| 摘要 |
A variable orifice pulse valve has a small internal volume for providing small, accurately measured pulse volumes of gas. The valve may be employed to supply a very small quantity of a therapeutic gas or a diagnostic gas into the breathing gases of a patient. The valve has a housing with an inlet for receiving the gas and an outlet providing the pulsatile discharge of the gas. A chamber, formed in the housing, has a first opening in fluid communication with the inlet and a second opening in fluid communication with the outlet. The intermediate chamber is formed to have a small volume compared to the minimum pulsatile gas discharge volume of the valve. A spring biases a variable orifice member toward the first opening and a solenoid moves the variable orifice member away from the first opening to form an orifice that meters a dose of gas into the valve. A sealing member is spring biased into sealing engagement with the second opening. A second control solenoid operates to move the second sealing member out of engagement with the second opening to form a pulse orifice in the valve that provides the pulsatile discharge of gas from the outlet. An outlet chamber of the valve may include a further inlet providing a carrier gas that sweeps the gas pulse exiting from the intermediate chamber out of the valve to prevent the gas pulse from being trapped in the valve. |
