JPH0340220B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a split operation controlled internal combustion engine.

In an internal combustion engine in which the engine load is controlled by a throttle valve, the fuel consumption rate worsens as the throttle valve opening becomes smaller. Therefore, in order to improve the fuel consumption rate, a split operation control type internal combustion engine is known in which some cylinders are deactivated when the engine is operated at low load, and the remaining cylinders are operated at high load. In this known internal combustion engine, the cylinders are divided into a first cylinder group A and a second cylinder group B, as shown in FIG. The second intake manifold 2 is connected, the first intake manifold 1 and the second intake manifold 2 are communicated with the atmosphere through a common throttle valve 3, and an intake cutoff valve 4 is connected to the intake air inlet of the first intake manifold 1. In addition, an exhaust recirculation valve 7 is provided in the exhaust recirculation passage 6 that connects the exhaust manifold 5 and the first intake manifold 1, and when the engine is operated at low load, fuel injection from the fuel injection valve 8 is stopped and the intake cutoff valve 4 is closed. close the valve and open the exhaust recirculation valve 7 to operate the second cylinder group B at high load,
On the other hand, during high-load engine operation, fuel is injected from all fuel injection valves 8 and 9, the intake cutoff valve 4 is opened, and the exhaust recirculation valve 7 is closed to cause all cylinders A and B to perform firing operation. . In this internal combustion engine, as mentioned above, when the engine is operated at low load, the intake cutoff valve 4 is closed and the exhaust recirculation valve 7 is opened, so that exhaust gas is circulated to the first cylinder group A via the exhaust recirculation passage 6. Therefore, pumping loss can be eliminated, and since the second cylinder group B is operated under high load at this time, the fuel consumption rate can be improved.

However, in this internal combustion engine, when the engine load reaches a predetermined load, the intake cutoff valve 4 is suddenly opened, and the exhaust recirculation valve 7 is suddenly closed, which prevents the supply of fuel especially to the first cylinder group. If the intake cutoff valve 4 and the exhaust recirculation valve 7 are suddenly opened and closed while the engine load is slowly increasing with the engine load starting, the engine output torque will fluctuate, causing This results in a problem that vehicle drivability deteriorates. On the other hand, if the opening and closing operations of the intake cutoff valve 4 and the exhaust recirculation valve 7 are made slow in order to solve this problem, a problem arises in that good acceleration cannot be obtained.

The present invention provides a split operation control type internal combustion engine that suppresses rapid fluctuations in engine output torque while ensuring good acceleration operation by changing the opening and closing speed of an intake cutoff valve according to the rate of change in engine load. It is about providing.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 2, 10 is the engine body, 11 is the first intake manifold, 12 is the second intake manifold,
13 is a surge tank, 14 is a first exhaust manifold, 15 is a second exhaust manifold, 16a, 16
b, 16c, 16d, 16e, and 16f indicate the first cylinder, the second cylinder, the third cylinder, the fourth cylinder, the fifth cylinder, and the sixth cylinder, respectively. Note that each of these cylinders is divided into a first cylinder group A consisting of cylinders 16a, 16b, and 16c, and a second cylinder group B consisting of cylinders 16d, 16e, and 16f. As can be seen from FIG. 2, the first intake manifold 11 and the first exhaust manifold 14 are connected to the first cylinder group A, and the second intake manifold 12 and the second exhaust manifold 15 are connected to the second cylinder group B. As shown in FIG. 2, each manifold branch pipe of the first intake manifold 11 and the second intake manifold 12 is provided with a fuel injection valve 1.
7a, 17b are attached, and the solenoid of each of these fuel injection valves 17a, 17b is connected to an electronic control unit 18. On the other hand, the first exhaust manifold 14 and the second exhaust manifold 15 are partitioned by a common partition wall 19 at their outlet portions, and both exhaust manifolds 1 are located within this partition wall 19.
An oxygen concentration detector 20 exposed within 4 and 15 is disposed. This oxygen concentration detector 20 is connected to the electronic control unit 18. Although not shown in the figure, a three-way catalytic converter is installed in the exhaust pipes connected to the outlet portions of the first exhaust manifold 14 and the second exhaust manifold 15. The first intake manifold 11 has an intake air inlet part 21 and branches from this intake air inlet part 21 to each cylinder 16a, 16b, 1.
It has three manifold branch pipes connected to the respective ports 6c, and the intake air inlet portion 21 is connected to the surge tank 13. Similarly, the second intake manifold 12 also includes an intake air inlet section 22 and an intake air inlet section 22.
The intake air inlet section 22 is connected to the surge tank 13. An intake duct 23 is attached to approximately the center of the surge tank 13, and a throttle valve 24 is disposed within the intake duct 23. This throttle valve 24 is connected via a wire to an accelerator pedal provided in the driver's cab of the vehicle. Furthermore, as shown in FIG. 2, an air flow meter 25 is attached to the intake duct 23, and this air flow meter 25 is connected to the electronic control unit 18 via a lead wire (not shown).
connected to.

