REFRIGERANT CHARGE INDICATION

• US 20100089076A1
• Filed: 12/20/2006
• Published: 04/15/2010
• Est. Priority Date: 12/20/2006
• Status: Active Grant

• Current Assignee: Carrier Corporation (Carrier Global Corporation)
• Original Assignee: Carrier Corporation (Carrier Global Corporation)
• Inventors: Schuster, Don A., Das, Sathish R.
• Granted Patent: US 9,568,226 B2
• Time in Patent Office: Days
• US Class Current: 62/77
• CPC Class Codes: F25B 2345/00 Details for charging or discharging refrigerants; Service stations therefor
• CPC Class Codes: F25B 2600/05 Refrigerant levels
• CPC Class Codes: F25B 2700/00 Sensing or detecting of parameters; Sensors therefor
• CPC Class Codes: F25B 2700/04 Refrigerant level
• CPC Class Codes: F25B 45/00 Arrangements for charging or discharging refrigerant
• CPC Class Codes: F25B 49/005 of safety devices F25B49/02 and F25B49/04 take precedence

Abstract

A method and apparatus are provided for indicating the status of the refrigerant charge in an air conditioning system based upon the degree of subcooling present in the condensed refrigerant system temperature measurements. The status of the refrigerant charge in the system is indicated in real-time on a service panel for access by a field service technician. The status of the refrigerant charge in the system on a time-average basis for a specified period of operation is presented on an indicator panel. The indicator panel includes a first indicator light indicating that the refrigerant charge is low, a second indicator light indicating that the refrigerant charge is high, and a third indicator light indicating that the refrigerant charge is correct.

Claims

1. A method for indicating the level of refrigerant charge in a refrigerant vapor compression system having a compressor, a condenser coil, an expansion device and an evaporator coil connected in serial relationship in refrigerant flow circuit, comprising the steps of:

sensing the pressure of the refrigerant leaving the condenser coil and generating a first signal indicative of the sensed refrigerant pressure;

sensing the temperature of the refrigerant downstream of the condenser coil and upstream of the expansion device and generating a second signal indicative of the sensed refrigerant temperature;

calculating in real-time a value for the degrees of subcooling present based upon the sensed refrigerant pressure and the sensed refrigerant temperature;

outputting an electrical signal indicative of the real-time value for the degrees of subcooling present;

calculating an average value for the degrees of subcooling over a preselected time period of system operation; and

outputting an indication of a refrigerant charge status over the preselected time period of system operation.

2. A method as set forth in claim 1 wherein the step of outputting an indication of refrigerant charge status over a preselected time period of system operation comprises the step of outputting an indication of whether the refrigerant charge status is low, high or correct.

3. A method as set forth in claim 1 wherein the step of outputting an indication of refrigerant charge status over a preselected time period of system operation comprises the steps of:

providing an acceptable range for said average value for the degrees of subcooling over a preselected time period of system operation, said acceptable range extending from a lower threshold level to an upper threshold level;

comparing said average valve for the degrees of subcooling over a preselected time period of system operation to said acceptable range therefor; and

providing a refrigeration charge status indication reflecting one of;

a low refrigerant charge if said average valve for the degrees of subcooling over a preselected time period of system operation is below said lower threshold value, a high refrigerant charge if said average valve for the degrees of subcooling over a preselected time period of system operation is above said upper threshold value, and a correct refrigerant charge if said average valve for the degrees of subcooling over a preselected time period of system operation lies within said acceptable range.

4. A method as set forth in claim 3 wherein the step of providing a refrigeration charge status indication reflecting one of a low refrigerant charge, a high refrigerant charge or a correct refrigerant charge comprises:

illuminating a first light indicating a low refrigerant charge if said average valve for the degrees of subcooling over a preselected time period of system operation is below said lower threshold value,

illuminating a second light indicating a high refrigerant charge if said average valve for the degrees of subcooling over a preselected time period of system operation is above said upper threshold value, and

illuminating a third light indicating a correct refrigerant charge if said average valve for the degrees of subcooling over a preselected time period of system operation lies within said acceptable range.

