JP3052777B2 - In-cylinder injection internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a four-stroke internal combustion engine in which the intake, compression, expansion, and exhaust strokes are performed in one operation cycle. In particular, the present invention relates to a direct injection internal combustion engine suitable for use in fuel injection control for early activation of an exhaust gas purifying catalyst.

[0002]

2. Description of the Related Art An exhaust gas purifying catalyst is provided in an exhaust passage for purifying exhaust gas of an engine such as an internal combustion engine for an automobile. Such a catalyst is activated at a high temperature up to a certain temperature. Otherwise, the exhaust gas purification ability cannot be exhibited. For this reason, for example, Japanese Patent Application Laid-Open No. 4-295153
In the two-cycle engine, a technique is disclosed in which a part of the fuel injected into the combustion chamber is blown into the exhaust passage within a required period of time from immediately after the start of the engine to the completion of warm-up of the catalyst. Have been.

[0003] The blow-through of the fuel into the exhaust passage is realized by performing fuel injection Is during the scavenging stroke time, and the fuel that has flowed through is burned by the action of the catalyst in the exhaust passage, so that the catalyst is blown. Is rapidly increased, and the catalyst can be quickly activated. As a result, immediately after the start of the engine, the exhaust gas is purified by the catalyst, that is, the harmful components (HC, C
O, NOx) emissions can be suppressed.

[0004] In this technique, the fuel is prevented from flowing into the exhaust passage during a period other than the above-mentioned predetermined period, thereby preventing a decrease in the fuel consumption rate due to the fuel blowing. The above-mentioned predetermined period is a period during the low-load operation of the engine, and is a period until the cumulative engine speed N1 after starting the engine reaches a predetermined value (first cumulative engine speed) N11. The time TAUS for performing the fuel injection Is (fuel injection time) is always set to a constant time regardless of the engine load Q / N and the engine speed N.

[0005]

However, the above-mentioned prior art has the following problems. In other words, since the fuel injection Is is performed only during the low load operation, if the driver starts the vehicle immediately after the engine is started, the vehicle is not in the low load operation range, so the fuel injection Is is not performed.
Is not done. Therefore, in this case, the catalyst cannot be actively activated by the fuel injection Is, and the exhaust gas cannot be purified immediately after the start.

Although the fuel injection time TAUS is always set to a fixed time, the time required for activating the catalyst becomes longer depending on the operating conditions and the like.
If US is set to a certain time, it may be difficult to realize early activation of the catalyst. In other words, when the fuel injection time TAUS is set to a certain time corresponding to the low load operation of the engine, the scavenging time becomes very short at the time of high load operation, so that the fuel injection Is is performed only for the fuel injection time TAUS. It becomes difficult. Conversely, the fuel injection time TA
If the US is set to a fixed time corresponding to the high-load operation of the engine, a problem occurs in that a sufficient amount of fuel cannot be injected during the low-load operation where activation of the catalyst is required most.

The above-mentioned prior art relates to a two-stroke engine, which is an internal combustion engine (in-cylinder injection type internal combustion engine) in which fuel is injected directly into a combustion chamber. Therefore, in order to apply such a conventional technology to a four-cycle in-cylinder injection type internal combustion engine in which the intake, compression, expansion, and exhaust strokes are performed in one operation cycle, appropriate measures must be taken.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and can perform fuel injection control suitable for a four-cycle in-cylinder injection type internal combustion engine to speed up the exhaust gas purification catalyst after the engine is started. It is another object of the present invention to provide an in-cylinder injection type internal combustion engine that can be activated reliably.

[0009]

According to the present invention, there is provided an in-cylinder injection type internal combustion engine according to the present invention.
In a four-stroke internal combustion engine in which each stroke of exhaust gas is provided during one operation cycle, a fuel injection valve for injecting fuel directly into a combustion chamber and a lower portion of a vehicle in an exhaust passage of the internal combustion engine are arranged.
Main catalyst provided in the exhaust passage, and the main catalyst and the main catalyst in the exhaust passage.
Smaller than the main catalyst, located in the area between the combustion chamber
And each of the auxiliary catalysts having a temperature raising function for the main catalyst.
An exhaust gas purifying device comprising an exhaust gas purifying catalyst;
Active state determining means for determining the active state of the wastewater purification device;
The exhaust gas purifying device is in an inactive state by the active state determining means.
And a fuel injection control means for operating the fuel injection valve after the expansion stroke of the internal combustion engine to inject additional fuel into the combustion chamber.

According to a second aspect of the present invention, in the cylinder injection type internal combustion engine according to the first aspect, the additional fuel is set to be injected in the exhaust stroke. I have. According to a third aspect of the present invention, there is provided the direct injection internal combustion engine according to the first aspect of the present invention, wherein
Determining means for determining whether the exhaust gas purification device is in an active state;
Status determination unit that determines
The exhaust gas purifier is inactivated by a criterion different from the standard
From the inactive state determination unit that determines whether or not
It is characterized by being constituted .

According to a fourth aspect of the present invention, in the cylinder injection type internal combustion engine of the first aspect , the fuel injection control means determines that the catalyst is active by the active state determination means. It is characterized in that the injection of the additional fuel is terminated when it is performed. According to a fifth aspect of the present invention, there is provided the in-cylinder injection type internal combustion engine according to the fourth aspect, further comprising: catalyst temperature detecting means for detecting or estimating the temperature of the catalyst; On the basis of detection information from the detection means, when the temperature of the catalyst exceeds a set value for a set time, the catalyst is determined to be in an active state. .

According to a sixth aspect of the present invention, there is provided an in-cylinder injection type internal combustion engine according to the fourth aspect, further comprising: a cooling water temperature detecting means for measuring a cooling water temperature of the internal combustion engine; However, it is characterized in that the catalyst is determined to be inactive when the cooling water temperature is equal to or lower than a set value, based on detection information from the cooling water temperature detecting means.

According to a seventh aspect of the present invention, in the cylinder injection type internal combustion engine according to the fourth aspect of the present invention, the activation state determining means includes at least one of a catalyst temperature and a cooling water temperature of the internal combustion engine. The present invention is characterized in that an active state of the catalyst is determined by detecting or estimating one of them. Cylinder injection type internal combustion engine of the present invention of claim 8, wherein, in the structure according to claim 1, wherein the fuel injection control means, an additional fuel injection amount per working cycle,
It is characterized in that it is set in accordance with the temperature state of the catalyst or the internal combustion engine.

According to a ninth aspect of the present invention, there is provided a direct injection internal combustion engine according to any one of the first to third aspects.
The fuel injection control means is configured to set the additional fuel injection amount as the valve opening time of the fuel injection valve and set the valve opening time of the fuel injection valve as a function of the engine speed. It is characterized by. According to a tenth aspect of the present invention, there is provided the in-cylinder injection type internal combustion engine according to the present invention , wherein each of intake, compression, expansion, and exhaust lines
To a four-stroke internal combustion engine with one stroke in one working cycle
In addition, a fuel injection valve that injects fuel directly into the combustion chamber,
Operating state determining means for determining an operating state of the internal combustion engine;
The internal combustion engine based on the determination result of the operating state determination means.
Is in a predetermined operating state, the expansion stroke of the internal combustion engine and beyond.
Activate the fuel injection valve to lower the fuel and inject additional fuel into the combustion chamber.
The internal combustion engine has a plurality of cylinders, the fuel injection valve is provided for each cylinder, and at least a part of the plurality of cylinders among the plurality of cylinders is provided. Therefore, the respective operation phases are set so that the opening times of the respective exhaust ports partially overlap,
The fuel injection control means is configured to simultaneously operate the fuel injection valves provided for the cylinders in which the opening timings of the exhaust ports overlap each other.

According to an eleventh aspect of the present invention, in the cylinder injection type internal combustion engine according to the tenth aspect, the fuel injection control means is provided in a cylinder whose opening timing of the exhaust port overlaps each other. The fuel injection valves are characterized in that they are simultaneously operated while limiting the operation time so as not to protrude from the overlap period.

According to a twelfth aspect of the present invention, in the cylinder injection type internal combustion engine according to the ninth aspect , the fuel injection control is performed.
Means for controlling the opening time of the fuel injection valve by the rotation of the internal combustion engine.
The higher the speed, the shorter and the higher the temperature of the exhaust gas purification device
It is characterized in that it is configured to be set as short as possible . According to a thirteenth aspect of the present invention, there is provided a cylinder injection type internal combustion engine according to any one of the first to third aspects, wherein the internal combustion engine has an ignition means in the combustion chamber. It is characterized by being constituted as.

