JP2019183815A - Control device of internal combustion engine - Google Patents

Abstract

To suppress the discharge of microparticulate matters.SOLUTION: On a top surface of a main combustion chamber (2), a sub chamber (51) communicating with the inside of the main combustion chamber (2) through a communication hole (52) is formed. Fuel is injected from a main fuel injection valve (3) into the main combustion chamber (2), and fuel is injected from a sub fuel injection valve (53) into the sub chamber (51). From the communication hole (52), a jet flame is ejected. When the temperature representing the temperature on a wall surface in an engine combustion chamber is lower than a set temperature, main injection amount injected from the main fuel injection valve (3) into the main combustion chamber (2) is reduced, and a sub injection amount injected in an intake stroke from the sub fuel injection valve (53) into the sub chamber (51) is increased.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a control device for an internal combustion engine.

  A main fuel injection valve for injecting main fuel is disposed in the intake port, and has a spark plug and a sub fuel injection valve on the top surface of the main combustion chamber, communicating with the main combustion chamber through a communication hole. A sub chamber is formed.Sub fuel is injected from the sub fuel injection valve into the sub chamber, and by burning this sub fuel, a jet flame is ejected from the communication hole, and this jet flame causes the air-fuel mixture in the main combustion chamber. An internal combustion engine in which is combusted is known (see, for example, Patent Document 1).

JP-A-6-33768

  By the way, in such an internal combustion engine, when the main fuel injection valve is arranged in the main combustion chamber and fuel is injected from the main fuel injection valve into the main combustion chamber, when the wall surface temperature of the main combustion chamber is low as in the cold state, Since the fuel injected into the main combustion chamber cannot evaporate sufficiently, it adheres to the inner wall surface of the main combustion chamber. When the fuel adheres on the inner wall surface in the main combustion chamber in this way, the adhered fuel is heated and carbonized in a state of insufficient oxygen, resulting in a problem that a large amount of particulate matter (PM) is generated. However, in the above-mentioned Patent Document 1, no consideration is given to the adhesion of fuel on the inner wall surface of the main combustion chamber.

  In order to solve the above problems, according to the present invention, a main fuel injection valve for injecting fuel into the main combustion chamber is provided, and the top surface of the main combustion chamber is connected to the main combustion chamber via a communication hole. And a sub-chamber having a spark plug and a sub fuel injection valve is formed. Sub fuel is injected from the sub fuel injection valve into the sub chamber, and jet fuel is ejected from the communication hole by burning the sub fuel. In the control device for an internal combustion engine in which the air-fuel mixture in the main combustion chamber is combusted by the jet flame, when the temperature representative of the temperature of the wall surface of the engine combustion chamber is lower than the set temperature, the main fuel injection valve to the main combustion chamber A control device for an internal combustion engine is provided that reduces the main injection amount injected into the sub-chamber and increases the sub-injection amount injected from the sub fuel injection valve into the sub chamber during the intake stroke.

  Since the sub chamber receives both the combustion heat of the sub fuel in the sub chamber and the combustion heat of the main fuel in the main combustion chamber, the temperature becomes extremely high. Therefore, when the amount of sub-injection injected from the sub fuel injection valve into the sub chamber during the intake stroke is increased, the fuel that has sufficiently evaporated in the sub chamber is injected into the main combustion chamber during the intake stroke through the communication hole. Further, at this time, the fuel flows at high speed in the communication hole, so that the evaporation of the fuel is also promoted at this time. Therefore, the fuel adhesion on the inner wall surface in the main combustion chamber is suppressed by an amount corresponding to the increase in the sub-injection amount, thereby preventing the particulate matter (PM) from being discharged.

FIG. 1 is an overall view of an internal combustion engine. FIG. 2 is a view of the cylinder head as viewed from below. FIG. 3 is a side cross-sectional view of the internal combustion engine taken along the line AA of FIG. FIG. 4 is an enlarged side sectional view around the sub chamber. FIG. 5 is a cross-sectional view of the sub chamber casing taken along the line BB of FIG. FIG. 6 is a view showing an jet jet flame from the sub chamber. 7A and 7B are diagrams showing the sub injection amount and the main injection amount. 8A and 8B are diagrams showing the relationship between the sub-injection amount and the engine coolant temperature. FIG. 9 is a diagram illustrating the sub injection amount and the main injection amount. FIG. 10 is a diagram illustrating the sub injection amount and the main injection amount. FIG. 11 is a diagram illustrating the sub injection amount and the main injection amount. FIG. 12 is a flowchart for performing the injection control.

