WO2001061829A1

WO2001061829A1 - Improvements relating to electrical machines

Info

Publication number: WO2001061829A1
Application number: PCT/GB2001/000674
Authority: WO
Inventors: Mervyn Frederick Lear; David Geraint Rhys Jones; Paul Gerald Cox
Original assignee: Redcliffe Magtronics Limited
Priority date: 2000-02-17
Filing date: 2001-02-16
Publication date: 2001-08-23
Also published as: GB0103906D0; GB2359417A; GB0003763D0; AU2001233884A1

Abstract

The advent of powerful rare earth permanent magnets has led to a resurgence of permanent magnet electrical machines, but the assembly of the magnets into the machine, conventionally by hand, has caused difficulties. To meet these, am method and apparatus are proposed in which unmagnetized bodies (1) of rare earth magnetic material are batched together, the bodies are supplied sequentially to a magnetizing station (4) where they are magnetized, they are then automatically removed from the magnetizing station and are then fed to the machine component (7) where they are automatically inserted into accommodating recesses (6) in the machine component. The invention thus avoids the need for manual handling of the magnets.

Description

Improvements Relating to Electrical Machines

Field of the Invention: This invention concerns improvements relating to electrical machines

and in particular concerns permanent magnet electrical machines such as

motors, generators and motor/generators.

Background of the Invention: As is well known, the manufacture of permanent magnet electrical

machines as abovementioned requires the assembly of permanent magnet components into the machine. This has traditionally been an operation that

has been performed manually and with the advent of powerful rare earth permanent magnets, such as Sm-Co (Samarium Cobalt) and Nd-Fe-B

(Neodymium Iron Boron) magnets for example, which provide opportunities

for utilisation of permanent magnet machines which previously were satisfied

with electromagnetic machines, a need arises to adopt a new approach.

Summary of the Invention:

According to the present invention in one of its aspects, a method of

assembling permanent magnets into a machine component comprises the steps

of providing unmagnetized bodies of magnetic material, particularly though

not exclusively a rare earth material such as Sm-Co or Nd-Fe-B

abovementioned, automatically supplying said bodies sequentially to a magnetizing station and magnetizing them at said station, and thereafter

automatically moving the magnetized bodies from the magnetizing station and

automatically inserting them into respective accommodating locations of said

machine component.

The invention also extends to an automatic apparatus for putting the abovementioned method into effect. According to an exemplary embodiment

of this aspect of the invention which will be described more fully hereinafter,

unmagnetized bodies of Sm-Co or Nd-Fe-B rare earth material, which may

have previously been demagnetized by use of equipment substantially as described in WO-A-9829883 and as manufactured and sold by us, are introduced into a means, for example a bowl feeder or like vibratory feeding

device, which is arranged to develop a stack of the bodies comprising a predetermined number of bodies all in the same predetermined orientation.

The stacks of bodies are then processed by feeding bodies from each stack,

one at a time, to a magnetizing station comprising equipment as mentioned

above and substantially as described in WO-A-9829883 where the bodies are indexed from the stack, one at a time, and subjected to magnetization as

described in WO-A-9829883. From the magnetizing station, the magnetized

bodies are supplied one at a time to an assembly station where they are

inserted into respective accommodating recesses of a rotor for a permanent

magnet machine. The entire process is effected automatically and under

automatic control. The recesses abovementioned may have adhesive applied to them prior

to the insertion of the magnets, so as to hold the magnets in place when the

machine is in operation, if the material of the recesses is not ferromagnetic or

if the machine will operate at such a high speed as to warrant the use of

adhesive. Alternatively or additionally the adhesive could be applied to the magnetized bodies, and/or mechanical securing means for the magnetized

bodies could be used.

The arrangement of the above-described embodiment could advantageously be such that the bodies of magnetic material are fed through

the magnetizing equipment, operating in a demagnetizing mode, before they are supplied to the bowl feeder, this ensuring that, when they enter the bowl feeder, they do not carry any remanent magnetism such as might interfere with

its proper operation. The equipment that is described in WO-A-9829883 has

both demagnetizing and magnetizing modes, and the arrangement of the embodiment can advantageously be such that magnetic bodies received from

their manufacturer are first input to a magnetizing/demagnetizing station

operating in a demagnetizing mode, then go to the bowl feeder and then return

to the magnetizing/demagnetizing station now operating in a magnetizing

mode. Alternatively, the magnetic state of the bodies can just be checked

before they are processed further.

The above and further features of the invention are set forth in the

appended claims and will be well understood from consideration of the

following description given with reference to the accompanying drawing. Description of the Drawing:

The single drawing figure is a schematic representation of an

exemplary embodiment of the present invention.

Detailed Description of the Embodiment:

Referring to the drawing, the schematically illustrated system performs

the function of loading rare earth magnets into recesses formed in flywheels for use in permanent magnet electric machines such as motors, generators and

motor generators. Not shown in the drawing is an input stage where demagnetized rare earth magnetic bodies are stacked and oriented

automatically, for example by means of a device such as a bowl feeder.

