JP2008232095A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase fuel consumption reduction effect by a tumble control valve (TCV) in a partial zone. <P>SOLUTION: Opening of TCV 33 is set to an open side as engine speed NE increases and opening of the TCV 33 is set to the open side as engine load PM increases in the partial zone. Consequently, opening of the TCV 33 can be controlled to a direction (open side) to reduce intake resistance with corresponding to increase of intake air quantity due to increase of engine speed NE, and pumping loss in the partial zone by the TCV 33 can be reduced. Ignition retarded quantity from standard ignition timing is set small as opening of the TCV 33 shifts to open side. Consequently, ignition timing can be corrected to a direction approaching to optimal ignition timing with corresponding to shift of optimal ignition timing (MBT) to advanced side due to decrease of combustion speed as opening of the TCV 33 shifts to open side, and fuel consumption reduction effect can be increased. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control apparatus for an internal combustion engine having a function of controlling the airflow intensity in a cylinder by adjusting the opening degree of an airflow control valve provided in an intake passage of the internal combustion engine.

  In order to improve the combustion state of the internal combustion engine and improve fuel consumption and exhaust emission, an air flow control valve (for example, a tumble control valve or a swirl control valve) that opens and closes a part of the intake passage of the internal combustion engine is provided. By closing the air intake and narrowing the flow path of the intake air to increase the flow velocity, the strength of the airflow in the cylinder (eg, tumble flow or swirl flow) is increased to promote the homogenization of the air-fuel mixture .

  However, in the partial range (partial load range), which is the most frequently used in the operating range of the internal combustion engine, when the rotational speed of the internal combustion engine increases and the intake air amount increases, the intake air resistance causes the intake resistance due to the intake throttle effect. However, the pumping loss increases and the fuel consumption tends to deteriorate.

As a technique for reducing the pumping loss due to such an airflow control valve, as described in Japanese Patent Application Laid-Open No. 2006-161633, the intake air amount is controlled by changing the lift amount of the intake valve. In some internal combustion engines, the opening degree of the airflow control valve is changed according to the opening degree (lift amount) of the intake valve that opens and closes for each intake stroke.
JP 2006-161633 A (2nd to 6th pages, FIG. 3 etc.)

  During operation of the internal combustion engine, since the intake valve is opened and closed at high speed for each intake stroke, air flow control is performed in synchronization with the change in the opening (lift amount) of the intake valve for each intake stroke, as in Patent Document 1 described above. In order to realize a configuration in which the opening degree of the valve is changed at high speed, it is necessary to change the design of the opening / closing drive mechanism of the airflow control valve, which is considered to increase the cost considerably. Moreover, if the opening degree of the airflow control valve is changed at high speed for each intake stroke, the flow of air passing through the airflow control valve is disturbed, the intake resistance is increased, and the pumping loss reduction effect is reduced. In addition, there is a delay time until the air that has passed through the airflow control valve reaches the intake valve, and this delay time changes depending on the flow velocity of the intake air, so that it accurately synchronizes with the change in the intake valve opening for each intake stroke Even if the opening degree of the airflow control valve is changed at a high speed, it is difficult to obtain a sufficient pumping loss reduction effect.

  In general, the smaller the opening of the airflow control valve and the stronger the airflow, the better the combustion state and the faster the combustion speed. Therefore, the optimal ignition timing (MBT) is set according to the opening of the airflow control valve. As a result, when the difference between the actual ignition timing and the optimum ignition timing becomes large, the fuel consumption deteriorates. However, Patent Document 1 does not have any description regarding the control of the ignition timing.

  The present invention has been made in consideration of such circumstances. Accordingly, the object of the present invention is to realize a reduction in pumping loss and optimization of the ignition timing in the partial region at a low cost. Another object of the present invention is to provide a control device for an internal combustion engine that can increase the fuel consumption reduction effect of the airflow control valve.

