GB2083873A

GB2083873A - Sealing rings

Info

Publication number: GB2083873A
Application number: GB8127675A
Authority: GB
Original assignee: Carl Freudenberg KG
Current assignee: Carl Freudenberg KG
Priority date: 1980-09-15
Filing date: 1981-09-14
Publication date: 1982-03-31
Also published as: DE3034692C2; SE448907B; FR2490309A1; SE8103911L; GB2083873B; DE3034692A1; FR2490309B1

Abstract

A sealing ring, consists of a support ring 5 and a lipped ring 6 forming a complete unit which can be mounted as a press-fit in a recess in a housing 4, the support ring 5 being of generally channel-shaped profile, with one of the two sealing lips 7 and 8 of the lipped ring 6 resting on an axially extending part of the support ring 5, the other sealing lip sealing against a shaft 3, and a flange of the support ring 5 intended to face higher pressure side 1 comprising a circumferential protrusion 10 resting on the lipped ring 6 radially between the two sealing lips 7 and 8. The space within the protrusion is pressure equalised through an opening 9. <IMAGE>

Description

SPECIFICATION Sealing rings The invention relates to sealing rings of the kind consisting of a lipped ring of an elastomeric material having a pair of radially-spaced sealing lips, and of a support ring associated with the lipped ring for firmly mounting the lipped ring in place, for example in a cylinder or on a piston.

Sealing rings of the above-mentioned kind are used especially in power hydraulics where working pressures of up to 400 bars occur and considerable mechanical demands must be satisfied.

Ordinarily for sealing such pressures, a lipped ring is used which comprises, on the side facing the higher pressure, two sealing lips separated from one another by a deep groove, and which is inserted into an annular recess of angular profile having an opening, on the side facing the higher pressure, which is closed by a specially adapted support ring. The production and fitting of such sealing rings is expensive because of the configurations both of the special support ring and of the grooved lipped ring.

Accordingly the invention is based upon the problem of developing a sealing ring which has comparable properties in use with known sealing rings but which can be produced at more favourable cost.

In accordance with the invention, in a sealing ring of the initially stated kind the support ring is of generally channel-shaped profile, comprising an axially extending part and a flange at each end thereof, with one of the sealing lips of the lipped ring resting on the axially extending part of the support ring, and that flange of the support ring intended to face the higher pressure comprising a circumferential protrusion resting on the lipped ring radially between the two sealing lips.

The sealing ring of the invention forms an inherently complete installation unit which without the need for the use of secondary securing means is held reliably in a suitably shaped recess.

This securing of the sealing ring in the recess is achievable merely as a press fit. The dimensional tolerances to be used for a press fit have long been familiar. However they have not hitherto been used in connection with a sealing ring for withstanding extremely high pressures.

The lipped ring may, at an end thereof intended to be remote from the higher pressure, be carried completely by the adjacent flange of the support ring. Indeed, the lipped ring is preferably defined in the axial direction by end faces extending in the radial direction. Accordingly it can be obtained at favourable cost from a tubular or even flat material. The surfaces which inwardly and outwardly define the lipped ring in the radial direction may have a constantly reducing distance apart in the direction intended to be away from the higher pressure. In accordance therewith, the sealing lips are formed as the external and internal circumferences of the larger diameter end face of the lipped ring.The clearance angle should amount to 20 to 4 on the dynamically acting sealing lips and 0.50 to 20 on the statically acting sealing lip resting on the axially extending part of the support ring.

The protrusion of the support ring lies on the end face of the lipped ring facing the higher pressure at a position between the two sealing lips. The zone of contact of the protrusion should lie approximately in the middle between the two sealing lips. Asymmetrical deformations of the profile of the lipped ring are thus avoided thereby having a positive effect upon the vibration behaviour and other mechanical properties in use.

It has been found that special pressing of the protrusion against the end face of the lipped ring is not necessary.

According to one special development, it is provided that the flange of the support ring intended to be remote from the higher pressure extends from one machine part into the immediate vicinity of the relatively moved machine part, i.e.

extends almost as far as that sealing lip of the lipped ring remote from the axially extending part of the support ring, this measure especially preventing the forcing out of some of the lipped ring in the sealing of highest pressures.

