JP5991576B2 - Operation control device for internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine having an in-cylinder fuel injection means for directly injecting fuel into a combustion chamber, and relates to an operation control device for an internal combustion engine that performs a catalyst temperature raising operation at the time of cold start.

  2. Description of the Related Art As an internal combustion engine of an automobile, an in-cylinder injection internal combustion engine that has an in-cylinder fuel injection unit that directly injects fuel into a combustion chamber and burns the fuel by spark ignition with an ignition plug is known. In this in-cylinder injection type internal combustion engine, at the time of cold start, that is, at the time of start in a state close to normal temperature, the catalyst temperature raising operation is performed for the purpose of raising the temperature of the catalyst for purifying exhaust gas to the activation temperature at an early stage. . In this catalyst temperature raising operation, fuel is injected into the combustion chamber from the in-cylinder fuel injection means in the latter half of the compression stroke, and the air-fuel ratio becomes a stoichiometric air-fuel ratio or an air-fuel mixture that is slightly leaner than the stoichiometric air-fuel ratio, and burns (for example, Patent Document 1). Thereby, the combustion at the time of starting can be stabilized. For this reason, the retard amount of the ignition timing can be set large. Since the exhaust gas temperature can be increased by setting a large retard amount of the ignition timing, the catalyst can be quickly heated.

JP 2002-235646 A

  However, during normal idle operation, as the cooling water temperature of the internal combustion engine rises, the drivability is taken into consideration, and the rotational speed of the internal combustion engine is reduced. There was a risk of it.

  Therefore, the present invention solves such a problem, and while reducing the exhaust gas amount while improving the drivability while performing the catalyst temperature increasing operation at the cold start, the catalyst is shortened. An object of the present invention is to provide an operation control device for an internal combustion engine capable of raising the temperature over time.

An operation control device for an internal combustion engine according to the present invention that solves the above-described problems is provided.
An internal combustion engine having a catalyst provided in an exhaust gas passage for purifying exhaust gas and in-cylinder fuel injection means for directly injecting fuel into a combustion chamber, wherein the in-cylinder fuel is subjected to a compression stroke of the internal combustion engine during a cold start. In an operation control device for an internal combustion engine for injecting fuel from an injection means into the combustion chamber and performing a catalyst temperature raising operation in which the air-fuel ratio is leaner than the stoichiometric air-fuel ratio or the stoichiometric air-fuel ratio,
Throttle control means for controlling the throttle opening provided in the intake passage of the internal combustion engine, the temperature of the cooling water for cooling the internal combustion engine or the elapsed time from the start of the catalyst temperature raising operation, A rotation speed control means for reducing the rotation speed of the internal combustion engine from the rotation speed of the initial setting value at the time of starting, and the opening / closing timing of at least one of the intake valve and the exhaust valve is changed to change the intake valve and the exhaust valve. Valve timing control means for increasing the valve overlap of the valve opening period more than the valve overlap of the initial set value at the time of starting ,
The rotation speed suppression means and the valve timing control means are configured to perform a decrease control of the rotation speed and an increase control of a valve overlap during the valve opening period from the start of the cooling water at a predetermined temperature or the start of the catalyst heating operation. The throttle control means is carried out after reaching the time, and the throttle control means increases the amount of air by increasing the throttle opening degree in the valve overlap increasing control .

According to the operation control apparatus for an internal combustion engine, the rotation speed control means is provided, and the rotation speed of the internal combustion engine is determined according to the temperature of the cooling water or the elapsed time from the start of the catalyst temperature increase operation during the catalyst temperature increase operation. Since the number is reduced, drivability can be improved.
Furthermore, a valve timing control means is provided, and at the time of the catalyst temperature raising operation, at least one of the intake valve and the exhaust valve according to the temperature of the cooling water or the elapsed time from the start of the operation of the catalyst temperature raising operation. Since the opening / closing timing is changed to increase the valve overlap during the valve opening period of the intake valve and the exhaust valve, it is possible to suppress a decrease in the exhaust gas amount accompanying a decrease in the engine speed. That is, during idle operation, the amount of internal EGR is increased by increasing the valve overlap during the valve opening period of the intake valve and the exhaust valve. Combustion becomes unstable due to the increase in internal EGR. At this time, air (O ₂ ) is made to enter the combustion chamber by increasing the opening of the intake throttle for stable combustion, that is, stable control of engine rotation. Actuating to supply, thereby increasing the intake air amount and consequently the exhaust gas amount. Therefore, it is possible to suppress a decrease in the exhaust gas amount. Thereby, a catalyst can be heated up rapidly.

In the present invention, the rotational speed reduction control and the valve overlap increase control during the valve opening period are performed after the cooling water reaches a predetermined temperature or a predetermined time from the start of the catalyst heating operation. It is characterized by that.

  Thus, after the cooling water reaches a predetermined temperature or a predetermined time from the start of the catalyst heating operation, the engine is started by performing the rotation speed control, intake valve opening / closing timing control and exhaust valve opening / closing timing control. Immediately after that, the combustion becomes unstable due to the increase control of the valve overlap, and the internal combustion engine can be prevented from stopping due to misfire or the like.

The internal combustion engine includes an ignition device that ignites an air-fuel mixture in the combustion chamber, and the operation control device includes an ignition timing control unit that controls an ignition timing of the ignition device, and an in-cylinder fuel injection unit. In-cylinder fuel injection control means for controlling the injection timing and injection amount of the injected fuel,
Control by which the ignition timing control means advances the ignition timing of the ignition device from an initial set value at the start, and control by which the in-cylinder fuel injection control means advances the injection timing from an initial set value at the start At least one of them may be performed after the cooling water reaches a predetermined temperature or a predetermined time from the start of the catalyst heating operation.

In the catalyst heating operation, the initial setting of the injection timing may be set with a large delay. Thereby, the temperature of exhaust gas can be made high. Therefore, the temperature of the catalyst can be raised in a short time. However, if the operation is performed with the same injection timing from immediately after the start of the catalyst temperature increase operation to the end of the catalyst temperature increase operation, there is a problem that the internal combustion engine is not suitable for effective combustion and the fuel consumption is deteriorated. Therefore, after the cooling water reaches a predetermined temperature or a predetermined time from the start of the catalyst heating operation, the fuel consumption can be improved by advancing the injection timing by the in-cylinder fuel injection control means.
Also at the ignition timing, after the cooling water reaches a predetermined temperature or a predetermined time from the start of the catalyst heating operation, the ignition timing is advanced by the ignition timing control means to obtain good combustion and improve fuel efficiency. Can be made.

Further, the internal combustion engine has intake port fuel injection means for injecting fuel into the intake port,
The operation control device includes an intake port fuel injection control means for controlling an injection timing and an injection amount of fuel injected from the intake port fuel injection means, and the intake port fuel injection means for the injection amount of the in-cylinder fuel injection means. And a fuel injection ratio control means for increasing the ratio of the injection amount of the engine from the initial set value at the start,
Control by which the ratio of the injection amount of the intake port fuel injection means to the injection amount of the in-cylinder fuel injection means is increased by the fuel injection ratio control means from the start of operation of the cooling water at a predetermined temperature or the catalyst temperature raising operation. It may be performed after the predetermined time is reached.