  FIG. 1 shows an overall view of an internal combustion engine using gasoline as fuel. Referring to FIG. 1, 1 is an engine body, 2 is a main combustion chamber of each cylinder, 3 is a main fuel injection valve for injecting fuel into each main combustion chamber 2, 4 is a surge tank, 5 is an intake branch pipe , 6 indicate exhaust manifolds, respectively. The surge tank 4 is connected to the outlet of the compressor 8 a of the exhaust turbocharger 8 via the intake duct 7, and the inlet of the compressor 8 a is connected to the air cleaner 10 via the intake air amount detector 9. A throttle valve 11 driven by an actuator is disposed in the intake duct 7, and an intercooler 12 for cooling intake air flowing through the intake duct 7 is disposed around the intake duct 7.

  On the other hand, the exhaust manifold 6 is connected to the inlet of the exhaust turbine 8 b of the exhaust turbocharger 8, and the outlet of the exhaust turbine 8 b is connected to the exhaust purification catalytic converter 14 via the exhaust pipe 13. The exhaust manifold 5 and the surge tank 4 are connected to each other via an exhaust gas recirculation (hereinafter referred to as EGR) passage 15, and an EGR control valve 16 is disposed in the EGR passage 15. Each main fuel injection valve 3 is connected to a fuel distribution pipe 17, and this fuel distribution pipe 17 is connected to a fuel tank 19 via a fuel pump 18.

  The electronic control unit 20 comprises a digital computer and is connected to each other by a bidirectional bus 21. A ROM (read only memory) 22, a RAM (random access memory) 23, a CPU (microprocessor) 24, an input port 25 and an output port 26 are connected. It comprises. The engine body 1 is provided with a water temperature sensor 33 for detecting the engine cooling water temperature. The output signal of the water temperature sensor 33 and the output signal of the intake air amount detector 9 are respectively sent to the corresponding AD converters 27. To the input port 25. A load sensor 31 that generates an output voltage proportional to the amount of depression of the accelerator pedal 30 is connected to the accelerator pedal 30, and the output voltage of the load sensor 31 is input to the input port 25 via the corresponding AD converter 27. The Further, a crank angle sensor 32 that generates an output pulse every time the crankshaft rotates, for example, 30 ° is connected to the input port 25. On the other hand, the output port 26 is connected to the main fuel injection valve 3, the actuator for driving the throttle valve 11, the EGR control valve 16, and the fuel pump 18 through corresponding drive circuits 28.

  2 shows a bottom view of the top surface of the combustion chamber 2 shown in FIG. 1, and FIG. 3 shows a side sectional view of the engine body 1 taken along the line AA in FIG. 2 and 3, 41 is a cylinder block, 42 is a cylinder head mounted on the cylinder block 41, 43 is a piston that reciprocates within the cylinder block 41, 44 is a pair of intake valves, and 45 is an intake port. , 46 are a pair of exhaust valves, and 47 is an exhaust port. As shown in FIGS. 2 to 5, a sub chamber casing 50 is attached to the center of the top surface of the main combustion chamber 2. In the example shown in FIGS. 2 to 5, the sub chamber casing 50 has a thin hollow cylindrical shape whose both ends are closed, and the main axis of the sub chamber casing 50 extends mainly in the direction of the center axis of the cylinder. It is attached to the top surface of the combustion chamber 2. In the example shown in FIGS. 2 to 5, the upper portion of the sub chamber casing 50 is located in the cylinder head 42, and only the lower portion of the sub chamber casing 50 is exposed in the main combustion chamber 2. A sub chamber 51 is formed in the sub chamber casing 50, and the sub chamber casing 50 has a radial shape from the periphery of the end of the sub chamber 51 on the main combustion chamber 2 side toward the periphery of the main combustion chamber 2. A plurality of communication holes 52 extending in the direction are formed.

  In this case, in the embodiment of the present invention, as shown in FIG. 5, each communication hole 52 extends radially from the central axis of the sub chamber casing 50 at equal angular intervals with respect to the central axis of the sub chamber casing 50. Is formed. Further, in the embodiment of the present invention, a sub fuel injection valve 53 is arranged at the center of the top surface of the sub chamber 51, and a spark plug 54 is arranged around the top surface of the sub chamber 51. As shown in FIG. 1, the auxiliary fuel injection valve 53 of each cylinder is connected to a fuel distribution pipe 55, and this fuel distribution pipe 55 is connected to the fuel tank 19 via a fuel pump 56. Further, the auxiliary fuel injection valve 53 and the spark plug 54 of each cylinder are connected to the output port 26 via the corresponding drive circuit 28.

