DE2021382A1 - Shaft seal - Google Patents

Description

PATENT LAWYERS

Dipl.ing. H. LEINWEBER dipl-ing H. ZIMMERMANN

8 Munich 2, Rosental 7, 2nd ed.

lei.-addr. lelnpat Munich Telephone (OHI) MIfM

_the April 30, 1970

Under signs

Z / Ri / Va / Lo

GEORGE ANGUS & COMPANY, Newcastle upon Tyne 1 /. Great Britain

Shaft seal

Addendum to patent ... ...... (patent application P 16 25 905.5-12)

The invention relates to shaft seals that Also known as oil seals and those used to seal against leakage of fluid along shafts, such as crankshafts or automotive drive transmissions, are known to occur due to factors such as shaft deflection, Torsional vibration and eccentric movement difficult to seal are.

It has long been known that the sealing of such Waves can be improved by having a kind of return screw or return screw on the sealed circumference provided which is formed by a helical ridge or groove on the surface of the shaft or seal. By appropriate choice of the direction of the helix in relation to on the normal direction of rotation of the shaft causes the relative

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009847/1163

BATH ORIGINAL

Rotation that the oil or any other liquid that tends to leak through the seal is returned.

The most suitable way of creating a return effect is to create the required rib or groove to form on the sealing circumference of the seal, so that a change in the shaft is not required and the seal on the cylindrical surface - any shaft of suitable size enters ». ,

The invention relates to an improvement or modification

of the invention according to patent (patent application

P 16 25 905.5-12), hereinafter referred to as the "main patent", through which a shaft seal is created in each Direction of rotation of the shaft exerts a return action.

The main patent relates to a shaft seal comprising a molded sealing ring made of elastic material, the one circumferential sealing lip with a circumferentially extending sealing band between an inner and has an outer frustoconical surface that when in use of the seal are respectively turned towards and away from the sealed liquid, the outer frustoconical surface is provided with guide surface parts, each of which forms the surface of a rib or a groove, which obliquely on the sealing tape hit. According to the main patent, an equal number of such guide surface parts meet in opposite directions Circumferential directions at an angle of not more than 20 to the plane of the sealing tape on this. The best results are achieved if the angle of incidence is less than 20, preferably not more than 10 ° or, if possible, not more than ' 5 °.

009847/1 163

According to the invention, the guide surface parts have two intersecting, oppositely directed groups are more helical Ribs on that on the outer frustoconical surface of the gasket, the ribs of each group being parallel to each other and the helix angle, i. the angle at which the ribs meet the sealing tape, in both groups of ribs the same size and directed in opposite directions is.

The two groups of ribs form the pattern with the im substantial rhomboid gaps and in the circumferential direction passing major axes, and the sealing tape cuts a circumferential series of spaces along one Circumference, which runs parallel to their main axes and preferably coincides with them.

Usually, in the case of a sealing ring, the sealing tape is one formed by the connection of the frustoconical surfaces formed edge, however, the edge is caused by the initial abrasion of the operating sealing ring known as "running-in" axially widened to form a narrow band, also known as the "contact band". A corresponding tape could however, they can also be formed during the manufacture of a sealing ring.

Further details, advantages and features of the invention emerge from the following description. On the drawing the invention is illustrated by way of example, namely show '

Fig. 1 shows an axial section of an inner shaft seal according to of the invention and

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FIG. 2 shows, on an enlarged scale, a partial section in the plane H-II of FIG. 1.

The drawing shows a molded sealing ring made of synthetic rubber or the like. with a channel-shaped cross-section, the has a cylindrical outer wall 1, which is stiffened by an insert 2 with an L-shaped cross-section to a holding part form, and also a flexible flange 3, which is surrounded by a radial spring 4 and forms the sealing lip.

A circular sealing edge 5 is created by the connection between an outer and an inner frustoconical Area 6 and 7 formed.

On the surface 6, two groups of helical ribs 8 and 9 are formed, which intersect at intersection points 10 and between them a symmetrical pattern of essentially rhomboid spaces 11 with essentially axially extending spaces Love axes X-X and running in the circumferential direction Form main axes.

