WO2004109082A1

WO2004109082A1 - Internal combustion engine with variable intake valve

Info

Publication number: WO2004109082A1
Application number: PCT/JP2003/006996
Authority: WO
Inventors: Yuusuke Kihara; Yoshihiro Sukegawa; Toshiharu Nogi
Original assignee: Hitachi, Ltd.
Priority date: 2003-06-03
Filing date: 2003-06-03
Publication date: 2004-12-16
Also published as: JPWO2004109082A1

Abstract

An internal combustion engine provided with a variable intake valve in which unburnt fuel can be reduced by preventing adhesion of fuel to the wall face thereby making it possible to atomize fuel spray. An engine control unit (20) sets the open period of an intake valve (7) in the intake stroke at the time of low load operation and controls the intake air volume by controlling the open interval and the lift of the intake valve (7). When the fuel injection period of a fuel injection valve (31) is longer than the open period of the intake valve (7), the engine control unit (20) controls the fuel injection period of a fuel injection valve (11) to be shorter than the open period of the intake valve (7) by increasing the fuel injection amount per unit time of the fuel injection valve having a variable injection rate mechanism (32) capable of altering the fuel injection rate.

Description

Internal combustion engine with variable intake valve

The present invention relates to an internal combustion engine provided with a variable intake valve capable of changing an opening timing, an opening period, and a lift amount of an intake valve, and in particular, to an internal combustion engine provided with a variable intake valve suitable for being applied to control at a cold start. About the institution.

Akira Background technology

book

In a conventional internal combustion engine, the purification capacity is low in an inactive state where the catalyst temperature is low at the time of cold start, and unburned fuel discharged from the engine is directly discharged into the atmosphere, which causes a deterioration in the environment. Therefore, it is necessary to minimize this unburned fuel to reduce emissions.

However, in the case of a port injection engine that injects fuel during the exhaust stroke, most of the injected fuel adheres to the intake pipes and intake valves.However, when cold, there is almost no heat received from the wall, and fuel vaporization is poor. However, the fuel adhering to the wall surface and flowing into the combustion chamber as a wall flow is diluted with engine oil, is insufficiently vaporized, and is discharged as unburned fuel. Thus, for example, as described in Japanese Patent Application Laid-Open No. 2002-224727, the opening timing of the intake valve is retarded at the time of starting when the water temperature is 50 ° C or lower, and the flow rate of the intake air is reduced. The fuel injection timing is set so that the fuel reaches the intake valve when the intake valve opens, and the amount of fuel adhering to the intake pipe is reduced by the air flow generated when the intake valve opens. ing. Disclosure of the invention

However, according to the technique described in Japanese Patent Application Laid-Open No. 2002-224727, when the fuel injection timing is longer than the opening period of the intake valve, a part of the fuel enters the combustion chamber. If the liquid does not enter, it adheres to the intake valve and forms a liquid film, causing a wall flow and deteriorating the exhaust.In addition, since there is no atomization due to the shear force generated between the gas and the air flow, the vaporization is poor and uneven. There was a problem that a high quality air-fuel mixture was formed and the flammability deteriorated.

An object of the present invention is to provide an internal combustion engine equipped with a variable intake valve capable of preventing fuel from adhering to a wall surface, enabling atomization of fuel spray, and reducing unburned fuel.

(1) In order to achieve the above object, the present invention relates to an internal combustion engine having a variable intake valve capable of changing the opening timing, the opening period, and the amount of lift of an intake valve. When the opening period of the intake valve is longer than the opening period of the intake valve, the fuel injection amount per unit time or the intake air amount is changed so that the fuel injection period of the fuel injection valve is controlled to be shorter than the opening period of the intake valve. This is provided with control means. With this configuration, the fuel injection period of the fuel injection valve is shorter than the opening period of the intake valve, preventing fuel from adhering to the wall surface, enabling atomization of fuel spray, and reducing unburned fuel. .

(2) In the above (1), preferably, at the time of low load operation, the control means sets an opening timing of the intake valve to an intake stroke, and controls an opening period and a lift amount of the intake valve. Adjusting the intake air amount; and further increasing the fuel injection amount per unit time of the fuel injection valve provided with the injection rate variable mechanism capable of changing the fuel injection rate. The fuel injection period is controlled so as to be shorter than the opening period of the intake valve.

(3) In the above (2), preferably, the injection rate variable mechanism capable of changing the fuel injection rate is a mechanism capable of changing a lift amount of a valve body of a fuel injection valve for controlling fuel discharge, The control means increases the lift amount of the valve body to increase the fuel injection amount per unit time of the fuel injection valve.

(4) In the above (2), preferably, the injection rate variable mechanism capable of changing the fuel injection rate is a mechanism capable of changing the fuel pressure of a high-pressure fuel feed pump, and the control means includes: The fuel pressure is increased to increase the fuel injection amount per unit time of the fuel injection valve.

(5) In the above (1), preferably, at the time of a low load operation, the control means sets an opening timing of the intake valve to an intake stroke, and sets an opening period and a lift amount of the intake valve and an intake pipe. The amount of intake air per unit time is reduced by controlling the degree of opening of a throttle valve provided upstream, and the fuel injection period of the fuel injection valve is controlled by the opening of the intake valve. The control is performed so as to be equal to or less than the mouth period.

(6) In the above (1), preferably, the control means sets the fuel injection end timing to a timing earlier than the closing timing of the intake valve by a time required for the injected fuel spray to reach the intake valve. It was done. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a configuration diagram illustrating a configuration of an internal combustion engine including a variable intake valve according to the first embodiment of the present invention.

FIG. 2 is a flowchart illustrating an operation of the internal combustion engine including the variable intake valve according to the first embodiment of the present invention.

Figure 3 is an explanatory diagram of the valve opening / closing timing and lift.

FIG. 4 is an explanatory diagram of a relationship between a ball valve lift amount FVL of a fuel injection valve having a lift amount variable mechanism used in an internal combustion engine according to an embodiment of the present invention and a fuel injection rate IRT.

FIG. 5 is a timing chart showing the operation at the time of cranking of the internal combustion engine provided with the variable intake valve according to the first embodiment of the present invention.

FIG. 6 is a timing chart showing the operation of the internal combustion engine equipped with the variable intake valve according to the first embodiment of the present invention at the time of a complete explosion.

FIG. 7 is a configuration diagram illustrating a configuration of an internal combustion engine including a variable intake valve according to the second embodiment of the present invention.

FIG. 8 is a flowchart showing an operation of the internal combustion engine including the variable intake valve according to the second embodiment of the present invention.

FIG. 9 is an explanatory diagram of the relationship between the fuel pressure RP of the fuel injection valve used in the internal combustion engine according to one embodiment of the present invention and the fuel injection rate IRT.

