JPH0235059Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an improvement in the structure of the oil seal portion of a front fork.

(Prior art) An oil seal is fitted on the inner periphery of the bottom case opening of the front fork to prevent leakage of the hydraulic oil sealed inside to the outside, but oil seals that occur between this oil seal and the fork pipe Grease is supplied to the oil seal lip in order to reduce sliding resistance.

(Problem to be solved by new invention) However, in the past, it was not possible to supply grease evenly over the entire circumference of the sliding contact surface between the oil seal and the fork pipe, making it difficult to completely reduce sliding resistance. It was hot.

Therefore, the purpose of this invention is to have a front fork oil seal structure that can uniformly supply grease to the sliding surfaces of the oil seal and fork pipe and minimize the sliding resistance generated on the sliding surfaces. is to provide.

(Means for Solving the Problems) In order to achieve the above object, the present invention forms a concave groove around the entire circumference at the fitting part between the bottom case and the oil seal, and a grease nit that opens into the concave groove. The pull is screwed onto the bottom case, and a plurality of small holes are radially bored between the oil seal's dust lip and the oil lip to communicate with the groove, and the cross-sectional area of the groove in the direction perpendicular to the grease flow direction is was made larger than the cross-sectional area of the small hole in the direction perpendicular to the flow direction of the grease.

(Example) An example of the present invention will be described below based on the accompanying drawings.

FIG. 1 is a longitudinal sectional view of the upper part of the bottom case of a front fork showing the oil seal structure according to the present invention, and FIG. 2 is a sectional view taken along the line 2-2 in FIG. 1.

In the figure, reference numeral 1 denotes a bottom case of a front fork, into which a fork pipe 2 is inserted and fitted via a guide bush 3 so as to be vertically slidable. An oil seal 4 is fitted on the inner circumference of the upper end of the bottom case 1, and is positioned and fixed by a stopper ring 5.

Incidentally, a recessed groove 1a is formed all around the bottom case 1 on the fitting surface with the oil seal 4, and a grease nipple 6 having an opening 6a in the recessed groove 1a is screwed into the bottom case 1. ing. A grease inlet 6b is opened in this grease nipple 6, and this inlet 6b is closed by a ball valve 9 formed by a ball 7 and a spring 8 provided in the grease nipple 6. ing.

On the other hand, the dust lip 4a of the oil seal 4
A plurality of small holes 4c (six in the illustrated example) opening into the groove 1a provided in the bottom case 1 are bored between the oil lip 4b and the oil lip 4b. The cross-sectional area of the groove 1a in the direction perpendicular to the grease flow direction is set larger than the cross-sectional area of the small hole 4c in the direction perpendicular to the grease flow direction.

Therefore, when grease is injected from the inlet 6b of the grease nipple 6, the cross-sectional area of the small hole 4c in the direction perpendicular to the flow direction of the grease becomes perpendicular to the flow direction of the grease in the groove 1a as described above. Since it is smaller than the cross-sectional area in the direction, it exhibits a large resistance to the inflow of grease, and the grease entering from the grease nipple 6 first spreads around the entire circumference of the groove 1a, that is, to the opposite side from the grease nipple, and then the grease enters the groove 1a. When the filling pressure is increased, each small hole 4 in the radial direction
Since it is applied more uniformly to the outer circumference of the fork pipe than c, friction can be reduced uniformly over the entire circumference of the fork pipe. This reduces the frictional resistance acting on the sliding surface between the oil seal 4 and the fork pipe 2, and also improves the durability of the oil seal 4 itself.

As described above, since the grease is uniformly supplied through the small holes 4c radially drilled in the sliding contact surface between the oil seal 4 and the fork pipe 2, the sliding resistance acting on the sliding contact surface is reduced. It can be kept to a minimum.

Although the example in which the groove 1a is provided on the bottom case 1 side has been shown above, the groove 4a may be provided on the oil seal 4 side as shown in FIG.

(Effects of the invention) As is clear from the above explanation, according to the invention, a concave groove is formed around the entire circumference at the fitting portion between the bottom case and the oil seal, and a grease nipple is provided that opens into the concave groove. It is screwed onto the bottom case, and small holes opening into the grooves are radially drilled between the dust lip and oil lip of the oil seal, and the cross-sectional area of the grooves is larger than the sum of the cross-sectional areas of the small holes, so that oil By uniformly supplying grease to the sliding surfaces of the seal and fork pipe, the sliding resistance generated on the sliding surfaces can be minimized.

[Brief explanation of drawings]

Fig. 1 is a vertical sectional view of the upper part of the bottom case of a front fork showing the structure of the oil seal portion according to the present invention, Fig. 2 is a sectional view taken along line 2-2 in Fig. 1, and Fig. 3 is an oil seal according to a modified embodiment. FIG. 2 is a diagram similar to FIG. 1 showing the partial structure. In addition, in the drawing, 1 is the bottom case, 1a is the groove,
2 is a fork pipe, 4 is an oil seal, 4a is a dust lip, 4b is an oil lip, 4c is a small hole, and 6 is a grease nipple.

Claims (1)

[Scope of utility model registration request] In a front fork oil seal structure in which an oil seal that slides on the outer periphery of the fork pipe is fitted to the inner periphery of the opening of the bottom case, a concave groove extending all the way around the fitting part of the bottom case and the oil seal is provided. At the same time, a grease nipple opening into the groove is screwed onto the bottom case, and a plurality of small holes communicating with the groove are radially bored between the dust lip of the oil seal and the oil lip. An oil seal structure for a front fork, characterized in that a cross-sectional area of the small hole in a direction perpendicular to the grease flow direction is larger than a cross-sectional area of the small hole in a direction perpendicular to the grease flow direction.