JP2006017004A - Control device for internal combustion engine with movable valve mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for a variable valve mechanism capable of performing control to maintain a stable combustion state even in cold condition. <P>SOLUTION: The number of valve stop cranking times i and the number of cycle times j are set based on engine water temperature, intake air temperature, actual compression ratio, and cranking rotating speed (step 101). When it is determined that the number of the cycle times j is larger than 0, a valve stop cranking cycle is started (step 103). Concretely, i valve stop crankings are started in a state of closing intake and exhaust valves and inhibiting ignition by an ignition plug. When the step 103 ends, processing returns to the step 101. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a control device for an internal combustion engine provided with a movable valve mechanism that makes the operation timing of intake and exhaust valves variable.

  Normally, in a general internal combustion engine, the piston position, the fuel injection timing of the injector, the timing of opening / closing control of the intake valve (IN valve) and the exhaust valve (EX valve), and the ignition timing are based on waveforms as shown in FIG. I have control. FIG. 11 shows the control timing of a port injection type four-cycle engine as an example. Here, FIGS. 11A, 11B, 11C, and 11D respectively show the piston position, injector injection valve opening / closing timing, IN valve opening / closing timing, and EX valve opening / closing timing by waveforms. .

  In such a conventional internal combustion engine, when the in-cylinder temperature during cold is low, the fuel injected from the injector is hardly atomized, causing problems such as discharge of unburned fuel.

In order to solve such a problem, a method is considered in which exhaust is not performed until most of the unburned fuel is combusted. The invention described in Japanese Patent Application Laid-Open No. Sho 62-243909 attempts to realize the above method. Specifically, at the time of starting the internal combustion engine, the intake valve and the exhaust valve are kept closed until the cranking stable rotational speed is reached. Further, even after reaching the cranking stable rotational speed, the unburned fuel is reduced by prohibiting the opening of the exhaust valve at a predetermined timing.
JP-A-62-243909 Japanese Patent Laid-Open No. 10-252511 Japanese Patent Laid-Open No. 10-9004

  However, although the above invention attempts to suppress the discharge of unburned fuel, the fuel injection from the injector is performed even while the intake valve and the exhaust valve are held closed. A large amount of fuel that is not atomized adheres to the wall surface of the combustion chamber or remains in the port or cylinder as floating droplets. Therefore, it cannot be said that the suppression of discharge of unburned fuel is sufficiently realized.

  The present invention has been made to solve the above-described problems, and provides a control device for a movable valve mechanism capable of performing control so that a stable combustion state is maintained even when cold. With the goal.

  In order to achieve the above object, according to a first aspect of the present invention, in a control device for an internal combustion engine provided with a variable valve mechanism, the variable valve mechanism that varies the operation pattern of an intake valve and an exhaust valve of the internal combustion engine; An initial state forming means for forming an initial state in which air and fuel are present in a cylinder of the internal combustion engine; and a valve closing means for closing the intake valve and the exhaust valve for a predetermined period after the initial state is formed; An ignition prohibiting unit that prohibits ignition by the spark plug over the predetermined period; and a release unit that realizes a release state in which functions of the valve closing unit and the ignition prohibiting unit are canceled after the predetermined period has elapsed. It is characterized by that.

  According to a second aspect of the present invention, there is provided a control device for an internal combustion engine including a variable valve mechanism, wherein the variable valve mechanism for changing the operation patterns of the intake valve and the exhaust valve of the internal combustion engine, and the cylinder of the internal combustion engine In-cylinder injection means for injecting fuel, valve closing means for closing the intake valve and the exhaust valve for a predetermined period from the start of the internal combustion engine, and the in-cylinder injection divided into a plurality of times during the predetermined period Disperse injection means for injecting fuel from the means, ignition prohibition means for prohibiting ignition by the spark plug for the predetermined period, and release of the functions of the valve closing means and the ignition prohibition means after the predetermined period has elapsed Release means for realizing the state.

  In a third aspect based on the first aspect, the initial state forming means opens the intake valve until the crank angle reaches a predetermined crank angle after the intake bottom dead center after the intake stroke starts. A decompression cycle realizing means for realizing the decompression cycle is included.

  According to a fourth aspect, in the third aspect, the initial state forming means includes valve opening means for opening the intake valve in an intake stroke after the decompression cycle.

  In a fifth aspect based on any one of the first to fourth aspects, the release means retards an initial ignition timing after the release state is formed with respect to a normal ignition timing. Means.

  According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the initial state forming means uses the air present in the cylinder when the internal combustion engine is started to form the initial state. And at least one of means for forming the initial state using air taken in at the start of the internal combustion engine.

