Method to control electronic expansion valve

Patent metadata

Field	Value
Publication number	US-9874381-B2
Application number	US-201514843057-A
Country	US
Kind code	B2
Filing date	Sep 2, 2015
Priority date	Dec 22, 2011
Publication date	Jan 23, 2018
Grant date	Jan 23, 2018

Abstract

A vapor compression refrigeration cycle system includes a compressor and an electronic expansion valve connected between first and second refrigerant ports of a compressor. An expansion valve controller is configured to control a flow of refrigerant through the expansion valve in response to a superheat temperature of the refrigerant. The controller is configured to execute a first control algorithm until a local maximum of the superheat temperature occurs, and then to execute a second control algorithm.

First claim

What is claimed is:

1. A system comprising:
a compressor comprising a refrigerant inlet port and a refrigerant outlet port;
an expansion valve interoperably coupled to the compressor;
a controller interoperably coupled to the compressor and the expansion valve;
wherein the controller is configured to:
determine whether the compressor is operating;
responsive to a determination that the compressor is operating, execute a startup-control algorithm to adjust a flow rate of refrigerant through the expansion valve;
determine an occurrence of a local maximum of a superheat temperature;
responsive to a determination that the local maximum of the superheat temperature has occurred, initiate a steady-state control algorithm; and
execute a transition-control algorithm prior to execution of the steady-state control algorithm, the transition-control algorithm brings the superheat temperature from a value at an end of the startup-control algorithm to within a temperature range at which the steady-state control algorithm is configured to maintain the superheat temperature during execution of the steady-state control algorithm.

2. The system of claim 1 , wherein the local maximum of the superheat temperature occurs when a first derivative of the superheat temperature changes from positive to negative and a current iteration time is greater than a predetermined startup time detected by the controller.

3. The system of claim 1 , wherein the controller is configured to return to the startup-control algorithm in an event that the expansion valve reaches a zero flow condition after the controller initiates the steady-state control algorithm.

4. The system as claim 1 , wherein, when executing the startup-control algorithm, the controller opens the expansion valve at a rate proportional to a second derivative of the superheat temperature.

5. The system of claim 1 , wherein the steady-state control algorithm is a fuzzy-logic algorithm.

6. The system of claim 1 , wherein the steady-state control algorithm is a proportional-integral-derivative control algorithm.

7. A controller comprising:
a memory configured to store operating instructions of a control algorithm;
an input interface configured to receive an input indicative of a superheat temperature of a refrigerant;
a processor interoperably coupled to the memory and the input interface;
in response to the input, the processor is configured to:
execute the operating instructions and issue a control signal to control a stepper motor;
determine whether a compressor is operating;
responsive to a determination that the compressor is operating, execute a startup-control algorithm to adjust a flow rate of refrigerant through an expansion valve;
determine occurrence of a local maximum of the superheat temperature; and
responsive to a determination that the local maximum of the superheat temperature has occurred, initiate a steady-state control algorithm; and

wherein the controller is configured to execute, a transition-control algorithm prior to execution of the steady-state control algorithm that brings the superheat temperature from a value at an end of the startup-control algorithm to within a temperature range at which the steady-state control algorithm is configured to maintain the superheat temperature during execution of the steady-state control algorithm.

8. The controller of claim 7 , wherein the local maximum of the superheat temperature occurs when a first derivative of the superheat temperature changes from positive to negative and a current iteration time is greater than a predetermined startup time detected by the controller.

9. The controller of claim 7 , wherein the controller is configured to return to the startup-control algorithm in an event that the expansion valve reaches a zero flow condition after the controller executes the steady-state control algorithm.

10. The controller of claim 7 , wherein, when executing the startup-control algorithm, the controller opens the expansion valve at a rate proportional to a second derivative of the superheat temperature.

11. The controller of claim 7 , wherein the steady-state control algorithm is a fuzzy-logic algorithm.

12. The controller of claim 7 , wherein the steady-state control algorithm is a proportional-integral-derivative control algorithm.

Assignees

• Lennox Ind Inc

Inventors

• Qu Yi
• Crawford Carl

Classifications

• F25B2700/21151

  at the suction side of the compressor · CPC title

• G05D7/0629

  characterised by the type of regulator means · CPC title

• F25B2500/26

  characterised by the startup of the refrigeration cycle · CPC title

• F25B2600/21

  Refrigerant outlet evaporator temperature · CPC title

• F25B2600/2513

  Expansion valves · CPC title