Flow control system

Claim 1

A device for regulating the flow of fluid from an environment, the environment having a pressure less than the ambient pressure, to an evacuation means, the device comprising: a path, through which the fluid passes from an input in fluid communication with the environment to an output in fluid communication with the evacuation means, the path not being vented at any point between the input and the output, so that the mass of fluid exiting the device through the output is substantially equal to the mass of fluid entering the device from the input; a piston movably mounted to a piston mounting structure, the piston being so mounted that it may constrict the path at a constriction point, and so that it may move in a direction transverse to the path at the constriction point, the piston having (i) a distal face exposed to a reference pressure, (ii) a frontal face directly across which the fluid flows and which is located in the path on the environment side of the constriction point, wherein the distal and frontal faces have approximately the same area; and restoring means, including the weight of the piston, for exerting a force on the piston in a direction that tends to move the piston so as to widen the path at the constriction point; so that the force exerted on the piston by the pressure of the fluid in the path on the evacuation means side of the constriction point is transverse to the direction of movement of the piston, and the forces exerted on the piston by the reference pressure, the pressure of the fluid in the path on the environment side of the constriction point, and the restoring means are generally parallel to the direction of movement of the piston.

Claim 2

A device for regulating the flow of fluid from an environment, the environment having a pressure less than the ambient pressure, to an evacuation means, the device comprising: a path, through which the fluid passes from an input in fluid communication with the environment to an output in fluid communication with the evacuation means, the path not being vented at any point between the input and the output, so that the mass of fluid exiting the device through the output is substantially equal to the mass of fluid entering the device from the input; a piston movably mounted to a piston mounting structure, the piston being so mounted that it may constrict the path at a constriction point, and so that it may move in a direction transverse to the path at the constriction point, the piston having (i) a distal face exposed to a reference pressure, (ii) a frontal face directly across which the fluid flows and which is located in the path on the environment side of the constriction point, wherein the distal and frontal faces have approximately the same area; and restoring means, including the weight of the piston, for exerting a force on the piston in a direction that tends to move the piston so as to widen the path at the constriction point; so that the force exerted on the piston by the pressure of the fluid in the path on the evacuation means side of the constriction point is transverse to the direction of movement of the piston, and the forces exerted on the piston by the reference pressure, the pressure of the fluid in the path on the environment side of the constriction point, and the restoring means are generally parallel to the direction of movement of the piston.

Claim 5

A device for regulating the flow of fluid from an environment, the environment having a pressure less than the ambient pressure, to an evacuation means, the device comprising: a path, through which the fluid passes from an input in fluid communication with the environment to an output in fluid communication with the evacuation means, the path not being vented at any point between the input and the output, so that the mass of fluid exiting the device through the output is substantially equal to the mass of fluid entering the device from the input; a piston movably mounted to a piston mounting structure, the piston being so mounted that it may constrict the path at a constriction point, and so that it may move in a direction transverse to the path at the constriction point, the piston having (i) a distal face exposed to a reference pressure, (ii) a frontal face exposed to the fluid in the path on the environment side of the constriction point; and restoring means, for exerting a force on the piston in a direction that tends to move the piston so as to widen the path at the constriction point; so that the force exerted on the piston by the pressure of the fluid in the path on the evacuation means side of the constriction point is transverse to the direction of movement of the piston, and the forces exerted on the piston by the reference pressure, the pressure of the fluid in the path on the environment side of the constriction point, and the restoring means are generally parallel to the direction of movement of the piston, wherein the piston includes a flexible diaphragm that may protrude into the path at the constriction point and that has a movable internal wall attached to the piston and a movable external wall attached to the piston mounting structure, wherein the lengths of the movable walls can vary as the piston moves.

