JPS6183480A - Double-intake valve engine - Google Patents

Abstract

PURPOSE:To prevent a change of torque, increase of a harmful component quantity in exhaust gas and worsening of a fuel consumption rate when an intake control valve is opened, by an intake control valve opening and closing the second intake port, subfuel injection valve provided in the upstream of a collection part, etc. CONSTITUTION:In a range of low and intermediate speed and load, an engine, closing an intake control valve 7 by a signal from a control circuit 25, generates in a combustion chamber a strong swirl S from the first intake valve 4. A main injector 32 supplies most of the required fuel, while a subinjector 33 supplies a part of the fuel or stops its supply. While the engine, for obtaining high torque and a high output in the range of high speed and high load, opens the intake control valve 7 by a signal from the control circuit 25 so as to enable air to be sucked also from the second intake port 3, further the whole part of the required fuel is supplied from the subinjector 33.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an improvement in fuel injection side control in a dual intake valve engine.

Prior Art Conventionally, in order to improve fuel efficiency and reduce exhaust gas emissions, a configuration has been proposed in which the first intake port is, for example, helical, the second intake port is straight, and the 22nd intake port is provided with a fuel injection valve. (See, for example, Japanese Patent Application No. 58-228399 filed by the present inventors).

The second intake port is provided with an intake control valve, and this intake control valve is closed in a low engine load range. When the intake control valve is closed, fuel is injected into the center of the combustion chamber from the straight second intake port, while air is introduced from the helical first intake port so as to swirl along the inner circumference of the cylinder. be done. As a result, stratification is achieved in which the air-fuel ratio inside the cylinder is normal (for example, the air-fuel ratio is 25-30), but the area near the spark plug in the center of the combustion chamber is close to the stoichiometric air-fuel ratio (approximately 14.0), which is optimal for combustion. . Therefore, even though the air-fuel ratio is ultra-lean, combustion can be performed stably,
It is possible to reduce the amount of NOx component emissions and improve the fuel consumption rate.

However, in this prior art, when the intake control valve is closed, the stratification is carried out as intended, or when the intake control valve is open, the rich air-fuel mixture flows from the straight-shaped second intake port into a helical-shaped mixture. Only air is taken from the first intake port for four people. In this case, the swirl from the first intake port is canceled by the air-fuel mixture from the second intake port, and as a result, the fuel and air are not mixed well, resulting in torque fluctuations, and the amount of harmful components in the exhaust gas increases. Furthermore, there is a problem of worsening fuel consumption rate.

Problems to be Solved by the Invention The present invention has been made to solve the problems of the prior art, such as torque fluctuation when the intake control valve is open, increase in the amount of harmful components in exhaust gas, An object of the present invention is to provide a multiple intake valve engine capable of preventing deterioration of fuel consumption rate.

Means for Solving the Problems According to the present invention, a first intake port opens into a combustion chamber and is shaped to generate a swirl within the combustion chamber, and a straight second intake port opens into the combustion chamber. port, and a main fuel injection valve provided at the second intake port;
A multiple intake valve engine is provided that includes an intake control valve that opens and closes a second intake port upstream of a main fuel injection valve, and a sub fuel injection valve provided upstream of an intake pipe collection section.

During operation when the intake control valve is closed, fuel is mainly introduced from the main fuel injection valve, and during operation when the intake control valve is open, fuel is also supplied from the sub fuel injection valve. Fuel injection at high loads when the intake control valve is open is mainly performed by the sub-fuel injection valve, and since this sub-fuel injection valve is located upstream of the collecting section, the well-mixed air-fuel mixture is injected into the first port and the second port. It can be supplied into the combustion chamber from the port.

The configuration of the present invention is similar to that of the inventors' earlier application, Japanese Patent Application No. 58-237961, in that the air-fuel mixture is supplied from both the first intake port and the second intake port during high loads.
However, in the present application, instead of installing a fuel injection valve for each first intake port as in the previous application, a common sub-fuel injection valve is installed upstream of the collecting portion, which is a difference in structure.

Example The present invention will be explained below with reference to illustrated embodiments.

FIG. 1 shows an embodiment of the invention. In the figure, an intake passage 1 branches into a first intake port 2 and a second intake port 3 in the middle and communicates with a combustion chamber 100. A second intake valve 5 is provided on each of the two intake ports 3Φ combustion chamber side. The first intake port 2 has a helical shape and is designed to generate swirl within the combustion chamber. On the other hand, the second intake port 3 opens near the spark plug 6 provided in the upper center of the combustion chamber 100, and has a straight shape.

At the branch part of the first and second intake ports 2.3, there is a second
An intake control valve 7 that can open and close the intake port 3 is provided.

The intake control valve 7 is driven to open and close by an actuator 10, which will be described later. When the engine is operated at low rotation speeds and light loads, the second intake port 3 is closed, and when the engine is operated at high rotation speeds and high loads, the second intake port 3 is closed. Open port 3.

