JPH11285234A - Permanent magnet type eddy current decelerating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To connect a ferromagnetic plate to a guide cylinder to prevent the ferromagnetic plate from coming off. SOLUTION: A guide cylinder 18 of non-magnetic material is arranged coaxially in the inside of a brake drum 13. Many ferromagnetic plates 21 are connected with circumferential equal spacings in a peripheral wall part 13a facing opposite to the brake drum 13 of the guide cylinder 18. A magnet 20 is connected so that a polarity facing opposite to that of the ferromagnetic plate 21 differs alternately in a peripheral direction, to a movable magnet support cylinder 19 supported to an inner space part 23 of rectangular section of the guide cylinder 18. An actuator, moving the magnet support cylinder 19 to a braking position, where the magnet 20 is faces the ferromagnetic plate 21, and a non-braking position without facing opposite, is provided. In the mold cast ferromagnetic plate 21, wall surfaces 51a, 51c circumferential end part of an outer half part 51 of a joint surface 50 are tilted, so as to gradually shorten the circumferential dimension in accordance with approaching an outer surface 51b from the joint surface 50, and a coming-off lock wall which impedes coming off to the inward of the ferromagnetic plate 21 is provided in a wall surface of an inner half part 61 of the joint surface 50.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eddy current reduction device for assisting friction braking of a large vehicle, and more particularly to a permanent magnet eddy current reduction device for preventing a ferromagnetic plate from falling off a guide cylinder.

[0002]

2. Description of the Related Art Japanese Patent Application No. 8-293,354 filed by the present applicant.
According to the permanent magnet type eddy current reduction device disclosed in Japanese Patent Application Laid-Open No. H11-157, the cross-sectional shape of the substantially rectangular ferromagnetic plate (pole piece) is made trapezoidal in which the outer surface facing the braking drum has a shorter side than the inner surface. The braking force can be improved. In the above-described eddy current reduction device, a magnet support cylinder that supports a permanent magnet (hereinafter simply referred to as a magnet) is sealed inside a guide cylinder having an inner space with a rectangular cross section, and is made of a non-magnetic material such as an aluminum casting. A ferromagnetic plate capable of facing the magnet is cast into the outer peripheral wall of the guide cylinder, or the ferromagnetic plate is welded to the outer peripheral wall of the guide cylinder made of austenitic stainless steel. By moving the magnet support cylinder in the axial direction or the circumferential direction, switching between braking and non-braking is achieved. By making the cross-sectional shape of the ferromagnetic plate trapezoidal, the magnetic flux from the magnet to the rotating braking drum through the ferromagnetic plate is narrowed to increase the magnetic flux density, and the eddy current generated in the braking drum is increased to increase the braking force. Enhance.

However, if the area of the ferromagnetic plate has a trapezoidal cross section extending toward the magnet, it is difficult to cast the ferromagnetic plate into the guide cylinder, and when the inner surface of the ferromagnetic plate is overlaid on the magnet, the ferromagnetic plate will not move. It may be attracted by the magnet and fall out of the guide cylinder. Also, when the brake drum is removed for repair and inspection, the ferromagnetic plate easily comes off the guide cylinder.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a permanent magnet type eddy current reduction device in which a ferromagnetic plate is prevented from dropping from a guide cylinder in view of the above-mentioned problems.

[0005]

According to the present invention, there is provided a brake drum comprising a conductor connected to a rotating shaft and having an inner space made of a non-magnetic material and having a rectangular cross section. An immovable guide cylinder is coaxially arranged, and a number of ferromagnetic plates are connected at equal intervals in a circumferential direction to an outer peripheral wall portion of the guide cylinder facing the braking drum so as to be movable to the inner space of the guide cylinder. A permanent magnet is coupled to the supported magnet support cylinder such that the polarity with respect to the ferromagnetic plate is alternately different in the circumferential direction, and the braking position where the permanent magnet faces the ferromagnetic plate and the permanent magnet are connected to the ferromagnetic plate. In a permanent magnet type eddy current reduction device including an actuator that moves the magnet support cylinder to a non-braking position that is not opposed to the braking position, the ferromagnetic plate to be die-forged has an outer circumferential surface facing a braking drum from a mold matching surface. The wall at the end in the direction The outer surface facing the braking drum from the surface is inclined so that its circumferential dimension is gradually shortened, and at least a part of the wall of the mating surface prevents the ferromagnetic plate from coming inward. It is characterized by having walls.

