JP4720799B2 - In-cylinder direct injection internal combustion engine - Google Patents

Description

  The present invention relates to an in-cylinder direct injection internal combustion engine, and more particularly to an internal combustion engine that enhances forward tumble using fuel injected from an in-cylinder injector.

  In-cylinder injectors that can adjust the direction of fuel to be injected have been proposed.

Patent Document 1 discloses an in-cylinder injector that divides the direction of fuel to be injected into two parts, injects one in a tumble or swirl direction, and injects the other in the vicinity of a spark plug.
Japanese Patent Laid-Open No. 11-30124

  However, when the fuel injected on the swirl flow such as tumble collides with the top surface of the piston or the like, the injected fuel rolls up (bounces) in the opposite direction to the swirl flow. There is a possibility that the swirl flow such as tumble is weakened by the rebound.

  Accordingly, an object of the present invention is to provide an in-cylinder direct injection internal combustion engine that effectively enhances forward tumble using injected fuel.

  An in-cylinder direct injection internal combustion engine according to the present invention includes an intake port that forms a forward tumble with air sucked into a combustion chamber via an intake valve, and a main spray that injects fuel in a direction that strengthens the forward tumble. An in-cylinder injector that performs sub-spraying that injects fuel at a flow rate slower than that of the main spray in a space where the hoisting occurs in order to prevent the fuel from rolling up in the reverse tumble direction due to the main spray With. The flow in the reverse tumble direction of a part of the fuel injected by the main spray is suppressed by the sub spray, and the forward tumble can be prevented from being weakened by the reverse tumble component.

  Preferably, the injector has a main spray hole used for main spray and a sub spray hole used for sub spray, and the main spray hole is smaller than the sub spray hole, and the main spray hole is smaller. Has more holes than subspray holes. This enables fuel injection with different flow rates and injection amounts using the same injector.

  Preferably, the injector has a main spray hole used for the main spray and a sub spray hole used for the sub spray, and the fuel pressure of the main spray hole is higher than the fuel pressure of the sub spray hole. Large, the main spray holes are the same size as the sub spray holes. This makes it possible to easily inject fuel with different flow rates and injection amounts using injectors with different fuel pressures.

  As described above, according to the present invention, it is possible to provide an in-cylinder direct injection internal combustion engine that effectively enhances forward tumble using injected fuel.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. The in-cylinder direct injection internal combustion engine in the present embodiment includes an engine body 1, an intake passage 3, an electric control throttle valve 4, an in-cylinder injector 6, a spark plug 7, an exhaust passage 8, a catalytic converter 9, an ECU 20, an intake air A valve 31 and an exhaust valve 32 are provided. In FIG. 2, the spark plug 7 is omitted.

  First, the operation of the engine body 1 will be described. Air is sucked into the combustion chamber 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 and timing of inhaling air are controlled by opening and closing the intake valve 31. The fuel injected from the 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 via the exhaust valve 32 and purified by the catalytic converter 9 provided in the exhaust passage 8.

  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.

  The shape of the intake port 3a of the intake passage 3 is set so that the flow of air (swirl flow) sucked into the combustion chamber via the intake valve 31 becomes a forward tumble. The formation of the forward tumble may be performed by a tumble control valve (not shown). In addition, the direction of the fuel injected from the injector 6 is in a space where the tumbling of the spray occurs in a direction (main spray direction) that strengthens the forward tumble formed by intake air and a reverse tumble direction (relative to the main spray direction). It is set to the direction (sub spray direction).

  The injector 6 is installed in the vicinity of the center of the upper surface of the cylinder, and injects fuel at a predetermined timing (simultaneously) from the main spray hole 61 and the sub spray hole 62 provided in the tip (injector nozzle) 6a. The hole diameter of the main spray hole 61 is set smaller than the hole diameter of the sub spray hole 62 so as to increase the flow velocity, and has more injection holes than the sub spray hole 62 so as to increase the injection amount.

  The shape and the injection direction of the main spray hole 61 are set so that the fuel is injected in a direction that reinforces the forward tumble formed by the intake air. That is, the fuel from the main spray hole 61 is injected along the direction of the flow of the forward tumble formed by the intake air (toward the side where the exhaust valve is present), and the fuel injection accelerates the forward tumble.

  The shape and the injection direction of the sub-spray hole 62 are set so that the fuel is injected into the space in which the hoisting occurs in the reverse tumble direction among the fuel injected from the main spray hole 61. That is, the fuel from the secondary spray hole 62 is injected in the direction along the forward tumble flow formed by the intake air and toward the outside of the forward tumble flow.

  For example, the fuel from the main spray hole 61 has a small angle θ1 formed with the moving direction of the piston 1a when viewed from the side, and is injected toward the top surface of the piston 1a. The angle θ2 formed with the moving direction of 1a is large and is injected toward the cylinder wall surface.

  Most of the fuel injected from the main spray hole 61 flows in a direction that reinforces the forward tumble formed by the intake air (see the thick broken line in FIG. 2). A part of the fuel injected from the main spray hole 61 rolls up in the reverse tumble direction (see the dotted line in FIG. 2). However, the fuel injected from the sub-spray hole 62 is entrained due to the difference in flow velocity from the fuel injected from the main spray hole 61, and suppresses the fuel from the main spray hole 61 from rolling up in the reverse tumble direction. (See thin solid line in FIG. 2). Accordingly, the forward tumble can be strengthened by effectively using the injected fuel without the forward tumble flow being weakened by the fuel rolled up in the reverse tumble direction.

  In this embodiment, the flow rate difference between the fuel injected from the main spray hole 61 and the fuel injected from the sub spray hole 62 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 (the flow rate increases when the fuel pressure is high). Will be faster).

It is a lineblock diagram of a direct injection type internal combustion engine in this embodiment. It is a block diagram which shows the fuel-injection state from the injector for cylinder injection in this embodiment. It is a bottom view of the injector for in-cylinder injection. It is a side view of the injector for cylinder injection.

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
31 Intake valve 32 Exhaust valve

Claims (3)

An intake port that forms a forward tumble with air drawn into the combustion chamber via the intake valve; and
The main spray that injects fuel in a direction that strengthens the forward tumble, and the main spray in a space where the hoisting occurs in order to suppress the hoisting of the fuel in the reverse tumble direction by the main spray. An in-cylinder direct injection internal combustion engine comprising: an in-cylinder injector that performs sub-spray for injecting the fuel at a slow flow rate.   The injector has a main spray hole used for the main spray and a sub spray hole used for the sub spray, and the main spray hole is smaller than the sub spray hole. The internal combustion engine according to claim 1, wherein the spray holes have more holes than the sub spray holes.   The injector has a main spray hole used for the main spray and a sub spray hole used for the sub spray, and the fuel pressure of the main spray hole is higher than the fuel pressure of the sub spray hole. 2. The internal combustion engine according to claim 1, wherein the main spray hole is substantially the same size as the sub spray hole.

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