GB2336187A

GB2336187A - Sealing Element

Info

Publication number: GB2336187A
Application number: GB9906413A
Authority: GB
Inventors: Otto Baumann; Ulrich Bohne
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1998-03-19
Filing date: 1999-03-19
Publication date: 1999-10-13
Anticipated expiration: 2019-03-19
Also published as: GB2336187B; GB9906413D0; DE19812041A1

Abstract

The invention relates to a sealing element for sealing off two coaxial sealing faces which are capable of axial displacement in relation to one another, particularly for sealing off a cylindrical face of a piston 18 in relation to the face of a hollow cylinder 20. The said sealing element 1 has an inner sealing lip 14 and an outer sealing lip 16 and a means for elastically bracing at least one of the sealing lips 14/16 against at least one of the sealing faces. The elastic means is made up from at least one lamella 2 which is disposed substantially radially between the inner sealing lip 14 and the outer sealing lip 16. The lamellae 2 (4, 6, 8, 10, 12 not shown) can be disposed at a distance from one another or symmetrically in the peripheral direction and can be moulded into the sealing element 1. The lamellae 2(4, 6, 8, 10, 12 not shown) can also be a configured in a variety of different cross-sections and be made from either plastic or metal.

Description

2336187 1 Sealing element The invention relates to a sealing element havmg

the features mentioned mi the pre-characterismig clause of claim 1.

Prior art

It is known practice for faces, for exwnple metal faces, which are capable of displacement or torsion in relation to one another to be sealed off by means of scaling elements against loss of pressure or fluid and/or against the penetration of dirt. Thus, the sealing faces of hydraulic cylinders and pistons are usually sealed off by means of grooved ring or bevelled-edge ring seals or sleeves.

Shaft-sealing rings or retaining rings are also known which have a sealing lip and an annularly closed tension spring for pressmig the sealing lip against an inner sealing face, in order to achieve a better sealing action.

A sealing element 'm the form of a commercially available shaft-sealmig ring and an offset annular or helical spring is also known, mi which radial pre-tensionmig of an inner and an outer seafingIp against mutually opposed sealing faces is produced by the offsetting of the spring.

Disadvantages of the known sealing elements are either the deficient sealing action under the influence of a high static pressure on the sealing lip or the relatively elaborate, and consequently expensive mode of construction of the offset annular spring.

Advantages of the invention 2 The sealing element according to the mivention, which is intended particularly for sealmig off a piston in relation to a cylinder and has the features mentioned mi claim 1, 'm particular at least two lamellae which are disposed substantially perpendicularly or at a slight inclination between an ffiner and an outer seal mig lip, has the advantage of an outstanding sealmig action, both agamist pressure loss and also against the passage of contarnmiants, because of a pre-tensionmig action resulting from simple and effective bracing between the ffiner and outer sealmig lips. Furthermore, sealmig elements of this kind can be simply and inexpensively manufactured by mouldmig the lamellae, for example into an elastomer, or by a mouldffig process using a homogeneous material for the sealing element and the lamellae 'm a small number of production steps.

The lamellae may preferably have a planar and thin cross-section and may, 'm advantageous manner, be disposed perpendicularly between the sealing lips. In this case, they achieve their pre-tensionffig action by slight buckIffig when the sealing element is installed, as a consequence of an overdimension, for which provision is made design-wise, in relation to an interval between the faces to be sealed off. However. preference is also given to plano-concave or biconcave cross-sections, a fact which u'nparts m'creased stiffness to the lamellae. This situation is particularly advantageous Mi the case of very close tolerances between the surfaces to be sealed, because here the pre-tensioning has to be applied almost exclusively by the elastic properties of the material of the sealmig element.