  In order to achieve the above object, an invention according to claim 1 provides a control device for an internal combustion engine that controls the airflow intensity in a cylinder by adjusting the opening degree of an airflow control valve provided in an intake passage of the internal combustion engine. The airflow control valve controls the opening degree of the airflow control valve according to the rotational speed of the internal combustion engine, and the ignition timing control means controls the ignition delay amount with respect to the reference ignition timing according to the airflow control valve opening degree. It is what I did.

  In this configuration, since the opening degree of the airflow control valve is controlled according to the rotational speed of the internal combustion engine, the opening degree of the airflow control valve corresponds to the increase in the intake air amount due to the increase in the rotational speed of the internal combustion engine. Can be controlled in the direction in which the intake resistance is reduced (open side), and the pumping loss in the partial region by the airflow control valve can be reduced. Moreover, since the ignition delay amount with respect to the reference ignition timing is controlled according to the opening degree of the airflow control valve, the ignition timing is set in response to the change of the optimal ignition timing (MBT) due to the opening degree change of the airflow control valve. It becomes possible to correct the deviation from the optimum ignition timing so that the fuel consumption reduction effect in the partial region can be increased at a low cost in combination with the above-described pumping loss reduction effect.

  Specifically, as described in claim 2, the opening degree of the airflow control valve is set to the open side as the rotational speed of the internal combustion engine increases, and the ignition delay with respect to the reference ignition timing is set as the opening degree of the airflow control valve becomes open side. What is necessary is just to make an angular amount small. Thus, if the opening degree of the airflow control valve is set to the open side as the rotational speed of the internal combustion engine increases, the airflow control valve within a range where the intake resistance (pumping loss) by the airflow control valve does not become excessive in the partial region. Is set to the closed side, and the combustion improvement effect by the airflow control valve can be obtained. Also, the more the airflow control valve opening is on the open side, the weaker the airflow is, the slower the combustion speed is, and the optimal ignition timing is shifted to the advance side. If the ignition delay amount with respect to the ignition timing is reduced, the ignition timing can be corrected so as to approach the optimum ignition timing, and the fuel consumption reduction effect can be increased.

  Further, the opening degree of the airflow control valve may be controlled according to the rotational speed and load (intake pipe pressure, intake air amount, fuel injection amount, etc.) of the internal combustion engine. By using both the rotational speed and load of the internal combustion engine, it is possible to more accurately evaluate the intake resistance (pumping loss) and combustion state of the airflow control valve, so airflow control according to the rotational speed and load of the internal combustion engine If the opening degree of the valve is controlled, the opening degree of the air flow control valve in the partial region can be controlled more accurately.

  Further, as in claim 4, when the rotational speed of the internal combustion engine is equal to or greater than the predetermined value A or the load is equal to or greater than the predetermined value B, the opening degree of the airflow control valve is set to be equal to or greater than the predetermined value C (preferably fully open). It is good to make it. In this way, the airflow control valve opening can be increased in the high rotation / high load range to reduce the intake resistance (pumping loss) by the airflow control valve, and the fuel consumption in the high rotation / high load range can be reduced. Can be improved.

  Further, the opening degree of the airflow control valve may be corrected according to the warm-up state of the internal combustion engine and / or the throttle opening degree. Before warming up the internal combustion engine, atomization of the injected fuel is less likely to be accelerated than after warming up.If the airflow control valve opening is corrected to the closed side before warming up, the airflow strength is increased. The atomization of the injected fuel can be promoted to improve the combustion state. Also, as the throttle opening increases, the amount of intake air increases. Therefore, if the opening of the airflow control valve is corrected so that the intake resistance decreases (open side) as the throttle opening increases, in the partial range. The increase in pumping loss due to the airflow control valve can be suppressed.

  The airflow control valve and ignition timing control according to the present invention described above may be prohibited during idling operation of the internal combustion engine (claim 6). This is because during the idling operation of the internal combustion engine, the rotation speed of the internal combustion engine is controlled to the target idle rotation speed, so that performing control different from the control in the partial range leads to stabilization of idle rotation and reduction of emissions. .