The actuator 10 has a diaphragm 1 inside the shell 11.
2 into an atmospheric chamber 13 and a variable pressure chamber 14, and the variable pressure chamber 14
It is configured such that atmospheric pressure or negative pressure can be selectively introduced into the tank. A rod 15 is fixed to the diaphragm 12,
This rod 15 is connected to the intake control valve 7 by engaging a long hole 16 formed at its tip with a pin 17 provided on the intake control valve 7 . A spring 18 is provided within the variable pressure chamber 14 to bias the diaphragm 12.

When negative pressure is introduced into the variable pressure chamber 14, the diaphragm 12 compresses the spring 18 and is displaced, causing the rod 15 to move to the right and the intake control valve 7 to close the second intake port 3 (
position indicated by the solid line in the figure). Conversely, when the inside of the variable pressure chamber 14 reaches atmospheric pressure, the diaphragm 12 is pressed by the spring 18 and moves to the left, and the intake control valve 7 opens the second intake port 3 via the rod 15 (indicated by the chain line in the figure). position shown).

A negative pressure switching valve (VSV) 20 applies negative pressure or atmospheric pressure to the variable pressure chamber 14 of the actuator 10.

That is, the negative pressure switching valve 20 is always in communication with the pressure transformation chamber 14 via the first conduit 21, and the fourteenth conduit 21 is connected to the second conduit 22, which is open to the air filter 30, or to the vacuum tank 23. It is designed to communicate with the 34th pipe 24. Switching of the valve body of the negative pressure switching valve 20 is performed by a control circuit 25, which will be described later. On the other hand, the vacuum tank 23 is connected to the intake passage 1 downstream of the throttle valve 27 via a check valve 28, so that negative pressure is maintained at all times during engine operation.

A main fuel injection valve (injector) 32 is provided for each cylinder in the middle of the straight second intake port 3 and downstream of the intake control valve 7. On the other hand, the sub fuel injection valve (injector) 33 is common to each cylinder, that is, it is the only one, and is provided upstream of the throttle valve 27 in the embodiment. The sub-fuel injection valve 33 may be installed at any position where fuel can be distributed to each cylinder, that is, upstream of the gathering point of each cylinder's intake pipe.
In order to improve fuel atomization and improve output, it is preferable to place the valve upstream of the throttle valve 27 as in the embodiment. On the other hand, if it is provided downstream of the throttle valve 27, the distance to the combustion chamber 100 can be shortened and transient response can be improved.

The control t'JR circuit 25 is a microprocessor (MPU)
34, an A/D converter 35, an input interface 36, an output interface 37, and a timing control circuit 38, which are interconnected by a lotus 39. The human power interface 36 has a rotational halus (crank angle pulse) of the engine crankshaft 101.
A crank angle sensor 40 is connected to detect the engine speed, and is used as a trigger for an interrupt routine for each crank angle. The A/D controller 35 is connected to a pressure sensor 41 for determining the intake pipe pressure downstream of the throttle valve 27 and an air flow sensor 42 for determining the amount of intake air passing through the throttle valve 27. Analog signals from these sensors are digitized in response to commands from MPU 34. Output interface 37
are connected to the respective fuel injection valves 32 and 33 via a main injection valve control circuit 44 and a sub fuel injection valve control circuit 46, and are also connected to the negative pressure switching valve 20 via an intake control valve control circuit 48. .

The MP[+ 34 includes a memory (not shown) in which a program for controlling the fuel injection valves 31, 32 and the intake control valve 7 according to the present invention is stored.

The operation of the configuration of the present invention described below is as follows. In the low-medium speed rotation and low-medium load range of the engine used during normal driving, the intake control valve 7 is closed by a signal from the control circuit 25 and the first
A strong swirl S is generated within the combustion chamber from the intake valve 4.

Most or all of the required fuel is supplied from the main injector 32, and a portion of the required fuel is supplied from the sub-injector 33, or the sub-injector 33 is stopped. Therefore, in the combustion chamber 100, good stratification is obtained in which the cylinder head side (near the spark plug 6) is a rich mixture, and the piston side is a lean mixture, and ultra-lean combustion and large-volume EGR are possible, which improves the fuel consumption rate and prevents harmful Emissions can be reduced.

On the other hand, in the high speed and high load range of the engine, in order to obtain high torque and high output, the intake control valve 7 is opened in response to a signal from the control circuit 25, allowing air to be taken in from the second intake port 3 as well. The entire amount of fuel is in the sub-injector 33
or the main injector and sub-injector each provide a mixture of approximately the same -8/F (
Measures will be provided. Therefore, insufficient mixing of fuel and unstable combustion can be prevented, the amount of harmful components emitted can be suppressed, and furthermore, good drivability can be achieved.

