JP2008095558A - Spark ignition type cylinder injection internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spark ignition type cylinder injection internal combustion engine suppressing an increase in the generation quantity of hydrocarbon and soot and causing no deterioration of startability by avoiding fuel injection interfering with a piston and an intake valve without limiting an intake air quantity. <P>SOLUTION: Two or more fuel injection valves are arranged in a combustion chamber 15 at each combustion chamber, and at least one fuel injection valve is formed so that the center axis of the fuel injection of a fuel injection hole of the first fuel injection valve 41 inclines at an angle α of 0° to 90° to the ignition plug side from a cylinder horizontal plane h orthogonally intersecting a cylinder bore center axis. One of other fuel injection valves is formed so that the center axis of the fuel injection of a fuel injection hole of the second fuel injection valve 42 inclines at an angle β of 0° to 90° to the piston side from the cylinder horizontal plane orthogonally intersecting the cylinder bore center axis. The first fuel injection valve injecting toward the ignition plug, and the second fuel injection valve injecting toward the piston are selectively used at each combustion chamber. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a spark ignition type cylinder injection internal combustion engine used in a vehicle such as an automobile, and more particularly to a reciprocating type spark ignition type cylinder injection internal combustion engine in which fuel is directly injected into a combustion chamber by a fuel injection valve.

  As an internal combustion engine used in a vehicle such as an automobile, in a reciprocating spark ignition internal combustion engine having an intake port and an ignition plug in a combustion chamber ceiling facing a top surface of a piston provided in a cylinder bore so as to be capable of reciprocating, A spark ignition type in-cylinder injection internal combustion engine (direct injection engine) in which fuel is directly injected into a combustion chamber by a fuel injection valve is known.

  The spark-ignition in-cylinder injection internal combustion engine has the advantage of improving fuel economy by stratified combustion with a lean air-fuel ratio, while the fuel (fuel spray) injected from the fuel injection valve is the surface of the intake valve umbrella when cold When the engine cools down, the fuel adhering to the surface does not vaporize well, and the amount of HC / soot generated increases and the cold startability deteriorates. Concerned.

  For example, when the piston is near top dead center (TDC), fuel injection may interfere with the top surface of the piston, and when the intake valve is at its maximum open, the surface of the umbrella portion of the intake valve There is a possibility that the fuel injection interferes with this. The fuel that has interfered with the piston and the intake valve is difficult to be vaporized and atomized particularly during cold operation, which may lead to deterioration of combustion and, as a result, startability may be deteriorated. In addition, some of the fuel that has interfered with the piston and the intake valve becomes HC / soot and is discharged from the exhaust pipe to pollute the atmosphere.

  As one of the solutions, it has been proposed to prevent interference of fuel injection to the intake valve by reducing the intake valve lift amount during cold start (for example, Patent Document 1).

JP 2003-106195 A

  However, if the intake valve lift amount is reduced in order to prevent the fuel injection interference with the intake valve, the intake air amount is limited, and there is a concern that the drivability deteriorates, the misfire occurs, and the startability deteriorates.

  The present invention has been made in view of the above-mentioned problems, and the object of the present invention is to prevent the fuel injection from interfering with the piston and the intake valve without restricting the intake air amount, and to reduce the HC / soot. It is an object of the present invention to provide a spark ignition type in-cylinder injection internal combustion engine that suppresses an increase in the generation amount of the engine and does not cause deterioration in startability.

  In order to achieve the above-mentioned object, a spark ignition type cylinder injection internal combustion engine according to the present invention has an intake port and a spark plug in a ceiling portion of a combustion chamber facing a top surface of a piston provided in a cylinder bore so as to be able to reciprocate. A spark ignition type cylinder injection internal combustion engine in which fuel is directly injected into the combustion chamber by a fuel injection valve, wherein two or more fuel injection valves are arranged for each combustion chamber, and at least one of the fuel injection valves One fuel injection valve is a first fuel injection valve. From the cylinder horizontal plane in which the central axis of the fuel injection of at least one fuel injection hole of the first fuel injection valve intersects the cylinder bore central axis at right angles, the ignition plug And at least one of the fuel injectors is a second fuel injector, and the second fuel injector is a second fuel injector. Have The central axis of fuel injection of the at least one fuel injection hole is inclined at an angle of 0 ° or more and 90 ° or less to the piston side from a cylinder horizontal plane that intersects the cylinder bore central axis at right angles.

