The present disclosure relates to a fuel system; more particularly to such a fuel system which includes a fuel injector and a fuel distribution conduit; and even more particularly to such a fuel system which provides a fuel-tight connection between the fuel injector and the fuel distribution conduit.
Fuel injection systems that deliver fuel to fuel consuming devices, for example internal combustion engines, have been known for many years. In modern internal combustion engines, it is increasingly common to provide fuel injectors which inject fuel, for example gasoline, directly into combustion chambers of the internal combustion engine. These internal combustion engines commonly include multiple combustion chambers, and consequently, each combustion chamber is provided with a respective fuel injector to inject fuel therein. A common conduit, typically referred to as a fuel rail, includes an inlet which receives fuel from a fuel source, such as one or more fuel pumps, and also includes a plurality of outlets, each of which is connected to a respective one of the fuel injectors.
Fuel injectors in gasoline fuel injection systems currently are predominantly sealed to a fuel distribution conduit, which supplies fuel to the fuel injector from the fuel rail, by an O-ring which is made of an elastomeric material. One such arrangement which uses an elastomeric O-ring is shown in United States Patent Application Publication No. US 2017/0350358 to Bayer et al. While O-rings may be adequate for sealing in current systems which operate below 35 MPa, in order to meet more stringent emissions requirements and fuel economy demands, gasoline fuel injection systems are expected to exceed 35 MPa and will likely exceed 50 MPa. Sealing with an elastomeric O-ring in systems using these elevated pressures may be difficult. Consequently, metal-to-metal sealing arrangements are being explored to provide robust sealing between the fuel injector and the fuel supply conduit. Many metal-to-metal sealing arrangements are known for joining a first metal conduit to a second metal conduit. Such arrangements may include an external thread formed on the first metal conduit while the second metal conduit includes a radially enlarged region which is used to engage a connection nut having internal threads. Consequently, when the connection nut is tightened, force from the connection nut is transferred through the radially enlarged region of the second metal conduit, thereby causing complementary sealing surfaces of the first metal conduit and the second metal conduit to be sealingly compressed against each other. One such arrangement is shown in United States Patent Application Publication No. US 2008/0042434 A1 to Kenny. However, such arrangements require the radially enlarged region to be formed after the nut has been applied to second metal conduit. This may be accomplished by deformation of the second metal conduit or by fixing another component to the second metal conduit. While this may be practical when the second metal conduit is thin-walled tubing, this approach may not be practical when the second metal conduit is integrally formed with the fuel rail, for example in a casting or forging operation or is integrally formed with the fuel injector since deformation may result in damage to sensitive internal components or may alter fuel spray characteristics of the fuel injector. Furthermore, arrangements such as those disclosed by Kenny may require multiple interfaces to be sealed which results in a higher risk of fuel leakage.
What is needed is an arrangement for joining a fuel injector to a fuel distribution conduit which minimizes or eliminates one or more of the shortcomings set forth above.
Briefly described, a fuel supply system is provided for supplying fuel to a fuel consuming device. The fuel supply system includes a fuel injector having a fuel injector inlet conduit, a nozzle opening, and a valve needle which is moveable to selectively permit and prevent flow of fuel from the fuel injector inlet conduit through the nozzle opening, the fuel injector inlet conduit extending along an axis from a first end which is most-distal from the nozzle opening and the fuel injector inlet conduit having a fuel injector inlet conduit shoulder which is traverse to the axis; a fuel distribution conduit which supplies fuel to the fuel injector, the fuel distribution conduit having external threads thereon; a connection nut having internal threads which are complementary to, and threadably engaged with, the external threads of the fuel distribution conduit, the connection nut also having a connection nut internal shoulder which is traverse to the axis; and a first ring sector and a second ring sector which each engage both the fuel injector inlet conduit shoulder and the connection nut internal shoulder such that tightening of the connection nut causes the first ring sector and the second ring sector to be compressed between the fuel injector inlet conduit shoulder and the connection nut internal shoulder. The fuel system described herein provides for robust sealing at ever-increasing pressures while providing simple construction. The fuel system described herein may also allow for minimal design change to existing fuel injector designs, which had previously used convention elastomer O-rings to achieve sealing, to be changed to a metal-to-metal sealing interface. Such design change may be limited to altering the outer profile of the fuel injector inlet conduit. Consequently, minimal manufacturing equipment change may be required to change the fuel injector design to accommodate a metal-to-metal sealing interface.
This invention will be further described with reference to the accompanying drawings in which:
Referring initially to
Referring now to
Now with reference to
An outer periphery of fuel distribution conduit 58 includes external threads 62 thereon. Furthermore, fuel distribution conduit 58 includes a fuel distribution conduit sealing surface 64 which mates with fuel injector inlet conduit 50 to provide a fuel-tight seal therebetween which prevents fuel leakage as will be described in greater detail later. As illustrated herein, fuel distribution conduit sealing surface 64 may be frustoconical in shape and concave in nature, however, may alternatively be other shapes such as frustospherical or convex in nature.
