Refrigeration and defrost control system
AssigneeRobertshaw Controls Company
InventorsThomas Davern, Jack Devine, William Bennett
Life of this patent
Estimating the term…
Abstract
A system and method for refrigeration timer control having an energy efficient defrost cycle are provided. The system and method provide a delay time after the refrigeration cycle and prior to the defrost cycle. During this delay period the evaporator fan may run. The fan circulation and the heat from the fan coil provide a pre-warm cycle to the evaporator prior to the defrost cycle. To further enhance energy efficiency, the system and method may also provide a pre-refrigeration cycle after the defrost cycle. During this pre-refrigeration cycle only the compressor is energized. This prevents warm moist air from being circulated until the evaporator coils are cooled.
Claims20
In a freezer having a refrigeration system including a compressor, an evaporator coil, an evaporator fan to circulate air over the evaporator coil and into a compartment of the freezer, a defrost heater for periodically removing frost build-up from the evaporator coil, and a timer control system controlling the operation of the compressor, evaporator fan, and defrost heater, the timer control system comprising:
- a switch arrangement including a compressor control blade, an evaporator fan control blade, a defrost heater control blade, and a common blade;
- a rotatable cam having a profiled surface in operable communication with the switch arrangement to control a relative positioning of the blades of the switch arrangement such that the compressor control blade and evaporator fan control blade contact the common blade in a first cycle, the defrost heater control blade connects with the common blade in a second cycle, and wherein the cam provides a third cycle between the first cycle and the second cycle to delay the defrost heater control blade from contacting the common blade for a period of time after the first cycle.
A method of defrosting evaporator coils of a refrigeration system comprising the steps of:
- de-energizing a compressor of the refrigeration system;
- waiting a predetermined period of time after the step of de-energizing the compressor;
- and thereafter
- energizing a defrost heater.
A refrigeration control timer, comprising:
- a motor-driven cam having at least one program control track;
- a compressor control blade;
- an evaporator fan control blade;
- an electrical circuit blade;
- and
- a defrost heater control blade;
- and
- wherein the at least one program control track is operable in relation to the compressor control blade, the evaporator fan control blade, the electrical circuit blade, and the defrost heater control blade to connect the compressor control blade and the evaporator fan control blade to the electrical circuit blade during a refrigeration cycle, to connect the evaporator fan control blade to the electrical circuit blade during a pre-warm cycle, and to connect the defrost heater control blade to the electrical circuit blade during a defrost cycle.
Dependencies are inferred from the claim text.