Fuel rail assembly

Abstract

A fuel rail assembly for an internal combustion engine is disclosed. It comprises a plurality of fuel delivery lines branching off from a fuel rail, each fuel delivery line hydraulically coupling one fuel injector to an outlet port of the fuel rail. Each fuel delivery line has a one-piece pipe which extends from an outlet port of the fuel rail to the respective fuel injector. The pipe has a cylindrical connection section adjoining the respective outlet port and a cylindrical injector cup section in which a fuel inlet portion of the respective fuel injector is received. The connection section and the injector cup section have different hydraulic diameters.

Claims

1. A fuel rail assembly for an internal combustion engine comprising: an elongated tubular fuel rail with a plurality of outlet ports; a plurality of fuel injectors; a plurality of fuel delivery lines branching off from the fuel rail, each fuel delivery line hydraulically coupling one of the fuel injectors to one of the outlet ports; wherein each fuel delivery line has a one-pieced pipe, the pipe extending from a respective outlet port of the fuel rail to a respective fuel injector so that the pipe hydraulically couples the fuel injector to the fuel rail, and having a cylindrical connection section adjoining the respective outlet port and a cylindrical injector cup section in which a fuel inlet portion of the respective fuel injector is received, the connection section and the injector cup section having different hydraulic diameters; wherein the fuel rail assembly further comprises a plurality of reinforcement rings, each reinforcement ring fixed to a respective pipe adjacent to the injector cup section, and a plurality of spring clips, each spring clip bearing against a respective pipe and against a respective fuel injector for biasing the fuel injector toward or away from the pipe, wherein each spring clip has a ground plate which is snap-fit connected in a groove of the respective fuel injector to block axial movement of the ground plate relative to the fuel injector with respect to a longitudinal axis of the fuel injector, and an axially compliant leg which extends from the ground plate, is bent and bears against a respective reinforcement ring of the respective pipe so as to compress the axially compliant leg and bias the fuel injector in a direction toward or away from the pipe, and wherein each reinforcement ring comprises an annular disc section with upper and lower parallel surfaces and an inner radial side, and a frustoconical shaped section which extends from the inner radial side of the annular disc section and extends in tapering fashion from the annular disc section.

2. The fuel rail assembly of claim 1, wherein the reinforcement ring is fixed to the pipe by means of at least one of: a brazed connection, a welded connection and a threaded connection.

3. The fuel rail assembly of claim 2, wherein, the pipe has an end section which comprises an opening of the pipe through which the respective fuel injector extends to the injector cup section, the end section has an interface with the injector cup section and tapers from the opening to said interface, and the reinforcement ring has a tapering circumferential surface which adjoins the end section.

4. The fuel rail assembly of claim 3, wherein the pipe and the reinforcement ring are made from different materials.

5. The fuel rail assembly of claim 3, wherein the pipe is at least one of: stamped, deep drawn, extruded and cold-formed metal tube.

6. The fuel rail assembly of claim 3, wherein the pipe further comprises: a cylindrical intermediate section, which is arranged between the connection section and the injector cup section, and a bend between the intermediate section and the connection section so that cylinder axes of the intermediate section and the connection section are not parallel, wherein the intermediate section and the connection section have the same hydraulic diameter.

7. The fuel rail assembly of claim 6, wherein the pipe has a tapering interface region between the injector cup section and at least one of: the connection section and the intermediate section.

8. The fuel rail assembly of claim 1, wherein each spring clip is rotationally locked relative to the respective fuel injector by the snap-fit connected ground plate in the groove of said fuel injector, and each spring clip and the respective fuel delivery line have corresponding indexing elements, which rotationally lock the spring clip relative to said fuel delivery line.

9. The fuel rail assembly of claim 1, wherein the axially compliant leg of each spring clip bears against the respective reinforcement ring so as to compress the axially compliant leg and bias the fuel injector in an axial direction away from the pipe, relative to a longitudinal axis of the fuel injector.

10. The fuel rail assembly of claim 1, wherein the pipe has an end section which comprises an opening of the pipe through which the respective fuel injector extends to the injector cup section, the end section has an interface with the injector cup section and tapers from the opening to said interface, an inner surface of the frustoconical shaped section contacting an outer surface of the end section.