The first intake manifold 1 as shown in FIG.
An intake cutoff valve 26 is disposed within the intake air inlet portion 21 of the intake air intake valve 1, and an arm 28 connected to a negative pressure diaphragm device 30 and a first changeover switch 29 are attached to a valve shaft 27 of the intake cutoff valve 26. As shown in FIG. 2, the negative pressure diaphragm device 30 has a pair of diaphragms 31 and 32 spaced apart from each other, and the inside of the negative pressure diaphragm device 30 is divided into a first Negative pressure chamber 33,
It is divided into three parts: a second negative pressure chamber 34 and an atmospheric pressure chamber 35. A compression spring 36 for pressing the diaphragm is inserted into the first negative pressure chamber 33, and a stopper 37 that is arranged to engage with the diaphragm 31 and can adjust the amount of displacement of the diaphragm 31 is provided in the housing of the negative pressure diaphragm device 30. be screwed on. Further, an engagement member 39 having an opening 38 is fixed on the surface of the diaphragm 31 exposed in the second negative pressure chamber 34.
A play coupling rod 40 having an enlarged head having a larger diameter than the aperture 38 and movable within the engagement member 39 is secured to the diaphragm 32. Additionally, a compression spring 41 is provided between the diaphragms 31 and 32.
is inserted and the diaphragm 32 is connected to the control rod 42.
It is connected to the tip of the arm 28 via. 1st
The negative pressure chamber 33 has a first electromagnetic switching valve 4 that can communicate with the atmosphere.
3 and the surge tank 13 via the negative pressure conduit 44.
The second negative pressure chamber 34 is connected to the inside of the surge tank 13 via a second electromagnetic switching valve 45 and a negative pressure conduit 47 that can communicate with the atmosphere. On the other hand, the first
The changeover switch 29 is connected to the valve shaft 27 of the throttle valve 26.
A movable contact 49 that rotates together with the movable contact 4
Three fixed contacts 50, 51, 52 that can be contacted with 9
These fixed contacts 50, 51, 52 are connected to the electronic control unit 18. Movable contact 49
is connected to a fixed contact 50 when the throttle valve 26 is fully open, connected to a fixed contact 51 when the throttle valve 26 is half open, and connected to a fixed contact 52 when the throttle valve 26 is fully closed.

On the other hand, the first exhaust manifold 14 upstream of the oxygen concentration detector 20 and the first intake manifold 11 downstream of the intake cutoff valve 26 are connected to each other by an exhaust gas recirculation passage 53. A type exhaust recirculation valve 54 is inserted. The exhaust gas recirculation valve 54 includes a negative pressure chamber 56 and an atmospheric pressure chamber 57 separated by a diaphragm 55.
A compression spring 58 for pressing the diaphragm is inserted inside. This negative pressure chamber 56 is connected to the inside of the surge tank 13 via a third electromagnetic switching valve 59 that can communicate with the atmosphere and a negative pressure conduit 60. The solenoid of the third electromagnetic switching valve 59 and the solenoids of the first and second electromagnetic switching valves 43 and 45 are controlled by the electronic control unit 18.
connected to. A valve body 61 that controls opening and closing of the exhaust gas recirculation passage 53 is disposed within the exhaust gas recirculation passage 53.
This valve body 61 is connected to the diaphragm 55 via a valve rod 62. Further, the exhaust gas recirculation valve 54 includes a second changeover switch 63. This second changeover switch 63 has a movable contact 64 connected to the diaphragm 55 and actuated by movement of the diaphragm 55, and a pair of fixed contacts 65, 66 that can come into contact with the movable contact 64. Contacts 65, 66 are connected to electronic control unit 18. The movable contact 64 is connected to the fixed contact 65 when the valve body 61 is closed, and is connected to the fixed contact 66 when the valve body 61 is opened. Incidentally, as shown in FIG. 2, a negative pressure sensor 67 for detecting the engine load is attached to the surge tank 13, and this negative pressure sensor 67 is connected to the electronic control unit 18. Further, a throttle sensor 68 is connected to the throttle shaft of the throttle valve 24 for detecting the rate of change in engine load. This throttle sensor 68 is a slider 6 connected to the throttle shaft of the throttle valve 24 and rotates together with the throttle valve 24.
9 and a fixed resistor 70. This fixed resistance 70
One end is grounded, and the other end is connected to a reference power source 71. On the other hand, the slider 69 is connected to the electronic control unit 1.
Connected to 8. As can be seen from FIG. 2, the output terminal of the throttle sensor 68 is connected to the throttle valve 24.
A voltage proportional to the opening is generated. Although not shown in FIG. 2, a rotation speed sensor 72 (FIG. 3) is attached to the engine body 10 to detect the engine rotation speed.