Claim 6

A device for regulating the flow of fluid from an environment, the environment having a pressure less than the ambient pressure, to an evacuation means, the device comprising: a path, through which the fluid passes from an input in fluid communication with the environment to an output in fluid communication with the evacuation means, the path not being vented at any point between the input and the output, so that the mass of fluid exiting the device through the output is substantially equal to the mass of fluid entering the device from the input; a piston movably mounted to a piston mounting structure, the piston being so mounted that it may constrict the path at a constriction point, and so that it may move in a direction transverse to the path at the constriction point, the piston having (i) a distal face exposed to a reference pressure, (ii) a frontal face exposed to the fluid in the path on the environment side of the constriction point; and restoring means, for exerting a force on the piston in a direction that tends to move the piston so as to widen the path at the constriction point; so that the force exerted on the piston by the pressure of the fluid in the path on the evacuation means side of the constriction point is transverse to the direction of movement of the piston, and the forces exerted on the piston by the reference pressure, the pressure of the fluid in the path on the environment side of the constriction point, and the restoring means are generally parallel to the direction of movement of the piston, wherein the piston includes a flexible diaphragm that may protrude into the path at the constriction point and that has a movable internal wall attached to the piston and a movable external wall attached to the piston mounting structure, wherein the lengths of the movable walls can vary as the piston moves.

Claim 14

A device for regulating the flow of fluid from an environment, the environment having a pressure less than the ambient pressure, to an evacuation means, the device comprising: a path, through which the fluid passes from an input in fluid communication with the environment to an output in fluid communication with the evacuation means, the path not being vented at any point between the input and the output, so that the mass of fluid exiting the device through the output is substantially equal to the mass of fluid entering the device from the input; a piston movably mounted to a piston mounting structure, the piston being so mounted that it may constrict the path at a constriction point, and so that it may move in a direction transverse to the path at the constriction point, the piston having (i) a distal face exposed to a reference pressure, (ii) a frontal face exposed to the fluid in the path on the environment side of the constriction point; restoring means, including the weight of the piston, for exerting a force on the piston in a direction that tends to move the piston so as to widen the path at the constriction point; and a throttling valve means disposed in the path between the environment and the piston, for constricting the path, such that a substantially constant fluid mass flow rate through the device may be maintained, wherein the throttling valve means is adjustable so that the amount that the path is constricted between the environment and the piston may be changed; so that the force exerted on the piston by the pressure of the fluid in the path on the evacuation means side of the constriction point is transverse to the direction of movement of the piston, and the forces exerted on the piston by the reference pressure, the pressure of the fluid in the path on the environment side of the constriction point, and the restoring means are generally parallel to the direction of movement of the piston.

Claim 15

A device for regulating the flow of fluid from an environment, the environment having a pressure less than the ambient pressure, to an evacuation means, the device comprising: a path, through which the fluid passes from an input in fluid communication with the environment to an output in fluid communication with the evacuation means, the path not being vented at any point between the input and the output, so that the mass of fluid exiting the device through the output is substantially equal to the mass of fluid entering the device from the input; a piston movably mounted to a piston mounting structure, the piston being so mounted that it may constrict the path at a constriction point, and so that it may move in a direction transverse to the path at the constriction point, the piston having (i) a distal face exposed to a reference pressure, (ii) a frontal face exposed to the fluid in the path on the environment side of the constriction point; restoring means, including the weight of the piston, for exerting a force on the piston in a direction that tends to move the piston so as to widen the path at the constriction point; and a throttling valve means disposed in the path between the environment and the piston, for constricting the path, such that a substantially constant fluid mass flow rate through the device may be maintained, wherein the throttling valve means is adjustable so that the amount that the path is constricted between the environment and the piston may be changed; so that the force exerted on the piston by the pressure of the fluid in the path on the evacuation means side of the constriction point is transverse to the direction of movement of the piston, and the forces exerted on the piston by the reference pressure, the pressure of the fluid in the path on the environment side of the constriction point, and the restoring means are generally parallel to the direction of movement of the piston.

