JP3687380B2 - Eddy current reducer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention mainly relates to an eddy current reduction device for assisting a friction brake of a large vehicle, and more particularly to an eddy current reduction device in which a magnetic pole of a magnet is directed in a circumferential direction of a magnet support cylinder.
[0002]
[Prior art]
As shown in FIGS. 12 and 13, the conventional eddy current speed reducer includes an output rotating shaft 49 supported by a gear box 44 of a vehicle transmission via a bearing 45 and a mounting flange 48 fitted by a spline 50 and a nut. 51, the end wall of the brake drum of the parking brake 56 and the flange 10 of the brake drum 2 are overlapped with the flange 48 and fastened by the bolt 47 and the nut 53. The base end portion of the brake drum 2 is coupled to the tip end of the spoke 9 that protrudes in the radial direction from the flange 10, and the guide cylinder 4 having an inner space portion 57 having a rectangular cross section is disposed inside the brake drum 2. A large number of ferromagnetic plates 5 are coupled to the outer cylinder portion 4 a of the guide cylinder 4. A magnet support cylinder 17 made of a magnetic material is accommodated in the inner space 57 of the guide cylinder 4 so as to be slidable in the axial direction, and the same number of magnets 7 as the ferromagnetic plates 5 are arranged on the outer peripheral surface of the magnet support cylinder 17 at equal intervals in the circumferential direction. The magnetic poles facing the ferromagnetic plate 5 are coupled so as to be alternately different in the circumferential direction.
[0003]
The guide cylinder 4 is formed by connecting a U-shaped section made of a magnetic material and an inverted L-shaped cylinder section for connecting the ferromagnetic plate 5 to a plurality of bolts 54, and the left end of the guide cylinder 4 is a gear. The support frame 31 having the reinforcing ribs 43 fitted and fixed to the shaft portion 46 of the box 44 is coupled via bolts 42 and 41.
[0004]
At the time of braking, when the magnet support cylinder 17 is pushed into the position shown in the figure by an actuator (not shown) through the rod 55, the magnetic field extends from the magnet 7 to the braking drum 2 rotating through the ferromagnetic plate 5 and to the braking drum 2. A braking torque based on the current is generated. During non-braking, if the magnet support cylinder 17 is moved to the left and pulled out from the inside of the braking drum 2, the magnetic field of the magnet 7 does not reach the braking drum 2 and the braking torque is eliminated.
[0005]
In the eddy current reduction device described above, a wedge-shaped presser plate 28 pressed from the outer peripheral side between adjacent magnets 7 is fastened to the magnet support cylinder 17 by bolts 29. The magnet 7 has polarity on the inner surface that contacts the magnet support cylinder 17 and the outer surface that faces the ferromagnetic plate 5.
[0006]
In the eddy current reduction device shown in FIG. 14, the braking drum 2 having the cooling fin 2 a is coupled to the tip of the spoke 9 extending radially from the flange 10, and the inner cylinder portion of the guide cylinder 4 disposed inside the braking drum 2. A rotatable magnet support cylinder 17 and a stationary magnet support cylinder 16 are supported by 4b, and the magnets 6 and 7 coupled thereto are passed through the ferromagnetic plate 5 embedded in the outer cylinder portion 4a of the guide cylinder 4. A magnetic field is applied to the brake drum 2. When pressurized air is supplied from one of the pipes 34 and 35 to one end chamber of the cylinder 23 of the pneumatic actuator 22, the movable magnet support cylinder 17 is rotated by the arrangement pitch of the magnets 7 by the piston. At this time, the magnetic poles of the magnets 6 and 7 arranged in the axial direction are the same, and a magnetic circuit is provided between the magnet support cylinders 16 and 17 and the brake drum 2 via two sets of magnets 6 and 7 adjacent in the circumferential direction. Occurs and exerts braking power. On the other hand, when the magnet support cylinder 17 is returned to the original position by the actuator 22, the magnetic poles of the magnets 6 and 7 aligned in the axial direction are opposite to each other, and a short circuit occurs between the magnet support cylinders 16 and 17 and the ferromagnetic plate 5. A magnetic circuit is generated, and no magnetic field is applied to the brake drum 2.
