GB2581156A

GB2581156A - Fuel injection system and a supply rail body thereof

Info

Publication number: GB2581156A
Application number: GB1901584.1A
Authority: GB
Inventors: Akin Levent; Güleryüz Begüm; Iyiuyarlar Bora; Turan Kivanc
Original assignee: Delphi Technologies IP Ltd
Current assignee: Delphi Technologies IP Ltd
Priority date: 2019-02-05
Filing date: 2019-02-05
Publication date: 2020-08-12
Anticipated expiration: 2039-02-05
Also published as: GB2581156B; GB201901584D0

Abstract

A supply rail body 4 for a fuel injection system, the supply rail body 4 comprising a body section defining a high-pressure fuel gallery 8; an outlet bore 24 defining an injector interface region 26 for connecting a respective fuel injector 20, wherein the outlet bore 24 is offset from the fuel gallery 8. A passage 28 fluidly connecting the fuel gallery 8 and the outlet bore 24, wherein the passage 28 is arranged at an acute angle (D, fig.3) with respect to a longitudinal axis (B, fig.3) of the outlet bore 24. An adaptor may be fitted between the body and the injector. Use of and angled passage 28 removes the need to cross drill the supply rail body and avoids redundant passages. Also claimed is a fuel injection system and a manufacturing method.

Description

FUEL INJECTION SYSTEM AND A SUPPLY RAIL BODY THEREFOR

FIELD OF THE INVENTION

This invention relates to a supply rail body of a fuel injection system for a spark-ignition internal combustion engine. Aspects of the invention relate to the supply rail body, a fuel injection system comprising the supply rail body and a method of manufacturing the supply rail body.

BACKGROUND

Fuel injection systems for internal combustion engines are increasingly required to operate with higher pressures and in smaller package spaces, with a view to improving efficiencies and reduce costs. These requirements increase the load on components of the fuel injection systems, and in particular the supply rail body and any sealing interfaces. This can increase costs as more durable components are required.

It is against this background that the invention has been devised.

STATEMENTS OF INVENTION

According to a first aspect of the invention, there is provided a supply rail body for a fuel injection system, the supply rail body comprising a body section defining a high pressure fuel gallery; an outlet bore defining an injector interface region for connecting a respective fuel injector, wherein the outlet bore is offset from the high pressure fuel gallery; and, a passage fluidly connecting the high pressure fuel gallery and the outlet bore, wherein the passage is arranged at an acute angle with respect to a longitudinal axis of the outlet bore.

Preferably, the supply rail body further comprises an adaptor comprising the outlet bore; and, a socket for receiving the adaptor, the adaptor and socket being configured to form a fastening means when the adaptor is received by the socket to secure the adaptor within the socket.

Preferably, the adaptor and socket are configured to form an annular seal therebetween when the adaptor is secured within the socket.

Preferably, the socket comprises a conical region defining an opening of the socket and the adaptor comprises an annular sealing face configured to engage the conical region of the socket to form the annular seal.

Preferably, sections of the adaptor and socket are configured to form an annular cavity therebetween and the passage is configured to extend between the high pressure fuel gallery and the annular cavity when the adaptor is secured within the socket.

Preferably, the section of the adaptor configured to form the annular cavity comprises two radial passages configured to extend between the outlet bore and the annular cavity when the adaptor is secured within the socket.

Preferably, the section of the socket configured to form the annular cavity comprises an annular trough into which the passage opens. Alternatively, the socket comprises a spherical depression into which the passage opens.

According to a second aspect of the invention, there is provided a fuel injection system comprising a supply rail body according to the first aspect.

According to a third aspect of the invention, there is provided a method of manufacturing a supply rail body according to the first aspect, the method comprising casting or forging the supply rail body defining a high pressure fuel gallery and an outlet bore offset from the high pressure fuel gallery, wherein the outlet bore defines an injector interface region for connecting a fuel injector; and, drilling into the high pressure fuel gallery at an acute angle with respect to a longitudinal axis of the outlet bore to form a passage defining a fluid connection between the high pressure fuel gallery and the outlet bore.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic view of a fuel injection system, including a supply rail body; Figure 2 is a cross-sectional view of a known supply rail body for use with the fuel injection system of Figure 1; Figure 3 is a cross-sectional view of a supply rail body in accordance with a first embodiment of the invention for use with the fuel injection system of Figure 1; Figure 4 is a cross-sectional view of a supply rail body in accordance with a second embodiment of the invention; and, Figure 5 is a cross-sectional view of a supply rail body in accordance with a third embodiment of the invention.

