JP3285059B2 - Eddy current type reduction gear - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method of simply rotating a stationary magnet supporting cylinder for supporting a permanent magnet (hereinafter simply referred to as a magnet) and a movable magnet supporting cylinder by an arrangement pitch of magnets. By reducing the amount of rotation given to an eddy current type speed reducer for a vehicle in which the magnet switches between a non-braking position in which the magnet does not exert a magnetic field on the braking drum and a braking position in which the magnet exerts a magnetic field, particularly a movable magnet support cylinder. The present invention relates to an eddy current type reduction gear having a reduced actuator.

[0002]

2. Description of the Related Art As disclosed in Japanese Patent Application Laid-Open No. 4-12659, a rotation switching type eddy current type speed reducer has the advantage of reducing the axial dimension of a brake drum for the entire device. If an actuator for rotating the movable magnet support cylinder protrudes long outside the diameter of the braking drum, and if two fluid pressure actuators are mounted horizontally on both sides of the reduction gear, the actuator will not fit inside the vehicle frame. In some cases, there is a need to shorten the actuator.

[0003] If the number of magnets is increased and the arrangement pitch of the magnets is reduced, the stroke of the actuator can be shortened. However, the number of magnets and mounting brackets increases, and material costs and manufacturing costs increase. Also, reduce the inner diameter of the braking drum,
If the axial dimension is increased, the actuator stroke can be shortened without increasing the number of magnets. However, there is a problem that a space for a parking brake drum disposed inside the braking drum and a universal joint for connecting the output shaft of the transmission and the propulsion shaft are eliminated.

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to reduce the stroke of an actuator for rotating a movable magnet support cylinder forward and backward without changing the inner diameter of a conventional brake drum or the number of magnets. An object of the present invention is to provide an eddy current type speed reducer which can be shortened.

[0005]

In order to achieve the above object, according to the present invention, an immovable guide cylinder made of a non-magnetic material and having an inner space with a rectangular cross section is provided inside a brake drum. A ferromagnetic plate is coupled to a number of openings provided at equal intervals in the circumferential direction on the outer peripheral wall of the guide cylinder, and a movable magnet support cylinder made of a magnetic material and an immovable magnet support cylinder are axially inserted in the inner space of the guide cylinder. The magnets whose circumferential dimensions are shorter than the ferromagnetic plate are connected to the outer peripheral surface of each magnet support cylinder so that the polarities opposite to the ferromagnetic plates are alternately different in the circumferential direction, and are movable with different polarities from each other. The non-braking position where the magnet of the magnet support cylinder and the magnet of the immovable magnet support cylinder face the common ferromagnetic plate, and the magnet of the movable magnet support cylinder and the magnet of the immovable magnet support cylinder having the same polarity as each other An actuator for rotating the movable magnet support cylinder forward and backward to a braking position facing the common ferromagnetic plate. A front end of the magnet of the movable magnet support tube is substantially aligned with a front end of the ferromagnetic plate with respect to the rotation direction of the brake drum by rotating the movable magnet support tube in the rotation direction of the brake drum by the actuator. The rear end edge of the magnet of the movable magnet support cylinder is switched from the coincident non-braking position to a braking position substantially coincident with the rear end edge of the ferromagnetic plate.

[0006]

According to the present invention, the axial dimension is slightly longer without changing the inner diameter of the brake drum and the circumferential dimension is slightly shorter than that of the ferromagnetic plate without changing the number of magnets, as compared with the conventional speed reducer. In addition, the length in the axial direction is lengthened to ensure the same braking capacity as the conventional one.

[0007] By changing the relative position of the movable magnet with respect to the ferromagnetic plate in the braking position and the non-braking position, the stroke of the actuator is shortened. That is, in the non-braking position, the front edge of the movable magnet coincides with the front edge of the ferromagnetic plate in the rotation direction of the braking drum, and in the braking position, the rear edge of the movable magnet coincides with the rear edge of the ferromagnetic plate. . As a result, the stroke of the actuator can be reduced by the circumferential dimension difference between the ferromagnetic plate and the movable magnet as compared with the magnet arrangement pitch.

