JP2008190508A - Fuel rail of internal combustion engine and fuel supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel rail and a fuel supply device capable of damping both of pulsation caused by fuel injection generated in a low pressure fuel passage and pulsation caused by a high pressure pump. <P>SOLUTION: In the low pressure fuel rail 32, the fuel port circumferential wall 39 of a first damper 36 is connected to an outer pipe 70, and a fuel port 37 is made to communicate with a pressure accumulation chamber 33. An inner pipe 100 is connected to the fuel port circumferential wall 39c of a second damper 38, and a fuel port 106 having a larger L-D ratio which is a ratio of a port length and a port diameter compared with that of the fuel port 37 of the first damper 36. The inner pipe 100 is inserted into the pressure accumulation chamber 33, and the fuel port 106 is made to communicate with the pressure accumulation chamber 33. The first damper 36 damps the pulsation caused by fuel injection, and a second damper assembly (38, 100) damps the pulsation caused by the high pressure pump having a low frequency. Since the inner pipe 100 is inserted in the pressure accumulation chamber 33, the pulsation caused by the high pressure pump can be damped by a compact structure. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel rail and a fuel supply device used for an internal combustion engine, and in particular, a low pressure fuel injection device that injects fuel from a low pressure fuel passage into an intake passage, and a high pressure that injects fuel from a high pressure fuel passage into a cylinder. The present invention relates to a fuel rail and a fuel supply device that supply fuel to a low-pressure fuel injection device in an internal combustion engine that includes a fuel injection device and a high-pressure fuel pump that sucks fuel from a low-pressure fuel passage and boosts the pressure.

  In recent years, some internal combustion engines include both a low-pressure fuel injection device that injects fuel into an intake passage and a high-pressure fuel injection device that injects fuel into a cylinder. Such an internal combustion engine usually has a fuel pump (hereinafter referred to as a low-pressure fuel pump) that pumps fuel from a fuel tank and pumps it, and a fuel pump (hereinafter referred to as a low-pressure fuel pump) that further boosts the pressure of the fuel pumped from the low-pressure fuel pump. , Referred to as a high-pressure fuel pump).

  The low-pressure fuel pump pumps low-pressure fuel from the fuel tank to a fuel passage (hereinafter referred to as a low-pressure fuel passage) communicating with the low-pressure fuel injection device. The low-pressure fuel injection device supplies fuel from the low-pressure fuel passage. In response to the supply, low-pressure fuel is injected into the intake passage. The low pressure fuel passage supplies fuel not only to the low pressure fuel injection device but also to the high pressure fuel pump. The high-pressure fuel pump sucks low-pressure fuel from the low-pressure fuel passage, boosts the pressure inside, and pumps high-pressure fuel into a fuel passage (hereinafter referred to as a high-pressure fuel passage) that communicates with the high-pressure fuel injection device. The high-pressure fuel injection device receives a supply of high-pressure fuel from a high-pressure fuel passage and injects fuel directly into the cylinder.

  Such a high-pressure fuel pump generally includes a pressurizing chamber whose volume changes periodically according to the engine speed of the internal combustion engine, and a communication between the low-pressure fuel passage and the pressurizing chamber by opening and closing the valve body. / A valve with a shut-off valve that can be switched off is used. Fuel is sucked into the pressurizing chamber from the low pressure fuel passage by increasing the volume of the pressurizing chamber, and the sucked fuel is boosted by decreasing the volume of the pressurizing chamber. The pressure is fed into the high-pressure fuel passage (see, for example, Patent Document 1).

  In addition, Patent Document 1 discloses that the fuel distribution pipe and the intake side of the high-pressure fuel pump (upstream of the metering valve) include a pulse generator in order to stabilize the fuel pressure in the low-pressure fuel passage including the inside of the fuel distribution pipe. A session damper is provided. Thereby, the fuel pressure pulsation generated in the low pressure fuel passage is attenuated.

JP 2006-144628 A

  By the way, in the case of a fuel supply device including a high-pressure fuel pump as in Patent Document 1, when the volume of the pressurizing chamber is reduced, the closing period of the shutoff valve is changed to control the pumping amount of the high-pressure fuel pump. Back flow into the low pressure fuel passage. Such a backflow may occur periodically according to the volume change of the pressurizing chamber, that is, the operation of the high-pressure fuel pump.

  If there is fuel that periodically flows back from the high-pressure fuel pump to the low-pressure fuel passage, fuel pressure pulsation, which is a periodic fluctuation of the fuel pressure, occurs in the low-pressure fuel passage. The fuel pressure pulsation generated in the low pressure fuel passage due to the operation of the high pressure fuel pump is simply referred to as “high pressure pump induced pulsation” in the following description. On the other hand, the fuel pressure pulsation generated in the low-pressure fuel passage due to the fuel injection of the low-pressure fuel injection device is distinguished by simply being referred to as “fuel injection-induced pulsation”. FIG. 5 shows an example of the fuel pressure pulsation in the low pressure fuel passage when the fuel injection pulsation and the high pressure pump pulsation occur simultaneously. The high-pressure pump-induced pulsation is generated according to the volume change of the pressurizing chamber, and as shown in FIG. 5, the cycle tends to be extremely long compared to the fuel injection pulsation.

  As described above, when a pulsation caused by a high-pressure pump having a long cycle occurs in the low-pressure fuel passage, in the low-pressure fuel injection device that receives the direct supply of fuel from the low-pressure fuel passage, the injection amount actually injected becomes a predetermined fuel injection amount. Deviation may occur in comparison. In addition, when the period of pulsation caused by the high-pressure pump is long, there may be variations in the injection amount injected by the low-pressure fuel injection device between different cylinders.

  Accordingly, a low-pressure fuel injection device that injects fuel into the intake passage, a high-pressure fuel injection device that injects fuel into the cylinder, a high-pressure fuel pump that can suck and boost the fuel from the low-pressure fuel passage, and can be pumped into the high-pressure fuel passage. In the internal combustion engine including the fuel rail and the fuel supply device for supplying fuel to the low-pressure fuel injection device, it is necessary to attenuate both the fuel injection-induced pulsation and the high-pressure pump-induced pulsation, which are greatly different in frequency.

  However, since the pulsation damper as in Patent Document 1 is mainly configured to attenuate the pulsation caused by fuel injection, the pulsation damper caused by high pressure pump having a lower frequency than the pulsation caused by fuel injection can be attenuated. is not. For this reason, in the fuel rail and the fuel supply device provided with the conventional pulsation damper, it is difficult to sufficiently attenuate both the fuel injection-induced pulsation and the high-pressure pump-induced pulsation generated in the low-pressure fuel passage.

  The present invention has been made in view of the above, and a fuel injection-induced pulsation that occurs in the low-pressure fuel passage due to the fuel injection of the low-pressure fuel injection device, and a low-pressure fuel passage that occurs due to the operation of the high-pressure fuel pump. It is an object of the present invention to provide a fuel rail and a fuel supply device that can attenuate both high-pressure pump-induced pulsations.

