GB2144185A - Stuffing box - Google Patents

Abstract

The invention concerns a stuffing box seal for sealing shafts relative to fixed walls in a housing or the like. The invention is characterised by a collar, ring, annular flange (3) or like component tightly and firmly connected to the shaft (4) to provide an annular surface (6) extending perpendicular to the axis of rotation (5) of the shaft and a stuffing box packing (1;1'etc) braced against said annular surface in the axial direction of the shaft. The flange may be integral with a shaft bushing 9 (Fig. 1) or separate therefrom (Fig. 2). <IMAGE>

Description

SPECIFICATION Stuffing box The invention concerns a stuffing box seal for sealing shafts relative to fixed walls in a housing or the like.

It is known for such stuffing box seals to consist of soft packing rings arranged in an annular chamber between the shaft and the relevant housing wall or a fixed component connected thereto, and to be pressed leak-tightly against the shaft and against the relevant housing wall by what is known as the stuffing box gland. Unfortunately, it often happens that the shaft does not run exactly smoothly round but with a "wobble". Even if this "wobble" amounts to only 0.2 to O.3 mm, it still results in the fluid leakage losses out of the space which should be sealed becoming unacceptably high in an unacceptably short time. This shaft "wobble" certainly widens out the stuffing box packing in the radial direction.The non-circular running of the shaft may also be occasioned by imbalance or manufacturing inaccuracies, but it is frequently occasioned by the loading of the shaft in operation. In order to counteract the widening out of the stuffing box packing, in conventional stuffing box seals the stuffing box gland has to be tightened up very often in order to bring the sealing gap to nil again. Naturally, this means that the working life of the stuffing box packing is considerably reduced.

It is the object of the invention to provide a stuff- ing box seal with a long working life, without the provision of expensive means for equalising the imbalance of the shaft.

According to the invention this object is achieved in a stuffing box seal by the characteristic features in Patent Claim 1.

With the solution according to the invention the axial sealing gap at the shaft, which is of course the main cause of leakage during the overall operating time, is in fact replaced by a radial sealing gap at the radial annular surface. It has been established that the working life of the stuffing box seal can be increased considerably in this way.

It can be assumed from practical experience that there is'in fact very little axial shaft play, and this does not therefore cause leakage at the radial sealing gap of the stuffing box packing.

The solution according to the invention is described in the following with reference to two embodiment examples.

Figures 1 and 2 are axial sections through the stuffing box seal according to the invention, and show an upper half and a lower half respectively.

In Figure 1 the packing rings of the stuffing box packing 1 are designated 1', 1", etc. These rings are pressed by the stuffing box gland 7 against the annular flange 3 of a shaft bushing 9. The shaft bushing is thereby drawn onto the shaft 4 with a press fit, and is held in place by a component 8 which is attached to the shaft. This component 8 could be the mounting sleeve of the supporting disc for a pump impellor, if a pump were involved in the embodiment example.

Since the shaft bushing 9 is drawn onto the shaft it seals against the shaft. Here the stuffing box packing 1 is shown after a long operating time, i.e.

with an enlarged gap between the shaft bushing 9 and its inner wall. This arises due to the fact that the shaft has widened the stuffing box packing out radially as a result of a slight wobble. This means that radially the stuffing box packing now lies substantially only against the housing. Despite this, however, leakages do not occur since the gap shown, which would in itself lead to leakage, is sealed in the radial direction by the radial annular surface 6 on the shaft bushing or on the annular flange 3 thereon. This annular surface 6 could naturaily also be provided on a ring, as shown with 2 in Figure 2. In this case, the component 8 must seal against the ring 2 in the radial direction. Here again, no leaking fluid can escape from the space 10.

It is advisable that the component which bears the annular surface 6, i.e. the ring 2 or the shaft bushing 9, should be made from a very wear-resistant material such as chromium carbide, for example. However, it is sufficient if the relevant component is providsd with a coating of wear-resistant material of this kind in the region of the annular surface 6. This can be effected electrolytically, for example.

The simple construction of the stuffing box seal can be clearly seen. No costly measures such as a movable holder for the stuffing box packing, for example, need be provided in order to achieve this considerable gain in the length of the working life.

In addition, movable stuffing box holders generally call for additional packing rings which are again susceptible to wear. All this is avoided with the invention.

1. A stuffing box seal sealing a shaft relative to a fixed wall in a housing or the like, characterised in that a collar, ring, annular flange, or like component is tightly and firmly connected to the shaft to provide an annular surface extending perpendicular to the axis of rotation of the shaft, the arrangement being such that the stuffing box packing is leak-tightly braced against said annular surface in the axial direction of the shaft.

2. A stuffing box seal according to Claim 1, characterised in that the component providing said annular surface is made from a particularly wearresistant material.

