JP2003074393A - Control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the generation amount of soot in an internal combustion engine. SOLUTION: Fuel supply amount supplied in a combustion chamber corresponding to intake amount supplied to the combustion chamber 5 is controlled. The more the intake amount is, the more the fuel supply amount is increased. First combustion of which the intake amount is less than the predetermined intake amount and the fuel supply amount is less than the predetermined fuel supply amount according to engine demand torque in order to output the engine demand torque, and second combustion of which the intake amount is more than the predetermined intake amount and the fuel supply amount is more than the predetermined fuel supply amount are switched. There is discontinuity between the fuel supply amount immediately before engine combustion is switched from the first combustion to the second combustion and the fuel supply amount immediately before the engine combustion is switched from the second combustion to the first combustion. When the engine combustion is switched from the first combustion to the second combustion, the fuel supply amount is set less than the required amount for outputting the engine demand torque.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an internal combustion engine.

[0002]

2. Description of the Related Art In an internal combustion engine, the amount of soot generated gradually increases and peaks as the amount of exhaust gas supplied to the combustion chamber increases. The first combustion in which the amount of exhaust gas supplied to the combustion chamber is increased, and the amount of exhaust gas supplied to the combustion chamber is less than the amount of exhaust gas in which the amount of soot generation peaks. Japanese Patent Application Laid-Open No. 11-107861 discloses an internal combustion engine in which the combustion of No. 2 is switched.

In the internal combustion engine described in this publication, the amount of fuel supplied to the combustion chamber (hereinafter referred to as the fuel supply amount) is controlled so that the engine required torque is output. That is, the fuel supply amount increases as the engine required torque increases, and the fuel supply amount decreases as the engine required torque decreases.

By the way, when the first combustion is performed in the internal combustion engine described in the above publication, the amount of exhaust gas supplied to the combustion chamber is large, and therefore the amount of air supplied to the combustion chamber is small. There is a limit to increasing the amount. Therefore, the first combustion is performed when the engine required torque is small. On the other hand, when the second combustion is performed, the amount of exhaust gas supplied to the combustion chamber is small, and therefore the amount of air supplied to the combustion chamber is large, so that the fuel supply amount can be relatively increased. Therefore, the second combustion is performed when the engine required torque is large.

[0005]

By the way, when the engine combustion is switched from the first combustion to the second combustion, the amount of exhaust gas supplied into the combustion chamber is reduced, the intake amount is increased, and the fuel is supplied. The quantity is increased. At this time, related devices are controlled so that the amount of exhaust gas supplied into the combustion chamber is reduced stepwise. Therefore, the related device is controlled so that the intake air amount increases stepwise. Then, the related devices are controlled so that the fuel supply amount also increases stepwise in accordance with the intake air amount increasing stepwise. However, although the fuel supply amount increases to a predetermined amount relatively quickly, it takes a relatively long time for the intake amount to increase to a predetermined amount. Therefore, immediately after the engine combustion is switched from the first combustion to the second combustion, the fuel supply amount becomes excessive with respect to the intake air amount, so that the amount of soot generated in the combustion chamber increases.

This is a problem similarly occurring in an internal combustion engine in which the fuel supply amount is increased stepwise when the intake air amount is increased when the engine combustion is switched from one fuel to another.

In view of these problems, an object of the present invention is to reduce the amount of soot generated in an internal combustion engine.

[0008]

In order to solve the above problems, in the first invention, the fuel supply amount supplied to the combustion chamber is controlled corresponding to the intake amount supplied to the combustion chamber, and the intake amount is In an internal combustion engine in which the fuel supply amount is large when the amount is large, in order to output the engine required torque, the intake amount is smaller than the predetermined intake amount and the fuel supply amount is the predetermined fuel amount according to the engine required torque. Switching for switching between first combustion that is less than the supply amount and second combustion that has an intake amount that is greater than the predetermined intake amount and that has a fuel supply amount that is greater than the predetermined fuel supply amount And a fuel supply amount immediately before the engine combustion is switched from the first combustion to the second combustion, and a fuel supply amount immediately before the engine combustion is switched from the second combustion to the first combustion. Has discontinuity in In the engine control device, the torque output by the second combustion is larger than the torque output by the first combustion, and the fuel supply amount is changed when the engine combustion is switched from the first combustion to the second combustion. It is made smaller than the amount required to output the engine required torque.

In order to solve the above-mentioned problems, in the second invention, in the internal combustion engine, the soot generation amount gradually increases and reaches the peak when the amount of the inert gas supplied to the combustion chamber is increased. The first combustion in which the amount of the inert gas supplied to the combustion chamber is greater than the amount of the inert gas at which the amount of generated soot peaks, and the amount of the inert gas at which the amount of soot generated peaks Switching means for switching between the second combustion in which the amount of the inert gas supplied into the combustion chamber is reduced, and
A torque output by second combustion in a control device for an internal combustion engine, comprising: a fuel supply amount control means for controlling a fuel supply amount of fuel supplied into a combustion chamber so that an engine required torque is output. Is larger than the torque output by the first combustion, and the engine combustion changes from the first combustion to the second combustion.
When the combustion is switched to combustion, the fuel supply amount is made smaller than the amount required to output the engine required torque.

According to a third aspect of the present invention, in the first or second aspect of the present invention, an auxiliary torque generating means for generating an auxiliary torque for assisting the output torque of the internal combustion engine is further provided, and the engine combustion starts from the first combustion. The auxiliary torque generating means generates an auxiliary torque for assisting the output torque of the internal combustion engine so that the engine required torque is output when the second combustion is switched to.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show the case where the present invention is applied to a 4-stroke compression ignition type internal combustion engine. 1 and 2, 1 is an engine body, 2 is a cylinder block, 3 is a cylinder head, 4 is a piston, 5 is a combustion chamber, 6 is an electrically controlled fuel injection valve, 7 is an intake valve, and 8 is intake air. Ports, 9 are exhaust valves, and 10 are exhaust ports. The intake port 8 is connected to a surge tank 12 via a corresponding intake branch pipe 11, and the surge tank 12 is connected via a suction duct 13 and an intercooler 14 to a supercharger, for example, the compressor 1 of the exhaust turbocharger 15.
6 is connected to the outlet part. The inlet of the compressor 16 is connected to an air cleaner 19 via an intake duct 17 and an air flow meter 18, and a throttle valve 21 driven by a step motor 20 is arranged in the intake duct 17.

