JPH11289745A - Eddy-current reduction gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a small-sized efficient magnetic circuit obtainable between an eddy-current reduction gear and a braking drum by a combined body of block-shaped (rectangular parallelepiped) magnets and a ferromagnetic member. SOLUTION: A nonmagnetic guide pipe 18, having a hollow section 23 formed for having a rectangular cross section, is laid in a braking drum 13 of a rotating shaft 4 and a nonmagnetic magnet supporting pipe 19 is turnably supported on the inner peripheral surface of the external wall of the guide pipe 18. Then many magnets 20 are coupled with the inner peripheral surface of the supporting pipe 19 at regular intervals in the peripheral direction, and the front end face of a ferromagnetic member 21 is made capable of facing opposite to the magnetic pole faces of the magnets 20 at both ends. In addition, the base-side end sections 21a of the member 21 are made to the inner peripheral surface of the braking drum 13, while the section 21a is supported through the external wall of the guide pipe 18, and a yoke pipe 24 is fixed to the inner peripheral surface of the internal wall of the guide pipe 18. An actuator, which rotates the magnet supporting pipe 18 in both the normal and reverse directions, is provided to the braking position where the magnets 20 are faced to the front end face of the member 21 and a non-braking position, where the magnets 20 face opposite to the projecting wall surface of the yoke pipe 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a ferromagnetic member (pole piece) in which a number of permanent magnets (hereinafter simply referred to as magnets) are arranged with their magnetic poles oriented in the axial direction of a braking drum.
The eddy current reduction device has a base end surface facing the inner peripheral surface of the braking drum and a leading end surface facing the magnetic pole surface of the magnet, so that an efficient magnetic circuit is formed between the magnet and the braking drum during braking. It is about.

[0002]

2. Description of the Related Art An eddy current reduction device disclosed in Japanese Patent Publication No. 3-86,060 and the like performs switching between braking and non-braking by reciprocating a magnet support cylinder in an axial direction. There is a disadvantage that the axial dimension becomes longer by the moving space of the support cylinder.

In the eddy current reduction device disclosed in Japanese Patent Publication No. Hei 7-118901, the movable magnet support cylinder is rotated during braking, and the polarity of the magnet of the movable magnet support cylinder and that of the immovable magnet support cylinder are changed. When the polarity of the magnet is made the same, a magnetic circuit is formed from the magnet to the ferromagnetic plate (pole piece), the braking drum, the ferromagnetic plate, the magnet, the magnet support cylinder, and the magnet. When crossing the magnetic flux from the magnet of the support cylinder, a braking force based on the eddy current is generated in the braking drum.

However, in each of the above-described eddy current reduction devices, the magnetic pole of the magnet is oriented in the radial direction of the brake drum, and the magnetic flux from the magnet passes through the ferromagnetic plate and enters the brake drum effectively.
It is necessary to machine the outer surface and the inner surface of the magnet into a cylindrical surface, which greatly increases the processing cost. Further, in order to guide the magnetic flux from the magnet to the brake drum without leaking, the ferromagnetic plate becomes large to cover the outer surface of the magnet. Since the magnetic circuit at the time of braking includes not only the ferromagnetic plate but also the magnet support cylinder, the magnetic flux density cannot be effectively increased, and a sufficient braking force cannot be generated.

[0005]

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide an efficient magnetic circuit between a brake drum and a combination of a block-shaped magnet and a ferromagnetic member. To provide an improved eddy current reduction device.

