Electrical generator or motor structure – Dynamoelectric – Linear
Reexamination Certificate
1999-10-08
2001-04-10
Mullins, Burton (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Linear
C310S015000, C310S156030, C310S254100, C310S266000, C310S090000, C417S415000
Reexamination Certificate
active
06215206
ABSTRACT:
BACKGROUND OF THE INVENTION
The present inventions relates to devices known variously as traversing machines, actuators, motors, positioning devices, robots, etc. More particularly, the invention relates to such devices that rotate an operating stage and move it linearly along an axis of rotation.
Various kinds of robotic actuators are known that provide multiple degrees of freedom. There is a need in the field for actuators that provide high accuracy, low weight, large load-carrying capacity, compact size, smooth operation, and cost-effectiveness. One known type of actuator that provides two-degrees of freedom, which scores highly in terms of the above design goals, is an entire class of so-called X-Y traversing systems, for example, as described in U.S. Pat. No. 5,334,892, the entirety of which is incorporated herein by reference. This patent describes a traversing system with a movable stage supported on an air bearing above a planar base. The traversing system described in the patent is, however, limited to movement in a plane.
OBJECTS AND SUMMARY OF THE INVENTION
An object of the present invention is to provide a actuator that provides independent rotational and axial movement of a stage.
Another object of the present invention is to provide an actuator that is simple in design and construction.
Another object of the present invention is to provide an actuator that is compact and light in weight.
Yet another object of the present invention is to provide an actuator that is cost-effective to manufacture and maintain.
Yet another object of the present invention is to provide an actuator capable of supporting large loads.
Briefly, an actuator, with two independent degrees of freedom, rotates a stage about an axis and moves the stage along the axis, the range of motion defining a cylinder or cylindrical section. The stage is mounted on a hollow cylindrical plunger fitting in an annular well. A bearing allows the plunger to move axially and rotationally, in the preferred embodiment the bearing is an air bearing. The plunger has an array of permanent magnets on its external cylindrical face opposite coils in the well. Equal numbers of oppositely-polarized permanent magnets are arranged in a regular cylindrical pattern at 50% packing density forming rings and columns of like-polarity magnets, the rings of one polarity alternating with rings of opposite polarity and the columns of one polarity alternating with columns of opposite polarity. A set of Z-axis coils (for axial movement) curve around the plunger and are shaped to allow a current in them to produce an axial force with respect to the rings of magnets. A set of &phgr;-axis coils (for rotational movement) have longitudinal axes that are parallel to the axis of the plunger and are sized to allow current in them to impel the columns of magnets. Part of the external surface of the plunger has a grid scale, which is encoded by Z-axis and &phgr;-axis optical pickups to provide position information to a controller.
According to an embodiment of the present invention, there is provided, a rotary-linear actuator, comprising: first and second elements, each having a common axis, the first element having at least one magnet, the second element having at least first and second electrical coils capable of generating respective first and second magnetic fields, a bearing to support the first element with respect to the second element to allow the first and second elements to rotate about an axis relative to each other and to slide in a direction collinear with the axis, the first and second coils being positioned relative to each other and relative to the magnet such as to produce a substantial motive force capable of both rotating and displacing the first and second elements with respect to each other when the first and second coils are excited by an electrical current.
According to another embodiment of the present invention, there is provided, a rotary-linear actuator, comprising: a base element having one of a plurality of magnets and a plurality of coils, a stage element having the other of a plurality of magnets and a plurality of coils, the stage element being connected to the base element such that the stage element is free to rotate on an axis and slide along the axis, the plurality of magnets and the plurality of coils being arranged to generate a motive force therebetween when the plurality of coils is energized.
According to still another embodiment of the present invention, there is provided, a rotary-linear actuator, comprising: a base member, a stage member, the base member having a first cylindrical surface, the stage member having a second cylindrical surface, the first and second cylindrical surfaces having a common axis, the base having one of a plurality of magnets and a plurality of electric coils shaped in such a way as to define a first cylinder coaxial with the common axis and the stage having another of the plurality of magnets and the plurality of electric coils shaped in such a way as to define a second cylinder coaxial with the common axis.
According to still another embodiment of the present invention, there is provided, a rotary-linear actuator, comprising: first and second members, each having a common axis, the first member having at least one first means for generating a first magnetic field, the second element having at least second and third means for generating second and third magnetic fields, means for supporting the first member with respect to the second member such that the first and second members are free to rotate about an axis relative to each other and to slide in a direction collinear with the axis, the second and third means for generating being positioned relative to each other and relative to the magnet such as to produce a substantial motive force capable of both rotating and displacing the first and second elements with respect to each other.
According to still another embodiment of the present invention, there is provided, a rotary-linear actuator, comprising: a first member with a cylindrical opening, a second member, cylindrical in shape, sized to fit within the annular cylindrical opening, the first and second members being connected by a bearing means for maintaining concentricity of the first and second members and freedom of relative linear movement of the first and second members along, and relative rotation of the first and second members about, a common axis of the first and second members, the first member having a means for generating a first magnetic field characterized by a first pattern, the second member having a means for generating a second magnetic field characterized by a second pattern, one of the first and second patterns being regular and permanent, the first and second magnetic fields being configured to interact so as to produce a motive force causing the first and second members to move relative to each other, another of the first and second patterns being time-varying, such that the first and second members are impelled to move continuously in rotational and linear modes.
The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements.
REFERENCES:
patent: 3777292 (1973-12-01), Fulenwider
patent: 4234831 (1980-11-01), Kemmer et al.
patent: 4626749 (1986-12-01), Asakawa
patent: 4644205 (1987-02-01), Sudo et al.
patent: 4720650 (1988-01-01), Hanamori et al.
patent: 4808955 (1989-02-01), Godkin et al.
patent: 5081388 (1992-01-01), Chen
patent: 5142172 (1992-08-01), Horikoshi et al.
Amin Himanshu S.
Anorad Corporation
Horn John J.
Mullins Burton
Walbrun William R.
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