WO1990003510A2

WO1990003510A2 - Fuel rail assemblies for internal combustion engines

Info

Publication number: WO1990003510A2
Application number: PCT/EP1989/001096
Authority: WO
Inventors: Randall M. Mahnke
Original assignee: Siemens Aktiengesellschaft
Priority date: 1988-09-29
Filing date: 1989-09-21
Publication date: 1990-04-05
Also published as: CA1336253C; WO1990003510A3

Abstract

Fuel rail assemblies (12, 70) include a tubular fuel rail (14, 16, 76) for supplying fuel to a fuel injector of an internal combustion engine. Rigid conduits (28, 36, 78) are coupled to the fuel rail (14, 16, 76) so as to allow relative rotational movements therebetween and thus permit, during production, the correction of any angular mismatch between the injectors and the engine with which the injectors are to be associated. A longitudinally extending, lateral ledge (64, 66) may be provided so as to support a clip (60) which retains the injectors in the fuel rail assembly during production. Countercurrent flow within some embodiments of the fuel rail assemblies (70) is provided by positioning an inner conduit (76) within an outer conduit (78) so as to establish therebetween a fuel flow passageway (79). Thus, the supply and discharge nipples for the fuel rail may be provided in close physical relationship with one another and thereby more easily facilitate their interconnection to a vehicle's fuel system during production.

Description

FUEL RAIL ASSEMBLIES FOR INTERNAL COMBUSTION ENGINES

FIELD OF THE INVENTION

The present invention is related to the field of internal combustion engines, and more particularly, to internal combustion engines which employ fuel injectors. In specific embodiments, the invention relates to means by which an available standby source of fuel is provided for fuel injectors of an internal combustion engine (such means usually being referred to in art parlance as a "fuel rail"). The fuel rails of this invention include especially adapted coupling assemblies so as to couple fuel supply/discharge conduits to the fuel rail to thereby allow relative rotational motion therebetween and hence facilitate assembly of the fuel rails to internal combustion engines.

BACKGROUND AND SUMMARY OF THE INVENTION

Fuel injected internal combustion engines have in recent years been employed by automotive manufacturers as a more fuel efficient alternative to conventional carbureted engines. Moreover, fuel injected internal combustion engines provide a more accurate means (as compared to carbureted engines) to control a variety of engine operating parameters via an on-board electronic control unit (ECU) .

Fuel is typically supplied to the injectors by means of one or more rigid conduits (usually referred to as "fuel rails" in art parlance). The fuel rails are thus adapted to receiving the injectors at spaced-apart locations along the fuel rail so as to be in alignment with respective positions of the intake ports of an internal combustion engine. In such a manner, fuel from the vehicle's fuel system may be supplied to the individual injectors via the fuel rail.

During production of fuel injected internal combustion engines, the fuel rail will usually have the injectors dependently attached thereto in some fashion (usually via a clip). This fuel rail/injector subassembly may then be mated with an engine block during assembly line production so that the injectors are positioned within respective intake ports of the engine.

Mating of the fuel rail/injecto.r subassembly usually presents little problems during production of in-line configured engines (e.g., a four cylinder engine in which all of the cylinders are oriented "in-line" relative to the engine block) . However, potential problems relating to angular mismatch as between the injectors of the fuel rail/injector subassembly and the intake ports of -the engine block in which the injectors are to be seated may occur with V-configured engines (e.g., six or eight cylinder engines in which one bank of cylinders is situated laterally of the other cylinder bank, with the respective cylinder banks being oriented in a V-shape as viewed from the end of the engine block). For these reasons, it would be very desirable if the fuel rail included the means by which any angular mismatch between the fuel rail/injector subassembly and the intake ports of the engine block could be corrected on line during manufacturing.

As indicated briefly above, fuel rails must ultimately -_>e connected to the vehicle's fuel system which usually entails connecting an inlet and an outlet of the fuel rail to "cruick connectors" of conduits (typically flexible conduits) associated with the supply and return sides, respectively, of the vehicle's fuel system. Hence, during production, it would also be very desirable if the inlet and outlet of the fuel rail were each closely located relative to one another so that the interconnection with the vehicle's fuel system may be more efficiently accomplished by an assembly line worker.