[0017]

In the above-described in-cylinder injection type internal combustion engine according to the first aspect of the present invention, the exhaust gas purifying device is disabled by the activation state determining means.
When it is determined that the fuel cell is in the active state, the fuel injection control means operates the fuel injection valve after the expansion stroke of the internal combustion engine to inject additional fuel into the combustion chamber. Thus, easy many additional fuel is fed to the left exhaust system unburned no longer, the exhaust gas
Promotes activation of the purification device. Especially, smaller volume than main catalyst
The auxiliary catalyst, which is arranged in a quantity and close to the combustion chamber,
Crabs are activated by raising the temperature.
The resulting heating heat promotes activation of the downstream main catalyst.
As a result, the exhaust gas purifying device is activated efficiently.

In the cylinder injection type internal combustion engine according to the present invention, since the injection of the additional fuel is performed in the exhaust stroke of the engine, most of the additional fuel is mixed with air without being burned. It will be sent to the exhaust system. In the cylinder injection type internal combustion engine according to the third aspect of the present invention, the activation state determination means may include:
Therefore, the activation state determining unit determines whether the exhaust gas purifying device has a criterion.
Determines whether the device is in the active state or not.
The state determination unit is different from the determination criteria of the active state determination unit.
Whether the exhaust gas purifier is in an inactive state according to criteria
Is determined.

Therefore, the inactive state determination unit outputs
Inject additional fuel when the purifier is determined to be inactive
To promote the activation of the exhaust gas purification device,
If the exhaust gas purifier is determined to be active by
Injection of additional fuel
It is possible to control the firing.

In the cylinder injection type internal combustion engine according to the present invention, when the activation state determination means determines that the catalyst is in an active state, the fuel injection control means determines whether or not the additional fuel has been injected. Since the injection is terminated, unnecessary injection of additional fuel is avoided, and the fuel consumption is reduced by this amount. In the in-cylinder injection internal combustion engine according to the fifth aspect of the present invention, based on the detection information from the catalyst temperature detecting means, the activation state determining means determines that the temperature of the catalyst has exceeded a set value for a set time. It is determined that the catalyst is in an active state when the time has elapsed. However, since the activity of the catalyst depends on the temperature of the catalyst, the activity of the catalyst can be reliably grasped by this determination.

In the direct injection type internal combustion engine according to the present invention, when the cooling water temperature is equal to or lower than a set value based on the detection information from the cooling water temperature detecting means, Is determined to be inactive. The temperature of the catalyst depends on the exhaust temperature and the combustion state of the engine, at least
In a situation where the temperature of the engine is low, the temperature of the catalyst is not high and can be said to be in an inactive state. Since the temperature of the cooling water corresponds to the temperature of the engine, it can be determined that the catalyst is in an inactive state if the temperature of the cooling water is equal to or lower than the set value.

In the cylinder injection type internal combustion engine according to the present invention, the activation state determination means may detect or estimate at least one of the catalyst temperature and the cooling water temperature of the internal combustion engine. Is used to determine the activation state of the catalyst. The activation state of the catalyst can be reliably grasped based on the temperature of the catalyst.

In the cylinder injection type internal combustion engine according to the present invention, the fuel injection control means sets an additional fuel injection amount per one operation cycle according to a temperature state of the catalyst or the internal combustion engine. I do. The additional fuel injection is performed to activate the catalyst. If the additional fuel injection is performed in an amount corresponding to the activation state of the catalyst, the catalyst can be activated and the fuel injection is not wasted. Since the activation state of the catalyst corresponds to the temperature state of the catalyst or the internal combustion engine, by setting the additional fuel injection amount according to the temperature state of the catalyst or the internal combustion engine, it is possible to prevent the additional fuel injection from being performed excessively. Thus, activation of the catalyst can be realized.

According to a ninth aspect of the present invention, in the cylinder injection type internal combustion engine, the fuel injection control means sets the additional fuel injection amount as an opening time of the fuel injection valve, and opens the fuel injection valve. Since the valve time is set as a function of the rotation speed of the engine, the additional fuel injection can be reliably performed in the exhaust stroke. In the direct injection internal combustion engine according to the present invention, it is determined that the internal combustion engine is in a predetermined operating state.
The fuel injection control means
The fuel injection valve is operated to inject additional fuel into the combustion chamber.
At this time, for the cylinders in which the opening timings of the exhaust ports of the plurality of cylinders overlap each other, the fuel injection valves provided for the respective cylinders are simultaneously operated, so that the control regarding the driving operation of the fuel injection valves is reduced. can do.

In the cylinder injection type internal combustion engine according to the eleventh aspect of the present invention, the fuel injection control means operates the engine such that the cylinders whose exhaust port opening timings overlap each other do not protrude from the overlap period. Is restricted, so that a situation in which the fuel injection valve operates other than when the exhaust port is opened is avoided. According to a twelfth aspect of the present invention, the fuel injection control means includes a fuel injection control device.
The opening time of the valve is shorter and shorter as the rotation speed of the internal combustion engine is higher.
The higher the temperature of the exhaust gas purifier, the shorter the setting.
The amount of additional fuel is controlled as needed.

According to the thirteenth aspect of the present invention, the in-cylinder injection type internal combustion engine of the present invention is configured such that the fuel injection valve for in-cylinder injection and the ignition means are partially disposed only in the vicinity of the ignition means. By supplying a sufficient amount of fuel and ensuring stable combustion performance, the combustion chamber as a whole can be made lean by reducing the fuel consumption by achieving a lean air-fuel ratio state. N in exhaust gas
The Ox amount increases. For this reason, in such an engine, a lean NOx catalyst may be provided as the catalyst. In such a case, the activation of the lean NOx catalyst causes harmful emissions in the exhaust gas if the operating state of the engine is lean. It becomes easy to absorb the substance into the catalyst, and in a rich operation, it becomes easy to release the harmful substance absorbed in the catalyst.

[0027]

Embodiments of the present invention will be described below with reference to the drawings. First, the first embodiment of the present invention will be described with reference to FIGS.
An in-cylinder injection type internal combustion engine as an embodiment will be described.
The configuration of the in-cylinder injection type internal combustion engine is as shown in FIG. 3, which is an internal combustion engine that performs each of the intake, compression, expansion, and exhaust strokes in one operation cycle, that is, a four-cycle engine. It is configured as an in-cylinder injection engine that is of an ignition type and directly injects fuel in a cylinder.

An intake passage 2 and an exhaust passage 3 are connected to the combustion chamber 1 so that they can communicate with each other. The communication between the intake passage 2 and the combustion chamber 1 is controlled by an intake valve 4.
The communication between the exhaust passage 3 and the combustion chamber 1 is controlled by an exhaust valve 5. The intake passage 2 is provided with an air cleaner 6 and a throttle valve 7 in order from the upstream side, and the exhaust passage 3 is provided with exhaust gas in order from the upstream side.
An exhaust gas purifying catalytic converter 9 as a purifying device and a muffler (muffler) not shown are provided. Note that a surge tank 2a is provided in the intake passage 2.

The opening of the throttle valve 7 changes in accordance with the amount of depression of an accelerator pedal (not shown). Further, although not shown, the throttle valve 7 is opened and closed by an idle speed control motor (ISC motor). Thus, the opening of the throttle valve 7 can be changed without depressing the accelerator pedal during idling.

An injector (fuel injection valve) 8 is arranged so that its opening faces the combustion chamber 1 so as to directly inject fuel toward the combustion chamber 1 in the cylinder. Naturally, the injectors 8 are provided for each cylinder. For example, if the engine of this embodiment is an in-line four-cylinder engine, four injectors 8 are provided.

With this configuration, the air sucked through the air cleaner 6 according to the opening of the throttle valve 7 is sucked into the combustion chamber 1 by opening the intake valve 4, and the air sucked inside the combustion chamber 1 And the fuel directly injected from the injector 8 are mixed, and the ignition plug 35
Is ignited at an appropriate timing to cause combustion and generate an engine torque. Then, the air-fuel mixture is discharged to the exhaust passage 3 as exhaust gas. CO, H
After purifying the three harmful components of C and NOx, the muffler silences and releases them to the atmosphere.