FIG. 3 shows a circuit diagram of the electronic control unit 18. Referring to FIG. 3, the electronic control unit 18
consists of a digital computer, including a microprocessor (MPU) 80 that performs various arithmetic operations;
Random access memory (RAM) 81, read-only memory (ROM) 82 in which control programs, calculation constants, etc. are stored in advance, and input port 83
In addition, output ports 84 are connected to each other via a bidirectional bus 85. Furthermore, the electronic control unit 1
8 is provided with a clock generator 86 for generating various clock signals. As shown in FIG. 3, the rotation speed sensor 72, the first changeover switch 29, and the second changeover switch 63 are connected to the input port 83 via corresponding buffer amplifiers 87, 88, and 89, respectively. In addition, the air flow meter 25 and the negative pressure sensor 67 are connected to the corresponding buffer amplifiers 90 and 9.
1 and AD converters 92 and 93, and the oxygen concentration detector 20 is connected to the input port 83 via a buffer 94 and a comparator 95. Furthermore, the throttle sensor 6
8 is connected to an input port 83 via a buffer 78 and an AD converter 79.

As mentioned above, the throttle sensor 68 generates an output voltage proportional to the opening degree of the throttle valve 24,
This output voltage is converted into a corresponding binary number by the AD converter 79 and then read into the MPU 80 via the input port 83 and the bus 85. The air flow meter 25 outputs an output voltage proportional to the amount of intake air, and this output voltage is converted into a corresponding binary number by the AD converter 92 and then sent to the input port 83.
It is also read into the MPU 80 via the bus 85. The rotation speed sensor 72 outputs continuous pulses with a period proportional to the engine rotation speed, and these continuous pulses are read into the MPU 80 via an input port 83 and a bus 85. The oxygen concentration detector 20 generates an output voltage of about 0.1 volt when the exhaust gas is in an oxidizing atmosphere, and generates an output voltage of about 0.9 volt when the exhaust gas is in a reducing atmosphere. This oxygen concentration detector 2
For example, the output voltage of 0 is determined by the comparator 95.
For example, when the exhaust gas is in an oxidizing atmosphere, an output signal is generated at one output terminal of the comparator 95, and when the exhaust gas is in a reducing atmosphere, an output signal is generated at the other output terminal of the comparator 95. Occur. The output signal of comparator 95 is transmitted via input port 83 and bus 85.
Loaded into MPU80. The negative pressure sensor 67 outputs an output voltage proportional to the negative pressure inside the surge tank 13, and this output voltage is converted into a corresponding binary number by the AD converter 93 and then sent to the MPU 80 via the input port 83 and bus 85. Loaded.
First changeover switch 29 and second changeover switch 6
3 contact switching signal is input port 83 and bus 8
5 to the MPU 80.