Further, according to the structure of the present invention, an immovable guide cylinder made of a non-magnetic material and having an inner space with a rectangular cross section is coaxially arranged inside a braking drum made of a conductor connected to a rotating shaft. A large number of ferromagnetic plates are joined to the outer peripheral wall of the guide cylinder at equal intervals in the circumferential direction, and a rotatable magnet support cylinder and a non-rotatable magnet support cylinder are axially arranged in the inner space of the guide cylinder. The magnets are supported side by side, and permanent magnets are coupled to the respective magnet support cylinders so that the polarity with respect to the ferromagnetic plate is alternately different in the circumferential direction. The permanent magnets of the respective magnet support cylinders facing the respective ferromagnetic plates have the same polarity. A permanent magnet type eddy current including an actuator for rotating one of the magnet support cylinders forward and reverse at a certain braking position and a non-brake position at which the permanent magnets of the magnet support cylinders facing the ferromagnetic plates have different polarities. In the reduction gear transmission, the ferromagnetic plate to be die-forged is matched with the mold. The wall surface at the circumferential end on the outer surface side facing the braking drum is inclined so that the dimension in the circumferential direction gradually decreases as approaching the outer surface facing the braking drum from the mold mating surface. A wall is provided with a retaining wall for preventing the ferromagnetic plate from coming inward.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a ferromagnetic plate (pole piece) is prevented from falling out of a guide cylinder by a magnetic attraction force.
A retaining wall is provided on the ferromagnetic plate. The ferromagnetic plate has an intermediate thickness, that is, the portion outside the mold matching surface (parting line),
That is, the cross section of the outer half is trapezoidal, and the inner half of the mating surface is substantially rectangular as in the prior art. In other words, the wall surface at the circumferential end or the axial end of the outer half of the matching surface of the ferromagnetic plate is inclined. Also, a protrusion (lead) is provided on the ferromagnetic plate along the mold matching surface so that the ferromagnetic plate does not fall out of the guide cylinder due to the attractive force of the magnet. Here, the mold mating surface refers to a boundary surface between an upper mold and a lower mold used for forging or casting a ferromagnetic plate.

[0008]

1 is a front sectional view 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, the spline hole 5a 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 the above 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 boss 9 of the brake drum 13 of the eddy current reduction device are superimposed on the mounting flange 5 and fastened with a plurality of bolts 10 and nuts 10a. .

The braking drum 13 is made of a conductor such as iron or aluminum. Preferably, a copper cylinder 35 formed by molding a thin copper plate into a cylinder is connected to the inner peripheral surface 13c. The braking drum 13 is connected at its base end to a number of spokes 12 extending radially from the boss 9. A large number of cooling fins 13a are integrally provided on the outer peripheral wall of the braking drum 13 at equal intervals in the circumferential direction.

A guide cylinder 18 having an inner space 23 having a box-shaped cross section is coaxially arranged inside the braking drum 13. The stationary guide cylinder 18 is a frame plate 3 that is externally fitted and fixed to the protruding wall 2a of the gear box 2.
1 is fixed by bolts 32 and 33. Guide tube 18
May be formed by connecting an annular end wall plate to both ends of the outer peripheral wall portion 18a and the inner peripheral wall portion 18b, but the illustrated guide cylinder 18 has a U-shaped cross section of a left half portion made of ordinary iron or the like. The cylindrical portion and the cylindrical portion of the right half made of a nonmagnetic material such as aluminum and having an inverted L-shaped cross section are connected by a number of bolts 14.

The outer peripheral wall 18a of the guide cylinder 18 facing the inner peripheral surface 13c of the braking drum 13 is provided with a number of openings at equal intervals in the circumferential direction, and a ferromagnetic plate 21 is fitted and fixed in each opening. In practice, the ferromagnetic plate 21 is cast when the outer peripheral wall 18a is cast from aluminum.

A plurality of actuators (not shown) are supported at equal intervals in the circumferential direction on the frame plate 31 having the reinforcing ribs 31a. The actuator fits a piston into a cylinder to define a pair of fluid pressure chambers, and a magnet support cylinder 19 is attached to an end of a rod 17 projecting from the piston to the inner space 23 of the guide cylinder 18.
Will be combined. The magnet support cylinder 19 is the inner space 2 of the guide cylinder 18.
3 is movably supported in the axial direction. Magnets 20 facing each ferromagnetic plate 21 are coupled to the outer peripheral wall of the magnet support cylinder 19 so that the polarities are alternately different in the circumferential direction.

