Viscosity-insensitive mechanical fluid flow regulator
First Claim
1. A fluid flow regulator comprising:
- a housing defining a channel for transporting a flowing fluid from an inlet where the fluid is at an inlet fluid pressure to an outlet where the fluid is at an outlet fluid pressure that is less than the inlet fluid pressure;
the housing'"'"'s channel having a first constricted region restricting fluid flow between its inlet and its outlet, across which fluid-flow-restricting constricted region the fluid pressure incurs a first pressure drop;
the housing'"'"'s channel having a second constricted region restricting fluid flow between its inlet and its outlet, across which fluid-flow-restricting constricted region the fluid pressure incurs a second pressure drop;
the sum of the first pressure drop and the second pressure drop substantially totaling a pressure drop between the inlet fluid pressure and the outlet fluid pressure;
a differential pressure sensor, located within the housing'"'"'s channel so as to experience the first pressure drop across the channel'"'"'s first constricted region, the differential pressure sensor moving in response to the first pressure drop;
wherein the differential pressure sensor is, because of its movement relative to the flowing fluid, at least slightly sensitive in such movement to fluid friction and thus to changes in fluid friction caused by changes in fluid viscosity;
a flow obstructor mechanically connected to the differential pressure sensor for moving therewith in order to variably occlude the housing'"'"'s channel at its second constricted region;
wherein the flow obstructor is, because of its movement to obstruct the fluid flow at the channel'"'"'s second constricted region, sensitive in such movement to fluid friction and thus to changes in fluid friction caused by changes in fluid viscosity;
a force basing means, operating between the housing and both of the mechanically-connected pressure sensor and flow obstructor, for biasing with a constant force (i) the differential pressure sensor against its movement in response to the first pressure drop, and (ii) the flow obstructor in a direction so as to less substantially obstruct the channel'"'"'s second constricted region, therein to more substantially flow fluid therethrough this second constricted region at a lower second pressure drop;
wherein because the total fluid pressure drop from inlet to outlet is the sum of the first and the second pressure drops, then the movement of the flow obstructor under force of the force biasing means in the direction so as to lower the second pressure drop correspondingly raises the fist pressure drop, therein serving to move the differential pressure sensor against the biasing force in response to this raised first pressure drop until an equilibrium is reached;
wherein at equilibrium a force on the differential pressure sensor resultant from the first pressure drop will be constant, and equal to the constant force of the force biasing means minus a frictional force of the flowing fluid against the flow obstructor;
the mechanical connection of the flow obstructor to the differential pressure sensor being so that an increased fluid frictional drag force on the flow obstructor where it moves to variably occlude the housing'"'"'s channel at its second constricted region acts mechanically oppositely to a change in static differential pressure on the pressure sensor due to the same increase in fluid frictional drag force, the mechanically oppositely-acting forces tending to cancel each other.
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Accused Products
Abstract
The differential-pressure-sensing and variable-area-occluding fundtions within variable-area flowmeters and flow regulators are performed by separate, but mechanically connected, elements. A housing defines a channel for guiding fluid flow from an upstream to a downstream location. A differential pressure sensor moves in a direction substantially perpendicular to the direction of fluid flow in response to a differential fluid pressure between the upstream and downstream locations. Because the movement of the pressure sensor is substantially perpendicular to the flowing fluid with which it comes in contact, it is substantially insensitive to fluid friction and to changes in fluid viscosity. A flow obstructor connects to the sensor and moves therewith to variably obstruct the channel and its flow of fluid from the upstream to the downstream location. Fluid frictional forces on the movement of the flow obstructor vary with changes in fluid viscosity. However the ratio of the area of the flow obstructor to the area of the pressure sensor, which ratio substantially equals the ratio of the fluid frictional forces to the pressure force, is consistently low, typically 1:100. Consequently the overall flowmeter or flow regulator is relatively insensitive to changes in fluid viscosity. It typically exhibits less than ±1% deviation in an indicated, or regulated, flow rate for variations in fluid viscosity on the order of ×20.
