JPH08296485A - Cylinder injection type internal combustion engine - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to a four-cycle cylinder injection type internal combustion engine, and in such a four-cycle engine, an exhaust gas purifying catalyst can be activated quickly and surely after the engine is started. The purpose is to do. In a four-cycle internal combustion engine, a fuel injection valve 8 that directly injects fuel into a combustion chamber, an operating state determination unit 104 that determines an operating state of the internal combustion engine such as an activated state of an exhaust gas purification catalyst 9, and an operation Based on the determination result of the state determination means 104, when the internal combustion engine is in a predetermined operating state such as when the catalyst 9 is in the inactive state, the fuel injection valve 8 is operated after the expansion stroke of the internal combustion engine. A fuel injection control means 101 for injecting additional fuel into the combustion chamber is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a four-cycle internal combustion engine which has intake, compression, expansion, and exhaust strokes in one operation cycle, and injects fuel directly into a combustion chamber. In particular, the present invention relates to a cylinder injection internal combustion engine suitable for use in fuel injection control for early activation of an exhaust gas purification 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, and such a catalyst is heated to a certain temperature and activated. Without it, the exhaust gas purification capacity cannot be exhibited. Therefore, for example, Japanese Patent Laid-Open No. 4-295153
Japanese Unexamined Patent Publication (Kokai) Publication discloses a technique in which, in a two-cycle engine, a part of the fuel injected into the combustion chamber is blown into the exhaust passage within a required period from immediately after the engine is started to when the catalyst is warmed up. Has been done.

The blowing of the fuel into the exhaust passage is realized by performing the fuel injection Is at the timing of the scavenging stroke. However, when the blown fuel burns by the action of the catalyst in the exhaust passage, the catalyst is exhausted. The temperature of the catalyst rapidly rises, and the catalyst can be activated early. As a result, the exhaust gas is purified by the catalyst immediately after the engine is started, that is, the harmful components (HC, C
It is possible to suppress the emission amount of O, NOx).

In addition, in this technique, the fuel is prevented from being blown into the exhaust passage except during the above-mentioned predetermined period to prevent the fuel consumption rate from being lowered due to the fuel blow-through. The above-described predetermined period is a period during which the engine is operating at low load, and is a period until the cumulative engine speed N1 after the engine starts reaches a predetermined value (first cumulative engine speed) N11. Further, the time (fuel injection time) TAUS for performing the fuel injection Is is always set to a constant time regardless of the engine load Q / N and the engine speed N.

[0005]

By the way, the above-mentioned conventional techniques have the following problems. That is, since the fuel injection Is is executed only during the low load operation, when the driver starts the vehicle immediately after the engine starts, the fuel injection Is is not in the low load operation range, and thus the fuel injection Is is performed.
Is not done. Therefore, in this case, the catalyst cannot be positively activated by the fuel injection Is, and the exhaust gas cannot be purified promptly after starting.

The fuel injection time TAUS is always set to a fixed time, but the time required for activation of the catalyst becomes long depending on the operating conditions and so on.
It may be difficult to achieve early activation of the catalyst if the US is set to a fixed time. That is, when the fuel injection time TAUS is set to a constant time corresponding to the low load operation of the engine, the scavenging time becomes very short during the high load operation, and therefore the fuel injection Is is performed for the fuel injection time TAUS. It will be difficult. Conversely, the fuel injection time TA
If the US is set to a constant time corresponding to the high load operation of the engine, there is a problem that a sufficient amount of fuel cannot be injected during the low load operation in which the activation of the catalyst is most required.

Further, the above-mentioned prior art relates to a two-cycle engine although it is an internal combustion engine (cylinder injection type internal combustion engine) in which fuel is directly injected into a combustion chamber. Therefore, in order to apply such a conventional technique to a four-cycle cylinder injection internal combustion engine in which each stroke of intake, compression, expansion and exhaust is provided in one operation cycle, appropriate measures are required.

The present invention was devised in view of the above-mentioned problems, and is capable of performing fuel injection control suitable for a four-cycle cylinder injection type internal combustion engine to accelerate the exhaust gas purifying catalyst after the engine is started. It is also an object of the present invention to provide a cylinder injection type internal combustion engine that can be surely activated.

[0009]

Therefore, the cylinder injection type internal combustion engine of the present invention as defined in claim 1 is provided with: intake, compression, expansion,
In a four-cycle internal combustion engine in which each stroke of exhaust gas is provided in one operation cycle, a fuel injection valve for directly injecting fuel into a combustion chamber, an operating state determining means for determining an operating state of the internal combustion engine, and the operating state determining means Based on the judgment result of
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 when the internal combustion engine is in a predetermined operating state. There is.

According to a second aspect of the present invention, there is provided an in-cylinder injection type internal combustion engine according to the first aspect, characterized in that the additional fuel is injected in the exhaust stroke. There is. According to a third aspect of the present invention, in the in-cylinder injection internal combustion engine of the second aspect, in the configuration according to the second aspect, the operating state determination means determines an active state of an exhaust gas purifying catalyst provided in an exhaust system of the internal combustion engine. Active state determination means for determining, wherein the fuel injection control means is configured to inject the additional fuel when the active state determination means determines that the catalyst is in an inactive state. It is characterized by that.

According to a fourth aspect of the present invention, in the cylinder injection type internal combustion engine of the present invention, in the structure according to the third aspect, the fuel injection control means determines by the activation state determination means that the catalyst is in the activated state. It is characterized in that it is configured so that the injection of the additional fuel described above is ended when this is done. A cylinder injection type internal combustion engine according to a fifth aspect of the present invention is the structure according to the fourth aspect, further comprising catalyst temperature detecting means for detecting or estimating the temperature of the catalyst, and the activation state determining means for the catalyst temperature detecting means. It is characterized in that, based on the detection information from the detection means, when the temperature of the catalyst exceeds a set value for a set time, it is determined that the catalyst is in the active state. .

According to a sixth aspect of the present invention, there is provided a cylinder injection type internal combustion engine according to the fourth aspect, further comprising cooling water temperature detecting means for raising a cooling water temperature of the internal combustion engine, and the active state determining means. 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 the detection information from the cooling water temperature detecting means.

According to a seventh aspect of the present invention, there is provided a direct injection type internal combustion engine according to the fourth aspect, wherein the active state determining means has at least one of the temperature of the catalyst and the temperature of cooling water of the internal combustion engine. It is characterized in that the active state of the catalyst is determined by detecting or estimating any one of them. According to an eighth aspect of the present invention, in a cylinder injection type internal combustion engine according to the third aspect, the fuel injection control means sets an additional fuel injection amount per operation cycle,
It is characterized in that it is configured to be set according to the temperature state of the catalyst or the internal combustion engine.

