JP2009103108A - Cylinder direct injection type internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cylinder direct injection type internal combustion engine for controlling a fuel injection direction according to a change of a flow direction of a swirl flow formed based on air sucked in a combustion chamber. <P>SOLUTION: This cylinder direct injection type internal combustion engine includes an injector 6 for cylinder injection for injecting fuel in a direction for strengthening a swirl flow (tumble or swirl) formed in a combustion chamber by air sucked in the combustion engine via first and second intake valves 31a, 31b. The engine includes a control unit for controlling an injection direction of the fuel along a flow direction of the swirl flow controlled by changing an air intake direction into the combustion chamber. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an in-cylinder direct injection internal combustion engine, and more particularly to an internal combustion engine that enhances a swirl flow formed by air sucked into a combustion chamber using fuel injected from an in-cylinder injector.

As in Patent Document 1, a direct injection type internal combustion engine that forms a tumble or swirl swirl using a difference in lift between two intake valves has been proposed.
JP 2003-106177 A

  On the other hand, a method of assisting the tumble formed by the intake air using fuel injection is conceivable. When these are combined, the swirl flow forming the tumble can be strengthened using the fuel injection.

  However, control of the fuel injection direction corresponding to the change in the direction of the swirl flow that forms the tumble or swirl has not been studied so far, and the fuel injection direction sufficiently corresponds to the change in the direction of the swirl flow. Otherwise, the swirl flow may not be effectively enhanced by the fuel injection, but rather may be attenuated.

  Accordingly, an object of the present invention is to provide an in-cylinder direct injection internal combustion engine that controls the fuel injection direction in accordance with the change in the direction of the flow of the swirl flow formed based on the air taken into the combustion chamber. .

  An in-cylinder direct injection internal combustion engine according to the present invention is an in-cylinder injection injector that injects fuel in a direction that reinforces a swirl flow formed in a combustion chamber by air sucked into the combustion chamber via an intake valve. And a control unit that controls the fuel injection direction along the direction of the swirl flow controlled by changing the direction of air intake into the combustion chamber. Thereby, the direction of fuel injection is controlled according to the direction of the flow of the swirl flow (tumble or swirl), and the swirl flow can be effectively enhanced by the fuel injection.

  Preferably, the intake valve has first and second intake valves, and the control unit forms a swirl flow formed by controlling the amount of air taken into the combustion chamber via the first and second intake valves. The direction of the flow of the fuel is controlled, and fuel is injected based on the difference between the amount of air sucked into the combustion chamber via the first intake valve and the amount of air sucked into the combustion chamber via the second intake valve Control the direction. By adjusting the difference between the amount of air sucked through the first intake valve and the amount of air sucked through the second intake valve, the direction of the swirl flow is controlled, and the fuel injection The direction can be controlled in a direction that enhances the swirl flow.

  More preferably, when the difference is small, a tumble is formed as a swirl flow, and when the difference is large, a swirl is formed as a swirl flow.

  Preferably, at least one of the first intake valve and the second intake valve has a variable lift amount, and the difference is varied by controlling the lift amount difference between the first intake valve and the second intake valve. The direction of the swirl flow is controlled by adjusting the lift amount (maximum lift amount) of the intake valve. When the difference in the lift amount of each valve is small, a tumble is formed as a swirl flow, and when the difference is large, a swirl is formed as a swirl flow.

  Preferably, when the swirl is formed as a swirl flow, the injector injects the fuel in a direction in which the swirl is strengthened and the fuel at a flow rate outside the swirl flow and slower than the main spray. A secondary spray is performed. By suppressing the rebound in the reverse swirl direction formed by the main spray by the sub spray, it becomes possible to effectively strengthen the swirl flow (swirl) by the fuel injection. Further, the sub-spray is caught in the main spray direction due to the difference in flow rate between the main spray and the sub-spray, and the main spray can be accelerated to enhance the swirl flow (swirl).

