Fluidic diode check valve

Fluidic diodes are disclosed that have a housing defining an inlet and an outlet and a divided fluid passageway therebetween defined by mirror image partitions generally tear-drop shaped spaced apart a first distance from one another by a constant width primary fluid pathway with the tip thereof pointed generally toward the outlet and spaced apart a second distance from an interior wall of the housing to define a constant width secondary fluid pathway. Fluid flow from the inlet to the outlet is through the primary fluid pathway with some additional flow through the secondary fluid pathways joining the primary fluid pathway proximate the outlet for flow together in the same direction, and fluid flow from the outlet to the inlet through the secondary fluid pathways exits the secondary fluid pathways into the primary fluid pathway, proximate the inlet, in a direction substantially opposite the flow in the primary fluid pathway.

TECHNICAL FIELD

The present application relates to a fluidic diode operating as a check valve, more particularly to a fluidic diode having high flow restriction when a pressure differential is imposed across the inlet and outlet directing fluid flow from the outlet toward the inlet and having low flow restriction when the pressure differential is reversed.

BACKGROUND

There are many circumstances that require a means to limit flow in one direction while permitting easy flow of fluids in the opposite direction. One way of accomplishing this is to use a check valve. A check valve typically has a component, such as a sealing member, in the fluid flow path that is movable between an open and a closed position, where in the closed position the sealing member blocks the flow in one direction and in the open position allows flow therethrough. There is a need for a means to control the flow in this manner without the cost, complexity, and other issues associated with these traditional style check valves.

SUMMARY

Herein, fluidic diodes are disclosed that replace traditional style check valves, i.e., there is no sealing member movable between an open position and a closed position. Instead, the shape and configuration of the internal pathways through the fluidic diode operate as a check valve using just the fluid flow itself therethrough. In all aspects, the fluidic diodes herein have a housing defining an inlet and an outlet and a divided fluid passageway therebetween defined by mirror image partitions generally tear-drop shaped spaced apart a first distance from one another by a constant width primary fluid pathway with the tip thereof pointed generally toward the outlet and spaced apart a second distance from an interior wall of the housing to define a constant width secondary fluid pathway. Fluid flow from the inlet to the outlet is through the primary fluid pathway with some additional flow through the secondary fluid pathways joining the primary fluid pathway proximate the outlet for flow together in the same direction, and fluid flow from the outlet to the inlet through the secondary fluid pathways exits the secondary fluid pathways into the primary fluid pathway, proximate the inlet, in a direction substantially opposite the flow in the primary fluid pathway.

In all aspects, each of the mirror image partitions has two straight sides having a length of about 4 mm to about 6 mm connected by a primary arcuate side having a radius of about 1 to about 2. The tip of each of the mirror image partitions has a secondary arcuate side having a radius of about 0 to about 0.1.

In all aspects, the outlet is dimensionally larger than the inlet, and the dimension of the outlet to the dimension of the inlet has a ratio of about 4:1 to about 2:1, and the width of the inlet is substantially the same as the width of the constant width primary fluid pathway.

The fluidic diodes disclosed herein may operatively control fluid flow within an engine, more particularly, within a subunit of the engine, such as a fuel vapor purge system, more specifically, a fuel vapor purge ejector, or within the intake manifold of the engine, more specifically to increase engine volumetric efficiency, or any system or subsystem that has periodic flow. The fluidic diodes in the engine system may have any and all of the features described herein.

DETAILED DESCRIPTION

The following detailed description will illustrate the general principles of the invention, examples of which are additionally illustrated in the accompanying drawings. In the drawings, like reference numbers indicate identical or functionally similar elements.

FIGS. 1 and 2illustrate a fluidic diode10that functions as a check valve, without a moving sealing member, by effectively using the fluid flow itself to stop or significantly reduce flow in an undesired direction B (from outlet18to inlet16), while allowing flow in the desired direction A (from inlet16to outlet18). As shown inFIG. 1, the fluidic diode10has a midsagittal plane M and a coronal plane C. The midsagittal plane M is aligned with a central longitudinal axis of a primary fluid pathway22, and the coronal plane C is transverse to the midsagittal plane M. The fluidic diode10has housing12with an inlet16and an outlet18connected for fluid communication therebetween by a divided fluid passageway20formed within the housing.

Referring now toFIG. 2, the divided fluid passageway20is defined by mirror image partitions14each positioned a spaced apart distance from one another by a constant width primary fluid pathway22and positioned a spaced apart distance from an interior wall28of the housing that defines a constant width secondary fluid pathway24between each partition14and the interior wall28of the housing. Each mirror image partition14has a generally tear-drop shaped coronal plane cross-section with its tip30pointed generally toward the outlet18. The partitions14each have two generally straight sides32extending from the tip30that each have a length of about 4 mm to about 6 mm, which are connected to one another by a primary arcuate side34having a radius of about 1 to about 2. The tip30of each partition may be a second arcuate side having a radius of about 0 to about 0.1.

