Fuel delivery structure of an in-cylinder injection engine

Abstract

To approximately suppress occurrence of abnormal sound and noise resulting from fuel pressure pulsation in a fuel delivery pipe without causing cost increase.SOLUTION: A fuel delivery structure for a cylinder injection engine 1 includes a cylinder head 2, a cylinder head cover 3, an injector 4 for injecting fuel into a combustion chamber of the cylinder head 2, and a fuel delivery pipe 5 for forcibly feeding and supplying the fuel to the injector 4, where the fuel is injected directly into the combustion chamber to cause combustion with spark ignition. On a wave belly part AN of the fuel delivery pipe 5, whose amplitude or displacement is relatively greater or maximum when the fuel delivery pipe 5 is vibrated with the injection of fuel by the injector 4, an accessory part AP of the cylinder injection engine 1 such as a pressure sensor 6 or a union bolt 9 is mounted.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a spark ignition engine mounted on a vehicle, and particularly to a fuel delivery structure of an in-cylinder injection engine that directly injects fuel into a combustion chamber.

Background Art

[0002] Patent Document 1 describes an invention related to a fuel delivery structure (fuel delivery pipe) of an engine. The fuel delivery pipe described in this Patent Document 1 includes a fuel delivery pipe body to which a plurality of injectors are attached, and a hollow damper member provided inside the fuel delivery pipe body and having a sealed space. And, when the fuel delivery pipe distributes and supplies the fuel supplied into the fuel delivery pipe body to each injector, the damper member is configured to absorb fuel pressure pulsation by deforming. Further, a mass body (damper mass) is attached to the wall portion of the damper member that is the fuel pressure pulsation absorption portion in this Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The fuel delivery structure described in Patent Document 1 above is used in direct injection engines (so-called direct injection engines) that inject fuel directly into the combustion chamber from injectors. The fuel delivery pipe of the fuel delivery structure distributes and supplies high-pressure fuel, which is pumped from the fuel pump, to multiple injectors. The fuel delivery pipe is attached to and fixed to the cylinder head cover of the direct injection engine. In a direct injection engine, intermittent fuel injection by the injectors can cause pulsation (fuel pressure pulsation) in the pressure of the fuel flowing through the fuel delivery pipe. When such fuel pressure pulsation occurs, there was a concern that the resulting vibrations would be transmitted to the cylinder head cover, causing resonance or vibration in the cylinder head cover, or that abnormal noises or sounds would be emitted from the cylinder head cover. Therefore, in the fuel delivery pipe described in Patent Document 1, a mass body that functions as a damper mass is added to the hollow damper member described above. Therefore, according to the engine fuel delivery structure described in Patent Document 1, a damper member with a mass body attached can function as a mass damper to effectively absorb or attenuate fuel pressure pulsations in the fuel delivery pipe.

[0005] However, in the fuel delivery pipe described in Patent Document 1 above, the addition of a mass to the damper member increases processing time and material costs, which contributes to the increased cost of direct injection engines. The problem of abnormal noise and vibration emitted from the cylinder head cover, as described above, can be addressed by increasing the strength and rigidity of the cylinder head cover, for example, by adding reinforcing ribs to the cylinder head cover or increasing the thickness of the cylinder head cover plate. Alternatively, it is conceivable to provide a cover or soundproofing material to block the emission of noise and vibration. However, adding ribs or increasing the plate thickness goes against the requirement for weight reduction. Moreover, in either case, it ultimately contributes to the increased cost of direct injection engines.

[0006] This invention was conceived in response to the technical problems described above, and aims to provide a fuel delivery structure for an in-cylinder injection engine that can appropriately suppress the generation of abnormal noises and other noises caused by fuel pressure pulsations in the fuel delivery pipe without increasing costs. [Means for solving the problem]

[0007] To achieve the above objective, this invention provides a fuel delivery structure for an in-cylinder injection engine, comprising a cylinder head, a cylinder head cover attached to the cylinder head and covering the upper surface of the cylinder head, an injector for injecting fuel into the combustion chamber of the cylinder head, and a fuel delivery pipe for pressurizing and supplying the fuel to the injector, wherein the fuel is injected directly into the combustion chamber and burned by spark ignition, The fuel delivery pipe is positioned directly above the injector and connected to the injector, and is fixed to the cylinder head cover via a plurality of fastening bolt bosses provided at predetermined intervals, and the fuel delivery pipe has a main pipe section for circulating the fuel, The aforementioned fuel delivery pipe The area between the bosses for the fastening bolts of the P Wave fronts where the amplitude or displacement of the injector vibrates in conjunction with fuel injection is maximized, or where the amplitude or displacement becomes relatively large. It is a department, In the aforementioned wave bell, At least one of the following is attached to the fuel delivery pipe: a fuel hose that supplies the fuel, a joint member connecting the fuel delivery pipe and the fuel delivery pipe, and an electric wire connected to the electrical components of the in-cylinder injection engine, thereby increasing the mass of the corrugated section. It is characterized by the following: [Effects of the Invention]