  In order to achieve the above object, a fuel rail according to the present invention includes a low pressure fuel injection device that injects fuel from a low pressure fuel passage into an intake passage, and a high pressure fuel injection that injects fuel from a high pressure fuel passage into a cylinder. A fuel rail for supplying fuel to a low-pressure fuel injection device, which is used in an internal combustion engine comprising a device and a high-pressure fuel pump capable of sucking fuel from a low-pressure fuel passage and boosting the pressure to the high-pressure fuel passage. An accumulator chamber is provided, and an outer pipe capable of supplying fuel in the accumulator chamber to the low-pressure fuel injection device, a first damper capable of attenuating fuel pressure pulsation through a fuel port connected to the accumulator chamber, and an outer pipe By connecting an inner pipe whose one end communicates with the pressure accumulating chamber, a fuel port portion having a larger L / D ratio, which is the ratio of the port length to the port diameter, is configured compared to the fuel port of the first damper. A second damper assembly capable attenuating the pressure pulsations, characterized in that it comprises a.

  In the fuel rail according to the present invention, the second damper assembly may include an inner pipe and a second damper having a fuel port having the same dimensions as the first damper, and the inner pipe has one end. And the other end is inserted into a pipe receiving portion provided in the outer pipe, and the space in the inner pipe is formed in the second damper assembly. It can be a fuel port.

  In the fuel rail according to the present invention, a port peripheral wall receiving portion into which the fuel port peripheral wall of the second damper can be inserted may be formed at an end of the outer pipe opposite to the pipe receiving portion. The fuel port peripheral wall of the second damper may be inserted into the port peripheral wall receiving portion so that the entire inner pipe is accommodated in the pressure accumulating chamber.

  In the fuel rail according to the present invention, a part of the inner pipe is provided outside the outer pipe, and the port length of the fuel port portion is set longer than the length in the longitudinal direction of the pressure accumulating chamber. be able to.

  In the fuel rail according to the present invention, the inner pipe may have communication holes arranged in the circumferential direction of the inner pipe to communicate the inside of the inner pipe with the pressure accumulating chamber.

  In the fuel rail according to the present invention, the pipe receiving portion of the outer pipe may be a cylindrical spacer that is provided in the pressure accumulation chamber and holds the inner pipe at a predetermined interval from the inner wall of the pressure accumulation chamber.

  In the fuel rail according to the present invention, a volume chamber is formed between the inlet and the inner pipe into which the fuel flows in the outer pipe, and the flow passage cross section of the fuel flowing from the inlet into the inner pipe is changed. Can be.

  The fuel supply apparatus according to the present invention may include the fuel rail, and the internal combustion engine may be mounted on an automobile as a prime mover, and the automobile has a vehicle body that flows fuel from a fuel tank toward the internal combustion engine. A fuel pipe may be provided. The fuel pipe closer to the internal combustion engine than the vehicle body fuel pipe includes a first low-pressure fuel pipe for flowing fuel toward the high-pressure fuel pump, and a first for flowing fuel toward the low-pressure fuel rail. It can be branched to two low pressure fuel pipes.

  According to the present invention, the first damper attenuates the fuel injection-induced pulsation, and the second damper assembly having the fuel port portion having an L / D ratio larger than the fuel port of the first damper causes the fuel injection-induced pulsation. The pulsation caused by the high-pressure pump having a lower frequency can be attenuated. Since the inner pipe that is longer than the fuel port peripheral wall of the first damper is inserted into the pressure accumulating chamber, it is possible to realize a fuel rail that can attenuate both injection-induced pulsation and high-pressure pump-induced pulsation with a compact configuration.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same.

  First, a schematic configuration of a fuel rail and a fuel supply device according to this embodiment and an internal combustion engine including the fuel rail will be described with reference to FIGS. 1 and 2. FIG. 1 is a cross-sectional view showing a schematic configuration around a cylinder of an internal combustion engine. FIG. 2 is a schematic diagram showing a schematic configuration of the fuel supply apparatus. In FIGS. 1 and 2, for the internal combustion engine and the fuel supply device, only the main parts related to the present invention are schematically shown.

  As shown in FIG. 1, in the internal combustion engine 10 according to the present embodiment, a low pressure fuel injection device 30 that injects low pressure (eg, 0.4 MPa) fuel into an intake passage as a fuel injection device that supplies fuel to a cylinder. A high-pressure fuel injection device 40 that injects high-pressure (for example, 10 MPa) fuel into the cylinder is provided for each cylinder.

  The “cylinder” is a space surrounded by the cylinder wall 15 of the cylinder block 14, the ceiling wall 22 of the cylinder head 20, and the top surface 28 (including the cavity wall 28 c) of the piston 27. The cylinder includes a combustion chamber 21 formed in the cylinder head 20 and a cavity formed in the piston 27.

  In addition, the “intake passage” means an air flow path through which air introduced from an outside air duct (not shown) passes into the cylinder. In this embodiment, the intake passage includes an intake manifold (not shown). In addition to the surge chamber and the branch passage, an intake port 24 of the cylinder head 20 is included.

  The low-pressure fuel injection device 30 is an electromagnetic fuel injection valve, and the injection period is controlled by a control device (not shown). The low pressure fuel injection device 30 is provided in an intake port formed in the cylinder head 20, and an injection hole is exposed to the intake port 24. When the low pressure fuel injection device 30 injects fuel into the intake passage, the injected fuel flows from the intake port 24 through the intake valve 25 into the cylinder. The low-pressure fuel injection device 30 receives supply of low-pressure (for example, 0.4 MPa) fuel from an outer pipe 70 of a fuel rail 32 that is a fuel distribution pipe described later.

  On the other hand, the high-pressure fuel injection device 40 is an electromagnetic fuel injection valve, and similarly, the injection period is controlled by a control device (not shown). The high-pressure fuel injection device 40 is provided on the ceiling wall 22 of the combustion chamber 21 formed in the cylinder head 20, and the injection hole is exposed to the combustion chamber 21. When the high-pressure fuel injection device 40 injects fuel into the combustion chamber 21, the injected fuel forms an air-fuel mixture in the cylinder. The high-pressure fuel injection device 40 is supplied with high-pressure (for example, 10 MPa) fuel from a high-pressure fuel rail that is a fuel distribution pipe described later.

  The internal combustion engine 10 according to the present embodiment is mounted on an automobile (not shown) as a prime mover, and as shown in FIG. 2, the automobile is a fuel supply device 1 that supplies fuel to the internal combustion engine 10. A fuel tank 80 for storing fuel injected by the fuel injection devices 30 and 40 and a vehicle body fuel pipe 90 for flowing fuel from the fuel tank 80 toward the internal combustion engine 10 are provided.

  The fuel tank 80 includes a low-pressure fuel pump 82 that is a pump that pumps up and pumps fuel as a low-pressure fuel system component that supplies the fuel in the fuel tank 80 to the internal combustion engine 10 at a predetermined fuel pressure, and dust contained in the fuel. And a pressure regulating valve (pressure regulator) 86 for adjusting the pressure of the fuel pumped from the low-pressure fuel pump 82 is provided.

  In the fuel tank 80, a fuel filter 84 is provided on the downstream side in the fuel flow direction of the low-pressure fuel pump 82, and a pressure regulating valve 86 is provided on the downstream side of the fuel filter 84. Connected to the pressure regulating valve 86 are a vehicle body fuel pipe 90 for supplying fuel toward the internal combustion engine 10 and a return pipe 87 for returning excess fuel to the fuel tank 80 again. The low-pressure fuel pump 82 is an electric fuel pump that pumps up fuel in the fuel tank 80 and pumps it toward the internal combustion engine 10.

