GB1566034A

GB1566034A - High-pressure shaft-sealing ring

Info

Publication number: GB1566034A
Application number: GB18722/77A
Authority: GB
Original assignee: Goetze GmbH
Current assignee: Goetze GmbH
Priority date: 1976-05-04
Filing date: 1977-05-04
Publication date: 1980-04-30
Also published as: DE2619565A1; FR2350524A1; IT1115702B

Description

(54) HIGH-PRESSURE SHAFT-SEALING RING (71) We, GOETHE AG (Formerly known as GOETZEWERKB FRIEDRICH GOETZE A.G.), a Body Corporate organised and existing under the laws of the Federal Republic of Germany, of Burgermeister Schmidt-Strasse 17, 5093 Burscheid, Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The invention concerns a shaft-sealing ring for sealing a medium under high pressure, in particular for the steering gear of motor vehicles, comprising a sealing housing of substantially angular cross-section, that is to say having a peripheral wall and an end wall extending radially inwards from one end of the peripheral wall, and an annular sealing body of elastomeric material fitted in the housing.

When using shaft-sealing rings for sealing media under high pressure, special requirements have to be met by the construction and development of the sealing lips of sleeve seals, since the pressure of the medium leads to considerable deformation and therefore to relatively high wear of the sealing lips. For sealing pistons or piston rods, a grooved ring seal is known from French Patent Specification 1,595,326, which sleeve has on the dynamically stressed sealing lip side, in the region of the bottom surface, a recess for receiving a supporting ring. The latter slides on the cylinder to be sealed or on the rod surface, and prevents the sealing lip material from flowing away owing to the high pressure of the medium in the sealing gap between the machine parts moving relatively to one another. Since the relatively high pressure of the medium in the same way acts on the second sealing lip of the grooved ring sleeve, a sufficiently good static seal is thus produced, such that in the case of a pure stroke movement between the parts to be sealed, an additional sealing housing is not necessary.

In the sealing of rotating shafts, the torque produced by friction at the dynamically stressed sealing place must be transmitted additionally across the statically stressed sealing place to the adjoining machine part.

In particular, in the case of normal, i.e.

atmospheric pressure of the medium, the radial sealing force produced by the medium at the statically stressed sealing place does not suffice for transmitting the torque. For this reason and further economic considerations, shaft-sealing rings usually consist of a generally metallic housing; substantially angular in cross-section, to the radial member of which an elastic sealing lip is vulcanised, the said lip being connected by a highly elastic intermediate diaphragm to the radial member of the sealing housing. To be able to use such seals also as highpressure seals, it is known from French Patent Specification 1,345,547 to lengthen the free end of the radial housing member and to allow it to extend as supporting body under the elastic diaphragm part. Owing to the wobble of rotating shafts, a relatively wide gap must be left between the inner periphery of the supporting member and the shaft surface.

It is furthermore known through German Patent Specification 948,464 to adhesively secure in a corresponding recess of the sealing lip of a shaft sealing ring a hard material ring, which lies with its inner periphery on the shaft surface and serves for guiding the sealing lip on the shaft surface rotating in a non-circular manner.

In accordance with the present invention there is provided a shaft-sealing ring comprising a seal housing having a peripheral wall and an end wall extending radially inwards from one end of the peripheral wall.

an annular sealing body of elastomeric mat- erial fitted in the housing and having a seal ing lip with a sealing edge for engagment with the shaft, the sealing lip being surrounded by a garter spring, and a supporting ring held between the sealing body and the end wall of the housing and accommodated in a recess in the radially inner surface of the sealing body, the inner diameter of the supporting ring being between the inner diameter of the garter spring and the inner diameter of the sealing edge.

To avoid friction between the supporting ring and the shaft surface, it is proposed to make the inner diameter of the supporting ring slightly larger than the shaft diameter.

The clearance provided is in accord with the ISO standard. The supporting ring is thus to be considered as a shim ring for the radial member of the sealing housing, since the production of a sealing housing with a finely toleranced internal diameter of the radial member would only be possible at particularly high expense.

To avoid an axially relatively broadly constructed sealing unit, it is sufficient if the radial depth of the recess in the groove ring sleeve is less than the thickness of the shaftside sealing lip, and therefore the supporting ring also is itself formed radially low or squat.