FIG. 10 is an explanatory diagram of the relationship between the fuel pressure RP of the fuel injection valve used in the internal combustion engine according to the embodiment of the present invention and the average spray velocity VF.

FIG. 11 is a timing chart showing an operation at the time of a complete explosion of an internal combustion engine equipped with a variable intake valve according to the second embodiment of the present invention.

FIG. 12 shows a configuration of an internal combustion engine having a variable intake valve according to the third embodiment of the present invention. FIG.

FIG. 13 is a flowchart showing the operation of an internal combustion engine equipped with a variable intake valve according to the third embodiment of the present invention.

FIG. 14 is a timing chart showing the operation of the internal combustion engine equipped with the variable intake valve according to the third embodiment of the present invention at the time of a complete explosion. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the configuration and operation of the internal combustion engine including the variable intake valve according to the first embodiment of the present invention will be described with reference to FIGS.

First, the configuration of an internal combustion engine having a variable intake valve according to the present embodiment will be described with reference to FIG. In this embodiment, multipoint injection (MPI) in which a fuel injection valve is provided for each cylinder is used.

The combustion chamber 4 is formed by a cylinder head 1, a cylinder block 2, and a piston 3 inserted into the cylinder block 2. An ignition plug 31 is provided at the upper center of the combustion chamber 4. The piston 3 is connected to a crankshaft 18 via a connecting rod 17. The crankshaft 18 is provided with a crank angle sensor 19 capable of detecting a crank angle and an engine speed.

The cylinder block 2 is provided with a water temperature sensor 12 for detecting the temperature of the cooling water. In the combustion chamber 4, an intake pipe 5 and an exhaust pipe 6 are opened. An intake valve 7 and an exhaust valve 8 for opening and closing the openings of the intake pipe 5 and the exhaust pipe 6, respectively, are provided.

The accelerator pedal 9 is provided with an accelerator opening sensor (S ACC) 10 for detecting the amount of depression of the driver. The intake pipe 5 is provided with a fuel injection valve 11 that injects fuel toward the intake valve 7 and a throttle valve 13 that can adjust the amount of air to be taken into the combustion chamber 4. The exhaust pipe 6 is provided with a three-way catalyst 14, an air-fuel ratio sensor 15 is provided on the upstream side, and a 〇2 sensor 16 is provided on the downstream side. The intake valve 7 has a variable valve mechanism (VV) 26 that can change the valve opening timing, opening period, and lift amount. You. A low pressure pump (PL) 30 installed in a fuel tank 29 is connected to the fuel injection valve 11 by a fuel pipe 28. A fuel pressure sensor (SFU) 27 capable of detecting a fuel pressure is provided in the middle of the fuel pipe 28.

An electronic control unit (ECU) 20 is a central processing unit (CPU) that executes arithmetic processing according to a set program, and a read-only memory (ROM) that stores control programs and data necessary for arithmetic operations. ) 22, a random access memory (RAM) 23 for temporarily storing the calculation results, an input circuit (IN) 24 for receiving signals from each sensor, and transmitting signals to each device from the calculation results Output circuit

(OUT) 25.

Inside the fuel injection valve 11, a valve body that controls the fuel injection amount by moving up and down is provided. The amount of fuel injection is controlled by changing the valve lift and opening period. The valve body is made of magnetostrictive material, and the length of the valve body can be changed by generating a magnetic field. The fuel injection valve 11 is provided with a lift amount variable mechanism (VL) 32 for controlling the strength of the magnetic field, so that the fuel injection amount can be changed while the opening period is constant. The variable valve mechanism 26 mechanically moves the camshaft of the intake valve to control the valve opening timing, opening period, and lift amount. Next, the operation of the internal combustion engine provided with the variable intake valve according to the present embodiment will be described with reference to FIGS.

FIG. 2 is a flowchart showing the operation of the internal combustion engine provided with the variable intake valve according to the first embodiment of the present invention.

When the ignition switch is turned on and the engine starts, in step s100, the ECU 20 receives the signal of the accelerator opening sensor 10 into the input circuit 24, and the CPU 21 calculates the accelerator opening ACD. .

Next, in step s110, the ECU 20 takes in the signal of the water temperature sensor 12 into the input circuit 24, and the CPU 21 calculates the water temperature TW.

Next, in step s120, the ECU 20 takes in the signal of the crank angle sensor 19 into the input circuit 24, and the CPU 21 calculates the engine speed NE. Next, in step s130, the ECU 20 takes in the signal of the fuel pressure sensor 27 into the input circuit 24, and the CPU 21 calculates the fuel pressure RP. Next, in step s140, the CPU 21 of the ECU 20 determines whether or not the load is low by using the accelerator opening ACD. If it is determined that the load is medium / high, the process proceeds to step s150. If it is determined that the load is low, the process proceeds to step s170.

When the CPU 21 determines that the load is medium to high, the CPU 21 determines the opening timing VOT2, the lift amount VL2, and the opening period VT2 of the intake valve 7 and controls the variable valve mechanism 26 in step s150. Since the load is medium and high, the opening timing V OT2, the lift amount VL2, and the opening period VT2 of the intake valve 7 are set so as to become the preset maximum values, respectively.

Here, the opening / closing timing of the valve and the lift amount will be described with reference to FIG.

Figure 3 is an explanatory diagram of the valve opening / closing timing and lift. In FIG. 3, the horizontal axis shows the crank angle S (deg), and the vertical axis shows the valve lift. The crank angle 0 is 0 to 90 degrees is the expansion stroke E XP, the 90 to 180 degrees is the scavenging process EXH, the 180 to 270 degrees is the intake stroke INT, and the 270 to 360 degrees is the compression stroke COM. In the figure, the solid line IN indicates the lift of the intake valve, and the dotted line EX indicates the lift of the exhaust valve. At medium to high loads, for example, the intake valve opening timing VOT2 is 360 degrees, the lift amount VL2 is the amount shown, and the opening period VT2 is 210 degrees. Next, in step s160, the CPU 21 calculates the target fuel injection amount MF2, the air-fuel ratio AZF2, the throttle valve opening THA2, and the fuel injection timing FI from the accelerator opening A CD, the water temperature TW, and the engine speed NE. Calculate T2, ignition timing I GT2. Then, the CPU 21 controls the fuel injection valve 11, the throttle valve 13, and the spark plug 16 so that these calculated values are obtained.

Here, the fuel injection timing FITT2 is set to a timing at which fuel injection ends during the exhaust stroke as used in a conventional MPI engine. The ignition timing I GT2 is determined near TDC for the purpose of increasing the exhaust gas temperature when the water temperature TW is less than 80 ° C, and near 20 ° before TDC when the water temperature TW is 80 ° C or more. You. The air-fuel ratio AZF 2 is determined to be 14.7, which is the theoretical mixing ratio of gasoline. The air-fuel ratio during operation is detected by the air-fuel ratio sensor 15, and if an error occurs from the target air-fuel ratio A / F2, the throttle valve opening THA2 is corrected.