For exemplary purposes, the numerical values and ranges below are for a fluidic diode as part of, and operatively controlling fluid flow in, a fuel vapor purge system. The inlet16and the outlet18are of different dimensions, preferably with the outlet being dimensionally larger than the inlet as illustrated inFIG. 2. The dimensions of the outlet compared to the dimensions of the inlet are typically selected to be within a ratio of about 4:1 to about 1.5:1. When the pressure drop across the fluidic device from the inlet to the outlet is in a range of about 2 kPa to about 10 kPa, the ratio of the outlet's dimensions to the inlet's dimensions is about 1.8:1 to about 3.4:1, more preferably about 1.9:1 to about 2.5:1, and even more preferably about 2:1 to about 2.2:1. In one instance, the dimension used for determining the ratios is the width of the inlet W1and the width W0of the outlet, or it may be the area defined by the inlet and the area defined by the outlet.

In another aspect, the width W1of the inlet16is substantially the same as the width W1of the constant width primary fluid pathway22, and, as indicated by the arrows W2and W1inFIG. 4, the width W1of the primary fluid pathway22is substantially the same as the width W2of the secondary fluid pathways24. Substantially the same as used herein, with respect to width(s), means that the widths are within 1% to 3% of each other. In another aspect, the width W1of the inlet16is less than the width W1of the constant width primary fluid pathway22. Less than as used herein, with respect to the width, means that the width W1is about 70% to about 90% of the width of W1. When the pressure drop across the fluidic device from the inlet to the outlet is in a range of about 2 kPa to about 10 kPa, the ratio of the width W1to the width W1is about 1:2.4 to about 1:1.5, more preferably about 1:1.9 to about 1:1.5, and even more preferably about 1:1.75 to about 1:6.

Turning toFIG. 5, the ratio of flow into the inlet (direction A) to flow into the outlet (direction B) is plotted versus the ratio of the inlet area to the outlet area of the fluidic diode for different delta pressures to demonstrate the check valve performance thereof. For each pressure drop, 2 kPa, 4 kPa, 6 kPa, 8 kPa, and 10 kPa, there is a peak ratio of the inlet area to outlet area, shown as approximately 48%. In other words, the area dimension of the inlet should be 48% of the size of the area dimension of the outlet. For example, if the outlet is rectangular (2 mm by 5 mm) with an area of 10 mm2, then the area of the inlet is preferably 4.8 mm2.

FIG. 6is a graph demonstrating that increasing the pressure drop across the diode causes an increase in the ratio of flow into the inlet to flow into the outlet side. In operation, the fluidic diode10has high flow restriction in the undesired direction B which flow tries to occur when a pressure differential is imposed that would direct flow in the undesired direction. The term high flow restriction can be quantified by the ratio of the flow A (FIG. 3) to the flow B (FIG. 4), where high flow restriction is present if the ratio of A/B is greater than two. The construction of the fluidic diode10provides this effect by allowing fluid flowing in the outlet to flow through the secondary fluid pathways24as well as the primary fluid pathway22in the same direction, but the flow through the secondary fluid pathways24exits into the primary fluid pathway22, proximate the inlet16, but directed substantially in the opposite flow direction as the flow in the primary fluid pathway. The high flow restriction is demonstrated in a flow diagram inFIG. 4.

The fluidic diode10has low flow restriction in the desired direction A (i.e., high flow through occurs) based on an appropriate pressure differential imposed relative to the inlet16and the outlet18. The low flow restriction is demonstrated in a flow diagram inFIG. 3. In comparingFIGS. 3 and 4, the length of the arrows is proportional to the flow speed of the fluid through the fluidic diode10. The construction of the fluidic diode10provides low flow restriction for the desired direction A by allowing fluid flowing in at the inlet16to flow through the primary fluid pathway22directly toward the outlet18with no impedance to the flow; moreover, some additional flow through the secondary fluid pathways24joins the primary fluid pathway22proximate the outlet18for flow together in the same direction.

While the dimension and numerical values given above are for a fuel vapor purge ejector system, other geometries, i.e., larger and smaller geometries, with similar ratios of sizes (widths and/or areas) would still be effective in checking flow. For example, a large fluidic diode of the shape disclosed herein could be mounted in an engine manifold, in either or both of the intake or exhaust manifolds, to increase engine volumetric efficiency or in the crankcase ventilation system of an engine, such as in the positions disclosed in U.S. application Ser. No. 14/015,456. The fluidic diodes disclosed herein could be added to any system or subsystem that has periodic flows, such as a mechanical supercharger, air pumps or air compressors for positive crankcase ventilation, canister purge, pneumatic brakes, etc.

The embodiments of this invention shown in the drawings and described above are exemplary of numerous embodiments that may be made within the scope of the appended claims. It is contemplated that numerous other configurations of the fluidic diode may be created taking advantage of the disclosed approach. In short, it is the Applicants' intention that the scope of the patent issuing herefrom be limited only by the scope of the appended claims.