GB1594090A

GB1594090A - Seal units

Info

Publication number: GB1594090A
Application number: GB4472976A
Authority: GB
Original assignee: West and Son Engineers Ltd
Current assignee: West and Son Engineers Ltd
Priority date: 1977-11-01
Filing date: 1977-11-01
Publication date: 1981-07-30

Description

(54) SEAL UNITS (71) We, WEST & SON ENGINEERS LIMITED, a British Company of 65 Sherwood Street, Mansfield Woodhouse, Nottinghamshire, 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 present invention relates to seal units particularly seal units for providing a seal between the drive shaft of a pump and the housing of the pump.

According to one aspect of the present invention there is provided a seal unit for providing a sealing connection between a shaft and a wall through which the shaft projects, the unit including a housing having at least two separable portions which permit the housing to be assembled about the shaft in a radial direction, the housing in its assembled condition including an annular chamber which in use extends about the shaft and which contains compressible sealing means which provide a seal between the shaft and the wall of the chamber, the annular chamber being defined by a bore in the housing, one end of the bore having an inwardly directed annular flange and the other end of the bore being closed by annular compression means co-operable with the internal wall of the bore so as to be movable within the bore for compressing said sealing means.

According to another aspect of the invention there is provided apparatus including a shaft and a wall and a seal unit as defined above arranged to provide a seal between the shaft and wall.

Reference is now made to the accompanying drawings in which: Figure 1 is an exploded perspective view of an embodiment according to the present invention; Figure 2 is an axial section of the embodiment illustrated in Figure 1 shown in position on a shaft protruding from the pump casing; Figure 3 is a part plan view of an embodiment according to the present invention; Figure 4 is a part perspective view of the embodiment of Figure 3; Figure 5 is a longitudinal section of the embodiment of Figure 3; The housing also includes a cylindrical portion 16 which projects from one side of a flange 12 and which is provided with a centray bore 17.

The end of the bore 17 remote from flange 12 is provided with an annular inwardly directed flange 18 and the internal wall of the bore 17 at least adjacent to the end opposite the end having annular flange 18 is internally threaded to threadedly receive a compression ring 20 whose outer periphery is externally threaded.

The dlameter of the aperture defined by the inner surface 18a of the annular flange 18 is chosen to give bare clearance between the flange and the shaft, for instance, to define a clearance gap in the order of about 5 thousandths of an inch.

A seal chamber 22 is defined between ring 20 annular flange 18 and the internal wall of the cylindrical portion 16.

In use chamber 22 is filled with a suitable packing material which is placed under compression by screwing ring 20 towards flange 18. The packing material may, for example, be material commonly used for filling of stuffing boxes in conventional pump seals.

In the present embodiment the packing material is in the form of elongate strips of a suitable plastics material such as 'Neoprene' (Registered Trade Mark) which is illustrated in Figure 1 and is in the form of split rings 21. As more clearly seen in Figure 2 in cross-section the strips have inclined side walls so that when located in chamber 20 and under axial compression the outer edges of each strip are urged outwards for sealing engagement with the inner wall of bore 17 and the inner edges are urged inwardly for sealing engagement with the shaft.

Consequently, wear occurring on the contact surfaces of the sealing strip may be compensated by increasing the axial compression by rotation of compression ring 20.

Turning of ring 20 is conveniently effected by a key 25 having a pair of spaced projections 26 which are received in recesses 27 formed in the outer end face 29 of the ring 20. The ring is conveniently restricted from rotation by a detent member 28 which is attached to flange 12 by a bolt 29. The detent member having a projection 28a which is locatable in any of recesses 27 so as to prevent rotation of the ring 20. As an alternative to the elongate strip being in the form of split rings 21, the strip may be in the form of a helical scroll.

The described seal unit may be inserted into the stuffing boxes of conventional centrifugal pumps and the outer wall 16a of the cylindrical portion 16 is provided with an annular recess 30 in which reception of an "0" ring 31 provides a sealing connection between an outer wall 16 and the surrounding wall of the pump casing.

Conveniently the "0" ring 31 may be of the split ring type which after location of the seal on to the cylindrical portion 16 abutting ends of the ring are joined together with a suitable adhesive.

