GB2028933A

GB2028933A - Shaft Sealing Rings

Info

Publication number: GB2028933A
Application number: GB7929272A
Authority: GB
Original assignee: Carl Freudenberg KG
Current assignee: Carl Freudenberg KG
Priority date: 1978-08-25
Filing date: 1979-08-22
Publication date: 1980-03-12
Also published as: SE7907055L; BR7905399A; JPS5530583A; IT7950107A0; IT7949399A0; BE878343A; IT1120539B; FR2434318A1

Abstract

A shaft sealing ring, comprising a supporting ring 1 of metal, which has an angle-shaped cross section, and an annular sealing lip 5, which is connected permanently, by an intermediate portion 3 of membrane- like form, with the inwardly-extending limb 4 of the supporting ring. The inwardly-extending limb of the supporting ring carries a generally axial, tapered extension 2, which reaches into the intermediate portion 3, the axial extent of the extension within the intermediate portion being between 50% and 80% of the axial extent of the intermediate portion. <IMAGE>

Description

SPECIFICATION Shaft Sealing Rings The invention relates to shaft sealing rings, comprising a supporting ring of metal, which has an angle-shaped cross-section, and of an annular sealing lip, which is connected permanently, by an intermediate portion of membrane-like form, with the inwardly-extending limb of the supporting ring.

Shaft sealing rings of this kind are known frm German DAS 1,007,130. The contact force thereby obtained of the sealing lip on the shaft to be sealed is on the one hand dependent on the elastic properties of the materials employed; and on the other hand on the relative dimensional exactness of the measurements of the lip and of an annular coil spring arranged on its outside.

In particular, in the manufacture of very large quantities, the combined variations of these three parameters can in individual rings lead to contact forces at the lip which lie outside permissible values. For cases of use-with exact requirements, therefore, an individual checking of each completed shaft sealing ring is necessary.

The object underlying the invention is to develop a shaft seaiing ring with comparable properties in use, which is cheaper in manufacture, andwhich in mass production-has a greater uniformity in the characteristics of each unit.

The object is, according to the invention, solved by a shaft sealing ring of the kind mentioned initially, in which the inwardlyextending limb of the supporting ring carries generally axial extension, which reaches into the intermediate portion, the axial extent of the extension within the intermediate portion being between 50% and 80% of the axial extent of the intermediate portion.

The supporting ring consists preferably of deep-drawn sheet steel, and the deep drawing process employed for its manufacture makes possible simultaneously with the general deformation the formation of the generally axial extension which is the essence of the invention.

The manufacture of the supporting ring does not fundamentally involve additional costs as compared with conventional constructions.

A significant accumulation of resilient material in the neighbourhood of the sealing lip is not necessary, but in comparison with conventional sealing rings significant savings are indeed possible with respect to the necessary resilient material.

For improvement of the resilient properties of the generally axial extension, provision is preferably made that the extension decreases in thickness away from the inwardly-extending limb of the supporting ring. According to another advantageous construction provision is made that the extension is divided into individual segments by cuts distributed uniformly around the circumference. If necessary, in conjunction with or independently of the previously described decrease in thickness of the extension, especially good results are frequently obtained- if the segments in the projecting part are tapered in width. A particularly favourable average width of the individual segments amounts to 2 to 10 mm.

The resiliently elastic behaviour of the extension, in the radial direction, is also influenced to a significant extent by the angle at which the extension is arranged with relation to the axis of the ring. Particularly advantageous are angles between 15 and 400, especially in the order of 250. Angles of 0 or negative angles have on the contrary in individual cases had an adverse effect on the vibratory behaviour of the sealing lip in operation and hence on the dynamic sealing.

The accompanying drawing shows by way of example one construction of a shaft sealing ring according to the invention. In these drawings:- Figure 1 is a perspective view of the ring on a shaft, with part of the ring broken away; and Figure 2-isa radial section of the ring.

The sealing ring comprises a supporting ring 1 of metal with'an angle-shaped cross-section. An annular sealing lip 5 of elastomeric material is connected by in intermediate portion 3 of membrane-like form with the inwardly extending limb 4 of the supporting ring 1. In fact the elastomeric material is moulded around the inwardly extending limb 4.

The sealing lip 5 cooperates with a rotating shaft 7.

The inwardly-extending limb 4 carries a generally axial extension 2, which reaches into the intermediate portion 3. In Figure 2, the axial extent of the extension 2 is indicated as x1, while the axial extent of the intermediate portion 3 is indicated as x2.

One example of a shaft sealing ring according to the invention, with proportions somewhat different from those shown in the accompanying drawings, is as follows:- Nominal diameter of shaft to be sealed: 45 mm.

Material of supporting ring: steel sheet 1 mm thick of a deep-drawing quality with a tensile strength of 350 N/mm2.

Material of sealing lip and intermediate portion: resilient rubber material with a hardness of 65-85 Shore A, directly vulcanised onto the supporting ring.

The axial extent of the extension within the intermediate portion is 60% of the axial extent of the intermediate portion. The extension is uniformly divided around the entire circumference by V-shaped gaps into segments having a width of 4 mm where they join the inwardly-extending limb.

The resilient contact force of the sealing lip on the surface ofthe shaft to be sealed is determined in particular by the-material properties and by the dimensions of the extension 2 and of the sealing lip 5. Both parameters can without special difficulties be very exactly checked and ensured in continuous production.

The properties in use of the shaft sealing rings according to the invention correspond with those of known constructions. The particular advantages consist, along with a significantly simplified possibility of manufacture, in a significantly improved uniformity as regards the properties of the individual units in comparison with one another.

Claims

Claims

1. Shaft sealing ring, comprising a supporting ring of metal, which has an angle-shaped crosssection, and an annular sealing lip, which is connected permanently, by an intermediate portion of membrane-like form, with the inwardlyextending limb of the supporting ring, characterised in that the inwardly-extending limb of the supporting ring carries a generally axial extension. which reaches into the intermediate portion, the axial extent of the extension within the intermediate portion being between 50% and 80% of the axial extent of the intermediate portion.

2. Shaft sealing ring according to Claim 1, characterised in that the extension decreases in thickness away from the inwardly-extending limb of the supporting ring.

3. Shaft sealing ring according to Claim 1 or Claim 2, characterised in that the internal surface of the extension makes an angle of 15O to 400 with the axis of the ring.

4. Shaft sealing ring according to any of Claims 1 to 3, characterised in that the extension is divided into individual segments by cuts distributed uniformly around the circumference.

5. Shaft sealing ring according to Claim 4, characterised in that the individual segments have a lesser width near the terminal edge of the extension than near the inwardly-extending limb of the supporting ring.

6. Shaft sealing ring according to Claim 4 or Claim 5, characterised in that the individual segments have an average width of 2 to 10 mm.

New Claims or Amendments to Claims filed on 12 Dec. 79.

Superseded Claim 1.

New or Amended Claim:

1. Shaft sealing ring, comprising a supporting ring of metal, which has an angle-shaped crosssection, and an annular sealing lip, which is connected permanently, by an intermediate portion of membrane-like form, with the inwardiyextending limb of the supporting ring, characterised in that the inwardly-extending limb of the supporting ring carries a generally axial extension, which reaches into the intermediate portion, the axial extent of the extension within the intermediate portion being between 50% and 80% of the axial extent of the intermediate portion, and the resilient contact force of the sealing lip on a shaft when in use being determined by the material properties and by the dimensions of the extension and of the sealing lip, without the presence of any other spring.