  The spark ignition type cylinder injection internal combustion engine according to the present invention individually controls the fuel injection operations of the first fuel injection valve and the second fuel injection valve provided for each combustion chamber independently of each other. It has fuel injection control means.

  In the spark ignition type cylinder injection internal combustion engine according to the present invention, the fuel injection control means includes a fuel injection timing and a fuel injection amount of the first fuel injection valve, and a fuel injection timing and a fuel injection amount by the second fuel injection valve. Are controlled independently of each other.

  The fuel injection control means in the spark ignition type cylinder injection internal combustion engine according to the present invention prohibits fuel injection by the first fuel injection valve in a predetermined section on the maximum opening side of the intake valve that opens and closes the intake port. .

  The fuel injection control means in the spark ignition type cylinder injection internal combustion engine according to the present invention prohibits fuel injection by the second fuel injection valve in a predetermined section including the piston top dead center position.

  In the spark-ignition in-cylinder injection internal combustion engine according to the present invention, the fuel injection control means restricts part or all of fuel injection by one of the first fuel injection valve and the second fuel injection valve. In this case, complementary control is performed in which the fuel injection by the other fuel injection valve compensates for the shortage of the fuel injection amount due to the restriction.

  According to the spark ignition type cylinder injection internal combustion engine of the present invention, the first fuel injection valve for spark plug direction injection and the second fuel injection valve for piston direction injection are provided for each combustion chamber. By prohibiting the operation of the fuel injection valve that injects fuel in the direction of interference in a section where there is a possibility of interference between the intake valve and the piston and the fuel injection, it is possible to reliably prevent the fuel injection interference. As a result, an increase in the amount of HC / soot generated can be suppressed, and startability deterioration can be prevented.

  In this spark ignition type in-cylinder injection internal combustion engine, as compared with the case where the intake valve lift amount is made variable, only a fuel injection valve is added, the mechanism is simple, and the reliability is improved.

Hereinafter, an embodiment of a spark ignition type cylinder injection internal combustion engine according to the present invention will be described in detail with reference to the drawings.
FIG. 1 shows the overall configuration of a spark ignition type cylinder injection internal combustion engine according to an embodiment of the present invention. The internal combustion engine has a cylinder block 11, and a plurality of cylinder bores 12 (only one is shown in FIG. 1) is formed in the cylinder block 11. Each cylinder bore 12 is provided with a piston 13 which can reciprocate in the direction of the cylinder bore central axis Cb (see FIG. 2). The piston 13 defines a combustion chamber 15 in the cylinder bore 12 above the piston top surface 14 as viewed in FIG.

  An intake port 17 and an exhaust port 18 are opened in the combustion chamber ceiling 16 facing the piston top surface 14. The intake port 17 is opened and closed by a poppet-type intake valve 20 driven by an intake cam 19. The exhaust port 18 is opened and closed by a poppet type exhaust valve 22 driven by an exhaust cam 21. Note that the intake valve 20 can also be an intake valve timing variable device, if necessary.

  The intake air is measured for flow rate by an air flow meter (air flow sensor) 26 which is one of the operating state measuring means of the internal combustion engine, enters a collector 28 through a throttle valve 27 for controlling the intake air flow rate, and an intake pipe 29 Are distributed to the combustion chambers 15 and guided into the combustion chambers 15 through the intake ports 17.