In the above example, the lift amount and the operating angle of the exhaust valve are fixed, but the exhaust valve Alternatively, a variable valve mechanism may be attached.

On the other hand, when the CPU 21 determines in step s140 that the accelerator opening ACD has a low load, in step s170, the CPU 21 determines whether the throttle valve 13 has the maximum opening degree (full open). Set the opening to THAI. Also, the CPU 21 calculates the target fuel injection amount MF1, the air-fuel ratio A / F1, and the ignition timing IGT1 from the water temperature TW, the engine speed NE, and the accelerator opening ACD.

Next, in step s180, the CPU 21 determines the opening timing VOT1, the opening period VT1, and the lift amount VL1 of the intake valve 7 from the air amount calculated from the fuel injection amount MF1 and the air-fuel ratio A / F1. calculate. The air-fuel ratio during operation is detected by the air-fuel ratio sensor 15, and if an error occurs with the air-fuel ratio AZF1, the opening period VT1 and the valve lift VL1 are corrected.

Next, in step s190, the CPU 21 calculates a fuel injection rate Γ RT which is a fuel injection amount per unit time of the fuel injection valve 11.

Here, the relationship between the ball valve lift amount FVL of the fuel injection valve 11 having the variable lift amount mechanism 21 and the fuel injection rate IRT will be described with reference to FIG.

In FIG. 4, the horizontal axis shows the ball valve lift FVL, and the vertical axis shows the fuel injection rate I RT. The origin N in FIG. 4 indicates the state of the standard value. The standard value indicates a state in which a magnetic field is generated in the valve element of the ball valve and the valve element is extended, and is normally used in this state. As the valve valve lift FVL increases from the standard value, the fuel injection rate I RT also increases linearly from the standard value.

In step s190, the initial value of the ball valve lift amount L F1 is the minimum standard value, and the fuel injection rate I RT is also set to the standard value.

Next, in step s200, the CPU 21 calculates a fuel injection period T1 from the fuel injection rate IRT and the fuel injection amount MF1.

Next, in step s210, the CPU 21 calculates the injection timing correction time T2. The injection timing correction time T2 is set after fuel is injected from the fuel injection valve 11. This is the time required for the fuel to reach the combustion chamber 4. The injection timing correction time T 2 is determined by the spray speed VF and the distance L from the tip of the fuel injection valve to the intake valve.

It is calculated by (1).

T2 = L / VF ... (1) Here, the average speed VF of the fuel spray is obtained from the fuel pressure RP and is determined by the performance of the fuel pump P L. Normally, fuel pressure caregis! In the configuration using a writer, the fuel pressure RP is kept constant. Since the distance L between the fuel injection valve and the intake valve is determined by the configuration of the engine, if the fuel pressure RP is constant, the injection timing correction time T2 can use a value previously stored in the ROM22. When the fuel pressure RP is detected by the fuel pressure sensor 27, a map of the relationship between the fuel pressure RP and the injection timing correction time T2 is stored in the ROM 22 in advance, and the injection timing is corrected using the map. The correct time T2 can also be calculated.

Next, in step s220, the CPU 21 determines whether or not the valve opening period VT1 'of the intake valve 7 is equal to or longer than the fuel injection period T1. If the opening period VT1 is equal to or longer than the fuel injection period T1, the process proceeds to step s230. In the following cases, the process proceeds to step s240. If the opening period VT1 is shorter than the fuel injection period T1, the valve is still injected even if the valve is closed because the opening period of the valve is shorter than the fuel injection period. Accordingly, since the injected fuel adheres to the intake pipe 5, a process for preventing this is executed in step s240 and thereafter.

If the opening period VT1 is longer than the fuel injection period T1, in step s230, the CPU 21 sets the end timing of the fuel injection period T1 earlier than the end timing of the opening period VT1 by the injection timing correction time T2. Thus, the fuel injection timing FIT 1 is calculated.

On the other hand, if the opening period VT1 is shorter than the fuel injection period T1, in step s240, the CPU 21 calculates the fuel injection rate IRT to be the same as the fuel injection period T1 and the opening period VT1.

In step s250, the CPU 21 determines whether the fuel injection period Recalculate the fuel injection period T1 so that it becomes equal to the mouth period VTl.

Then, in step s260, the CPU 21 obtains the ball valve lift amount L FI from the fuel injection rate I RT obtained in step s240 using the characteristics shown in FIG.

Next, in step s230, the CPU 21 calculates the fuel injection timing FI T1 such that the end time of the fuel injection period T1 is earlier than the end time of the opening period VT1 by the injection timing correction time T2. I do.

Then, the CPU 21 controls the fuel injection valve 11, the throttle valve 13, the ignition plug 16, the valve variable mechanism 26, and the lift amount variable mechanism 32 so that these calculated values are obtained.

Next, a specific operation of the internal combustion engine including the variable intake valve according to the present embodiment will be described with reference to FIGS. In the following description, it is assumed that the engine is operating at the time of cold start and that the accelerator is not opened immediately after the engine is started.

FIG. 5 is a timing chart showing an operation at the time of cranking of the internal combustion engine including the variable intake valve according to the first embodiment of the present invention. FIG. 6 is a timing chart showing an operation at the time of a complete explosion of the internal combustion engine provided with the variable intake valve according to the first embodiment of the present invention. The horizontal axis in Figs. 5 and 6 indicates the time T (ms). The crank angle is shown in parentheses. The upper side of FIGS. 5 and 6 shows the lift amount FV L (/ m) of the fuel injection valve. The lower part of FIGS. 5 and 6 shows the lift amount VL (mm) of the intake valve.

First, the operation in the cranking state by star evening will be described with reference to Figs.

When the engine starts and enters the cranking state, signals from the accelerator opening sensor 10, the water temperature sensor 12, and the crank angle sensor 19 are input to the input circuit 24 through the processing of steps si00, s110, and si20 in FIG. Is input to Since the fuel pressure RP is kept constant, the processing in step s130 is not performed. Here, for example, it is assumed that the accelerator opening ACD = 0 degrees, the water temperature Τ "νν = 20Τ, and the engine speed ΝΕ = 200 r / min. The results are stored in the RAM M23 and updated successively. You. Since the operating condition is such that the accelerator is not opened immediately after the engine is started, the process proceeds from step s140 in FIG. 2 to step s170, where the fuel injection amount MF1 is calculated from the accelerator opening ACD. The intake air amount is calculated so that the air-fuel ratio AZF 1 becomes 14.7 for the injection amount MF 1. Here, for example, it is assumed that the engine is a 500-cc single cylinder engine, the fuel amount is 12 mg, and the air amount is 176 mg. A signal is output from the output circuit 25 to the throttle valve 13 to control the throttle valve opening THAI to be fully opened. The ignition timing I GT 1 is set at the top dead center for the purpose of increasing the temperature of the exhaust gas, and is controlled to output a signal to the ignition plug 31 when the crank angle reaches the top dead center.

