Method and apparatus for controlling pressure in a single compressor refrigeration system

Apparatus for controlling the system refrigerant pressure in a single refrigeration compressor system, comprising

• timing means for establishing a selected time period functionally related to the compressor on-off cycle,
• means for establishing and detecting an operating suction pressure range in the system for determining when upper and lower limits of said operating pressure range have been exceeded,
• means for generating a compressor turn-on signal in response to exceeding said upper limit of said operating pressure range,
• means for generating a compressor turn-off signal in response to exceeding said lower limit of said operating pressure range, and
• control means receiving said compressor turn-on and turn-off signals and cooperating with said timing means for applying said turn-on signal to said compressor when said upper limit of said operating pressure range has been exceeded, and preventing the application of said turn-off signal to the compressor only if said established time period has not elapsed.

A method of averaging the evaporator compartment temperature in a single compressor refrigeration system, comprising the steps of

• establishing a selected time period functionally related to the compressor on-off cycle,
• establishing an operating suction pressure range,
• detecting the suction pressure in the system for determining when upper and lower limits of said operating pressure range have been exceeded,
• applying a compressor turn-on signal to the compressor in response to exceeding said upper limit of said operating pressure range,
• operating the compressor in the system in response to applying said turn-on signal,
• determining when said lower limit of said operating pressure range has been exceeded for generating a compressor turn-on signal,
• preventing the application of said turn-off signal to the compressor only if said established time period has not elapsed, and
• repeating the above steps for successive determinations of when said upper and lower limits of said operating pressure range have been exceeded for averaging over a long time period the actual time that the compressor is turned on and turned off.

Apparatus for averaging the evaporator compartment temperature in a single compressor refrigeration system, comprising

• timing means for establishing a selected time period functionally related to the compressor on-off cycle,
• means for establishing and detecting an operating suction pressure range in the system for determining when upper and lower limits of said operating pressure range have been exceeded,
• means for generating a compressor turn-on signal in response to exceeding said upper limit of said operating pressure range,
• means for generating a compressor turn-off signal in response to exceeding said lower limit of said operating pressure range,
• control means receiving said compressor turn-on and turn-off signals for successive determinations of when said upper and lower limits of said operating pressure range have been exceeded and cooperating with said timing means for applying said turn-on signal to said compressor when said upper limit of said operating pressure range has been exceeded, and preventing the application of said turn-off signal to the compressor only if said established time period has not elapsed for averaging over a long time period the actual time that the compressor is turned on and turned off.