As described above, the fuel injection ratio control means is provided, and the fuel injection from the intake port fuel injection means is performed after the cooling water reaches a predetermined temperature or a predetermined time from the start of the catalyst temperature increase operation during the catalyst temperature increase operation. By increasing the ratio of the amount, the fuel vaporized efficiently in the intake port whose temperature has been raised can be supplied to the combustion chamber. That is, vaporization of fuel is promoted by the temperature rise of the intake port over time, combustion efficiency is improved, and fuel consumption can be improved.
Further, the fuel injected into the intake port is uniformly diffused into the air in the intake port. By opening the intake valve in this state, air in which fuel is uniformly diffused can be supplied into the combustion chamber, so that good combustion can be obtained. And by increasing the ratio of the injection amount of the intake port fuel injection means, the ratio of the amount of air in which the fuel is uniformly diffused increases, so that stable combustion is obtained and harmful components in the exhaust gas are reduced. Can do.

  In addition, the intake port fuel injection control means performs control for advancing the injection timing of the intake port fuel injection means with respect to the injection angle of the initial set value at the time of start-up. It is good to carry out after reaching a predetermined time from the start of operation.

  As described above, the intake port fuel injection control means is provided, and the fuel injection timing of the intake port fuel injection means is advanced, so that the time existing in the intake port becomes longer. As a result, it takes a long time for the fuel to vaporize, so that vaporization of the fuel is promoted, and good combustion can be obtained to improve fuel consumption, and harmful components in the exhaust gas can be reduced.

  Further, the fuel injection ratio control means reduces the injection amount of the in-cylinder fuel injection means from an initial set value at the time of starting, whereby the intake port fuel injection means with respect to the injection amount of the in-cylinder fuel injection means. It is good to increase the ratio of the injection amount.

  Thus, the fuel injection ratio control means reduces the injection amount of the in-cylinder fuel injection means from the injection amount of the initial set value at the time of starting, thereby relatively increasing the injection amount of the intake port fuel injection means. be able to. As a result, the air-fuel ratio can be made lean to improve fuel efficiency.

  According to the present invention, an operation control device for an internal combustion engine capable of suppressing the decrease in the amount of exhaust gas while improving the drivability while performing the catalyst temperature increasing operation at the time of cold start, and capable of increasing the temperature of the catalyst in a short time. Can be provided.

1 is a schematic configuration diagram of an internal combustion engine according to a first embodiment of the present invention. 1 is a configuration block diagram of an ECU according to a first embodiment and devices related to the ECU. It is a figure which shows the control flow which concerns on 1st embodiment. It is a figure which shows the flow of the subroutine of the operation control 1 which concerns on 1st embodiment. It is a time chart of ECU which concerns on 1st embodiment, (A) is an engine speed, (B) is exhaust gas amount, (C) is an intake time, (D) is an exhaust time, (E) is a water temperature, ( F) shows a timer counter. It is explanatory drawing for demonstrating the valve overlap angle of the exhaust valve concerning 1st embodiment, and an intake valve. It is a map which shows the relationship between the water temperature W concerning 1st embodiment, and the engine speed Ne. It is a figure which shows the control flow which concerns on 2nd embodiment. It is a figure which shows the flow of the subroutine of the operation control 2 which concerns on 2nd embodiment. It is a time chart of ECU which concerns on 2nd embodiment, (A) is engine speed, (B) is exhaust-gas amount, (C) is ignition timing, (D) is injection timing, (E) is water temperature, ( F) shows a timer counter. It is explanatory drawing for demonstrating the valve overlap angle of the exhaust valve and intake valve which concerns on 2nd embodiment, injection timing, and ignition timing. It is a map of volumetric efficiency. It is a map which shows the relationship between volumetric efficiency and ignition timing. It is an injection time map. It is a figure which shows the control flow which concerns on 3rd embodiment. It is a time chart of ECU which concerns on 3rd embodiment, (A) is an engine speed, (B) is exhaust gas amount, (C) is an intake timing, (D) is an exhaust timing, (E) is an ignition timing, (F) is an injection timing, (G) is a water temperature, and (H) is a timer counter. It is a schematic block diagram of the engine which concerns on 4th embodiment. It is a block diagram of a configuration of an ECU according to a fourth embodiment and devices related to the ECU. It is a figure which shows the control flow which concerns on 4th embodiment. It is a figure which shows the flow of the subroutine of the operation control 3 which concerns on 4th embodiment. It is a time chart of ECU which concerns on 4th embodiment, (A) is MPI ratio, (B) is an intake port fuel-injection-unit injection quantity, (C) is in-cylinder fuel-injection-unit injection quantity, (D) is an air fuel ratio. (E) is the intake port fuel injection means injection timing, (F) is the water temperature, and (G) is the timer counter. It is a figure which shows the control flow which concerns on 5th embodiment. It is a time chart of ECU which concerns on 5th embodiment, (A) is an engine speed, (B) is exhaust-gas amount, (C) is an intake timing, (D) is an exhaust timing, (E) is an ignition timing, (F) is the in-cylinder fuel injection means injection timing, (G) is the MPI ratio, (H) is the intake port fuel injection means injection amount, (I) is the in-cylinder fuel injection means injection amount, (J) is the air-fuel ratio, (K) is the intake port fuel injection means injection timing, (L) is the water temperature, and (M) is the timer counter.

  Hereinafter, an operation control apparatus for an internal combustion engine according to the present invention will be described in detail with reference to the drawings. It should be noted that the dimensions, materials, shapes, relative arrangements, and the like of the components described in the following examples are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative. It is just an example.

<First embodiment>
<Configuration of internal combustion engine and control device>
FIG. 1 is a schematic configuration diagram of an internal combustion engine according to a first embodiment of the present invention. As shown in FIG. 1, the internal combustion engine (hereinafter referred to as the engine 1) is a four-cycle engine, is a spark ignition type, and is configured so that fuel can be directly injected into the combustion chamber 2.

  The cylinder head 3 of the engine 1 is formed with an intake port 7 that is opened and closed by an intake valve 5 and an exhaust port 11 that is opened and closed by an exhaust valve 9. An intake passage 13 and an exhaust passage 15 are connected to the intake port 7 and the exhaust port 11, respectively.

  In addition, an intake valve timing adjustment device 17 and an exhaust valve timing adjustment device 19 that can variably adjust the opening / closing timings of the intake valve 5 and the exhaust valve 9 are provided. The intake valve timing adjustment device 17 and the exhaust valve timing adjustment device 19 adjust the phases of the intake cam shaft and the exhaust cam shaft with respect to a timing pulley connected to the crankshaft 33 via a timing belt (not shown), for example, and the intake valve 5 And the opening / closing timing of the exhaust valve 9 is continuously adjusted.

