JPH0621599B2 - Fuel injection internal combustion engine with multiple intake valves - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fuel injection type internal combustion engine having a plurality of intake valves.

[Conventional technology]

As the air-fuel mixture supplied to the engine cylinder is made leaner, the fuel consumption rate can be improved. Therefore, in order to improve the fuel consumption rate, the air-fuel mixture supplied to the engine cylinder is made as lean as possible. Is desirable. However, when a lean air-fuel mixture is used, not only is the ignitability deteriorated, but even if it ignites, there is a problem that good combustion cannot be obtained because the flame propagation speed is slow.

In order to solve such a problem, the intake passage is tangentially extended to the inner peripheral wall surface of the combustion chamber, the fuel injection valve is arranged in the intake passage, and the fuel injection from the fuel injection valve An internal combustion engine is known in which the valve is stopped a little before closing the valve (JP-A-56-148636). In this internal combustion engine, only air is supplied into the combustion chamber in the first half of the intake stroke during partial load operation, and injected fuel is supplied into the combustion chamber in the latter half of the intake stroke, so a rich mixture layer is formed at the top of the combustion chamber. A lean mixture layer is formed below the combustion chamber to stratify the combustion chamber. As a result, the rich air-fuel mixture gathers around the spark plug to improve the ignitability, and the swirling flow is generated in the combustion chamber by the air flow flowing from the intake passage, so that the ignition flame can be rapidly propagated into the combustion chamber. be able to.

By the way, in the case of stratifying in this way, if the air-fuel ratio of the entire stratified air-fuel mixture is kept constant, combustion can be improved by increasing the degree of stratification.
For example, when the air-fuel ratio of the entire stratified air-fuel mixture is 25 and the air-fuel ratio of the rich air-fuel mixture is 20, the air-fuel ratio of the lean air-fuel mixture is 30, and the air-fuel ratio of the rich air-fuel mixture is 15, the air-fuel ratio of the lean air-fuel mixture is Considering the case where the air-fuel ratio is 35, the latter case provides better combustion than the former case. That is, even if the air-fuel ratio of the rich air-fuel mixture is 20, ignition can be ignited by the spark plug, but the flame due to combustion of the rich air-fuel mixture is weak, and as a result it takes time to burn the lean air-fuel mixture. It is difficult to get good combustion. On the other hand, when the air-fuel ratio of the rich mixture is 15, the flame due to the combustion of the rich mixture is strong, and in this case, therefore, even if the lean mixture is leaner, it is necessary to burn the lean mixture. The time is short and thus good combustion is obtained. To obtain such good combustion, it is necessary to increase the degree of stratification.

However, in the above-mentioned internal combustion engine, since the injected fuel flows into the combustion chamber at a high speed together with the intake air flow, the injected fuel is likely to spread into the combustion chamber, and thus stratification is performed, but the degree of stratification is not sufficient. .

In order to solve such a problem, a first intake valve and a second intake valve are provided, and the first intake passage connected to the combustion chamber via the first intake valve is formed in a helical shape, An internal combustion engine in which an intake control valve that opens during high load operation is provided in a second intake passage that is connected to a combustion chamber via an intake valve, and a fuel injection valve is provided in a second intake passage downstream of the intake control valve. An institution has already been proposed by the applicant (Japanese Patent Application No. 59-69176).
No.). In this internal combustion engine, since the intake control valve is held in the open state during the partial load operation, if the second intake valve opens during the intake stroke, the pressure in the second intake passage downstream of the intake control immediately approaches the pressure in the combustion chamber. Fall to. As a result, since the pressure difference in the second intake passage downstream of the intake control valve and the pressure difference in the combustion chamber are maintained at a relatively small pressure difference, the fuel injected into the second intake passage burns at a slow speed. Flows into the room. Therefore, the injected fuel does not spread so much into the combustion chamber, and thus the degree of stratification can be increased.