On the other hand, the exhaust port 10 is connected to the exhaust manifold 2
Exhaust turbine 2 of exhaust turbocharger 15 via 2
3 is connected to the inlet portion of the exhaust turbine 23, and the outlet portion of the exhaust turbine 23 is a casing 25 containing a particulate filter 24.
Connected to. The exhaust pipe 26 connected to the outlet of the casing 25 and the intake duct 17 downstream of the throttle valve 21 are connected to each other via an EGR passage 27.
An EGR control valve 29, which is driven by a step motor 28, is arranged in the unit 7. Further, in the EGR passage 27, E
An intercooler 30 for cooling the EGR gas flowing in the GR passage 27 is arranged. In the embodiment shown in FIG. 1, the engine cooling water is guided into the intercooler 30, and the engine cooling water cools the EGR gas.

On the other hand, the fuel injection valve 6 is connected to a fuel reservoir, a so-called common rail 32, via a fuel supply pipe 31. Fuel is supplied into the common rail 32 from an electrically controlled variable fuel discharge pump 33, and the fuel supplied into the common rail 32 is supplied to the fuel injection valve 6 via each fuel supply pipe 31. A fuel pressure sensor 34 for detecting the fuel pressure in the common rail 32 is attached to the common rail 32, and the fuel pump 33 is arranged so that the fuel pressure in the common rail 32 becomes the target fuel pressure based on the output signal of the fuel pressure sensor 34. Is controlled.

On the other hand, in the embodiment shown in FIG. 1, the transmission 35 is connected to the output shaft of the engine, and the electric motor 37 is connected to the output shaft 36 of the transmission 35. In this case, as the transmission 35, a normal automatic transmission including a torque converter,
It is possible to use various continuously variable transmissions or automatic transmissions of a type in which a clutch operation and a gear shift operation in a manual transmission having a clutch are automatically performed.

Further, the electric motor 37 connected to the output shaft 36 of the transmission 35 constitutes a driving force generator for generating a driving force separately from the driving force of the engine. In the embodiment shown in FIG. 1, this electric motor 37 has an output shaft 36 of the transmission 35.
The AC synchronous motor includes a rotor 38 mounted on the upper surface and having a plurality of permanent magnets mounted on the outer peripheral surface thereof, and a stator 39 having an exciting coil wound to form a rotating magnetic field. The exciting coil of the stator 39 is connected to the motor drive control circuit 40, and the motor drive control circuit 40 is connected to the battery 41 that generates a DC high voltage.

The electronic control unit 50 is composed of a digital computer, and has a ROM (Read Only Memory) 52, a RAM (Random Access Memory) 53, a CPU (Microprocessor) 54, an input port 55, which are connected to each other by a bidirectional bus 51. An output port 56 is provided. The output signals of the air flow meter 18 and the fuel pressure sensor 34 are input to the input port 55 via the corresponding AD converters 57, respectively. Air-fuel ratio sensors 43a and 43b are respectively arranged in the exhaust manifold 22 and the exhaust pipe 26, and the output signals of these air-fuel ratio sensors 43a and 43b are input to the input port 55 via the corresponding AD converters 57, respectively. . In addition, various signals representing the gear ratio or speed of the transmission 35, the rotation speed of the output shaft 36, and the like are input to the input port 55.

On the other hand, a load sensor 45 for generating an output voltage proportional to the amount L of depression of the accelerator pedal 44 is connected to the accelerator pedal 44, and the output voltage of the load sensor 45 is input via the corresponding AD converter 57 to the input port. 55 is input. Further, the input port 55 is connected to a crank angle sensor 46 that generates an output pulse each time the crankshaft rotates, for example, 30 °. On the other hand, the output port 56 is connected to the fuel injection valve 6, the step motor 20, the EGR control valve 28, the fuel pump 33, the transmission 35, and the motor drive control circuit 40 via the corresponding drive circuit 58.

Supply of electric power to the exciting coil of the stator 39 of the electric motor 37 is normally stopped, and the rotor 38 is rotating together with the output shaft 36 of the transmission 37 at this time. On the other hand, when driving the electric motor 37, the DC high voltage of the battery 41 is converted in the motor drive control circuit 40 into a three-phase AC having a frequency of fm and a current value of Im, and this three-phase AC is supplied to the exciting coil of the stator 39. To be done. The frequency fm is a frequency required to rotate the rotating magnetic field generated by the exciting coil in synchronization with the rotation of the rotor 38, and the frequency fm is calculated by the CPU 54 based on the rotation speed of the output shaft 36. In the motor drive control circuit 40, this frequency fm is the frequency of the three-phase AC.

On the other hand, the output torque of the electric motor 37 is almost proportional to the current value Im of the three-phase AC. This current value Im is calculated by the CPU 54 based on the required output torque of the electric motor 37, and the motor drive control circuit 40 uses this current value Im as the three-phase AC current value.

When the electric motor 37 is driven by an external force, the electric motor 37 operates as a generator,
The electric power generated at this time is regenerated to the battery 41. Whether the electric motor 37 should be driven by an external force is determined by the CPU 5
4 and when it is determined that the electric motor 37 should be driven by an external force, the motor control circuit 40
Is controlled to be regenerated by the electric power battery 41 generated in the electric motor 37.

FIG. 3 shows another embodiment of the compression ignition type internal combustion engine. In this embodiment, the electric motor 3 is attached to the output shaft 47 of the engine.
7, the transmission 35 is connected to the output shaft of the electric motor 37. In this implementation, the rotor 38 of the electric motor 37
Are mounted on the output shaft 47 of the engine, so that the rotor 38 always rotates with the output shaft 47 of the engine.
Also in this embodiment, as the transmission 35, an ordinary automatic transmission having a torque converter, various continuously variable transmissions, or a manual transmission having a clutch is automatically operated for clutch operation and speed change operation. It is possible to use an automatic transmission of the above type.

The vertical axis TQ of FIG. 4 shows the required torque for the engine, the horizontal axis N shows the engine speed, and each solid line shows the required torque TQ and the engine speed N at the same depression amount of the accelerator pedal 44. Shows the relationship with. Further, in FIG. 4, the solid line A shows the amount of depression of the accelerator pedal 44 is zero, the solid line B shows the maximum amount of depression of the accelerator pedal 44, and the amount of depression of the accelerator pedal 44 from the solid line A to the solid line B is shown. Is increasing. In the embodiment of the present invention, the required torque TQ corresponding to the depression amount L of the accelerator pedal 44 and the engine speed N is first calculated from the relationship shown in FIG. 4, and the fuel injection amount and the like are calculated based on this required torque TQ. To be done.

Next, operation control during acceleration operation and deceleration operation will be described. In the embodiment according to the present invention, the electric motor 37 is driven during the acceleration operation so that a good acceleration operation can be obtained even during the acceleration operation in the operation region where the exhaust turbocharger 15 does not operate. On the other hand, during deceleration operation, the electric motor 37 is operated as a generator, and the generated electric power is regenerated.

FIG. 5 shows a processing routine at the time of acceleration / deceleration, and this routine is executed by interruption at regular time intervals.

