JP3770092B2 - Eddy current reducer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an eddy current reduction device that suppresses drag torque caused by a leakage magnetic field from a magnet during non-braking.
[0002]
[Prior art]
As an eddy current speed reducing device using a permanent magnet (hereinafter simply referred to as a magnet), a drum type as disclosed in Japanese Patent Application No. 63-127696 and a Japanese Patent Application No. 63-127695 are disclosed. However, in both cases, the magnetic field from the magnets leaks between the ferromagnetic members when not braked (the strong magnets of rare earths have the ability to go straight to the outside). Because it is strong), it enters the rotating body and generates drag torque magnetically. As a measure for suppressing drag torque, in the drum-type eddy current reduction device disclosed in Japanese Patent Application No. 5-34848, a recess is provided in the central portion in the circumferential direction of the magnetic pole (outer surface) of the magnet, and the inner portion of the recess is not covered. By superimposing magnetic reinforcement plates or combining weak magnetic reinforcements, the strength of the magnet's indented portion is increased, and the strength of the magnetic field from the indentation is reduced, so that the magnetism between the ferromagnetic members is reduced. Prevents leakage.
[0003]
However, it is difficult to sufficiently suppress the magnetic field passing between the non-braking ferromagnetic members when the magnet is provided with a non-magnetic reinforcing plate. There is a problem that the strength of. In addition, a weak magnetic member is combined with the recess to suppress the magnetic field from the central part in the circumferential direction of the magnet to some extent, and the ferromagnetic member is located on both sides of the non-braking magnet (before and after the rotating direction of the rotating body). A magnetic field is passed through to a certain extent to prevent magnetic leakage from between the ferromagnetic members, but it is still insufficient, reducing the strength of the magnetic field during braking.
[0004]
[Problems to be solved by the invention]
In view of the above-described problems, the problem of the present invention is that when the magnetic field is not braked, the magnetic field reaches the braking drum through the gap between the ferromagnetic members arranged in the circumferential direction of the outer cylinder part of the guide cylinder. An object of the present invention is to provide an eddy current reduction device which is effectively suppressed.
[0005]
[Means for Solving the Problems]
In order to solve the above-described problems, the configuration of the present invention is such that a guide cylinder having an inner cavity with a rectangular cross section is disposed inside a brake drum coupled to a rotating shaft, and a number of magnets are provided in the inner cavity of the guide cylinder. A magnet support cylinder coupled at equal intervals in the circumferential direction is supported so as to be able to rotate in the forward and reverse directions, and a large number of ferromagnetic plates are disposed on the outer cylinder portion of the guide cylinder so as to face the magnet. In the eddy current reduction device for generating a braking force based on an eddy current in the braking drum by a magnetic field passing through the magnetic plate to the braking drum, a shaft provided at a circumferential central portion of the outer surface of the magnet facing the ferromagnetic plate A ferromagnetic plate is coupled to the groove in the direction.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the ferromagnetic plate is coupled to the axial groove provided in the center in the circumferential direction of the outer surface of the magnet. The magnetic field from the central portion in the circumferential direction of the magnet at the non-braking position flows into the ferromagnetic member through the ferromagnetic plate, and magnetic leakage from the gap between the ferromagnetic members to the braking drum or the braking disk as a rotating body is eliminated.
[0007]
【Example】
As shown in FIG. 1, the drum-type eddy current reduction device includes a brake drum 7 coupled to a rotating shaft 1 and a guide cylinder made of a non-magnetic material having a rectangular cross section disposed inside the brake drum 7. 10 and a magnet support cylinder 14 supported in the inner space of the guide cylinder 10 so as to be rotatable forward and backward. A brake drum 7 having a large number of cooling fins 8 on its outer peripheral surface is coupled at one end to the tips of a large number of support arms 6 extending radially from a boss portion 5 coupled to the rotary shaft 1. The guide tube 10 is fixed to, for example, a wall portion of a vehicle transmission, and plate-like ferromagnetic members 15 are coupled to the outer tube portion 10a at equal intervals in the circumferential direction. Preferably, the ferromagnetic member 15 is cast when casting the guide tube 10 from aluminum. The magnet support cylinder 14 made of a ferromagnetic material is supported on the inner cylinder portion 10b of the guide cylinder 10 via the slide bearing 12 and on the side wall via the thrust bearing 12a, and the slot on the side wall of the guide cylinder 10 from the magnet support cylinder 14 is supported. A rod 16 projecting outside through 10c is connected to a rod 17a of a fluid pressure actuator. The actuator 20 is fitted with a piston 17 in a cylinder 18 so that fluid chambers are defined at both ends, and a rod 17a protrudes from the piston 17 to the outside. Magnets 24 are coupled to the outer peripheral surface of the magnet support cylinder 14 at equal intervals in the circumferential direction so that the polarities facing the ferromagnetic member 15 are alternately different in the circumferential direction.