Hereinafter, an embodiment embodying the best mode for carrying out the present invention will be described.
First, a schematic configuration of the entire engine control system will be described with reference to FIG.
An air cleaner 13 is provided at the most upstream portion of the intake pipe 12 of the engine 11 that is an internal combustion engine, and an air flow meter 14 that detects the intake air amount is provided downstream of the air cleaner 13. A throttle valve 16 whose opening is adjusted by a motor 15 and a throttle opening sensor 17 for detecting the opening (throttle opening) of the throttle valve 16 are provided on the downstream side of the air flow meter 14.

  Further, a surge tank 18 is provided on the downstream side of the throttle valve 16, and an intake pipe pressure sensor 19 for detecting the intake pipe pressure PM is provided in the surge tank 18. The surge tank 18 is provided with an intake manifold 20 that introduces air into each cylinder of the engine 11, and a downstream portion of the intake manifold 20 of each cylinder is connected to an intake port 29 of each cylinder.

  A partition plate 30 is provided downstream of the intake manifold 20 of each cylinder so as to partition the intake passage vertically. An upper passage 31 and a lower passage 32 are partitioned by the partition plate 30. A tumble control valve 33 (air flow control valve) that opens and closes the lower passage 32 is provided at the inlet of the lower passage 32 of each cylinder, and the tumble control valve (hereinafter referred to as “TCV”) 33 is closed. In this way, the intake air is caused to flow through the upper passage 31 to increase the flow velocity of the intake air, thereby increasing the strength of the tumble flow in the cylinder (vertical intake swirl flow) and promoting the homogenization of the air-fuel mixture. I try to improve.

  The TCV 33 of each cylinder is driven to open and close by a common motor (not shown) so that the opening of the TCV 33 is adjusted between a fully open position (for example, 0 °) and a fully closed position (for example, 90 °). It has become. The TCV 33 may be driven to open and close by an individual motor for each cylinder or each cylinder group.

  Further, a fuel injection valve 21 for injecting fuel is attached to the downstream side of the TCV 33 of each cylinder, and a spark plug 22 is attached to the cylinder head of the engine 11 for each cylinder. The air-fuel mixture in the cylinder is ignited by the discharge.

  On the other hand, the exhaust pipe 23 of the engine 11 is provided with an exhaust gas sensor 24 (air-fuel ratio sensor, oxygen sensor, etc.) for detecting the air-fuel ratio or rich / lean of the exhaust gas. A catalyst 25 such as a three-way catalyst for purifying gas is provided.

  A cooling water temperature sensor 26 that detects the cooling water temperature and a crank angle sensor 27 that outputs a pulse signal each time the crankshaft of the engine 11 rotates a predetermined crank angle are attached to the cylinder block of the engine 11. Based on the output signal of the crank angle sensor 27, the crank angle and the engine speed NE are detected.

  Outputs of these various sensors are input to a control circuit (hereinafter referred to as “ECU”) 28 for engine control. The ECU 28 is mainly composed of a microcomputer, and executes various engine control programs stored in a built-in ROM (storage medium), so that the fuel injection amount of the fuel injection valve 21 can be changed according to the engine operating state. The ignition timing of the spark plug 22 is controlled, and the opening of the TCV 33 is controlled according to the engine operating state.

Here, the fuel consumption reduction effect by the TCV 33 in the partial region will be described with reference to FIGS. 2 and 3.
FIG. 2 is a diagram showing the fuel consumption reduction effect of TCV33 (opening ratio 30%) when the engine rotation speed is 1600 rpm and no load compared to when TCV is not present (when TCV33 is fully open). If the intake air flow path is narrowed by the TCV 33 to increase the strength of the airflow, the air-fuel mixture is homogenized and the combustion state is improved. In this experimental example, the engine speed is 1600 rpm and no load is applied. In this case, at the optimal ignition timing (MBT), a fuel efficiency reduction effect of 2.5% was obtained by TCV33 (opening ratio 30%) as compared with the case without TCV.

