Electricity: magnetically operated switches – magnets – and electr – Magnets and electromagnets – With magneto-mechanical motive device
Patent
1986-04-23
1988-05-24
Harris, George
Electricity: magnetically operated switches, magnets, and electr
Magnets and electromagnets
With magneto-mechanical motive device
335234, H01F 708
Patent
active
047468866
DESCRIPTION:
BRIEF SUMMARY
Technical Field
The present invention generally relates to an electromagnetic actuator which electrically controlls mechanical force for electromagnetic devices such as electro-magnetic relay, electromagnetic switch, electromagnetic valve, electromagnetic locking means, electromagnetic brake, electromagnetic clutch, electromagnetic vibrator, or the like.
PRIOR ARTS
In various field of industrial art, public use and so on, conventionally used electromagnetic actuators are generally composed of a combination of electromagnetic attraction of an electromagnet and spring bias force. For a specific use, it is well known that an electromagnetic actuator with self-supporting ability (latching property) is composed of an electromagnet, a spring, and a permanent magnet as a self-latching means.
Referring to FIGS. 9(a),(b), there is shown a constitution of most commonly used plunger type electromagnetic actuator in the prior art. That is, in the drawing, this plunger type electromagnetic actuator comprises a stationary element consisting of a stationary iron core 1 and a winding element 4 wound round the core 1, a plunger shape movable iron core 2 capable of reciprocating with respect to the iron core 1, and a spring 3 generating a bias force so as to maintain a gap 1a between the stationary iron core 1 and the movable iron core 2 while the winding element 4 is free from an electric current.
FIG. 9(a) shows this OFF-state of this plunger type electromagnetic actuator; that is, the plunger shape movable iron core 2 is present to the iron core 1 under mechanical stable condition on account of the function of the spring 3 which applys the bias force in the direction shown by an arrow 3a to the movable core 2.
When an electric current is flowed through the winding element 4 as shown in FIG. 9(b), a magnetic flux 27 is generated so that a magnetic attractive force will be also caused in the reverse direction of the bias force 3a and the magnetic attractive force is greater than the bias force. Accordingly, the plunger shape movable iron core 2 is forcedly moved towards the stationary iron core 1 and contacted thereto as shown in FIG. 9(b). In this way, an actuating member connected to the movable iron core 2 such as an electric contact piece, a valve rod or like ( not shown ) can be mechanically actuated.
This mechanical actuated state is maintained during the ON-state of the winding element 4. On the other hand, the movable iron core 2 will be returned to the mechanical stable state as shown FIG. 9(a) due to the bias force of the spring 3 if the winding element 4 is switched from the ON-state to the OFF-state.
Referring to FIGS. 10(a)(b), there is shown another conventional electromagnetic actuator which is additionally provided with a permanent magnet for latching. That is, this latching type electromagnetic actuator is so constituted that the magnetomotive force of the permanent magnet 5 is applied in series to the magnetomotive force of the magnetic circuit consisting of the stationary iron core 1, the movable iron core 2 and the gap 1a as shown in FIGS. 9(a),(b).
When the winding element 4 is present in the OFF-state; i.e., an electric current is not flowed therethrough, the magnetic flux 26 caused by the magnetic force of the permanent magnet 5 applys the attractive force to the movable iron core 2 which is always subjected to the bias force in the direction of arrow 3a by means of the spring 3. Since this attractive force by the permanent magnet 5 exists in equilibrium with the bias force of the spring 3, the movabble iron core 2 is isolated from the stationary iron core 1 with a gap 1a therebetween. This state is referred as "first mechanical stable state".
Nextly, when an electric current in a series of pulses is flowed through the winding element 4 in the direction as shown in FIG. 10(a), the magnetic flux 27 is generated and overlapped with the magnetic flux 26 caused by the permanent magnet 5 so that the magnetic attractive force greater than the bias force ( arrow 3a ) of the spring 3 is generated. Thus t
REFERENCES:
patent: 3783423 (1974-01-01), Mater et al.
patent: 4157520 (1979-06-01), Moates et al.
patent: 4419643 (1983-12-01), Ojima et al.
Harris George
Iwasaki Electronics Co. Ltd.
Mitsubishi Mining & Cement Co. Ltd.
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