Next, in the processing of step s180, the opening timing V〇T1, the opening period VT1, and the maximum lift amount VL1 of the intake valve are determined from the target intake air amount by referring to a map stored in the ROM 22 in advance. I do. Here, it is assumed that the opening timing of the intake valve VOT 1 is 60 ° ATDC, the opening period is 50 ° crank angle, and the maximum lift is 0.8mm. That is, as shown in the lower part of Fig. 5, the intake valve starts to open at 60 ° ATDC, and opens for 50 ° up to 110 ° ATDC, and the maximum lift at that time is 0.8 mm.

If the air flow generated at the time of intake is very high, the fuel spray flying in the intake pipe will adhere to the intake pipe under the influence of the flow. For this reason, the opening timing V OT 1 is set so that the difference between the speed of the fuel spray and the speed of the air generated during intake is 20 Om / sec or less for a fuel spray having an average particle diameter of 50 m or more. Within this range, it is less susceptible to the effects of airflow during intake.

Next, due to the processing of steps s190 and s200, the initial value of the pole valve lift amount LF1 is the minimum standard value, and the fuel injection period T1 is calculated from the standard value of the fuel injection rate IRT. Is done. Here, assuming that the standard value of the fuel injection rate I RT is 1.2 mg / ms, the fuel injection period T 1 is 1 Oms from the fuel amount of 12 mg obtained in step s 170.

Next, by the processing in step s210, the injection timing correction time T2 is set to 2.5 ms from the average spray velocity VF and the distance L from the tip of the fuel injection valve to the intake valve. This is because the average diameter of the fuel droplets injected from the fuel injector 1 1 is 60 m, the average spray velocity V F was 4 OmZsec, and the distance L from the tip of the fuel injection valve to the intake valve was 0.1 lm. At a rotational speed of 200 r / min, this corresponds to a crank angle of 3 degrees. The injection timing correction time T2 is stored in the ROM 22 in advance.

Next, in the determination of step s220, at a rotational speed of 200 r / min, the crank angle 50 °, which is the opening period of the intake valve, becomes 42 ms, and the opening period VT1 (42 ms) is determined by the fuel injection obtained in step 200. Since it is longer than the period T 1 (10 ms), it is determined that the fuel injection rate IRT does not need to be changed, and the process proceeds to step s210.

In the processing of step s230, the fuel injection period T1 is 1 Oms, which corresponds to a crank angle of 12 degrees at a rotational speed of 200 rZmin. Since the intake valve closing timing is 110 ° AT DC, the fuel injection timing is as follows: the intake valve closing timing is 110 ° ATDC, the fuel injection period T l (10 ms = 12 °), and the injection timing correction time T 2 (2 5 ms = 3.) is subtracted to set 95 ° ATDC, and the crank angle is controlled to output a signal from the output circuit 25 to the fuel injection valve 11 at 95 ° ATDC. That is, as shown in the upper part of FIG. 5, the fuel injection valve 11 starts the injection at 95 ° ATDC, performs the injection for 12 °, and ends the injection at 107 ° ATDC. The 107 ° ADTC at the end of injection is 3 ° earlier than the 110 ° ATDC at which the intake valve closes. The lift FVL of the fuel injector is 40 m.

The above-described result is calculated by the CPU 21 and the intake stroke starts at the same time. When the piston 3 is located at the top dead center, the intake valve 7 and the exhaust valve 8 are both closed. When the piston 3 starts to fall from the top dead center position, the pressure in the combustion chamber 4 decreases because the intake valve 7 is closed.

Then, as shown in FIG. 5, the intake valve 7 opens at 60 ° ATDC, but since the pressure in the combustion chamber 4 is lower than the pressure in the intake pipe 5, immediately after the intake valve opens, the intake valve 7 A high-speed airflow is generated in the combustion chamber 4. Further, by making the lift amount of the intake valve 7 very small, the speed of the airflow sucked into the combustion chamber 4 by lowering the piston 3 can be maintained at 40 to 50 m / sec.

At 95 ° ATDC, fuel is injected from the fuel injection valve 11, and the fuel spray reaches the vicinity of the intake valve 7 in about 2.5 ms and is generated by making a minute lift It flows into the combustion chamber 4 by the high-speed airflow. At this time, the particles pass through the gap between the intake valve 7 and the combustion chamber 4 and are atomized by the shearing force of the high-speed airflow.

At 107 ° ATDC, the fuel injection ends. At 110 °, when the last part of the fuel spray flows into the combustion chamber 4, the intake valve 7 closes. The spray atomized by the high-speed airflow is vaporized and easy to ride on the flow of air, so it does not adhere to the cylinder wall, and a homogeneous air-fuel mixture is formed. When the compression stroke is completed and the piston reaches the top dead center, it is ignited by the spark plug 31 and the engine completely explodes, and starts rotating regardless of the speed.

Next, the operation during continuous operation immediately after the complete explosion will be described with reference to Figs. In the upper part of FIG. 6, the solid line B indicates the lift amount of the fuel injection valve when the correction of steps s240 to s260 in FIG. 2 is performed, and the broken line A indicates the lift amount before the correction is performed. Is shown.

The signals from the accelerator opening sensor 10, the water temperature sensor 12, and the crank angle sensor 19 are input to the input circuit 24, and from these signals, the accelerator opening AC D = 0, water temperature TW = 20 ° C, engine speed NE = 1200 rZmin is calculated. Since the load is constant, the amount of fuel and the amount of air are the same as in the above example. The intake air volume is determined by the opening timing and the opening period, and the influence of the engine speed is small. Therefore, as in the above example, the intake valve opening timing VOT1 is 60 ° ATDC, the opening period is 50 ° crank angle, and the maximum lift is 0. . 5 mm. That is, as shown in the lower part of Fig. 6, the intake valve starts to open at 60 ° ATDC, and opens for 50 ° up to 110 ° ATDC, and the maximum lift at that time is 0.8 mm.

The initial value of the ball valve lift LF1 is a standard value, the fuel injection rate I RT = 1.2mgZms, and the fuel injection period T1 is 10ms.

Next, in the determination of step s220, at a rotational speed of 1200 r / min, the crank angle 50 °, which is the opening period of the intake valve, becomes 6.94 ms, and the opening period VT 1 (6.92 ms) becomes the fuel injection period. Since it is shorter than T l (10 ms) and the fuel injection rate I RT needs to be changed, the process proceeds to step s240.

Then, the CPU 21 resets the fuel injection rate IRT so that the fuel injection period T1 becomes the same as the opening period VT1 by the processes of steps s240 and s250. Since the opening period is 6.94 ms and the fuel injection amount is 12 mg, the target fuel injection rate I RT is 1.73 mg ms.

