GB1563986A

GB1563986A - Centrifuge

Info

Publication number: GB1563986A
Application number: GB1441078A
Authority: GB
Original assignee: COPUS AG; NELCO Ltd
Current assignee: COPUS AG; NELCO Ltd
Priority date: 1978-04-12
Filing date: 1978-04-12
Publication date: 1980-04-02

Description

(54) CENTRIFUGE (71) We, NELCO LIMITED, a British Company, of Guildford Road, Farnham, Surrey, GU9 9PZ, and ARTHUR GORDON Corpus, a British Subject, of Nelco Limited, Guildford Road, Farnham, Surrey, GU9 9PZ, 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: This invention relates to a centrifuge in which the centrifuge bowl, or rotor, which terms are used herein as meaning any rotatably mounted member for accommodating the sample or samples to be spun, is coupled directly or indirectly to an electric motor.

Such arrangements are well known, but commonly the electric motor employed is of such a type that access to the brush gear for maintenance is severely restricted, and involves substantial dismantling of the centrifuge. The reason for this is that the known centnfuges employ motors in which the brushes are arranged radially around a commutator provided at or adjacent the end of the motor shaft opposite that which extends from the motor casing to transmit torque to the centrifuge bowl.

According to the present invention, there is provided a centrifuge comprising a rotor for accommodating a test sample, or samples and a fixedly mounted electric motor having a projecting shaft portion on which the rotor is mounted, the motor having, at or adjacent the end from which said shaft portion projects, a faceplate commutator and brushgear located such that removal of the rotor from said shaft permits access thereto.

The motor may have a casing of which a portion accommodates, and is apertured to expose, said commutator and brushgear.

The brushgear may comprise a plurality of brushes each engaging and bearing upon the commutator in a direction substantially parallel to the motor shaft. The centrifuge rotor may have a central portion provided with a screw threaded bore in which a screw threaded end part of the shaft portion is engaged, the said central portion defining a recess in which at least part of said motor casing portion is disposed.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawing, of which the single figure is a vertical section illustrating the major components of a centrifuge according to the invention.

The centrifuge comprises a housing (not shown), which may be cylindrical and which includes means, in this case an inner circumferential ledge 1, for mounting an electric motor 2 with its shaft 3 projecting in a direction which will extend vertically up, wardly in normal use of the centrifuge. The ledge 1 supports a peripheral flange 4 proS jecting radially from a substantially cylindrical lower portion 5 of the motor casing.

This lower portion 5 houses the stator and rotor windings, while an upper, substantially conical portion 6 of the casing houses the motor commutator and brushgear. The commutator is of the faceplate type consisting of a circular plate 7 having circumferentially spaced radially extending contacts, of which diametrically opposite pairs are contacted sequentially upon rotation of the shaft by a pair of brushes 8 arranged to bear upon the commutator in a direction generally parallel to the shaft. The brushes 8 are positioned symmetrically about the shaft 3 and are fixed relative to the motor casing. The shaft 3 projects axially though a bearing 9 fixed in the apex of the upper casing portion and terminates in a screw-threaded portion 10 which is engaged in a screw-threaded bore 11 in a central part of the centrifuge rotor, or bowl 12. This central part is, in this embodiment substantially conical to fit over and accommodate in its central recess the upper portion of the motor casing.

A multi-blade fan element may be mounted on the motor shaft at the base of the casing to circulate air through the casing and thereby produce a cooling air flow over the motor windings.

As explained hereinbefore, the centrifuge bowl may be of any appropriate shape and configuration to suit the nature of the sample to be spun. Commonly, such a bowl is provided with radially projecting bores to hold test-tubes, but this is only one of a large number of possible arrangements.

Removal of the centrifuge bowl permits inspection of, and access to, the motor brushgear, which is exposed both visually and physically through windows 14 in the upper casing portion 6. Accordingly, the above-described arrangement facilitates maintenance without requiring motor removal for access to the brushgear.

This is particularly advantageous since the centrifuge housing commonly accommodates additional equipment such as dec trical control gear and sometimes refrigerator plant which also has to be removed or disturbed where, as is known, the brushgear is located at the base of the motor.

WHAT WE CLAIM IS: 1. A centrifuge comprising a rotor for accommodating a test sample, or samples and a fixedly mounted electric motor having a projecting shaft portion on which the rotor is mounted, the motor having, at or adjacent the end from which said shaft portion projects, a faceplate commutator and brushgear located such that removal of the rotor from said shaft permits access thereto.

2. A centrifuge according to claim 1 in which the motor has a casing of which a portion accommodates, and is apertured to expose, said commutator and brushgear.

3. A centrifuge according to claim 1 or claim 2 in which the brushgear comprises a plurality of brushes each engaging and bearing upon the commutator in a direction substantially parallel to the motor shaft.

4. A centrifuge according to any preceding claim in which the rotor has a central portion releasably engaged with an end part of said shaft portion.

5. A centrifuge according to claim 4 in which said central portion has a screwthreaded bore in which said end part, which is complementarily screw-threaded, engages.

6. A centrifuge according to claim 2 and any of claims 3 to 5, wherein said rotor is shaped to define a central recess in which at least a part of said motor casing portion is disposed.

7. A centrifuge according to any preceding claim in which said motor also drives a fan for producing a cooling air flow over the motor windings.

8. A centrifuge substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. and configuration to suit the nature of the sample to be spun. Commonly, such a bowl is provided with radially projecting bores to hold test-tubes, but this is only one of a large number of possible arrangements. Removal of the centrifuge bowl permits inspection of, and access to, the motor brushgear, which is exposed both visually and physically through windows 14 in the upper casing portion 6. Accordingly, the above-described arrangement facilitates maintenance without requiring motor removal for access to the brushgear. This is particularly advantageous since the centrifuge housing commonly accommodates additional equipment such as dec trical control gear and sometimes refrigerator plant which also has to be removed or disturbed where, as is known, the brushgear is located at the base of the motor. WHAT WE CLAIM IS:

1. A centrifuge comprising a rotor for accommodating a test sample, or samples and a fixedly mounted electric motor having a projecting shaft portion on which the rotor is mounted, the motor having, at or adjacent the end from which said shaft portion projects, a faceplate commutator and brushgear located such that removal of the rotor from said shaft permits access thereto.