  According to a seventh invention, in any one of the first to sixth inventions, there is provided means for repeatedly executing the operation from the initial state to the release state a plurality of times.

  Further, an eighth invention is based on any one of the first to seventh inventions, based on at least one of the cooling water temperature, the intake air temperature, the actual compression ratio, and the cumulative number of times of cranking since the start of the internal combustion engine. It has a number-of-times determining means for determining the number of times to execute the operation from the initial state to the release state.

  Further, a ninth invention is based on any one of the first to eighth inventions, on the basis of at least one of the coolant temperature, the intake air temperature, the actual compression ratio, and the cumulative cranking count from the start of the internal combustion engine. It has the period determination means which determines a predetermined period, It is characterized by the above-mentioned.

  Further, a tenth aspect of the invention is based on any one of the first to ninth aspects of the invention, based on at least one of the coolant temperature, the intake air temperature, the actual compression ratio, and the cumulative cranking count from the start of the internal combustion engine. It has an execution decision means for deciding whether or not to execute the operation from the initial state to the release state.

  In an eleventh aspect based on any one of the first to the tenth aspects, the valve closing means is at least one of a cooling water temperature, an intake air temperature, an actual compression ratio, and a cumulative cranking count from the start of the internal combustion engine. It is characterized by having a period end judging means for judging whether or not the predetermined period has ended with reference to one.

  According to the first invention, atomization of the fuel is promoted by closing the intake valve and the exhaust valve and cranking in a state where air and fuel are present in the cylinder of the internal combustion engine. Moreover, a stable combustion state can be realized by igniting the atomized fuel. Furthermore, emission of unburned fuel can be suppressed by realizing a stable combustion state.

  According to the second invention, in the in-cylinder injection type internal combustion engine, by injecting the fuel into the cylinder in a plurality of times, compared to injecting a predetermined amount of fuel at a time, It is possible to prevent droplet fuel from adhering to the combustion chamber and the wall surface of the piston. Further, atomization of the fuel is promoted by closing the intake valve and the exhaust valve while cranking the fuel while injecting the fuel into the cylinder of the internal combustion engine. Further, the ignition is performed on the atomized fuel, so that the combustion state can be stably realized. Furthermore, emission of unburned fuel can be suppressed by realizing a stable combustion state.

  According to the third aspect of the invention, even when the decompression cycle in which the intake valve is opened from the intake stroke to the compression stroke is realized, the effects obtained in the first invention can be obtained. Also, by realizing the decompression cycle, it is possible to reduce the pumping loss when performing cranking by closing the intake valve and the exhaust valve.

  According to the fourth invention, by opening the intake valve in the intake stroke after the decompression cycle, it is possible to sufficiently intake air necessary for combustion into the cylinder. Further, by opening the intake valve, the pumping loss in the intake stroke can be reduced.

  According to the fifth invention, a large amount of heat can be sent to the catalyst together with the exhaust gas by igniting later than the normal timing. As a result, warming up of the catalyst can be promoted.

  According to the sixth aspect of the invention, the initial state can be formed by using the air that has been present in the cylinder in advance or the air that has been sucked into the cylinder after the start.

  According to the seventh aspect, the operation from the initial state to the release state can be repeatedly executed as necessary. As a result, until the operation of the internal combustion engine settles down, it is possible to maintain a stable combustion state and to realize emission suppression of unburned fuel.

  According to the eighth aspect, the number of times to repeat the operation from the initial state to the release state can be determined based on various conditions. As a result, the operation of the internal combustion engine can be smoothly shifted to a stable state.

  According to the ninth aspect, it is possible to determine the period during which the operation from the initial state to the release state should be performed based on various conditions. As a result, the operation of the internal combustion engine can be smoothly shifted to a stable state.

  According to the tenth aspect, it is possible to determine whether or not to perform the operation from the initial state to the release state based on various conditions. As a result, when the operation of the internal combustion engine is shifted to a stable state, the operation can be smoothly switched to the normal operation.

  According to the eleventh aspect, it is possible to determine whether or not the predetermined period has ended based on various conditions. As a result, when the operation of the internal combustion engine is shifted to a stable state, the operation can be smoothly switched to the normal operation.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is common in each figure, and the overlapping description is abbreviate | omitted.

Embodiment 1 FIG.
[Configuration of Embodiment 1]
FIG. 1 is a diagram for explaining the configuration of an internal combustion engine 10 according to Embodiment 1 of the present invention. The internal combustion engine 10 includes a piston 14 inside a cylinder 12. The piston 14 is connected to a crank 18 via a connecting rod 16. An engine speed sensor 20 that detects the speed of the crankshaft is disposed in the vicinity of the crank 18.

