Drive mechanism
AssigneeNational Research Development Corporation
InventorsIan C. A. Leonard, Barry E. Jones
Life of this patent
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Abstract
A drive mechanism for driving one or a plurality of displaceable elements around a closed path, such as a circle, constituted by a linear induction actuator associated with means for constraining the displaceable elements to move in the closed path. A capacitive feedback control system determines the position of the element or elements around the path and controls the windings of the linear induction actuator in dependence on an error signal generated therefrom. An open path drive mechanism having a plurality of linear induction actuators and a capacitive feedback control system is also encompassed by the invention as are hybrid linear induction motors using sets of arcuate linear induction actuators around the rim of a reaction member which drives an output shaft of the motor.
Claims15
A drive mechanism for driving at least one displaceable element along a predetermined path comprising:
- a linear induction actuator having a plurality of individual electrical windings extending closely adjacent said path;
- means for constraining said at least one displaceable element to move along said predetermined path, a reaction member on said at least one displaceable element on which, when said windings are appropriately energized, is exerted a force driving said at least one displaceable element along said predetermined path;
- a plurality of position sensitive transducers spaced along said predetermined path, each said position sensitive transducer incorporating fixed transducer members spaced from one of a non-magnetic metal part of said linear induction actuator and a non-magnetic metal plate carried by said linear induction actuator, at a position on the far side of the path of said reaction member of said at least one displaceable element therefrom;
- means for feeding an electrical signal to said fixed transducer members;
- and
- means sensitive to the reactance between said fixed transducer members and one of said non-magnetic metal parts of said linear induction actuator and said non-magnetic metal plate carried by said linear induction actuator operating to provide a signal representing the position of said at least one displaceable element.
A drive mechanism for driving at least one displaceable element to move around a closed path, comprising:
- a linear induction actuator extending adjacent said closed path and substantially entirely around it;
- a reaction member for cooperation with said linear induction actuator on said at least one displaceable element, whereby, when said linear induction actuator is appropriately energized, said at least one displaceable element is driven around said closed path;
- at least one fixed transducer member associated with said linear induction actuator;
- means for feeding an electrical signal to said at least one fixed transducer member;
- means for sensing the reactance between said at least one fixed transducer member and said reaction member of said at least one displaceable element which reactance sensing means provides an electrical signal which represents the actual position of said at least one displaceable element with respect to said linear induction actuator;
- means for producing at least one demand signal representing the desired position of said at least one displaceable element;
- and
- means for comparing said demand and said actual position signals to produce at least one error signal for controlling the position of said at least one displaceable element over at least a part of said path.
A drive mechanism for driving at least one displaceable element to move around a closed path, comprising:
- a linear induction actuator extending adjacent said closed path and substantially entirely around it;
- a reaction member for cooperation with said linear induction actuator on said at least one displaceable element, whereby when said linear induction actuator is appropriately energized, said at least one displaceable element is driven around said closed path;
- at least one fixed transducer member associated with said linear induction actuator;
- means sensitive to the capacitance between said fixed transducer member and a non-magnetic metal part of said linear induction actuator, said at least one displaceable element being positioned in such a way that said reaction member thereof passes between said fixed transducer member and said metal part of said linear induction actuator, in operation of the mechanism, whereby to vary the electrical capacitance between them and to produce an electrical signal in dependence on said capacitance, which signal represents the actual position or positions of said displaceable element around said path;
- means for providing at least one demand signal representing the desired position of said at least one displaceable element;
- and
- means for comparing said demand signal with said position signal from said means sensitive to said capacitance between said at least one fixed transducer member and said non-magnetic metal part of said linear induction actuator whereby to produce at least one error signal for controlling the position of said at least one displaceable element over at least a part of said path.
Dependencies are inferred from the claim text.