In particular, as will be described later, the present engine is an engine capable of performing economizing operation while keeping the air-fuel ratio lean. During lean operation, the amount of NOx in the exhaust gas increases, so that the catalyst (exhaust gas purifying device) 9 is exhaust gas purification
Main catalyst 107, which is a catalyst for exhaust gas, and a catalyst for purifying exhaust gas.
The main catalyst 107 is located under the floor of the vehicle.
The sub-catalyst 108 is installed under the bed.
The underfloor catalyst 107 before the lower catalyst 107 and the combustion chamber 1
The front catalyst is disposed in the exhaust passage 3 between the front catalysts. Supplement
The co-catalyst (front catalyst) 108 is a main catalyst (under-floor catalyst)
Combustion with a capacity smaller than 107 and upstream of the exhaust passage 3
At a position close to the chamber 1, that is, a position close to the exhaust port 3A
It is arranged. Of these, the main catalyst 107
Thus, a lean NOx catalyst and a three-way catalyst are combined. Then, purification of exhaust gas, that is, exhaust gas
Of emissions of harmful components (HC, CO, NOx) in wastewater
Is mainly performed by the underfloor catalyst 107 and the front catalyst 1
08 is used for early activation of the underfloor catalyst 107
It is supposed to be. By the way, the present engine will be further described. This engine is configured such that the intake air flowing into the combustion chamber 1 from the intake passage 2 forms a vertical vortex (reverse tumble flow). Forms such a vertical vortex, so that, for example, the ignition plug 3 arranged at the center of the top of the combustion chamber 1 is used while utilizing the vertical vortex.
The fuel is collected only in the vicinity of 5 and an extremely lean air-fuel ratio state can be achieved in a portion separated from the spark plug 35. Stable combustion is realized by setting the stoichiometric air-fuel ratio only in the vicinity of the spark plug 35. Meanwhile, fuel consumption can be suppressed.

In particular, since this engine is an in-cylinder injection engine, there is no restriction on the timing of fuel injection, and fuel injection can be performed at a timing most suitable for realizing the above-described uneven distribution of fuel. It is known that the optimal fuel injection timing in this case is the latter stage of the compression stroke in which the air flow is weak. In order to obtain a high output from the engine, the combustion may be performed by bringing the entire combustion chamber 1 into a stoichiometric air-fuel mixture state. In this case, the fuel is sufficiently atomized and vaporized. By performing fuel injection at such timings, high output can be obtained efficiently. It is known that the optimum fuel injection timing in this case is set so as to end the fuel injection at the beginning or the first half of the intake stroke so as to promote the atomization and vaporization of the fuel by utilizing the intake flow. ing.

Incidentally, various sensors are provided to control the engine. First, on the intake passage 2 side, an air flow sensor 11, which detects an intake air amount from Karman vortex information, an intake air temperature sensor 12, which detects an intake air temperature, and an atmospheric pressure sensor 13, which detects an atmospheric pressure, are provided at the portion where the air cleaner is provided. The throttle valve is provided with a potentiometer type throttle sensor 14 for detecting the opening of the throttle valve 7, an idle switch 15 for detecting an idling state, and the like.

On the exhaust passage 3 side, an oxygen concentration sensor 17 (hereinafter simply referred to as an O ₂ sensor 17) for detecting an oxygen concentration (O ₂ concentration) in the exhaust gas is provided upstream of the catalyst 9.
Is provided. Further, as other sensors, a water temperature sensor (cooling water temperature detecting means) 19 for detecting an engine cooling water temperature and a crank angle sensor 21 for detecting a crank angle as shown in FIG. (It also serves as a rotation speed sensor to detect)
And TDC for detecting top dead center of the first cylinder (reference cylinder)
Sensors (cylinder discrimination sensors) 22 are provided in the distributors, respectively.

The detection signals from these sensors are input to an electronic control unit (ECU) 23. The ECU 23 is provided with a voltage signal from an accelerator position sensor 24 that detects the amount of depression of an accelerator pedal and a voltage signal from a battery sensor 25 that detects the voltage of a battery, and a cranking switch [or an ignition switch (key switch)] that detects a start time. The signal from the terminal 20 is also input.

The hardware configuration of the ECU 23 is as shown in FIG. 2. The ECU 23 has a CPU 27 as its main part.
Intake air temperature sensor 12, atmospheric pressure sensor 13, a throttle sensor 14, O ₂ sensor 17, water temperature sensor 19, via a detection signal input interface 28 and an analog / digital converter 30 from an accelerator position sensor 24 and a battery sensor 25 inputs At the same time, detection signals from the airflow sensor 11, the crank angle sensor 21, the TDC sensor 22, the idle switch 15, the cranking switch 20, the ignition switch, and the like are input via the input interface 29.

Further, the CPU 27 has a ROM for storing program data and fixed value data via a bus line.
31, a RAM 32 that is updated and rewritten sequentially, a free running counter 48, and a battery backup RAM (not shown) that is backed up while the battery is connected by holding the stored contents while the battery is connected. It gives and receives.

The data in the RAM 32 disappears and is reset when the ignition switch is turned off. The fuel injection control signal based on the calculation result by the CPU 27 is transmitted to the solenoid (injector solenoid) 8a of the injector 8 via the (here, four) injection driver (fuel injection valve driving means) 34 for each cylinder.
(Accurately, a transistor 8b for the injector solenoid 8a as shown in FIG. 4).

Further, when this ECU 23 is shown in detail,
As shown in FIG. That is, as shown in FIG. 4, the ECU 23 includes a CPU 27, a ROM 31, and a RAM 3.
It comprises a microcomputer having two and a plurality of ports 46, and has a cylinder discriminating external register (flip-flop) 47, a free-running counter 48, registers 49 to 52, comparators 53 to 56 and RS flip-flops 57 to 57. 60 and the like.

The output signal of the airflow sensor 11 is input to an interrupt terminal INT2 of the CPU 27, and the crank phase signal from the crank angle sensor 21 is shaped into a rectangular wave by a waveform shaping circuit as an input interface.
7 is input to an interrupt terminal INT1. Further, the cylinder discrimination signal from the cylinder discrimination sensor 22 is shaped into a rectangular wave by a waveform shaping circuit as an input interface,
, The intake air temperature sensor 13, the atmospheric pressure sensor 13, O
The signals from the _two sensors 17, the water temperature sensor 19, etc. are adjusted to an appropriate level by a level adjustment circuit as an input interface, are converted from analog to digital by the analog / digital converter 30, and are input to the port 46. ing.

The injector 8 is opened and closed by controlling the power supply from a DC power supply (battery) to a valve body opening / closing injector solenoid 8a by a switching transistor 8b. Focusing on fuel injection control (air-fuel ratio control), a fuel injection control signal calculated by the CPU 27 is output via the driver 34,
For example, four injectors 8 are sequentially driven.

In view of the characteristics of the direct injection engine described above, this engine has the following fuel injection modes.
A late injection mode in which fuel is injected in the second half of the compression stroke to realize operation by lean combustion (lean operation), and an early or early period of the intake stroke to realize operation by stoichiometric air-fuel ratio combustion (stoichiometric air-fuel ratio operation) Is provided with an earlier injection mode for ending fuel injection. In the stoichiometric air-fuel ratio operation, if the amount of fuel to be supplied is large, the fuel injection may be started from the latter or final stage of the exhaust stroke and may be ended in the early or early stage of the intake stroke.

In particular, in the present internal combustion engine, the catalyst 9 is activated (hereinafter, the activation and inactivation of the catalyst 9 are described) in addition to the fuel injection for the normal combustion in the combustion chamber as described above.
Means mainly the activity and inactivity of the main catalyst 107.
For this purpose, additional fuel is injected. In this additional fuel injection, by supplying an air-fuel mixture containing an unburned fuel component to the catalyst 9, the unburned fuel component in the air-fuel mixture is burned by the catalyst 9, and the temperature of the catalyst 9 is raised to activate the fuel. What you want to do.

For this reason, in the additional fuel injection, when the catalyst 9 is not activated (inactive), as shown in FIG. 5, the exhaust stroke of each cylinder (specifically, from the end of the expansion stroke to the exhaust stroke) ), And is not performed when the catalyst 9 is activated. For such fuel injection control (injector drive control), the CPU 27 is provided with a fuel injection control means 101 for selecting an injection mode and setting a fuel injection amount.

