Ventilator exhalation flow valve
View Patent ↗Described herein is an exhalation valve for a ventilator that controls gas flow through a patient exhalation line in response to a target pressure within the line. The valve controls gas flow by (i) providing both a high frequency signal and a low frequency signal through a coil positioned in a fixed magnetic field, (ii) determining a position of the coil by detecting the high frequency signal, and (iii) controlling a position of the coil by adjusting the low frequency signal.
1. A valve comprising:
a valve orifice with an adjustable opening;
a fixed magnetic field;
a force coil configured to be moved within the fixed magnetic field in response to a low frequency current;
a current amplifier configured to direct a summed current comprising the low frequency current and a high frequency current into the force coil;
a feedback coil configured to detect the high frequency current in the force coil, the detected high frequency current having a magnitude that is proportional to a force coil position within the fixed magnetic field;
a processor configured (i) to receive data relating to the position of the force coil and (ii) to send instructions to the current amplifier; and
a diaphragm configured to adjust the valve orifice opening based on the position of the force coil.
2. The valve of claim 1 , wherein the processor is further configured to receive data relating to the velocity of the force coil, and the valve further comprises:
a position circuit configured to receive a signal from the feedback coil and to direct data to the processor relating to the force coil position; and
a velocity circuit configured to determine a velocity of the force coil and to direct data to the processor relating to the velocity of the force coil.
3. The valve of claim 1 , wherein the feedback coil is mounted outside of the fixed magnetic field.
4. The valve of claim 1 , wherein the fixed magnetic field is generated by at least one permanent magnet.
5. The valve of claim 1 , wherein the instructions to the current amplifier are configured to adjust the low frequency current directed to the force coil.
6. The valve of claim 1 , wherein the instructions to the current amplifier are configured to adjust the position of the force coil.
7. The valve of claim 1 , wherein the current amplifier comprises a linear current output amplifier.
8. The valve of claim 1 , wherein the valve is configured to be positioned along an exhalation pathway of a ventilator to adjust pressure within the exhalation pathway.
9. The valve of claim 8 , wherein the processor is configured to receive data relating to the exhalation pathway pressure and to direct the current amplifier to adjust the position of the force coil based on the pressure.
10. The valve of claim 9 , wherein the processor is configured to direct the current amplifier to close the valve orifice opening when the pressure drops below a threshold pressure.
11. The valve of claim 10 , wherein the threshold pressure is above an ambient pressure.