Metering valve for a metered dose inhaler having improved flow
First Claim
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1. An aerosol metering valve comprising:
- a body wall defining an internal chamber and comprising a metering gasket and a diaphragm, the diaphragm having walls defining an aperture;
a valve stem comprising a body portion and a stem portion, the body portion comprising a bottom edge and being positioned in the internal chamber of the metering valve, the stem portion comprising a discharge outlet and passing through the aperture in slidable, sealing engagement with the diaphragm;
an annular gap comprising an inlet and having a length of about 3.2 mm or less, wherein the length of the annular gap is defined by the distance from the bottom edge of the body portion of the valve stem to the inlet; and
a flow path providing at least transient fluid communication between the internal chamber and the annular gap through the inlet.
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Abstract
A novel metering valve having improved flow for delivery of an aerosol formulation is disclosed. Methods of improving the flow characteristics of a metering valve are also disclosed.
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Citations
34 Claims
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1. An aerosol metering valve comprising:
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a body wall defining an internal chamber and comprising a metering gasket and a diaphragm, the diaphragm having walls defining an aperture;
a valve stem comprising a body portion and a stem portion, the body portion comprising a bottom edge and being positioned in the internal chamber of the metering valve, the stem portion comprising a discharge outlet and passing through the aperture in slidable, sealing engagement with the diaphragm;
an annular gap comprising an inlet and having a length of about 3.2 mm or less, wherein the length of the annular gap is defined by the distance from the bottom edge of the body portion of the valve stem to the inlet; and
a flow path providing at least transient fluid communication between the internal chamber and the annular gap through the inlet. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An aerosol metering valve comprising:
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a body wall defining an internal chamber and comprising a metering gasket and a diaphragm, the diaphragm having walls defining an aperture;
a valve stem comprising a body portion and a stem portion, the body portion comprising a bottom edge and being positioned in the internal chamber of the metering valve, the stem portion comprising a discharge outlet and passing through the aperture in slidable, sealing engagement with the diaphragm;
an annular gap comprising an inlet and having a width defined by the distance from the body wall to the valve stem, and also having a length defined by the distance from the inlet to the bottom edge of the body portion of the valve stem, and wherein a ratio of the length of the annular gap to the width of the annular gap is less than about 40;
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a flow path providing at least transient fluid communication between the internal chamber and the annular gap through the inlet. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 20, 21, 22, 23, 24, 25, 26, 27, 28, 30, 31)
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19. An aerosol metering valve comprising:
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a body wall defining an internal chamber and comprising a metering gasket and a diaphragm, the diaphragm having walls defining an aperture;
a valve stem comprising a body portion and a stem portion, the body portion comprising a bottom edge and being positioned in the internal chamber of the metering valve, the stem portion comprising a discharge outlet and passing through the aperture in slidable, sealing engagement with the diaphragm;
an annular gap comprising an inlet and having a width defined by the distance from the body wall to the valve stem, and also having a length of about 3.2 mm or less, defined by the distance from the inlet to the bottom edge of the body portion of the valve stem, wherein a ratio of the length of the annular gap to the width of the annular gap is less than about 320;
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a flow path providing at least transient fluid communication between the internal chamber and the annular gap through the inlet.
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29. A method of improving flow of an aerosol formulation in a metering valve comprising:
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a) providing a metering valve comprising i) a body wall defining an internal chamber and comprising a metering gasket and a diaphragm, the diaphragm having walls defining an aperture, ii) a valve stem comprising a body portion and a stem portion, the body portion comprising a bottom edge and being positioned in the internal chamber of the metering valve, the stem portion comprising a discharge outlet and passing through the aperture in slidable, sealing engagement with the diaphragm, iii) an annular gap comprising an inlet and having an original length defined by the distance from the inlet to the bottom edge of the body portion of the valve stem, and iv) a flow path providing at least transient fluid communication between the internal chamber and the annular gap; and
b) reconfiguring the inlet, the bottom edge of the body portion of the valve stem, or both so that a new length of the annular gap is defined by the distance from the inlet to the bottom edge of the body portion of the valve stem after the reconfiguring;
wherein the new length of the annular gap is less than the original length of the annular gap.
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32. A method of improving flow of aerosol formulation in a metering valve comprising:
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a) providing a metering valve comprising i) a body wall defining an internal chamber and comprising a metering gasket and a diaphragm, the diaphragm having walls defining an aperture, ii) a valve stem comprising a body portion and a stem portion, the body portion comprising a bottom edge and being positioned in the internal chamber of the metering valve in slidable, sealing engagement with the metering gasket, the stem portion comprising a discharge outlet and passing through the aperture in slidable, sealing engagement with the diaphragm, iii) an annular gap comprising an inlet and having a length defined by the distance from the inlet to the bottom edge of the body portion of the valve stem, and iv) a flow path providing at least transient fluid communication between the internal chamber and the annular gap through the inlet;
b) reconfiguring the metering valve to change one or more variables in the formula;
wherein;
P=pressure drop, L=length of the annulus [m], Q=volumetric flow rate [m3/s], μ
=fluid viscosity [kg/m·
s],f=average annulus utilization [0-1], h=distance between the inner and outer wall of the annulus [m], R=inner radius of the annulus [m], ρ
=density of the formulation [kg/m3], andK=entrance loss coefficient, so that flow of formulation is improved. - View Dependent Claims (33, 34)
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Specification