3. A stuffing box seal according to Claim 1, characterised in that the component providing said annular surface is provided with a coating of a particularly wear-resistant material, especially on said annular surface.

4. A stuffing box seal constructed, arranged and adapted for use substantially as hereinbefore described with reference to, and as shown in, the accompanying drawing.

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

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Stuffing box The invention concerns a stuffing box seal for sealing shafts relative to fixed walls in a housing or the like. It is known for such stuffing box seals to consist of soft packing rings arranged in an annular chamber between the shaft and the relevant housing wall or a fixed component connected thereto, and to be pressed leak-tightly against the shaft and against the relevant housing wall by what is known as the stuffing box gland. Unfortunately, it often happens that the shaft does not run exactly smoothly round but with a "wobble". Even if this "wobble" amounts to only 0.2 to O.3 mm, it still results in the fluid leakage losses out of the space which should be sealed becoming unacceptably high in an unacceptably short time. This shaft "wobble" certainly widens out the stuffing box packing in the radial direction.The non-circular running of the shaft may also be occasioned by imbalance or manufacturing inaccuracies, but it is frequently occasioned by the loading of the shaft in operation. In order to counteract the widening out of the stuffing box packing, in conventional stuffing box seals the stuffing box gland has to be tightened up very often in order to bring the sealing gap to nil again. Naturally, this means that the working life of the stuffing box packing is considerably reduced. It is the object of the invention to provide a stuff- ing box seal with a long working life, without the provision of expensive means for equalising the imbalance of the shaft. According to the invention this object is achieved in a stuffing box seal by the characteristic features in Patent Claim 1. With the solution according to the invention the axial sealing gap at the shaft, which is of course the main cause of leakage during the overall operating time, is in fact replaced by a radial sealing gap at the radial annular surface. It has been established that the working life of the stuffing box seal can be increased considerably in this way. It can be assumed from practical experience that there is'in fact very little axial shaft play, and this does not therefore cause leakage at the radial sealing gap of the stuffing box packing. The solution according to the invention is described in the following with reference to two embodiment examples. Figures 1 and 2 are axial sections through the stuffing box seal according to the invention, and show an upper half and a lower half respectively. In Figure 1 the packing rings of the stuffing box packing 1 are designated 1', 1", etc. These rings are pressed by the stuffing box gland 7 against the annular flange 3 of a shaft bushing 9. The shaft bushing is thereby drawn onto the shaft 4 with a press fit, and is held in place by a component 8 which is attached to the shaft. This component 8 could be the mounting sleeve of the supporting disc for a pump impellor, if a pump were involved in the embodiment example. Since the shaft bushing 9 is drawn onto the shaft it seals against the shaft. Here the stuffing box packing 1 is shown after a long operating time, i.e. with an enlarged gap between the shaft bushing 9 and its inner wall. This arises due to the fact that the shaft has widened the stuffing box packing out radially as a result of a slight wobble. This means that radially the stuffing box packing now lies substantially only against the housing. Despite this, however, leakages do not occur since the gap shown, which would in itself lead to leakage, is sealed in the radial direction by the radial annular surface 6 on the shaft bushing or on the annular flange 3 thereon. This annular surface 6 could naturaily also be provided on a ring, as shown with 2 in Figure 2. In this case, the component 8 must seal against the ring 2 in the radial direction. Here again, no leaking fluid can escape from the space 10. It is advisable that the component which bears the annular surface 6, i.e. the ring 2 or the shaft bushing 9, should be made from a very wear-resistant material such as chromium carbide, for example. However, it is sufficient if the relevant component is providsd with a coating of wear-resistant material of this kind in the region of the annular surface 6. This can be effected electrolytically, for example. The simple construction of the stuffing box seal can be clearly seen. No costly measures such as a movable holder for the stuffing box packing, for example, need be provided in order to achieve this considerable gain in the length of the working life. In addition, movable stuffing box holders generally call for additional packing rings which are again susceptible to wear. All this is avoided with the invention. CLAIMS

1. A stuffing box seal sealing a shaft relative to a fixed wall in a housing or the like, characterised in that a collar, ring, annular flange, or like component is tightly and firmly connected to the shaft to provide an annular surface extending perpendicular to the axis of rotation of the shaft, the arrangement being such that the stuffing box packing is leak-tightly braced against said annular surface in the axial direction of the shaft.

2. A stuffing box seal according to Claim 1, characterised in that the component providing said annular surface is made from a particularly wearresistant material.

3. A stuffing box seal according to Claim 1, characterised in that the component providing said annular surface is provided with a coating of a particularly wear-resistant material, especially on said annular surface.

4. A stuffing box seal constructed, arranged and adapted for use substantially as hereinbefore described with reference to, and as shown in, the accompanying drawing.