[0006]

In order to solve the above-mentioned problems, according to the structure of the present invention, a guide cylinder made of a non-magnetic material having an inner space with a rectangular cross section is provided inside a brake drum connected to a rotating shaft. Disposed, rotatably supports a magnet support cylinder made of a non-magnetic material at the axial center of the inner peripheral surface of the outer cylinder wall of the guide cylinder,
A large number of magnets are connected at equal intervals in the circumferential direction to the inner peripheral surface of the magnet support cylinder, and the tip surfaces of the ferromagnetic members are disposed on the magnetic pole surfaces at both ends in the axial direction of the magnets so as to be opposed to each other. A yoke having a base end surface penetrating the outer cylinder wall of the guide cylinder and facing the inner peripheral surface of the braking drum, and a yoke having a projecting wall surface on the inner peripheral surface of the inner cylinder wall of the guide cylinder capable of facing the inner surface of each magnet. An actuator that fixes the cylinder and has an actuator that rotates the magnet support cylinder forward and backward at a braking position where the magnet faces the distal end surface of the ferromagnetic member and at a non-braking position where the magnet faces the protruding wall surface. It is characterized by the following.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a block (such as a rectangular parallelepiped) magnet is supported on a magnet support cylinder made of a non-magnetic material such that the magnetic poles at both ends are oriented in the axial direction (the direction of the rotation axis of the braking drum). The pair of left and right ferromagnetic members (pole pieces) have a structure in which the base end surfaces face the inner peripheral surface of the brake drum, and the front end surfaces face the magnetic pole surfaces at both ends of the magnet. A magnet support cylinder that couples a large number of magnets supports the magnet support cylinder inside a guide cylinder made of a non-magnetic material so as to be rotatable forward and backward.

At the time of braking, when each magnet of the magnet support cylinder approaches between the tip surfaces of a pair of right and left ferromagnetic members, magnetic flux from each magnet enters the braking drum via the ferromagnetic member. When the rotating brake drum crosses the magnetic flux from each magnet, a braking force based on the eddy current is generated in the brake drum. When the magnet support cylinder is rotated in the circumferential direction by half the pitch of the magnets when braking is not performed, the magnet of the magnet support cylinder faces the protruding wall surface of the yoke cylinder, and a short-circuit magnetic circuit is formed between the magnet and the yoke cylinder. Once formed, the magnetic flux from the magnet does not reach the braking drum and no braking force is generated.

[0009]

1 and 3 are front sectional views of an eddy current reduction device to which the present invention is applied, and FIG. 2 is a side sectional view of the same. The eddy current reduction device couples the braking drum 13 to the rotating shaft 4. For this reason, a spline hole 5 is formed in the output rotary shaft 4 supported by the bearing 3 on the end wall of the gear box 2 of the transmission and protruding from the end wall.
The mounting flange 5 having a is fitted and fastened by a nut 6 so as not to come off. The end wall of the brake drum 7 of the parking brake and the flange portion 9a integral with the wheel 9 supporting the brake drum 13 of the eddy current reduction device are superimposed on the mounting flange 5, and a plurality of bolts 10 and nuts 10 are provided.
a.

The braking drum 13 is made of a material having a high magnetic permeability such as iron, and a plurality of cooling fins 13a are provided on the outer peripheral wall at regular intervals in the circumferential direction. The proximal end of the braking drum 13 is connected to a number of support arms (spokes) 12 fitted to the wheel 9 and extending radially from the wheel 9. A guide cylinder 18 having a box-shaped inner space 23 is coaxially disposed inside the braking drum 13. A stationary guide cylinder 18 made of a non-magnetic material such as aluminum is fixedly fitted to the projecting wall 2a of the gear box 2 and has a frame plate 31 provided with a reinforcing rib 31a.
Is fixed by bolts (not shown). Guide tube 18
Is formed by connecting annular end wall plates 18c and 18d to both ends of the outer cylindrical portion 18a and the inner cylindrical portion 18b. In the illustrated embodiment, the outer tubular portion 18a, the end wall plate 18c, and the inner tubular portion 18b are integrally formed as a tubular body having a U-shaped cross section, and the end wall plate 18d is connected to the tubular body by bolts.