Fuel injector inlet conduit 50 is tubular and extends along a fuel injector inlet conduit axis 50a which is nominally coincident with fuel distribution conduit axis 58a and is shown as such in the figures, however, some angular or lateral misalignment may be accommodated by the connection arrangement used to connect fuel injector inlet conduit 50 to fuel distribution conduit 58. Fuel injector inlet conduit 50 extends along fuel injector inlet conduit axis 50a from a first end 50b which is most-distal from nozzle openings 30, i.e. first end 50b is the furthest-most portion of fuel injector inlet conduit 50 from nozzle openings 30. Fuel injector inlet conduit 50 includes a fuel injector inlet conduit shoulder 50c which is traverse to fuel injector inlet conduit axis 50a and faces in a direction away from first end 50b. Fuel injector inlet conduit shoulder 50c is formed by an area of reduced diameter which is spaced axially away from first end 50b.
Furthermore, fuel injector inlet conduit shoulder 50c may be radiused as shown at its radially outward extent. Fuel injector inlet conduit 50 also includes a fuel injector inlet conduit sealing surface 50d which mates with fuel distribution conduit sealing surface 64. As illustrated herein, fuel injector inlet conduit sealing surface 50d is a radiused corner initiating at first end 50b, however, fuel injector inlet conduit sealing surface 50d may be any shape which complements fuel distribution conduit sealing surface 64 to mate in a fluid-tight interface.
In order to sealingly compress together fuel injector inlet conduit sealing surface 50d and fuel distribution conduit sealing surface 64, fuel system 10 includes a connection nut 66, a first ring sector 68, and a second ring sector 70. In the paragraphs that follow, the features of connection nut 66, first ring sector 68, and second ring sector 70 will be described in greater detail.
Connection nut 66 is made of a metal material and includes a connection nut upper portion 66a which circumferentially surrounds fuel distribution conduit 58 and a connection nut lower portion 66b which circumferentially surrounds fuel injector inlet conduit 50 such that connection nut 66 extends from a connection nut upper end 66c which is distal from nozzle openings 30 to a connection nut lower end 66d which is proximal to nozzle openings 30. Connection nut 66 includes a connection nut central passage 66e extending axially therethrough from connection nut upper end 66c to connection nut lower end 66d. Connection nut 66 includes internal threads 66f within connection nut central passage 66e such that internal threads 66f are located within connection nut upper portion 66a. Internal threads 66f are complementary to, and are threadably engaged with, external threads 62 of fuel distribution conduit 58. It should be noted that the smallest portion of connection nut central passage 66e in the radial direction, i.e. the portion of connection nut central passage 66e which is proximal to connection nut lower end 66d, is sized to allow fuel injector inlet conduit 50 to be inserted thereinto at least until fuel injector inlet conduit shoulder 50c is located therein. It should also be noted that prior to connection nut 66 being tightened, connection nut central passage 66e is sized to allow angular misalignment between fuel injector 20 and fuel distribution conduit 58 which may exist during mounting of fuel rail 18 to cylinder head 26.
After internal threads 66f, connection nut central passage 66e includes a connection nut first surface 66g which is inclined relative to fuel distribution conduit axis 58a such that connection nut first surface 66g converges toward fuel distribution conduit axis 58a in a direction from connection nut upper end 66c to connection nut lower end 66d. As shown in the figures, connection nut first surface 66g may be frustoconical in shape. At the end of connection nut first surface 66g which is proximal to connection nut lower end 66d, connection nut first surface 66g intersects with a connection nut second surface 66h which is inclined relative to fuel distribution conduit axis 58a such that connection nut second surface 66h converges toward fuel distribution conduit axis 58a in a direction from connection nut lower end 66d to connection nut upper end 66c. As shown in the figures, connection nut second surface 66h may be frustoconical in shape. Together, connection nut first surface 66g and connection nut second surface 66h form a connection nut internal shoulder which is traverse to fuel injector inlet conduit axis 50a and fuel distribution conduit axis 58a.