As shown in FIG. 1, the fuel injection control means 101 performs a function (additional fuel injection control means) 102 for performing additional fuel injection when the catalyst 9 is inactive, and performs fuel injection control during normal operation. Function (normal fuel injection control means)
103 and additional fuel injection control means 102
Are characteristic components of the direct injection internal combustion engine for exhaust gas purification.

Since the additional fuel injection control means 102 performs control based on the operating state of the internal combustion engine, in particular, the active state of the catalyst 9, the CPU 27 has an active state determining means (operating state) for determining the active state of the catalyst 9. (State determining means) 104 is provided. The activation state determination means 104 includes detection information from a catalyst temperature sensor (catalyst temperature detection means) 105 for detecting the temperature of the catalyst 9 and a water temperature sensor (cooling water temperature detection means) 19 for detecting a cooling water temperature of the engine; Based on the timer count information from
Is determined.

In particular, the active state determining means 104 includes an active state determining unit 10 for determining whether or not the catalyst is in an active state.
4A, and an inactive state determination unit 104B that determines whether the catalyst is in an inactive state. Criteria for determination by active state determining section 104A and inactive state determining section 10
4B is provided separately from the criterion.

The inactive state judging section 104B is for judging whether or not the activation of the catalyst 9 by the additional fuel injection is necessary, and the engine cooling water temperature Tw detected by the water temperature sensor 19 becomes a predetermined temperature T _0. If below, it is determined that the catalyst 9 is in the inactive state. The activation state determination unit 104A is for determining whether or not the catalyst 9 has been sufficiently activated when additional fuel injection is performed, and the temperature Temp.c / C of the catalyst 9 detected by the catalyst temperature sensor 105. c is the predetermined temperature T ₁
State (or a state that has exceeded the predetermined time t ₀ )
Determines the duration tc / c of Once becomes ₀ or greater than the predetermined time t, the catalyst 9 is in an active state.

The additional fuel injection control means 102 has a function (start / end determination unit) 102A for instructing start and end of the additional fuel injection, and an additional fuel injection time in each cycle.
(I.e., a function (injection time setting unit) 102B ) for setting (ie, the valve opening time of the injector 8 ). In the start / end determining unit 102A, the inactive state determining unit 10
When it is determined in 4B that the catalyst 9 is in the inactive state, it is determined to start the additional fuel injection, and the active state determination unit 10
When it is determined in 4A that the catalyst 9 is in the active state, it is determined to terminate the additional fuel injection.

Incidentally, the activation state of the catalyst 9 depends on the catalyst temperature T.
Since the determination can be made based on emp c / c, the inactive state determination by the inactive state determination unit 104B to determine whether to start the additional fuel injection is performed in the same manner as the determination of the active state. It may be performed based on / c. The cooling water temperature Tw is equal to the catalyst temperature Temp c /
c, the inactive state determination unit 104B determines the inactive state and the active state determination unit 104A
The cooling water temperature Tw may also be used for the determination of the activation state by the above. That is, the cooling water temperature Tw increases because
This is because the combustion is sufficiently performed after the engine is started. If the combustion is sufficiently performed, the catalyst temperature Temp c / c is sufficiently increased by the high-temperature exhaust gas. Conversely, the cooling water temperature T
If w is low, it means that combustion has not yet been sufficiently performed after the engine is started, and the catalyst temperature Tem due to the exhaust gas is low.
This is because it can be determined that the increase in pc / c is not yet sufficient. Therefore, additional fuel injection control means 102
In the predetermined value T temperature Temp.c / c is underfloor catalyst 107 ₀₀ or more
Below (here, the equivalent condition
Retirement water temperature Tw is the predetermined temperature T ₀ or less), then the catalyst 9 inactivation
To perform additional fuel injection during the exhaust stroke
It has become.

In this embodiment, the determination of the inactive state is based on the cooling water temperature Tw. This is because the detection range of the catalyst temperature sensor 105 is near the active area of the catalyst 9, This is because it is more appropriate to use the cooling water temperature Tw to determine the temperature region lower than the vicinity of the active region. Of course, if the detection range of the catalyst temperature sensor 105 is set to include a temperature range lower than the vicinity of the active region of the catalyst 9, the determination of the inactive state is also based on the catalyst temperature Temp c / c as described above. Can be.

In addition, the determination of the active state, which is a condition for terminating the additional fuel injection, is such that the state in which the catalyst temperature Temp c / c has exceeded the predetermined temperature T ₁ continues for a predetermined time t ₀ or more. The reason why the determination is made using the duration t ₀ is that the additional fuel injection is to be terminated when the catalyst 9 is surely activated. After the start determination of the additional fuel injection, the additional fuel injection is continued until the end determination is made. However, the injection of the additional fuel is performed in the exhaust stroke of each cylinder (see FIG. 5) as described above. The injection time t _ex of the additional fuel at this time is set by the injection time setting unit 102B.
In this injection time setting section 102B, the temperature Temp.
It is set in accordance with c / c and the engine speed (engine speed) Ne. For example, as shown in FIG. 6, as the catalyst temperature Temp.c / c is higher, the injection time t _ex is shorter, and as the engine speed Ne is higher, the injection time t _ex is shorter.
_ex is set to be short.

The reason for this is that the lower the catalyst temperature Temp.c / c, the more the activation of the catalyst 9 is required, so that more additional fuel is injected to promote the activation of the catalyst 9, and conversely, the lower the catalyst temperature Temp.c / c. c /
Since the activation of the catalyst 9 becomes unnecessary as c becomes higher,
It is intended to reduce the injection of additional fuel. In addition, the higher the engine speed Ne, the shorter the time required for one operation cycle. Therefore, the exhaust stroke in one operation cycle is shortened, and the time during which fuel injection can be performed in the exhaust stroke is also shortened. Therefore, the engine speed Ne
The higher the value, the shorter the injection time of the additional fuel.

As shown in FIG. 5, such additional fuel injection is performed separately from normal fuel injection. By the way, the fuel injection control in the normal fuel injection control means 103 will be described. In the normal operation control means 103, the injection mode is set based on the engine speed (rotation speed) Ne and the accelerator pedal depression amount θ _ACC based on the engine target. The output torque T is set, and either the first injection mode or the second injection mode is selectively set according to the engine speed Ne and the target output torque T. For example, in a region where the engine speed Ne is low and the target torque T is low, the late injection mode is set, and the engine speed Ne and the target torque T are set.
If any of the above is not low, the former injection mode is set.

The fuel injection amount is set as a fuel injection time (a driving time of the injector, which is called an injector driving pulse width in actual control) _tAU. In the case of
Engine load (amount of intake air per stroke) Q / Ne
And air-fuel ratio (A / F, hereinafter referred to as AF) as a target based on such, first, the basic drive time t _p is calculated by the following equation.

T _p = (Q / Ne) × (1 / AF) × (α
_AIR / α _FUEL ) × (1 / G _INJ ) The engine load Q / Ne is the amount of intake air per stroke, and the amount of intake air Q detected by the air flow sensor 11 is used as the engine speed sensor (crank angle sensor). ) 2
It is obtained by dividing by the engine speed Ne detected at 1. Α _AIR is the air density, α _FUEL is the fuel density, and G _INJ is the injector gain.

Then, the fuel injection time t _AU is calculated by the following equation. t _AU = t _p × K + t _D Here, K is various fuel correction coefficients. The fuel correction coefficient K is the engine cooling water temperature detected by the water temperature sensor 19, the intake air temperature detected by the intake air temperature sensor 12, The setting is made according to the atmospheric pressure detected by the atmospheric pressure sensor 13 and the like. Further, t _D is the injector dead time (dead time).

The exhaust gas purifying apparatus for an engine according to the first embodiment of the present invention is configured as described above.
For example, as shown in FIG. 7, normal fuel injection control and determination of additional fuel injection (exhaust stroke fuel injection) are performed. FIG.
The routine shown in (1) is executed at every fixed crank angle, but first, for normal fuel injection, steps A10 to A10 are executed.
The process of A30 is performed. That is, in step A10, the engine load Q / N is calculated based on the intake air amount Q and the engine speed Ne detected by the air flow sensor 11 and the speed sensor 21.
e (that is, the amount of intake air per stroke) is calculated. Then, in step A20, as shown in the above equation, based on the engine load Q / Ne, calculating a basic drive time t _p. Further, in step A30, and calculates the fuel injection time t _AU performs a multiplication of various fuel correction coefficient K to the basic drive time t _p.

