JPS5848735A - Internal-combustion engine with divided cylinder group operation control type - Google Patents

Abstract

PURPOSE:To attain smooth emission of exhaust gas even at the time of switching the number of operative cylinders, by keeping the air-fuel ratio of mixture at the theoretical air-fuel ratio through accurate measurement of intake air supplied to cylinders at the time when an intake-air stop valve is being opened or closed. CONSTITUTION:A first intake manifold 11 and a first exhaust manifold 14 are connected to a first cylinder group A, while a second intake manifold 12 and a second exhaust manifold 15 are connected to a second cylinder group B. The datum injection quantity of fuel calculated from the output signal of an air-flow meter 25 is corrected on the basis of the output signal of first oxygen-density detector 20a to provide a datum injection quantity for the first cylinder group A, while a datum injection quantity for the second cylinder group B is obtained by correcting the datum injection quantity of fuel calculated from the output signal of the air-flow meter 25 on the basis of the output signal of a second oxygen-density detector 20b. According to these data, injection pulses are applied to fuel injection valves 17a, 17b belonging respectively to the first and the second cylinder groups A, B, and fuel is injected from the valves 17a, 17b to supply air-fuel mixture to the cylinder groups A, B at the theoretical air-fuel ratio.

Description

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

In a private engine in which the engine load is controlled by a throttle valve, the fuel consumption rate worsens as the throttle valve opening decreases. Therefore, in order to improve the fuel consumption rate, some cylinders are deactivated when the engine is operated at low load, and the remaining 90 cylinders are operated at high load. It is publicly known as described in Bulletin No. 69736. In this known internal combustion engine, the cylinders are divided into a first cylinder group M and a second cylinder group B, as shown in No. 111, and the first cylinder group M and the second cylinder group BK are respectively connected to the first intake manifold 1 and Connect the second intake manifold 2 and the first intake manifold 1 and the second intake!
An exhaust gas recirculation passage connects the exhaust manifold 5 and the first intake manifold 1, which communicates the intake manifold 2 with the atmosphere through a common throttle valve 3, and provides an intake cutoff valve 4 at the intake air inlet of the first intake manifold 1. Exhaust recirculation valve 7 in 6
is provided to stop fuel injection from the fuel injector 8 during low load operation of one engine, open the intake cutoff valve 4 and open the exhaust recirculation valve 7, and cause the second cylinder group B to operate under high load. On the other hand, when the engine is operating under high load, when fuel is injected from all fuel injection valves 8 and 9, the Kl & air shut-off is opened and the exhaust recirculation valve 7 is closed, causing all cylinders M and B to perform firing operation. . In this internal combustion engine, as mentioned above, when the engine is operated under low load, the intake quick cutoff valve 4 closes and the exhaust recirculation valve 7 opens, so that exhaust gas is circulated to the first cylinder group ^ via the exhaust recirculation passage 6. It is possible to eliminate the pumping loss due to the
Moreover, since the second cylinder group B is operated under high load at this time, the fuel consumption rate can be improved.

In such a split-operation controlled internal combustion engine, a three-way catalytic converter and an oxygen concentration detector are installed in the engine exhaust system, and the air-fuel ratio of the mixture supplied to the engine cylinders is theoretically determined based on the output signal of the oxygen concentration detector. When attempting to match the air-fuel ratio, it is necessary to accurately measure the amount of intake air. For this purpose, an air flow meter K is installed upstream of the throttle valve 3 as shown in FIG. -Meter KK
- I try to measure the total amount of intake air. However, when the air flow meter K is installed upstream of the throttle valve 3 like this, the intake cutoff valve 4 is fully open and the same amount of intake air is being supplied to all cylinders, or the intake cutoff valve 4 is It is only possible to accurately measure the amount of intake air supplied to each cylinder when it is fully closed and intake air is supplied only to the second cylinder bK.In other words, the intake cutoff valve 4 is in a half-open state. When K is the first cylinder group and the second cylinder group
It is not possible to accurately determine the amount of air supplied to each cylinder in the first cylinder group B and the second cylinder group B because it is not known at what ratio the intake air is distributed to each cylinder group B.
In this way, the intake cutoff valve 4 becomes partially closed when the intake quick cutoff valve 4 changes from fully closed to fully open, or from fully open to fully closed.

Therefore, in such a case, as mentioned above, the amount of intake air supplied to each cylinder cannot be determined accurately, so the air-fuel mixture supplied to each cylinder becomes too rich or too lean, and thus the exhaust emitter 1 This results in the problem of deterioration of performance. In particular, if the opening or closing operation of the intake cutoff valve 4 is made slow in order to prevent a sudden increase or decrease in the engine output, the exhaust emitter 1 becomes even worse.