The output port 84 is provided to operate the fuel injection valves 17a, 17b and the electromagnetic switching valves 43, 45, 59, and binary data is written to the output port 84 from the MPU 80 via the bus 85. The output terminals of output port 84 are connected to down counters 96, 97, 98 and corresponding input terminals of latch 105. Each down counter 96, 97, 98 is provided to convert the binary data written from the MPU 80 into the corresponding time length, and these down counters 96, 97, 98 are A down count of the counted data is started by the clock signal of the clock generator 86, and when the count value reaches 0, the count is completed and a count completion signal is generated at the output terminal. The reset input terminal R of each S-R flip-flop 99, 100, 101 is connected to the output terminal of down counter 96, 97, 98, respectively.
The set input terminals S of 9, 100 and 101 are connected to a clock generator 86. These S-R flip-flops 99, 100, 101 are set by the clock signal of the clock generator 86 at the same time as the down count starts, and are reset by the counter completion signal of the corresponding down counters 96, 97, 98 when the down count is completed. Ru. Therefore S
-The output terminals Q of the R flip-flops 99, 100, 101 are connected to the corresponding down counters 96, 97,
The level remains high while the down count of 98 is being performed. S-R flip-flop 99,10
The output terminals Q of 0 and 101 are respectively connected to power amplification circuits 10.
2, 103, 104, the fuel injection valve 17a of the first cylinder group A, the fuel injection valve 17b of the second cylinder group B
and a first electromagnetic switching valve 43, respectively. Therefore, while the down counters 96, 97, 98 are counting down, the fuel injection valves 17a, 1
Fuel is injected from each of the first electromagnetic switching valves 4 and 7b.
3 is energized. On the other hand, the data for controlling the electromagnetic switching valve written in the output port 84 is held by the latch 105, and the data held by the latch 105 causes the electromagnetic control valves 45 and 59 to operate.

FIG. 4 and FIG. 5 show time charts for explaining the divided operation control method according to the present invention.
In Figures 4 and 5, the diagrams (a) to (h) indicate the following.

(a): Output voltage of negative pressure sensor 67.

(b): Control voltage applied to the solenoid of the first electromagnetic switching valve 43.

(c): Control voltage applied to the solenoid of the second electromagnetic switching valve 45.

(d): Control voltage applied to the solenoid of the third electromagnetic switching valve 59.

(e): Control pulse applied to the fuel injection valve 17b of the second cylinder group B.

(f): Control pulse applied to the fuel injection valve 17a of the first cylinder group A.

(g): Opening degree of the intake cutoff valve 26.

(h): Opening degree of the valve body 61 of the exhaust gas recirculation valve 54.

Note that FIG. 4 shows the transition from high load operation to low load operation, and FIG. 5 shows the transition from low load operation to high load operation.

Time T ₁ in FIG. 4 indicates a high load operation when the output voltage of the negative pressure sensor 67 is low. At this time, the fourth
As shown in FIG. b, the solenoid of the first electromagnetic switching valve 43 is deenergized, and therefore the first negative pressure chamber 33
communicates with the atmosphere via the first electromagnetic switching valve 43. At this time, as shown in FIG. 4c, the solenoid of the second electromagnetic switching valve 45 is also deenergized, and therefore the second negative pressure chamber 34 also
It communicates with the atmosphere through. As a result, both diaphragms 31 and 32 have moved furthest toward the atmospheric pressure chamber 35, and thus the intake cutoff valve 26 is fully open as shown in FIG. 4g. Furthermore, the time shown in Figure 4
At _T1 , the solenoid of the third electromagnetic switching valve 59 is deenergized, as shown in FIG. 4d, and therefore the negative pressure chamber 56 of the exhaust recirculation valve 54 is
9 to the atmosphere. In this way, the diaphragm 55 has moved furthest toward the atmospheric pressure chamber 57, and as a result, the valve body 61 completely closes the exhaust gas recirculation passage 53, as shown in FIG. 4h.

On the other hand, at this time, the MPU 80 shown in FIG. 2 calculates the engine rotation speed from the output pulse of the rotation speed sensor 72, and further calculates the basic fuel injection amount from this engine rotation speed and the output signal of the air flow meter 25. Furthermore, when a three-way catalyst is used, the purification efficiency is highest when the air-fuel ratio of the air-fuel mixture supplied into the engine cylinder reaches the stoichiometric air-fuel ratio; The fuel injection amount is calculated by correcting the basic fuel injection amount based on the output signal of the oxygen concentration detector 20 so that the fuel ratio approaches the stoichiometric air-fuel ratio. Data representing this fuel injection amount is written to the output port 84, and based on this data, pulses as shown in FIGS. 4e and 4f are sent to the fuel injection valves 17a of the first cylinder group A and the second cylinder It is applied to the group B fuel injection valves 17b. Therefore, during high-load engine operation, all fuel injection valves 17a,
Fuel is injected from 17b.