Then, in step A40, the water temperature sensor 1
The engine coolant temperature Tw detected at step 9 is equal to the predetermined temperature T.₀
It is determined whether or not: Here, the cooling water temperature Tw is a predetermined temperature.
Degree T ₀If below, in step A50, the catalyst activation flag
It is determined whether F is 1 or not. This catalyst activation flag F is
1 if additional fuel injection should be performed to activate the medium
Becomes 0 when there is no need to perform additional fuel injection.
It is set to 1 at the time of initial setting.

Normally, since the flag F is 1, step A
The process proceeds from step 50 to step A60, in which an exhaust stroke fuel injection control described later (ie, additional fuel injection control) is performed. If the cooling water temperature Tw is not lower than the predetermined temperature T ₀ , the exhaust stroke fuel injection control (additional fuel injection control) is not performed because the catalyst 9 is not in an inactive state. The exhaust stroke fuel injection control (additional fuel injection control) is performed as shown in FIG. That is, first, in step B10, the injection time t _ex of the additional fuel is set. This additional fuel injection time t _ex is
For example, as shown in FIG. 6, the temperature is set according to the temperature Temp.c / c of the catalyst 9 and the engine speed Ne. Then, the process proceeds to step B20, the catalyst temperature detected by the catalyst temperature sensor 105 Temp.c / c is determined whether the threshold value above T _1, the catalyst temperature Temp.c / c is the threshold value above T ₁ If not,
In step B30, the timer is reset, and in step B4
At 0, an exhaust stroke fuel injection (additional fuel injection) is executed.
As shown in FIG. 5, this additional fuel injection is performed during the exhaust stroke by the additional fuel injection time t set in step B10.
Only _{ex is} executed.

Then, by the additional fuel injection in the exhaust stroke, an air-fuel mixture containing an unburned fuel component is supplied to the catalyst 9 and burned by the catalyst 9. Thereby, the catalyst 9
Gradually rises, and the catalyst temperature Temp.c / c becomes the threshold T ₁
Then, the process proceeds from step B20 to step B50 to start timer counting. Then step B
60 determines whether less than a value tc / c is the threshold t ₀ of the timer count at.

Immediately after the start of the timer count, since the timer count value tc / c is less than the threshold value t ₀ , the process proceeds from step B60 to step B40 to execute the exhaust stroke fuel injection (additional fuel injection). On the other hand, the timer count advances,
When the timer count value tc / c is the threshold value t ₀ or more, the process proceeds from step B60 to step B70, a flag F 0
To complete the exhaust stroke fuel injection (additional fuel injection).

As described above, when the flag F is set to 0 in step B70, until the flag F is set to 1 in step A80 in FIG.
Until the temperature once exceeds the predetermined temperature T ₀ , step A in FIG.
By the determination at 50, the exhaust stroke fuel injection (additional fuel injection) at step A60 is not performed. Of course, the cooling water temperature T
If w exceeds the predetermined temperature T ₀ , the exhaust stroke fuel injection (additional fuel injection) is not performed according to the determination in step A40.

[0065] Thus, for example when the temperature of the engine is low at startup, the temperature Temp.c / c catalyst 9 to thresholds T ₁ or more state continues for a predetermined time t ₀ or more, the exhaust stroke fuel The injection (additional fuel injection) is executed, and the catalyst 9
, The catalyst 9 is quickly and reliably heated and activated after the engine is started. Therefore, immediately after the start of the engine, purification of the exhaust gas by the catalyst 9, that is, harmful components (HC, CO, N
Ox) emission can be suppressed.

Further, since the temperature of the catalyst 9 can be increased without adding a hardware configuration such as a heater for heating the catalyst to the apparatus, the activation of the catalyst 9 can be realized while suppressing an increase in cost. Further, since the additional fuel injection is performed in the exhaust stroke, the additional fuel is supplied almost directly to the catalyst 9 together with the exhaust gas in an unburned state without being provided for combustion in the combustion chamber. The activity of the catalyst 9 can be promoted by the additional fuel. In the exhaust stroke, high-temperature exhaust gas after burning in the combustion chamber 1 flows out. Therefore, the additional fuel supplied to the catalyst 9 together with the high-temperature exhaust gas is quickly burned by the catalyst 9 to generate heat. The activity of the catalyst 9 can be more positively promoted.

In addition, the injection during the exhaust stroke is particularly likely to occur only near the end of the exhaust stroke, so that adverse effects on combustion in a normal combustion chamber hardly occur. However, control of normal fuel injection (that is, fuel injection from the end of the exhaust stroke to the intake stroke) is the same regardless of whether additional fuel injection is performed or not. Can do it.

As shown in FIG. 6, the injection amount of the additional fuel injection increases as the catalyst temperature Temp.c / c increases, as the injection time t increases.
_ex is shortened, and the injection time t _ex is set to be shorter as the engine speed Ne is higher, so that additional fuel injection as needed is realized, and there is no waste of additional fuel injection, and Activation can be performed promptly. Further, by increasing the injection time of the additional fuel as the engine speed Ne increases, the additional fuel injection can be performed only during the exhaust stroke in each combustion cycle, and the additional fuel injection can be performed within the exhaust stroke as described above. The advantage obtained by performing the above can be obtained reliably.

Further, when the temperature of the catalyst 9 is reliably raised to the predetermined temperature T ₁ , the additional fuel injection is terminated.
The increase in fuel consumption due to the temperature rise is also suppressed. Moreover,
When the temperature Temp.c / c of the underfloor catalyst 107 is low and inactive,
Since additional fuel injection is performed during the exhaust stroke,
The temperature of the front catalyst 108 near the firing chamber 1 rises and is activated,
Due to the heat-up heat of the front catalyst 108, it is installed downstream.
The heated underfloor catalyst 107 is heated and activated. At this time,
Since the front catalyst 108 is close to the combustion chamber 1, it is injected during the exhaust stroke.
The additional fuel to be injected is discharged at a high temperature after combustion in the combustion chamber 1.
The gas 108 is supplied to the catalyst 108 together with the gas. For this reason,
Some of the added fuel is burned before entering the front catalyst 108.
Combustion reaction with extremely high temperature exhaust gas
Unburned gas that is likely to flow into the front catalyst 108
The unburned gas is immediately burned by the front catalyst 108.
It generates heat due to the burning reaction. Thereby, the front catalyst 108
Will rise very quickly. In particular, additional fuel
Even if the injection amount of the fuel is small, the front catalyst 108
Temperature rises quickly enough, and enough
Heat can be supplied, and the temperature of the underfloor catalyst 107 also rises quickly,
Sexualize. This allows for less additional fuel injection
As a result, the temperature of the underfloor catalyst 107 can be raised and activated,
Advantage of saving fuel required for activating medium 107
There is. In addition, the front catalyst 108 is an underfloor catalyst 107.
Small enough to supply heat to the
In a narrow place near the exhaust port 3A in the exhaust passage 3
Can also be installed sufficiently. On the other hand, the underfloor catalyst 107
Must have sufficient capacity to purify exhaust gas.
However, it is relatively difficult to secure space under the vehicle floor for this purpose.
Therefore, the underfloor catalyst 107 having a sufficient capacity is relatively self-contained.
It can be installed in a flexible layout. like this
Then, in the engine of the present embodiment, a sufficient capacity of the catalyst (below the bed)
While installing the catalyst 107), this catalyst is slightly
Rapid temperature rise and activation by additional fuel injection
And actively promote exhaust gas purification.
Kiruyo Uninaru. By the way, FIG.
Showing the characteristics of the amount of HC emitted and the temperature of the catalyst
And the vehicle ran at a vehicle speed as shown in (C).
In this case, the amount of HC emission changes as shown in FIG.
The catalyst temperature [here, the substrate on which the catalyst is installed (catalyst bed)
Temperature) changes as shown in FIG. Sand
That is, as shown in (B), the temperature of the front catalyst quickly rises.
The underfloor catalyst rises to follow the temperature of this front catalyst.
And heat the front and underfloor catalysts simultaneously.
In the case where the floor is touched, as shown in FIG.
Exhaust gas purification performance is better than when only a medium is provided.
You can see that it goes up. The lean NOx catalyst provided in the catalyst 9 can also be expected to have the following effects in addition to the above. That is, the lean NOx catalyst has a NOx absorbent that absorbs NOx when the air-fuel ratio of the inflowing exhaust gas is lean, and releases the absorbed NOx when the oxygen concentration in the inflowing exhaust gas decreases. If the amount increases, rich operation (operation with rich air-fuel ratio) during lean operation (operation with lean air-fuel ratio)
To release the absorbed NOx. As described above, when the operation mode is switched to the rich operation mode during the lean operation, the driver may feel uncomfortable.