In the drawings, like features are denoted by like reference signs.

SPECIFIC DESCRIPTION

The following detailed description refers to the accompanying drawings that show, by way of illustration, specific details and embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments may be utilised, and structural and logical changes may be made without departing from the scope of the invention as defined in the appended claims. Moreover, references in the following description to "vertical", "horizontal" and any other terms having an implied orientation are not intended to be limiting, and refer only to the orientation of the features as shown in the accompanying drawings.

Figure 1 is a schematic illustration of a fuel injection system, generally designated by 2, comprising a supply rail body 4. The fuel injection system 2 is suitable for an internal combustion engine 6. In this example, the internal combustion engine 6 is a spark-ignition internal combustion engine and the supply rail body 4 is configured to supply high pressure gasoline fuel thereto. However, the skilled reader will appreciate that aspects of the invention could also be applied to a fuel injection system supplying fuel to a compression-ignition internal combustion engine. The supply rail body 4 is generally tubular and comprises a body section 7 that defines a high pressure fuel gallery 8 extending along the longitudinal axis A of the supply rail body 4. The supply rail body 4 comprises an inlet port 10 and a plurality of outlet ports 12, each of which is in fluid connection with the high pressure fuel gallery 8. The inlet port 10 is connected to a high pressure supply line 14, which, in turn, is connected to a high pressure fuel pump 16. In use, the fuel pump 16 pumps fuel from a low pressure reservoir 18 to the supply rail body 4. In this example, the supply rail body 4 comprises six outlet ports 12 configured to receive respective fuel injectors 20 for controlling the injection of fuel into the combustion chambers of the internal combustion engine 6. Although not shown in Figure 1, the supply rail body 4 may also comprise a suite of other features for monitoring and regulating the pressure within the high pressure fuel gallery 8. For example, the supply rail body 4 may comprise a pressure relief port operatively connected to a pressure relief valve to return fuel to the reservoir 18, via a return line 22, in the event the pressure in the high pressure fuel gallery 8 exceeds a predetermined maximum pressure. It will be appreciated that the rail supply body 4 may comprise fewer or more than six outlet ports 12 depending on the configuration of the internal combustion engine 6. Moreover, the inlet and outlet ports 10, 12 may be orientated and positioned on the supply rail body 4 according to the architecture of the internal combustion engine 6.

Figure 2 is a cross-sectional view of an embodiment of a known supply rail body 4 showing an end of a fuel injector 20 held within a horizontal outlet bore 24 defining an outlet port 12. The outlet bore 24 comprises an injector interface region 26 for securing the fuel injector 20 in position within the outlet bore 24 via an interference fit. The interference fit provides a sufficient frictional connection between the injector interface region 26 and the fuel injector 20 to enable the dellivery of pressurised fuel to the fuel injector 20 from the high pressure fuel gallery 8. The longitudinal axis B of the outlet bore 24 extends perpendicularly and is offset by a distance C with respect to the longitudial axis A of the supply rail body 4. A passage 28 verticallly extends between the high pressure gallery 8, defined by a body section 7, and the outlet bore 24, providing a fluid conneciton therebetween. The passage 28 can only be formed by cross drilling the supply rail body 4, which is formed either by casting or forging. However, by necessity, this also forms a redundant passage 30 extending from the top of the supply rail body 4 to the high pressure gallery 8. This passage 30 is redundant in that it serves no functional requirement, and is only formed as a consequence of cross drilling the passage 28 extending between the high pressure gallery 8 and the outlet bore 24. In order to seal the redundant passage 30, the supply rail body 4 further comprises an embossment, generally designated by 32, for holding a seal plug assembly (not shown), preventing fuel held within the high pressure gallery 8 from escaping the supply rail body 4 via the redundant passage 30. Other embodiments of known supply rail bodies may include a threaded plug for sealing the redundant passage 30. The presence of the redundant passage 30 increases the internal surface area of the supply rail body 4 that is exposed to high pressure fuel, thereby increasing the risk of the supply rail body 4 failing due to fatigue. Moreover, in addition to the embossment 32 increasing the cost and weight of the supply rail body 4, high points of stress are generated at the interface between the seal plug assembly and the embossment 32. Another drawback is that the design and/ or pressure rating of the seal plug assembly changes according to the increasing pressure requriements of the supply rail body 4. The inventors seek to overcome or substantially mitigate at least some of these problems associated with the known supply rail body 4.