The sealing element may advantageously be produced from elastomenic material, and the lamellae from an elastic plastic or from a sheet of spring steel, for example. However, the lamellae are preferably made of the same material as the sealing element and connected to the latter in one piece. It is also preferable if at least two axially spaced-apart rows of lamellae are moulded into the sealing 3 element, as a result of which a uniform sealing action can be achieved 'm both directions of axial displacement of the sealig faces, particularly of a piston and cylinder, in relation to one another. Fitting of the sealmig elements may take place in the piston andlor mi the cylinder, preferably in a groove so that the smallest possible gap width between the piston and cylinder can be achieved.

Preference is also given to use as a shaft-sealing ring, in which case offsetting of the lamellae 'm a manner deviating from the radial is advantageous. Under these circumstances, offsetting of the lamellae may ninprove the sealing action 'm advantageous manner in dependence upon a direction of rotation of at least one of the sealing faces. In addition, a spring characteristic, that is to say a stiffness between the inner and outer sealing lips, can be influenced 'm a simple manner, design-wise, by offsetting the lamellae in this way.

Other preferred refinements of the invention emerge from the remaining features which are mentioned 'm the subclaims.

Drawmgs The invention will be explained in greater detail below 'm exemplified embodiments with the aid of the appertaining drawings, in which:

Figure 1 shows a diagrammatic plan view of a sealing element.

Figure 2a shows a sectional view of a sealing element in a first form of embodiment; Figure 2b shows a sectional view, 'm detail form, of the sealing element 4 corresponding to figure 2a; Figure 2c shows a sectional view, 'm detail form, of a sealig element 'm another form of embodiment; Figure 3a shows a plan view, mi detail form, of a sealing element with radially disposed plane lamellae; Figure 3b shows a plan view, 'm detail form, of a sealing element with radial, biconcave lamellae; Figure 31c shows a plan view, 'm detail form, of a sealing element with offset lamellae, Figure 3d shows a plan view, 'm detail form, of a sealing element with curved lamellae, and Figure 3e shows another plan view, in detail form, of a sealmig element with a variable lamella cross-section.

Descniption of the exemplified embodiments Figure 1 shows, Mi a diagrammatic plan view, a sealing element 1 which has miner and outer sealing lips 14 and 16 disposed concentrically with one another, and is such as can be used, for example, for sealing off a piston 18 in relation to a cylinder 20. It is possible to discern a multiplicity of flat, disc-shaped lamellae 2 disposed 'm a uniformly star- shaped manner, which are mi each case disposed perpendicularly to the inner and outer sealing lips 14 and 16 respectively. These lamellae 2 are intended to ensure pre-tensioning of the inner and outer sealing lips against the piston 18 and against the cylinder 20 respectively.

Figure 2a shows a longitudinal section through the sealing element 1 in a first form of embodiment, with the lamellae 2 moulded into the said element. In the exemplified embodiment shown, the flat lamellae 2 possess a trapezoidal contour whose short basal side faces towards a closed side of the sealing element 1. However other contours, for example rectangular or semicircular ones, are also possible. A long basal side of the trapezium faces towards an open side of the sealing element 1 so that, mi the untensioned condition, the inner sealing lip 14 is pressed against the piston 18, and the outer seal mig lip 16 against the cylinder 20. When the sealing element 1 is inserted, the lamellae 2 are slightly deformed or buckled in each case, so that they have a slight curvature mi the installed condition. Because of the closed and open sides of the sealmig element 1, the latter possesses a U-shaped annular cross-section.

Figure 2b shows a detail B of the scaling element 1, in a manner corresponding with the sectional view in figure 2a, in which detail it can be seen how the inner sealing lip 14 and the outer sealing bp 16 are pre-tensioned radially inwards and outwards respectively when in the untensioned condition (not the installed condition). As a result of this, it is possible to ensule contact pressure against the walls of the piston 18 and of the cylinder 20, and thereby a pressure-tight connection.