At the time of braking, as shown in FIG. 1, the magnet support cylinder 19 is moved by the brake rod 13 by the rod 17 of the actuator.
Is protruded into the inside of. The rotating braking drum 13 is a magnet 2
0 to the inner peripheral surface 13 of the braking drum 13 through the ferromagnetic plate 21
When crossing the magnetic field reaching c, an eddy current is generated in the braking drum 13, and the braking drum 13 generates a braking torque. The braking drum 13 generates heat due to the eddy current, and is cooled by the outside air directly or via the cooling fin 13a. At the time of braking, a magnetic circuit 40 is formed between the magnet support cylinder 19 and the braking drum 13 as shown in FIG.

When the brake is not applied, the magnet support cylinder 19 is moved to the left in FIG. 1 by the actuator, and is withdrawn from the brake drum 13, so that the magnet 20 does not exert a magnetic field on the brake drum 13 and the brake drum 13 applies the braking torque. Does not occur.

In the present invention, a thick plate is not simply curved into an arc shape to form a ferromagnetic plate in order to prevent the ferromagnetic plate 21 from falling off from the guide cylinder 18, but is typified by FIG. In this manner, the outer half 51 and the inner half 61 of the molding surface 56 are each formed in a truncated pyramid shape, and the bottom surfaces of the pyramids are overlapped with each other to form a three-dimensional shape. For more information,
Regarding the cross-sectional shape of the ferromagnetic plate 21 to be die-forged or cast, the circumferential end of the ferromagnetic plate 21 is reduced so that the dimension in the circumferential direction becomes shorter as approaching the outer surface facing the braking drum 13 from the mating surface 56. The wall is inclined. As a result, the magnetic flux from the magnet 20 to the braking drum 13 is concentrated, and a decrease in the magnetic flux density is suppressed. However, the inclination angle (gradient) of the wall surface of the circumferential end of the ferromagnetic plate 21 with respect to the mold matching surface 56
Is too small, the magnetic flux is saturated. According to the results of the experiment, the inclination angle of the wall surface at the circumferential end of the ferromagnetic plate 21 is optimally about 75 °.

In the embodiment shown in FIGS. 3 and 4, the outer half 51 of the arc-shaped curved mating surface 56 of the ferromagnetic plate 21 to be die-forged, that is, the outer half having the outer surface 51b facing the braking drum 13 is shown. The side section of the portion 51 is formed in a trapezoidal shape, and the magnet 2
The side surface cross section of the inner half portion 61 having the inner surface 61b facing 0 is trapezoidal. A ridge (bead) 50 is formed on the connection portion between the outer half portion 51 and the inner half portion 61, that is, on the mold matching surface 56 so as to surround the entire periphery of the ferromagnetic plate 21. In other words,
The outer half portion 51 of the ferromagnetic plate 21 has a wall surface 51a at the circumferential end,
51c is inclined such that its circumferential dimension gradually decreases as it approaches the outer surface 51b from the molding surface 56. The inner half 61 of the ferromagnetic plate 21 is also slightly inclined so that the circumferential dimension gradually decreases as the inner wall surfaces 61a and 61c of the ferromagnetic plate 21 approach the inner surface 61b from the mold mating surface 56 for convenience of die forging. .

As shown in FIG. 4, the wall surface 51d at the axial end of the outer half portion 51 of the ferromagnetic plate 21 is inclined such that the axial dimension becomes gradually shorter as the outer surface 51b is approached from the mating surface 56. You. The wall surface 61d at the axial end of the inner half portion 61 of the ferromagnetic plate 21 is also slightly inclined so that the axial dimension gradually decreases as approaching the inner surface 61b from the molding surface 56.

In the above embodiment, the ridges (beads) 5
0 is a wall surface 51a, 51c, 61a, 61c at the circumferential end.
And only one of the wall surfaces 51d and 61d at the axial end. If the wall surfaces 51a and 51c at the circumferential end of the ferromagnetic plate 21 and the wall surfaces 61a and 61c are inclined, as shown in FIG. So that and are coplanar,
That is, the front cross section of the ferromagnetic plate 21 may be configured to be substantially rectangular.

In the embodiment shown in FIG. 6, with respect to the shape of the side cross section of the ferromagnetic plate 21, the wall surfaces 51a and 51c at the circumferential end of the outer half portion 51 are not simply inclined surfaces, but are formed from the molding surface 56 to the outer surface. The magnetic flux directed from the magnet 20 to the brake drum 13 is narrowed by forming a curved surface narrowed in an arc shape to 51b. The front sectional shape of the ferromagnetic plate 21 is the same as that shown in FIGS. Can be configured.