[Problems to be Solved by the Invention] However, in this internal combustion engine, when the second intake valve is opened in the latter half of the intake stroke in order to increase the degree of stratification, the injected fuel in the second intake passage has a slow speed. Since all the injected fuel cannot flow into the combustion chamber because it only flows into the combustion chamber, the injected fuel that could not flow into the combustion chamber at the moment when the second intake valve opens in the next intake stroke. However, when the injected fuel, which could not flow in the previous intake stroke, flows into the combustion chamber at the moment when the second intake valve opens in this way, the injected fuel gathers in the central portion of the combustion chamber, and therefore, is good. There is a problem that it is not possible to obtain proper stratification. On the other hand, if the opening timing of the second intake valve is advanced in order to supply all the injected fuel into the combustion chamber during the intake stroke, the injected fuel in the second intake passage will be supplied into the combustion chamber from the early timing of the intake stroke. Therefore, also in this case, it is difficult to obtain good stratification. That is, when it is intended to achieve stratification by closing the intake control valve provided in the second intake passage, no matter how the opening timing of the second intake valve is set, good stratification is achieved. Can't get

The present invention enhances the degree of stratification by always opening the second intake passage and appropriately controlling the completion timing of fuel injection,
As a result, a fuel injection type internal combustion engine that ensures good combustion is provided. The applicant (Japanese Patent Application No. 60-56126) describes an internal combustion engine in which the second intake passage is always open. However, in this internal combustion engine, sufficient consideration is given to the completion timing of fuel injection. It is difficult to obtain good stratification because it is not present.

[Means for solving problems]

In order to solve the above problems, according to the present invention, two intake valves including a first intake valve and a second intake valve and two intake passages including a first intake passage and a second intake passage are provided. The first intake passage for generating a swirling flow around the cylinder axis in the combustion chamber is connected to the combustion chamber via the first intake valve, and from the straight port connected to the combustion chamber via the second intake valve. In the fuel injection type internal combustion engine in which the fuel injection valve is arranged in the second intake passage, the first intake valve is opened from near the top dead center of the intake stroke to the beginning of the compression stroke, and the second intake valve is opened in the center of the intake stroke. The valve is opened from the vicinity to the beginning of the compression stroke, and the fuel injection completion timing of the fuel injection valve is gradually advanced from the end of the intake stroke to the beginning of the intake stroke as the engine speed increases.

〔Example〕

Referring to FIGS. 1 to 3, 1 is an engine body, 2 is a cylinder block, 3 is a piston that reciprocates in the cylinder block 2, 4 is a cylinder head fixed on the cylinder block 2, and 5 is a piston. Reference numeral 3 denotes a combustion chamber formed between the cylinder head 4 and 3, and 6 denotes a spark plug arranged at the top of the combustion chamber 5. No. 1 on the inner wall surface of the cylinder head 4.
Two intake valves consisting of the intake valve 7 and the second intake valve 8;
An exhaust valve 9 is arranged. The first intake valve 7 is the second intake valve 8
Has a larger valve diameter. In the cylinder head 4, two intake passages including a first intake passage 10 and a second intake passage 11 and an exhaust passage 12 connected to the combustion chamber 5 via an exhaust valve 9 are formed. The first intake passage 10 and the second intake passage 11 are separated from each other by a thin partition wall 13 and extend in the same direction in the cylinder head 4, and the second intake passage 11 has a cross section smaller than that of the first intake passage 10. The first intake passage 10 and the second intake passage 11 are connected to the same intake branch pipe 14 and join each other inside the intake branch pipe 14. The first intake passage 10 is connected to the inside of the combustion chamber 5 via a first intake valve 7, and the first intake passage 10 is connected to the combustion chamber 5.
It is formed in a helical shape to generate a swirling flow inside. The second intake passage 11 is connected to the combustion chamber 5 via the second intake valve 8.
Internally connected, this second intake passage 11 is formed as a straight port extending straight. Second intake passage 1
A fuel injection valve 15 is disposed on the upper wall surface of the fuel cell 1, and fuel is injected from the fuel injection valve 15 toward the back surface of the second intake valve 8.

