Patent Application
20110209772
1. Field of the Invention
The present invention relates generally to pipe connectors, more specifically to venturi connectors, and most specifically to an in-line treble-port venturi connector having a low flow, low pressure inlet port for drawing supplemental fluid into a main flow path.
2. Description of Related Art
Venturi tubes are used for a variety of applications in fluid systems. Generally, a venturi tube or venturi operates by restricting a flow path, for example, by narrowing a section of pipe from a large diameter to a smaller diameter. According to the Bernouli principle, as flow velocity increases through the restriction, it creates a corresponding drop in fluid pressure. It is well known to exploit this principle by connecting pressure gauges at both the large and small diameter portions of the pipe to detect a pressure differential from which a measurement of fluid velocity or flow rate may be derived.
Another application of the Bernouli principle may be found in the design of a carburetor. In a carburetor, a first fluid, such as fuel, may be introduced into the main flow of a second fluid, such as air, by directing the flow of the second fluid through a venturi in the main flow path. An inlet for the first fluid may be connected to the venturi at the restriction area, so that when the second fluid gains sufficient velocity through the restricted area, the corresponding pressure drop draws the first fluid into the main flow path. See, e.g. V. Ostdiek et al., Inquiry Into Physics, pp. 160-162, 1987.
The carburetor has been used throughout the twentieth century as a means for mixing a hydrocarbon fuel (such as gasoline) with air drawn into the intake manifold of an internal combustion engine. More recently, the applicants of the present invention have investigated the feasibility of supplementing the hydrocarbon fuel in an internal combustion engine of a vehicle with hydrogen and/or oxygen generated on board the vehicle through electrolysis of water or other means. The hydrogen/oxygen gas stream is usually only a fraction of a percent of the intake combustion air flow but experimental evidence shows that this small stream can reduce emissions of particulates from diesel engines and in some cases also reduce emissions of NOx and provide small increases in engine fuel efficiency. On-board hydrogen/oxygen generators are typically water electrolyzers powered by electrical current from the vehicle battery or alternator and are fitted to the rear of the cab compartment of a truck or under the hood of a car.
For the present inventors, a design objective for an on-board hydrogen/oxygen generator is the minimization of cost and complexity through the use of passive controls. The problem being solved by the present invention is how to introduce a supplemental flow of hydrogen or oxygen into the airstream of an intake manifold of an internal combustion engine using passive controls.
The present invention provides an engineering design for an in-line treble port venturi connector that provides a low flow, low pressure inlet port for drawing supplemental fluid into a main flow path. The invention also pertains to a method for creating the low flow, low pressure inlet port. One application for the invention is in conjunction with an on-board hydrogen generator for a vehicle, wherein the connector may be used to introduce hydrogen and/or oxygen gas from the generator as a fuel supplement into a main flow of hydrocarbon fuel in the intake manifold of an internal combustion engine.
In one embodiment, the invention provides an in-line treble-port venturi connector. The connector includes a main flow tube having a mixing channel bordered by an upstream port and a downstream port, the upstream port having an inner diameter greater than an inner diameter of the mixing channel. An inlet port is provided in fluid communication with the mixing channel, and a baffle is provided that projects into the main flow tube from the inner surface of the mixing channel at a location upstream of the inlet port. By immersing the connector within flow of a main fluid to direct a portion of the main fluid through the upstream port, the portion of main fluid that flows into the mixing channel will increase in velocity and decrease in pressure according to the Bernouli principle. The baffle obstructs part of the flow to create a separation zone within the area of decreased pressure and to cause rotational flow in the separation zone so that within the separation zone the average flow rate in the direction of main flow is less than main fluid flow rate around the separation zone. The connector is configured to create the separation zone adjacent to the inlet port, so that supplemental fluid at a higher pressure may be introduced into a low pressure area of the mixing channel at a low flow relative to the main flow. Rotational flow induced in the supplemental fluid assists in mixing the supplemental fluid into the main flow downstream of the connector.
More elaborate embodiments of a connector according to the invention include variations in the shape of the baffle, various means for connecting the supplemental fluid to the inlet port, and various means for anchoring the connector to the wall of a conduit carrying the flow of main fluid.
A method according to the invention for providing low flow, low pressure inlet for introducing supplemental fluid into a flow of main fluid includes the following steps: (i) immersing a treble-port venturi within the flow of main fluid to direct a portion of the main fluid flow through the venturi, the venturi having an upstream port, a mixing channel, and a downstream port, the upstream port having an inner diameter greater than an inner diameter of the mixing channel and the mixing channel having an inlet port for supplemental fluid, (ii) connecting the inlet port to a supply of the supplemental fluid external to the main fluid flow, and (iii) obstructing the portion of main fluid flow through the venturi upstream of the inlet port to create a separation zone adjacent to the inlet port. The method may also include a step for maintaining pressure of the supplemental fluid greater than pressure in the separation zone, and a step for maintaining pressure of the supplemental fluid less than pressure in the main fluid outside of the venturi connector.