The embodiment shown in FIGS.
No bead is provided along the line. FIG.
In the embodiment shown in FIG. 8, with respect to the side cross section of the ferromagnetic plate 21, the wall surfaces 51a and 51c at the circumferential end of the outer half portion 51 are
It is inclined so that the circumferential dimension is gradually reduced as it approaches the outer surface 51b from the mating surface 56. The wall surfaces 61a and 61c at the circumferential end of the inner half portion 61 of the ferromagnetic plate 21 are inclined such that the circumferential dimension gradually decreases as approaching the inner surface 61b from the molding surface 56. As shown in FIG.
As for the front cross section of the ferromagnetic plate 21, the wall surface 51d at the axial end of the outer half portion 51 is inclined such that the axial dimension gradually decreases as the outer surface 51b approaches the outer surface 51b from the mating surface 56. The wall surface 61d at the axial end of the inner half portion 61 of the ferromagnetic plate 21 is inclined such that the axial dimension becomes gradually shorter as it approaches the inner surface 61b from the molding surface 56.

In each of the above-described embodiments, the front section of the ferromagnetic plate 21 is configured to be symmetrical, but as shown in FIG.
Considering the flow of magnetic flux during braking (the loop shape of the magnetic circuit), the inclination of the one wall surface 51d at the axial end of the outer half portion 51 is moderately reduced (the inclination angle with respect to the mold matching surface 56 is reduced). As shown in FIG. 10, even if the inclination angle of one wall surface 51d at the axial end of the outer half portion 51 and the inclination angle of the other wall surface 61d at the axial end of the inner half portion 61 are reduced. Good.

In the present invention, as described above, since the area of the outer surface 51b and the inner surface 61b of the ferromagnetic plate 21 is smaller than the area of the molding surface 50, the ferromagnetic plate 21 is cast into the outer peripheral wall 18a of the guide cylinder 18. Even if the ferromagnetic plate 21 receives the attractive force of the magnet 20, it can be prevented from falling off the guide cylinder 18 by the wedge effect.

In the above-described embodiment, the magnet support cylinder is reciprocated in the axial direction with respect to the braking drum, so that the magnet is positioned between the braking position where the magnet faces the ferromagnetic plate and the non-braking position where the magnet does not face the ferromagnetic plate. Although the switching type eddy current reduction device has been described, the present invention is not limited to this.
No. 1 for the braking drum as disclosed in
By rotating two magnet support cylinders, a braking position in which two magnets having the same polarity face a common ferromagnetic plate and a braking position in which two magnets having different polarities
An eddy current reduction device of a type in which two magnets are switched to a non-braking position facing a common ferromagnetic plate, and a magnet support cylinder which is immovable inside a braking drum as disclosed in JP-A-4-12659. A magnet support cylinder is disposed, and one of the magnet support cylinders is rotated so that the magnets having the same polarity of both magnet support cylinders entirely face the common ferromagnetic plate, and a braking position where both magnets are supported. The present invention is also applicable to an eddy current reduction device of a type in which a pair of magnets having different cylinder polarities is switched to a non-braking position in which the common ferromagnetic plate and the entire magnet face each other.

[0024]

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 coaxially arranged inside a braking drum made of a conductor connected to a rotating shaft. A large number of ferromagnetic plates are connected at equal circumferential intervals to an outer peripheral wall portion of the guide cylinder facing the braking drum, and a magnet support cylinder supported in the inner space of the guide cylinder has a polarity with respect to the ferromagnetic plate. Are coupled alternately in the circumferential direction with a magnet, and the braking position where the magnet applies a magnetic field to the braking drum via the ferromagnetic plate and the non-braking position where the magnet does not apply a magnetic field to the braking drum via the ferromagnetic plate. In the magnet type eddy current reduction device provided with an actuator for moving the magnet support cylinder, the ferromagnetic plate to be die-forged has a wall surface at a circumferential end on an outer surface side facing the brake drum from the mold mating surface. From the mating surface to the braking drum Since it is inclined so that the dimension in the circumferential direction gradually becomes shorter as approaching the outer surface, and at least a part of the wall of the mold mating surface is provided with a retaining wall for preventing the ferromagnetic plate from coming inward, It is possible to prevent the ferromagnetic plate from dropping from the guide cylinder due to the attractive force of the magnet.

