil ports, thereby reducing the shock absorbing effect. In addition the coil spring and the inner surface of the tube of the shock absorber contact each other, when the former bulges outwardly under the compression, thereby adversely affecting the operating characteristics and performance of the shock absorber and shortening its life. According to the present invention, these disadvantages are overcome by making at least one of the spring seats for the ends of the coil spring rotatable by means of a low friction member. An example of a shock absorber according to the present invention will now be described, with reference to the accompanying drawing which is a longitudinal section. In the shock absorber illustrated a coiled compression spring 1 is interposed between an end member 3 supporting one end of a piston rod 2 and the corresponding cylinder portion (not shown) which is located at the other end of the piston rod 2. The spring 1 is enclosed by a tube 4 and end of the spring is retained by a spring seat 5 which is arranged to rotate through a number of low friction members 6 at the rear of the pressure receiving surface and which are shown as supported by a seat plate 9, which may not be necessary in all constructions. The low friction members 6 have the function of reducing the rolling friction, being, for example, in the forum of ball bearings or rollers, which are fitted to rotate in holes or recesses 8 formed in a ring-shaped supporting frame or cage 7. As a result, the spring seat 5 engaging with these low friction members is allowed to rotate with the end of the coil spring 1 by the rolling friction resulting from the low friction members 6, in accordance with the torsion which is established when the coil spring 1 is compressed. A similar spring receiving structure can also be applied to the spring seat at the other end (i.e. the cylinder end) of the coil spring. Thus, the spring seats at one or both ends of the coil spring are constructed as described. As a result of the reduction of friction between the coil spring and the seat or seats the generation of metal chips and the deformation of the spring to engage the tube are prevented so that the performance of the shock absorber can be maintained at a high level. CLAIMS

1. A shock absorber including a piston slidably fitted in a cylinder and a coiled compression spring surrounding the rod of the piston and acting against the cylinder, and in which one end of the coil spring is received by a seat capable of rotation through a low friction member.

2. A shock absorber according to claim 1 in which both ends of the coil spring are received by such rotary seats.

3. A shock absorber according to claim 1 or claim 2 in which the or each low friction member includes a ring-shaped supporting frame formed with holes or recesses enclosing ball bearings or rollers.