  The cylinder head 3 is provided with in-cylinder fuel injection means 23 for directly injecting fuel into the combustion chamber 2. In the present embodiment, a fuel injection valve is used as the in-cylinder fuel injection means 23. The in-cylinder fuel injection means 23 is connected to a high-pressure pump 27 provided on the discharge side of the feed pump 25. The fuel is increased in pressure by the high-pressure pump 27 and injected from the in-cylinder fuel injection means 23 as high-pressure fuel.

An ignition device 29 is provided at the center of the top of the combustion chamber 2 of each cylinder of the cylinder head 3. In the present embodiment, a spark plug is used as the ignition device 29.
The cylinder block 4 is also provided with a coolant temperature sensor 31 that detects the coolant temperature of the engine 1 and a crank angle sensor 35 that outputs crank angle information in synchronization with the rotation of the crankshaft 33. Crank angle information from the crank angle sensor 35 is input to an ECU 61, which will be described later, and is used for calculation of engine speed, control of fuel injection timing, control of ignition timing, and the like. Further, an accelerator position sensor (not shown) for detecting the accelerator opening is provided.

  A piston 37 is housed in the cylinder block 4 so as to be able to reciprocate. The piston 37 is connected to the crankshaft 33 via a connecting rod 39. The engine 1 forms a four-cycle operation from operations such as ignition of the ignition device 29, reciprocation of the piston 37, fuel injection from the in-cylinder fuel injection means 23, opening and closing of the intake valve 5 and the exhaust valve 9, and the like. The power obtained at 37 is output from the crankshaft 33.

  An electronic throttle 41, a flow sensor 43, and an air cleaner 45 are provided in the intake passage 13 of the engine 1.

Further, an exhaust gas purification device 47 is provided downstream of the exhaust passage 15. The exhaust gas purifying device 47 is a device that purifies harmful components (CO, unburned HC, NOx, etc.) in the exhaust gas, and has a structure including a three-way catalyst 49. In addition, there is no limitation in the kind of catalyst, It can apply also to a NOx catalyst etc.
An oxygen concentration sensor 51 that detects the concentration of oxygen contained in the exhaust gas is provided on the upstream side of the exhaust gas purification device 47. The amount of oxygen contained in the exhaust gas has a characteristic that its output greatly changes with a theoretical air-fuel ratio (hereinafter referred to as stoichiometric) as a boundary.

  Further, an ECU 61 (corresponding to an operation control device) for controlling the engine 1 is provided. The ECU 61 includes a ROM, a RAM, a CPU, etc. (not shown).

FIG. 2 is a configuration block diagram of the ECU 61 according to the first embodiment and devices related to the ECU 61.
As shown in FIG. 2, the ECU 61 includes a timer counter 63, a rotation speed control means 65, a valve timing control means 67, an ignition timing control means 69, and an in-cylinder fuel injection control means 71.

  The timer counter 63 uses the elapsed time information obtained by measuring the elapsed time from the start of the operation of a later-described compression light lean operation (corresponding to the catalyst temperature raising operation) as a rotational speed control means 65, a valve timing control means 67, and an ignition timing control means 69. And in-cylinder fuel injection control means 71 and the like.

  The rotational speed control means 65 calculates the rotational speed of the engine 1 based on the crank angle information input from the crank angle sensor 35. Further, the rotation speed control means 65 is based on the elapsed time information input from the timer counter 63 and detection information from the coolant temperature sensor 31, accelerator position sensor, flow sensor 43, crank angle sensor 35, and the like. Control the number of revolutions. The rotational speed control means 65 calculates the valve opening angle of the electronic throttle 41 and the fuel injection amount based on a map stored in a memory such as a ROM, and then controls the valve opening angle of the electronic throttle 41 and The injection amount information is output to the in-cylinder fuel injection control means 71.

The valve timing control means 67 calculates the opening / closing timings of the intake valve 5 and the exhaust valve 9 based on the elapsed time information input from the timer counter 63 and the detection information from the crank angle sensor 35 or the like.
The opening / closing timings of the intake valve 5 and the exhaust valve 9 are respectively a map showing the relationship between the elapsed time of the compression slur lean operation and the opening / closing angle of the intake valve 5, and the elapsed time of the compression slur lean operation and the opening / closing angle of the exhaust valve 9. It is calculated based on a map showing the relationship. These maps are stored in advance in a memory such as a ROM.

  The valve timing control means 67 outputs the calculated opening / closing timing information of the intake valve 5 and the exhaust valve 9 to the intake valve timing adjustment device 17 and the exhaust valve timing adjustment device 19, respectively. The intake valve timing adjustment device 17 and the exhaust valve timing adjustment device 19 open and close the intake valve 5 and the exhaust valve 9 based on the opening / closing timing information of the intake valve 5 and the exhaust valve 9 input from the valve timing control means 67.

  The ignition timing control means 69 controls the ignition timing based on the crank angle information input from the crank angle sensor 35, the elapsed time information input from the timer counter 63, and the like. The ignition timing is calculated on the basis of a map indicating the relationship between the elapsed time of the compression sleek lean operation stored in a memory such as a ROM and the ignition timing.

  Further, the in-cylinder fuel injection control means 71 is based on the fuel injection amount information input from the rotation speed control means 65, the detection information from the oxygen concentration sensor 51, etc., and the injection timing and injection amount of the in-cylinder fuel injection means 23. To control. The fuel injection timing is different between the intake stroke injection mode in which fuel is injected during the intake stroke and premixed combustion is performed, and the compression stroke injection mode in which fuel is injected during the compression stroke and stratified combustion is performed. Two modes are provided.

  In the intake stroke injection mode, intake air stoichiometric operation in which the air-fuel ratio is controlled to become stoichiometric using the oxygen concentration detection result by the oxygen concentration sensor 51, and control is performed so that the air-fuel ratio (lean air-fuel ratio) is leaner than stoichiometric. There are provided an intake lean operation for controlling the intake air and an intake rich operation for controlling the air / fuel ratio to be richer than that of stoichiometric.

  Also, in the compression stroke injection mode, a lean air-fuel ratio (A / F = 15 to 16) that is slightly leaner than the compression-lean operation, stoichio or stoichio, which is controlled to become a leaner air-fuel ratio than the intake lean mode. Compressed light lean operation (hereinafter referred to as “compressed S / L operation”) is provided.