[0008]

1 is a side sectional view of an eddy current type speed reducer according to the present invention, and FIG. 2 is a front sectional view thereof. An eddy current type speed reducer according to the present invention includes a braking drum 7 made of a conductor coupled to an output rotation shaft 1 of a vehicle transmission, for example, and a braking drum 7.
, A guide tube 10 made of a non-magnetic material, and a movable magnet support tube 14 and an immovable magnet support tube 14A housed 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 together with the end wall portion 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 has a plurality of bolts 4 and nuts. Is concluded. One end of a brake drum 7 having a cooling fin 8 is connected to a number of spokes 6 extending radially from the boss 5.

The guide cylinder 10 having a box-shaped cross section is, for example, a cross section C
An end wall 11 made of an annular plate is connected to a letter-shaped cylinder. The guide tube 10 is fixed by a suitable means to, for example, a gearbox of a transmission. The outer peripheral wall 10a of the guide cylinder 10 is connected to a large number of openings 25 provided at regular intervals in the circumferential direction by embedding a ferromagnetic plate 15 therein. Preferably, the ferromagnetic plate 15 is cast when the guide cylinder 10 is formed. The ferromagnetic plate 15 has a rectangular plate shape, and the plate surface is curved in an arc shape. Strictly speaking, from the viewpoint of strength, it is sufficient for the guide cylinder 10 to be made only of the outer peripheral wall 10a that couples the ferromagnetic plate 15 to a nonmagnetic material.

The movable magnet support tube 14 made of a magnetic material is
The axial dimension of the inner space of the guide tube 10 is set to approximately half of the inner space, and is supported by the inner peripheral wall 10b by a sliding bearing or roller bearing 12 so as to be capable of normal and reverse rotation. Magnet support tube 14
The arm 16 extending in the axial direction from the actuator 20 passes through an arc-shaped slit 18 a provided on the end wall of the guide cylinder 10, and is actuated by the actuator 20.
Is connected to the rod. The magnet support tube 14 has a magnet 24 on the outer peripheral surface facing the left half of each ferromagnetic plate 15 and the ferromagnetic plate 1.
5 are connected in such a manner that the polarities for 5 are alternately different in the circumferential direction.

A stationary magnet support tube 14A made of a magnetic material
The same number of magnets 24 as magnets 14
A are connected at equal intervals in the circumferential direction. The magnet support tube 14A is connected to the inner peripheral wall 10b of the guide tube 10. However, the magnet support tube 14A may be coupled to the outer peripheral wall 10a of the guide tube 10.

Preferably, two actuators 20 are connected to the left end wall of the guide tube 10 at equal circumferential intervals. The actuator 20 has a piston 17 fitted on a cylinder 18, and a rod projecting from the piston 17 to the outside is an arm 1.
6 is connected.

As shown in FIG. 3, in the present invention, the immovable magnet 24A has a dimension in the circumferential direction (arrow y) shorter than that of the ferromagnetic plate 15 and is arranged at the center in the circumferential direction with respect to the ferromagnetic plate 15. Set up. The movable magnet 24 has the same size as the magnet 24A, and the front edge 24a of the magnet 24 coincides with the front edge 15a of the ferromagnetic plate 15 in the non-braking position in the rotation direction (arrow y) of the braking drum 7, as shown in FIG. In this way, the rear edge 24b of the magnet 24 is aligned with the rear edge 15b of the ferromagnetic plate 15 in the braking position.
Therefore, the stroke s of the actuator for rotating the magnet from the non-braking position to the braking position or from the braking position to the non-braking position depends on the arrangement pitch of the magnets 14 and 14A (the arrangement of the ferromagnetic plates 15 in terms of the rotation angle). (Same as the pitch) is shorter than p by Δs.

Next, the operation of the eddy current type speed reducer according to the present invention will be described. When the brake is not applied, as shown in FIGS. 1 and 3, the magnets 24 of the magnet support tube 14 and the magnets 24A of the magnet support tube 14A have opposite polarities completely opposite to the common ferromagnetic plate 15. I have. At this time, the magnets 24, 24
A forms a short-circuit magnetic circuit w between each ferromagnetic plate 15 and the magnet support cylinder 14 and does not apply a magnetic field to the braking drum 7.

At the time of braking, when the movable magnet support cylinder 24 is rotated by a stroke s (= p−Δs) in the rotation direction y of the braking drum 7, the magnets 2 arranged in the axial direction as shown in FIGS.
4, 24A have the same polarity opposing each ferromagnetic plate 15, and apply a magnetic field to the braking drum 7 via the ferromagnetic plate 15.
When the rotating brake drum 7 crosses the magnetic field, the brake drum 7
An eddy current flows through the brake drum 7, and the braking drum 7 receives a braking torque.
At this time, each magnet 24, 24A forms a magnetic circuit z between the braking drum 7 and the magnet support tube 14.

