JP2002300767A - Eddy current reducer - Google Patents

Abstract

(57) [Problem] To provide an eddy current reduction device that more effectively suppresses magnetic leakage during non-braking and reduces drag torque of a rotating body. SOLUTION: A guide cylinder 10 having an inner space with a rectangular cross section made of a non-magnetic material is disposed inside a braking drum 7 made of a conductor connected to a rotating shaft 1. Outer tube part 10 of guide tube 10
A large number of ferromagnetic members 15 are connected at equal intervals in the circumferential direction.
Magnet support tube 1 rotatably supported in the inner space of guide tube 10
4, a permanent magnet 24 is coupled to each ferromagnetic member 15 so that the polarity thereof is alternately different in the circumferential direction. Ferromagnetic member 1
5 are formed on both circumferential edges at both circumferential edges so as to extend in the axial direction.
The ferromagnetic plate 36 closing the space between the adjacent ridges 35 is attached to the outer cylinder portion 1.
0a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eddy current reduction device mainly for assisting a friction brake of a large vehicle, and more particularly to an eddy current reduction device for suppressing drag torque due to magnetic leakage during non-braking.

[0002]

2. Description of the Related Art There are two types of permanent magnet type eddy current reduction devices, one in which the rotating body is a braking drum type (Japanese Patent Application No. 63-127696) and the other in the case of a braking disk type (Japanese Patent Application No. 63-127695). In any case, the permanent magnet 24 (hereinafter, simply referred to as a magnet) is located between the adjacent ferromagnetic members 15 and 15 so that no leakage magnetic field is exerted on the rotating body 7 when no braking is performed. I have. However, actually, as shown in FIG. 9, the magnetic field w1 from the magnet 24 leaks from between the ferromagnetic members 15 to the rotating body 7 even during non-braking, and the rotating body 7 generates drag torque. In an eddy current reduction device proposed in Japanese Patent Application Laid-Open No. 2000-116106 and Japanese Patent Application No. 4-207420 for suppressing a leakage magnetic field, as shown in FIGS.
Although the gap between the magnets 24 is narrowed, that is, the path of the magnetic flux from the magnet 24 to the rotating body 7 is narrowed, it is not sufficient.

[0003]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to more effectively suppress magnetic leakage during non-braking,
An object of the present invention is to provide an eddy current reduction device configured to reduce a drag torque of a rotating body.

[0004]

In order to solve the above-mentioned problems, according to the present invention, a guide cylinder having a rectangular hollow section made of a non-magnetic material is disposed inside a rotatable brake drum. A plurality of ferromagnetic members are coupled to the outer cylinder portion of the guide cylinder,
A permanent magnet is coupled to the magnet support cylinder housed in the inner space of the guide cylinder so as to oppose each of the ferromagnetic members and have polarities alternately different in the circumferential direction, and to both circumferential edges of the ferromagnetic member. A ferromagnetic plate is formed on the peripheral surface of the outer cylindrical portion to form a ridge and close a gap between the adjacent ridges.

Further, according to the structure of the present invention, a guide cylinder having a rectangular hollow section made of a non-magnetic material is disposed between a pair of rotatable braking disks, and a plurality of strong cylinders are provided on both side walls of the guide cylinder. A magnetic member is coupled, and a permanent magnet is coupled to the magnet support cylinder housed in the inner space of the guide cylinder so as to oppose each of the ferromagnetic members and have polarities alternately different in the circumferential direction. Protrusions are formed at both ends in the circumferential direction, and ferromagnetic plates for closing between the adjacent protrusions are provided on the peripheral surfaces of the side walls.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A ferromagnetic member (pole piece) provided with a ridge projecting in the circumferential direction at an edge thereof is embedded in an outer cylindrical portion of a guide cylinder made of a non-magnetic material. A ferromagnetic plate that closes the gap with the strip is provided on the inner or outer peripheral surface of the outer cylinder to prevent magnetic leakage from the magnet to the rotating body. Here, the rotating body means a braking drum or a braking disk made of a conductor.