Referring to FIG. 3, the intake branch pipe 14 is connected to a common surge tank 16, and the surge tank 16 includes an intake duct 17
Also, it is connected to an air cleaner (not shown) via the air flow meter 18. A throttle valve 19 connected to an accelerator pedal (not shown) is arranged in the intake duct 17, and a throttle switch 21 is connected to a valve shaft 20 of the throttle valve 19. This throttle switch 21
When the throttle valve 19 is almost fully opened, for example, when the throttle opening is 90 degrees when fully opened, it turns on when the throttle opening exceeds 80 degrees.

On the other hand, a distributor 22 is attached to the engine body 1, and the rotor 23 of the distributor 22 is driven by the engine at a rotation speed of 1/2 of the crankshaft. A pair of discs 24 and 25 are fixed to the rotor 23, and a pair of crank angle sensors 26 and 27 are arranged so as to face the toothed outer peripheral surfaces of the discs 24 and 25.
The crank angle sensor 26 is a sensor for determining whether or not the first cylinder is at the intake top dead center, and generates an output pulse when the first cylinder is at the intake top dead center. On the other hand, the crank angle sensor 27 has, for example, a crankshaft of 30.
An output pulse is generated every rotation. Therefore, the crank angle of each cylinder can be calculated from the output pulses of the crank angle sensors 26 and 27, and the engine speed can be calculated from the output pulse of the crank angle sensor 27. These crank angle sensors 26 and 27 are electronic control unit 5
Connected to 0.

The electronic control unit 50 comprises a digital computer, and ROMs connected to each other by a bidirectional bus 51.
A (read-on memory) 52, a RAM (random access memory) 53, a CPU (microprocessor) 54, an input port 55 and an output port 56 are provided. The air flow meter 18 generates an output voltage proportional to the intake air amount, and the air flow meter 18 is connected to the input port 55 via the AD converter 57. Furthermore, the input port 55
The throttle switch 21 and the crank angle sensor 2
6, 27 are connected. On the other hand, the output port 56 is connected to the fuel injection valve 15 of the corresponding cylinder via the drive circuits 58a, 58b, ....

The internal combustion engine according to the present invention has an average air-fuel ratio of 25 to 3 by stratifying the air-fuel mixture in the combustion chamber 5 during partial load operation.
It operates by using a lean air-fuel mixture such as 0, and in the engine high load operation, the air-fuel mixture in the combustion chamber 5 is made uniform and the average air-fuel ratio is made small in order to obtain high output. In order to increase the degree of stratification during partial load operation, it is necessary to appropriately set the opening timing of the second intake valve 8 and the injection completion timing of the fuel injection valve 15. After the basic operation is described, the valve opening timing of the second intake valve 8 and the injection completion timing of the fuel injection valve 15 will be described.

FIG. 4 shows the opening period of the first intake valve 7 and the second intake valve 8. In FIG. 4, the vertical axis L shows the valve lift, and the horizontal axis θ shows the crank angle. In FIG. 4, a curve A shows the opening period of the first intake valve 7. As you can see from curve A, the first
The intake valve 7 opens slightly before the top dead center (TDC) of the intake stroke, and closes at the beginning of the compression stroke just beyond the bottom dead center (BDC) of the intake stroke. On the other hand, the opening period of the second intake valve 8 is shown by the curve B in FIG. As can be seen from the curve B, the second intake valve 8 opens at approximately the center of the intake stroke, and closes at the same time as the first intake valve 7. The opening timing of the second intake valve 8 needs to be set substantially at the center of the intake stroke, but there is some freedom regarding the closing timing of the second intake valve 8. The intake valve 7 can be closed a little before the valve is closed, or can be closed a little after the first intake valve 7 is closed. Fuel injection valve 15
Although the injection timing will be described in detail later, roughly speaking, the fuel injection is completed before the second intake valve 8 is closed so that all the injected fuel is supplied into the combustion chamber 5.