It is towards achieving such desired attributes of automotive fuel rails that the present invention is specifically directed.

According to one aspect of the present invention, a novel fuel rail is provided which includes the means by which angular mismatch between the fuel rail/injector subassembly is capable of being corrected on line during manufacture of the engine. At least one end of the fuel rail defines a recess in which an end of a rigid fuel conduit is accepted. The fuel conduit is itself provided with an annular flange which is retained in the recess of the fuel rail by means of a fixed-position, arcuately shaped retainer flange. The end of the retainer flange thus bears against the annular flange of the fuel conduit so as to retain the latter within the recess of the fuel rail, while yet also allowing relative rotational movements between the fuel rail and the fuel conduit. This relative rotational ovement may then be used during manufacture so as to correct any angular mismatch which may be present between the fuel rail/injector subassembly and the engine block.

Inlet and outlet nipples may also be provided

-•v closely adjacent one another according to another aspect of this invention. That is, the present invention also contemplates a fuel rail comprised of a pair of substantially concentrically disposed conduits which define therebetween an annular space through which fuel may flow. Means may be provided at a terminal end of the inner conduit so as to positionally concentrically retain it within the outer conduit, and to establish fluid communication between the inner conduit and the annular passageway. In such a manner, the fuel rails of this invention may establish countercurrent flow of fuel therewi hin.

These, as well as other aspects and advantages of this invention will become more clear after careful consideration is given to the detailed description of the preferred exemplary embodiments which follow. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Reference will hereinafter be made to the accompanying drawings wherein like reference numerals throughout the various FIGURES denote like structural -elements, and wherein;

FIGURI 1 is a top plan view of one specific exemplary embodiment of a fuel rail assembly according to the present invention;

FIGURE 2 is an end elevational view of the assembly shown in FIGURE 1 as taken along line 2-2 therein;

FIGURE 3 is another end elevational view of the assembly shown in FIGURE 1 as taken along line 3-3 therein;

FIGURE 4 is an enlarged cross-sectional view showing the means employed to couple fuel conduits to the fuel rails of the assembly shown in FIGURE 1;

FIGURE 5 is an enlarged detail view of another coupling means which may be employed according to this invention to couple conduits to a fuel rail;

FIGURE 6 is a top plan view of another specific fuel rail assembly according to the present invention;

FIGURE 7 is a cross-sectional elevational view of the terminal ends of the fuel rail shown in FIGURE 6;

FIGURE 8 is a cross-sectional end view taken along line 8-8 in FIGURE^" 6 showing the relationship between the fuel rail and a representative fuel injector;

FIGURE 9 is an enlarged partial cross-sectional view of another specific fuel rail assembly according to this invention; and

FIGURE 10 is an end view of the fuel rail assembly shown in FIGURE 9 as taken along line 10-10 therein.

DETAILED DESCRIPTION OF THE PREFERRED EXEMPLARY EMBODIMENTS

An exemplary internal combustion engine 10 which employs one preferred embodiment of the fuel rail assembly 12 according to the present invention is shown in accompanying FIGURES 1-3. The assembly 12 just happens to be associated with a V-6 configured engine 12, but other engine configurations (including in-line configured engines) could employ the beneficial^' attributes of this invention to be discussed in greater detail below.

Since the assembly 12 is depicted in accompanying FIGURES 1-3 as being employed with a V-configured engine, a pair of rigid elongate tubular fuel rails 14 and 16 are provided in substantially parallel disposition relative to one another. That is, fuel rail 14 supplies fuel to injector ports 14a-14c in which an inlet end of fuel injectors 20 (see FIGURES 2 and 3) is received so as to service one bank of combustion chambers lOa-lOc of engine 10, respectively. On the other hand, fuel rail 16 supplies fuel to injector ports 15a-16c in which an ii let end of fuel injectors 22 (see FIGURES 2 and 3) is received so as to service the other bank of combustion chambers lOd-lOf of engine 10, respectively.