  A throttle sensor 30, which is one of internal combustion engine operating state measuring means for detecting the opening degree, is attached to the arrangement portion of the throttle valve 27. A cam angle sensor 31 that detects the rotation angle of the intake cam 19 is attached to the arrangement portion of the intake cam 19. An ignition plug 23 and an ignition coil device 24 are attached to the combustion chamber ceiling 16.

  A water temperature sensor 25 that detects the coolant temperature is attached to the cylinder block 11, and a first fuel injection valve 41 and a second fuel injection valve 42 are attached to each fuel chamber 15. . The first fuel injection valve 41 and the second fuel injection valve 42 each have at least one fuel injection hole (not shown) and are attached in different directions. Details of this will be described later.

  The fuel is supplied from a fuel tank (not shown) and pressurized by a fuel pump (not shown), and then passes through the common rail 43 and is disposed in each combustion chamber 15. It is pumped to the second fuel injection valve 42. In the present embodiment, the common rail 43 is shared by the first fuel injection valve 41 and the second fuel injection valve 42, but the first fuel injection valve 41 and the second fuel are respectively used as separate common rails. The fuel pressure may be different from that of the injection valve 42.

The fuel pressure-fed to the first fuel injection valve 41 and the second fuel injection valve 42 is individually injected into the combustion chamber 15 from each of the first fuel injection valve 41 and the second fuel injection valve 42. Is done. The fuel injected into the combustion chamber 15 is mixed with the intake air and ignited by the spark plugs 23 arranged in each combustion chamber 15.
Fuel injection by the first fuel injection valve 41 and the second fuel injection valve 42 is controlled by an engine control unit (ECU) 50.

  The ECU 50 is a control device including a microcomputer and serves as fuel injection control means. The ECU 50 receives sensor signals from each of the water temperature sensor 25, the airflow sensor 26, the throttle sensor 30, the cam angle sensor 31, and the crank angle sensor (a sensor that detects the rotation angle of the crankshaft of the internal combustion engine) 32, and the airflow sensor 26 detects the intake air amount from the sensor signal of 26, detects (calculates) the engine speed from the sensor signal of the crank angle sensor, detects the opening of the throttle valve 27 from the sensor signal of the throttle sensor 30, and detects the cam angle sensor 31. The intake valve position is detected from the sensor signal of the crank angle sensor 32 and the sensor signal of the crank angle sensor 32, the coolant temperature is detected from the sensor signal of the water temperature sensor 25, and the first fuel injection valve 41, the first The fuel injection timing and fuel injection amount of the second fuel injection valve 42 are calculated, and the first fuel injection valve 41 and the second fuel injection valve 42 To control the fuel injection operations.

  Here, the ECU 50 individually controls the fuel injection operations of the first fuel injection valve 41 and the second fuel injection valve 42 provided for each combustion chamber 15 independently of each other. Details of this will also be described later.

  Details of the first fuel injection valve 41 and the second fuel injection valve 42 will be described with reference to FIGS.

  FIG. 2 is a vertical cross-sectional view of the combustion chamber. Here, the trajectory on the vertical plane of the fuel injection from the first fuel injection valve 41 and the second fuel injection valve 42 will be described. The vertical surface is a vertical surface including the cylinder bore central axis Cb, and is a surface formed by the paper surface of FIG.

  The injection trajectory of the fuel injected from the fuel injection hole (not shown) of the first fuel injection valve 41 is indicated by symbol A. The fuel injection center axis Ac of the fuel injection locus A is inclined at an angle α of 0 ° or more and 90 ° or less from the cylinder horizontal plane h that intersects the cylinder bore center axis Cb at a right angle when viewed in the vertical plane. is doing. The angle α is an angle formed by the cylinder horizontal plane h and the fuel injection center axis Ac on the vertical plane.

  Accordingly, the first fuel injection valve 41 performs fuel injection toward the upper side from the cylinder horizontal plane h. This is called the spark plug direction.