Claim 20

A device for regulating the flow of fluid from an environment, the environment having a pressure less than the ambient pressure, to an evacuation means, the device comprising: a path, through which the fluid passes from an input in fluid communication with the environment to an output in fluid communication with the evacuation means, the path not being vented at any point between the input and the output, so that the mass of fluid exiting the device through the output is substantially equal to the mass of fluid entering the device from the input; a piston movably mounted to a piston mounting structure, the piston being so mounted that it may constrict the path at a constriction point, and so that it may move in a direction transverse to the path at the constriction point, the piston having (i) a distal face exposed to a reference pressure, (ii) a frontal face exposed to the fluid in the path on the environment side of the constriction point; restoring means, for exerting a force on the piston in a direction that tends to move the piston so as to widen the path at the constriction point; and a ferrofluid forming a seal between the piston and the piston mounting structure, and a magnet, mounted on either of the piston or the piston mounting structure, for holding the ferrofluid in a position to form a seal between the piston and the piston mounting structure; so that the force exerted on the piston by the pressure of the fluid in the path on the evacuation means side of the constriction point is transverse to the direction of movement of the piston, and the forces exerted on the piston by the reference pressure, the pressure of the fluid in the path on the environment side of the constriction point, and the restoring means are generally parallel to the direction of movement of the piston.

Claim 21

A device for regulating the flow of fluid from an environment, the environment having a pressure less than the ambient pressure, to an evacuation means, the device comprising: a path, through which the fluid passes from an input in fluid communication with the environment to an output in fluid communication with the evacuation means, the path not being vented at any point between the input and the output, so that the mass of fluid exiting the device through the output is substantially equal to the mass of fluid entering the device from the input; a piston movably mounted to a piston mounting structure, the piston being so mounted that it may constrict the path at a constriction point, and so that it may move in a direction transverse to the path at the constriction point, the piston having (i) a distal face exposed to a reference pressure, (ii) a frontal face exposed to the fluid in the path on the environment side of the constriction point; restoring means, for exerting a force on the piston in a direction that tends to move the piston so as to widen the path at the constriction point; and a ferrofluid forming a seal between the piston and the piston mounting structure, and a magnet, mounted on either of the piston or the piston mounting structure, for holding the ferrofluid in a position to form a seal between the piston and the piston mounting structure; so that the force exerted on the piston by the pressure of the fluid in the path on the evacuation means side of the constriction point is transverse to the direction of movement of the piston, and the forces exerted on the piston by the reference pressure, the pressure of the fluid in the path on the environment side of the constriction point, and the restoring means are generally parallel to the direction of movement of the piston.

Claim 22

A device for regulating the flow of fluid from an environment, the environment having a pressure less than the ambient pressure, to an evacuation means, the device comprising: a path, through which the fluid passes from an input in fluid communication with the environment to an output in fluid communication with the evacuation means, the path not being vented at any point between the input and the output, so that the mass of fluid exiting the device through the output is substantially equal to the mass of fluid entering the device from the input; a piston movably mounted to a piston mounting structure, the piston being so mounted that it may constrict the path at a constriction point, and so that it may move in a direction transverse to the path at the constriction point, the piston having (i) a distal face exposed to a reference pressure, (ii) a frontal face exposed to the fluid in the path on the environment side of the constriction point, wherein the frontal face of the piston has a central area and a perimeter; restoring means, for exerting a force on the piston in a direction that tends to move the piston so as to widen the path at the constriction point; and a modulator mounted proximate to the piston for redirecting the fluid so that the fluid flows across the frontal face of the piston away from the central area radially outward towards the perimeter, such that the direction of the fluid flow is redirected from a direction that is generally parallel to the direction of movement of the piston to directions that are transverse to the direction of movement of the piston, so that, as the velocity of the fluid moving through the device increases, the force exerted on the frontal face of the piston by the pressure of the fluid in the path decreases, so that the piston tends to move to further constrict the path at the constriction point; so that the force exerted on the piston by the pressure of the fluid in the path on the evacuation means side of the constriction point is transverse to the direction of movement of the piston, and the forces exerted on the piston by the reference pressure, the pressure of the fluid in the path on the environment side of the constriction point, and the restoring means are generally parallel to the direction of movement of the piston.