Fuel rails 14 and 16 are fluid-connected to one another at their respective ends 24 and 26 via a rigid conduit 28. In the embodiment shown, conduit 28 is in the form of a shallow U-shaped element so as to maintain the substantially parallel relationship between the rails 14 and 16. However, other configurations of conduit 28 are possible in dependence upon the particular fuel path needed for a particular engine design. A supply nipple 30 is coupled to the end 32 of fuel rail 14 (which is opposite to end 24) and is adapted to being interconnected to the supply side of a vehicle's fuel system via flexible or rigid conduit (not shown) . The end 34 of fuel rail 16 is fluid-connected via rigid conduit 36 to a fuel regulator 38, which itself is preferably rigidly coupled to rail 14 via mounting bracket 40.

As will be appreciated, fuel is supplied coaxially to rail 14 via supply nipple 30 (i.e., in the direction of arrow 42 in FIGURE 1), flows through rail 14 so as to supply fuel to the injectors 20 associated therewith. Fuel will also flow from rail 14 to rail 16 via conduit 28 where it is supplied to the injectors 22 via ports 16a-16c. The fluid circuit is then completed by means of the fuel flowing from rail 16, consecutively through conduit 36 and regulator 38, and then being discharged from regulator 38 to the return side of a vehicle's fuel system (not shown) via discharge nipple 42 in the direction of arrow 44.

Important to the present invention is the coupling means 46 employed to couple the ends of conduit 28 to the respective ends 24 and 26 of fuel rails 14 and 16, in addition to coupling an" end of conduit 36 to end 34 of fuel rail 16 and/or supply nipple 30 to end 32 of fuel rail 14. The preferred coupling means 46 employed in the present invention is shown in greater detail in accompanying FIGURE 4.

As is seen in FIGURE 4, an axial recess 48 is formed in end 26 of fuel rail 16 so as to receive a terminal end 28a of conduit 28. In such a manner, fuel will flow from the end 28a of conduit 28 in substantially coaxial relationship to interior chamber 50 of fuel rail 16 (see FIGURE 2 ) . End 28a of conduit 28 includes an integral annular flange 52 which is maintained within recess 48 by means of a retainer 54. A suitable bolt 55 rigidly connects retainer 54 to end 26 of fuel rail 14. Retainer 54 also includes an arcuately shaped flange 56 so as to provide a saddle support for conduit 28. Flange 56 is moreover accepted within the recess 48 of fuel rail end 26 and bears against annular flange 52 of conduit end 28a. A suitable O-ring seal 58 seals the end 28a and fuel rail 16 against fuel leakage from the recess 48.

The bearing relationship between retainer flange 56 and annular flange 52 of conduit end 28a axially restrains conduit end 28a against separation from the recess 48 of fuel rail end 26. In addition, the arcuate saddle support provided by means of retainer flange 56 allows relative rotational movements between the conduit 28 and the fuel rail 16. During production therefore, any angular mismatch which may be present between the injectors 22 and the engine 10 may be corrected by simply pivoting the fuel rail 16 and/or conduit 28 until the desired angular orientation is achieved.

The description above with respect to the coupling means 46 associated with end 26 of fuel rail 16 is equally applicable to the coupling means 46 associated with the other end 34 of fuel rail 34, in addition to coupling means 46 associated with ends 24 and 32 of fuel rail 14. Suffice it to say that wherever a rigid conduit is to be coupled to either of the fuel rails 14 or 16, it is preferred according to the present invention that the coupling means 46 be of the type described above with reference to FIGURE 4 (i.e., so as to permit the beneficial relative rotational movements between the rigid conduits and the fuel rail). During engine production, the injectors 20 and 22 will be coupled to the fuel rails 14 and 16, respectively. That is, the injectors 20 and 22 will be received in a respective one of ports 14a-14c and 16a-16c and will be maintained therewithin via clips 60. In this regard, it will be observed that the fuel rails 14 and 16 each define a lateral, axially extending ledge surface 64, 66, respectively. One end of the clip 60 is thus supported by a respective ledge surface 64, 66, while the other end thereof engages a respective one of the injectors 20, 22. The clips 60 thus ensure that the injectors 20 and 22 will be retained in their respective ports 14a-14c and 16a-16c during engine production.

