Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
1999-09-17
2001-03-06
Ramirez, Nestor (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S096000, C310S099000, C310S268000
Reexamination Certificate
active
06198182
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to motors and/or actuators. In particular, there is a two-phase electro-mechanical stepper motor having 1) a high ratio of torque per mass and torque per power draw, to be able to develop required rotating torque, 2) a magnetic circuit that allows developing of a significant holding torque while using a limited amount of electric power, and 3) two disk stators with salient poles are positioned on either side of two disk rotors and 4) a gear train positioned between the rotors.
2. Description of the Related Art
Various devices dealing with stepper motors are legion. Examples of patents related to the present invention are as follows, and each patent is herein incorporated by reference for the supporting teachings:
U.S. Pat. No. 5,512,871 is a rotatable single phase electromagnetic actuator.
U.S. Pat. No. 5,334,893 is a monophase electromagnetic rotary actuator of travel between 60 and 120 degrees.
U.S. Pat. No. 5,298,825 is a single phase electromagnetic actuator with low obstruction.
U.S. Pat. No. 5,054,940 is a ceramic bearing design for attachment to a shaft.
U.S. Pat. No. 4,973,866 is a variable angle stepper motor.
U.S. Pat. No. 4,645,430 is a wet motor fuel pump with self aligning bearing.
U.S. Pat. No. 3,749,458 is a centering device for a rotary shaft.
WIPO PCT patent publication 99/13558 is a brushless DC motor.
The foregoing patents reflect the state of the art of which the applicant is aware and are tendered with the view toward discharging applicants' acknowledged duty of candor in disclosing information that may be pertinent in the examination of this application. It is respectfully stipulated, however, that none of these patents teach or render obvious, singly or when considered in combination, applicant's claimed invention.
Referring to
FIG. 1
, there is a cross section of a typical related art rotatable single phase electromagnetic actuator
10
. Actuator
10
has a shaft
12
with an axis
13
, a stator
14
, a rotor
16
, and a bearing structure
25
. The stator has a magnetic field inducing wire coil
18
, a stator pole shoe
20
, and a bearing support
24
. Bearing assembly
25
includes a top and bottom bearing retaining housing
26
, and a plurality of ball bearings
28
. The rotor
16
includes a set of rotor magnets
22
. Other supporting structures such as a housing and other bearings have been omitted for clarity. It is noted that the actuator illustrates an ideal design, where the bearing parts, stator parts and rotor parts have all respective surfaces appropriately aligned either perpendicular or parallel.
3. Problem with the Related Art
A common problem occurring with multi-position valves is that they require a driving actuator that both 1) develops a significant rotating torque to move from one angular position to another, and 2) can be locked in one of the angular positions, usually by a holding torque. Both competing needs must be met without using large amounts of electric power.
Some specific applications may require more torque than the actuator can provide. A solution to this problem is to add a gear train to an end of the actuator. However, in some applications space constraints may preclude this.
Therefore, there is a need for a stepper motor that both steps to various positions and holds at those positions with low power usage. Additionally, there is a need for a motor that has a poly-phase electric power supply to enable a switch to turn on or off the power to parts of its winding and, for example, reverse the direction of rotation, and there is a need for a motor with an integrated gear train for applications with even higher torque requirements.
SUMMARY OF THE INVENTION
It is a feature of the invention to provide a two-phase electro-mechanical stepper motor having 1) a high ratio of torque per mass and torque per power draw, to be able to develop required rotating torque, 2) a magnetic circuit that allows developing of a significant holding torque while using a limited amount of electric power, and 3) two disk stators with salient poles are positioned on either side of two disk rotors and 4) a gear train positioned between the rotors. Additionally; the motor uses a two-phase electric power supply to enable switching on or off the power to parts of its winding and, for example, reverse the direction of rotation.
An additional feature of the invention is to provide a rotary actuator that includes a shaft. A first and second rotor are rotationally fixed on the shaft. A first and second permanent magnet are fixedly mounted on an outer surface of each of the rotors. The first and second magnets each have a plurality of north and south pole magnet regions that are oriented such that the first magnet's north and south pole magnet regions are misaligned with respect to the second magnet's north and south pole magnet regions. A first and second stator are mounted around the shaft and positioned adjacent to the first and second permanent magnets and have a disc shaped yoke and several first poles and second poles extending away from the yoke, parallel to the shaft, and toward the first and second rotors. Several first and second independent wire coils are wrapped around the first and second poles to allow the formation of several first and second electromagnets by passing electrical current through the first and second wire coils in such a way that the electromagnets in each stator have alternating polarities of N, S, N, S.
A further feature of the invention is to provide a gear train that is positioned between the first and second rotors. The gear train includes a first gear that is attached to the shaft, a second gear engaged with the first gear and an output shaft that passes through and is attached to the second gear.
The invention resides not in any one of these features per se, but rather in the particular combination of all of them herein disclosed and claimed. Those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. Further, the abstract is neither intended to define the invention of the application, which is measured by the claims, neither is it intended to be limiting as to the scope of the invention in any way.
REFERENCES:
patent: 3749458 (1973-07-01), Thylefors
patent: 3784850 (1974-01-01), Inaba et al.
patent: 4006375 (1977-02-01), Lyman, Jr. et al.
patent: 4082971 (1978-04-01), Miyake et al.
patent: 4645430 (1987-02-01), Carleton
patent: 4823040 (1989-04-01), Oudet
patent: 4973866 (1990-11-01), Wang
patent: 5053661 (1991-10-01), Kitamura et al.
patent: 5054940 (1991-10-01), Momose
patent: 5184040 (1993-02-01), Lim
patent: 5298825 (1994-03-01), Oudet
patent: 5334893 (1994-08-01), Oudet
patent: 5512871 (1996-04-01), Oudet
patent: 5637937 (1997-06-01), Nakajima
patent: 5814914 (1998-09-01), Caamano
patent: 5982058 (1999-11-01), Bustamante et al.
patent: 6037696 (2000-03-01), Sromin et al.
patent: WO 99/13558 (1999-03-01), None
Adams Phillip G.
Bustamante Eleazar Felipe
Hoskin Catherine
Leng David Yan
Roubinchtein Grigori
Borgman Mark
Bourgeois Mark
CTS Corporation
Nguyen Tran N
Ramirez Nestor
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