JP2012132354A - Control apparatus of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reliably prevent deposits from accumulating on a nozzle hole of a fuel injector, concerning a control apparatus of an internal combustion engine.SOLUTION: The control apparatus of the internal combustion engine includes: intake ports 22a and 22b, intake valves 14a and 14b, and fuel injectors 26a and 26b that are disposed in a cylinder 12; a communication part 30 for bringing the intake ports 22a and 22b into communication with each other; a shut-off valve 32 that is arranged upstream of a fuel injection position of the fuel injector 26a in the intake port 22a and shuts off the intake port 22a; a valve stop device for stopping the intake valve 14b in a closed state; and a part-of-valve stop operation device for, when a part-of-valve stop operation is carried out which stops the intake valve 14b using the valve stop device to operate the internal combustion engine, stopping fuel injection from the fuel injector 26b in the intake port 22b corresponding to the stopped intake valve 14b and shutting-off the shut-off valve 32 to inject the fuel only from the fuel injector 26a.

Description

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

  There is known an internal combustion engine that includes a plurality of intake ports per cylinder and that includes a fuel injector for each of the plurality of intake ports (see, for example, Patent Document 1).

JP 2010-138804 A JP 2010-96079 A

  The internal combustion engine as described above may be operated by injecting fuel from only a part of a plurality of fuel injectors of one cylinder. In this case, there is a problem that deposits are likely to accumulate in the injection hole of the fuel injector that has stopped the fuel injection. This is due to the following reason. The vicinity of the nozzle hole at the tip of the fuel injector receives radiant heat from the combustion chamber. In a fuel injector that injects fuel, a temperature rise near the injection hole is suppressed by a cooling effect by the fuel passing through the inside. On the other hand, in the fuel injector in which the fuel injection is stopped, since the cooling effect by the passing fuel is lost, the vicinity of the injection hole becomes high due to the radiant heat from the combustion chamber. As a result, the fuel or the like is carbonized in the nozzle hole and is deposited as a deposit.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a control device for an internal combustion engine that can reliably suppress deposit accumulation in a nozzle hole of a fuel injector. .

In order to achieve the above object, a first invention is a control device for an internal combustion engine,
A plurality of intake ports and intake valves provided per cylinder of the internal combustion engine;
A fuel injector provided for each of the plurality of intake ports of the same cylinder;
A communicating portion for communicating the plurality of intake ports of the same cylinder with each other in a downstream region of a fuel injection position of the fuel injector;
A shut-off valve arranged upstream of the fuel injection position of the fuel injector of at least one intake port of the plurality of intake ports of the same cylinder, and capable of shutting off the intake port;
Valve stop means capable of stopping an intake valve corresponding to at least one intake port other than the intake port with a cutoff valve provided with the cutoff valve among the plurality of intake ports of the same cylinder in a closed state;
The fuel in the intake port corresponding to the stopped intake valve when performing the partial valve stop operation of operating the internal combustion engine by stopping a part of the plurality of intake valves of the same cylinder by the valve stop means Partial valve stop operation means for stopping fuel injection from the injector, closing the shutoff valve, and injecting fuel only from the fuel injector of the intake port with the shutoff valve;
It is characterized by providing.

The second invention is the first invention, wherein
The partial valve stop operation is performed in an operation region where the engine rotation speed is lower than a predetermined value.

  According to the first aspect of the present invention, during the partial valve stop operation, the fresh air is circulated through the intake port of the fuel injector in which the fuel injection is stopped, so that the vicinity of the nozzle hole of the fuel injector in which the fuel injection is stopped is fresh. Can be cooled by. For this reason, since it can suppress that the vicinity of the nozzle hole of the fuel injector which stopped the fuel injection becomes high temperature by the radiant heat from a combustion chamber, it can suppress reliably that a deposit accumulates in a nozzle hole.

  According to the second aspect of the present invention, combustion in the region can be improved by performing the partial valve stop operation in the operation region where the engine rotation speed is lower than the predetermined value.

It is a figure for demonstrating the system configuration | structure of Embodiment 1 of this invention. It is a figure for demonstrating the system configuration | structure of Embodiment 1 of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is common in each figure, and the overlapping description is abbreviate | omitted.

Embodiment 1 FIG.
1 and 2 are diagrams each showing a system configuration according to the first embodiment of the present invention. As shown in these drawings, the system of this embodiment includes an internal combustion engine 10 mounted on a vehicle or the like. In these drawings, one of the plurality of cylinders 12 included in the internal combustion engine 10 is shown, but the number of cylinders and the cylinder arrangement are not particularly limited in the present invention. FIG. 1 shows a cross-sectional view as viewed from a direction parallel to the crankshaft of the internal combustion engine 10, and FIG. 2 shows a schematic view of the cylinder 12 as viewed from above.