Claim 23

A device for regulating the flow of fluid from an environment, the environment having a pressure less than the ambient pressure, to an evacuation means, the device comprising: a path, through which the fluid passes from an input in fluid communication with the environment to an output in fluid communication with the evacuation means, the path not being vented at any point between the input and the output, so that the mass of fluid exiting the device through the output is substantially equal to the mass of fluid entering the device from the input; a piston movably mounted to a piston mounting structure, the piston being so mounted that it may constrict the path at a constriction point, and so that it may move in a direction transverse to the path at the constriction point, the piston having (i) a distal face exposed to a reference pressure, (ii) a frontal face exposed to the fluid in the path on the environment side of the constriction point, wherein the frontal face of the piston has a central area and a perimeter; restoring means, for exerting a force on the piston in a direction that tends to move the piston so as to widen the path at the constriction point; and a modulator mounted proximate to the piston for redirecting the fluid so that the fluid flows across the frontal face of the piston away from the central area radially outward towards the perimeter, such that the direction of the fluid flow is redirected from a direction that is generally parallel to the direction of movement of the piston to directions that are transverse to the direction of movement of the piston, so that, as the velocity of the fluid moving through the device increases, the force exerted on the frontal face of the piston by the pressure of the fluid in the path decreases, so that the piston tends to move to further constrict the path at the constriction point; so that the force exerted on the piston by the pressure of the fluid in the path on the evacuation means side of the constriction point is transverse to the direction of movement of the piston, and the forces exerted on the piston by the reference pressure, the pressure of the fluid in the path on the environment side of the constriction point, and the restoring means are generally parallel to the direction of movement of the piston.

Claim 29

A device for regulating the mass flow rate of fluid flowing from an input to an output, the device comprising: a path through which the fluid passes from the input to the output; a venturi disposed in the path; a piston having a frontal face forming part of the venturi and a distal face exposed to a reference pressure, the piston being movably mounted so that as the velocity of the fluid flowing through the path increases the difference between the reference pressure and the pressure in the venturi increases such that the piston tends to move so as to narrow the venturi; and restoring means, including the weight of the piston, for exerting a force on the piston in a direction that tends to move the piston so as to widen the venturi, wherein the piston is hingedly mounted to that the piston rotates about a hinge port in such a manner to alter the width of the venturi, the piston including a slidable wight that may be moved closure towards or further from the hinge point so as decrease or increase the tendency of the piston to widen the venturi.

Claim 30

A device for regulating the mass flow rate of fluid flowing from an input to an output, the device comprising: a path through which the fluid passes from the input to the output; a venturi disposed in the path; a piston having a frontal face forming part of the venturi and a distal face exposed to a reference pressure, the piston being movably mounted so that as the velocity of the fluid flowing through the path increases the difference between the reference pressure and the pressure in the venturi increases such that the piston tends to move so as to narrow the venturi; and restoring means, including the weight of the piston, for exerting a force on the piston in a direction that tends to move the piston so as to widen the venturi, wherein the piston is hingedly mounted to that the piston rotates about a hinge port in such a manner to alter the width of the venturi, the piston including a slidable wight that may be moved closure towards or further from the hinge point so as decrease or increase the tendency of the piston to widen the venturi.

Claim 32

A device for regulating the flow of fluid from an environment, the environment having a pressure less than the ambient pressure, comprising: (i) a manifold including a side wall, an evacuation port disposed in the side wall through which the manifold is in communication with an evacuation means and an environment port through which the manifold is in communication with the environment; (ii) a piston having a frontal face and a distal face, movably mounted in the manifold with the distal face exposed to ambient pressure, the piston being mounted so that it moves in a direction substantially parallel to the side wall and transverse to the evacuation port, and so that a relatively lower pressure in the manifold in comparison to the ambient pressure results in a force on the piston in a direction in which the piston may move across the evacuation port so as to partially occlude the evacuation port, the piston being mounted with respect to the environment port so that the piston does not occlude the environment port; and (iii) restoring means for exerting a force on the piston in a direction which may move the piston so as to tend to open the evacuation port; so that the pressure in the manifold changes, the piston may partially occlude or expose the manifold to the evacuation means, thus ensuring that an approximately constant partial vacuum is maintained with respect to the environment.