The present invention theoretically calculates the air-fuel ratio of the air-fuel mixture supplied to each cylinder by accurately measuring the amount of intake air supplied to each cylinder even when the intake quick-cut valve is opening or closing the valve. It is an object of the present invention to provide an internal combustion engine in which the air-fuel ratio is maintained at a constant level, thereby ensuring good exhaust emissions even when the number of operating cylinders is changed.

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 air
! Nifold, 12 is the 29th Qi Nifold.

13 is a surge tank, and 14 is a first exhaust manifold.

15 is the second exhaust manifold, 16 Hatake*16be16c,
16d, 16e, and 16f indicate the 1st cylinder, 2nd cylinder, 3rd cylinder, 4th cylinder, 5th cylinder, and 6th cylinder, respectively.
In addition, each of these cylinders is cylinder 16*16b-16c.
The first cylinder group A, etc.

It is divided into a second cylinder 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, and the second intake manifold 12 and the second exhaust manifold 15 are connected to the second cylinder group BK. As shown in FIGS. 2 and 3, the first intake manifold, the first intake manifold, and the second intake manifold! Fuel injection valves 17m and 17b are attached to each manifold branch pipe of the Nifold 12, and the solenoid of each of these fuel injection valves 17m and 17b is controlled by an electronically controlled Enit 1.
Connected to 8. On the other hand, the first exhaust manifold 14 and the second exhaust manifold 15 are partitioned at their outlet portions by a common partition wall 19, and exhaust passages are provided on both sides of this partition wall 19.

That is, a first oxygen concentration detector 20m and a second oxygen concentration detector 20b are arranged in the first exhaust manifold 14 and the second exhaust manifold 15, respectively.

These oxygen concentration detectors 20m and 20b are connected to an electronic control unit 18. The first exhaust manifold 14 and the second exhaust manifold 15 are connected to a three-way contact converter 75 via a common exhaust pipe 74, and a partition wall 76 is disposed within this exhaust pipe 74. One end of the partition wall 76 is connected to the partition wall 19 of the exhaust manifold 14 , 15 , and the other end of the partition wall 76 extends to the vicinity of the three-way catalytic converter 75 . Therefore, the first exhaust manifold 1 is located inside the exhaust pipe 74.
A first exhaust passage 74b communicating with the inside of the three-way catalytic converter 75 and a second exhaust passage 74b communicating with the second exhaust manifold 15 are formed. join together.

On the other hand, the first intake manifold 11 has an intake air inlet section 21, and a cylinder 16m branching from the intake air inlet section 21,
It has three manifold branch pipes 16b and 16cK connected to each other, and the intake air inlet section 21 is connected to the surge tank 13. Also, the second intake! Similarly, the intake air inlet 12 has an intake air inlet 22 and three air inlets 11116d, 16e, and 16fK that are branched from the intake air inlet 22 and connected to each other.
It has a main manifold branch pipe, and the intake air inlet section 22 is connected to the nerge tank IBK@. An intake duct 23 is installed in the center of the surge tank 13. A throttle valve 24 is disposed within the intake duct 23 of : . This throttle valve 24 is connected via a wire 25' to an accelerator pedal provided in the vehicle cab. Furthermore, the third
As shown in the figure, an air flow meter 2 is installed in the intake duct 23.
5 is installed, and the air meter 74 is connected to the electronic control unit 18 via a lead wire (not shown), and the air meter 25 is connected to the electronic control unit 18 via a lead wire (not shown).
The fK second intake manifold 12 has a substantially symmetrical shape with respect to the axis of symmetry 8 that is perpendicular to the longitudinal direction of the engine body 1G, and the intake duct 23 is arranged approximately on this axis of symmetry 1s8. ing. It was. surge tank 1
3 also has a substantially symmetrical shape with respect to the axis of symmetry 8.

As shown in FIGS. 2 and 3, an intake cutoff valve 26 is disposed in the intake air inlet 21 of the first intake manifold 11, and a negative pressure diaphragm device 30 is connected to the valve shaft 27 of the intake cutoff valve 26. A connected arm 28 and a first exchange switch 29 are attached. As shown in FIG. 3, the negative pressure diaphragm device 30 includes a pair of spaced apart diaphragms 31,32.
The interior of the diaphragm 31.32 creates a first negative pressure element 33. It is divided into eight 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 is arranged to be able to engage with the diaphragm 31 to adjust the amount of displacement of the diaphragm 31 . be screwed on. It was. The retaining member 3- has an opening 38 on the surface of the diaphragm 31 exposed in the second negative pressure chamber 34.
is fixed to the diaphragm 32, and a play coupling rod 4o having an enlarged head having a larger diameter than the opening 38 and movable within the retaining member 39 is attached to the diaphragm 32. A compression spring 41 is inserted between the diaphragms 31 and 32, and the diaphragm 32 is connected to the distal end of the arm 28 via a control rod 42. Switching valve 43. It is connected to the inside of the surge tank 13 via a throttle 46 and a negative pressure conduit 44, and is connected to the inside of the surge tank 13.