When the brake is not applied, since the magnet 24A and the magnet 24 are displaced in the circumferential direction, the magnetic circuit is displaced from the plane including the center axis of the brake drum 7, but the ferromagnetic plate 15 is disengaged from both the magnets 24,2.
4A, no new problem such as magnetic leakage to the braking drum 7 occurs. No change occurs in the magnetic circuit at the time of braking as compared with the conventional one.

In the above-described embodiment, the stationary magnet 24A is disposed at the center in the circumferential direction of the ferromagnetic plate 15. However, even if the stationary magnet 24 is moved to the front edge 15a of the ferromagnetic plate 15, To the rear edge 15b.

Further, the front edge 24a of the movable magnet 24 in the non-braking position is slightly projected forward (about 5 mm) from the front edge 15a of the ferromagnetic plate 15, and the rear end of the movable magnet 24 in the braking position. The edge 24b is the rear edge 15b of the ferromagnetic plate 15.
Even if it protrudes slightly (about 5 mm) from the rear, there is almost no effect on the braking force during braking or the magnetic leakage during non-braking, and the stroke of the actuator can be further reduced.

As shown in FIG. 5, the front and rear edges 15a, 15b of the ferromagnetic plate 15 projecting from the immovable magnet 24A.
May be removed. That is, the circumferential dimension of the ferromagnetic plate 15 is the same as that of the immobile magnet 24A for the portion overlapping the immobile magnet 24A, and is the same as that shown in FIG.

[0020]

As described above, according to the present invention, the movable magnet is moved toward the front edge of the ferromagnetic plate in the non-braking position and toward the rear edge in the braking position, whereby the movable magnet support cylinder is rotated forward and backward. The stroke of the moving actuator can be substantially shortened compared to the arrangement pitch of the magnets, and the mounting space in the vehicle can be saved by shortening the lateral dimension (dimension in the vehicle width direction) of the entire apparatus.

Further, the amount of air consumed by the actuator can be reduced by shortening the actuator, and a quick switching operation of the reduction gear can be obtained.

[Brief description of the drawings]

FIG. 1 is a front sectional view of an eddy current type speed reducer according to the present invention when no braking is performed.

FIG. 2 is a side sectional view of the speed reducer during braking.

FIG. 3 is a developed plan view showing a relationship between a magnet and a ferromagnetic plate when the speed reducer is not braked.

FIG. 4 is a developed plan view showing a relationship between a magnet and a ferromagnetic plate during braking of the speed reducer.

FIG. 5 is a developed plan view showing a relationship between a magnet and a ferromagnetic plate according to a modified example of the present invention.

[Explanation of symbols]

7: Brake drum 10: Guide tube 14, 14A: Magnet support tube 15: Ferromagnetic plate 15a: Front edge 15b: Rear edge 24: Movable magnet
24A: Immobile magnet 24a: Front edge 24b: Rear edge

Claims (1)

(57) [Claims] An immovable guide cylinder made of a non-magnetic material and having an inner space with a rectangular cross section is disposed inside a brake drum, and is provided on a plurality of openings provided at equal intervals in a circumferential direction on an outer peripheral wall of the guide cylinder. A ferromagnetic plate is connected, and a movable magnet support tube made of a magnetic material and an immovable magnet support tube are juxtaposed in the axial direction in the inner space of the guide tube. Also, a magnet with a short circumferential dimension is coupled so that the polarity facing each ferromagnetic plate is alternately different in the circumferential direction, and the magnet of the movable magnet support cylinder and the magnet of the immovable magnet support cylinder with different polarities are common. The movable magnet support is provided between a non-braking position opposed to the ferromagnetic plate and a braking position where the magnet of the movable magnet support tube and the magnet of the immovable magnet support tube having the same polarity mutually face the common ferromagnetic plate. Equipped with an actuator that rotates the cylinder forward and backward, and a movable magnet support cylinder is By rotating in the rotation direction of the moving drum, the front edge of the magnet of the movable magnet support cylinder is moved from the non-braking position where the front edge of the magnet of the movable magnet support cylinder substantially coincides with the front edge of the ferromagnetic plate in the rotation direction of the brake drum. An eddy current type speed reducer, wherein a rear end edge of the magnet is switched to a braking position substantially coincident with a rear end edge of the ferromagnetic plate.