Next, if the high load operation is switched to the low load operation at time Ta in FIG. 4, the output voltage of the negative pressure sensor 67 will rise rapidly as shown in FIG. 4a. The MPU 80 determines that low load operation is occurring when the output voltage of the negative pressure sensor 67 becomes larger than the reference value Vr (Fig. 4 a), and as a result, the fourth
As shown in FIG. b, data to energize the solenoid of the first electromagnetic switching valve 43 is written to the output port 84. At this time, as can be seen from Fig. 4b, a pulse is sent to the solenoid of the first electromagnetic switching valve 43 during the initial time _T2 , and after time _T2 has elapsed, the pulse is sent to the solenoid of the first solenoid switching valve 43.
The solenoid of the electromagnetic switching valve 43 is continuously energized. Therefore, at time _T2 , the first negative pressure chamber 33 is switched to the surge tank 1 by the switching operation of the first electromagnetic switching valve 43.
3 and the atmosphere alternately. As a result, the negative pressure in the first negative pressure chamber 33 gradually increases, and the diaphragm 31 moves toward the first negative pressure chamber 33 against the compression spring 36. At this time, the engaging member 3
9 lifts the control rod 42 into engagement with the loose connection rod 40, thus gradually closing the intake shutoff valve 26 as shown in FIG. 4g. On the other hand, when the negative pressure sensor 67 detects that the operation has changed from high load operation to low load operation, the feedback control of the air-fuel ratio by the oxygen concentration detector 20 is stopped, and at the same time, the air flow meter 25 and the negative pressure sensor 67 are activated. Based on the detection signal, the amount of fuel injected from the fuel injection valves 17a and 17b is adjusted so that the air-fuel ratio of the air-fuel mixture supplied to the first cylinder group A and the second cylinder group B respectively becomes the stoichiometric air-fuel ratio. controlled. That is, when the intake cutoff valve 26 gradually closes, the negative pressure inside the surge tank 13 decreases, and if the engine speed is constant, the intake cutoff valve 2
There is a one-to-one relationship between the opening degree of 6 and the negative pressure inside the surge tank 13. Furthermore, if the engine speed is constant, the opening degree of the intake cutoff valve 26 has a one-to-one relationship with the allocation ratio of the intake air supplied to the first cylinder group A and the second cylinder group B, and therefore, the engine speed increases. If constant, there is a one-to-one relationship between the negative pressure in the surge tank 13 and the amount of intake air supplied to the second cylinder group B. Thus, if the relationship between the negative pressure in the surge tank 13 and the amount of intake air supplied to the second cylinder group B is known for each engine speed, it can be calculated from the engine speed and the negative pressure in the surge tank 13. The amount of intake air supplied to the second cylinder group B can be determined. In the present invention, the relationship between the engine speed N, the negative pressure P in the surge tank 13, and the amount of intake air supplied to the second cylinder group B is determined in advance through experiments, and the relationship between the engine speed N, the negative pressure P in the surge tank The relationship with the amount of intake air supplied to the second cylinder group B is stored in the ROM 82 in advance. Therefore, the engine rotation speed N is calculated in the MPU 80 from the output signal of the rotation speed sensor 72, and the engine rotation speed N thus calculated and the negative pressure sensor 67 are calculated.
The amount of intake air supplied to the second cylinder group B is calculated from the above-mentioned relationship stored in the ROM 82 based on the output signal. Furthermore, in the MPU 80, the amount of intake air supplied to the second cylinder group B is subtracted from the total amount of intake air determined from the output signal of the air flow meter 25, thereby reducing the amount of intake air supplied to the first cylinder group A. The amount is calculated. Then MPU
Within 80, the air-fuel ratio of the air-fuel mixture supplied to each cylinder becomes the stoichiometric air-fuel ratio based on the amount of intake air supplied to the first cylinder group A and the amount of intake air supplied to the second cylinder group B. A fuel injection amount is calculated, and fuel is injected from the fuel injection valves 17a and 17b based on the calculation result. Such open-loop air-fuel ratio control is performed between time Ta and time Tb in FIG. During this time, the intake cutoff valve 26 is closed as shown in Fig. 4g.
As can be seen, since the valves gradually close, the amount of intake air supplied to the first cylinder group A gradually decreases, and the amount of intake air supplied to the second cylinder group B gradually increases. Therefore, between time Ta and time Tb, the fourth
As shown in Figure f, the amount of fuel injected into the first cylinder group A gradually decreases, and as shown in Figure 4e, the amount of fuel injected into the second cylinder group B gradually increases.