  The pressure regulating valve 86 is divided into a housing and a diaphragm (not shown) to form a fuel chamber into which the fuel to be attenuated flows, and a spring (not shown) expands and contracts due to the pressure of the fuel flowing into the fuel chamber. Then, the valve element opens and moves when the diaphragm is bent. The pressure regulating valve 86 opens the valve body when the fuel pressure in the fuel chamber exceeds a predetermined pressure, and guides excess fuel to the return pipe 87. In this manner, the pressure regulating valve 86 regulates the fuel pressure in the fuel chamber and the fuel passage communicating with the fuel chamber to a predetermined pressure (for example, 0.4 MPa).

  The fuel pumped up by the low-pressure fuel pump 82 is sent to the pressure regulating valve 86 after the dust contained in the fuel is removed by the fuel filter 84. The pressure regulating valve 86 returns excess fuel that is not consumed by the fuel injection devices 30 and 40 from the fuel pumped up by the low-pressure fuel pump 82 from the return pipe 87 to the fuel tank 80 again. The pressure regulating valve 86 adjusts the fuel pressure of the low-pressure fuel pump 82 to a predetermined value (for example, 0.4 MPa), and causes the fuel to flow through the fuel hose 88 that extends outside the fuel tank. The fuel hose 88 is connected to the vehicle body fuel pipe 90.

  The vehicle body fuel pipe 90 is a metal pipe fixed to a vehicle body of an automobile such as an under floor, and a fuel passage 95 is formed therein. One end of the vehicle body fuel pipe 90 is connected to a fuel hose 88 extending from the fuel tank 80, and the other end is disposed in the engine room and connected to a connector 92. The connector 92 is connected to a second low-pressure fuel pipe 34 that flows fuel toward a low-pressure fuel rail 32 described later and a first low-pressure fuel pipe 94 that flows fuel toward a high-pressure fuel pump 50 described later.

  The internal combustion engine 10 distributes fuel to each high-pressure fuel injection device 40 as a high-pressure fuel system component for boosting the pressure of the fuel supplied from the first low-pressure fuel pipe 94 and supplying the fuel to the high-pressure fuel injection device 40. The high-pressure fuel rail 44 that is a distribution pipe, the high-pressure fuel pump 50 that pressurizes and pressurizes the low-pressure fuel from the first low-pressure fuel pipe 94, and the high-pressure fuel from the high-pressure fuel pump 50 flows to the high-pressure fuel rail 44. A high pressure fuel pipe 46 is provided.

  Each high-pressure fuel injection device 40 provided for each cylinder is connected to the high-pressure fuel rail 44. A pressure accumulating chamber 45 is formed inside the high pressure fuel rail 44, and the pressure accumulating chamber 45 communicates with the nozzle holes of each high pressure fuel injection device 40. A high pressure fuel pipe 46 is connected to the high pressure fuel rail 44, and a pressure accumulation chamber 45 of the high pressure fuel rail 44 and a fuel passage 47 formed in the high pressure fuel pipe 46 communicate with each other. The high-pressure fuel rail 44 distributes and supplies the high-pressure fuel from the high-pressure fuel pump 50 to each high-pressure fuel injection device 40.

  The high-pressure fuel pipe 46 has a fuel passage 47 through which fuel flows. One end of the high-pressure fuel pipe 46 is connected to a check valve 51 described later of the high-pressure fuel pump 50, and the other end is connected to the high-pressure fuel rail 44. The high-pressure fuel pipe 46 communicates the check valve 51 of the high-pressure fuel pump 50 and the pressure accumulation chamber 45 of the high-pressure fuel rail 44. The high pressure fuel pipe 46 allows the high pressure fuel boosted by the high pressure fuel pump 50 to flow to the high pressure fuel rail 44.

  The high-pressure fuel pump 50 has a cylinder hole 52 formed therein. A plunger 54 that reciprocates in the cylinder hole 52, a pump cam 56 that drives the plunger 54, and the plunger 54 on the pump cam 56 side. It is composed of a spring 58 or the like for biasing. The high-pressure fuel pump 50 is formed with a pressurizing chamber 60 that is partitioned by a cylinder hole 52 and a plunger 54 and pressurizes the fuel.

  In the high-pressure fuel pump 50, the pump cam 56 is coupled to a camshaft (not shown) that drives an intake valve or an exhaust valve, and this camshaft is connected to a crankshaft (not shown) of the internal combustion engine 10. Driven by the mechanical power of The pump cam 56 rotates at a speed proportional to the rotational speed of the crankshaft of the internal combustion engine 10.

  In the high-pressure fuel pump 50, the plunger 54 reciprocates along the axis of the cylinder hole 52 by the rotation of the pump cam 56. The high pressure fuel pump 50 increases or decreases the volume of the pressurizing chamber 60 by the reciprocating motion of the plunger 54. That is, the volume of the pressurizing chamber 60 changes at a frequency proportional to the rotational speed of the crankshaft (hereinafter referred to as engine rotational speed).

  The high-pressure fuel pump 50 is interposed between the fuel passage 95 and the pressurizing chamber 60 of the first low-pressure fuel pipe 94, and can be switched between communication and disconnection between the pressurizing chamber 60 and the fuel passage 95. A valve 64 is provided. The shut-off valve 64 is an electromagnetic on-off valve, and the valve body 64a is urged by the urging force of the spring 67 to open, and the valve body 64a is driven by the electromagnetic force generated by energization of the electromagnetic coil 66 to close the valve. To do. The energization period of the electromagnetic coil 66 is controlled by a control device (not shown). In this way, the high pressure fuel pump 50 switches between communication and disconnection between the low pressure fuel passage and the pressurizing chamber 60 by the opening / closing operation of the shutoff valve 64.

  Further, the high pressure fuel pump 50 is provided with a check valve 51 for preventing back flow of fuel. The check valve 51 opens when the fuel pressure in the pressurizing chamber 60 exceeds a predetermined valve opening pressure, and causes the fuel in the pressurizing chamber 60 to flow through the high-pressure fuel passage. The check valve 51 prevents the fuel pressure-fed from the pressurizing chamber 60 to the fuel passage 47 in the high-pressure fuel pipe 46 from flowing back into the pressurizing chamber 60 again.

  In the high-pressure fuel pump 50, when the pump cam 56 is rotationally driven by receiving mechanical power from the crankshaft of the internal combustion engine 10, the plunger 54 reciprocates in the cylinder hole 12 according to the rotation of the pump cam 56. To do. Thereby, the pressurizing chamber 60 changes its volume.

  The high-pressure fuel pump 50 opens the shut-off valve 64 to connect the fuel passage 95 and the pressurizing chamber 60 when the volume of the pressurizing chamber 60 is increased (hereinafter referred to as “volume increase”). Then, the fuel in the fuel passage 95 is sucked into the pressurizing chamber 60. On the other hand, the high-pressure fuel pump 50 closes the shut-off valve 64 and shuts off the low-pressure fuel passage and the pressurizing chamber 60 when the volume of the pressurizing chamber 60 is decreasing (hereinafter referred to as “volume reduction”). As a result, the fuel in the pressurizing chamber 60 can be increased to a pressure higher than the valve opening pressure of the check valve 51, and the fuel can be pumped from the check valve 51 to the high pressure fuel passage 47.