In particular, in the case of strongly fluctuating pressure of the medium, it is of advantage if the inner peripheral surface of the sealing lip, extending from the sealing edge towards the supporting ring, extends at an angle of less than 10 , preferably 5 , inclined to the shaft surface. In the case of a relatively low pressure of the medium, contact of the sealing lip with the shaft surface is thereby ensured exclusively in the region of the sealing edge, while in the case of extremely high pressure of the medium, the entire inner peripheral surface of the sealing lip is brought to bear uniformly on the shaft surface without particularly strong deformation of the sealing lip cross-section.

An embodiment example of the invention is represented in the drawings and is described more particularly in the following.

In the drawings: Fig. 1 shows a cross-section through a high-pressure shaft-sealing ring according to the invention, Fig. 2 shows a part section through the high-pressure shaft-sealing ring fitted in a hydraulic steering gear.

The shaft-sealing ring shown in Fig. 1 comprises a sealing housing 1 of angular cross-section, a groove annular sealing body 2 inserted therein and secured by a housing collar 3 against falling out axially, and a supporting ring 6 inserted in a recess in the base surface 5 of the grooved sealing body 2, which supporting ring is held axially by the radial member 7 of the sealing housing 1. The high pressure medium side of the seal is shown at 8, the static sealing lip at 9 and the dynamic sealing lip at 10. The latter has, on the outer periphery, a groove 11 for receiving a helical garter spring 12, while on the periphery a sealing edge 13 is formed by two oppositely inclined inner peripheral surfaces 14, 15. The angle of inclination between the inner peripheral surface 14 and the shaft surface (the latter is shown in dot-and-dash lines) amounts to about 5". The inner cylindrical peripheral surface 16 of the supporting ring has a diameter greater than that of the shaft by 0.1 to 0.2 mm.

The sealing housing 1 consists of metal and is drawn as sheet-metal part. The groove ring sleeve 2 consists of rubber, while the supporting ring is made of a relatively hard material having good sliding properties, for example PTFE.

Figure 2 shows the conditions of fitting the shaft-sealing ring of Fig. 1 in a hydraulic steering gear of a motor vehicle. The shaftsealing ring is arranged in a recess 17 of the gear housing 18, the said recess being open towards the medium side 8', such that the pressure of the medium presses both the grooved sealing body 2 and the sealing housing 1 sealingly axially and radially against the boundary surfaces of the recess 17. Static sealing between the seal housing 1 and the gear housing 18 is increased by a lacquer coating previously applied to the seal housing. For dismounting the shaft-sealing ring, a number of holes 19, distributed over the periphery, are drilled in the radial flange 20 of the gear housing 18, through which holes the shaft-sealing ring, pressed into the recess 17 with- considerable force, can be pressed out again by the press-out punches of a tool, not shown.

WHAT WE CLAIM IS: 1. A shaft-sealing ring comprising a seal housing having a peripheral wall and an end wall extending radially inwards from one end of the peripheral wall, an annular sealing body of elastomeric material fitted in the housing and having a sealing lip with a sealing edge for engagement with the shaft, the sealing lip being surrounded by a garter spring, and a supporting ring held between the sealing body and the end wall of the housing and accommodated in a recess in the radially inner surface of the sealing body, the inner diameter of the supporting ring being between the inner diameter of the garter spring and the inner diameter of the sealing edge.

2. A shaft-sealing ring as claimed in claim 1 in which the radial depth of the said recess is less than the radial thickness of the sealing lip.