Referring to FIG. 5, first step 10
At 0, for example, it is judged from the change amount ΔL (> 0) of the depression amount L of the accelerator pedal 44 whether or not the acceleration operation is being performed. If it is during acceleration operation, the routine proceeds to step 101, where the output torque Tm to be generated by the electric motor 37 is calculated. The output torque Tm increases as the amount of change ΔL in the depression amount L of the accelerator pedal 44 increases, as shown in FIG. Next, at step 102, the current value Im of the three-phase alternating current to be supplied to the electric motor 37 in order to generate the output torque Tm is calculated. Next, at step 103, based on the engine speed N, the electric motor 37
The frequency fm of the three-phase alternating current to be supplied to is calculated. Next, at step 104, the three-phase alternating current having a current value of Im and a frequency of fm is supplied to the electric motor 37, and thereby the electric motor 37 is driven. In this way, during acceleration operation, the output torque of the electric motor 37 is superimposed on the output torque of the engine.

Next, at step 105, for example, it is judged from the depression amount L of the accelerator pedal 44 and the engine speed N whether or not it is during deceleration operation. When the vehicle is in deceleration operation, the routine proceeds to step 106, where the electric motor 37 is made to operate as a generator, and the generated electric power is regenerated to the battery 41.

By the way, in the internal combustion engine of this embodiment, by controlling the opening degree of the EGR control valve 29 and the opening degree of the throttle valve 21, the amount of exhaust gas (that is, inert gas) introduced into the combustion chamber 5 is controlled. Can be controlled. Then, in the internal combustion engine of the present embodiment, as the amount of exhaust gas introduced into the combustion chamber 5 (hereinafter referred to as the EGR gas amount) is increased, the soot generation amount gradually increases and reaches a peak, and the EGR gas amount is increased. When the temperature is further increased, the temperature of the fuel and the gas around it during combustion in the combustion chamber 5 becomes lower than the soot generation temperature, and soot is hardly generated.

Since the amount of soot generated differs depending on the amount of EGR gas as described above, the first combustion in which the amount of EGR gas in the combustion chamber 5 is larger than the amount of EGR gas at which the amount of soot generated reaches a peak in this embodiment. And the second combustion in which the amount of EGR gas in the combustion chamber 5 is smaller than the amount of EGR gas at which the amount of soot generated reaches a peak is switched according to the required torque, so that the amount of soot generated is suppressed to a small amount. There is. In this embodiment, the first combustion is performed when the required torque is relatively small, and the second combustion is performed when the required torque is relatively large.

By the way, when the engine combustion is switched from the first combustion to the second combustion, the EGR gas amount is reduced beyond the amount at which the soot generation amount reaches the peak. Therefore, at this time, the EGR gas amount is relatively rapidly reduced stepwise. Therefore, at this time, the amount of air taken into the combustion chamber 5 (hereinafter referred to as the intake amount) is relatively rapidly increased stepwise. Then, according to the normal operation control of the present embodiment that calculates the fuel injection amount according to the required torque, the fuel injection amount can be increased stepwise if not rapidly with the stepwise increase of the intake air amount. It will be.

That is, between the fuel injection amount immediately before the engine combustion is switched from the first combustion to the second combustion and the fuel injection amount immediately before the engine combustion is switched from the second combustion to the first combustion. Have a relatively large difference and are not continuous.

As described above, according to the present embodiment, when the engine combustion is switched from the first combustion to the second combustion, the device related to increase the intake air stepwise, the throttle valve 21 in this embodiment. And the EGR control valve 29 are controlled. However, in reality, the fuel injection amount is immediately increased, but the intake air amount is not immediately increased. That is, the time taken to increase the actual intake air amount is longer than the time taken to increase the actual fuel injection amount. Therefore, when the engine combustion is switched from the first combustion to the second combustion, the intake amount does not increase so much when the increased amount of fuel is injected according to the normal operation control of the present embodiment, Therefore, the fuel becomes excessive with respect to the amount of air in the combustion chamber 5. For this reason, the fuel is difficult to burn and the amount of soot generated increases.

Therefore, in this embodiment, when the engine combustion is switched from the first combustion to the second combustion, the fuel injection amount is made smaller than the amount required to generate the required torque, and a certain predetermined time elapses. Then, the switching operation control for maintaining the fuel injection amount at this reduced amount is executed until the intake amount sufficiently increases, and after the predetermined amount of time elapses, the intake amount normally increases and then the normal operation is performed. The operation control of is executed.

In this embodiment, the amount of fuel injection that is smaller than the amount required to generate the required torque is smaller than the amount of fuel injection immediately before the engine combustion is switched from the first combustion to the second combustion. Is adopted. Therefore, in this embodiment, when the engine combustion is switched from the first combustion to the second combustion, the fuel injection amount is made smaller than the fuel injection amount immediately before the engine combustion is switched from the first combustion to the second combustion. , The switching operation control for maintaining the fuel injection amount at this reduced amount is executed until the intake amount sufficiently increases after a certain predetermined time elapses, and the intake amount after a certain predetermined time elapses. After that, the normal operation control is executed.

As another embodiment, instead of maintaining the fuel injection amount at this reduced amount until the intake amount sufficiently increases after a certain predetermined time, a certain predetermined time elapses. The fuel injection amount may be gradually increased toward the fuel injection amount calculated by the normal fuel injection control until the intake amount sufficiently increases.

As described above, the increase in the amount of soot generated is suppressed by executing the switching operation control according to the present embodiment.

By the way, while the switching operation control is executed according to the present embodiment, the fuel injection amount is made smaller than the amount required to output the required torque. Therefore, the output torque is less than the required torque. This is not preferable from the viewpoint of surely outputting the required torque.

Therefore, in this embodiment, when the switching operation control is being executed, the shortage of the actually output torque with respect to the required torque is calculated, and this shortage of torque is supplemented by the auxiliary torque from the electric motor 37. To do so. That is, when the switching operation control is being executed, the electric motor 37 is caused to generate, as the auxiliary torque, a torque capable of compensating for the shortage of the torque output by the engine body 1 with respect to the required torque. According to this, the required torque is output as a whole.

FIG. 7 is a time chart showing changes in the intake air amount Ga, the fuel injection amount Q, and the auxiliary torque ATQ from the electric motor 37 when the switching operation control of this embodiment is executed. According to the switching operation control of the present embodiment as shown in FIG. 7, when the engine combustion is switched from the first combustion to the second combustion at time t ₁ , the EGR control valve 29
And the opening of the throttle valve 21 is increased, and the intake air amount Ga gradually increases. However, the intake air amount Ga does not reach the target intake air amount TGa immediately.