  A combustion chamber 22 is formed above the piston 14. An intake port 24 and an exhaust port 26 communicate with the combustion chamber 22, and a spark plug 28 is inserted so that the tip portion is exposed. An injector 30 is assembled in the intake port 24. Further, a throttle valve 32 and an intake air amount sensor 34 are disposed upstream of the injector 30. On the other hand, an air-fuel ratio sensor 36 that emits an output corresponding to the air-fuel ratio of the air-fuel mixture supplied to the internal combustion engine 10 is disposed in the exhaust port 26. In the present embodiment, the throttle valve 32 includes an actuator for realizing an arbitrary opening degree regardless of the depression amount of the accelerator pedal.

  The internal combustion engine 10 includes an intake valve 38 that opens and closes the intake port 24 and an exhaust valve 40 that opens and closes the exhaust port 26. The internal combustion engine 10 also includes a variable valve mechanism 42 that drives the intake valve 38 and a variable valve mechanism 44 that drives the exhaust valve 40. The variable valve mechanisms 42 and 44 in the present embodiment are assumed to be electromagnetically driven valves that can open and close each valve. However, the present invention is not limited to this, and an electromagnetic cam or mechanically idle driving is assumed. It may be a cam or the like.

  The internal combustion engine 10 shown in FIG. 1 includes an ECU (Electronic Control Unit) 49. Various sensors such as the engine speed sensor 20, the intake air amount sensor 34, and the air-fuel ratio sensor 36 are electrically connected to the ECU 49. In addition, an intake air temperature sensor 50 that detects the temperature THA of the intake air, a cooling water temperature sensor 52 that detects the cooling water temperature THW of the internal combustion engine 10, and a compression ratio sensor 54 that detects a substantial compression ratio of the internal combustion engine 10 are also electrically connected to the ECU 49. Connected. The ECU 49 acquires information necessary for controlling the internal combustion engine from these various sensors. Based on the information, the spark plug 28, the injector 30, the throttle valve 32, the variable valve mechanisms 42 and 44, and the like are driven.

  By the way, after the internal combustion engine 10 is cold-started, the fuel is less likely to be atomized than after the warm-up is completed until the warm-up is sufficiently performed. Hereinafter, a time point at which such a state can occur, that is, a point in time when a good combustion state may not be maintained after the start of the internal combustion engine 10 is referred to as “cold time”. Further, the time point when the internal combustion engine 10 is operating in this state is referred to as “during cold operation”.

  The deterioration of the combustion state during the cold operation described above can be prevented by creating a state in which the fuel is easily atomized. In the internal combustion engine 10 of the present embodiment, the atomization of fuel is promoted by promoting the mixing of air and fuel existing in the cylinder by the cranking operation of the piston 14. That is, after the initial state in which air and fuel are present in the cylinder is formed, the fuel is sufficiently atomized by performing compression and expansion while holding the intake valve 38 and the exhaust valve 40 closed for a predetermined period. Ignition by the spark plug 28 is prohibited. By doing so, a good combustion state can be maintained even during cold operation.

[Control in Embodiment 1]
Hereinafter, control in the present embodiment will be described. FIG. 2 is a timing chart for explaining the piston position in the internal combustion engine and the contents of control of the injector, the intake valve, and the exhaust valve. Specifically, FIG. 2A is a waveform showing how the position of the piston 14 moves, and also shows the timing of ignition. FIG. 4B shows the injection timing of the injector 30, and FIGS. 4C and 4D show the timing of opening / closing control of the intake valve 38 and the exhaust valve 40, respectively. For convenience of explanation, the initial position of the piston 14 is a bottom dead center (BDC), and the position of the piston 14 is directed to the top dead center (TDC) as the internal combustion engine 10 starts. Shall be moved.

  In FIG. 2, the internal combustion engine 10 starts to be started, the intake valve 38 is opened (FIG. 2C), and fuel is injected from the injector 30. Thereby, an initial state in which air and fuel exist in the combustion chamber 22 is formed.

  When the initial state is formed and the position of the piston 14 reaches the BDC, the intake valve 38 is closed (FIG. 2C). Since the exhaust valve 40 has been kept closed since the internal combustion engine 10 is started, both the intake valve 38 and the exhaust valve 40 are closed at this time. The internal combustion engine 10 performs cranking while maintaining this closed state (FIG. 2A). Here, cranking while holding the intake valve and the exhaust valve closed is called “valve stop cranking”. The number of times the piston is reciprocated while holding the intake valve and the exhaust valve closed is referred to as “valve stop cranking number”. FIG. 2 shows an example in which the first ignition is performed after the valve stop cranking is performed twice.

