Linear motor with improved cooling

• US 5,783,877 A
• Filed: 04/12/1996
• Issued: 07/21/1998
• Est. Priority Date: 04/12/1996
• Status: Expired due to Term

• Current Assignee: Anorad Corporation (Rockwell Automation, Inc.)
• Original Assignee: Anorad Corporation (Rockwell Automation, Inc.)
• Inventors: Chitayat, Anwar
• Primary Examiner(s): Stephan, Steven L.
• Assistant Examiner(s): MULLINS, BURTON S
• Application Number:
  US08/631,343
• Time in Patent Office: 830 Days
• Field of Search: 310/12, 310/13, 310/14, 310/52, 310/54, 310/58, 310/59, 310/60 R, 310/64, 310/16
• US Class Current: 310/12.33
• CPC Class Codes: H02K 41/03 Synchronous motors; Motors moving step by step; Reluctance motors H02K41/035 takes precedence
• CPC Class Codes: H02K 9/00 Arrangements for cooling or ventilating channels or ducts in parts of the magnetic circuit H02K1/20, H02K1/32; channels or ducts in or between conductors H02K3/22, H02K3/24
• CPC Class Codes: H02K 9/24 Protection against failure of cooling arrangements, e.g. due to loss of cooling medium or due to interruption of the circulation of cooling medium

Abstract

A linear motor has an epoxy core armature with dual cold plates attached to a top and a bottom of the epoxy core armature to effect cooling of the epoxy core armature. The use of dual cold plates with circulating cooling fluid reduces heat build up by providing paths of high thermal conductivity from any point in the epoxy core armature to the cold plates. Another embodiment of the invention employs ceramic heat sink plates laminated to sides of the epoxy core armature to increase the thermal conductivity and the resultant power dissipation capacity of the epoxy core armature without introducing magnetic or electrically conducting materials. Other embodiments of the invention utilize cold plates formed from extrusions of aluminum or ceramic materials. Still other embodiments have forced air cooling wherein a U-frame of the linear motor has longitudinal flexible seals and air is forced through the U-frame in which the epoxy core armature travel. Yet another embodiment has a U-frame with ducts formed therein through which air is force. Orifices connect the ducts to an interior of the U-frame through which the epoxy core armature travels.

Claims

1. A linear motor comprising:

a magnet plate having a plurality of magnets of alternating polarity affixed thereto;

an armature block having at least one coil encapsulated in a settable resin;

said armature block containing substantially no magnetic material;

a first cold plate affixed to a bottom portion of said armature block;

a second cold plate affixed to a top portion of said armature block;

said armature block having a ceramic heat sink plate affixed upon a side thereof;

said ceramic heat sink plate extending to make thermal contact with each of said first and second cold plates such that heat is effectively removed from a middle portion of said armature block; and

means for allowing supply of a cooling liquid to said first and said second cold plates such that heat dissipated by said at least one coil in said armature block is removed by said cooling liquid.

2. A linear motor according to claim 1 wherein said first and second cold plates each include a member having a slot into which said top and bottom portions of said armature block are affixed, respectively, and tubing incorporated substantially throughout perimeters of said first and second cold plates.

3. A linear motor according to claim 1 wherein:

said first and second cold plates each include an extrusion member having a slot into which said top and bottom portions of said armature block are affixed, respectively, and integral passages, parallel to said slot, for carrying cooling liquid; and

passage connecting means for interconnecting said integral passages so as to provide a complete fluid circuit, in each of said first and second cold plates, from a cooling fluid input to a cooling fluid output thereof.

4. A linear motor according to claim 3 wherein said extrusion members are formed from non-magnetic and non-electrically conductive materials such as ceramics including one of silicon carbide and aluminum nitride.

5. A linear motor according to claim 1 wherein said at least one coil is a flat coil having windings formed from wire having a rectangular cross section.

6. A linear motor as in claim 1, wherein said first and second cold plates are of material with a higher thermal conductivity than a thermal conductivity of encapsulating material of said armature block.

7. A linear motor comprising:

a magnet plate having a plurality of magnets of alternating polarity affixed thereto;

an armature block having at least one coil and a ceramic substrate heat sink;

said at least one coil having a center aperture;

said ceramic substrate heat sink having a plate surface and a protrusion extending from said plate surface and into said center aperture of said at least one coil positioned upon said plate surface;

said at least one coil and said ceramic substrate heat sink being encapsulated in a settable resin;

said armature block containing substantially no magnetic material;

heat sink means for sinking heat carried by said ceramic substrate heat sink from said at least one coil;

said heat sink means includes a cold plate affixed to a lower portion of said armature block; and

said heat sink means includes means for allowing supply of a cooling liquid to said cold plate such that heat dissipated by said at least one coil in said armature block is removed by said cooling liquid.

8. A linear motor according to claim 7, further comprising:

a magnet plate having a plurality of magnets of alternating polarity affixed thereto;

an armature block having at least one coil and a ceramic substrate heat sink;

said heat sink means including a second cold plate;

said second cold plate being affixed to an upper portion of said armature block; and

said heat sink means including means for allowing supply of a cooling liquid to said second cold plate such that heat dissipated by said at least one coil in said armature block is removed by said cooling liquid.

9. A linear motor according to claim 8 wherein

said ceramic substrate heat sink includes a base portion and a top portion;

said base portion is affixed in said first cold plate and said top portion is affixed in said second cold plate; and

said base portion and said top portion have a thickness greater than said ceramic substrate heat sink at said plate surface so as to decrease a thermal junction resistance between said base and top portions and said first and second cold plates, respectively.