When the brake is not applied, the magnetic field from the central portion in the circumferential direction of the magnet enters the adjacent magnet through the ferromagnetic plate and the protrusion of the ferromagnetic member, so that no magnetic flux leakage occurs. The circumferential dimension of the ferromagnetic plate is substantially the same as the gap between adjacent ridges. When the ferromagnetic plate is disposed on the inner peripheral surface of the outer cylinder portion, the ridge of the ferromagnetic member is biased toward the outer peripheral side, and when the ferromagnetic member is disposed on the outer peripheral surface, the ridge of the ferromagnetic member is displaced. The ridge is biased inward.

The circumferential distance or gap between the inner peripheral portions of the ferromagnetic member or the circumferential distance or gap between the outer peripheral portions of the ferromagnetic member is made as large as possible.

[0009]

FIG. 1 is a front sectional view of a drum type eddy current reduction device according to the present invention, and FIG. 2 is a side sectional view of the same. The eddy current reduction device according to the present invention includes, for example, a braking drum 7 made of a conductor coupled to the output rotation shaft 1 of a vehicle transmission, and a stationary guide tube made of a non-magnetic material disposed inside the braking drum 7. And a magnet support tube 14 rotatably supported in an inner space of the guide tube 10 having a rectangular cross section. The brake drum 7 overlaps the flange portion 5a of the boss 5 with the end wall of the brake drum 3 of the parking brake on the mounting flange 2 which is spline-fitted and fixed to the rotating shaft 1;
And a nut. The proximal end of a braking drum 7 provided with cooling fins 8 is connected to a number of spokes 6 extending radially from the boss 5.

The guide tube 10 having a rectangular cross section is, for example, a cross section C
An annular side wall 11 is connected to a cylindrical body having a character shape. The guide tube 10 is fixed by a suitable means, for example, to the wall of a transmission. A large number of ferromagnetic members 15 are coupled to the outer cylinder portion 10a of the guide cylinder 10 at equal intervals in the circumferential direction. Preferably,
The ferromagnetic member 15 is cast when the guide tube 10 is formed. The ferromagnetic member 15 has a rectangular plate shape, and the plate surface is curved in an arc shape. A ridge 25 is provided on the side edge of the ferromagnetic member 15.
(FIG. 1) is integrally formed, and the outer cylinder portion 10a of the guide cylinder 10 is formed.
And the ferromagnetic member 15 to increase the degree of coupling by casting. The magnet support tube 14 is an inner space portion of the guide tube 10, specifically, the inner tube portion 10.
b is supported by the bearing 12 so as to be able to rotate forward and backward.

On the left side wall 11 of the guide tube 10, preferably 3
The two hydraulic actuators 20 are connected at equal intervals in the circumferential direction. Actuator 20 has piston 1 attached to cylinder 18.
7 is fitted, and the rod projecting from the piston 17 to the outside is connected to the arm 16 projecting from the magnet support cylinder 14 via the arc-shaped slit 18a on the left side wall of the guide cylinder 10. As shown in FIG. 2, a magnet 24 facing each ferromagnetic member 15 is coupled to the outer peripheral surface of the magnet support tube 14. The magnet support tube 14 is made of a magnetic material, and the magnets 24 facing the ferromagnetic members 15 are arranged so that the polarities of the magnets 24 are alternately different in the circumferential direction. A step 31 is formed at the circumferential end of each magnet 24, and a holding member 32 made of a non-magnetic material engaged with the adjacent step 31 is fastened to the magnet support cylinder 14 by a non-magnetic bolt 33. Is done.

According to the present invention, in order to suppress the leakage magnetic field from passing from the central portion of the magnet 24 in the circumferential direction to the brake drum 7 through the space between the ferromagnetic members 15 during braking, Protrusions 35 are formed at both ends in the circumferential direction of the magnetic member 15, and the ferromagnetic plate 36 that closes between adjacent protrusions 35 (a gap between the protrusions 35) is formed by the outer cylindrical portion 10 a. On the inner surface (inner surface or outer surface). The circumferential dimension of the ferromagnetic plate 36 is substantially the same as the gap between the ridges 35. In the embodiment of FIG. 2, the ferromagnetic plate 36 is provided on the inner peripheral surface of the outer cylindrical portion 10a, and in the embodiment of FIG. 3, the ferromagnetic plate 36a is provided on the outer peripheral surface of the outer cylindrical portion 10a. It is preferable that the circumferential interval or gap between the inner peripheral portions of the ferromagnetic member 15 or the circumferential interval or gap between the outer peripheral portions of the ferromagnetic member 15 be as large as possible. Is formed not in a flat surface including the axis of the outer cylindrical portion 10a but in a triangular cross section.

