JP2011157920A - Fuel supply system for internal combustion engine, and the internal combustion engine equipped therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel supply system for an internal combustion engine, enabling to stabilize the flow amount of fuel to be injected from a fuel injection device into a combustion chamber, and to provide the internal combustion engine equipped therewith. <P>SOLUTION: A dynamic damper 15 is installed in a fuel distribution pipe 4a of a common rail 4 for damping the pressure pulsation of fuel. In the fuel distribution pipe 4a of the common rail 4, a piston 15a of the dynamic damper 15 is installed movably along the longitudinal direction of the fuel distribution pipe 4a. The pressure pulsation of the fuel, when produced in an accumulator 4a1 of the common rail 4, gives resonation to the piston 15a of the dynamic damper 15 to absorb vibration energy. This suppresses the propagation of the pressure pulsation in the common rail 4 to stabilize the flow amount of the fuel to be injected from an injector 5 into the combustion chamber. <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 dynamic vibration absorber that attenuates the pressure pulsation of the fuel, and the dynamic vibration absorber is movable in the fuel distribution pipe of the common rail along the longitudinal direction of the fuel distribution pipe. A piston having a mass set in advance and a first chamber connected to the plurality of fuel injection devices in a fuel distribution pipe of the common rail, separated by the piston. It has two chambers and a spring portion formed by the fuel supplied to the second chamber.

  In the fuel supply system for an internal combustion engine, the first sensor provided in the first chamber for detecting the pressure of the fuel in the first chamber, and the fuel in the second chamber provided in the second chamber. A second sensor for detecting the pressure of the fuel, a first valve for controlling a flow rate of the fuel supplied to the second chamber, a second valve for controlling a flow rate of the fuel discharged from the second chamber, and the second valve 1. A control unit that adjusts the spring constant of the dynamic vibration absorber by controlling the pressure of fuel in the second chamber by controlling the first and second valves based on detection information from the second sensor. With.

  In the fuel supply system for an internal combustion engine, a damper for the movement of the piston is provided.

  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 dynamic pulsator for attenuating the pressure pulsation of the fuel is provided in the common rail, thereby suppressing the pressure pulsation propagating in the common rail. Therefore, 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 in an internal combustion engine according to an embodiment of the present invention. It is a block diagram of the fuel supply system in the internal combustion engine of other embodiment of this invention.

  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. The common rail 4 is connected to each injector 5 disposed in each cylinder, and the fuel supplied and accumulated in the common rail 4 is evenly distributed to each injector 5.

  The injector 5 is a device that injects fuel supplied from the common rail 4 into the combustion chamber of the engine 1 from the injection hole. Each injector 5 is electrically connected to an electronic control unit (Engine Control Unite; hereinafter abbreviated as ECU, control unit) 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 is controlled. Further, each injector 5 is connected to the fuel tank 2 through a return pipe 10, so that excess fuel in each injector 5 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 dynamic vibration absorber 15 that attenuates the pressure pulsation of the fuel is installed in the fuel flow pipe 4 a of the common rail 4.

  The dynamic vibration absorber 15 is separated by a piston 15a from a piston 15a having a preset mass and a fuel pressure accumulation chamber (first chamber, hereinafter simply referred to as pressure accumulation chamber) 4a1 in a fuel flow pipe 4a of the common rail 4. It has a pulsation damping chamber (second chamber, hereinafter simply referred to as a damping chamber) 4a2 and a spring portion formed by the elastic force of the fuel in the pulsation damping chamber 4a2.

  The piston 15a is installed in the fuel flow pipe 4a of the common rail 4 so as to be movable along the longitudinal direction (Z-axis direction) of the fuel flow pipe 4a. The fuel flow pipe 4a is divided into a pressure accumulating chamber 4a1 and a damping chamber 4a2 by a piston 15a.