In the inner space 23 of the guide cylinder 18, the magnet support cylinder 1
9 and a large number of ferromagnetic members 21 forming a left and right pair are accommodated,
The magnet 20 of the magnet support tube 19 and the pair of ferromagnetic members 21 can form a horseshoe-shaped combination. The magnet support cylinder 19 is supported by a slide bearing 26 on the inner peripheral surface of the outer cylinder part 18a so as to be able to rotate forward and backward. A large number (the same number as the ferromagnetic members 21) of block magnets 20 are coupled to the inner peripheral surface of the magnet support cylinder 19 at equal intervals in the circumferential direction.

As shown in FIG. 4, the magnets 20 of the magnet support cylinder 19 are preferably arranged so that the directions of the left and right magnetic poles are alternately different in the circumferential direction. A pair of left and right ferromagnetic members (pole pieces) 21 are provided on the pole faces at both axial ends of each magnet 20.
Are opposed to each other. The ferromagnetic member 21 is curved in an arc shape radially outward from the axial direction, and has a base end portion formed into the outer cylindrical portion 18a.
And the base end surface 21a is opposed to the inner peripheral surface 13c of the braking drum 13. As shown in FIGS. 2 and 3, the yoke cylinder 2 made of a magnetic material is provided on the outer peripheral surface of the inner cylinder portion 18b of the guide cylinder 18.
4 is fixed. On the outer peripheral surface of the yoke cylinder 24, a number of projecting wall surfaces 24a facing the inner surface of each magnet 20 are formed at equal intervals in the circumferential direction.

As shown in FIG. 2, a forward / reverse rotation mechanism 45 is connected between the yoke cylinder 24 and the magnet support cylinder 19. The forward / reverse rotation mechanism 45 includes a rotation shaft 44 supported in a groove portion of the yoke cylinder 24.
And a support tube 43 having a base end coupled to the rotating shaft 44 and a rod 42 fitted to the support tube 43 so as to be extendable and contractable and having a distal end connected to the magnet support tube 19 by a pin 41. You. The rotation shaft 44 of the forward / reverse rotation mechanism 45 is
Is rotated forward and backward by an actuator, for example, an electric motor provided on the outer wall of the motor. However, the forward / reverse rotation mechanism 45 is not limited to this, and the magnet support cylinder 19 may be directly rotated by, for example, a fluid pressure actuator.

As shown in FIGS. 2 to 4, at the time of braking, each magnet 20 of the magnet support cylinder 19 is axially aligned with a pair of left and right ferromagnetic members 21. When the rotating brake drum 13 crosses the magnetic flux from the magnet 20 via the ferromagnetic member 21 to the inner peripheral surface 13c of the brake drum 13, an eddy current is generated in the brake drum 13 and a braking torque is generated in the brake drum 13. . At this time, as shown in FIG.
And a magnetic circuit 40 is formed between them.

When the brake is not applied, the rotation shaft 4 is moved by the actuator.
When the magnet 4 is rotated clockwise in FIG. 2 (in the direction of the arrow in FIG. 4) and the magnet support cylinder 19 is rotated by half the pitch of the magnet 20, the state shown in FIGS. No magnetic flux is applied to the drum 13, and no braking torque is generated on the braking drum 13. In other words, each magnet 20 escapes from between the pair of ferromagnetic members 21 and each magnet 20
Has an inner surface facing the protruding wall surface 24a of the yoke cylinder 24, and a short-circuit magnetic circuit 40a is formed between the magnet 20 and the yoke cylinder 24 as shown in FIG.

