WO2022268877A1

WO2022268877A1 - A reinforced fuel rail and a manufacturing process thereof

Info

Publication number: WO2022268877A1
Application number: PCT/EP2022/067004
Authority: WO
Inventors: Ralf Weber; Omercan YURUMEZ; Cengiz OTUK; Andreas Rehwald
Original assignee: Robert Bosch Gmbh
Priority date: 2021-06-24
Filing date: 2022-06-22
Publication date: 2022-12-29

Abstract

The present invention proposes a fuel rail (10) for an internal combustion engine, comprising: a forged tubular body (20) extending along a longitudinal axis (A) with an inner longitudinal bore and the fuel rail (10) comprises: a first reinforcement member (32) extending between a corresponding one of the injector mounts (21) and the connector (30), and a second reinforcement member (33) extending between a corresponding one of the support members (22) and the connector (30). The present invention also proposes a manufacturing process of the fuel rail (10) for an internal combustion engine.

Description

SPECIFICATION

A REINFORCED FUEL RAIL AND A MANUFACTURING PROCESS THEREOF

Technical Field

The present invention relates to a fuel rail for an internal combustion engine according to the preamble of Claim 1. The present invention also relates to a manufacturing process of the fuel rail.

Background of the Invention

A fuel rail is part of a fuel injection system and serves to supply fuel to the fuel injection valves of an internal combustion engine. During the operation, fuel is injected at high pressure into a tubular body of the fuel rail and transferred via fuel injection devices into the cylinders of the internal combustion engine. In the art, forged fuel rails are preferred for reliability when operating at higher pressures. In the forging process, injector mounts, connectors, or support sections of the fuel rail are often formed by the material of the tubular body of the fuel rail. The connector of the fuel rail is arranged for attaching a sensor, a high pressure sensor or a high pressure line to determine an internal pressure and is often positioned in a radial direction of the tubular body. In such designs, lateral dynamic loads could be critical on the connectors in terms of strength, wear, and durability. During the operation, the force may lead to high loads on the attached sensor or line itself and/or on the electrical contact pins of the sensor or line connection that may crack or wear. Such attached sensors may be highly loaded by stress which may cause damage to the sensor in a longer usage time.

A prior art publication in the technical field of the invention may be referred to as EP 2 998 566 A1 which discloses a fuel distributor according to the prior art with a forged tubular body and mounting supports. The mounting supports are formed by flange portions which are formed integrally from the material of the tubular body, and sleeves which are pressed into bores in the flange portions. Brief Description of the Invention

The present invention proposes a fuel rail for an internal combustion engine, comprising: a forged tubular body extending along a longitudinal axis with an inner longitudinal bore for, in use, receiving pressurized fuel; a plurality of injector mounts formed in one piece on the tubular body and made of a same material as the tubular body; a plurality of support members formed in one piece on the tubular body for securement to a component of the internal combustion engine; at least one transversally protruding connector formed in one piece on the tubular body for receiving a pressure sensor for determining an internal pressure. The fuel rail comprises: a first reinforcement member extending between a corresponding one of the injector mounts and the connector, wherein the first reinforcement member is formed in one piece on the tubular body and made of a same material as the tubular body; and a second reinforcement member extending between a corresponding one of the support members and the connector wherein the second reinforcement member is formed in one piece on the tubular body and made of a same material as the tubular body. Thus, the connector member on the fuel rail is stiffened and minimal deformation during the operation is obtained. Therefore, the high pressure sensor or a high pressure line attached to the connector is kept safely.

In a possible embodiment, the connector comprises a neck part on both sides of the connector on the longitudinal axis and the first reinforcement member and the second reinforcement member are formed as extending on the neck parts on both sides of the connector. Thus, the stress concentration in the junction area of the connector and the tubular body can be reduced or even avoided.

In a possible embodiment, the first reinforcement member and the second reinforcement member are oriented in the same longitudinal direction parallel to the longitudinal axis of the tubular body. Thus, the optimum distribution of the load path is realized, without the need for additional stiffening structures that only increase weight. In a possible embodiment, the first reinforcement member has a first thickness value and the second reinforcement member has a second thickness value wherein the first thickness value and the second thickness value are the same. Thus, optimum load path distribution is achieved. In a possible embodiment, the thickness values may vary in the direction of the longitudinal axis of the tubular body and perpendicular to the longitudinal axis.