When the first intake valve 7 is opened and the intake stroke is started during the partial load operation, intake air is supplied into the combustion chamber 5 through the first intake passage 10. As described above, since the first intake passage 10 is formed in a helical shape, the air swirls into the combustion chamber 5 while swirling, so that a strong swirling flow is generated in the combustion chamber 5. Since the second intake valve 8 opens when the piston 3 moves down by about half a stroke, the air-fuel mixture formed in the second intake passage 11 by the fuel injected from the fuel injection valve 15 passes through the second intake valve 8 and the combustion chamber. Inflow into 5. At the beginning of opening the second intake valve 8, since the valve lift of the second intake valve 8 is small, the amount of the air-fuel mixture flowing into the combustion chamber 5 is not small, and the air-fuel mixture is mixed with the swirling air to mix with the combustion chamber. 5
A lean mixture is formed near the top of the. At this time, only air is present near the top surface of the piston 3. Next, when the piston 3 further descends, the valve lift of the second intake valve 8 increases,
The air-fuel mixture flowing into the combustion chamber 5 from the second intake passage 11 gradually increases. In the latter half of the intake stroke, the valve lift of the first intake valve 7 gradually decreases, so the amount of intake air flowing into the combustion chamber 5 from the first intake passage 10 decreases, while the second intake valve 8 Since the valve lift is increased, the amount of air-fuel mixture flowing into the combustion chamber 5 from the second intake passage 10 is increased. Therefore, the air-fuel mixture formed on the top of the combustion chamber 5 gradually becomes richer. This tendency becomes stronger as the first intake valve 7 approaches the closing timing, and thus when the first intake valve 7 and the second intake valve 8 are closed, a rich mixture is collected at the top of the combustion chamber 5, The concentration of the air-fuel mixture gradually decreases toward the piston 3, and only air is present on the top surface of the piston 3. Next, when the compression stroke is started, the air on the top surface of the piston 3 mixes with the surrounding lean air-fuel mixture to become a lean air-fuel mixture, so at the end of the compression stroke, a rich air-fuel mixture gathers at the top of the combustion chamber 5 and the piston 3 A lean air-fuel mixture gathers near the top surface. Thus, the air-fuel mixture in the combustion chamber 5 is stratified. Since the rich air-fuel mixture is gathered at the top of the combustion chamber 5, the rich air-fuel mixture is gathered around the spark plug 6, and therefore the air-fuel mixture can be easily ignited. At this time, since a swirling flow is generated in the combustion chamber 5, the ignition flame rapidly spreads in the combustion chamber 5.

As described above, in order to obtain good combustion in the case of stratification, it is necessary to increase the degree of stratification, and for that purpose, the opening timing of the second intake valve 8 and the injection completion timing of the fuel injection valve 15 are set appropriately. Must be specified in. That is, if the opening timing of the second intake valve 8 is advanced, the degree of stratification becomes small because the air-fuel mixture is supplied into the combustion chamber 5 from the beginning of the intake stroke. On the other hand, if the opening timing of the second intake valve 8 is delayed, all the injected fuel cannot flow into the combustion chamber 5 while the second intake valve 8 is open, and the fuel that could not flow is the second intake passage. 11 and stays in the second intake valve 8 in the next intake stroke.
When the valve opens, the fuel flows into the combustion chamber 5 all at once. However, if the fuel thus accumulated flows into the combustion chamber 5 at once immediately after the opening of the second intake valve 8, a rich mixture is formed in the combustion chamber 5 in the middle of the intake stroke, so that the degree of stratification is no longer present. Can not be raised. According to an experiment conducted by the present inventor, it has been found that the degree of stratification can be maximized by setting the valve opening timing of the second intake valve 8 at approximately the center of the intake stroke. The valve opening timing of the valve 8 is set substantially at the center of the intake stroke.