Of the above-described operations, the intake stoichiometric operation, the intake lean operation, the intake rich operation, and the compression lean operation are used for fuel injection control during normal times. In such a case, the ECU 61 selects each operation as appropriate according to the operating state of the engine 1 determined by the accelerator opening and the engine speed.
On the other hand, the compression S / L operation is used to quickly raise the temperature of the cold catalyst to the activation temperature immediately after the cold start of the engine 1. In the compression S / L operation, fuel is injected from the in-cylinder fuel injection means 23 immediately after the engine 1 is cold-started. This injection is performed by making the air-fuel ratio leaner than stoichiometric or slightly stoichiometric in the compression stroke. In this air-fuel ratio operation, combustion is extremely stable. Therefore, during the compression S / L operation, the ignition timing control means 69 delays the ignition timing more than usual and retards it to the limit. There is also a setting to increase the temperature. Thereby, the time until the catalyst reaches the activation temperature can be shortened. In order to perform the compression S / L operation, the ECU 61 inputs various information necessary for the compression S / L operation, such as ignition switch start information and coolant temperature information, from the above-described various sensors.
When the compression S / L operation is started, an elapsed time from the start of operation is measured by a timer counter 63 provided in the ECU 61. The elapsed time is output as the elapsed time information.

<Control flow>
Next, a control flow related to the compression S / L operation will be described with reference to FIGS.

  First, as shown in FIG. 3, when the engine 1 is started by turning on the ignition switch of the engine 1, the ECU 61 detects the start of the engine 1 (step S1).

Subsequently, the coolant temperature W of the engine 1, the engine speed Ne, and the valve overlap angle VOL are calculated (step S2).
The coolant temperature W is detected by the coolant temperature sensor 31. Water temperature information of the water temperature W measured by the cooling water temperature sensor 31 (hereinafter simply referred to as the water temperature W) is input from the cooling water temperature sensor 31 to the ECU 61.
The engine speed Ne is calculated based on crank angle information input from the crank angle sensor 35.
The opening / closing timings of the intake valve 5 and the exhaust valve 9 immediately after the engine start are set values that are set based on a map of the operation region of the engine 1 set in advance. Based on the set values of the opening / closing timings of the intake valve 5 and the exhaust valve 9, the valve timing control means 67, as shown in FIG. 6, the valve overlap angle VOL from the intake valve opening timing In to the exhaust valve closing timing Out. Is calculated.

Next, as shown in FIG. 3, the rotational speed control means 65 of the ECU 61 determines whether or not the water temperature W input from the cooling water temperature sensor 31 is equal to or lower than a preset threshold value Wth (step S3). In this embodiment, the threshold value Wth is, for example, 50 ° C., but is not limited to this value.
When the coolant temperature W is higher than the threshold value Wth, it is assumed that the catalyst is sufficiently warmed, and the normal control operation (for example, the above-described intake stoichiometric operation, intake lean operation, intake rich operation, compression lean operation) is performed. ) Is carried out (step S4).

On the other hand, when the coolant temperature W is equal to or lower than the threshold value Wth, it is determined whether or not the engine 1 is already in the compression S / L operation state (step S5).
When the engine 1 is not in the compression S / L operation state, the compression S / L operation is started (step S6).
While starting the compression S / L operation, the rotation speed control means 65, the valve timing control means 67, the ignition timing control means 69, and the in-cylinder fuel injection control means 71 are respectively connected to the engine speed Ne, the valve overlap angle VOL (intake air). Calculated from the valve opening timing In and the exhaust valve closing timing Out), the ignition timing SA, and the fuel injection timing IT, the engine speed Ne1 and the valve overlap of the initial setting values set in advance for idle operation at the cold start The angle VOL1 (calculated from the intake valve opening timing In1 and the exhaust valve closing timing Out1), the ignition timing SA1, and the fuel injection timing IT1 are set.

When the compression S / L operation is started, the engine speed Ne1, the intake valve opening timing In1, the exhaust valve closing timing Out1, the ignition timing SA1, and the fuel injection timing IT1 are held constant (for example, FIG. 5A). FIG. 5C and FIG. 5D). Thereby, as shown in FIG. 5B, the exhaust gas amount is kept constant.
Further, as shown in FIG. 5 (F), while starting the compression S / L operation, the timer counter 63 resets the value of the timer counter 63 to 0 (zero), and the progress of the compression S / L operation has elapsed. Start measuring time.
After the compression S / L operation starts, as shown in FIG. 5E, the water temperature W gradually rises with time.

When the catalyst temperature is low and the purification ability of the exhaust gas purification device 47 is low, such as during cold start, it is more effective to reduce unburned HC by making the air-fuel ratio lean as much as possible within a range where combustion does not deteriorate. The compression stroke injection is faster than the intake stroke injection because of the stratified combustion, has excellent combustion stability, and has good drivability. In the present embodiment, fuel is injected only from the in-cylinder fuel injection means 23 during the compression S / L operation. In addition, the compression stroke injection is performed by controlling the air-fuel ratio to stoichiometric or a slightly lean air-fuel ratio slightly leaner than stoichiometric. In this case, a rich region with a very high fuel concentration and a lean region with a low fuel concentration are formed in the combustion chamber 2 locally. In the rich region, oxygen is insufficient locally, so incomplete combustion (for example, C ₈ H ₁₈ + O ₂ → CO + H ₂ ) occurs, and relatively large amounts of CO and H ₂ are generated. In the lean region, combustion occurs. A large amount of O ₂ that does not contribute to the excess O ₂ exists as surplus O ₂ .
Therefore, by performing the compression S / L operation, reactive CO, H ₂ and surplus O ₂ can be simultaneously supplied to the exhaust gas purification device 47 via the exhaust passage 15. The temperature of the exhaust gas purification device 47 (three-way catalyst 49) is increased by the reaction heat of CO, H ₂ and O ₂ due to the oxidation reaction in the exhaust gas purification device 47.

  By the way, as shown in FIG. 3, when the engine 1 is already in the compression S / L operation state in step S5, the compression S / L operation is continued and step S7 described later is performed.

  Next, in step 7, the timer counter 63 measures the elapsed time from the start of the compression S / L operation. The elapsed time information (hereinafter referred to as elapsed time T) measured by the timer counter 63 is transferred from the timer counter 63 to the rotation speed control means 65, the valve timing control means 67, the ignition timing control means 69, and the in-cylinder fuel injection control means 71. Is output.

The rotation speed control means 65 determines whether or not the elapsed time T input from the timer counter 63 is equal to or longer than a predetermined time Tth1 set in advance (step S8).
The predetermined time Tth1 is a value set in advance by experiments or the like, and is set to 10 seconds in the present embodiment, for example. The value is not limited to this value.
When the elapsed time T is less than the predetermined time Tth1, the engine speed Ne1, the intake valve opening timing In1, the exhaust valve closing timing Out1, the initial setting values preset for idle operation at the time of cold start, ignition, The compression S / L operation is continued while maintaining the state of the timing SA1 and the fuel injection timing IT1. And step S2 is implemented again.

On the other hand, when the elapsed time T is equal to or longer than the predetermined time Tth1, it is determined whether or not the elapsed time T is less than the predetermined time Tend set in advance (step S9).
The predetermined time Tend is an operation time of the compression S / L operation set in advance by an experiment or the like. That is, when the predetermined time Tend has elapsed, the compression S / L operation is terminated. In the present embodiment, the predetermined time Tend is set to 90 seconds, for example. The value is not limited to this value.
When the elapsed time T is equal to or longer than the predetermined time Tend, normal control is performed in step S4, assuming that the compression S / L operation is sufficiently performed and the catalyst is warmed.

