Transport refrigeration system control
AssigneeThermo King Corporation
InventorLeland L. Howland
Life of this patent
Estimating the term…
Abstract
A transport refrigeration unit powered by a two speed prime mover and having the capability of providing at least four modes of operation is controlled by an arrangement as shown in FIG. 2 which provides for operation in either a continuous cycle in which the prime mover runs continuously to provide the modes shown in FIG. 3 or, alternatively, operates in a start-stop cycle to provide the modes of operation shown in FIG. 4. The control in both of the cycles of operation provide for delays in the change of speed from low to high upon certain departures in temperature from one temperature band to another band which would normally call for high speed operation.
Claims15
In a transport refrigeration system of the type having the capabilities of at least heating and cooling operations, and dual compressor speed operation, and control means responsive to temperatures in the space served by the system for controlling the system in at least four modes of operation in accordance with temperatures in the served space differing from a setpoint temperature range, and in accordance with served space temperature being in first and second temperature bands first above the next above, respectively, the setpoint temperature range, and in accordance with served space temperatures being in third and fourth temperature bands first below and next below, respectively, the setpoint temperature range, the improvement comprising:
- said control means includes means for operating the system in either a continuous cycle with said compressor running continuously and, alternatively, in an automatic start-stop cycle in which said compressor is stopped when the served space temperature is in said third temperature band;
- said control means further including speed change delay means operative in said continuous cycle operation to delay for a predetermined time an increase in compressor speed from low to high upon a departure in served space temperatures from either the third to the fourth band, or from the first to the second band, coupled with an uninterrupted call by said control means for said high speed, and operative in a start-stop cycle, with said compressor stopped when the served space temperature is in said third temperature band, to effect any start of said compressor, occasioned by a departure of served space temperature from said third band, at said low speed.
In the method of operation of a transport refrigeration system which has high and low speed diesel engine driven compressor operation, and both heating and cooling capabilities, and in which the system provides at least high speed cooling, low speed cooling, low speed heat, and high speed heat modes of operation corresponding to the temperatures of the served space being in ranges well above, next above, next below, and well below, respectively, the set point temperature for the system, the improved method of operation comprising:
- operating said system with said engine running continuously to provide at least the modes of operation as listed in the preamble hereto;
- and
- alternatively, operating said system with said engine operating in an automatic start-stop cycle in which said engine is stopped as the temperature in said served space either descends down into or rises up into said temperature range next below said set point temperature, and said engine is started again upon a predetermined departure in served space temperature from said temperature range next below said set point temperature.
Dependencies are inferred from the claim text.