JP2005207285A - Internal combustion engine control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine control device capable of keeping excellent combustion of an internal combustion engine while preventing lowering of fuel efficiency even when an EGR control valve is opened and fixed. <P>SOLUTION: The internal combustion engine control device controls the internal combustion engine having an exhaust gas recirculation function of recirculating exhaust gas from an exhaust passage 4 to an intake passage 3 through an exhaust gas passage 5. When the EGR valve 51 for opening/closing the exhaust gas passage 5 is opened and fixed, a combustion state of the internal combustion engine is improved by improving the combustion by increase of a turning flow or the like in comparison with that before opening fixation thereof. Thus, combustibility can be improved without increasing fuel injection, and the excellent combustion of the internal combustion engine can be kept, while the lowering of the fuel economy is prevented. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an internal combustion engine control device that controls an internal combustion engine mounted on a vehicle.

Conventionally, as related to internal combustion engine control, as described in Japanese Patent No. 3321837, an abnormality of an EGR (Exhaust Gas Recirculation) valve is detected, and the operating state of the internal combustion engine is changed and controlled based on the detection result In this case, the type of abnormality of the EGR valve is diagnosed, it is determined that the abnormality is in the opening direction while the EGR valve is open, and if there is no fresh air leakage, the air-fuel ratio is corrected to the rich side. Are known.
Japanese Patent No. 3321737

  In such an internal combustion engine control device, there is a problem that fuel consumption deteriorates. That is, the fuel supplied to the internal combustion engine is increased by correcting the air-fuel ratio to the rich side. As a result, the combustion state is stabilized, but it is inevitable that the fuel consumption decreases.

  Therefore, an object of the present invention is to provide an internal combustion engine control apparatus that can maintain good combustion of an internal combustion engine while preventing a reduction in fuel consumption even when an EGR control valve is fixed open.

  That is, an internal combustion engine control apparatus according to the present invention is an internal combustion engine control apparatus that controls an internal combustion engine having an exhaust gas recirculation function that recirculates exhaust gas from an exhaust path to an intake path through an exhaust gas path. Combustion improving means for improving the combustion state is provided, and the combustion state of the internal combustion engine is improved by the combustion improving means when the exhaust gas recirculation valve for opening and closing the exhaust gas passage is fixed open.

  According to the present invention, when the exhaust gas recirculation valve is stuck open, the combustion state is improved by the combustion improving means. As a result, the combustion state of the internal combustion engine can be kept good without increasing the fuel supply amount.

  In the internal combustion engine control apparatus according to the present invention, the combustion improving means described above is a swirl flow control means for controlling the swirl flow in the combustion chamber of the internal combustion engine. Compared to the above, the swirl flow is increased to improve the combustion state.

  According to the present invention, when the exhaust gas recirculation valve is stuck open, the combustion state can be improved without increasing the fuel supply amount by increasing the swirl flow as compared to before the open sticking. For this reason, it is possible to maintain good combustion of the internal combustion engine while preventing a reduction in fuel consumption.

  Further, the internal combustion engine control apparatus according to the present invention is a variable valve control means for controlling the valve opening characteristics of the internal combustion engine by the combustion improving means described above, and when the exhaust gas recirculation valve is stuck open, The valve opening characteristic is controlled so that the overlap is reduced as compared with the above.

  According to the present invention, when the exhaust gas recirculation valve is stuck open, the valve opening characteristic is controlled so that the overlap is reduced as compared to before the open sticking, so that the fuel supply amount is not increased. The combustion state can be improved. For this reason, it is possible to maintain good combustion of the internal combustion engine while preventing a reduction in fuel consumption.

  An internal combustion engine control apparatus according to the present invention is an internal combustion engine control apparatus for controlling an internal combustion engine having an exhaust gas recirculation function for recirculating exhaust gas from an exhaust path to an intake path through an exhaust gas path. Intake amount increasing means for increasing the amount of intake air per unit, and when the exhaust gas recirculation valve that opens and closes the exhaust gas passage is fixed open, the amount of intake air sucked into the internal combustion engine is increased by the intake amount increasing means It is characterized by.

  According to this invention, when the exhaust gas recirculation valve is stuck open, the intake air amount is increased, so that the combustion state can be improved without decreasing the EGR rate and increasing the fuel supply amount. For this reason, it is possible to maintain good combustion of the internal combustion engine while preventing a reduction in fuel consumption.