30 Citations
23 Claims
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1. A fluid flow regulator comprising:
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a housing defining a channel for transporting a flowing fluid from an inlet where the fluid is at an inlet fluid pressure to an outlet where the fluid is at an outlet fluid pressure that is less than the inlet fluid pressure; the housing'"'"'s channel having a first constricted region restricting fluid flow between its inlet and its outlet, across which fluid-flow-restricting constricted region the fluid pressure incurs a first pressure drop; the housing'"'"'s channel having a second constricted region restricting fluid flow between its inlet and its outlet, across which fluid-flow-restricting constricted region the fluid pressure incurs a second pressure drop; the sum of the first pressure drop and the second pressure drop substantially totaling a pressure drop between the inlet fluid pressure and the outlet fluid pressure; a differential pressure sensor, located within the housing'"'"'s channel so as to experience the first pressure drop across the channel'"'"'s first constricted region, the differential pressure sensor moving in response to the first pressure drop; wherein the differential pressure sensor is, because of its movement relative to the flowing fluid, at least slightly sensitive in such movement to fluid friction and thus to changes in fluid friction caused by changes in fluid viscosity; a flow obstructor mechanically connected to the differential pressure sensor for moving therewith in order to variably occlude the housing'"'"'s channel at its second constricted region; wherein the flow obstructor is, because of its movement to obstruct the fluid flow at the channel'"'"'s second constricted region, sensitive in such movement to fluid friction and thus to changes in fluid friction caused by changes in fluid viscosity; a force basing means, operating between the housing and both of the mechanically-connected pressure sensor and flow obstructor, for biasing with a constant force (i) the differential pressure sensor against its movement in response to the first pressure drop, and (ii) the flow obstructor in a direction so as to less substantially obstruct the channel'"'"'s second constricted region, therein to more substantially flow fluid therethrough this second constricted region at a lower second pressure drop; wherein because the total fluid pressure drop from inlet to outlet is the sum of the first and the second pressure drops, then the movement of the flow obstructor under force of the force biasing means in the direction so as to lower the second pressure drop correspondingly raises the fist pressure drop, therein serving to move the differential pressure sensor against the biasing force in response to this raised first pressure drop until an equilibrium is reached; wherein at equilibrium a force on the differential pressure sensor resultant from the first pressure drop will be constant, and equal to the constant force of the force biasing means minus a frictional force of the flowing fluid against the flow obstructor; the mechanical connection of the flow obstructor to the differential pressure sensor being so that an increased fluid frictional drag force on the flow obstructor where it moves to variably occlude the housing'"'"'s channel at its second constricted region acts mechanically oppositely to a change in static differential pressure on the pressure sensor due to the same increase in fluid frictional drag force, the mechanically oppositely-acting forces tending to cancel each other. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A fluid flow regulator comprising:
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a housing defining a channel for flowing fluid in a flow direction from an inlet where the fluid is at an inlet fluid pressure past, in either order, (i) a flow-controlling location where the cross-sectional area of fluid flow is variably occluded and across which the fluid undergoes a variable first pressure drop, and (ii) a flow-restricting location where the cross-sectional area of fluid flow i constricted to a constant area and across which the fluid undergoes a second pressure drop, to an outlet port where the fluid is the outlet pressure; a differential pressure sensing means, located between flow-connections to the flowing fluid at locations upstream and downstream of the channel'"'"'s flow-restricting location, for moving in response to the second pressure drop; wherein the differential pressure sensing means is, because of its movement relative to the flowing fluid, at least slightly sensitive in such movement to fluid friction and thus to changes in fluid friction caused by changes in fluid viscosity; a force biasing means, connected between the differential pressure sensing means and the housing, for force-biasing with a constant force the movement of the differential pressure sensing means in a direction against the pressure force of the second pressure drop; and a flow control means, responsive to the differential pressure sensing means for moving in accordance therewith, for moving relative to the channel'"'"'s flow-controlling location to variably occlude the channel at this flow-controlling location, therein to variably determine the first pressure drop; wherein the flow control means is, because of its movement to obstruct the fluid flow at the channel'"'"'s second constricted region, sensitive in such movement to fluid friction and thus to changes in fluid friction caused by changes in fluid viscosity; wherein the sense of a coupling of movement between the flow control means and the differential pressure sensing means, and a sense of the variably-occluded fluid flow and variably-determined pressure drop resultant therefrom, is so as to make that the variable first pressure drop controlled by action of the flow control means will always be so as to produce a downstream pressure that is fixed relative to the outlet pressure, which downstream pressure drop is determined in its magnitude by the constant force of the force biasing means substantially regardless of changes in the inlet fluid pressure over an operational range; wherein because the second pressure drop is maintained constant across the channel'"'"'s flow=-restricting location of constant area, the rate of fluid flow through this flow-restricted location and out the channel'"'"'s outlet port is regulated to be constant substantially regardless of changes in the output pressure; the mechanical connection of the flow obstructor to the differential pressure sensor being so that an increased fluid frictional drag force on the flow obstructor where it moves to variably occlude the housing'"'"'s channel at its second constricted region acts mechanically oppositely to a change in static differential pressure on the pressure sensor due to the same increase in fluid frictional drag force, the mechanically oppositely-acting forces tending to cancel each other. - View Dependent Claims (20, 21, 22, 23)
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Specification