[0013] The engine targeted by this invention is a spark-ignition engine, such as a gasoline engine, and is a direct-injection engine (a so-called direct injection engine) that injects fuel directly into the combustion chamber using an injector. The fuel delivery structure for supplying high-pressure fuel to the injector includes a fuel delivery pipe that pressurizes fuel between the fuel pump and the injector. When the injector intermittently injects fuel, the fuel delivery pipe vibrates due to the pulsation of fuel pressure (fuel pressure pulsation) within the fuel delivery pipe. When the fuel delivery pipe vibrates, the vibration is transmitted to the cylinder head cover, which may cause resonance or vibration in the cylinder head cover, or cause abnormal noise or noise to be emitted from the cylinder head cover. Therefore, in the fuel delivery structure for a direct-injection engine of this invention, a predetermined accessory component of the direct-injection engine is attached to the corrugated crust of the fuel delivery pipe. The corrugated bellows of the fuel delivery pipe are the antinodes of the vibration modes when the fuel delivery pipe vibrates as described above; that is, the parts where the amplitude or displacement of the vibration becomes relatively large or is at its maximum. The accessories of an in-cylinder injection engine are existing parts or components that are essential for constructing an in-cylinder injection engine, and therefore inevitably have a predetermined mass. For this reason, in the fuel delivery structure of the in-cylinder injection engine of this invention, the accessories attached to the corrugated bellows can function as damper masses. In other words, the fuel delivery pipe with the mass of the accessories added to the corrugated bellows can function as a mass damper. Therefore, vibrations of the fuel delivery pipe can be easily and effectively absorbed or damped by using existing accessories without using special parts, components, or vibration damping mechanisms.

[0014] Furthermore, the fuel delivery structure for an in-cylinder injection engine of this invention is applicable to an in-cylinder injection engine in which the fuel delivery pipe is positioned directly above the injector, that is, almost directly above the injector in the vertical direction. Alternatively, the fuel delivery structure for an in-cylinder injection engine of this invention is applicable to an in-cylinder injection engine in which the fuel delivery pipe is positioned directly above the cylinder head cover and the combustion chamber of the cylinder head, that is, a so-called center injection type in-cylinder injection engine. In an in-cylinder injection engine with such a configuration, the distance between the fuel delivery pipe and the cylinder head cover increases because the diameter of the fuel delivery pipe is increased in the space between the fuel delivery pipe and the injector in order to connect the fuel delivery pipe and the injector, and to pump high-pressure fuel. In other words, the height of the boss member that fixes the fuel delivery pipe to the cylinder head cover increases. As a result, the fuel delivery pipe becomes more susceptible to vibration. For an in-cylinder injection engine with such a configuration, the fuel delivery structure for the in-cylinder injection engine of this invention allows for easy and effective absorption or damping of vibrations of the fuel delivery pipe by attaching existing accessories to the corrugated fins of the fuel delivery pipe, as described above.

[0015] Furthermore, in the fuel delivery structure for the in-cylinder injection engine of this invention, accessories for the in-cylinder injection engine such as a pressure sensor (fuel pressure sensor) for detecting fuel pressure, a coupling member (union bolt, etc.) for connecting the fuel delivery pipe and the fuel hose, or an electric wire (wire harness, etc.) for connecting to electrical components are used. Therefore, by utilizing these existing parts and materials, vibrations of the fuel delivery pipe can be easily absorbed or dampened without increasing costs.