Figure 2c shows, in another detail B, an alternative form of embodiment of the sealing element 1, with trapezoidal lamellae 12 which are disposed mi a two-sided or symmetrical manner and are separated by a circumferential annular web 24 between the inner sealing lip 14 and the outer sealing lip 16. The seal mig element 6 1 is open towards both sides and therefore has an H-shaped contour. In tile untensioned condition, the trapezoidal contour of the lamellae 12 results mi a slightly V-shaped contour of the inner sealmig lip 14 and outer sealing lip 16 'm each case which, Mi the installed condition, ensures uniform contact pressure by both edges of the sealmig element 1 agamist the walls of the piston 18 and also of the cylinder 20. As a result of this, a constant sealing action, both against loss of pressure and against penetration by dirt, can be achieved in both directions, that is to say particularly during relative axial movements of the piston 18 and cylinder 20.

In five detail views A corresponding to figure 1, figures 3 a to 3e show a number of possible forms of embodiment or arrangements of lamellae 2, 4, 6, 8 and 10 'm the sealmig element 1. Under these circumstances, the sealing element 1 may, in each case, be open on one side 'm a manner corresponding to figure 2b, or open on two sides in a manner correspondmig to figure 2c. The same parts as in the precedmig figures are provided with the same reference symbols and are not explamied again. The lamellae may be disposed so as to be either radial (figures 3a and 3b) or inclined (figure 3c), curved (figure 3d) or variable in some other way (figure 33e).

In a first detail view A corresponding to figure 1, figure 3a shows a plan view of the sealmig element 1 with lamellae 2 which are disposed radially between the inner and outer sealing lips 14 and 16 respectively, and have a uniform thickness at every point.

In another detail view A corresponding to figure 1, figure 3b shows a plan view of the sealing element 1 with lamellae 4 which are likewise disposed radially between the inner sealing lip 14 and outer sealmig lip 16, but which are not plane 7 and therefore relatively low in flexural strength, but have a biconcave contour which u'nparts a considerably higher degree of stiffness to them.

A concave or biconcave contour of this kind for the lamellae 4 is therefore particularly suitable for sealing-off purposes, with minimal fitting tolerances, between the piston 18 and cylinder 20, since the lamellae permit almost no deformation, but adaptation to the sealing surfaces has to take place exclusively by way of deformation or compression of the slightly elastic material of the sealing element. With suitable dimensionmig of the concave lamellae 4, a sealmig element 1 of this kind may also have similar stiffness to that of a sealmig element with plane lamellae (corresponding to figure 3a). For this purpose, it is expedient to select the thickness of the lamellae 4 at their edge mi a manner corresponding to the uniform thickness of the lamellae 2.

In another detail view A, figure 3c shows a lamella 4 which is disposed in an offset manner, and is disposed, not radially but obliquely, between 'die inner sealing lip 14 and outer sealing bp 16. In the case of this arrangement, adaptation or pressmg-M takes place, in the installed condition, not by buckling of the lamellae 4 but substantially by additional staggering, that is to say by varying an angle of staggering a between the inner or outer sealing lip 14, 16 and the surface of the lamellae 4.

In another detail view A, figure 3d shows a lamella 8 which is disposed in a curved manner and is once again disposed radially between the inner sealing lip 14 and outer seal Mig lip 16. In this case, the contour of the lamellae 8 has an Sshaped course, which can bring about very high flexibility and elasticity if sufficiently thin lamellae 8 are used. Adaptation of the sealing element 1 to the surfaces of the piston 18 and cylinder 20 takes place, in the installed condition, by 8 elastic deformation of the lamellae 8.

In another detail view A. figure 3e shows a lamella 10 which is disposed in an offset manner and, 'm a manner corresponding to the exemplified embodiment shown mi figure 3b, is likewise disposed between the inner sealig lip 14 and outer sealing lip 16 not radially, but at an angle of offset P. In addition, the lamellae 10 have a biconeave cross-section, a fact which can u'npart mcreased stiffness to the sealing element 1. In the case of this arrangement adaptation or pressmig-in takes place, Mi the installed condition, substantially as a result of elastic re-shapmg in the direction of staggering of the lamellae 10 between the inner and outer sealing lips 14, 16 and the surface of the lamellae 10, that is to say as a result of variation of the angle of staggering P.

