JP3285052B2 - Eddy current type reduction gear - 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 friction braking of a large vehicle, and more particularly to a plurality of eddy current type speed reducers arranged at equal intervals in a circumferential direction on an inner peripheral surface of a brake drum and an outer peripheral surface of a magnet support cylinder. A ferromagnetic plate (pole piece) corresponding to each magnet is provided between a permanent magnet (hereinafter simply referred to as a magnet) and a vortex that switches between braking and non-braking by changing the relative rotational phase of the ferromagnetic plate. The present invention relates to a current-type reduction gear.

[0002]

2. Description of the Related Art In an eddy current type speed reducer disclosed in Japanese Patent Application Laid-Open No. 4-12659, an immovable guide cylinder is disposed inside a brake drum, and a movable cylinder having substantially the same configuration is provided in an inner space of the guide cylinder. A magnet support cylinder and an immovable magnet support cylinder are arranged in the axial direction, and the movable magnet support cylinder is rotated by the pitch of the magnet arrangement. The applied braking position and the polarity of the magnets arranged in the axial direction are opposite to each other, and the position is switched to the non-braking position where no magnetic field is applied to the braking drum.

As shown in FIGS. 8 and 9, in the above-described eddy current type speed reducer, the magnet 24 of the movable magnet support tube 14 and the magnet 2 of the stationary magnet support tube 14A with respect to the common ferromagnetic plate 15 are provided.
When the magnets 24 and 24A are rotated by the arrangement pitch p of the ferromagnetic plate 15 in the direction of the arrow y from the non-braking position where the polarities of 4A are different from each other, the polarities of the magnets 24 and 24A with respect to the common ferromagnetic plate 15 become the same braking position. The magnets 24, 24A adjacent to each other in the direction, that is, two pairs of front and rear magnets 24, 24A
(See FIG. 2).

However, when the movable magnet 24 is rotated from the non-braking position by the rotation amount P1 in the direction of the arrow y, the pair of front and rear magnets 24 is connected to the common ferromagnetic plate 15 by a short-circuit magnetic circuit. Form z. When the rear edge 24b of the magnet 24 in the illustrated state moves away from the ferromagnetic plate 15, a strong attractive force acts between the rear edge 24b of the magnet 24 and the front edge of the ferromagnetic plate 15. That is, the driving torque required to rotate the magnet support cylinder 14 from the non-braking position to the braking position by the arrangement pitch p is, as shown by the line 31, the rear end edge 24b of the magnet 24 being the front end edge of the ferromagnetic plate 15. Abnormally high when moving away from Therefore, the actuator 20 for driving the magnet support cylinder 14 needs to have a capacity to overcome the above-mentioned peak torque, and there is a problem that the actuator 20 becomes large.

[0005]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to reduce the peak torque acting on a movable magnet support cylinder at the time of switching between braking and non-braking, so that a small-capacity actuator can support a magnet. An object of the present invention is to provide an eddy current type reduction gear capable of driving a cylinder.

[0006]

In order to achieve the above object, the present invention provides an immovable guide cylinder made of a non-magnetic material and having an inner space having a rectangular cross section inside a brake drum connected to a rotating shaft. A large number of substantially rectangular ferromagnetic plates are buried in the outer peripheral wall of the guide cylinder at equal intervals in the circumferential direction, and a movable magnet support cylinder made of a magnetic material and an immovable magnet support are provided in the inner space of the guide cylinder. The magnets are arranged side by side in the axial direction, and the magnets facing each ferromagnetic plate are coupled to each magnet support cylinder so that the polarities are alternately different in the circumferential direction. A movable magnet is provided between a non-braking position that is different and completely overlaps the common ferromagnetic plate, and a braking position that is completely overlapped on the common ferromagnetic plate with the same polarity of magnets arranged in the axial direction of each magnet support cylinder. Eddy current type reduction gear equipped with an actuator that rotates the support cylinder by the pitch of the magnet array In the magnet, the rear end edge of each magnet of the movable magnet support tube and the front end edge of each ferromagnetic plate intersect with each other in the direction of rotation of the movable magnet support tube from the non-braking position to the braking position. And one of the front edge of the ferromagnetic plate is cut off at an angle.

[0007]

When the movable magnet support cylinder is rotated from the non-braking position to the braking position, the front and rear magnets having different polarities face the common ferromagnetic plate, and a gap is formed between the ferromagnetic plate and the magnet support tube. A short-circuit magnetic circuit results. In order to reduce the peak torque acting on the movable magnet support cylinder immediately before the short-circuit magnetic circuit disappears, the rear edge of the magnet of the movable magnet support cylinder and the front edge of the rectangular ferromagnetic plate are not parallel. One edge is cut obliquely so as to cross each other. Therefore, when the rear edge of the magnet of the movable magnet support tube is separated from the front edge of the ferromagnetic plate, the force of the ferromagnetic plate to attract the magnet gradually decreases,
Finally, the magnet separates from the ferromagnetic plate in a point-contact manner in a plan view. As a result, the peak torque acting on the movable magnet support cylinder based on the attraction force between the ferromagnetic plate and the magnet is reduced, and it is possible to switch between non-braking and braking with a small-capacity actuator.

