JPH054778U - Permanent magnet type eddy current reducer - Google Patents

Abstract

(57) [Abstract] [Purpose] When not braking, the magnet is included in the short-circuit magnetic circuit to prevent the magnetic field from leaking to the braking disc. [Structure] A magnet support frame 10 made of a non-magnetic material is disposed between a pair of braking discs 8 coupled to a rotating shaft 2. A large number of magnetic plates 15 are joined to the both end walls of the fixed frame 10 facing the braking disc 8 at equal intervals in the circumferential direction. A circuit switching disk 18 made of a non-magnetic material is rotatably supported in the inner space of the fixed frame 10. A ferromagnetic plate 19 corresponding to each magnetic plate 15 is coupled to the circuit switching disk 18. Permanent magnets 16 are coupled to one end of each magnetic plate 15 in the circumferential direction such that the polarities facing the ferromagnetic plates 19 are alternately different in the circumferential direction. A protrusion 15 a facing each ferromagnetic plate 19 is integrally provided at the other end of each magnetic plate 15 in the circumferential direction. An actuator 37 is provided between the fixed frame 10 and the circuit switching disc 18 to relatively rotate the permanent magnets 16 by a half of the arrangement interval.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a speed reducer for assisting a friction brake of a vehicle, and more particularly to a disk-shaped permanent magnet eddy current speed reducer with a reduced leakage magnetic field when not braking.

[0002]

[Prior Art]

 The permanent magnet type eddy current speed reducer disclosed in Japanese Laid-Open Patent Publication No. 1-298947 has a fixed frame made of a non-magnetic material disposed between a pair of braking discs, and both end walls facing the braking disc of the fixed frame. A large number of ferromagnetic plates are attached at equal intervals in the circumferential direction to the disk made of non-magnetic material that is rotatably supported inside the fixed frame. The magnets are simply referred to as magnets) and the polarities are alternately different in the circumferential direction.

When each magnet is sandwiched between a pair of left and right ferromagnetic plates during braking, the magnetic field of the magnets passes through the ferromagnetic plate and exerts a magnetic field on the braking disc, so that the rotating braking disc is rotated. When the magnetic field crosses the magnetic field, an eddy current flows in the braking disc, and the braking disc receives the braking torque. During non-braking, if the fixed frame is rotated by half the magnet arrangement interval and each magnet straddles between two pairs of left and right ferromagnetic plates arranged in the circumferential direction, the two magnets arranged in the circumferential direction and the ferromagnetic plate A short-circuiting magnetic circuit is generated between them and no magnetic field is applied to the braking disc.

[0004]

[Problems to be solved by the device]

 In the eddy current speed reducer described above, when not braking, both ends of each magnet in the circumferential direction are sandwiched by the strong magnetic plates of the fixed frame, but the central part of the magnet is not sandwiched, so that the magnetic field is generated from the gap between the ferromagnetic plates. There is a problem that drag torque is generated in the braking disc because it leaks and reaches the braking disc.

In view of the above problems, an object of the present invention is to provide a permanent magnet type eddy current speed reducer in which a non-braking magnet is included in a short-circuited magnetic circuit and a leakage magnetic field is not exerted on a braking disc. And in.

[0006]

[Means for solving problems]

 In order to achieve the above object, the structure of the present invention is such that a magnet supporting frame made of a non-magnetic material is disposed between a pair of braking discs connected to a rotary shaft, and both ends of the fixed frame facing the braking discs. A large number of magnetic plates are connected to the wall at equal intervals in the circumferential direction, and a circuit switching disc made of a non-magnetic material is rotatably supported in the inner space of the fixed frame. The circuit switching disc corresponds to each magnetic plate. A ferromagnetic plate is connected, and a permanent magnet is connected to one end of each magnetic plate of the fixed frame in the circumferential direction so that the polarities facing the ferromagnetic plate are alternately different in the circumferential direction. In addition, a protrusion facing the ferromagnetic plate is integrally provided, and a rotating means is provided between the fixed frame and the circuit switching disc so as to relatively rotate only half the arrangement interval of the permanent magnets.