  The “high pressure fuel passage” means a fuel flow path through which high pressure fuel pressurized by the high pressure fuel pump 50 flows. In this embodiment, the high pressure fuel passage includes a pressure accumulation chamber 45 formed in the high pressure fuel rail 44 in addition to the fuel passage 47 in the high pressure fuel pipe 46.

  The internal combustion engine 10 is distributed and supplied to the low-pressure fuel injector 30 as a low-pressure fuel system component for supplying the fuel from the low-pressure fuel pump 82 to the low-pressure fuel injector 30 and the high-pressure fuel pump 50. A low-pressure fuel rail 32, a second low-pressure fuel pipe 34 for flowing fuel from the vehicle body fuel pipe 90 to the low-pressure fuel rail 32, and a first low-pressure fuel pipe 94 for flowing fuel from the vehicle body fuel pipe 90 to the high-pressure fuel pump 50 are provided. It has been.

  The first low-pressure fuel pipe 94 and the second low-pressure fuel pipe 34 are constituted by a resin fuel hose or the like, and fuel passages 95 and 35 are formed therein, respectively. One end of the first low-pressure fuel pipe 94 is connected to the end (connector 92) of the vehicle body fuel pipe 90 on the internal combustion engine 10 side, and the other end is connected to the upstream side of the shut-off valve 64 of the high-pressure fuel pump 50. . The first low-pressure fuel pipe 94 is provided with a pulsation damper 96 so that the fuel pressure pulsation in the fuel passage 95 can be attenuated.

  On the other hand, the second low-pressure fuel pipe 34 is constituted by a resin hose or the like, one end is connected to the end (connector 92) of the vehicle body fuel pipe 90 on the internal combustion engine 10 side, and the other end is a low-pressure fuel rail. 32 is connected to an inlet described later. The passage 35 of the second low-pressure fuel pipe 34 communicates with the passage 95 in the first low-pressure fuel pipe 94.

  The fuel pressure-fed by the low-pressure fuel pump 82 of the fuel tank 80 flows through the passage 91 in the vehicle body fuel pipe 90, and at the end (connector 92) of the vehicle body fuel pipe 90 on the internal combustion engine 10 side, The flow branches off into the passage 95 and the passage 35 of the second low-pressure fuel pipe 34. Thus, in the fuel supply device 1, the first low-pressure fuel pipe 94 supplies fuel to the high-pressure fuel pump 50, and the second low-pressure fuel pipe 34 supplies fuel to the low-pressure fuel rail 32.

  The low pressure fuel rail 32 is connected to a low pressure fuel injection device 30 provided for each cylinder. A pressure accumulating chamber 33 (described later) is formed inside the low pressure fuel rail 32. The pressure accumulating chamber 33 communicates with a nozzle hole (not shown) of the low pressure fuel injection device 30. The low-pressure fuel rail 32 distributes and supplies low-pressure fuel that has flowed from the low-pressure fuel pump 82 through the vehicle body fuel pipe 90 and the second low-pressure fuel pipe 34 to the low-pressure fuel injection devices 30.

  In addition, the pressure accumulation chamber 33 of the low-pressure fuel rail 32 is connected to the fuel passage 95 in the first low-pressure fuel pipe 94 via the fuel passage 35 in the second low-pressure fuel pipe 34, that is, the shutoff valve 64 of the high-pressure fuel pump 50. It communicates with the upstream fuel passage 95. That is, when the shutoff valve 64 is opened, the pressure accumulation chamber 33 of the low pressure fuel rail 32 is connected to the high pressure fuel pump 50 via the passage 35 in the second low pressure fuel pipe 34 and the passage 95 in the first low pressure fuel pipe 94. The pressure chamber 60 communicates. A characteristic configuration of the low-pressure fuel rail 32 according to the present embodiment will be described later.

  The “low pressure fuel passage” means a fuel flow path in which the fuel regulated by the pressure regulating valve 86 flows to the high pressure fuel pump 50 or the low pressure fuel injection device 30. In this embodiment, the low pressure fuel passage includes a fuel passage 91 in the vehicle body fuel pipe 90, a fuel passage 95 in the first low pressure fuel pipe 94, and a fuel passage 35 in the second low pressure fuel pipe 34, as well as a low pressure fuel. A pressure accumulating chamber 33 formed in the rail 32, a fuel port 37 of the first damper 36, a fuel port portion 106 of a second damper assembly (38, 100) described later, and the like are included.

  In the fuel supply apparatus 1 configured as described above, when the pumping amount of the high-pressure fuel pump 50 is adjusted by changing the valve closing period of the shutoff valve 64 when the volume of the pressurizing chamber 60 is decreased, the pressurizing chamber 60 is adjusted. Therefore, a back flow occurs in the passage 95 of the first low-pressure fuel pipe 94. Such a reverse flow is periodically generated at a frequency proportional to the engine speed of the internal combustion engine 10.

  If there is fuel that periodically flows back in the passage 95 in the first low-pressure fuel pipe 94, fuel pressure pulsation occurs in the passage 95. This fuel pressure pulsation propagates to the pressure accumulating chamber 33 in the low pressure fuel rail 32 via the passage 35 in the second low pressure fuel pipe 34. In this manner, fuel pressure pulsation (hereinafter referred to as high-pressure pump-induced pulsation) caused by the operation of the high-pressure fuel pump 50 occurs in the pressure accumulation chamber 33 of the low-pressure fuel rail 32. Further, in the pressure accumulation chamber 33 of the low-pressure fuel rail 32, fuel pressure pulsation (hereinafter referred to as fuel injection-induced pulsation) caused by the fuel injection of the low-pressure fuel injection device 30 also occurs. The high-pressure pump-induced pulsation has an extremely long cycle compared to the fuel injection-induced pulsation.

  When pulsations due to the high-pressure pump having a long cycle occur in the pressure accumulation chamber 33 of the low-pressure fuel rail 32 as described above, there is a possibility that the fuel injection amount injected by the low-pressure fuel injection device 30 between different cylinders may vary. Therefore, in the internal combustion engine according to the present embodiment, the fuel supply device 1 that supplies fuel to the low-pressure fuel injection device 30 attenuates not only the fuel injection-induced pulsation, but also the high-pressure pump-induced pulsation that differs greatly in frequency. Is required.

  Therefore, in the fuel supply apparatus according to the present embodiment, the low pressure fuel rail has a structure capable of attenuating the pulsation caused by the high pressure pump, and the detailed structure of the low pressure fuel rail will be described below with reference to FIG. FIG. 3 is a longitudinal sectional view of the low-pressure fuel rail.

  The low-pressure fuel rail 32 has a pressure accumulating chamber 33 formed therein, and an outer pipe 70 to which the low-pressure fuel injection device 30 is connected, and first and second pulsation dampers (hereinafter referred to as “attenuating the fuel pressure pulsation”). , Simply referred to as “first damper” and “second damper”) 36, 38, and the inner pipe 100 combined with the second damper 38 and accommodated in the pressure accumulating chamber 33 of the outer pipe 70.

