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US 6,479,911 B1Granted
PM type stepping motor
AssigneeSeiko Epson Corporation
InventorsYoshikazu Koike, Akihiko Ikegami
Life of this patent
Estimating the term…
Abstract
A PM type stepping motor is provided capable of further reducing the higher harmonic component of detent torque. n sets of teeth groups, each consisting of m stator polar teeth, are set for each of an outer yoke and an inner yoke, and the pitch P2 of the stator polar teeth, the pitch P3 of the teeth groups, and the pitch P1 of the N and S poles of permanent magnets are set such that the relationship: P2≠P1, P3≠m·P1, and P3≠m·P2 holds true, where P1, P2 and P3 are electrical angles, and m and n are integers equal to or larger than 2.
Claims18
A PM type stepping motor, comprising:
- a rotor in which N and S magnetic pole pairs of permanent magnets are alternately arranged circumferentially on an outer peripheral surface of the rotor at a fixed pitch P1;
- a stator surrounding the rotor,
- the stator having a stator unit equipped with an outer yoke and an inner yoke, the outer yoke and the inner yoke having comb-teeth-like stator pole teeth in an inner periphery of the outer yoke and the inner yoke,
- each of the outer yoke and the inner yoke being equipped with n sets of teeth groups, each set consisting of m stator polar teeth, and the stator polar teeth in the teeth groups having a pitch of P2 and the teeth groups having a pitch of P3, where:
- P2≠P1,
- P3≠m·P1, and
- P3≠m·P2,
- with P1, P2 and P3 being electrical angles, and m and n being integers equal to or larger than 2;
- and
- a constraining member provided in an outer periphery in a vicinity of a forward end of the stator polar teeth formed of a non-magnetic material and constraining the stator polar teeth.
7 more elements
A PM type stepping motor, comprising:
- a rotor in which N and S magnetic pole pairs of permanent magnets are alternately arranged circumferentially on an outer peripheral surface of the rotor at a fixed pitch P1;
- and
- a stator surrounding the rotor,
- the stator having a stator unit equipped with an outer yoke and an inner yoke, the outer yoke and the inner yoke having comb-teeth-like stator pole teeth in an inner periphery of the outer yoke and the inner yoke,
- each of the outer yoke and the inner yoke being equipped with n sets of teeth groups, each set consisting of m stator polar teeth, and the stator polar teeth in the teeth groups having a pitch of P2 and the teeth groups having a pitch of P3, where:
- P2≠P1,
- P3≠m·P1, and
- P3≠m·P2,
- with P1, P2 and P3 being electrical angles, and m and n being integers equal to or larger than 2, and where:
- P2=P1 {1±i/u}, and
- P3=P1 {m±i′/(n·ν′)},
- with u being a positive integer, i being a positive integer which is not a multiple of u, i′ being a positive integer which is not a multiple of n, and ν′ being an order of main higher harmonic reduced.
9 more elements
A PM type stepping motor, comprising:
- a rotor in which N and S magnetic pole pairs of permanent magnets are alternately arranged circumferentially on an outer peripheral surface of the rotor at a fixed pitch P1;
- and
- a stator surrounding the rotor,
- the stator having a stator unit equipped with an outer yoke and an inner yoke, the outer yoke and the inner yoke having comb-teeth-like stator pole teeth in an inner periphery of the outer yoke and the inner yoke,
- each of the outer yoke and the inner yoke being equipped with n sets of teeth groups, each set consisting of m stator polar teeth, and the stator polar teeth in the teeth groups having a pitch of P2 and the teeth groups having a pitch of P3, where:
- P2≠P1,
- P3≠m·P1, and
- P3≠m·P2,
- with P1, P2 and P3 being electrical angles, and m and n being integers equal to or larger than 2, and where:
- P2=P1 {1±i/(m·ν)}, and
- P3=P1 {m±i′/(n·ν′)},
- with ν and ν′ being degrees of main higher harmonics reduced, i being a positive integer which is not a multiple of m, and i′ being a positive integer which is not a multiple of n.