On the other hand, when the elapsed time T is less than the predetermined time Tend, the operation control 1 is performed (step S10).
In operation control 1, as shown in FIG. 4, the rotational speed control means 65 determines whether or not the engine rotational speed Ne calculated in step S <b> 2 is larger than a preset threshold value Nth (step S <b> 11). ). The threshold value Nth is a value set in advance by experiments or the like.

When the engine speed Ne is larger than the threshold value Nth, the speed control means 65 calculates a new engine speed Ne by subtracting the predetermined value a from the current engine speed Ne. Subsequently, the rotation of the engine 1 is reduced to a new engine rotation speed Ne (see step S12, FIG. 5A). Thereafter, step S13 described later is performed.
On the other hand, when the engine speed Ne calculated in step 2 is equal to or less than the threshold value Nth, step S13 is subsequently performed without decreasing the engine speed Ne. That is, the engine speed Ne is set so as not to decrease below the threshold value Nth.

  In step S13, the valve timing control means 67 determines whether or not the valve overlap angle VOL calculated in step S2 is less than a preset threshold value VOLth (step S13).

  When the valve overlap angle VOL is less than the threshold value VOLth, the valve timing control means 67 calculates a new valve overlap angle VOL by adding a predetermined value b to the valve overlap angle VOL, and sets the valve overlap. A new valve overlap angle VOL is set (step S14). Specifically, as shown in FIGS. 5C and 5D, the intake valve opening timing In is advanced and the exhaust valve closing timing Out is retarded. In the present embodiment, the advance angle of the intake valve opening timing In and the retard angle of the exhaust valve closing timing Out are set to, for example, b / 2. The advance angle of the intake valve opening timing In and the retard angle of the exhaust valve closing timing Out are not limited to the same value, and may be different values. For example, the advance angle of the intake valve opening timing In and the retard angle of the exhaust valve closing timing Out may be set to b / 3 and 2b / 3, respectively.

When the valve overlap angle VOL is increased, the amount of internal EGR increases and combustion becomes unstable. At this time, the ECU 61 operates to supply air (O ₂ ) to the combustion chamber 2 by increasing the opening of the electronic throttle 41 for stable combustion, that is, stable control of engine rotation. As a result, the intake air amount increases, and as a result, the exhaust gas amount also increases.

By reducing the engine speed Ne in step S12, the exhaust gas amount is reduced. In step S14, the exhaust gas amount is increased by increasing the valve overlap angle VOL. As a result, a significant decrease in the amount of exhaust gas can be suppressed (see FIG. 5B).
In consideration of drivability, a decrease in exhaust gas amount due to an increase in the water temperature W and a decrease in the engine speed Ne can be suppressed by increasing the valve overlap angle VOL. The temperature increase effect of the original catalyst 49) can be maintained.

In the present embodiment, the case where the intake valve opening timing In and the exhaust valve closing timing Out are both moved in step S14 has been described. However, the present invention is not limited to this, and the intake valve opening timing In and the exhaust valve are not limited thereto. Only one of the valve closing times Out may be moved.
Step S2 (see FIG. 3) is performed after step S14.

  In step S13, when the valve overlap angle VOL is equal to or greater than the threshold value VOLth, step S2 is performed without increasing the valve overlap angle VOL. That is, the valve overlap angle VOL is set so as not to be larger than the threshold value VOLth.

<Effect>
According to the first embodiment described above, the rotational speed control means 65 is provided, and the drivability at the cold start is reduced by decreasing the engine rotational speed Ne after a predetermined time Tth1 of the compression S / L operation. Can be improved.

  Further, a valve timing control means 67 is provided, and after a predetermined time Tth1 of the compression S / L operation has elapsed, the opening / closing timing of at least one of the intake valve 5 and the exhaust valve 9 is changed to change the intake valve 5 and the exhaust valve. By increasing the valve overlap angle VOL with 9, the reduction of the exhaust gas amount can be suppressed. Therefore, the temperature of the exhaust gas purification device 47 (three-way catalyst 49) can be quickly raised.

  Further, after the compression S / L operation reaches the predetermined time Tth1, the engine speed Ne, the intake valve 5 opening / closing timing control, and the exhaust valve 9 opening / closing timing control are performed. Can be prevented from stopping.

  In the present embodiment, the case where the new engine speed Ne is calculated by subtracting the predetermined value a from the current engine speed Ne in step S12 is not limited to this. For example, as shown in FIG. 7, a new engine speed Ne may be calculated based on a map indicating the relationship between the water temperature W and the engine speed Ne acquired in advance through experiments or the like.

<Second embodiment>
Next, a second embodiment of the present invention will be described. In the following description, portions corresponding to those of the first embodiment described above are denoted by the same reference numerals, description thereof is omitted, and differences are mainly described. In the operation control of the second embodiment, when the compression S / L operation has elapsed for a predetermined time Tth1, in addition to the operation control 1 described in the first embodiment, the injection timing and ignition timing of the in-cylinder fuel injection means 23 are advanced. It is something to be made.

<Control flow>
A control flow related to the compression S / L operation according to the present embodiment will be described with reference to FIGS.

  First, as shown in FIG. 8, the ignition switch of the engine 1 is turned on to start the engine 1 (step S1).

Then, the coolant temperature W, the engine speed Ne, the valve overlap angle VOL, the ignition timing SA, and the fuel injection timing IT are calculated (step S2 ′).
The ignition timing SA and the fuel injection timing IT immediately after the start are set values that are set based on a map of the operation region of the engine 1 that is set in advance. The ignition timing control means 69 and the in-cylinder fuel injection control means 71 calculate the ignition timing SA and the fuel injection timing IT from each map.
Next, similarly to the first embodiment, steps S3 to S10 are performed.

Thereafter, operation control 2 is performed (step S20).
In operation control # 2, as shown in FIG. 9, the ignition timing control means 69 determines whether the ignition timing SA calculated in step S2 'is greater (retarded) than a preset threshold value SAth. It is determined whether or not (step S21). The threshold value SAth is a value set in advance by experiments or the like.

When the ignition timing SA is larger than the threshold value SAth, the ignition timing control means 69 calculates a new ignition timing SA by subtracting (advancing) the predetermined value c from the current ignition timing SA. Subsequently, as shown in FIGS. 10C and 11, the ignition timing is advanced to a new ignition timing SA (step S22). Thereafter, step S23 described later is performed.
On the other hand, if the ignition timing SA calculated in step S2 ′ is equal to or less than the threshold value SAth in step S21, step S23 is subsequently performed without advancing the ignition timing SA. That is, the ignition timing SA is set so as not to advance more than the threshold value SAth.