  The outer pipe 70 is a metal pipe having a substantially cylindrical shape, and a pressure accumulating chamber 33 whose shape is defined by the peripheral wall 71 is formed. The pressure accumulating chamber 33 has a cylindrical shape extending in the longitudinal direction of the outer pipe 70 (indicated by an arrow A in the figure). On the peripheral wall 71 of the outer pipe 70, an outlet 72 for communicating the pressure accumulating chamber 33 and the low-pressure fuel injection device 30 is formed corresponding to the cylinder. The low pressure fuel rail 32 supplies the fuel in the pressure accumulating chamber 33 to the low pressure fuel injection device 30 through the outlet 72.

  A nipple 73 for connecting the second low-pressure fuel pipe 34 is provided at one end of the outer pipe 70, and an inflow port 74 is formed by being partitioned by the nipple 73. The inflow port 74 connects the pressure accumulation chamber 33 and the fuel passage 35 of the second low-pressure fuel pipe 34. Low-pressure fuel from the fuel passage 35 flows into the outer pipe 70 from the inlet 74.

  Of the end portion of the outer pipe 70, a volume chamber 76 is formed immediately downstream from the inflow port 74 in the fuel flow direction, that is, between the inflow port 74 and an upstream end portion 101 of the inner pipe 100 described later. . The volume chamber 76 changes the cross-sectional area of the fuel flow path, thereby generating fuel pressure pulsations that propagate between the passage 35 of the second low-pressure fuel pipe 34 and the pressure accumulating chamber 33 and the inner pipe 100, particularly high-frequency fuel pressure pulsations. It is possible to attenuate.

  In addition, the first and second dampers 36 and 38 are attached to the outer pipe 70. The first and second dampers 36 and 38 include a housing 36a, a diaphragm 36c that partitions the space in the housing 36a, a spring 36e that supports the diaphragm 36c with respect to the housing 36a, and the like. The housing 36a and the diaphragm 36c A fuel port 37 that is a space into which the fuel to be attenuated flows is formed. The dampers 36 and 38 can attenuate the fuel pressure pulsation by changing the volume of the fuel port 37 by changing the volume of the fuel port 37 by the expansion and contraction of the spring 36e according to the fuel pressure pulsation in the fuel port 37. .

  The fuel port 37 has a substantially cylindrical shape, and its axis is indicated by a one-dot chain line C in the figure. In the following description, a cylindrical wall portion surrounding the fuel port 37 in the housings 36a of the dampers 36 and 38 will be referred to as a “fuel port peripheral wall” and indicated by reference numerals 39 and 39c in the figure.

  A through-hole 77 for inserting the fuel port peripheral wall 39 of the first damper 36 is formed in the peripheral wall 71 of the outer pipe 70. A port peripheral wall receiving portion 78 having a cylindrical shape is formed at the end of the outer pipe 70 opposite to the side having the inflow port 74 in accordance with the shape of the fuel port peripheral wall 39.

  The frequency characteristic of the fuel pressure pulsation in which the pulsation damper mainly attenuates can be changed according to the shape of the fuel port. Specifically, as shown in FIG. 3, the ratio of the length L of the fuel port in the axial center C direction (hereinafter referred to as a port length) to the diameter D of the fuel port (hereinafter referred to as a port diameter) “ L / D ratio ". For example, the frequency characteristic of the fuel pressure pulsation in which the first damper 36 mainly attenuates is defined by the L / D ratio that is the ratio of the port length L of the fuel port 37 and the port diameter D. When the L / D ratio of the fuel port is set large, the frequency of the fuel pressure pulsation that the damper can mainly attenuate becomes small. Conversely, when the L / D ratio is set small, the frequency of the fuel pressure pulsation that the damper can mainly attenuate is large. Tend to be. In the present embodiment, the first damper 36 and the second damper 38 include the same characteristics such as the characteristics of the spring 36e and the diaphragm 36c, including the dimensions of the fuel port 37.

  The first damper 36 is fixed to the outer pipe 70 by inserting the fuel port peripheral wall 39 into a through hole 77 formed in the peripheral wall 71 of the outer pipe 70. Thus, the fuel port 37 of the first damper 36 communicates with the pressure accumulation chamber 33 of the outer pipe 70. The first damper 36 is set with characteristics such as the L / D ratio of the fuel port 37 so that fuel injection-induced pulsations caused by the fuel injection of the low-pressure fuel injection device 30 can be attenuated. Thereby, the first damper 36 can attenuate the fuel injection-induced pulsation in the pressure accumulation chamber 33.

  On the other hand, the second damper 38 is coupled by inserting the peripheral wall 102 of the inner pipe 100 into the fuel port peripheral wall 39c. The inner pipe 100 is a tubular member having a space inside and is a cylindrical member. In the inner pipe 100, a plurality of communication holes 104 that communicate the inner pipe 100 and the pressure accumulating chamber 33 are arranged in the circumferential direction of the inner pipe 100 on the downstream side of the upstream end portion 101 in the fuel flow direction. Yes. On the other hand, the downstream end portion 103 of the inner pipe 100 is inserted into the fuel port peripheral wall 39 c of the second damper 38. Thus, the 2nd damper 38 and the inner pipe 100 are couple | bonded, and the 2nd damper assembly (38,100) based on a present Example is comprised.

  In the second damper assembly (38, 100) configured as described above, the space 106 in the inner pipe 100 is a space into which fuel to be attenuated flows, that is, a space corresponding to a fuel port in the pulsation damper. Fuel port part ". The fuel port portion 106 of the second damper assembly (38, 100) has a larger port length L and a smaller port diameter D than the fuel port 37 of the first damper 36, and the above-mentioned L / D ratio. Is a big one.

  The inner pipe 100 constituting the second damper assembly (38, 100) is inserted into and coupled to a pipe receiving portion provided in the pressure accumulating chamber 33 formed in the outer pipe 70. Specifically, a cylindrical spacer 110 is inserted into the pressure accumulating chamber 33 of the outer pipe 70 adjacent to the volume chamber 76, and the inner pipe 100 is fixed in the vicinity of the volume chamber 76 of the outer pipe 70. The outer diameter of the spacer 110 is set to be substantially the same as the inner diameter of the pressure accumulating chamber 33, and the inner diameter of the hole 111 of the spacer 110 is set to be substantially the same as the outer diameter of the inner pipe 100.

  The second damper assembly (38, 100) is joined by inserting the upstream end 101, which is the end of the inner pipe 100 having the communication hole 104, into the hole 111 of the spacer 110 as a pipe receiving portion. The The communication hole 104 of the inner pipe 100 is arranged so as not to cover the hole 111 of the spacer 110 when the end of the inner pipe 100 is inserted into the hole 111 of the spacer 110.

  Further, a port peripheral wall receiving portion 78 is formed in the outer pipe 70 in accordance with the fuel port peripheral wall 39c. The second damper 38 of the second damper assembly (38, 100) is coupled to the outer pipe 70 by inserting the fuel port peripheral wall 39c into the port peripheral wall receiving portion 78.

  In the low-pressure fuel rail 32 manufactured in this way, the entire inner pipe 100 of the second damper assembly (38, 100) is accommodated in the pressure accumulating chamber 33 of the outer pipe 70, and the second damper 38 is located downstream of the outer pipe 70. It is provided at the end 70c. Thereby, the port length L of the fuel port portion 106 of the second damper assembly (38, 100) is made as close as possible to the length of the outer pipe 70 in the longitudinal direction (indicated by an arrow A in the drawing). Further, in the low-pressure fuel rail 32, a portion other than the port peripheral wall 39 c of the second damper 38 protrudes from the downstream end 70 c of the outer pipe 70 in the longitudinal direction A.