[Brief description of the drawings]

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

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

FIG. 3 is a side view of a ferromagnetic plate in the eddy current reduction device.

FIG. 4 is a front view of the ferromagnetic plate.

FIG. 5 is a front sectional view showing another embodiment of the ferromagnetic plate in the eddy current reduction device.

FIG. 6 is a side sectional view showing another embodiment of the ferromagnetic plate in the eddy current reduction device.

FIG. 7 is a side view showing another embodiment of the ferromagnetic plate in the eddy current reduction device.

FIG. 8 is a front view of the ferromagnetic plate.

FIG. 9 is a front view showing another embodiment of the ferromagnetic plate in the eddy current reduction device.

FIG. 10 is a front view showing another embodiment of the ferromagnetic plate in the eddy current reduction device.

[Explanation of symbols]

4: Rotary shaft 5: Mounting flange 5a: Spline hole
7: braking drum 9: boss 9a: flange 1
2: spoke 13: braking drum 13a: cooling fin 13c: inner peripheral surface 18: guide cylinder 18a: outer peripheral wall portion
18b: inner peripheral wall portion 19: magnet support cylinder 20: magnet 21: ferromagnetic plate 2
3: Inner space 50: Retaining ridge 51: Outer half 51
a: Wall surface 51b: Outer surface 51c: Wall surface 51d: Wall surface 56: Molding surface 61: Inner half 61a: Wall surface 61
b: inner surface 61c: wall surface 61d: wall surface

Claims (4)

[Claims] An immovable guide cylinder made of a non-magnetic material and having an inner space having a rectangular cross section is coaxially disposed inside a brake drum made of a conductor connected to a rotating shaft, and the brake drum of the guide cylinder is provided. A large number of ferromagnetic plates are connected to the outer peripheral wall portion at equal intervals in the circumferential direction, and the magnet supporting tube movably supported in the inner space of the guide tube has a polarity with respect to the ferromagnetic plate in the circumferential direction. An actuator that couples the permanent magnets so as to be alternately different, and moves the magnet support cylinder to a braking position in which the permanent magnet faces the ferromagnetic plate and a non-braking position in which the permanent magnet does not face the ferromagnetic plate. In the permanent magnet type eddy current reduction device, the ferromagnetic plate to be die-forged has a circumferential end wall on an outer surface side facing the brake drum from the mold matching surface, and an outer surface facing the brake drum from the mold matching surface. As you approach A permanent magnet type vortex, characterized in that at least a part of the wall of the mold mating surface is provided with a retaining wall for preventing the ferromagnetic plate from coming off inward. Current reducer. 2. An immovable guide cylinder made of a non-magnetic material and having an inner space having a rectangular cross section is coaxially disposed inside a braking drum made of a conductor coupled to a rotating shaft, and an outer peripheral wall of the guide cylinder. A large number of ferromagnetic plates are connected to the portion at equal intervals in the circumferential direction, and a rotatable magnet support tube and a non-rotatable magnet support tube are arranged and supported in the inner space of the guide tube in the axial direction. A permanent magnet is coupled to each magnet support cylinder so that the polarity with respect to the ferromagnetic plate is alternately different in the circumferential direction, and the braking position where the polarity of the permanent magnet of each magnet support cylinder facing each of the ferromagnetic plates is the same, and In a permanent magnet type eddy current reduction device comprising an actuator for rotating one of the magnet support cylinders forward and backward at a non-braking position having a different polarity of a permanent magnet of each magnet support cylinder facing each ferromagnetic plate, The forged ferromagnetic plate is moved from the mating surface to the braking drum. The wall surface of the circumferential end portion of the outer surface of,
The ferromagnetic plate is inclined so that the circumferential dimension gradually decreases as approaching the outer surface facing the braking drum from the mating surface, so that at least a part of the wall of the mating surface prevents the ferromagnetic plate from coming inward. A permanent magnet type eddy current reduction device comprising a retaining wall. 3. The permanent magnet type eddy current reduction device according to claim 1, wherein said retaining wall is a ridge extending along a mold matching surface. 4. The retaining wall inclines the wall surface at the circumferential end of the inner half part of the mold mating surface so that the dimension in the circumferential direction becomes gradually shorter as it approaches the inner surface facing the magnet from the mold mating surface. The permanent magnet type eddy current reduction device according to any one of claims 1 and 2.