  However, in the partial range (partial load range), which is the most frequently used in the engine operating range, when the engine speed increases and the intake air amount increases, the intake air resistance increases due to the intake throttle effect by the TCV 33, resulting in a pumping loss. However, the fuel consumption tends to deteriorate.

  As a countermeasure, in this embodiment, the opening degree of the TCV 33 is set to the open side as the engine speed increases. In this way, it is possible to control the opening of the TCV 33 in a direction (open side) in which the intake resistance decreases in response to the increase in the engine speed and the intake air amount. Pumping loss in the partial area can be reduced.

  Similarly, as the engine load (intake pipe pressure, intake air amount, fuel injection amount, etc.) increases, the opening of the TCV 33 is set to the open side. In this way, it is possible to control the opening of the TCV 33 in a direction (open side) in which the intake resistance decreases in response to an increase in engine load, and an increase in pumping loss accompanying an increase in engine load. Can be suppressed.

  FIG. 3 is a graph showing the fuel consumption reduction effect of TCV33 (opening ratio 30%) at an engine rotation speed of 1600 rpm and a vehicle speed of 20 km / h compared to when TCV is not present (when TCV33 is fully open). In this experimental example, when the engine rotation speed is 1600 rpm and the vehicle speed is 20 km / h, the fuel consumption is reduced by about 1.5% by TCV33 (opening ratio 30%) at the optimal ignition timing (MBT) compared with the case without TCV. The effect was obtained.

  In this case, as the opening of the TCV 33 is reduced and the strength of the airflow is increased, the combustion state is improved and the combustion speed is increased. Therefore, the optimal ignition timing (MBT) changes according to the opening of the TCV 33, As a result, when the difference between the actual ignition timing and the optimum ignition timing becomes large, the fuel consumption deteriorates.

  Therefore, in this embodiment, the ignition retard amount with respect to the reference ignition timing is reduced as the opening of the TCV 33 is opened. As the opening of the TCV 33 becomes the opening side, the strength of the airflow becomes weaker and the combustion speed becomes slower, and the optimum ignition timing shifts to the advance side. Therefore, as the opening of the TCV 33 becomes the opening side, the ignition delay with respect to the reference ignition timing. If the amount is reduced, the ignition timing can be corrected so as to approach the optimum ignition timing, and the fuel consumption reduction effect can be increased.

  The opening control and ignition timing control of the TCV 33 in the partial region of the present embodiment described above are executed by the ECU 28 as follows according to the TCV opening / ignition timing control routine of FIG. The TCV opening / ignition timing control routine of FIG. 4 is executed at a predetermined cycle while the ECU 28 is powered on, and functions as an airflow control means and an ignition timing control means in the claims. When this routine is started, it is first determined in step 101 whether or not the IG switch (ignition switch) is turned on. If the IG switch is turned off, this routine is executed without performing the subsequent processing. finish.

  On the other hand, if it is determined in step 101 that the IG switch is ON, the process proceeds to step 102, where it is determined whether or not the start is completed. If the start is not completed (during start), the TCV 33 is closed. The routine is terminated with the predetermined opening being fixed.

  Thereafter, when it is determined in step 102 that the start is completed, the process proceeds to step 104, where it is determined whether the idle switch is OFF (whether it is a partial area), and the idle switch is ON (idle If it is determined that the operation is in progress, the routine is terminated without performing the subsequent processing. The processing in step 104 serves as prohibition means in the claims.

  On the other hand, if it is determined in step 104 that the idle switch is OFF (partial range), the process proceeds to step 105 where the engine speed NE is less than a predetermined value A and the engine load (for example, intake pipe pressure PM) is predetermined. It is determined whether or not the value is less than B. As a result, if it is determined that the engine speed NE is greater than or equal to the predetermined value A or the engine load PM is greater than or equal to the predetermined value B, the process proceeds to step 106 and the opening of the TCV 33 is fixed at the fully open position. In addition, you may fix the opening degree of TCV33 to the predetermined opening degree (opening more than the predetermined value C) close | similar to a fully open position. In this way, the opening of the TCV 33 can be increased in the high rotation / high load range to reduce the intake resistance (pumping loss) by the TCV 33, and the fuel efficiency in the high rotation / high load range can be improved.