  By performing the valve stop cranking, the internal combustion engine 10 promotes the mixing of the air and the fuel existing in the combustion chamber 22, and as a result, the fuel can be burned in a sufficiently atomized state.

  In the internal combustion engine 10, ignition by the spark plug 28 is prohibited until fuel atomization is sufficiently performed by valve stop cranking (FIG. 2A). When the position of the piston 14 reaches TDC after the end of the valve stop cranking, the operation prohibition of the spark plug 28 is released and ignition is performed (FIG. 2A). After ignition, the exhaust valve 40 is opened (FIG. 2D), and the exhaust gas is discharged. Thereafter, in the internal combustion engine 10, fuel is injected together with the opening of the intake valve 38 (FIGS. 2B and 2C), and normal operation is performed.

  A state in which the internal combustion engine 10 can start normal operation is a series of control in which ignition is performed through valve stop cranking after an initial state in which air and fuel exist in the combustion chamber 22 is formed. The number of times of a series of control executed until the time is “cycle number”. In the present embodiment, as shown in FIG. 2, the case where the number of cycles is one has been described. However, the number of cycles can be set to two or more in accordance with the operation state of the internal combustion engine.

  In the present embodiment, by performing valve stop cranking, the air and fuel in the combustion chamber are sufficiently mixed, and ignition can be performed in a state where the fuel is atomized. This not only realizes a stable combustion state in the internal combustion engine 10, but also realizes emission suppression of unburned fuel.

Embodiment 2. FIG.
In the first embodiment, the control performed according to the set valve stop cranking number and cycle number has been described. In the present embodiment, control for setting the valve stop cranking number and the cycle number will be described.

[Control in Embodiment 2]
FIG. 3 is a flowchart illustrating an outline of processing performed by the ECU 49 in Embodiment 2 of the present invention. In this routine, first, the valve stop cranking number i and the cycle number j are set from the engine water temperature, the intake air temperature, the actual compression ratio, and the cranking rotation speed (step 101).

  The engine water temperature, the intake air temperature, the actual compression ratio, and the cranking rotation speed are detected by the cooling water temperature sensor 52, the intake air temperature sensor 50, the compression ratio sensor 54, and the engine rotation speed sensor 20, respectively. In this step, the valve stop cranking number i and the cycle number j are set based on these detection contents.

  Here, the setting method of the valve stop cranking frequency | count i performed at this step is demonstrated using FIG. 4A to 4D are maps schematically showing the relationship between the engine water temperature (THW), the intake air temperature (THA), the actual compression ratio, the cranking rotation speed, and the valve stop cranking frequency, respectively. . These maps are incorporated in the ECU 49. ECU49 inquires the data detected from various sensors, and these maps, and sets the valve stop cranking frequency | count i.

  Hereinafter, the maps shown in FIGS. 4A to 4D will be described. First, the high engine water temperature (THW) shown in FIG. 4 (A) indicates that the internal combustion engine is warming up, which indicates that the fuel is easily atomized. . Therefore, the higher the THW, the less the required number of valve stop crankings. Further, a high intake air temperature (THA) shown in FIG. 4B indicates that warm air is sucked into the cylinder, and that the fuel is easily atomized in the cylinder. Therefore, the higher the THA, the less the required number of valve stop crankings.

  Further, the high actual compression ratio shown in FIG. 4C indicates that the compression end temperature in the cylinder, that is, the cylinder temperature when the piston reaches the top dead center, is high. Is in a state of being easily atomized. Therefore, the higher the actual compression ratio, the smaller the required number of valve stop cranking operations. Furthermore, a large cranking rotational speed shown in FIG. 4D indicates that time has elapsed since the internal combustion engine started, and that the warm-up of the internal combustion engine has progressed accordingly. . Therefore, as the cranking rotation speed increases, the required number of valve stop cranking operations decreases.

  In FIG. 3, when the processing in step 101 is completed, it is next determined whether or not the number of cycles j is greater than 0 (step 102). As described above, the number of cycles refers to the number of times that a series of control is performed from when the initial state is formed to when ignition is performed. 10 indicates that it is still necessary to perform valve stop cranking, that is, it is not possible to shift to normal operation. On the other hand, if the number of cycles j is 0, the internal combustion engine 10 is sufficiently warmed up and can smoothly shift to normal operation without further control including valve stop cranking. It is shown that.

