Thermally actuated flow control valve

Abstract

This disclosure relates to a system including a valve, a control unit, and a thermal element. The thermal element is selectively operable in response to instructions from the control unit to control a position of the valve. The control unit is operable in a static mode and a dynamic mode. In the static mode, the valve position is held substantially constant. In the dynamic mode, the valve position is adjusted in response to a valve outlet condition.

1 . A system, comprising:
 a valve;   a control unit;   a thermal element selectively operable in response to instructions from the control unit to control a position of the valve; and
 wherein the control unit is operable in one of (1) a static mode where valve position is held substantially constant and (2) a dynamic mode where valve position is adjusted in response to a valve outlet condition. 
   
     
     
         2 . The system as set forth in  claim 1 , wherein the valve includes a valve pin and a support shell, and wherein the valve pin and the support shell are formed of different materials, each having a different coefficient of thermal expansion. 
     
     
         3 . The system as set forth in  claim 1 , further comprising a sensor configured to generate a signal indicative of the valve outlet condition, the control unit providing instructions to the thermal element in response to the signal from the sensor when in dynamic mode. 
     
     
         4 . The system as set forth in  claim 1 , wherein a temperature sensor is placed near the valve. 
     
     
         5 . The system as set forth in  claim 1 , wherein, when in the static mode, the control unit provides instructions to the thermal element to maintain the valve at a substantially constant temperature to achieve a substantially constant flow rate regardless of the valve outlet condition. 
     
     
         6 . The system as set forth in  claim 1 , wherein the valve outlet condition is one of (1) an outlet pressure and (2) an outlet flow rate. 
     
     
         7 . The system as set forth in  claim 1 , wherein the thermal element is located at one of (1) a location within a housing of the valve and (2) a location adjacent to the support shell and the valve pin. 
     
     
         8 . The system as set forth in  claim 1 , wherein the system includes a mass spectrometer. 
     
     
         9 . The system as set forth in  claim 8 , wherein the control unit is operable in the dynamic mode to regulate the pressure within an ion source of a mass spectrometer, and wherein the control unit is operable in the static mode to regulate fluid flow rate. 
     
     
         10 . A method, comprising:
 (a) operating a thermal element to control a position of a valve;   (b) holding the valve position substantially constant when in a static mode; and   (c) adjusting the valve position in response to a valve outlet condition when in a dynamic mode.   
     
     
         11 . The method as set forth in  claim 10 , wherein the valve includes a valve pin and a support shell, and wherein the valve pin and the support shell are formed of different materials, each having a different coefficient of thermal expansion. 
     
     
         12 . The method as set forth in  claim 10 , wherein, when in the dynamic mode, a control unit instructs the thermal element to adjust the valve position based on the valve outlet condition. 
     
     
         13 . The method as set forth in  claim 10 , wherein, when in the static mode, a control unit instructs the thermal element to maintain the valve at a substantially constant temperature to achieve a substantially constant flow rate regardless of the valve outlet condition. 
     
     
         14 . The method as set forth in  claim 10 , wherein the valve outlet condition is one of (1) an outlet pressure and (2) an outlet flow rate. 
     
     
         15 . The method as set forth in  claim 10 , further including a mass spectrometer and a control unit, wherein the control unit is operable in the dynamic mode to regulate the pressure within an ion source of a mass spectrometer, and wherein the control unit is operable in the static mode to regulate fluid flow rate.