According to a ninth aspect of the present invention, there is provided a cylinder injection type internal combustion engine according to the first aspect, wherein
The fuel injection control means is configured to set the additional fuel injection amount as a valve opening time of the fuel injection valve, and set the valve opening time of the fuel injection valve as a function of an engine speed. Is characterized by. The cylinder injection type internal combustion engine of the present invention according to claim 10 is the structure according to any one of claims 1 to 3, wherein the internal combustion engine has a plurality of cylinders, and the fuel injection valve is provided for each cylinder. The fuel injection is performed by setting the operation phases of at least some of the plurality of cylinders so as to partially overlap the opening timings of the respective exhaust ports. It is characterized in that the control means is configured to simultaneously operate the fuel injection valves provided to the cylinders for the cylinders whose opening timings of the exhaust ports overlap each other.

According to an eleventh aspect of the present invention, in the in-cylinder injection type internal combustion engine according to the tenth aspect, the fuel injection control means is provided in a cylinder in which the exhaust port opening timings overlap each other. Further, the fuel injection valve is characterized in that it is configured to be operated simultaneously while limiting the operation time so as not to protrude from the overlap period.

According to a twelfth aspect of the present invention, there is provided an in-cylinder injection type internal combustion engine according to the third aspect, wherein the catalyst is an underfloor catalyst provided under the floor of a vehicle, the underfloor catalyst and the combustion chamber. Between the underfloor catalyst and a front catalyst having a smaller capacity than that of the underfloor catalyst. A cylinder injection type internal combustion engine according to a thirteenth aspect of the present invention is the spark ignition type four-cycle 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 configured as.

[0017]

In the in-cylinder injection type internal combustion engine of the present invention as set forth in claim 1, when the operating state determining means determines that the internal combustion engine is in a predetermined operating state, the fuel injection control means causes the internal combustion engine to operate. After the expansion stroke, the fuel injection valve is operated to inject additional fuel into the combustion chamber. Therefore, most of the additional fuel is easily sent to the exhaust system without being burned.

In the cylinder injection type internal combustion engine according to the second aspect of the present invention, since the injection of the additional fuel is performed in the exhaust stroke of the engine, most of the additional fuel remains unburned and is mixed with air. It will be sent to the exhaust system. In an in-cylinder injection internal combustion engine according to the present invention as set forth in claim 3, the active state determining means as the operating state determining means is provided in an exhaust system of the internal combustion engine as an operating state of the internal combustion engine for exhaust gas purification. Determine the active state of the catalyst. The fuel injection control means injects the additional fuel when the active state determination means determines that the catalyst is in the inactive state.

Most of this additional fuel injection is mixed with air in an unburned state and is sent to the exhaust system to be supplied to the catalyst installed in the exhaust system. The air-fuel mixture containing such unburned fuel is burned by the catalyst, and the temperature of the catalyst is raised to promote its activity. Further, since the additional fuel is supplied to the catalyst while being hardly supplied to the combustion in the combustion chamber, the activity of the catalyst can be promoted with a small amount of the additional fuel, and there is no adverse effect on the combustion of the additional fuel in the combustion chamber. Unlikely to occur.

In the cylinder injection type internal combustion engine of the present invention as set forth in claim 4, when the active state determination means determines that the catalyst is in the active state, the fuel injection control means causes the additional fuel Since the injection is finished, the injection of extra fuel is avoided, and the fuel consumption is suppressed accordingly. In the cylinder injection type internal combustion engine of the present invention according to claim 5, the state in which the temperature of the catalyst exceeds the set value based on the detection information from the catalyst temperature detection means is set for a set time. Although the catalyst is determined to be in the active state when the time has elapsed, the activity of the catalyst depends on the temperature of the catalyst, and therefore the activity of the catalyst is surely grasped by this determination.

According to the sixth aspect of the present invention, in the cylinder injection type internal combustion engine, the active state determination means determines the catalyst based on the detection information from the cooling water temperature detection means when the cooling water temperature is equal to or lower than the set value. Is determined to be inactive. The temperature of the catalyst depends on the exhaust temperature and the combustion state of the engine, and at least
When the engine temperature is low, the catalyst temperature is not high and it can be said that the catalyst is in an inactive state. Since the temperature of the engine corresponds to the temperature of the cooling water, if the cooling water temperature is equal to or lower than the set value, it can be determined that the catalyst is inactive.

In the cylinder injection type internal combustion engine of the present invention as set forth in claim 7, the active state determination means detects or estimates at least one of the temperature of the catalyst and the cooling water temperature of the internal combustion engine. The active state of the catalyst is determined by the method, but the active state of the catalyst can be reliably grasped based on the temperature of the catalyst, and the active state of the catalyst can be reliably estimated based on the cooling water temperature.

In the cylinder injection type internal combustion engine of the present invention as set forth in claim 8, the fuel injection control means sets the additional fuel injection amount per operation cycle in accordance with the temperature state of the catalyst or the internal combustion engine. To do. This additional fuel injection is performed to activate the catalyst, and if the additional fuel injection is performed by an amount corresponding to the activated state of the catalyst, the catalyst can be activated and there is no waste of fuel injection. Since the active 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, additional fuel injection can be performed without excessive injection. Therefore, the activation of the catalyst can be realized.

In the cylinder injection type internal combustion engine of the present invention as defined in claim 9, the fuel injection control means sets the additional fuel injection amount as a valve opening time of the fuel injection valve and opens the fuel injection valve. Since the valve time is set as a function of the rotational speed of the engine, additional fuel injection can be reliably performed within the exhaust stroke. In the in-cylinder injection internal combustion engine of the present invention as set forth in claim 10, for the cylinders of the plurality of cylinders whose exhaust port opening timings overlap each other, the fuel injection valves provided in the respective cylinders are simultaneously operated. Therefore, the control related to the drive operation of the fuel injection valve can be reduced.

In the cylinder injection type internal combustion engine of the present invention as set forth in claim 11, the fuel injection control means operates the operation time so that the cylinders in which the exhaust port opening timings overlap each other do not protrude from the overlap period. Is restricted, so that the situation where the fuel injection valve is activated except when the exhaust port is opened is avoided. In the cylinder injection type internal combustion engine according to the twelfth aspect of the present invention, since the underfloor catalyst can be installed by utilizing the empty space under the floor of the vehicle, the underfloor catalyst having a sufficient capacity can be installed. Further, since the front catalyst is close to the combustion chamber and is small in size, it can be quickly heated and activated even if the additional injection amount of fuel is reduced. Activation of the underfloor catalyst is promoted.

According to the cylinder injection type internal combustion engine of the present invention as set forth in claim 13, the fuel injection valve for the cylinder injection and the ignition means are partially set only in the vicinity of the ignition means in accordance with the setting of the positional relationship. Lean operation with less fuel consumption can be realized by setting a lean air-fuel ratio state for the entire combustion chamber while supplying sufficient fuel to ensure stable combustibility, but with this lean operation N in exhaust gas
The amount of Ox increases. Therefore, in such an engine, a lean NOx catalyst may be provided as the catalyst, and in such a case, activation of the lean NOx catalyst may cause harmful effects in the exhaust gas if the engine operating condition is lean operation. It becomes easy for the substance to be absorbed by the catalyst, and for rich operation, it becomes easy to release the harmful substance absorbed by the catalyst.

