Pre-trip diagnostic methods for a transport refrigeration unit
First Claim
1. A method of automatically checking predetermined functions and operating performance of a transport refrigeration unit having electrical control, electrically controlled components, a refrigeration circuit which includes a refrigerant compressor, and a prime mover for the refrigerant compressor which includes an internal combustion engine, with the transport refrigeration system conditioning air returning from a cargo space via commanded heating and cooling modes, as required to hold a predetermined set point temperature, and discharging the conditioned air back into the cargo space, and including temperature sensors for providing the temperatures of the return air, discharge air and ambient air, comprising the steps of:
- measuring the current draw of predetermined electrical components with the prime mover stationary,comparing the measured current draw of each electrical component with an allowable range for the component,starting the internal combustion engine at a predetermined rated speed when the comparison step finds that the current draw for each component checked is in the associated allowable range,determining the actual speed of the internal combustion engine,comparing the actual speed of the internal combustion engine with an allowable range for the predetermined rated speed,commanding the transport refrigeration system to operate in a cooling mode,checking for adequate cooling capacity of the transport refrigeration unit as a dynamic function of the temperature values of the return air, discharge air, and ambient air, commanding the transport refrigeration system to operate in a heating mode,determining if the transport refrigeration system is operating in the commanded heating mode by comparing the temperatures of the return air and discharge air,and preparing an indication of a fault condition descriptive of any detected malfunction and marginal operating performance.
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Accused Products
Abstract
Pre-trip operational methods and procedures for automatically checking predetermined functions and the operating performance of a transport refrigeration unit which includes a refrigerant compressor, and a prime mover for the refrigerant compressor which includes an internal combustion engine. The methods include the steps of measuring the current draw of predetermined electrical components with the prime mover stationary, starting the engine when the current draw is normal, determining if the speed of the engine is in an allowable range, commanding the unit to operate in a cooling mode, checking for adequate cooling capacity as a dynamic function of the temperatures of the return air, discharge air, and ambient air, commanding the unit to operate in a heating mode, determining if the unit is actually operating in the heating mode, and preparing an indication of a fault condition descriptive of any detected malfunction and/or marginal operating performance.
40 Citations
13 Claims
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1. A method of automatically checking predetermined functions and operating performance of a transport refrigeration unit having electrical control, electrically controlled components, a refrigeration circuit which includes a refrigerant compressor, and a prime mover for the refrigerant compressor which includes an internal combustion engine, with the transport refrigeration system conditioning air returning from a cargo space via commanded heating and cooling modes, as required to hold a predetermined set point temperature, and discharging the conditioned air back into the cargo space, and including temperature sensors for providing the temperatures of the return air, discharge air and ambient air, comprising the steps of:
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measuring the current draw of predetermined electrical components with the prime mover stationary, comparing the measured current draw of each electrical component with an allowable range for the component, starting the internal combustion engine at a predetermined rated speed when the comparison step finds that the current draw for each component checked is in the associated allowable range, determining the actual speed of the internal combustion engine, comparing the actual speed of the internal combustion engine with an allowable range for the predetermined rated speed, commanding the transport refrigeration system to operate in a cooling mode, checking for adequate cooling capacity of the transport refrigeration unit as a dynamic function of the temperature values of the return air, discharge air, and ambient air, commanding the transport refrigeration system to operate in a heating mode, determining if the transport refrigeration system is operating in the commanded heating mode by comparing the temperatures of the return air and discharge air, and preparing an indication of a fault condition descriptive of any detected malfunction and marginal operating performance. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of automatically checking predetermined functions and operating performance of a transport refrigeration unit operable in a cooling mode, and including electrical control, electrically controlled components, including a modulation valve, a refrigeration circuit which includes the modulation valve in a suction line thereof, a refrigerant compressor connected to the refrigerant circuit, and a prime mover for the refrigerant compressor which includes an internal combustion engine, comprising the steps of:
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running the internal combustion engine, operating the transport refrigeration unit in the cooling mode with the modulation valve open, storing the speed of the internal combustion engine, closing the modulation valve to a predetermined setting, determining the speed of the internal combustion engine after the closing step, comparing the determined speed with the stored speed of the internal combustion engine, and storing an indication of a fault in the event the comparison step does not find that the determined speed exceeds the stored speed. - View Dependent Claims (12, 13)
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Specification