As shown in FIG. 4, when the ferromagnetic member 15 and the ferromagnetic plate 36 are cast into an outer cylindrical portion made of aluminum or the like, the ferromagnetic member 15 and the ferromagnetic plate 36 are formed into an annular ferromagnetic member. After casting as a member 44 in advance, the ferromagnetic member 44 is disposed inside a mold surrounded by the outer peripheral surface 41 and the inner peripheral surface 42, and molten aluminum is cast and integrated into the mold. Next, the outer peripheral wall and the inner peripheral wall of the casting are fixed to the outer peripheral surface 39.
As shown by the inner peripheral surface 40, the outer cylindrical portion 10a as shown in FIG.

Next, the operation of the eddy current reduction device according to the present invention will be described. During braking, the fluid pressure actuator 20
When the magnet support cylinder 14 is rotated to cause each magnet 24 to completely oppose each ferromagnetic member 15, a magnetic circuit is formed between the magnet support cylinder 14 and the braking drum 7. When the rotating brake drum 7 crosses the magnetic field, the brake drum 7 generates a braking torque based on the eddy current. When the brake is not applied, the magnet support cylinder 14 is rotated by the half-arrangement pitch of the ferromagnetic member 15 by the fluid pressure actuator 20 so that two magnets 24 adjacent in the circumferential direction partially face each ferromagnetic member 15. A short-circuit magnetic circuit w is formed between the magnet support cylinder 14 and the ferromagnetic member 15.

Protrusions 35 are formed at both circumferential edges of each ferromagnetic member 15, and a ferromagnetic plate 36 for closing between adjacent protrusions 35 (a gap between the protrusions 35) is provided. , Outer cylinder 1
0a, the magnetic field which is about to leak from the central portion in the circumferential direction of each magnet 24 to the brake drum 7 through the gap between the ferromagnetic plates 36 and the ferromagnetic plate 36 Article 3
5, a short-circuited magnetic circuit w
1, the leakage magnetic field does not reach the brake drum 7, and the brake drum 7 does not generate drag torque.

In the embodiment shown in FIGS. 2 to 4, the ridge 35 has a rectangular or triangular cross section, but may have a trapezoidal or semicircular cross sectional shape, and as shown in FIG. In consideration of the normal rotation direction, one of the ridges of each ferromagnetic member 15 has a trapezoidal cross-section, and the other ridge has a semicircular cross-section, so that the ferromagnetic plate 36 is substantially closed. You may arrange | position on the inner peripheral surface or outer peripheral surface of the outer cylinder part 10a.

In the embodiment shown in FIG. 5, the normal rotation direction of the brake drum 7 is taken into account, that is, the distortion of the magnetic circuit formed between the brake drum 7 and the magnet support cylinder 14 during braking is taken into account. The ridge 35 formed on the circumferential edge of each ferromagnetic member 15 is formed asymmetrically. That is, a long ridge 35 having a trapezoidal cross section is provided at one end of the ferromagnetic member 15, and a short ridge 35 having a semicircular cross section is formed at the other end. A ferromagnetic plate 36 having substantially the same size as the gap between the ridges 35 of the ferromagnetic members 15 adjacent to each other in the circumferential direction is disposed so as to close the gap. The ferromagnetic plate 36 is the outer cylinder 1
0a is disposed on the inner peripheral surface or the outer peripheral surface of the ferromagnetic plate 36a.
A sufficient radial gap is provided between the ridge 35 and the ridge 35.