[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.

The movable magnet support tube 14 made of a magnetic material is
The inner diameter of the guide cylinder 10 is substantially the same as the inner diameter of the guide cylinder 10, and the guide cylinder 10 is supported on the inner peripheral wall 10b by a slide bearing or roller bearing 12 so as to be able to rotate forward and backward. 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 is coupled to the left half outer peripheral surface with magnets 24 facing the left half of each ferromagnetic plate 15 so that the polarity with respect to the ferromagnetic plate 15 is alternately different in the circumferential direction.

On the other hand, an immovable magnet support cylinder 14A made of a non-magnetic material has the same number and the same number of magnets 24A as the magnets 24 buried or cast at equal intervals in the circumferential direction. Magnet support tube 14A
Is connected to the inner surface of the outer peripheral wall 10a of the guide tube 10 with a heat insulating material 19 preferably made of glass wool, asbestos or the like interposed therebetween.
A suitable gap is provided between the inner peripheral surface of the magnet support tube 14A and the outer peripheral surface of the right half of the magnet support tube 14.

To the left end wall of the guide tube 10, preferably three actuators 20 are connected at equal intervals in the circumferential direction. 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, according to the present invention, when switching the magnet support tube 14 from the non-braking position to the braking position,
In order to reduce the peak torque acting on the magnet support tube 14, the front edge of the ferromagnetic plate 15 and the rear edge 2 of the movable magnet 24
4b is configured to separate in a point contact state instead of a line contact state in a plane. For this reason, the ferromagnetic plate 15 is substantially rectangular and its front edge is parallel to the center axis of the brake drum 7, while the rear edge 24 b of the movable magnet 24 intersects with the front edge of the ferromagnetic plate 15. It is cut diagonally to make it.

Next, the operation of the eddy current type speed reducer according to the present invention will be described. At the time of non-braking, as shown in FIG. 1, the magnet 24 of the magnet support tube 14 and the magnet 24 of the magnet support tube 14A
A has a polarity opposite to that of the ferromagnetic plate 15. At this time, the magnets 24 and 24A form a short-circuit magnetic circuit 26 between each ferromagnetic plate 15 and the magnet support tube 14, and do not apply a magnetic field to the braking drum 7.

The magnet support cylinder 14 is actuated by the actuator 20.
Is rotated from the non-braking position to the braking position by the arrangement pitch p of the magnets 24, the front and rear magnets 24 having different polarities face the common ferromagnetic plate 15 on the way, but the rear end edge 24 of the magnet 24
b is cut obliquely with respect to the front edge of the rectangular ferromagnetic plate 15, so that the rear edge 24b of the magnet 24 is
When the magnet leaves the front edge of the magnet, the force of the ferromagnetic plate 15 attracting the magnet 24 gradually decreases, and finally, the magnet 24 separates from the ferromagnetic plate 15 in a point contact state in a plan view. Accordingly, the peak torque acting on the magnet support tube 14 is reduced based on the attractive force between the ferromagnetic plate 15 and the magnet 24, and switching between non-braking and braking can be performed by the actuator 20 having a smaller capacity than before. become.

As shown in FIG. 2, during braking, the magnets 24, 24A arranged in the axial direction have the same polarity facing the ferromagnetic plates 15, and apply a magnetic field to the braking drum 7 via the ferromagnetic plates 15. When the rotating brake drum 7 crosses the magnetic field, an eddy current flows through the brake drum 7, and the brake drum 7 receives a braking torque. At this time, the magnets 24 and 24A form a magnetic circuit 26a between the brake drum 7 and the magnet support tube 14.

In the above embodiment, each of the magnets 24, 2
The movable magnet 24 and the immovable magnet 24A are configured to be trapezoidal in plan view because 4A is shared. In addition, the stationary magnet 24A is joined in a cylindrical shape by a magnet support tube 14A made of a non-magnetic material and fixed to the guide tube 10.
The illustrated magnet support tube 14 may be divided into an immovable magnet support tube and a movable magnet support tube, and the magnet 24A may be supported by the immovable magnet support tube.