  The above-described supply pump 3 is connected to the pressure accumulating chamber 4a1 and the damping chamber 4a2. The fuel is filled in the pressure accumulating chamber 4a1 and at the same time the fuel is filled in the damping chamber 4a2. Fuel supply from the supply pump 3 to the common rail 4 is performed in two systems. The first system is a path for supplying fuel from the fuel outlet of the supply pump 3 to the pressure accumulating chamber 4 a 2 through the fuel inlet 4 b of the common rail 4. That is, in the first system, the fuel supplied from the supply pump 3 is always pumped to the pressure accumulation chamber 4a1. On the other hand, in the second system, a path switching valve (first valve) 16 is interposed in the middle of the path, from which a fuel is supplied to the pressure accumulating chamber 4a1 through the fuel inlet 4c of the common rail 4, and a fuel inlet of the common rail 4 And a path for supplying fuel to the damping chamber 4a2 through 4d. That is, in the second system, the fuel supplied from the supply pump 3 is pumped to either the pressure accumulating chamber 4a1 or the damping chamber 4a2 by switching the path with the path switching valve 16. The path switching valve 16 is electrically connected to the ECU 9, and path switching is controlled by the ECU 9.

  The pressure accumulating chamber 4 a 1 is connected to the fuel inlet of each injector 5 through each of the plurality of fuel outlets 4 e of the common rail 4. Further, the pressure accumulating chamber 4a1 is connected to the return pipe 10 from the fuel outlet 4f via a first pressure control valve (PCV) 17a. On the other hand, the damping chamber 4a2 is connected to the return pipe 10 from the fuel outlet 4g via the second pressure regulating valve (PCV, second valve) 17b. As a result, it is possible to adjust the fuel pressure in the pressure accumulation chamber 4a1 and the decompression chamber 4a2. The pressure regulating valves 17a and 17b are electrically connected to the ECU 9, and the opening and closing of the valves is controlled by the ECU 9.

  Sensors (first sensor and second sensor) 18a and 18b are installed in the pressure accumulation chamber 4a1 and the attenuation chamber 4a2, respectively. The sensors 18a and 18b are sensors for detecting the pressure and / or temperature of the fuel in the pressure accumulation chamber 4a1 and the attenuation chamber 4a2, respectively. These sensors 18a and 18b are electrically connected to the ECU 9, and signals detected by the sensors 18a and 18b are input to the ECU 9.

  The ECU 9 controls the drive of the supply pump 3 based on the information from the sensor 18a in the common rail 4 and the information on the engine speed and the load sent from the sensors 19 for the pressure and supply amount of the fuel in the accumulator 4a1. Thus, the optimum value is set according to the operating state of the engine 1. The sensors 19 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.

  On the other hand, the pressure and supply amount of the fuel in the damping chamber 4a2 are set so that the spring constant of the spring portion of the dynamic vibration absorber 15 becomes an optimum value for suppressing the pressure pulsation propagating into the pressure accumulating chamber 4a1. ing.

  The spring constant of the spring portion of the dynamic vibration absorber 15 is determined by measuring the fuel pressure in the pressure accumulating chamber 4a1 and the damping chamber 4a2 based on detection signals from the sensors 18a and 18b, and the fuel filled in the damping chamber 4a2 and the piston 15a. The optimum value is obtained from the equation of motion of the spring-mass system formed by the mass.

  The spring constant of the spring portion of the dynamic vibration absorber 15 can be set (adjusted) to an optimum value for suppressing pressure pulsation by changing the pressure of the fuel in the damping chamber 4a2. In order to change the fuel pressure in the damping chamber 4a2, the fuel to the damping chamber 4a2 is controlled by controlling the path switching valve 16 and the second pressure regulating valve 17b based on the detection signal sent from the sensor 18b to the ECU 9. This is performed by controlling the supply amount and the fuel discharge amount from the attenuation chamber 4a2.