[0016] Therefore, according to the fuel delivery structure of the in-cylinder injection engine of this invention, it is possible to appropriately suppress the generation of abnormal noises and sounds caused by fuel pressure pulsations in the fuel delivery pipe without increasing costs. [Brief explanation of the drawing]

[0017] [Figure 1] Figure 1 is a diagram illustrating the fuel delivery structure of the in-cylinder injection engine of the present invention, and is a perspective view showing the cylinder head and cylinder head cover of the in-cylinder injection engine to which the fuel delivery structure of the present invention is applied. [Figure 2] Figure 2 is a diagram illustrating the fuel delivery structure of the in-cylinder injection engine of this invention, and is a perspective view showing the basic structure of the injector. [Figure 3] Figure 3 is a diagram illustrating the fuel delivery structure of the in-cylinder injection engine of this invention, and is a perspective view showing the basic structure of the fuel delivery pipe. [Figure 4] Figure 4 is a diagram illustrating the fuel delivery structure of the in-cylinder injection engine of this invention, and is a perspective view showing the fuel delivery pipe arranged on the cylinder head cover, and the wire harness (accessory part) used in the in-cylinder injection engine. [Figure 5] Figure 5 is a diagram illustrating the fuel delivery structure of the in-cylinder injection engine of this invention, and is a top view showing a fuel pressure sensor (accessory) attached to the rear end (corrugated fin) of the fuel delivery pipe. [Figure 6] Figure 6 is a perspective view showing an example of an accessory component for an in-cylinder injection engine that is attached to the corrugated fin of the fuel delivery pipe, and shows the shape of a union bolt (accessory component) that connects the fuel delivery pipe and the fuel hose. [Figure 7] Figure 7 is a schematic diagram showing an example of an accessory component for an in-cylinder injection engine that is attached to the corrugated fin of the fuel delivery pipe, illustrating how the fuel delivery pipe and fuel hose are connected by a union bolt (accessory component). [Figure 8] Figure 8 is a diagram illustrating the operation and effect of the fuel delivery structure of the in-cylinder injection engine of this invention, and shows the frequency analysis results with union bolts (accessory parts) attached to the corrugated crusts of the fuel delivery pipe. [Modes for carrying out the invention]

[0018] Embodiments of the present invention will be described with reference to the drawings. Note that the embodiments shown below are merely examples of the present invention when embodied, and do not limit the present invention.

[0019] The in-cylinder injection engine in the embodiments of the present invention is typically a spark ignition engine that uses gasoline, and in addition, for example, LP gas, alcohol, or hydrogen as fuel. In particular, it is an in-cylinder injection (direct injection) engine that directly injects fuel into the combustion chamber. Further, the in-cylinder injection engine targeted in the embodiments of the present invention is a direct injection engine of a so-called center injection system in which an injector for injecting fuel is arranged almost directly above the combustion chamber, as will be described later. And, as shown in FIG. 1, the in-cylinder injection engine (hereinafter, the engine) 1 in the embodiments of the present invention includes a cylinder head cover 3 that covers the upper surface of the cylinder head 2.

[0020] The cylinder head cover 3 is made of metal, for example, an aluminum alloy or a magnesium alloy, and a material with higher strength and rigidity is adopted compared with the existing "resin-made cylinder head cover". For example, in the example shown in FIG. 1, the cylinder head cover 3 made of an aluminum alloy produced by the aluminum die-casting method is used. As shown in FIG. 1, the cylinder head cover 3 is formed with an injector arrangement hole 3a for arranging an injector 4 described later, and a boss 3b for fastening bolts for fixing a fuel delivery pipe 5 described later.

[0021] The injector arrangement hole 3a is a through hole formed at a predetermined position on the cylinder head cover 3 corresponding to the arrangement position of the injector 4 installed directly above a combustion chamber (not shown) formed in the cylinder head 2. In the example shown in FIG. 1, the cylinder head cover 3 is provided with injector arrangement holes 3a at four positions corresponding to the four injectors 4, respectively.

[0022] The boss 3b for the fastening bolt is a boss-shaped part for attaching the fuel delivery pipe 5 to the cylinder head cover 3 by bolt fastening. A screw hole (not shown) for screwing in a fastening bolt (not shown) is formed in the boss 3b for the fastening bolt.

[0023] In addition, in the cylinder head cover 3, a spark plug placement hole 3c for fixing a spark plug (not shown) and a bolt hole 3d for attaching the cylinder head cover 3 to the cylinder head 2 by bolt fastening are formed.

[0024] In a direct injection engine such as the engine 1 in the embodiment of this invention, for example, in order to cope with the increase in fuel injection pressure, compared with a conventional port injection type engine, a higher strength and rigidity are required for the cylinder head cover 3. Also, by adopting the center injection method as described above, the space for arranging the injector 4 on the cylinder head cover 3 becomes smaller, and as a result, the strength margin of the cylinder head cover 3 also becomes smaller. Therefore, in the engine 1 in the embodiment of this invention, a metal cylinder head cover 3 with high strength and rigidity is adopted. Thereby, it is possible to appropriately ensure the strength and rigidity of the cylinder head cover 3 in response to the increase in fuel injection pressure and the special structure of the center injection method.