  Preferably, when the swirl is formed as a swirling flow, the injector suppresses the main spray that injects fuel in a direction that strengthens the swirl and the rebound of the fuel by the main spray in the reverse swirl direction. A sub-spray that injects fuel at a slower flow rate than the main spray is performed in a space where rebounding occurs. By suppressing the rebound in the reverse swirl direction formed by the main spray by the sub spray, it becomes possible to effectively strengthen the swirl flow (swirl) by the fuel injection. Further, the sub-spray is caught in the main spray direction due to the difference in flow rate between the main spray and the sub-spray, and the main spray can be accelerated to enhance the swirl flow (swirl).

  In another direct injection internal combustion engine according to the present invention, a tumble is formed in the combustion chamber by an in-cylinder injector for injecting fuel and air sucked into the combustion chamber via an intake valve. In the case where the swirl is formed in the combustion chamber so that the injector performs longitudinal injection to strengthen the tumble, the fuel injection direction so that the injector performs lateral injection and strengthens the swirl And a control unit for controlling. Thus, the direction of fuel injection is controlled according to the direction of tumble or swirl flow, and the swirl flow can be effectively enhanced by fuel injection.

  As described above, according to the present invention, there is provided a direct injection type internal combustion engine that controls the fuel injection direction in accordance with the change in the direction of the flow of the swirl flow formed based on the air taken into the combustion chamber. be able to.

  Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. The internal combustion engine in the first embodiment includes an engine body 1, an intake passage 3, an electrically controlled throttle valve 4, an in-cylinder injector 6, a spark plug 7, an exhaust passage 8, a catalytic converter 9, an ECU 20, first and second Intake valves 31a and 31b, an exhaust valve 32, and a valve lift amount continuous variable mechanism 38 are provided.

  First, the operation of the engine body 1 will be described. Air is sucked into the combustion chamber 5 of each cylinder of the engine body 1 under the control of the electric control throttle valve 4 via the intake passage 3. The amount of air taken in is controlled by the lift amount of the first and second intake valves 31a and 31b. The fuel mf injected from the in-cylinder injector 6 mixes with the sucked air to form an air-fuel mixture. The air-fuel mixture burns by ignition of the spark plug 7 based on the ignition signal from the ECU 20. Exhaust gas from the engine body 1 is discharged from the exhaust passage 8 when the exhaust valve 32 is opened, and is purified by the catalytic converter 9 provided in the exhaust passage 8.

  The lift amount (maximum lift amount) of the first intake valve 31a does not vary. The lift amount (maximum lift amount) of the second intake valve 31b is changed according to the operating state of the internal combustion engine via the valve lift amount continuously variable mechanism 38. Therefore, the lift amount difference (lift amount difference DVL) between the first and second intake valves 31a and 31b is adjusted by the valve lift amount continuous variable mechanism 38.

When the lift amount difference DVL is small (when the lift amount difference threshold value DVL is smaller than ₀ ), the air flow (swirl flow) sucked into the combustion chamber 5 through the first and second intake valves 31a and 31b is exhausted. The intake port of the intake passage 3 is formed so as to form a forward tumble (see the thick broken lines in FIGS. 2 and 3) that pivots so as to descend the valve 32 and raise the first and second intake valves 31a and 31b. The shape is set.

When the lift amount difference DVL is large (when the lift amount difference threshold value DVL is ₀ or more), the flow of air (swirl flow) drawn into the combustion chamber 5 via the first and second intake valves 31a and 31b is generated. Of the first and second intake valves 31a and 31b, the intake valve having a large lift amount (the first intake valve 31a in the present embodiment) is swung from the exhaust valve 32 side, and the intake valve having a small lift amount from the exhaust valve 32 side. A swirl (see thick broken lines in FIGS. 4 and 5) that turns to the valve (the second intake valve 31b in the present embodiment) is formed.

  The in-cylinder injector 6 in this embodiment can change the direction in which the fuel mf is injected in the cylinder by adjusting the eccentric state of the needle valve in the in-cylinder injector nozzle (not shown). The control of the direction in which the fuel mf is injected is not limited to the adjustment of the eccentric state of the needle valve, but may take other forms.

