JPH0333934B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rod guide for slidably holding a piston rod of a shock absorber.

Shock absorbers applied to vehicles generally consist of a cylinder and a piston rod that has a piston attached to it so that it can slide freely inside the cylinder.For example, the cylinder is attached to the wheel side, the piston rod is attached to the vehicle body, and the piston is attached to the road surface. The vertical movement of the wheel in response to unevenness is absorbed by the expansion and contraction movement of the shock absorber, and a damping force is generated during this expansion and contraction movement to improve riding comfort.

In this manner, the shock absorber performs its function through relative movement in the axial direction between the cylindrical body and the piston rod to which the piston is attached, so the piston rod is held slidably relative to the body via the rod guide. Although a low-friction oil metal or the like is generally used as the rod guide, the force acting on the shock absorber does not coincide with the axial direction of the piston rod, and there are also side forces that act in a lateral direction to the shock absorber. This side force acts on the shock absorber as a bending moment, which causes friction between the piston rod and the rod guide, making it impossible to obtain a stable damping force, resulting in poor riding comfort.

As a solution to this problem, the Utility Model 52-4616
No. is proposed. The content of this prior example is that a ball bearing is provided linearly in the guide of the piston rod, and although it is effective to some extent in reducing friction due to side forces, it cannot be said to be sufficient.

An object of the present invention is to provide a rod guide that can exhibit a remarkable effect in reducing friction than the above-mentioned prior art, and to achieve this object, the present invention divides the rod guide into an inner ring and an outer ring, and A plurality of bearing groups, each consisting of a large number of ball bearings arranged in a ring shape, are held radially around the piston rod, and a bearing such as a roller bearing is interposed between the inner ring and the outer ring. The gist is:

Embodiments of the present invention will be described below based on the accompanying drawings.

Fig. 1 is a side sectional view showing the internal structure of a hydraulic shock absorber to which the rod guide according to the present invention is applied, Fig. 2 is a plan sectional view of the same shock absorber, Fig. 3 is a perspective view showing the structure of the rod guide, and Fig. 4 The figure is an exploded perspective view of the same rod guide.

In the figure, 1 is an outer tube, and an inner tube 2 is disposed inside the outer tube 1. A piston rod 3 is inserted into the inner tube 2, and the lower end of the piston rod 3 is in sliding contact with the inner surface of the inner tube 2. The piston 4 is fixed. An oil chamber A is formed by the outer tube 1 and the inner tube 2, and an oil chamber B is formed inside the inner tube 2.

Further, the top of the inner tube 2 is supported by a side plate 5, and between this side plate 5 and a side plate 6 above this, a rod guide 7, which is the gist of the present invention, is provided to slidably support the piston rod 3. .
Here, a seal ring 8 is fitted onto the inner peripheral surface of the side plate 6 to prevent oil leakage from the oil chamber B and to obtain a stable damping force. Furthermore, an oil seal 10 is held above the side plate 6 by an oil seal case 9.

Next, details of the rod guide 7 will be explained based on FIGS. 2 to 4.

The rod guide 7 has an inner ring 11 and an outer ring 12,
The inner ring 11 further includes a first inner ring 11a and a second inner ring 11b disposed outside of the first inner ring 11a. 1st inner ring 11
a consists of alternating and integrally continuing blocks 13 having a prismatic shape and blocks 14 having an oval shape in cross section;
A second inner ring 1 attached to the outside of the inner ring 11a
Block 1 of the first inner ring 11a is on the inner surface of 1b.
3 and a recess 16 facing the block 14 of the first inner ring 11a are alternately and continuously formed, and step portions 17 and 18 are provided at the upper and lower portions of the recess 16. A locking piece 20 of the upper holder 19 having an arc-shaped inner surface 19a is fitted into the portion 17, and a locking piece 22 of the lower holder 21, which also has an arc-shaped inner surface 21a, is fitted into the stepped portion 18.