Next, when time Tb is reached in FIG. 4, the diaphragm 31 comes into contact with the stopper 37 and stops moving, and the intake cutoff valve 26 is maintained in a half-open state. In this way, the diaphragm 31 is connected to the stopper 37.
At the same time, the movable contact 49 of the first changeover switch 29 connects to the fixed contact 51, and the connection signal of the fixed contact 51 is read into the MPU 80.
As soon as this connection signal is issued, the MPU 80 writes data to stop fuel injection in the first cylinder group A and data to energize the solenoid of the third electromagnetic switching valve 59 to the output port 84. At the same time the second
Air-fuel ratio feedback control for cylinder group B is started, and data indicating the fuel injection amount based on the output signal of oxygen concentration detector 20 is written to output port 84. As a result, when time Tb is reached, the fourth
As shown in Figure e, the amount of fuel injected from the fuel injection valve 17b of the second cylinder group B is increased, and the
As shown in FIG. f, fuel injection from the fuel injection valve 17a of the first cylinder group A is stopped. Further, since the solenoid of the third electromagnetic switching valve 59 is energized, the negative pressure chamber 56 of the exhaust gas recirculation valve 54 is connected to the inside of the surge tank 13 via the third electromagnetic switching valve 59 . As a result, negative pressure is applied in the negative pressure chamber 56, so the diaphragm 55 moves toward the negative pressure chamber 56 against the compression spring 58, and the valve body 61 opens the exhaust gas recirculation passage 53. As a result, the exhaust gas in the first exhaust manifold 14 is recirculated into the first intake manifold 11 via the exhaust gas recirculation passage 53. When the valve body 61 of the exhaust gas recirculation valve 54 fully opens the exhaust gas recirculation passage 53, the movable contact 64 of the second changeover switch 63 connects to the fixed contact 66, and a connection signal from the fixed contact 66 is read into the MPU 80. This time is indicated by time Tc in FIG. This fixed contact 66
As soon as the connection signal of
Data to energize the solenoid of the electromagnetic switching valve 45 is written to the output port 84. In this way, when the solenoid of the second electromagnetic switching valve 45 is energized, the second negative pressure chamber 34 is connected to the inside of the surge tank 13 via the negative pressure conduit 47, and thus the inside of the second negative pressure chamber 34 is Negative pressure is applied to the As a result, diaphragm 32
moves toward the first negative pressure chamber 33 against the compression spring 41, and the control rod 42 is thus lifted, so that the intake cutoff valve 26 is fully closed as shown in FIG. 4g.

On the other hand, in FIG. 5, time Ta indicates a transition from low load operation to high load operation. At this time, first, as shown in FIG. 5c, the solenoid of the second electromagnetic switching valve 45 is deenergized, and as a result, the second negative pressure chamber 34 is communicated with the atmosphere via the second electromagnetic switching valve 45. Therefore, the diaphragm 32 moves toward the atmospheric pressure chamber 35, and the intake cutoff valve 26 is opened to the half-open position as shown in FIG. 5g. When the intake cutoff valve 26 is opened to the half-open position, the intake cutoff valve 26 is temporarily held in the half-open state. On the other hand, when the intake cutoff valve 26 is opened to the half-open position, the first changeover switch 2
The movable contact 49 of 9 connects to the fixed contact 51, and this connection signal causes the third
The electromagnetic switching valve 59 is deenergized. As a result, the negative pressure chamber 56 of the exhaust recirculation valve 54 is communicated with the atmosphere via the third electromagnetic switching valve 59, and the diaphragm 55 moves toward the atmospheric pressure chamber 57, as shown in FIG. 5h. Valve body 61 closes exhaust gas recirculation passage 53. When the valve body 61 is fully closed, the second changeover switch 63
The movable contact 64 is connected to the fixed contact 65, and the connection signal of the fixed contact 65 applies a pulse to the solenoid of the first electromagnetic switching valve 43 as shown in FIG. 5b, and as shown in FIG. 5f. As shown, the fuel injection action from the fuel injection valve 17a of the first cylinder group A is started. Furthermore, at this time, the feedback control by the oxygen concentration detector 20 is stopped,
Based on the output signals of the air flow meter 25 and the negative pressure sensor 67, the air-fuel ratio of the air-fuel mixture supplied to the first cylinder group A and the second cylinder group B becomes the stoichiometric air-fuel ratio. The fuel injection amount is controlled.

