JP2011127558A - Fuel supply system of internal combustion engine and internal combustion engine having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel supply system of an internal combustion engine capable of stabilizing a flow rate of fuel injected into a combustion chamber from a fuel injection device, and the internal combustion engine having the same. <P>SOLUTION: A damping device 15 for damping pulsation of the fuel is arranged in a common rail 4. A part constituted of a mesh part 15b and a support part 15c of its outer periphery is supported in a housing 15a of the damping device 15 in a state of being movable in the Z axis direction (both lateral directions) for making the fuel flow by a spring 15d connected to both surfaces crossing with its thickness direction. Thus, since propagation of the pulsation in the common rail 4 can be restrained, the flow rate of the fuel injected into the combustion chamber from an injector 5 can be stabilized. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fuel supply system for an internal combustion engine and an internal combustion engine including the same, and more specifically, a fuel supply system for an internal combustion engine capable of stabilizing the flow rate of fuel injected from a fuel injection device into a combustion chamber, and The present invention relates to an internal combustion engine including the same.

  In a common rail fuel supply system for a diesel engine, fuel accumulated in the common rail is injected into each cylinder through an injector at a timing controlled by the rotational speed of the engine.

  In this common rail type fuel supply system, since the fuel in the fuel injection flow path up to the high pressure pump, common rail and injector is in a high pressure state, the fuel generated in the injector during fuel injection in the fuel injection flow path As a result of this pressure pulsation being transmitted, there is a problem that the amount of fuel injected by the injector fluctuates and a minute flow rate cannot be injected in a stable state.

  In order to cope with such pressure pulsation, a configuration is disclosed in which damping means for attenuating the pressure pulsation of fuel is provided in the common rail (see, for example, Patent Documents 1 and 2).

  Patent Document 1 discloses a configuration in which a common rail has a double cylindrical structure, and an inner pressure accumulation chamber and an outer pressure accumulation chamber are connected via an orifice (attenuating means).

  In Patent Document 2, an accumulator (attenuating means) having a large diameter portion and a small diameter portion is provided in the internal fuel passage of the common rail, and an orifice is provided at a portion connecting the communication passage connected to the injector and the small diameter portion in the common rail. A configuration in which (attenuating means) is provided is disclosed.

JP-A-6-346818 JP 2007-0771152 A

  An object of the present invention is to provide a fuel supply system for an internal combustion engine that can stabilize the flow rate of fuel injected from a fuel injection device into a combustion chamber, and an internal combustion engine including the same.

  In order to achieve the above object, a fuel supply system for an internal combustion engine according to the present invention is a fuel supply system for an internal combustion engine that includes a common rail that accumulates pressure supplied from a fuel supply source and supplies the fuel to a plurality of fuel injection devices. The common rail includes a damping device for damping fuel pulsation, and the damping device includes a mesh portion disposed so as to intersect a direction in which the fuel flows, and the mesh portion. It is provided in a connected state, and includes a support portion having a preset mass, and an elastic member that supports the mesh portion and the support portion in a state in which the mesh portion and the support portion are movable in the fuel flow direction.

  In the fuel supply system for an internal combustion engine, the damping device is disposed so as to delimit each of the plurality of fuel outlets to which each of the plurality of fuel injection devices is connected in the common rail. Thereby, the pressure pulsation which arises by interaction between each fuel-injection apparatus can also be suppressed effectively. For this reason, fuel pulsation can be more efficiently suppressed.

  In the fuel supply system for an internal combustion engine, the support portion is supported in a state of being sandwiched between the elastic members disposed on both sides intersecting the thickness direction. That is, since the mesh portion and the support portion can be supported in a state where the mesh portion and the support portion can be moved in both directions in the thickness direction, pulsation propagating from the fuel injection device to the fuel supply source side through the common rail can be attenuated, and from the fuel supply source The pulsation propagating to the fuel injection device through the common rail can also be attenuated. For this reason, fuel pulsation can be more efficiently suppressed.

  In the fuel supply system for an internal combustion engine, the fuel is liquefied gas fuel.

  In order to achieve the above object, an internal combustion engine of the present invention includes the fuel supply system.

  According to the fuel supply system for an internal combustion engine and the internal combustion engine including the same according to the present invention, the pressure pulsation propagating in the common rail can be suppressed by providing the damping device for damping the fuel pulsation in the common rail. As a result, the flow rate of the fuel injected from the fuel injection device of the fuel supply system into the combustion chamber can be stabilized.

1 is a configuration diagram of a fuel supply system for an internal combustion engine according to an embodiment of the present invention. It is a top view of the fuel distribution surface of the damping device in the common rail of the fuel supply system of FIG. It is sectional drawing of the AA line of FIG. It is sectional drawing of an example along the longitudinal direction of the common rail of the fuel supply system of FIG. It is sectional drawing of the other example along the longitudinal direction of the common rail of the fuel supply system of FIG.

