The invention relates to fuel rails for a fuel system of an internal combustion engine, and more particularly to a self-damping fuel rail for damping pressure pulsations created by the fuel injectors.
In fuel injection systems, pressure pulsations within the fuel system, and in particular a fuel rail, can cause various problems. For example, internal pressure pulsations within a fuel rail tube of an automotive fuel injection system can result in audible noise, and can adversely affect tailpipe emissions and driveability. It is known to use self-damping fuel rails in the fuel injection system to solve these problems.
The present invention provides a fuel rail for a fuel-injected internal combustion engine. The fuel rail includes an elongated tube including a longitudinal axis, an overall length, and a cross-sectional shape along a substantial portion of the length of the tube. The cross-sectional shape is a closed curve, wherein all portions of the cross-sectional shape curve outwardly from the longitudinal axis, and the cross-sectional shape has a non-constant radius. The fuel rail also includes at least one fuel outlet for communicating with a fuel injector.
In a further embodiment of the invention, the radius of the tube varies adjacent the fuel outlet. In another embodiment of the invention, the tube includes a first axis perpendicular to the longitudinal axis with the cross-sectional shape symmetrical about the first axis. The tube may further include a second axis perpendicular to the longitudinal axis and the first axis with the cross-sectional shape symmetrical about the first and second axes. In still a further embodiment of the invention, the cross-sectional shape is substantially elliptical.
The present invention also provides a fuel supply system for a fuel-injected internal combustion engine. The fuel supply system includes a fuel rail including a longitudinal axis and a substantially elliptical cross-sectional shape with the fuel rail further including a sidewall defining a chamber and first and seconds ends. The fuel supply system also includes at least one fuel outlet formed in the sidewall for communicating with a fuel injector and a fuel injector cup in communication with the fuel outlet and the chamber.
In a further embodiment of the invention, the fuel rail has a thickness wherein the thickness adjacent the fuel injector is greater than the thickness of the remaining portions of the fuel rail.
In a further embodiment of the invention, the fuel supply system includes a second fuel rail including a longitudinal axis and having a substantially elliptical cross-sectional shape, the second fuel rail further including a sidewall defining a chamber and first and second ends. At least one fuel outlet is formed in the sidewall of the second fuel rail for communicating with a fuel injector. Further, a fuel conduit communicates with the chamber of the first fuel rail and the chamber of the second fuel rail.
The present invention further provides a method for fabricating a fuel rail for a fuel-injected internal combustion engine. The method includes providing an elongated tube and forming the tube to have a non-constant radius such that a cross-sectional shape of the tube is a closed curve, wherein all portions of the cross-sectional shape curve outwardly.
In a further embodiment of the invention, the tube is formed by rolling, whereas in another embodiment of the invention, the tube is formed by flattening.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings.
Before one embodiment of the invention is explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is understood that the phraseology and terminology used herein with reference to element orientation (such as, for example, terms like “top”, “bottom”, “side”, etc.) are only used to simplify description of the present invention, and do not alone indicate or imply that the element referred to must have a particular orientation. In addition, terms such as “first” and “second” are used herein for purposes of description and are not intended to indicate or imply relative importance or significance. The use of “including”, “having” and “comprising” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.
The tube has a first axis 54 perpendicular to the longitudinal axis 22 and a second axis 58 perpendicular to the longitudinal axis 22 and the first axis 54. In a preferred embodiment of the invention, the cross-sectional shape 26 is symmetrical about the first axis 54 and the second axis 58. In still another preferred embodiment of the invention, the cross-sectional shape 26 is elliptical (shown in
In the illustrated embodiment of the invention, the whole fuel rail 14 has a thickness T between about 0.8 mm and about 1.5 mm (shown in
As illustrated in
The cross-sectional shape 26 of the fuel rail 14 reduces pressure pulsations within the fuel rail 14. As compared to prior art fuel rails having an oval cross-sectional shape with flat surfaces, the cross-sectional shape 26 of the fuel rail 14 has a more gradual transition from more curved to less curved surfaces of the fuel rail 14, which reduces stress in the fuel rail 14. Curved surfaces are stronger and stiffer than flat surfaces due to an increase in the bending moment. The transverse stiffness (i.e., in-plane stiffness transverse to the longitudinal axis of the fuel rail) in the curved cross-sectional shape 26 couples with the bending stiffness of the fuel rail 14 for a more rigid fuel rail as compared to oval prior art fuel rails. Therefore, the fuel rail 14 having the cross-sectional shape 26 experiences less deflection under the same pressure as prior art fuel rails having an oval cross-sectional shape. The fuel rail 14 distributes stress from fuel pressure pulsations over a larger area than prior art fuel rails with improved absorption of the pressure pulsations and reduced noise within the fuel injection system.