  Each cylinder 12 is provided with intake valves 14 a and 14 b, an exhaust valve 16, and a spark plug 18. In addition, intake ports 22 a and 22 b and an exhaust port 24 communicate with the combustion chamber 20 of each cylinder 12. Each cylinder 12 is provided with fuel injectors (fuel injection valves) 26a and 26b for injecting fuel into the intake ports 22a and 22b.

  As shown in FIG. 2, in the internal combustion engine 10 of this embodiment, two intake valves 14a and 14b are provided per cylinder, and two intake ports 22a and 22b are provided correspondingly. Yes. A fuel injector 26a for injecting fuel into the intake port 22a and a fuel injector 26b for injecting fuel into the intake port 22b are provided. A partition wall 28 is formed between the intake port 22a and the intake port 22b. At a position where the partition wall 28 is located, the intake port 22a and the intake port 22b are independent of each other. On the other hand, on the downstream side of the fuel injection positions (positions of the tip injection holes) of the fuel injectors 26a and 26b, a portion without the partition wall 28, that is, a communication portion 30 where the intake port 22a and the intake port 22b communicate with each other is provided. It has been.

  A shutoff valve 32 capable of shutting off the intake port 22a is provided upstream of the fuel injection position of the fuel injector 26a of the one intake port 22a. The shut-off valve 32 can be opened and closed by being driven by an actuator 34.

  As shown in FIG. 1, the system of this embodiment further includes a crank angle sensor 36, an air flow meter 38, an accelerator opening sensor 40, a variable valve operating device 42, and an ECU (Electronic Control Unit) as a control device. ) 50. Various sensors and actuators including those described above are electrically connected to the ECU 50.

  The ECU 50 controls the operation by detecting the engine operation information by each sensor and driving each actuator based on the detection result. For example, an accelerator pedal operation amount (accelerator opening) by the driver of the vehicle is detected by the accelerator opening sensor 40, and an intake air amount control means (for example, a throttle valve) (not shown) is controlled based on the detection result. Further, the engine speed and the crank angle are detected based on the output of the crank angle sensor 36, and the intake air amount is detected by the air flow meter 38. Then, the fuel injection amount is calculated based on the intake air amount, the engine rotational speed, etc., and after determining the fuel injection timing, ignition timing, etc. based on the crank angle, the fuel injection control and ignition control are executed.

  The variable valve operating device 42 has a function of executing a valve stop for stopping only the intake valve 14b in the closed state among the two intake valves 14a and 14b. The variable valve device 42 may be configured to selectively switch between a state in which the intake valve 14b is opened and closed and a state in which the intake valve 14b is stopped, or the lift amount (working angle) of the intake valve 14 may be used. ) May be continuously changed to zero. The variable valve operating device 42 may have a function of changing the valve opening characteristic of the other intake valve 14a. As such a variable valve operating apparatus 42, those having various known structures can be adopted, and therefore, detailed description of the structure is omitted here.

  When the intake valve 14b is stopped by the variable valve device 42, fresh air flows into the cylinder only from the intake valve 14a. As a result, it is possible to form a stronger swirl flow (swirl) in the cylinder as compared with the case where fresh air is introduced from both intake valves 14a and 14b. Accordingly, by performing an operation (hereinafter referred to as “one-valve stop operation”) in which the variable valve device 42 stops the intake valve 14b in an operation state in which combustion needs to be improved by the swirling flow in the cylinder. Combustion can be improved. In the present embodiment, the ECU 50 performs control so that the one-valve stop operation is performed in an operation region where the engine speed is lower than a predetermined value. When the engine speed is low, the piston speed is low, and the flow rate of fresh air (air mixture) flowing into the cylinder is small, so that mixing is insufficient and combustion tends to deteriorate. On the other hand, mixing is strengthened and combustion can be improved by generating a strong swirling flow by performing a single valve stop operation in a region where the engine rotational speed is low. It should be noted that the engine rotational speed (the above-mentioned predetermined value) serving as a boundary between the normal operation for operating both the intake valves 14a and 14b and the one-valve stop operation does not necessarily have to be constant, and can be changed according to the engine load or the like. May be.

  In a normal operation in which both the intake valves 14a and 14b are operated, the ECU 50 opens the shutoff valve 32 and controls to inject fuel from both the fuel injectors 26a and 26b.

  On the other hand, in the single valve stop operation, the ECU 50 controls as follows. FIG. 2 shows a state in the single valve stop operation. As shown in FIG. 2, in the one-valve stop operation, the fuel injection from the fuel injector 26b on the intake port 22b side corresponding to the stopped intake valve 14b is stopped, and the corresponding intake valve 14a is operated. Fuel is injected only from the fuel injector 26a on the intake port 22a side. Further, the shutoff valve 32 is closed.

  When the shutoff valve 32 is closed, the flow of fresh air from the upstream side of the fuel injection position of the fuel injector 26a to the intake port 22a is blocked. For this reason, fresh air flows into the intake port 22b from the upstream side of the fuel injection position of the fuel injector 26b where fuel injection is stopped, passes through the communication portion 30, and moves to the intake port 22a. Inhaled. That is, fresh air is introduced into the cylinder through a path indicated by a curve with an arrow in FIG.