Next, as described above, if the injected fuel stays in the second intake passage 11, good stratification cannot be obtained, and the acceleration response also deteriorates. Therefore, all the injected fuel is burned during the intake stroke. It is necessary to let it flow into the chamber 5. in this case,
If the fuel injection is performed too early, the fuel stays in the second intake passage 11, and the stayed fuel flows into the combustion chamber 5 when the second intake valve 8 opens, so that the degree of stratification becomes small. I will end up. That is, it is necessary to delay the fuel injection timing as much as possible. By the way, according to an experiment conducted by the present inventor, the injected fuel is on the inner wall surface of the second intake passage 11 or the back surface of the second intake valve 8 by about the intake bottom dead center (BDC) shown by the chain line C in FIG. It has been proved that all the injected fuel can be supplied into the combustion chamber 5 if it has reached. Fuel injection valve 15
It takes a certain time for the fuel injected from the fuel tank to reach the back surface of the second intake valve 8 at the rear of the bulge portion. This time is almost constant, but if this time is converted into a crank angle, it changes according to the engine speed. Will be done. That is, the crank angle at which the injected fuel reaches the rear surface of the second intake valve 8 at the rear of the bulk becomes larger as the engine speed becomes higher. Therefore, in order for the last injected fuel to reach the back surface of the second intake valve 8 near the bottom dead center of the intake air, the injection completion timing of the fuel injection valve 15 must be advanced according to the increase of the engine speed. I won't. Further, the time taken for the injected fuel to reach the rear surface of the second intake valve 8 at the rear of the bulge portion also changes depending on the flow velocity of the intake air flowing in the second intake passage 11. That is, as the engine speed becomes higher, the flow velocity of the intake air flowing through the second intake passage 11 becomes faster. Therefore, in terms of the flow velocity of the intake air, it is necessary to delay the injection completion timing as the engine speed becomes higher. is there.

The optimum fuel injection completion timing considering the flow velocity of the intake air is shown by the curve D in FIG. The vertical axis N in FIG.
Indicates the engine speed, and the horizontal axis θ indicates the crank angle. As can be seen from the curve D, the injection completion timing represented by the crank angle θ is generally advanced as the engine speed N is increased. However, when the engine speed N increases, the flow velocity of the intake air flowing through the second intake passage 11 increases, so the amount of change in the injection completion timing with respect to the increase in the engine speed N decreases. If the fuel injection is completed at the crank angle indicated by the curve D in FIG. 4, regardless of the engine speed N, the last injected fuel is the second intake valve 8 near the intake bottom dead center.
Reaching the rear surface of the bulge, thus all the fuel is supplied into the combustion chamber 5 during the opening period of the second intake valve 8 and a large amount of air-fuel mixture is supplied into the combustion chamber 5 at the end of the intake stroke. Therefore, the degree of stratification can be increased. In FIG. 4, τ ₀ represents the control time from the injection completion timing to the intake bottom dead center, and τ represents the fuel injection period.

On the other hand, during engine high load operation, the amount of injected fuel is increased by a predetermined ratio, and the injection completion timing is set slightly before the first intake valve 7 opens as indicated by the chain line E in FIG. Τ ′ in FIG. 4 indicates the fuel injection period at this time. When the injection completion timing is advanced in this way, the injected fuel stays in the second intake passage 11 as described above,
Since this injected fuel is supplied into the combustion chamber 5 when the second intake valve 8 is opened, the degree of stratification becomes low. Further, since the fuel accumulated in the second intake passage 11 is sucked out into the first intake passage 10 by the intake air flow flowing in the first intake passage 10, the air-fuel mixture also flows from the first intake passage 10 into the combustion chamber 5 Will be supplied within. Therefore, at the time of high load operation, the degree of stratification is extremely weakened and a nearly uniform air-fuel mixture is formed in the combustion chamber 5, so that even if the injected fuel is increased by a certain ratio, the surroundings of the spark plug 6 become extremely high. It does not become too rich. Therefore, good ignitability can be secured, and high output can be obtained by increasing the amount of injected fuel.

Next, the control of the fuel injection valve 15 will be described with reference to the flowcharts shown in FIG. 5 and FIG.