9

Claims

1. Sealing element for sealing off two coaxial sealing faces which are capable of axial displacement in relation to one another and/or torsion 'm relation to one another, particularly for sealing off the cylindrical face of a piston in relation to the face of a hollow cylinder, the said element having an inner sealmig lip and an outer sealing lip and a means for elastically bracing at least one of the sealing lips against at least one of the sealing faces, characteni sed in that the means for elastic bracing comprises at least one lamella (2, 4, 6, 8, 10, 12) which is disposed substantially radially between the inner sealing lip (14) and outer sealing lip ( 16).

2. Sealing element acco to claim 1, characterised in that the means comprises at least two lamellae (2, 4, 6, 8, 10, 12) which are disposed at a distance from one another mi the peripheral direction.

3. Sealing element according to one of the preceding claims.

characterised 'm that the lamellae (2, 4, 6, 8, 10, 12) are disposed symmetrically in the peripheral direction.

4. Sealing element according to one of the preceding claims, characterised in that the lamellae (2, 4, 6, 8, 10, 12) are moulded into the sealing element (1).

5. Sealing element according to one of claims 1 to 3, characterised in that the lamellae (2, 4, 6, 8, 10, 12) are designed in one piece with the sealing element (1).

6. Scaling element accordmig to one of claims 4 or 5, characterised mi that the lamellae (2, 4, 6, 8, 10, 12) have a trapezoidal contour with a low extension in thickness.

7. Sealing element according to one of claims 4 or 5, characterised mi that the lamellae (2, 4, 6, 8, 10, 12) have a rectangular or semicircular contour with a low extension m thickness.

8. Sealing element accordmig to one of claims 6 or 7, characterised 'm that the sealing element (1) has a rectangular annular cross-section with an annular face (17) which is open on one side.

9. Sealing element according to claim 8, characterised m that the inner sealmig lip (14) and the outer sealmig lip (16) are connected by a closed annular face (15) which is perpendicular to the said lips.

10. Sealing element according to claim 9, characterised mi that the miner sealing lip (14) and the outer sealing lip (16) are connected by a web (24) disposed centrally and perpendicularly between the said lips.

11. Sealing element accordmig to claim 10, characterised 'm that two rows, m each case, of lamellae (12) which are mutually opposed with their narrow end faces and are separated by the web (24), are moulded into the sealmig element (I).

12. Sealm'g element according to one of the preceding claims, characterised M" that the lamellae (2) have a plane and uniformly thin cross section.

11

13. Sealing element according to one of claims 1 to 11, characterised in that the lamellae (4) have a plano-concave cross-section.

14. Sealing element according to one of claims 1 to 11, characterised in that the lamellae (4) have a biconcave cross-section.

15. Sealing element according to one of claims 1 to 11, characterised in that the lamellae (6) have, in each case, an installation position which is inclined by an angle of offset (cc, P) in relation to the radial (30).

16. Sealing element according to claim 15, characterised 'm that the lamellae (10) have a plano-concave cross-section.

17. Sealing element according to claim 15, characterised in that lamellae (10) have a biconcave cross-section.

the

18. Sealing element acg to one of claims 1 to 11, characteni sed in that the lamellae (8) have a surface which is curved in an S-shaped manner.

19. Sealmg element according to one of the preceding claims, characterised m that the sealing element (1) consists of an elastomenic plastic.

20. Sealing element according to one of the preceding claims, characterised m that the lamellae (2, 4, 6, 8, 10, 12) consist of a plastic.

21. Sealing element according to one of the preceding claims, characterised in that the lamellae (2, 4, 6, 8, 10, 12) and the sealing element (1) consist of the same plastic.

12

22 Sealmig element according to one of the preceding claims, characterised m that the lamellae (2, 4, 6, 8, 10, 12) consist of a fibrereinforced plastic.