[0025] And the fuel delivery structure of the in-cylinder injection engine in the embodiment of this invention includes an injector 4 and a fuel delivery pipe 5 as shown in FIGS. 2, FIGS. 3, FIGS. 4, and FIGS. 5.

[0026] The injector 4 is a component that injects fuel into the combustion chamber of the cylinder head 2. As described above, the engine 1 in the embodiment of this invention is a direct injection engine of the center injection type. Therefore, the injector 4 is arranged directly above the combustion chamber (substantially directly above in the vertical direction) in the cylinder head cover 3 and the cylinder head 2.

[0027] As shown in Figure 2, the injector 4 is basically configured the same as a conventional "center injection type injector". That is, the main body (nozzle holder) 4a of the injector 4 is almost straight, and the injector mounting portion 5b of the fuel delivery pipe 5, which will be described later, is connected to its upper end 4b, and high-pressure fuel is supplied from the fuel delivery pipe 5. Inside the main body 4a of the injector 4, a valve mechanism (not shown) is formed from a solenoid (not shown) and a plunger (not shown). An injection nozzle portion 4c is formed at the tip (lower end) of the main body 4a, which directly injects fuel into the combustion chamber of the cylinder head 2.

[0028] In the example shown in Figure 2, the injector 4 is equipped with a nozzle holder clamp 4d. The nozzle holder clamp 4d tightens and connects the upper end portion 4b of the injector 4 to the injector mounting portion 5b of the fuel delivery pipe 5. At the same time, the nozzle holder clamp 4d is structured to press the injector 4 toward the cylinder head 2 by the elastic force of a spring (not shown). Therefore, for example, when starting the engine 1, where the fuel injection pressure is relatively low, the movement of the injector 4 due to combustion pressure can be suppressed, thereby improving the airtightness between the injector 4 and the cylinder head 2. In addition, vibrations and noise caused by the movement of the injector 4 can be reduced.

[0029] The fuel delivery pipe 5 supplies high-pressure fuel discharged from a fuel pump (not shown) to the injectors 4 under pressure. In the example shown in Figure 3, injectors 4 are installed in each of the four injector placement holes 3a formed in the cylinder head cover 3, and the fuel delivery pipe 5 distributes and supplies fuel to these four injectors 4.

[0030] As shown in Figure 3, the fuel delivery pipe 5 basically has the same configuration as a conventional "fuel delivery pipe for a direct injection engine." That is, it has a straight pipe section 5a with a predetermined length corresponding to the number of injectors 4 that supply fuel, and an injector mounting section 5b.

[0031] The main pipe section 5a is a tubular member connected to the fuel pump and extending in the direction of the main flow of fuel discharged from the fuel pump. Therefore, the longitudinal direction of this main pipe section 5a is the direction of the main flow or supply of fuel in the fuel delivery pipe 5.

[0032] The injector mounting section 5b is a boss-shaped part that branches off from the main pipe section 5a, and the injector 4 is connected and mounted thereto. As described above, the upper end portion 4b of the injector 4 is attached to the injector mounting section 5b using the nozzle holder clamp 4d.

[0033] In the example shown in Figure 3, the fuel pressure sensor 6 is mounted at part AN1, near the center of the main pipe section 5a in the longitudinal direction of the fuel delivery pipe 5. In the example shown in Figure 5, which will be described later, the fuel pressure sensor 6 is mounted at part AN2, near the tip (right end in Figure 5) of the main pipe section 5a in the longitudinal direction of the fuel delivery pipe 5. The fuel pressure sensor 6 is a pressure sensor that detects the pressure of the high-pressure fuel injected from the injector 4, and is an accessory part AP for the entire engine 1, including the fuel delivery structure. Accessory parts AP are existing parts or components that are essential for constructing the engine 1. As will be described later, in the fuel delivery structure of the in-cylinder injection engine in this embodiment of the invention, accessory parts AP such as this fuel pressure sensor 6 are attached to the above-mentioned parts AN1 and AN2, that is, to the corrugated sections AN1 and AN2 of the fuel delivery pipe 5, and function as a "damper mass".