The assembled stacks of demagnetized bodies, there being 16 bodies

in each stack in this particular embodiment, are automatically supplied to a dispensing device which includes an actuator (not shown) controlled to

dispense the bodies 1 one at a time from the stack 2 into the magnetizing coil

4 of a magnetizing/demagnetizing apparatus 5 as mentioned hereinbefore and

substantially as described in WO-A-9829883 which is operating in its

magnetizing mode. The magnetized bodies are then moved from the coil 4 by

the actuator and arrive at a loading position where they are inserted into a

respective recess 6 in a flywheel 7 which is positioned to receive the

respective body by means of a loading station 8. As previously mentioned, an

adhesive may be used to secure the bodies 1 in the recesses 6. The loading station 8 has provision for the mounting of first and

second flywheels 7-1 and 7-2 each on an indexable hub (not shown) enabling

the flywheels to be controUably rotated in stepwise manner for locating their

recesses successively in registry with the loading position for insertion of a

magnetized body 1. The operation of the indexing mechanism in the loading station 8 is synchronized with the operation of the actuator and of the

magnetizing apparatus 5 by electronic control means (not shown). The

loading station 8 also provides for automatic movement of second flywheel 7- 2 into registry with the loading position once the loading of magnetized bodies

into the recesses of the first flywheel 7-1 has been completed, the first filled flywheel 7-1 then being removed and replaced by an empty flywheel which will be moved automatically into loading position once flywheel 7-2 has been

filled.

The operation of the invention will be clear from the foregoing and it will be appreciated that the invention proposes a fully automated system

designed to accept high strength magnets, such as the rare earth Nb-Fe-B

magnet material previously referred to or Sm-Co magnets for example, from

their supplier/manufacturer, demagnetize them to eliminate residual effects or

at least check them to determine their magnetic status, magnetize them

appropriately and load them into flywheels or other components substantially

without human intervention.

Recent improvements in the properties of Nd-Fe-B and Sm-Co

magnets, coupled with the emergence of new designs for large motors, generators and motor generators, has meant that the magnetization and

assembly of such magnets is becoming increasingly safety critical. This is

because the magnetic forces and resulting potential mechanical forces are

related to the magnetic properties and the size, especially the surface area, of

the magnets involved. Unless great care is taken in the machanical handling of these magnets in their magnetized state, there is a great risk to personal

safety through potential uncontrolled movement of powerful magnets. The

system and method of the present invention enables this problem to be

overcome or at least substantially reduced. The invention having been described by reference to a specific embodiment, it is to be well understood that the embodiment is exemplary

only and that modifications and variations are possible without departure from

the spirit and scope of the invention. For example, it might be possible to place the magnets in the recesses, with or without use of adhesive, and then

magnetize them in situ rather than sliding in already magnetized bodies as described hereinbefore. This might be difficult and possibly impractical for

large rare earth machines, but it is theoretically possible.

Claims

Claims:

1. A method of assembling permanent magnets into a machine component, said method comprising: providing unmagnetized or substantially unmagnetized bodies of a magnetic material; automatically supplying said bodies sequentially to a magnetizing station and magnetizing them at said station; and automatically removing the magnetized bodies from the magnetizing station and automatically inserting them into respective accommodating locations of said machine component.

2. A method as claimed in claim 1 wherein said providing step includes demagnetization of bodies of magnetic material received from a supplier.

3. A method as claimed in claim 1 or 2 wherein said magnetic material comprises rare earth material such as Nd-Fe-B or Sm-Co.

4. A method as claimed in any preceding claim wherein said machine component comprises a rotor for a motor, a generator or a motor/generator.

5. A method as claimed in any preceding claim except that the unmagnetized bodies are automatically inserted into the machine component and then are magnetized in situ.

6. An apparatus for carrying out a method as claimed in any of the preceding claims.

7. An apparatus for assembling permanent magnets into a machine component, said apparatus comprising: means for accepting unmagnetized or substantially unmagnetized magnetic bodies in batches each comprising a predetermined number of bodies similarly oriented in the batch; means for supplying bodies from a batch of the same sequentially to a magnetizing station; means for taking the magnetized bodies from said magnetizing station and inserting them into respective locations of said machine component; and control means synchronizing the operation of said batching means, said supplying means, said magnetizing station and said taking and inserting means.

8. An apparatus as claimed in claim 7 wherein means are provided for demagnetizing magnetic bodies received from a supplier and to supply said demagnetized magnetic bodies to said arranging means.

9. An apparatus as claimed in claim 8 wherein said demagnetizing means is provided at said magnetizing station, one and the same means operating in different modes being provided for demagnetizing and for magnetizing said magnetic bodies.

10. An apparatus for assembling permanent magnets into a machine component, said apparatus comprising: means for accepting unmagnetized or substantially unmagnetized bodies in batches; means for supplying bodies sequentially from a batch of the same and inserting them into respective locations of said machine component; means for magnetizing said bodies in situ in said machine component; and control means synchronizing the operation of said batching means, said supplying and inserting means and said magnetizing means.