GB2054742A - Rotary pumps - Google Patents

Abstract

A pump for e.g. a potable liquid or a pharmaceutical liquid, in which a rotor shaft 23 is supported by a sleeve 42 mounted in a bearing 16, the sleeve being secured to the shaft by e.g. a pin 49 in a transverse slot 41, so that it rotates therewith but can be moved axially thereof to facilitate cleaning of the pump interior. The shaft may be also supported by a bearing 26 and carry a lobed rotor 36, which meshes with a similar rotor 37. <IMAGE>

Description

SPECIFICATION Pump The present invention relates to pumps.

Aithough the invention is not restricted to hygienic pumps, it has particular advantage with such pumps. By hygienic pumps we means pumps which are used to pump liquid, creams and the like and which are particularly used in the foodstuff industry and must be maintained scrupulously clean. Such pumps may be used for pumping cream, milk, beer, or other ingredients of foodstuffs or might be used in the pharmaceutical industry for pumping the constituents of pharmaceutical products. Such pumps must not contaminate the product being pumped and are conventionally, therefore, manufactured of stainless steel and are carefully arranged so that no parts of, for example, the bearings which contain oil, can come into contact with the material being pumped.

Furthermore such pumps must be readily dismantled so as to be cleaned and sterilised as is required at regular intervals.

As a result of these requirements, it has been conventionally arranged that such pumps comprise a pump casing including a pump chamber, and to one side of the pump chamber is provided timing gear means in a gear chamber for driving the pump, one or more shafts protruding through the pump chamber and the rotors of the pump being mounted on the or each shafts. An end cover plate normally closes the pump chamber and the shaft or shafts are normally supported at the end protruding into the gear chamber. The reason for this is that any bearings in the end cover plate would be likely to contaminate the materials in the pump chamber. It is thus preferred to close the pump chamber by means of a generally flat end plate.

Furthermore, problems would arise when removing the end plate to dismantle the pump to clean the chambers if bearings were mounted in the end plate.

However, this has raised problems as to the maximum pressure which can be pumped by such a pump since too great a pressure will flex the shaft or shafts.

The present invention provides, in a hygienic pump of the above type, a rotor, a shaft for driving the rotor and on which the rotor is mounted, and bearings supporting the shaft on both sides of the rotor.

The shaft is supported on one side of the rotor by means of a conventional bearing, and on the other side by a bearing which is preferably provided in an end plate for closing the pump chamber, the bearing supporting a sleeve which, in turn, supports the shaft. Coupling means may be provided to couple the sleeve and the shaft whereby they rotate together but are axially free to move relative to one another.

The invention also provides a pump comprising a rotor, a shaft supporting the rotor, the shaft being supported, at least at one end, in a sleeve, the sleeve being mounted in a bearing, and coupling means being provided to couple the sleeve and the shaft whereby the sleeve and shaft rotate together but are axially free to move relative to one another.

Preferably the coupling means comprises a pin connected to the sleeve and projecting to engage with a slot in the end of the shaft. In this way the sleeve may be withdrawn from the shaft.

There is preferably provided a seal between the end of the sleeve and the rotor and between the sleeve and the shaft.

The bearings are preferably mounted in an end plate attached to a housing for the pump.

The opposite end of the shaft may be supported in bearings which resist axial thrust so that when the sleeve is pulled from the end of the shaft, the shaft is held against axial movement.

A preferred embodiment of the invention will now be described by way of example only and with reference to the accompanying drawings in which: Figure 1 is an external view of a pump according to the invention, and, Figure 2 is a cross section of the pump of Figure 1.

Referring to Figure 1 there is shown an external view of a pump 10 including a gear housing 11 for the pump timing assembly 12 (shown in Figure 2), a housing 13 for the pump chamber 14 (shown in Figure 2) having an inlet and outlet indicated at 1 5 by dotted lines, and an end plate assembly 16. As can be seen from Figure 1 the end plate assembly 1 6 is attached to the remainder of the pump housing by means of bolts 1 7 whereby an end plate assembly 16 can be readily removed in an axial direction.

Referring now to the interior details which are revealed by the axial section shown in Figure 2, the pump 10 includes an input shaft 18, a pump timing assembly which comprises timing gears 21,22, the gears 21,22 driving primary and secondary shafts 23, 24. Both primary and secondary shafts 23, 24 are mounted in the casing by means of double roller bearing assemblies 26, 27 respectively, the two sets of roller bearings in each being inclined to the axis in opposite directions so as to support the primary and secondary shafts 26, 27 against axial movement.

The primary and secondary shafts 26, 27 pass into the pump chamber 14 through a dividing wall 28 in which is mounted respective glands 31,32.

Within the pump chamber 14 each of the primary and secondary shafts include a spline coupling 33, 34 which mounts respective primary and secondary pump rotors 36, 37, in this case the pump rotors being of the three-lobe type.