  Thereafter, when the engine speed NE is less than the predetermined value A and the engine load PM is less than the predetermined value B, the routine proceeds to step 107, where the engine speed NE and the engine load PM shown in FIG. 5 are used as parameters. With reference to the TCV opening map, the opening of the TCV 33 is set according to the current engine speed NE and the engine load PM. The TCV opening degree map of FIG. 5 is created so that the opening degree of the TCV 33 is set to the open side as the engine speed NE increases, and the opening degree of the TCV 33 is set to the opening side as the engine load PM increases. Yes. As a result, the opening of the TCV 33 can be controlled in a direction (open side) in which the intake resistance is reduced in response to the increase in the engine speed NE and the intake air amount. The pumping loss at can be reduced.

  Thereafter, the routine proceeds to step 108, where the ignition delay amount map with the opening degree of the TCV 33 shown in FIG. 6 as a parameter is set, and the ignition delay amount with respect to the reference ignition timing is set according to the current opening degree of the TCV 33. . The ignition delay amount map of FIG. 6 is created so that the ignition delay amount with respect to the reference ignition timing is set to be smaller as the opening of the TCV 33 is opened. As the opening of the TCV 33 is on the open side, the strength of the airflow is weakened and the combustion speed is slowed down, and the optimum ignition timing (MBT) is shifted to the advance side, so that the opening of the TCV 33 is on the open side, If the ignition retard amount is reduced, the ignition timing can be corrected in a direction approaching the optimal ignition timing, and the fuel consumption reduction effect can be increased.

  An example of the opening degree control and ignition timing control of the TCV 33 in the partial range of the present embodiment described above will be described with reference to FIG. In the example of FIG. 7, the opening of the TCV 33 is fixed to be fully closed (for example, 90 °) during idle operation. Then, at the time t1 when the throttle opening is opened and the IG switch is turned off, the control shifts to partial area control. In the partial range, as the engine speed NE increases, the opening degree of the TCV 33 is set to the opening side, and as the engine load PM increases, the opening degree of the TCV 33 is set to the opening side, and the opening degree of the TCV 33 is set to the opening side. The ignition delay amount with respect to the reference ignition timing is set to be smaller.

  Then, at the time t2 when the engine rotational speed NE becomes equal to or higher than the predetermined value A, the opening degree of the TCV 33 is fixed fully open (for example, 0 °). Thereafter, at the time point t3 when the engine speed NE drops below the predetermined value A, the above-described partial range control is resumed, the opening of the TCV 33 is set according to the engine speed NE and the engine load PM, and the reference ignition is performed. The ignition retard amount with respect to the timing is set according to the current opening of the TCV 33. As a result, during the period from t4 to t5, the opening of the TCV 33 is set to 30 °, the ignition delay amount with respect to the reference ignition timing is set to 5 ° C. from the map of FIG. 6, and after t6, the opening of the TCV 33 is set. Is set to 60 °, and the ignition delay amount with respect to the reference ignition timing is set to 7 ° C. from the map of FIG.

  In the present embodiment described above, in the partial range, the opening degree of the TCV 33 is set to the open side as the engine rotational speed NE increases, and the opening degree of the TCV 33 is set to the open side as the engine load PM increases. As a result, the opening of the TCV 33 can be controlled in a direction (open side) in which the intake resistance decreases in response to the increase in the engine speed NE and the intake air amount. The pumping loss at can be reduced. In addition, since the ignition delay amount with respect to the reference ignition timing is set to be smaller as the opening degree of the TCV 33 becomes the opening side, the combustion speed becomes slower as the opening degree of the TCV 33 becomes the opening side, and the optimal ignition timing (MBT). Corresponding to the shift to the advance side, the ignition timing can be corrected so as to approach the optimal ignition timing, and the fuel consumption reduction effect can be increased.

