Vibration-proof stepping motor with built-up stator

• US 5,187,400 A
• Filed: 07/07/1992
• Issued: 02/16/1993
• Est. Priority Date: 11/16/1990
• Status: Expired due to Fees

• Current Assignee: ASMO Company Limited (DENSO Corporation)
• Original Assignee: ASMO Company Limited (DENSO Corporation)
• Inventors: Kurata, Kazuyuki
• Primary Examiner(s): Stephan, Steven L.
• Assistant Examiner(s): NGUYEN, MATTHEW VAN
• Application Number:
  US07/908,873
• Time in Patent Office: 224 Days
• Field of Search: 310/49 R, 310/51, 310/89, 310/91, 310/99
• US Class Current: 310/49.12
• CPC Class Codes: H02K 3/525 Annular coils, e.g. for cores of the claw-pole type
• CPC Class Codes: H02K 37/14 with magnets rotating within the armatures
• CPC Class Codes: H02K 5/16 Means for supporting bearings, e.g. insulating supports or means for fitting bearings in the bearing-shields magnetic bearings H02K7/09
• CPC Class Codes: H02K 7/116 with gears

Abstract

A vibration-proof stepping motor of the type having a stator of a built-up construction is disclosed, wherein the stator is composed of a single socket-like stator core member and a plurality of plug-like stator core members assembled with the socket-like stator core member in stacking relation, with stator coils disposed between adjacent pairs of the stator core members. An upper end of the plug-like stator core members which are stacked in the socket-like stator core member together with the stator coils projects from an upper end of the socket-like stator core member. A bobbin of each of the stator coils is resiliently deformable so that the stator is firmly retained by and between upper and lower housings in a compressed condition when the housings are joined together. With the stator thus retained, the stepping motor is free from vibration which would otherwise lead to generation of unpleasant operation noise.

Claims

1. A vibration-proof stepping motor of the type having a stator of a built-up construction, comprising:

a lower housing having an internal space;

an upper housing disposed in confrontation to said lower housing; and

a stator and a rotor disposed between said upper and lower housings, said stator being composed of at least two stator cores disposed one above another in said internal space and each including a pair of stator core members and a coil disposed between said stator core members, said rotor being rotatably disposed in said stator and having a rotor shaft and a rotor body integral with said rotor shaft,

wherein said stator is composed of a socket-like stator core member having a plurality of upstanding magnetic poles and a plurality plug-like stator core members each having a plurality of upstanding magnetic poles, said pluglike stator core members being stacked in said socket-like stator core members with said coil disposed between each adjacent pair of said stator core members,

wherein said coil includes a bobbin, windings wound around said bobbin and a plurality of terminals electrically connected with said windings, said bobbin having opposite end flanges between which said windings are disposed, one of said end flanges having a mounting portion carrying thereon said terminals,

wherein said one end flange has a first projection and a lower damper projection, said first projection having a height larger than the thickness of the material of said plug-like stator core members,

wherein the other of said end flanges has at least one second projection having a height smaller than the thickness of the material of said stator core members, and

wherein said plug-like stator core members stacked in said socket-like stator core members together with said coils have an upper end projecting from an upper end of said socket-like stator core member.

2. A vibration-proof stepping motor according to claim 1, wherein said coils are stacked such that said one end flange of each of said coils confronts said one end flange of the adjacent coil.

3. A vibration-proof stepping motor according to claim 1, wherein said lower housing has a side wall defining said internal space of said lower housing, and at least one rib projecting from said side wall into said internal space of said lower housing, said rib being pressfitted with a side wall of said socket-like stator core member.

4. A vibration-proof stepping motor according to claim 1, wherein said upper housing has a bearing hole rotatably supporting an end portion of said rotor shaft, and an annular rib concentric with said bearing hole and projecting from an inside surface of said upper housing into engagement with an upper end of said stator.

5. A vibration-proof stepping motor according to claim 1, wherein said bobbin is formed of a resiliently deformable material.

7. A vibration-proof stepping motor according to claim 2, wherein said coils are stacked such that said one end flange of each of said coils confronts said one end flange of the adjacent coil.