  The low pressure fuel rail 32 includes a port peripheral wall 39c of the second damper 38, which is both ends of the second damper assembly (38, 100), and an upstream end 101 of the inner pipe 100, respectively. 78 and the hole 111 of the spacer 110. As a result, the rigidity of the low-pressure fuel rail 32 is increased, and the second damper assembly (38, 100) is prevented from resonating with the vibration of the internal combustion engine 10.

  Further, in the low pressure fuel rail 32, the port peripheral wall receiving portion 78 of the outer pipe 70 and the hole 111 (pipe receiving portion) of the spacer 110 hold the inner pipe 100 at a predetermined interval from the inner wall 33 a of the pressure accumulating chamber 33. . As a result, the fuel flow in the pressure accumulating chamber 33 is improved, and the peripheral wall 102 of the inner pipe 100 and the peripheral wall 71 of the outer pipe 70 are prevented from contacting each other. Thereby, contamination (contaminants) such as metal powder is prevented in the pressure accumulation chamber 33 of the low pressure fuel rail 32 due to vibration of the internal combustion engine 10 to which the low pressure fuel rail 32 is mounted.

  The low-pressure fuel rail 32 configured as described above causes the fuel pressure pulsation propagating between the inflow port 74 and the fuel port portion 106 to change the flow passage cross-sectional area at the entrance and exit of the volume chamber 76 and the volume of fuel in the volume chamber 76. It can be attenuated by elasticity. The low-pressure fuel rail 32 attenuates the low-frequency high-pressure pump pulsation among the fuel pressure pulsations propagating from the volume chamber 76 toward the pressure accumulating chamber 33 by the fuel port portion 106 of the second damper assembly (38, 100). can do. In addition, the low-pressure fuel rail 32 can attenuate the fuel pressure pulsation propagating between the fuel port portion 106 and the pressure accumulating chamber 33 due to the change in the cross-sectional area of the communication hole 104. As described above, the low-pressure fuel rail 32 can attenuate the pulsation caused by the high-pressure pump that propagates through the low-pressure fuel passage from the inflow port 74 toward the pressure accumulating chamber 33.

  In the fuel supply device 1 configured as described above, the high-pressure pump-induced pulsation generated in the passage 95 a of the first low-pressure fuel pipe 94 due to the operation of the high-pressure fuel pump 50 is the fuel passage in the first low-pressure fuel pipe 94. 95, through the connector 92, the passage 35 of the second low-pressure fuel pipe 34, the volume chamber 76 in the low-pressure fuel rail 32, the fuel port portion 106 of the inner pipe 100, and the communication hole 104 of the inner pipe peripheral wall 102, It propagates through the low pressure fuel passage to the pressure accumulating chamber 33 for supplying fuel to the fuel injection device 30. Thus, in the low-pressure fuel passage from the upstream passage 95a of the high-pressure fuel pump 50 to the pressure accumulating chamber 33, the high-pressure pump-induced pulsation is attenuated to some extent by the cross-sectional change of the flow path through which the fuel flows and the volume elasticity of the fuel. Then, it propagates from the inlet 74 to the low pressure fuel passage in the low pressure fuel rail 32.

  In the low-pressure fuel rail 32, fuel injection-induced pulsation due to fuel injection of the low-pressure fuel device 30 propagates from the outlet 72 to the pressure accumulation chamber 33. The fuel injection-induced pulsation in the pressure accumulating chamber 33 is attenuated mainly by the first damper 36. On the other hand, the pulsation caused by the high pressure pump that is caused by the operation of the high pressure fuel pump 50 and propagates from the inlet 74 to the pressure accumulating chamber 33 through the fuel port portion 106 is mainly attenuated by the second damper assembly (38, 100). Is done. In this manner, in the fuel supply device 1, the fuel injection amount injected by the low-pressure fuel injection device 30 is prevented from being deviated from a predetermined value and the fuel injection amount varies between different cylinders. The

  As described above, the low pressure fuel rail 32 according to the present embodiment has the pressure accumulation chamber 33 provided therein, the outer pipe 70 capable of supplying the fuel in the pressure accumulation chamber 33 to the low pressure fuel injection device 30, and the pressure accumulation chamber 33. The first damper 36 is connected to the fuel port 37 so that the fuel pressure pulsation can be attenuated, and the inner pipe 100 disposed in the outer pipe 70 and having one end 101 communicating with the pressure accumulating chamber 33 is connected to the first damper. The fuel port portion 106 having a larger L / D ratio than the 36 fuel ports 37 is configured to include the second damper assembly (38, 100) that can attenuate the fuel pressure pulsation.

  Accordingly, the second damper assembly (38, 100) having the fuel port portion 106 having the L / D ratio larger than that of the fuel port 37 of the first damper 36 while the first damper 36 attenuates the pulsation caused by the fuel injection. The pulsation caused by the high-pressure pump having a lower frequency than that caused by the fuel injection can be attenuated. Since the inner pipe 100 of the second damper assembly (38, 100) is disposed in the outer pipe 70, a fuel rail capable of attenuating both injection-induced pulsation and high-pressure pump-induced pulsation with a compact configuration can be realized. .

  In the low-pressure fuel rail 32 according to the present embodiment, the second damper assembly (38, 100) includes an inner pipe 100 and a second damper having the same size fuel port as the first damper. The pipe 100 has one end 103 (downstream end) inserted into the fuel port peripheral wall 39c of the second damper 38 and the other end 101 (upstream end) provided in the outer pipe 70. It is assumed that it is inserted into the receiving part (the hole 111 of the spacer 110), and the space in the inner pipe 100 becomes the fuel port part 106 of the second damper assembly (38, 100).

  Accordingly, the first damper 36 and the second damper 38 have the same size fuel port so that the parts can be shared, and the inner pipe 100 is inserted into the fuel port peripheral wall 39c of the second damper 38. Thus, the second damper assembly (38, 100) having the fuel port portion 106 having a large L / D ratio can be realized.

  In the low-pressure fuel rail 32 according to the present embodiment, the fuel port peripheral wall 39c of the second damper 38 is disposed at the end of the outer pipe 70 opposite to the side where the pipe receiving portion (the hole 111 of the spacer 110) is formed. A port peripheral wall receiving portion 78 into which the inner pipe 100 can be inserted, the fuel port peripheral wall 39c of the second damper 38 is inserted into the port peripheral wall receiving portion 78, and the inner pipe 100 is accommodated in the pressure accumulating chamber 33. It was.

  Since the entire inner pipe 100 is accommodated in the pressure accumulating chamber 33 of the outer pipe 70, a portion other than the port peripheral wall 39c of the second damper 38 protrudes from the end of the outer pipe 70 while ensuring the port length L of the fuel port portion 106 as much as possible. The port peripheral wall 39c of the second damper 38 of the second damper assembly (38, 100) and the upstream end 101 of the inner pipe are held by the outer pipe 70. The rigidity of the low-pressure fuel rail can be increased to make it difficult to resonate with the vibration of the internal combustion engine 10.

