JP4752549B2 - Deposit cleaning device for internal combustion engine - Google Patents

Description

  The present invention relates to a deposit cleaning apparatus for preventing deposit accumulation on the back of an intake valve umbrella in an internal combustion engine.

In Patent Document 1, in an internal combustion engine including a direct injection injector that directly injects fuel into a combustion chamber (cylinder) and a port injector that injects fuel into an intake port, the deposit deposited on the direct injection injector should be burned down. At times, fuel injection is performed by the port injector, and the combustion temperature is raised by reducing the cylinder operation or by increasing the fuel injection amount and the exhaust valve opening timing, etc., and the deposit deposit on the direct injection injector is surely burned down. Yes.
JP-A-2005-090457

However, if deposits adhere to or accumulate on the back of the intake valve umbrella due to spray interference with the intake valve or exhaust air blowback during operation with a direct injection injector, this causes a reduction in output due to ventilation resistance. Can not be burned down even if the combustion temperature is raised.
The present invention has been made in view of the above circumstances, and it is an object of the present invention to reliably remove deposits adhering to the back of an intake valve umbrella by washing.

For this reason, in the present invention, the deposit is attached to the back of the umbrella of the intake valve, provided with a spray angle varying means for setting the port injector to inject fuel toward the intake valve and making the spray angle of the port injector variable. Is switched from fuel injection by the direct injection injector to fuel injection by the port injector, the injection timing of the port injector at this time is set during the compression stroke after the intake valve is closed , and the spray angle The variable angle means is used to reduce the spray angle of the port injector .

  According to the present invention, when the deposit adhered to the back of the umbrella of the intake valve is to be cleaned, the deposit can be cleaned and removed by the fuel by injecting the fuel toward the intake valve by the port injector. In particular, by setting the injection timing of the port injector at this time during the compression stroke after the intake valve is closed, a sufficient fuel permeation time can be secured, and the intake valve opens and enters the cylinder. When the inflow of the intake air is started, the deposit is relatively easily removed.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a configuration diagram around a combustion chamber of an internal combustion engine (direct injection gasoline engine).
A combustion chamber 4 is defined by the cylinder block 1, the cylinder head 2 and the piston 3. In the combustion chamber 4, an ignition plug 5 is disposed at the upper center, and an intake valve 6 and an exhaust valve 7 are provided so as to sandwich the ignition plug 5. The combustion chamber 4 is connected to the intake port 8 via the intake valve 6 and is connected to the exhaust port 9 via the exhaust valve 7.

Here, a direct injection injector 10 that directly injects fuel into the combustion chamber 4 is provided so as to face the combustion chamber 4.
The direct injection injector 10 can form a homogeneous air-fuel mixture in the entire area of the combustion chamber 4 by injecting it in the intake stroke. Is possible. Further, by injecting in the compression stroke, the air-fuel mixture can be concentrated around the spark plug 5 in the combustion chamber 4, and by igniting and burning the stratified air-fuel mixture by the spark plug 5, stratified combustion Is possible.

Further, a port injector 12 that is attached to the intake manifold (11 in FIG. 2) and injects fuel into the intake port 8 is provided.
FIG. 2 is a detailed view of the port injector 12.
The port injector 12 normally forms an air-fuel mixture in the intake port 8 by being injected in the exhaust stroke, and is sucked into the combustion chamber 4 together with the opening of the intake valve 6 to be homogeneous in the combustion chamber 4. It can be used to form a mixture.

In the present invention, the port injector 12 is used for cleaning the deposit attached to the back of the umbrella of the intake valve 6.
For this reason, the port injector 12 (spray center line C) is directed toward the shaft portion (stem portion) above the umbrella back (near the umbrella back) of the intake valve 6, as shown in FIG. This is because, as shown in FIG. 3, the connecting portion between the umbrella back 6a of the intake valve 6 and the shaft portion 6b becomes a concave portion, and deposits tend to accumulate here, so that it aims to enter under the deposit from above. is there.

Next, the operation will be described.
As shown in FIG. 1 (A), during operation of the direct injection injector 10, as shown in FIG. 1 (B), the back of the umbrella of the intake valve 6 is caused by the interference of the spray to the intake valve 6 and the blowback of exhaust gas. Deposits and deposits on the surface.
Therefore, in order to periodically clean the deposit adhered to the back of the umbrella of the intake valve 6, as shown in FIG. 1C, the fuel injection by the direct injection injector 10 is switched to the fuel injection by the port injector 12, The injector 12 injects toward the shaft part above the umbrella back of the intake valve 6 (near the umbrella back), thereby cleaning and removing deposits adhering to the back of the intake valve 6. As a result, it is possible to prevent a decrease in output due to the airflow resistance and the like, and it is not necessary to increase the fuel injection amount.

