Pumps – Condition responsive control of pump drive motor – Responsive to pump lubricant – sealant – or coolant condition
Reexamination Certificate
2000-02-24
2001-08-28
Koczo, Michael (Department: 3746)
Pumps
Condition responsive control of pump drive motor
Responsive to pump lubricant, sealant, or coolant condition
Reexamination Certificate
active
06280146
ABSTRACT:
BACKGROUND OF THE INVENTION
This application relates to a sealed compressor wherein hot oil is moved into contact with a protector switch to shut down the compressor motor in the event that adverse conditions are occurring in the compressor.
Sealed compressors are utilized in most refrigerant compression applications. In a typical sealed compressor, an electric motor drives a compressor pump unit to compress a refrigerant. The refrigerant passes from the compressor pump unit to downstream locations in a refrigeration cycle. There are challenges with operation of sealed compressors. In some cases, there may be a loss of refrigerant within the system. This so-called loss of charge operation can have detrimental effects on the compressor pump unit. When there is an unusually low amount of refrigerant being compressed, the compressor pump components may become hot. This is undesirable.
One popular type of modern compressor pump unit is a scroll compressor pump unit. In a scroll compressor pump unit, a first scroll member has a base and a generally spiral wrap extending from the base. A second scroll member has a base and a generally spiral wrap extending from its base. The wraps of the two scroll members interfit to define compression chambers. The second scroll member is caused to orbit relative to the first, and as the two orbit, compression chambers between the two wraps decrease in volume to compress an entrapped refrigerant.
Scroll compressors are often powered by a three phase electric motor. Three phase electric motors receive three power connections to drive the motor. Occasionally, when the motor is being connected to its power supply, the phase of the three connections are improperly aligned. When this occurs, the motor may be driven in a reverse direction than that which is expected. When a scroll compressor is driven to rotate in the reverse direction, then the refrigerant which Has typically been moved from a radially outer area towards a central area moves in the opposed direction. This is undesirable, and causes the generation of a good deal of heat within the compressor pump unit.
Various methods for identifying reverse rotation and loss of charge situations in sealed compressors have been proposed. However, it would be desirable to provide a simple and yet sure method for identifying such adverse conditions, and stopping operation of a motor when such adverse conditions are identified.
SUMMARY OF THE INVENTION
In a disclosed embodiment of this invention, a protector switch for controlling a motor associated with a sealed compressor stops operation of the motor should a predetermined temperature be exceeded. The present invention places a flow of lubricating oil such that it will contact the protector switch, at least when certain adverse conditions are encountered in the compressor. Typically, known sealed compressors have a protector switch at the top of the motor stator windings. Known protector switches actuate when a particular temperature is experienced and stop operation of the motor.
However, the protector switches are mounted on the motor, and are thus not always sensitive to increased temperature in the pump unit. In one disclosed embodiment of this invention, a heat sensitive valve opens when a particular temperature is achieved in the compressor pump unit. When opened, this valve allows flow of oil from the compressor pump unit to a path directed to flow onto the protector switch. The valve is preferably a bi-metal temperature sensitive valve. When the compressor pump unit reaches an unusually high temperature due to some adverse condition such as loss of charge or reverse running, the valve opens. Hot oil from the compressor pump unit is then directed into contact with the protector switch. This will cause the protector switch to be actuated, stopping operation of the motor.
In a second embodiment, the protector switch is positioned at a lower end of the windings such that it is in contact with the oil sump. During adverse operation of the compressor, the temperature of the oil in the sump will increase. The protector switch will then stop operation of the motor when this increasing oil temperature reaches a predetermined limit.
The present invention thus provides a simple and sure way of identifying adverse conditions during operation of a sealed compressor. These and other features of the present invention can be best understood from the following specification and drawings.
REFERENCES:
patent: 3010401 (1961-11-01), Granqvist
patent: 3232519 (1966-02-01), Long
patent: 4361417 (1982-11-01), Suzuki
patent: 6017205 (2000-01-01), Weatherston et al.
Barito Thomas
Bush James W.
Hahn Greg
Hill Joe T.
Hugenroth Jason
Carlson & Gaskey & Olds
Koczo Michael
Scroll Technologies
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