Figure 3 is a cross-sectional view of a first embodiment of a supply rail body 4 according to the invention. Similar to the known supply rail body, this supply rail body 4 comprises a body section 7, defining a high pressure gallery 8 extending along the longitudinal axis A of the supply rail body 4, together with an outlet bore 24, offset by a distance C from the high pressure fuel gallery 8, that defines an injector interface region 26 for connecting a respective fuel injector. The supply rail body 4 further comprises a passage 28 extending between the high pressure gallery 8 and the outlet bore 24, providing a fluid connection therebetween. In this embodiment, the passage 28 extends between the bottom of the high pressure fuel gallery 8 and the injector interface region 26 of the outlet bore 24 at an acute angle, indicated by D, with respect to the longitudinal axis B of the outlet bore 24.

The passage 28 is formed by drilling at an angle into the high pressure gallery 8 from the outlet bore 24. The use of an angled drilling removes the need to cross drill the supply rail body 4, which avoids the need for a redundant passage and all of its associated drawbacks as outlined above. The angle at which the passage 28 is drilled can be any angle that provides the necessary clearance in the outlet bore 24 for carrying out the drilling.

Figure 4 is a cross-sectional view of a second embodiment of a supply rail body 4 according to the invention, comprising a modular adapter 34. This modular arrangement means that the adaptor 34 can be configured for various different applications without needing to modify the rest of the supply rail body 4. In this embodiment, the outlet bore 24 is an open bore concentrically formed within the adaptor 34, which is configured to be received within a socket 36 formed in the supply rail body 4. An outer radial surface of the adaptor 34 and an inner radial surface of socket 36 are configured to form an engagement region, generally designated by 38, comprising a fastening means for securing the adaptor 34 within the socket 36. In one embodiment, the fastening means may be defined as a threaded engagement between the inner and outer radial surfaces of the socket 36 and the adaptor 34 respectively. In an alternative embodiment, the fastening means may be defined as a press-fit formed between these two surfaces. The skilled reader will, however, appreciate that the term, fastening means, is intended to characterise many alternative ways of assembling the adaptor 34 and socket 36 provided that these alternatives are suitable for generating an assembly force to hold the adaptor 34 within the socket 36 during the operation of the fuel injection system 2.

The socket 36 comprises a conical region 40 extending between the inner radial surface defining the engagement region 38 and an opening 42 of the socket 36. The conical region 40 comprises a conical seat 44 substantially adjacent the opening 42. An annular seal 46 is formed between an outer radial surface of the adaptor 34 and the conical seat 44, under the assembly force provided by the fastening means, preventing pressurised fuel from leaking between the adaptor 34 and socket 36. In such an application, an assembly force within the range of 50kN to 70kN would be sufficient to form the annular seal 44.

The adaptor 34 and socket 36 are configured to form an annular cavity 48 therebetween, located between the engagement region 38 and the annular seal 46. The adaptor 34 comprises two radial passages 50 providing a fluid connection between the outlet bore 24 and the annular cavity 48, although it will be appreciated by the skilled reader that a single radial passage or more than two radial passages may be used to connect the outlet bore 24 and the annular cavity 48 provided that the structural and/ or flow requirements of the supply rail body 4 are met. The radial passages 50 are positioned away from the injector interface region 26 of the outlet bore 24 to avoid the need to drill into injector interface region 26, which could negatively influence the connection it forms with the fuel injector 20. A passage 28 extends between the high pressure gallery 8 and the annular cavity 48, defining at least part of the fluid connection between the high pressure gallery 8 and the outlet bore 24. The passage 28 is formed by drilling into the high pressure gallery 8 from the socket 36 at an acute angle with respect to the longitudinal axis B of the outlet bore 24.

In use, high pressure fuel exits the high pressure gallery 8 via the passage 28 and enters the annular cavity 48. From there, fuel then enters the outlet bore 24 via the radial passages 50 for delivery to the fuel injector 20. The annular cavity 48 functions as a secondary reservoir, enabling a more consistent follow of fuel into the outlet bore 24 according to the load requirements of the internal combustion engine 6.