  The injection trajectory of the fuel injected from the fuel injection hole (not shown) of the second fuel injection valve 42 is indicated by symbol B. The fuel injection center axis Bc of the fuel injection trajectory B is at an angle β of 0 ° or more and 90 ° or less from the cylinder horizontal plane h that intersects the cylinder bore center axis Cb at a right angle when viewed from the vertical plane. Inclined. The angle β is an angle formed by the cylinder horizontal plane h and the fuel injection central axis Bc in the vertical plane.

  Thus, the second fuel injection valve 42 performs fuel injection toward the lower side than the cylinder horizontal plane h. This is called piston direction injection.

  FIG. 3 is a cross-sectional view of the combustion chamber as viewed from the spark plug direction. Since there are two fuel injection valves for each combustion chamber 15, space constraints are severe. As a countermeasure, the center axis C41 of the first fuel injection valve 41 and the center axis C42 of the second fuel injection valve 42 are shown in the drawing so as not to intersect the cylinder bore center axis Cb when viewed in the cylinder horizontal plane h. As described above, the mounting directions (arrangements) of the first fuel injection valve 41 and the second fuel injection valve 42 are set.

  Thus, when the center axis C41 of the first fuel injection valve 41 and the center axis C42 of the second fuel injection valve 42 are set, the fuel injection is biased in the combustion chamber 15. As a countermeasure, a fuel injection hole (not shown) of the first fuel injection valve 41 and a fuel injection hole (not shown) of the second fuel injection valve 42 are each viewed from the cylinder horizontal plane h, with the central axis C41. , C42 is opened in a direction deflected, and as shown in FIG. 4, the fuel injection center axis Ac of the first fuel injection valve 41 and the fuel injection center of the second fuel injection valve 42 Each axis Bc intersects the cylinder bore central axis Cb.

  Next, the fuel injection control of the first fuel injection valve 41 and the second fuel injection valve 42 by the ECU 50 will be described with reference to the flowchart shown in FIG.

  First, sensor information is taken in from each sensor, and the engine water temperature, the engine speed, and the central angle position (intake valve position) of the intake valve are detected (step S1). Here, the center angle position of the intake valve 20 is defined as a crank angle position at which the intake valve opening at the variable timing is maximized.

  Next, a piston direction injection prohibited section and a spark plug direction injection prohibited section are calculated from the engine water temperature, the engine speed, and the central angle position of the intake valve (step S2).

  Spark plug direction injection is fuel injection from the first fuel injection valve 41, and piston direction injection is fuel injection from the second fuel injection valve 42.

When the crank angle position of the exhaust TDC is −360 ° C. A BTDC and the crank angle position of the compression TDC is defined as 0 ° C. A BTDC, the spark plug direction injection prohibition section of the first fuel injection valve 41 is as follows: Set.
(A1) When the engine water temperature is 20 ° C. or less and the engine speed is 2000 r / min or less, the spark plug direction injection prohibited section = the central angle position of the intake valve 20 is within ± 40 ° C.
(A2) When the engine water temperature is 21 ° C. or more and the engine speed is 2000 r / min or less, the spark plug direction injection prohibition section = the center angle position of the intake valve 20 is within ± 30 ° A.
(A3) In cases other than the above, the spark plug direction injection prohibited section = the center angle position of the intake valve 20 is within ± 20 ° C.

  At the central angle position of the intake valve 20, the intake valve opening becomes maximum, and fuel spray injected in the spark plug direction at this time easily interferes with the intake valve 20. Therefore, in a predetermined section on the maximum opening side of the intake valve 20. The fuel injection in the spark plug direction by the first fuel injection valve 41 is prohibited. When the engine water temperature is low, the fuel adhering to the intake valve 20 is difficult to vaporize, so the injection prohibition section in the spark plug direction by the first fuel injection valve 41 is lengthened. Even when the engine speed is low, the intake speed is slow and the fuel tends to adhere to the intake valve 20, so that the injection prohibited section in the spark plug direction by the first fuel injection valve 41 is lengthened.