[0034] Furthermore, in this embodiment of the invention, the fuel delivery pipe 5 is positioned directly above the injector 4 (directly above in the vertical direction) and connected to the upper end portion 4b of the injector 4. In this state, the fuel delivery pipe 5 is fixed to the metal cylinder head cover 3.

[0035] As described above, in order to fix the fuel delivery pipe 5 to the cylinder head cover 3, a fastening bolt boss 5c is formed on the fuel delivery pipe 5. The fastening bolt boss 5c is a boss-shaped part for attaching the fuel delivery pipe 5 to the cylinder head cover 3 by bolt fastening. As shown in Figures 3 and 4, a bolt hole (through hole) 5d is formed on the fastening bolt boss 5c for inserting the fastening bolt 7.

[0036] Furthermore, in the fuel delivery structure of the in-cylinder injection engine according to this embodiment of the invention, a predetermined accessory AP of the engine 1 is attached to the corrugated surface AN of the fuel delivery pipe 5.

[0037] Wave bellows AN are the antinodes of vibration modes when the fuel delivery pipe 5 vibrates due to the fuel pressure pulsations described above. These are the areas where the amplitude or displacement of the vibration is relatively large, or where the amplitude or displacement of the vibration is maximum. In the example shown in Figure 3, the fuel pressure sensor 6 is attached as an accessory AP to area AN1, which is near the center of the main pipe section 5a of the fuel delivery pipe 5 in the longitudinal direction. In other words, in the example shown in Figure 3, area AN1 is the wave bellows AN1 of the fuel delivery pipe 5. In the example shown in Figure 5, the fuel pressure sensor 6 is attached as an accessory AP to area AN2, which is near the tip (right end in Figure 5) of the main pipe section 5a of the fuel delivery pipe 5 in the longitudinal direction. In other words, in the example shown in Figure 5, area AN2 is the wave bellows AN2 of the fuel delivery pipe 5.

[0038] Engine 1 accessory parts AP are those that are involved in the structure or operation of Engine 1, or that constitute Engine 1, and are essential parts or components for the construction of Engine 1. In the example shown in Figures 3 and 5, a fuel pressure sensor (pressure sensor) 6 is attached to the fuel delivery pipe 5 as an accessory part AP. The fuel pressure sensor 6 necessarily has a predetermined mass. Therefore, by being attached to the wave fin AN of the fuel delivery pipe 5, the fuel pressure sensor 6 functions as a damper mass in the vibration system when the fuel delivery pipe 5 vibrates.

[0039] In other words, in the fuel delivery structure of the in-cylinder injection engine according to this embodiment of the invention, the fuel delivery pipe 5, to which the mass of the fuel pressure sensor 6 is attached to the wave bell AN as described above, can function as a mass damper. Therefore, vibrations of the fuel delivery pipe 5 can be easily and effectively absorbed or damped by using existing accessory components AP such as the fuel pressure sensor 6.

[0040] In the fuel delivery structure of the in-cylinder injection engine in this embodiment of the invention, in addition to the fuel pressure sensor 6 described above, a predetermined accessory component AP may be attached to the corrugated section AN of the fuel delivery pipe 5. For example, a wire harness 8 as shown in Figure 4 can be attached to the corrugated section AN of the fuel delivery pipe 5 to function as a damper mass. The wire harness 8 is an electric wire or bundle of electric wires connected to the electrical components (not shown) of the engine 1, and is an accessory component AP that is essential for operating the engine 1. Although not shown in Figure 4, by attaching and fixing a predetermined binding portion (not shown) of such a wire harness 8 to the corrugated section AN of the fuel delivery pipe 5, it can function as a damper mass in the vibration system of the fuel delivery pipe 5, similar to the case of the fuel pressure sensor 6 described above.

[0041] Alternatively, a union bolt 9, as shown in Figure 6, may be attached to the corrugated surface AN of the fuel delivery pipe 5. The union bolt 9 is a connecting member that links the fuel delivery pipe 5 with the fuel hose 10 that supplies high-pressure fuel to the fuel delivery pipe 5, as shown in the image in Figure 7, and is an accessory component AP that is essential for constructing the engine 1 (especially the fuel delivery structure of the engine 1). For example, by attaching and fixing a union bolt 9 adjusted to the required weight to the corrugated surface AN of the fuel delivery pipe 5, it can function as a damper mass in the vibration system of the fuel delivery pipe 5, similar to the case of the fuel pressure sensor 6 described above.

