Claims
- 1. An electric linear motor for driving a reciprocating load comprising:a stator having a magnetically permeable core with at least one air gap and means for producing a non constant magnetic flux in said stator and said at least one air gap; an armature having a structure which supports at least one permeable magnet of which at least a substantial portion is located in at least one of said at least one air gap, such that the interaction of the magnetic field of said at least one permanent magnet and said non constant flux in said at least one air gap producing a force on said armature, said armature in use being connected to said load and thereby reciprocating with respect to said stator; and energisation means for controlling said means for producing an alternating flux such that at least one end of said at least one permanent magnet passes outside the region of substantially uniform flux density present within said at least one of said at least one air gap during a portion of the reciprocal motion of said armature.
- 2. An electric linear motor as claimed in claim 1 wherein said means for producing an alternating magnetic flux comprises at least one coil wound around a portion of said stator and energised with a non constant voltage.
- 3. An electric linear motor as claimed in claim 2 wherein said energisation means comprises a commutation circuit including a direct current power supply, switching devices connected to said power supply current to said at least one coil and a programmed digital processor including memory and input-output ports, at least one of said ports being connected to said commutation circuit to supply switching control signals thereto.
- 4. An electric linear motor as claimed in claim 1 wherein the displacement of said at least one permanent magnet at which said at least one end of said at least one magnet passes outside said region of substantially uniform flux density is 67% of the maximum displacement.
- 5. A refrigerator which uses a compressor characterized in that the compressor and compressor motor are linear devices and said motor comprises:a stator having a magnetically permeable core with at least one air gap and means for producing a non constant magnetic flux in said stator and said at least one air gap; an armature having a structure which supports at least one permanent magnet of which at least a substantial portion is located in at least one of said at least one air gap, such that the interaction of the magnetic field of said at least one permanent magnet and said non constant flux in said at least one air gap producing a force on said armature, said armature in use being connected to said load and thereby reciprocating with respect to said stator; and energisation means for controlling said means for producing an alternating flux such that at least one end of said at least one permanent magnet passes outside the region of substantially uniform flux density present within said at least one of said at least one air gap during a portion of the reciprocal motion of said armature.
Priority Claims (2)
Number |
Date |
Country |
Kind |
336375 |
Jun 1999 |
NZ |
|
500519 |
Oct 1999 |
NZ |
|
Parent Case Info
This application is a divisional application of Ser. No. 10/018,323, filed on Dec. 11, 2001 and assigned a filing date under 35 U.S.C. §371 of Apr. 5, 2002, which is the United States National Stage patent application of PCT/NZ00/00105 which has an international filing date of Jun. 21, 2000 and which was published in English on Dec. 28, 2000 under International Publication No. WO 00/79671.
US Referenced Citations (25)
Foreign Referenced Citations (8)
Number |
Date |
Country |
248489 |
Nov 1987 |
EP |
0726394 |
Aug 1996 |
EP |
9250449 |
Sep 1997 |
JP |
792511 |
Dec 1980 |
SU |
WO9835428 |
Aug 1998 |
WO |
WO0016482 |
Mar 2000 |
WO |
WO0148379 |
Jul 2001 |
WO |
WO0179671 |
Oct 2001 |
WO |