Patent Application
20100122733
These teachings relate generally to pressure biased valves an in particular to pressure biased shutoff valves.
In the prior art, sensing the off state of a system when the fluid source reservoir has the ability to be pressurized would require a check valve having a crack pressure higher than the maximum reservoir pressure. The crack pressure is the nominal pressure drop across the valve during operation. This drop in pressure presents difficulties in small micro-fluidic applications.
What is needed therefore, is a passive shutoff valve that has no maximum pressure, is self regulating, and has a low nominal operating pressure drop.
Embodiments of a valve are disclosed that allow for the control and adjustment of a fluid flow between a valve inlet port and a valve output port as a function of the pressure at the valve inlet port, a pressure at a first pressure input port, and a reference pressure. In one embodiment, the valve that includes two ports—a valve inlet port a valve outlet port, and one or more valve seats circumscribing one or more of the two ports. The valve further includes a diaphragm having first and second major surfaces. The first major surface in a closed position acts as a valve face to cover the one or more valve seats preventing fluid communication therebetween. In an open position, the first major surface unseals the valve inlet port and the valve outlet port and allows for fluid communication therebetween. In addition, the valve includes a first pressure inlet coupled to the second major surface of the flexible diaphragm. The first pressure inlet provides a first pressure to said second major surface to attempt to move the diaphragm into the closed position. The valve also includes a reference pressure providing component operatively coupled to the second major surface of said flexible diaphragm. In one instance, fluid communication between said valve inlet and said valve outlet can be controlled and adjusted utilizing in the first pressure and the reference pressure.
Several embodiments of the valve of these teachings are disclosed. Methods for utilizing the valve of these teachings are also disclosed.
These and other features, aspects, and advantages of the present teachings will become better understood with regard to the following description, appended claims, and accompanying drawings. The drawings are not necessarily to scale, emphasis instead being placed on illustration of principles of the teachings. The drawings include the following figures:
The present teachings may be understood by the following detailed description, which should be read in conjunction with the attached drawings. The following detailed description of certain embodiments is by way of example only and is not meant to limit the scope of the present teachings.
“Diaphragm” as used herein refers to an element capable of being manipulated such that it can at least partially block the passage of fluid flow between an input port and an output port in a first position and permit the flow of fluid between an input port and an output port in a second position. An “actuating force” is a force that is capable of moving the diaphragm between the first and second positions. A “valve seat” is an element designed to accept a portion of the diaphragm when in the first position, thereby blocking fluid flow from the respective port.
The present teachings relate the use of scaled valves to control fluid flow. While the present teachings are not limited to a particular sealing method, in one embodiment, an actuating force pushes a diaphragm against or away from a valve seat to restrict fluid flow and the diaphragm is then sealed to or removed from the valve seat.
In the first position, the first major surface 110a covers the valve outlet seat 106 and the valve outlet port 108. In this position, the first major surface acts a closed valve face and prevents fluid communication between valve inlet port 104 and the valve outlet port 108.
In the second position, the first major surface 110a uncovers the valve outlet seat 106, valve outlet port 108; the valve inlet port 104 is also not covered by the first major surface 110a. In this position, the first major surface acts an open valve face and allows fluid communication between valve inlet port 104 and the valve outlet port 108.
The valve 100 also includes a first pressure inlet 112. The first pressure inlet 112 provides for pressure to be exerted against the second major surface 110b of the diaphragm 110. In the embodiment depicted in
In the first position, the first major surface 110a covers both the valve inlet seat 102 and valve inlet port 104. In this position, the first major surface acts a closed valve face and prevents fluid communication between valve inlet port 102 and the valve outlet port 108.
In the second position, the first major surface 110a uncovers the valve inlet seat 102, valve inlet port 104; the valve outlet port 108 is also not covered by the first major surface 110a. In this position, the first major surface acts an open valve face and allows fluid communication between valve inlet port 102 and the valve outlet port 108. The valve 100 also includes a first pressure inlet 112 and a reference pressure providing component 114.