On the other hand, in the present internal combustion engine, additional fuel injection is performed during the exhaust stroke so as not to affect fuel injection for normal combustion. Can be released, and the lean NOx catalyst can be regenerated (release of NOx) without giving the driver an uncomfortable feeling. Also,
Since the NOx absorbent contains sulfur contained in fuel and lubricating oil of the engine, the exhaust gas also contains sulfur such as sulfate, and this sulfur is also absorbed by the NOx absorbent together with NOx. Then, the absorbed sulfur content is NOx
Even if the air-fuel ratio of the exhaust gas flowing into the absorbent is simply made rich, it is not released from the NOx absorbent, but is decomposed by heating the NOx absorbent and released from the NOx absorbent.

However, at this stage, the sulfur content is in a harmful state, for example, sulfur oxide SO ₃ .
I want to release it after making it harmless. Such harmful sulfur components (for example, sulfur oxide SO ₃ ) are immediately oxidized by unburned HC and CO in the exhaust gas and become harmless, so that the rich operation or the stoichiometric operation is performed with the NOx absorbent heated. When the operation is performed, the sulfur absorbed by the NOx absorbent becomes harmless and is released from the NOx absorbent.

In this internal combustion engine, by performing additional fuel injection during the exhaust stroke, the temperature of the lean NOx catalyst is controlled to a temperature range in which this sulfur is decomposed, and further, unburned components are given to the exhaust gas. The lean NOx catalyst can be regenerated (sulfur release) by controlling the required additional fuel injection. When the activation of the catalyst 9 is determined based on the catalyst temperature Tempc / c, the fuel injection control is performed as shown in FIG.

The difference from the control of the embodiment is that step A42
, And the step A42, the catalyst temperature Temp.c / c detected by the catalyst temperature sensor 105 determines whether a predetermined temperature T ₀₀ less. If the catalyst temperature Temp.c / c is the predetermined temperature T ₀₀ or less, under the conditions of the flag F = 1, performs additional fuel injection in the exhaust stroke. If the catalyst temperature Temp.c / c is not less than the predetermined temperature T _00, it does not perform the additional fuel injection in the exhaust stroke.

The activation of the catalyst 9 is determined by determining the catalyst temperature T.
When performing based on emp c / c, the fuel injection control
This is performed as shown in FIG. The difference from the control of the first embodiment (FIG. 7) is that the inactivation of the catalyst 9 is determined (step A).
42), and in step A42, the catalyst temperature sensor 1
Detected catalyst temperature Temp.c / c 05 determines whether the predetermined temperature T ₀₀ less.

[0075] If the catalyst temperature Temp.c / c is the predetermined temperature T ₀₀ less, performs additional fuel injection control routine (FIG. 8) in the exhaust stroke under the condition of the flag F = 1. If the catalyst temperature Temp.c / c is not less than the predetermined temperature T _00, it does not perform the additional fuel injection routine in the exhaust stroke. Note that this determination threshold T ₀₀ is
Set to a value lower than the activation determination thresholds T ₁ used in step B20 in FIG. 8.

When both the determination of the inactive state by the inactive state determining unit 104B and the determination of the active state by the active state determining unit 104A are performed based on the cooling water temperature Tw, the additional fuel injection control is performed as shown in FIG. This is performed as shown in FIG. Difference from the control (FIG. 8) of the first embodiment is the determination of the activation of the catalyst 9 (step B22), In step B22, the predetermined coolant temperature Tw of the detected engine coolant temperature sensor 19 is a temperature T ₁₁ It is determined whether or not this is the case.

[0077] If the cooling water temperature Tw is not the predetermined temperature T ₁₁ or more, subjected to additional fuel injection in the exhaust stroke. Cooling water temperature Tw
There if the predetermined temperature T ₁₁ or more, in terms of timer count tc / c has finished counting the time required to end the additional fuel injection in the exhaust stroke. Next, a second embodiment will be described. An internal combustion engine (engine) according to this embodiment has
It has a cylinder and is configured as, for example, a V-type 12-cylinder engine. Of course, this engine is also a spark ignition type four-cycle engine, and is configured as a direct injection engine that directly injects fuel in a cylinder.

In the engine of this embodiment as well, the fuel injection control means 101 is provided with an additional fuel injection control means 102 and a normal fuel injection control means 103. In the additional fuel injection control means 102, the determination is made by the active state determination means 104. The additional fuel injection is controlled based on the activated state of the catalyst 9. This additional fuel injection is performed in the same manner as in the first embodiment.
Although the process is performed in the exhaust stroke of each cylinder, in an engine having a large number of cylinders, the exhaust stroke may overlap (overlap) between a plurality of cylinders. For example, in the case of a 12-cylinder engine as in the present embodiment, as shown in FIG. 11, the exhaust strokes of three cylinders simultaneously overlap.

In the additional fuel injection control means 102 of this embodiment, the 12 cylinders are divided into four groups each including three cylinders whose exhaust strokes overlap each other, and the additional fuel injection in the exhaust stroke is performed for each group. Is to be performed. In this example, as shown in FIG.
The first cylinder (# 1), the second cylinder (# 2), and the ninth cylinder (#
9) and the 10th cylinder (# 1)
0), a fifth cylinder (# 5) and a sixth cylinder (# 6) (second group), an eleventh cylinder (# 11), a twelfth cylinder (# 12), and a third cylinder (# 3). (Third group), the fourth cylinder (# 4), the seventh cylinder (# 7) and the eighth cylinder
The engine is divided into four groups, that is, a group (fourth group) with the cylinder (# 8), and the cylinders of each group simultaneously perform additional fuel injection in the exhaust stroke.

By the way, the plurality of cylinders in each group are
As shown in FIG. 11, there is a period during which the exhaust stroke is performed at the same time, but this period is naturally shorter than the exhaust stroke of a single cylinder, and in the case of 12 cylinders as in this embodiment,
The period during which the exhaust stroke is common to each cylinder in the group is approximately one third of the period during the single cylinder. Therefore,
The injection time setting unit 102B is configured to limit the injection time t _ex so that each cylinder in the group performs additional fuel injection during the exhaust stroke. That is, the injection time setting unit 102B sets an upper limit value t _ex (Ne) _MAX of the injection time t _ex according to the engine speed Ne, for example, as shown in FIG. This upper limit value t
_ex (Ne) _MAX is set to the amount of displacement of the crank angle defined by the broken line indicating the region of the group injection in FIG. 11, and the injection time t _ex is limited by this upper limit value t _ex (Ne) _MAX . Thus, additional fuel injection is performed when each of the cylinders in the group is in the exhaust stroke.

The injection time t _ex is set according to the temperature Temp.c / c of the catalyst 9 and the engine speed Ne, as in the first embodiment, within such restrictions. The other parts are configured in the same manner as in the first embodiment. Since the exhaust gas purifying apparatus for an engine according to the second embodiment of the present invention is configured as described above, each of the cylinders is a group of a plurality (three in this case) of cylinder units which simultaneously perform an exhaust stroke. In any case, additional fuel injection is performed simultaneously while limiting during the exhaust stroke. Therefore, the same operation and effect as those of the first embodiment can be obtained, and the load on the CPU for controlling the fuel injection valve can be reduced. Also, there is an advantage that the cost for the CPU can be reduced.

[0082]

[0083]

[0084]

[0085]

[0086]

[0087]

[0088]

[0089] The contact, in the above embodiments, although the injection of additional fuel for the catalyst activation is performed in the exhaust stroke, the additional fuel injection is not necessarily limited to the exhaust stroke, the expansion stroke The advantage that the catalyst can be activated at an early stage can be obtained even if the process is performed in another stroke such as the intake stroke and the intake stroke.

