Electricity: magnetically operated switches – magnets – and electr – Magnets and electromagnets – With magneto-mechanical motive device
Patent
1987-12-02
1989-08-22
Harris, George
Electricity: magnetically operated switches, magnets, and electr
Magnets and electromagnets
With magneto-mechanical motive device
335234, H01F 708
Patent
active
048599751
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an electromagnetic actuator which is used for specific devices such as electromagnetic valves, electromagnetic pumps, electromagnetic locking devices, electromagnet relays, electromagnetic clutches, and so on which can electromagnetically control a holding operation of a mechanical stable state and a shifting operation from such mechanical stable state.
BACKGROUND TECHNICS OF THE INVENTION
Generally, commonly used electromagnetic valves and the like have contained the electromagnetic actuator as shown in FIG. 10. Such type electromagnetic actuator comprises a stationary core 1 fixed on a yoke 2, movable core 3 movably arranged with respect to the stationary core 1 so as to reciprocally move in the direction represented by the arrow 11, and coil 7 wound around the movable core 3 to generate the first magnetic flux 8 when the coil 7 is energized.
However, this type electromagnetic actuator is relatively poor in its sensitivity and thus can not generate required attractive force at a low current. The inventor of the present invention has already proposed improved electromagnetic actuators which can generate great moving force in spite of low current. This type electromagnetic actuators have been shown in PCT/JP84/00084, PCT/JP85/00313, PCT/JP85/00314, and PCT/JP85/00536.
This type of electromagnetic actuator further comprise a permanent magnet 5 in addition to the conventional device as shown in FIG. 10. In detail, as shown in FIG. 1 to FIG. 4, the permanent magnet 5 is secured to the yoke 2 or the movable core 3 so as to generate the second magnetic flux 9 which dividingly flows in parallel to the first magnetic flux 8 generated by the coil 7.
In the previously invented devices shown in FIG. 1, FIG. 2 and FIGS. 3(a), (b), the movable core 3 is reciprocally moved in the direction represented by the arrow 11 with respect to the stationary core 1.
In the previously invented device shown in FIG. 4(a) and FIG. 4(b), the movable core 3 is secured to a shaft 13a and can be rotatably moved in the direction represented by the arrow 11 with respect to the stationary core 1 through a journal 13b.
However, the above described devices shown in FIG. 1 to FIG. 4, previously proposed by the inventor of the present invention, can not always provide characteristics of a high sensitivity since it depends on the combination of values such as magnetomotive forces caused by the coil 7 and the permanent magnet 5 and magnetic reluctances of the permanent magnet 5 and in the gap between the movable core 3 and the stationary core 1 or the movable core 3 and the yoke 2.
DESCRIPTION OF THE INVENTION
Thererfore, in order to overcome the above mentioned problems, it is an object of the present invention to easily provide an improved electromagnetic actuator which can provide a high sensitivity and a great actuating force with using a low current.
The present invention is based on the following knowledges according to various experiments and theoretical analysis.
First of all, arithmetic operation on the magnetic circuits of conventional devices, previously proposed by the inventor of the present invention, shown in FIG. 5 and FIG. 6 will be conducted.
In these drawings, a stationary core 1 is installed in a yoke 2 with fixing to the inside of the yoke 2. A movable core 3 is so arranged as to be capable of reciprocating in the direction represented by the arrow 11 with respect to the stationary core 1. A first gap d.sub.1 is defined between a pole face 2a of the yoke 2 and a pole face 3a of the movable core 3. A second gap d.sub.2 is also defined between a pole face 1a of the stationary core 1 and a pole face 3b of the movable core 3.
A permanent magnet 5 is fixed on the inner wall of the yoke 2. In detail, its S-pole face is fixed on the inner wall and its N-pole face faces to the movable core 3 through a gap g.
Assuming that the first magnetic flux 8 generated when a coil 7 is energized by the current as shown in the drawings and the second magnetic fluxes 9a and 9b, dividingly flo
REFERENCES:
patent: 4142166 (1979-02-01), Arnoux
patent: 4451808 (1984-05-01), Koehler
patent: 4604599 (1986-08-01), Koehler
Harris George
Iwasaki Electronics Co. Ltd.
Mitsubishi Mining & Cement Co.
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