Software for realizing the above control is stored as a program in the memory of the control circuit 25. The outline of the program will be explained below using a flowchart.

FIG. 2 shows a control routine for the counter CNT used to control the opening/closing of the intake control valve 7 and to calculate the fuel distribution ratio from the fuel injection valves 32 and 33. Reference numeral 400 indicates the start of a routine, which is a time interrupt routine that is activated at certain fixed time intervals (for example, every 8 msec). Alternatively, it may be an interrupt routine that is activated at every fixed crank angle (for example, 180° CA). In step 401, data from the pressure sensor 41 is A/D converted by the A/D converter 35 and loaded into a register. In step 402, the difference ΔP between the A/D conversion value when this routine was passed last time and the current A/D conversion value is determined. = P bn P bn-1 is calculated. In the next step 403, it is determined whether the absolute value of ΔP is larger or smaller than a predetermined value ΔP, and if it is, this routine is ended. As a result, if P suddenly changes during gear change express racing, etc., the following routine is bypassed. If ΔP is smaller than Δp btb, the process advances to step 404 and the control counter (CNT
) is loaded. It is assumed that this CNT has been initially set to OO in an initial routine (not shown). Next, in step 405, P is set to the predetermined path.
It is determined whether the load is larger or smaller, and if it is larger, that is, on the high load side, the process proceeds to step 406, and if it is smaller, that is, on the light load side, the process proceeds to step 409. In step 406, CNT is decremented, so that the contents of one address in the memory that stores the value of counter CNT decreases by one for each interrupt process. As a result, when the counter value immediately before the decrement is counted down to φφ, the content of the address as a result of the execution of step 406 overflows with the FF. If there is an overflow as a result of decrementing in step 407, the value is 00 in step 408.
is set and the process proceeds to step 412.

On the other hand, in step 409, CNT is incremented, so that the contents of the memory address storing the count CNTO value increase by one. As a result, when the counter value immediately before incrementing is counted up to FF, the content of the address as a result of the execution of step 409 is φ
becomes φ and overflows. This overflow judgment is made in step 410, and if there is an overflow, F is determined in step 411.
Set F. In step 412, CNT is stored and the routine ends. As the routine shown in Fig. 2 is performed, when the intake pipe pressure increases (acceleration state) as shown in 7!1 in Fig. 5 (a), when the set value P exceeds (b) The value of the counter CNT starts to increase as ml, and the value of the counter CNT starts to increase until it reaches the hexadecimal number FF, which is the maximum value of the 8-bit memory cell, which is one address that stores the CNT data.
When the value is reached, the value is retained. Conversely, when the intake pipe pressure decreases as shown in 12 (deceleration pattern B>, pb), the value of the counter CNT begins to decrease and reaches φφ in hexadecimal.

Conversely, if you look at the value of counter CNT, it is a hexadecimal FF.
If so, it is determined that the load is stable and the intake control valve 7 should be opened, and if it is OO in hexadecimal notation, it is determined that the load is stable and the intake control valve 7 should be closed. can.

Furthermore, when the counter CNT is at an intermediate value between "o o" and "FF", it can be determined that it is a transient state, and as will be described later, the fuel injection is performed either before or after the operation of the intake control valve 7. Delay control such as control can be performed.

Also, in Figure 5, 6. ,jl! When the intake pipe pressure suddenly changes as shown at 4, the counter CNT is not controlled as a result of the steps 402 and 403 in FIG.

FIG. 3 shows the opening/closing routine of the intake control valve 7.

First, in step 601, the content of the address where CNT data is stored is loaded, and in step 6b2, it is determined whether the counter CNT is larger or smaller than a certain value CNT.

If it is, the process proceeds to step 603, where the MPU 34 controls the negative pressure switching valve 20 via the control circuit 48 from the output interface.
A demagnetizing signal is applied to. Therefore, the switching valve 20 takes the white port position, and
Atmospheric pressure from the air filter 30 acts on the spring 18
The force causes the diaphragm 12 to move to the left, and the intake control valve 7
is in the fully open position as shown by the broken line.

At 602, when counter CNT is lower than CNTth (N
o') is determined to be under low load, and in this case, the process proceeds to 604, where the control circuit 48 outputs an excitation signal for the negative pressure switching valve 20, and the switching valve 20 assumes the black port position, and the intake pipe negative pressure is increased. The voltage is transmitted to the variable pressure chamber 14 of the actuator 10. Therefore, the diaphragm 12 moves to the right against the force of the spring 18, and the intake control valve 7 assumes the fully open position shown by the solid line.

FIG. 4 shows a fuel injection control routine, in which signals are sent from the crank angle sensor 40 at every predetermined crank angle (for example, every 30 degrees).
An interrupt is entered by the signal.

