Fluidic diode check valve

Abstract

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.

Claims

1. A fluidic diode comprising: a housing having an inlet and an outlet and a divided fluid passageway formed therein, wherein the divided fluid passageway is defined by mirror image partitions positioned a first spaced apart distance from one another by a constant width primary fluid pathway and positioned a second spaced apart distance from an interior wall of the housing that defines a constant width secondary fluid pathway between each partition and the interior wall; wherein each of the mirror image partitions is generally tear-drop shaped when viewed as a coronal plane cross-section with a tip pointed generally toward the outlet; wherein 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 wherein 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.

2. The fluidic diode of claim 1, wherein 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.

3. The fluidic diode of claim 2, wherein the tip of each of the mirror image partitions comprises a secondary arcuate side having a radius of about 0 to about 0.1.

4. The fluidic diode of claim 1, wherein the outlet is dimensionally larger than the inlet.

5. The fluidic diode of claim 4, wherein the dimension of the outlet to the dimension of the inlet has a ratio of about 4:1 to about 2:1.

6. The fluidic diode of claim 4, wherein the width of the inlet is substantially the same as the width of the constant width primary fluid pathway.

7. The fluidic diode of claim 6, wherein the dimension of the outlet to the dimension of the inlet has a ratio of about 4:1 to about 2:1.

8. An engine system, comprising a fluidic diode according to claim 1.

9. The engine system of claim 8, wherein 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.

10. The engine system of claim 9, wherein the tip of each of the mirror image partitions comprises a secondary arcuate side having a radius of about 0 to about 0.1.

11. The engine system of claim 8, wherein the outlet is dimensionally larger than the inlet.

12. The engine system of claim 11, wherein the fluidic diode operatively controls fluid flow in a fuel vapor purge system.

13. The engine system of claim 12, wherein the dimension of the outlet to the dimension of the inlet has a ratio of about 4:1 to about 2:1.

14. The engine system of claim 12, wherein the width of the inlet is substantially the same as the width of the constant width primary fluid pathway.

15. The engine system of claim 14, wherein the dimension of the outlet to the dimension of the inlet has a ratio of about 4:1 to about 2:1.

16. The engine system of claim 8, wherein the fluidic diode operatively controls fluid flow of an engine manifold, a crankcase ventilation system, a supercharger, an air pump in a positive crankcase ventilation system, an air compressor in a positive crankcase ventilation system, a canister purge system, or a pneumatic brake system.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The claimed subject matter is described with reference to the accompanying drawings. A brief description of each figure is provided below. Elements with the same reference number in each figure indicate identical or functionally similar elements.

(2) FIG. 1 is a perspective view of one embodiment of a fluidic diode.

(3) FIG. 2 is a cross-sectional view along the coronal plane of the fluidic diode of FIG. 1 transverse to the midsagittal plane aligned with the primary fluid pathway.

(4) FIG. 3 is a flow diagram of fluid flow from the inlet to the outlet.

(5) FIG. 4 is a flow diagram of fluid flow from the outlet to the inlet.

(6) FIG. 5 is a graph of check valve performance of the fluidic diode when different differential pressure drops occur across the fluidic diode.

(7) FIG. 6 is a graph demonstrating that increasing the pressure drop across the fluidic diode causes an increase in the ratio of flow into the inlet to flow into the outlet side.

DETAILED DESCRIPTION

(8) 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.

(9) FIGS. 1 and 2 illustrate a fluidic diode 10 that 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 outlet 18 to inlet 16), while allowing flow in the desired direction A (from inlet 16 to outlet 18). As shown in FIG. 1, the fluidic diode 10 has a midsagittal plane M and a coronal plane C. The midsagittal plane M is aligned with a central longitudinal axis of a primary fluid pathway 22, and the coronal plane C is transverse to the midsagittal plane M. The fluidic diode 10 has housing 12 with an inlet 16 and an outlet 18 connected for fluid communication therebetween by a divided fluid passageway 20 formed within the housing.

(10) Referring now to FIG. 2, the divided fluid passageway 20 is defined by mirror image partitions 14 each positioned a spaced apart distance from one another by a constant width primary fluid pathway 22 and positioned a spaced apart distance from an interior wall 28 of the housing that defines a constant width secondary fluid pathway 24 between each partition 14 and the interior wall 28 of the housing. Each mirror image partition 14 has a generally tear-drop shaped coronal plane cross-section with its tip 30 pointed generally toward the outlet 18. The partitions 14 each have two generally straight sides 32 extending from the tip 30 that each have a length of about 4 mm to about 6 mm, which are connected to one another by a primary arcuate side 34 having a radius of about 1 to about 2. The tip 30 of each partition may be a second arcuate side having a radius of about 0 to about 0.1.

(11) 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 inlet 16 and the outlet 18 are of different dimensions, preferably with the outlet being dimensionally larger than the inlet as illustrated in FIG. 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 W.sub.1 and the width W.sub.0 of the outlet, or it may be the area defined by the inlet and the area defined by the outlet.

(12) In another aspect, the width W.sub.1 of the inlet 16 is substantially the same as the width W.sub.1 of the constant width primary fluid pathway 22, and, as indicated by the arrows W.sub.2 and W.sub.1 in FIG. 4, the width W.sub.1 of the primary fluid pathway 22 is substantially the same as the width W.sub.2 of the secondary fluid pathways 24. 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 W.sub.1 of the inlet 16 is less than the width W.sub.1 of the constant width primary fluid pathway 22. Less than as used herein, with respect to the width, means that the width W.sub.1 is about 70% to about 90% of the width of W.sub.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 width W.sub.1 to the width W.sub.1 is 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.

(13) Turning to FIG. 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 mm.sup.2, then the area of the inlet is preferably 4.8 mm.sup.2.

(14) FIG. 6 is 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 diode 10 has 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 diode 10 provides this effect by allowing fluid flowing in the outlet to flow through the secondary fluid pathways 24 as well as the primary fluid pathway 22 in the same direction, but the flow through the secondary fluid pathways 24 exits into the primary fluid pathway 22, proximate the inlet 16, 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 in FIG. 4.

(15) The fluidic diode 10 has low flow restriction in the desired direction A (i.e., high flow through occurs) based on an appropriate pressure differential imposed relative to the inlet 16 and the outlet 18. The low flow restriction is demonstrated in a flow diagram in FIG. 3. In comparing FIGS. 3 and 4, the length of the arrows is proportional to the flow speed of the fluid through the fluidic diode 10. The construction of the fluidic diode 10 provides low flow restriction for the desired direction A by allowing fluid flowing in at the inlet 16 to flow through the primary fluid pathway 22 directly toward the outlet 18 with no impedance to the flow; moreover, some additional flow through the secondary fluid pathways 24 joins the primary fluid pathway 22 proximate the outlet 18 for flow together in the same direction.

(16) 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.

(17) 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.