The pressure chamber 34 is connected to the inside of the surge tank 13 via a second electromagnetic switching valve 45 that can communicate with the atmosphere and a negative pressure conduit 47. On the other hand, the first changeover switch 29 has a movable contact 49 that rotates together with the valve shaft 27 of the throttle valve 26, and a movable contact 49 that rotates together with the valve shaft 27 of the throttle valve 26.
3 fixed contacts that can be contacted with 9! So, 51.32, these fixed contacts 50, 51.52 end connected to the electronic control unit 18. The movable contact 49 is the throttle valve 2
When the throttle valve 26 is fully open, it is connected to the fixed contact 50, when the throttle valve 26 is half open, it is connected to the fixed contact 51, and when the throttle valve 26 is fully closed, it is connected to the fixed contact 50. 52, followed by 11.

On the other hand, the tlEl exhaust water field 14 upstream of the oxygen concentration detector 20 and the first intake manifold 1 downstream of the intake quick cut valve 26
1 are connected to each other by an exhaust gas recirculation passage 53, and a negative pressure diaphragm type exhaust gas recirculation valve 54 is connected to this exhaust gas recirculation passage 53.
is inserted. This exhaust recirculation valve 54 has a diaphragm 55
It has a negative pressure chamber 56 and an atmospheric pressure chamber 57 which are separated by a negative pressure chamber 56, and a compression spring 58 for pressing the diaphragm is inserted into the negative pressure chamber 56. The 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. This solenoid of the third electromagnetic switching valve 59 and the first solenoid. The solenoid of the second electromagnetic switching valve 43,45 is connected to the electronic control unit 18. A valve body 6 for controlling opening and closing of the exhaust gas recirculation passage 53 is provided in the exhaust gas recirculation passage 53.
1 is placed.

This valve body 61 is connected to the diaphragm 55 through a valve quadruple 62.
connected to. 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 58 and actuated by movement of the diaphragm 5Js, and a pair of fixed contacts 65 and 66 that can come into contact with the movable contact 64. .66 is connected to the electronic control unit 18. The movable contact 64 is the defining contact 6! when the valve body '61 is closed. $, and when the valve body 61 opens, it is connected to the fixed contact 66. As shown in FIG. 3, six negative pressure sensors are attached to the surge tank 13 to detect the engine load, and this negative pressure sensor 67 is connected to the electronic control unit 1B. Additionally, as shown in FIG. 2, an exhaust gas recirculation device is provided, which comprises a recirculation exhaust gas flow control valve 73 and a recirculation exhaust gas conduit 69.

The exhaust gas inlet lower 0 of this recirculation exhaust gas conduit 69 is connected to the first exhaust manifold 14 upstream of the oxygen concentration detector 20, and the exhaust gas inlet 11 and outlet 9 port 71 of the recirculation exhaust gas conduit 69 are almost symmetrical. It is connected within the surge tank 13 on the axis 8 . Although not shown in Figures 2 and 3, in order to detect the engine rotation speed, the engine rotation speed +7t72
(Fig. 4) is attached to the engine body 10.

FIG. 4 shows a circuit diagram of the electronic control unit 18.

Referring to FIG. 4, the slave control unit 18 is comprised of a digital computer, and includes an i-microprocessor (!IJPU) 80. which 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
．． Input port 83 and output port 84 are bidirectional bus 8
They are connected to each other via 5. Furthermore, a four clock generator 86 is provided within the electronic control unit 18 for generating various clock signals. *<As shown in the figure, the rotation speed sensor 72. First changeover switch 29. The second changeover switch 63 is connected to the input port 83 via a corresponding buffer amplifier 87, 88, 89, respectively.

In addition, the air flow meter 25 and the negative pressure sensor 67 are connected to the corresponding buffer amplifiers 90 and 91 and the ^D converter 92.
．． The first oxygen concentration detector 20 and the second oxygen concentration detector 20b are connected to the corresponding buffers 94m and 94, respectively, and to the comparator 95at95 via +. (capo) 83.