Step 700 shows a routine for calculating the fuel injection time τ according to the operating conditions (for example, the rotational speed N) and the intake air amount ratio G/N as a load equivalent value. This routine itself is well known and is not a characteristic part of the present invention, so it will be shown in a simplified manner.
There is a map of fuel injection time according to /N in memory,
The fuel injection time τ corresponding to the actually measured N and Q/N is calculated in step 302. Such a map has a set air-fuel ratio range, for example, from 21st super lean in the low rotation and low load range to 12.5 in the high rotation and high load range, slightly lean. At 701, the value of the counter CNT is loaded, and then at 702 the value of the counter CNT is loaded.
Depending on the value of NT, the fuel injection ratios α, β (0<α<l, Q<
β〈1. α+β=1) is calculated. As shown in FIG. 6, when the intake control valve 7 is closed, α is increased and β is decreased for CN T =φφ, and the supply ratio from the main injector 32 is increased to obtain good stratification. When the intake control valve is open, α is small, and by increasing β and increasing the supply ratio from the sub-injector, the air-fuel mixture in the combustion chamber is kept constant. When the intake control valve 7 is switched from open to closed, the intake control valve 7 is closed first, and then the supply amount from the main injector 32 is increased, and conversely, when the intake control valve 7 is switched from closed to open, the supply amount from the sub-injector 33 is increased. The values of α and β are set so that the intake control valve 7 is opened after increasing the amount. Further, a slight hysteresis may be provided when the intake control valve 7 is switched from open to closed and from closed to open, as shown by the broken line in the figure. Actually, α and β are determined experimentally based on the shape and size of the intake pipe injector, but the bottom line is that good stratification is obtained when the intake control valve is closed, improving fuel consumption and reducing harmful component emissions. Also, since good stratification cannot be obtained when the intake control valve is closed, α and β are set so that the inside of the combustion chamber is as uniform as possible, and furthermore, the above objectives can be achieved even during transient periods.

In the next step 703, the injection/opening time (pulse width) τ9 of the injection pulse of the main fuel injection valve 32 is set as the closed value obtained by multiplying α by τ, and the injection/opening time (pulse width) τ9 of the injection pulse of the main fuel injection valve 32 is set as the value calculated by multiplying β by τ. 33 injection pulse-like opening times τ are set.

In step 704, the crank angle θ8 at which fuel injection from the main fuel injection valve 32 should be executed and the sub fuel injection valve 33 are determined.
The crank angle θ, at which fuel injection should be performed from 705 is calculated, and these τS, rM.

θ3. θ, lJ<MPU Set in the register of 34.

As is well known, the timing control circuit 38 has θi, θ,.

from the crank angle of the main and sub fuel injection valves 32
, 33 execute fuel injection for a period of τi, τ, from the output interface 37 to the respective control circuits 44,
46.

The above is one embodiment of the present invention, and the opening/closing of the intake control valve and the injection ratio of the main injector and sub-injector can be changed depending on various engines and operating conditions. This is because if the engine changes, the combustion chamber shape, intake pipe shape, and injector mounting position will change, so the optimal swirl and stratification degree will also change.

Also, when the engine is cold, the fuel injected from the sub-injector tends to adhere to the inner wall of the intake pipe, delaying fuel intake, and flowing into the combustion chamber in liquid form, so in that case, it is better to increase the supply amount from the main injector as much as possible. . Further, the opening/closing timing of the intake control valve and the main sub-injector injection ratio can be made variable depending on conditions such as engine rotation, intake air amount, and basic injection pulse width.

Effects of the invention In the normal usage range of low-medium speeds and low-medium loads, by stratifying the inside of the combustion chamber, a large lean burn IEGR is achieved, improving fuel consumption rate and reducing harmful component emissions.
In areas where high speed, high load, high torque and high output are required, abnormal combustion can be prevented and the conflicting demands of both operating ranges can be harmonized by installing one common sub-injector 33. The number of points is saved, the structure is streamlined, and it becomes compact.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of an embodiment of the present invention. Figures 2, 3, and 4 are flowchart diagrams showing the software configuration. Figure 5 shows changes in intake pipe pressure and counter value changes over time. Figure 6 is a graph showing changes in the injection ratios of the main and sub fuel injection valves with respect to the count value (CNT). 2...First intake port, 3...Second intake port, 7
...Intake control valve, 32...Main fuel injection valve,
33... Sub fuel injection valve, 100... Combustion chamber.

Claims (1)

[Claims] 1. A first intake port that opens into the combustion chamber and is shaped to generate a swirl within the combustion chamber, a straight second intake port that opens into the combustion chamber, and a straight second intake port that opens into the combustion chamber. main fuel injection valve,
A multiple intake valve engine that includes an intake control valve that opens and closes a second intake port upstream of the main fuel injection valve, and a sub fuel injection valve provided upstream of the intake pipe collection section.