FIGURE 5 shows another specific embodiment of the coupling means 46' which may be employed according to this invention so as to couple a rigid conduit 28' to a tubular fuel rail 16' to allow for relative rotational movements about the longitudinal axis of the latter. As was similar to the conduit 28 described above with particular reference to FIGURE 4, the conduit 28^r in the embodiment of FIGURE 5 includes a terminal end 28a' and an integral annular flange 52'.

A connector fitting 60 is rigidly coaxially attached to the terminal end 16" of fuel rail 16' and defines an inner cylindrical surface 61 sized and configured so as to closely match the external surface of terminal end 28a. The fitting 60 also includes an annular beveled stop 62 which provides a seat for the annular beveled edge 63 of terminal end 28a. Thus, stop 62 limits the axial extent to which end 28a may be inserted into the fitting 60, while also providing a bearing surface for edge 63 during rotational movements of conduit 28' and/or fuel rail 16'.

An annular recessed surface 64 is defined at the end of fitting 60 opposite to its stop 62 and is adapted to receiving a suitable O-ring seal 65 therein. The annular flange 52' of conduit 28' is maintained in sealing contact with the O-ring seal 65 by means of an inwardly turned (i.e., towards the longitudinal axis of conduit 16') integral retaining flange 66. Slight axial play is allowed for flange 52' within the recessed surface 64 of fitting 60 so that the former is not "pinched" against the O-ring seal 65 to an extent which would preclude relative rotational movements between the conduit 28' and the fuel rail 16' . Of course, the axial play should not be of such a magnitude whereby the sealing contact between the flange 52' and the O-ring seal 65 could be lost. The retaining flange 66 is preferably annular (i.e., without discontinuities) but could be formed of a number of segments without detrimentally affecting its .intended function.

The coupling assembly 46' shown in FIGURE 5 is most conveniently fabricated by sliding the terminal end 28a' into the fitting 60 (the latter having already been fixed within the end 16" of fuel rail 16' ) with the O-ring seal 65 being positioned about the terminal end 28a' near the annular flange 52'. At this point, the retaining flange is not inwardly turned as shown in FIGURE 5, but instead extends outwardly from the fitting 60 substantially parallel to the axis of fuel rail 16' . Thereafter, the fitting 60/fuel rail 16'/conduit 28' subassembly may then be supported upon a work table via support flanges 67 formed on the fitting 60 so that a forming tool may be brought into contact with the retaining flange 66 to cause it to turn inwardly to the extent shown in FIGURE 5.

It will be observed in FIGURE 1, that the • » supply and discharge nipples 30 and 42 are relatively physically close to one another so as to facilitate their connection to a vehicle's fuel system. Other embodiments of this invention which also achieve close physical association of supply and discharge conduits is shown in accompanying FIGURES 6-10. The fuel rail assemblies 70 and 120 shown in FIGURES 6-8 and FIGURES 9-10, respectively, are also particularly well suited for use with internal combustion engines having cylinders configured in an "in-line" manner.

As is seen in FIGURES 6-8, the fuel rail assembly 70 includes an inlet nipple 72 and an outlet nipple 74 for respective fluid connection to the supply and return sides of a vehicle's fuel system. The supply nipple 74 is preferably an integral extension of an inner conduit 76 as can be seen more clearly in accompanying FIGURE 7. The supply nipple 72 (and hence the inner conduit 76) is preferably concentrically disposed within an outer conduit 78 so as to establish an annular passageway 79 therebetween. The inner conduit 76 is retained within the outer conduit 78 of the fuel rail assembly 70 at its supply end 70a by means of an inwardly turned flange 80. Fluid leakage is prevented at end 70a by means of an O-ring seal 82 positioned between an axially separated pair of annular flanges 84, 86 associated with the inner conduit 76.

The inner conduit 76 extends (preferably coaxially) within the outer conduit 78 to closely adjacent the terminal end 70b of the fuel rail assembly 70. The terminal end 70b is closed by means of a diagnostic fitting 88 (which serves to allow measurement of the pressure which may exist within the fuel circuit established by the fuel rail 70) and is sealed against fuel leakage thereat by means of an O-ring seal 90 positioned between a pair of axially spaced apart annular flanges 92, 94. The fitting 88 is retained within the terminal end 70b by means of an inwardly turned flange 96 in a manner similar to flange 80 employed at end 70a to retain the supply nipple 72.