[0016]

As described above, according to the present invention, a guide cylinder made of a non-magnetic material having an inner space with a rectangular cross section is provided inside a brake drum connected to a rotating shaft. A magnet support cylinder made of a non-magnetic material is rotatably supported at the axial center of the inner peripheral surface of the cylindrical wall, and a number of magnets are connected to the inner peripheral surface of the magnet support cylinder at regular intervals in the circumferential direction. The leading end surface of the ferromagnetic member is disposed so as to be opposed to the magnetic pole surfaces at both ends in the axial direction, and the base end surface of the ferromagnetic member is opposed to the inner peripheral surface of the braking drum through the outer cylinder wall of the guide cylinder. Then, a yoke cylinder having a protruding wall surface capable of facing the inner surface of each magnet is fixed to the inner peripheral surface of the inner cylinder wall of the guide cylinder, and a braking position in which the magnet faces the distal end surface of the ferromagnetic member and An actuator for rotating the magnet support cylinder in the forward and reverse directions at a non-braking position where a magnet faces the protruding wall surface, Since the magnets are arranged such polarity occurs in direction, in the prior art to effectively act the magnetic flux flowing to the magnet support tube to the brake drum, large braking force is obtained.

Since the magnetic flux of the magnet acts on the braking drum by using a pair of ferromagnetic members, the magnet can be formed into an arbitrary shape, and the outer and inner surfaces of the magnet do not need to be formed into cylindrical surfaces.

By inverting the magnetic poles of the magnets adjacent to each other in the circumferential direction and arranging a pair of ferromagnetic members on the magnetic pole surfaces at both ends of the magnet, the magnetic flux of the magnet is effectively guided to the inside of the brake drum. Can be.

By arranging the ferromagnetic members on the pole faces at both ends of the magnet, the shape of the magnet can be simplified, and the processing cost can be greatly reduced.

[Brief description of the drawings]

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

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

FIG. 3 is a front sectional view showing a main part of the eddy current reduction device in a braking state.

FIG. 4 is an exploded plan sectional view showing the inside of the guide cylinder in a braking state of the eddy current reduction device.

FIG. 5 is a side sectional view showing the non-braking state of the eddy current reduction device.

FIG. 6 is a front sectional view showing a main part of the eddy current reduction device in a non-braking state.

FIG. 7 is a plan sectional view showing the inside of the guide cylinder in the non-braking state of the eddy current reduction device in an unfolded state.

[Explanation of symbols]

2: gear box 3: bearing 4: rotating shaft 7: braking drum
9a: Flange part 9: Wheel 12: Support arm 1
3: braking drum 13a: cooling fin 13c: inner peripheral surface 18: guide cylinder 18a: outer cylinder 18b: inner cylinder 1
8c, 18d: End wall plate 19: Magnet support tube 20: Magnet 21: Ferromagnetic member 21a: Base end surface 21b: Tip end surface 23: Inner space 24: Yoke tube 24a: Protruding wall surface 2
6: Bearing 31: Frame plate 42: Rod 43: Support cylinder
44: rotating shaft 45: rotating mechanism

Claims (2)

[Claims] 1. Inside a brake drum connected to a rotating shaft,
A guide tube made of a non-magnetic material having an inner space with a rectangular cross section is provided, and a magnet support tube made of a non-magnetic material is rotatable at the axial center of the inner peripheral surface of the outer tube wall of the guide tube. A large number of magnets are connected to the inner peripheral surface of the magnet support cylinder at equal intervals in the circumferential direction, and the tip surfaces of the ferromagnetic members are disposed on the magnetic pole surfaces at both ends in the axial direction of the magnet so as to be opposed to each other. The base end surface of the magnetic member penetrates the outer cylinder wall of the guide cylinder and is opposed to the inner peripheral surface of the braking drum, and the inner peripheral surface of the inner cylinder wall of the guide cylinder has a protruding wall face that can face the inner surface of each magnet. An actuator configured to fix the yoke cylinder having the magnet support cylinder and to rotate the magnet support cylinder in a forward / reverse direction between a braking position where the magnet faces the distal end surface of the ferromagnetic member and a non-braking position where the magnet faces the protruding wall surface. An eddy current reduction device comprising: 2. The eddy current reduction device according to claim 1, wherein the magnetic poles of the magnets adjacent in the circumferential direction are opposite to each other.