[0007]

[Action]

 During non-braking, the protrusions at one end in the circumferential direction of the magnetic plate (which may be a ferromagnetic plate) arranged at equal intervals in the circumferential direction on both end walls of the magnet support frame face the ferromagnetic plate of the circuit switching disc. On the other hand, the magnet at the other end is opposed to the adjacent ferromagnetic plate. Therefore, a short-circuit magnetic circuit occurs between the magnetic plate of the magnet support frame and the ferromagnetic plate of the circuit switching disc. Since the magnet is included in the short-circuited magnetic circuit, it does not leak the magnetic field to the braking disc.

During braking, when the circuit switching disk is rotated by half the magnet arrangement interval, the magnets of one magnetic plate and the protrusions of the other magnetic plate that are adjacent in the circumferential direction face the common ferromagnetic plate. Then, a magnetic circuit is generated between the circuit switching disc sandwiching the magnet and the braking disc, and as the braking disc rotates, an eddy current flows through the braking disc, and the braking disc receives the braking torque.

[0009]

[Example of device]

 1 is a front sectional view showing an upper half of a permanent magnet type eddy current speed reducer according to the present invention, FIG. 2 is a side sectional view of the same eddy current speed reducer, and FIG. 3 is a circumferential direction development of the same eddy current speed reducer. FIG. The bosses 5 of the braking disk 8 are connected to the pair of mounting flanges 3 fitted to the rotary shaft 2 by splines with bolts 4, respectively. A braking disc 8 having fins 7 is connected to a large number of spokes 6 extending radially from the boss 5. A magnet support frame 10 made of a non-magnetic material having a box-shaped cross-section inner space is arranged between a pair of braking disks 8. The magnet support frame 10 is configured by connecting an annular closing plate to a tubular body having a C-shaped cross section, and includes an outer tubular portion 13, an inner tubular portion 14, and left and right end walls 12. In order to maintain the axial position of the magnet support frame 10, the inner cylinder portion 14 is coupled to the boss 22 supported by the rotary shaft 2 by the bearings 23 through a large number of spokes 21.

A large number of openings are provided in both end walls 12 of the magnet support frame 10, and a magnetic plate 15 is fitted and fixed in each opening. The magnet 16 facing the ferromagnetic plate 19 is coupled to the surface of each magnetic plate 15 opposite to the braking disc 8. The polarities of the magnets 16 with respect to the ferromagnetic plate 19 are arranged so as to be alternately different in the circumferential direction. A circuit switching disk 18 made of a non-magnetic material is supported at the center of the magnet support frame 10. The circuit switching disc 18 is rotatably supported by the inner cylindrical portion 14 by a bearing 20.

A large number of openings are provided in the circuit switching disc 18 at equal intervals in the circumferential direction, and a ferromagnetic plate 19 corresponding to the magnetic plate 15 is fitted and fixed in each opening. In reality, the magnet support frame 10 and the circuit switching disc 18 are respectively cast with the magnetic plate 15 and the ferromagnetic plate 19 during casting. As shown in FIG. 3, the magnetic plate 15 of each end wall 12 has a magnet 16 coupled to one end in the circumferential direction, and a protrusion 15a facing the ferromagnetic plate 19 is integrally formed at the other end in the circumferential direction.

As shown in FIG. 2, in order to rotate the circuit switching disc 18, from the opening 31 provided in the outer cylindrical portion 13 of the stationary magnet support frame 10, the protrusion 36 of the circuit switching disc 18 is provided. Is projected radially outward and is connected to the actuator 37. The connecting portion with the actuator 37 is covered with a cover 33 that is integral with the outer cylinder portion 13. The actuator 37 has a piston fitted into a cylinder 32 coupled to the outer cylinder portion 13, and a rod 34 protruding from the piston is connected to a projecting piece 36 via a joint 35.

As shown in FIG. 3, when the magnets 16 and the protrusions 15 a at the circumferential end portions of the magnetic plates 15 on the both end walls 12 of the magnet support frame 10 are opposed to the common magnetic plate 15 as shown in FIG. A short-circuit magnetic circuit indicated by a chain line is generated between the magnetic plate 15 and the ferromagnetic plate 19. Since the magnet 16 is included in the short-circuited magnetic circuit, it does not exert a leak magnetic field on the braking disc 8.