Claim 33

A device for regulating the flow of fluid from an environment, the environment having a pressure less than the ambient pressure, comprising: (i) a manifold including a side wall, an evacuation port disposed in the side wall through which the manifold is in communication with an evacuation means and an environment port through which the manifold is in communication with the environment; (ii) a piston having a frontal face and a distal face, movably mounted in the manifold with the distal face exposed to ambient pressure, the piston being mounted so that it moves in a direction substantially parallel to the side wall and transverse to the evacuation port, and so that a relatively lower pressure in the manifold in comparison to the ambient pressure results in a force on the piston in a direction in which the piston may move across the evacuation port so as to partially occlude the evacuation port, the piston being mounted with respect to the environment port so that the piston does not occlude the environment port; and (iii) restoring means for exerting a force on the piston in a direction which may move the piston so as to tend to open the evacuation port; so that the pressure in the manifold changes, the piston may partially occlude or expose the manifold to the evacuation means, thus ensuring that an approximately constant partial vacuum is maintained with respect to the environment.

Claim 34

A device for regulating the flow of fluid from an environment, the environment having a pressure less than the ambient pressure, comprising: (i) a manifold including a side wall, an evacuation port disposed in the side wall through which the manifold is in communication with an evacuation means and an environment port through which the manifold is in communication with the environment; (ii) a piston having a frontal face and a distal face, movably mounted in the manifold with the distal face exposed to ambient pressure, the piston being mounted so that it moves in a direction substantially parallel to the side wall and transverse to the evacuation port, and so that a relatively lower pressure in the manifold in comparison to the ambient pressure results in a force on the piston in a direction in which the piston may move across the evacuation port so as to partially occlude the evacuation port, wherein the piston includes a flexible diaphragm; and (iii) restoring means for exerting force on the piston in a direction which may move the piston so as to tend to open the evacuation port; so that the pressure in the manifold changes, the piston may partially occlude or expose the manifold to the evacuation means, thus ensuring that an approximately constant partial vacuum is maintained with respect to the environment.

Claim 35

A device for regulating the flow of fluid from an environment, the environment having a pressure less than the ambient pressure, comprising: (i) a manifold including a side wall, an evacuation port disposed in the side wall through which the manifold is in communication with an evacuation means and an environment port through which the manifold is in communication with the environment; (ii) a piston having a frontal face and a distal face, movably mounted in the manifold with the distal face exposed to ambient pressure, the piston being mounted so that it moves in a direction substantially parallel to the side wall and transverse to the evacuation port, and so that a relatively lower pressure in the manifold in comparison to the ambient pressure results in a force on the piston in a direction in which the piston may move across the evacuation port so as to partially occlude the evacuation port, wherein the piston includes a flexible diaphragm; and (iii) restoring means for exerting force on the piston in a direction which may move the piston so as to tend to open the evacuation port; so that the pressure in the manifold changes, the piston may partially occlude or expose the manifold to the evacuation means, thus ensuring that an approximately constant partial vacuum is maintained with respect to the environment.

