Methods and apparatus for monitoring the operation of a transport refrigeration system
US5181389A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 26, 1992 |
| Grant date | Jan 26, 1993 |
| Priority date | — |
| Expiry date | Apr 26, 2012 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG07C5/085
- WIPO fieldTransport
- WIPO sectorMechanical engineering
Abstract
A transport refrigeration unit, and methods and apparatus for monitoring the operation thereof, with the unit conditioning a load to a selected set point temperature via commanded cooling and heating cycles. A thermostat provides a digital signal as a function of the load temperature and the selected set point temperature, with each toggling of the least significant bit (LSB) thereof indicating a predetermined change in load temperature. A timer initiates a predetermined timing period with each toggling of the LSB, with the timing period being a dynamic function of the selected set point temperature. Expiration of the timing period before the next bit toggle initiates an alarm signal indicating the rate-of-change of load temperature is not within an acceptable limit for the selected set point temperature. A comparison of successive digital signals also results in an alarm signal when the direction of temperature change is not consistent with the commanded operating cycle.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.