[0027]

Embodiments of the present invention will be described below with reference to the drawings. First, referring to FIG. 1 to FIG.
An in-cylinder injection type internal combustion engine will be described as an example.
The structure of the in-cylinder injection internal combustion engine is as shown in FIG. 3, and is an internal combustion engine having four strokes of intake, compression, expansion, and exhaust in one operation cycle, that is, a four-cycle engine. It is an ignition type and is configured as an in-cylinder injection engine that directly injects fuel in the 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, and the intake passage 2 and the combustion chamber 1 are controlled to communicate with each other by an intake valve 4.
The exhaust passage 3 and the combustion chamber 1 are controlled to communicate with each other 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 in order from the upstream side with an exhaust gas purifying catalytic converter 9 as an exhaust gas purifying catalyst.
And a muffler (silencer) not shown is provided.
The intake passage 2 is provided with a surge tank 2a.

The opening of the throttle valve 7 changes according to the amount of depression of an accelerator pedal (not shown), and it is also opened / closed by an idle speed control motor (ISC motor) (not shown). As a result, the opening of the throttle valve 7 can be changed without pressing the accelerator pedal during idling.

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

With this structure, the air sucked through the air cleaner 6 in accordance with the opening degree of the throttle valve 7 is sucked into the combustion chamber 1 by opening the intake valve 4, and the air sucked in the combustion chamber 1 is taken. And the fuel directly injected from the injector 8 are mixed, and the spark plug 35 in the combustion chamber 1 is mixed.
After being ignited at an appropriate timing to be combusted to generate engine torque, the air-fuel mixture is discharged as exhaust gas to the exhaust passage 3, and the catalytic converter (hereinafter, also simply referred to as catalyst) 9 exhausts the exhaust gas. CO, H
After the three harmful components of C and NOx are purified, they are silenced by the muffler and released to the atmosphere side.

Particularly, as will be described later, this engine is an engine capable of performing a saving operation while making the air-fuel ratio lean, and during lean operation, the amount of NOx in the exhaust gas increases, so that the catalyst 9 operates lean NOx. It is a combination of the catalyst 9A and the three-way catalyst 9B. By the way, to explain this engine further, this engine
The intake flow that has flowed into the combustion chamber 1 from the intake passage 2 is configured to form a vertical vortex (reverse tumble flow), and in the combustion chamber 1, the intake flow forms such a vertical vortex flow. While utilizing the vortex flow, for example, the fuel can be collected only in the vicinity of the ignition plug 35 arranged at the center of the top of the combustion chamber 1, and an extremely lean air-fuel ratio state can be obtained in the portion separated from the ignition plug 35. By setting the stoichiometric air-fuel ratio only in the vicinity of the plug 35, it is possible to suppress the fuel consumption while realizing stable combustion.

In particular, since this engine is a cylinder injection engine, there is no restriction on the timing of fuel injection, and fuel injection can be performed at the timing most suitable for realizing the above-mentioned uneven distribution of fuel. It is known that the optimum fuel injection timing in this case is in the latter stage of the compression stroke where the air flow is weak. Further, in order to obtain a high output from this engine, it suffices to burn the entire combustion chamber 1 with a stoichiometric air-fuel ratio, and also at this time, the fuel is sufficiently atomized and vaporized. By performing the fuel injection at such a timing as described above, it is possible to efficiently obtain a high output. The optimum fuel injection timing in this case is known to be set so that the fuel injection is ended in the early or early period of the intake stroke so that the atomization and vaporization of the fuel can be promoted by utilizing the intake flow. ing.

By the way, various sensors are provided to control the engine. First, on the side of the intake passage 2, an air flow sensor 11 for detecting the intake air amount from the Karman vortex information, an intake temperature sensor 12 for detecting the intake air temperature, and an atmospheric pressure sensor 13 for detecting the atmospheric pressure are provided in 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, on the upstream side of the catalyst 9, an oxygen concentration sensor 17 (hereinafter, simply referred to as O ₂ sensor 17) for detecting the oxygen concentration (O ₂ concentration) in the exhaust gas.
Is provided. Further, as other sensors, a water temperature sensor (cooling water temperature detecting means) 19 for detecting the engine cooling water temperature and a crank angle sensor 21 for detecting a crank angle as shown in FIG. 2 (this crank angle sensor 21 indicates the engine speed). Also serves as a rotation speed sensor for detection)
And TDC for detecting the top dead center of the first cylinder (reference cylinder)
A sensor (cylinder discrimination sensor) 22 is provided in each distributor.

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

By the way, the hardware configuration of the ECU 23 is as shown in FIG. 2, and the ECU 23 has a CPU 27 as its main part.
Detection signals from the intake air temperature sensor 12, the atmospheric pressure sensor 13, the throttle sensor 14, the O ₂ sensor 17, the water temperature sensor 19, the accelerator position sensor 24, and the battery sensor 25 are input via the input interface 28 and the analog / digital converter 30. At the same time, detection signals from the air flow 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 through the input interface 29.

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

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

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

Further, the output signal of the air flow sensor 11 is input to the 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 and is then sent to the CPU2.
7 is input to the interrupt terminal INT1. Further, the cylinder discriminating signal from the cylinder discriminating sensor 22 is shaped into a rectangular wave by a waveform shaping circuit as an input interface and is registered in the register 47.
Is input to the intake air temperature sensor 13, atmospheric pressure sensor 13, O
The signals from the ₂ sensor 17, the water temperature sensor 19, etc. are adjusted to an appropriate level by a level adjusting circuit as an input interface, analog / digital converted by the analog / digital converter 30, and input to the port 46. ing.

Further, the injector 8 is adapted to be opened / closed by the switching transistor 8b controlling ON / OFF of power supply from the DC power source (battery) to the valve body injector solenoid 8a. Now, focusing on the fuel injection control (air-fuel ratio control), the fuel injection control signal calculated by the CPU 27 is output via the driver 34,
For example, four injectors 8 are sequentially driven.

Because of the characteristics of the cylinder injection engine as described above, this engine has the following fuel injection modes.
In order to realize lean combustion operation (lean operation), the latter-stage injection mode in which fuel is injected in the latter part of the compression stroke and the theoretical air-fuel ratio operation (theoretical air-fuel ratio operation) are realized at the beginning or the beginning of the intake stroke. Is provided with a first-term injection mode for finishing fuel injection. In this stoichiometric air-fuel ratio operation, when the amount of fuel to be supplied is large, fuel injection may start from the latter half or the latter half of the exhaust stroke, and may end in the early or the first half of the intake stroke.

Further, in particular, in the present internal combustion engine, in addition to the fuel injection for combustion in the normal combustion chamber as described above, additional fuel is injected to activate the catalyst 9. There is. In this additional fuel injection, the air-fuel mixture containing the unburned fuel component is supplied to the catalyst 9, so that the unburned fuel component in the air-fuel mixture is burned by the catalyst 9 to raise the temperature of the catalyst 9 and activate it. Is what you are trying to do.