11. A fuel rail assembly for an internal combustion engine comprising: an elongated tubular fuel rail with a plurality of outlet ports; a plurality of fuel injectors; a plurality of fuel delivery lines branching off from the fuel rail, each fuel delivery line hydraulically coupling one of the fuel injectors to one of the outlet ports; wherein each fuel delivery line comprises a pipe, the pipe extending from a respective outlet port of the fuel rail to a respective fuel injector so that the pipe couples the fuel injector to the fuel rail, and having a connection section adjoining the respective outlet port and an injector cup section in which a fuel inlet portion of the respective fuel injector is received, the connection section and the injector cup section having different inner diameters; wherein the fuel rail assembly further comprises a plurality of reinforcement rings, each reinforcement ring fixed to a respective pipe adjacent to the injector cup section, and a plurality of spring clips, wherein each spring clip has a ground plate which is snap-fit connected in a groove of the respective fuel injector to block axial movement of the ground plate relative to the fuel injector with respect to a longitudinal axis of the fuel injector, and an axially compliant leg which extends from the ground plate, is bent and bears against a respective reinforcement ring of the respective pipe so as to compress the axially compliant leg and bias the fuel injector in a direction toward or away from the pipe, wherein the reinforcement ring comprises an annular disc section with upper and lower parallel surfaces and an inner radial side, and a frustoconical shaped section which extends from the inner radial side of the annular disc section and extends in tapering fashion from the annular disc section.

12. The fuel rail assembly of claim 11, wherein the axially compliant leg of each spring clip bears against the respective reinforcement ring so as to compress the axially compliant leg and bias the fuel injector in an axial direction away from the pipe, relative to a longitudinal axis of the fuel injector.

13. The fuel rail assembly of claim 11, wherein the pipe has an end section which comprises an opening of the pipe through which the respective fuel injector extends to the injector cup section, the end section has an interface with the injector cup section and tapers from the opening to said interface, and an inner surface of the frustoconical shaped section contacts an outer surface of the end section.

14. The fuel rail assembly of claim 11, wherein each spring clip is rotationally locked relative to the respective fuel injector by the snap-fit connected ground plate in the groove of said fuel injector, and each spring clip and the respective pipe have corresponding indexing elements, which rotationally lock the spring clip relative to said fuel delivery line.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1A shows a longitudinal section view of a fuel rail assembly according to a first exemplary embodiment,

(2) FIG. 1B shows a detail of FIG. 1B in a larger scale,

(3) FIG. 2A shows another longitudinal section view of the fuel rail assembly according to the first exemplary embodiment,

(4) FIG. 2B shows a detail of FIG. 2B in a larger scale,

(5) FIG. 3 shows a perspective view of a pipe of the fuel rail assembly according to first exemplary embodiment,

(6) FIG. 4 shows a perspective view of a reinforcement ring of the fuel rail assembly according to the first embodiment,

(7) FIG. 5 shows a longitudinal section view of a fuel rail assembly according to a second exemplary embodiment, and

(8) FIG. 6 shows a perspective view of a reinforcement ring of the fuel rail assembly according to the second exemplary embodiment.

DETAILED DESCRIPTION

(9) In the exemplary embodiments and in the figures, similar, identical or similarly acting elements are provided with the same reference symbols. In some figures, individual reference symbols may be omitted to improve the clarity of the figures.

(10) FIG. 1A shows a fuel rail assembly 3 for an internal combustion engine 1 in a longitudinal section view. FIG. 1B shows a detail of FIG. 1 in an enlarged scale.

(11) The fuel rail assembly 3 comprises an elongated tubular fuel rail 31 and a plurality of fuel injectors 7. The image plane of FIGS. 1A and 1B is parallel to an elongation direction of the tubular fuel rail and to longitudinal axes L of the fuel injectors 7. Only a portion of the fuel rail assembly 3, showing one fuel injector 7 of the plurality of fuel injectors 7, is shown in FIG. 1A.

(12) The fuel injectors 7 are positioned in receptacle bores of a cylinder head 5 of the internal combustion engine 1 so that they are operable to inject fuel directly into respective combustion chambers of the internal combustion engine 1. Each fuel injector 7 is hydraulically and mechanically connected to an outlet port 39 of the fuel rail 31 by means of a fuel delivery line 11.

(13) The fuel rail 31 is metallic; in particular it is made from steel. Fuel is supplied to the fuel rail 31 through an inlet fitting (not shown) on one axial end of the fuel rail 31 with respect to the elongation direction of the fuel rail 31. The opposite axial end of the fuel rail 31 is sealed by an end plug (not visible in FIG. 1A). The fuel rail may be fixed with respect to the engine 1 by means of a fixation lug (not shown). A sensor port tube (not shown) may branch off from the fuel rail 31, in particular for measuring fuel pressure in the fuel rail 31.

