Electricity: magnetically operated switches – magnets – and electr – Magnets and electromagnets – With magneto-mechanical motive device
Reexamination Certificate
2001-03-29
2002-11-05
Donovan, Lincoln (Department: 2832)
Electricity: magnetically operated switches, magnets, and electr
Magnets and electromagnets
With magneto-mechanical motive device
C335S229000
Reexamination Certificate
active
06476702
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an actuator that contains the following components; at least one magnet with a predetermined direction of magnetization, an electrically conductive coil with a longitudinal axis that is oriented in an essentially vertical position with respect to the direction of magnetization of the magnet and which can be operated by an electric current, with the coil being arranged in an offset position near the magnet in the direction of the magnetization of the magnet so that an air gap remains between the coil and the magnet and, viewed in a longitudinal direction of the coil, the magnet protrudes beyond the ends of the coil during a static state of the actuator, a ferromagnetic core of high permeability around which the coil is wound and which, viewed in the longitudinal direction of the coil, ends above and below the coil in collar-shaped projections made of a highly permeable ferromagnetic material.
Actuators of the type mentioned at the outset contain a spring-mass system able to oscillate that is initiated to oscillate when an alternating current is driven through the electrically conductive coil. The actuators are used for very diverse purposes, for instance, as linear motors in pumps, as oscillations generators, or as oscillation eliminators. In the latter case, an actuator of the type mentioned at the outset is connected in its mechanical effect to an oscillating component and oscillations are created in the actuator which are superimposed on the oscillations of the component. By a suitable choice of amplitude, frequency, and phase of the oscillations created by the actuator, the oscillations of the component are reduced or eliminated.
2. Discussion of Background Information
An actuator is known from DE 43 01 845 C1 that is used as the active oscillation eliminator for a machine component moving back and forth. The active oscillation eliminator contains a support plate, mounted to the machine component, on which an electrically conductive insertion coil is positioned stationarily. The insertion coil is concentrically enclosed radially inside and radially outside by a pot magnet. With the aid of spring elements, the pot magnet is connected in a springed manner to the support plate of the active oscillation eliminator and is guided by a guiding device arranged parallel to the axis of the insertion coil. When an alternating current is driven through the electrically conductive insertion coil, the pot magnet begins to oscillate. The oscillations of the pot magnet are superimposed onto the oscillations of the machine component such that a reduction or elimination of these oscillations results.
The active oscillation eliminator known from DE 43 01 845 C1 has a relatively simple design and an extensively linear operational behavior due to a consistent gap width of the air gap that is ensured by the guidance device of the pot magnet. However, it is discernible that the elimination force created by the pot magnet is relatively small in relation to its constructive size since, in the active oscillation eliminator, only relatively small periodic exciter forces can be created and the elimination force is proportional to the amplitude of the exciter force. In the oscillation eliminator, only an electrodynamic force, which develops from the electric current flowing through the insertion coil between the insertion coil and the pot magnet, acts as the exciter force. Since the elimination force created in an oscillation eliminator is also proportional to the size of the oscillating mass, this problem could be solved basically by an enlargement of the pot magnet. However, not all applications of the active oscillation eliminator provide a sufficiently large constructive space. Basically, the problem could also be solved by choosing the natural frequency of the oscillating mass-spring system to be the same as the one to be eliminated since, in this case, the amplitude of the inertial mass results in very high values at an accordingly small dampening. The smaller the dampening, however, the smaller also the bandwidth of the desired resonance superposition so that only in a small range of frequencies can large elimination forces be achieved. In summary, it can be seen that, with the aid of the active oscillation eliminators known from DE 43 01 845 C1 in the given construction volume of the oscillating system (i.e., in a predetermined mass of the pot magnet), only relatively smaller elimination forces can be created. Thus, only relatively small forces can be eliminated.
From the paper “Modeling and Analysis of a new Linear Actuator” by Renato Carlson, Nelson Sadowski, Alberto M. Beckert, Nelson J. Batistela (published at the Industry Application Conference 1995, 30th IAS Meeting IAS' 95, Conference Record of the 1995 IEEE, Oct. 8-12 1995, Orlando, Fla.) a linear actuator of the above-mentioned type is known that is provided with two cuboid permanent magnets with an electrically conductive coil being provided, which is wound onto an iron core in the shape of a double T. The magnetization of the permanent magnets points to the electrically conductive coil that is positioned between the permanent magnets and the upper and lower surfaces of the permanent magnets, viewed in the longitudinal direction of the coil, are covered with iron. The two cuboid permanent magnets are then positioned between two cuboid iron blocks. Furthermore, the permanent magnets and the flux guiding pieces covering them at the upper and lower end, with the aid of coil springs mounted in a springed manner, the other components of the linear actuator, however, being mounted statically. When alternating current is guided through the electrically conductive coil, the permanent magnets mounted in a springed manner are excited into oscillations.
In the linear actuator according to the above-mentioned paper, large exterior exciter forces can be created since, in addition to the electrodynamic forces, magnetic reluctance forces additionally act between the parts of the actuator that are statically positioned and those positioned in a springed manner, with said forces all acting in the same direction and add to a great force summary. Thus, in the linear actuator according to the above-mentioned paper, relatively greater exciter forces can be created with relatively small constructive dimensions. However, it must be stated that the linear actuator known from the above-mentioned paper is provided with complicated design since it contains a multitude of parts that are separated from each other by air gaps.
SUMMARY OF THE INVENTION
The invention is based on developing an actuator having a simple design in which large excited forces can be created.
According to another embodiment, the invention provides for an actuator in which the magnet is embedded in a ferromagnetic jacket of high permeability that covers at least the surface of the magnet facing away from the coil and, viewed in the longitudinal direction of the coil, at least partially the upper and the lower surface of the magnet and in that either the embedded magnet is statically positioned and the coil, including the core, is positioned in a springed manner such that the coil, including the core, is able to perform oscillations in the longitudinal direction of the coil or the coil, including the core, is statically positioned and the embedded magnet is positioned in a springed manner such that it can perform oscillations in the longitudinal direction of the coil.
The components of the actuator that are positioned as being oscillating in a given case are made to oscillate when an alternating current flows through the coil of the actuator.
In addition to the uses mentioned at the outset, the actuator can be used to excite the masses in a motor vehicle positioned in a springed manner to oscillator for the purpose of superimposing these oscillations onto the distributing oscillations in the motor vehicle such that they are eliminated as much as possible. In this case, the force creating the oscillating mass
Hartwig Christoph
Hofmann Maik
Karkosch Hans-Jürgen
Preussler Stefan
Contitech Vibration Control GmbH
Donovan Lincoln
Greenblum & Bernstein P.L.C.
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