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 sent to the rear input port 83 and the bus 8.
The rotational speed sensor 72 outputs continuous pulses with a period proportional to the engine rotational speed, and these continuous pulses are read into the MPU 5OK via an input port 83 and a bus 85. Oxygen concentration detector 20
a.

20b is 0.1 por Fl when the exhaust gas is in an oxidizing atmosphere!
When the exhaust gas is in a reducing atmosphere, it generates an output voltage of 1!
Generates an output voltage of a9* power. The output voltage of this oxygen concentration detector 2one 20b is determined by the comparator 95a.
* For example, when the exhaust gas is in an oxidizing atmosphere, an output signal is generated at one output terminal of the comparator 9 S m * 9 S b, and the exhaust gas is in a reducing atmosphere. At this time, an output signal is generated at the other output terminal of the comparators 95m and 95b. The output signals of the comparators 95 a e 95 b are read into the MPU 80 via the input port 83 and the bus 85 .

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 D converter 93 and then sent to the MPU via the input port 83 and the bus 85. 80. 1st
The contact switching signals of the changeover switch 29 and the second changeover switch 63 are sent to the MPU via the input port 83 and the path 8s.
801C is loaded.

The output port 84 is provided to operate the fuel injection valves 17m and 17b as well as the electromagnetic switching valves 43, 45, and 59, and the output port 84 stores binary data to the MPU 8.
0 via path 85. Output port 84
The output terminals are down counters 96, 97 and latches,
98 corresponding input terminals. Each down counter 96.s7 is provided to convert the binary data written from the MPo 8G into the corresponding time length), and these down counters 96 and 97 are input from the output port 84. The down-counting of the received data is started by the clock signal of the four clock generator 86, and when the count value is OK, the counting is completed and a count completion signal is generated at the output terminal. The set input terminals R of each 8-R flip-flop 99s 100 are connected to the output terminals of the down counters 96, 97, respectively, and the set input terminals 8 of the 8-R flip-flops 99,100 are connected to the clock generator 86. Ru. These 8-R7 lip 7
The W knobs 9G and 100 are set at the same time as the down count starts by the clock signal of the clock generator 86, and the corresponding down counter 96.97 is set when the down count is completed.
It is reset by the count completion signal. Therefore 8
The output terminals Q of the R flips 7a 9G and 100 are at a high level because the corresponding down counters 9g and 97 are down counting. The output terminals Q of the 8-87 lip-flops 99 and 100 are connected to power amplification circuits 101, respectively.
．． 10! are connected to the fuel injection valve 17 of the first cylinder group B and the fuel injection valve 17bKl of the second cylinder group B,
Therefore, while the down counters 96 and 97 are counting down, fuel is also injected into the fuel injection valves 17m and 17b, respectively. on the other hand.

The data for controlling the electromagnetic switching valve written in the output port 84 is held by a latch 98, and the data held by the latch 98 causes the electromagnetic control valve 43°45.59 to operate.

5 and 6 show time charts for explaining the divided operation control method according to the present invention.

In Figure 51 and Figure 6, the diagrams (1) to (h) indicate the following.

(1)! Output voltage of negative pressure sensor 67.

(b1 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 5g.

(e) is a control pulse applied to the fuel injection valve 17b of the second cylinder group B.

(f)! A control pulse applied to the fuel injection valve 171 of the first cylinder group A.

(Opening degree of the g-door intake value cutoff valve 26.

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

Note that the Its diagram shows the transition from high-load operation to low-load operation, and FIG. 6 shows the transition from low-load operation to high-load operation.

Time T1 in FIG. 5 indicates a high load operation when the output voltage of the negative pressure sensor 67 is low. At this time, as shown in FIG. 5(b), the solenoid of the first electromagnetic switching valve 43 is deenergized, and therefore the first negative pressure chamber 33 is
It communicates with the atmosphere through. It was. At this time, Figure 5 (
As shown in c), the solenoid of the second electromagnetic switching valve 45 is also deenergized.

Therefore, the second negative pressure chamber 34 also communicates with the atmosphere via the second electromagnetic switching valve 45. As a result, 1 car Diacrum 31.3
2 is the most atmospheric pressure chamber 3! ! *, and thus the intake quick cut valve 26 is fully open as shown in FIG. 5 ω. Furthermore, at time TI in FIG. 5, the solenoid of the third solenoid switching valve 59 is deenergized as shown in FIG. 59 to the atmosphere. In this way, the diaphragm S5 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. 5(b) 4'C.

On the other hand, at this time, at MP080 in FIG. 4, the engine speed is calculated from the output pulse of the rotation speed sensor 72, and the basic fuel injection amount is calculated from this engine speed and the output signal of the air meter 25.

