US4871934A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Induction motor
Assignee: NEC Corp
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Filing: 1987-04-03
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Granted: 1989-10-03
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Expires: 2007-04-03
Abstract
Abstract Stator slots are skewed relative to rotor slots with a skew amount comprising an integer multiple of a stator electrical angle of 60°, thereby minimizing a torque ripple which is an integer multiple of six times of a primary frequency of electrical energy.
Inventors
- 👤 Kiyokazu Okamoto
- 👤 Tetsuo Endo
- 👤 Yukio Miyamoto
- 👤 Yoshiharu Suzuki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 05:16
CPC Classifications
H; H02; H02K; H02K17/00; H02K17/02; H02K17/16; H02K1/00; H02K1/06; H02K1/12; H02K1/16; H02K1/22; H02K1/26; H02K2201/00; H02K2201/06
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
160 words
An induction motor comprising: a stator having slots for accommodating a primary winding therein, said stator being adapted to generate a rotary magnetic flux upon application of electrical energy to said primary winding; and a rotor, having slots for accommodating a secondary winding comprising one of the groups consisting of coils and a squirrel-cage circuit to generate a torque by an interaction between the rotary magnetic flux crossing said secondary winding and a secondary current flowing in said secondary winding due to electromagnetic induction by said stator when the electrical energy is applied to said induction motor; said stator slots and said rotor slots being skewed relative to each other by an amount of an integer multiple of a stator electrical angle of 60° between ends of an axial effective length of a torque generation portion of said rotor, thereby minimizing a torque ripple which is an integer multiple of six times of the primary frequency of the electrical energy.
Claim 2
Dependent Claim
160 words
An induction motor comprising: a stator having slots for accommodating a primary winding therein, said stator being adapted to generate a rotary magnetic flux upon application of electrical energy to said primary winding; and a rotor, having slots for accommodating a secondary winding comprising one of the groups consisting of coils and a squirrel-cage circuit to generate a torque by an interaction between the rotary magnetic flux crossing said secondary winding and a secondary current flowing in said secondary winding due to electromagnetic induction by said stator when the electrical energy is applied to said induction motor; said stator slots and said rotor slots being skewed relative to each other by an amount of an integer multiple of a stator electrical angle of 60° between ends of an axial effective length of a torque generation portion of said rotor, thereby minimizing a torque ripple which is an integer multiple of six times of the primary frequency of the electrical energy.
Claim 3
Dependent Claim
35 words
A motor according to claim 1, wherein said stator slots are parallel to an axial direction of a rotating shaft, and said rotor slots are skewed relative to said stator slots along the axial direction.
Claim 4
Dependent Claim
35 words
A motor according to claim 1, wherein said rotor slots are parallel to an axial direction of a rotating shaft, and said stator slots are skewed relative to said rotor slots along the axial direction.
Claim 5
Dependent Claim
54 words
A motor according to claims 1, 2, or 3, wherein the amount of skew is equal to an integer multiple of a stator slot pitch, whereby both a torque ripple caused by the slots as well as the torque ripple which is an integer multiple of six times of the primary frequency are minimized.
Claim 6
Dependent Claim
29 words
A motor according to claim 2, wherein said rotor slots are skewed relative to said stator slots by an amount of an integer multiple of a stator slot pitch.
Claim 7
Dependent Claim
29 words
A motor according to claim 3, wherein said stator slots are skewed relative to said rotor slots by an amount of an integer multiple of a stator slot pitch.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-10-02 | 1993-04-03 | 1993-10-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-10-02 | 1997-04-03 | 1997-10-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-10-02 | 2001-04-03 | 2001-10-03 | $7700.00 | Window Closed / Lapsed |