[0007]
As described above, in the conventional eddy current reduction device, the direction of the magnetic pole of each magnet is in the radial direction, so that the circumferential dimension of the magnet is relatively large, and the radial dimension or thickness of the magnets 6 and 7 is increased. It is necessary to increase the thickness considerably.
[0008]
[Problems to be solved by the invention]
In view of the above-described problems, the present invention is to provide an eddy current reduction device that can reduce the leakage magnetic flux during non-braking because the volume of the magnet is small and the braking force is large.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the structure of the present invention comprises a non-magnetic material in which a guide cylinder is disposed inside a brake drum coupled to a rotating shaft, and the guide cylinder is supported so as to be movable in the axial direction of the rotating shaft. A large number of circumferentially extending magnets are supported on the outer peripheral surface of the magnet support cylinder so that the polarities of the circumferential end portions of the magnets are the same polarity at the opposite end surfaces. Holding the magnetic body, projecting the outer surface of the ferromagnetic body to the inner peripheral surface of the brake drum rather than the magnet and approaching the inner peripheral surface of the brake drum so as to face each other, and reciprocally move the magnet support cylinder in the axial direction Thus, switching between a braking position and a non-braking position is performed .
Further, according to the configuration of the present invention, a guide cylinder is disposed inside a brake drum coupled to a rotation shaft, and a rotatable magnet support cylinder made of a nonmagnetic material and an immobile magnet support cylinder are arranged on the guide cylinder. A number of circumferentially extending magnets are supported on the outer peripheral surface of each magnet support cylinder so that the polarities of the circumferentially spaced ends are opposite to each other. A ferromagnetic material is sandwiched between magnets, the outer surface of the ferromagnetic material protrudes from the magnet to the inner peripheral surface of the brake drum, and closes and opposes the inner peripheral surface of the brake drum. The magnet support cylinder is switched between a braking position and a non-braking position by rotating forward and backward .
[0010]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the magnetic poles are oriented in the circumferential direction and the opposing magnetic poles of the magnets adjacent in the circumferential direction are formed in the same polarity, and the ferromagnetic material facing the ferromagnetic plate of the guide cylinder is disposed between the magnets arranged in the circumferential direction. Arrange. The magnetic field from the magnet reaches the braking drum via a ferromagnetic material extending radially outward from the magnetic pole. Compared to the conventional eddy current reduction device, the ferromagnetic material from the magnet directly faces the inner peripheral surface of the brake drum, so that an efficient magnetic circuit is formed.
[0011]
【Example】
FIG. 1 is a side sectional view of an eddy current reduction device according to the present invention. In the present invention, a large number of magnets 6 are arranged at equal intervals in the circumferential direction with respect to the outer peripheral surface of the magnet support cylinder 16 made of a non-magnetic material, and the magnetic poles face the circumferential direction and the opposing magnetic poles of the adjacent magnets 6 are the same. The wedge-shaped ferromagnetic material 15 is disposed between the magnets 6. The ferromagnetic body 15 protrudes outward in diameter from the magnet 6 and approaches the inner peripheral surface 2 b of the braking drum 2. The outer surface side of the magnet 6 may be left as it is, but the cover plate 8 made of a non-magnetic material may be spanned between the ferromagnetic materials 15.
[0012]
In the embodiment shown in FIG. 1, a wedge-shaped ferromagnetic material 15 that is sufficiently thicker than the thickness of the magnet 6 is sandwiched between the magnets 6 arranged in the circumferential direction, but there may be a gap between the two. Absent. Moreover, it is preferable to apply a coating for heat countermeasures on the outer surface of the magnet 6. Instead of coating, the cover plate 8 may be bridged between the ferromagnetic bodies 15 adjacent to each other in the circumferential direction so as to cover the outer surface of the magnet 6.