Further, the cross-sectional shape 26 includes a larger interior rail volume, as compared to prior art fuel rails having an oval cross-sectional shape. The larger volume of the fuel rail 14 also aids in distributing stress from fuel pressure pulsations in the fuel rail 14 over a larger area than prior art fuel rails, and combined with the flexible sidewall 30, reduces the pressure pulsations returned to a fuel inlet 62. The cross-sectional shape 26 of the fuel rail 14 results in damping of the fuel rail 14 over a wider range of frequencies and improves the fatigue life of the fuel rail 14.
The fuel rail 14 is fabricated using an elongated tube 66 that has a substantially circular cross-sectional shape, however, in further embodiments of the invention tubes having other shapes may be used. The tube is formed or processed to have the desired shape, i.e., until the cross-sectional shape 26 has a non-constant radius such that the cross-sectional shape 26 of the fuel rail 14 is a closed curve with all portions of the cross-sectional shape 26 curving outwardly. The cross-sectional shape 26 of the tube is formed by roll-forming, although in further embodiments of the invention, flattening, hydro-forming, or other known processes in the art are used to form the cross-sectional shape to its desired shape.
The elongated tube 66 is comprised of stainless steel, such as 300 series stainless steel, available from Central Steel (Detroit, Mich.), which has a long fatigue life, does not leak or corrode, and is recyclable. Chrome and nickel may be added to the steel for corrosion resistance and strength. In further embodiments of the invention, different types of stainless steel form the tube 66 or the tube 66 is plated with another material, such as zinc or chromium.
As illustrated in
The illustrated embodiment of the fuel rail 14 is for use with a six-cylinder engine and includes six fuel injector cups 18 coupled to the fuel rail 14. As illustrated in
As illustrated in
A first end cap 90 is attached to the first end 38 of the fuel rail 14 and a second end cap 94 is attached to the second end 42 of the fuel rail 14 to enclose the chamber 34. In the illustrated embodiment, the first and second ends 38, 42 of the fuel rail 14 have substantially the same cross-sectional shape as the fuel rail 14, whereby the end caps 90, 94 have substantially the same cross-sectional shape as the fuel rail 14. In a further embodiment of the invention, the first and second ends 38, 42 have a different cross-sectional shape than the remainder of the fuel rail 14, such as circular, whereby the end caps 90, 94 will have substantially the same cross-sectional shape as the ends 38, 42 of the fuel rail 14. The end caps 90, 94 are attached to the fuel rail 14 by press-fitting the end caps 90, 94 to the first and second ends 38, 42 and laser welding the end caps 90, 94 to the fuel rail 14.
A fuel line tube 98 is attached to the first end cap 90 and is in communication with the chamber 34 of the fuel rail 14. The fuel line tube 98 provides a conduit for fuel from a fuel line (not shown) attached to a free end 102 of the fuel line tube 98 to the chamber 34 of the fuel rail 14. The fuel line tube 98 provides a quick connect to the fuel line. The fuel line tube 98 is press-fit to the end cap 90 and welded to the end cap 90. In a further embodiment of the invention, the fuel line tube 98 is attached along another portion of the fuel rail system 10, such as to the second end cap 94.