In a possible embodiment, the first reinforcement member has a first chamfered portion that extends the injector mount in the form of a continuous curve and has a second chamfered portion that extends the connector in the form of a continuous curve. With this arrangement, a smooth transition is obtained, which minimizes stress especially at connections between the connector and the injector mount.

In a possible embodiment, the second reinforcement member has a third chamfered portion that extends the connector in the form of a continuous curve and has a fourth chamfered portion that extends the support member in the form of a continuous curve. With this arrangement, a smooth transition is obtained, which minimizes stress especially at connections between the connector and the support member. In a possible embodiment, the first reinforcement member has a substantially triangular form. Thus, the transition is kept as smooth as possible to eliminate any risk of cracks thereof.

In a possible embodiment, the first reinforcement member and the second reinforcement member are formed from a flash formed during a forging process. Thus, there is no need to join together individual parts via several operating steps such as bonding, soldering, welding, or other joining processes.

In a possible embodiment, the connector comprises a branch bore extending along a direction transversal to said longitudinal axis and in communication with said longitudinal bore. Thus, the optimum engagement hole is arranged for the sensor in a secure manner.

In a possible embodiment, the injector mount is provided with an injector mount reinforcement member, adjacent to the first reinforcement member, formed from a flush formed during a forging process. This further optimizes the stiffening effect with the help of easy detachment from the forging die.

The present invention also proposes a manufacturing process of a fuel rail for an internal combustion engine, comprising the steps of: shaping a bulk material in a forging tool through a forging process into a semi-finished product, thereby forming a flash; removing the semi-finished product from the forging tool;- subjecting the semi finished product to a machining process; wherein the semi-finished product having a plurality of injector mounts formed in one piece on the tubular body and made of a same material as the tubular body; a plurality of support members formed in one piece on the tubular body for securement to a motor vehicle component of the internal combustion engine; and at least one transversally protruding connector formed in one piece on the tubular body for receiving a pressure sensor for determining an internal pressure; and trimming the flash to shape a first reinforcement member extending between a corresponding one of the injector mounts and the connector, and trimming another flash to shape a second reinforcement member extending between a corresponding one of the support members and the connector. Thus, the formed flash during the forging process is used to increase the stiffness of the rail structure. No additional material is needed to use. The junction areas are strengthened by the reinforcement members to reduce concentration and high deflection. Creating reinforcement members from the flash leads to reduce the weight of the fuel rail and require less machining.

In a possible embodiment, the first reinforcement member is formed in one piece on the tubular body and is made of the same material as the tubular body. Similarly, the second reinforcement member is formed in one piece on the tubular body and is made of the same material as the tubular body. Thus, there is no need to join together individual parts via several operating steps such as bonding, soldering, welding, or other joining processes.

In a possible embodiment, the first reinforcement member has a first chamfered portion that extends the injector mount in the form of a continuous curve and has a second chamfered portion that extends the connector in the form of a continuous curve. Similarly, the second reinforcement member has a third chamfered portion that extends the connector in the form of a continuous curve and has a fourth chamfered portion that extends the support member in the form of a continuous curve. Thus, a smooth transition is obtained, and only material is used that is actually needed so that the weight of the fuel rail is also optimized. A blank of metallic material, e.g., stainless steel, can be used as a bulk material for the production of the fuel rail.

Brief description of the figures

The accompanying drawings are given solely for the purpose of exemplifying the invention whose advantages over prior art were outlined above and will be explained in detail hereinafter:

Fig. 1 illustrates a perspective view of a fuel rail in a semi-finished product form before subjecting a machining process, according to the present invention.

Fig. 2 illustrates a perspective view of the fuel rail subjected to the machining process, according to the present invention.

Fig. 3 illustrates another perspective view of the fuel rail, according to the present invention.

Fig. 4 illustrates an enlarged perspective view of the tubular body showing a connector formed with a first reinforcement member and a second reinforcement member, according to the present invention.

Fig. 5 illustrates another enlarged perspective view of the tubular body showing the connector formed with the first reinforcement member and the second reinforcement member, according to the present invention.