FIG. 4 shows the relationship between the injection timing for washing and the valve timing, and the injection timing is set during the compression stroke after the intake valve is closed. Specifically, the injection start timing is set immediately after the intake valve is closed (almost simultaneously with the valve closing).
According to this, it is possible to sufficiently ensure the permeation time of the fuel into the deposit after the fuel injection and before the intake valve 6 is opened, and the adhesion force of the deposit can be weakened by the permeation. Therefore, when the intake valve 6 is opened and the inflow of intake air into the cylinder is started, the deposit can be removed relatively easily by the flow of intake air.

Further, the spray center line C is set at the shaft portion above the umbrella back of the intake valve 6 for the spray target position of the port injector 12. As a result, most of the fuel is injected above the place where it is most likely to deposit, and enters under the deposit, so that a sufficient cleaning effect can be obtained.
The spray angle of the port injector 12 is set to be narrower than that during normal fuel injection. As a result, more fuel can be applied to the intake valve 6 to be used for deposit cleaning, and the deposit can be cleaned and removed in a short period of time.

  Therefore, when both normal fuel injection and cleaning fuel injection are used, a means for changing the spray angle of the port injector 12 is provided, and the spray angle may be reduced during deposit cleaning. As means for making the spray angle variable, a means (pressure regulator) capable of changing the pressure (fuel pressure) of the fuel supplied to the injector 12 can be implemented relatively easily. For example, when the fuel pressure is increased and the atomization of the injected fuel advances and the spray angle widens, the spray angle can be narrowed as a liquid injected fuel by reducing the fuel pressure.

Further, when the deposit cleaning of the back of the umbrella of the intake valve 6 is performed periodically by switching from the fuel injection by the direct injection injector 10 to the fuel injection by the port injector 12, the start determination of the deposit cleaning (determination of the deposit cleaning timing) Can be done as follows.
The determination of the deposit cleaning time is made based on whether or not a period corresponding to deposit accumulation has elapsed based on travel distance, operating time, engine rotation history, and the like.

  Moreover, about an operation state, it is good to wash | clean by switching to intake port injection in medium rotation and medium load (for example, 60-100 km / h). This is because, with medium rotation and medium load, it is difficult to produce the fuel consumption and output disadvantages of direct injection and the amount of fuel is relatively large, so that it can be cleaned in a short time. On the other hand, the idle fuel consumption is low because the amount of fuel is small, and direct injection is better when output is required, such as during rapid acceleration. desirable.

The end determination after the start of cleaning may be performed by setting in advance the time required for cleaning / removal and whether or not the time has elapsed.
In addition, fuel injection at the time of cleaning may be performed in a plurality of times while the intake valve is closed.

Configuration diagram around the combustion chamber of the engine Detailed view of port injector Explanatory drawing of target position during deposit cleaning Diagram showing the relationship between the injection timing for cleaning and the valve timing

Explanation of symbols

4 Combustion chamber 5 Spark plug 6 Intake valve 8 Intake port 10 Direct injection injector 12 Port injector

Claims (3)

In an internal combustion engine comprising a direct injection injector that injects fuel directly into a combustion chamber and a port injector that injects fuel into an intake port,
The port injector is set to inject fuel toward the intake valve,
A spray angle varying means for varying the spray angle of the port injector;
When the deposit adhering to the back of the intake valve umbrella should be cleaned, the fuel injection by the direct injection injector is switched to the fuel injection by the port injector. The injection timing of the port injector at this time is the compression stroke after the intake valve is closed. A deposit cleaning apparatus for an internal combustion engine , wherein the spray angle of the port injector is reduced using the spray angle varying means .   2. The deposit cleaning apparatus for an internal combustion engine according to claim 1, wherein the port injector is directed toward a shaft portion above the umbrella back of the intake valve. In an internal combustion engine comprising a direct injection injector that injects fuel directly into a combustion chamber and a port injector that injects fuel into an intake port,
The port injector is set to inject fuel toward the intake valve,
A spray angle varying means for varying the spray angle of the port injector;
When the deposit adhered to the back of the intake valve umbrella is to be cleaned, the fuel injection by the direct injection injector is switched to the fuel injection by the port injector, and the spray angle of the port injector is reduced by using the spray angle varying means. A deposit cleaning apparatus for an internal combustion engine.

Images