GB2171471A

GB2171471A - Dynamic sealing rings

Info

Publication number: GB2171471A
Application number: GB08600877A
Authority: GB
Inventors: Francisco Sala Fernandez
Original assignee: ITW Espana SA
Current assignee: ITW Espana SA
Priority date: 1985-01-24
Filing date: 1986-01-15
Publication date: 1986-08-28
Also published as: GB8600877D0; SE8600147L; ES284130Y; SE8600147D0; DE3601718A1; IT8619170A0; ES284130U; GB2171471B; FR2576384A1; IT1188306B; IT8620599V0

Abstract

A dynamic sealing ring, for installation between a fixed element and a movable element of a shock absorber, for example, comprises a single-part body defining an inner cylindrical crown 1 and an outer cylindrical crown 2 which are joined by a portion 3 of semicircumferential profile, the inner crown 1 being longer in the axial direction than the outer crown 2, and either the inner crown 1 or the outer crown 2 or both being assisted by a respective circular spring, the spring 4 on the inner crown 1 providing compression directed radially inwards and the spring 5 on the outer crown 2 providing expansion directed radially outwards, for maintaining the required sealing properties in spite of any wear or irregularities. <IMAGE>

Description

SPECIFICATION Dynamic sealing rings This invention relates to dynamic sealing rings designed to be installed between two elements intended to move with respect to one another.

The sealing rings are specially applicable to shock absorbers, such as, for example, a shock absorber for absorbing vibrations between one fixed and one movable element, in which a sealing effect must be produced between two chambers defined within the shock absorber.

The main problem which affects a sealing ring in this type of shock absorber lies in the fact that, due to the relative mobility between the parts to be sealed and the stresses to which it is subjected, together with the nature of the actual material comprising the ring, gradual wear is produced which after a relatively short time makes the ring inoperative, since this wear causes maladjustments between the ring and the parts with which it is associated.

An aim of this invention has been to tackle the above-noted problem in the hope of ensuring perfect sealing, lasting a considerable length of time, which is not affected by any wear suffered by the material of which the ring is made, nor by possible irregularities, either in the ring itself or in the bodies or parts connected with it.

In accordance with the present invention, a dynamic sealing ring, for installation between two elements intended to move with respect to one another, comprises a single-part body defining an inner cylindrical crown and an outer cylindrical crown which are joined by a portion of semicircumferential profile, with the inner crown having a longer axial dimension than the outer crown.

The inner crown is dimensioned to fit tightly with a shank or shaft against which the sealing is wished to be made, both with respect to axial thrust and linear dynamics. The outer crown is dimensioned to fit tightly with the inner wall of a cylinder or chamber liner to which in turn the sealing ring has to be adapted, to form the fluidtightness or airtightness sought.

To complete the structure disclosed, it has been foreseen that, surrounding the inner crown, a circular spring is fixed which works under compression, clamping the inner crown against the shaft or shank so that said spring gradually grips the ring tighter, as it is worn through friction against the shaft or shank, thus compensating for this wear.

On the other hand, the outer crown is also assisted by a circular spring, in this case adapted to its inner surface, which works under expansion, with the same aim as above, i.e. of projecting the outer crown radially against the inner surface of the liner of the cylinder or chamber concerned, and counteracting the effect of wear produced by friction of the ring against the cylinder or chamber.

From the construction disclosed, it is obvious that in cases in which the relative mobility between the ring and the shank/shaft or the cylinder/chamber only affects one of these elements, the spring corresponding to the fixed element may be eliminated.

In this connection, let us take as an example a shock-absorber in which the dynamic sealing ring remains in a stable position with respect to a cylinder, with a shank sliding within the inner crown. Obviously, in this case, wear will only be produced in the inner crown, so the spring mentioned above for the outer crown will be unnecessary. It is also obvious that in the opposite case, it will be the spring which assists the inner crown which will be unnecessary.

In any event, a joint is obtained which, in its specific practical application of dynamic sealing, helps to ensure that the required airtightness is maintained in time, with regard to possible wear suffered in its normal working.

