JP3937743B2 - Eddy current reducer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention mainly relates to an eddy current reduction device that assists a friction brake of a large vehicle, and more particularly to an eddy current reduction device that can easily control a braking torque.
[0002]
[Prior art]
As proposed in Japanese Patent Application Nos. 1-218499 and 2-201820, the eddy current reduction device uses a permanent magnet (hereinafter simply referred to as a magnet) and an electromagnet. There is. The former is small (compact) and lightweight, but the magnet (magnet support tube) must be moved to control the braking torque. In particular, in recent years, the performance of rare earth magnets has improved, and the eddy current reduction device of the magnet type has been reduced in size and weight. However, control of the braking torque requires a large driving force to move the magnet support cylinder. Powerful actuators (pneumatic, hydraulic, electric, etc.) are required, and the response is somewhat difficult. The latter only needs to adjust the current of the electromagnet and is excellent in controllability of braking torque, but has a problem that the weight of the device is large.
[0003]
[Problems to be solved by the invention]
In view of the above problems, an object of the present invention is to provide an eddy current reduction device that is relatively small and light and does not require power for switching between braking and non-braking.
[0004]
[Means for solving problems]
In order to solve the above problems, the configuration of the present invention is such that one of an annular body made of a conductor and an annular yoke is supported on a rotating shaft and the other is supported on a non-rotating portion of the vehicle body, and the peripheral portion of the annular yoke A large number of iron cores projecting radially outward are provided at equal intervals in the circumferential direction , an electromagnetic coil is wound around the iron core to form an electromagnet, and the polarity of the magnetic pole at the tip of the iron core facing the annular body is circumferential. The permanent magnets, which are arranged so as to be alternately different and are embedded with radial permanent magnets at intermediate positions in the circumferential direction of the iron core adjacent to the circumferential direction of the yoke and whose both sides in the circumferential direction form magnetic poles , and the circumferential direction The electromagnets adjacent to each other form the same magnetic circuit that passes through the annular body during braking.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, a plurality of electromagnets composed of an iron core and an electromagnetic coil are arranged in the circumferential direction, and each iron core composed of a soft magnetic material is connected in a ring shape with a yoke (junction) at the inner end of the inner diameter. The end is opposed to the annular body made of a conductor, and a magnet is embedded in a portion between the iron cores of the yoke. The magnetic poles at the outer ends of the iron cores of the electromagnets are arranged alternately in the circumferential direction such as N, S, N, S,. The magnets are arranged inside the yoke so that the magnetic poles facing each other in the circumferential direction are the same.
[0006]
During braking, when an electromagnetic coil is energized and excited, the magnetic field from the electromagnet and the magnetic field from the magnet are aligned in the circumferential direction (together), and the magnetic circuit is between the annular body (braking disc drum or braking disc). Form. When the rotating annular body crosses the electromagnet and the magnetic field from the magnet, a braking torque based on the eddy current is generated in the annular body. During non-braking, if the energization of the electromagnetic coil is interrupted, the electromagnet is demagnetized, and the magnetic field from the magnet forms a short circuit inside the yoke and does not reach the inside of the annular body, so that no braking torque is generated.
[0007]
In order to control the braking torque, the current of the electromagnetic coil is controlled. Since the magnet is embedded not in the iron core but in the yoke away from the electromagnetic coil, it is hardly affected by the heat of the electromagnetic coil as well as the heat in the annular body.
[0008]
The fixed portion (stator) may have an integral structure of an iron core (magnetic pole piece) made of a soft magnetic material on the outer peripheral portion and an annular yoke on the inner peripheral portion, or the divided member may be fastened with a bolt or the like. In the case of an integral structure, electromagnetic steel sheets can be laminated. In order to protect against external muddy water and the like, the magnet is preferably sealed with a cover.
[0009]
The annular body may be fixed and an electromagnet and a yoke supporting the magnet may be coupled to the rotating shaft. In this case, a water-cooled annular body can be employed. Moreover, the rotor which supports a magnet can be comprised as an armature of an electric motor or a generator. Further, the yoke supporting the magnet and the electromagnet may be disposed on the outer peripheral side, and the annular body may be disposed on the inner peripheral side.
[0010]
【Example】
FIG. 1 is a front sectional view of the eddy current reduction device according to the present invention during braking, and FIG. 2 is a front sectional view of the eddy current reduction device during non-braking. As shown in FIG. 1, iron having cooling fins 2 a on the outer peripheral surface at the tips of a large number of support arms extending radially from a boss portion 16 (see FIG. 4 which is another embodiment) coupled to a rotating shaft 4 . An annular body made of a conductor such as copper or aluminum, that is, a base end portion of the brake drum 2 is joined by welding or the like, and a soft magnetic body, preferably an electromagnetic steel plate is laminated inside the brake drum 2 A large number of iron cores 3 a are projected outward from the periphery of the yoke 3, and are opposed to the inner peripheral surface of the brake drum 2. The yoke 3 is disposed coaxially with the brake drum 2 and is supported by, for example, a bolt 8 on a non-rotating portion of the vehicle. An electromagnet 10 is configured by winding an electromagnetic coil 6 around the iron core 3 a via a winding frame 5. The same number of magnets 7 as the iron cores 3 a are embedded in the yoke 3. Specifically, the yoke 3 is punched from the magnetic steel sheet by a press machine, and at the same time a rectangular opening is punched, and a block-shaped magnet 7 is embedded in the opening. The magnets 7 are arranged so that the end faces in the circumferential direction form magnetic poles and the opposing magnetic poles of the magnets 7 arranged in the circumferential direction have the same polarity.