(14) The fuel delivery lines 11, of which only one is positioned in the portion of the fuel rail assembly which is visible in FIG. 1A are spaced apart from one another and follow one another in the elongation direction of the fuel rail 31. The fuel rail lines 11 hydraulically couple the fuel rail 31 to the fuel injectors 7. The fuel injectors 7 may also be held in place mechanically by the fuel rail assembly 3.

(15) All fuel delivery lines 11 are of identical construction. In particular, they consist of a pipe 41 and a reinforcement ring 50. The pipes 41 branch off from the fuel rail 31 at respective outlet ports 39 of the fuel rail.

(16) In the present embodiment, the outlet ports 39 each comprise a bore in a circumferential sidewall of the fuel rail 31 and an outlet port tube attached to an outer surface of the circumferential sidewall. The outlet port tube laterally surrounds the bore. In the present embodiment, the lateral dimension of the outlet port tube is larger than its axial dimension, i.e. its dimension in direction of the fuel flow.

(17) Each pipe 41 is a one-piece metal tube which is manufactured, for example, by deep drawing, stamping, cold-forming or molding. The pipe has a connection section 43, a bend 44, an intermediate section 45, an interface region 46, an injector cup section 47 and an end section 49 which follow one another in flow direction of the fuel through the pipe 41 from the fuel rail 31 to the fuel injector 7.

(18) The connection section 43 is shifted into the outlet port tube of the outlet port 39and in one development also into the bore in the circumferential wall of the fuel rail 31for hydraulically and mechanically connecting an upstream end of the pipe 41 to the fuel rail 31. The end section 49 has an opening 490 through which the fuel inlet portion 705 of the fuel injector 7 is shifted into the pipe 41 so that the fuel inlet portion 705 axially overlaps the injector cup portion 47 of the pipe 41.

(19) The fuel inlet portion 705 of the fuel injector 7 is circumferentially surrounded by the injector cup portion 47. The fuel injector 7 comprises a sealing element in the region of the fuel inlet portion 705. The sealing element is an elastomeric sealing ring which is held in position relative to a shoulder of the fuel injector 7 by a backup ring in the present embodiment. In the figures, the elastomeric sealing ring and the backup ring are drawn radially oversized so that they overlap with the circumferential wall of the pipe 41 in the figures. In fact, however, the sealing ring and the backup ring are radially compressed in the assembled state so that they are completely laterally surrounded by the circumferential inner surface of the injector cup section 47 of the pipe 41. The oversized representation in the figures is used to indicate the radial compression.

(20) The connection section 43 and the intermediate section 45 and the injector cup section 47 of the pipe 41 are cylindrical. The connection section 43 and the intermediate section 45 have a first hydraulic diameter which is defined by the diameter D.sub.1 of the cylindrical inner circumferential surface of the pipe 41 in the connection portion 43 and the intermediate portion 45, respectively. The injector cup section 47 has a second hydraulic diameter which is defined by the diameter D.sub.2 of the cylindrical circumferential inner surface of the pipe 41 in the injector cup section 47. The hydraulic diameter of the injector cup section 47 is larger than the hydraulic diameters of the intermediate section 45 and the connection section 43, i.e. D.sub.2>D.sub.1.

(21) Between the intermediate section 45 and the injector cup section 47, the interface region 46 is arranged, which is in the shape of a conical shell. The diameter of the inner circumferential surface of the interface region 46 expands from the first diameter D.sub.1 at an end of the interface region 46 where it merges with the intermediate section 45 to the second diameter D.sub.2 at the opposite end of the interface region 46, where it merges with the injector cup section 47.

(22) At its end remote from the interface region 46, the injector cup section 47 has an interface 492 with the end section 49. The end section is also a conical shell which widens in direction away from the interface 492 with the injector cup section 47 to the opening 490 of the pipe 41. The opening 490 is positioned at an axial end of the end section 49 remote from its interface 492 with the injector cup section 47.

(23) The conical end section 49, the cylindrical injector cup section 47, the interface region 46 and the intermediate section 45 are co-axial with respect to their central axis and also, in the present embodiment, with respect to the longitudinal axis L of the fuel injector 7. In top view along the longitudinal axis L, the fuel injector 7 is positioned laterally displaced relative to the fuel rail 31, in particular in a direction perpendicular to the elongation direction of the fuel rail 31. In order to bridge this offset, the pipe 41 has the bend 44 between the intermediate section 45 and the connection section 43 so that the cylinder axes of the connection section 43 and the intermediate section 45 are at an angle with respect to one another and the connection section 43 bridges the lateral distance between the fuel rail 31 and the fuel injector 7.