Preferably: the outer crown is formed on its inner surface with an inwardly directed shoulder for helping to retain the associated circular spring on said inner surface; the inner crown is formed on its outer surface with an outwardly directed shoulder for helping to retain the associated circular spring on said outer surface; the circular spring associated with the inner crown is located on a portion of the outer surface of the inner crown which is not overlapped by the outer crown; the portion of semicircumferential profile is semitoroidal; and the portion of semicircumferential profile has a thickness in the axial direction which is greater than the thickness in the radial direction of either the inner crown or the outer crown.

A dynamic sealing ring, in accordance with the present invention, will now be described, by way of example only, with reference to the accompanying drawing, which shows an axial cross-section through the dynamic sealing ring.

It can be seen that the dynamic sealing ring comprises a singe-part body made of suitable material, in which an inner cylindrical crown 1 is defined, and a shorter outer cylindrical crown 2, the inner diameter of the inner crown 1 coinciding dimensionally with a shaft or shank to which it is to be fitted, while the outer crown 2 has an outer diameter in keeping with that of a chamber or cylinder liner which is going to be inter-related therewith, these two crowns 1 and 2 being connected to each other through a semicircumferentially profiled portion 3.

The inner crown 1 may be assisted by an encasing circular spring 4, which works under compression, tending to confine the said crown 1 against the shaft or shank so that, as we have already said, with a view to possible wear by the normal sliding of the shaft or shank inside it, this wear is absorbed, and the sealing sought is maintained.

Similarly, when necessary, as the case may be, the outer crown 2 will be assisted by a second circular spring 5, similar to the previous spring 4, but adapted in this case to the inner surface of the outer crown 2, such that the circular spring 5 works under expansion and expands the said crown 2 radially in orderto achieve perfect adaptation against the chamber or cylinder liner, and, consequently, absorbs possible wear or irregularities which may be caused in it during its normal use.

To complete the structure disclosed, it is possible to make shoulders, like that shown on the inner crown 1 and marked with reference number 6, intended to retain the respective spring 4 or 5 axially.

Claims

1. A dynamic sealing ring, for installation between two elements intended to move with respect to one another, comprising a singlepart body defining an inner cylindrical crown and an outer cylindrical crown which are joined by a portion of semicircumferential profile, with the inner crown having a longer axial dimension than the outer crown.

2. A dynamic sealing ring according to claim 1, in which the outer crown is assisted on its inner surface by a circular spring which works under expansion, said expansion being directed radially outwards.

3. A dynamic sealing ring according to claim 1, in which the inner crown is assisted on its outer surface by a circular spring which works under compression, said compression being directed radially inwards.

4. A dynamic sealing ring according to claim 1, in which the inner crown is assisted on its outer surface by a circular spring which works under compression, said compression being directed radially inwards, and the outer crown is assisted on its inner surface by a circular spring which works under expansion, said expansion being directed radially outwards.

5. A dynamic sealing ring according to claim 2 or claim 4, in which the outer crown is formed on its inner surface with an inwardly directed shoulder for helping to retain the associated circular spring on said inner surface.

6. A dynamic sealing ring according to any one of claims 3 to 5, in which the inner crown is formed on its outer surface with an outwardly directed shoulder for helping to retain the associated circular spring on said outer surface.

7. A dynamic sealing ring according to any one of claims 3 to 6, in which the circular spring associated with the inner crown is located on a portion of the outer surface of the inner crown which is not overlapped by the outer crown.

8. A dynamic sealing ring according to any preceding claim, in which the portion of semicircumferential profile is semitoroidal.

9 A dynamic sealing ring according to any preceding claim, in which the portion of semicircumferential profile has a thickness in the axial direction which is greater than the thickness in the radial direction of either the inner crown or the outer crown.

10. A dynamic sealing ring substantially as hereinbefore described with reference to the accompanying drawing.

11. A dynamic sealing ring according to any preceding claim when forming part of a shock absorber.