On the other hand, when the three-way catalytic converter 75 is used, the purification efficiency by the three-way catalyst is highest when the air-fuel ratio of the air-fuel mixture supplied into the engine cylinder reaches the stoichiometric air-fuel ratio. The basic fuel injection amount calculated from the output signal of the meter 25 does not exactly match the fuel amount required to form the stoichiometric air-fuel ratio. Therefore, the air-fuel ratio of the air-fuel mixture supplied to the first cylinder group AK The basic fuel injection amount to be injected from the fuel injection valve 17m of the first cylinder group BK is corrected based on the output signal of the first oxygen concentration detector 20m so that the air-fuel ratio becomes the stoichiometric air-fuel ratio. The basic fuel injection amount to be injected from the fuel injection valve 17b of the second cylinder B is corrected based on the output signal of the second oxygen concentration detector 20b so that the air-fuel ratio of the mixture becomes the stoichiometric air-fuel ratio. . The data representing the fuel injection amount obtained by K after each correction is written to the output port 84, and based on this data, as shown in Fig. 511(e) and Fig. 5(f), is applied to the fuel injection valve 17m of the second cylinder group B and the fuel injection valve 17b of the second cylinder group B. Therefore, during high-load engine operation, fuel is injected from all fuel injection valves 17mt17b, and the fuel injection valve 17m of the second cylinder group B is injected. The air-fuel mixture at the stoichiometric air-fuel ratio is supplied to each of the cylinder group BK and the second cylinder group BK.

Next is the time shown in Figure 5! When high load operation is switched to low load operation at point 1 and point 9 is reached, the output voltage of the *pressure sensor 67 rises rapidly as shown in FIG. 5(a)K. ) J.P.U.
80, when the output voltage It of the negative pressure sensor 67 is larger than the reference value v, (Fig. 5)), it is determined that the operation is under low load, and as a result, as shown in Fig. 5(b)K, K11!
1. Write the data to energize the solenoid of the electromagnetic switching valve 43 to the output port 84.

When the solenoid of the first electromagnetic switching valve 43 is energized in this way, the first negative pressure chamber 33 is connected to the inside of the surge tank 13 via the throttle 946 and the first electromagnetic switching valve 43. As a result, the negative pressure inside the first negative pressure chamber 33 gradually increases, so that the diaphragm 31 resists the compression spring 36 and the negative pressure inside the first negative pressure chamber 33 increases gradually. Move to the negative pressure chamber 33 side.

At this time, the engagement member 39 lifts the control rod 42 to engage the play connecting rod 40, thus FIG.
As shown in K, the intake cutoff valve 26 gradually closes. On the other hand, when the negative pressure sensor 67 detects that the high load operation has changed to the low load operation, the first cylinder group A and the second cylinder The basic fuel injection amount to be supplied to Part B is calculated.

That is, as the intake cutoff valve 26 gradually closes, the negative pressure within the storage tank 13 decreases accordingly.

Assuming that the engine speed is constant, there is a one-to-one relationship between the opening degree of the intake cutoff valve 26 and the negative pressure in the surge tank 13. Furthermore, if the engine speed is constant, the opening degree of the intake speed 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 BK, and therefore the engine speed increases. If constant, there is a one-to-one relationship between the negative pressure in the two surge tanks 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 BK for each engine speed is known, it can be calculated from the engine speed and the negative pressure in the surge tank 13. II2 The amount of intake air supplied to the cylinder group B can be determined.1 In the present invention, the engine speed N, the surge tank 1
The relationship between the negative pressure P in the surge tank and the amount of intake air supplied to the second cylinder group BK was determined in advance through experiments. The relationship with the amount is stored in the ROM 82 in advance. Therefore, the engine rotation speed N is determined from the output signal of the rotation speed sensor 72 as MP08.
Calculated within G, and thus calculated engine speed N
Based on the output signal of the negative pressure sensor 67 and the above-mentioned relationship stored in 80Mg2, the amount of intake air supplied to the second cylinder BK is calculated.

Furthermore, the second cylinder group BK is calculated based on the total intake air amount obtained from the output signal of the air flow meter 25 in lMPU8G.
The amount of intake air supplied is subtracted, thereby calculating the amount of intake air supplied to the first cylinder group AK.
In PU 80, the amount of intake air supplied to the first cylinder group B and the amount of intake air supplied to the second cylinder group B is necessary for the air-fuel ratio of the mixture supplied to each cylinder to reach the stoichiometric air-fuel ratio. Then, in the MPU 80, the basic fuel injection amount to be supplied to the first cylinder group is corrected based on the output signal of the first oxygen concentration detector 201.