23. Sealing element according to one of claims 1 to 19, characterised m that the lamellae (2, 4, 6. 8, 10, 12) consist of metal.

24. Sealing element according to one of claims 1 to 19, characten' sed in that the lamellae (2, 4, 6, 8, 10, 12) consist of a sheet of spring steel.

25. Any of the sealmig elements substantially as herein described with reference to the accompanymig drawings.

13 Amendments to the claims have been filed as follows CLAIMS 1. A sealing element for scaling offtwo coaxial sealing faces which are capable of axial displacement and/or torsion in relation to one another, the scaling element comprising an inner sealing lip, an outer sealing lip and at least one lamella which is disposed substantially radially between the inner sealing lip and outer sealin lip and which, 'm use, elastically braces at least one of the seal me 1 9 ips against at least one of the sealing faces.

2. A sealing element according to clanin 1, wherein at least two lamellae are disposed substantially radially between the inner and outer sealiner lips at a distance from one another in the peripheral direction.

A sealing element according to claim 2 wherein the lamellae are disposed syrrunetrically 'm the peripheral direction.

4. A sealing element according to any of the preceding claims. wherein the or each lamella is moulded into the sealing element.

5. A sealing element according to any of claims 1 to 3, wherein the or each lamella is integrally formed with the sealing c- 6. A sealing element according to any of the preceding clanins, wherein the or each lamella has a trapezoidal contour with a low extension in thickness.

7. A sealing element according to any of claims 1 or 5, wherein the or each lamella has a rectangular or semicircular contour with a low extension in thickness.

Pi- A sealing element according to any of the preceding claims, wherein the sealing element has a rectangular annular cross-section with an annular face which is open on one side.

9.

A scaling element according to any of the preceding claims, wherein the inner sealing lip and the outer sealmig lip are connected by a closed annular face which is perpendicular to the said lips.

10. A sealina element according to any of the preceding claims. wherein the inner scaling lip and the outer sealing lip are connected by, a web disposed centrally and perpendicularly between the said lips.

A sealing element according to claim 10, wherein two rows., in each case, of lamellae which are mutually opposed with their narrow end faces and are separated by the web. are moulded into the scaling element.

12. A sealing element according to any of the preceding claims, wherein the or each lamella has a plane and uniforn-dy thin cross-section.

3. A sealine, element according to any of claims 1 to 11. wherein the or each lamella has a plano-concave cross-section.

14.

A sealine element according to any of claims 1 to 11, the or each lamella has a biconcave cross-section.

15. A sealing element according to any of claims 1 to 11, wherein the or each lamella has, in each case, an installation position which is inclined by an angle of offset in relation to the radial direction.

15, 16. A sealing element according to claim 15, wherein the or each lamella has a plano-concave cross-section.

17. A scaling element according to claim 15, wherein the or each lamella 1 has a biconcave cross-section.

18. A sealing element according to any of claims 1 to 11, wherein the or each lamella has a surface which is curved in an S-shaped manner.

19. A sealing element according to any of the preceding claims, wherein the sealing element is formed of an elastomenic plastic.

20. A scaling element according to any of the preceding claims, wherein the or each lamella is formed of a plastic.

21. A sealing element according to any of the preceding claims, wherein the or each lamella and the sealing element are formed of the same plastic.

22. A sealing element according to any of the preceding claims. wherein the or each lamella is formed of a fibre-reinforced plastic.

A sealing element according to any of claims 1 to 19, wherein the or each lamellae consist of metal.

2 3 - A sealing element according to any of claims 1 to 19, wherein the or each lamella is formed of a sheet of spring steel.

24.

25.

A sealing element according to any of the preceding claims, wherein, 1 (a in use, the sealing element seals off the cylindrical face of a piston in relation to the face of a hollow cylinder.

Any of the sealing elements substantially as herein described with reference to the accompanying drawings.

26.