  In the low pressure fuel rail 32 according to the present embodiment, the inner pipe 100 is provided with communication holes 104 arranged in the circumferential direction of the inner pipe 100 so as to communicate the space in the inner pipe 100 and the pressure accumulating chamber 33. It was supposed to be. Providing the communication hole 104 in this manner allows propagation between the fuel port portion 106 and the pressure accumulation chamber 33 while ensuring a cross-sectional area of the flow path between the fuel port portion 106 and the pressure accumulation chamber 33 in the inner pipe 100. The pulsating fuel pressure pulsation can be attenuated by the change in the cross-sectional area of the flow path in the communication hole 104.

  Further, in the low pressure fuel rail 32 according to the present embodiment, the pipe receiving portion 78 of the outer pipe 70 is provided by being inserted into the pressure accumulating chamber 33 to hold the inner pipe 100 at a predetermined interval from the inner wall of the pressure accumulating chamber 33. The cylindrical spacer 110 is used. After the pressure accumulating chamber 33 is formed in the outer pipe 70, the above-described pipe receiving portion can be easily realized simply by inserting the spacer 110 and fixing it to the inner wall 33a of the pressure accumulating chamber 33.

  In the low-pressure fuel rail 32 according to the present embodiment, the cross section of the flow path of the fuel flowing from the inlet 74 into the inner pipe 100 between the inlet 74 and the inner pipe 100 into which the fuel flows in the outer pipe 70. Therefore, the fuel pressure pulsation propagating between the inflow port 74 and the fuel port portion 106 is attenuated by the change in the cross-sectional area of the flow passage in the volume chamber 76 and the volume elasticity of the fuel. can do.

  Further, in the fuel supply apparatus 1 according to the present embodiment, the fuel pipe closer to the internal combustion engine 10 than the vehicle body fuel pipe 90 is connected to the first low-pressure fuel pipe 94 that flows the fuel toward the high-pressure fuel pump 50 and the low-pressure fuel rail 32. It was assumed to be branched to a second low-pressure fuel pipe 34 through which fuel flows. Thus, the length of the fuel pipe from the high-pressure fuel pump 50 to the low-pressure fuel rail 32 can be made as long as possible while leaving the vehicle body fuel pipe 90 as it is, and the accumulator 33 of the low-pressure fuel rail 32 from the high-pressure fuel pump 50. The high pressure pump-induced pulsation propagating to the inside of the first low-pressure fuel pipe 94 and the second low-pressure fuel pipe 34 are damped by the change in the flow path cross-section and the bulk elasticity of the fuel. be able to.

  The low-pressure fuel rail according to the present embodiment will be described with reference to FIG. FIG. 4 is a longitudinal sectional view of the low-pressure fuel rail. In the low-pressure fuel rail according to this embodiment, a part of the inner pipe is provided outside the outer pipe, and the port length of the fuel port portion is set longer than the length in the longitudinal direction of the pressure accumulating chamber. Unlike the first embodiment, the details will be described below. In addition, about the structure which is common in Example 1, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  In the low-pressure fuel rail 32B according to the present embodiment, a part of the inner pipe 100B is provided outside the outer pipe 70B. Specifically, the downstream end portion 103 of the inner pipe 100B and the winding portion 120 provided on the upstream side of the downstream end portion 103 are disposed outside the peripheral wall 71 of the outer pipe 70B, that is, the pressure accumulating chamber 33 with respect to the peripheral wall 71. It is provided on the side that does not have. The “upstream side” means the upstream side in the fuel flow direction, and is the side where the inflow port 74 in the direction along the longitudinal direction A of the outer pipe 70B is provided. In the inner pipe 100B, the side where the communication hole 104 is provided is meant.

  The downstream end 103 of the inner pipe 100B is inserted into the fuel port peripheral wall 39c of the second damper 38 and coupled. Thus, the second damper assembly (38, 100B) according to the present embodiment is configured. A space in the peripheral wall 102B of the inner pipe 100B serves as a fuel port portion 106B. The second damper 38 is provided on the outer side of the outer pipe 70 </ b> B, that is, on the side having no pressure accumulation chamber 33 </ b> B with respect to the peripheral wall 71. In addition, the second damper 38 is provided on the same side as the first damper 36 with respect to the peripheral wall 71 of the outer pipe 70B.

  The winding portion 120 is a portion of the inner pipe 100B that is wound in a spiral shape with the longitudinal direction A of the outer pipe 70B as an axis. By forming the winding part 120 in the inner pipe 100B, the port length L of the fuel port part 106 in the inner pipe 100B is made longer than when the winding part 120 is not formed, that is, a straight pipe is used. be able to.

  The winding portion 120 is provided on the upstream side of the downstream end portion 103 and is provided on the outer side of the outer pipe 70B, that is, on the side having no pressure accumulation chamber 33B with respect to the peripheral wall 71. In addition, the winding part 120 is provided on the same side as the side where the first damper 36 and the second damper 38 are installed with respect to the peripheral wall 71 of the outer pipe 70B.

  In the inner pipe 100B, on the upstream side of the winding part 120, there is a crank part 115 which is a bent pipe having two bends in order to move the pipe line from the outside of the peripheral wall 71 of the outer pipe 70B to the inside, that is, into the pressure accumulating chamber 33B. Is provided. The outer pipe 70B is provided with a through hole 71c, and the crank portion 115 is moved through the through hole 71c to the pressure accumulating chamber 33B. The upstream side of the crank portion 115 is a straight pipe extending along the inner wall 33 a of the pressure accumulating chamber 33.

  The downstream end portion 103 of the inner pipe 100B is inserted and coupled into the fuel port peripheral wall 39c of the second damper 38, whereby the second damper assembly (38, 100B) according to the present embodiment is configured. . The inner pipe 100B of the second damper assembly (38, 100B) is coupled to the outer pipe 70B by inserting the upstream end 101 into the hole 111 of the spacer 110 constituting the pipe receiving portion. On the other hand, in the second damper 38 of the second damper assembly (38, 100B), the fuel port peripheral wall 39c is coupled to the peripheral wall 71 of the outer pipe 70B by a bracket 130 or the like.

  Since the second damper assembly (38, 100B) has the winding part 120, the fuel port 106B is longer than the length in the longitudinal direction A of the pressure accumulating chamber 33B. Even if the inner pipe 100B is configured by replacing the winding portion 120 with a straight pipe, since the crank portion 115 is provided, the port length L of the fuel port 106B is equal to the pressure accumulation chamber 33B. The length in the longitudinal direction A is longer. That is, if a part of the inner pipe 100B is provided outside the outer pipe 70B, the fuel port length is longer than when the entire inner pipe is accommodated in the pressure accumulating chamber 33B of the outer pipe 70B.

  The low-pressure fuel rail 32 </ b> B configured as described above attenuates the fuel injection-induced pulsation generated in the pressure accumulation chamber 33 </ b> B by the fuel injection of the low-pressure fuel injection device 30 by the first damper 36, and from the inlet 74 to the pressure accumulation chamber 33. Among the fuel pressure pulsations propagating in the direction, the pulsations caused by the high-pressure pump having a particularly low frequency can be attenuated by the fuel port portion 106B of the second damper assembly (38, 100B) having a large L / D ratio.

