Electrical generator or motor structure – Dynamoelectric – Reciprocating
Reexamination Certificate
2000-03-29
2001-10-09
Ramirez, Nestor (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Reciprocating
C310S012060, C310S328000
Reexamination Certificate
active
06300692
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a linear actuator with an expansion device which includes first and second threaded collars which alternately support, a load depending upon the expansive condition of the expansion device, thereby enabling advancement of the load along a threaded support.
BACKGROUND OF THE INVENTION
Prior art devices designed to provide linear actuation using the expansion of material as a primary actuator are considerably complicated, expensive, and lack robustness.
One such linear actuator is described in U.S. Pat. No. 5,705,863, which teaches a linear actuator having a magnetostrictive rod which is magnetically energized under analog logic control in operative relation to a pair of electrically disengaged one-way locking devices, one of which is interconnected with the actuator through a stroke multiplier to provide a high force, high speed motor drive. Two-stage operation of the stroke multiplier is effected through levers angularly displaced by angular deformation of the magnetostrictive rod about a pivotal axis offset from the rod axis by means of a flexible support for such levers to avoid wear and backlash. This structure results in a complicated, expensive device.
Accordingly, it is desirable to provide a simple, inexpensive and robust linear actuator.
DISCLOSURE OF THE INVENTION
The present invention overcomes the above-referenced shortcomings of prior art linear actuators by providing a simple, inexpensive and robust linear actuator which takes advantage of new materials which can exert high forces, while having limited displacement, such as piezoelectrics, magnetorheologicals, and magnetostrictives, such as Terfenol. The device employs first and second collars threadedly engaged on a threaded support for alternately supporting a load depending upon the expansive condition of an expansion device. The first collar is rotatably driven by a drive motor.
More specifically, the present invention provides a linear actuator including a threaded support and first and second collars threadedly engaged with the threaded support. First and second plates are abuttable against the first and second collars, respectively, and the first and second plates have a clearance fit with the respective first and second collars. An expansion device engages the first and second plates. A motor operatively engages the first collar for rotating the first collar. The first and second collars and expansion device are configured such that a load applied to the second plate is alternately supported by one of the first and second collars, depending upon the expansive condition of the expansion device, as the other of the first and second collars is rotated along the threaded support, thereby enabling the second plate to advance along the support against the load by expansion of the expansion device.
Another aspect of the invention provides a method of linear actuation including the steps of: a) providing first and second collars threadedly engaged with a threaded support and including first and second plates abuttable against the first and second collars, respectively; b) rigidly supporting a load applied against the second plate on the second collar via its threaded engagement with the threaded support; c) rotatably advancing the first collar toward the first plate to contact and rigidly support the first plate; d) expanding an expansion device between the first and second plates to advance the second plate against the load while the first plate is rigidly supported by the first collar and its threaded engagement with the threaded support; e) rotatably advancing the second collar toward the advanced second plate to contact and rigidly support the second plate, thereby rigidly supporting the load; and f) contracting the expansion device and repeating steps (c)-(e) to advance the load along the threaded support.
Accordingly, an object of the present invention is to provide an improved linear actuator which employs an expansion device between first and second movable collars in a manner which is simple, inexpensive and robust.
The above object and other objects, features, and advantages of the present invention are readily apparent from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings.
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Brown Gregory P.
Ford Global Technologies Inc.
Perez Guillermo
Ramirez Nestor
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