JPH072003B2 - Eddy current type speed reducer - Google Patents

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 a current type speed reducer having a short overall length (axial dimension) and capable of gradually adjusting a braking force. is there.

[0002]

2. Description of the Related Art In an eddy current type speed reducer according to Japanese Patent Application No. 1-218498, a magnet supporting cylinder for connecting a large number of magnets at regular intervals in a circumferential direction is axially moved to a fixed frame protruding inside a braking drum. The magnet support cylinder is supported so that the magnet support cylinder protrudes into the braking drum, and the 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 inner peripheral surface of.

[0003]

The above-mentioned eddy current type speed reducer has the advantage that the braking force can be adjusted according to the amount of axial movement of the magnet support cylinder, but the overall length of the device is long and the speed reducer is parked. There are various difficulties in arranging together with the brake in a narrow mounting space of the connecting portion between the output shaft of the transmission and the propulsion shaft under the floor of the vehicle body.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide an eddy current type speed reducer which has a short overall length and is capable of gradually adjusting the braking force by the rotational differential of a large number of magnet supporting cylinders.

[0005]

In order to achieve the above object, according to the present invention, a cylindrical fixing frame having a box-shaped cross section made of a non-magnetic material is provided inside a braking drum connected to a rotary shaft. The fixed frame has a large number of ferromagnetic plates embedded in the outer cylinder of the fixed frame at equal intervals in the circumferential direction, and the stationary magnet support cylinder is externally fitted to the inner cylinder of the fixed frame. Is one
A pair of movable magnet support cylinders are fitted on the outer surface of each magnet support cylinder, and magnets facing the respective ferromagnetic plates are coupled to the outer peripheral surface of each magnet support cylinder so that the polarities thereof are alternately different in the circumferential direction. It is provided with means for separately rotating each one by one pitch of the magnet arrangement.

[0006]

In the braking position where the polarities of the magnets of the pair of movable magnet supporting cylinders for the respective ferromagnetic plates are the same as the polarities of the magnets of the stationary magnet supporting cylinder, the magnets of the magnet supporting cylinders adjacent in the circumferential direction are magnetized. A magnetic circuit is generated between the braking drum and the braking drum, and when the rotating braking drum crosses the magnetic field, an eddy current flows in the braking drum, and the braking drum receives a braking torque.

At the semi-braking position where the polarity of the magnet of one movable magnet support cylinder for each ferromagnetic plate differs from the polarity of the magnet of the stationary magnet support cylinder, each ferromagnetic plate and a pair of movable magnet support cylinders A short-circuiting magnetic circuit is generated between the magnet and the pair of movable magnet supporting cylinders, and only the magnet of the stationary magnet supporting cylinder exerts a magnetic field on the braking drum, and the braking torque received by the braking drum is halved. To do.

At a non-braking position where the polarities of the magnets of the pair of movable magnet supporting cylinders for each ferromagnetic plate are different from the polarities of the magnets of the stationary magnet supporting cylinder, each ferromagnetic plate and the pair of movable magnet supporting cylinders are supported. Since a short-circuit magnetic circuit occurs between the magnet of the cylinder, the magnet of the stationary magnet support cylinder, and each magnet support cylinder, and each magnet does not exert a magnetic field on the braking drum, the braking drum receives no braking torque.

[0009]

1 is a side sectional view of an eddy current type speed reducer according to the present invention during half braking. The braking drum 10 is the boss portion 10.
For example, c is fitted and fixed to the rotary shaft 14 which is the output shaft of the transmission. The braking drum 10 has a large number of cooling fins 1 on its outer peripheral surface.
0a are provided at equal intervals in the circumferential direction, and are integrally connected to the boss portion 10c by the spokes 10b.

The fixed frame 7 made of a non-magnetic material is the braking drum 1.
It is arranged inside 0. The fixed frame 7 is formed by connecting annular end walls 7a to both ends of the outer tubular portion 7b and the inner tubular portion 7c, and a large number of ferromagnetic plates 15 are joined to the outer tubular portion 7b at equal intervals in the circumferential direction. In practice, the ferromagnetic plate 15 is cast when casting the outer cylinder portion 7b from aluminum or the like. Movable magnet support cylinders 12a, 12 housed in the inner space of the fixed frame 7 having a box-shaped cross section.
b is rotatably supported by bearings 25 and 27 on the inner cylinder portion 7c, and the stationary magnet support cylinder 12c is externally fitted on the inner cylinder portion 7c. Length of magnet support cylinders 12a, 12b (axial dimension)
Is about half of the magnet support cylinder 12c. Each magnet support cylinder 1
The outer peripheral surfaces of the magnets 2a, 12b, 12c are connected with the same number of magnets 13a, 13b, 13c as the ferromagnetic plate 15 at equal intervals in the circumferential direction, and the ferromagnetic plates 15 of the magnets 13a, 13b, 13c are connected.
Are arranged so as to have different polarities in the circumferential direction.

A pair of movable magnet supporting cylinders 12a and 12b is separately provided for one pitch p (FIG. 2) of the arrangement of the magnets 13a and 13b.
In order to make the arm 21 rotatable, only the arm 21 is projected from the magnet supporting cylinder 12a to the outside through the slit of the end wall 7a.
The partial gear 21a formed on the arm 21 meshes with a small gear 22 coupled to the main shaft of the electric motor 2 with a brake. Similarly, the arm 23 is projected from the magnet supporting cylinder 12b to the outside through the slit 26 of the magnet supporting cylinder 12a and the slit of the end wall 7a, and the partial gear 23a formed on the arm 23 is coupled to the main shaft of the electric motor with brake 2a. It meshes with the small gear 24.
The partial gears 21a and 23a are concentric with the rotary shaft 14.