  As described above, in the fuel supply system of the engine 1 according to the present embodiment, when the dynamic vibration absorber 15 is provided in the common rail 4 and fuel pressure pulsation occurs in the pressure accumulating chamber 4a1 of the common rail 4, a corresponding change occurs accordingly. The piston 15a of the dynamic vibration absorber 15 vibrates (resonates) by the action of the spring portion formed by the elastic force of the fuel in the damping chamber 4a2, thereby absorbing vibration energy due to pressure pulsation in the pressure accumulating chamber 4a1. it can.

  Thereby, the pressure pulsation propagating from the injector 5 to the supply pump 3 side through the common rail 4 can be attenuated, and the pressure pulsation propagating from the supply pump 3 side to the injector 5 through the common rail 4 can also be attenuated.

  Therefore, the pressure pulsation of the fuel propagating in the common rail 4 can be more efficiently suppressed as compared with the case where only the orifice (pulsation damping means) is installed in the common rail 4. As a result, even if the flow rate of the fuel injected from the injector 5 into the combustion chamber is very small, the injection flow rate can be stabilized.

  In addition, since the dynamic vibration absorber 15 has a simple structure using the piston 15a, the dynamic vibration absorber 15 can be easily and inexpensively provided on the common rail 4 and does not require difficult control. Furthermore, since the dynamic vibration absorber 15 is small and lightweight, the size and weight of the common rail 4 do not increase extremely.

  Next, FIG. 2 shows a modification of the fuel supply system. In this fuel supply system, the above-described dynamic vibration absorber 15 includes a damper 15b. That is, the damper 15b for the movement of the piston 15a is installed between one surface intersecting the axial direction of the piston 15a and one surface of the damping chamber 4a2 facing this. The damper 15b is a device that absorbs vibration due to pressure pulsation generated in the pressure accumulating chamber 4a1, and the vibration damping effect can be improved by providing the damper 15b.

  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.

  A plurality of pistons 15a of the dynamic vibration absorber 15 may be installed in parallel. At this time, each piston can be set to a different mass. As a result, a plurality of resonance frequencies can be set and a damping action can be generated for pulsations with different vibrations, so that the damping effect can be further improved.

  The internal combustion engine fuel supply system of the present invention and the internal combustion engine including the same can include the dynamic vibration absorber that attenuates the pressure pulsation of the fuel in the common rail, thereby suppressing the pressure pulsation propagating 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)
4a Fuel distribution pipe 4a1 Fuel accumulator (first chamber)
4a2 Pulsation damping chamber (second chamber)
4b, 4c, 4d Fuel inlet 4e, 4f, 4g Fuel outlet 5 Injector (fuel injection device)
9 Electronic control unit (control unit)
10 Return piping 15 Dynamic vibration absorber 15a Piston 15b Damper 16 Path switching valve (first valve)
17a First pressure regulating valve 17b Second pressure regulating valve (second valve)
18a sensor (first sensor)
18b Sensor (second sensor)

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 dynamic vibration absorber that attenuates fuel pressure pulsation,
The dynamic vibration absorber is
A piston having a mass set in advance in the fuel flow pipe of the common rail provided in a movable state along the longitudinal direction of the fuel flow pipe;
A second chamber provided in a state separated from the first chamber connected to the plurality of fuel injection devices by the piston in the fuel flow pipe of the common rail;
A fuel supply system for an internal combustion engine having a spring portion formed by the fuel supplied to the second chamber. A first sensor provided in the first chamber for detecting the pressure of fuel in the first chamber;
A second sensor provided in the second chamber for detecting the pressure of fuel in the second chamber;
A first valve for controlling a flow rate of fuel supplied to the second chamber;
A second valve for controlling a flow rate of fuel discharged from the second chamber;
The spring constant of the dynamic vibration absorber is adjusted by controlling the fuel pressure in the second chamber by controlling the first and second valves based on detection information from the first and second sensors. The fuel supply system for an internal combustion engine according to claim 1, further comprising a control unit.   The fuel supply system for an internal combustion engine according to claim 1 or 2, further comprising a damper for movement of the piston.   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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