JP5896292B2 - Operation control device for internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine provided with an in-cylinder fuel injection means for directly injecting fuel into a combustion chamber and an intake port fuel injection means for injecting fuel into an intake port, and a catalyst temperature increasing operation at a cold start The present invention relates to an operation control device for an internal combustion engine.

  2. Description of the Related Art In general, an internal combustion engine of an automobile is known that includes an in-cylinder fuel injection unit that directly injects fuel into a combustion chamber and an intake port fuel injection unit that injects fuel into an intake port. In this internal combustion engine, at the time of cold start, that is, at the time of start in a state close to normal temperature, a catalyst temperature raising operation is performed for the purpose of quickly raising the temperature of the catalyst for purifying exhaust gas to the activation temperature. In the catalyst temperature rising operation, fuel is injected into the intake port from the intake port fuel injection means in the expansion to intake process, and fuel is injected into the combustion chamber from the in-cylinder fuel injection means in the latter half of the compression stroke, so that the air-fuel ratio is theoretical. The air-fuel ratio or the air-fuel mixture that is slightly leaner than the stoichiometric air-fuel ratio is combusted (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. By setting the retard amount of the ignition timing to be large, the exhaust gas temperature can be increased, and the catalyst can be quickly heated.

JP 2011-202568 A

When the catalyst temperature raising operation is performed, the temperature of the internal combustion engine rises with time. Since the volatility of the fuel injected into the combustion chamber of the internal combustion engine varies depending on the temperature of the internal combustion engine, it is unnecessary to make the operating conditions such as the fuel injection amount and the injection timing constant during the catalyst temperature raising operation. Will continue to inject fuel. Therefore, there has been a problem that fuel consumption is deteriorated.
In addition, when the fuel injection ratio from the in-cylinder fuel injection means increases, the air-fuel ratio of the stratified portion formed around the ignition device becomes rich, combustion deteriorates and smoke is generated, or PN (particulate number) Or increase.

  Accordingly, the present invention provides an operation control device for an internal combustion engine that solves such a problem and can improve fuel efficiency while achieving good combustion while performing a catalyst temperature raising operation during cold start. The purpose is to do.

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 for purifying exhaust gas provided in an exhaust gas passage, in-cylinder fuel injection means for directly injecting fuel into a combustion chamber, and intake port fuel injection means for injecting fuel into an intake port, An internal combustion engine that performs a catalyst heating operation in which the air-fuel ratio is leaner than the stoichiometric air-fuel ratio or the stoichiometric air-fuel ratio by injecting fuel into the combustion chamber from the in-cylinder fuel injection means during the compression stroke of the internal combustion engine at the cold start In the operation control device of
In-cylinder fuel injection control means for controlling the injection timing and amount of fuel injected from the in-cylinder fuel injection means;
Intake port fuel injection control means for controlling the injection timing and injection amount of fuel injected from the intake port fuel injection means;
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 started according to 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 fuel injection ratio control means for increasing the ratio of the initial setting value at the time ,
The fuel injection ratio control means determines the injection amount of the intake port fuel injection means relative to the injection amount of the in-cylinder fuel injection means until the cooling water reaches a predetermined temperature or a predetermined time from the start of the catalyst temperature raising operation. The initial set value is kept constant as a ratio, and control is performed to increase the ratio of the injection amount after the cooling water reaches the predetermined temperature or the predetermined time from the start of the catalyst heating operation. Features.

According to the operation control apparatus for an internal combustion engine, the fuel injection ratio control means is provided, and the intake port according to the temperature of the cooling water or the elapsed time from the start of the operation of the catalyst temperature increase operation during the catalyst temperature increase operation. By increasing the ratio of the fuel injection amount from the fuel injection means, 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 control for increasing the ratio of the injection amount of the intake port fuel injection means to the injection amount of the in-cylinder fuel injection means has reached a predetermined time from the start of the operation of the catalyst temperature raising operation or the cooling water. To be implemented later .

  As described above, after the cooling water reaches a predetermined temperature or a predetermined time from the start of the catalyst heating operation, the control is performed to increase the ratio of the injection amount of the intake port fuel injection means to the injection amount of the in-cylinder fuel injection means. By doing so, it becomes possible to prevent combustion from becoming unstable immediately after starting and stopping the internal combustion engine due to misfire or the like.

Further, the intake port fuel injection control means has a time difference calculated in advance by subtracting the predetermined time from an elapsed time measured after the start of the catalyst temperature raising operation after the predetermined time is reached. When the time difference is greater than or equal to the set time difference, it is preferable to perform control to advance the injection timing of the intake port fuel injection means from the injection angle of the initial set value at the start.