5. A method as set forth in claim 1 wherein said step of outputting an electrical signal indicative of the real-time value for the degrees of subcooling present comprises the step of outputting a milli-volt electrical signal indicative of the real-time value for the degrees of subcooling present.

6. Apparatus for indicating the level of refrigerant charge in a refrigerant vapor compression system having a compressor, a condenser coil, an expansion device and an evaporator coil connected in serial relationship in refrigerant flow circuit, comprising the steps of:

a pressure sensor for sensing the pressure of the refrigerant leaving the condenser coil and generating a first signal indicative of the sensed refrigerant pressure;

a temperature sensor for sensing the temperature of the refrigerant downstream of the condenser coil and upstream of the expansion device and generating a second signal indicative of the sensed refrigerant temperature;

a processor for calculating in real-time a value for the degrees of subcooling present based upon the sensed refrigerant pressure and the sensed refrigerant temperature and outputting an electrical signal indicative of the real-time value for the degrees of subcooling present and for calculating an average value for the degrees of subcooling over a preselected time period of system operation and outputting an indication of a refrigerant charge status over the preselected time period of system operation.

7. Apparatus as recited in claim 6 wherein further comprising a service panel for receiving the electrical signal indicative of the real-time value for the degrees of subcooling present from said processor, said service panel having a tap at which the electrical signal indicative of the real-time value for the degrees of subcooling present is presented.

8. Apparatus as recited in claim 6 further comprising an indicator panel for receiving a signal indicative of the refrigerant charge status over the preselected time period of system operation, said indicator panel having a first indicator associated with a low refrigerant charge, a second indicator operatively associated with a high refrigerant charge, and a third indicator operatively associated with a correct refrigerant charge.

9. Apparatus as recited in claim 8 wherein:

said first indicator comprises a first light adapted to be illuminate for indicating a low refrigerant charge;

said second indicator comprises a second light adapted to be illuminated for indicating a high refrigerant charge; and

said third indicator comprises a third light adapted to be illuminated for indicating a correct refrigerant charge.

10. Apparatus for indicating the level of refrigerant charge in an air conditioning system having a compressor, a condenser coil, an expansion device and an evaporator coil connected in serial relationship in refrigerant flow circuit, comprising the steps of:

a pressure sensor for sensing the pressure of the refrigerant leaving the condenser coil and generating a first analog signal indicative of the sensed refrigerant pressure;

a first analog-to-digital converter operatively associated with said pressure sensor for converting said first analog signal into a first digital signal;

a temperature sensor for sensing the temperature of the refrigerant downstream of the condenser coil and upstream of the expansion device and generating a second analog signal indicative of the sensed refrigerant temperature;

a second analog-to-digital converter operatively associated with said temperature sensor for converting said second analog signal into a second digital signal;

a microprocessor for receiving said first and second digital signals and calculating in real-time a value for the degrees of subcooling present based upon the sensed refrigerant pressure and the sensed refrigerant temperature and outputting an digital signal indicative of the real-time value for the degrees of subcooling present and for calculating an average value for the degrees of subcooling over a preselected time period of system operation and outputting an indication of a refrigerant charge status over the preselected time period of system operation;

a digital-to-analog converter for converting the digital signal indicative of the real-time value for the degrees of subcooling present to a millivolt electrical signal;

a service panel for receiving the millivolt electrical signal indicative of the real-time value for the degrees of subcooling present from said processor, said service panel having a tap at which the millivoltelectrical signal indicative of the real-time value for the degrees of subcooling present is presented; and

an indicator panel for receiving a signal from said microprocessor indicative of the refrigerant charge status over the preselected time period of system operation, said indicator panel having a first light adapted to be illuminate for indicating a low refrigerant charge, a second light adapted to be illuminated for indicating a high refrigerant charge, and a third light adapted to be illuminated for indicating a correct refrigerant charge.