Claim 39

A device for regulating the flow of fluid from an environment, the environment having a pressure less than the ambient pressure, comprising: (i) a manifold including a side wall, an evacuation port disposed in the side wall through which the manifold is in communication with an evacuation means and an environment port through which the manifold is in communication with the environment; (ii) a piston having a frontal face and a distal face, movably mounted in the manifold with the distal face exposed to ambient pressure, the piston being mounted so that it moves in a direction substantially parallel to the side wall and transverse to the evacuation port, and so that a relatively lower pressure in the manifold in comparison to the ambient pressure results in a force on the piston in a direction in which the piston may move across the evacuation port so as to partially occlude the evacuation port; and (iii) restoring means for exerting a force on the piston in a direction which may move the piston so as to tend to open the evacuation port; so that the pressure in the manifold changes, the piston may partially occlude or expose the manifold to the evacuation means, thus ensuring that an approximately constant partial vacuum is maintained with respect to the environment wherein the piston includes a relatively rigid central portion and a flexible diaphragm along the periphery of the piston, and the piston is disposed in the manifold so that the flexible diaphragm forms a peripherally disposed protrusion along the side wall of the manifold, the protrusion having a movable internal and movable external wall whose lengths can vary as the central portion of the diaphragm moves in relation to the periphery.

Claim 40

A device for regulating the flow of fluid from an environment, the environment having a pressure less than the ambient pressure, comprising: (i) a manifold including a side wall, an evacuation port disposed in the side wall through which the manifold is in communication with an evacuation means and an environment port through which the manifold is in communication with the environment; (ii) a piston having a frontal face and a distal face, movably mounted in the manifold with the distal face exposed to ambient pressure, the piston being mounted so that it moves in a direction substantially parallel to the side wall and transverse to the evacuation port, and so that a relatively lower pressure in the manifold in comparison to the ambient pressure results in a force on the piston in a direction in which the piston may move across the evacuation port so as to partially occlude the evacuation port; and (iii) restoring means for exerting a force on the piston in a direction which may move the piston so as to tend to open the evacuation port; so that the pressure in the manifold changes, the piston may partially occlude or expose the manifold to the evacuation means, thus ensuring that an approximately constant partial vacuum is maintained with respect to the environment wherein the piston includes a relatively rigid central portion and a flexible diaphragm along the periphery of the piston, and the piston is disposed in the manifold so that the flexible diaphragm forms a peripherally disposed protrusion along the side wall of the manifold, the protrusion having a movable internal and movable external wall whose lengths can vary as the central portion of the diaphragm moves in relation to the periphery.

Claim 43

A device for regulating the flow of fluid from an environment to an evacuation means, the device comprising: a path, through which the fluid passes from an input in fluid communication with the environment to an output in fluid communication with the evacuation means, the path not being vented at any point between the input and the output, so that the mass of fluid exiting the device through the output is substantially equal to the mass of fluid entering the device from the input; a piston movably mounted to a piston mounting structure, the piston being so mounted that it may constrict the path at a constriction point, and so that it may move in a vertical direction and transverse to the path at the constriction point, the piston having (i) a distal face at the bottom of the piston exposed to a reference pressure, (ii) a frontal face at the top of the piston across which the fluid flowing through the path on the environment side of the constriction point directly passes, the piston being mounted so that the weight of the piston exerts a force on the piston in a direction that tends to move the piston so as to widen the path at the constriction point, the force exerted on the piston by the pressure of the fluid in the path on the evacuation means side of the constriction point is transverse to the direction of movement of the piston, and the forces exerted on the piston by the reference pressure, the pressure of the fluid in the path on the environment side of the constriction point, and the weight of the piston are generally parallel to the direction of movement of the piston.

Claim 44

A device for regulating the flow of fluid from an environment to an evacuation means, the device comprising: a path, through which the fluid passes from an input in fluid communication with the environment to an output in fluid communication with the evacuation means, the path not being vented at any point between the input and the output, so that the mass of fluid exiting the device through the output is substantially equal to the mass of fluid entering the device from the input; a piston movably mounted to a piston mounting structure, the piston being so mounted that it may constrict the path at a constriction point, and so that it may move in a vertical direction and transverse to the path at the constriction point, the piston having (i) a distal face at the bottom of the piston exposed to a reference pressure, (ii) a frontal face at the top of the piston across which the fluid flowing through the path on the environment side of the constriction point directly passes, the piston being mounted so that the weight of the piston exerts a force on the piston in a direction that tends to move the piston so as to widen the path at the constriction point, the force exerted on the piston by the pressure of the fluid in the path on the evacuation means side of the constriction point is transverse to the direction of movement of the piston, and the forces exerted on the piston by the reference pressure, the pressure of the fluid in the path on the environment side of the constriction point, and the weight of the piston are generally parallel to the direction of movement of the piston.

