Refrigeration – Automatic control – Diverse – cascade or compound refrigeration-producing system
Reexamination Certificate
2005-08-09
2005-08-09
Norman, Marc (Department: 3744)
Refrigeration
Automatic control
Diverse, cascade or compound refrigeration-producing system
C062S193000, C062S196100, C062S228500, C062S510000
Reexamination Certificate
active
06925822
ABSTRACT:
Several control algorithms reduce the likelihood of insufficient oil return to the compressor. One algorithm is useful in a multi-circuit refrigerant system. A control reduces the cooling capacity of one of the circuits if the number of compressor start/stop cycles becomes excessive. By reducing the capacity, the control will reduce the number of compressor start/stop cycles for a circuit. In this manner, the oil continues to circulate through the circuit, and is more efficiently returned to the compressor. Another problem area associated with a poor oil return back to the compressor is when there is low mass flow rate of refrigerant circulating through the system. Various ways of increasing the refrigerant mass flow rate are disclosed to ensure proper oil return to the compressor. Also, if oil return problems are likely due to an undesirably high oil viscosity at the vapor portion of the evaporator or suction line, then steps are taken to reduce oil viscosity. Overall, the present invention discloses three distinct algorithms that may be utilized, either separately or in combination, to ensure better flow of oil back to the compressor. The invention enhances system and compressor reliability and performance as well as prevents the compressor damage.
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Dobmeier Thomas J.
Lifson Alexander
Taras Michael F.
Carlson & Gaskey & Olds
Carrier Corporation
Norman Marc
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