In the embodiment shown in FIG. 6, a ferromagnetic plate 36 having substantially the same size as the gap between the ridges 35 of the ferromagnetic members 15 adjacent in the circumferential direction is disposed so as to close the gap. Is done.
In particular, the ferromagnetic member 15 is provided with a sufficient circumferential gap between the ferromagnetic members 15 on the inner peripheral surface of the outer cylindrical portion 10a on which the ferromagnetic plate 36 is disposed. The cross-sectional shape of the edge is taken into account.

The present invention can be applied to a disk type eddy current reduction device. As shown in FIGS. 7 and 8, in the eddy current reduction device, a guide cylinder 55 having an inner space with a rectangular cross section made of a non-magnetic material is disposed between a pair of left and right braking disks 53 connected to a rotating shaft 51. A large number of ferromagnetic members 56 are connected to both side walls 55a of the guide cylinder 55 at regular intervals in the circumferential direction. A magnet support cylinder 6 supported in the inner space of the guide cylinder 55 by a bearing 67 so as to be capable of normal and reverse rotation.
3, the magnets 62 are coupled to each of the ferromagnetic members 56 so that the polarities thereof are alternately different in the circumferential direction.

The guide cylinder 55 is an outer cylinder 63a made of a non-magnetic material.
And the inner cylinder 63b, between which the magnet 62 is supported, a thin sliding plate 64 impregnated with lubricating oil is connected to both sides of the magnet support cylinder 63, and can slide on the ferromagnetic member 56 It is said. Although not shown, a pinion of an electric motor as an actuator fixed to the guide cylinder 55 meshes with a partial gear formed on the outer peripheral wall of the magnet support cylinder 63, and the magnet support cylinder 63 is positive only by a half array pitch of the magnet 62. Reverse rotation is possible. As shown in FIG. 8, protrusions 58 are formed on both circumferential edges of the ferromagnetic member 56, and a ferromagnetic plate 57 that blocks between adjacent protrusions 58 is provided on the inner surface or the outer surface of the side wall 55 a.

At the time of braking, the magnet support cylinder 63 is rotated by a half-array pitch of the magnets 62 by an electric motor, and each magnet 62 is completely opposed to each ferromagnetic member 56.
A magnetic field is applied to the pair of left and right braking disks 53 via the pair of ferromagnetic members 56. When the rotating pair of left and right braking disks 53 cross the magnetic field, the pair of left and right braking disks 53 generate a braking torque based on the eddy current. At the time of non-braking, as shown in FIG. 8, two circumferentially adjacent magnets 62 are connected to a common ferromagnetic member 56.
, A short-circuit magnetic circuit w is generated between the pair of left and right ferromagnetic members 56, and no magnetic field is applied to the braking disk 53.

In particular, protrusions 58 are formed on both circumferential edges of the ferromagnetic member 56, and a ferromagnetic plate 57 for closing between the adjacent protrusions 58 is provided on the inner surface or the outer surface of the side wall 55a. The magnetic field that is about to leak from the central portion in the circumferential direction of 62 to the braking disk 53 through the gap between the ferromagnetic plate 57 and the ferromagnetic plate 57 passes through the ferromagnetic plate 57 and the ridge 58 to the adjacent ferromagnetic member 56. Since a short-circuit magnetic circuit is formed, the leakage magnetic field does not reach the braking disk 53, and the braking disk 53 does not generate drag torque.

[0023]

As described above, according to the present invention, a guide cylinder having a rectangular hollow section made of a non-magnetic material is disposed inside a rotatable brake drum, and a plurality of guide cylinders are provided on the outer cylinder of the guide cylinder. A permanent magnet is coupled to the magnet support cylinder accommodated in the inner space of the guide cylinder so as to oppose each of the ferromagnetic members and to have polarities alternately different in the circumferential direction. Protrusions are formed at both ends in the circumferential direction of the member, and a ferromagnetic plate that blocks between the adjacent protrusions is provided on the peripheral surface of the outer cylindrical portion, or a ferromagnetic plate is provided between a pair of rotatable braking disks. A guide cylinder having a hollow section with a rectangular cross section made of a magnetic material is arranged, a plurality of ferromagnetic members are coupled to both side walls of the guide cylinder, and a magnet support cylinder housed in the hollow section of the guide cylinder, A permanent magnet is coupled to each of the ferromagnetic members so that the polarity is alternately different in the circumferential direction, and
Protrusions are formed on both ends in the circumferential direction of the ferromagnetic member, and the ferromagnetic plates that block between the adjacent protuberances are provided on the peripheral surfaces of the side walls. The magnetic field leaking to the braking drum or the braking disk through the gap between the ferromagnetic members is blocked by the ferromagnetic plate, guided to the ferromagnetic member through the ridge, and short-circuited between the ferromagnetic member and the magnet support cylinder. Since a magnetic circuit is formed, drag torque due to a leakage magnetic field on the braking drum or the braking disk is suppressed.