The downstream end of inner conduit 76 terminates in a number (preferably pairs of) radially flared segments 98. Each of the segments 98 is formed by removing adjacent material from the downstream end of inner-conduit 76, and then flaring the remaining material radially outward. A portion of each segment 98 will thus contact the inner surface 100 of the outer conduit 78 so as to positionally maintain the inner conduit 78 in its substantially coaxial relationship within outer conduit 78. Adjacent ones of the segments 98 will also define therebetween respective open regions 104 to thereby establish fluid communication between the inner conduit 76 and the annular passageway 79.

Fuel which is supplied to the inlet nipple 72 flows through the inner conduit 76 towards its downstream end where it exits via the open regions 104 and then flows through the annular passageway 79. As is perhaps more clearly seen in FIGURE 8, the annular passageway 79 is fluid-connected to the injectors 106 via respective ports 108 (only one such port 108 and its associated injector 106 are shown in FIGURE 7 as being representative of a number of the same). Fuel not supplied to the injectors 106 then flows to closely adjacent the supply end 70a where it is directed to a fuel regulator 110 via an outlet opening 112 (see FIGURE 6). After flowing through the regulator 110, the fuel is then discharged to the return side of the vehicle's fuel system via the discharge nipple 74.

It will be observed in FIGURES 6 and 8 that the fuel rail 70 may also define a longitudinally extending, lateral ledge surface 114 so as to support one end of a clip member (not shown in FIGURES 6-8) for maintaining the injectors 106 within their respective-ports 108. Thus, the fuel rail assembly 70 shown in FIGURES 6-8 may be provided with a lateral ledge surface to accomplish a similar purpose as the ledge surfaces described above with reference to the embodiment of this invention shown in FIGURES 1-4. The nipple 72/inner conduit 76 may also be mounted within the outer conduit 78 via flange 80 so that the former structures are capable of rotating relative to the latter structure and thereby allow correction of any angular mismatch between the injectors 106 and the engine during production.

Accompanying FIGURES 9 and 10 show another embodiment of a fuel rail assembly 120 according to this invention which provides for close physical relationship between a fuel supply nipple 122 and a fuel discharge nipple 124. The fuel rail assembly 120 includes an inner conduit 126 which is positioned within an outer conduit 128 so as to define therebetween an eccentric annulus 130. The inlet end 126a of conduit 126 is fitted into a blind hole 132 formed in a baffle plug 134 located within the outer conduit 128 near the discharge nipple 124. The supply nipple 122 communicates with the blind hole 132 by entering the same at substantially a right angle relative to the elongate axis of the inner conduit 126. In such a manner, the supply nipple is fluid-connected to the inner conduit 126.

The baffle plug 134 includes one or more through apertures 138 which fluid-connect the eccentric annulus 130 and the discharge nipple 124. The downstream end of the inner conduit 126 (not shown in FIGURE 9) is preferably comprised of at least one radially outwardly flared segment so as to positionally maintain the inner conduit 126 within the outer conduit 128 and to establish fluid connection at the downstream end of conduit 126 with the eccentric annulus 130 (i.e., in a manner similar to the functions provided by means of the segments 89 shown in FIGURE 7).

Therefore, fuel entering the supply nipple 122 is directed- at substantially a right angle via blind hole 132 into the inlet end 126a of inner conduit 126 and then flows the length of inner conduit 126 towards its downstream end. The fuel then enters the eccentric annulus 130 at the downstream end of inner conduit 126 and flows towards the baffle plug 134 (i.e., in a direction countercurrent to the fuel flow within the inner conduit 126). The fuel then flows through the apertures 138 and into the supply nipple 124 where it may be directed to a downstream fuel pressure regulator (not shown) .

The reader will now undoubtedly realize the advantages which may be achieved by means of the fuel rail assemblies according to this invention. Thus, while the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments. Instead, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the_ appended claims.