  Hereinafter, an internal combustion engine according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows the configuration of a fuel supply system for an internal combustion engine according to an embodiment of the present invention. In addition, the solid line arrow in FIG. 1 indicates the flow of fuel. A broken line indicates a signal wiring, and a broken arrow indicates a flow of an electric signal.

  The internal combustion engine of the present embodiment is configured as an in-line four-cylinder common rail type diesel engine 1 mounted on an automobile such as a truck, for example. In addition, this invention is not limited to a diesel engine, It can also apply to a gasoline engine etc.

  A fuel supply system of a diesel engine (hereinafter referred to as an engine) 1 includes a fuel such as light oil stored in a fuel tank (fuel supply source) 2, a supply pump (fuel supply source, high-pressure pump) 3, and a common rail 4. And it has the structure which passes each injector (fuel-injection apparatus) 5 in order, and supplies it to the combustion chamber of each cylinder (not shown) of the engine 1.

  The fuel tank 2 is connected to the supply pump 3 via the fuel filter 8. The fuel tank 2 accommodates a low-pressure pump (not shown), and the fuel in the fuel tank 2 is pressurized by the low-pressure pump and then pumped to the supply pump 3 via the fuel filter 8.

  The supply pump 3 is a pump that increases the pressure to a level suitable for injecting fuel into the combustion chamber, and is driven in accordance with the reciprocating motion of the piston of each cylinder (not shown) of the engine 1. The supply pump 3 is connected to the common rail 4, and the fuel pumped to the supply pump 3 is pressurized to several tens of MPa to 200 MPa and then pumped to the common rail 4.

  The common rail 4 is a container for accumulating fuel to be injected. A pressure sensor (not shown) for detecting the fuel pressure is installed inside the common rail 4. The pressure sensor is electrically connected to an electronic control unit (Engine Control Unite; hereinafter abbreviated as ECU) 9, and a signal detected by the pressure sensor is input to the ECU 9.

  The pressure and flow rate of the fuel in the common rail 4 is controlled by an ECU 9 that controls a solenoid valve (not shown) of the supply pump 3 based on information from the pressure sensor in the common rail 4 and information on the engine speed and load sent from the sensors 10. By doing so, the optimum value is set according to the operating state of the engine 1. The sensors 10 are sensors that detect the operating state of the engine 1, and include, for example, a crank sensor, a cam sensor, an accelerator opening sensor, and a temperature sensor.

  The common rail 4 is connected to each injector 5 arranged in each cylinder, and the fuel supplied to and accumulated in the common rail 4 is evenly distributed to each injector 5, and from each injector 5 to each combustion chamber of each cylinder. Directly injected. The common rail 4 is connected to the fuel tank 2 via a pressure control valve (PCV) 11, and is configured to return excess fuel to the fuel tank 2.

  The injector 5 is a device that injects fuel supplied to the fuel inflow pipe of the injector 5 through the fuel tank 2, the supply pump 3, and the common rail 4 into the combustion chamber of the engine 1 through the injection hole of the injector 5.

  Each injector 5 is electrically connected to the ECU 9. The ECU 9 injects fuel into the combustion chamber of each cylinder with an appropriate injection amount and injection pressure during an appropriate fuel injection timing and fuel injection period in accordance with the operating state such as the rotational speed and load state of the engine 1. Thus, each injector 5 can be controlled. Each injector 5 is connected to the fuel tank 2 so that excess fuel can be returned to the fuel tank 2.

  By the way, in the fuel supply system of the engine 1 of the present embodiment, a damping device for damping fuel pulsation is installed in the common rail 4. An example of the attenuation device 15 is shown in FIGS. FIG. 2 is a plan view of a fuel flow surface (a surface orthogonal to the direction in which the fuel flows) of the damping device 15, and FIG. 3 is a cross-sectional view taken along the line AA in FIG.

  The damping device 15 includes a housing 15a, a mesh portion 15b, a support portion 15c, and a spring (elastic member) 15d. The mesh portion 15b is arranged so as to be orthogonal (cross) to the direction in which the fuel flows (Z-axis direction: left-right direction in FIG. 3). A support portion 15c is connected to the outer periphery of the mesh portion 15b.

  The support portion 15c has a preset mass. The support portion 15c is supported in a state of being sandwiched between springs 15d connected to both surfaces orthogonal to (crossing) the thickness direction (Z-axis direction). Thereby, the part comprised by the mesh part 15b and the support part 15c is supported in the state which can move to the Z-axis direction (left-right both directions of FIG. 4) with the spring 15d in the housing 15a. The spring coefficient of the spring 15d, the mass of the mesh portion 15b and the support portion 15c, and the roughness of the mesh portion 15b are set so as to efficiently suppress fuel pulsation.

  As described above, in the fuel supply system of the engine 1 according to the present embodiment, the pressure pulsation of the fuel propagating in the common rail 4 can be suppressed by providing the damping device 15 in the common rail 4. Even if the flow rate of fuel injected into the combustion chamber is very small, the injection flow rate can be stabilized.

  Further, since the fuel flow path of the damping device 15 is configured by the mesh portion 15b, for example, a large fuel pressure such as pulsation can be selectively dispersed and relaxed without disturbing the fuel supply itself.

