Methods of operating a refrigeration system
First Claim
1. A method of interlocking the selection and operation of an internal combustion engine and an electric drive motor which are arranged to selectively and alternatively function as a prime mover for a refrigerant compressor in a refrigeration system, to prevent energization of the electric motor while the engine is operative, comprising the steps of:
- monitoring engine oil pressure,detecting the selection of the drive motor as the prime mover,determining if the engine oil pressure is zero in response to said detecting step finding selection of the drive motor as the prime mover,preventing energization of the drive motor, when de-energized, and de-energizing the drive motor, when energized, in response to the determining step finding the engine oil pressure is not zero,initiating a predetermined timing period in response to the determining step finding the engine oil pressure is not zero,repeating periodically the step of determining if the engine oil pressure is zero,and providing an indication of a fault when the repeated determining step consistently finds the engine oil pressure is not zero over the predetermined timing period.
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Accused Products
Abstract
Methods of monitoring the operation of a refrigeration system, including interlocking the selection and operation of an engine and electric motor which are arranged to alternatively function as prime movers for a refrigerant compressor; detecting slippage of a clutch connected between the engine and compressor; and, detecting improper rotational direction of an evaporator fan motor. The interlocking method prevents energization of the drive motor while the engine is operative, and it includes monitoring engine oil pressure and engine RPM. The clutch slippage method includes detecting engine speed fluctuations and the polarity of battery current. The monitoring of the evaporator fan motor, which drives a fan which draws return air RA from a conditioned space, and discharges conditioned air DA into the conditioned space, includes the steps of comparing the difference between the temperatures RA and DA of the return air and discharge air with a predetermined reference value.
53 Citations
32 Claims
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1. A method of interlocking the selection and operation of an internal combustion engine and an electric drive motor which are arranged to selectively and alternatively function as a prime mover for a refrigerant compressor in a refrigeration system, to prevent energization of the electric motor while the engine is operative, comprising the steps of:
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monitoring engine oil pressure, detecting the selection of the drive motor as the prime mover, determining if the engine oil pressure is zero in response to said detecting step finding selection of the drive motor as the prime mover, preventing energization of the drive motor, when de-energized, and de-energizing the drive motor, when energized, in response to the determining step finding the engine oil pressure is not zero, initiating a predetermined timing period in response to the determining step finding the engine oil pressure is not zero, repeating periodically the step of determining if the engine oil pressure is zero, and providing an indication of a fault when the repeated determining step consistently finds the engine oil pressure is not zero over the predetermined timing period. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A method of detecting slippage of a clutch disposed between an internal combustion engine and a refrigerant compressor in a refrigeration system in which a prime mover for the compressor is selectable between the internal combustion engine and clutch, and an electric drive motor, and wherein the refrigeration system further includes an alternator driven by rotation of the compressor, and a battery connected to be charged by the alternator, comprising the steps of:
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detecting a predetermined fluctuation in the speed of the internal combustion engine, when the internal combustion engine is the selected prime mover, monitoring the polarity of the battery current, with a first polarity indicating battery charging current, and a second polarity indicating battery discharging current, and shutting the internal combustion engine down in response to;
(1) the detecting step detecting said predetermined fluctuation in engine speed, and (2) the monitoring step detecting the second polarity. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29)
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30. A method of detecting reverse operation of an evaporator fan motor in a refrigeration system having a refrigerant compressor driven by a prime mover, with the evaporator fan motor driving air mover means which draws return air from a conditioned space and discharges conditioned air into the conditioned space, including the steps of:
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detecting the temperatures RA and DA of the return air and the discharge air, respectively, determining the difference between the temperatures RA and DA to provide a first difference value Δ
D,comparing said first difference value Δ
D with a first reference value,initiating a predetermined timing period when said first difference value Δ
D exceeds said first reference value,repeating, periodically, the steps of detecting the temperatures RA and DA of the return air and the discharge air, and the step of determining the difference between the temperatures RA and DA, to provide updated difference values Δ
D,comparing each of said updated difference values--Δ
D with a second reference value,and shutting the prime mover and fan motor down when the step of comparing each updated difference value Δ
D with the second reference value consistently finds that each updated difference value Δ
D exceeds said second reference value over said predetermined timing period. - View Dependent Claims (31, 32)
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Specification