Demand defrost controller for refrigerated display cases
US4993233A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 26, 1989 |
| Grant date | Feb 19, 1991 |
| Priority date | — |
| Expiry date | Jul 26, 2009 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF25B2700/21173
- WIPO fieldFurniture, games
- WIPO sectorOther fields
Abstract
A demand defrost controller employs temperature measurements taken at the outlet of the discharge air curtain and the inlet of the air return to determine the need for defrost. If the difference between these temperature measurements exceeds a set point for a predetermined sustained period of time and a minimum amount of time has elapsed since the last defrost of the case, defrost is initiated. Regardless of the value of the temperature difference, defrost is initiated if elapsed time since the last defrost exceeds a specified maximum time between defrosts for the case. Defrost can be terminated on the basis of time and/or temperature. The demand defrost controller can also control display case temperature and can be applied to independently control multiple display case circuits.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.