Electric machine

• US 5,534,739 A
• Filed: 07/14/1992
• Issued: 07/09/1996
• Est. Priority Date: 09/14/1990
• Status: Expired due to Fees

• Current Assignee: Magnet-Motor Gesellschaft Fur Magnetmotorische Technik MbH
• Original Assignee: Magnet-Motor Gesellschaft Fur Magnetmotorische Technik MbH
• Inventors: Heidelberg, Gotz, Grundl, Andreas, Ehrhart, Peter
• Primary Examiner(s): Skudy, R.
• Application Number:
  US07/852,204
• Time in Patent Office: 1,456 Days
• Field of Search: 310/179, 310/44, 310/261, 310/262, 310/181, 310/192, 310/203, 310/208, 310/180, 310/181, 310/67 R, 310/216, 310/269, 310/154, 310/254
• US Class Current: 310/179
• CPC Class Codes: H02K 1/146 consisting of a generally annular yoke with salient poles
• CPC Class Codes: H02K 21/22 with magnets rotating around the armatures, e.g. flywheel magnetos
• CPC Class Codes: H02K 29/03 with a magnetic circuit specially adapted for avoiding torque ripples or self-starting problems
• CPC Class Codes: H02K 3/42 Means for preventing or reducing eddy-current losses in the winding heads, e.g. by shielding

Abstract

An electric machine includes an exciter part and an induction part disposed adjacent the exciter part. The exciter part and the induction part define an air gap there-between and are movable relative to one another thereby defining a direction of movement. The induction part includes teeth disposed adjacent one another and projecting in a direction toward the air gap. The teeth define grooves therebetween, each of the teeth having a tooth base and a tooth tip adjacent the air gap. In addition, each of a plurality of the teeth further includes a middle portion having two ends and a constant width defined in a direction along the air gap and perpendicular to the direction of movement; and a pair of tooth widening portions, each of the tooth widening portions having a free end and a transition end and being located at one of the two ends of the middle portion at the transition end thereof for forming one of the plurality of the teeth with the middle portion. Each of the tooth widening portions further has a dimension defined in the direction of movement which decreases from a corresponding end of the middle portion toward the free end, and a width defined in the direction along the air gap and perpendicular to the direction of movement which decreases from a corresponding tooth base toward a corresponding tooth tip.

Claims

1. An electric machine comprising

an exciter part;

an induction part disposed adjacent the exciter part, the exciter part and the induction part defining an air gap therebetween and being moveable relative to one another thereby defining a direction of movement, the induction part further including;

teeth disposed adjacent one another and projecting in a direction toward the air gap, the teeth defining grooves therebetween, each of the teeth having a tooth base, and a tooth tip adjacent the air gap, each of a plurality of the teeth including;

a middle portion having two ends and a constant width defined in a direction along the air gap and perpendicular to the direction of movement; and

a pair of tooth widening portions, each of the tooth widening portions having a free end and a transition end and being located adjacent one of the two ends of the middle portion at the transition end thereof for forming said each of the plurality of the teeth with the middle portion, each of the tooth widening portions further having a dimension defined in the direction of movement which decreases from a corresponding end of the middle portion toward the free end, and a width defined in the direction along the air gap and perpendicular to the direction of movement which decreases from a corresponding tooth base toward a corresponding tooth tip; and

conductor coils disposed within the grooves.

2. The electric machine according to claim 1, wherein the width of said each of the plurality of the teeth decreases gradually from the corresponding tooth base to the corresponding tooth tip such that a magnetic flux density generated by the conductor coils is constant along said each of the plurality of the teeth.

3. The electric machine according to claim 1, wherein the induction part further includes a magnetic return path portion having a width defined in a direction along the air gap and perpendicular to the direction of movement which is substantially equal to a width of the tooth base of said each of the plurality of the teeth, the teeth being disposed on the magnetic return path portion at respective tooth bases thereof.

4. The electric machine according to claim 1, wherein the tooth widening portions are made of an isotropic ferromagnetic material of high electrical resistance.

5. The electric machine according to claim 4, wherein all magnetic flux carrying components of the induction part are substantially made of an isotropic ferromagnetic material of high electrical resistance.

6. The electric machine according to claim 4, wherein the isotropic ferromagnetic material is a plastics bound metal powder material.

7. The electric machine according to claim 1, wherein the exciter part includes permanent magnets.

8. The electric machine according to claim 7, wherein the permanent magnets are made of rare earths and one of cobalt and iron.

9. The electric machine according to claim 1, consisting of an electronically commutated electric motor.

10. The electric machine according to claim 1, further including an electronically commutative power source operatively associated with the induction part, wherein the conductor coils comprise individual coils corresponding to individual ones of said each of the plurality of the teeth and connected to the power source.

11. The electric machine according to claim 10, wherein each of the individual coils are individually connected to the power source.

12. The electric machine according to claim 10, wherein the individual coils are interconnected in groups, each of the groups being connected to the power source.

13. The electric machine according to claim 10, wherein all of the individual coils are interconnected in one group, the group being connected to the power source.

14. The electric machine according to claim 1, wherein the machine is constructed according to flow concentration principles.