[0090]

As described above in detail, according to the in-cylinder injection type internal combustion engine of the first aspect of the present invention, the four-stroke internal combustion engine having the intake, compression, expansion, and exhaust strokes in one operation cycle. A fuel injection valve for injecting fuel directly into a combustion chamber of an engine, and a vehicle underfloor portion of an exhaust passage of the internal combustion engine;
And the main catalyst in the exhaust passage
And a smaller portion than the main catalyst disposed in a portion between the main catalyst and the combustion chamber.
Auxiliary catalyst having a capacity and a temperature raising function for the main catalyst
An exhaust gas purifying apparatus comprising: each exhaust gas purifying catalyst;
Active state determining means for determining the active state of the exhaust gas purification device
And the exhaust gas purification device is inactivated by the activation state determination means.
Fuel injection control means for operating the fuel injection valve and injecting additional fuel into the combustion chamber after the expansion stroke of the internal combustion engine when it is determined that the fuel is in a neutral state. and it can be fed to the exhaust system, exhaust
The fuel can be supplied to the exhaust gas purification device installed in the system . The fuel supplied to the exhaust gas purifier is
The fuel burns in the process before it is supplied to the gasifier or when it is supplied to the exhaust gas purifier , and the heat of combustion burns the exhaust gas.
The effect of promoting the activity of the gasification device and the effect of adjusting the exhaust gas purification device to a required temperature state can be obtained. In particular, this
The exhaust gas purification device has a main catalyst and an auxiliary catalyst.
Auxiliary located at a smaller capacity and closer to the combustion chamber
The catalyst is quickly heated and activated to activate the auxiliary catalyst.
Activation of the downstream main catalyst by heat
As a result, the exhaust gas purifying device is efficiently activated.

According to the in-cylinder injection type internal combustion engine of the present invention, the additional fuel is set to be injected in the exhaust stroke. The mixture containing the unburned fuel component can be efficiently supplied to the exhaust system by the additional fuel, and the fuel can be supplied to the exhaust gas purifying device provided in the exhaust system. Then, the required fuel can be supplied to the exhaust gas purification device with a small amount of additional fuel, and the exhaust gas purification device has an effect of efficiently promoting the activity of the catalyst by the heat of combustion.

According to a third aspect of the present invention, in the cylinder injection type internal combustion engine of the first aspect , the activated state is provided.
Determining means for determining whether the exhaust gas purification device is in an active state;
Status determination unit that determines
The exhaust gas purifier is inactivated by a criterion different from the standard
And an inactive state determination unit that determines whether the device is in the active state.
Each judgment can be made according to the appropriate judgment criteria
You.

[0093] According to a cylinder injection type internal combustion engine of the present invention described in claim 4, in the configuration of claim 1, wherein the fuel injection control means, that said catalyzed by active state determining means is active Is determined, the additional fuel injection is terminated, so that the additional fuel injection is efficiently used to raise the temperature of the catalyst, and unnecessary fuel consumption due to the additional fuel injection is avoided.

According to a fifth aspect of the present invention, there is provided the in-cylinder injection type internal combustion engine according to the fourth aspect, further comprising a catalyst temperature detecting means for detecting or estimating the temperature of the catalyst. Is configured to determine that the catalyst is in an active state when a state in which the temperature of the catalyst exceeds a set value for a set time has elapsed based on detection information from the catalyst temperature detecting means. As a result, the activation state of the catalyst can be reliably determined, and the exhaust gas can be more reliably purified by the catalyst.

According to a sixth aspect of the present invention, there is provided the in-cylinder injection type internal combustion engine according to the fourth aspect, further comprising a cooling water temperature detecting means for measuring a cooling water temperature of the internal combustion engine.
The activation state determination means is configured to determine that the catalyst is in an inactive state when the cooling water temperature is equal to or lower than a set value, based on detection information from the cooling water temperature detection means, Immediately after starting, the catalyst can be reliably activated, and the exhaust gas can be more reliably purified by the catalyst.

According to the seventh aspect of the present invention, in the configuration of the fourth aspect, the activation state determining means determines whether the temperature of the catalyst or the temperature of the cooling water of the internal combustion engine is high. Is configured to determine the activation state of the catalyst by detecting or estimating at least any of the above, by appropriately using the means for detecting the temperature of the catalyst and the temperature of the cooling water, It is possible to appropriately determine the activation state of the catalyst while suppressing an increase in cost for detecting the catalyst.

According to the in-cylinder injection type internal combustion engine of the present invention described in claim 8, in the configuration of claim 1 , the fuel injection control means sets the additional fuel injection amount per operation cycle to the catalyst or the catalyst. Since it is configured to be set according to the temperature state of the internal combustion engine, the promotion of the activation by the additional fuel injection amount is performed according to the activation state of the catalyst,
The additional fuel injection can be performed efficiently.

According to a ninth aspect of the present invention, in the cylinder injection type internal combustion engine of the present invention, the fuel injection control means controls the additional fuel injection amount to the fuel injection amount. By setting the opening time of the injection valve and setting the opening time of the fuel injection valve as a function of the rotation speed of the engine, the additional fuel injection can be performed in the exhaust stroke. That is, the advantage of the exhaust stroke injection, that is, the advantage of promoting the activity of the catalyst with a small amount of additional fuel,
Advantages such as hardly affecting the combustion in a normal combustion chamber can be reliably obtained.

According to the in-cylinder injection type internal combustion engine of the present invention , each of the intake, compression, expansion and exhaust strokes is performed in one operation.
In a four-stroke internal combustion engine provided during a dynamic cycle,
Fuel injection valve for injecting fuel directly into a combustion chamber, and the internal combustion engine
Operating state determining means for determining the operating state of the vehicle;
Based on the determination result of the state determination means, the internal combustion engine
When in the operating state, the fuel
Activate the fuel injection valve to inject additional fuel into the combustion chamber
With fuel injection control means, the internal combustion engine has a plurality of cylinders, the fuel injection valve is disposed for each cylinder, and at least some of the plurality of cylinders, The operation phases are set so that the opening timings of the respective exhaust ports partially overlap, and the fuel injection control means determines that each of the cylinders whose opening timings of the exhaust ports overlaps each other. By simultaneously operating the fuel injection valves provided in the fuel injection control means, there is an advantage that the load on the fuel injection control means can be reduced and the cost for the fuel injection control means can be reduced.

According to the in-cylinder injection type internal combustion engine of the present invention, in the configuration of the present invention, the fuel injection control means is provided for the cylinder whose opening timing of the exhaust port overlaps each other. The fuel injection valve provided is simultaneously operated while limiting the operation time so as not to protrude from the overlap period, thereby reducing the load on the fuel injection control means and reducing the exhaust stroke. The advantages of the injection, that is, the advantage of promoting the activity of the catalyst with a small amount of additional fuel, and the advantage of hardly affecting the combustion in a normal combustion chamber can be reliably obtained.

According to a twelfth aspect of the present invention, in the cylinder injection type internal combustion engine of the ninth aspect , the fuel injection
The injection control means determines the opening time of the fuel injection valve by the internal combustion engine.
The faster the rotation speed of the exhaust gas, the shorter the temperature and the temperature of the exhaust gas purification device.
Is set to be shorter as the
If necessary, the amount of additional fuel is controlled to activate the catalyst.
It has the advantage of being performed efficiently .

According to a thirteenth aspect of the present invention, there is provided the in-cylinder injection type internal combustion engine according to any one of the first to third aspects, wherein the internal combustion engine has an ignition means in the combustion chamber. By being configured as a four-cycle internal combustion engine, the catalyst for purifying exhaust gas in a spark ignition type direct injection internal combustion engine can be quickly activated without adding a hardware configuration such as a heater for heating the catalyst to the device. Thus, the exhaust gas can be quickly purified by the catalyst even after the engine is started.

[Brief description of the drawings]

FIG. 1 is a control block diagram schematically showing a main configuration of a control system of a direct injection internal combustion engine as a first embodiment of the present invention.

FIG. 2 is a control block diagram of the direct injection internal combustion engine as the first embodiment of the present invention.

FIG. 3 is an overall configuration diagram of a direct injection internal combustion engine as a first embodiment of the present invention.