  In step S23, the in-cylinder fuel injection control means 71 determines whether or not the fuel injection timing IT calculated in step S2 ′ is greater than a preset threshold ITth (step S23). The threshold value ITth is a value set in advance by experiments or the like.

When the fuel injection timing IT is larger (retarded) than the threshold ITth, the in-cylinder fuel injection control means 71 subtracts the predetermined value d from the current fuel injection timing IT (advances). A) A new fuel injection timing IT is calculated. Subsequently, as shown in FIGS. 10D and 11, the fuel injection timing is advanced to a new fuel injection timing IT (step S24). Thereafter, step S2 ′ is performed again.
On the other hand, if the fuel injection timing IT calculated in step S2 ′ is equal to or less than the threshold ITth in step S23, step S2 ′ is subsequently performed without advancing the fuel injection timing IT. That is, the fuel injection timing IT is set so as not to advance more than the threshold value ITth.

<Effect>
According to the second embodiment described above, the in-cylinder fuel injection control means 71 is provided, and fuel efficiency can be improved by advancing the fuel injection timing IT after a predetermined time Tth1 of the compression S / L operation has elapsed. it can.
Further, an ignition timing control means 69 is provided, and after a predetermined time Tth1 of the compression S / L operation, the ignition timing SA is advanced to obtain good combustion to raise the temperature of the catalyst and improve fuel efficiency. be able to.
Furthermore, also in this embodiment, the same effect as 1st embodiment can be acquired.

  In the present embodiment, the case where the new ignition timing SA is calculated by subtracting the predetermined value c from the current ignition timing SA in step S22 is not limited to this. For example, The volumetric efficiency V is calculated from the volumetric efficiency map shown in FIG. 12 based on the coolant temperature W and the engine speed Ne calculated in step S2 ′, and then the relationship between the volumetric efficiency and ignition timing shown in FIG. The ignition timing SA corresponding to the volumetric efficiency V may be calculated from the map indicating the new ignition timing SA. A volume efficiency map and a map indicating the relationship between the volume efficiency and the ignition timing are stored in advance in a memory such as a ROM.

  In the present embodiment, the case where the new fuel injection timing IT is calculated by subtracting the predetermined value d from the current fuel injection timing IT in step S24 is not limited to this. For example, the injection angle may be calculated from the injection timing map shown in FIG. 14 based on the coolant temperature W and the engine speed Ne calculated in step S2 ′, and set as the new fuel injection timing IT. The injection timing map is stored in advance in a memory such as a ROM.

<Third embodiment>
Next, a third embodiment of the present invention will be described. In the operation control of the third embodiment, when the predetermined time Tth1 has elapsed for the compression S / L operation, the operation control 1 is performed. When the predetermined time Tth2 (> Tth1) has elapsed for the compression S / L operation, the operation control 2 is performed. In addition, it will be implemented.

<Control flow>
Next, a control flow related to the compression S / L operation according to the present embodiment will be described with reference to FIGS. 15 and 16.

  First, as shown in FIG. 15, steps S1 to S10 are performed in the same manner as in the second embodiment.

Next, the rotation speed control means 65 determines whether or not the elapsed time T input from the timer counter 63 is equal to or longer than a predetermined time Tth2 set in advance (step S15).
The predetermined time Tth2 is a value set in advance by experiments or the like, and is set to 20 seconds, for example, in the present embodiment. The value is not limited to this value.
If the elapsed time T is less than the predetermined time Tth2, step S2 ′ is performed again.
On the other hand, when the elapsed time T is equal to or longer than the predetermined time Tth2, as shown in FIGS. 16E and 16F, the operation control 2 is performed in addition to the operation control 1 (step S20). . In addition, the control content of operation control 2 is the same as that of 2nd embodiment.

<Effect>
According to the third embodiment described above, since the operation control 1 is performed after the elapse of the predetermined time Tth1, the drivability due to the decrease in the engine speed Ne can be reliably improved.
Then, after the predetermined time Tth2 has elapsed, the operation control No. 2 is further performed, so that the temperature of the exhaust gas purification device 47 can be raised efficiently with good fuel efficiency while stably maintaining the engine speed Ne at the time of startup.
In addition, also in this embodiment, the same effect as 1st embodiment and 2nd embodiment can be acquired.

<Fourth embodiment>
Next, a fourth embodiment of the present invention will be described.
The engine of the fourth embodiment includes intake port fuel injection means for injecting fuel into the intake port 7, and fuel is injected from the intake port fuel injection means and the in-cylinder fuel injection means 23.

FIG. 17 is a schematic configuration diagram of an engine 81 according to the fourth embodiment. FIG. 18 is a configuration block diagram of the ECU 82 of the engine 81 and devices related to the ECU 82 according to the present embodiment.
As shown in FIGS. 17 and 18, the engine 81 further includes intake port fuel injection means 83 that injects fuel into the intake port 7. The intake port fuel injection means 83 is connected to the fuel tank via the feed pump 25 in the fuel tank 24. As the fuel in the fuel tank, the fuel pumped by the feed pump 25 is directly injected from the intake port fuel injection means 83.

The ECU 82 further includes intake port fuel injection control means 85 and fuel injection ratio control means 87.
Based on the fuel injection amount input from the rotation speed control means 65, the detection information input from the oxygen concentration sensor 51, the crank angle information input from the crank angle sensor 35, etc., the fuel injection ratio control means 87 The ratio of the injection amount of the intake port fuel injection means 83 to the injection amount of the fuel injection means 23 is calculated, and the injection amounts of the in-cylinder fuel injection means 23 and the intake port fuel injection means 83 are calculated. Thereafter, the fuel injection ratio control means 87 outputs the calculated injection amount information of the in-cylinder fuel injection means 23 and the intake port fuel injection means 83 to the in-cylinder fuel injection control means 71 and the intake port fuel injection control means 85, respectively.
The intake port fuel injection control means 85 controls the fuel injection amount and injection timing of the intake port fuel injection means 83 based on the inputted fuel injection amount information and crank angle information.
Further, the in-cylinder fuel injection control means 71 controls the fuel injection amount and the injection timing of the in-cylinder fuel injection means 23 based on the inputted fuel injection amount information, crank angle information, and the like.

<Control flow>
Next, a control flow related to the compression S / L operation according to the present embodiment will be described with reference to FIGS. 19 and 20.

  First, as shown in FIG. 19, the ignition switch of the engine 81 is turned on to start the engine 81 (step S1).

Then, the coolant temperature W, the engine speed Ne, the valve overlap angle VOL, the ignition timing SA, the fuel injection timing IT of the in-cylinder fuel injection means 23, the fuel injection timing MPIT of the intake port fuel injection means 83, and the fuel injection ratio (Hereinafter referred to as MPI ratio RA) and the air-fuel ratio A / F are calculated (step S2 ″).
In this specification, the MPI ratio RA is the ratio of the fuel injection amount from the intake port fuel injection means 83 to the fuel injection amount from the in-cylinder fuel injection means 23.