Therefore, 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). Between) and not 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 a fuel injection control during normal operation. Function (normal fuel injection control means)
And additional fuel injection control means 102.
Is a characteristic constituent element of the main cylinder injection type internal combustion engine for purifying exhaust gas.

Since the additional fuel injection control means 102 performs control based on the operating state of the internal combustion engine, particularly the active state of the catalyst 9, the CPU 27 causes the CPU 27 to determine the active state determining means (operating state). State determination means) 104 is provided. The active state determination means 104 includes detection information from a catalyst temperature sensor (catalyst temperature detection means) 105 that detects the temperature of the catalyst 9 and a water temperature sensor (cooling water temperature detection means) 19 that detects the cooling water temperature of the engine, and a timer 106. Based on the timer count information from the catalyst 9
The active state of is determined.

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

The inactive state judging section 104B is for judging whether the catalyst 9 needs to be activated by the additional fuel injection, and the engine cooling water temperature Tw detected by the water temperature sensor 19 is the predetermined temperature T _0. If it is below, it is determined that the catalyst 9 is in the inactive state. The active state determination unit 104A is for determining whether or not the catalyst 9 has been sufficiently activated when the additional fuel injection is performed, and the temperature Temp.c / of the catalyst 9 detected by the catalyst temperature sensor 105. c is the predetermined temperature T ₁
State (or a state in which the time exceeds a predetermined time t ₀ )
When the continuous time tc / c of is greater than or equal to the predetermined time t ₀ , it is determined that the catalyst 9 is in the active state.

The additional fuel injection control means 102 has a function (start / end determination unit) 102A for instructing the start and end of the additional fuel injection, and a function (injection time setting unit) for setting the injection time of the additional fuel in each cycle. ) 102B is provided. Of these, the start / end determination unit 102A determines to start additional fuel injection when the inactive state determination unit 104B determines that the catalyst 9 is in the inactive state, and the active state determination unit 104A determines that the catalyst 9 is inactive. When it is determined that the fuel cell is in the active state, it is determined that the additional fuel injection should be ended.

By the way, the active state of the catalyst 9 is the catalyst temperature T.
Since the determination can be made based on emp c / c, the inactive state determination, which is the determination of whether to start additional fuel injection by the inactive state determination unit 104B, is similar to the determination of the active state, that is, the catalyst temperature Tempc You may make it based on / c. Further, the cooling water temperature Tw is the catalyst temperature Temp c /
Since it substantially corresponds to c, the inactive state determining unit 104B determines the inactive state and the active state determining unit 104A
The cooling water temperature Tw may also be used for the determination of the active state by. That is, the cooling water temperature Tw increases
This is after the combustion is sufficiently performed after the engine is started, and if the combustion is sufficiently performed, the catalyst temperature Temp c / c is also sufficiently increased by the high temperature exhaust gas. On the contrary, the cooling water temperature T
If w is low, it means that combustion has not been sufficiently performed after the engine is started, and the catalyst temperature Tem due to exhaust gas is Tem.
This is because it can be determined that the rise in pc / c is not yet sufficient.

In this embodiment, the determination of the inactive state is based on the cooling water temperature Tw, but this is because the detection range of the catalyst temperature sensor 105 is near the active region of the catalyst 9. This is because it is more suitable to make a determination using the cooling water temperature Tw for 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 region lower than the vicinity of the active region of the catalyst 9, the determination of the inactive state is based on the catalyst temperature Temp c / c as described above. You can

Further, the determination of the active state which is the condition for ending the additional fuel injection is such that the state in which the catalyst temperature Temp c / c becomes equal to or higher than the predetermined temperature T ₁ continues for the predetermined time t ₀ or more. The determination is made using the duration time t ₀ in this way because it is desired to end the additional fuel injection 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, but this additional fuel injection 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 unit 102B, the temperature Temp.
It is set according to c / c and the engine speed (engine speed) Ne. For example, as shown in FIG. 6, the injection time t _ex becomes shorter as the catalyst temperature Temp.c / c becomes higher, and the injection time t becomes higher as the engine speed Ne becomes higher.
_ex is set to be short.

This is because the lower the catalyst temperature Temp.c / c is, the more the catalyst 9 needs to be activated. Therefore, the additional fuel is injected more to promote the activation of the catalyst 9, and conversely, the catalyst temperature Temp.c. c /
The higher the c, the more unnecessary the activation of the catalyst 9, so
It is intended to reduce the injection of additional fuel. Also, the higher the engine speed Ne, the shorter the time required for one operation cycle, and therefore the shorter the exhaust stroke in one operation cycle and the shorter the time during which fuel injection can be performed within the exhaust stroke. Therefore, the engine speed Ne
Is higher, the injection time of additional fuel is shorter.

Such additional fuel injection is carried out separately from the normal fuel injection, as shown in FIG. By the way, the fuel injection control in the normal fuel injection control means 103 will be explained. In the normal operation time control means 103, the injection mode is based on the engine speed (rotation speed) Ne and the accelerator pedal depression amount θ _ACC. The output torque T is set, and one of the early injection mode and the late 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 either of the above is not low, the previous period injection mode is set.

The fuel injection amount is set as the fuel injection time (the injector drive time, which is called the injector drive pulse width in actual control) t _AU , but the latter injection mode is also used in the early injection mode. In the case of
Engine load (intake air amount per stroke) Q / Ne
Based on the target air-fuel ratio (A / F, hereinafter referred to as AF) and the like, 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 ) Note that the engine load Q / Ne is the intake air amount per stroke, and the intake air amount 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 in 1. Further, α _AIR is the air density, α _FUEL is the fuel density, and G _INJ is the injector gain.

The fuel injection time t _AU is calculated by the following equation. t _AU = t _p × K + t _D where K is various fuel correction coefficients, which are the engine cooling water temperature detected by the water temperature sensor 19, the intake air temperature detected by the intake air temperature sensor 12, and the large value. It is set according to the atmospheric pressure or the like detected by the atmospheric pressure sensor 13. Further, t _D is an injector dead time.

Since the engine exhaust gas purifying apparatus as the first embodiment of the present invention is constructed as described above,
For example, as shown in FIG. 7, normal fuel injection control and additional fuel injection (exhaust stroke fuel injection) determination are performed. Figure 7
The routine shown in is executed every fixed crank angle, but first, for normal fuel injection, steps A10 to A10 are performed.
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 detected by the air flow sensor 11 and the rotation speed sensor 21 and the engine rotation speed Ne.
e (that is, the intake air amount per stroke) is calculated. Next, in step A20, the basic drive time t _p is calculated based on the engine load Q / Ne as shown in the above equation. Further, in step A30, the fuel injection time t _AU is calculated by multiplying the basic drive time t _p by various fuel correction coefficients K and the like.

Then, in step A40, the water temperature sensor 1
The engine cooling water temperature Tw detected in 9 is the predetermined temperature T₀
It is determined whether or not the following. Here, the cooling water temperature Tw is a predetermined temperature.
Degree T ₀If the following, in step A50, the catalyst activation flag
It is determined whether F is 1. This catalyst activation flag F is touched.
1 if additional fuel injection for medium activation should be performed
Becomes 0 when no additional fuel injection is required.
In addition, it is set to 1 at the time of initial setting.