  The direction of the fuel mf injected from the injector 6 is controlled by the ECU 20. Specifically, when the tumble is formed by the intake air, the injection direction of the fuel mf faces the exhaust valve 32 side (with respect to the line segment connecting the first and second intake valves 31a and 31b in a top view). It is set in one direction that strengthens the tumble (see FIGS. 2 and 3) in line with the direction of the tumble flow (on the substantially perpendicular bisector and facing the exhaust valve 32 side).

  When the swirl is formed by the intake air, the injection direction of the fuel mf faces the intake valve side where the lift amount is large and coincides with the direction of the swirl flow to strengthen the swirl (main spray direction). The direction in which rebound by spraying in the direction of strengthening the swirl occurs (the direction between the first intake valve 31a having a large lift and the wall surface of the combustion chamber 5, the sub spraying direction) is set in two directions ( (See FIGS. 4 and 5).

  That is, the fuel from the injector 6 is injected along the direction of the flow of the swirl flow (tumble or swirl) formed by the intake air (toward the side where the exhaust valve is located), and the fuel injection is swirled (tumble or tumble). Speed up swirl). The direction of the swirl flow differs between tumble and swirl, and also varies depending on the degree of swirl (the degree of lateral rotation component). In this embodiment, the fuel mf is calculated by calculating whether the formed swirling flow is a tumble or a swirl and the degree of the swirl from the difference in the lift amount between the first and second intake valves 31a and 31b (lift amount difference DVL). Controls the injection direction.

  By injecting the fuel mf along the direction of the swirl flow near the bottom dead center of the intake air, the swirl flow formed by the intake air can be strengthened by using the penetration force of the injected fuel, and until the ignition timing Good combustion can be obtained by maintaining the swirl flow well.

  The ECU 20 includes a microcomputer including a CPU, a ROM, a RAM, an A / D converter, an input / output interface, and the like, receives input signals from various sensors, performs arithmetic processing based on the signals, Control the operation. In particular, in the present embodiment, the ECU 20 calculates the direction of the swirling flow formed by the intake air, and injects the fuel mf so as to enhance the swirling flow.

  Specifically, the ECU 20 calculates the difference between the lift amount of the first intake valve 31a and the lift amount of the second intake valve 31b from the state (set value) of the valve lift amount continuously variable mechanism 38, and the difference is small. In this case, it is assumed that a tumble is formed in the combustion chamber 5 by the intake air, and fuel mf is injected in the vicinity of the intake bottom dead center in the direction in which the tumble is strengthened (the direction that coincides with the direction of the tumble flow). Directional injection (see FIGS. 2 and 3), and if the difference is large, it is assumed that a swirl is formed in the combustion chamber 5 by intake air, and the direction in which the swirl is strengthened based on the difference (the direction of the swirl flow) (Middle direction) and fuel mf injection (sub spray) less than the main spray toward the space where rebound from the main spray occurs (lateral injection). Figure 4, see Figure 5). That is, in the secondary spray, fuel mf is injected in a direction along the swirl flow formed by the intake air and toward the outside of the swirl flow (near the wall surface of the combustion chamber 5).

  The injector 6 is installed near the upper side of the cylinder and on a substantially perpendicular bisector with respect to the line connecting the first and second intake valves 31a and 31b when viewed from the upper surface, and is used for the main spray provided in the injector nozzle. The fuel mf is injected from the hole and the sub spray hole at a predetermined timing (simultaneously). The hole diameter of the main spray hole is set smaller than the hole diameter of the sub spray hole so that the flow rate is increased, and the number of injection holes is larger than that of the sub spray hole so as to increase the injection amount.

  When injection of fuel mf for strengthening the tumble is performed, the fuel mf from the main spray hole and the sub spray hole corresponds to the line segment connecting the first and second intake valves 31a and 31b when viewed from above. Injection is performed in parallel with the substantially perpendicular bisector, that is, in the same direction.