  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 the injection amount of the initial set value at the time of starting, whereby the intake port fuel with respect to the injection amount of the in-cylinder fuel injection means The ratio of the injection amount of the injection means may be increased.

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.
Further, the fuel injection ratio control means sets in advance a time difference calculated by subtracting the predetermined time from the elapsed time measured after the start of the catalyst temperature raising operation after the predetermined time has been reached. If the time difference is greater than or equal to the time difference, the air-fuel ratio may be made lean by decreasing the injection amount of the in-cylinder fuel injection means while maintaining the injection amount of the intake port fuel injection means.

  ADVANTAGE OF THE INVENTION According to this invention, the operation control apparatus of the internal combustion engine which can improve a fuel consumption, aiming at favorable combustion, implementing a catalyst temperature rising operation at the time of cold start can be provided.

1 is a schematic configuration diagram of an engine according to a first embodiment. 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 MPI ratio, (B) is an intake port fuel-injection means injection amount, (C) is in-cylinder fuel-injection means injection amount, (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 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 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 time chart of ECU which concerns on 2nd 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. It is a figure which shows the flow of the subroutine of the operation control 3 which concerns on 2nd embodiment. It is a map which shows the relationship between the water temperature W and the engine speed Ne. 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.

  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 in the fuel tank 24. 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.
Further, the cylinder head 3 is provided with intake port fuel injection means 83 for injecting fuel into the intake port 7. The intake port fuel injection means 83 is connected to the fuel tank via the feed pump 25. 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.

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. Then, the engine 1 performs four cycles 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 and the intake port fuel injection means 83, opening and closing of the intake valve 5 and the exhaust valve 9. Power is obtained from the piston 37 and is output from the crankshaft 33 to form an operation.

  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, an in-cylinder fuel injection control means 71, and an intake port fuel injection control. Means 85 and fuel injection ratio control means 87 are provided.

  The timer counter 63 uses the elapsed time information obtained by measuring the elapsed time from the start of the compression-slight lean operation (corresponding to the catalyst temperature raising operation) as the rotational speed control means 65, the valve timing control means 67, the ignition timing control means 69, and the cylinder. Output to the internal fuel injection control means 71, the intake port fuel injection control means 85, the fuel injection ratio control means 87, and the like. In the present specification, the operation of injecting fuel in the compression stroke while setting the stoichiometric air-fuel ratio (A / F = 15 to 16) slightly leaner than stoichio or stoichio is referred to as the compression-slight lean operation (hereinafter referred to as compression S / L). L driving).

  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 and the intake port fuel injection control means 85.

  The valve timing control means 67 determines the relationship between the elapsed time information input from the timer counter 63, the detection information from the crank angle sensor 35, the preset elapsed time of the compression S / L operation, and the opening / closing angle of the intake valve 5. The opening / closing timings of the intake valve 5 and the exhaust valve 9 are respectively calculated based on the map shown and the map showing the relationship between the preset elapsed time of the compression S / L operation and the opening / closing angle of the exhaust valve 9. 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, respectively. .

  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.

  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.

In the ECU 61 according to the present embodiment, a normal mode is set in which the in-cylinder fuel injection means 23 and the intake port fuel injection means 83 are injected in accordance with the operating state of the engine 1. This normal mode is composed of three types of injection modes at an extremely low load, a low / medium load, and a high load.
Specifically, it has an injection mode in which low-pressure fuel is injected in the expansion stroke only from the intake port fuel injection means 83 at an extremely low load.
Further, at the time of low and medium load, in the split injection mode divided into the in-cylinder fuel injection means 23 and the intake port fuel injection means 83, the fuel injection ratio control means 87 changes the injection ratio in accordance with the load while the expansion stroke to the intake stroke. There is an injection mode in which fuel is injected from the intake port fuel injection means 83 and fuel is injected from the in-cylinder fuel injection means 23 in the intake stroke to the compression stroke.
And it has the injection mode which injects high pressure fuel only by the in-cylinder fuel injection means 23 at an exhaust stroke-intake stroke at the time of high load.
These injection modes are selected by the ECU 61 according to a map of the operation region of the engine 1 stored in advance in a memory such as a ROM.

  In the present embodiment, the ECU 61 selects the split injection mode when performing the compression S / L operation. When the ECU 61 selects the compression S / L operation, the injection timing of the in-cylinder fuel injection control means 71 and the intake port fuel injection means 85 is set so that the fuel injection ratio control means 87 causes the air-fuel ratio to become slightly leaner than stoichiometric or stoichiometric. And the injection amount are set.