[0042] Figure 8 shows the results of an analysis to explain the effects of the fuel delivery structure of the in-cylinder injection engine in this embodiment of the invention. The example shown in Figure 8 shows the results of an analysis of the vibration mode of the cylinder head cover 3 in the direction perpendicular to the surface when the union bolt 9 (i.e., accessory part AP) as described above is attached as a damper mass to the corrugated crust AN (part AN2 in Figure 5) of the fuel delivery pipe 5. Furthermore, the example shown in Figure 8 is an analysis result for a V-type engine 1, and the vibration mode of the cylinder head cover 3 on the right bank side, to which the union bolt 9 is attached, is shown by a solid line, and the vibration mode of the cylinder head cover 3 on the left bank side is shown by a dashed line. For comparison, the union bolt 9 as a damper mass is not attached to the fuel delivery pipe 5 on the left bank side.

[0043] As shown in Figure 8, when an excitation force is applied to the left and right fuel delivery pipes 5, the left and right cylinder head covers 3 to which each fuel delivery pipe 5 is attached vibrate. The left and right cylinder head covers 3 basically exhibit similar vibration modes, but in the example shown in Figure 8, a difference is observed depending on the presence or absence of the union bolt 9. Specifically, in the cylinder head cover 3 on the right bank side, where the union bolt 9 is attached as a damper mass, the inertance is reduced in the noise generation range between approximately 1.3 kHz and approximately 1.5 kHz. On the other hand, in the cylinder head cover 3 on the left bank side, where the union bolt 9 is not attached as a damper mass, no reduction in inertance is observed in the above noise generation range. Therefore, it can be seen that by attaching an accessory part AP such as the union bolt 9 to the corrugated bunker AN of the fuel delivery pipe 5 and allowing it to function as a damper mass, vibration and noise suppression effects can be obtained.

[0044] As described above, the fuel delivery structure for an in-cylinder injection engine in this embodiment of the present invention can appropriately suppress the generation of abnormal noise and other noises caused by fuel pressure pulsation in the fuel delivery pipe 5 without using special parts or materials, by utilizing existing accessory parts AP, that is, without increasing costs. [Explanation of Symbols]

[0045] 1. In-cylinder injection engine (direct injection engine with center injection system) 2 Cylinder heads 3 Cylinder head cover 3a Injector placement hole (formed in the cylinder head cover) 3b Bosses for fastening bolts (formed on the cylinder head cover) 3c (Spark plug mounting hole formed in the cylinder head cover) 3D (bolt holes formed in the cylinder head cover) 4 Injectors 4a (Injector) main body (nozzle holder) 4b Upper end (of the injector) 4c (Injector) nozzle section 4d (Injector) Nozzle Holder Clamp 5. Fuel delivery pipe 5a Main section (of the fuel delivery pipe) 5b Injector mounting section (of the fuel delivery pipe) 5c (Boss for fastening bolts on fuel delivery pipes) 5d (Fuel delivery pipe) Bolt hole (through hole) 6. Fuel pressure sensor (pressure sensor: included part) 7 Fastening bolts 8. Wire harness (electrical wires: included parts) 9 Union bolt (joint component: accessory part) 10 Fuel hose AP accessory parts AN, AN1, AN2 wave abdominal area (the area where attached components are mounted)

Claims

[Claim 1] A fuel delivery structure for an in-cylinder injection engine, comprising a cylinder head, a cylinder head cover attached to the cylinder head and covering the upper surface of the cylinder head, an injector for injecting fuel into the combustion chamber of the cylinder head, and a fuel delivery pipe for supplying the fuel to the injector under pressure, wherein the fuel is injected directly into the combustion chamber and burned by spark ignition, The fuel delivery pipe is positioned directly above the injector and connected to the injector, and is fixed to the cylinder head cover via a plurality of fastening bolt bosses provided at predetermined intervals. The fuel delivery pipe has a main pipe section through which the fuel flows, The portion of the fuel delivery pipe between the bosses for the fastening bolts is a wave-like structure where the amplitude or displacement is maximized when the injector vibrates in conjunction with the injection of fuel, or where the amplitude or displacement is relatively large. At least one of the following is attached to the corrugated section: a joint member connecting the fuel hose that supplies fuel to the fuel delivery pipe and the fuel delivery pipe, and an electric wire connected to the electrical components of the in-cylinder injection engine, thereby increasing the mass of the corrugated section. A fuel delivery structure for an in-cylinder injection engine characterized by the following.

Images