Further, the ball valve lift amount FVL that satisfies the target fuel injection rate IRT is derived from the map stored in the ROM 22 by the process of step s260. The ball valve lift FVL is controlled by the lift variable mechanism 32 so that the fuel injection period T1 becomes 6.94 ms.

From the average spray velocity V F and the distance L from the tip of the fuel injection valve to the intake valve, the injection timing correction time T 2 is 2.5 ms, which corresponds to a crank angle of 18 degrees at a rotational speed of 1200 r / min. The fuel injection period T1 is 6.94 ms, which corresponds to a crank angle of 50 degrees at a rotational speed of 1200 r / min. The intake valve closing timing is 110 ° ATDC, the fuel injection timing is set to 42 ° ATDC by CPU21, and the output circuit 25 is controlled to output a signal from the output circuit 25 to the fuel injection valve 11 when the crank angle is 42 ° ATDC. .

In the processing in step s230, the fuel injection period T1 is 6.94 ms, which corresponds to a crank angle of 50 degrees at a rotational speed of 1200 rZmin. Since the intake valve closing timing is 110 ° ATDC, the fuel injection timing is as follows: The intake valve closing timing is 110 ° ATDC, the fuel injection period T1 (6.94ms = 50 °) = 18 °), and is set to 42 ° ATDC. At a crank angle of 42 ° ATDC, the output circuit 25 is controlled to output a signal to the fuel injection valve 11. That is, as shown in the upper part of FIG. 6, the fuel injection valve 11 starts the injection from the 42 ° ATDC, injects the fuel for 50 °, and ends the injection at the 92 ° ATDC. The 92 ° ADTC at the end of the injection is 18 ° earlier than the 110 ° ATDC at which the intake valve closes. The lift FVL of the fuel injector is 58 m. When the intake stroke starts and the piston 3 starts to fall from the top dead center position, the pressure in the combustion chamber 4 decreases because the intake valve 7 is closed. Then, as shown in the lower part of Fig. 6, the intake valve 7 opens when the temperature reaches 60 ° ATDC, but since the pressure in the combustion chamber 4 is lower than the pressure in the intake pipe 5, the intake A high-speed airflow is generated from the pipe 5 to the combustion chamber 4. Also, by minimizing the lift amount of the intake valve 7, the velocity of the airflow sucked into the combustion chamber 4 by lowering the piston 3 is maintained at 20 Om / sec. I can.

At 42 ° AT DC, fuel is injected from the fuel injection valve 11 as shown in the upper part of Fig. 6, and the fuel spray reaches the vicinity of the intake valve 7 in about 2.5 ms, causing a slight lift. It flows into the combustion chamber 4 by the high-speed airflow generated by this. At this time, fine particles are formed by the shearing force of the high-speed airflow where the gas passes through the gap between the intake valve 7 and the combustion chamber 4.

The fuel injection ends at 92 ° ATDC, and at 110 ° the intake valve 7 closes when the last part of the fuel spray flows into the combustion chamber 4. The spray atomized by the high-speed airflow is vaporized and chewy, and easily adheres to the flow of air, so that it does not adhere to the cylinder wall, and a homogeneous mixture is formed. Therefore, when the piston reaches the top dead center, it is stably burned by the spark plug 31 after ignition.

As described above, according to the present embodiment, by setting the fuel injection period T1 to be equal to or less than the opening period VT1 of the intake valve, there is no adhesion to the cylinder wall, and a homogeneous air-fuel mixture is formed to perform combustion. By doing so, the amount of unburned fuel discharged can be reduced. Next, the configuration and operation of an internal combustion engine provided with a variable intake valve according to the second embodiment of the present invention will be described with reference to FIGS.

First, the configuration of the internal combustion engine including the variable intake valve according to the present embodiment will be described with reference to FIG. In this embodiment, multipoint injection (MPI) in which a fuel injection valve is provided for each cylinder is used.

FIG. 7 is a configuration diagram illustrating a configuration of an internal combustion engine including a variable intake valve according to the second embodiment of the present invention. The same reference numerals as those in FIG. 1 indicate the same parts.

The present embodiment differs from the configuration shown in FIG. 1 in the following points. That is, a high-pressure pump (PH) 33 is used as the fuel pump. Further, the fuel pipe 28 is provided with a fuel pressure variable mechanism (VFP) 34 which can change the fuel pressure by adjusting the flow rate in the pipe. The fuel injection valve is provided with a conventionally used fuel injection valve 35 having no mechanism for changing the lift amount.

Next, the operation of the internal combustion engine including the variable intake valve according to the present embodiment will be described with reference to FIGS.

FIG. 8 shows the operation of an internal combustion engine equipped with a variable intake valve according to the second embodiment of the present invention. It is a flowchart shown. The same step numbers as those in FIG. 2 indicate the same processing contents.

The processing contents of steps s100 to s180 are the same as those in FIG.

In step s19OA, the CPU 21 calculates the fuel injection rate IRT. Here, in the present embodiment, the fuel injection rate I RT is determined from the characteristic diagram of the fuel pressure RP and the fuel injection rate IR shown in FIG.

Here, the relationship between the fuel pressure RP and the fuel injection rate IRT will be described with reference to FIG.

FIG. 9 is an explanatory diagram showing the relationship between the fuel pressure RP of the fuel injection valve used in the internal combustion engine according to the embodiment of the present invention and the fuel injection rate IRT.

In FIG. 9, the horizontal axis shows the fuel pressure RP, and the vertical axis shows the fuel injection rate IRT. The origin N in FIG. 9 indicates the state of the standard value. The standard value indicates the lowest fuel pressure. As the fuel pressure RP increases from the standard value, the fuel injection rate I RT also increases from the standard value. '

In step s19OA, the initial value of the fuel pressure RP is the minimum standard value, and the fuel injection rate IRT is also set to the standard value.

Next, in step s200, the CPU 21 calculates the fuel injection period T1 from the fuel injection rate IRT and the fuel injection amount MF1.

Next, in step s205, the CPU 21 calculates the spray average velocity VF. Since the average spray speed VF changes depending on the fuel pressure RP, the average spray speed VF can be obtained from the characteristic diagram of the fuel pressure RP and the average spray speed VF shown in FIG.

Here, the relationship between the fuel pressure RP and the average spray velocity VF will be described with reference to FIG. ,

In FIG. 10, the horizontal axis represents the spray average velocity VF, and the vertical axis represents the fuel injection rate IRT. The origin N in FIG. 10 indicates the state of the standard value. The standard value indicates the lowest fuel pressure. As the fuel pressure RP increases from the standard value, the average spray velocity VF also increases from the standard value. Next, in step s21OA, the CPU 21 calculates the injection timing correction time T2. The injection timing correction time Τ2 is determined by the spray speed VF and the distance L from the tip of the fuel injection valve to the intake valve, and is calculated by the following equation (1).