3. A shaft-sealing ring as claimed in

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. ing lip with a sealing edge for engagment with the shaft, the sealing lip being surrounded by a garter spring, and a supporting ring held between the sealing body and the end wall of the housing and accommodated in a recess in the radially inner surface of the sealing body, the inner diameter of the supporting ring being between the inner diameter of the garter spring and the inner diameter of the sealing edge. To avoid friction between the supporting ring and the shaft surface, it is proposed to make the inner diameter of the supporting ring slightly larger than the shaft diameter. The clearance provided is in accord with the ISO standard. The supporting ring is thus to be considered as a shim ring for the radial member of the sealing housing, since the production of a sealing housing with a finely toleranced internal diameter of the radial member would only be possible at particularly high expense. To avoid an axially relatively broadly constructed sealing unit, it is sufficient if the radial depth of the recess in the groove ring sleeve is less than the thickness of the shaftside sealing lip, and therefore the supporting ring also is itself formed radially low or squat. In particular, in the case of strongly fluctuating pressure of the medium, it is of advantage if the inner peripheral surface of the sealing lip, extending from the sealing edge towards the supporting ring, extends at an angle of less than 10 , preferably 5 , inclined to the shaft surface. In the case of a relatively low pressure of the medium, contact of the sealing lip with the shaft surface is thereby ensured exclusively in the region of the sealing edge, while in the case of extremely high pressure of the medium, the entire inner peripheral surface of the sealing lip is brought to bear uniformly on the shaft surface without particularly strong deformation of the sealing lip cross-section. An embodiment example of the invention is represented in the drawings and is described more particularly in the following. In the drawings: Fig. 1 shows a cross-section through a high-pressure shaft-sealing ring according to the invention, Fig. 2 shows a part section through the high-pressure shaft-sealing ring fitted in a hydraulic steering gear. The shaft-sealing ring shown in Fig. 1 comprises a sealing housing 1 of angular cross-section, a groove annular sealing body 2 inserted therein and secured by a housing collar 3 against falling out axially, and a supporting ring 6 inserted in a recess in the base surface 5 of the grooved sealing body 2, which supporting ring is held axially by the radial member 7 of the sealing housing 1. The high pressure medium side of the seal is shown at 8, the static sealing lip at 9 and the dynamic sealing lip at 10. The latter has, on the outer periphery, a groove 11 for receiving a helical garter spring 12, while on the periphery a sealing edge 13 is formed by two oppositely inclined inner peripheral surfaces 14, 15. The angle of inclination between the inner peripheral surface 14 and the shaft surface (the latter is shown in dot-and-dash lines) amounts to about 5". The inner cylindrical peripheral surface 16 of the supporting ring has a diameter greater than that of the shaft by 0.1 to 0.2 mm. The sealing housing 1 consists of metal and is drawn as sheet-metal part. The groove ring sleeve 2 consists of rubber, while the supporting ring is made of a relatively hard material having good sliding properties, for example PTFE. Figure 2 shows the conditions of fitting the shaft-sealing ring of Fig. 1 in a hydraulic steering gear of a motor vehicle. The shaftsealing ring is arranged in a recess 17 of the gear housing 18, the said recess being open towards the medium side 8', such that the pressure of the medium presses both the grooved sealing body 2 and the sealing housing 1 sealingly axially and radially against the boundary surfaces of the recess 17. Static sealing between the seal housing 1 and the gear housing 18 is increased by a lacquer coating previously applied to the seal housing. For dismounting the shaft-sealing ring, a number of holes 19, distributed over the periphery, are drilled in the radial flange 20 of the gear housing 18, through which holes the shaft-sealing ring, pressed into the recess 17 with- considerable force, can be pressed out again by the press-out punches of a tool, not shown. WHAT WE CLAIM IS:

1. A shaft-sealing ring comprising a seal housing having a peripheral wall and an end wall extending radially inwards from one end of the peripheral wall, an annular sealing body of elastomeric material fitted in the housing and having a sealing lip with a sealing edge for engagement with the shaft, the sealing lip being surrounded by a garter spring, and a supporting ring held between the sealing body and the end wall of the housing and accommodated in a recess in the radially inner surface of the sealing body, the inner diameter of the supporting ring being between the inner diameter of the garter spring and the inner diameter of the sealing edge.

3. A shaft-sealing ring as claimed in

claim 1 or 2 in which the flank of the sealing lip extending from the sealing edge towards the supporting ring is inclined at less than 10 to a cyhudrical surface centred on the axis of the ring.

4. A shaft-sealing ring substantially as described with reference to Fig. 1 of the accompanying drawing.

5. A shaft-sealing ring assembled in a hydraulic steering gear housing the assembly being substantially as described with reference to the accompanying drawings.