[0011]
When the electromagnetic coil 6 is energized and excited during braking, the iron core 3a is magnetized as shown in FIG. That is, the magnetic poles of the iron core 3a facing the inner peripheral surface of the brake drum 2 are magnetized so as to be alternately different in the circumferential direction. The magnet 7 is disposed between the iron core 3a and the iron core 3a, that is, the iron core 3a has a rotational phase shifted by a half pitch and is disposed inside the yoke 3, and the magnetic pole of the magnet 7 and the magnetic pole at the inner end of the iron core 3a Are opposite to each other, a magnetic circuit z is formed between the pair of iron cores 3 a and the brake drum 2. When the rotating braking drum 2 crosses the magnetic field from each iron core 3a, a braking torque based on eddy current is generated in the braking drum 2. As shown in FIG. 2, when the energization to the electromagnetic coil 6 is stopped during non-braking, each iron core 3a is not magnetized, and a short-circuit magnetic circuit w as shown is formed in the magnet 7 and the yoke 3, thereby The drum 2 does not exert a magnetic field.
[0012]
In the embodiment shown in FIG. 3, a magnet 7 is embedded in an annular yoke 3 as an annular body coupled to a rotating shaft, and a winding frame is formed on an iron core 3 a that protrudes radially inward from the inner peripheral surface of the yoke 3. The electromagnet 10 is configured by winding the electromagnetic coil 6 via 5. The electromagnets 10 are arranged at equal intervals in the circumferential direction, and the magnets 7 are arranged radially outward from the iron core 3a, and are arranged between the iron cores 3a and 3a as in the embodiment shown in FIG. It is. An annular water chamber 20 having a rectangular cross section is formed in the stationary braking drum 2 disposed inside the yoke 3. That is, the water chamber 20 is provided with an inlet 12 for introducing cooling water and an outlet 13 for discharging the cooling water of the water chamber 20 to the outside, specifically, to a radiator (heat exchanger). The cooled water is configured to return to the inlet 12 again. Also in the embodiment shown in FIG. 3, when the electromagnetic coil 6 is energized, the braking drum 2 is braked based on eddy current when the magnetic field from the rotating iron core 3a crosses the braking drum 2 as in the embodiment shown in FIG. Torque is generated.
[0013]
In the embodiment shown in FIG. 4, an annular plate 2 b formed at one end of a hollow braking drum 2 having a water chamber 20 is fixed to, for example, a wall portion of a vehicle transmission by a plurality of bolts 14. The annular yoke 3 is coupled by a bolt 15 to a flange 16a integrated with the boss portion 16 coupled to the output rotating shaft 4 of the machine. Magnets 7 are embedded in the yoke 3 at equal intervals in the circumferential direction, and iron cores 3 a protruding radially outward from the yoke 3 and disposed at equal intervals in the circumferential direction are opposed to the inner circumferential surface of the brake drum 2. An electromagnetic coil 6 is wound around the iron core 3 a via a winding frame 5 to form an electromagnet 10. Switching between braking and non-braking is achieved by energizing or shutting off the electromagnetic coil 6 as in the embodiment shown in FIG.
[0014]
【The invention's effect】
In the present invention, as described above, one of the annular body made of a conductor and the annular yoke is supported on the rotating shaft, and the other is supported on the non-rotating portion of the vehicle body, and the peripheral edge of the annular yoke is radially outward . A large number of protruding iron cores are provided at equal intervals in the circumferential direction , electromagnetic coils are wound around the iron core to form an electromagnet, and the polarities of the magnetic poles at the tip of the iron core facing the annular body are alternately different in the circumferential direction. The permanent magnet having a radial direction embedded in a circumferential intermediate position of the iron core adjacent to the circumferential direction of the yoke , and the electromagnet adjacent in the circumferential direction, with the permanent magnets having both sides in the circumferential direction forming magnetic poles However, since the same magnetic circuit passing through the annular body is formed at the time of braking, the eddy current reduction device can be configured to be relatively small and light, and no power is required for switching between braking and non-braking.
[0015]
The braking torque can be controlled by adjusting the current applied to the electromagnetic coil.
[0016]
Since the magnet is disposed at a portion radially inward from the iron core of the yoke, it is not easily affected by heat generated in the electromagnetic coil as well as heat generated in the brake drum.
[Brief description of the drawings]
FIG. 1 is a front sectional view at the time of braking of an eddy current reduction device according to the present invention.
FIG. 2 is a front sectional view of the eddy current reduction device when not braking.
FIG. 3 is a side sectional view of an eddy current reduction device according to a second embodiment of the present invention.
FIG. 4 is a side sectional view of an eddy current reduction device according to a third embodiment of the present invention.
[Explanation of symbols]
w: short circuit magnetic circuit z: magnetic circuit 2: braking drum 2a: cooling fin 2b: annular plate 3: yoke 3a: iron core 4: rotating shaft 5: winding frame 6: electromagnetic coil 7: magnet 8: bolt 10: electromagnet 12 : Inlet 13: Outlet 14: Bolt 15: Bolt 16: Boss 16a: Flange 20: Water chamber

Claims (2)

One of the annular body made of a conductor and the annular yoke is supported on the rotating shaft, the other is supported on the non-rotating portion of the vehicle body, and a large number of iron cores projecting radially outward are circumferentially formed on the peripheral edge of the annular yoke. provided at equal intervals, it said core to form an electromagnet by winding an electromagnetic coil, arranged so as different polarities in the circumferential direction alternating pole tip of said core facing the annular body, circumference of the yoke circumferentially intermediate position of the core adjacent to the direction, embedding the radial direction of the permanent magnet, and the permanent magnets both sides in the circumferential direction forms a magnetic pole, and the electromagnet adjacent to the circumferential direction, braking the annular body An eddy current reduction device characterized by forming the same magnetic circuit passing through. The eddy current reduction device according to claim 1, wherein the annular body is one of a braking drum and a braking disk.

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