T 2 = L / VF… (1) Injection timing correction time T 2 is determined by the spray speed VF and the distance L from the tip of the fuel injection valve to the intake valve, but since the spray speed VF changes with the fuel pressure RP, it is stored in ROM22. Is stored, and the distance L to the intake valve is stored in the ROM 22. During operation, the average spray velocity VF is calculated from the result of the fuel pressure sensor 27, and the CPU 21 calculates the injection timing correction time T2 according to equation (1).

If it is determined in step s220 that the opening period VT1 is shorter than the fuel injection period T1, in step s240, the CPU 21 determines whether the fuel injection period T1 is equal to the opening period VT1. Calculate the injection rate IRT. Then, in step s270, the CPU 21 again calculates the target fuel pressure RP from FIG. 9 so as to reach the calculated fuel injection rate IRT.

Next, in step s275, the CPU 21 obtains the spray average velocity VF again. In step s280, the CPU 21 calculates the injection timing correction time T2 again.

Then, the CPU 21 controls the fuel injection valve 11, the throttle valve 13, the spark plug 16, the variable valve mechanism 26, and the variable fuel pressure mechanism 34 so that these calculated values are obtained.

Next, a specific operation of the internal combustion engine including the variable intake valve according to the present embodiment will be described with reference to FIG. In the following description, it is assumed that the engine is operating at the time of cold start and that the accelerator is not opened immediately after the engine is started.

FIG. 11 is a timing chart showing an operation at the time of a complete explosion of an internal combustion engine equipped with a variable intake valve according to the second embodiment of the present invention. The horizontal axis in FIG. 11 indicates time T (ms). The crank angle is shown in parentheses. The upper side of FIG. 11 shows the lift amount FVL (ΐη) of the fuel injection valve. Fig. 11 Lower part of the intake valve The amount (mm).

First, the operation in the cranking state by star evening will be described. The operation at this time is the same as that shown in FIG.

When the engine starts and enters the cranking state, signals from the accelerator opening sensor 10, the water temperature sensor 12, and the crank angle sensor 19 are input to the input circuit 24, and the accelerator opening ACD = 0 by the CPU 21 based on these signals. , Water temperature TW = 20 ° C, engine speed NE = 200 r / min.

Next, the CPU 21 calculates the intake air amount from the accelerator opening ACD so that the fuel injection amount MF 1 and the air-fuel ratio A / F 1 become 14.7. Here, the fuel amount is 12 mg and the air amount is 176 mg. A signal is output from the output circuit 25 to the throttle valve 13, and the throttle valve opening THAI is controlled to be fully opened. The ignition timing I GT1 is set at the top dead center for the purpose of increasing the temperature of the exhaust gas, and is controlled to output a signal to the ignition plug 31 when the crank angle reaches the top dead center.

The standard value of the fuel pressure RP is a value that can secure the minimum flow rate, and the initial value is this standard value, and the fuel injection rate IRT is calculated from the fuel pressure RP. Then, the fuel injection period T1 is calculated by the CPU 21 from the calculated fuel injection rate IRT. Here, the fuel pressure RP = 300 kPa and the fuel injection rate I RT = 1.2 mg / ms are used as the initial values, and the fuel injection period T1 is 1 Oms.

Next, the operation during continuous operation immediately after the complete explosion will be described with reference to FIGS. In the upper part of FIG. 11, solid line B indicates the lift amount of the fuel injection valve when the correction of steps s240 to s280 in FIG. 8 is performed, and dashed line A indicates the value before the correction is performed. The lift amount is shown.

The signals from the accelerator opening sensor 10, the water temperature sensor 12, and the crank angle sensor 19 are input to the input circuit 24. From these signals, the accelerator opening AC D = 0, water temperature = 20 ° Engine speed NE = 1200 r / min is calculated. Here, since the load is constant, the fuel amount and air amount are the same as during cranking, the opening timing of the intake valve VOT1 is 60 ° ATDC, the opening period is 50 ° crank angle, and the maximum lift is 0.8mm. In other words, as shown in the lower part of Fig. 11, the intake valve starts to open at 60 ° ATDC, opens for 50 ° to 110 ° ATDC, and The maximum lift at the time of is 0.8 mm.

The ball valve lift LF 1 is set to 40, the fuel injection rate I RT = 1.2 mg / ms, the fuel injection period T 1 is 1 Oms, but the crank angle is the opening period at 1200 r / min. 50 ° is 6.94 ms, and it is determined that the opening period VT 1 is shorter than the fuel injection period T 1 at 1200 r / min by the determination in step s 220.

Therefore, in step s240, the CPU 21 resets the fuel injection rate IRT so that the fuel injection period T1 becomes the same as the opening period VT1. Since the opening period is 6.94 ms and the fuel injection amount is 12 mg, the target fuel injection rate I RT is 1.73 mg / ms.

Next, in step s270, the CPU 21 refers to the fuel pressure RP from the map stored in the ROM 22, and obtains the fuel pressure RP that becomes the target fuel injection rate IRT. The fuel pressure RP is, for example, 620 kPa.

Next, in step s275, the CPU 21 refers to the spray average speed VF from the map stored in the ROM 22. When the fuel pressure R P is 620 kPa, the average spray velocity V F is 58 m / sec.

Then, in step s280, the injection timing correction time T2 is 1.7 ms from the distance L from the tip of the fuel injection valve to the intake valve, and corresponds to a crank angle of 12 degrees at a rotational speed of 1200 r / min. The fuel injection period T1 is 6.94 ms, which corresponds to a crank angle of 50 degrees at a rotational speed of 1200 r / min. The intake valve closing timing is 110 ° A TDC, the fuel injection timing is set to 48 ° ATDC by the CPU 21, and the output circuit 25 is controlled to output a signal from the output circuit 25 to the fuel injection valve 11 when the crank angle is 48 ° ATDC. You.

That is, as shown in the upper part of FIG. 11, the fuel injection valve 11 starts injection at 48 ° ATDC, injects fuel for 50 °, and ends injection at 98 ° ATDC. The 98 ° ADTC at the end of the injection is 12 ° earlier than the 1 10 ° ATDC when the intake valve closes. The lift amount FVL of the fuel injection valve does not change at 40 iim, but a predetermined fuel injection amount can be obtained by increasing the fuel pressure RP. When the intake stroke begins and piston 3 starts to fall from the top dead center position, intake valve 7 Since it is closed, the pressure in the combustion chamber 4 decreases. Then, as shown in the lower part of FIG. 11, the intake valve 7 opens at 60 ° ATDC, but since the pressure in the combustion chamber 4 is lower than the pressure in the intake pipe 5, immediately after the intake valve opens, A high-speed airflow is generated from the intake pipe 5 to the combustion chamber 4. Further, by making the lift amount of the intake valve 7 small, the velocity of the airflow sucked into the combustion chamber 4 by lowering the piston 3 can be kept at 2 OOSS OmZs ec.

