JPH0591717A - Eddy current type speed reducer - Google Patents

Abstract

(57) [Abstract] [Purpose] To reduce the axial dimension of the device by switching between braking and non-braking without moving the magnet support ring in the axial direction. A stationary magnet support ring 20 made of a non-magnetic material is provided inside a braking drum 13 coupled to a rotary shaft 4, and a large number of ferromagnetic materials are provided on the outer peripheral wall of the magnet support ring 20 at equal intervals in the circumferential direction. The magnetic pole members 21 are connected. Inside the magnet support ring 20, there are provided a stationary permanent magnet 32a facing the magnetic pole members 21 and having polarities alternately different in the circumferential direction, and a movable permanent magnet 32 capable of rotating together with a shaft 31 parallel to the rotation shaft 4. Arrange. The permanent magnet 3 for each magnetic pole member 21 is provided by the magnet rotating means.
If the polarity of 2 is the same as that of the permanent magnet 32a, the braking drum 13 receives the braking force, but if the polarity of the permanent magnet 32 is reversed, the magnetic field does not reach the braking drum 13 and the braking drum 13
Does not receive braking force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to an eddy current type speed reducer for assisting a friction brake of a large vehicle, and more particularly to an eddy current type speed reducer capable of shortening an axial dimension.

[0002]

2. Description of the Related Art An eddy current type speed reducer according to Japanese Patent Application No. 1-218498 has an axial direction in which a magnet support ring for coupling a large number of permanent magnets at equal intervals in a circumferential direction is fixed to a fixed frame projecting inside a braking drum. The magnet support ring is movably supported, and the magnet support ring projects into the braking drum so that the permanent magnet exerts a magnetic field on the inner peripheral surface of the braking drum. It is switched to a non-braking position where no magnetic field is applied to the surface.

In the above-mentioned eddy current type speed reducer, the fixed frame has a long axial dimension, and for example, the speed reducer and the parking brake are installed in a narrow mounting space of the connection portion between the output rotary shaft of the transmission and the propulsion shaft under the floor of the vehicle body. There are various difficulties in arranging in. Further, in order to increase the braking ability, it is necessary to increase the size of the permanent magnet. For example, if the circumferential dimension of the permanent magnet is increased,
The circumferential gap between the permanent magnets is reduced, and the amount of magnetic leakage increases, which is a limitation. Therefore, if the axial dimension of the permanent magnet is lengthened, not only the fixed frame but also the actuator that drives the magnet support ring will need to have a long stroke.There are many parts to change, which is preferable from the viewpoint of weight and cost. Absent.

[0004]

SUMMARY OF THE INVENTION In view of the above problems, the object of the present invention is to reduce the axial size of the device by switching between braking and non-braking without moving the magnet support ring in the axial direction. An object is to provide an eddy current type speed reducer.

[0005]

In order to achieve the above object, in the structure of the present invention, a stationary magnet support ring made of a non-magnetic material is disposed inside a braking drum connected to a rotary shaft, and a magnet support is provided. A large number of magnetic pole members made of a ferromagnetic material are coupled to the outer peripheral wall of the ring at equal intervals in the circumferential direction, and a stationary permanent magnet whose polarity opposite to each magnetic pole member in the magnet support ring is alternately different in the circumferential direction. A movable permanent magnet that can rotate together with an axis parallel to the axis is provided, and the movable permanent magnet has a braking position having the same polarity as the stationary permanent magnet with respect to each magnetic pole member and a non-braking having a different polarity. It is provided with a magnet rotating means for switching to the position.

[0006]

In the present invention, a large number of magnetic pole members are connected to the outer peripheral wall of the magnet support ring facing the inner peripheral surface of the braking drum at equal intervals in the circumferential direction, and a radial line passing through the center is formed inside the magnet support ring. On the other hand, an immovable permanent magnet is arranged so that the magnetic pole members are slightly inclined and the polarities of the magnetic pole members are alternately different in the circumferential direction, and the polarities of the magnetic pole members are rotatably supported by an axis parallel to the rotation axis of the braking drum. A movable permanent magnet that can be reversed is provided.

During braking, if the polarity of the movable permanent magnet with respect to the magnetic pole member is made the same as that of the stationary permanent magnet, a magnetic circuit in which the adjacent magnetic pole members straddle the braking drum is generated. That is, both permanent magnets exert a magnetic field on the inner peripheral surface of the braking drum via the magnetic pole members. When the rotating braking drum crosses the magnetic field, an eddy current flows in the braking drum, and the braking drum receives a braking force.

When the braking is released, the movable permanent magnet is rotated so that the polarity of the movable permanent magnet with respect to the magnetic pole member is opposite to that of the stationary permanent magnet. Both permanent magnets are short-circuited inside the magnet supporting ring. Occurs, the magnetic field is not applied to the braking drum, and the braking drum receives no braking force.