On the other hand, when the engine combustion is switched from the first combustion to the second combustion, the fuel injection amount Q is set to the amount Qb smaller than the fuel injection amount Qa when the first combustion is performed, and the electric An auxiliary torque ATQb is generated from the motor 37. Until time t ₂ when the intake air amount Ga reaches the target intake air amount TGa, the fuel injection amount Q is maintained at the small amount Qb, and the electric motor 37 continues to generate the auxiliary torque ATQb.

When the intake air amount Ga reaches the target intake air amount TGa, the fuel injection amount Q is set to the fuel injection amount Qc calculated by the normal operation control when the second fuel is being supplied. Generation of auxiliary torque is stopped.

FIG. 8 is a flow chart for executing the operation control of this embodiment. Referring to FIG. 8, first, at step 200, it is judged if the flag showing that the operating state of the internal combustion engine is in the first operating region I is set or not. When it is determined in step 200 that the flag is set, that is, when the operating state of the internal combustion engine is in the first operating state I, step 201
Then, it is determined whether the required torque L has become larger than the first boundary X (N) (L> X (N)).

When it is judged at step 201 that L≤X (N), the routine proceeds to step 203, where the operation control I for performing the first combustion is executed. That is, in step 203, the target opening degree ST of the throttle valve 21 is calculated, the opening degree of the throttle valve 21 is set to this target opening degree ST, then the target opening degree SE of the EGR control valve 29 is calculated, and the target opening degree SE of the EGR control valve 29 is calculated. The opening is set to this target opening SE, then the target air-fuel ratio A / F is calculated, the target fuel injection amount Q is calculated so that the air-fuel ratio becomes the target air-fuel ratio A / F, and then the target injection start timing θS. Is calculated, and finally the fuel of the target fuel injection amount Q is injected from the fuel injection valve 6 at the target injection start timing θS.

On the other hand, in step 201, L> X
If it is determined to be (N), the routine proceeds to step 202, where the flag is reset, then the routine proceeds to step 206, and the switching operation control is executed according to the flowchart shown in FIG. This will be described later.

When it is determined in step 200 that the flag is reset, that is, when the operating state of the internal combustion engine is in the second operating state II, step 204
Then, it is determined whether the required torque L has become smaller than the second boundary Y (N) (L <Y (N)).

When it is judged at step 204 that L ≧ Y (N), the routine proceeds to step 207, where the operation control II for performing the second combustion is executed. That is, in step 203, the target opening degree ST of the throttle valve 21 is calculated, the opening degree of the throttle valve 21 is set to this target opening degree ST, then the target opening degree SE of the EGR control valve 29 is calculated, and the target opening degree SE of the EGR control valve 29 is calculated. The opening is set to this target opening SE, then the target air-fuel ratio A / F is calculated, the target fuel injection amount Q is calculated so that the air-fuel ratio becomes the target air-fuel ratio A / F, and then the target injection start timing θS. Is calculated, and finally the fuel of the target fuel injection amount Q is injected from the fuel injection valve 6 at the target injection start timing θS.

On the other hand, in step 204, L <Y
When it is determined to be (N), the routine proceeds to step 205, where the flag is set, then the routine proceeds to step 203, where the operation control I is executed.

Next, the switching operation control will be described with reference to FIG. In the flowchart of FIG. 9, first, at step 300, the intake air amount Ga is read. Next, at step 301, it is judged if the intake air amount Ga is substantially the target intake air amount TGa (Ga≈TGa). When it is determined in step 301 that Ga≈TGa, the processing ends. In this case, the routine of FIG. 8 proceeds to step 207 via steps 200 and 204, so that the second operation control II is executed.

On the other hand, in step 301, Ga≈TG
If it is determined that the value is not a, step 302
And the third operation control III is executed. That is, the target opening degree ST of the throttle valve 21 and the EGR control valve 2
The target opening degree SE of 9 is calculated according to the second operation control II, and the opening degree of the throttle valve 21 is set to the target opening degree ST.
The opening degree of the GR control valve 29 is set to the target opening degree, the target fuel injection start timing θS is calculated according to the second operation control II, and the target fuel injection amount Q is the engine combustion from the first combustion to the second combustion.
Is set to a quantity Qb which is smaller than the fuel injection quantity immediately before the combustion is switched to combustion, and the small quantity Qb of fuel is injected from the fuel injection valve 6 at the target fuel injection start timing θS.

Next, the routine proceeds to step 303, where the flag is set. In this case, the routine of FIG.
Since the process proceeds to step 206 via 00, 201 and 202, the third operation control III is executed until it is determined that Ga≈TGa in step 301 of FIG.

Finally, the first combustion and the second combustion will be described in detail. FIG. 10 shows changes in output torque when the air-fuel ratio A / F (horizontal axis in FIG. 10) is changed by changing the opening degree of the throttle valve 21 and the EGR rate during engine low load operation, and smoke, HC, An example of an experiment showing changes in CO and NOx emissions is shown. As can be seen from FIG. 10, in this experimental example, the EGR rate increases as the air-fuel ratio A / F decreases, and when the air-fuel ratio is equal to or less than the theoretical air-fuel ratio (≈14.6), the EGR rate is 65% or more.

As shown in FIG. 10, when the air-fuel ratio A / F is reduced by increasing the EGR rate, the EGR rate becomes around 40%, and when the air-fuel ratio A / F becomes about 30, smoke is generated. The amount of generation begins to increase. Next, when the EGR rate is further increased and the air-fuel ratio A / F is reduced, the amount of smoke generated sharply increases and reaches a peak. Next, when the EGR rate is further increased and the air-fuel ratio A / F is reduced, the smoke sharply decreases this time, the EGR rate is increased to 65% or more, and the smoke becomes almost zero when the air-fuel ratio A / F is around 15.0. . That is, soot is hardly generated. At this time, the output torque of the engine is slightly reduced, and the amount of NOx generated is considerably reduced. On the other hand, at this time H
The amount of C and CO generation starts to increase.

FIG. 11 (A) shows the change in combustion pressure in the combustion chamber 5 when the air-fuel ratio A / F is around 21 and the amount of smoke generated is the largest, and FIG. 11 (B) shows the air-fuel ratio A / F. F is 18
The graph shows the change in combustion pressure in the combustion chamber 5 when the amount of smoke generated is near zero. FIG. 11A and FIG.
As can be seen by comparing with (B), the combustion pressure in the case shown in FIG. 11 (B) in which the smoke generation amount is almost zero is larger than that in the case in which the smoke generation amount is large in FIG. 11 (A). It turns out that is low.

From the experimental results shown in FIGS. 10 and 11, the following can be said. That is, first, when the air-fuel ratio A / F is 15.0 or less and the amount of smoke generated is almost zero, the amount of NOx generated is considerably reduced as shown in FIG.
A decrease in the amount of NOx generated means that the combustion temperature in the combustion chamber 5 has decreased. Therefore, it can be said that the combustion temperature in the combustion chamber 5 is low when almost no soot is generated. . The same can be said from FIG. That is, soot is hardly generated in FIG.
In the state shown in (B), the combustion pressure is low, and therefore the combustion temperature in the combustion chamber 5 is low at this time.