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 unit 23 and the intake port fuel injection unit 83 immediately after the cold start of the engine 1. 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, 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). The air / fuel ratio A / F is 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 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 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, 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, the catalyst is sufficiently warmed and normal control operation is performed (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).
In addition to starting the compression S / L operation, the in-cylinder fuel injection control means 71, the intake port fuel injection control means 85, and the fuel injection ratio control means 87 are respectively connected to the fuel injection timing IT and the intake port fuel of the in-cylinder fuel injection means 23. Regarding the fuel injection timing MPIT, the MPI ratio RA, and the air-fuel ratio A / F of the injection means 83, the fuel injection timing IT1, the fuel injection timing MPIT1, and the MPI ratio RA1 of initial setting values that are preset for idle operation at the time of cold start are preset. The air-fuel ratio A / F1 is set.

When the compression S / L operation is started, the fuel injection timing IT1, the fuel injection timing MPIT1, the MPI ratio RA1, and the air-fuel ratio A / F1 are kept constant (see, for example, FIGS. 5A to 5E). .
Further, as shown in FIG. 5G, 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 is started, as shown in FIG. 5 (F), the water temperature W gradually rises with time.

When the catalyst temperature is low and the purification capability 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 A / F lean as much as possible within a range where combustion does not deteriorate. As for the injection timing of the in-cylinder fuel injection means 23, the compression stroke injection is faster than the intake stroke injection because of the stratified combustion, the combustion is faster, the combustion stability is better, and the drivability is better. In addition, during the compression S / L operation, 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 obtained from the timer counter 63, the rotational speed control means 65, the valve timing control means 67, the ignition timing control means 69, the in-cylinder fuel injection control means 71, It is output to intake port fuel injection control means 85 and fuel injection ratio control means 87.

The ECU 61 determines whether or not the elapsed time T measured by 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 compression S / L operation is continued as it is. 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 S30).
In operation control 1, as shown in FIG. 4, 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. 5A to 5C, 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.

If 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 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. 5B to 5D, 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 larger 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. 5E, 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. Then, step S2 is implemented.

<Effect>
According to the first embodiment described above, the in-cylinder fuel injection control means 71, the intake port fuel injection control means 85, and the fuel injection ratio control means 87 are provided, and after the predetermined time Tth1 of the compression S / L operation has elapsed, the intake port By increasing the injection amount of the fuel injection means 83 (that is, increasing the MPI ratio RA), 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, 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 raise the exhaust gas temperature.

  Further, since the operation control 1 is performed after the compression S / L operation reaches the predetermined time Tth1, it is possible to prevent the engine 1 from being stopped due to misfire or the like because combustion becomes unstable immediately after the start.

<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 is performed for a predetermined time Tth1, operation control 2 described later is performed, and when the compression S / L operation is performed for a predetermined time Tth2 (> Tth1), the operation described later is performed. When the control S3 is further performed and the compression S / L operation has elapsed for a predetermined time Tth3 (> Tth2), the operation control 1 is further performed as in the first embodiment.
Operation control part 2 and operation control part 3 will be described below.

<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. 6, the engine 1 is started by turning on the ignition switch of the engine 1 (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 MPI ratio RA Then, the air-fuel ratio A / F is calculated (step S2 ′).

  The opening / closing timings of the intake valve 5 and the exhaust valve 9 immediately after the engine start are set values calculated based on the map of the operation region of the engine 1 set in advance. Based on the set values of the opening and closing timings of the intake valve 5 and the exhaust valve 9, the valve timing control means 67, as shown in FIG. 8, the valve overlap angle VOL from the intake valve opening timing In to the exhaust valve closing timing Out. Is calculated.

  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 based on the respective maps of the operating region of the engine 1 set in advance.

Next, similarly to the first embodiment, steps S3 to S9 are performed.
In step S6, when the compression S / L operation is started, the rotational speed control means 65, the valve timing control means 67, and the ignition timing control means 69 are the engine rotational speed Ne, the valve overlap angle VOL (intake valve The engine speed Ne1 and the valve overlap angle VOL1 (the intake valve opening) are set in advance for the idling operation at the time of cold start with respect to the ignition timing SA and the ignition timing SA, calculated from the valve opening timing In and the exhaust valve closing timing Out. Calculated from the valve timing In1 and the exhaust valve closing timing Out1) and the ignition timing SA1.

Next, when the elapsed time T is equal to or longer than the predetermined time Tend in step S9, step S4 is subsequently performed as in the first embodiment.
On the other hand, when the elapsed time T is less than the predetermined time Tend, the operation control 2 is performed (step S10).
In operation control 2, as shown in FIG. 7, 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). S11). 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. 9A). 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. 9C and 9D, 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. 9B).
In consideration of drivability, the exhaust gas purification device at the time of cold start can be reduced because the decrease in the exhaust gas amount can be suppressed by increasing the valve overlap angle VOL as the engine speed Ne decreases as the water temperature W increases. 47 (three-way catalyst 49) can be kept warm.