  The damping device 15 has a simple structure using the mesh portion 15b, the support portion 15c, and the spring 15d, does not require difficult control, and is small and lightweight. For this reason, even when a plurality of damping devices 15 are provided in the common rail 4, a large-scale design change of the common rail 4 is not required, and an extreme weight increase does not occur.

  Next, FIG. 4 and FIG. 5 show arrangement examples of the attenuation device 15. 4 and 5 show cross-sectional views along the longitudinal direction of the common rail 4. The arrows in FIGS. 4 and 5 indicate the flow of fuel.

  4 shows a case where the fuel inlet 16 is provided on one end face in the longitudinal direction of the common rail 4, and FIG. 5 shows a case where the fuel inlet 16 is provided on both end faces in the longitudinal direction of the common rail 4. Yes. The fuel inlet 16 is connected to the fuel outlet of the supply pump 3 shown in FIG. 1 through a pipe (not shown).

  4 and 5, the common rail 4 is formed with a fuel flow path 17 extending in the longitudinal direction thereof, and a plurality of fuel outlets at predetermined intervals along the longitudinal direction of the fuel flow path 17. 18 is formed in communication with the fuel flow passage 17. Each fuel outlet 18 is connected to a fuel inlet of each injector 5 shown in FIG. 1 through a pipe (not shown).

  A damping device 15 is installed in the fuel flow path 17 of the common rail 4 so as to divide each of the plurality of fuel outlets 18. The outer periphery of the housing 15a of each damping device 15 is joined and fixed to the inner wall of the fuel flow path 17, but the mesh portion 15 and the support portion 15c of each damping device 15 are along the Z-axis direction in which the fuel flows by the spring 15d. It is possible to move.

  In addition, although the mesh part 15b, the support part 15c, and the spring 15d of each damping device 15 are the same, they do not necessarily need to be the same. The configuration conditions and materials of each damping device 15 may be changed according to the location of each damping device 15 so that the pressure pulsation is reduced. Thereby, pressure pulsation can be efficiently suppressed.

  By providing the damping device 15 in the common rail 4 as described above, it is possible to effectively suppress the pressure pulsation as compared with the case where only the orifice is installed as the means for damping the pressure pulsation. In particular, by arranging the damping device 15 so as to divide the fuel outlets 18, pressure pulsation caused by the interaction between the injectors 5 can be effectively suppressed. Further, since the mesh portion 15b and the support portion 15c can be supported in a state in which they can be moved in both directions in the thickness direction, pulsation propagating from the injector 5 to the supply pump 3 side through the common rail 4 can be attenuated, Pulsations propagating from the 3 side to the injector 5 side through the common rail 4 can also be attenuated. As a result, fuel pulsation can be more efficiently suppressed.

  In the above description, the case where the fuel is light oil has been described. However, the fuel is not limited to this and can be variously changed. For example, liquefied gas fuel such as propane or DME (Dimethly ether) is used. Also good.

  The fuel supply system for an internal combustion engine of the present invention and the internal combustion engine including the same can suppress pressure pulsation propagating in the common rail by including a damping device for damping fuel pulsation in the common rail. Since the flow rate of the fuel injected from the fuel injection device of the fuel supply system into the combustion chamber can be stabilized, it can be used for a fuel supply system such as an automobile and an internal combustion engine including the same.

1 Diesel engine (internal combustion engine)
2 Fuel tank (fuel supply source)
3 Supply pump (fuel supply source, high-pressure pump)
4 Common rail (fuel supply source)
5 Injector (fuel injection device)
9 Electronic control unit (control unit)
15 Damping device 15a Housing 15b Mesh portion 15c Support portion 15d Spring (elastic member)
16 Fuel inlet 17 Fuel passage 18 Fuel outlet

Claims (5)

A fuel supply system for an internal combustion engine comprising a common rail that accumulates fuel supplied under pressure from a fuel supply source and supplies the fuel to a plurality of fuel injection devices,
The common rail includes a damping device for damping fuel pulsation,
The damping device includes a mesh portion disposed so as to intersect a direction in which the fuel flows,
A support portion provided in a state of being connected to the mesh portion, and having a preset mass;
A fuel supply system for an internal combustion engine, comprising: an elastic member that supports the mesh portion and the support portion in a state where the mesh portion and the support portion are movable in a direction in which fuel flows.   2. The fuel supply system for an internal combustion engine according to claim 1, wherein the damping device is arranged so as to separate each of a plurality of fuel outlets to which each of the plurality of fuel injection devices is connected in the common rail.   The fuel supply system for an internal combustion engine according to claim 1 or 2, wherein the support portion is supported in a state of being sandwiched between the elastic members arranged on both sides intersecting the thickness direction thereof.   The fuel supply system for an internal combustion engine according to any one of claims 1 to 3, wherein the fuel is a liquefied gas fuel.   An internal combustion engine comprising the fuel supply system according to any one of claims 1 to 4.

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