Second, when the amount of smoke produced, that is, the amount of soot produced, becomes almost zero, the amounts of HC and CO discharged increase as shown in FIG. This means that hydrocarbons are discharged without growing to soot. That is, the linear hydrocarbons and aromatic hydrocarbons contained in the fuel as shown in FIG. 12 are thermally decomposed to form soot precursors when the temperature is raised in a state of oxygen deficiency, and then mainly carbon is formed. Soot is produced that is made up of solids of atoms. In this case, the actual soot formation process is complicated, and it is not clear what form the soot precursor will take, but in any case, the hydrocarbon as shown in FIG. After that, it will grow to soot. Therefore, as described above, when the soot generation amount becomes almost zero, the HC and CO emission amounts increase as shown in FIG. 10, but at this time, the HC is a soot precursor or a hydrocarbon in the state before it. .

Summarizing these considerations based on the experimental results shown in FIGS. 10 and 11, the soot generation amount becomes almost zero when the combustion temperature in the combustion chamber 5 is low, and at this time, the soot precursor or the soot precursor. The hydrocarbons in this state are discharged from the combustion chamber 5. As a result of further detailed experimental research on this fact, when the temperature of the fuel in the combustion chamber 5 and the gas around it is below a certain temperature, the soot growth process stops halfway, that is, soot is generated. It was found that soot was not generated at all and soot was generated when the temperature of the fuel and its surroundings in the combustion chamber 5 reached a certain temperature or higher.

By the way, the temperature of the fuel and its surroundings when the hydrocarbon production process stops in the state of the soot precursor, that is, the above-mentioned certain temperature depends on various factors such as the type of fuel and the compression ratio of the air-fuel ratio. It cannot be said how many times it changes, but this certain temperature has a deep relationship with the amount of NOx produced, so this certain temperature can be defined to some extent from the amount of NOx produced. it can. Ie E
As the GR rate increases, the temperature of the fuel during combustion and the gas surrounding it decrease, and the amount of NOx generated decreases. At this time, soot is hardly generated when the NOx generation amount becomes around 10 p.pm or less. Therefore, the above-mentioned certain temperature is almost the same as the temperature when the amount of NOx generated becomes about 10 p.pm or less.

Once soot is produced, this soot cannot be purified by post-treatment with a catalyst having an oxidizing function. On the other hand, the soot precursor or the hydrocarbon in the state before the soot can be easily purified by post-treatment using a catalyst having an oxidizing function. Considering the post-treatment with a catalyst having an oxidizing function in this way, hydrocarbons are discharged from the combustion chamber 5 in the state of soot precursor or in the state before it, or
Alternatively, there is an extremely large difference in whether or not the soot is discharged from the combustion chamber 5. The new combustion system employed in the present invention allows hydrocarbons to be discharged from the combustion chamber 5 in the form of soot precursors or in the pre-existing state without producing soot in the combustion chamber 5. The core is to oxidize with a catalyst having an oxidizing function.

Now, in order to stop the growth of hydrocarbons before the soot is generated, the temperature of the fuel and the gas around it in the combustion chamber 5 during combustion is set to a temperature lower than the temperature at which the soot is generated. It needs to be suppressed. In this case, it has been found that, in order to suppress the temperature of the fuel and the gas around it, the endothermic action of the gas around the fuel when the fuel burns has an extremely large effect.

That is, when only air exists around the fuel, the evaporated fuel immediately reacts with oxygen in the air and burns. In this case, the temperature of the air separated from the fuel does not rise so much, and only the temperature around the fuel locally becomes extremely high. That is, at this time, the air separated from the fuel hardly absorbs the combustion heat of the fuel. In this case, since the combustion temperature locally becomes extremely high, the unburned hydrocarbons that have received this heat of combustion will generate soot.

On the other hand, the situation is slightly different when the fuel is present in a mixed gas of a large amount of inert gas and a small amount of air.
In this case, the evaporated fuel diffuses into the surroundings, reacts with oxygen mixed in the inert gas, and burns. In this case, the combustion heat is absorbed by the surrounding inert gas, so that the combustion temperature does not rise so much. That is, the combustion temperature can be kept low. That is, the presence of the inert gas plays an important role in suppressing the combustion temperature, and the combustion temperature can be suppressed low by the endothermic action of the inert gas.

In this case, in order to suppress the temperature of the fuel and the gas around it to a temperature lower than the temperature at which soot is generated, an amount of inert gas sufficient to absorb the amount of heat required to do so is required. . Therefore, if the fuel amount increases, the required amount of inert gas also increases accordingly. In this case, the larger the specific heat of the inert gas, the stronger the endothermic action, and therefore the inert gas is preferably a gas having a large specific heat. In this respect, since CO ₂ and EGR gas have relatively large specific heat, it can be said that it is preferable to use EGR gas as the inert gas.

FIG. 13 shows the relationship between the EGR rate and smoke when EGR gas is used as the inert gas and the cooling degree of the EGR gas is changed. That is, in FIG. 13, the curve A shows the case where the EGR gas is strongly cooled to maintain the EGR gas temperature at about 90 ° C., and the curve B shows the case where the EGR gas is cooled with a small cooling device. Curve C shows the case where the EGR gas is not forcibly cooled.

As shown by the curve A in FIG. 13, when the EGR gas is strongly cooled, the soot generation amount peaks when the EGR rate is slightly lower than 50%, and in this case, the EGR rate is almost 55. Almost no soot is generated if the percentage is exceeded.

On the other hand, as shown by the curve B in FIG.
When the R gas is slightly cooled, the soot generation peaks when the EGR rate is slightly higher than 50%,
In this case, if the EGR rate is set to about 65% or more, soot is hardly generated.

As shown by the curve C in FIG. 13, the EGR
When the gas is not forcibly cooled, the EGR rate is 55
The amount of soot generated reaches a peak in the vicinity of the percentage, and in this case, if the EGR rate is set to approximately 70% or more, the soot hardly occurs.

FIG. 13 shows the amount of smoke generated when the engine torque is relatively high. When the engine torque becomes small, the EGR rate at which the amount of soot generated reaches a peak decreases slightly, and soot hardly occurs. The lower limit of the EGR rate also decreases slightly. In this way, soot is hardly generated EG
The lower limit of the R ratio changes depending on the cooling degree of EGR gas and the engine torque.