  The internal combustion engine control apparatus according to the present invention is characterized in that the intake air amount increasing means causes the internal combustion engine to perform a reduced cylinder operation when the exhaust gas recirculation valve is stuck open.

  In this case, it is preferable to perform the injection cut at a part of the cylinders in the internal combustion engine. Further, the injection cut may be performed at a predetermined timing in the cylinder of the internal combustion engine. Further, the valve operation may be stopped at a part of the cylinders in the internal combustion engine.

  According to the present invention, when the exhaust gas recirculation valve is stuck open, the internal combustion engine is reduced in cylinder operation, and the intake air amount per cylinder is increased, thereby reducing the EGR rate and increasing the fuel supply amount. The combustion state can be improved without any problems. For this reason, it is possible to maintain good combustion of the internal combustion engine while preventing a reduction in fuel consumption.

  The internal combustion engine control device according to the present invention is characterized in that the intake air amount increasing means changes the shift point of the automatic transmission to the high speed side when the exhaust gas recirculation valve is stuck open.

  According to the present invention, when the exhaust gas recirculation valve is fixed open, the shift point of the automatic transmission is changed to the high speed side, thereby improving the combustion state without decreasing the EGR rate and increasing the fuel supply amount. Can be made. For this reason, it is possible to maintain good combustion of the internal combustion engine while preventing a reduction in fuel consumption.

  According to the present invention, even when the EGR valve is stuck open, combustion of the internal combustion engine can be kept good while preventing a reduction in fuel consumption.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.
(First embodiment)
FIG. 1 shows a schematic configuration diagram of an internal combustion engine control apparatus according to this embodiment.

  As shown in FIG. 1, an internal combustion engine control device 1 according to the present embodiment is a device that controls an engine 2 that is an internal combustion engine mounted on a vehicle. The engine 2 has an EGR (Exhaust Gas Recirculation) function. An exhaust gas passage 5 is provided between the intake passage 3 and the exhaust passage 4 of the engine 2. The exhaust gas passage 5 is a path through which exhaust gas discharged from the engine 2 to the exhaust path 4 is returned to the intake path 3 and recirculated. An EGR valve 51 is provided in the middle of the exhaust gas passage 5.

  The EGR valve 51 is a valve body that communicates and closes the exhaust gas passage 5 by opening and closing the EGR valve 51. For example, the EGR valve 51 is, for example, a normally closed valve that opens when the pressure difference between the exhaust path 4 and the intake path 3 becomes a predetermined value or more. The EGR valve 51 may be controlled to be opened and closed by the ECU 6. It is preferable to incorporate a valve open / close detection sensor 52 in the EGR valve 51 so that the open / closed state of the EGR valve 51 can be detected. In this case, the output signal of the valve opening / closing detection sensor 52 is input to the ECU 6.

  An EGR gas temperature sensor 53 is installed between the EGR valve 51 and the intake path 3 in the exhaust gas passage 5. The EGR gas temperature sensor 53 functions as an EGR gas temperature detecting means for detecting the temperature of the exhaust gas returned from the exhaust path 4.

  A throttle valve 31 is installed in the intake path 3. The throttle opening of the throttle valve 31 is detected by a throttle position sensor 32. The output signal of the throttle position sensor 32 is input to the ECU 6. Further, an ISC (Idle Speed Control) valve 33 is installed in the intake path 3. The ISC valve 33 is provided in a bypass path 34 formed across the throttle valve 31. The idle speed can be increased by opening the ISC valve 33, and the idle speed can be decreased by closing the ISC valve 33. The ECU 6 opens and closes the ISC valve 33.

  A swirl port 35 is formed in the intake port of the engine 2. The swirl port 35 swirls the intake air in a vortex in the combustion chamber. A swirl control valve 36 is provided at the intake port. The strength of the swirling flow can be controlled by opening and closing the swirl control valve 36. The swirl control valve 36 opens and closes according to the operation of the swirl control actuator 37. The swirl control actuator 37 is driven by receiving a control signal from the EUC 6.

