Exhaust gas recirculation valve having a rotary motor

Abstract

An exhaust gas recirculation valve is provided. The exhaust gas recirculation valve has a base, a spring biasing the valve closed, and an actuator including a rotary motor and a linearly displaceable shaft that is coupled to the motor's rotor. The valve includes a valve member and valve seat disposed within a fluid conduit, and the spring is disposed between the actuator and the valve.

1 . An exhaust gas recirculation valve, comprising: 
 a base including a fluid conduit extending between first and second ports;    a valve member disposed within the fluid conduit, the valve member being configured from a closed to an open position by linear displacement of the valve member;    a valve shaft having a first end fixed to the valve member;    a linear actuator including a rotary motor, the linear actuator positioned to exert an actuator force on the valve shaft to displace the valve shaft in a first direction; and    a valve spring disposed between the actuator and the valve shaft, the valve spring being positioned to exert a spring force on the valve shaft in a second direction opposite the first direction, the spring force being sufficient to back drive the linear actuator.    
   
   
       2 . The-exhaust gas recirculation valve of  claim 1 , further comprising:. 
 a pintle assembly including the valve shaft and a moving member of the valve member; and    a spring cup connecting the spring with the valve shaft,    wherein a preload on the spring is greater than a force represented by:      (mass of pintle assembly+½ mass of valve spring+mass of spring cup)*(expected acceleration load on exhaust gas recirculation valve).    
   
   
       3 . The exhaust gas recirculation valve of  claim 2 , wherein the expected acceleration load on the valve is 13 G.  
   
   
       4 . The exhaust gas recirculation valve of  claim 1 , wherein the motor is a synchronous motor.  
   
   
       5 . The exhaust gas recirculation valve of  claim 1 , wherein the actuator includes a member coupled to the motor's rotor and the member is disposed adjacent to a second end of the valve shaft.  
   
   
       6 . The exhaust gas recirculation valve of  claim 5 , wherein the member includes a disc-shaped end, the valve shaft includes a curved end, and wherein when the valve is configured in the open position, the curved surface is in contact with the member's end.  
   
   
       7 . The exhaust gas recirculation valve of  claim 1 , wherein the spring is a linear spring.  
   
   
       8 . The exhaust gas recirculation valve of  claim 7 , wherein the valve shaft includes a flange and the spring is disposed between the flange and the valve member.  
   
   
       9 . The exhaust gas recirculation valve of  claim 8 , the exhaust gas recirculation valve further including a bracket having a first end secured to the base and a second end, wherein the actuator is disposed above the bracket and the spring is disposed between the bracket first and second ends.  
   
   
       10 . A method for failsafe operation of an exhaust gas recirculation valve, comprising the steps of: 
 providing a valve portion including a valve member engaged with a valve seat;    providing a linear actuator for displacing the valve member, wherein the actuator is powered by a rotary motor;    providing a linear compression spring for exerting a spring force on the valve member;    actuating the linear actuator to displace the valve member from a first position to a second position; and    returning the valve member from the second position to the first position by back driving the rotary motor with the linear compression spring.    
   
   
       11 . The method of  claim 10 , wherein the linear actuator has a thread pitch, and wherein the step of returning the valve member from the second position to the first position by back driving the rotary motor with the linear compression spring further comprises backdriving the rotary motor through the thread pitch.  
   
   
       12 . The method of  claim 10 , wherein the second position corresponds to a closed valve position.  
   
   
       13 . The method of  claim 10 , wherein the step of providing a linear actuator for displacing the valve member includes providing an actuator having an actuator shaft, the rotary motor displacing the shaft to first and second shaft positions corresponding respectively to the shaft being decoupled from the valve member and coupled to the valve member.  
   
   
       14 . The method of  claim 13 , wherein the providing a linear actuator includes providing a disc-shaped element disposed at the end of the shaft.  
   
   
       15 . The method of  claim 13 , wherein the actuating step includes measuring a displacement of the shaft.  
   
   
       16 . The method of  claim 15 , wherein the contacting step includes detecting an absence of displacement of the shaft.  
   
   
       17 . The method of  claim 16 , wherein the detecting an absence of displacement for a period of 100 milliseconds.  
   
   
       18 . The method of  claim 13 , wherein the actuator includes a sensor for determining the position of the shaft and the actuator includes a rotation-to-displacement coupling between the shaft and the motor's rotor.  
   
   
       19 . The method of  claim 13 , wherein the motor has an axis of rotation and the valve portion includes a stem having a longitudinal axis that is substantially parallel to the axis of rotation, the stem having a first end that is fixed to the valve member and a second end adapted for being in contact with the shaft.  
   
   
       20 . The method of  claim 13 , wherein the shaft is decoupled from the spring.