[0008]
As shown in FIG. 2, step portions 35 are formed at both ends of each magnet 24 in the circumferential direction, and a stopper 36 made of a nonmagnetic material is interposed between the step portions 35 of the magnets 24 arranged in the circumferential direction. The bolt 37 is fastened to the magnet support cylinder 14. In the braking position shown in FIG. 2, each magnet 24 entirely overlaps the ferromagnetic member 15. At this time, the magnetic field from the magnet 24 reaches the brake drum 7 through the ferromagnetic member 15, and a magnetic circuit w is formed between the brake drum 7 and the magnet support cylinder 14. When the rotating brake drum 7 receives a magnetic field from the magnet 24, the actuator 20 generates a braking torque based on the eddy current.
[0009]
When the actuator 20 rotates the magnet support cylinder 14 by a half arrangement pitch of the magnets 24, the two magnets 24 arranged in the circumferential direction partially overlap the ferromagnetic member 15 as shown in FIG. A short-circuit magnetic circuit z is generated between the magnet support cylinder 14 and the brake drum 7 does not generate a braking torque. However, the direction of the magnetic field from the outer surface of the magnet 24 toward the braking drum 7 has a curvilinearity as the magnet 24 becomes stronger, so that the magnetic field from the central portion in the circumferential direction of each magnet 24 is a non-magnetic outer cylinder portion 10a. When the brake drum 7 is reached after passing through, the brake drum 7 generates drag torque.
[0010]
In the present invention, in order to suppress the drag torque, the ferromagnetic plate 34 is coupled by embedding the ferromagnetic plate 34 in an axial groove provided in the central portion in the circumferential direction of the magnet 24. Are connected so that the magnetic field from the circumferential center of the magnet 24 is guided to the adjacent ferromagnetic member 15 by the ferromagnetic plate 34 and does not reach the braking drum 7. .
[0011]
As shown in FIG. 4, the circumferential dimension b of the ferromagnetic plate 34 may be narrower than the distance a between the ferromagnetic members 15, but preferably, if the circumferential dimension b is larger than the distance a, The leakage magnetic field from the magnet 24 to the braking drum 7 can be completely prevented. However, as shown in FIG. 2, if the distance a (see FIG. 4) between the ferromagnetic members 15 is made too small, a part of the magnetic field constituting the magnetic circuit w is between the ferromagnetic members 15 even during braking. Since there is a risk of short-circuiting and the braking ability being diminished, the relationship between the circumferential dimension b and the distance a is obtained experimentally. As shown in FIG. 6, the width of the groove 34a provided at the center in the circumferential direction of the outer surface of the magnet 24 may be the same as that of the ferromagnetic plate 34. However, as shown in FIG. ) May be longer than the width of the ferromagnetic plate 34. In this case, the distance between the circumferential center of the magnet 24 and the brake drum 7 is increased, and not only the magnetic field reaching the brake drum 7 is weakened, The ferromagnetic plate 34 induces (curves) a magnetic field to the ferromagnetic member 15.
[0012]
The means for coupling the magnet 24 to the magnet support cylinder 14 is shown in FIG. 2, but as shown in FIG. 8, a circumferential groove having the same width as the axial dimension of the magnet 24 provided on the outer peripheral surface of the magnet support cylinder 14 is used. The magnet 24 may be engaged with the magnet 14 a, the ferromagnetic plate 34 may be overlapped with the groove 34 a of the magnet 24, and the magnet support tube 14 may be fastened with one or two bolts 41.
[0013]
As shown in FIG. 9, the outer tube portion 10a of the guide tube 10 is formed by alternately forging or casting iron, which is a magnetic body, to alternately form thick portions and thin portions in the circumferential direction. The thickness may be changed to 15, and nickel may be melted into the thin portion to change to a non-magnetic austenite structure (corresponding to the portion 15a). Alternatively, the outer cylindrical portion 10a having a uniform wall thickness may be formed from martensite or ferritic stainless steel, and a ferromagnetic portion and a nonmagnetic portion or a weak magnetic portion may be formed by heat treatment.