Claim 46

A device for regulating the flow of fluid from an environment, the environment having a pressure less than the ambient pressure, to an evacuation means, the device comprising: a path, through which the fluid passes from an environment port in fluid communication with the environment to at least two evacuation ports in fluid communication with the evacuation means, the path not being vented at any point between the environment port and the evacuation ports, so that the mass of fluid exiting the device through the evacuation ports is substantially equal to the mass of fluid entering the device from the environment port; a piston having a (i) distal face exposed to a reference pressure and (ii) a frontal face with the center and a perimeter, the piston being movably mounted adjacent to the evacuation ports so that the perimeter of the frontal face may constrict the path at the evacuation ports, and so that the piston may move in a direction transverse to the path at the evacuation ports, wherein the environment port is located opposite from the center of the frontal face and the two evacuation ports are spaced away from each other so that the path is redirected from a direction that is generally parallel to the direction of movement of the piston to at least two directions extending radially from the center of the frontal face to the at least two evacuation ports; and restoring means, including the weight of the piston, for exerting a force on the piston in a direction that tends to move the piston so as to widen the path at the constriction points.

Claim 47

A device for regulating the flow of fluid from an environment, the environment having a pressure less than the ambient pressure, to an evacuation means, the device comprising: a path, through which the fluid passes from an environment port in fluid communication with the environment to at least two evacuation ports in fluid communication with the evacuation means, the path not being vented at any point between the environment port and the evacuation ports, so that the mass of fluid exiting the device through the evacuation ports is substantially equal to the mass of fluid entering the device from the environment port; a piston having a (i) distal face exposed to a reference pressure and (ii) a frontal face with the center and a perimeter, the piston being movably mounted adjacent to the evacuation ports so that the perimeter of the frontal face may constrict the path at the evacuation ports, and so that the piston may move in a direction transverse to the path at the evacuation ports, wherein the environment port is located opposite from the center of the frontal face and the two evacuation ports are spaced away from each other so that the path is redirected from a direction that is generally parallel to the direction of movement of the piston to at least two directions extending radially from the center of the frontal face to the at least two evacuation ports; and restoring means, including the weight of the piston, for exerting a force on the piston in a direction that tends to move the piston so as to widen the path at the constriction points.

Claim 49

A device for regulating the mass flow rate of fluid flowing from an input to an output, the device comprising: a path through which the fluid passes from the input to the output; a venturi disposed in the path; and a piston having on its top a frontal face forming part of the venturi, such that fluid flows directly over the frontal face, and on the piston's bottom a distal face exposed to a reference pressure, the piston being movably mounted so that as the velocity of the fluid flowing through the path increases the difference between the reference pressure and the pressure in the venturi increases such that the piston tends to move so as to narrow the venturi, the piston being mounted so that the weight of the piston exerts a force on the piston in a direction that tends to move the piston so as to widen the venturi.

Claim 50

A device for regulating the mass flow rate of fluid flowing from an input to an output, the device comprising: a path through which the fluid passes from the input to the output; a venturi disposed in the path; and a piston having on its top a frontal face forming part of the venturi, such that fluid flows directly over the frontal face, and on the piston's bottom a distal face exposed to a reference pressure, the piston being movably mounted so that as the velocity of the fluid flowing through the path increases the difference between the reference pressure and the pressure in the venturi increases such that the piston tends to move so as to narrow the venturi, the piston being mounted so that the weight of the piston exerts a force on the piston in a direction that tends to move the piston so as to widen the venturi.