Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1994-12-28
1998-02-03
Dougherty, Thomas M.
Electrical generator or motor structure
Dynamoelectric
Rotary
310 66, 310 71, 385 53, 25023113, 417902, H02K 2910, G01D 526, G02B 624
Patent
active
057148112
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention is related to a rotor position detecting apparatus for a brushless motor, and particularly to a rotor position detecting apparatus for a compressor which is embodied by a brushless motor.
BACKGROUND ART
In a refrigerator, an air conditioner or similar appliance, a compressor, which is used for changing the state of a fluid, for example refrigerant, is generally embodied by an A.C. induction motor. Furthermore, the compressor used in the appliance is tightly closed within a housing defined by parts welded together in order to prevent a decrease in the pressure therein. Within the housing, the motor is connected to a piston (in a reciprocating compressor). A connector, which is mounted in the body of the housing, has several terminals electrically connected to each of the phase windings of the motor. When the phase voltages are applied to the terminals, the axle of the motor starts to rotate, thereby causing the piston connected to the axle to reciprocate within a cylinder. In the manner described above, refrigerant is drawn into the cylinder and is then compressed. The closed compressor is required to normally operate under the temperature condition of a maximum 130.degree. C. and several tens of Psi, and to endure oil and refrigerant.
Compared with an A.C. motor, a brushless motor has a low noise level and low power consumption, and may be operated at a continuously varying rotating rate. Considering the advantages, a closed compressor embodied by a brushless motor has been continuously developed. The brushless motor is activated by D.C. currents, out of phase from each other, flowing into each of the phase windings. Accordingly, a means for detecting the polarity of the rotor is essential to the brushless motor. A pair of light emitting and receiving elements are typically used for detecting the polarity of the rotor.
However, there is a problem in that it is impossible to place the light receiving and emitting elements in the housing of the closed compressor, which operates under high temperature and high pressure, because the elements are normally made of semiconducting material. Furthermore, there is another problem in that the compressor seal is easily damaged because the signal wires of the elements extend through the housing. Considering these problems, there has been developed a system using a winding induced voltage, instead of detecting by the elements. However, the system has a problem in that a means for detecting the winding induced voltage, a filter means and a means for starting the compressor are additionally required, and also it is not applicable to the brushless motor.
DISCLOSURE OF INVENTION
It is an object of the present invention to provide a rotor position detecting apparatus required for driving a brushless motor.
It is another object of the present invention to provide a rotor position detecting apparatus using a photoelectric conversion system to increase the detection ability in a brushless motor.
It is another object of the present invention to provide a rotor position detecting apparatus constructed with a simple configuration without damaging the seal of the closed compressor embodied by a brushless motor.
According to the present invention, there is provided a rotor position detecting apparatus for a brushless motor enclosed in a housing. The apparatus comprises a plurality of light reflecting members located symmetrically around the axis of the rotor; a plurality of light non-reflecting members located symmetrically around the axis of the rotor alternating with the light reflecting members; a pair of optical fibers for transmitting and receiving light signals, one end of the pair of the optical fibers positioned to face the surface of the rotor; a pair of light emitting and photoelectric converting elements respectively positioned to face the other end of the pair of transmitting and receiving optical fibers; and, a connector mounted to the body of the housing, the connector comprising a plurality of terminals connected to the pha
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Dougherty Thomas M.
Mullins B.
Samsung Electronics Co,. Ltd.
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