Referring to FIG. 5, first, at step 70, an output signal of the crank angle sensor 27 representing the engine speed N and an air flow meter 18 representing the intake air amount Q.
The output signal of is taken into the CPU 54, and Q / N is calculated in step 71. This Q / N represents the amount of air taken into each cylinder per cycle, and therefore Q / N
N corresponds to the engine load. Next, at step 72, the basic fuel injection pulse width τ _p is obtained from the equation τ _p = K ₁ · Q / N. Here, K ₁ is a constant. Next, at step 73, it is judged if the throttle switch 21 is on, that is, if the throttle valve 19 is almost fully opened. If the throttle valve 19 is not substantially fully opened, the routine proceeds to step 74, where it is judged if the engine speed N is higher than a predetermined speed N ₀ , for example 3000 rpm. When N ≦ N _0, the routine proceeds to step 75, where the control time τ ₀ from the injection completion timing to the intake bottom dead center is calculated. FIG. 7 shows the relationship between the control time τ ₀ and the engine speed N. The relationship shown in FIG. 7 is stored in advance in the ROM 52 in the form of a function or a data table. Next, at step 76, the increase count K _{2 is set} to 1.0.
And proceed to step 77. In step 77, the fuel injection pulse width τ is calculated from the equation τ = K ₂ · K ₃ · τ _p + τ _r . Here, K ₃ is a correction count and τ _r is an invalid injection time. Next, at step 78, the fuel injection valve 15
The injection start timing θ _{1 of} is calculated from the equation θ ₁ = θ ₀ − (τ + τ ₀ ). Here, θ ₀ indicates the crank angle of the intake bottom dead center. τ is the crank angle at which fuel injection is performed, τ ₀
Indicates the control time represented by the crank angle. Therefore, at step 78, the injection start crank angle θ ₁ is calculated with reference to the intake bottom dead center. Next, at step 79, θ
_The injection completion crank angle θ ₂ with the intake bottom dead center as a reference is calculated from the formula ₂ = θ ₀ −τ ₀ . Next, at step 80, the injection start crank angle θ ₁ and the injection completion crank angle θ ₂ thus calculated are stored in the RAM 53.

On the other hand, when it is determined in step 73 that the throttle switch 21 is on, or when it is determined in step 74 that N> N ₀ , the routine proceeds to step 81. In step 81, a constant value G is set in the control time τ ₀ . This constant value G is, as shown in FIG. 4, the intake bottom dead center C from the crank angle E slightly before the opening of the first intake valve 7.
Up to the crank angle. Next, at step 82, the increase count K ₂ is obtained. This increase count K ₂ is determined by Q / N and N as shown in FIG. 8, and each increase count K ₁₁ ... K _mn shown in FIG. 8 is stored in advance in the ROM 52 in the form of a map. This increase count K ₂ is larger than 1.0, and increases as Q / N and N increase. Next, at step 77, the fuel injection pulse width τ is obtained, but since K ₂ is larger than 1.0, the amount of fuel is increased. Further, in step 79, the injection completion crank angle θ ₂ is obtained, but τ ₀ is a constant value G, so the fuel injection completion timing is fixed to the crank angle slightly before the opening of the first intake valve 7. Become.

FIG. 6 shows a fuel injection processing routine. This routine is performed by a time interrupt. Referring to FIG. 6, first, at step 90, the crank angle sensor 2
The current crank angle CA is calculated from the output pulses of 6,27. Next, at step 91, the current crank angle CA
There is discriminated whether or not ₁ theta injection start crank angle stored in the RAM 53, the data should be started fuel injection proceeds to step 92, if the injection start crank angle theta ₁ is output to an output port 56 Fuel injection from the fuel injection valve 15 is started. On the other hand, whether the current crank angle CA proceeds to step 93 is injection completion crank angle theta ₂ is discriminated and when not, the injection start crank angle theta _1, in step 94, if the injection completion crank angle theta ₂ The data which should advance and stop fuel injection is output to the output port 56, and the fuel injection from the fuel injection valve 15 is stopped.

Therefore, as can be seen from the flowchart shown in FIG. 5, when the opening degree of the throttle valve 19 is smaller than the predetermined opening degree and the engine speed is lower than the predetermined speed N ₀ , the fuel injection is performed as shown in FIG. It is completed at the time shown by the curve D of. As a result, the degree of stratification increases as described above, and thus good combustion can be obtained.
Further, when the second intake valve 8 is opened, intake air flows in the second intake passage 11, so that the vaporization of the injected fuel is promoted, and thus good ignitability can be secured. On the other hand, when the throttle valve 19 is almost fully opened or the engine speed N is higher than the predetermined speed N _{0, the} fuel injection is the fourth.
It is completed at a fixed time indicated by a chain line E in the figure. As a result, the degree of stratification is weakened as described above, and a substantially uniform air-fuel mixture is formed in the combustion chamber 5. Further, at this time, the amount of fuel is increased and the average air-fuel ratio is reduced, but the degree of stratification is weakened so that the air-fuel mixture around the spark plug 6 does not become excessively rich, thus ensuring good ignitability. be able to. Higher output can be obtained by further reducing the average air-fuel ratio.