  In this step, when it is determined that the cycle number j is not greater than 0, the present routine is terminated as it is. That is, the internal combustion engine 10 starts normal operation. On the other hand, if it is determined that the cycle number j is greater than 0, the process proceeds to step 103.

  In step 103, a valve stop cranking cycle is started. Specifically, i times of valve stop cranking is started in accordance with the value of the number of times of valve stop cranking i determined in step 101 with the intake and exhaust valves closed and ignition by the spark plug prohibited. . When the process of step 103 is completed, the process returns to step 101, and the valve stop cranking number i and the cycle number j are set again based on the current engine water temperature, intake air temperature, actual compression ratio, and cranking rotation speed.

  As described above, by setting the valve stop cranking number i and the cycle number j based on the engine water temperature, the intake air temperature, the actual compression ratio, and the cranking rotation speed, the setting according to the current state of the internal combustion engine 10 is performed. be able to. As a result, the internal combustion engine can be smoothly started when cold.

Embodiment 3 FIG.
In the first embodiment, the intake valve 38 is opened at the start of the internal combustion engine 10 and air is supplied into the combustion chamber 22, but in this embodiment, the intake valve 38 is not opened. Control for performing valve stop cranking using air pre-existing in the combustion chamber 22 will be described. However, in the present embodiment, since it is necessary to inject fuel into the combustion chamber 22 without opening the intake valve 38, an internal combustion engine of a cylinder injection type is used instead of the internal combustion engine using the port injector shown in FIG. A description will be given assuming that an organization is used.

  First, FIG. 5 shows a timing chart for explaining the piston position and the contents of control of the injector, the intake valve and the exhaust valve in the cylinder injection type internal combustion engine. As shown in FIG. 5A, since the piston 14 is positioned at the BDC at the start of the start of the internal combustion engine 10, air necessary for combustion already exists in the combustion chamber 22. Therefore, in this embodiment, it is not necessary to open the intake valve 38, and the valve closing state is maintained (FIG. 5C).

  While the position of the piston 14 moves from TDC to BDC, fuel injection by the injector is started (FIG. 5B). When the fuel injection is completed, air and fuel exist in the combustion chamber 22. Thereafter, the intake valve 38 and the exhaust valve 40 are held closed, valve stop cranking is performed, and ignition by the spark plug 28 is performed (FIG. 5A).

  Even when the piston 14 is not positioned at the BDC when the internal combustion engine 10 is started, if the air necessary for combustion exists in the combustion chamber 22 in advance, the control contents described in FIG. Similarly, valve stop cranking can be performed without opening the intake valve 38. However, if the air necessary for combustion does not exist in the combustion chamber 22, the intake valve 38 must be opened to supply air. Therefore, in the third embodiment, it is confirmed whether or not sufficient air exists in the combustion chamber 22, and the subsequent processing is performed. FIG. 6 shows a routine for performing control for confirming the presence or absence of air in the combustion chamber 22. Hereinafter, the control contents performed by the ECU 49 will be described with reference to FIG.

  First, it is determined whether or not the piston position is within a predetermined value from the bottom dead center (BDC) (step 201). Here, the “predetermined value” is a value indicating a piston position at which a minimum value of the amount of air necessary for combustion can be secured. When the piston 14 is located within this predetermined value, it means that the amount of air necessary for combustion exists in the combustion chamber 22. Therefore, when it is determined in this step that the piston position is within the predetermined value, it is not necessary to supply new air, so the intake valve 38 is maintained in the closed state (step 203). On the other hand, when the piston 14 is positioned on the TDC side exceeding this value, it means that the amount of air necessary for combustion does not exist in the combustion chamber 22. Therefore, when it is determined in this step that the piston position does not exist within the predetermined value, the internal combustion engine 10 opens the intake valve 38 to supply air necessary for combustion into the combustion chamber 22 (step). 207).

  After the amount of air necessary for combustion is secured in the combustion chamber 22 by controlling the intake valve 38, valve stop cranking is performed while the intake valve 38 and the exhaust valve 40 are held closed (step 205). . By this valve stop cranking, air and fuel can be sufficiently mixed in the combustion chamber, and ignition can be performed with the fuel atomized.

  By performing the control as described above, in the internal combustion engine 10 of the present embodiment, when there is sufficient air in the combustion chamber 22, valve stop cranking can be performed without opening the intake valve 38. .

Embodiment 4 FIG.
Next, a fourth embodiment of the present invention will be described with reference to FIG. In the first embodiment, a mode is described in which the necessary fuel is injected into the combustion chamber 22 at one time, and then valve stop cranking is performed without performing fuel injection. In the fourth embodiment, a mode in which the fuel injected in the first embodiment is injected in small portions in a plurality of times will be described.