Furthermore, when a pulse is applied to the solenoid of the first electromagnetic switching valve 43, the first negative pressure chamber 33 is alternately communicated with the atmosphere and the inside of the surge tank 13, so that the negative pressure in the first negative pressure chamber 33 gradually decreases. becomes smaller. As a result, the diaphragm 31 gradually moves toward the second negative pressure chamber 34, and the intake cutoff valve 26 gradually opens and fully opens as shown in FIG. 5g.

As shown in FIGS. 4b and 5b, when the intake cutoff valve 26 closes from the fully open position to the half open position, or when the intake cutoff valve 26 opens from the half open position to the fully open position, at time T ₂ . A pulse is then applied to the solenoid of the first electromagnetic switching valve 43.
In the present invention, the width of this pulse is varied depending on the rate of change of the engine load. Next, this will be explained with reference to FIG. In FIG. 7, (A-1) and (B-1) indicate the output voltage θ of the throttle sensor 68, (A-2) and (B-2) indicate the output voltage V of the negative pressure sensor 67, (A-3) and (B-3) indicate voltages applied to the solenoid of the first electromagnetic switching valve 43. Also, (A-1), (A
-2) and (A-3) show cases where the throttle valve 24 is suddenly opened, and (B-1) and (B-
2) and (B-3) show the case where the throttle valve 24 is opened slowly. The opening speed of the throttle valve 24 is constantly calculated within the MPU 80 from the output signal of the throttle sensor 68. As seen from (A-1), throttle valve 2
4 is suddenly opened, the pulse width of the pulse applied to the solenoid of the first electromagnetic switching valve 43 is relatively small. That is, the pulse duty ratio is small. On the other hand, as can be seen from (B-1), when the throttle valve 24 is opened slowly, the pulse width of the pulse applied to the solenoid of the first electromagnetic switching valve 43 is relatively large. Therefore, the pulse duty ratio is large. The first reason is that the pulse duty ratio is small.
This means that the negative pressure chamber 33 is communicated with the atmosphere for a long time, and therefore the negative pressure in the first negative pressure chamber 33 decreases quickly, that is, the intake cutoff valve 26
This means that the valve opens quickly. Therefore, it can be seen that when the throttle valve 24 opens suddenly, the intake cutoff valve 26 opens rapidly, and when the throttle valve 24 opens slowly, the intake cutoff valve 26 opens slowly. On the other hand, the duty ratio is set so that when the throttle valve 24 closes rapidly, the intake cutoff valve 26 closes rapidly, and when the throttle valve 24 closes slowly, the intake cutoff valve 26 closes slowly. predetermined. In the embodiment shown in FIG. 2, the rate of change in the engine load is detected from the opening speed of the throttle valve 24, but the rate of change in the engine load can also be detected from the output voltage of the negative pressure sensor 67. .

Another embodiment is shown in FIG. In this embodiment, a gear 112 that meshes with a worm 111 attached to the output shaft of a step motor 110 is connected to the intake cutoff valve 2.
The step motor 110 is fixed to the valve shaft 27 of No.6.
The opening and closing of the intake cutoff valve 26 is controlled by. In this embodiment, when the throttle valve 24 is suddenly opened as shown in (A-1) of FIG. 7, the step motor 11 is opened as shown in (A-4).
The interval between the drive pulses supplied to 0 becomes shorter, causing the intake cutoff valve 26 to open rapidly.
When the throttle valve 24 opens slowly as shown in (B-4), the interval between the drive pulses supplied to the step motor 110 becomes longer, causing the intake cutoff valve 26 to open slowly as shown in (B-4). It will be done. In any of the embodiments, as shown in FIGS. 4 and 5, when the intake cutoff valve 26 closes from the half-open position to the fully closed position, or when the intake cutoff valve 26 closes from the fully closed position to the half-open position, When opening, the intake cutoff valve 26 is rapidly closed or opened at a constant speed.

