GB2207977A

GB2207977A - Piston for shock absorbers

Info

Publication number: GB2207977A
Application number: GB08818367A
Authority: GB
Inventors: Munoz Juan Jose Marcos
Original assignee: Plastica & Met Ind
Current assignee: Plastica & Met Ind
Priority date: 1987-08-03
Filing date: 1988-08-02
Publication date: 1989-02-15
Anticipated expiration: 2008-08-02
Also published as: ES1003062U; DE3826148C2; IT1226578B; GB8818367D0; FR2619178A1; ES1003062Y; DE3826148A1; FR2619178B1; GB2207977B; IT8821620A0

Description

9 2 0 7 9 y -1.

11 PISTON FOR SHOCK ABSORBERS SPECIFICATION

OBJECT OF THE INVENTION The present invention relates to a piston for shock absorbers, of the type wherein the piston itself, besides being provided with an axial bore for coupling thereof to the rod, is provided with a plurality of apertures which are preferably in a perimetral alignment, said apertures being destined to be partially obturated by means of washers, positioned at both sides of the said piston, and which regulate the flow of liquid in the two directions, during the normal piling up of the shock absorber.

BACKGROUND OF THE INVENTION

Usual shock absorbers are comprised by means of the operative combination of a cylinder and a rod, the latter being provided with a piston which defines two chambers, interconnected through the piston itself, in the cylinder, the operativeness of the shock absorber as a whole depending on the communication means between the said two chambers, established in the piston itself.

Due to the fact that the market demands shock absorbers with different operative features, and furthermore due to the fact that in any case all shock absorbers must afford different operative features during the contraction and extension thereof, to date and for each specific case, an adequate piston is required, with one or more washers likewise being required, which determine specific features for the shock absorber.

In this sense Spanish Utility Models 247,814 and 147,816, owned by the applicant of the present invention, should be quoted.

L- In the solutions afforded by said Spanish Utility Models two essential problems arise: on the one hand it is necessary to use perforated washers, which perforations imply a considerable increase in the cost for obtaining same, and on the other hand such washers require positioning means which ensure in the context of the piston the correct positioning in relation thereto and to the piston itself. Furthermore, and given that these washers are resiliently deformed by the thrust bearing generated by the decanting of the fluid f rom one chamber to another of the shock absorber, when there is a reversion in the displacement of the piston, the abrupt resilient recovery of such washers determines a hammering thereof against the front of the piston itself, which generates an undesireable noise.

DESCRIPTION OF THE INVENTION

The piston for shock absorbers of the invention, f ully solves all the aspects of this problem, allowing the use of conventional washers, i.e., of washers exclusively provided with the unavoidable central aperture. for the coupling thereof to the piston itself, forming part of the gasket' correponding thereto, without the need of positioning means and likewise eliminating the noise problems to which reference has been made.

For this purpose, and more specifically, the piston of the invention centres its features in the use of blind washers, as has been previously said, which afford the regulation at will of the flow of liquid through the piston by means of the adequate selection of the diameter thereof, such that depending on the diameter of such washers, same will obturate to a greater or lesser extent the section of the perimetral set of apertures established in the piston itself and, consequently, will allow the desired regulation of the flow.

Pursuant to a further characteristic of the invention, the peripheral zone established between. the apertures and the edge of the piston itself is recessed, in order to establish a "high-relief" i %W 3.- f or the mouth of said apertures which minimizes the contact surf ace.of the washers with the piston, especially when same are resiliently recovered, wherefore when same strike the noticeably sharp edge, instead of the a flat surface, the sound generated in the piston is practically non-existent.

More specifically, this "high-relief 11 for the mouth of the apertures, which minimizes the contact surface of the washers with the piston, af f ects a narrow marginal and external zone of such apertures, a sinuous line being def ined f or the free edge of such high-reliefs, which is interrupted between each pair of adjacent apertures, specifically in correspondence with radial branches which extend up to the linking rim between this face of the piston and the side surface thereof, and which likewise afford a minimum surface.

DESCRIPTION OF THE DRAWINGS

Figure 1 shows a perspective stripping of a piston for shock absorbers effected in accordance with the present invention.

Figure 2 shows an axial view of the piston itself, on the side of compression thereof, i.e.-, on the base thereof opposed to that shown in figure 1.

Figure 3 finally shows a sectional view of the same piston represented in the preceding figure, pursuant to cut-line A-B of said figure.

PREFERRED EMBOD M NT OF THE INVENTION In view of these figures and more specifically figure 1, it may be observed that the piston for shock absorbers which is described herein is comprised by piston 1 itself, with the corresponding axial aperture 2 thereof, for the coupling of rod 3 of the shock absorber, against the metallic top 4, aided by resilient top 5, and with the 4.- co-operation of nut 6. washers 7 being established between piston 2 and top 4 in contact with the piston and a deflector 8 which leans on top 4, with the co-operation of a washer 9, whereas washers V, deflector 8' and washer 9' are established between piston 1 and nut 6.