The fuel injection timings IT and MPIT of the in-cylinder fuel injection means 23 and the intake port fuel injection means 83 immediately after the start are set according to each map of the compression S / L operation region, and the in-cylinder fuel injection control means 71 and The intake port fuel injection control means 85 calculates the fuel injection timing IT and MPIT by reading each map.
Further, the MPI ratio RA and the air-fuel ratio A / F immediately after start-up are set according to the respective maps in the compression S / L operation region, and the fuel injection ratio control means 87 reads the respective maps to read the MPI ratio. RA and air-fuel ratio A / F are calculated.

Next, similarly to the second embodiment, steps S3 to S20 are performed.
In step S6, when the compression S / L operation is started, the fuel injection timing MPIT, the MPI ratio RA, and the air-fuel ratio A / F of the intake port fuel injection means 83 are set in advance for idle operation at the time of cold start. The fuel injection timing MPIT1, the MPI ratio RA1, and the air-fuel ratio A / F1 are set as initial setting values.

Thereafter, operation control 3 is performed (step S30).
In operation control # 3, as shown in FIG. 20, the ECU 61 calculates a time difference ΔT by subtracting a predetermined time Tth1 from the elapsed time T measured by the timer counter 63, and the time difference ΔT is set in advance. It is determined whether or not the time difference is less than ΔTth (step S31).
The time difference ΔTth is a value set in advance by an experiment or the like, and is set to, for example, 10 seconds in this embodiment. The value is not limited to this value.
When the time difference ΔT is less than the time difference ΔTth, step S32 described later is performed.

  Next, in step S32, the fuel injection ratio control means 87 determines whether or not the MPI ratio RA calculated in step S2 ″ is less than a preset threshold value RAth. The threshold value RAth is a value set in advance through experiments or the like.

When the MPI ratio RA is less than the threshold value RAth, the fuel injection ratio control unit 87 calculates a new MPI ratio RA by adding a predetermined value e to the current MPI ratio RA (step S33). Subsequently, the injection amounts of the intake port fuel injection means 83 and the in-cylinder fuel injection means 23 are determined so as to obtain a new MPI ratio RA.
Specifically, as shown in FIGS. 21A to 21C, the injection amount from the intake port fuel injection means 83 is increased and the injection amount from the in-cylinder fuel injection means 23 is decreased. A new MPI ratio RA is assumed. At this time, the injection amount from the intake port fuel injection means 83 increases, but the injection amount from the in-cylinder fuel injection means 23 decreases, so the air-fuel ratio A / F does not change. Then, step S2 is implemented.
On the other hand, if the MPI ratio RA calculated in step S2 ″ is greater than or equal to the threshold RAth in step S32, step S2 ″ is performed again without changing the MPI ratio RA. That is, the MPI ratio RA is set so as not to be larger than the threshold value RAth.

  By the way, when the time difference ΔT is greater than or equal to the time difference ΔTth in step S31, step S34 is performed.

  In step S34, the fuel injection ratio control means 87 determines whether or not the air-fuel ratio A / F calculated in step S2 ″ is less than a preset threshold A / Fth. The threshold value A / Fth is a value set in advance through experiments or the like.

When the air-fuel ratio A / F is less than the threshold value A / Fth, the fuel injection ratio control means 87 calculates a new air-fuel ratio A / F by adding a predetermined value f to the current air-fuel ratio A / F. (Step S35). Subsequently, as shown in FIGS. 21 (B) to 21 (D), the air-fuel ratio A / F is decreased by decreasing the injection amount of the in-cylinder fuel injection means 23 while keeping the injection amount of the intake port fuel injection means 83 as it is. To make it lean. Thereafter, step S36 described later is performed.
On the other hand, if the air-fuel ratio A / F is greater than or equal to the threshold value A / Fth in step S34, the air-fuel ratio A / F is maintained as it is without leaning. That is, the air-fuel ratio A / F is set so as not to become leaner than the threshold value FAth. Thereafter, step S36 described later is performed.

  In step S36, the intake port fuel injection control means 85 determines whether or not the fuel injection timing MPIT calculated in step S2 ″ is greater than a preset threshold value MPITth. The threshold value MPITth is a value set in advance by experiments or the like.

When the fuel injection timing MPIT is larger (retarded) than the threshold value MPITth, the intake port fuel injection control means 85 subtracts the predetermined value g from the current fuel injection timing MPIT (advances). A) A new fuel injection timing MPIT is calculated. Subsequently, as shown in FIG. 21E, the injection timing of the intake port fuel injection means 83 is advanced to a new fuel injection timing MPIT (step S37). Thereafter, Step S2 ″ is performed again.
On the other hand, if the fuel injection timing MPIT is equal to or less than the threshold value MPITth in step S36, the fuel injection timing MPIT is held as it is without advancing the fuel injection timing MPIT. That is, the fuel injection timing MPIT is set so as not to advance more than the threshold value MPITth. Thereafter, Step S2 ″ is performed.

<Effect>
According to the fourth embodiment described above, the fuel injection ratio control means 87 is provided, and the injection amount of the intake port fuel injection means 83 is increased after the predetermined time Tth1 of the compression S / L operation has elapsed (that is, the MPI ratio RA is increased). ), The fuel vaporized efficiently in the intake port 7 whose temperature has been raised can be supplied to the combustion chamber 2. That is, vaporization of the fuel is promoted by the temperature rise of the intake port 7 over time, so that the combustion efficiency is improved and the fuel consumption can be improved.

  Further, the fuel injected into the intake port 7 is uniformly diffused into the air in the intake port 7. Since the intake valve 5 is opened in this state, air in which fuel is uniformly diffused can be supplied into the combustion chamber 2, so that good combustion can be obtained. And by increasing the ratio of the injection amount of the intake port fuel injection means 83, the ratio of the amount of air in which the fuel is uniformly diffused increases, so that stable combustion is obtained and harmful components in the exhaust gas are reduced. be able to.

  When the injection amount of the in-cylinder fuel injection means 23 is reduced below the injection amount at the time of cold start, the injection amount of the intake port fuel injection means 83 can be relatively increased. As a result, the air-fuel ratio A / F becomes lean and good combustion can be obtained. Furthermore, since good combustion can be stably obtained without increasing the total supply amount of fuel, fuel efficiency can be improved.

Further, the intake port fuel injection control means 85 is provided, and after the predetermined time Tth1 of the compression S / L operation has elapsed, the fuel injection timing MPIT of the intake port fuel injection means 83 is advanced to obtain good combustion and discharge. The temperature of the gas can be raised.
In addition, also in this embodiment, the same effect as 1st embodiment and 2nd embodiment can be acquired.

<Fifth embodiment>
Next, a fifth embodiment of the present invention will be described. In the operation control of the fifth embodiment, when the predetermined time Tth1 has elapsed for the compression S / L operation, the operation control 1 is performed, and when the predetermined time Tth2 (> Tth1) has elapsed for the compression S / L operation, the operation control 2 is performed. Further, when the compression S / L operation is performed for a predetermined time Tth3 (> Tth2), operation control 3 is further executed.