The material from which the housing and ring 20 are made is chosen bearing in mind the working conditions of the seal unit, for instance, they may be made of a metal or of a suitable plastics material. For example, if the seal unit is to be used in an acidic environment the housing may be made of stainless steel or if the unit is to be used in a water environment the housing may be of an anodized aluminium or an alloy.

The housing 11 and ring 20 are split along a diametric plane into respective parts 1 lea and 1 lib and 20a and 20b. The halves 20a and 20b are located together by locating dowels 40 and are prevented from separation when the assembled ring is threadedly received in bore 17. The housing halves 1 lea and 1 lib are connected together by locating dowels 41 and by bolts 42 which extend through one half to be threadedly received in the other half.

Consequently, if desired, removal of the described seal unit from a pump casing is simply achieved without the necessity of dismantling the pump. Additionally, replacement of the sealing rings within the chamber 20 can be simply and quickly carried out.

With reference to Figures 3 to 5 a seal unit is generally shown at 10 and is of similar construction as that described and illustrated in Figures 1 and 2 and accordingly similar part have been alloted similar reference numerals.

The annular compression ring 20 of the present seal unit includes an outer annular ring 120 and an inner annular ring 121 which is threadedly received therein. The outer annular ring 120 is threadedly received in a central bore 17 of housing 11 and has an abutment end face 123 which is arranged to contact an outer edge of sealing ring 21 so that the outer edges thereof are urged into engagement with the walls of bore 17 and the inner edges thereof are urged into contact with the shaft (not shown).

The inner annular ring 121 is also provided with an abutment face 124 which is arranged to abut the inner marginal portion of sealing rings 21. Consequently, as readily appreciated from Figure 5, as the outer ring 120 is moved axially to the left the rings are distorted so that the outer edges are moved further outwards and the inner edges are moved further inwards. However, this distortion is opposed by the inner ring 121.

Consequently, in use the amount of pressure exerted by the inner edges of rings 21 on the shaft as a lied by ring 120 may be carried as desired by axial movement of inner ring 121 relative to the outer ring 120. As clearly seen in Figures 3 and 4 the outer ring 120 is provided with longitudinally extending recesses 130 which provide access to end face 121a of the inner ring 121 for the purpose of causing rotation thereof by a key 140.

Conveniently, the inner ring 121 is split about a diametric plane into two halves in a similar manner to ring 120.

It will be appreciated that the inner ring may be axially extended so as to project from the outer end face of ring 12 or be flush therewith to provide access thereto for the purpose of rotating relative to the outer ring 12u.

It is envisaged that the present seal units may be used for providing a seal between a shaft and a wall in a variety of instances whether the shaft is moved axially and/or is rotated relative to the wall.

WHAT WE CLAIMS IS: 1. A seal unit for providing a sealing connection between a shaft and a wall through which the shaft projections, the unit including a housing having at least two separable portions which permit the housing to be assembled about the shaft in a radial direction, the housing in its assembled condition including an annular chamber which in use extends about the shaft and which contains compressible sealing means which provide a seal between the shaft and the wall of the chamber, the annular chamber being defined by a bore in the housing, one end of the bore having an inwardly directed annular flange and the other end of the bore being closed by annular compression means co-operable with the internal wall of the bore so as to be movable within the bore for compressing said sealing means.