Normally, since the flag F is 1, step A
The routine proceeds from 50 to step A60, where exhaust stroke fuel injection control (that is, additional fuel injection control) described later is performed. If the cooling water temperature Tw is not lower than or equal to the predetermined temperature T ₀ , the catalyst 9 is not in the inactive state, so the exhaust stroke fuel injection control (additional fuel injection control) is not performed. 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, it is set according to the temperature Temp.c / c of the catalyst 9 and the engine speed Ne. Next, in step B20, it is determined whether the catalyst temperature Temp.c / c detected by the catalyst temperature sensor 105 is equal to or higher than the threshold value T ₁ , and the catalyst temperature Temp.c / c is equal to or higher than the threshold value T _1. Otherwise,
The timer is reset in step B30, and then step B4
At 0, the exhaust stroke fuel injection (additional fuel injection) is executed.
As shown in FIG. 5, the additional fuel injection is performed by the additional fuel injection time t set in step B10 in the exhaust stroke.
Only _{ex is} executed.

By the additional fuel injection in the exhaust stroke, the air-fuel mixture containing unburned fuel components is supplied to the catalyst 9 and burned by the catalyst 9. As a result, the catalyst 9
Gradually increases, and the catalyst temperature Temp.c / c becomes the threshold value T ₁
When the above is reached, the process proceeds from step B20 to step B50 to start the timer count. Then, step B
At 60, it is determined whether the value tc / c of the timer count is less than the threshold value t ₀ .

Immediately after the timer count is started, the timer count value tc / c is less than the threshold value t ₀ , so the routine proceeds from step B60 to step B40, where the exhaust stroke fuel injection (additional fuel injection) is executed. On the other hand, as the timer count advances,
When the timer count value tc / c becomes equal to or greater than the threshold value t ₀ , the process proceeds from step B60 to step B70, and the flag F is set to 0.
To complete the exhaust stroke fuel injection (additional fuel injection).

Thus, when the flag F is set to 0 in step B70, the cooling water temperature Tw is set until the flag F is set to 1 in step A80 of FIG.
Until the temperature exceeds the predetermined temperature T ₀ , step A in FIG.
According to the determination of 50, the exhaust stroke fuel injection (additional fuel injection) in 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.

In this way, for example, when the engine temperature is low at the time of starting, the exhaust stroke fuel is kept until the temperature Temp.c / c of the catalyst 9 is equal to or higher than the threshold value T ₁ for a predetermined time t ₀ or more. When the injection (additional fuel injection) is performed, the catalyst 9
Since the temperature is raised, the catalyst 9 is quickly and surely heated and activated after the engine is started. Therefore, immediately after the engine is started, the exhaust gas is purified by the catalyst 9, that is, harmful components (HC, CO, N in the exhaust gas are removed.
It becomes possible to suppress the emission amount of Ox).

Further, since the temperature of the catalyst 9 can be raised without adding a hardware structure such as a heater for heating the catalyst to the apparatus, the activation of the catalyst 9 can be realized while suppressing the cost increase. Further, since the additional fuel injection is performed in the exhaust stroke, the additional fuel is scarcely supplied to the catalyst 9 together with the exhaust gas in an unburned state without being used for combustion in the combustion chamber. The additional fuel can promote the activity of the catalyst 9. In the exhaust stroke, the high-temperature exhaust gas after burning in the combustion chamber 1 flows out, so that the additional fuel supplied to the catalyst 9 together with this high-temperature exhaust gas is rapidly burned by the catalyst 9 to generate heat. The activity of the catalyst 9 can be promoted more actively.

In addition, the injection in the exhaust stroke is the case where the additional fuel injection is performed because the adverse effect on the combustion in the normal combustion chamber is unlikely to occur unless it is performed near the end of the exhaust stroke. However, the control of the normal fuel injection (that is, the fuel injection in the intake stroke from the end of the exhaust stroke) is the same whether the additional fuel injection is performed or not. Can be done.

As shown in FIG. 6, the injection amount of the additional fuel injection increases as the catalyst temperature Temp.c / c increases.
_{Since ex} becomes shorter and the injection time t _ex becomes shorter as the engine speed Ne becomes higher, additional fuel injection can be realized as needed, and there is no waste of additional fuel injection, and catalyst 9 It can be activated quickly. Further, the injection time of the additional fuel is shortened as the engine speed Ne is higher, so that the additional fuel injection can be performed only within the exhaust stroke in each combustion cycle, and the additional fuel injection is performed within the exhaust stroke as described above. It is possible to surely obtain the advantage of performing.

Further, when the temperature of the catalyst 9 is surely raised to the predetermined temperature T ₁ , this additional fuel injection is completed, so the catalyst 9
The increase in fuel consumption due to the temperature rise of is also suppressed. In addition to the lean NOx catalyst provided in the catalyst 9, the following effects can be expected. In other words, lean N
The Ox catalyst is NO when the air-fuel ratio of the inflowing exhaust gas is lean.
NOx absorbent that absorbs x and releases the absorbed NOx when the oxygen concentration in the inflowing exhaust gas decreases,
When the NOx absorption amount of the absorbent increases, it is necessary to switch to the rich operation (operation with the air-fuel ratio rich) during the lean operation (operation with the air-fuel ratio lean) to release the absorbed NOx. In this way, if the rich operation is switched during the lean operation, the driver may feel uncomfortable.

On the other hand, in the present internal combustion engine, the additional fuel injection is performed within the exhaust stroke so as not to affect the fuel injection for normal combustion. Therefore, for example, NOx due to the additional fuel injection is continued while continuing lean operation. Can be released, and regeneration of the lean NOx catalyst (release of NOx) can be performed without making the driver feel uncomfortable. Also,
Since the NOx absorbent contains sulfur contained in the fuel and the 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. 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 such as sulfur oxide SO ₃ , so
I want to release it after making it harmless. Such harmful sulfur content (for example, sulfur oxide SO ₃ ) is immediately oxidized by unburned HC and CO in the exhaust gas and becomes harmless, so that the NOx absorbent is heated in a rich operation or stoichiometric state. During operation, the sulfur content absorbed by the NOx absorbent becomes harmless and is released from the NOx absorbent.

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

The difference from the control of the embodiment is 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 judged by the catalyst temperature T.
When performing based on emp c / c, fuel injection control is
This is performed as shown in FIG. The difference from the control of the first embodiment (FIG. 7) is that the deactivation of the catalyst 9 is determined (step A).
42), and in step A42, the catalyst temperature sensor 1
It is determined whether the catalyst temperature Temp.c / c detected in 05 is less than or equal to a predetermined temperature T ₀₀ .

If the catalyst temperature Temp.c / c is lower than the predetermined temperature T ₀₀ , the additional fuel injection control routine (FIG. 8) in the exhaust stroke is executed 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. The determination threshold T ₀₀ is
It is set to a value lower than the activation determination threshold T ₁ used in step B20 of FIG.

