Refrigeration system
US4807445A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 24, 1987 |
| Grant date | Feb 28, 1989 |
| Priority date | — |
| Expiry date | Nov 24, 2007 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02B30/70
- WIPO fieldThermal processes and apparatus
- WIPO sectorMechanical engineering
Abstract
The degree of opening of the expansion valve in refrigeration system is controlled by means of PID control such that a refrigerant superheat at the outlet of the evaporator approaches a target valve. Since an elapsed time after the start of the refrigeration system varies in response to a change of a heat load of air to be cooled by the evaporator, if the control constant of the PID control is designed so that the expansion valve can be controlled adequately for high evaporator heat load, or for low evaporator heat load, adequate control cannot be achieved in the opposite case not taken into consideration in design. According to the present invention, the control constant of the PID control is varied when an elapsed time after the start of the refrigeration system reaches a reference time which is determined on the basis of a heat load of air to be cooled by the evaporator.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.