  Next, the injection control from the main fuel injection valve 3 and the auxiliary fuel injection valve 53 will be described with reference to FIG. 7A. 7A shows the amount of fuel injected from the main fuel injection valve 3 into the main combustion chamber 2, that is, the main injection amount and the fuel injected from the sub fuel injection valve 53 into the sub chamber 51 during normal operation. The amount, that is, the sub injection amount is shown. As shown in FIG. 7A, during normal operation, fuel QM is injected from the main fuel injection valve 3 into the main combustion chamber 2 during the intake stroke, whereby an air-fuel mixture is formed in the main combustion chamber 2. Next, at the end of the compression stroke, the fuel QI is injected from the auxiliary fuel injection valve 53 into the auxiliary chamber 51. Next, the fuel in the sub chamber 51 is ignited by the spark plug 54 and combusted. When the fuel in the sub chamber 51 is combusted, a jet flame J as shown in FIG. 6 is ejected from each communication hole 52 to the main combustion chamber 2, and the air-fuel mixture in the main combustion chamber 2 becomes the jet flame. Burned by J.

  By the way, for example, when the engine temperature is low, such as when the engine is cold-started, the wall surface temperature of the main combustion chamber 2 and the top surface temperature of the piston 43 do not increase easily even when the engine is started. Accordingly, if fuel is directly injected from the main fuel injection valve 3 into the main combustion chamber 2 at this time, the fuel injected into the main combustion chamber 2 cannot be sufficiently evaporated, and as a result, a part of the injected fuel is burned into the main combustion chamber. It adheres on the inner wall surface of the chamber 2. When the injected fuel adheres to the inner wall surface in the main combustion chamber 2 in this way, the attached fuel is heated and carbonized in a state of lack of oxygen, and as a result, a large amount of particulate matter (PM) is generated. Is produced.

  On the other hand, since the sub chamber 51 receives both the combustion heat of the sub fuel in the sub chamber 51 and the combustion heat of the main fuel in the main combustion chamber 2, the temperature becomes extremely high. The sub chamber 51 is formed in the sub chamber casing 50, and the heat capacity of the sub chamber casing 50 is much smaller than the heat capacities of the cylinder block 41 and the piston 43. Therefore, even when the engine temperature is low, such as when the engine is cold started, the temperature of the sub chamber 51 becomes extremely high. Therefore, in the embodiment according to the present invention, the fuel injected from the main fuel injection valve 3 is injected into the main combustion chamber 2 by utilizing the fact that the temperature of the sub chamber 51 becomes extremely high even when the engine temperature is low. It is made to suppress adhering on the inner wall surface of the.

  That is, in the embodiment according to the present invention, when the engine temperature is low as in the cold start of the engine, as shown by QA in FIG. 7B, a part of fuel to be injected from the main fuel injection valve 3 (hatched portion) Are injected from the auxiliary fuel injection valve 53 into the auxiliary chamber 51 during the intake stroke. When the fuel QA is injected into the sub chamber 51 from the sub fuel injection valve 53 in this way, the temperature of the sub chamber 51 is extremely high. Therefore, after the fuel QA has sufficiently evaporated in the sub chamber 51, the communication hole 52 Is injected into the main combustion chamber 2 during the intake stroke. Further, at this time, the fuel QA flows through the communication hole 52 at a high speed, so that the evaporation of the fuel QA is also promoted at this time. Therefore, the fuel QA is prevented from adhering to the inner wall surface of the main combustion chamber 2 and the particulate matter (PM) can be prevented from being discharged.

  Therefore, in the embodiment according to the present invention, the main fuel injection valve 3 for injecting fuel into the main combustion chamber 2 is provided, and the main combustion chamber 2 is connected to the top surface of the main combustion chamber 2 through the communication hole 52. 2 is formed, and a sub chamber 51 having a spark plug 54 and a sub fuel injection valve 53 is formed. Sub fuel is injected from the sub fuel injection valve 54 into the sub chamber 51, and the sub fuel is burned. In the control device for an internal combustion engine in which the jet flame is ejected from the communication hole 52 and the air-fuel mixture in the main combustion chamber 2 is combusted by the jet flame, a temperature representative of the temperature of the inner wall surface of the engine combustion chamber 2 is set. When the temperature is lower than the temperature, for example, when the temperature of the engine coolant is lower than the set temperature, the main injection amount injected from the main fuel injection valve 3 into the main combustion chamber 2 is reduced, and the sub fuel injection valve 54 Intake air into sub chamber 51 So that increasing the amount of auxiliary injection quantity during injection.