Furthermore, the basic fuel injection amount to be supplied to the second cylinder group BK is corrected based on the output signal of the second oxygen concentration detector 20b.

With this correction, fuel is injected from the fuel injection valves 17m and 17b based on the especially obtained nine fuel injection amounts.

Open-loop air-fuel ratio control is performed from time T in Figure 5 to time! It is held at Menseki. During this time, the intake cutoff valve 26 gradually closes as shown in FIG. increases gradually. Therefore, between time T1 and time Tb, tuna 5
As shown in Figure (f) K, the amount of fuel injected into the first cylinder *AK gradually decreases, and as shown in Figure 5 (e) K, the amount of fuel injected into the second cylinder group BK gradually decreases. During this time, the pressure of each cylinder group increases.

The air-fuel ratio of the air-fuel mixture supplied to BK is maintained at the stoichiometric air-fuel ratio. Then, when time Tb is reached in FIG. 5, the diaphragm 31 comes into contact with three stoppers and stops moving, and the intake quick cutoff valve 26 is half-open. is maintained in the state of

In this way, when the diaphragm 31 comes into contact with the stop/(3?), the movable contact 49 of the tcI11 changeover switch 29 connects to the fixed contact SIK, and the connection signal of this fixed contact 51 is read into the MPU 80. Write the generated medium distortion, the data to stop the fuel injection of the first cylinder group B, and the data to energize the third solenoid switching valve! $9 solenoid to the output capo) 84, at this time to the second cylinder group B. continues to be supplied with fuel, and the air-fuel ratio of the mixture supplied to the second cylinder group BK is determined by the second oxygen concentration detector 2.
It is controlled to maintain the stoichiometric air-fuel ratio based on the output signal of 0b. As a result, when 1 time ThK is reached, the fuel injection amount from the fuel injection valve 17b of the second cylinder group B is increased as shown in FIG. 5(e), and the amount of fuel injected into the KM1 cylinder is increased as shown in FIG. 5(f). Fuel injection from the 17 fuel injection valves of group A is stopped. Further, since the solenoid of the third electromagnetic switching valve 59 is energized, the negative end 56 of the exhaust recirculation valve 54 is connected to the inside of the surge tank 13 via the third electromagnetic switching valve 59. As a result, a negative pressure is applied in the negative pressure chamber 56, so that the diaphragm 55 resists the compression spring 5BK and the negative pressure i! 56 side, and thus 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. The valve body 61 of the exhaust gas recirculation valve 54 is connected to the exhaust gas recirculation W.
When 653 is fully opened, the movable contact 6 of the second changeover switch 63
4 is connected to a fixed contact 66, and a connection signal from this fixed contact 66 is read into the MPU 80. This time is indicated by time Tc in FIG. As soon as the connection signal of the fixed contact 66 is issued, the MPU 80 activates the second electromagnetic switching valve 450.
Data to energize the solenoid is written to the output port 84. When the solenoid of the second electromagnetic switching valve 4-5 is energized in this way, the second negative pressure chamber 34 is connected to the surge tank via the negative pressure conduit 47. 13, thus applying negative pressure to the second negative pressure chamber 34. As a result, the diaphragm 32 resists the compression spring 41 and the first negative pressure chamber 3
3 side, and thus the control rod 42 is lifted, so that the intake quick-release valve 26 is moved to the 3 side as shown in FIG. 5(g)K.
is fully closed.

As shown in Fig. 5(@)'PI to Fig. 5(h)K, when the engine shifts from high-load operation to low-load operation, the intake quick cutoff valve 26 is first gradually closed to the half-open position. , and ψh are also controlled so that the air-fuel ratio of the air-fuel mixture supplied to this cylinder becomes the stoichiometric air-fuel ratio, so the output torque of the first cylinder group B gradually decreases, and the output torque of the second cylinder group B gradually decreases. The output torque increases gradually. the result.

The key is to smoothly transition from high-load operation to low-load operation without causing a sudden decrease in output torque. Furthermore,
Since the intake cutoff valve 26 is held in a half-open state until the exhaust gas recirculation action is started, pumping loss during transition from high load operation to low load operation can be eliminated.