8. A vibration-proof stepping motor according to claim 2, wherein said lower housing has a side wall defining said internal space of said lower housing ,and at least one rib projecting from said side wall into said internal space of said lower housing, said rib being press-fitted with a side wall of said socket-like stator core member.

9. A vibration-proof stepping motor according to claim 2, wherein said upper housing has a bearing hole rotatably supporting an end portion of said rotor shaft, and an annular rib concentric with said bearing hole and projecting from an inside surface of said upper housing into engagement with an upper end of said stator.

10. A vibration-proof stepping motor according to claim 2, wherein said bobbin is formed of a resiliently deformable material.

6. A vibration-proof stepping motor of the type having a stator of a built-up construction, comprising:

a lower housing having an internal space;

an upper housing disposed in confrontation to said lower housing; and

a stator and a rotor disposed between said upper and lower housings, said stator being composed of at least two stator cores disposed one above another in said internal space and each including a pair of stator core members and a coil disposed between said stator core members, said rotor being rotatably disposed in said stator and having a rotor shaft and a rotor body integral with said rotor shaft,

wherein said lower housing has a bottom surface and a first locking projection on said bottom surface,

wherein said stator is composed of a socket-like stator core member having a plurality of upstanding magnetic poles and a plurality plug-like stator core members each having a plurality of upstanding magnetic poles, said pluglike stator core members being stacked in said socket-like stator core members with said coil disposed between each adjacent pair of said stator core members, said socket-like stator core member further having a first guide hole and a second guide hole having a diameter different to the diameter of said first guide hole, said first guide hole being fitted with said first locking projection,

wherein said coil includes a bobbin, windings wound around said bobbin and a plurality of terminals electrically connected with said windings, said bobbin having opposite end flanges between which said windings are disposed, one of said end flanges having a mounting portion carrying thereon said terminals, said one end flange having a second locking projection and a low damper projection, said second projection having a height larger than the thickness of the material of said plug-like stator core members, the other of said end flanges having at least one third projection having a height smaller than the thickness of the material of said stator core members,

wherein said third locking projection is fitted with said second guide hole of said socket-like stator core member,

wherein each of said plug-like stator core members has a third guide hole, and said second locking projection is fitted with said third guide hole of an adjacent one of said plug-like stator core members, with said damper projection disposed between said other end flange of each bobbin and said adjacent plug-like stator core member,

wherein said plug-like stator core members stacked in said socket-like stator core members together with said coils have an upper end projecting from an upper end of said socket-like stator core member, and

wherein said stator is held by and between said upper and lower housings in a compressed condition.

11. A vibration-proof stepping motor of the type having a stator of a built-up construction, comprising:

lower housing having a first internal space;

an upper housing having a second internal space;

a support plate held between said upper and lower housings and having a plurality of support shafts projecting into said second internal space;

a stator and a rotor disposed between said upper and lower housings, said rotor being rotatably disposed in said stator and having a rotor shaft and a rotor body integral with said rotor shaft, said rotor shaft having a pinion at an output end thereof;

a reduction gear disposed in said second internal space and held between said upper housing and said support plate for lowering the output speed of said rotor shaft;

said reduction gear including first and second gears rotatably supported on said support shafts, respectively, and held in mesh with each other, said first gear being also held in mesh with said pinion of said rotor shaft;

said stator being composed of at least two stator cores disposed one above another in said first internal space and each including a pair of stator core members and a coil disposed between said stator core members;

said stator being composed of a socket-like stator core member having a plurality of upstanding magnetic poles and a plurality plug-like stator core members each having a plurality of upstanding magnetic poles, said plug-like stator core members being stacked in said socket-like stator core members, with said coil disposed between each adjacent pair of said stator core members;

said coil including a bobbin, windings wound around said bobbin and a plurality of terminals electrically connected with said windings, said bobbin having opposite end flanges between which said windings are disposed, one of said end flanges having a mounting portion carrying thereon said terminals;

said one end flange having a first projection and a low damper projection, said first projection having a height larger than the thickness of the material of said plug-like stator core members;

the other of said end flanges having at least one second projection having a height smaller than the thickness of the material of said stator core members; and

said plug-like stator core members stacked in said socket-like stator core members together with said coils having an upper ned projecting from an upper end of said socket-like stator core member.