  As described above, in the low-pressure fuel rail 32B according to the present embodiment, a part of the inner pipe 100B is provided outside the outer pipe 70B, and the port length of the fuel port portion 106B is the longitudinal direction A of the pressure accumulating chamber 33B. Therefore, the port length of the fuel port portion 106B may be longer than that of the low pressure fuel rail in which the entire inner pipe is accommodated in the pressure accumulation chamber of the outer pipe. The second damper assembly (30, 100B) having a large L / D ratio can be realized. Even when the frequency of the pulsation caused by the high pressure pump propagating from the inlet 74 to the pressure accumulating chamber 33B of the low pressure fuel rail 32B is extremely low, the second damper assembly (38, 100B) is accumulating in the low pressure fuel rail 32B. The high-pressure pump-induced pulsation propagating to the chamber 33B can be attenuated satisfactorily.

  Further, in the low pressure fuel rail 32B according to the present embodiment, since a part of the inner pipe 100B is provided outside the outer pipe 70B, the volume of the pressure accumulating chamber 33B can be secured to that extent. Thereby, the low pressure fuel rail 32B can reduce the fuel pressure fluctuation generated in the pressure accumulating chamber 33B by the fuel injection of the low pressure fuel injection device 30 as compared with the case where the entire inner pipe is accommodated in the pressure accumulating chamber.

  Further, in the low pressure fuel rail 32B according to the present embodiment, the first damper 36, the second damper 38, and the winding portion 120 are linearly arranged on the same side with respect to the peripheral wall 71 of the outer pipe 70B. A low pressure fuel rail including the second damper assembly (38, 100B) having a large L / D ratio can be realized without impairing the mountability of the low pressure fuel rail to the internal combustion engine.

  In each of the above-described embodiments, the second damper assembly is configured by inserting the end portion 103 of the inner pipe (100; 100B) into the fuel port peripheral wall 39c of the second damper 38. The method of joining the second damper 38 and the inner pipe (100; 100B) is not limited to this. For example, the end surface of the inner pipe may be coupled to the end surface of the fuel port peripheral wall 39c of the second damper 38 by brazing or the like.

  As described above, the low-pressure fuel rail and the fuel supply device according to this embodiment include the low-pressure fuel injection device that injects the fuel from the low-pressure fuel passage into the intake passage, and the high-pressure that injects the fuel from the high-pressure fuel passage into the cylinder. This is useful for an internal combustion engine including a fuel injection device and a high-pressure fuel pump capable of sucking fuel from a low-pressure fuel passage and boosting the pressure to the high-pressure fuel passage. In particular, the volume is periodically increased according to the operating state of the internal combustion engine. Is useful for an internal combustion engine having a high pressure fuel pump having a pressurizing chamber in which the pressure changes, and a shutoff valve capable of switching communication and shutoff between the low pressure fuel passage and the pressurizing chamber by an opening / closing operation.

1 is a cross-sectional view illustrating a schematic configuration around a cylinder of an internal combustion engine according to a first embodiment. 1 is a schematic diagram illustrating a schematic configuration of a fuel supply device including an internal combustion engine according to a first embodiment. 1 is a longitudinal sectional view of a low pressure fuel rail according to Embodiment 1. FIG. It is a longitudinal cross-sectional view of the low-pressure fuel rail which concerns on Example 2. FIG. It is a figure which shows an example of the fuel pressure pulsation in a low-pressure fuel path when the fuel injection-induced pulsation and the high-pressure pump-induced pulsation occur simultaneously.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 30 Low pressure fuel injection apparatus 32, 32B Low pressure fuel rail (fuel rail)
33, 33B Accumulation chamber 34 Second low-pressure fuel pipe 36 First pulsation damper (first damper)
38 Second pulsation damper (second damper)
39, 39c Fuel port peripheral wall 40 High-pressure fuel injection device 44 High-pressure fuel rail 50 High-pressure fuel pump 64 Shut-off valve 70, 70B Outer pipe 71 Outer pipe peripheral wall 72 Outlet 74 Inlet 76 Volume chamber 80 Fuel tank 90 Body fuel piping 94 First low-pressure fuel Piping 100, 100B Inner pipe 101 Upstream end (one end)
102 peripheral wall 103 downstream side end 104 communication hole 106, 106B fuel port part 110 spacer 115 crank part 120 winding part

Claims (8)

A low-pressure fuel injection device that injects fuel from the low-pressure fuel passage into the intake passage; a high-pressure fuel injection device that injects fuel from the high-pressure fuel passage into the cylinder; and a high-pressure fuel passage that sucks and boosts fuel from the low-pressure fuel passage. A fuel rail that is used in an internal combustion engine that includes a high-pressure fuel pump that can be pumped to a low-pressure fuel injection device,
An outer pipe that is provided with an accumulator chamber and is capable of supplying fuel in the accumulator chamber to the low-pressure fuel injection device;
A first damper capable of attenuating fuel pressure pulsation by connecting a fuel port to the pressure accumulating chamber;
By connecting an inner pipe disposed in the outer pipe and having one end communicating with the pressure accumulating chamber, a fuel port portion having a larger L / D ratio than that of the fuel port of the first damper is formed to attenuate fuel pressure pulsation. A possible second damper assembly;
A fuel rail comprising: The fuel rail according to claim 1,
The second damper assembly includes an inner pipe and a second damper having a fuel port having the same dimensions as the first damper.
The inner pipe has one end inserted into the fuel port peripheral wall of the second damper and the other end inserted into a pipe receiving portion provided in the outer pipe.
A fuel rail, wherein a space in an inner pipe serves as a fuel port portion of a second damper assembly. The fuel rail according to claim 2,
A port peripheral wall receiving portion into which the fuel port peripheral wall of the second damper can be inserted is formed at the end of the outer pipe opposite to the pipe receiving portion.
A fuel rail, wherein a fuel port peripheral wall of a second damper is inserted into a port peripheral wall receiving portion, and the entire inner pipe is accommodated in a pressure accumulating chamber. A fuel rail according to claim 1 or 2,
A fuel rail characterized in that a part of the inner pipe is provided outside the outer pipe, and the port length of the fuel port portion is set longer than the length in the longitudinal direction of the pressure accumulating chamber. The fuel rail according to any one of claims 2 to 4, wherein
A fuel rail, wherein the inner pipe has communication holes arranged in the circumferential direction of the inner pipe. The fuel rail according to any one of claims 2 to 5,
A fuel rail, wherein the pipe receiving portion of the outer pipe is a cylindrical spacer provided in the pressure accumulation chamber and holding the inner pipe at a predetermined interval from the inner wall of the pressure accumulation chamber. The fuel rail according to any one of claims 1 to 6,
A fuel rail, wherein a volume chamber for changing a flow path cross section of the fuel flowing from the inlet to the inner pipe is formed between the inlet and the inner pipe into which the fuel flows in the outer pipe. A fuel supply device comprising the fuel rail according to any one of claims 1 to 7,
An internal combustion engine is mounted on a car as a prime mover,
The automobile is provided with a vehicle body fuel pipe for flowing fuel from the fuel tank toward the internal combustion engine,
The fuel pipe on the internal combustion engine side from the vehicle body fuel pipe is branched into a first low-pressure fuel pipe that flows fuel toward the high-pressure fuel pump and a second low-pressure fuel pipe that flows fuel toward the low-pressure fuel rail; Fuel supply device.

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