[Configuration of Embodiment 4]
The system of the present embodiment can be realized by using an injector inserted into the combustion chamber 22 instead of the injector 30 assembled to the intake port 24 in the configuration shown in FIG. About another structure, it can implement | achieve using the structure similar to Embodiment 1. FIG.

[Control in Embodiment 4]
FIG. 7 is a timing chart for explaining the control of the piston position and the injector, intake valve and exhaust valve in the cylinder injection internal combustion engine. Specifically, FIG. 7A is a waveform showing how the position of the piston 14 moves between the top dead center (TDC) and the bottom dead center (BDC). Here, the timing of ignition is shown. It also shows. FIG. 7B shows the injection timing of the injector 30, and FIGS. 7C and 7D show the timing of opening / closing control of the intake valve 38 and the exhaust valve 40, respectively.

  As shown in FIG. 7, in the internal combustion engine 10 of the present embodiment, the intake valve 38 is opened after the start of the internal combustion engine 10 so that air necessary for combustion is supplied into the combustion chamber 22 (see FIG. 7). 7 (C)). By injecting fuel into the air in the combustion chamber 22, an initial state in which air and fuel exist is formed. In this embodiment, the fuel is supplied into the combustion chamber 22 by three divided injections. (FIG. 7B). Specifically, the first fuel injection is performed by the injector in accordance with the opening timing of the intake valve 38 (FIG. 7B). However, since this fuel injection is performed in a short time, combustion is performed. The amount of fuel is insufficient with respect to the amount of air in the chamber 22. Accordingly, the second and third fuel injections are performed while performing valve stop cranking over a predetermined period (FIG. 7B), and fuel and air necessary for one combustion are supplied.

  By performing such split injection, the control apparatus for an internal combustion engine provided with the variable valve mechanism of the present embodiment has the following effects. That is, dividing the fuel into multiple injections as compared to injecting the fuel once when the temperature of the combustion chamber has not risen when it is cold increases the atomization rate of the fuel. Become. Moreover, as shown in FIG. 7, by performing split injection when the piston 14 reaches the BDC, fuel can be prevented from adhering to the piston 14 and atomization can be promoted.

Embodiment 5. FIG.
Next, a fifth embodiment of the present invention will be described with reference to FIG. In the fourth embodiment, a mode in which fuel necessary for the combustion chamber 22 is injected in a plurality of times and then a normal operation is performed is described. In the fifth embodiment, a mode in which fuel injection immediately after the start of operation of the internal combustion engine is avoided and the divided injection performed in the fourth embodiment is performed will be described. Note that the system of the present embodiment can be realized using the same configuration as that of the fourth embodiment.

[Control in Embodiment 5]
FIG. 8 is a timing chart for explaining the control of the piston position, injector, intake valve, and exhaust valve in the direct injection internal combustion engine. As shown in FIG. 8, in the internal combustion engine 10 of the present embodiment, the intake valve 38 is opened after the start of the internal combustion engine 10, and air necessary for combustion is supplied into the combustion chamber 22 (FIG. 8C )). After the supply of air is completed, fuel is injected by the injector during the second valve stop cranking (FIG. 8B), and ignition is performed. After ignition, the exhaust valve 40 is opened (FIG. 8D), new air is taken in (FIG. 8C), and fuel is injected in three steps (FIG. 8B). .

  Here, when the internal combustion engine is started, the accuracy of fuel injection becomes lower than usual because sufficient fuel pressure cannot be obtained in the injector. As shown in FIG. 8, the valve stop cranking is performed even during the cold operation by controlling the fuel to be injected immediately after the start of the internal combustion engine 10 and immediately before the first ignition is performed. While waiting for the fuel pressure to rise. Therefore, it is possible to maintain the fuel injection accuracy as usual. Further, since the second and subsequent valve stop cranking is divided injection, the same effect as that obtained in the fourth embodiment can be obtained.

Embodiment 6 FIG.
Next, a sixth embodiment of the present invention will be described with reference to FIG. In the sixth embodiment, the control executed when the internal combustion engine is started to perform pressure reduction (decompression) for reducing the compression work by delaying the timing for closing the intake valve will be described. Note that the system of the present embodiment can be realized by the configuration shown in FIG. However, the present invention is not limited to a port injection type internal combustion engine, and may be applied to a cylinder injection type internal combustion engine.