(24) The fuel delivery line 11 also has a reinforcement ring 50 which is fixed to the pipe 41 adjacent to the injector cup section 47. Specifically in the present embodiment, the reinforcement ring 50 has a tapering circumferential surface 501 which adjoins the conical outer circumferential surface of the end section 49. The reinforcement ring 50 is brazed and/or welded to the circumferential outer surface of the pipe 41.

(25) In the present embodiment, the reinforcement ring 50 is in the shape of a flat disc. In other words, it is delimited by two parallel surfaces which extend circumferentially around and perpendicular to the central axis of the reinforcement ring 50.

(26) The fuel rail assembly further comprises one spring clip 60 assigned to each fuel injector 7. The spring clip 60 has a ground plate 610 which positioned in a groove 710 of a housing of the fuel injector 7. The ground plate is shaped in particular as a radially compliant fork, which is sized such that it is elastically deformed when the ground plate 610 is shifted into the groove 710 and a snap-fit connection between the ground plate 610 and the fuel injector 7 is established when the ground plate 610 is fully assembled into the groove 710. In this way, axial movement of the ground plates 610 relative to the fuel injector 7 with respect to the longitudinal axis L is blocked.

(27) The ground plate 610 is spaced apart from the pipe 41 and the reinforcement ring 50 in longitudinal direction L. An axially compliant leg 620 of the spring clip 60 extends in curved fashion from the ground plate 610 to the fuel delivery line 11, where it is in contact with a lower surface of the reinforcement ring 50.

(28) The lower surface of the reinforcement ring 50 in particular extends around the opening 490 of the pipe 41 and is preferably in a common plane with the opening 490. The axially compliant leg 620 is dimensioned and shaped in such fashion that it is axially compressed by means of mechanical interaction with the reinforcement ring 50 and with the fuel injector 7 via the ground plate 610 in the assembled state of the fuel rail assembly 3. In this way, the spring clip 60 is operable to press the fuel injector 7 into the receptacle bore of the cylinder head 5, in a direction away from the pipe 41.

(29) The spring clip is 60 is rotationally locked relative to the fuel injector 7, for example by means of lateral flats of the groove 710 and a corresponding shape of the ground plate 610. Further, the reinforcement ring 50 has an indexing element 510, which is in the present embodiment a cutout that extends laterally inwards from an outer circumferential surface of the reinforcement ring 50. The spring clip 60 has a corresponding indexing element 630in the present embodiment a longitudinally elongated pinthat is received in the cutout of the reinforcement ring 50. In this way, the indexing elements 510, 630 of the reinforcement ring 50 and the spring clip 60 rotationally lock the spring clip 60 relative to the fuel delivery line 11. Consequently, the fuel injector 7 is rotationally locked relative to the fuel delivery line 11 due to the rotational locking between the fuel injector 7 and the spring clip 60 and between the spring clip 60 and the reinforcement ring 50.

(30) FIG. 5 shows one pipe 41 of a fuel delivery assembly 3 according to a second exemplary embodiment in a longitudinal section view. The fuel delivery assembly 3 according to the second exemplary embodiment corresponds in general to that of the first embodiment. The fuel injector 7, which is received with its fuel inlet portion 705 in the injector cup section 47, is omitted in FIG. 5.

(31) The fuel rail assembly 3 according to the second embodiment has a reinforcement ring 50 with a shape which is different from that of the reinforcement ring 50 of the fuel rail assembly 3 according to the first embodiment. FIG. 6 shows the reinforcement ring 50 of the fuel rail assembly 3 according to the second embodiment in a perspective view.

(32) In the second embodiment, the reinforcement ring 50 is not a flat disc. Instead, it has an angled cross-section. To put it differently, the shape of the reinforcement ring 50 is composed of a perforated disc section with upper and lower parallel surfaces facing in longitudinal direction and a conical section which mergers with the inner circumferential edge of the perforated disc section and extends in tapering fashion from the perforated disc in longitudinal direction L. In the present embodiment, the tapering circumferential surface 501 of the reinforcement ring 50 is comprised by the conical section. The conical section may terminate, at its axial end remote from the perforated disc section adjacent to the interface 492 of the section 49 with the cylindrical injector cup section 47.

(33) The invention is not limited to specific embodiments by the description on basis of these exemplary embodiments. Rather, it comprises any combination of elements of different embodiments. Moreover, the invention comprises any combination of claims and any combination of features disclosed by the claims.