2. A seal unit according to claim 1 wherein the compression means comprises

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. Turning of ring 20 is conveniently effected by a key 25 having a pair of spaced projections 26 which are received in recesses 27 formed in the outer end face 29 of the ring 20. The ring is conveniently restricted from rotation by a detent member 28 which is attached to flange 12 by a bolt 29. The detent member having a projection 28a which is locatable in any of recesses 27 so as to prevent rotation of the ring 20. As an alternative to the elongate strip being in the form of split rings 21, the strip may be in the form of a helical scroll. The described seal unit may be inserted into the stuffing boxes of conventional centrifugal pumps and the outer wall 16a of the cylindrical portion 16 is provided with an annular recess 30 in which reception of an "0" ring 31 provides a sealing connection between an outer wall 16 and the surrounding wall of the pump casing. Conveniently the "0" ring 31 may be of the split ring type which after location of the seal on to the cylindrical portion 16 abutting ends of the ring are joined together with a suitable adhesive. The material from which the housing and ring 20 are made is chosen bearing in mind the working conditions of the seal unit, for instance, they may be made of a metal or of a suitable plastics material. For example, if the seal unit is to be used in an acidic environment the housing may be made of stainless steel or if the unit is to be used in a water environment the housing may be of an anodized aluminium or an alloy. The housing 11 and ring 20 are split along a diametric plane into respective parts 1 lea and 1 lib and 20a and 20b. The halves 20a and 20b are located together by locating dowels 40 and are prevented from separation when the assembled ring is threadedly received in bore 17. The housing halves 1 lea and 1 lib are connected together by locating dowels 41 and by bolts 42 which extend through one half to be threadedly received in the other half. Consequently, if desired, removal of the described seal unit from a pump casing is simply achieved without the necessity of dismantling the pump. Additionally, replacement of the sealing rings within the chamber 20 can be simply and quickly carried out. With reference to Figures 3 to 5 a seal unit is generally shown at 10 and is of similar construction as that described and illustrated in Figures 1 and 2 and accordingly similar part have been alloted similar reference numerals. The annular compression ring 20 of the present seal unit includes an outer annular ring 120 and an inner annular ring 121 which is threadedly received therein. The outer annular ring 120 is threadedly received in a central bore 17 of housing 11 and has an abutment end face 123 which is arranged to contact an outer edge of sealing ring 21 so that the outer edges thereof are urged into engagement with the walls of bore 17 and the inner edges thereof are urged into contact with the shaft (not shown). The inner annular ring 121 is also provided with an abutment face 124 which is arranged to abut the inner marginal portion of sealing rings 21. Consequently, as readily appreciated from Figure 5, as the outer ring 120 is moved axially to the left the rings are distorted so that the outer edges are moved further outwards and the inner edges are moved further inwards. However, this distortion is opposed by the inner ring 121. Consequently, in use the amount of pressure exerted by the inner edges of rings 21 on the shaft as a lied by ring 120 may be carried as desired by axial movement of inner ring 121 relative to the outer ring 120. As clearly seen in Figures 3 and 4 the outer ring 120 is provided with longitudinally extending recesses 130 which provide access to end face 121a of the inner ring 121 for the purpose of causing rotation thereof by a key 140. Conveniently, the inner ring 121 is split about a diametric plane into two halves in a similar manner to ring 120. It will be appreciated that the inner ring may be axially extended so as to project from the outer end face of ring 12 or be flush therewith to provide access thereto for the purpose of rotating relative to the outer ring 12u. It is envisaged that the present seal units may be used for providing a seal between a shaft and a wall in a variety of instances whether the shaft is moved axially and/or is rotated relative to the wall. WHAT WE CLAIMS IS:

1. A seal unit for providing a sealing connection between a shaft and a wall through which the shaft projections, the unit including a housing having at least two separable portions which permit the housing to be assembled about the shaft in a radial direction, the housing in its assembled condition including an annular chamber which in use extends about the shaft and which contains compressible sealing means which provide a seal between the shaft and the wall of the chamber, the annular chamber being defined by a bore in the housing, one end of the bore having an inwardly directed annular flange and the other end of the bore being closed by annular compression means co-operable with the internal wall of the bore so as to be movable within the bore for compressing said sealing means.

2. A seal unit according to claim 1 wherein the compression means comprises

an annular member which is threadedly received within the bore.

3. A seal unit according to claim 2 wherein the annular member is composed of at least two separable portions which may be assembled about the shaft in a radial direction.

4. A seal unit according to claim 2 or 3 wherein the compression means includes a further annular member which is axially movable within said annular member for compression of the sealing means received in the chamber.

5. A seal unit according to claim 4 wherein said further annular member is composed of at least two separable portions which may be assembled about the shaft in a radial direction.

6. A seal unit according to any of claims 1 to 5 wherein the sealing means comprises an elongate strip having an outer edge which in use contacts the wall of the bore and an inner edge which contacts the shaft, the strip in cross-section having side walls inclined to the axis of the bore so that when the strip is axially compressed the outer edge is urged outwardly and the inner edge is urged inwardly.

7. A seal unit according to claim 6 wherein the elongate strip is in the form of a split ring.

8. A seal unit according to claim 6 wherein the elongate strip is in the form of a helical scroll.

9. A seal unit substantially as described with reference to and as illustrated in the accompanying drawings.

10. Apparatus including a shaft and a wall and a seal unit according to any preceding claim arranged to provide a seal between the shaft and wall.