In the first position, the first major surface 210a covers both the valve inlet seat 202, valve inlet port 204, valve outlet seat 206, and valve outlet port 208. In this position, the first major surface acts a closed valve face and prevents fluid communication between valve inlet port 202 and the valve outlet port 208.
In the second position, the first major surface uncovers both the valve inlet seat 202, valve inlet port 204, valve outlet seat 206, and valve outlet port 208. In this position, the first major surface acts an open valve face and allows fluid communication between valve inlet port 202 and the valve outlet port 208.
The valve 200 also includes a first pressure inlet 212. The first pressure inlet 212 provides for pressure to be exerted against the second major surface 210b of the diaphragm 210. In the embodiment depicted in
In the embodiments described hereinabove, the movement of diaphragm 110 (or 210 in
In one embodiment, each of the first and second surfaces has substantially equal surface areas. As is known, force=pressure*surface area, or F=P*A. In this embodiment, the forces on the first and second major surfaces become:
P
out
*A
first≧(Pin+Pref)*Asecond (1)
where Afirst is the surface area of the first major surface, Asecond is the surface area of the second major surface, Pout is the pressure resulting from flow from the valve inlet port 104 (or 204,
P
out
≧P
in
+
Pref. (2)
The above conditions is the condition in which the diaphragm moves from position 110′ to 110″ and moves away from the valve inlet port and valve outlet port and allows fluid communication therebetween.
It should be noted that while the reference pressure has been depicted as a pressure, for example provided by a separate pump or other pressure generating element. However, the reference pressure may also be provided by a force, for example provided by a spring, a bimetallic material, or the force may be generated by the elasticity of the diaphragm 110 itself.
In another embodiment, the first and second surfaces have unequal surface areas. As is known, force=pressure*surface area, or F=P*A. In this embodiment, the forces on the first and second major surfaces become:
P
out
*A
first≧(Pin+Pref)*Asecond (3)
where Afirst is the surface area of the first major surface, Asecond is the surface area of the second major surface. Thus, the control of the fluid flow between the valve inlet port and the valve outlet port may be a function of Pin, Pout and the ratio of the first and second surface areas.
The condition given by equations (3) hereinabove is the condition in which the diaphragm moves from position 110′ to 110″ and moves away from the valve inlet port and valve outlet port and allows fluid communication therebetween. In this way, the valve operation may be adjusted to open at pressures that are specific to a particular system by adjusting the first and second surface areas accordingly.
As above, it should be noted that while the reference pressure has been depicted as a pressure, for example, as provided by a separate pump or other pressure generating element. However, the reference pressure may also be generated by a force, for example provided by a spring, a bimetallic material, or the force may be generated by the elasticity of the diaphragm 110 itself.
This embodiment is particularly useful in a system in which the valve and pump are located within the fluid supply reservoir or in a fluid supply cartridge. In this instance, the pump will be at rest, i.e., non-operational in the detached state and the valve 100 will prevent fluid from leaving the fluid supply cartridge. However, embodiments of the valve of these teachings can also be used when the valve and pump are separately connected to the fuel reservoir or cartridge. By operation of the embodiments disclosed hereinabove, flow into the valve outlet port is substantially prevented when the pump is inactive.
By careful adjustment of the various parameters, for example the size of inlet seat 102, the size of the valve inlet port 104, the size of the valve outlet seat 106, the size of the valve outlet port 108 or the size of the first and second surface areas, the pressure at first pressure inlet may be used to control the fluid flow between the valve input port 104 and valve output port 108. By using the pressure at the first pressure inlet as the control variable and the fluid volume or flow rate as a controlled variable, a feedback control system may be designed that allows for using the valve 100 as a flow control device.
It should be noted that while several embodiments of the reference pressure generating component have been described, these teachings are not limited to only those embodiments.
While the present teachings have been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the teachings as defined by the appended claims. All the features disclosed in this specification, including any accompanying claims, abstract, and drawings, may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise.