Mounting tabs 106 are attached to the sidewall 30 of the fuel rail 14 for coupling the fuel rail 14 onto an engine (not shown). The mounting tabs 106 are substantially S-shaped and include a base portion 110 for attachment to the fuel rail 14 and a flange portion 114 for attachment to the engine. The base portion 110 of the mounting tab 106 is spot-welded or tack welded to the sidewall 30 of the fuel rail 14, although other securing means known in the art may be employed. The flange portion 114 includes apertures 118 for receiving a fastener (not shown) to secure the fuel rail 14 to the engine. Any fastener known in the art may be used to secure the fuel rail 14 as described, for example, screws, nails, rivets, pins, posts, clips, clamps, inter-engaging elements, and any combination of such fasteners. In further embodiments of the invention, the flange portion 114 of the mounting tab 106 is welded to the engine or the mounting tab 106 has other shapes.
As illustrated in
The fuel rail assembly 140 includes a two fuel rails 14a and 14b. A fuel conduit 144 communicates with the chamber 34 of the first fuel rail 14a and the chamber 34 of the second fuel rail 14b. The fuel conduit 144 provides a crossover between the two fuel rails 14a, 14b. A first end 148 of the fuel conduit 144 is attached to the first end cap 90 of the first fuel rail 14a, and a second end 152 of the fuel conduit 144 is attached to the first end cap 90 of the second fuel rail 14b. A fuel line tube 156 is attached to the fuel conduit 144 to direct fuel to the fuel rail assembly 140 through the fuel conduit 144. In further embodiments of the invention, those skilled in the art will recognize that the fuel line tube may be attached anywhere on the fuel rail assembly, including one of the fuel rails.
The fuel rails 14 illustrated in
Various features of the invention are set forth in the following claims. For example, some fuel rail systems may require more than one self-damping fuel rail, fewer or more fuel injectors, or a flexible hose fuel conduit.
Number | Name | Date | Kind |
---|---|---|---|
4457280 | Hudson, Jr. | Jul 1984 | A |
4474160 | Gartner | Oct 1984 | A |
4519368 | Hudson, Jr. | May 1985 | A |
4570600 | Atkins et al. | Feb 1986 | A |
4660524 | Bertsch et al. | Apr 1987 | A |
5022372 | Imura et al. | Jun 1991 | A |
5024198 | Usui | Jun 1991 | A |
5027777 | De Bruyn et al. | Jul 1991 | A |
5090385 | Usui et al. | Feb 1992 | A |
5211149 | DeGrace et al. | May 1993 | A |
5617827 | Eshleman et al. | Apr 1997 | A |
6148798 | Braun et al. | Nov 2000 | A |
6205979 | Sims, Jr. et al. | Mar 2001 | B1 |
6354273 | Imura et al. | Mar 2002 | B1 |
6371083 | Rossi et al. | Apr 2002 | B1 |
6418909 | Rossi et al. | Jul 2002 | B1 |
6418910 | Nally et al. | Jul 2002 | B1 |
6427665 | Knoedl et al. | Aug 2002 | B1 |
6463911 | Treusch et al. | Oct 2002 | B1 |
6470859 | Imura et al. | Oct 2002 | B1 |
6497128 | Canfield et al. | Dec 2002 | B1 |
6497219 | Natsume | Dec 2002 | B1 |
6513500 | Braun et al. | Feb 2003 | B1 |
6513501 | Schwegler et al. | Feb 2003 | B1 |
6672286 | Miandoab et al. | Jan 2004 | B1 |
6889660 | Usui et al. | May 2005 | B1 |
6901914 | Becene et al. | Jun 2005 | B1 |
20010042538 | Rossi et al. | Nov 2001 | A1 |
20020053341 | Imura et al. | May 2002 | A1 |
20020083924 | Murphy | Jul 2002 | A1 |
20020108660 | Braun | Aug 2002 | A1 |
20030019477 | Bodenhausen et al. | Jan 2003 | A1 |
20030056759 | Davey | Mar 2003 | A1 |
20040226540 | Kreschel et al. | Nov 2004 | A1 |
Number | Date | Country |
---|---|---|
40 06 501 A 1 | Sep 1991 | DE |
3-179162 | Aug 1991 | JP |