The side of the pump chamber 14 opposite the dividing wall 28 is closed by an end plate 38, and in Figure 2, it should be noted that only the upper part of the end plate 38 is in section, the lower part comprising a side view. The construction of the end plate 38 will be described with reference to the primary shaft 23, but it should be understood that the construction of the end plate with respect to the secondary shaft is exactly similar.

The end plate includes a collar 39 through which the primary shaft extends. The outer end of the primary shaft 23 includes a transverse slot 41.

Surrounding the part of the primary shaft 23 which extends beyond the pump chamber 14 is a sleeve 42, the inner wall of the sleeve being of substantially the same diameter as the outer diameter of the protruding part of the primary shaft 23 so that there is sliding fit between them.

The inner end face of the sleeve 42 abuts the rotor 36 and there is provided an annular channel 43 in the end face of the sleeve 42 which mounts a neoprene 0 ring 44 which acts as a seal against the rotor 36. A further channel 46 is provided adjacent the inner end of the sleeve 42 on the inside surface thereof, this channel 46 mounting a further neoprene 0 ring seal 47 for sealing the inner end of the protruding part of the primary shaft 23 to the sleeve 42. Surrounding the sleeve 42 is a gland 48 mounted within the collar 39.

Adjacent its outer end, the sleeve 42 includes a pin 49 which extends through the sleeve and transversely across the axis of the sleeve whereby to engage the slot 41.

Furthermore, the outer end of the sleeve 42 is mounted by means of a double roller bearing assembly 51 similar two roller bearing assemblies 26 to the end plate 38.

In use, therefore, the rotor is driven by means of a motor connected to the input shaft 18, the input shaft rotating and thereby driving through the gears 21, 22 the primary and secondary shafts 23, 24. The rotation of these shafts rotates the rotors 36, 37 within the pump chamber 14 which includes the inlet and outlet 15.

The primary and secondary shafts 23, 24, are supported at opposite ends on either side of the pump chamber 14 and thus the pump 10 operates at a higher pressure than if the primary and secondary shafts were supported by means of bearings on one side of the pump chamber 14 only.

The pump 10 is a hygienic pump which is primarily intended for use with degradable material such as milk, cream or pharmaceuticals where purity is required. Thus the pump chamber is sealed by means, of the glands 31,32 and 48, and also by means of the 0 rings 44 and 47.

To disassemble the pump to clean the pump chamber and other parts which come into contact with the material being pumped, it is necessary to release the bolts 17 and to withdraw the end plate 38 in one piece. In this operation the end plate 38 will be moved parallel to the axis of the primary and secondary shafts 23, 24 and the sleeve 42 will disengage from the primary and secondary shafts 23, 24. The rotors 36, 37 can then be withdrawn along the spline coupling 33, 34 and the chamber and rotors cleaned together with the protruding parts of the primary and secondary shafts.

To reassemble, the lobes are re-engaged with the splines on the primary and secondary shafts 23, 24 and the end plate is moved axially into engagement with the remainder of the pump casing. The pin 49 will engage with the slot 41 in the primary shaft (and similarly a pin will engage with a slot in the secondary shaft).

It will be understood that the pin and slot connection allows the sleeve 42 to rotate with the primary shaft and the primary shaft is adequately supported through the sleeve by bearings 51.

The invention is not restricted to the details of the foregoing example.

Claims (9)

1. A pump comprising a rotor, a shaft supporting the rotor, a sleeve supporting the shaft at at least one end, a bearing mounting the sleeve, and coupling means being provided to couple the sleeve and the shaft whereby the sleeve and shaft rotate together but are free to move axially relative to one another to facilitate cleaning.

2. A pump as claimed in claim 1 in which the coupling means comprises a pin connected to the sleeve and projecting to engage with a slot in the end of the shaft.

3. A pump as claimed in claim 1 or claim 2 in which a seal is provided between the end of the sleeve and the rotor and between the sleeve and the shaft.

4. A pump as claimed in any of claims 1 to 3 in which the sleeve mounting bearing is preferably mounted in an end plate attached to a housing for the pump.

5. A pump as claimed in claim 4 in which the opposite end of the shaft is supported in a bearing which resists axial thrust so that when the sieeve is pulled from the end of the shaft the shaft is held against axial movement.

6. A hygienic pump as defined comprising a rotor, a shaft for driving the rotor and on which the rotor is mounted, and bearings supporting the shaft on both sides of the rotor.

7. A hygienic pump as claimed in claim 6 in which the shaft is supported on one side of the rotor by means of a conventional bearing, and on the other side by a bearing which is provided in an end plate for closing the pump chamber, the latter bearing supporting a sleeve which, in turn, supports the shaft.

8. A pump as claimed in claim 7 in which coupling means is provided to couple the sleeve and the shaft whereby they may rotate together but are axially free to move relative to one another.

9. A pump as claimed in claim 1 substantially as hereinbefore described with reference to the accompanying drawings.