Refrigeration mechanical diagnostic protection and control device

Abstract

In vapor compression refrigeration systems a mechanism and method are provided for protecting a compressor from failures related to lack of superheat, loss of lubricating oil and other system malfunctions. Also provided is a mean of monitoring system conditions and providing service personnel with a quick manner of diagnosing problems.

Description

BACKGROUND OF THE INVENTION [0001] The present invention relates to refrigeration, air conditioning and heat pumps and more particularly to a method and apparatus for monitoring and controlling system pressures, temperatures, and superheat and subcooling. [0002] In the operation of refrigeration and air conditioning systems, the cooling effect is provided by the change in state of the refrigerant from a liquid to a gas in the evaporator of the system. The gaseous refrigerant is compressed by a compressor and is condensed to a liquid state in a condenser before passing through an expansion valve upon being returned to the evaporator. [0003] The failure of a compressor is usually very costly. Most compressor failures can be traced back to one of the following system conditions: “refrigerant floodback”, “flooded starts”, “slugging”, excessively high discharge temperature or loss of lubricating oil. [0004]“Refrigerant floodback” results when liquid refrigerant returns to the compressor ...

AI Technical Summary

Benefits of technology

[0024] In addition to system protection from low superheat, the present invention uses the collected data to further increase system efficiency by providing a method of increasing subcooling under heavy load conditions or decreasing subcooling when needed.

[0025] An electrical device monitors the mechanical aspects of standard refrigeration and air conditioning systems. The device protects these systems by calculating temperature, pressure, superheat, sub-cooling, ambient temperature and controlling system components. The device provides an easy, graphic representation of system conditions and faults for rapid verification of satisfactory operating parameters. Further detailed system conditions are provided for more extensive examination through use of digital read-outs.

Problems solved by technology

The failure of a compressor is usually very costly.

Most compressor failures can be traced back to one of the following system conditions: “refrigerant floodback”, “flooded starts”, “slugging”, excessively high discharge temperature or loss of lubricating oil.

The lubricant oil becomes mixed with refrigerant to the point that it cannot properly lubricate the load bearing surfaces.

When the compressor starts, the diluted oil cannot properly lubricate the load bearing surfaces causing erratic wear.

In the case of excessively high discharge temperature the compressor head and cylinders become so hot that the oil loses its ability to lubricate properly.

This causes rings, pistons and cylinders to wear resulting in “blow by”, leaking valves and metal debris in the oil.

Loss of oil is the result of insufficient oil in the crankcase to properly lubricate the load bearing surfaces.

The result is the system superheat.

Another cause for concern is introduction of foreign materials from the gauge set into the system.

This device does not monitor or display other system parameters such as temperature and pressure.

Further it does not provide simple system status indicators for the actual condition of superheat.

This device also relies on analog to digital converters for refrigerant pressure sensing, a method with inherent inaccuracies that would not provide the level of accurate control required with a refrigeration system under heavy load conditions.

These devices, however, only address one or two dangerous systems conditions and fail to provide and adequate level of compressor protection.

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