<Control flow>
Next, a control flow related to the compression S / L operation according to the present embodiment will be described with reference to FIGS.

  First, as shown in FIG. 22, steps S1 to S6 are performed in the same manner as in the fourth embodiment. Subsequently, Steps S7 to S20 are performed in the same manner as in the third embodiment.

Thereafter, the rotational speed control means 65 determines whether or not the elapsed time T is equal to or longer than a predetermined time Tth3 set in advance (step S25).
The predetermined time Tth3 is a value set in advance by experiments or the like, and is set to 30 seconds, for example, in the present embodiment. The value is not limited to this value.
If the elapsed time T is less than the predetermined time Tth3, step S2 ″ is performed again.
On the other hand, when the elapsed time T is equal to or longer than the predetermined time Tth3, as shown in FIGS. 23 (G) to 23 (K), the operation control 3 is further performed (step S30). The control content of operation control 3 is the same as that of the fourth embodiment.

<Effect>
According to the fifth embodiment described above, since the operation control 1 is performed after the predetermined time Tth1 has elapsed, the drivability due to the decrease in the engine speed Ne can be reliably improved.
Then, after the predetermined time Tth2 has elapsed, the operation control No. 2 is further performed, so that the temperature of the exhaust gas purification device 47 can be raised efficiently with good fuel efficiency while stably maintaining the engine speed Ne at the time of startup.
Furthermore, after the predetermined time Tth3 has elapsed, since the operation control 3 is further performed, it is possible to improve fuel efficiency while stably maintaining the engine speed Ne at the start.
In this embodiment, the same effects as those of the first embodiment, the third embodiment, and the fourth embodiment can be obtained.

  Although description is omitted in this specification, the operation control 1 and the operation control 3 may be performed almost simultaneously after the compression S / L operation has elapsed for a predetermined time Th1.

  In each of the above-described embodiments, the case where the operation control No. 1, No. 2, and No. 3 are performed after the compression S / L operation has passed the predetermined time Tth1, the predetermined time Tth2, and the predetermined time Tth3 has been described. However, the present invention is not limited to this, and after the water temperature W becomes equal to or higher than the predetermined temperature Wth1, the predetermined temperature Wth2, and the predetermined temperature Wth3, the operation control Nos. 1, 2, and 3 may be performed.

  The present invention can be applied to a case where the exhaust gas temperature is raised in a short time in an internal combustion engine that performs a catalyst temperature raising operation during cold start.

1 Engine 2 Combustion chamber 3 Cylinder head 4 Cylinder block 5 Intake valve 7 Intake port 9 Exhaust valve 11 Exhaust port 13 Intake passage 15 Exhaust passage 17 Intake valve timing adjustment device 19 Exhaust valve timing adjustment device 23 In-cylinder fuel injection means 24 Fuel tank 25 Feed pump 27 High pressure pump 29 Ignition device 31 Cooling water temperature sensor 33 Crankshaft 35 Crank angle sensor 37 Piston 39 Connecting rod 41 Electronic throttle 43 Flow sensor 45 Air cleaner 47 Exhaust gas purification device 49 Three-way catalyst 51 Oxygen concentration sensor 61 ECU
63 Timer counter 65 Rotational speed control means 67 Valve timing control means 69 Ignition timing control means 71 In-cylinder fuel injection control means 81 Engine 82 ECU
83 Intake port fuel injection means 85 Intake port fuel injection control means 87 Fuel injection ratio control means

Claims (5)

An internal combustion engine having a catalyst provided in an exhaust gas passage for purifying exhaust gas and in-cylinder fuel injection means for directly injecting fuel into a combustion chamber, wherein the in-cylinder fuel is subjected to a compression stroke of the internal combustion engine during a cold start. In an operation control device for an internal combustion engine for injecting fuel from an injection means into the combustion chamber and performing a catalyst temperature raising operation in which the air-fuel ratio is leaner than the stoichiometric air-fuel ratio or the stoichiometric air-fuel ratio,
Throttle control means for controlling the throttle opening provided in the intake passage of the internal combustion engine, the temperature of the cooling water for cooling the internal combustion engine or the elapsed time from the start of the catalyst temperature raising operation, A rotation speed control means for reducing the rotation speed of the internal combustion engine from the rotation speed of the initial setting value at the time of starting, and the opening / closing timing of at least one of the intake valve and the exhaust valve is changed to change the intake valve and the exhaust valve. Valve timing control means for increasing the valve overlap of the valve opening period more than the valve overlap of the initial set value at the time of starting ,
The rotation speed suppression means and the valve timing control means are configured to perform a decrease control of the rotation speed and an increase control of a valve overlap during the valve opening period from the start of the cooling water at a predetermined temperature or the start of the catalyst heating operation. Carried out after the time,
The operation control device for an internal combustion engine, wherein the throttle control means increases the amount of air by increasing the opening of the throttle during the valve overlap increase control . The internal combustion engine has an ignition device that ignites an air-fuel mixture in the combustion chamber,
The operation control device includes: an ignition timing control unit that controls an ignition timing of the ignition device; and an in-cylinder fuel injection control unit that controls an injection timing and an injection amount of fuel injected from the in-cylinder fuel injection unit. In addition,
Control by which the ignition timing control means advances the ignition timing of the ignition device from an initial set value at the start, and control by which the in-cylinder fuel injection control means advances the injection timing from an initial set value at the start operation controller for an internal combustion engine according to at least one, in claim 1, wherein the cooling water which comprises carrying out after a predetermined time after operation start of the operation a predetermined temperature or the catalyst Atsushi Nobori of the. The internal combustion engine has intake port fuel injection means for injecting fuel into the intake port,
The operation control device includes an intake port fuel injection control means for controlling an injection timing and an injection amount of fuel injected from the intake port fuel injection means, and the intake port fuel injection means for the injection amount of the in-cylinder fuel injection means. And a fuel injection ratio control means for increasing the ratio of the injection amount of the engine from the initial set value at the start,
Control by which the ratio of the injection amount of the intake port fuel injection means to the injection amount of the in-cylinder fuel injection means is increased by the fuel injection ratio control means from the start of operation of the cooling water at a predetermined temperature or the catalyst temperature raising operation. 3. The operation control device for an internal combustion engine according to claim 1 , wherein the operation control device is implemented after a predetermined time has been reached. 4. The internal combustion engine according to claim 3 , wherein the intake port fuel injection control means performs control to advance an injection timing of the intake port fuel injection means with respect to an injection angle of an initial set value at start-up. Operation control device. The fuel injection ratio control means reduces the injection amount of the in-cylinder fuel injection means from an initial set value at the time of start, thereby causing the injection amount of the intake port fuel injection means to be relative to the injection amount of the in-cylinder fuel injection means. The operation control device for an internal combustion engine according to claim 3 , wherein the ratio is increased.

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