FIG. 14 shows a mixture of EGR gas and air which is necessary to bring the temperature of the fuel and its surrounding gas at the time of combustion to a temperature lower than the temperature at which soot is produced when EGR gas is used as the inert gas. The amount of gas, the ratio of air in this mixed gas amount, and the ratio of EGR gas in this mixed gas are shown. In FIG. 14, the vertical axis represents the total amount of intake gas drawn into the combustion chamber 5, and the dashed line Y
Indicates the total amount of intake gas that can be drawn into the combustion chamber 5 when supercharging is not performed. The horizontal axis represents the required torque.

Referring to FIG. 14, the ratio of air, that is, the amount of air in the mixed gas, shows the amount of air required to completely burn the injected fuel. That is, in the case shown in FIG. 14, the ratio between the air amount and the injected fuel amount is the stoichiometric air-fuel ratio. On the other hand, in FIG. 14, the ratio of the EGR gas, that is, the amount of the EGR gas in the mixed gas makes the temperature of the fuel and its surrounding gas lower than the temperature at which soot is formed when the injected fuel is burned. The minimum required EGR gas amount is shown. This EGR gas amount is E
The GR rate is approximately 55% or more, and the graph of FIG.
In the example shown in FIG. That is, the total intake gas amount sucked into the combustion chamber 5 is indicated by a solid line X in FIG. 14, and the air amount and E
When the ratio with respect to the GR gas amount is set to the ratio shown in FIG. 14, the temperature of the fuel and the gas around it becomes lower than the temperature at which soot is generated, so that soot is not generated at all. The amount of NOx generated at this time is around 10 p.pm,
Or less, and therefore the amount of NOx generated is extremely small.

When the fuel injection amount increases, the amount of heat generated when the fuel burns increases. Therefore, in order to maintain the temperature of the fuel and the gas around it at a temperature lower than the temperature at which soot is generated, heat generated by the EGR gas is used. The amount of absorption must be increased. Therefore, as shown in FIG. 14, the EGR gas amount must be increased as the injected fuel amount is increased. That is, the EGR gas amount needs to increase as the required torque increases.

By the way, when the supercharging is not performed, the upper limit of the total intake gas amount X sucked into the combustion chamber 5 is Y. Therefore, in FIG. 14, the required torque is larger in the region where the required torque is larger than Lo. EGR as it gets bigger
The air-fuel ratio cannot be maintained at the stoichiometric air-fuel ratio unless the gas ratio is reduced. In other words, if the air-fuel ratio is to be maintained at the stoichiometric air-fuel ratio in the region where the required torque is larger than Lo when supercharging is not performed, the EGR rate decreases as the required torque increases, thus In the region where the required torque is larger than Lo, the temperature of the fuel and the gas around it cannot be maintained below the temperature at which soot is generated.

However, as shown in FIG. 1, the EGR passage 2
When the EGR gas is recirculated to the inlet side of the supercharger, that is, in the intake duct 17 of the exhaust turbocharger 15 via 7, the EGR is performed in a region where the required torque is larger than Lo.
The rate can be maintained above 55 percent, for example 70 percent, thus maintaining the fuel and surrounding gas temperatures below the temperature at which soot is produced. That is, if the EGR gas is recirculated so that the EGR rate in the intake duct 17 becomes, for example, 70%, the compressor 1 of the exhaust turbocharger 15
The EGR rate of the intake gas boosted by 6 also becomes 70%, and thus, the temperature of the fuel and the gas around it can be maintained at a temperature lower than the temperature at which soot is generated up to the limit at which the compressor 16 can boost the pressure. . Therefore, the operating range of the engine capable of producing the low temperature combustion can be expanded. Required torque is Lo
When the EGR rate is 55% or more in a larger region, the EGR control valve 29 is fully opened and the throttle valve 21 is slightly closed.

As described above, FIG. 14 shows the case where the fuel is burned under the stoichiometric air-fuel ratio.
The amount of NOx can be reduced to around 10 p.pm or less while preventing the generation of soot even if the amount of air is less than the amount shown in the table, that is, even if the air-fuel ratio is rich. Even if the amount of air is larger than that shown in 14, that is, even if the average value of the air-fuel ratio is lean from 17 to 18, the amount of NOx generated should be around 10 p.pm or less while preventing the generation of soot. You can

That is, when the air-fuel ratio is made rich, the fuel becomes excessive, but since the combustion temperature is suppressed to a low temperature, the excessive fuel does not grow to soot, and soot is generated. Absent. At this time, NOx is also generated in an extremely small amount. On the other hand, when the average air-fuel ratio is lean, or even when the air-fuel ratio is the stoichiometric air-fuel ratio, a small amount of soot is generated if the combustion temperature becomes high, but in the present invention the combustion temperature is suppressed to a low temperature, soot Not generated at all. Further NOx
Also produces only a very small amount.

When low temperature combustion is performed in this manner, soot is generated regardless of the air-fuel ratio, that is, whether the air-fuel ratio is rich, the stoichiometric air-fuel ratio, or the average air-fuel ratio is lean. Not generated, and the amount of NOx generated is extremely small. Therefore, considering the improvement of the fuel consumption rate, it can be said that it is preferable to make the average air-fuel ratio lean at this time.

By the way, the temperature of the fuel and the gas around it during combustion in the combustion chamber can be suppressed below the temperature at which the growth of hydrocarbons stops halfway only when the engine is operating at a low load, where the calorific value of combustion is relatively small. To be Therefore, in the embodiment according to the present invention, during low load operation in the engine, the temperature of the fuel and the gas around it during combustion is suppressed below the temperature at which the growth of hydrocarbons stops halfway, and the first combustion, that is, low temperature combustion is performed. In addition, the second combustion, that is, the combustion normally performed from the conventional one is performed during the engine high load operation. It should be noted that the first combustion, that is, low-temperature combustion, is clear here from the above description that the amount of inert gas in the combustion chamber is larger than the amount of inert gas at which the amount of soot is peaked, and soot is hardly generated. The term "combustion" means the second combustion, that is, combustion that is more commonly performed than before, and that the amount of inert gas in the combustion chamber is smaller than the amount of inert gas at which the amount of soot generated peaks. Say

FIG. 15 shows the first operating region I where the first combustion, that is, the low temperature combustion is performed, and the second operating region II where the second combustion, that is, the combustion by the conventional combustion method is performed. There is. In FIG. 15, the vertical axis TQ shows the required torque, and the horizontal axis N shows the engine speed. Further, in FIG. 15, X (N) indicates a first boundary dividing the first operating region I and the second operating region II, and Y (N)
(N) indicates a second boundary that divides the first operating region I and the second operating region II. From the first operating region I to the second
The first boundary X is used to judge the change of the operating range to the operating range II of
Based on (N), the change judgment of the operating range from the second operating range II to the first operating range I is performed on the second boundary Y.
It is performed based on (N).