[Control in Embodiment 6]
FIG. 9 is a timing chart for explaining the control of the piston position and the injector, intake valve and exhaust valve in the direct injection internal combustion engine. As shown in FIG. 9, in this embodiment, after the internal combustion engine 10 is started, the intake valve 38 is opened at the intake top dead center (FIG. 9C). Thereafter, the intake valve 38 is maintained in an open state to a position that exceeds the intake bottom dead center by a predetermined crank angle (FIG. 9C). Thereafter, the intake valve 38 is closed, but the valve 14 is opened again for a predetermined period from the position where the piston 14 exceeds the intake top dead center by a predetermined crank angle (FIG. 9C).

  As shown in FIG. 9B, fuel injection by the injector is performed in accordance with the opening timing of the intake valve 38. When the intake valve 38 is first opened after the internal combustion engine 10 is started, about half of the fuel required for one combustion is injected. Further, when the intake valve 38 is opened for the second time, the remaining fuel is injected.

  By performing such control, the control apparatus for an internal combustion engine provided with the variable valve mechanism of the present embodiment has the following effects. That is, first, by closing the intake valve 38 at a retarded timing during cold operation, the compression work due to pumping can be reduced, so that the startability of the internal combustion engine 10 is improved. Secondly, by performing fuel injection in accordance with the opening timing of the intake valve 38, it is possible to inject fuel into the inflowing air, thereby promoting fuel atomization. Third, after the start of the internal combustion engine 10, when the position of the piston 14 moves from TDC to BDC for the second time, the intake valve 38 is opened to replenish the air deficient in the first intake. Therefore, sufficient output torque can be exhibited from the first ignition.

Embodiment 7 FIG.
Next, a seventh embodiment of the present invention will be described with reference to FIG. During cold operation, it is important to warm up the internal combustion engine, but it is also important to raise the temperature of the catalyst for purifying the exhaust gas to the activation temperature. In the seventh embodiment, a mode in which catalyst warm-up is performed by retarding the ignition of fuel will be described. Note that the system of the present embodiment can be realized by the configuration shown in FIG. However, the present invention is not limited to a port injection type internal combustion engine, and may be applied to a cylinder injection type internal combustion engine.

[Control in Embodiment 7]
FIG. 10 is a timing chart for explaining the piston position and the contents of control of the injector, the intake valve, and the exhaust valve in the cylinder injection internal combustion engine. In FIG. 10, when the internal combustion engine 10 starts to start, the intake valve 38 is opened (FIG. 10C), and at the same time, fuel is injected from the injector 30 (FIG. 10B). Thereby, an initial state in which air and fuel exist in the combustion chamber 22 is formed. At this time, the exhaust valve 40 is kept closed.

  When the initial state is formed, valve stop cranking is started. When the valve stop cranking is completed, ignition is normally performed when the position of the piston 14 reaches TDC, but in this embodiment, the ignition executed at this time is subjected to a retarding process (FIG. 10). (B)).

  When the position of the piston 14 is moved to just before reaching the BDC, ignition by the spark plug 28 is executed (FIG. 10B), and the exhaust valve 40 is opened (FIG. 10D). At this time, exhaust gas containing a large amount of heat is exhausted from the exhaust valve 40. Thereafter, the exhaust gas reaches the catalyst, and the catalyst is warmed up by afterburning.

  In the present embodiment, the structure in which the ignition plug is assembled to the combustion chamber is used. However, in order to further promote the warming up of the catalyst, another ignition plug may be provided immediately before the catalyst.

  By performing such control, the control apparatus for an internal combustion engine provided with the variable valve mechanism of the present embodiment has the following effects. That is, fuel atomization can be promoted by performing valve stop cranking when the warm-up of the catalyst does not reach the activation temperature during the cold operation. In addition, since the fuel is sufficiently atomized, ignition delayed from the normal ignition timing can be performed. Further, by performing the retarded ignition, a large amount of heat can be sent to the catalyst together with the exhaust gas. As a result, warming up of the catalyst can be promoted.