When the intake cutoff valve is rapidly opened or closed, the engine output torque will fluctuate rapidly only when fuel is being supplied to the first cylinder group. When the intake cutoff valve is not supplied, the output torque of the engine does not change suddenly even if the intake cutoff valve is rapidly opened or closed. Therefore, in order to transition from low-load operation to high-load operation and from high-load operation to low-load operation as quickly as possible without causing torque fluctuations, it is necessary to transition as quickly as possible when the fuel supply to the first cylinder group is stopped. It is preferable to open or close the intake cutoff valve. According to the present invention, when the intake cutoff valve is between the fully open position and the approximately half-open position and fuel is being supplied to the first cylinder group, when the negative pressure in the throttle valve or surge tank slowly changes, the intake Since the shutoff valve also opens or closes slowly, it is possible to prevent the output torque of the engine from fluctuating rapidly, thus ensuring good vehicle drivability. Furthermore, since the intake cutoff valve is rapidly opened while the intake cutoff valve is opening from the fully closed position to the approximately half open position, the transition from low load operation to high load operation can be made more quickly. On the other hand, when the throttle valve is suddenly opened, the intake cutoff valve is rapidly opened from the fully closed position to the fully open position, so that good acceleration can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a plan view schematically showing a conventional internal combustion engine, FIG. 2 is a plan view schematically showing an internal combustion engine according to the present invention, FIG. 3 is a circuit diagram of the electronic control unit shown in FIG. 5 is a diagram for explaining the divided operation control method according to the present invention, FIG. 6 is a diagram for explaining the divided operation control method according to the present invention, FIG. 6 is a plan view of another embodiment, and FIG. The figure is a diagram for explaining the divided operation control method according to the present invention. 11...First intake manifold, 12...Second intake manifold, 13...Surge tank, 14...
First exhaust manifold, 15... Second exhaust manifold, 17a, 17b... Fuel injection valve, 18... Electronic control unit, 24... Throttle valve, 26...
...Intake cutoff valve, 29...First selector switch, 30
...Negative pressure diaphragm device, 43...First electromagnetic switching valve, 45...Second electromagnetic switching valve, 53...Exhaust recirculation passage, 54...Exhaust recirculation valve, 59...Third electromagnetic switching valve, 63... ...Second changeover switch, 67...Negative pressure sensor, 68...Throttle sensor.

Claims (1)

[Claims] 1 dividing the cylinders into a first cylinder group and a second cylinder group, connecting the first cylinder group and the second cylinder group to a common surge tank via a first intake passage and a second intake passage, respectively; An intake cutoff valve is provided in the first intake passage, the intake cutoff valve is fully closed during low engine load operation, and fully opened during high engine load operation, and the first intake passage downstream of the intake cutoff valve and the engine exhaust passage are An exhaust recirculation valve is provided in the exhaust recirculation passage connecting the two cylinders, and the exhaust recirculation valve is opened when the engine is running at low load and closed when the engine is running at high load. In an internal combustion engine equipped with a fuel supply device that stops the fuel supply and controls the supply of fuel to the second cylinder group, and controls the supply of fuel to the first cylinder group and the second cylinder group during engine high load operation, The system includes a rate-of-change detector that detects the rate of change in engine load, and a drive device that drives the intake cutoff valve based on the output signal of the rate-of-change detector, and is capable of transitioning from low-load engine operation to high-load operation. When the intake cutoff valve is between the fully open position and the approximately half-open position when the engine is in a transition state from high load operation to low load operation, the fuel supply device supplies fuel to the first cylinder group and the second cylinder group. and when the intake cutoff valve is between the fully closed position and the approximately half open position, the fuel supply device
Stops the supply of fuel to the cylinder group and controls the supply of fuel to the second cylinder group, and when the intake cutoff valve is between the fully open position and the approximately half open position, as the rate of change in the engine load increases increasing the opening speed or closing speed of the intake cutoff valve;
A split operation control system that rapidly opens or closes the intake cutoff valve at a constant speed, regardless of the rate of change in the engine load, when the intake cutoff valve is between a fully closed position and a substantially half open position. Internal combustion engine.