The piston itself is 'further provided, as is usual, with the conventional alignment of apertures or bores 10, which form a circumferential alignment which is coaxial with central aperture 2 itself.

From this basic structure, one of the features of the invention is centred on the f act that washers 7 and V, which are adapted to the two faces of piston 1 itself, are blind washers, i.e., they lack bores opposed to bores 10 of the piston, the f low of liquid being regulated f or each case through said piston in accordance with the requirements f or each case and for a similar piston 1, by means of the use of washers 7-7' having different diameters which obturate the mouths of such bores 10 to a greater or lesser extent depending on the diameter thereof, thereby determining the operative surface of the latter.

In accordance with a further characteristic of the invention, recesses 11 are established on the peripheral zone of the two faces of piston 1 itself, specifically on the marginal zone thereof which lies between bores 10 and the free edge thereof, which recesses determine high-relief borders 12 for the mouths of apertures or bores 10 of the piston, such that following the resilient deformation of washers 7 and when the abrupt recovery thereof takes place, same strike the piston through the minimum surfaces, those determined by said borders 12, a substantial deadening thus being achieved in the sound effects of conventional shock absorbers of this type.

These high-relief borders 12, as may be observed in figure 2, define an external edge hich perimetrally runs along the face of the piston shown in said figure, with a sinuous line, which is C 5.- interrupted between each pair of apertures 10 by means of radial branches 13, which extend towards the imaginary rim linking the side wall of the piston and which likewise afford a minimum surface, at the same time as said high-relief borders 12 are interrupted in correspondence with certain apertures of the piston, specifically those numbered 10', wherein said interruption determines side or radial apertures 14 for the outlet of the liquid. which allow said outlet to take place when washers having a diameter which totally covers the mouths of basic apertures 10 are used.

Thanks to the structure described, on the one hand an outstanding simplication of costs is obtained, as same allows the use of blind and conventional washers, selected depending on the diameter thereof and not depending on the holes established therein, which, on the other hand affords a total automation of the assembly, as a specific positioning of said washers is not required with respect to the piston itself, guide or centering elements thus being unnecessary.

However, the regulation of the flow through the piston may be fully gauged, by means of variations in the diameter of the washers, with the smallest necessary magnitude, and finally, as has just been stated, the noise problems in the striking of washers 7-7' on piston itself 1, in the resilient recovery thereof, are solved.

Claims

C L A I M

S 6, A piston for a telescopic shock absorber and including a circumferential array of apertures for the passage of fluid from one side of the piston to the other, wherein at least one recess is provided in the marginal space between said apertures and the edge of the piston on at least one side of the said piston, said recess being contiguous with one or more of said apertures to define an enlarged aperture mouth.
2. A piston according to Claim 1 having a symmetrical array of apertures, a plurality of said apertures having a corresponding contiguous marginal recess.
3. A piston according to Claim 1 or Claim 2 having at least one marginal recess on each side of the piston.

A piston according to any preceding Claim and including a further recess in said marginal space, said recess being non-contiguous with an adjacent aperture and thereby defining a relatively narrow lip over part of the mouth to said aperture.

A piston for telescopic shock absorber substantially as described herein with reference to the drawings.

1 7.- 6 - Piston f or shock absorbers, of the type wherein the piston itself forms part of a gasket which may be fixed to the corresponding end of the rod of the shock absorber, together with a series of deflector washers and the corresponding securing nut, and wherein the piston itself, besides the axial aperture thereof to couple same to the rod, is provided with a perimetral alignment of duly calibrated apertures or bores, essentially characterized in that the said piston itself, at least on one of the faces thereof and in the marginal zone established between the mouths of the operative apertures or bores thereof and the edges thereof, is provided with recesses which determine surrounding borders f or such apertures, which mouths are theref ore provided in high-relief, thereby minimizing the striking surface of the resilient washers on said piston, in the recovery thereof, and the noises generated by the hammering between f lat surfaces being eliminated, it having been foreseen that such borders define along the periphery of the base of the piston and outside the the apertures thereof, a sinuous line which is interrupted between each pair of adjacent apertures, by means of a radial branch which extends up to the rim linking the side surface of the piston and which likewise affords a minimum surface, with the particularity that said borders are interrupted in correspondence with certain apertures of the piston, for which is established a side or radial aperture for the outlet of liquid, framed by a pair of radial branches as those cited, it furthermore having been foreseen that blind washers with a variable diameter and which may be selected in accordance with such diameter participate with said piston itself in order to obtain different levels of partial obturation in such apertures, which washers may totally obturate the basic apertures of the piston, with the exception of those provided with radial apertures.

Published 1988 at The Paten', Of-fice. State House. 66 71 High Holborn, London WC1R 4TP. Further copies may be obtained from The Patent Office, Sales Branch. St MarT Cray. Orpington, Kent BR5 3RD. Printed by Multiplex techniques hd, St Mary Cray. Kent. Con 157.