[0014]
In the embodiment shown in FIG. 10, a projecting piece 15b extending in the circumferential direction along the inner surface of the ferromagnetic member 15 is provided on the end wall surface in the circumferential direction of the ferromagnetic member 15 of the outer cylinder portion 10a. In other words, the distance between the ferromagnetic members 15 is increased on the outer peripheral side and gradually decreased toward the inner peripheral side. At the non-braking position of the magnet support cylinder 14, the magnetic field from the central portion in the circumferential direction of the magnet 24 is guided to the ferromagnetic member 15 by the ferromagnetic plate 34 and does not reach the braking drum 7.
[0015]
In the embodiment shown in FIG. 11, the configuration and the function and effect of the ferromagnetic plate 34 with respect to the magnet 24 are as described above, but the circumferential end walls 15 c and 15 d of the ferromagnetic member 15 of the outer cylinder portion 10 a are provided with diameters. The end wall surfaces 15c and 15d are configured to be slightly overlapped with a gap in the radial direction. Since the magnetic field from the circumferential center of the magnet 24 toward the braking drum 7 is blocked by the end wall surfaces 15c and 15d at the non-braking position of the magnet support cylinder 14, drag torque is suppressed.
[0016]
As shown in FIGS. 12 and 13, the present invention is also applied to a disk-type eddy current reduction device. In the disc-type eddy current reduction device, a pair of left and right braking discs 53 are coupled to the rotating shaft 52, and a guide cylinder 55 made of a non-magnetic material having an inner space with a rectangular cross section is disposed between both. A magnet support cylinder 63 is supported in the inner space of the guide cylinder 55 so as to be able to rotate forward and backward. Although not shown, the guide tube 55 is fixed to a non-rotating portion of the vehicle body. The brake disc 53 is provided with an air guide path 53c for cooling, and the boss portion 53a is spline fitted to the rotary shaft 52 and fixed so as not to move in the axial direction. A plurality of spokes 55b extend in a radial direction from a boss portion 55a supported on the rotary shaft 52 by a bearing 54 so as to be relatively rotatable, and a guide tube 55 is coupled to the tip of the spoke 55b. Ferromagnetic members 56 made of fan-shaped or trapezoidal plates facing the brake disc 53 are coupled to both side walls 55c of the guide tube 55 at equal intervals in the circumferential direction.
[0017]
The magnet support cylinder 63 is formed by connecting the same number of magnets 62 as the ferromagnetic member 56 between the outer cylinder 60 and the inner cylinder 58 made of a non-magnetic material at equal intervals in the circumferential direction. Is supported by the inner cylinder portion. The magnets 62 are arranged so that the polarities facing the left and right ferromagnetic members 56 are alternately reversed in the circumferential direction. Preferably, sliding plates 64 are coupled to both side surfaces of the magnet 62 so that smooth sliding with the ferromagnetic member 56 can be obtained.
[0018]
In the present embodiment, in order to prevent the magnetic field from leaking from the circumferential central portion of the magnet 62 to the braking disk 53 through the gap between the ferromagnetic member 56 and the ferromagnetic member 56 at the non-braking position of the magnet support cylinder 63. Ferromagnetic plates 70 are coupled to radial grooves provided in the circumferential center of both sides of the magnet 62. At the non-braking position of the magnet support cylinder 63, the magnetic field from the circumferential central portion of the magnet 62 toward the braking disc 53 is guided to the ferromagnetic member 56 by the ferromagnetic plate 70 to form a short circuit magnetic circuit z.
[0019]
【The invention's effect】
As described above, according to the present invention, a guide cylinder having an inner cavity with a rectangular cross section is disposed inside a brake drum coupled to a rotating shaft, and a large number of magnets are arranged at equal intervals in the inner circumference of the guide cylinder. A magnet support cylinder to be coupled is supported so as to be able to rotate forward and backward, and a large number of ferromagnetic plates are disposed on the outer cylinder portion of the guide cylinder so as to face the magnet, and the magnet passes through the ferromagnetic plate and passes through the ferromagnetic plate. In the eddy current reduction device for generating a braking force based on an eddy current in the braking drum by a magnetic field applied to the braking drum, a strong force is exerted on an axial groove provided in a circumferential central portion of the outer surface of the magnet facing the ferromagnetic plate. A magnetic plate is coupled, and the magnetic field from the center in the circumferential direction of the magnet at the non-braking position flows into the ferromagnetic member through the ferromagnetic plate, and from the gap between the ferromagnetic members to the braking drum or the braking disk. Magnetic leakage is eliminated and drag torque is suppressed.
