Bearings – Linear bearing
Reexamination Certificate
1999-08-10
2001-10-30
Hannon, Thomas R. (Department: 3682)
Bearings
Linear bearing
C384S037000, C384S042000
Reexamination Certificate
active
06309106
ABSTRACT:
In one aspect this invention is concerned with motors, and relates in particular to novel varieties of linear motor and the mechanism for driving them. In a second aspect the invention relates to bearings—that is to say, devices for providing relatively frictionless support of one object as it moves relative to the surface of another which supports it or with which it is in contact—which bearings are of use in the motors of the invention. In its second aspect the invention relates in particular to linear bearings, and also optionally combines this function with a selectable force/distance law spring effect.
MOTORS
The term “linear motor” is usually employed to describe a variety of electric motor. In a common type of conventional electric motor a rotating electromagnetic field is produced by a set of stationary coils (known as the stator) arranged to form a circle or cylinder, and this field interacts with a rotatably-mounted magnet or electromagnet (known as the rotor) mounted within the circle or cylinder of the stator, to drive the rotor round. In a linear motor, however, the stator coils are arranged in a line, and the field they produce advances along that line driving the “rotor”—in this case better described as a “translator”—along with it. Such a linear motor can be visualised as a conventional rotary motor the stator of which has been opened out and spread flat.
There are many other devices which produce propulsive force in a straight line rather than in a circle, and thus that might technically be considered as “linear” motors. Thus, steam, gas-driven, internal combustion, hydraulic and pneumatic reciprocating piston/cylinder engines are all non-electrical devices which fall into this category, while other electronic, electrical, electromagnetic devices are voice-coil motors, piezo-electric actuators, and some magnetostrictive devices (these last two have very short translator travel, measured in microns). Some types of linear motor—the so-called “inch-worm” motors—use regions of physico-mechanical compression and expansion in the stator to push the translator along at the speed of propagation of those regions.
There are applications where very high speed, low force, long travel, high linearity and very low moving mass are required, but none of the known linear motors have all of these capabilities. This is a problem the present invention addresses, seeking to provide a linear motor that will enable long-travel high-linearity motion in either a straight or a curved line at very high speed with extremely small translator mass, and yet which is extremely simple in concept and can be manufactured from a very small number of components. To achieve this, the invention proposes the use of a mechanism that applies motive, displacing force not primarily in the direction along which translator movement is desired but instead approximately at right angles to that direction, the construction of the mechanism being such that the consequence is that there is a resultant force—a resolved component of the applied motive force—that is directed along the desired line of movement of the translator, and thus the translator is “squeezed” out in the required direction rather in the way that a cherry pip or plum stone can be shot out by being squeezed between finger and thumb. Another analogy would be trying to pick up a wet (and thus very slippery) curved-outline piece of soap with the palm of a wet hand (the harder the soap is “gripped” the faster it shoots out away approximately at right angles to the direction of grasp). In this latter case the “gripping” hand is nominally stationary (it is the stator) and provides the motive power, whilst the soap plays the part of the moving part or “translator”.
In one aspect, therefore, the invention provides a linear motor comprising a linearly-extensive stator supporting a translator in such a manner that the translator is able easily to move along the line, or axis, of the stator, and wherein:
the stator provides in operation a squeezing force across the translator in a direction approximately orthogonal to the line of the stator; and
either the translator has along its movement direction a profile (either intrinsically or when so squeezed by the stator) that is slightly tapered,
or the translator is mounted on the stator by force-transmitting bearings that when so squeezed by the stator deform to become slightly tapered along the line of the stator,
such that in either case the effect of the squeezing is to produce a resultant force on the translator that is approximately orthogonal to the squeezing force, and thus along the line of the stator.
The linear motor of the invention comprises a linearly-extensive stator supporting a translator. The stator is linear in that it extends in a line rather than being arranged in a circle as in the case in most conventional electric motors. However, the line of the stator need not be straight—though most likely it is—but can be curved in several places and in one or two dimensions.
The stator may be of almost any type, shape and size, applying the squeezing force in any way thought appropriate. Basically, though, the stator is so constructed as to allow deformation of. the bearing aperture within it from a nominally cylindrical internal outline to a nominally truncated conical form, it being possible to reverse which end of the aperture has the smaller internal diameter. This may be achieved in a multiplicity of ways, including:
using a piezoelectric material for the stator, applying suitable electrode patterns, and driving those electrodes from an electrical supply;
making the stator from magnetostrictive material, and applying appropriate magnetic fields, for example by the provision of currents through suitably positioned adjacent conductors;
constructing the stator as a hollow shell-form object made of elastic material, this stator being divided into two (or more) internal chambers by one or more partitions, wherein the separate chambers so formed are driven with differing hydraulic or pneumatic fluid pressure supplies;
making the stator from a material with an appreciable thermal coefficient of expansion (at least in the circumferential direction around the bearing aperture), and driving it thermally (e.g. by hot fluids, by electrical resistance heating, or by direct conduction from one or more heat sources) so that one end of the aperture expands more than the other (such an arrangement might, for example, be used to control a thermostatic control valve, where the thermal sources included one or more of the hot fluid supply, the cold fluid supply and the exit fluid);
making a variant of the just-mentioned thermally-activated stator wherein a shape-memory alloy is used to produce the differential aperture diameter by application of thermal control sources;
building the stator to incorporate a bio-structure material capable of contraction or expansion (e.g. muscle tissue) so arranged around the interior of the aperture, and so stimulated by external control signals, that the desired conical deformations ensue.
However, the variety of stator presently thought most convenient and useful is that made of a piezoelectric material driven by suitably-applied electrical voltages.
In the invention's linear motor the stator supports a translator. In this context a “translator” is simply a component that can be driven along the stator by the applied force so as to perform some desired operation. Examples of stators, as defined by what they are required to do, include:
a rod coupled to an external mechanism to provide useful mechanical movement therein;
a light self-contained radially-stiff piston effectively sealed against fluid flow within the stator (perhaps by the bearing structure) which acts directly on the air surrounding it, to act as an acoustic transducer;
a self-contained radially stiff piston effectively sealed against fluid flow within the stator (perhaps by the bearing structure) fluid-coupled to one or more external chambers so as to act as a pump in conjunction with fluid flow control valves
1... Limited
Hannon Thomas R.
Synnestvedt & Lechner LLP
LandOfFree
Motors, and bearings therefor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Motors, and bearings therefor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Motors, and bearings therefor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2560573