  The engine 2 is provided with a crank position sensor 21 that detects the engine speed and a water temperature sensor 22 that detects the temperature of the engine 2. Output signals of the crank position sensor 21 and the water temperature sensor 22 are input to the ECU 6. The engine 2 includes a variable valve mechanism 23. The variable valve mechanism 23 can change the valve opening characteristics of the intake valve 24 and is controlled by the ECU 6.

  The ECU 6 controls the entire apparatus, and is configured mainly by a computer including a CPU, a ROM, and a RAM, for example.

  Next, the operation of the internal combustion engine control apparatus according to this embodiment will be described.

  FIG. 2 is a flowchart showing the operation of the internal combustion engine control apparatus according to the present embodiment. The control process in FIG. 2 is repeatedly executed by the ECU every predetermined time.

  As shown at S10 in FIG. 2, it is determined whether or not the EGR valve 51 has an abnormal operation. This determination is made based on the output of the EGR gas temperature sensor 53, for example. If the output of the EGR gas temperature sensor 53 indicates a temperature higher than a predetermined value when the EGR valve 51 is to be closed, it is determined that the EGR valve 51 is stuck open and malfunctioning. The open sticking means a failure state in which the valve body is not opened and closed.

  On the other hand, if the output of the EGR gas temperature sensor 53 indicates a temperature lower than a predetermined value when the EGR valve 51 should be opened, it is determined that the EGR valve 51 is closed and stuck to cause an abnormal operation. Closed fixation means a failure state in which the valve body is not opened while closed. Whether the operation of the EGR valve 51 is abnormal may be determined based on the output of the valve opening / closing detection sensor 52.

  When it is determined in S10 that the EGR valve 51 is not operating abnormally, normal swirl control is performed (S12). In normal swirl control, for example, when the engine water temperature is equal to or lower than a predetermined temperature, the engine is idling, and the transmission is neutral, the swirl control valve 36 is closed and the swirl flow in the combustion chamber is increased. On the other hand, when the engine water temperature is not lower than the predetermined temperature, the engine is not idling, or the transmission is not neutral, the swirl control valve 36 is opened and the swirl flow in the combustion chamber is reduced.

  On the other hand, when it is determined in S10 that the EGR valve 51 is malfunctioning, it is determined whether or not the EGR valve 51 is in the open fixed state (S14). When it is determined that the EGR valve 51 is not in the open fixed state, the process proceeds to S12. When it is determined that the EGR valve 51 is in the open fixed state, the valve timing of the intake valve 24 is controlled so as to be the most retarded (S16). This most retarded angle control is performed by outputting a control signal from the ECU 6 to the variable valve mechanism 23. By performing the most retarded angle control, the overlap between the exhaust valve, the intake valve 24 and the exhaust valve opening at the same time is reduced, and so-called internal EGR can be reduced.

  Then, the process proceeds to S18 to determine whether or not idling is in progress. If it is determined that the vehicle is idling, the process proceeds to S22. On the other hand, when it is determined that the engine is not idling, it is determined whether or not the engine 2 is operated in a light load state (S20). This determination is made based on, for example, the throttle opening. When it is determined in S20 that the engine 2 is not operated in a light load state, the control process is terminated. On the other hand, when it is determined that the engine 2 is operating in a light load state, the process proceeds to S22.

  In S22, valve closing control of the swirl control valve 36 is performed. This valve closing control is a control process for closing the swirl control valve 36 and increasing the swirling flow. By this valve closing control, the swirl flow in the combustion chamber is increased and the combustibility is improved. In S22, control other than swirl valve closing control may be performed as long as the swirl flow is increased to improve combustibility. And a control process is complete | finished after completion | finish of S22.

  As described above, according to the internal combustion engine control device according to the present embodiment, when the EGR valve 51 is stuck open, the swirl flow is increased as compared to before the open sticking. For this reason, the combustion state can be improved without increasing the fuel supply amount, and the combustion of the internal combustion engine can be kept good while preventing the fuel consumption from decreasing. In addition, misfire, engine stall, and catalyst melting damage at the time of failure can be prevented, and a situation in which self-running to the repair shop is hindered can be prevented.

  Further, according to the internal combustion engine control apparatus according to the present embodiment, when the EGR valve 51 is fixed open, overlap of the simultaneous opening in the intake valve 24 and the exhaust valve 25 is reduced as compared to before the open fixing. For this reason, internal EGR by overlap can be reduced and a combustion state can be improved, without increasing fuel supply amount. Therefore, it is possible to maintain good combustion of the internal combustion engine while preventing a reduction in fuel consumption. In addition, misfire, engine stall, and catalyst melting damage at the time of failure can be prevented, and a situation in which self-running to the repair shop is hindered can be prevented.