On the other hand, in FIG. 6, time Ta indicates a transition from low load operation to high load operation. At this time, first, as shown in FIG. 6(C), 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. The diaphragm 32 is moved to the atmospheric pressure chamber 35, and the intake cutoff valve 26 is opened to the half-open position as shown in FIG. 6(g). 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 movable contact 4 of the first changeover switch 29
9 is connected to the fixed contact 51Kii, and this connection signal deenergizes the third electromagnetic switching valve 59 as shown in FIG. 3(d)K. As a result, the negative pressure chamber 56 of the exhaust gas recirculation valve 54
The diaphragm 55 moves toward the atmospheric pressure chamber 57 to be communicated with the atmosphere via the electromagnetic switching valve 59, and as shown in FIG.
h) The valve body 61 closes the exhaust gas recirculation passage 53 as shown in K. 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 from the fixed contact 65 deenergizes the first electromagnetic switching valve 43 as shown in FIG.
f) Fuel injection valve 17m of the first cylinder group A as shown in K
The fuel injection action starts.

If the first cylinder group A is kept at rest for a long time until the injection action of the brain fuel starts from the fuel injection valve 17, then during this time the exhaust gas will flow through the intake and exhaust of the first cylinder group A. Since the exhaust gas is only circulating within the system, the temperature of the exhaust gas decreases, and as a result, the temperature of the detection part of the 111th line concentration detection lfl 20 m drops to about 150℃.However, the oxygen concentration detector If the temperature of the first oxygen concentration detector 201 is not higher than the activation temperature (1, for example, 350 degrees Celsius or higher, the detection ability will be reduced). The air-fuel ratio cannot be controlled by the output signal.

To determine whether the temperature of the detection part of the first oxygen concentration detector 20m has become higher than the activation temperature, check the first oxygen concentration detector 2.
This can be determined from the peak value of the output voltage at 0 m, and if this peak value exceeds approximately α5 port, it can be determined that the first oxygen concentration detector 20- has a detection capability. The output voltage of the first oxygen concentration detector 20m is constantly monitored by the MPU 1 through the comparator 95m, so that when the fuel injection action from the fuel injection valve 171 is started as described above, the first oxygen concentration The temperature of the detection part of the temperature detector 20 islands is the active temperature 111! If the amount has not been reached, fuel is injected from the fuel injection valve 171 based on the basic fuel injection amount calculated from the output signals of the air full meter 25 and the negative pressure center t67. At this moment im passionately
If the temperature of the detection part of the first oxygen concentration detector 208 exceeds the activation temperature, the above-mentioned basic fuel injection amount is corrected based on the output signal of the first oxygen concentration detector 201.

As described above, when the fuel injection action from the fuel injection valve 17a is started and at the same time the first electromagnetic switching valve 43 is deenergized, the first
Since the negative pressure chamber 33 is communicated with the atmosphere through the throttle 46, the diaphragm 31 gradually moves to the first negative pressure chamber 3411, and thus the intake cutoff valve 26 is closed as shown in FIG. The valve gradually opens and then fully opens. At this time, if the temperature of the detection part of the first oxygen concentration detector 20m has not yet reached the activation temperature, the amount of sacrificial fuel from the fuel injection valve 17 is calculated based on the basic fuel injection amount calculated from the output signal of the airflow meter 25. is injected, and the first oxygen concentration detector 20m
If the temperature of the detection part exceeds the activation temperature, this basic fuel injection amount is corrected by the output signal of the first oxygen 11 degree detection 920 m.

When the engine shifts from low-load operation to high-load operation in this way, the intake cutoff valve 26 is first half-opened, and then the valve body 61 of the exhaust recirculation valve 54 closes the exhaust recirculation passage 53, eliminating the pumping loss. Then, the intake cutoff valve 26 is gradually opened to the fully open position, and the output torque of the first cylinder group is gradually increased, so that it is possible to prevent the engine output from rapidly increasing. can.

As described above, according to the present invention, when the engine transitions from high-load operation to low-load operation, or from low-load operation to high-load operation, the intake cutoff valve is gradually opened and closed. During the opening/closing operation, the air-fuel ratio of the air-fuel mixture supplied to the first and second cylinder groups is controlled to be the stoichiometric air-fuel ratio, which prevents deterioration of the exhaust system and increases the output suddenly. Torque fluctuations can be prevented. In addition, when one engine shifts from high-load operation to low-load operation, or from low-load operation to high-load operation, the exhaust recirculation valve is opened and closed with the intake cutoff valve half open, resulting in pumping loss. In addition, fuel is not supplied to the first cylinder group when exhaust gas recirculation is being performed, and fuel is not supplied to the first cylinder group when exhaust gas recirculation is stopped. good combustion can be obtained. Furthermore, in the present invention, oxygen concentration detectors 20g+ and 20b are separately installed in each intake manifold 14.15 separated by a partition wall 19. Conventionally, for example, the first exhaust is placed on the partition wall 19! A through hole was formed to communicate the inside of the nitrogen fold 14 and the inside of the second exhaust i-nifold 15, and a single oxygen concentration detector was installed in this through hole. However, in this case, when the first cylinder group A is stopped, the exhaust gas temperature in the first exhaust manifold 14 decreases, so even if high-temperature exhaust gas is flowing in the second exhaust manifold 14, the oxygen concentration detector The temperature of the detector is the 7th
As shown in the figure, the temperature drops below the activation temperature, resulting in a significant drop in detection ability.