[0009]

1 is a side sectional view showing an embodiment in which an eddy current type speed reducer according to the present invention is arranged at a rear end portion of a vehicle transmission. The mounting flange 6 is spline-fitted to the output rotary shaft 4 supported by the bearing 2 on the rear end wall of the gear box 3, and is fastened by the nut 5. The end wall of the braking drum 10 of the known parking brake and the end wall 12 of the braking drum 13 of the speed reducer are overlapped with the mounting flange 6, and the bolt 8
Is fastened by nut 9. A yoke 7 of a universal joint for connecting the rotary shaft 4 and a known propulsion shaft is fitted to the mounting flange 6 and is joined by a bolt (not shown). The braking drum 13 is provided with a large number of cooling fins 15 on the outer peripheral wall at equal intervals in the circumferential direction.

A permanent magnet 32 rotatable with the shaft 31 and a stationary permanent magnet 32a (see FIG. 2) are provided in an empty space between the inner peripheral surface 14 of the braking drum 13 and the outer peripheral surface of the braking drum 10.
A magnet support ring 20 is disposed to alternately support and in the circumferential direction. Therefore, the circular frame plate 16 having reinforcing ribs is fixed to the rear end wall of the gear box 3 via the mounting plate 16a, and the annular support plate 19 having an L-shaped cross section is fixed to the plate surface of the frame plate 16. To be done. The magnet support ring 20 is fixed to the plate surface of the support plate 19, and the drive ring 17 is rotatably supported by the cylindrical portion of the support plate 19.

The magnet support ring 20 is provided at both ends of an inner cylinder 24 made of a magnetic material and an outer cylinder 23 made of a non-magnetic material.
A cylindrical portion 27 for accommodating the cylindrical permanent magnet 32, which is formed by connecting 8 and 29, and is preferably connected to an axis 31 parallel to the rotation axis 4, is provided. The shaft 31 is supported by bearings on the end walls 28 and 29. A gear 18 is coupled to the left end of the shaft 31 and meshes with a gear 17a formed on the drive ring 17.

As shown in FIG. 2, rectangular openings are provided in the outer cylinder 23 of the magnet support ring 20 at equal intervals in the circumferential direction, and magnetic pole members 21 having a triangular cross section are fitted and fixed in the openings. Inner cylinder 2
4 is also integrally formed with a magnetic pole member 24a having a triangular cross section. The magnetic pole member 21 and the magnetic pole member 24a are arranged so as to be shifted by a half pitch in the circumferential direction, and a stationary permanent magnet 32a is coupled between them. Therefore, the stationary permanent magnet 32a is inclined with respect to the radial line passing through the center of the braking drum 13,
Moreover, the polarities of the magnetic pole members 21 are arranged so as to be alternately different in the circumferential direction. The movable permanent magnet 32 and the stationary permanent magnet 32a are paired with the magnetic pole member 21 and the magnetic pole member 2.
It is arranged between 4a. Therefore, the cylindrical portion 27 is partially formed in the magnetic pole member 21 and the magnetic pole member 24a corresponding to the peripheral surface of the permanent magnet 32 having a circular cross section.

The magnetic pole member 21 is cast when the outer cylinder 23 is cast from an aluminum alloy or the like. One of the shafts 31 is connected to the shaft of an electric motor (not shown) supported by the frame plate 16. When the shaft 31 is rotated a half turn by the electric motor, the drive ring 17 is rotated and the magnetic poles of the permanent magnets 32 are reversed in direction.

As shown in FIG. 2, in a braking state in which the permanent magnets 32 form a pair with the permanent magnets 32a and the polarities of the magnetic pole members 21 are the same, as shown by the chain line in FIG. A magnetic circuit straddling the braking drum 13 is generated between the members 21. That is, the permanent magnet 32, the magnetic pole member 21,
The braking drum 13, the adjacent magnetic pole member 21, the permanent magnet 32a,
A magnetic circuit is generated through the magnetic pole member 24a. Therefore,
When the rotating braking drum 13 crosses the magnetic field, an eddy current flows through the braking drum 13, and the braking drum 13 receives a braking force.

When the drive ring 17 is rotated by an electric motor (not shown), the shaft 3 is moved together with the gear 18 meshing with the gear 17a.
1 and the permanent magnet 32 make a half rotation, and as shown in FIG. 3, the polarities of the permanent magnet 32 and the permanent magnet 32a with respect to the magnetic pole members 21 are reversed. In this non-braking state, the stationary permanent magnet 32a and the movable permanent magnet 32 for each magnetic pole member 21 are
A short-circuited magnetic circuit occurs inside the magnet support ring 20. That is, as shown by a chain line in FIG. 3, a magnetic circuit passing through the permanent magnet 32, the magnetic pole member 21, the permanent magnet 32a, the magnetic pole member 24a, the inner cylinder 24, and the adjacent magnetic pole member 24a is generated, and the braking drum 1
Since the magnetic field is not applied to 3, the braking drum 13 receives no braking force.