  When the fuel mf for intensifying the swirl is injected, the fuel mf from the main spray hole is substantially vertically bisected with respect to the line connecting the first and second intake valves 31a and 31b when viewed from above. The fuel is injected toward the intake valve (the first intake valve 31a in this embodiment) in the direction intersecting at the first angle θ1 (> 0 degree) and having a large lift amount. The fuel mf from the auxiliary spray hole is an intake air having a large lift amount in a direction intersecting the substantially perpendicular bisector with respect to the line connecting the first and second intake valves 31a and 31b at the second angle θ2 (> θ1). It is injected toward the direction between the valve and the wall surface of the combustion chamber 5 (see FIG. 4).

  When the fuel mf for reinforcing the swirl is injected, most of the fuel mf injected from the main spray hole flows in a direction for strengthening the swirl formed by the intake air (see the thick broken lines in FIGS. 4 and 5). Part of the fuel mf injected from the main spray hole rebounds in the reverse swirl direction (the swirl turning direction and the reverse rotation direction) (see dotted lines in FIGS. 4 and 5). However, the fuel mf injected from the sub spray hole is caught by the flow velocity difference from the fuel mf injected from the main spray hole, and the rebound of the fuel mf from the main spray hole in the reverse swirl direction is suppressed ( (Refer to the thin solid lines in FIGS. 4 and 5). Moreover, the main spray is accelerated by being caught. Accordingly, the swirl can be strengthened by effectively using the injected fuel mf without weakening the flow of the swirl by the fuel mf bounced back in the reverse swirl direction.

Next, the procedure of fuel injection direction control by the ECU 20 will be described with reference to the flowchart of FIG. The control shown in the flowchart of FIG. 6 is performed for each predetermined crank angle during which the engine body 1 is operating. In step S11, it is determined whether or not the lift amount difference DVL is smaller than the lift amount difference threshold DVL ₀ . Specifically, the current maximum lift amount of the second intake valve 31b set according to the operating state is detected or estimated, and the maximum lift amount and the maximum lift amount (fixed value) of the first intake valve 31a are determined. The difference (lift amount difference DVL) is compared with the lift amount difference threshold value DVL ₀ . If it is smaller, the swirl flow formed by the intake air is assumed to be tumble, and the process proceeds to step S12. If not, the swirl flow formed by the intake air is assumed to be a swirl, and the process proceeds to step S13.

  In step S12, tumble-enhancing fuel injection (longitudinal injection) is set. Specifically, when viewed from above, the fuel mf from the main spray hole and the sub spray hole is parallel to a substantially perpendicular bisector with respect to the line connecting the first and second intake valves 31a and 31b. The injection direction is set.

  In step S13, fuel injection (lateral injection) for swirl enhancement is set. Specifically, the fuel mf from the main spray hole is viewed in a direction intersecting with a substantially perpendicular bisector with respect to the line connecting the first and second intake valves 31a and 31b at the first angle θ1 when viewed from above. The injection direction of the fuel mf from the main spray hole is set on the intake valve (first intake valve 31a in this embodiment) side with a large lift amount, and the line connecting the first and second intake valves 31a and 31b is set. The injection direction of the fuel mf from the sub spray hole is set in a direction intersecting the substantially perpendicular bisector at the second angle θ2 and between the intake valve having a large lift amount and the wall surface of the combustion chamber 5. . The values of the first and second angles θ1, θ2 are set based on the degree of swirl calculated or estimated from the value of the lift amount difference DVL.

  In step S14, fuel mf is injected in the injection direction set in step S12 or step S13 at the injection timing set near the intake bottom dead center.

In the present embodiment, the fuel mf is changed in accordance with the difference in lift amount (lift amount difference DVL) between the plurality of intake valves (first and second intake valves 31a, 31b) that is varied by the valve lift amount continuous variable mechanism 38 or the like. When the tumble is formed in the combustion chamber 5 by controlling the injection direction so that the lift amounts are substantially matched (lift amount difference DVL <lift amount difference threshold DVL ₀ ), the tumble is strengthened by the vertical injection of the fuel mf, When the swirl is formed in the combustion chamber 5 with different lift amounts (lift amount difference DVL ≧ lift amount difference threshold value DVL ₀ ), the swirl is strengthened by lateral injection of the fuel mf in the direction corresponding to the swirl degree. By controlling the injection direction of the fuel mf based on the difference between the lift amounts of the plurality of intake valves, the swirl flow (tumble or swirl) formed by the intake is effectively enhanced by using the fuel injection. It becomes possible.

