Thermo King Corporation

Westinghouse Electric Corporation

Lowell B Naley

Jay L Hanson

David A Christiansen

Doyle G Herrig

Alan D Gustafson

Robert L Harrington

Norman F Spear

Richard A Johnson

Lars Ivan Sjoholm

David H Taylor

Romuald M Jurewicz

Peter W Freund

Lee J Erickson

Jayaram Seshadri

Robert W Haberkorn

Gregory R Truckenbrod

James E Nixon

Sung L Kwon

Dannis R Johnson

Jeffrey B Berge

Stanley O Hoium

Gerald J Ladendorf

Ronald W Seipp

Kevin W Kiefer

Lawrence J Shirek

Virgil D Leinum

A method of starting and running an internal combustion engine connected to drive a refrigerant compressor in a refrigeration system which operates the engine at predetermined first and second speeds in response to a predetermined control algorithm, with the first speed being lower than the second speed. The method includes the step of starting and running the engine at the first speed, preventing switching from the first to the second speed in response to the control algorithm during an initial dynamic delay period following the step of starting the engine. The method then includes the step of determining the length of the initial dynamic delay period as a function of at least one predetermined parameter of the engine, and selecting the at least one predetermined engine parameter during the initial dynamic delay period.

Method of starting and running an internal combustion engine connected

A refrigeration system of the type having an economizer cycle is provided with a null cycle, in addition to heating and cooling cycles, without shutting a compressor prime mover down, to preserve air flow in a conditioned space. First, second and third controllable valves respectively: (1) select main and auxiliary condensers, (2) open and close a liquid line, and (3) open and close a line which provides a warm liquid to an economizer heat exchanger. The valves are controlled in at least one predetermined open/close pattern during a null cycle, and preferably in a plurality of selectable predetermined open/close patterns, to provide a null cycle at any instant which substantially matches the net heat gain or loss taking place in the conditioned space. Thus, the temperature of the served space will be more apt to remain in a null temperature range close to set point, providing smoother and more accurate control over the temperature of the conditioned space for longer shelf life of perishables stored therein.

Methods and apparatus for operating a refrigeration system

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 monitoring a transport refrigeration system which is effective regardless of the temperature of a served space relative to a selected set point temperature. Different 'windows' of acceptable and marginal performance are provided in the form of different minimum magnitudes of .DELTA.T, i.e., the algebraic difference between the return and discharge air temperatures, as a function of ambient and return air temperatures. The transport refrigeration system is thus monitored at all times, during both cooling and hot gas heating modes, and also including during initial temperature pull down of the cargo space, enabling an early warning to be generated for a marginal performance, and an early shut down to be initiated for unacceptable performance. In a preferred embodiment, a maximum value of .DELTA.T is also provided, which, if exceeded by the actual .DELTA.T, indicates a restricted air flow in the cargo space.

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 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

The invention relates to the air conditioning of a storage compartment and is especially significant for a transport system. Air is circulated between an air tempering zone and the storage compartment, said air tempering zone having air cooling means and air heating means controlled by a thermostat. The thermostat has a wide range set point and depending upon what set point is selected, the thermostat is responsive either to the temperature of the air discharged from the tempering zone or the temperature of the air returning to said zone. When the set point is above a given point and the air is being cooled to near the desired temperature, said desired temperature is accurately obtained by the thermostat first sending a signal from a selected one of the two sensors that provides a step-reduction in the capacity of the cooling means and then sending a signal to a modulating valve that further reduces to the set point the capacity of the cooling means by a modulation reduction.

Electronic capacity control or direct expansion refrigeration of air

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Minnetonka, MN, United States of America

Lowell B Naley