Electricity: magnetically operated switches – magnets – and electr – Magnets and electromagnets – With magneto-mechanical motive device
Patent
1995-12-04
1997-12-16
Donovan, Lincoln
Electricity: magnetically operated switches, magnets, and electr
Magnets and electromagnets
With magneto-mechanical motive device
335177, 310266, H01F 708
Patent
active
056990316
DESCRIPTION:
BRIEF SUMMARY
The present invention concerns an electromagnetic actuator with rotary core, the rotation of which is controlled directly by the magnetic field.
As known, it is always more widespread in the technique applied to the construction of plants and machines to use actuators, namely devices--electromagnetic, pneumatic, oledionamic--adapted to produce small linear or angular movements of component parts of said plants and machines.
The fundamental characteristic of an actuator is the capability to impart, simultaneously with the motion of a movable element thereof, a thrusting and/or drawing force in the case of the linear type of actuator, or a torque in the case of an angular type of actuator.
The most widespread use of actuators is made of in servomechanisms since there is in fact a great advantage--compared to other operating systems--in being able to produce the motion where it is directly required, without having to derive it with kinematic mechanisms from a central motion source.
Among the known actuators, use is particularly made of the electrically operated ones, usually defined as electromagnetic actuators or, in short, as electromagnets.
Obviously, also in the field of electromagnetic actuators there are two types of movements, linear or angular, adapted to be imparted therewith.
In the case of a linear movement, the movable element of the electromagnet (or movable core) performs a motion along a rectilinear trajectory, under the action of a magnetic field obtained by suitably energizing one or more coils.
In the case of an angular movement, the movable core of the electromagnet performs a rotary motion about its own axis, under the action of a suitable magnetic field.
The technique to produce electromagnets with a linear movement of the movable element has greatly evolved during the past years, and a great number of modifications have been introduced to improve the product so as to be able to obtain more and more advanced performances.
Definitely less evolved is the technique to produce electromagnets wherein the movable core performs a rotary motion about its on axis, or "electromagnets with rotary core". In fact, the examples of construction of electromagnets with rotary core are positively few, since it is usually preferred--as far as can be reckoned from the proposals of the constructors--to resort to electromagnets, wherein the rectilinear movement of the movable core is turned into a rotary motion by mechanical means.
A clear example is represented by the solution proposed by various constructors according to which, even though the coils generate a force along the axis of the electromagnet, which thus tends to move the movable core along this trajectory said core then performs a rotary motion thanks to a torque imparted thereto as a result of its motion.
In fact, in said actuators, a movable cylindrical core carries at one end a disc flange fixed thereto, which faces a circular flat zone of the fixed par of the electromagnet. Between the disc of the movable core and the circular zone of the fixed par there are interposed some balls engaging into grooves which extend into a circle arc, said grooves being formed on the two facing zones in such a way that, when the electromagnet is energized, the magnetic force induced in the movable core in an axial sense generates, at the points of contact with the balls, a component perpendicular to the radius and creates a torque acting on the movable core.
In this way, the movable core performs a rotary motion simultaneously with its axial movement.
As can be easily understood, this is a very rough solution which prejudices the speed of the electromagnet, due to the considerable inertias of the movable core and the significant frictions being produced between the various parts.
Said solution is therefore not adapted to solve the great number of problems arising in present technique, especially when the times of response of the actuators have to be very short and said actuators have to perform a large number of consecutive operations.
The present invention now p
REFERENCES:
patent: 2343325 (1944-03-01), Ranseen
patent: 3201670 (1965-08-01), Myers
patent: 3248499 (1966-04-01), Young
patent: 5337030 (1994-08-01), Mohler
Covelli Marco
Dandolo Enzo
Donovan Lincoln
Nuova Roj Electrotex S.r.l.
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