10. A linear motor according to claim 7 further comprising said armature block including a ceramic cover plate such that said at least one coil is interposed between said ceramic cover plate and said ceramic substrate heat sink.

11. A linear motor, comprising:

a magnet plate having a plurality of magnets of alternating polarity affixed thereto;

an armature block having at least one coil and a ceramic substrate heat sink;

said at least one coil having a center aperture;

said ceramic substrate heat sink having a plate surface and a protrusion extending from said plate surface and into said center aperture of said at least one coil positioned upon said plate surface;

said at least one coil and said ceramic substrate heat sink being encapsulated in a settable resin;

said armature block containing substantially no magnetic material;

heat sink means for sinking heat carried by said ceramic substrate heat sink from said at least one coil;

said heat sink means includes a cold plate affixed to a lower portion of said armature block; and

said heat sink means includes means for allowing supply of a cooling liquid to said cold plate such that heat dissipated by said at least one coil in said armature block is removed by said cooling liquid;

said ceramic substrate heat sink includes a base portion;

said base portion is affixed in said cold plate; and

said base portion has a thickness greater than said ceramic substrate heat sink at said plate surface so as to decrease a thermal junction resistance between said base portion and said cold plate.

12. A linear motor comprising:

a magnet plate having a plurality of magnets of alternating polarity affixed thereto;

an armature block having at least one coil and a ceramic substrate heat sink;

said ceramic substrate heat sink being located on a side of said armature block;

said ceramic substrate heat sink having a recess for accepting said at least one coil;

said at least one coil and said ceramic substrate heat sink being encapsulated in a settable resin;

said armature block containing substantially no magnetic material;

heat sink means for sinking heat carried by said ceramic substrate heat sink from said at least one coil; and

said ceramic substrate heat sink contacting at least a portion of said heat sink means, whereby heat is effectively removed from a middle portion of said armature block.

13. A linear motor according to claim 12 further comprising:

said at least one coil having a center aperture; and

said recess having a bottom surface and a protrusion extending from said bottom surface and into said center aperture of said at least one coil positioned upon said plate surface.

14. A linear motor according to claim 12 wherein:

said heat sink means includes a cold plate affixed to a lower portion of said armature block; and

said heat sink means includes means for allowing supply of a cooling liquid to said cold plate such that heat dissipated by said at least one coil in said armature block is removed by said cooling liquid.

15. A linear motor according to claim 12 wherein:

said heat sink means includes a first and a second cold plate;

said first cold plate is affixed to a lower portion of said armature block;

said second cold plate is affixed to an upper portion of said armature block; and

said heat sink means includes means for allowing supply of a cooling liquid to said first and said second cold plates such that heat dissipated by said at least one coil in said armature block is removed by said cooling liquid.

16. A linear motor according to claim 15 further comprising:

said at least one coil having a center aperture; and

said recess having a bottom surface and a protrusion extending from said bottom surface and into said center aperture of said at least one coil positioned upon said plate surface.

17. A linear motor comprising:

a U-frame having opposing inner walls, joined by a bridge portion at a closed end, defining a longitudinal cavity;

said opposing inner walls having a plurality of magnets of alternating polarity affixed thereto;

an armature block having at least one coil encapsulated in a settable resin and traveling within said U-frame;

said armature block containing substantially no magnetic material;

said U-frame having a duct extending throughout a longitudinal length thereof;

said duct having orifices connecting said duct with said longitudinal cavity;

said duct and said orifices permitting cooling air to be introduced into said longitudinal cavity such that heat generated in said armature block is removed by said cooling air;

a cold plate affixed to a bottom portion of said armature block;

a ceramic heat sink plate affixed to a side of said armature block and in thermal contact with said cold plate, such that heat is effectively removed from a middle portion of said armature block;

means for allowing supply of a cooling liquid to said cold plate such that heat dissipated by said at least one coil in said armature block is removed by said cooling liquid; and

said orifices directing a flow of cooling air at a top portion of said armature block furthest from said first cold plate.

18. A linear motor according to claim 17 further comprising:

said armature block having a ceramic heat sink plate affixed upon a side thereof,

said ceramic heat sink plate extending to make thermal contact with said cold plate such that heat is effectively removed from a middle portion of said armature block.

19. A linear motor according to claim 17 further comprising:

said armature block having a ceramic substrate heat sink;

said at least one coil having a center aperture; and

said ceramic substrate heat sink having a plate surface and a protrusion extending from said plate surface into said center aperture of said at least one coil positioned upon said plate surface.

20. A linear motor according to claim 17 further comprising:

an armature block having a ceramic substrate heat sink;

said ceramic substrate heat sink having a recess for accepting said at least one coil;

said cold plate sinking heat carried by said ceramic substrate heat sink from said at least one coil.

21. A method of making a linear motor, comprising the steps of:

positioning a frame with permanent magnets adjacent an armature element having electrical coils and a duct in such a way as to form a space between said frame and said armature element;

forming a passage in said armature passing from one surface of said armature not adjacent said space through said duct and into said space thereby forming a passage opening to said space at a first opening of said passage and opening through said one surface not adjacent said space at a second opening of said passage;

sealing said second opening so that said duct communicates with said space without leaking through said second opening;

injecting air into said space through said duct, through said passage and out through said first opening.