The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 27, 1986
Filed:
May. 22, 1985
Jacob E Shaffer, York, PA (US);
Wayne D Dellinger, Windsor, PA (US);
James R Harnish, York, PA (US);
Borg-Warner Corporation, Chicago, IL (US);
Abstract
By sensing the outdoor ambient temperature and the outdoor coil temperature in a heat pump when the outdoor coil is frost-free, a control system determines the split or difference that will later exist between those temperatures (the coil temperature drops as frost accumulates) when sufficient frost has built up on the outdoor coil to necessitate defrosting. When that defrost temperature split, called the Normal Defrost Value or NDV, is exceeded, defrost is initiated and the coil will be defrosted. Since the amount of frost that may have already accumulated on the coil is unknown when the control system is initially powered up (such as when power is restored after an outage), the control system calculates, from the current outdoor ambient temperature, an assumed value for the coil temperature which is likely to exist if the coil were frost-free. The first NDV determined after power up is based on the assumed coil temperature. As a safety feature to prevent damage to the heat pump, a Default Defrost Value (DDV), which is the maximum temperature split that will be allowed between the outdoor ambient temperature and the coil temperature, is calculated based on the current outdoor temperature. If the coil temperature ever drops below the outdoor temperature to an extent greater than the DDV, the outdoor coil is defrosted. If two successive default defrosts are requested within one hour, the heat pump's compressor is turned off and locked out.