[Brief description of the drawings]
FIG. 1 is a front sectional view of an eddy current reduction device according to the present invention.
FIG. 2 is a side sectional view of the eddy current reduction device during braking.
FIG. 3 is a side cross-sectional view of the eddy current reduction device when not braked.
FIG. 4 is a side sectional view showing a dimensional relationship between a gap between ferromagnetic members and a ferromagnetic plate disposed in a magnet.
FIG. 5 is a side sectional view showing a dimensional relationship between a gap between ferromagnetic members and a ferromagnetic plate disposed in a magnet.
FIG. 6 is a side view showing a relationship between a groove of a magnet and a ferromagnetic plate.
FIG. 7 is a side view showing a relationship between a groove of a magnet and a ferromagnetic plate.
FIG. 8 is a side sectional view showing a magnet support structure with respect to a magnet support cylinder.
FIG. 9 is a side cross-sectional view of an outer cylinder portion of a guide cylinder.
FIG. 10 is a side cross-sectional view showing the relationship between the ferromagnetic member and the magnet in the outer tube portion of the guide tube.
FIG. 11 is a side sectional view showing a relationship between a ferromagnetic member and a magnet in an outer cylinder portion of the guide cylinder.
FIG. 12 is a front sectional view of a braking disk type eddy current reduction device.
FIG. 13 is a plan sectional view showing the eddy current reduction device developed in the circumferential direction.
[Explanation of symbols]
1: Rotating shaft 5: Boss part 6: Support arm 7: Braking drum 8: Cooling fin 10: Guide cylinder 10a: Outer cylinder part 10b: Inner cylinder part 12: Sliding bearing 12a: Thrust bearing 14a: Groove 14: Magnet support cylinder 15: Ferromagnetic member 15b: Projection piece 15c, 15d: End wall surface 20: Actuator 24: Magnet 34: Ferromagnetic plate 34a: Groove 52: Rotating shaft 53: Braking disc 53a: Boss portion 54: Bearing 53c: Air guide path 55: Guide tube 55a: Boss portion 56: Ferromagnetic member 55b: Spoke 57: Bearing 55c: Side wall 58: Inner tube 62: Magnet 63: Magnet support tube 64: Sliding plate 70: Ferromagnetic plate

Claims (4)

A guide cylinder having an inner cavity with a rectangular cross section is disposed inside the brake drum coupled to the rotating shaft, and a magnet support cylinder for coupling a number of magnets at equal intervals in the circumferential direction is arranged in the inner cavity of the guide cylinder. A large number of ferromagnetic plates are disposed so as to be pivotably supported so as to face the magnet on the outer cylinder portion of the guide cylinder, and an eddy current is generated by a magnetic field extending from the magnet to the brake drum through the ferromagnetic plate. In the eddy current reduction device that generates a braking force based on the above-described braking drum, a ferromagnetic plate is coupled to an axial groove provided in a circumferential central portion of the outer surface of the magnet facing the ferromagnetic plate. An eddy current reduction device. 2. The eddy current reduction device according to claim 1, wherein a dimension in a circumferential direction of the ferromagnetic plate is wider than a distance between the ferromagnetic members of the outer cylinder portion. 2. The eddy current reduction device according to claim 1, wherein a dimension in a circumferential direction of the ferromagnetic plate is narrower than an interval between the ferromagnetic members of the outer cylinder portion. A stationary guide cylinder having an inner space with a rectangular cross section made of a non-magnetic material is disposed between a pair of left and right braking disks coupled to the rotating shaft, and a plurality of guide cylinders on both side walls of the guide cylinder facing the braking disk. A ferromagnetic member is coupled at equal intervals in the circumferential direction, and a magnet support cylinder that couples a number of magnets at equal intervals in the circumferential direction is supported in the inner space of the guide cylinder so as to be able to rotate forward and backward. A vortex provided with means for rotating the magnet support cylinder between a braking position where the magnet faces the magnetic member entirely and a non-braking position where the two magnets partially face the ferromagnetic member of the magnet support cylinder 2. An eddy current reduction device according to claim 1, wherein a ferromagnetic plate is coupled to an axial groove provided in a circumferential central portion of the outer surface of the magnet facing the ferromagnetic plate.

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