  In this embodiment, the opening of the TCV 33 is set according to the engine speed NE and the engine load PM. However, the opening of the TCV 33 is set according to the warm-up state of the engine 11 and / or the throttle opening. You may make it correct | amend. Before the engine 11 is warmed up, atomization of the injected fuel is less likely to be accelerated than after the engine is warmed up. Therefore, if the opening of the TCV 33 is corrected to the closed side before the engine is warmed up, Fuel atomization can be promoted to improve the combustion state. Further, since the intake air amount increases as the throttle opening increases, the TCV 33 in the partial region can be corrected by correcting the opening of the TCV 33 in a direction (open side) in which the intake resistance decreases as the throttle opening increases. The increase of the pumping loss due to can be suppressed.

  In the present embodiment, the present invention is applied to a system including a tumble control valve 33 that generates a tumble flow (longitudinal intake swirl flow) in the cylinder. However, a swirl flow (lateral intake swirl flow) is generated in the cylinder. The present invention may be applied to a system including a swirl control valve that generates the above.

It is a schematic block diagram of the whole engine control system in one Example of this invention. It is a figure which shows the fuel consumption reduction effect of TCV (opening ratio 30%) at the time of engine load speed 1600rpm and no load compared with the time of TCV absence (at the time of TCV full open). It is a figure which shows the fuel consumption reduction effect of TCV (opening ratio 30%) at the engine speed of 1600 rpm and a vehicle speed of 20 km / h in comparison with no TCV (when TCV is fully open). It is a flowchart which shows the flow of a process of TCV opening degree and ignition timing control routine. It is a figure which shows an example of the TCV opening degree map which uses engine speed NE and engine load PM as parameters. It is a figure which shows an example of the ignition retard amount map which makes a TCV opening degree a parameter. It is a time chart explaining an example of TCV opening degree control in the partial region, and control of ignition timing.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Intake pipe, 16 ... Throttle valve, 21 ... Fuel injection valve, 22 ... Spark plug, 23 ... Exhaust pipe, 26 ... Cooling water temperature sensor, 27 ... Crank angle sensor, 28 ... ECU ( Airflow control means, ignition timing control means, prohibition means), 33 ... tumble control valve (airflow control valve)

Claims (6)

In the control device for an internal combustion engine that controls the airflow intensity in the cylinder by adjusting the opening degree of the airflow control valve provided in the intake passage of the internal combustion engine,
Airflow control means for controlling the opening of the airflow control valve in accordance with the rotational speed of the internal combustion engine;
An internal combustion engine control device comprising: an ignition timing control means for controlling an ignition delay amount with respect to a reference ignition timing in accordance with an opening of the airflow control valve. The air flow control means sets the opening of the air flow control valve to the open side as the rotational speed of the internal combustion engine increases,
2. The control device for an internal combustion engine according to claim 1, wherein the ignition timing control unit decreases an ignition delay amount with respect to the reference ignition timing as the opening of the airflow control valve is opened.   3. The control device for an internal combustion engine according to claim 1, wherein the air flow control unit controls an opening degree of the air flow control valve in accordance with a rotation speed and a load of the internal combustion engine.   The airflow control means sets the opening degree of the airflow control valve to a predetermined value C or more when the rotational speed of the internal combustion engine is a predetermined value A or more or the load is a predetermined value B or more. The control device for an internal combustion engine according to claim 3.   5. The internal combustion engine according to claim 1, wherein the air flow control unit corrects an opening degree of the air flow control valve in accordance with a warm-up state of the internal combustion engine and / or a throttle opening degree. Control device.   6. The control device for an internal combustion engine according to claim 1, further comprising prohibiting means for prohibiting control by the airflow control means and the ignition timing control means during idle operation of the internal combustion engine. .

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