Thermo King Corporation

David A Christiansen

Lowell B Naley

Richard A Johnson

Alan D Gustafson

Gregory R Truckenbrod

Robert L Harrington

Dannis R Johnson

Laurence R Brickner

Jay L Hanson

Leonard C Vercellotti

Doyle G Herrig

Romuald M Jurewicz

Jayaram Seshadri

Stanley O Hoium

Jeffrey B Berge

Ronald W Seipp

Kevin W Kiefer

Arthur A Anderson

Lawrence J Shirek

Robert G Colclaser, Iii

Herbert S Falk

Robert G Colclaser Iii

John G Leddy

A method of operating a transport refrigeration system having a compressor driven by a prime mover at a selected one of high and low speeds, an evaporator, and an evaporator blower driven by the prime mover. Refrigeration control provides an error value which controls the temperature of a load space to a predetermined set point via heating and cooling modes. The method includes the steps of driving the compressor at high speed during pull down, and injecting hot gas into the evaporator when the error is reduced to a predetermined value. The prime mover is maintained at high speed, to keep evaporator air flow at a high rate, continuing a relatively rapid temperature pull-down across the entire load space. The speed of the prime mover is reduced to low speed when the error is further reduced to a second value, which also initiates suction line modulation while maintaining hot gas injection.

Method of operating a transport refrigeration system

A method of determining if the refrigerant charge in a refrigeration system is within an acceptable range, including the step of developing a model evaporator temperature-versus-time signature for a system known to have a recommended refrigerant charge level. The model developing step includes the steps of isolating an evaporator from a space to be conditioned by the system, operating the system in a cooling mode to cool the evaporator, trapping refrigerant in the cooled evaporator to introduce an instability into the cooling cycle, and continuing the cooling mode for a time sufficient for a system having an acceptable charge level to recover from the trapping step. A test signature is then provided for a system to be checked, using steps similar to those used to develop the model signature, and the test signature is compared with the model signature to determine if the refrigerant charge is within an acceptable range.

Method of determining refrigerant charge

A method of controlling a refrigeration system by determining an average air temperature by sensing and averaging evaporator return and discharge air temperatures, and developing an average error by using the average air temperature and a selected set point temperature. The average air temperature is then used to calculate a proportional error and an integral error, and the discharge air temperature is used to calculate a floor error. The proportional error, integral error and floor error are weighted by predetermined gain factors and then summed to provide an error signal which is used to modulate the capacity of the refrigeration system, with the control mode depending upon the location of the error signal relative to set point.

Method of controlling the capacity of a transport refrigeration system

A power line carrier communication system for monitoring refrigerated containers which includes a master monitoring unit and a first power line interface which interchange messages in a first format. The first power line interface translates the first format to a second format suitable for power line environment, and messages in the second format are applied to a power line. Remote monitoring units receive the messages from the power line, and they return messages to the power line containing status data relative to refrigerated containers. The second format includes a message starting preamble having a duration and logic level which is not duplicated by normal operation of the apparatus, enhancing the probability of proper message synchronization and reception over noisy power line environments.

Power line carrier communication system for monitoring refrigerated

A microprocessor based system monitors and controls a transport refrigeration system having a two speed compressor coupled to a condenser and an evaporator and further having two speed condenser and evaporator fans, a refrigerant modulating valve, and heater means to cool or heat a served space. A keypad is provided for operator entry of the temperature setpoint and for display selections. Return air and discharge air temperature sensors provide signals to the microprocessor for temperature control. The microprocessor is programmed to sequence or control the compressor, the fans, the modulating valve and the heater means for temperature control in accordance with one of four stored algorithms. One of the temperature sensors is used for control, and if it is detected to have failed automatic switchover is made to use of the other temperature sensor for temperature control. Various input signals from the refrigeration system and from the microprocessor hardware are processed by the microprocessor to provide a data log and data for display and to detect system faults for fault history storage and for protective control action.

Microprocessor based control system and method providing better

A transport refrigeration unit for a transport container in which the refrigeration unit has side-by-side evaporator and condenser compartments 18 and 20 in the upper portion of the exterior frame, with a power compartment 24 extending across the entire width of the lower portion of the unit, the power compartment containing an internal combustion engine 26, a motor-alternator 28 and a refrigerant compressor 30 in in-line relationship, a radiator coil 62 condenser coil 64 being in inclined disposition in the condenser compartment and receiving air therethrough from condenser fan 66, the evaporator coil 72 being inclined in the evaporator compartment and in a disposition in which a portion of the coil projects out of the plane of the rear face of the frame, and a pair of double inlet centrifugal fans 74 are provided in the upper portion of the evaporator compartment to draw air from the upper part of the container and direct it downwardly through the coil 72 back into the container, and separate panels 36 and 40 are provided for the evaporator and condenser compartments for individual access, the evaporator panel including an adjustable vent plate 38 for controlling the exchange of air between atmosphere and the container interior.

Container refrigeration unit

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Bloomington, MN, United States of America

David A Christiansen