Other systems, methods, features and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the accompanying claims. Component parts shown in the drawings are not necessarily to scale, and may be exaggerated to better illustrate the important features of the invention. Dimensions shown are exemplary only. In the drawings, like reference numerals may designate like parts throughout the different views, wherein:
The following disclosure presents an exemplary embodiment of the invention for a treble-port venturi connector for introducing supplemental flow into a main flow. The venturi connector is designed for immersion within a flow path of a main fluid, and for directing the supplemental flow into a low pressure separation zone created within the venturi connector.
The connector 10 may be formed from a single rigid material, such as a metal or thermoset plastic, and it may be molded, cast, or machined, or formed by some combination of molding, casting, and machining. In another embodiment, the connector 10 may be composed of two or more parts that are welded together, or from two or more parts that are fastened together, for example, by threaded connection.
Inlet tube 13 may extend from an inlet port in the main flow tube 14 to a connecting end 20. An anchoring flange 21 may be connected to the inlet tube 13 between the connecting end 20 and the inlet port. In one embodiment, the anchoring flange may project radially outward from the inlet tube, as shown. The anchoring flange 21 may be displaced from the main flow tube by a length of inlet tube called the insertion length 22. When installed, the anchoring flange 21 may abut an inner wall of a main flow conduit (such as main flow conduit 11), thereby displacing the main flow tube 14 from the inner wall of the main flow conduit by a distance determined according to the insertion length 22.
On the opposite side of the anchoring flange, the inlet tube 13 may also provide a tapered portion 23. Tapered portion 23 may extend from the lower surface of the anchoring flange, i.e. the surface that faces away from the main flow tube, toward the connecting end 20. In one embodiment, the tapered portion 23 has a maximum diameter at the anchoring flange, tapering to a minimum diameter as it approaches the connecting end.
In the embodiment of
For example, one method of installing the connector 10 is to drill or tap an installation hole into an uninstalled section of main flow conduit. Preferably, the section of main flow conduit is formed from a slightly resilient material such as a hard rubber. The installation hole should be slightly smaller in diameter than the inner diameter of the threaded portion 24. The connecting end 20 of the connector 10 may then be pushed or rotated through the installation hole from inside the section of main flow conduit until the lower part of the tapered portion 23 reaches the installation hole. At this point, fastening hardware, such as a washer and hex nut, may be respectively placed and threaded onto the threaded portion 24 from outside the conduit section. By tightening the nut onto threaded portion 24, the tapered portion 23 will be drawn further into the installation hole to form a tight seal with the conduit section. As the nut is tightened further, the lower surface of the anchoring flange 21 will abut the inner wall of the conduit section, and the anchoring spikes 27 will begin to contact the inner wall. At this point, connector 20 may be oriented so that the upstream port faces the direction of incoming flow through the main flow conduit. As the nut continues to tighten, the anchoring spikes will dig into the inner wall of the conduit section and prevent rotation of the connector. The nut may then be tightened to a desired torque.
Flow entering the upstream port is ideally irrotational. As the main flow enters the connector, it accelerates through the venturi restriction and impacts the outer wall 31, which diverts the flow over and around the baffle. In an area directly downstream of the baffle 19, the obstruction of the baffle creates a separation zone 35. The dashed line indicates, approximately, the boundary of the separation zone. A portion of the main flow continues around the separation zone as irrotational flow. Within separation zone 35, however, portions of the fluid separate from the irrotational flow channels and enter the separation zone, forming vortices characterized by rotational flow patterns. The shape of the separation zone and the flow characteristics therein are determined by a number of factors, including the Reynolds number, the geometry of the channel, the shape of the baffle, and the roughness of the outer wall. See, e.g., Roberson, et al., Engineering Fluid Mechanics, 3rd Ed., pp. 158-162, 1985.
In
In a connector according to the present invention, three concepts are combined: (i) the concept of a venturi restriction to determine pressure at point 34, (ii) the concept of creating a separation zone 35 through which the pressure at point 34 prevails, and (iii) the treble-port configuration whereby the inlet port 18 opens into the separation zone 35 downstream of baffle 19. By this novel design, supplemental fluid that is maintained at a higher pressure than the pressure in the separation zone may enter the mixing channel through the inlet port into a volume of rotational flow. Because pressure in the separation zone is lower than pressure in the main flow outside of the connector, the Bernouli principle requires that flow velocity in the separation zone be greater than main flow velocity outside the connector. However, because the flow within the separation zone is rotational, the Bernouli principle is satisfied by higher angular velocities of fluid rotating as vortices within the separation zone. Some of the kinetic energy of the fluid within the separation zone will be dissipated as heat. In aggregate, the average flow velocity in the separation zone in the direction of main flow from the upstream port to the downstream port will be lower than the flow velocity of irrotational fluid flowing around the separation zone (i.e. the irrotational flow indicated by the paths of upper and lower flow lines 33). The overall result is that a treble-port venturi connector according to the invention creates a low pressure, low flow entry point for introducing a supplemental fluid into a main flow path. This concept is counter-intuitive to engineers designing systems according to the Bernouli principle, which associates low pressure with high flow and vice versa.