In the above-described embodiment, the movable permanent magnet 32 has a circular cross section, but the intermediate portion which is not the magnetic pole may be shaved flat to have an oval cross section. In addition, the immobile permanent magnet 3
If 2a has the same circular cross section as the movable permanent magnet 32,
Costs can be saved by sharing parts.

In the embodiment shown in FIG. 4, a stationary permanent magnet 32 is used.
The a and the movable permanent magnet 32 are oval in cross section, and the cost and weight are reduced by sharing the parts.

In the above-mentioned embodiment, the magnet rotating means comprises the respective shafts 3.
The gear 18 of No. 1 is meshed with the gear 17a of the drive ring 17 rotated by the electric motor, and the rotation of the shaft 31 is half-turned to switch between the braking and non-braking of the reduction gear. As shown in, the gear 1 of each shaft 31
8, a small gear 18a supported by a magnet support ring 20
, And one of the shafts 31 may be driven by an electric motor 36 supported on the frame plate 16 via a support plate 35. Further, in order to interlock the gears 18 with each other, an endless toothed belt called a cog belt is wound around the drive ring 17, or an endless chain is wound around a chain wheel connected to each shaft 31 instead of the gears 18. , The arms connected to the respective shafts 31 may be annularly connected by a link, and one of the arms may be swung by a pneumatic actuator.

[0019]

As described above, according to the present invention, the stationary magnet support ring made of a non-magnetic material is provided inside the braking drum connected to the rotary shaft, and the outer peripheral wall of the magnet support ring is arranged at equal intervals in the circumferential direction. A large number of magnetic pole members made of a ferromagnetic material are coupled to each other, and they are rotated together with an immovable permanent magnet facing the magnetic pole members in the magnet support ring, the polarities of which are alternately different in the circumferential direction, and an axis parallel to the rotation axis. A movable permanent magnet to be obtained, and a braking position in which the movable permanent magnet has the same polarity as the stationary permanent magnet with respect to each magnetic pole member,
Since the magnet rotating means for switching to the non-braking position having the different polarity is provided, the switching between braking and non-braking can be obtained by the rotation of the permanent magnet regardless of the axial movement of the permanent magnet. It fits compactly inside, the axial dimension of the device is greatly reduced compared to the conventional example, and it becomes easy to mount it on a vehicle.

Compared with the conventional example, there is more space in the vehicle mounting space, the braking force can be increased by lengthening the permanent magnets accordingly, and products with different specifications (braking force) can be manufactured without changing the magnet rotating means. It is advantageous in terms of cost, weight and the like.

By adjusting the amount of rotation of the permanent magnet, the strength of the magnetic field exerted on the braking drum changes, and the braking force can be controlled according to the running conditions.

[Brief description of drawings]

FIG. 1 is a side sectional view of an eddy current type speed reducer according to the present invention.

FIG. 2 is a front sectional view showing a braking state of the device.

FIG. 3 is a front cross-sectional view showing a non-braking state of the device.

FIG. 4 is a front sectional view of an eddy current type speed reducer according to a modified embodiment of the present invention.

FIG. 5 is a front view showing a rotation driving means for a permanent magnet in an eddy current type speed reducer.

[Explanation of symbols]

4: rotating shaft 13: braking drum 17a, 18, 18
a: gear 20: magnet support ring 21: magnetic pole member 27:
Cylindrical part 31: Shafts 32, 32a: Permanent magnet 36: Electric motor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masayuki Sano 3-25-1 Tonomachi, Kawasaki-ku, Kawasaki-shi, Kanagawa Isuzu Motors Limited Kawasaki Plant

Claims (1)

[Claims] 1. A stationary magnet support ring made of a non-magnetic material is disposed inside a braking drum connected to a rotating shaft, and a large number of magnetic poles made of a ferromagnetic material are provided on the outer peripheral wall of the magnet support ring at equal intervals in the circumferential direction. The members are coupled to each other, and a stationary permanent magnet having polarities alternately opposite to each other in the circumferential direction and a movable permanent magnet capable of rotating with an axis parallel to the rotation axis are arranged inside the magnet supporting ring. A magnet rotating means for switching between a braking position in which a movable permanent magnet has the same polarity as the stationary permanent magnet with respect to each magnetic pole member and a non-braking position having a different polarity.
Eddy current type speed reducer.