FIG. 4 is a hardware block diagram showing a control system of a direct injection internal combustion engine as a first embodiment of the present invention.

FIG. 5 is a diagram showing injection timing of additional fuel in the direct injection internal combustion engine as the first embodiment of the present invention.

FIG. 6 is a diagram showing setting characteristics of an additional fuel injection time of the direct injection internal combustion engine as the first embodiment of the present invention.

FIG. 7 is a flowchart illustrating a fuel injection control of the direct injection internal combustion engine as the first embodiment of the present invention.

FIG. 8 is a flowchart illustrating a fuel injection control of the direct injection internal combustion engine as the first embodiment of the present invention.

FIG. 9 is a flowchart illustrating a first modification of the fuel injection control of the direct injection internal combustion engine as the first embodiment of the present invention.

FIG. 10 is a flowchart illustrating a second modification of the fuel injection control of the direct injection internal combustion engine as the first embodiment of the present invention.

FIG. 11 is a diagram showing injection timing of additional fuel in a direct injection internal combustion engine as a second embodiment of the present invention.

FIG. 12 is a diagram showing setting characteristics of an additional fuel injection time of a direct injection internal combustion engine as a second embodiment of the present invention.

FIG. 13 is a cylinder injection type internal combustion engine as a first embodiment of the present invention .
It is a figure explaining the effect of the catalyst of the engine.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Combustion chamber 2 Intake passage 2a Surge tank 3 Exhaust passage 4 Intake valve 5 Exhaust valve 6 Air cleaner 7 Throttle valve 8 Injector (fuel injection valve) 8a Injector solenoid 8b Switching transistor for injector solenoid 9 Exhaust gas purification catalyst as exhaust gas purification device Converter 9A Lean NOx catalyst 9B Three-way catalyst 11 Air flow sensor 12 Intake temperature sensor 13 Atmospheric pressure sensor 14 Throttle sensor 15 Idle switch 17 Oxygen concentration sensor (O ₂ sensor) 19 Water temperature sensor (Cooling water temperature detecting means) 20 Cranking switch or Ignition switch 21 Crank angle sensor (engine speed sensor) 22 TDC sensor (cylinder discrimination sensor) 23 Electronic control unit (ECU) 24 Accelerator position sensor 25 Battery Resensor 27 CPU 28, 29 Input interface 30 Analog / digital converter 31 ROM 32 RAM 34 Injection driver (fuel injection valve drive means) 35 Spark plug 46 Microcomputer port 47 External register for cylinder discrimination (flip-flop) 48 Free running counter 49-52 register 53-56 comparator 57-60 RS flip-flop 101 fuel injection control means 102 additional fuel injection control means 102A start / end determination section 102B injection time setting section 103 normal fuel injection control means 104 active state determination means (operating state determining means) 104A active state determining unit 104B inactive state determining unit 105 catalyst temperature sensor (catalytic temperature detecting means) 106 main catalyst of O to catalyze timer 107 exhaust gas purification (underfloor catalyst) 10 Cocatalyst of O and catalyst for purifying exhaust gases (front catalyst)

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁷ Identification code FI F02D 41/02 330 F02D 41/02 330A 45/00 312 45/00 312Q 312R (72) Inventor Kazuo Koga Shibago, Minato-ku, Tokyo No. 33-8, Mitsubishi Motors Corporation (56) References JP-A-4-183922 (JP, A) JP-A-3-271540 (JP, A) JP-A-6-93902 (JP, A) JP-A-4-272448 (JP, A) JP-A-8-291729 (JP, A) JP-A-5-79320 (JP, A) JP-A-2-256815 (JP, A) JP-A-3-202613 (JP, A) JP-A-4-136410 (JP, A) JP-A-53-115213 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02D 41/34 F02D 41 / 02 330

Claims (13)

(57) [Claims] 1. A four-stroke internal combustion engine having intake, compression, expansion, and exhaust strokes in one operation cycle, a fuel injection valve for injecting fuel directly into a combustion chamber, and a vehicle in an exhaust passage of the internal combustion engine. Main located under the floor
A catalyst, and the main catalyst and the combustion chamber in the exhaust passage.
Between the main catalyst and the main catalyst.
Exhaust gas purification of auxiliary catalyst with temperature raising function for catalyst
Exhaust gas purification device comprising a catalyst for activation , and an active state determining means for determining an active state of the exhaust gas purification device
The exhaust gas purifying device is in an inactive state by the
And a fuel injection control means for operating the fuel injection valve and injecting additional fuel into the combustion chamber after the expansion stroke of the internal combustion engine if it is determined that the internal combustion engine is in the state. Internal injection type internal combustion engine. 2. The direct injection internal combustion engine according to claim 1, wherein the injection of the additional fuel is set to be performed in the exhaust stroke. 3. The exhaust gas purifying device according to claim 1, wherein
Status determination unit that determines whether the device is in the active state
And a criterion different from the criterion of the active state determining unit.
Determines whether the exhaust gas purification device is in an inactive state
To characterized in that it is composed of an inactive state judging unit, a direct injection type internal combustion engine according to claim 1. 4. The fuel injection control means is configured to terminate the injection of the additional fuel when the active state determination means determines that the catalyst is in an active state. to, cylinder injection type internal combustion engine according to claim 1. 5. A catalyst temperature detecting means for detecting or estimating a temperature of the catalyst, wherein the activation state judging means is configured to detect a temperature of the catalyst exceeding a set value based on detection information from the catalyst temperature detecting means. 5. The direct injection internal combustion engine according to claim 4, wherein the catalyst is determined to be in an active state when the set state has elapsed for a set time. 6. A cooling water temperature detecting means for measuring a cooling water temperature of the internal combustion engine, wherein the activation state determining means sets the cooling water temperature based on detection information from the cooling water temperature detecting means. The in-cylinder injection type internal combustion engine according to claim 4, wherein the catalyst is determined to be in an inactive state when the value is equal to or less than the value. 7. The active state determining means is configured to determine an active state of the catalyst by detecting or estimating at least one of a temperature of the catalyst and a cooling water temperature of the internal combustion engine. 5. The method according to claim 4, wherein
An in-cylinder injection internal combustion engine as described in the above. 8. The fuel injection control means is configured to set an additional fuel injection amount per one operation cycle according to a temperature state of the catalyst or the internal combustion engine. Item 6. An in-cylinder injection internal combustion engine according to item 1 . 9. The fuel injection control means sets the additional fuel injection amount as a valve opening time of the fuel injection valve and sets the valve opening time of the fuel injection valve as a function of an engine speed. The direct injection internal combustion engine according to any one of claims 1 to 3, wherein the internal combustion engine is configured. 10. The process of intake, compression, expansion, and exhaust is performed in one cycle.
Four-stroke internal combustion engine provided during working cycle
A fuel injection valve for injecting fuel directly into the combustion chamber, operating state determining means for determining an operating state of the internal combustion engine, and the internal combustion engine based on a determination result of the operating state determining means.
Is in a predetermined operating state, the expansion stroke of the internal combustion engine and beyond.
Activate the fuel injection valve to lower the fuel and inject additional fuel into the combustion chamber.
The internal combustion engine has a plurality of cylinders, the fuel injection valves are provided for each cylinder, and at least some of the plurality of cylinders are provided. so,
The operation phases are set so that the opening timings of the respective exhaust ports partially overlap, and the fuel injection control means determines that each of the cylinders whose opening timings of the exhaust ports overlaps each other. An in-cylinder injection type internal combustion engine , characterized in that the fuel injection valves provided in the engine are simultaneously operated. 11. The fuel injection control means restricts an operation time of the fuel injection valve provided in a cylinder whose opening timing of the exhaust port overlaps each other so as not to protrude from the overlap period. 11. The direct injection internal combustion engine according to claim 10, wherein the direct injection internal combustion engine is configured to operate simultaneously. 12. The fuel injection control means comprises a fuel injection valve.
The shorter the valve opening time of the internal combustion engine is, the shorter the valve opening time is.
The higher the temperature of the exhaust gas purifying device, the shorter the setting.
10. The direct injection internal combustion engine according to claim 9, wherein the internal combustion engine is configured as follows . 13. The in-cylinder injection according to claim 1, wherein the internal combustion engine is configured as a spark ignition type 4-cycle internal combustion engine having an ignition means in the combustion chamber. Type internal combustion engine.