That is, when the engine operating condition is in the first operating region I and low temperature combustion is performed, the required torque T
When Q exceeds the first boundary X (N) which is a function of the engine speed N, it is determined that the operating region has moved to the second operating region II, and combustion is performed by the conventional combustion method. Next, the required torque TQ is the second boundary Y which is a function of the engine speed N.
When it becomes lower than (N), it is determined that the operating region has moved to the first operating region I, and low temperature combustion is performed again.

In this way, the two boundaries of the first boundary X (N) and the second boundary Y (N) on the side of lower torque than the first boundary X (N) are provided as follows. For one reason. The first reason is that the combustion temperature is relatively high on the high torque side of the second operating region II, and at this time the required torque TQ is the first boundary X.
This is because even if the temperature becomes lower than (N), low temperature combustion cannot be performed immediately. That is, the low temperature combustion is not started immediately unless the required torque TQ becomes considerably low, that is, when it becomes lower than the second boundary Y (N). The second reason is the first operating region I and the second operating region.
This is to provide a hysteresis with respect to a change in the operating area between the II and II.

The engine operating region is the first operating region I.
Therefore, soot is hardly generated when the low temperature combustion is performed, and instead, unburned hydrocarbons are discharged from the combustion chamber 5 in the form of the soot precursor or the state before it. At this time, the unburned hydrocarbons discharged from the combustion chamber 5 are satisfactorily oxidized by the catalyst having an oxidizing function. Therefore, the particulate filter 24 has an oxidation catalyst such as NO.
x It is preferable to carry an absorbent to oxidize and remove unburned hydrocarbons.

The NOx absorbent has a function of absorbing NOx when the average air-fuel ratio in the combustion chamber 5 is lean, and releasing NOx when the average air-fuel ratio in the combustion chamber 5 becomes rich. This NOx absorbent uses, for example, alumina as a carrier, and potassium K, sodium Na,
At least one selected from alkali metals such as lithium Li and cesium Cs, alkaline earths such as barium Ba and calcium Ca, rare earths such as lanthanum La and yttrium Y, and a noble metal such as platinum Pt are supported. ing.

Next, referring to FIG. 16, the first operating region I
The operation control in the second operation area II will be briefly described. FIG. 16 shows the opening of the throttle valve 21, the opening of the EGR control valve 29, the EGR with respect to the required torque TQ.
The ratio, the air-fuel ratio, the injection timing and the injection amount are shown. Figure 1
As shown in FIG. 6, in the first operating region I where the required torque TQ is low, the opening degree of the throttle valve 21 is gradually increased from near full close to about 2/3 opening degree as the required torque TQ increases, and the EGR The opening degree of the control valve 29 is the required torque T
As Q increases, it is gradually increased from near fully closed to fully open. Further, in the example shown in FIG. 16, the EGR rate is approximately 70% in the first operating region I,
The air-fuel ratio is considered to be slightly lean.

In other words, in the first operating region I, EGR
The opening of the throttle valve 21 and the opening of the EGR control valve 29 are controlled so that the ratio becomes approximately 70% and the air-fuel ratio becomes a lean air-fuel ratio which is slightly lean. In the first operating region I, fuel injection is performed before the compression top dead center TDC. In this case, the injection start timing θS is the required torque L
Becomes higher and the injection completion timing θE becomes later as the injection start timing θS becomes later.

During idling operation, the throttle valve 21 is closed until it is almost fully closed. At this time, the EGR control valve 2
9 is also closed to near full closure. Throttle valve 21
When the valve is closed to near full closure, the pressure in the combustion chamber 5 at the beginning of compression becomes low, and the compression pressure becomes small. When the compression pressure becomes small, the compression work by the piston 4 becomes small, so that the vibration of the engine body 1 becomes small. That is, in idling operation, the throttle valve 21 is closed to close the throttle valve 21 in order to suppress the vibration of the engine body 1.

On the other hand, the operating condition of the engine is the first operating region I.
When changing from the second operating range II to the second operating range II, the opening degree of the throttle valve 21 is increased stepwise from about 2/3 opening degree toward the full opening direction. At this time, in the example shown in FIG. 16, the EGR rate is reduced stepwise from approximately 70% to 40% or less, and the air-fuel ratio is increased stepwise. That is, the EGR rate causes a large amount of smoke E
Since the GR rate range is skipped (see FIG. 13), a large amount of smoke does not occur when the operating state of the engine changes from the first operating region I to the second operating region II.

In the second operating region II, the conventional combustion is performed. In the second operating region II, the throttle valve 21 is kept fully open except for a part, and the opening degree of the EGR control valve 29 is gradually reduced as the required torque L increases. Further, in this operating region II, the EGR rate becomes lower as the required torque TQ becomes higher, and the air-fuel ratio becomes equal to the required torque TQ.
It becomes smaller as Q becomes higher. However, the air-fuel ratio is a lean air-fuel ratio even if the required torque TQ becomes high. The second
In the operating region II of, the injection start timing θS is the compression top dead center TDC.
It is said to be in the vicinity.

FIG. 17 shows the target air-fuel ratio A / F in the first operating region I. In FIG. 17, A / F = 1
The respective curves shown by 5.5, A / F = 16, A / F = 17, A / F = 18 have air-fuel ratios of 15.5, 16, 17,
18 is shown, and the air-fuel ratio between the curves is determined by proportional distribution. As shown in FIG. 17, the air-fuel ratio is lean in the first operating region I, and
In the operating region I, the target air-fuel ratio A / F becomes leaner as the required torque TQ becomes lower.

That is, the lower the required torque TQ, the smaller the amount of heat generated by combustion. Therefore, the required torque T
As the Q becomes lower, the low temperature combustion can be performed even if the EGR rate is lowered. When the EGR rate is reduced, the air-fuel ratio increases, so that the required torque T as shown in FIG.
The target air-fuel ratio A / F is increased as Q decreases. The fuel consumption rate increases as the target air-fuel ratio A / F increases, and therefore, in order to make the air-fuel ratio as lean as possible, in the embodiment of the present invention, the target air-fuel ratio A / F is increased as the required torque TQ decreases. .

The fuel injection amount Q in the first operation region I is stored in advance in the ROM 52 in the form of a map as a function of the required torque TQ and the engine speed N as shown in FIG. As shown in FIG. 18 (B), the injection start timing θS in the operating region I of No. 1 is a ROM in advance in the form of a map as a function of the required torque TQ and the engine speed N.
Stored in 52.

FIG. 1 shows the air-fuel ratio according to the operating condition of the engine.
The target opening degree ST of the throttle valve 21 required to set the target air-fuel ratio A / F shown in 7 and the EGR rate to the target EGR rate according to the operating state of the engine is as shown in FIG. 19 (A). The map is pre-stored in the ROM 52 as a function of the required torque TQ and the engine speed N, and the air-fuel ratio is the target air-fuel ratio A / shown in FIG. 17 according to the operating state of the engine.
F and set the EGR rate to the target EG according to the operating state of the engine.
The target opening degree SE of the EGR control valve 29 required to obtain the R rate
Is stored in advance in the ROM 52 in the form of a map as a function of the required torque TQ and the engine speed N as shown in FIG.