Detailed description of the figures

The present invention proposes a fuel rail (10) for an internal combustion engine, comprising: a forged tubular body (20) extending along a longitudinal axis (A) with an inner longitudinal bore for, in use, receiving pressurized fuel; a plurality of injector mounts (21) formed in one piece on the tubular body (20) and made of a same material as the tubular body (20); a plurality of support members (22) formed in one piece on the tubular body (20) for securement to a component of the internal combustion engine; at least one transversally protruding connector (30) formed in one piece on the tubular body (20) for receiving a pressure sensor for determining an internal pressure. The fuel rail (10) comprises: a first reinforcement member (32) extending between a corresponding one of the injector mounts (21) and the connector (30), wherein the first reinforcement member (32) is formed in one piece on the tubular body (20) and made of a same material as the tubular body (20); and a second reinforcement member (33) extending between a corresponding one of the support members (22) and the connector (30) wherein the second reinforcement member (33) is formed in one piece on the tubular body (20) and made of a same material as the tubular body (20). Said first reinforcement member (32) and the second reinforcement member (33), respectively, extend between the connector (30) and the injector mounts (21) and support members (22) linearly elongate and narrow.

The first reinforcement member (32) and the second reinforcement member (33) are advantageously formed from a flash formed during a forging process. The application of the forging process has the benefit that the fuel rail (10) as a whole can be made in one piece and of the same material. There is no need to join together individual parts via several operating steps. Fig. 1 shows a semi-finished fuel rail (10) which is formed in the fording process. Afterward, a drilling process is applied to form the interior space of the tubular body (20) and the connector (30), and injector mounts (21). A continuous branch bore (31) is formed in the connector (30) extending along a direction transversal to the longitudinal axis (A) and in communication with said longitudinal bore. During the forging process, the injector mount (21) is also provided with an injector mount reinforcement member (34), adjacent to the first reinforcement member (32), formed from a flush.

Referring to Fig. 1, the tubular body (20) is formed with a plurality of injector mounts (21), a plurality of support members (22), and a connector (30). Said injector mounts (21) are provided to connect fuel injection valves which inject fuel into a cylinder head of the internal combustion engine and the support members (22) enable securement of the fuel rail (10) to a further motor vehicle component and support of the fuel rail (10). Moreover, a sensor (i.e., pressure sensor) may be placed in the connector (30) for controlling the internal pressure in the fuel rail (10). The second reinforcement member (33) extends one of the inclined lateral walls of the support member (22).

The connector (30) comprises a neck part (39) on both sides of the connector (30) on the longitudinal axis (A) and the first reinforcement member (32) and the second reinforcement member (33) are formed as extending on the neck parts (39) on both sides of the connector (30). Thus, the stress concentration in the junction area of the connector (30) and the tubular body (20) can be reduced or even avoided.

The support members (22) are an integral part of the tubular body (20) with converging lateral walls. The support member (22) has a generally cylindrical shape with a connection hole (23) in a middle portion thereof wherein corresponding fixation means (i.e., bolts, screws) are guided perpendicular to the longitudinal axis (A) through the connection hole (23), thereby simplifying assembly of the fuel rail (10).

Referring to Figs. 4 and 5, the first reinforcement member (32) and the second reinforcement member (33) are oriented in the same longitudinal direction parallel to the longitudinal axis (A) of the tubular body (20). Said first reinforcement member (32) has a first thickness value (Tl) and the second reinforcement member (33) has a second thickness value (T2) wherein the first thickness value (Tl) and the second thickness value (T2) are the same. With this arrangement, optimum load path distribution can be achieved. Said thickness values (Tl, T2) are a distance between the upper planar surface and the lower planar surface of the reinforcement members (32, 33).

The injector mount (21) and the support members (22) extend in parallel orientation with respect to each other. Similarly, the injector mount (21) and the support members (22) extend in perpendicular relation to the longitudinal axis (A) of the tubular body (20) in the same plane. Thus, the forging process is simplified as the injector mounts

(21) and the support members (22) can be arranged in a parting plane of the forging tool.