Claims

WHAT IS CLAIMED IS:

1. A fuel rail assembly for supplying fuel to fuel injectors of an internal combustion engine comprising: a tubular fuel rail defining an elongate axis and including means for receiving a portion of said fuel injectors so as to direct fuel thereto; and a rigid fuel conduit; characterized in that a coupling means couples said fuel conduit and said fuel rc_il in a sealed end-to-end manner so that fuel can pass between the two without leaking out of the assembly and the coupling means allows relative rotational movements of said fuel conduit and said fuel rail about said defined elongate axis while the fuel rail and conduit remain coupled in sealed end-to-end manner.

2. A fuel rail assembly as in claim 1, characterized in that said coupling means includes annular flange means formed on said rigid fuel conduit and accepted within an end of said tubular fuel rail, and retaining flange means integrally formed on said end of said tubular fuel rail, said retaining flange means being inwardly turned relative to said defined elongate axis for retaining said annular flange means of said rigid fuel conduit within said tubular fuel rail while yet allowing relative rotational movements between said conduit and fuel rail about said defined axis.

3. A fuel rail assembly as in claim 1, characterized in that said coupling means includes; a recess defined in one end of said fuel rail? an annular flange associated with one end of said fuel conduit and accepted within said defined recess of said fuel rail; and retainer means fixed to said one end of said fuel rail for retaining said annular flange within said defined recess of said fuel rail while yet allowing said relative rotational movements to occur between said fuel rail and said fuel conduit.

4. A fuel rail assembly as in claim 3, characterized in that said retainer means includes an arcuate retainer flange accepted within said defined recess of said fuel rail to provide a saddle support for said fuel conduit, said retainer flange terminating in an arcuate end which bears against said annular flange of said fuel conduit, whereby said fuel conduit is retained within said defined recess but said rotational movements between said fuel rail and fuel conduit are allowed.

5. A fuel rail assembly as set forth in claim 1 characterized by: a second tubular fuel rail disposed substantially parallel to the first one including means for receiving a portion of said fuel injectors so as to supply fuel thereto; a second coupling means for coupling said rigid fuel conduit to said second fuel rail in a sealed end-to-end manner while allowing for relative rotational movements between said fuel rails and said full conduit about respective axes of said fuel rails.

6. A fuel rail assembly for an internal combustion engine comprising, in combination: plural fuel injectors; an elongate tubular fuel rail having means for receiving said fuel injectors at spaced locations therealong so as to supply fuel thereto; characterized in that said fuel rail defines in the vicinity of said fuel injectors an axially extending ledge surface; and said fuel rail assembly also comprises clip means having an end engaged with, and supported by, said ledge surface, and an opposite end engaged with respective ones of said fuel injectors for retaining said fuel injectors in said spaced locations relative to said fuel rail.

7. A fuel rail for supplying fuel to injectors of an internal combustion engine comprising: a pair of rigid tubular conduits, characterized in that one of said conduits is disposed within the other of sa d conduits so as to establish therebetween a passageway through which fuel may flow; and means associated with a terminal end of said one conduit positionally maintain said disposition of said one conduit within said another conduit, and establish fluid communication between said one conduit and said passageway, whereby fuel may flow countercurrently within said fuel rail.

8. A fuel rail as in claim 7, characterized in that said means includes at least one pair of radially flared segments integral with said terminal end of said one conduit, said flared segments having a portion in contact with said other conduit, said flared segments defining therebetween respective circumferentially extending open regions which fluid-connect said one conduit to said passageway.

A fuel rail as in claim 7, further characterized by: a supply nipple; a discharge nipple; and a baffle plug located within said other conduit, said baffle plug including (i) means defining a blind hole which fluid connects said supply nipple and said one conduit, and (ii) means defining at least one through aperture which fluid connects said established passageway and said discharge nipple. 10. An automotive fuel rail characterized by: a supply nipple; a discharge nipple; a first rigid tubular conduit; a second rigid tubular conduit housed within said first conduit and establishing therebetween a fuel flow passageway; means located near a downstream end of said second conduit for establishing fluid connection between said second conduit and said fuel flow passageway; and baffle plug means positioned within said first conduit which (i) defines a blind hole for fluid connecting said supply nipple and an upstream end of said second conduit, and (ii) defines at least one through aperture for fluid connecting said established fuel flow passageway and said discharge nipple.