  In this embodiment, the overlap is reduced by the most retarded angle control of the intake valve 24. However, although it is not the most retarded angle control, the valve opening timing of the intake valve 24 is delayed compared to before the open fixing. The wrap may be reduced. Moreover, the valve lift amount of the intake valve 24 may be controlled to reduce overlap. Furthermore, the valve opening characteristic of the exhaust valve 25 may be controlled to reduce overlap.

Further, in this embodiment, when the EGR valve 51 is stuck open, the combustion state of the engine 2 is improved by the swirl flow control and the valve opening control compared to before the sticking open, but the combustion state of the engine 2 is improved. If it can be made, the combustion state may be improved by other control or the like. In addition, one of the swirl flow control process or the valve opening control process may be executed.
(Second embodiment)
Next, an internal combustion engine control apparatus according to the second embodiment will be described.

  FIG. 3 is a flowchart showing the operation of the internal combustion engine control apparatus according to this embodiment. The internal combustion engine control apparatus according to the present embodiment has the same hardware configuration as the internal combustion engine control apparatus of the first embodiment shown in FIG.

  Based on FIG. 3, the operation of the internal combustion engine control apparatus according to the present embodiment will be described. The control process in FIG. 3 is repeatedly executed by the ECU 6 every predetermined time. As shown in S30 in FIG. 3, it is determined whether or not the EGR valve 51 has an abnormal operation. This determination is made based on the output of the EGR gas temperature sensor 53, for example. If the output of the EGR gas temperature sensor 53 indicates a temperature higher than a predetermined value when the EGR valve 51 is to be closed, it is determined that the EGR valve 51 is stuck open and malfunctioning. The open sticking means a failure state in which the valve body is not opened and closed.

  On the other hand, if the output of the EGR gas temperature sensor 53 indicates a temperature lower than a predetermined value when the EGR valve 51 should be opened, it is determined that the EGR valve 51 is closed and stuck to cause an abnormal operation. Closed fixation means a failure state in which the valve body is not opened while closed. Whether the operation of the EGR valve 51 is abnormal may be determined based on the output of the valve opening / closing detection sensor 52.

  If it is determined in S30 that the EGR valve 51 is not operating abnormally, the control process is terminated. On the other hand, when it is determined in S30 that the EGR valve 51 is malfunctioning, it is determined whether or not the EGR valve 51 is in the open fixing state (S32). When it is determined that the EGR valve 51 is not in the open fixed state, the control process is terminated. When it is determined that the EGR valve 51 is in the open fixing state, it is determined whether or not the engine is idling (S34). When it is determined that the engine is not idling, the process proceeds to S38. On the other hand, when it is determined that the engine is idling, an ISC opening increase process is performed (S36).

  The ISC opening degree increasing process is a process for increasing the opening number of the ISC valve 33 to increase the idle speed. By performing this ISC opening increase process, the amount of air taken into the combustion chamber through the intake passage 3 increases, so that the EGR rate can be reduced and misfire and engine stall can be prevented.

  And it transfers to S38 and an injection cut process is performed. The injection cut process is a process for reducing fuel injection in the cylinders of the engine 2. For example, fuel injection is cut for some of the cylinders. Further, fuel injection may be cut at predetermined timings in the cylinders of the engine 2. By performing such an injection cut process, the amount of air taken into the combustion chamber through the intake passage 3 increases, so that the EGR rate can be reduced and misfire and engine stall can be prevented.

  Then, the process proceeds to S40, and an AT shift change process is performed. This AT shift changing process is a process of changing a shift point at which the gear ratio is switched in the automatic transmission, and changes the shift point so that it is easy to shift up and shift down. By performing this AT shift change processing, the driver performs an accelerator operation so that the throttle opening is opened in the vehicle operation, so that EGR can be reduced and misfire and engine stall can be prevented. After the end of S40, the control process ends.