Referring to Fig. 5, the first reinforcement member (32) has a first chamfered portion (35) that extends the injector mount (21) in the form of a continuous curve and has a second chamfered portion (36) that extends the connector (30) in the form of a continuous curve. Moreover, the second reinforcement member (32) has a third chamfered portion (37) that extends the connector (30) in the form of a continuous curve and has a fourth chamfered portion (38) that extends the support member (22) in the form of a continuous curve. The first chamfered portion (35) and the second chamfered portion (36) can extend in a continuous curve defined by a radius of, advantageously and can have 3 to 20 millimeters wall thickness. Similarly, the third chamfered portion (37) and the fourth chamfered portion (38) can extend in a continuous curve defined by a radius. As can be seen in Fig. 5, the first reinforcement member (32) can have a substantially triangular form. The present invention also proposes a manufacturing process of a fuel rail (10) for an internal combustion engine, comprising the steps of: shaping a bulk material in a forging tool through a forging process into a semi-finished product, thereby forming a flash; removing the semi-finished product from the forging tool; subjecting the semi finished product a machining process to form the fuel rail; wherein the semi-finished product having a plurality of injector mounts (21) formed in one piece on the tubular body (20) and made of a same material as the tubular body; a plurality of support members (22) formed in one piece on the tubular body (20) for securement to a motor vehicle component of the internal combustion engine; and at least one transversally protruding connector (30) formed in one piece on the tubular body (20) for receiving a pressure sensor for determining an internal pressure; and trimming the flash to shape a first reinforcement member (32) extending between a corresponding one of the injector mounts (21) and the connector (30), and trimming another flash to shape a second reinforcement member (33) extending between a corresponding one of the support members (22) and the connector (30). The tubular body (20) on which integral injector mounts (21), support members (22), and the connector (30) are formed from the same material in this forging process. According to the present invention, the forging process allows the production of a fuel rail in one piece and of the same material. There is no need for soldered or welded seams or similar joints between individual components that represent potential weak spots. In the manufacturing process, at first, a bulk material (i.e., metal block) is placed in the forging tool, then the bulk material is shaped in one or more steps into a semi finished product, with a flash being formed on the bulk material in the forging process. After being removed from the forging tool, the semi-finished product is subjected to a machining process, which involves a material removing process such as drilling, cutting, trimming, and the like. In particular, drilling is applied to form the interior space of the base body and the inlets and injector mounts (21). As mentioned above, forging is followed by mechanical treatment, in particular machining of the forged structure, including the provision of bores for the longitudinal hollow space in the tubular body (20) and connection bores in the injector mount (21). The first reinforcement member (32) is formed in one piece on the tubular body (20) and is made of the same material as the tubular body (20). Similarly, the second reinforcement member (33) is formed in one piece on the tubular body (20) and is made of the same material as the tubular body (20).

The first reinforcement member (32) has a first chamfered portion (35) that extends the injector mount (21) in the form of a continuous curve defined by a radius and has a second chamfered portion (36) that extends the connector (30) in the form of a continuous curve defined by a radius. The second reinforcement member (33) has a third chamfered portion (37) that extends the connector (30) in the form of a continuous curve, and has a fourth chamfered portion (38) that extends the support member (22) in the form of a continuous curve.

Reference list:

10. Fuel rail

20. Tubular body

21. Injector mount

22. Support member

23. Connection hole

30. Connector

31. Branch bore

32. First reinforcement member

33. Second reinforcement member

34. Injector mount reinforcement member

35. First chamfered portion

36. Second chamfered portion

37. Third chamfered portion

38. Fourth chamfered portion

39. Neck part

A Longitudinal axis

T1 First thickness value

T2 Second thickness value

Claims

1. A fuel rail (10) for an internal combustion engine, comprising: a forged tubular body (20) extending along a longitudinal axis (A) with an inner longitudinal bore for, in use, receiving pressurized fuel; a plurality of injector mounts (21) formed in one piece on the tubular body (20) and made of a same material as the tubular body (20); a plurality of support members (22) formed in one piece on the tubular body (20) for securement to a component of the internal combustion engine; at least one transversally protruding connector (30) formed in one piece on the tubular body (20) for receiving a pressure sensor for determining an internal pressure, characterized in that the fuel rail (10) comprises: a first reinforcement member (32) extending between a corresponding one of the injector mounts (21) and the connector (30), wherein the first reinforcement member (32) is formed in one piece on the tubular body (20) and made of a same material as the tubular body (20); and a second reinforcement member (33) extending between a corresponding one of the support members (22) and the connector (30) wherein the second reinforcement member (33) is formed in one piece on the tubular body (20) and made of a same material as the tubular body (20).