When both the inactive state determination by the inactive state determination unit 104B and the active state determination by the active state determination unit 104A are performed based on the cooling water temperature Tw, the additional fuel injection control is performed as shown in FIG. It is performed as shown in FIG. The difference from the control of the first embodiment (FIG. 8) is the determination of activation of the catalyst 9 (step B22). In step B22, the engine cooling water temperature Tw detected by the water temperature sensor 19 is the predetermined temperature T _11. It is determined whether or not the above.

If the cooling water temperature Tw is not higher than the predetermined temperature T ₁₁ , additional fuel injection is performed in the exhaust stroke. Cooling water temperature Tw
Is equal to or higher than the predetermined temperature T ₁₁ , the timer count tc / c finishes counting the required time, and then the additional fuel injection in the exhaust stroke is finished. Next, a second embodiment will be described. The internal combustion engine (engine) according to this embodiment is
It has a cylinder, and is configured as a V-type 12-cylinder engine, for example. Of course, this engine is also a spark ignition type four-cycle engine, and is configured as an in-cylinder injection engine that directly injects fuel in the cylinder.

Also in the engine of this embodiment, the additional fuel injection control means 102 and the normal fuel injection control means 103 are provided in the fuel injection control means 101, and in the additional fuel injection control means 102, the active state determination means 104 determines. The additional fuel injection is controlled based on the activated state of the catalyst 9. Further, this additional fuel injection is similar to the first embodiment,
Although the exhaust stroke of each cylinder is performed, in an engine having a large number of cylinders, the exhaust strokes of a plurality of cylinders may overlap (overlap). For example, in the case of a 12-cylinder engine as in this embodiment, the exhaust strokes of three cylinders simultaneously overlap as shown in FIG.

In the additional fuel injection control means 102 of the present embodiment, the 12 cylinders are divided into four groups each of which has three cylinders that overlap each other in the exhaust stroke, and the additional fuel injection in the exhaust stroke is performed for each group. Is designed to do. In this example, as shown in FIG.
First cylinder (# 1), second cylinder (# 2), and ninth cylinder (#
9) group (first group), 10th cylinder (# 1
0), 5th cylinder (# 5) and 6th cylinder (# 6) group (2nd group), 11th cylinder (# 11), 12th cylinder (# 12) and 3rd cylinder (# 3) Group (third group), fourth cylinder (# 4), seventh cylinder (# 7) and eighth group
The cylinders (# 8) and the group (fourth group) are divided into four groups, and the additional fuel injection in the exhaust stroke is performed simultaneously in the cylinders of each group.

By the way, the plurality of cylinders in each group are
As shown in FIG. 11, although there is a period during which the exhaust strokes are simultaneously performed, this period is naturally shorter than the exhaust stroke of a single cylinder, and in the case of 12 cylinders as in the present embodiment,
The period of common exhaust stroke for each cylinder in the group is approximately one third of the exhaust stroke period for a 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, in the injection time setting unit 102B, for example, as shown in FIG. 12, and sets the upper limit t _ex (Ne) _MAX injection time t _ex according to the engine RPM Ne. This upper limit value t
_ex (Ne) _MAX is set to the amount of displacement of the crank angle defined by the broken line showing the region of group injection in FIG. 11, and the injection time t _ex is limited by this upper limit value t _ex (Ne) _MAX . As a result, additional fuel injection is performed for each cylinder in the group during the exhaust stroke.

The injection time t _ex is set within such limits according to the temperature Temp.c / c of the catalyst 9 and the engine speed Ne, as in the first embodiment. The other parts are configured in the same manner as in the first embodiment. Since the engine exhaust gas purifying apparatus as the second embodiment of the present invention is configured as described above, each cylinder is a group of a plurality of cylinders (here, three cylinders) that are simultaneously in the exhaust stroke. In both cases, additional fuel injection is performed at the same time while being limited during the exhaust stroke, so that the same operation and effect as in the first embodiment can be obtained, and the load on the CPU for controlling the fuel injection valve can be reduced. There is also an advantage that the cost of the CPU can be reduced.

Next, the third embodiment will be described. In this embodiment, as shown in FIG. 13, the catalyst 9 comprises a main catalyst 107 and an auxiliary catalyst 108, and the main catalyst 107 is installed under the floor of the vehicle. And the auxiliary catalyst 108
Is a front catalyst arranged in the exhaust passage 3 between the underfloor catalyst 107 and the combustion chamber 1 before the underfloor catalyst 107. The auxiliary catalyst (front catalyst) 108 has a smaller capacity than the main catalyst (underfloor catalyst) 107, and is arranged at a position near the combustion chamber 1 upstream of the exhaust passage 3, that is, at a position close to the exhaust port 3A. There is.

Purification of the exhaust gas, that is, suppression of the emission of harmful components (HC, CO, NOx) in the exhaust gas is mainly performed by the underfloor catalyst 107, and the front catalyst 108 activates the underfloor catalyst 107 early. Are being used for. Then, in the additional fuel injection control means 102, the temperature Temp.c / c of the underfloor catalyst 107 is equal to or lower than a predetermined value T ₀₀ (or the engine cooling water temperature T which is a condition corresponding thereto).
If w is equal to or lower than the predetermined temperature T ₀ ), the catalyst 9 is in the inactive state, so that the additional fuel injection in the exhaust stroke is performed as in the first and second embodiments.

The other parts are constructed similarly to the first embodiment. Since the engine exhaust gas purifying apparatus as the third embodiment of the present invention is configured as described above, when the temperature Temp.c / c of the underfloor catalyst 107 is low and inactive, additional fuel injection in the exhaust stroke is performed. Is performed,
First, the front catalyst 108 near the combustion chamber 1 is heated and activated, and the heat of the front catalyst 108 heats and activates the underfloor catalyst 107 installed downstream.

At this time, the front catalyst 108 is in the combustion chamber 1
Therefore, the additional fuel injected in the exhaust stroke is supplied to the catalyst 108 together with the high-temperature exhaust gas after combustion in the combustion chamber 1. For this reason, a part of the additional fuel causes a combustion reaction to generate heat before entering the front catalyst 108, so that an extremely high temperature exhaust gas and an unburned gas that easily burns flow into the front catalyst 108. The fuel gas rapidly burns and reacts with the front catalyst 108 to generate heat.

As a result, the temperature of the front catalyst 108 rises extremely quickly. In particular, even if the injection amount of the additional fuel is small, the temperature of the front catalyst 108 can be raised sufficiently quickly to supply sufficient heat to the underfloor catalyst 107, and the temperature of the underfloor catalyst 107 can also be raised rapidly. Activate. As a result, the temperature rise of the underfloor catalyst 107 can be increased by injection of a smaller amount of additional fuel than in the first and second embodiments.
There is an advantage that the activation can be realized and the fuel required for the activation of the catalyst 107 can be saved.