One advantage of a treble-port venturi connector of the present invention is that it allows a supplemental fluid to be introduced into a main flow path in a more controllable fashion. For example, parameters such as the geometry of the flow channels and baffle, the main fluid flow rate, and the supplemental fluid pressure, may be determined so that the supplemental fluid flow may be passively controlled. An ideal mixture of two fluids, for example, a main flow of hydrocarbon fuel and a supplemental flow of hydrogen, may be obtained thereby. A further advantage of the invention is that configuration of the connector causes rotational flow of supplemental fluid as it enters the inlet port. The rotational flows or whirlpools of supplemental and main fluids improve the homogeneity of the mixture as it progresses downstream. Yet another advantage of the present invention is that it allows the supplemental fluid to be maintained at a lower pressure than the normal pressure of the main fluid. This has particular significance in applications for on-board hydrogen generators. For safety reasons, it preferable not to maintain hydrogen gas in a highly pressurized state on board a passenger vehicle.
Various configurations of a baffle 19 are possible within the scope of the invention.
This embodiment of inlet tube 40 may be considered similar to connector 10 but with the main flow tube 14 removed. Inlet tube 40 may be substantially cylindrical, and includes an insertion end 41, and anchoring flange 42, and a connecting end 44. The insertion end 41 defines an outlet port 45 as an opening in the insertion end to allow passage of supplemental fluid, such as hydrogen or oxygen gas, from the tube and into the main flow 43. The baffle 19 may be formed at the insertion end 41 so that it extends the insertion end 41 beyond the outlet port 45 on one side of the outlet port, as shown. In one embodiment, the baffle 19 may be formed as a partial circumferential extension of the insertion end beyond the outlet port 45, and in another embodiment, the partial circumferential extension may be formed as a semi-cylindrical extension of the main cylindrical portion of the inlet tube.
The anchoring flange 42 projects from an outer wall of the inlet tube 40 radially outward with respect to an imaginary longitudinal axis running vertically through the center of the tube. One or more anchoring spikes 47 may be disposed on a lower surface of the anchoring flange 42, that is, the surface facing away from the insertion end 41, as shown. The pointed end of each anchoring spike 47 protrudes a short distance from the flange surface and is designed to penetrate (but not perforate) an inner wall of the main flow conduit when the inlet tube is clamped thereto, to anchor the tube to the conduit and prevent rotation or slippage of the tube.
The anchoring flange 42 may be displaced from the outlet port by an insertion length 46. The insertion length 46 may be defined as length the positions the outlet port 45 at an approximate center of main flow 43 when the inlet tube 40 is anchored to a main flow conduit. In one embodiment, an apparatus according to the invention may include a portion of a main flow conduit, such as a rubber boot or rubber hose connection, with the inlet tube 45 installed. An inlet tube so installed means that it is fully clamped to opposing sides of a wall of the main flow conduit with the anchoring spikes 47 engaging the inner wall.
The connecting end 44 extends from the lower surface of the anchoring flange 42 and terminates at an inlet port 48. In one embodiment, the connecting end 44 may include a tapered circumferential portion 49 located adjacent to the lower surface of the anchoring flange 42, as shown. A threaded circumferential portion 50 may extend along the outside surface of the tube from the tapered circumferential portion 49 to a clamping length 51. The clamping length provides sufficient surface area to allow a hose clamp to connect and seal a plastic or rubber supply tube to the connecting end. The clamping length 51 may extend from the threaded circumferential portion to a tubing barb 52. The tubing barb may provide a tapered portion that tapers from a maximum diameter at the junction with the clamping length, to a minimum diameter at the inlet port 48. An abrupt edge 53 may be formed at the junction with the clamping length to create the seal when the supply tube is clamped along the clamping length 51.
When the inlet tube 40 is installed in a main flow conduit so that the baffle 19 is located approximately in the center of main fluid flow, a separation zone will form downstream of baffle 19. The separation zone will exhibit flow characteristics similar to those described in the context of connector 10 and shown in
When installing the inlet tube 40 within a section of main flow conduit, it may be helpful to include a visual indicator on the connecting end 44 that indicates the proper orientation of the inlet tube 40 with respect to the direction of main fluid flow. For this purpose, to indicator such as an arrow or other directional marker (see, e.g. arrow 30 in
Exemplary embodiments of the invention have been disclosed in an illustrative style. Accordingly, the terminology employed throughout should be read in a non-limiting manner. Although minor modifications to the teachings herein will occur to those well versed in the art, it shall be understood that what is intended to be circumscribed within the scope of the patent warranted hereon are all such embodiments that reasonably fall within the scope of the advancement to the art hereby contributed, and that that scope shall not be restricted, except in light of the appended claims and their equivalents.
This invention claims priority to U.S. Provisional Application No. 61/305,786, which was filed Feb. 18, 2010, and which is fully incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61305786 | Feb 2010 | US |