12. A vibration-proof stepping motor according to claim 11, wherein said coils are stacked such that said one end flange of each of said coils confronts said one end flange of the adjacent coil.

13. A vibration-proof stepping motor according to claim 11, wherein said lower housing has a side wall defining said internal space of said lower housing, and at least one rib projecting from said side wall into said internal space of said lower housing, said rib being pressfitted with a side wall of said socket-like stator core member.

14. A vibration-proof stepping motor according to claim 11, wherein said upper housing has a bearing hole rotatably supporting an end portion of said rotor shaft, and an annular rib concentric with said bearing hole and projecting from an inside surface of said upper housing into engagement with an upper end of said stator.

15. A vibration-proof stepping motor according to claim 11, wherein said bobbin is formed of a resiliently deformable material.

16. A vibration-proof stepping motor of the type having a stator of a built-up construction, comprising:

a lower housing having a first internal space;

an upper housing having a second internal space;

a support plate held between said upper and lower housings and having a plurality of support shafts projecting into said second internal space;

a stator and a rotor disposed between said upper and lower housings, said rotor being rotatably disposed in said stator and having a rotor shaft and a rotor body integral with said rotor shaft, said rotor shaft having a pinion at an output end thereof;

a reduction gear disposed in said second internal space and held between said upper housing and said support plate for lowering the output speed of said rotor shaft;

said reduction gear including first and second gears rotatably supported on said support shafts, respectively, and held in mesh with each other, said first gear being also held in mesh with said pinion of said rotor shaft;

said stator being composed of at least two stator cores disposed one above another in said first internal space and each including a pair of stator core members and a coil disposed between said stator core members;

said lower housing having a bottom surface and a first locking projection on said bottom surface, said stator being composed of a socket-like stator core member having a plurality of upstanding magnetic poles and a plurality plug-like stator core members each having a plurality of upstanding magnetic poles, said plug-like stator core members being stacked in said socket-like stator core members with said coil disposed between each adjacent pair of said stator core members, said socket-like stator core member further having a first guide hole and a second guide hole having a diameter different to the diameter of said first guide hole, said first guide hole being fitted with said first locking projection;

said coil including a bobbin, windings wound around said bobbin and a plurality of terminals electrically connected with said windings, said bobbin having opposite end flanges between which said windings are disposed, one of said end flanges having a mounting portion carrying thereon said terminals, said one end flange having a second locking projection and a low damper projection, said second projection having a height larger than the thickness of the material of said plug-like stator core members, the other of said end flanges having at least one third projection having a height smaller than the thickness of the material of said stator core members;

said third locking projection being fitted with said second guide hole of said socket-like stator core member;

each of said plug-like stator core members having a third guide hole, said second locking projection being fitted with said third guide hole of an adjacent one of said plug-like stator core members, with said damper projection disposed between said other end flange of each bobbin and said adjacent plug-like stator core member;

said plug-like stator core members stacked in said socket-like stator core members together with said coils having an upper end projecting from an upper end of said socket-like stator core member;

said stator being held by and between said upper and lower housings in a compressed condition.

17. A vibration-proof stepping motor according to claim 16, wherein said coils are stacked such that said one end flange of each of said coils confronts said one end flange of the adjacent coil.

18. A vibration-proof stepping motor according to claim 16, wherein said lower housing has a side wall defining said internal space of said lower housing, and at least one rib projecting from said wall into said internal space of said lower housing, said rib being press-fitted with a side wall of said socket-like stator core member.

19. A vibration-proof stepping motor according to claim 16, wherein said upper housing has a bearing hole rotatably supporting an end portion of said rotor shaft, and an annular rib concentric with said bearing hole and projecting from an inside surface of said upper housing into engagement with an upper end of said stator.

20. A vibration-proof stepping motor according to claim 16, wherein said bobbin is formed of a resiliently deformable material.