For a better explanation, the ribs 8 are shown in FIG. 1 with thick lines and the ribs 9 with thin lines.

The sealing edge 5 coincides with the main axes of a row of spaces 11 running in the circumferential direction, which are halved and are too open after the sealing edge, such that the remaining parts of the ribs delimiting them Form pairs of oppositely directed guide surfaces 8a and 9a, which merge into the sealing edge 5, whereby the return the leaking liquid is caused in each direction of rotation of the shaft.

00 9 847/116 3 '

A seal as shown in Fig. 1 can be made by shaping the outer frustoconical surface β complete with the ribs 8 and 9 Ms for the full axial extension of the flange 3, as indicated by dashed lines, whereupon the inner surface 7 is formed by trimming, as is known in the manufacture of shaft seals. The resulting shape of the sealing edge 5, on which the guide surfaces 8a and 9a meet, is shown on an enlarged scale in FIG. 2, which shows a partial section in the plane H-II of FIG.

Accurate cutting operations are required to achieve the Sealing edge 5 exactly along the relevant main axes Forming Y-Y, however, this is not essential. Good results can be achieved with a trimmed sealing edge which runs essentially parallel to the main axes Y-Y, since, as mentioned above, the sealing edge is widened axially by initial wear, i.e. running-in, whereby it forms a sealing tape. If very precise training is required in a particular case, the surfaces 6 and 7 with the ribs 8 and 9 meeting with the sealing edge 5 are produced entirely by molding.

The preferred cross-sectional shape of the ribs 8 and 9 is As Fig. 2 shows, essentially an L-shaped or right-angled triangular shape, one side surface of which is cylindisch.um the axis of the sealing ring runs.

The dimensions are shown on the drawing for better explanation of the ribs enlarged, in practice, however, the ribs are only fine thread webs, so that they only have a little of the surface 6 on

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of which they are formed, protrude and smoothly merge into the sealing edge 5 without forming projections that form the complete Line contact of the sealing edge 5 with the surface of a shaft with a suitable diameter would interfere.

The actual dimensions of the ribs will depend on the size and type of seal. The following examples can but serve as adequate tail surfaces.

Angle of the outer frustoconical surface - 30 ° shaft diameter "76.2 mm

Pitch of each screw thread 4.75 per cm

Incline of each group 19 per cm

(4 courses in each group)

radial dimension of each screw thread 0.127 mm, axial dimension of each screw thread 0.22 mm

The invention has been described in terms of its use as an inner shaft seal, but it can also be applied to a outer shaft seal are used, which is known to be attached to a shaft that it rotates with her and seals against a surrounding cylindrical surface of a housing. In the case of an outer seal, the positions are as the holding part formed wall 1 and that of the flange 3 reversed with respect to each other and the radial spring 4 acts radially Outside.

The elastic material of the sealing ring can, such as mentioned above, synthetic rubber or natural rubber or similar material, e.g. plastics known as elastomers.

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Claims (2)

P at e η t an s ρ r ü c he: \ / Ml shaft seal made from a molded sealing ring elastic material that has a circumferential sealing lip with a circumferential sealing tape between a inner and an outer frustoconical surface, which in the Operation of the seal of the sealed liquid facing or facing away, with the outer frusto-conical surface with Conductive surface parts is provided, each of which forms the surface of a rib or a groove which impinge obliquely on the sealing tape, with at least two of these conductive surface parts ■ on the sealing tape in opposite directions, at an angle of not more than 20 to the plane of the Sealing tape hit, according to patent ......... (patent application P 16 25 905.5-12), characterized in that the guide surface parts are two intersecting, oppositely directed Have groups of helical ribs (8, 9) on the outer frustoconical surface (6) of the seal formed where the ribs of each group are parallel to each other and the helix angle, i.e. the angle at which the The ribs meet the sealing tape (5), both groups of ribs are of the same size and point in opposite directions. 2. Shaft seal according to claim 1, characterized in that that the ribs (8, 9) have a substantially L-shaped Have cross-section in which a side surface extends cylindrically around the axis of the directional ring. 009847/1163. BATH ORIGINAL Blank page