  In the present embodiment, the following effects can be obtained by performing the one-valve stop operation by the method described above. If the fuel is injected from both the fuel injectors 26a and 26b during the one-valve stop operation, the fuel injected from the stopped fuel injector 26b on the intake valve 14b side accumulates in the intake port 22b. easy. For this reason, the amount of fuel flowing into the cylinder shifts and the in-cylinder air-fuel ratio is disturbed. As a result, emission and drivability are deteriorated. Further, even when the number of fuel injectors per cylinder is one and the fuel injected from one fuel injector is distributed to two intake ports as in a conventional internal combustion engine. Since fuel accumulates in the intake port on the intake valve side that is stopped, there is a problem similar to the above. On the other hand, according to the present embodiment, since the fuel injection from the fuel injector 26b on the intake valve 14b side that is stopped is stopped, it is possible to reliably prevent fuel from accumulating in the intake port 22b. it can. Therefore, the cylinder air-fuel ratio can be accurately controlled.

  However, when the fuel injection from the stopped fuel injector 26b on the intake valve 14b side is simply stopped, another problem such as the following occurs. The vicinity of the nozzle holes at the tips of the fuel injectors 26 a and 26 b receive radiant heat from the combustion chamber 20. In the fuel injector 26a injecting the fuel, the temperature rise near the injection hole is suppressed by the cooling effect by the fuel passing through the inside. On the other hand, in the fuel injector 26b in which the fuel injection is stopped, the cooling effect by the passing fuel is lost, so that the vicinity of the injection hole becomes high due to the radiant heat from the combustion chamber 20. As a result, fuel or the like is carbonized in the nozzle hole and easily deposits as a deposit. If the injection hole of the fuel injector 26b becomes narrow due to the deposit, there arises a problem that after the fuel injection is restarted, the injection amount decreases.

  On the other hand, in the one-valve stop operation of the present embodiment, by closing the shut-off valve 32, deposit accumulation in the injection hole of the fuel injector 26b that has stopped fuel injection can be reliably suppressed. The reason for this is as follows. As described above with reference to FIG. 2, by closing the shutoff valve 32 and shutting off the upstream side of the intake port 22a, the total amount of fresh air flowing into the cylinder 12 is first reduced to the fuel injector 26b that has stopped fuel injection. Into the intake port 22b. Thereafter, fresh air moves from the intake port 22b through the communication portion 30 to the intake port 22a, and is sucked into the cylinder from the intake valve 14a. Thus, by closing the shutoff valve 32, a large amount of fresh air flows in the vicinity of the fuel injection position (injection hole) of the fuel injector 26b where fuel injection has been stopped, so that the injection hole of the fuel injector 26b is caused by the fresh air. The vicinity is cooled and the temperature rise is suppressed. As a result, deposit accumulation in the injection hole of the fuel injector 26b can be reliably suppressed.

  In the present embodiment, the internal combustion engine 10 having two intake ports 22 per cylinder has been described as an example. However, in the present invention, the number of intake ports per cylinder may be three or more. .

  In the embodiment described above, the variable valve device 42 corresponds to the “valve stop means” in the first invention, and the one-valve stop operation corresponds to the “partial valve stop operation” in the first invention. Yes. Further, the “partial valve stop operation means” in the first aspect of the present invention is realized by the ECU 50 controlling the single valve stop operation as described above.

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 12 Cylinder 14a, 14b Intake valve 16 Exhaust valve 18 Spark plug 20 Combustion chamber 22a, 22b Intake port 24 Exhaust port 26a, 26b Fuel injector 28 Bulkhead 30 Communication part 32 Shut-off valve 34 Actuator 42 Variable valve apparatus 50 ECU

Claims (2)

A plurality of intake ports and intake valves provided per cylinder of the internal combustion engine;
A fuel injector provided for each of the plurality of intake ports of the same cylinder;
A communicating portion for communicating the plurality of intake ports of the same cylinder with each other in a downstream region of a fuel injection position of the fuel injector;
A shut-off valve arranged upstream of the fuel injection position of the fuel injector of at least one intake port of the plurality of intake ports of the same cylinder, and capable of shutting off the intake port;
Valve stop means capable of stopping an intake valve corresponding to at least one intake port other than the intake port with a cutoff valve provided with the cutoff valve among the plurality of intake ports of the same cylinder in a closed state;
The fuel in the intake port corresponding to the stopped intake valve when performing the partial valve stop operation of operating the internal combustion engine by stopping a part of the plurality of intake valves of the same cylinder by the valve stop means Partial valve stop operation means for stopping fuel injection from the injector, closing the shutoff valve, and injecting fuel only from the fuel injector of the intake port with the shutoff valve;
A control device for an internal combustion engine, comprising:   2. The control apparatus for an internal combustion engine according to claim 1, wherein the partial valve stop operation is performed in an operation region where the engine rotation speed is lower than a predetermined value.

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