[Brief description of the drawings]

FIG. 1 is a front sectional view of a braking drum type eddy current reduction device according to the present invention.

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

FIG. 3 is a side sectional view of an eddy current reduction device according to a modified embodiment of the present invention.

FIG. 4 is a cross-sectional side view of the eddy current reduction device when the outer cylinder portion of the guide cylinder is cast.

FIG. 5 is a side sectional view of an eddy current reduction device according to a modified embodiment of the present invention.

FIG. 6 is a side sectional view of an eddy current reduction device according to a modified embodiment of the present invention.

FIG. 7 is a front sectional view of a braking disk type eddy current reduction device to which the present invention is applied.

FIG. 8 is a plan sectional view showing the eddy current reduction device developed in a circumferential direction.

FIG. 9 is a side sectional view of a conventional eddy current reduction device.

FIG. 10 is a side sectional view of another conventional eddy current reduction device.

FIG. 11 is a side sectional view of another conventional eddy current reduction device.

[Explanation of symbols]

1: rotating shaft 2: mounting flange 3: braking drum 4:
Bolt 5: Boss 6: Spoke 7: Brake drum
8: Cooling fin 10: Guide cylinder 10a: Outer cylinder part 10
b: Inner cylinder part 11: Side wall 12: Bearing 14: Magnet support cylinder 15: Ferromagnetic member 16: Arm 17: Piston 1
8: Cylinder 18a: Slit 20: Actuator 24: Magnet 31: Step 32: Holding member 33:
Bolt 35: Ridge 36: Ferromagnetic plate 36a: Ferromagnetic plate 41: Outer peripheral surface 42: Inner peripheral surface 43: Non-magnetic member 4
4: Ferromagnetic member 51: Rotating shaft 53: Braking disk 53
a: Cooling fin 55: Guide tube 55a: Side wall 56:
Ferromagnetic member 57: Ferromagnetic plate 58: Ridge 62: Magnet 63: Magnet support cylinder 63a: Outer cylinder 64: Sliding plate 63
b: Inner cylinder 65: Boss part 66: Spoke 71: Bearing 72: Boss part 73: Spoke 75: Good conductor 76:
Good conductor

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H649 AA03 BB02 BB03 BB07 GG09 GG10 GG11 GG13 GG16 GG18 HH04 HH16 HH18 JK03 PP02 PP13

Claims (2)

[Claims] 1. A guide cylinder having a hollow section having a rectangular cross section made of a non-magnetic material is disposed inside a rotatable brake drum, and a plurality of ferromagnetic members are coupled to an outer cylinder of the guide cylinder. A permanent magnet is coupled to the magnet support cylinder housed in the inner space of the guide cylinder so as to oppose each of the ferromagnetic members and have polarities alternately different in the circumferential direction, and to both circumferential edges of the ferromagnetic member. An eddy current reduction device, wherein a ferromagnetic plate is formed on a peripheral surface of the outer cylindrical portion to form a ridge and close a gap between the adjacent ridges. 2. A guide cylinder having a rectangular hollow section made of a non-magnetic material is provided between a pair of rotatable braking disks.
A plurality of ferromagnetic members are connected to both side walls of the guide tube, and the magnet support tube housed in the inner space of the guide tube is permanently attached to the magnet support tube so as to oppose the ferromagnetic members and have polarities alternately different in the circumferential direction. Magnets are coupled, and protrusions are formed on both circumferential edges of the ferromagnetic member, and ferromagnetic plates for closing between adjacent protrusions are provided on the circumferential surfaces of the side walls. Eddy current reduction device.