As shown in FIG. 4, when the circuit switching disc 18 is rotated by half the arrangement interval of the magnets 16 during braking, the magnets 16 of one magnetic plate 15 adjacent to each other in the circumferential direction and the magnetism of the other magnetic plate 15 are circumferentially adjacent to each other. The protrusion 15a of the plate 15 faces the common ferromagnetic plate 19, and a magnetic circuit indicated by a chain line is generated between the circuit switching disc 18 and the braking disc 8 that sandwich the magnet 16 to rotate the braking disc 8. Along with this, an eddy current flows through the braking disc 8 and the braking disc 8 receives a braking torque.

In the above embodiment, the circuit switching disc 18 may be fixed and the magnet support frame 10 may be rotated.

[0016]

[Effect of the device]

 As described above, according to the present invention, a magnet supporting frame made of a non-magnetic material is arranged between a pair of braking discs connected to a rotary shaft, and both end walls of the fixed frame facing the braking disc are circumferentially equally spaced. A large number of magnetic plates are combined, a circuit switching disc made of a non-magnetic material is rotatably supported in the inner space of the fixed frame, and a ferromagnetic plate corresponding to each magnetic plate is coupled to the circuit switching disc. A permanent magnet is connected to one end of each magnetic plate of the fixed frame in the circumferential direction so that the polarities facing the ferromagnetic plate are alternately different in the circumferential direction, and the other end of each magnetic plate in the circumferential direction faces the ferromagnetic plate. It is equipped with a protrusion integrally, and is provided with a rotating means for providing relative rotation between the fixed frame and the circuit switching disk by half the arrangement interval of the permanent magnets. If the magnets and protrusions at both ends in the circumferential direction of the magnetic plate arranged at equal intervals in the circumferential direction face the common ferromagnetic plate, Simplistic magnetic circuit between the ferromagnetic plates of the magnetic plate and the circuit switching 換円 plate of the frame occurs. At this time, since the magnet is included in the short-circuited magnetic circuit, it does not exert a leaking magnetic field on the braking disc, and therefore the braking disc does not receive drag torque.

[Brief description of drawings]

FIG. 1 is a front sectional view showing an upper half portion of a permanent magnet type eddy current speed reducer according to the present invention.

FIG. 2 is a side sectional view of the same eddy current reduction device.

FIG. 3 is a plan cross-sectional view showing a non-braking state of the same eddy current speed reducer in a circumferential direction.

FIG. 4 is a plan sectional view showing a braking state of the eddy current speed reducer in a circumferential direction.

[Explanation of symbols]

8: Braking disc 10: Magnet support frame 15: Magnetic plate 15
a: protrusion 16: permanent magnet 18: circuit switching disc 1
9: Ferromagnetic plate

Front page continuation (72) Creator Masayuki Sano 3-25-1 Tonomachi, Kawasaki-ku, Kawasaki-shi, Kanagawa Isuzu Motors Limited Kawasaki Plant

Claims (1)

[Claims for utility model registration] [Claim 1] A magnet support frame made of a non-magnetic material is disposed between a pair of braking discs connected to a rotary shaft, and both end walls of the fixed frame that face the braking discs. A large number of magnetic plates are connected at equal intervals in the circumferential direction, and a circuit switching disc made of a non-magnetic material is rotatably supported in the inner space of the fixed frame, and the circuit switching disc is made of a ferromagnetic material corresponding to each magnetic plate. The permanent magnets are connected to one end of each magnetic plate of the fixed frame in the circumferential direction so that the polarities facing the ferromagnetic plate are alternately different in the circumferential direction, and the other end of each magnetic plate in the circumferential direction is strengthened. A permanent magnet type eddy current speed reducer, which is integrally provided with a projection facing a magnetic plate, and is provided with a rotating means for relatively rotating the fixed frame and the circuit switching disk by a half of the arrangement interval of the permanent magnets.