An exemplary controller includes a control valve that includes an electric actuator operatively coupled to a valve stem, a piston operatively coupled to one or more hydraulic fluid paths controlled by the control valve and including a piston shaft, a rotatable shaft operatively coupled to the piston shaft and mechanically isolated from the valve stem and capable of adjusting geometry of the variable geometry turbine, and an electronic sensor capable of sensing an angular position of the rotatable shaft. Various other exemplary systems, methods, devices, etc., are also disclosed.
1. A control system for a variable geometry turbine comprising:
a control valve that includes an electric actuator operatively coupled to a valve stem;
a piston operatively coupled to one or more hydraulic fluid paths controlled by the control valve and including a piston shaft;
a rotatable shaft operatively coupled to the piston shaft and mechanically isolated from the valve stem and capable of adjusting geometry of the variable geometry turbine; and
an electronic sensor capable of sensing an angular position of the rotatable shaft.
2. The control system of claim 1 , wherein the control valve is suitable for use in controlling cam timing of an internal combustion engine.
3. The control system of claim 1 , wherein the electronic sensor includes a resonator circuit.
4. The control system of claim 3 , wherein a rotation of the rotatable shaft causes rotation of the resonator circuit.
5. The control system of claim 1 , wherein a closed control loop exists between a control signal provided to the control valve and an output signal of the electronic sensor.
6. The control system of claim 5 , wherein the closed control loop relies on one or more parameters related to operating conditions of an internal combustion engine.
7. The control system of claim 1 , wherein the electric actuator actuates the valve stem based at least in part on a pulse width modulated signal.
8. The control system of claim 7 , wherein the pulse width modulate signal has a frequency in a range from approximately 80 Hz to approximately 150 Hz.
9. The control system of claim 7 , wherein the pulse width modulated signal reduces static friction of the valve stem.
10. A method for controlling a variable geometry turbine comprising:
providing a pulse width modulated signal to a control valve having a valve stem;
in response to the providing, moving the valve stem;
in response to the moving, flowing hydraulic fluid;
in response to the flowing, translating a piston;
in response to the translating, rotating a crank shaft wherein the crank shaft is mechanically isolated from the valve stem;
in response to the rotating, adjusting one or more geometry elements of the variable geometry turbine; and
determining geometry based at least in part on angular position of the crank shaft.
11. The method of claim 10 , wherein the moving depends on a duty cycle of the pulse width modulated signal.
12. The method of claim 10 , wherein the providing provides a signal having a frequency in a range from approximately 80 Hz to approximately 150 Hz.
13. The method of claim 10 , wherein the determining includes receiving one or more signals from a resonator circuit that rotates in response to the rotating.
14. The method of claim 13 , wherein at least one of the one or more signals varies as a sinusoid.