  As described above, according to the internal combustion engine control apparatus according to the present embodiment, when the EGR valve 51 is fixed open, injection is cut at a part of the cylinder in the engine 2 or at every predetermined timing in the cylinder in the engine 2. Reduce the cylinder operation by cutting the injection. As a result, a large amount of new air is sucked through the intake passage 3 and the EGR rate is lowered, so that the combustion state can be improved without increasing the fuel supply amount. For this reason, it is possible to maintain good combustion of the internal combustion engine while preventing a decrease in fuel consumption. In addition, misfire, engine stall, and catalyst melting damage at the time of failure can be prevented, and a situation in which self-running to the repair shop is hindered can be prevented.

  Further, according to the internal combustion engine control apparatus according to the present embodiment, when the EGR valve 51 is stuck open, the shift point in the automatic transmission is changed to the high speed side compared with before the open sticking, so that the driver can Since the accelerator operation is performed so as to open the throttle opening, the intake air amount of fresh air can be increased and the EGR rate can be reduced. Therefore, it is possible to maintain good combustion of the internal combustion engine while preventing a reduction in fuel consumption. In addition, misfire, engine stall, and catalyst melting damage at the time of failure can be prevented, and a situation in which self-running to the repair shop is hindered can be prevented.

  In the present embodiment, the description has been given of the case where the intake air amount is increased by the injection cut or the AT shift change when the EGR valve 51 is fixed open, but the intake air amount is increased by other control or the like. Also good. For example, the valve operation may be stopped at a part of the cylinders in the engine 2 to perform the reduced cylinder operation, and the intake air amount per cylinder may be increased by the reduced cylinder operation to decrease the EGR rate.

  Further, in the control process shown in FIG. 3 of the present embodiment, not all the ISC opening increase process, the injection cut process, and the AT shift change process are executed, but some of the processes may be performed. For example, when only the ISC opening degree increasing process is performed when the opening is fixed, only the injection cut process is performed, only the AT shift changing process is performed, or two of these processes are performed.

1 is a schematic configuration diagram of an internal combustion engine control device according to a first embodiment of the present invention. 3 is a flowchart of control processing in the internal combustion engine control device of FIG. 1. It is a flowchart of the control processing of the internal combustion engine control apparatus which concerns on 2nd embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine control apparatus, 2 ... Engine, 3 ... Intake path, 4 ... Exhaust path, 5 ... Exhaust gas path, 6 ... ECU (combustion improvement means, swirl flow control means, variable valve control means, intake air quantity increase means ), 23 ... Variable valve mechanism, 51 ... EGR valve (exhaust gas recirculation valve)

Claims (6)

In an internal combustion engine controller for controlling an internal combustion engine having an exhaust gas recirculation function for recirculating exhaust gas from an exhaust path to an intake path through an exhaust gas passage,
Combustion improving means for improving the combustion state of the internal combustion engine,
Improving the combustion state of the internal combustion engine by the combustion improving means when the exhaust gas recirculation valve for opening and closing the exhaust gas passage is fixed open;
An internal combustion engine control device. The combustion improvement means is a swirl flow control means for controlling a swirl flow in a combustion chamber of the internal combustion engine,
When the exhaust gas recirculation valve is stuck open, the swirl flow is increased compared to before the sticking to improve the combustion state;
The internal combustion engine controller according to claim 1. The combustion improving means is a variable valve control means for controlling a valve opening characteristic of the internal combustion engine;
Controlling the valve opening characteristic so that the overlap is reduced when the exhaust gas recirculation valve is stuck open compared to before the sticking open;
The internal combustion engine controller according to claim 1. In an internal combustion engine controller for controlling an internal combustion engine having an exhaust gas recirculation function for recirculating exhaust gas from an exhaust path to an intake path through an exhaust gas passage,
An intake air amount increasing means for increasing the intake air amount per cylinder of the internal combustion engine;
When the exhaust gas recirculation valve for opening and closing the exhaust gas passage is fixed open, the intake air amount taken into the internal combustion engine by the intake air amount increasing means is increased;
An internal combustion engine control device. The intake air amount increasing means causes the internal combustion engine to perform a reduced cylinder operation when the exhaust gas recirculation valve is stuck open;
The internal combustion engine controller according to claim 4. The intake air amount increasing means changes the shift point of the automatic transmission to a high speed side when the exhaust gas recirculation valve is stuck open;
The internal combustion engine controller according to claim 4.

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