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US 8,734,125 B2Granted
Crankcase heater systems and methods for variable speed compressors
AssigneeEmerson Climate Technologies, Inc.
InventorsDaniel L. McSweeney, Charles E. Green, Stephen M. Seibel
Life of this patent
Estimating the term…
Abstract
A system includes a compressor having a shell housing a compression mechanism driven by an electric motor in an on state and not driven by the electric motor in an off state. The system also includes a variable frequency drive that drives the electric motor in the on state by varying a frequency of a voltage delivered to the electric motor and that supplies electric current to a stator of the electric motor in the off state to heat the compressor.
Claims16
A system comprising:
- a compressor including a shell housing a compression mechanism driven by an electric motor in an on state and not driven by the electric motor in an off state;
- a variable frequency drive that drives the electric motor in the on state by varying a frequency of a voltage delivered to the electric motor and that supplies electric current to a stator of the electric motor in the off state to heat the compressor;
- a control module connected to the variable frequency drive that controls a speed of the electric motor in the on state and that controls the electric current supplied to the stator of the electric motor in the off state;
- a compressor temperature sensor that generates a compressor temperature signal corresponding to a compressor temperature;
- wherein the stator heats the compressor for a first time period and the control module receives the compressor temperature signal, determines a rate of change of the compressor temperature over a second time period, after the first time period, and calculates an amount of current to supply to the stator based on the rate of change.
2 more elements
A method comprising:
- driving a compression mechanism of a compressor with an electric motor by driving the electric motor with a variable frequency drive that varies a frequency of a voltage delivered to the electric motor in an on state, and not driving the compression mechanism with the electric motor in an off state;
- heating the compressor by supplying electric current to a stator of the electric motor with the variable frequency drive to heat the stator of the electric motor in the off state;
- controlling a speed of the electric motor in the on state with a control module connected to the variable frequency drive;
- controlling, with the control module, the electric current supplied to the stator of the electric motor in the off state;
- generating a compressor temperature signal corresponding to a compressor temperature with a compressor temperature sensor;
- heating the compressor with the stator for a first time period;
- receiving the compressor temperature signal with the control module;
- determining, with the control module, a rate of change of the compressor temperature over a second time period, after the first time period;
- calculating, with the control module, an amount of current to supply to the stator of the electric motor based on the rate of change.
6 more elements
Dependencies are inferred from the claim text.