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.
After step S14, step S15 (see FIG. 6) described later is performed.

  On the other hand, if the valve overlap angle VOL is greater than or equal to the threshold value VOLth in step S13, step S15 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.

In step S15, the ECU 61 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.
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, operation control 3 is further performed (step S20).

  In operation control # 3, as shown in FIG. 10, 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. 8 and 9E, 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. 8 and 9F, the fuel injection timing is advanced to a new fuel injection timing IT (step S24). Thereafter, step S25 is performed.
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 S25 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.

In step S25, the rotation 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.
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. 9 (G) to 9 (K), operation control 1 is further performed (step S30). The control content of the first operation control is the same as in the first embodiment.

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

  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, 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 Tth2 of the compression S / L operation.
Further, an ignition timing control means 69 is provided, and after a predetermined time Tth2 of the compression S / L operation has elapsed, the ignition timing SA is advanced to obtain good combustion to raise the temperature of the catalyst and improve fuel efficiency. be able to.

Further, since the operation control 2 is performed after the predetermined time Tth1 has elapsed, the drivability due to the decrease in the engine speed Ne can be reliably improved, and the engine 1 can be prevented from being stopped due to misfire or the like at the start. .
Then, after the predetermined time Tth2 has passed, since the operation control 3 is further performed, 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 start.
Furthermore, after the predetermined time Tth3 has elapsed, since the operation control 1 is further performed, it is possible to improve the fuel efficiency while stably maintaining the engine speed Ne at the start.

  In this embodiment, the same effect as that of the first embodiment can be obtained.

  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. 11, a new engine speed Ne may be calculated based on a map showing the relationship between the water temperature W and the engine speed Ne acquired in advance through experiments or the like.

  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.

  Although description is omitted in this specification, after the compression S / L operation has elapsed for a predetermined time Th1, operation control No. 1, No. 2 and No. 3 may be performed almost simultaneously.

  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 83 Intake port fuel injection means 85 Intake port fuel injection control means 87 Fuel injection ratio control means

Claims (4)

An internal combustion engine having a catalyst for purifying exhaust gas provided in an exhaust gas passage, in-cylinder fuel injection means for directly injecting fuel into a combustion chamber, and intake port fuel injection means for injecting fuel into an intake port, An internal combustion engine that performs a catalyst heating operation in which the air-fuel ratio is leaner than the stoichiometric air-fuel ratio or the stoichiometric air-fuel ratio by injecting fuel into the combustion chamber from the in-cylinder fuel injection means during the compression stroke of the internal combustion engine at the cold start In the operation control device of
In-cylinder fuel injection control means for controlling the injection timing and amount of fuel injected from the in-cylinder fuel injection means;
Intake port fuel injection control means for controlling the injection timing and injection amount of fuel injected from the intake port fuel injection means;
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 started according to 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 fuel injection ratio control means for increasing the ratio of the initial setting value at the time ,
The fuel injection ratio control means determines the injection amount of the intake port fuel injection means relative to the injection amount of the in-cylinder fuel injection means until the cooling water reaches a predetermined temperature or a predetermined time from the start of the catalyst temperature raising operation. The initial set value is kept constant as a ratio, and control is performed to increase the ratio of the injection amount after the cooling water reaches the predetermined temperature or the predetermined time from the start of the catalyst heating operation. An operation control apparatus for an internal combustion engine characterized by the above. The intake port fuel injection control means is preset with a time difference calculated by subtracting the predetermined time from the elapsed time measured after the start of the catalyst temperature raising operation after reaching the predetermined time. 2. The internal combustion engine according to claim 1, wherein control is performed to advance the injection timing of the intake port fuel injection means from an injection angle of an initial set value at the time of starting when the time difference is greater than or equal to a predetermined time difference. Operation control device.   The fuel injection ratio control means reduces the injection amount of the in-cylinder fuel injection means to an injection amount of 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 The operation control device for an internal combustion engine according to claim 1 or 2, wherein the ratio of the injection amount of the engine is increased. The fuel injection ratio control means is preset with a time difference calculated by subtracting the predetermined time from the elapsed time measured from the start of the catalyst temperature raising operation after the predetermined time is reached. 4. The air-fuel ratio is made lean by decreasing the injection amount of the in-cylinder fuel injection means while keeping the injection amount of the intake port fuel injection means as it is when the time difference is greater than or equal to the time difference. The operation control device for an internal combustion engine according to any one of the preceding claims .

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