Variable orifice flow sensing apparatus

An obstruction assembly for a flow sensing apparatus used to measure a fluid flow in a channel, comprising:

• a secured element outside the channel fixed relative to said flow sensing apparatus;
• an elastically flexible, substantially planar flow obstruction element configured such that a substantial portion of the periphery of said obstruction element is disposed proximal to the periphery of said channel when no fluid is flowing through said channel;
• and
• a hinge element hingeably connecting said secured element to said obstruction element.

A flow sensing apparatus, comprising:

• a housing having an upstream half and a downstream half such that said housing includes a channel therethrough;
• said upstream half having an inlet port coaxially to and fluidly connected to an outlet port;
• said inlet port of said upstream half including a centrally disposed target within said channel such that said target is secured to said housing by a plurality of radial spokes;
• said downstream half having an inlet port coaxially to and fluidly connected to an outlet port;
• said outlet port of said upstream half slidably engaging said inlet port of said downstream half;
• said outlet port of said upstream half having a planar male mating surface disposed at and perpendicular to said outlet port;
• said male mating surface having an annular ridge encircling said outlet port;
• said annular ridge having a radial tab disposed above of said outlet port;
• said inlet port of said downstream half having a planar female mating surface disposed at and perpendicular to said inlet port;
• said female mating surface having an annular recess encompassing said inlet port and sized to slidably receive said annular ridge;
• said annular recess having a radial notch sized to receive said radial tab;
• said radial notch disposed above said inlet port of said downstream half;
• an obstruction assembly having a secured element forming an annular ring sized to be received in said annular recess;
• an obstruction element disposed in said inlet port of said downstream half;
• a hinge element extending through said radial notch and hingeably connecting said secured element to said obstruction element;
• said upstream half having an upstream pressuring sensing port disposed between said inlet port and said outlet port in fluid communication with said upstream half inlet port and outlet port;
• and
• said downstream half having a downstream pressure sensing port disposed between said inlet port and said outlet port in fluid communication with said downstream half inlet port and outlet port.

A flow sensing apparatus for providing a relatively high pressure differential at low flow rates, and a relatively low pressure differential at high flow rates, and a reduced area permanently perpendicular to the fluid flow so as to reduce collection of contaminants, comprising:

• a housing having a channel therethrough, said channel defining a channel flow area, said channel having a periphery, said channel commencing at an inlet port and terminating at an outlet port;
• and
• an obstruction assembly disposed between said inlet port and said outlet port, said obstruction assembly including:
• a secured element fixed within said housing externally of said channel;
• an obstruction element disposed within said channel and sized to substantially occlude said channel when there is no fluid flow through said channel and to provide a periphery which is spaced from said channel periphery so as to define a static flow area where no fluid is flowing through said channel and a dynamic flow area larger than said static flow area when fluid is flowing through said channel such that said dynamic flow area may increase as the flow rate through said channel increases to be approximately equal to said channel flow area thereby providing a turndown ratio greater than the turndown ratio of a fixed orifice;
• and
• a hinge element extending substantially less than completely about said channel periphery, and hingeably connecting said secured element to said obstruction element.

A flow sensing apparatus for medical ventilators comprising:

• a housing having an inlet port and an outlet port;
• means for providing fluid communication between said inlet port and said outlet port;
• an obstruction assembly means disposed between said inlet port and said outlet port for providing a high turndown ratio pressure differential between said inlet port and said outlet port;
• a ridge disposed within said housing adjacent to said obstruction assembly;
• means for securing said obstruction assembly in a predetermined orientation within said housing;
• and
• means for reducing pressure waves within a flow stream within said fluid communication means.

A flow sensing apparatus for medical ventilators comprising:

• a housing having an inlet port and an outlet port;
• means for providing fluid communication between said inlet port and said outlet port;
• an obstruction assembly means disposed between said inlet port and said outlet port for providing a high turndown ratio pressure differential between said inlet port and said outlet port;
• a ridge disposed within said housing adjacent to said obstruction assembly;
• means for securing said obstruction assembly in a predetermined orientation within said housing;
• a target assembly including:
• a target element centrally disposed within said fluid communications means;
• and
• a plurality of spokes radially extending from said target element of said housing.

A flow sensing apparatus for medical ventilators comprising:

• a housing having an inlet port and an outlet port;
• an obstruction assembly means disposed between said inlet port and said outlet port for providing a high turndown ratio pressure differential between said inlet port and said outlet port;
• a ridge disposed within said housing;
• means for securing said obstruction assembly in a predetermined orientation within said housing:
• means for providing fluid communication between said inlet port and said outlet port, said means including a channel having a periphery which includes an arcuate portion such that said ridge is disposed on said arcuate portion proximal to said obstruction assembly when no fluid flow is flowing through said channel;
• and
• means for reducing pressure waves within a flow stream within said fluid communication means.

An obstruction assembly for a flow sensing apparatus wherein said flow sensing apparatus is configured to be secured with respect to a fluid flow in a channel, comprising:

• a secured element fixed with respect to said apparatus;
• an elastically flexible, substantially planar flow obstruction element connected to a hinge element on the periphery of said obstruction element, the remainder of said obstruction element configured to substantially occlude said channel when no fluid is flowing through said channel;
• said hinge element hingeably connecting said secured element to said obstruction element, said hinge element extending substantially perpendicular from said secured element, wherein said obstruction assembly includes
• an arcuate recess proximal to each connection of said hinge element and said obstruction element.

A flow sensing apparatus for providing a relatively high pressure differential at low flowrates, a relatively low pressure differential at high flowrates, and a reduced area permanently perpendicular to the fluid flow, comprising:

• a housing having a channel therethrough defining a periphery, said channel commencing at an inlet port and terminating at an outlet port;
• and
• an obstruction assembly disposed between said inlet port and said outlet port, said obstruction assembly including:
• a secured element fixed within said housing externally of said channel;
• an obstruction element within said channel and having a periphery which is spaced from said channel so as to define a static flow area when no fluid is flowing through said channel and a dynamic flow area larger than said static flow area when the fluid flowrate through said channel is greater than a predetermined velocity, wherein said obstruction element includes a plurality of spaced, parallel, vertical slots;
• and
• a hinge element extending substantially less than completely about said channel periphery, and hingeably connecting said secured element to said obstruction element.

An obstruction assembly for a flow sensing apparatus, used to measure a fluid flow in a channel, comprising:

• a secured element fixed relative to said flow sensing apparatus;
• an elastically flexible, substantially planar flow obstruction element configured such that a substantial portion of the periphery of said obstruction element is disposed proximal to the periphery of said channel when no fluid is flowing through the channel, said obstruction element including a plurality of spaced parallel slots;
• and
• a hinge element hingeably connecting said secured element to said obstruction element.