On the other hand, as shown in the upper part of Fig. 11, when the temperature reaches 48 ° ATDC, fuel is injected from the fuel injection valve 11 and the fuel spray reaches the vicinity of the intake valve 7 in about 1.7 ms, causing a slight lift The resulting high-speed airflow flows into the combustion chamber 4. At this time, the particles pass through the gap between the intake valve Ί and the combustion chamber 4 and are atomized by the shearing force with the high-speed airflow. ■

Then, the fuel injection ends at 98 ° AT DC, and the intake valve 7 closes when the last part of the fuel spray flows into the combustion chamber 4 at 110 °. The spray atomized by the high-speed airflow is easy to vaporize, and because it is easy to ride on the flow of air, there is no adhesion to the cylinder wall, and a homogeneous mixture is formed. Therefore, when the piston reaches the top dead center, it is stably burned after ignition by the spark plug 31.

As described above, according to the present embodiment, by setting the fuel injection period T1 to be equal to or less than the opening period VT1 of the intake valve, there is no adhesion to the cylinder wall, and a homogeneous mixture is formed and burned. As a result, the amount of unburned fuel discharged can be reduced. Next, the configuration and operation of an internal combustion engine having a variable intake valve according to the third embodiment of the present invention will be described with reference to FIGS.

FIG. 12 is a configuration diagram illustrating a configuration of an internal combustion engine including a variable intake valve according to the third embodiment of the present invention. The same reference numerals as those in FIG. 1 indicate the same parts.

The present embodiment differs from the configuration shown in FIG. 1 in the following points. That is, the fuel injection valve 35 is a conventionally used injection valve without a mechanism for varying the lift amount. Otherwise, the configuration is the same as in FIG. Next, the operation of the internal combustion engine including the variable intake valve according to the present embodiment will be described with reference to FIG.

FIG. 13 is a flowchart illustrating an operation of the internal combustion engine including the variable intake valve according to the third embodiment of the present invention. The same step numbers as those in FIG. 2 indicate the same processing contents.

In the present embodiment, unlike the examples shown in FIGS. 1 and 7, there is no means for changing the fuel injection rate IRT. Therefore, when the opening period VT1 is shorter than the fuel injection period T1, the opening degree THAI of the throttle valve 13 is reduced to generate a negative pressure in the intake pipe 5, thereby reducing the amount of intake air per unit time. The opening THA1 of the throttle valve 13 is controlled so that the period VT1 becomes equal to the fuel injection period T1.

The processing contents of steps s100 to s170, s180, and s230 are the same as those in FIG.

In the present embodiment, when the CPU 21 determines that the accelerator opening ACD is low load in the determination in step s140, in step s170, the CPU 21 determines that the opening of the throttle valve 13 is the maximum (full open). Throttle valve opening THAI. Further, the CPU 21 calculates a target fuel injection amount MF1, an air-fuel ratio A / F1, and an ignition timing IGT1 from the water temperature TW, the engine speed NE, and the accelerator opening ACD.

Next, in step s175, the CPU 21 calculates a fuel injection rate IRT which is a fuel injection amount of the fuel injection valve 11 per unit time. Since the fuel injection valve 11 does not have a mechanism capable of changing the lift amount, the fuel injection rate I RT is a preset value. Further, the CPU 21 calculates a fuel injection period T1 from the fuel injection rate IRT and the fuel injection amount MF1. Further, the CPU 21 calculates an injection timing correction time T2. The injection timing correction time T2 is determined by the spray speed VF and the distance L from the tip of the fuel injection valve to the intake valve, and is calculated by the above equation (1).

Next, in step s180, the CPU 21 calculates the opening timing VOT1, the opening period VT1, and the lift amount VL1 of the intake valve 7 from the air amount calculated from the fuel injection amount MF1 and the air-fuel ratio A / F1. I do. The air-fuel ratio during operation is detected by the air-fuel ratio sensor 15, and if an error occurs with the air-fuel ratio A / F1, the opening period VT1 and the valve lift VL1 are corrected. Next, in step s220, the CPU 21 determines whether or not the valve opening period VT1 of the intake valve 7 is equal to or longer than the fuel injection period T1. If the opening period VT1 is equal to or longer than the fuel injection period T1, the process proceeds to step s230. When the opening period VT 1 is shorter than the fuel injection period T 1, fuel is injected even when the valve is closed because the opening period of the valve is shorter than the fuel injection period. Therefore, since the injected fuel adheres to the intake pipe 5, a process for preventing this is performed in step s240 and thereafter.

On the other hand, if the opening period VT1 is shorter than the fuel injection period T1, in step s290, the CPU 21 sets the opening period VT1 of the intake valve to be the same as the fuel injection period T1 and the opening period VT1. Recalculate. Also, the valve lift amount VL1 is calculated.

Further, in step s295, the CPU 21 reduces the opening of the throttle valve by the length of the opening period VT1 of the intake valve, and reduces the opening of the throttle valve THAI so that the amount of air to be sucked is the same. Is calculated again.

Next, in step s230, the CPU 21 calculates the fuel injection timing FIT1 such that the end time of the fuel injection period T1 is earlier than the end time of the opening period VT1 by the injection timing correction time T2. I do.

Then, the CPU 21 controls the fuel injection valve 11, the throttle valve 13, the spark plug 16, and the variable valve mechanism 26 so that these calculated values are obtained.

Next, a specific operation will be described with reference to FIGS. Here, it is assumed that the cold start is performed as in the embodiment of FIG. 1 and the operating conditions are such that the accelerator is not opened immediately after the engine is started. '

FIG. 14 is a timing chart showing an operation at the time of a complete explosion of an internal combustion engine equipped with a variable intake valve according to the third embodiment of the present invention. The horizontal axis indicates time T (ms). The crank angle is shown in parentheses. The upper part of Fig. 14 shows the fuel injection valve 6 Indicates the lift amount FVL (um). The lower part of FIG. 14 shows the lift amount VL (mm) of the intake valve. In FIG. 14, the solid line B indicates the opening period of the intake valve when the correction of steps s290 to s29.5 in FIG. 2 is performed, and the broken line A indicates the opening period before the correction is performed. ing.

The operation in the cranking state by star evening is the same as that of the embodiment shown in FIG. Next, the operation during continuous operation immediately after the complete explosion will be described.

The signals from the accelerator opening sensor 10, the water temperature sensor 12, and the crank angle sensor 19 are input to the input circuit 24 by the processing of steps s100 to s120, and the CPU 21 uses these signals to input the accelerator opening, water temperature TW, and engine rotation. The number NE is calculated. Since the fuel pressure RP is kept constant, the process in step s130 is not performed. Here, for example, it is assumed that the accelerator opening ACD = 0 degree, the water temperature TW = 20t :, and the engine speed NE = 1200 r / min. This result is stored in the RAM 23 and updated sequentially.