Then, the second inner ring 11b is fitted onto the first inner ring 11a, and the upper and lower holding bodies 19, 21 are fitted onto the second inner ring 1.
By fitting into the step portions 17 and 18 of 1b, a ring-shaped ball bearing holding space _S1 is formed. A ring-shaped bearing group 25 is formed by housing a large number of ball bearings 24 in this space _S1 . Next, the first inner ring 11
By fitting the holding plate 27 with an opening 26 through which a part of the ball bearings 24 are exposed from the inside of the bearing group 25, the bearing groups 25 are arranged radially around the piston rod 3, as shown in the cross-sectional plan view of FIG. The location is maintained.

Further, in the space S2 between the second inner ring 11b and the outer ring ₁₂ , a roller bearing 28 is installed between the upper and lower retaining plates 29, 2.
It is held and arranged at 9. This holding plate 29 is formed with a protrusion 30 for regulating the vertical position of the roller bearing 28 and a piece 31 for regulating the horizontal position. The upper and lower surfaces of the rod guide 7 assembled in this way are connected to the thrust plates 32 and 3.
It is mounted in the outer tube 1 while being held by the side plates 5 and 6 via the tubes 2.

In addition, as shown in FIGS. 1 and 2, side plates 5,
6 and the outer circumferential surface of the outer ring 12 are formed with vertical grooves 33, and the hydraulic oil scraped off by the oil seal 10 flows through the vertical grooves 33 into the oil chamber A.
brought back inside.

In addition, in the illustrated example, the second inner ring 11b and the outer ring 1
A roller bearing 28 was arranged between the
A ball bearing or the like may be provided.

In the above, the piston rod 3 is slid in the axial direction via the ball bearing 24 with extremely low friction, and the piston rod 3 is rotated around the axis smoothly via the roller bearing 28.

FIG. 5 is a graph showing the relationship between the side force and friction of a shock absorber using the rod guide according to the present invention and a conventional shock absorber, where the solid line _l1 represents the product of the present invention and the dashed line _l2 represents the conventional product. show. As is clear from this graph, the characteristic line _l1 of the shock absorber using the rod guide according to the present invention is almost flat compared to the conventional shock absorber, and even when a large side force acts, there is a slight increase in friction. It turns out that you can get away with it.

As explained above, according to the present invention, the guide of the piston rod of the shock absorber is composed of an inner ring and an outer ring, and the inner ring has a plurality of bearing groups in which a large number of ball bearings are arranged in a ring shape. This allows the piston rod to slide in the axial direction with extremely small friction, and since a bearing is also interposed between the inner and outer rings, the piston rod can rotate around its axis without large friction. It can be done smoothly without any complications.

Therefore, even if a large side force acts on the shock absorber, the occurrence of friction can be suppressed to an extremely small amount, and many effects such as greatly improved riding comfort are exhibited.

[Brief explanation of the drawing]

Fig. 1 is a side sectional view showing the internal structure of a hydraulic shock absorber using a rod guide according to the present invention, Fig. 2 is a plan sectional view of the same shock absorber, Fig. 3 is a cutaway perspective view of the rod guide, and Fig. 4 is a An exploded perspective view of the same rod guide.
FIG. 5 is a graph showing the relationship between side force and friction. In the drawings, 1 is an outer tube, 2 is an inner tube, 3 is a piston rod, 7 is a rod guide, 11 is an inner ring, 11a is a first inner ring, 11b is a second inner ring, 12 is an outer ring, 19 and 21 are a holding body, and 24
is a ball bearing, 25 is a bearing group, 27
is a holding plate, and 28 is a roller bearing.

Claims (1)

[Claims] 1. A rod guide that slidably holds a piston rod of a shock absorber, and this rod guide has an inner ring and an outer ring, and the inner ring has a plurality of bearing groups each having a large number of ball bearings arranged in a ring shape, which hold the rod radially around the piston rod. A rod guide characterized in that a bearing is also interposed between the inner ring and the outer ring.