It will be appreciated by a person skilled in the art that the invention could be modified to take many alternative forms to that described herein, without departing from the scope of the appended claims. For example, the volume of the annular cavity 48 can be increased or decreased as required by different applications. For example, the inner radial surface of the socket 36 forming the annular cavity 48 may comprise a spherical depression (not shown) into which the passage 28 opens from the high pressure gallery 8. This improves the manufacturability of the angled passage 28, by providing a means for locating the drill bit during the drilling of the passage 28, and increases the volume of the annular cavity 48, which can help provide a more consistent flow of fuel into the outlet bore 24. Alternatively, the inner radial surface of the socket 36 forming the annular cavity 48 may comprise an annular trough 52, as shown in Figure 5, into which the passage 28 opens, increasing the volume of the annular cavity 48.

References used: 2 fuel injection system 4 supply rail body 6 internal combustion engine 7 body section 8 high pressure fuel gallery 10 inlet port 12 outlet ports 14 high pressure supply line 16 high pressure fuel pump 18 reservoir 20 fuel injectors 22 return line 24 outlet bore 26 injector interface region 28 passage 30 redundant passage 32 embossment 34 adaptor 36 socket 38 engagement region 40 conical region 42 opening of the socket 44 conical seat 46 annular seal 48 annular cavity 50 radial passages 52 annular trough

Claims

CLAIMS: 1. A supply rail body (4) for a fuel injection system (2), the supply rail body (4) comprising: a body section (7) defining a high pressure fuel gallery (8); an outlet bore (24) defining an injector interface region (26) for connecting a respective fuel injector (20), wherein the outlet bore (24) is offset from the high pressure fuel gallery (8); and, a passage (28) fluidly connecting the high pressure fuel gallery (8) and the outlet bore (24), wherein the passage (28) is arranged at an acute angle (D) with respect to a longitudinal axis (B) of the outlet bore (24).
2. A supply rail body (4) according to claim 1, further comprising: an adaptor (34) comprising the outlet bore (24); and, a socket (36) for receiving the adaptor (34), the adaptor (34) and socket (36) being configured to form a fastening means when the adaptor (34) is received by the socket (36) to secure the adaptor (34) within the socket (36).
3. A supply rail body (4) according to claim 2, wherein the adaptor (34) and socket (36) are configured to form an annular seal (44) therebetween when the adaptor (34) is secured within the socket (36).
4. A supply rail body (4) according to claim 3, wherein the socket (36) comprises a conical region (40) defining an opening (42) of the socket (36) and the adaptor (34) comprises an annular sealing face (46) configured to engage the conical region (40) of the socket (36) to form the annular seal (44).
5. A supply rail body (4) according to any one of claims 2 to 4, wherein sections of the adaptor (34) and socket (36) are configured to form an annular cavity (48) therebetween and the passage (28) is configured to extend between the high pressure fuel gallery (8) and the annular cavity (48) when the adaptor (34) is secured within the socket (36).
6. A supply rail body (4) according to claim 5, wherein the section of the adaptor (34) configured to form the annular cavity (48) comprises two radial passages (50) configured to extend between the outlet bore (24) and the annular cavity (48) when the adaptor (34) is secured within the socket (36).
7. A supply rail body (4) according to claim 5 or 6, wherein the section of the socket (36) configured to form the annular cavity (48) comprises an annular trough (52) into which the passage (28) opens.
8. A supply rail body (4) according to claim 5 or 6, wherein the socket (36) comprises a spherical depression into which the passage (28) opens.
9. A fuel injection system (2) comprising a supply rail body (4) according to any preceding claim. 10
10. A method of manufacturing a supply rail body (4) according to claims 1 to 8 comprising: casting or forging the supply rail body (4) defining a high pressure fuel gallery (8) and an outlet bore (24) offset from the high pressure fuel gallery (8), wherein the outlet bore (24) defines an injector interface region (26) for connecting a fuel injector (20); and, drilling into the high pressure fuel gallery (8) at an acute angle (D) with respect to a longitudinal axis (B) of the outlet bore (24) to form a passage (28) defining a fluid connection between the high pressure fuel gallery (8) and the outlet bore (24).