The process of step s175 is executed, but the fuel injection amount is the same as that at the time of cranking, the fuel injection rate I RT = 1.2 mgZms, and the fuel injection period T 1 = 10 ms.

By the process of step s180, the intake air amount is determined by the opening timing and the opening period, and since the influence of the engine speed is small, the opening timing of the intake valve V〇T 1 is set to 60 ° AT DC, and the opening period is set to the crank angle of 50 °, the maximum lift is lmm. That is, as shown in the lower part of Fig. 14, the intake valve starts to open at 60 ° ATDC and opens for 50 ° up to 110 ° A TJDC, and the maximum lift at that time is assumed to be 0.8 mm. You.

Next, in the determination of step s220, at a rotational speed of 1200 rZmin, the crank angle 50 °, which is the opening period of the intake valve, becomes 6.94 ms, and the opening period VT 1 (6.92 ms) becomes the fuel injection period T l (10 ms), and it is necessary to change the opening period VT 1 of the intake valve. Therefore, the process proceeds to step s290.

Then, by the processing of step s290, the CPU 21 controls the opening period VT1 and the valve lift amount VL1 so that the opening time is constant and the opening period VT1 is the same as the fuel injection period T1. And the throttle valve opening T The HA 1 is closed and a negative pressure is generated in the intake pipe 5 to control the throttle valve opening THAI so that the intake air amount MF 1 becomes the target value. Here, the opening period VT 1 is a crank angle of 72 °, the lift amount VL 1 is 1 mm, and the CPU 21 determines that the intake valve opening timing V AT 1 = Control so that 38 ° ATDC and opening period VT 1 = 72 °. In addition, the throttle valve opening THAI is closed by 40 °. The relationship between the opening period VT 1 and the throttle valve opening TH A 1 uses a force stored in the ROM 22 as a map and feedback control by the air-fuel ratio sensor 15.

Further, as shown in the upper part of FIG. 14, the CPU 21 sets the fuel injection timing to 20 ° ATDC and outputs a signal from the output circuit 25 to the fuel injection valve 11 when the crank angle is 20 ° ATDC. Is controlled as follows.

When the intake stroke starts and the piston 3 starts to fall from the top dead center position, the pressure in the combustion chamber 4 decreases because the intake valve 7 is closed. Then, as shown in the lower part of FIG. 14, the intake valve と opens at 38 ° ATDC, but since the pressure in the combustion chamber 4 is lower than the pressure in the intake pipe 5, the intake A high-speed airflow is generated from the pipe 5 to the combustion chamber 4. Further, by making the lift amount of the intake valve 7 small, the speed of the airflow sucked into the combustion chamber 4 by lowering the piston 3 can be maintained at 180 to 200 m / sec.

On the other hand, as shown in the upper part of Fig. 14, when the temperature reaches 20 ° ATDC, fuel is injected from the fuel injection valve 11 and the fuel spray reaches the vicinity of the intake valve 7 in about 2.5 ms, and is set to a small lift. It flows into the combustion chamber 4 by the high-speed airflow generated by this. At this time, the particles are atomized by the shearing force with the high-speed airflow at the passage through the gap between the intake valve 7 and the combustion chamber 4. The fuel injection ends at 92 ° ATDC, and at 110 ° the intake valve 7 closes when the last part of the fuel spray flows into the combustion chamber 4. The spray atomized by the high-speed air flow is easy to vaporize, and because it is easy to get on the air flow, it does not adhere to the cylinder wall, and a homogeneous mixture is formed. Therefore, when the piston reaches the top dead center, the ignition plug 31 stably burns after ignition.

As described above, according to the present embodiment, by setting the opening period VT 1 of the intake valve to be equal to or less than the fuel injection period T 1, a homogeneous mixture is formed without combustion on the cylinder wall and burned. As a result, the amount of unburned fuel discharged can be reduced. In each of the above embodiments, the same effect can be obtained by using an electromagnetic variable valve instead of a mechanical valve as the magnetic valve. Industrial potential

According to the present invention, the fuel injection period is made shorter than the opening period of the intake valve to prevent the fuel from adhering to the wall surface at the time of supplying the fuel, and the fuel spray can be atomized to reduce unburned fuel. Become.

Claims

The scope of the claims

1. In an internal combustion engine equipped with a variable intake valve that can change the opening timing, opening period, and lift of the intake valve,

When the fuel injection period of the fuel injection valve (11) is longer than the opening period of the intake valve (7)), the fuel injection amount or intake air amount per unit time is varied to change the fuel of the fuel injection valve. An internal combustion engine equipped with a variable intake valve, comprising a control means (20) for controlling an injection period to be equal to or shorter than an opening period of the intake valve.

2. An internal combustion engine provided with the variable intake valve according to claim 1,

During low load operation, the control means (20) sets the opening timing of the intake valve (7) to the intake stroke, and controls the opening period and lift amount of the intake valve to reduce the intake air amount. Adjust,

Further, the control means (20) increases a fuel injection amount per unit time of a fuel injection valve (7) provided with an injection rate variable mechanism (32; 34) capable of changing a fuel injection rate. And controlling the fuel injection period of the fuel injection valve to be equal to or shorter than the opening period of the intake valve.

3. An internal combustion engine provided with the variable intake valve according to claim 2,

The injection rate variable mechanism capable of changing the fuel injection rate is a mechanism (32) capable of changing a lift amount of a valve body of a fuel injection valve that controls fuel discharge.

The internal combustion engine, wherein the control means increases the lift amount of the valve body to increase the fuel injection amount per unit time of the fuel injection valve.

4. An internal combustion engine equipped with the variable intake valve according to claim 2,

The injection rate variable mechanism capable of changing the fuel injection rate is a mechanism (34) capable of changing the fuel pressure of a high-pressure fuel feed pump.

The internal combustion engine, wherein the control means increases the fuel pressure to increase the fuel injection amount per unit time of the fuel injection valve.

5. An internal combustion engine equipped with the variable intake valve according to claim 1,

During low load operation, the control means (20) sets the opening timing of the intake valve to the intake stroke, and sets the opening period and lift amount of the intake valve and the throttle valve (1) provided upstream of the intake pipe. 3) controlling the opening degree so as to reduce the amount of intake air per unit time so as to control the fuel injection period of the fuel injection valve to be shorter than the opening period of the intake valve. organ.

6. An internal combustion engine equipped with the variable intake valve according to claim 1,

The control means (20) is characterized in that the fuel injection end timing is a timing earlier than the closing timing of the intake valve by a time required for the injected fuel spray to reach the intake valve. organ. '