Defrost system
First Claim
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1. A system for defrosting a refrigeration unit wherein heat is exchanged between refrigerant in a heat exchange means and a stream of air directed over said heat exchange means comprising:
- means for sensing a determined temperature of said heat exchange means and providing a temperature signal representative thereof;
means for sensing a determined change in pressure in said stream of air over said heat exchange means caused by frost thereon and providing a pressure signal representative thereof;
means for heating said heat exchange means to melt frost thereon defrosting same;
and timing means for actuating said heating means thereby initiating a defrost cycle only upon the simultaneous occurrence of said temperature and pressure signals for a determined interval and for thereafter terminating said defrost cycle upon the lapse of a determined interval or upon a determined change in said temperature signal whichever condition occurs first.
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Accused Products
Abstract
A defrost system for refrigeration units, particularly heat pumps, is described. Features include means for initiating a defrost cycle upon the concurrence of two sensed conditions, and terminating the defrost cycle either on the lapse of a determined time interval or the occurrence of a sensed condition, whichever occurs first. Delay timer means prohibits consecutive defrost cycles or a defrost cycle upon restoration of power in the event of a power failure. Means are also provided permitting short cycle testing of the system.
53 Citations
6 Claims
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1. A system for defrosting a refrigeration unit wherein heat is exchanged between refrigerant in a heat exchange means and a stream of air directed over said heat exchange means comprising:
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means for sensing a determined temperature of said heat exchange means and providing a temperature signal representative thereof; means for sensing a determined change in pressure in said stream of air over said heat exchange means caused by frost thereon and providing a pressure signal representative thereof; means for heating said heat exchange means to melt frost thereon defrosting same; and timing means for actuating said heating means thereby initiating a defrost cycle only upon the simultaneous occurrence of said temperature and pressure signals for a determined interval and for thereafter terminating said defrost cycle upon the lapse of a determined interval or upon a determined change in said temperature signal whichever condition occurs first. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification