Monolithic fuel rail structure and method of manufacture

Abstract

The integral fuel rail structure is configured to receive and support a fuel injector and includes a main pipe, an injector cup integrally projecting from the outer surface of the main pipe, and a fuel passage. The inner surface of the main pipe defines the main fuel passage, and the injector cup includes an orifice opening at one end. The inlet end of the fuel injector is received in the orifice. The fuel passage provides fluid communication between the orifice and the main fuel passage, and the fuel passage corresponds to a portion of the orifice extending through the injector cup on each of the opposite sides of the injector cup.

Description

Background Technology

[0001] A fuel rail can be used to supply fuel to multiple fuel injectors that inject fuel into the intake manifold of an internal combustion engine. The inlet end of the fuel injector is typically removably attached to the fuel rail using clips or other similar mechanical attachments, and the outlet end of the fuel injector can engage a corresponding opening or port in the intake manifold. In some applications, the fuel rail can supply high-pressure fuel via fuel injectors by directly injecting it into the corresponding engine cylinder.

[0002] While plastic fuel rails are known, metal fuel rails can also be used to deliver fuel at high pressure and include a main fluid supply line referred to as the "log". As used herein, the term "high pressure" refers to a pressure greater than 250 bar. The log has a main fuel passage through which fuel is supplied from the fuel tank or fuel pump. The fuel rail includes distribution arms for distributing fuel to the individual cylinders of the engine. The distribution arms protrude from the log and provide a fuel passage communicating with the main fuel passage. Each distribution arm terminates in an injector cup (sometimes referred to as a bushing). Each injector cup includes an orifice that receives and holds the inlet end of a fuel injector. The fuel injector inlet end includes a seal that fills the space between the fuel injector and the orifice to define a high-pressure fuel distribution chamber within the injector cup. Fuel is supplied at high pressure to the fuel distribution chamber via the main fuel passage of the log and the fuel passage of the corresponding distribution arm. The relative geometry of the log, distribution arms, and injector cups is complex and depends on the engine geometry and the available space within the engine system. Summary of the Invention

[0003] An integral fuel rail structure, configured to provide high-pressure fuel distribution, is manufactured using a process in which the main pipe, distribution arms, and injector cups are integrally formed from a single metal blank. Manufacturing processes used to form the integral fuel rail structure can include, but are not limited to, extrusion, casting, forging, and injection molding. These methods require conventional machining (e.g., drilling) to provide the main fuel passage within the main pipe, fuel passages within each distribution arm, and orifices within each injector cup. However, machining the distribution arm fuel passages through the injector cup orifices into the main fuel passage of the main pipe without contacting the orifices and without compromising the integrity of the fuel distribution chamber is challenging, especially in geometries where the centerline of the orifice is offset relative to the centerline of the main fuel passage. For example, to avoid compromising the integrity of the fuel distribution chamber, machining is limited to providing fuel passages aligned with the centerline of the orifice and having a maximum offset from the centerline of the orifice corresponding to the orifice radius. Therefore, the range of the fuel distribution paths and the ability of the fuel rail structure to fit into the available space within the engine system are limited.

[0004] To achieve greater design flexibility, the inventors realized that forming an opening in the injector cup at a location outside the high-pressure fuel distribution chamber provided at the fuel injector inlet end would be acceptable. Specifically, it was realized that forming an opening in the injector cup at a location between the fuel injector seal and the injector cup opening end would not compromise the integrity of the fuel distribution chamber. Specifically, the fuel passage opening enters the injector cup below the seal, passes through the orifice, and exits the injector cup above the seal. The fuel passage opening extends via the distribution arm into the main fuel passage of the main pipe. In doing so, a fuel passage between the orifice and the main fuel passage can be formed with a greater offset and at a non-zero angle relative to the centerline of the orifice. Therefore, the fuel passage connecting the main fuel passage of the main pipe to the orifice of the integral injector cup is formed through the injector cup via an inlet formed in the sidewall of the injector cup and extending at an angle relative to the centerline of the orifice, thereby allowing offset from the centerline of the main pipe in two orthogonal directions perpendicular to the centerline of the main fuel passage. By machining in this manner, engine designers have greater flexibility in integrating the fuel rail assembly into the engine. Furthermore, the fuel rail disclosed herein is backward compatible. This means that a given engine can be upgraded to increase fuel pressure and reduce the number of parts, requiring only limited redesign and testing of components such as the cylinder head, fuel injectors, pressure sensors, connecting pipes, and electrical fixtures. This reduces the risk of untested parts and saves build time and money. Additionally, the fuel rail disclosed herein allows for the reuse of equipment and process measurements.

[0005] The integrated fuel rail structure disclosed herein represents an improvement over conventional fuel distribution systems where the main pipe, distribution arm, and injector cup are combinations of individual components, such as pipes, injector bushings, plugs, sensor attachments, fuel inlets, and outlets. These individual components can be secured together using various types of mechanical clamps, welds, and brazing. However, these attachment methods are often associated with contamination and weak fit retention. Contamination can lead to blocked connection passages, and any insufficient retention or fit can result in inadequate filling of the space, thereby preventing fuel from being distributed in the intended amount, location, and service life.

[0006] In some embodiments, the fuel passage is machined using an electrical discharge machining (EDM) process. This process is well-suited for forming fuel passages because EDM is a precise process and the material removed by EDM is dissolved, resulting in a clean hole that can be deburred by electropolishing of the finished fuel rail assembly. Importantly, the EDM process does not leave any debris, chips, or other contaminants in the machined part that would adversely affect its function and durability. While other machining methods, such as auger drilling, laser burning, plasma burning, and water jet erosion, can be used to form fuel passages, in some embodiments other machining methods may not be suitable due to potential contamination, relative inaccuracy, and / or relatively poor form control.

[0007] In some embodiments, the diameter of the fuel passage between the injector cup orifice and the main fuel channel can be in the range of 1 mm to 3.5 mm. The combination of the length and diameter of the fuel passage can provide a pressure damping effect, which can complement or replace the orifice typically present in the rail inlet fitting or injector cup for this purpose. Therefore, the cost associated with the formation of the rail inlet fitting or orifice can be reduced.

[0008] In some aspects, the integral fuel rail structure is configured to receive and support a fuel injector. The fuel injector has an injector housing, a fuel inlet end, a fuel outlet end opposite to the fuel inlet end, and a seal disposed on the outer surface of the injector housing. The integral fuel rail structure includes a main pipe, an injector cup integrally projecting from the outer surface of the main pipe, and a fuel passage. The main pipe includes a first end of the main pipe, a second end of the main pipe opposite to the first end, and an inner surface of the main pipe defining a main fuel passage. The main fuel passage is concentric with the longitudinal axis of the main pipe, and the longitudinal axis of the main pipe extends between the first end and the second end. The injector cup includes a sidewall, the inner surface of which defines an orifice. The injector cup includes a proximal end that closes one end of the sidewall and a distal end opposite to the proximal end. The distal end is open, and the centerline of the sidewall extends through the proximal and distal ends. The orifice includes an open end coinciding with the distal end. Furthermore, the orifice includes a blind end disposed between the open end and the proximal end of the injector cup. The fuel passage provides fluid communication between the orifice and the main fuel channel, the fuel passage corresponding to a portion of the orifice extending through the injector cup on each of the opposite sides of the injector cup.

[0009] In some embodiments, the hole passes through the sidewall of the injector cup such that it extends through the sidewall facing the main pipe and through the sidewall opposite to the sidewall facing the main pipe.

[0010] In some embodiments, the inner surface of the sidewall includes a sealing seat region that receives a seal when the fuel injector is disposed in the injector cup. The sealing seat region is disposed between an open end and a blind end. The orifice coincides with a straight line passing through the sidewall. This straight line includes: a) a first line portion located in a first portion of the injector cup, the first portion of the injector cup being disposed between the sealing seat region and a proximal end, and b) a second line portion located in a second portion of the injector cup, the second portion of the injector cup being disposed between the sealing seat region and a distal end.

[0011] In some embodiments, the sealing seat region has a larger dimension in a direction parallel to the centerline of the sidewall than the dimension of the seal in the same direction, to accommodate the movement of the fuel injector within the injector cup during operation of the fuel rail structure.

[0012] In some embodiments, the hole extends through a first portion of the sidewall, and the first portion of the ejector cup includes the first portion of the sidewall.

[0013] In some embodiments, the hole extends through a second portion of the sidewall, and the second portion of the ejector cup includes the second portion of the sidewall.

[0014] In some embodiments, the first line portion intersects the sidewall at a location between the sealing seat region and the blind end, and the second line portion intersects the sidewall at a location between the sealing seat region and the open end.

[0015] In some embodiments, the hole coincides with a straight line passing through the sidewall at an angle θ relative to the Y-axis. The Y-axis intersects and is perpendicular to the longitudinal axis of the main pipe. Furthermore, the Y-axis is parallel to the centerline of the sidewall, and the angle θ is in the range of 0 to 45 degrees.

[0016] In some embodiments, the injector cup is connected to the outer surface of the main pipe via a dispensing arm having a first end integral with the outer surface of the main pipe and a second end integral with the injector cup, and a fuel passage passes through the dispensing arm.

[0017] In some embodiments, the dispensing arm is long enough that the injector cup is spaced apart from the main pipe.

[0018] In some embodiments, the sealing seat region has a size in a direction parallel to the centerline of the sidewall that is 150% to 300% larger than the corresponding size of the seal.

[0019] In some aspects, the fuel rail assembly includes an integral fuel rail structure and a fuel injector supported on the fuel rail structure. The fuel injector includes an injector housing, a fuel inlet end, a fuel outlet end opposite to the fuel inlet end, and a seal disposed on the outer surface of the injector housing. The integral fuel rail structure includes a main pipe, an injector cup integrally projecting from the outer surface of the main pipe, and a fuel passage. The main pipe includes a first end of the main pipe, a second end of the main pipe opposite to the first end, and an inner surface of the main pipe defining a main fuel passage. The main fuel passage is concentric with the longitudinal axis of the main pipe. The longitudinal axis of the main pipe extends between the first end and the second end. The injector cup includes a sidewall, the inner surface of which defines an orifice. The injector cup includes a proximal end that closes one end of the sidewall and a distal end opposite to the proximal end. The distal end is open, and the centerline of the sidewall extends through the proximal and distal ends. The orifice includes an open end coinciding with the distal end and a blind end disposed between the open end and the proximal end of the injector cup. In addition, the fuel passage provides fluid communication between the orifice and the main fuel channel, the fuel passage corresponding to a portion of the orifice extending through the injector cup on each of the opposite sides of the injector cup.

[0020] In some aspects, a method for manufacturing an integral fuel rail structure is provided. The method includes the steps of: providing a metal blank; heating the metal blank to a predetermined temperature below the melting temperature of the metal; and forging the heated metal blank to provide an integral fuel rail structure. The fuel rail structure includes a main pipe and an injector cup integrally projecting from the outer surface of the main pipe. The injector cup includes cylindrical sidewalls, and the inner surface of the sidewalls defines an aperture. The injector cup includes a proximal end that closes one end of the sidewalls and a distal end opposite the proximal end. The distal end is open. The method includes the additional steps of: machining a main fuel passage in the main pipe; machining the aperture in the injector cup; and machining a fuel passage in the fuel rail structure that provides fluid communication between the main fuel passage and the aperture. The fuel passage corresponds to a portion of an aperture extending through the injector cup on each of the opposite sides of the injector cup.

[0021] In some embodiments, the hole passes through the sidewall of the injector cup such that it extends through the sidewall facing the main pipe and through the sidewall opposite to the sidewall facing the main pipe.

[0022] In some embodiments, the inner surface of the injector cup includes a sealing seat region configured to receive a seal from a fuel injector. The sealing seat region is disposed between a proximal end and a distal end, and the step of machining the fuel passage in the fuel rail structure includes forming the orifice such that it extends along a straight line. This straight line includes: a) a first line portion located in a first portion of the injector cup disposed between the sealing seat region and the proximal end, and b) a second line portion located in a second portion of the injector cup disposed between the sealing seat region and the distal end.

[0023] In some embodiments, the step of machining the fuel passage includes creating a single hole in the fuel rail structure, the single hole being interrupted by a bore and extending through each of the opposite sides of the fuel injector cup.

[0024] In some embodiments, the step of machining fuel passages in the fuel rail structure includes using an electrical discharge machining (EDM) process.

[0025] In some embodiments, the EDM process uses rigid straight electrodes.

[0026] In some aspects, the integral fuel rail structure is configured to receive and support fuel injectors relative to the cylinders of the engine. The integral fuel rail structure includes a main pipe having an inner surface defining a primary fuel passage and an injector cup integrally projecting from the outer surface of the main pipe. The inner surface of the injector cup defines an orifice opening at one end of the injector cup. The integral fuel rail structure includes a fuel passage providing fluid communication between the orifice and the primary fuel passage. The fuel passage corresponds to a portion of the orifice extending through the injector cup on each of the opposite sides of the injector cup. Attached Figure Description

[0027] Figure 1 This is a perspective view of the integral fuel rail structure.

[0028] Figure 2 yes Figure 1 A perspective view of a portion of the integral fuel rail structure, showing the fuel injector positioned within the injector cup.

[0029] Figures 3-5 All are as along Figure 2 Line 3-3 is visible. Figure 2 A cross-sectional view of a portion of it.

[0030] Figure 6 This is a perspective view of an alternative embodiment of an integral fuel rail structure, showing a fuel injector disposed in an injector cup.

[0031] Figure 7 Is it like along Figure 6 Line 7-7 is visible Figure 5 A cross-sectional view of a portion of it.

[0032] Figure 8 This is a flowchart representing a method for manufacturing an integral fuel rail structure. Detailed Implementation

[0033] refer to Figures 1-3The integral fuel rail structure 2 is configured to supply fuel to a plurality of fuel injectors 100, which inject fuel directly into the cylinders of an internal combustion engine (not shown). The fuel rail structure 2 includes a main pipe 10 that receives high-pressure fuel from a fuel tank or fuel pump (not shown). The fuel rail structure 2 includes integral distribution arms 20 spaced along the length of the main pipe 10 and projecting from an outer surface 14 of the main pipe 10. As used herein, the term "integral" is defined as "being whole, forming a single unit with another part". Each distribution arm 20 is configured to distribute pressurized fuel to a corresponding single cylinder of the engine. Each distribution arm 20 terminates in an integral injector cup 40, which is configured to receive the inlet end 108 of a fuel injector 100. Each fuel injector 100 includes a circumferential seal 106 adjacent to the inlet end 108, and the seal 106 forms a fluid-impermeable seal with the inner surface of the corresponding injector cup 40. Furthermore, the fuel injector 100 is detachably secured to the injector cup 40 using pins, clips, or other similar mechanical attachment devices. Fuel, at high pressure, is supplied to the fuel distribution chamber 51 defined within each injector cup 40 via the main fuel passage 15 of the main pipe 10 and the fuel passage 22 of the corresponding distribution arm 20. Thus, the high-pressure fuel received in the fuel rail structure 2 is directly distributed to each cylinder of the engine via the corresponding distribution arm 20, the injector cup 40, and the fuel injector 100. The relative geometry of the main pipe 10, the distribution arm 20, and the injector cup 40 is complex and depends on the engine geometry and the available space within the engine system. The fuel passage 22 is formed in the main fuel passage 15 of the main pipe 10 and the fuel distribution chamber 51 of the injector cup 40 via an EDM process, which includes forming inlet holes in the outer surface 43 of the injector cup 40, as discussed in detail below.

[0034] Fuel injector 100 can be a high-pressure device used for direct injection into the cylinders of a gasoline engine. Fuel injector 100 may include an elongated, generally tubular valve housing 102 that supports an injector valve (not shown). Valve housing 102 is an elongated, generally tubular structure. The inlet end 108 of valve housing 102 provides a fuel connection sleeve 109 with a circumferentially extending O-ring seal 106. The outlet end 110 of valve housing 102 is opposite to the inlet end 108 and provides a valve seat (not shown) and a fuel injection opening or nozzle 112. The seal 106 mates with the inner surface of injector cup 40 to define a high-pressure fuel distribution chamber 51 within injector cup 40.

[0035] Fuel rail structure 2 includes a main pipe 10, which is an elongated hollow tube providing a common rail or manifold. In the illustrated embodiment, the main pipe 10 is cylindrical, but not limited to having a cylindrical shape. The main pipe 10 includes a first end 11, a second end 12 opposite to the first end 11, and a longitudinal axis 16 extending between the first and second ends 11, 12. The main pipe 10 is thick-walled to accommodate high fuel pressures, and the inner surface 13 of the main pipe defines a main fuel passage 15, providing fuel supply from a fuel tank or fuel pump (not shown). The centerline of the main fuel passage 15 coincides with the longitudinal axis 16 of the main pipe. The material and dimensions of the main pipe are determined by the requirements of the specific application. For example, in some embodiments, the main pipe 10 is a tube made of stainless steel with a tube diameter of approximately 15 mm to 30 mm and a wall thickness of approximately 1.5 mm to 4 mm. In some embodiments, the main pipe 10 may include a boss 19 configured to receive a pressure sensor. One end of the main tube (e.g., the first end 11) can be shaped to provide an inlet connector 18, and the opposite end (e.g., the second end 12) is closed.

[0036] The fuel rail structure 2 includes a plurality of distribution arms 20 integrally projecting from the outer surface 14 of the main pipe and providing an integral connection between the main pipe 10 and the corresponding injector cup 40. The distribution arms 20 are configured to supply high-pressure fuel to the corresponding fuel injectors 100 via the injector cup 40. The number of distribution arms 20 projecting from the main pipe 10 depends on the engine configuration. For example, when using a four-cylinder engine, the main pipe 10 is provided with four distribution arms 20 spaced apart along the longitudinal axis 16, and when using an inline six-cylinder engine, the main pipe 10 is provided with six distribution arms 20 spaced apart along the longitudinal axis 16. Each distribution arm 20 includes a fuel passage 22 communicating with the main fuel passage 15, as discussed in more detail below.

[0037] Each injector cup 40 is a cup-shaped structure disposed at the distal end of the corresponding dispensing arm 20. Each injector cup 40 includes a cylindrical sidewall 41, and the inner surface 42 of the sidewall 41 defines an orifice 47. Each injector cup 40 includes a proximal end 45 projecting from the corresponding dispensing arm 20 and closing one end of the sidewall 41, and a distal end 46 opposite to the proximal end 45. The orifice 47 intersects with the distal end 46. Specifically, the orifice 47 includes an open end 49 coinciding with the distal end 46 and a blind end 48 disposed between the orifice open end 49 and the proximal end 45 of the injector cup. In applications where the fuel rail structure 2 is mounted above the engine block, the injector cup 40 opens downward. The centerline 44 of the sidewall 41 extends through the proximal and distal ends 45, 46 of the injector cup and is perpendicular to the longitudinal axis 16 of the main pipe 10.

[0038] When the inlet end 108 of the fuel injector 100 is positioned in the orifice 47 of the injector cup 40, the seal 106 provided on the fuel injector inlet end 108 forms an impermeable fluid seal with the inner surface 42 of the sidewall within the sealing seat region 50 of the orifice 47. The seal 106 divides the internal space of the fuel injector cup 40 into two separate chambers 51, 52. The first chamber, referred to as the fuel distribution chamber 51, is defined between the seal 106, the first portion 41(1) of the sidewall 41, and the blind end 48 of the orifice. Fuel is supplied to the fuel distribution chamber 51 via the main fuel passage 15 of the main pipe 10 and the fuel passage 22 of the corresponding distribution arm 20. In the illustrated embodiment, fuel is supplied to the fuel distribution chamber 51 at high pressure. The second chamber 52 is defined between the seal 106, the second portion 41(2) of the sidewall 41, and the orifice opening end 49. The second chamber 52 opens to the environment.

[0039] refer to Figure 2 and Figure 4 A sealing region 50 is disposed between and spaced apart from the orifice opening end 49 and the orifice blind end 48. The sealing region 50 has a diameter sized to receive the fuel injector seal 106 and form an impermeable seal therewith. The sealing region 50 of the injector cup 40 has a longitudinal dimension ℓ1 (e.g., a dimension in a direction parallel to the sidewall centerline 44), which is larger than the corresponding dimension ℓ2 of the fuel injector seal 106. The longitudinal dimension ℓ1 of the sealing region 50 is set to accommodate longitudinal movement of the fuel injector 100 within the injector cup 40 during operation of the fuel rail structure 2. This longitudinal movement can be due to vehicle vibration, engine vibration, pressure changes within the fuel distribution chamber 51, etc. In some embodiments, for example, the longitudinal dimension ℓ1 of the sealing region 50 can be in the range of 120% to 300% of the longitudinal dimension of the seal 106.

[0040] Each injector cup 40 has an orifice 47 including an injector retention region 54 disposed between a sealing seat region 50 and a distal end 46. The injector retention region 54 has a larger diameter than the sealing seat region 50 and includes an orifice opening end 49. A pair of through holes 55 are provided within the sidewall 41 of the injector retention region 54. The through holes 55 are parallel to each other and lie in a plane 56 perpendicular to the centerline 44 of the sidewall. The through holes 55 are spaced apart from each other and are disposed on each side of the centerline 44 of the sidewall. Each through hole 55 is formed and sized to receive a retaining pin 58 by press-fit or spring-fit. The through holes 55 are arranged such that when the fuel injector 100 is disposed within the orifice 47 and the retaining pin 58 is disposed in each through hole 55, the retaining pin 58 extends through the orifice 47 on each of the opposite sides of the fuel injector 100. Furthermore, the retaining pin 58 is received in the diameter reduction portion 114 of the fuel injector housing 102, whereby the retaining pin 58 engages with the diameter reduction portion 114 of the fuel injector housing 102 to retain the fuel injector 100 in the aperture 47. In other embodiments, the fuel injector 100 may be rigidly retained in a "non-suspended manner" using an external spring or clip, whereby the retaining pin 58 and the corresponding through hole 55 may be omitted.

[0041] refer to Figure 5 As previously described, each dispensing arm 20 includes a fuel passage 22 that provides fluid communication between the main fuel passage 15 of the main pipe 10 and the fuel dispensing chamber 51 of the orifice 47 of the injector cup 40. Each fuel passage 22 extends linearly and coincides with a reference line 62. The reference line 62 includes a first line portion 62(1) located on a first portion 40(1) of the injector cup and a second line portion 62(2) located on a second portion 40(2) of the injector cup. Furthermore, the reference line 62 includes a third line portion 62(3) providing a centerline for the fuel passage 22 and a fourth line portion 62(4) located on the main fuel passage 15.

[0042] A first portion of the injector cup 40(1) is disposed between the sealing seat region 50 and the proximal end 45 of the injector cup. A first line portion 62(1) is located in the first portion of the injector cup 40(1) and extends through the first portion 41(1) of the sidewall 41 on one side of the injector cup 40. In the illustrated embodiment, said side of the injector cup 40 is on the side of the injector cup 40 facing the main pipe 10, for example, on the inward side 53 of the injector cup 40.

[0043] The second portion 40(2) of the injector cup is disposed between the sealing seat region 50 and the distal end 46 of the injector cup. A second line portion 62(2) is located within the second portion 40(2) of the injector cup and extends through the second portion 41(2) of the sidewall 41 on the side of the injector cup 40 opposite to the inward side 53 of the injector cup. In the illustrated embodiment, the opposite side is on the side of the injector cup 40 away from the main pipe 10, for example, on the outward side 59 of the injector cup 40.

[0044] Therefore, the first line portion 62(1) intersects the sidewall 41 at the position between the sealing seat region 50 and the hole blind end 48, and the second line portion 62(2) intersects the sidewall 41 at the position between the sealing seat region 50 and the hole opening end 49.

[0045] As discussed below, a fuel passage 22 is formed in the integral fuel rail structure 2 by forming a hole 60 in the fuel rail structure 2. The hole 60 is centered on line 62 and coincides with the first, second, and third line portions 62(1), 62(2), and 62(3). Specifically, the hole 60 passes through the second portion 41(2) of the sidewall 41 on the injector cup outward 59. As line 62 passes through the hole 47, the hole 60 is interrupted, and the hole 60 continues through the first portion 41(1) of the sidewall 41 on the injector cup inward 53. In order to provide communication between the fuel distribution chamber 51 and the main fuel passage 15, the hole 60 passes through the injector cup inward 53 within the first portion 40(1) of the injector cup, for example, at a location between the sealing seat region 50 and the proximal end 45 of the injector cup. Furthermore, the hole 60 extends through the length of the distribution arm 20 that connects the injector cup 40 to the main pipe 10 and through the wall of the main pipe 10, so that the fuel passage 22 communicates with the main fuel passage 15.

[0046] To maintain the sealing integrity of the fuel distribution chamber 51, the orifice 60 can extend outward 59 through the injector cup within the second portion 40(2) of the injector cup, for example, only at a location between the sealing seat region 50 and the distal end 46 of the injector cup, corresponding to the second chamber 52 leading to the environment. Therefore, the line 62 can be at an angle θ relative to the sidewall centerline 44. In some embodiments, the angle θ can be zero, thereby the line is parallel to the sidewall centerline 44, and the injector cup 40 is substantially below the main pipe 10. For an angle θ of zero degrees, the injector cup centerline 44 can be offset in the X direction relative to the longitudinal axis 16 of the main pipe by a distance corresponding to the diameter of the orifice 47. As used herein, the X and Y directions are referenced with respect to orthogonal reference axes X and Y with their origin on the longitudinal axis 16 of the main pipe. The X and Y axes are perpendicular to the main pipe centerline, and the Y axis is parallel to the injector cup centerline 44.

[0047] The maximum angle θ is the angle at which the orifice 60 passes outward 59 through the injector cup directly below the sealing region 50 and inward 53 through the injector cup directly above the sealing region 50. Therefore, the maximum angle θ is limited by the geometry of the injector cup 40, which includes the orifice diameter and the longitudinal dimension of the sealing region 50. In some embodiments, for example, the angle θ may be in the range of 0 to 70 degrees. In other embodiments, the angle θ may be in the range of 0 to 45 degrees. When the angle θ is maximized, the injector cup 40 can be positioned along the injector cup sidewall 41. In this configuration, compared to the injector cup 40 configuration when the angle θ is zero, the injector cup 40 can be closer to the main longitudinal axis 16 in the y-direction and further away from the centerline in the x-direction.

[0048] Fuel passages 22 are formed in the fuel rail structure 22, which is further formed from a single piece having an integral injector cup 40, by having orifices 60 pass through opposite sides 53, 59 (or 45, 46) of the injector cup 40 at an angle. This configuration allows for injector cups 40 that are offset in both the X and Y directions from the centerline 16 of the main pipe 10. For example, see reference... Figures 2-5 The orientation of the fuel rail structure shown (which is not intended to be restrictive) allows the injector cup 40 to be positioned offset from and below the longitudinal axis 16 of the main pipe. Because the injector cup 40 can be provided offset in the X and Y directions relative to the long centerline 16, engine designers have greater flexibility in integrating the fuel rail assembly into the engine.

[0049] Furthermore, because the fuel rail structure 2 can be formed as a single, integral structure, it can directly replace some conventional fuel rail devices that are multi-part welded assemblies. In other words, the integral fuel rail structure 2 is "backward compatible," allowing vehicle engines to be upgraded to increase fuel pressure and reduce the number of parts, requiring only limited redesign and testing of cylinder heads, fuel injectors, pressure sensors, connecting pipes, and electrical fixtures. This reduces the risk of untested components and saves construction time and money. The integral fuel rail structure 2 allows for the reuse of equipment and process measurements. Moreover, by providing the integral fuel rail structure 2, multiple components and their fastening processes (positioning welding and brazing) can be eliminated, thereby reducing the number and location of potential failures and quality control methods.

[0050] refer to Figure 6 and Figure 7 Alternative embodiments of the integral fuel rail structure 200 are similar to those described above regarding Figures 1-5The fuel rail structure 2 is described above, and common reference numerals are used to refer to common elements. The integral fuel rail structure 200 differs from previous embodiments in that it includes a relatively longer distribution arm 220 and fuel passage 222. For example, in the illustrated embodiment, the distribution arm 220 is long enough that the injector cup 40 is spaced apart from the main pipe 10. Advantageously, because the distribution arm 200 is relatively long, the X-offset of the injector cup 40 is relatively larger compared to previous embodiments. Because the injector cup 40 can be provided with a relatively larger X-offset relative to the long centerline 16, engine designers can integrate the fuel rail assembly into the engine with even greater flexibility.

[0051] refer to Figure 8 The fuel rail structures 2 and 200, including the main pipe 10, distribution arms 20 and 200, and injector cup 40, are manufactured as an integral structure during a forging process. As used herein, the term "forging process" refers to the forming process in which a metal billet is heated until it is malleable but not melted and mechanically pressed into the desired shape. This can be done manually, for example by hand hammering, or by machine, for example by electric hammering, high-pressure stamping, or pressing. In the illustrated embodiment, the fuel rail structure 2 is manufactured using the following manufacturing steps.

[0052] In the initial step (step 200), a metal billet is provided. The billet is the raw material block that will be used to form the fuel rail structure. In the illustrated embodiment, the material is stainless steel, although other possible materials may include, but are not limited to, low-carbon high-strength steel and high-strength aluminum.

[0053] The metal billet is then heated (step 202) to a predetermined temperature sufficient to facilitate forging of the billet and below the melting temperature of the metal. In an example where the material used to form the billet is stainless steel, the predetermined temperature may be in the range of 600 degrees Celsius to 1000 degrees Celsius, depending on the process requirements.

[0054] Following the heating step, the heated metal billet undergoes a forging step (step 204) to provide an integral fuel rail structure. The resulting preliminary fuel rail structure has an irregular and complex shape and is a solid body (e.g., the preliminary fuel rail structure has no internal cavities). The preliminary fuel rail structure includes a solid main pipe portion and solid protrusions corresponding to the distribution arm portion and the injector cup portion. Multiple alternating heating and forging steps are required on the billet before the preliminary fuel rail structure achieves the desired shape. Excess material is trimmed from the preliminary fuel rail structure as needed.

[0055] The initial fuel rail structure is then machined to provide the desired internal cavities and / or passageways. For example, a first machining step (step 206) may include forming a first hole in the initial fuel rail structure using an auger. Specifically, the first hole is formed in the main pipe portion, and it corresponds to the main fuel passage 15. The first hole is a straight hole extending along the longitudinal axis 16 of the main pipe. In some embodiments, the first hole is a blind hole opening at a fuel inlet in the first end 11 of the main pipe. In other embodiments, the first hole is a through hole opening at both the first and second ends 11, 12 of the main pipe. In the case of a through hole, the first end 11 of the main pipe may be configured to provide a fuel inlet, and the second end 12 of the main pipe may be plugged. Although an auger can be used, the first machining step 206 is not limited to being performed using an auger. For example, in some embodiments, the first hole may be formed by using an EDM process or other suitable machining process.

[0056] The second machining step (step 208) may include forming a second hole in the initial fuel rail structure using an auger. Specifically, the second hole is formed in the injector cup portion and corresponds to injector cup orifice 47. The second hole is a straight blind hole opening at the distal end 46 of the injector cup. Because orifice 47 includes a sealing seat region 50 that may have a different diameter than the injector retention region 54, the second machining step 208 may include multiple sub-steps using machining tools with different diameters. While an auger can be used, the second machining step 208 is not limited to being performed using an auger. For example, in some embodiments, the second hole may be formed using an EDM process or other suitable machining process.

[0057] The third machining step (step 210) may include forming a third hole in the preliminary fuel rail structure using an EDM process. Specifically, the third hole will form a fuel passage 22 in the distribution arm portion. The third hole is a straight through-hole that passes through the injector cup portion and the distribution arm portion and connects the hole 47 to the main fuel passage 15 of the main pipe 10. Specifically, the third hole enters the preliminary structure of the main pipe at a position corresponding to the second portion 40(2) of the injector cup, outward along the injector cup. Therefore, the entry position of the third hole is set on the side of the injector cup portion away from the main pipe portion. The third hole extends linearly along line 62 and passes through the injector cup inward 53 at a position corresponding to the first portion 40(2) of the injector cup. Line 62 is appropriately angled to avoid the sealing seat area 50 and extends through the distribution arm portion and intersects the main fuel passage 15.

[0058] A rotary EDM process using a rigid linear (e.g., straight) electrode is used to create the third hole, which advantageously provides a precisely and uniformly sized hole without cutting chips. While the third hole can be formed using other machining processes such as auger drilling or laser cutting, in some cases such processes can disadvantageously leave debris or burrs in the hole. This step forms the fuel passage 22, which extends along a straight line 62. In some embodiments, the fuel passage 22 is at a non-zero angle relative to the centerline 44 of the injector cup 40, and the inlet hole of the third machining step 210 is provided in the sidewall 41 of the injector cup 40.

[0059] The fourth machining step (step 212) may include forming fourth and fifth holes in the preliminary fuel rail structure using a spiral drill. Specifically, the fourth and fifth holes are formed in the injector cup portion and correspond to through holes 55 received in the injector retaining pin 58. The fourth and fifth holes may be through holes.

[0060] The first, second, third, and fourth machining steps 206, 208, 210, and 212 can be performed in any order.

[0061] Following the first, second, third, and fourth machining steps 206, 208, 210, and 212, the machined preliminary fuel rail structure undergoes a chemical deburring step (step 214). For example, the machined preliminary fuel rail structure can be immersed in an electroplating bath, which removes burrs and sharp edges and produces the finished fuel rail structure 2, 200.

[0062] Although the fuel rail structure 2 is described herein as a monolithic structure made from a single piece during the forging process, the fuel rail structure 2 is not limited to being manufactured via a forging process. For example, the fuel rail structure can be manufactured as a monolithic structure via other processes, such as, but not limited to, casting or injection molding.

[0063] While the illustrated embodiments include a fuel rail structure that supplies high-pressure fuel directly to the cylinders of an engine via fuel injectors, the fuel rail structure is not limited to use in high-pressure direct injection fuel supply systems. For example, in other embodiments, the fuel rail structure may supply fuel at a relatively low pressure. In yet other embodiments, the fuel rail structure may supply fuel indirectly to the cylinders, for example, via an inlet port.

[0064] The foregoing has described selective illustrative embodiments of the integral fuel rail structure and its manufacturing method in some detail. It should be understood that only structures deemed necessary to define the fuel rail structure have been described herein. It is assumed that other conventional structures, as well as those including auxiliary and supplementary components such as the hydraulic circuit of the reuse device, are known and understood by those skilled in the art. Furthermore, while working examples of the integral fuel rail structure and its manufacturing method have been described for the foregoing, the integral fuel rail structure and its manufacturing method are not limited to the working examples described above, and various design modifications may be implemented without departing from the integral fuel rail structure and its manufacturing method as set forth in the claims.

Claims

1. An integral fuel rail structure configured to receive and support a fuel injector having an injector housing, a fuel inlet end, a fuel outlet end opposite to the fuel inlet end, and a seal disposed on the outer surface of the injector housing, the integral fuel rail structure comprising: director; The injector cup protrudes integrally from the outer surface of the main body; as well as Fuel passage, in The supervisors include: The first end of the supervisory department; The second end of the main tube opposite to the first end of the main tube; and The inner surface of the main pipe defines a main fuel passage concentric with the longitudinal axis of the main pipe, the longitudinal axis of the main pipe extending between a first end and a second end of the main pipe. The injector cup includes: Sidewall, the inner surface of which defines a hole; The proximal end of one end of the closed sidewall; and The distal end, opposite the proximal end, is open, and the midline of the sidewall extends through both the proximal end and the distal end. And among them The hole includes an opening end that coincides with the distal end. The hole includes a blind end disposed between the open end and the proximal end of the injector cup, and The fuel passage provides fluid communication between the orifice and the main fuel channel, wherein the orifice passes through the sidewall of the injector cup and includes a first section extending through the sidewall to the main pipe side and a second section extending through the sidewall to the side opposite to the main pipe side, the fuel passage corresponding to the first section of the orifice.

2. The integral fuel rail structure according to claim 1, wherein... The inner surface of the sidewall includes a sealing seat region that receives a seal when the fuel injector is disposed in the injector cup. The sealing seat region is located between the open end and the blind end. The hole coincides with a straight line passing through the sidewall, and the straight line includes... a) A first line portion located in the first part of the injector cup, the first part of the injector cup being disposed between the sealing seat region and the proximal end, and b) A second line portion located in the second part of the injector cup, the second part of the injector cup being disposed between the sealing seat region and the distal end.