As shown in FIG. 4, the movable magnet 24 and the immobile magnet 24A may have shorter side edges facing each other and longer side edges. Also, as shown in FIG.
Instead of cutting off the rear edge 24b of the magnet 24 at an angle, the corners of the magnet 24 may be rounded or, as shown in FIG.
May be parallelograms, or the magnets 24 may be oblong in plan view, or the magnets 24 and 24A may remain rectangular and the front edge 15a of the ferromagnetic plate 15 may be partially The magnet 24 may be cut off obliquely so as to intersect with the rear end edge 24b of the movable magnet 24, and the magnet 24 is separated from the ferromagnetic plate 15 in a point contact state.

[0019]

As described above, 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 disposed inside a brake drum connected to a rotating shaft. A large number of almost rectangular ferromagnetic plates are embedded in the wall at equal intervals in the circumferential direction, 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. The magnets facing each ferromagnetic plate are coupled to each magnet support tube so that the polarities are alternately different in the circumferential direction, and the magnets arranged in the axial direction of each magnet support tube have different polarities and are all over the common ferromagnetic plate. The movable magnet support cylinder is rotated by an arrangement pitch of the magnets between a non-braking position where the magnets overlap each other and a braking position where the magnets arranged in the axial direction of the respective magnet support cylinders have the same polarity and completely overlap the common ferromagnetic plate. In an eddy current type speed reducer having a moving actuator, a movable magnet support cylinder is The rear end of the magnet and the ferromagnetic plate are arranged such that the rear end of each magnet of the movable magnet support cylinder and the front end of each ferromagnetic plate intersect each other in the direction of rotation from the moving position to the braking position. When the movable magnet support cylinder is rotated from the non-braking position to the braking position, the front and rear magnets with different polarities face the common ferromagnetic plate because one of the front edges of the The rear edge of the magnet is separated from the front edge of the ferromagnetic plate in a point-contact manner in a plan view. Accordingly, the force by which the ferromagnetic plate attracts the magnet gradually weakens, and the peak torque of the magnet support cylinder based on the attraction force between the ferromagnetic plate and the magnet is reduced. Switching between braking and braking becomes possible.

[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 plan view showing a relationship between a magnet and a ferromagnetic plate of the eddy current type speed reducer.

FIG. 4 is a plan view illustrating a relationship between a magnet and a ferromagnetic plate according to a modified example of the present invention.

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

FIG. 6 is a plan view illustrating a relationship between a magnet and a ferromagnetic plate according to a modified example of the present invention.

FIG. 7 is a plan view illustrating a relationship between a magnet and a ferromagnetic plate according to a modified example of the present invention.

FIG. 8 is a side sectional view of a conventional eddy current type speed reducer.

FIG. 9 is a plan view illustrating a relationship between a magnet and a ferromagnetic plate of the eddy current type speed reducer.

[Explanation of symbols]

7: Brake drum 10: Guide cylinder 14, 14A: Magnet support cylinder 15: Ferromagnetic plate 24, 24A: Magnet 24b: Rear edge

──────────────────────────────────────────────────続 き Continuing from the front page (72) Eiji Okumura, Inventor No. 8 Fujisawa-shi, Kanagawa Prefecture Isuzu Central Research Institute Co., Ltd. (72) Inventor Masayuki Kato Eight Dozerana, Fujisawa-shi Kanagawa Prefecture, Isuzu Central Research Inc. In-house (72) Inventor Makoto Ogawa 8 Tsuchiya, Fujisawa-shi, Kanagawa Prefecture Isuzu Central Research Institute Co., Ltd. (56) References Utility model registration 2572529 (JP, Y2) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02K 49/02 H02K 49/10

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 connected to a rotating shaft, and a large number of the guide cylinders are arranged at equal intervals in a circumferential direction on an outer peripheral wall of the guide cylinder. A ferromagnetic plate having a substantially rectangular shape is embedded, and a movable magnet support tube made of a magnetic material and an immovable magnet support tube are juxtaposed in the inner space of the guide tube in the axial direction. A non-braking position in which the magnets facing the magnetic plate are coupled such that the polarities are alternately different in the circumferential direction, the polarities of the magnets arranged in the axial direction of the respective magnet support cylinders are different, and the common ferromagnetic plate is entirely overlapped, Eddy current with an actuator that rotates the movable magnet support cylinder by the pitch of the magnets at the braking position where the magnets arranged in the axial direction of the magnet support cylinders have the same polarity and completely overlaps the common ferromagnetic plate. In the speed reducer, the movable magnet support cylinder is moved from the non-braking position to the braking position. One of the rear edge of the magnet and the front edge of the ferromagnetic plate is inclined such that the rear edge of each magnet of the movable magnet support cylinder and the front edge of each ferromagnetic plate intersect each other in the moving direction. An eddy current type speed reducer, characterized in that the speed reducer is cut off.