Next, the operation of the eddy current type speed reducer according to the present invention will be described. At the time of all braking, the magnet support cylinders 12a, 1
2b is rotated by the electric motors 2 and 2a, and each ferromagnetic plate 15 is rotated.
Magnets 13a, 1 of each magnet support cylinder 12a, 12b for
The polarity of 3b is the same as the polarity of the magnet 13c of the magnet support cylinder 12c. At this time, as shown representatively in the case of the magnet supporting cylinder 12c in FIG.
b, 12c magnets 13a, 13b, 13c are ferromagnetic plates 1
5, the magnetic field is applied to the inner peripheral surface of the braking drum 10 to form a magnetic circuit shown by a chain line in FIGS. When the rotating braking drum 10 crosses the magnetic field, an eddy current flows through the braking drum 10 and the braking drum 10 receives a braking torque.
The braking torque at this time is determined by the magnets 13a, 13b, 13c.
Of the magnetic field exerted on the braking drum 10 by the
Proportional to the rotation speed of.

Here, for example, the magnet supporting cylinder 12a is rotated by one pitch p of the magnet array by the electric motor 2, and as shown in FIG. 1, the polarity of the magnet 13a facing each ferromagnetic plate 15 is the polarity of the magnet 13b. If it is set to a position different from
A short-circuited magnetic circuit passing through the ferromagnetic plate 15, the magnet 13b, the magnet supporting cylinder 12b, and the magnet supporting cylinder 12a is generated.
13b does not exert a magnetic field on the braking drum 10. Only the magnet 13c exerts a magnetic field on the braking drum 10, and the braking torque received by the braking drum 10 is halved.

When the magnet supporting cylinders 12a and 12b are rotated by the electric motors 2 and 2a during non-braking so that the polarities of the magnets 13a and 13b with respect to the ferromagnetic plates 15 are opposite to those of the magnet 13c. As shown by the chain line in 5, each magnet 13
a, 13b, ferromagnetic plate 15, magnet 13c, magnet support cylinder 1
2c, a short circuit magnetic circuit passing through each magnet support cylinder 12b, 12a is generated, the magnetic field does not reach the braking drum 10 at all, and the braking drum 10 receives no braking torque.

[0015]

As described above, according to the present invention, a cylindrical fixed frame having a box-shaped cross section made of a non-magnetic material is disposed inside the braking drum connected to the rotary shaft, and the fixed frame has an outer cylindrical portion. A pair of movable magnets in which a large number of ferromagnetic plates are embedded at equal intervals in the circumferential direction, a stationary magnet support cylinder is externally fitted to the inner cylinder portion of the fixed frame, and the length is almost half the length of the stationary magnet support cylinder. A support cylinder is externally fitted, and magnets facing the ferromagnetic plates are connected to the outer peripheral surface of each magnet support cylinder so that the polarities are alternately different in the circumferential direction, and a pair of movable magnet support cylinders are separately arranged in a magnet array. It is provided with means for rotating the magnet supporting cylinder not only by switching between braking and non-braking but also by switching the strength of the braking force regardless of the axial movement of the magnet supporting cylinder. Since the magnet support cylinder is compactly housed inside the braking drum, the overall length of the device is greatly shortened. Mounted to both is easy.

Compared with the conventional example, there is more room in the mounting space of the vehicle, and the braking torque can be increased by making the magnet longer.
Further, since it is possible to manufacture speed reducers having different braking torques without changing the magnet supporting cylinder rotating means, it is advantageous in terms of cost and weight.

By selectively rotating the movable magnet support cylinder, the strength of the magnetic field exerted on the braking drum changes, and the braking torque can be adjusted according to the running conditions.

[Brief description of drawings]

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

2 is a front sectional view of the eddy current type speed reducer taken along the line 2A-2A in FIG.

FIG. 3 is a developed plan view showing a semi-braked state of each magnet support cylinder.

FIG. 4 is a side plan view showing all braking states of each magnet support cylinder.

FIG. 5 is a side plan view showing a non-braking state of each magnet support cylinder.

[Explanation of symbols]

2, 2a: electric motor 7: fixed frame 7b: outer cylinder part 7c:
Inner cylinder part 10: Braking drums 12a, 12b, 12c:
Magnet support cylinders 13a, 13b, 13c: Magnet 14: Rotating shaft 15: Ferromagnetic plate

Claims (1)

[Claims] 1. A cylindrical fixed frame having a box-shaped cross section and made of a non-magnetic material is disposed inside a braking drum connected to a rotary shaft.
A large number of ferromagnetic plates are embedded in the outer cylinder of the fixed frame at equal intervals in the circumferential direction, a stationary magnet support cylinder is externally fitted to the inner cylinder of the fixed frame, and the length is about half the length of the stationary magnet support cylinder. A pair of movable magnet support cylinders are fitted onto the outer peripheral surface of the magnet support cylinders, and magnets facing the ferromagnetic plates are coupled to the outer peripheral surface of the magnet support cylinders so that the polarities thereof are alternately different in the circumferential direction. An eddy current type speed reducer comprising means for rotating the support cylinders separately by one pitch of the magnet arrangement.