The support ring of the sealing ring may be formed of sheet metal, perferably of a sheet steel, and the protrusion may be formed by the end of that flange of the support ring intended to face the higher pressure. It is especially advantageous if the protrusion is a rolling-in of that flange of the support ring intended to face the higher pressure, all round, which is produced by the application of a known mechanical deformation method.

An annular cavity enclosed by the lipped ring and the support ring, in the region of the protrusion, can be connected with the higher pressure by an opening through the support ring.

The opening should have only a very small diameter, for example between 0.3 and 1 mm. In a special manner it favours the uniform sealing behaviour of the proposed sealing ring.

Two sealing rings in accordance with the present invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 shows a sealing ring in half-sectional representation in use mounted in a cylinder; and Figure 2 shows a sealing ring in half-sectional representation in use mounted on a piston rod.

The sealing ring shown in Figure 1 consists of a support ring 5 and a lipped ring 6 inserted in an angular recess of a housing 4. The lipped ring 6 rests with a statically acting sealing lip 7 against the inside of the support ring 5 and with a dynamically acting sealing lip 8 on the surface of a cylindrical shaft 3. The higher pressure side is designated by 1, the lower pressure side buy 2.

The support ring 5 consists of deep-drawn sheet steel. It has a generally channel-shaped profile, the opening of which is directed inwards.

An end face of the lipped ring 6 remote from the pressure side 1 is supported over its full area by an adjacent flange of the support ring 5 extending in the radial direction. Another flange of the support ring 5, facing the pressure side 1, is rolled inwards to form, all round, a protrusion 10 which lies on the adjacent end face of the lipped ring 6 between the two sealing lips 7 and 8. The free end of the protrusion 10 is rounded off to avoid damage to the lipped ring 6 of rubber elastic material. An annular cavity, enclosed by the lipped ring and the support ring in the region of the protrusion, is connected with the pressure side 1 by a relief bore 9 having a diameter of 0.2 mm. The cavity is accordingly completely filled with the same medium as that on the pressure side 1.

Under operational conditions, however, substantial quantities of fluid do not pass through the opening 9, and therefore there is no fear of blockage.

Figure 2 refers to an embodiment for the sealing of part of a piston 1 7. The inner diameter of a support ring 12 is only slightly larger than the outer diameter of the angular recess of a piston 1 7. After forceful pressing in, a firmly adhering connection occurs between the two parts, which cannot be disengaged by the forces occurring by reason of operation.

In this case, again, the support ring 12 consists of deep-drawn sheet steel, and is of equivalent (mirror-image) profile to the above-described support ring 5. A lipped ring 13 is sealed off by a statically acting seal lip 14 in relation to the support ring 12, and by a dynamically acting seal lip 1 5 in relation to a relatively movable cylinder wall 11, a circumferential protrusion 1 6 resting on the lipped ring 1 3 radialiy between the two sealing lips 14 and 1 5.

Claims

1. A sealing ring consisting of a lipped ring of an elastomeric material having a pair of radially spaced sealing lips, and of a support ring associated with the lipped ring for firmly mounting the lipped ring in place, the support ring being of generally channel-shaped profile, comprising an axially extending part and a flange at each end thereof, with one of the sealing lips of the lipped ring resting on the axially extending part of the support ring, and that flange of the support ring intended to face the higher pressure comprising a circumferential protrusion resting on the lipped ring radially between the two sealing lips.

2. A sealing ring according to claim 1, in which the lipped ring is defined in the axial direction by end faces extending in the radial direction.

3. A sealing ring according to claim 1 or claim 2, in which that flange of the support ring intended to be remote from the higher pressure extends almost as far as that sealing lip of the lipped ring remote from the axially extending part of the support ring.

4. A sealing ring according to any one of claims 1 to 3, in which the support ring is formed of sheet metal and the protrusion is formed by the end of that flange of the support ring intended to face the higher pressure.

5. A sealing ring according to claim 4, in which the protrusion is a circumferential rolling-in of that flange of the support ring intended to face the higher pressure.

6. A sealing ring according to any one of claims 1 to 5, in which an annular cavity enclosed by the lipped ring and the support ring, in the region of the protrusion, is connectable with the higher pressure by an opening through the support ring.

7. A sealing ring according to claim 1 and substantially as hereinbefore described with reference to Figure or Figure 2 of the accompanying drawings.

8. A sealing ring according to any preceding claim when mounted in a cylinder or on a piston and respectively sealing with the piston or the cylinder.