In FIG. 7, the vertical axis T indicates the temperature of the detection part of the oxygen concentration detector, tl indicates when all cylinders are operating, and tl indicates when the first cylinder group is at rest. 19. If a through hole as described above is formed, the high temperature exhaust gas in the second intake manifold will be transferred to the first intake manifold when the first cylinder group is at rest! Because the oil and carbon contained in the high-temperature exhaust gas flow into the engine's intake manifold, the oil and carbon contained in the high-temperature exhaust gas enter the engine's first intake manifold and fuel injection valve
The problem arises that it accumulates at 1. However, in the present invention, by providing the partition wall 19.76, even when the first cylinder group A is at rest, the high temperature exhaust gas in the second exhaust manifold 15 does not enter into the first exhaust manifold. In this way, it is possible to prevent oil mist, carbon, etc. from accumulating.

First, the second oxygen concentration detector 20b is always in contact with the high-temperature exhaust gas, so it can be kept in a detectable state at all times. on the other hand,! When the first cylinder group is in operation, the second
There may be cases where the temperature of the oxygen concentration detector is not high enough, but in such cases, the air-fuel ratio can be controlled to approximately the stoichiometric air-fuel ratio by open-loop air-fuel ratio control.

[Brief explanation of the drawing]

FIG. 1 is a plan view schematically showing a conventional internal combustion engine. Fig. 2 is a plan view of an internal combustion engine according to the present invention, and Fig. 3 is a plan view of the internal combustion engine according to the present invention.
FIG. 4 is a circuit diagram of the electronic control unit shown in FIG. 3, FIG. 5 is a ninth diagram illustrating the split operation control system according to the present invention, and FIG. 7 is a diagram for explaining the divided operation control method according to the present invention, and FIG. 7 is a diagram showing the temperature of the detection section of the oxygen concentration detector. DESCRIPTION OF SYMBOLS 11... 1st air manifold, 12... 2nd intake manifold, 13... surge tank, 14... 1st exhaust manifold, 15... 2nd exhaust manifold, 17m
. 1.7b...Fuel injection valve, 18...Electronic control unit. 20m, 20b... Oxygen concentration detector, 24... Four two-way valve, 26... Intake cutoff valve, 29... First changeover switch, 3.O... Negative pressure diaphragm device, 4
3... @1 electromagnetic switching valve, 45... 2nd electromagnetic switching valve,
53... Exhaust recirculation passage, 54... Exhaust recirculation valve, 59
...Third electromagnetic switching valve, 63...Second switching switch,
67...Negative pressure sensor. Figure 1 Figure 2

Claims (1)

[Claims] The cylinders are divided into a 10th cylinder group and a 20th cylinder group. The first cylinder group and the second cylinder group are respectively connected to a common surge tank via a first intake passage and a second intake passage, and a cutoff valve is provided in the first intake passage to connect the intake passage to a common surge tank. Open the shutoff valve during high load operation. An exhaust recirculation valve is provided in the exhaust recirculation passage that connects the first intake passage downstream of the intake cutoff valve and the engine exhaust passage, and the exhaust recirculation valve is closed during high engine load operation, and the above-mentioned exhaust recirculation valve is closed during high engine load operation. 9. The internal combustion engine is equipped with a fuel supply device that controls the supply of fuel to the first cylinder group and the second cylinder group, and cuts off the supply of fuel to the first cylinder group during low load operation of the engine. The exhaust passages of the group and the exhaust passages of the second cylinder group are provided independently from each other, and an oxygen concentration detector is disposed in each of the mutually standing exhaust passages, and the oxygen concentration detector is further provided to the first cylinder group. It is equipped with an intake air amount detection device capable of detecting the amount of intake air, and while the intake cutoff valve is in the opening operation, the oxygen concentration detector provided in the exhaust passage of the first cylinder group and the intake air amount detection device are provided. A nine-division operation control type internal combustion engine that controls the fuel supply amount so that the air-fuel ratio of the air-fuel mixture supplied to the first cylinder group becomes the stoichiometric air-fuel ratio based on the output signal of the device.