  In this embodiment, the flow velocity difference between the fuel injected from the main spray hole and the fuel injected from the sub spray hole is established by making the size of the spray hole different with one injector. However, the flow rate difference may be established in other forms. For example, a configuration in which the size of the spray hole is made different by using two injectors, or a mode in which the spray hole is the same size and the fuel pressure is made different by using two injectors is considered. Will be faster).

  Moreover, although the injection direction variable injector 6 was used and the form which switches and performs the vertical direction injection for strengthening a tumble and the horizontal direction injection for strengthening a swirl was explained, using a plurality of injectors, A mode in which the injector for vertical injection and the injector for horizontal injection are properly used may be used.

  Further, although the mode of adjusting the amount of air sucked through the plurality of intake valves by adjusting the lift amount of the intake valve via the valve lift amount continuous variable mechanism 38 has been described, it is provided at the intake port or the like. The amount of air drawn in may be adjusted using a provided airflow control valve.

It is a block diagram of the internal combustion engine in this embodiment. It is a block diagram seen from the upper surface when the swirl flow forms a tumble, and shows the fuel injection direction and the swirl flow direction. It is the perspective view seen from the side surface in case a swirl flow forms a tumble, and shows the injection direction of a fuel and the flow direction of a swirl flow. It is a block diagram seen from the upper surface when a swirl flow forms a swirl, and shows the injection direction of the fuel and the flow direction of the swirl flow. It is the perspective view seen from the side surface in case a swirl flow forms a swirl, and shows the fuel injection direction and the flow direction of the swirl flow. It is a flowchart which shows the procedure of fuel injection direction control.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine main body 3 Intake passage 4 Electric control throttle valve 6 In-cylinder injector 7 Spark plug 8 Exhaust passage 9 Catalytic converter 20 ECU
31a, 31b First and second intake valves 32 Exhaust valves 38 Valve lift amount continuously variable mechanism

Claims (7)

An in-cylinder injector for injecting fuel in a direction to reinforce a swirl flow formed in the combustion chamber by air sucked into the combustion chamber via an intake valve;
A direct injection type internal combustion engine comprising: a control unit that controls the injection direction of the fuel along the direction of the flow of the swirl flow that is controlled by changing the intake direction of air into the combustion chamber. organ. The intake valve has first and second intake valves,
The controller controls the direction of the swirling flow formed by controlling the amount of air sucked into the combustion chamber via the first and second intake valves, and controls the first intake valve. The fuel injection direction is controlled based on the difference between the amount of air sucked into the combustion chamber via the second intake valve and the amount of air sucked into the combustion chamber via the second intake valve. The internal combustion engine according to claim 1. When the difference is small, a tumble is formed as the swirling flow,
The internal combustion engine according to claim 2, wherein a swirl is formed as the swirl flow when the difference is large. At least one of the first intake valve and the second intake valve has a variable lift amount,
The internal combustion engine according to claim 2, wherein the difference is varied by controlling a difference in lift amount between the first intake valve and the second intake valve.   When the swirl is formed as the swirl flow, the injector sprays the fuel in a direction to strengthen the swirl, and the fuel is discharged outside the swirl flow and at a slower flow rate than the main spray. The internal combustion engine according to claim 1, wherein the secondary spray is injected.   When the swirl is formed as the swirl flow, the injector is configured to suppress main fuel spray that injects the fuel in a direction that strengthens the swirl and rebound of the fuel in the reverse swirl direction by the main spray. 2. The internal combustion engine according to claim 1, wherein a subspray that injects the fuel at a flow rate slower than that of the main spray is performed in a space in which the rebound occurs. An in-cylinder injector for injecting fuel;
When the tumble is formed in the combustion chamber by the air sucked into the combustion chamber through the intake valve, the swirl is placed in the combustion chamber so that the injector performs a longitudinal injection to strengthen the tumble. A direct injection internal combustion engine comprising: a control unit that controls an injection direction of the fuel so that the injector performs a lateral injection to strengthen the swirl. .

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