  8A and 8B show the relationship between the auxiliary fuel amount QA injected from the auxiliary fuel injection valve 54 during the intake stroke and the engine coolant temperature. In the example shown in FIG. 8A, when the engine coolant temperature is lower than the set temperature TM, the sub fuel amount QA is increased as the engine coolant temperature is lowered. On the other hand, in the example shown in FIG. 8B, when the engine coolant temperature is lower than the set temperature TM, the auxiliary fuel amount QA is increased compared to when the engine coolant temperature is higher than the set temperature TM. In the example shown in FIG. 8B, when the engine coolant temperature is higher than the set temperature TM, the auxiliary fuel amount QA can be made zero.

  FIG. 9 shows a further embodiment of the main injection amount and the sub injection amount when the engine temperature is low as in the cold engine start. By the way, the injection speed of the auxiliary fuel QA from the communication hole 52 into the main combustion chamber 2 becomes the highest during the intake stroke, and therefore, the fuel injection from the auxiliary fuel injection valve 53 ends before the compression bottom dead center. Is preferred. However, as shown in FIG. 9, the auxiliary fuel QA can be continuously injected from the auxiliary fuel injection valve 53 from the intake stroke to the beginning of the compression stroke. However, in this case, during the compression stroke, the injection speed of the auxiliary fuel QA from the communication hole 52 into the main combustion chamber 2 becomes small, so that it is not possible to expect the fuel evaporation to be accelerated accordingly.

  FIG. 10 shows still another embodiment regarding the main injection amount and the sub-injection amount when the engine temperature is low, such as at the time of engine cold start. In this embodiment, as shown in FIG. 10, the fuel injection from the auxiliary fuel injection valve 53 during the intake stroke is performed in a plurality of times. In this case also, a part of the auxiliary fuel QA can be injected at the beginning of the compression stroke.

  FIG. 11 shows still another embodiment regarding the main injection amount and the sub-injection amount when the engine temperature is low as in the cold engine start. In this embodiment, the fuel injection QA from the auxiliary fuel injection valve 53 is started slightly before the intake top dead center. In this embodiment, since the temperature in the sub chamber 51 is the highest among the embodiments described so far, evaporation of the sub fuel Q is most promoted. However, in this embodiment, unburned fuel may be discharged from the sub chamber 51 depending on the closing timing of the exhaust valve 46.

  FIG. 12 shows a routine for executing the fuel injection control, and this routine is executed by interruption every predetermined time. Referring to FIG. 12, first, at step 60, the required injection amount Qt is calculated based on the required torque of the engine. Next, at step 61, an auxiliary fuel amount QI injected from the auxiliary fuel injection valve 53 at the end of the compression stroke is calculated. Next, at step 62, the auxiliary fuel amount QA from the auxiliary fuel injection valve 53 is calculated. Next, at step 63, the main injection amount QM from the main fuel injection valve 3 is calculated by subtracting the sub fuel amount QI and the sub fuel amount QA from the required injection amount Qt. Next, at step 64, a fuel injection process is performed.

2 Main combustion chamber 3 Main fuel injection valve 44 Intake valve 46 Exhaust valve 51 Sub chamber 52 Communication hole 53 Sub fuel injection valve 54 Spark plug

Claims (1)

  A main fuel injection valve for injecting fuel into the main combustion chamber is provided, and a sub-portion communicating with the main combustion chamber through a communication hole on the top surface of the main combustion chamber and having a spark plug and a sub fuel injection valve. A chamber is formed, and the auxiliary fuel is injected from the auxiliary fuel injection valve into the auxiliary chamber. By burning the auxiliary fuel, a jet flame is ejected from the communication hole, and the jet flame causes the air-fuel mixture in the main combustion chamber to In a control device for an internal combustion engine to be combusted, when the temperature representative of the temperature of the wall surface of the engine combustion chamber is lower than the set temperature, the main injection amount injected from the main fuel injection valve into the main combustion chamber is reduced and the auxiliary fuel is reduced. A control apparatus for an internal combustion engine that increases a sub-injection amount that is injected from an injection valve into a sub-chamber during an intake stroke.

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