9 more elements
A PM type stepping motor, comprising:
- a rotor in which N and S magnetic pole pairs of permanent magnets are alternately arranged circumferentially on an outer peripheral surface of the rotor at a fixed pitch P1;
- a stator surrounding the rotor,
- the stator having a construction in which a plurality of stator units equipped with outer yokes and inner yokes are stacked together, and the outer yokes and the inner yokes having comb-teeth-like stator polar teeth in an inner periphery of the outer yokes and the inner yokes, each of the outer yokes and the inner yokes being equipped with n sets of teeth groups, each set consisting of m stator polar teeth, and the stator polar teeth in the teeth groups having a pitch of P2 and the teeth groups having a pitch of P3,
- an axial gap being formed between base portions of the stator polar teeth of axially adjacent stator units so that the base portions do not come into contact with each other;
- and where
- P2=P1 {1±i/u}, and
- P3=P1 {m±i′/(n·ν′)},
- with u being a positive integer, i being a positive integer which is not a multiple of u, i′ being a positive integer which is not a multiple of n, and ν′ being an order of main higher harmonic reduced.
5 more elements
A PM type stepping motor, comprising:
- a rotor in which N and S magnetic pole pairs of permanent magnets are alternately arranged circumferentially on an outer peripheral surface at a fixed pitch;
- a stator surrounding the rotor, the stator having a stator unit equipped with an outer yoke and an inner yoke having comb-teeth-like stator polar teeth in an inner periphery of the outer yoke and the inner yoke;
- and
- a constraining member provided between a vicinity of the forward end of the stator polar teeth and exciting coil formed of a non-magnetic material and constraining the stator polar teeth.
1 more element
A PM type stepping motor, comprising:
- a rotor in which N and S magnetic pole pairs of permanent magnets are alternately arranged circumferentially on an outer peripheral surface at a fixed pitch P1;
- a stator surrounding the rotor, the stator comprising covers and a stator unit equipped with an outer yoke and an inner yoke being inserted between the covers from an axial direction, and the outer yoke and the inner yoke having comb-teeth-like stator polar teeth in an inner periphery, each of the outer yoke and the inner yoke being equipped with n sets of teeth groups, each set consisting of m stator polar teeth, and the stator polar teeth in the teeth groups having a pitch of P2 and the teeth groups having a pitch of P3, where:
- a cover collision preventing structure that prevents collision of the stator polar teeth with the covers;
- and where
- P2=P1 {1±i/u}, and
- P3=P1 {m±i′/(n·ν′)},
- with u being a positive integer, i being a positive integer which is not a multiple of u, i′ being a positive integer which is not a multiple of n, and ν′ being an order of main higher harmonic reduced.
4 more elements
A PM type stepping motor, comprising:
- a rotor in which N and S magnetic pole pairs of permanent magnets are alternately arranged circumferentially on an outer peripheral surface at a fixed pitch P1;
- a stator surrounding the rotor, the stator having a stator unit equipped with an outer yoke and an inner yoke, and the outer yoke and the inner yoke having comb-teeth-like stator polar teeth in an inner periphery, each of the outer yoke and the inner yoke being equipped with n sets of teeth groups, each set consisting of m stator polar teeth, and the stator polar teeth in the teeth groups having a pitch of P2 and the teeth groups having a pitch of P3,
- ribs integrally formed by press molding at base portions of the stator polar teeth;
- and where
- P2=P1 {1±i/u}, and
- P3=P1 {m±i′/(n·ν′)},
- with u being a positive integer, i being a positive integer which is not a multiple of u, i′ being a positive integer which is not a multiple of n, and ν′ being an order of main higher harmonic reduced.
4 more elements
A PM type stepping motor, comprising:
- a rotor in which N and S magnetic pole pairs of permanent magnets are alternately arranged circumferentially on an outer peripheral surface at a fixed pitch;
- a stator surrounding the rotor, the rotor having a rotation shaft rotatably supported by members on a stator side at two positions axially separated from each other, the stator having a stator unit equipped with an outer yoke and an inner yoke, and the outer yoke and the inner yoke having comb-teeth-like stator polar teeth in an inner periphery;
- and
- rotor side members using elastic members capable of elastic deformation in the axial direction that support two positions axially separated from each other of the rotation shaft of the rotor.
1 more element
Dependencies are inferred from the claim text.