The front catalyst 108 is the underfloor catalyst 1
A small one that can supply the heat-up heat to 07 is sufficient, and the exhaust passage 3 can be sufficiently installed in a narrow place near the exhaust port 3A. On the other hand, underfloor catalyst 1
No. 07 requires a sufficient capacity for purifying exhaust gas, but since it is relatively easy to secure a space for this under the floor of the vehicle, the underfloor catalyst 107 having a sufficient capacity can be laid out relatively freely. It can be installed at.

In this way, in the engine of this embodiment, the catalyst (the underfloor catalyst 107) having a sufficient capacity is installed, and the temperature of the catalyst is rapidly increased and activated by a little additional fuel injection. Therefore, exhaust gas purification can be promoted more actively. By the way,
FIG. 4 is a diagram showing the characteristics of the amount of HC emissions and the catalyst temperature generated as the vehicle travels. When the vehicle travels at a vehicle speed as shown in (C), the amount of HC emissions is (A ), The catalyst temperature [here, the temperature of the base material (catalyst bed) on which the catalyst is installed] changes as shown in (B).

That is, as shown in (B), the temperature of the front catalyst rapidly rises, and that of the underfloor catalyst rises so as to follow the temperature of the front catalyst, so that these front catalyst and underfloor catalyst are provided at the same time. In this case, as shown in (A), it is understood that the exhaust gas purification performance is improved as compared with the case where only the underfloor catalyst is provided. In each of the above embodiments, the injection of additional fuel for activating the catalyst is performed in the exhaust stroke, but this additional fuel injection is not necessarily limited to the exhaust stroke, and the expansion stroke, intake stroke, etc. Even if it is carried out in other steps, the advantage that the catalyst can be activated early can be obtained.

[0090]

As described in detail above, according to the direct injection type internal combustion engine of the present invention as defined in claim 1, a four-cycle internal combustion engine having each stroke of intake, compression, expansion and exhaust in one operation cycle. In the engine, a fuel injection valve that directly injects fuel into a combustion chamber, an operating state determination unit that determines an operating state of the internal combustion engine, and a predetermined operation of the internal combustion engine based on a determination result of the operating state determination unit. And a fuel injection control means for injecting additional fuel into the combustion chamber by operating the fuel injection valve after the expansion stroke of the internal combustion engine when in the state Therefore, the fuel can be supplied to the element that needs the fuel (for example, the fuel necessary element such as the exhaust gas purifying catalyst at the time of activation promotion) installed in the exhaust system. The fuel supplied to the fuel necessary element burns in the process until it is supplied to the fuel necessary element or when it is supplied to the fuel necessary element, and in the case of the exhaust gas purifying catalyst, the combustion heat thereof activates the catalyst. An effect that can be promoted and an effect that the exhaust gas purification catalyst can be adjusted to a required temperature state are obtained.

According to the cylinder injection type internal combustion engine of the present invention as set forth in claim 2, in the structure of claim 1, the injection of the additional fuel is set to be performed in the exhaust stroke, Elements that can efficiently supply a mixture containing unburned fuel components to the exhaust system by the additional fuel and that require fuel installed in the exhaust system (for example, an exhaust gas purification catalyst during activation promotion) Can be supplied with fuel. The required fuel can be supplied to the fuel required element with a small amount of additional fuel, and the exhaust gas purifying catalyst has an effect of efficiently promoting the activity of the catalyst by the combustion heat thereof.

According to the in-cylinder injection type internal combustion engine of the present invention as defined in claim 3, in the construction of claim 2, the operating condition determining means is for exhaust gas purification provided in an exhaust system of the internal combustion engine. An active state determination means for determining an active state of the catalyst, wherein the fuel injection control means performs injection of the additional fuel when the active state determination means determines that the catalyst is in an inactive state. With the above configuration, when the catalyst is in the inactive state, the mixture containing the unburned fuel component is supplied to the catalyst by the additional fuel and burned,
There is an advantage that the catalyst can be rapidly activated and the exhaust gas can be promptly purified by the catalyst even after the engine is started. Further, it is not necessary to add a hardware structure such as a heater for heating the catalyst to the apparatus, and the activation of the catalyst can be realized while suppressing the cost increase.

According to the cylinder injection type internal combustion engine of the present invention as set forth in claim 4, in the structure of claim 3, the fuel injection control means is that the catalyst is in the active state by the active state determining means. When it is determined that the additional fuel injection is completed, 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 the cylinder injection type internal combustion engine of the present invention as set forth in claim 5, in the structure of claim 4, the catalyst temperature detecting means for detecting or estimating the temperature of the catalyst is provided, and the active state determining means is provided. Is configured to determine that the catalyst is in an active state based on the detection information from the catalyst temperature detection means when the temperature of the catalyst exceeds a set value for a set time. As a result, the active state of the catalyst can be reliably determined, and the exhaust gas purification by the catalyst can be performed more reliably.

According to the cylinder injection type internal combustion engine of the present invention described in claim 6, in the structure of claim 4, the cooling water temperature detecting means for heating the cooling water temperature of the internal combustion engine is provided.
By the active state determination means is configured to determine that the catalyst is inactive when the cooling water temperature is equal to or lower than a set value based on the detection information from the cooling water temperature detection means, The catalyst can be surely activated immediately after starting, and exhaust gas purification by the catalyst can be performed more reliably.

According to the cylinder injection type internal combustion engine of the present invention as set forth in claim 7, in the structure of claim 4, the activation state determining means determines whether the temperature of the catalyst or the cooling water temperature of the internal combustion engine. It is configured to determine the active state of the catalyst by detecting or estimating at least one 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 active state of the catalyst while suppressing an increase in the cost required for detecting.

According to the in-cylinder injection type internal combustion engine of the present invention described in claim 8, in the configuration according to any one of claims 1 to 3, the fuel injection control means is configured to add additional fuel per operating cycle. Since the amount is set according to the temperature state of the catalyst or the internal combustion engine, the activation is promoted by the additional fuel injection amount according to the activation state of the catalyst. Can be performed efficiently.

According to the cylinder injection type internal combustion engine of the present invention described in claim 9, in the structure according to any one of claims 1 to 3, the fuel injection control means sets the additional fuel injection amount to the fuel. By setting the valve opening time of the injection valve and setting the valve opening time of the fuel injection valve as a function of the rotational speed of the engine, additional fuel injection can be performed within the exhaust stroke. Therefore, the advantage of exhaust stroke injection, that is, the advantage of promoting the activity of the catalyst with a small amount of additional fuel,
It is possible to surely obtain the advantage that the influence on the combustion in the normal combustion chamber is unlikely to occur.

According to the cylinder injection type internal combustion engine of the present invention described in claim 10, in the structure according to any one of claims 1 to 3, the internal combustion engine has a plurality of cylinders, and the fuel injection valve Are arranged for each cylinder, and their operating phases are set such that at least some of the above-mentioned cylinders partially overlap the opening timing of each exhaust port. Then, the fuel injection control means is configured to simultaneously operate the fuel injection valves provided in the cylinders for the cylinders whose opening timings of the exhaust ports overlap each other. There is an advantage that the load of the means can be reduced and the cost for the fuel injection control means can be reduced.