[0013]
In the present invention, the guide cylinder is not shown in the figure, but it may be of a U-shaped cross-section with the outer peripheral side open or a cylindrical one that externally fits the magnet support cylinders 16 and 17, and other configurations are shown in FIGS. Or it is the same as that shown in FIG. When the magnet support cylinder 16 is pushed into the brake drum 2 during braking, a magnetic circuit y shown in FIG. 1 is generated between the magnet 6 and the brake drum 2, and a braking force based on eddy current is generated in the brake drum 2. . When the magnet support cylinder 16 is pulled out of the brake drum 2 during non-braking, the magnetic field does not reach the brake drum 2.
[0014]
If two magnet support cylinders 16 shown in FIG. 1 are prepared, one is a stationary magnet support cylinder 16 and the other is a stationary magnet support cylinder 17, an eddy current reduction device of the type shown in FIG. 14 is configured. If the polarities of the magnets 6 and 7 of the magnet support cylinders 16 and 17 arranged in the axial direction are the same during braking, the magnetic circuit y is provided between the braking drum 2 and the magnet 6 as shown in FIG. Occurs, and a braking force is generated in the braking drum 2. If the movable magnet support cylinder 17 is rotated by the arrangement pitch of the magnets 7 during non-braking so that the magnetism of the magnets 6 and 7 of the magnet support cylinders 16 and 17 aligned in the axial direction is reversed, FIG. As shown in FIG. 2, a short-circuit magnetic circuit w is generated between the ferromagnetic bodies 15 and 15a and the magnets 6 and 7, and no magnetic field is applied to the braking drum 2. Also, an arbitrary braking force can be obtained by setting the movable magnet support cylinder 17 to an arbitrary position between braking and non-braking.
[0015]
In the embodiment described above, the magnets 6 and 7 are plate-like, and the inner surface 72 has an arcuate cross section in close contact with the outer surface of the magnet support cylinder 16, but the shape of the magnets 6 and 7 is limited to this. 3, the inner surface 72 may be a cylindrical surface and the outer surface may be flat as shown in FIG. 3, and the outer surface 71 and the inner surface 72 may be bent into a roof shape as shown in FIG. As shown, the outer surface 71 and the inner surface 72 may be cylindrical. Further, as shown in FIG. 6, the inner surface 72 may be a flat surface and the outer surface 71 may be a roof shape, and as shown in FIG. 7, the inner surface 72 may be a flat surface and the outer surface 71 may be a cylindrical shape. Further, as shown in FIGS. 8 to 10, the magnets 6 and 7 may be formed in a rectangular parallelepiped or a cube.
[0016]
As shown in FIG. 11, in the present invention, the same effect can be obtained even if an electromagnet is used instead of the permanent magnet. That is, the outer peripheral surface of the magnet support cylinder 16 made of a non-magnetic material is coupled with the ferromagnetic material 15 projecting radially outward and facing the inner peripheral surface 2b of the brake drum 2, and between the ferromagnetic materials 15. If the coil 13 is wound around the circumferentially disposed iron core 12 disposed on the electromagnet 6A to form the electromagnet 6A and current is supplied to both ends of the coil 13 from the power source 40, the electromagnet 6A and the circumference are similar to the embodiment shown in FIG. A magnetic circuit y is generated between the two ferromagnetic bodies 15 arranged in the direction and the braking drum 2, and a braking force is generated in the braking drum 2.
[0017]
【The invention's effect】
In short, in the present invention, a magnet support cylinder made of a non-magnetic material is disposed inside a brake drum coupled to a rotating shaft, and a large number of circumferentially extending magnets are arranged at equal intervals in the circumferential direction on the outer peripheral surface of the magnet support cylinder. In addition, the ends of the circumferential direction are supported so that the polarities of the opposite end faces are the same, and the ferromagnetic body is sandwiched between the magnets, and the outer surface of the ferromagnetic body is placed inside the brake drum more than the magnet. Because it protrudes to the peripheral surface and faces the inner peripheral surface of the brake drum close to and facing , the magnetic field from the magnet at the time of braking passes through the ferromagnetic material to the brake drum, and the magnetic circuit bypasses the magnet support cylinder Compared to the above, the braking torque can be greatly improved with the magnet of the same volume.