It is a figure for demonstrating the structure of embodiment suitable for this invention. It is a timing chart explaining the control content performed in Embodiment 1 suitable for this invention. It is a flowchart explaining the control content performed in Embodiment 2 suitable for this invention. It is explanatory drawing which shows an example of the map used for the setting of the valve stop cranking frequency | count in Embodiment 2 suitable for this invention. It is a timing chart explaining the control content performed in Embodiment 3 suitable for this invention. It is a flowchart for demonstrating the control content performed in Embodiment 3 suitable for this invention. It is a timing chart explaining the control content performed in Embodiment 4 suitable for this invention. It is a timing chart explaining the control content performed in Embodiment 5 suitable for this invention. It is a timing chart explaining the control content performed in Embodiment 6 suitable for this invention. It is a timing chart explaining the control content performed in Embodiment 7 suitable for this invention. It is a timing chart explaining the content of control performed in the conventional internal combustion engine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 12 Cylinder 14 Piston 16 Connecting rod 18 Crank 20 Engine speed sensor 22 Combustion chamber 24 Intake port 26 Exhaust port 28 Spark plug 30 Injector 32 Throttle valve 34 Intake air amount sensor 36 Air fuel ratio sensor 38 Intake valve 40 Exhaust valve 42, 44 Variable valve mechanism 49 ECU (Electronic Control Unit)
50 Intake air temperature sensor 52 Cooling water temperature sensor 54 Compression ratio sensor

Claims (11)

A variable valve mechanism that varies the operation pattern of the intake valve and the exhaust valve of the internal combustion engine;
Initial state forming means for forming an initial state in which air and fuel are present in a cylinder of the internal combustion engine;
Valve closing means for closing the intake valve and the exhaust valve over a predetermined period after the initial state is formed;
Ignition inhibiting means for inhibiting ignition by the spark plug over the predetermined period;
A control unit for an internal combustion engine having a variable valve mechanism, comprising: a release unit that realizes a release state in which functions of the valve closing unit and the ignition inhibition unit are released after the predetermined period has elapsed. . A variable valve mechanism that varies the operation pattern of the intake valve and the exhaust valve of the internal combustion engine;
In-cylinder injection means for injecting fuel into the cylinder of the internal combustion engine;
Valve closing means for closing the intake valve and the exhaust valve over a predetermined period from the start of the internal combustion engine;
Distributed injection means for injecting fuel from the in-cylinder injection means divided into a plurality of times during the predetermined period;
Ignition inhibiting means for inhibiting ignition by the spark plug over the predetermined period;
A control unit for an internal combustion engine having a variable valve mechanism, comprising: a release unit that realizes a release state in which functions of the valve closing unit and the ignition inhibition unit are released after the predetermined period has elapsed. .   The initial state forming means includes decompression cycle realizing means for realizing a decompression cycle for opening the intake valve until the crank angle reaches a predetermined crank angle after the intake bottom dead center after the start of the intake stroke. A control apparatus for an internal combustion engine, comprising the variable valve mechanism according to claim 1.   The internal combustion engine having a variable valve mechanism according to claim 3, wherein the initial state forming means includes valve opening means for opening the intake valve in an intake stroke after the decompression cycle. Control device.   The said cancellation | release means includes the ignition delay means which retards the first ignition timing after forming a cancellation | release state with respect to a normal ignition timing, The said any one of Claims 1-4 characterized by the above-mentioned. The control apparatus of the internal combustion engine provided with the variable valve mechanism.   The initial state forming means forms the initial state using air existing in a cylinder when starting the internal combustion engine, and forms the initial state using air sucked when starting the internal combustion engine. The control device for an internal combustion engine provided with the variable valve mechanism according to any one of claims 1 to 5, further comprising at least one of means for performing the operation.   The control device for an internal combustion engine having a variable valve mechanism according to any one of claims 1 to 6, further comprising means for repeatedly executing the operation from the initial state to the release state a plurality of times.   A number-of-times determining means for determining the number of times to execute the operation from the initial state to the release state based on at least one of the cooling water temperature, the intake air temperature, the actual compression ratio, and the cumulative number of cranking times from the start of the internal combustion engine. An internal combustion engine control device comprising the variable valve mechanism according to any one of claims 1 to 7.   2. The apparatus according to claim 1, further comprising period determining means for determining the predetermined period on the basis of at least one of a cooling water temperature, an intake air temperature, an actual compression ratio, and a cumulative cranking count from the start of the internal combustion engine. Item 9. A control device for an internal combustion engine, comprising the variable valve mechanism according to any one of Items 8.   Execution decision for determining whether or not to execute the operation from the initial state to the release state on the basis of at least one of the cooling water temperature, the intake air temperature, the actual compression ratio, and the cumulative number of times of cranking since the start of the internal combustion engine 10. A control apparatus for an internal combustion engine comprising a variable valve mechanism according to claim 1, further comprising means.   The valve closing means determines whether or not the predetermined period has ended based on at least one of the coolant temperature, the intake air temperature, the actual compression ratio, and the cumulative number of crankings since the start of the internal combustion engine. 11. A control device for an internal combustion engine comprising the variable valve mechanism according to claim 1, further comprising means.

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