2. The fuel rail (10) according to claim 1, wherein the connector (30) comprises a neck part (39) on both sides of the connector (30) on the longitudinal axis (A) and the first reinforcement member (32) and the second reinforcement member (33) are formed as extending on the neck parts (39) on both sides of the connector (30).

3. The fuel rail (10) according to claim 1 or 2, wherein the first reinforcement member (32) and the second reinforcement member (33) are oriented in the same longitudinal direction parallel to the longitudinal axis (A) of the tubular body (20).

4. The fuel rail (10) according to any one of the preceding claims, wherein the first reinforcement member (32) has a first thickness value (Tl) and the second reinforcement member (33) has a second thickness value (T2) wherein the first thickness value (Tl) and the second thickness value (T2) are the same.

5. The fuel rail (10) according to any one of the preceding claims, wherein the first reinforcement member (32) has a first chamfered portion (35) that extends the injector mount (21) in the form of a continuous curve, and has a second chamfered portion (36) that extends the connector (30) in the form of a continuous curve.

6. The fuel rail (10) according to any one of the preceding claims, wherein the second reinforcement member (33) has a third chamfered portion (37) that extends the connector (30) in the form of a continuous curve and has a fourth chamfered portion (38) that extends the support member (22) in the form of a continuous curve.

7. The fuel rail (10) according to any one of the preceding claims, wherein the first reinforcement member (32) has a substantially triangular form.

8. The fuel rail (10) according to any one of the preceding claims, wherein the first reinforcement member (32) and the second reinforcement member (33) are formed from a flash formed during a forging process.

9. The fuel rail (10) according to any one of the preceding claims, wherein the connector (30) comprises a branch bore (31) extending along a direction transversal to said longitudinal axis (A) and in communication with said longitudinal bore.

10. The fuel rail (10) according to any one of the preceding claims, wherein the injector mount (21) is provided with an injector mount reinforcement member (34), adjacent to the first reinforcement member (32), formed from a flush formed during a forging process.

11. A manufacturing process of a fuel rail (10) for an internal combustion engine, comprising the steps of:

- shaping a bulk material in a forging tool through a forging process into a semi- finished product, thereby forming a flash;

- removing the semi-finished product from the forging tool;

- subjecting the semi-finished product a machining process to form the fuel rail (10); wherein the semi-finished product having a plurality of injector mounts (21) formed in one piece on the tubular body (20) and made of a same material as the tubular body; a plurality of support members (22) formed in one piece on the tubular body (20) for securement to a motor vehicle component of the internal combustion engine; and at least one transversally protruding connector (30) formed in one piece on the tubular body (20) for receiving a pressure sensor for determining an internal pressure; and - trimming the flash to shape a first reinforcement member (32) extending between a corresponding one of the injector mounts (21) and the connector (30), and trimming another flash to shape a second reinforcement member (33) extending between a corresponding one of the support members (22) and the connector (30).

12. The manufacturing process according to Claim 10, wherein the first reinforcement member (32) is formed in one piece on the tubular body (20) and is made of a same material as the tubular body (20).

13. The manufacturing process according to Claim 10 or 11, wherein the second reinforcement member (33) is formed in one piece on the tubular body (20) and is made of a same material as the tubular body (20).

14. The manufacturing process according to any one of claim 10 to 12, wherein the first reinforcement member (32) has a first chamfered portion (35) that extends the injector mount (21) in the form of a continuous curve and has a second chamfered portion (36) that extends the connector (30) in the form of a continuous curve.

15. The manufacturing process according to any one of claim 10 to 13, wherein the second reinforcement member (33) has a third chamfered portion (37) that extends the connector (30) in the form of a continuous curve and has a fourth chamfered portion (38) that extends the support member (22) in the form of a continuous curve.