As may be most apparent from
Second ring sector 70 is substantially identical to first ring sector 68, and as a result, the following description will mirror the description of first ring sector 68. Second ring sector 70 is a sector of a ring. Preferably, second ring sector 70 is a 180° or less sector of a ring, however, the sum of first ring sector 68 and second ring sector 70 does not exceed 360°. Second ring sector 70 includes a second ring sector inner periphery 70a which is concave and arc-shaped and a second ring sector outer periphery 70b which is convex and arc-shaped. Second ring sector 70 includes a second ring sector first surface 70c which engages connection nut first surface 66g. As illustrated in the figures, second ring sector first surface 70c may be complementary to connection nut first surface 66g; i.e. second ring sector first surface 70c is frustoconical and formed at the same angle as connection nut first surface 66g. Second ring sector 70 also includes a second ring sector second surface 70d which intersects with second ring sector first surface 70c and which engages connection nut second surface 66h. As illustrated in the figures, second ring sector second surface 70d may be complementary to connection nut second surface 66h; i.e. second ring sector second surface 70d is frustoconical and formed at the same angle as connection nut second surface 66h. Second ring sector second surface 70d extends to second ring sector inner periphery 70a and intersects with a second ring sector third surface 70e. Second ring sector third surface 70e may be substantially parallel to second ring sector first surface 70c and engages fuel injector inlet conduit shoulder 50c. Second ring sector third surface 70e may have a shape which is complementary to fuel injector inlet conduit shoulder 50c, for example frustoconical or frustospherical, thereby providing for retention of fuel injector 20 while allowing for angular misalignment between fuel injector 20 and fuel distribution conduit 58.
As mentioned previously, the sum of first ring sector 68 and second ring sector 70 does not exceed 360°. The sum of first ring sector 68 and second ring sector 70 is preferably in the range of 350° to 360°, however, the sum of first ring sector 68 and second ring sector 70 may be less than 350° depending on the pressure of fuel that is supplied to fuel injector 20 and therefore depending on the force first ring sector 68 and second ring sector 70 must resist to counteract the torque applied to connection nut 66 to a achieve a leak-free connection between fuel injector inlet conduit 50 and fuel distribution conduit 58. As a result, a practitioner of ordinary skill in the art would be capable of determining the extent to which first ring sector 68 and second ring sector 70 need to surround fuel injector inlet conduit 50. It should also be noted that first ring sector 68 and second ring sector 70 preferably have equal angular lengths, thereby allowing a single design to be used for both first ring sector 68 and second ring sector 70. First ring sector 68 and second ring sector 70 are preferably made of a metal material, but may alternatively be made of a polymer such as nylon.
Assembly of fuel injector 20 to fuel rail 18 will now be described. In a first step as shown in
While fuel distribution conduit 58 has been embodied herein as being an integral and unitary element with fuel rail 18, it should be understood that fuel distribution conduit 58 may alternatively be a pipe that is formed independent of fuel rail 18 and sealed thereto. In a further alternative, fuel distribution conduit 58 may be a supply conduit which is not connected to a fuel rail, but rather receives fuel directly from a fuel pump.
While first ring sector 68 and second ring sector 70 have been described and illustrated herein as having a particular cross-sectional shape, it should be understood that this has been provided for exemplary purposes only and numerous other shapes may alternatively be utilized. By way of non-limiting example only, first ring sector 68 and second ring sector 70 may have cross-sectional shapes that are circular, elliptical, square, rectangular, regular polygonal, irregular polygonal, or combinations thereof.
Use of connection nut 66, first ring sector 68, and second ring sector 70 as disclosed herein to connect fuel injector 20 to fuel rail 18 provides for robust sealing at ever-increasing pressures while providing simple construction. This arrangement may also allow for minimal design change to existing fuel injector designs, which had previously used convention elastomer O-rings to achieve sealing, to be changed to a metal-to-metal sealing interface. Such design change may be limited to altering the outer profile of fuel injector inlet conduit 50. Consequently, minimal manufacturing equipment change may be required to change the fuel injector design to accommodate a metal-to-metal sealing interface.
While the invention has been described by reference to various specific embodiments, it should be understood that numerous changes may be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the invention not be limited to the described embodiments, but rather only to the extent set forth in the claims that follow.
Number | Name | Date | Kind |
---|---|---|---|
4454711 | Ben-Porat | Jun 1984 | A |
4832376 | Sugao | May 1989 | A |
5752486 | Nakashima | May 1998 | A |
5903964 | Uematsu | May 1999 | A |
6070618 | Iwabuchi | Jun 2000 | A |
6286556 | Kato | Sep 2001 | B1 |
6415768 | Usui | Jul 2002 | B1 |
6431608 | Kato | Aug 2002 | B1 |
6843275 | Kato | Jan 2005 | B2 |
7735473 | Kato | Jun 2010 | B2 |
8186724 | Kato | May 2012 | B2 |
8196967 | Seifert et al. | Jun 2012 | B2 |
8640673 | Male | Feb 2014 | B2 |
20040135368 | Furugen | Jul 2004 | A1 |
20050284447 | Usui | Dec 2005 | A1 |
20080042434 | Kenny | Feb 2008 | A1 |
20110108005 | Nishizawa | May 2011 | A1 |
20160102641 | Harter | Apr 2016 | A1 |
20170350358 | Bayer et al. | Dec 2017 | A1 |
20180094614 | Tadokoro et al. | Apr 2018 | A1 |
Number | Date | Country |
---|---|---|
102705605 | Oct 2012 | CN |