[0018]
Since the magnet support cylinder simply supports the magnet and does not form a path of the magnetic circuit at the time of braking and non-braking, it can be reduced in weight by being made of a nonmagnetic material such as aluminum.
[0019]
The thickness of the guide cylinder that protects the magnet can be made as thin as possible or the outer cylinder portion can be removed, there is no magnetic leakage to the brake drum during non-braking, and no drag torque is generated.
[0020]
A reduction in braking torque during high-speed rotation is suppressed, and a small and lightweight eddy current reduction device with high braking capability is obtained.
[Brief description of the drawings]
FIG. 1 is a side sectional view of an eddy current reduction device according to a first embodiment of the present invention.
FIG. 2 is a developed plan view of an eddy current reduction device according to a second embodiment of the present invention.
FIG. 3 is a perspective view of a magnet in the eddy current reduction device.
FIG. 4 is a perspective view of a magnet in the eddy current reduction device.
FIG. 5 is a perspective view of a magnet in the eddy current reduction device.
FIG. 6 is a perspective view of a magnet in the eddy current reduction device.
FIG. 7 is a perspective view of a magnet in the eddy current reduction device.
FIG. 8 is a perspective view of a magnet in the eddy current reduction device.
FIG. 9 is a perspective view of a magnet in the eddy current reduction device.
FIG. 10 is a perspective view of a magnet in the eddy current reduction device.
FIG. 11 is a side sectional view of an eddy current reduction device according to a third embodiment of the present invention.
FIG. 12 is a front sectional view of a conventional eddy current reduction device.
FIG. 13 is a perspective view showing a main part of the eddy current reduction device.
FIG. 14 is a perspective view of another conventional eddy current reduction device.
[Explanation of symbols]
2: Braking drum 2b: Inner peripheral surface 4: Guide tube 4a: Outer tube portion 4b: Inner tube portion 5: Ferromagnetic plate 6: Magnet 6A: Electromagnet 7: Magnet 8: Cover plate 9: Spoke 10: Flange 15: Strong Magnetic body 15a: Ferromagnetic body 16: Magnet support cylinder 17: Magnet support cylinder 22: Actuator 23: Cylinder 25: Empty part 28: Presser plate 29: Bolt 31: Support frame

Claims (2)

A guide cylinder is disposed inside a brake drum coupled to a rotating shaft, and is arranged on the outer peripheral surface of a magnet support cylinder made of a non-magnetic material supported on the guide cylinder so as to be movable in the axial direction of the rotating shaft. The extending magnet is supported at equal intervals in the circumferential direction and the polarities of the end portions in the circumferential direction are opposite to each other, the ferromagnetic material is sandwiched between the magnets, and the outer surface of the ferromagnetic material is magnetized. Moreover projecting to the inner peripheral surface of the brake drum, approaching and facing the inner peripheral surface of the brake drum, and reciprocating the magnet support tube in the axial direction to switch between the braking position and the non-braking position. An eddy current reduction device characterized by that. A guide cylinder is disposed inside a brake drum coupled to the rotation shaft, and a rotatable magnet support cylinder made of a non-magnetic material and a stationary magnet support cylinder are arranged side by side in the guide cylinder and supported in the axial direction of the rotation shaft. A large number of circumferentially extending magnets are supported on the outer peripheral surface of each magnet support cylinder so that the polarities of the circumferential end portions of the magnets are the same polarity at the opposite end surfaces. The outer surface of the ferromagnetic material protrudes to the inner peripheral surface of the braking drum from the magnet, and approaches the inner peripheral surface of the braking drum so as to face the outer surface of the braking drum. An eddy current reduction device characterized by switching between a braking position and a non-braking position by rotating .

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