Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1992-07-06
1994-10-11
Stephan, Steven L.
Electrical generator or motor structure
Dynamoelectric
Rotary
310 68R, 310156, 310254, 29597, H01F 708, H02K 2112
Patent
active
053553730
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present application is related to electric motors, a controller therefor and methods for controlling and assembling the same and, in particular, to miniature electric motors and a controller therefor and methods for controlling and assembling the same.
Background Art
Miniature electric motors that can be rotated between fixed angles and held stationary at those fixed angles for a specified period of time are finding a wide variety of applications such as for driving needle indicators in meters, gauges and the like. For such motors to find wide application they must have high performance, be relatively low cost, and have a compact construction.
In the control of such motors it is desirable to maintain the position of a rotor of the motor at a specified location for a specified period of time. A stepper motor uses electromagnetic detents to maintain a rotor at a desired location. Electrical energy is added to cause the rotor to move past a magnetic hill. When the motor is deenergized, the rotor will settle and be maintained within a magnetic valley. A stepper motor is therefore designed with these magnetic valleys located at the desired stopping positions. Thus, one drawback of stepper motors is the requirement of a large number of detents in order to allow the stepper motor to be held at a large number of positions.
Another drawback of stepper motors is that as the motor settles in a magnetic valley, the motor shaft may vibrate before coming to rest at the desired location. This vibration could cause damage or excess wear to the motor or to a payload.
A micro-stepper motor offers an improvement over the stepper motor in that it allows a shaft to be held at an indefinite number of positions. The micro-stepper motor operates by applying electrically orthogonal signals to spatially orthogonal poles of a motor. By changing the ratio of magnitude of the signals applied, the motor can be moved to and held at any desired location. In order to hold the rotor at a desired location, however, electrical energy must be applied constantly. As a result, the performance of micro-stepper motors has been limited by the requirement of a corresponding increase in applied electrical energy for greater restraining torques.
These problems have been addressed by U.S. Pat. No. 4,890,027, to Bohner et al., which discloses a dynamic motor controller for a low cost motor. The position control of the motor is accomplished by the use of an electronic braking apparatus, which includes a piezoelectric transducer for applying a braking force to the rotor.
One attempt to surface mount a coil gauge mechanism is disclosed in Disclosure Number 30650, contained in Research Disclosure, October 1989. The gauge mechanism consists of surface mount coils and a permanent magnet spindle assembly. Attached to the spindle can be a dial pointer or other indicating device. The coils have a high permeability core and are wound with insulated copper wire for the coil. The rotational position of the spindle assembly permanent magnet is controlled by the amount and direction of electrical current in the surface mount coils. The mechanism is held in place by a bottom self-lubricating bearing and an upper bearing bracket. The upper bearing bracket also serves as a flux-containing package.
Summary of the Invention
It is an object of the present invention to provide a low cost, light-weight, compact motor which is relatively easy to control.
It is also an object of the present invention to provide a motor-controller combination which is low cost, efficient, compact and stable.
It is yet still another object of the present invention to provide a motor which can be surface-mounted on a substrate to provide a combination which is relatively easy to assemble using conventional automated equipment.
A further object of the present invention is to provide methods for controlling and assembling such electric motors.
In carrying out the above objects and other objects and features of the present invention, an electric motor for driving a load i
REFERENCES:
patent: 3110830 (1962-04-01), Smith
patent: 3350709 (1967-10-01), Pursiano et al.
patent: 4137491 (1979-01-01), Bartley et al.
patent: 4358694 (1982-11-01), Grundland
patent: 4682065 (1987-07-01), English et al.
patent: 4686400 (1987-08-01), Fujisaki et al.
patent: 4890027 (1989-12-01), Bohner et al.
patent: 4955791 (1990-09-01), Wrobel
patent: 5157293 (1992-10-01), Escaravage
Research Disclosure Oct. 1989, 30650 Surface Mount Coil Gage Mechanism, p. 732.
Ehle David L.
Hovis Jeffrey G.
Salmon Michael E.
Haszko D. R.
Nu-Tech and Engineering, Inc.
Stephan Steven L.
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