Carrier Corporation

Michael J Brandemuehl

John Robert Reason

Daryl G Erbs

A method of closely controlling the supply air temperature delivered from an air conditioning unit into a mobile cargo container wherein the supply air temperature is compared to a desired set point temperature and a suction control valve in the air conditioner compressor inlet line is adjusted in response to the sensed difference between the supply air temperature and the set point temperature. Three different preprogramed control modes are available which are selected automatically in response to the amount of deviation between the compared temperatures that are used to bring the supply temperature down the set point temperature and hold it under steady state conditions within .+-.0.25.degree. C. of the set point. A trim heater is placed in the supply air passage to warm the supply air any time the control valve is in a full closed position. This increases the heating load on the unit so that operating time of the unit will be prolonged and the compressor will not be cycling ON and OFF.

Control apparatus for refrigerated cargo container

A method of closely controlling the supply air temperature delivered from an air conditioning unit into a mobile cargo container wherein the supply air temperature is compared to a desired set point temperature and a suction control valve in the air conditioner compressor inlet line is adjusted in response to the sensed difference between the supply air temperature and the set point temperature. Three different preprogramed control modes are available which are selected automatically in response to the amount of deviation between the compared temperatures that are used to bring the supply temperature down to the set point temperature and hold it under steady state conditions within .+-.0.25.degree. C. of the set point. A trim heater is placed in the supply air passage to warm the supply air any time the control valve is in a full closed position. This increases the heating load on the unit so that operating time of the unit will be prolonged and the compressor will not be cycling ON and OFF.

Provision is made in a multiple zone air conditioning system for varying the speed of the compressor to match the load thereon. The differences between the actual temperatures and the set points in the individual zones are monitored and the largest of these differences is periodically selected and applied to a transfer function to obtain a new speed at which the compressor is run. At the same time, the individual dampers within the zones are modulated in response to their respective sensed temperature differences. Provision is also made to vary the speed of the indoor fan in a similar manner.

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Manlius, NY, United States of America

Michael J Brandemuehl