Magnetic torque limiter

• US 7,741,746 B2
• Filed: 12/17/2007
• Issued: 06/22/2010
• Est. Priority Date: 12/20/2006
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Groening, Ingolf
• Primary Examiner(s): Nguyen; Tran N
• Application Number:
  US11/957,705
• Publication Number:
  US 20080150383A1
• Time in Patent Office: 918 Days
• Field of Search: 310/75.R, 310/103, 310/105, 310/112, 310/114, 310/78, 310 92- 96, 310/101, 310/106, 192 841- 846
• US Class Current: 310/106
• CPC Class Codes: H02K 49/106 with a radial air gap

Abstract

A magnetic slip clutch has an outer rotor and an inner rotor, one of the rotors includes permanent magnets, and one of the rotors includes slots, and both rotors are located coaxially to one another; the outer rotor is embodied as a hollow cylinder open on one end, which cylinder includes a face-end covering with a central recess, by which the hollow cylinder can be located on a shaft, and the inner rotor is embodied as a solid cylinder, which is located inside the outer rotor, and a shaft can be located in a central recess in the solid cylinder, and a separate shaft is connectable to each rotor, so that the axis of rotation of the two separate shafts is identical, and a torque transmission is possible from one shaft to the other shaft by both rotors.

Claims

1. A magnetic slip clutch for electrical machines, comprising:

an outer rotor including a plurality of permanent magnets;

an inner rotor, wherein said inner rotor is formed as a solid cylinder having axial longitudinal slots distributed over a circumference of the solid cylinder, in a manner corresponding to positioning of said permanent magnets, both said rotors being located coaxially to one another and spaced apart from one another by an air gap;

shafts selected from the group consisting of drive shafts and driven shafts and connected to said two rotors, and

wherein the principle of a reluctance machine is utilized.

2. A magnetic slip clutch as defined in claim 1, wherein said protrusions have a width, viewed in a cross-section, which corresponds substantially to from 0.9 to 1.1 times a width, viewed in a cross-section, of said permanent magnets.

3. A magnetic slip clutch as defined in claim 2, wherein the width of said permanent magnets and the width of said protrusions are identical.

4. A magnetic slip clutch as defined in claim 1, wherein a protrusions surface is selected from the group consisting of a convex surface and a concave surface in a cross-section, and permanent magnet surfaces oriented toward the protrusion surfaces are configured corresponding to said protrusion surface so that a substantially uniform air gap is formed between said surfaces of said protrusions and said permanent magnets.

5. A magnetic slip clutch as defined in claim 1, wherein each of said permanent magnets, viewed in a cross-section, extends over a region of (k*360°

)/(2p) along a rotor surface, wherein p represents a number of pole pairs, with one of the pole pairs being formed by two of said permanent magnets of different polarity.

6. A magnetic slip clutch as defined in claim 5, wherein a constant k is in a range between 0.2 and 0.7.

7. A magnetic slip clutch as defined in claim 5, wherein a constant k is in a range between 0.2 and 0.44.

8. A magnetic slip clutch as defined in claim 5, wherein a constant k is in a range between 0.45 and 0.55.

9. A magnetic slip clutch as defined in claim 1, wherein said outer rotor is configured as a first cylindrical body which includes a face-end covering with a central recess, and said inner rotor is configured as a second cylindrical body which is located inside said outer rotor, and one separate shaft of said shafts is connectable to each of said rotors so that an axis of rotation of both said separate shafts is identical, and a torque transmission between said both separate shafts is provided.

10. A magnetic slip clutch as defined in claim 9, wherein said permanent magnets are distributed uniformly over a circumference of an inner wall of said first body, and axial longitudinal slots are distributed over a circumference of said second body in a way corresponding to said permanent magnets.

11. A magnetic slip clutch as defined in claim 9, wherein longitudinal slots are distributed uniformly over a circumference of an inner wall of said first body, and said permanent magnets are distributed over a circumference of said second body in a way corresponding to said longitudinal slots.

12. A magnetic slip clutch as defined in claim 1, wherein said permanent magnets and said protrusions provided between longitudinal slots have dimensions which are dimensioned in accordance with a torque threshold value, so that if the torque threshold value is exceeded an rpm of one of said rotors decreases compared to an rpm of the other of said rotors.

13. A magnetic slip clutch as defined in claim 1, wherein said one of said shafts is located on each of said rotors and protrudes from at least one end of said rotor and on an opposite end of said rotor comes to an end essentially flush with said rotor.

14. A magnetic slip clutch as defined in claim 1;

and further comprising a housing, said rotors being rotatable relative to said housing, and said shafts being rotatably supported on said housing.

15. A rotary synchronous motor with a magnetic torque limitation, comprising:

a motor shaft;

a magnetic slip clutch; and

a slip clutch including an outer rotor having a plurality of permanent magnets;

an inner rotor, wherein said inner rotor is formed as a solid cylinder having axial longitudinal slots distributed over a circumference of the solid cylinder, in a manner corresponding to positioning of said permanent magnets, both said rotors being located coaxially to one another and spaced apart from one another by an air gap;

shafts selected from the group consisting of drive shafts and driven shafts and connected to said two rotors, said motor shaft being connected directly in a manner fixed against relative rotation, to one of said shafts of said slip clutch, or said motor shaft is formed by one of said shafts of said slip clutch, while another of said shafts of said slip clutch is configured as a power takeoff means, to which a device to be driven by the motor is connectable, and wherein the principle of a reluctance machine is utilized.

16. A rotary synchronous motor as defined in claim 15;

and further comprising a housing that accommodates said motor shaft and said slip clutch.

21. A drive system, comprising a drive controller;

a drive regulator; and

a rotary synchronous motor with a magnetic torque limitation as defined in claim 15.

17. A generator with a magnetic torque limitation, comprising:

a generator shaft; and

a magnetic slip clutch including an outer rotor having a plurality of permanent magnets;

an inner rotor, wherein said inner rotor is formed as a solid cylinder having axial longitudinal slots distributed over a circumference of the solid cylinder, in a manner corresponding to positioning of said permanent magnets, both said rotors being located coaxially to one another and spaced apart from one another by an air gap;

shafts selected from the group consisting of drive shafts and driven shafts and connected to said two rotors, said generator shaft being connected directly in a manner fixed against relative rotation, to one of said shafts of said slip clutch or said generator shaft is configured as one of said shafts of said slip clutch, while another shaft of said slip clutch is configured as a drive mechanism, to which a device that drives said generator is connectable, and wherein the principle of a reluctance machine is utilized.

18. A generator as defined in claim 17;

and further comprising a housing accommodating said generator shaft and said slip clutch.

19. A power plant, comprising a generator as defined in claim 17.

20. A wind farm comprising a generator as defined in claim 17.