The piston direction injection prohibition section of the second fuel injection valve 42 is set as follows.
(B1) When the engine water temperature is 20 ° C. or less, the piston direction injection prohibited section = 360 ° C. A within BTDC ± 40 ° C. and 0 ° C. A within BTDC ± 40 ° C.
(B2) In cases other than the above, piston direction injection prohibited section = 360 ° C. A within BTDC ± 20 ° C. and 0 ° C. A within BTDC ± 20 ° C.

  That is, the vicinity of TDC is a state in which the piston 13 is closest to the first and second fuel injection valves 41 and 42. In this state, if fuel is injected in the piston direction, the fuel is likely to interfere with the piston top surface 14, so that the fuel injection in the piston direction by the second fuel injection valve 42 is prohibited in a predetermined section including the piston top dead center position. To do. When the engine water temperature is low, the fuel adhering to the piston top surface 14 is difficult to vaporize, and therefore, the injection prohibition section in the piston direction by the second fuel injection valve 42 is lengthened.

  Next, the fuel injection end timing and the fuel injection period of each of the spark plug direction fuel injection and the piston direction fuel injection are calculated from the fuel injection end timing and the fuel injection period calculated in the same manner as in the conventional control (step S3).

  Here, the fuel injection in the spark plug direction by the first fuel injection valve 41 is calculated so as not to inject fuel in the spark plug direction injection prohibited section, and the fuel injection in the piston direction by the second fuel injection valve 42 is Calculation is performed so that fuel is not injected in the direction injection prohibited section. When an injection prohibition section is set in at least one of the first fuel injection valve 41 and the second fuel injection valve 42 and a part or all of the fuel injection is restricted, the fuel shortage due to the injection prohibition section is reduced. The fuel injection end timing and the fuel injection period are set so as to perform complementary control supplemented by other fuel injection valves.

  Next, as an example, the operation under the following conditions will be described with reference to the timing chart of FIG. All the numerical values in the figure indicate crank angles when the exhaust TDC is 360 ° C. A BTDC and the compression TDC is 0 ° C. A BTDC.

(A) A first fuel injection valve 41 and a second fuel injection valve 42 are provided for each combustion chamber 15.
(B) It is assumed that the first fuel injection valve 41 and the second fuel injection valve 42 have the same fuel pressure and the same pulse width and the fuel injection amount is ½ as compared with the conventional one.
(C) Water temperature 0 ° C
(D) Engine speed 1800 r / min.
(E) The fuel injection end timing of the conventional control is 260 ° C. A BTDC
(F) Conventional control fuel injection period is 80 ° C
(G) The central angle position of the variable intake valve is 240 ° C A BTDC

  In this case, according to the condition (A1), the spark plug direction injection prohibited section = 280 to 200 ° C. A BTDC, and under the condition (B1), the piston direction injection prohibited section = 400 to 320 ° C. A BTDC and 40 to −40 ° C. A BTDC It becomes.

When the injection prohibition section is not considered, the fuel injection section is 340 to 260 ° C. A BTDC. Considering the injection prohibited section, the fuel injection section is calculated as follows.
Spark plug direction injection section = 370-280 ° C A BTDC
Piston direction injection section = 320-260 ° C A BTDC

  Thus, by setting the injection prohibition section, interference of fuel injection with respect to the intake valve 20 and the piston top surface 14 can be reliably prevented, and the amount of fuel adhering to the intake valve 20 and the piston top surface 14 is reduced. . As a result, an increase in the amount of HC / soot generated is suppressed, and startability deterioration is prevented.

  The start timing of the piston direction injection has a restriction of the piston direction injection prohibition section, and the end time has a restriction of the fuel injection end time of the conventional control, so the fuel injection section becomes short. The shortened amount is added to the spark plug direction injection section.

  As a result, when part or all of the fuel injection by the first fuel injection valve 41 or the second fuel injection valve 42 is restricted, the shortage of the fuel injection amount due to the restriction is reduced to the other fuel injection valve. When the fuel injection by the first fuel injection valve 41 is limited, the fuel injection by the second fuel injection valve 42 conversely causes the second fuel injection. When the fuel injection by the valve 42 is restricted, the fuel injection by the first fuel injection valve 41 is supplemented, and even if the fuel injection is restricted, the fuel injection amount is insufficient as a whole. There is no.