3. The integral fuel rail structure according to claim 2, wherein... The sealing seat region has a larger dimension in a direction parallel to the centerline of the sidewall than the dimension of the seal in the same direction, so as to accommodate the movement of the fuel injector within the injector cup during operation of the fuel rail structure.

4. The integral fuel rail structure of claim 2, wherein the hole extends through a first portion of the sidewall, and the first portion of the injector cup includes the first portion of the sidewall.

5. The integral fuel rail structure of claim 2, wherein the hole extends through a second portion of the sidewall, and the second portion of the injector cup includes the second portion of the sidewall.

6. The integral fuel rail structure according to claim 2, wherein... The first line portion intersects the sidewall at a location between the sealing seat area and the blind end, and The second line portion intersects the sidewall at a location between the sealing seat area and the opening end.

7. The integral fuel rail structure according to claim 1, wherein... The hole coincides with the straight line passing through the sidewall. The straight line is at an angle θ relative to the Y-axis. The Y-axis intersects with and is perpendicular to the longitudinal axis of the main body. The Y-axis is parallel to the centerline of the sidewall, and The angle θ is in the range of 0 degrees to 45 degrees.

8. The integral fuel rail structure according to claim 1, wherein... The injector cup is connected to the outer surface of the main tube via a dispensing arm, the dispensing arm having a first end integral with the outer surface of the main tube and a second end integral with the injector cup. The fuel passage passes through the distribution arm.

9. The integral fuel rail structure of claim 8, wherein the distribution arm has sufficient length to space the injector cup from the main pipe.

10. The integral fuel rail structure according to claim 2, wherein the sealing seat region has a size in the range of 150% to 300% larger than the corresponding size of the seal in a direction parallel to the centerline of the sidewall.

11. A fuel rail assembly comprising an integral fuel rail structure and a fuel injector supported on the fuel rail structure, wherein The fuel injector includes: Injector housing; Fuel inlet end; The fuel outlet end opposite to the fuel inlet end; as well as A seal disposed on the outer surface of the injector housing. The integral fuel rail structure includes: director; The injector cup protrudes integrally from the outer surface of the main tube; and Fuel passage, The supervisors include: The first end of the supervisory department; The second end of the main tube opposite to the first end of the main tube; and The inner surface of the main pipe defines a main fuel passage concentric with the longitudinal axis of the main pipe, the longitudinal axis of the main pipe extending between a first end and a second end of the main pipe. The injector cup includes: Sidewall, the inner surface of which defines a hole; The proximal end of one end of the closed sidewall; and The distal end, opposite the proximal end, is open, and the midline of the sidewall extends through both the proximal end and the distal end. And among them The hole includes an opening end that coincides with the distal end. The hole includes a blind end disposed between the open end and the proximal end of the injector cup, and The fuel passage provides fluid communication between the orifice and the main fuel channel, wherein the orifice passes through the sidewall of the injector cup and includes a first section extending through the sidewall to the main pipe side and a second section extending through the sidewall to the side opposite to the main pipe side, the fuel passage corresponding to the first section of the orifice.

12. A method for manufacturing an integral fuel rail structure, the method comprising the following steps: Provide metal billets; The metal billet is heated to a predetermined temperature below the melting temperature of the metal; Forging a heated metal billet to provide an integral fuel rail structure comprising a main pipe and an injector cup integrally projecting from the outer surface of the main pipe, the injector cup comprising... Cylindrical sidewalls, the inner surface of which defines holes. The proximal end of one end of the closed sidewall, and The distal end, opposite the proximal end, is open; The main fuel passage is machined in the main pipe; A hole is machined in the injector cup; A fuel passage is machined in the fuel rail structure, the fuel passage providing fluid communication between the main fuel passage and the orifice, wherein the orifice passes through the sidewall of the injector cup and includes a first section extending through the sidewall to the main pipe side and a second section extending through the sidewall to the side opposite to the main pipe side, the fuel passage corresponding to the first section of the orifice.

13. The method of claim 12, wherein The inner surface of the injector cup includes a sealing seat region configured to receive a seal from the fuel injector. The sealing seat area is disposed between the proximal end and the distal end, and The step of machining the fuel passage in the fuel rail structure includes forming the hole such that it extends along a straight line, the straight line including... a) A first line portion located in the first part of the injector cup, the first part of the injector cup being disposed between the sealing seat region and the proximal end, and b) A second line portion located in the second part of the injector cup, the second part of the injector cup being disposed between the sealing seat region and the distal end.

14. The method of claim 12, wherein the hole is interrupted by the aperture.

15. The method of claim 12, wherein the step of machining the fuel passage in the fuel rail structure includes an electrical discharge machining process.

16. The method of claim 15, wherein the electrical discharge machining process uses a rigid straight electrode.

17. An integral fuel rail structure configured to receive and support a fuel injector relative to a cylinder of an engine, the integral fuel rail structure comprising: A main pipe with an inner surface that defines the primary fuel passage; An injector cup integrally protrudes from the outer surface of the main tube, and the inner surface of the injector cup defines an opening at one end of the injector cup; as well as A fuel passage providing fluid communication between the orifice and the main fuel channel. in The orifice passes through the sidewall of the injector cup and includes a first section extending through the sidewall towards the main pipe and a second section extending through the sidewall towards the opposite side of the main pipe, the fuel passage corresponding to the first section of the orifice.

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