Self-adjusting valve

• US 6,105,379 A
• Filed: 03/14/1997
• Issued: 08/22/2000
• Est. Priority Date: 08/25/1994
• Status: Expired due to Fees

• Current Assignee: Altech Controls Corporation
• Original Assignee: Altech Controls Corporation
• Inventors: Johnson, Jeffrey W., Malone, Paul, Rose, Collin A., Bryson, Barry, Ansted, Roger C., Alsenz, Richard H.
• Primary Examiner(s): Tapolcai, William E.
• Application Number:
  US08/818,704
• Time in Patent Office: 1,257 Days
• Field of Search: 236/92 B, 62/225, 62/210, 62/211
• US Class Current: 62/225
• CPC Class Codes: F25B 2341/062 Capillary expansion valves
• CPC Class Codes: F25B 2341/0681 the sensor is heated
• CPC Class Codes: F25B 2700/21171 of the fluid cooled by the evaporator
• CPC Class Codes: F25B 2700/21175 of the refrigerant at the outlet of the evaporator
• CPC Class Codes: F25B 41/335 via diaphragms

Abstract

The present invention discloses an automatic self-adjusting thermally powered expansion valve for controlling the flow of refrigerant to an evaporator of a refrigeration system. The valve includes a differential fluid amplifier transducer which produces a constant flow of refrigerant independent of the liquid line pressure and includes a generally cylindrical interior with an inlet chamber having an inlet port and an outlet chamber having an outlet port and an orifice between the chambers providing a passage for the flow of refrigerant through the valve. The flow of refrigerant through the valve is regulated by a valve element, which moves longitudinally within the chambers with respect to the orifice. The longitudinal position of the valve element is controlled by force generators and sensors. The position of the valve element depends on the fluid pressure and the size of the pressure disks, and the spring constant of the compression spring. As the temperature at the sensors increases, so to does the pressure force on the pressure disks.

Claims

1. An apparatus for controlling the flow of refrigerant fluid through an evaporator in a refrigeration system comprising a self-adjusting thermally powered expansion valve having a back pressure for controlling fluid flow downstream of the valve independently of the fluid pressure upstraem of the valve, said valve has an inlet and an outlet for passage of fluid through the valve and a valve element intermediate the inlet and outlet such that the position of the valve element determines the flow passage area for flow between the inlet and outlet,

a first probe for sensing the temperature at a first location and providing a fluid pressure that is representative of the sensed temperature to configure the valve element for controlling the flow of refrigerant fluid through the orifice, and

a second probe for sensing the temperature at a second location and providing a fluid pressure that is representative of the sensed temperature to configure the valve element for controlling the flow of refrigerant fluid through the orifice.

2. The apparatus as in claim 1, further comprising:

a first force generator, operable by application of fluid pressure thereto for applying force tending to move the valve element in a first direction tending to close the flow passage area to flow; and

a second force generator, operable by application of fluid pressure thereto for applying force tending to move the valve element in a second direction tending to open the flow passage area to flow.

3. The apparatus as in claim 1, wherein said first probe is located in the air external to the evaporator.

4. The apparatus as in claim 1, wherein said second probe is located at the evaporator outlet.

5. The apparatus as in claim 1, wherein:

said first probe is in fluid pressure communication with the first force generator and applies fluid pressure to the first force generator that is representative of the temperature external of the evaporator; and

said second probe is in fluid pressure communication with the second force generator and applies fluid pressure to the second force generator that is representative of the temperature sensed at the evaporator outlet.

6. A valve as defined in claim 5 wherein the first force generator produces force in response to a quantity of fluid pressure applied thereto that is smaller than force produced by the second force generator in response to the same quantity of fluid pressure applied thereto.

7. A valve as in claim 5 wherein the first and second force generators comprise first and second bellows, respectively, and the first operable area of the first bellows for generating forces to configure the valve element is smaller than the second operable area of the second bellows for generating forces to configure the valve element.

8. A valve as in claim 7 wherein the first operable area is approximately 60% of the second operable area.

9. A valve as in claim 2 wherein:

the valve element is a sliding valve element;

the first force generator operatively connects to the valve element on one side thereof;

the second force generator operatively connects to the valve element the opposite side thereof; and

at least one fluid pressure communication passage communicating fluid pressure from downstream of the valve to said first and second force generators.

10. A valve as in claim 2 further comprising a spring for applying a force tending to move the valve element in the first direction.

11. An apparatus for cooling at least one refrigerated area in a refrigeration system, comprising:

an evaporator having an evaporator inlet and an evaporator outlet;

a thermo-mechanical expansion valve having an inlet and an outlet for the passage of refrigeration fluid through the valve and a valve element intermediate the inlet and outlet such that the position of the valve element determines the flow passage area for flow between the inlet and outlet, the outlet being connected to the evaporator inlet;

a force generator representative of the refrigerated area'"'"'s temperature operably connected to the valve element; and

an opposing force generator representative of the temperature at the outlet of the evaporator operably connected to the valve element, the resultant forces of the force generators controlling the flow passage area; and

a restrictor creating a back pressure at the outlet whereby the flow passage area and back pressure meter refrigeration fluid into the evaporator inlet in response to a change in the compartment air temperature.

12. The apparatus of claim 11 wherein said force generator controls the closing of said orifice of said thermo-mechanical expansion valve to restrict the metering of liquid into the inlet of said evaporator in response to an increase of the temperature at the evaporator outlet.

13. A method of controlling the flow of refrigerant to an evaporator of a refrigeration system comprising the steps of:

passing liquid refrigerant into the inlet of a self-adjusting expansion valve;

placing a back pressure on the refrigerant flow through the valve;

controlling refrigerant flow downstream of the valve independently of the refrigerant pressure upstream of the valve;

maintaining the temperature at the outlet end of the evaporator lower than the temperature external to the evaporator and higher than the temperature within the evaporator; and

sensing the temperature of the air external to the evaporator and applying a quantity of fluid pressure that is representative of the sensed temperature to configure the valve.

14. A method as defined in claim 13 further comprising:

increasing refrigerant flow when the temperature of the air external to the evaporator decreases, or the temperature at the outlet end of the evaporator increases, or the pressure in the evaporator decreases; and

decreasing refrigerant flow when the temperature of the air external to the evaporator increases, or the temperature at the outlet end of the evaporator decreases, or the pressure in the evaporator increases.

15. A method as defined in claim 13 further comprising:

increasing refrigerant flow when the difference between the temperature at the outlet end of the evaporator and the temperature within the evaporator increases, or the difference between the temperature of the air external to the evaporator and the temperature within the evaporator decreases; and

decreasing refrigerant flow when the difference between the temperature at the outlet end of the evaporator and the temperature within the evaporator decreases, or the difference between the temperature of the air external to the evaporator and the temperature within the evaporator increases.