The figure which shows the whole structure of one Embodiment of the spark ignition type cylinder injection type internal combustion engine by this invention. 1 is a longitudinal sectional view of a combustion chamber of a spark ignition type cylinder injection internal combustion engine according to one embodiment. The combustion chamber transverse cross section which looked at the spark ignition type cylinder injection type internal combustion engine by one embodiment from the direction of a spark plug. The combustion chamber cross-sectional view which looked at the spark ignition type in-cylinder internal combustion engine according to one embodiment from the direction of the spark plug. The flowchart which shows an example of the control flow of the spark ignition type cylinder injection type internal combustion engine by one Embodiment. The timing chart of the fuel injection valve injection timing by the spark ignition type cylinder injection type internal combustion engine by one embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Cylinder block 12 Cylinder bore 13 Piston 14 Piston top surface 15 Combustion chamber 16 Combustion chamber ceiling 17 Intake port 18 Exhaust port 19 Intake cam 20 Intake valve 21 Exhaust cam 22 Exhaust valve 23 Spark plug 24 Ignition coil device 25 Water temperature sensor 26 Air flow rate Meter (Air flow sensor)
27 Throttle valve 28 Collector 29 Intake pipe 30 Throttle sensor 31 Cam angle sensor 32 Crank angle sensor 41 First fuel injection valve 42 Second fuel injection valve 50 Engine control unit (ECU)

Claims (6)

A spark-ignition in-cylinder injection internal combustion engine having an intake port and an ignition plug at a ceiling portion of a combustion chamber facing a top surface of a piston provided in a cylinder bore so as to be able to reciprocate, and injecting fuel directly into the combustion chamber by a fuel injection valve Because
Two or more fuel injection valves are arranged for each combustion chamber,
At least one fuel injection valve of the fuel injection valves is a first fuel injection valve, and a fuel injection central axis of at least one fuel injection hole of the first fuel injection valve is a cylinder bore central axis. The cylinder is inclined at an angle of 0 ° or more and 90 ° or less from the horizontal plane of the cylinder that intersects at right angles to the spark plug side.
At least one other fuel injection valve of the fuel injection valves is a second fuel injection valve, and the central axis of fuel injection of at least one fuel injection hole of the second fuel injection valve is a cylinder bore. A spark ignition type in-cylinder injection internal combustion engine, which is inclined at an angle of 0 ° or more and 90 ° or less toward a piston side from a cylinder horizontal plane intersecting at right angles to a central axis.   It has fuel injection control means for controlling fuel injection operations of the first fuel injection valve and the second fuel injection valve provided for each combustion chamber independently of each other. The spark ignition type cylinder injection internal combustion engine according to claim 1.   The fuel injection control means controls the fuel injection timing and the fuel injection amount of the first fuel injection valve and the fuel injection timing and the fuel injection amount independently of each other by the second fuel injection valve. The spark ignition type cylinder injection internal combustion engine according to claim 2.   The fuel injection control means prohibits fuel injection by the first fuel injection valve in a predetermined section on the maximum valve opening side of an intake valve that opens and closes the intake port. Spark ignition type cylinder injection internal combustion engine.   The spark according to any one of claims 2 to 4, wherein the fuel injection control means prohibits fuel injection by the second fuel injection valve in a predetermined section including a piston top dead center position. Ignition type cylinder injection internal combustion engine.   When a part or all of the fuel injection by one fuel injection valve of the first fuel injection valve and the second fuel injection valve is restricted, the fuel injection control means is short of the fuel injection amount due to the restriction. 6. The spark ignition type in-cylinder injection internal combustion engine according to any one of claims 1 to 5, wherein complementary control is performed in which fuel injection by the other fuel injection valve is compensated for.

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