FIG. 20 shows the target air-fuel ratio A / when the second combustion, that is, the normal combustion by the conventional combustion method is performed.
F is shown. Note that in FIG. 20, A / F = 24, A
The curves shown by / F = 35, A / F = 45, A / F = 60 show the air-fuel ratios of 24, 35, 45 and 60, respectively.

The target fuel injection amount Q when the second combustion is performed is stored in advance in the form of a map in the form of a ROM as a function of the required torque TQ and the engine speed N as shown in FIG.
The target injection start timing θS when the second combustion is performed is stored in the ROM 52 and is stored in the ROM 52 in advance in the form of a map as a function of the required torque TQ and the engine speed N as shown in FIG. It is stored in.

FIG. 2 shows the air-fuel ratio according to the operating state of the engine.
The target opening degree ST of the throttle valve 21 required to set the target air-fuel ratio A / F shown in 0 and the EGR rate to the target EGR rate according to the operating state of the engine is as shown in FIG. 22 (A). The map is pre-stored in the ROM 52 as a function of the required torque TQ and the engine speed N, and the air-fuel ratio is set to the target air-fuel ratio A / shown in FIG. 20 according to the operating state of the engine.
F and set the EGR rate to the target EG according to the operating state of the engine.
The target opening degree SE of the EGR control valve 29 required to obtain the R rate
Is stored in advance in the ROM 52 in the form of a map as a function of the required torque TQ and the engine speed N as shown in FIG.

[0093]

According to the present invention, when the engine combustion is switched from the first combustion to the second combustion, the fuel supply amount is made smaller than the amount required to output the required torque. When the engine combustion is switched from the first combustion to the second combustion, the internal combustion engine is controlled to increase the intake amount, but actually it takes time for the intake amount to reach the target intake amount. Therefore, if the fuel supply amount when the engine combustion is switched from the first combustion to the second combustion as in the present invention is made smaller than the amount required to output the required torque, the actual intake amount Therefore, the amount of soot generated can be suppressed to a low level because the fuel is not excessive.

[Brief description of drawings]

FIG. 1 is an overall view of a compression ignition type internal combustion engine.

FIG. 2 is a side sectional view of an engine body.

FIG. 3 is a diagram showing a required torque.

FIG. 4 is an overall view showing another embodiment of a compression ignition type internal combustion engine.

FIG. 5 is a flowchart for performing acceleration / deceleration processing.

FIG. 6 is a diagram showing output torque to be generated by the electric motor.

FIG. 7 is a time chart for explaining the switching operation control of the present embodiment.

FIG. 8 is a flowchart for executing the operation control of this embodiment.

FIG. 9 is a flowchart for executing switching operation control according to the present embodiment.

FIG. 10 is a diagram showing amounts of smoke and NOx generated, and the like.

FIG. 11 is a diagram showing a combustion pressure.

FIG. 12 is a diagram showing a fuel molecule.

FIG. 13 is a diagram showing the relationship between the amount of smoke generated and the EGR rate.

FIG. 14 is a diagram showing a relationship between a fuel injection amount and a mixed gas amount.

FIG. 15 is a diagram showing a first operating region I and a second operating region II.

FIG. 16 is a diagram showing an opening degree of a throttle valve and the like.

FIG. 17 is a diagram showing an air-fuel ratio in a first operating region I.

FIG. 18 is a diagram showing a map of a fuel injection amount and the like.

FIG. 19 is a diagram showing a map of a target opening degree of a throttle valve or the like.

FIG. 20 is a diagram showing an air-fuel ratio in a second operating region II.

FIG. 21 is a diagram showing a map of fuel injection amount and the like.

FIG. 22 is a diagram showing a target opening of a throttle valve or the like.

[Explanation of symbols]

6 ... Fuel injection valve 21 ... Throttle valve 24 ... Particulate filter 29 ... EGR control valve 37 ... Electric motor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02M 25/07 570 F02M 25/07 570D 570J (72) Inventor Hiroki Murata 1 Toyota-cho, Toyota-shi, Aichi Prefecture Toyota F-term within Automobile Co., Ltd. (reference) 3G062 AA01 AA05 BA04 BA06 EA10 FA08 3G093 AA01 AA05 AB01 BA20 DB23 EA02 EA05 EA06 3G301 HA02 HA11 HA13 JA24 KA11 LA01 LB11 MA11 ND01 PA11A PB03A PD15A

Claims (3)

[Claims] 1. An internal combustion engine in which the fuel supply amount supplied to the combustion chamber is controlled corresponding to the intake air amount supplied to the combustion chamber and the fuel supply amount is increased when the intake amount is large, Depending on the engine required torque to output
First combustion in which the intake air amount is less than a predetermined intake air amount and the fuel supply amount is less than the predetermined fuel supply amount, and the intake air amount is more than the predetermined intake air amount and the fuel supply amount Further comprises switching means for switching between the second combustion in which the fuel supply amount is larger than the predetermined fuel supply amount,
There is a discontinuity between the fuel supply amount immediately before the engine combustion is switched from the first combustion to the second combustion and the fuel supply amount immediately before the engine combustion is switched from the second combustion to the first combustion. In a control device for an internal combustion engine, engine combustion is the first
The control device for an internal combustion engine, wherein the fuel supply amount is made smaller than the amount required to output the engine required torque when the combustion is switched to the second combustion. 2. In an internal combustion engine, the soot generation amount gradually increases and reaches a peak as the amount of the inert gas supplied to the combustion chamber is increased. The amount of the inert gas supplied to the combustion chamber is larger than the amount of the first combustion, and the amount of the inert gas supplied to the combustion chamber is larger than the amount of the inert gas at which the amount of soot is peaked. The internal combustion engine is provided with a switching unit for switching between the second combustion in which the fuel consumption is reduced and a fuel injection amount control unit for controlling the amount of fuel supplied to the combustion chamber so that the engine required torque is output. In the engine control device, the torque output by the second combustion is larger than the torque output by the first combustion, and the fuel supply amount is changed when the engine combustion is switched from the first combustion to the second combustion. Output engine required torque The control device for an internal combustion engine is characterized in that the amount is made smaller than that necessary for the purpose. 3. An engine torque request is further provided for generating an auxiliary torque for assisting the output torque of the internal combustion engine, and when the engine combustion is switched from the first combustion to the second combustion, the engine request is generated. 3. The control device for an internal combustion engine according to claim 1, wherein the auxiliary torque generating means generates an auxiliary torque for assisting the output torque of the internal combustion engine so that the torque is output.