FIG. 9 shows another flowchart for obtaining the injection start crank angle θ ₁ and the injection completion crank angle θ ₂ . Referring to FIG. 9, steps 100 to 102 are steps 70 to 7 in FIG.
Since it is the same as 2, the description thereof will be omitted. Step 103
Then, it is determined whether or not Q / N is larger than a constant value H, that is, whether or not a high load operation is being performed. . If not under high load operation, the routine proceeds to step 104, where it is judged if the engine speed N is higher than a predetermined speed N ₀ . N
≦ If _{N 0} to increase the count _{K 2} in step 105 1.0 is placed. Next, at step 106, the fuel injection pulse width τ = K ₂ · K ₃ · τ _p + τ _r is calculated. Next, at step 107, the injection start crank angle θ ₁ is obtained from the map. That is, the relationship between the injection start crank angle θ ₁ and Q / N, N as shown in FIG. 10 is stored in advance in the ROM 52 in the form of a map.
The injection start crank angle θ ₁ is calculated from the data θ ₁₁ , θ ₁₂ ... θ _mn stored in M52. Next, at step 108, the injection completion crank angle θ ₂ is calculated from the formula θ ₂ = θ ₁ + τ, and then at step 109, θ ₁ and θ ₂ are RA
It is stored in M53. On the other hand, when Q / N> H or N> N ₀ , the increase count value K ₂ is obtained in step 110 from the map stored in the ROM 52 shown in FIG. The major difference between this embodiment and the embodiment shown in FIG.
In the embodiment shown in the figure, the injection start crank angle θ ₁ is calculated, whereas in the embodiment shown in FIG. 9, the injection start crank angle θ ₁ is stored in advance in the ROM 52 in the form of a map. Is.

〔The invention's effect〕

Since the degree of stratification in the combustion chamber can be increased, good combustion can be obtained even with a lean air-fuel mixture having an average air-fuel ratio of 25 to 30.

[Brief description of drawings]

FIG. 1 is a side sectional view of an internal combustion engine, FIG. 2 is a plan sectional view of FIG. 1, FIG. 3 is an overall view of the internal combustion engine, and FIG. 4 is a line showing an intake valve opening period and an injection completion timing. 5 and 5 are flowcharts for obtaining an injection start crank angle and an injection completion crank angle, FIG. 6 is a flowchart for fuel injection processing, and FIG. 7 is a diagram showing the relationship between control time and engine speed.
FIG. 8 is a diagram showing the increment count stored in the ROM, FIG.
FIG. 10 is a flowchart of another embodiment, and FIG. 10 is a diagram showing the injection start crank angle stored in ROM. 5 ... Combustion chamber, 6 ... Spark plug, 7 ... First intake valve, 8 ... Second intake valve, 10 ... First intake passage, 11 ... Second intake passage, 15 ... Fuel injection valve .

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Taiyo Kawai 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Tokuhisa Nakagawa 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation ( 72) Inventor Kei Nomura 1 Toyota-cho, Toyota City, Aichi Prefecture Toyota Motor Corporation (56) References JP-A-58-204959 (JP, A)

Claims (1)

[Claims] 1. A combustion engine comprising a first intake valve and a second intake valve, two intake valves, and a first intake passage and a second intake passage. The first intake passage for generating the swirling flow of the fuel is connected to the combustion chamber via the first intake valve, and the fuel is introduced into the second intake passage formed of the straight port connected to the combustion chamber via the second intake valve. In a fuel injection internal combustion engine having an injection valve, the first intake valve is opened from near the top dead center of the intake stroke to the beginning of the compression stroke, and the second intake valve is opened from near the center of the intake stroke to the beginning of the compression stroke. A fuel injection internal combustion engine having a plurality of intake valves that gradually advances the fuel injection completion timing of the fuel injection valve from the end of the intake stroke to the beginning of the intake stroke as the engine speed increases.