According to the cylinder injection type internal combustion engine of the present invention as set forth in claim 11, in the structure of claim 10, the fuel injection control means is arranged in a cylinder in which the opening timings of the exhaust ports overlap each other. The fuel injection valve provided is configured to be operated simultaneously while limiting the operation time so as not to protrude from the overlap period, thereby reducing the load of the fuel injection control means and performing the exhaust stroke. It is possible to surely obtain the advantage of injection, that is, the advantage that the activity of the catalyst can be promoted with a small amount of additional fuel and that the influence on the combustion in the normal combustion chamber is unlikely to occur.

According to the cylinder injection type internal combustion engine of the present invention as set forth in claim 12, in the structure of claim 3, the catalyst is an underfloor catalyst provided under the floor of the vehicle, the underfloor catalyst and the combustion. While being installed in the exhaust passage between the chamber and the front catalyst having a smaller capacity than the underfloor catalyst, while installing a sufficient capacity of the catalyst as the underfloor catalyst,
There is an advantage that the underfloor catalyst can be rapidly heated and activated through the front catalyst by a slight additional fuel injection, and exhaust gas purification can be more actively promoted.

According to the cylinder injection type internal combustion engine of the present invention as set forth in claim 13, in the structure according to any one of claims 1 to 3, the internal combustion engine has spark ignition having an ignition means in the combustion chamber. By being configured as a four-cycle internal combustion engine, the exhaust gas purifying catalyst in the 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. Therefore, the exhaust gas can be promptly purified by the catalyst even after the engine is started.

[Brief description of 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 in a direct injection internal combustion engine as a 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 a cylinder injection type internal combustion engine as a first embodiment of the present invention.

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

FIG. 7 is a flow chart for explaining fuel injection control of a cylinder injection type internal combustion engine as a first embodiment of the present invention.

FIG. 8 is a flow chart for explaining fuel injection control of a direct injection internal combustion engine as a first embodiment of the present invention.

FIG. 9 is a flowchart for explaining a first modified example 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 for explaining a second modified example 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 cylinder injection type internal combustion engine as a second embodiment of the present invention.

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

FIG. 13 is an overall configuration diagram of a cylinder injection type internal combustion engine as a third embodiment of the present invention.

FIG. 14 is a diagram for explaining the effect of the catalyst of the cylinder injection type internal combustion engine as the third embodiment of the present invention.

[Explanation 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 Injector solenoid switching transistor 9 Exhaust gas purification as exhaust gas purification catalyst Catalyst converter 9A lean NOx catalyst 9B three-way catalyst 11 air flow sensor 12 intake air 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 detection 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 sensor 27 CPU 28, 29 Input interface 30 Analog / digital converter 31 ROM 32 RAM 34 Injection driver (fuel injection valve driving means) 35 Spark plug 46 Microcomputer port 47 Cylinder discrimination external register (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 (operation) State determination means) 104A Active state determination section 104B Inactive state determination section 105 Catalyst temperature sensor (catalyst temperature detection means) 106 Timer 107 Underfloor catalyst 108 Front catalyst

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location F02D 41/02 330 F02D 41/02 330A 45/00 312 45/00 312R 312Q (72) Inventor Koga Kazuo 5-3-8 Shiba, Minato-ku, Tokyo Inside Mitsubishi Motors Corporation

Claims (13)

[Claims] 1. A four-cycle internal combustion engine having intake, compression, expansion, and exhaust strokes in one operation cycle, and a fuel injection valve for directly injecting fuel into a combustion chamber and an operating state of the internal combustion engine are determined. Based on the operating state determination means and the determination result of the operating state determination means, when the internal combustion engine is in a predetermined operating state, the fuel injection valve is operated after the expansion stroke of the internal combustion engine to cause the combustion chamber to enter the combustion chamber. An in-cylinder injection type internal combustion engine, comprising: a fuel injection control means for injecting additional fuel. 2. The in-cylinder 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 operating state determining means is an active state determining means for determining an active state of an exhaust gas purifying catalyst equipped in an exhaust system of the internal combustion engine, and the fuel injection control means is for the active state determining means. When the state determination means determines that the catalyst is in an inactive state, it is configured to inject the additional fuel.
The cylinder injection internal combustion engine according to claim 2. 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. The in-cylinder injection internal combustion engine according to claim 3. 5. The catalyst temperature detection means for detecting or estimating the temperature of the catalyst is provided, and the activation state determination means determines that the temperature of the catalyst exceeds a set value based on the detection information from the catalyst temperature detection means. 5. The in-cylinder injection internal combustion engine according to claim 4, wherein the catalyst is configured to determine that the catalyst is in an active state when the above state has elapsed for a set time. 6. The cooling water temperature detecting means for heating the cooling water temperature of the internal combustion engine is provided, and the active state judging means sets the cooling water temperature based on the detection information from the cooling water temperature detecting means. The in-cylinder injection internal combustion engine according to claim 4, wherein when the value is less than or equal to a value, the catalyst is determined to be in an inactive state. 7. The activation state determination means is configured to determine the activation state of the catalyst by detecting or estimating at least one of the temperature of the catalyst and the cooling water temperature of the internal combustion engine. 5. The method according to claim 4, wherein
The in-cylinder injection internal combustion engine described. 8. The fuel injection control means is configured to set an additional fuel injection amount per one operation cycle in accordance with a temperature state of the catalyst or the internal combustion engine. Item 3. A cylinder injection internal combustion engine according to item 3. 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 the rotational speed of the engine. The in-cylinder injection internal combustion engine according to any one of claims 1 to 3, which is configured. 10. The internal combustion engine has a plurality of cylinders, the fuel injection valve is provided for each cylinder, and between at least some of the plurality of cylinders,
For the cylinders in which the operation phases of the respective exhaust ports are set so that the opening timings of the respective exhaust ports partially overlap each other, and the fuel injection control means are such that the opening timings of these exhaust ports overlap each other, The in-cylinder injection internal combustion engine according to any one of claims 1 to 3, which is configured to simultaneously operate the fuel injection valves provided in the above. 11. The fuel injection control means limits an operating time of the fuel injection valve provided in a cylinder in which the opening timings of the exhaust ports overlap each other so that the fuel injection valve does not protrude from the overlap period. 11. The in-cylinder injection internal combustion engine according to claim 10, wherein the internal combustion engine is configured to be operated simultaneously while being operated. 12. The catalyst comprises an underfloor catalyst provided under the floor of a vehicle and a front catalyst disposed in an exhaust passage between the underfloor catalyst and the combustion chamber and having a smaller capacity than the underfloor catalyst. The in-cylinder injection internal combustion engine according to claim 3, wherein the internal combustion engine is a cylinder injection type internal combustion engine. 13. The in-cylinder injection according to claim 1, wherein the internal combustion engine is configured as a spark ignition type four-cycle internal combustion engine having an ignition means in the combustion chamber. Type internal combustion engine.