JP2009167963A - Abnormality determination device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an abnormality determination device specifying an abnormal section in an internal combustion engine including two superchargers. <P>SOLUTION: The abnormality determination device for the internal combustion engine 1 is provided with a first and a second superchargers 13a, 13b disposed in parallel. The device is provided with a plurality of control valves 17, 19, 21, 31 used for changing over operation modes between a twin turbo mode in which the first and the second superchargers 13a, 13b are used for supercharging, and a single turbo mode in which the second supercharger 13b is not used for supercharging but the first supercharger 13a is used for supercharging. The device is provided with a compressor inlet side air flow meter 15 provided in an upstream of a compressor of the second supercharger 13b and detecting intake air quantity GA2 flowing in the second supercharger 13b. The device is provided with a control part 5 carrying out a failure diagnosis of at least one control valve of the plurality of the control valves, based on intake air quantity GA2 during at least one of operations of open operation or close operation of at least one control valve of the plurality of the control valves. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an abnormality determination apparatus for an internal combustion engine having two superchargers arranged in parallel, and more particularly to an apparatus for determining an abnormality based on the intake air amount of one of the superchargers.

  An internal combustion engine having first and second superchargers arranged in parallel has been proposed. In such an internal combustion engine, a single turbo mode in which the second supercharger is not used for supercharging and the first supercharger is used for supercharging according to the operating state, and the first and second superchargers are supercharged. It is used by switching to the twin turbo mode. In this internal combustion engine, a control valve such as an intake switching valve is provided to switch between the twin turbo mode and the single turbo mode. If these control valves are not properly opened and closed, the target boost pressure cannot be obtained, and the internal combustion engine may be damaged. For this reason, there is a need for an apparatus for determining abnormality of the internal combustion engine, such as failure diagnosis of a control valve.

Patent Document 1 uses a differential pressure sensor in an internal combustion engine having two superchargers to check whether there is a failure in a control valve such as an intake switching valve based on the differential pressure between the upstream and downstream of the intake switching valve. An apparatus for diagnosing is disclosed.
Japanese Patent No. 3157350

  However, in the failure diagnosis using the differential pressure sensor in the apparatus of Patent Document 1, it is not possible to specify which control valve has failed. For this reason, after the failure of the control valve is found, it is necessary to identify which control valve has failed using another means. In addition, surge diagnosis of the two turbochargers cannot be performed.

  Accordingly, an object of the present invention is to provide an abnormality determination device that identifies an abnormal point in an internal combustion engine having two superchargers.

  An abnormality determination apparatus for an internal combustion engine according to the present invention includes first and second superchargers arranged in parallel, a twin turbo mode in which the first and second superchargers are used for supercharging, and a second supercharger. Provided upstream of the compressor of the second supercharger, and a plurality of control valves used to switch between a single turbo mode in which the supercharger is not used for supercharging and the first supercharger is used for supercharging. , Suction when the compressor inlet-side air flow meter for detecting the amount of intake air flowing into the second supercharger and at least one of the plurality of control valves is opened or closed. And a control unit that performs failure diagnosis for one control valve among the plurality of control valves based on the air amount.

  Due to the operation of the control valve for switching between the twin turbo mode and the single turbo mode, the flow of exhaust gas to the turbine of the second turbocharger and the flow of air to the compressor of the second turbocharger fluctuate. Accordingly, the amount of intake air flowing into the second supercharger also varies. For this reason, it becomes possible to identify the failed control valve as the identification of the abnormal part based on the behavior of the intake air amount.

  Preferably, the plurality of control valves include an exhaust switching valve that switches between blocking and opening an exhaust passage connected to the second supercharger, and the control unit instructs to open the valve in the single turbo mode. A failure diagnosis of the exhaust gas switching valve is performed based on at least one of the intake air amount when the exhaust gas switching valve receives and the intake air amount when the exhaust gas switching valve receives an instruction to close the valve.

  If the exhaust gas switching valve is normally opened, the exhaust gas flowing into the turbine of the second supercharger will increase and the amount of intake air flowing into the second supercharger will increase compared to when it is closed. . On the other hand, if the exhaust gas switching valve is normally closed, the exhaust gas flowing into the turbine of the second supercharger is reduced compared to when the valve is open, and the amount of intake air flowing into the second supercharger is reduced. Decrease. For this reason, it is possible to perform failure diagnosis of the exhaust gas switching valve by checking the amount of intake air flowing into the second supercharger in such a state. Further, in the single turbo mode, since the second supercharger is not used for supercharging, the influence of the opening / closing operation of the exhaust gas switching valve on the operating state of the internal combustion engine is small.

  Preferably, the plurality of control valves include an intake air switching valve that switches between blocking and opening an intake passage connected to the second supercharger, and the control unit opens the valve in the single turbo mode. Failure diagnosis of the intake air switching valve is performed based on at least one of the intake air amount when the intake air switching valve receives an instruction and the intake air amount when the intake air switching valve receives an instruction to close the valve.

  If the intake air switching valve is normally opened and closed, the intake air flows into the second supercharger because the air flowing into the compressor of the second supercharger flows into the engine body side by opening the valve. Air volume increases. Further, by closing the valve, the flow of air flowing into the compressor of the second supercharger is blocked from flowing into the engine main body, so the amount of intake air flowing into the second supercharger is reduced. Therefore, it is possible to perform failure diagnosis of the intake air switching valve by confirming the amount of intake air flowing into the second supercharger in such a state. Further, in the single turbo mode, since the second supercharger is not used for supercharging, the influence of the opening / closing operation of the intake air switching valve on the operating state of the internal combustion engine is small.

  Preferably, the plurality of control valves are provided between an intake switching valve that switches between blocking and releasing an intake passage connected to the second supercharger, and between the compressor outlet of the second supercharger and the intake switching valve. And an intake bypass valve that switches between blocking and releasing the intake bypass passage that communicates with the compressor inlet of the first supercharger, and the control unit takes in an instruction to close the valve in the single turbo mode. A failure diagnosis of the intake bypass valve is performed based on at least one of the intake air amount when the bypass valve receives and the intake air amount when the intake bypass valve receives an instruction to open the valve.

  If the intake bypass valve is normally opened and closed, the valve is closed so that the air flowing into the compressor of the second supercharger is blocked from flowing into the intake bypass passage. The amount of intake air flowing into In addition, since the air that has flowed into the compressor of the second supercharger flows into the intake bypass passage by opening the valve, the amount of intake air that flows into the second supercharger increases. Therefore, it is possible to perform a failure diagnosis of the intake bypass valve by confirming the amount of intake air flowing into the second supercharger in such a state. Further, in the single turbo mode, since the second supercharger is not used for supercharging, the influence of the opening / closing operation of the intake bypass valve on the operating state of the internal combustion engine is small.

  More preferably, failure diagnosis for one control valve among the plurality of control valves is performed when the internal combustion engine is operated in an idle state immediately after starting.

  By performing failure diagnosis immediately after startup, it is possible to perform failure diagnosis at the earliest possible point and enter the fail-safe mode. In addition, by performing failure diagnosis in the idle state, it is possible to suppress the exhaust gas exhausted at the time of failure diagnosis as much as possible, and to reduce the influence on the internal combustion engine due to the opening and closing operation of the control valve different from the normal operation Become.

  Preferably, the plurality of control valves are provided in an intake switching valve that switches between blocking and releasing an intake passage connected to the second supercharger, and an intake lead passage that communicates upstream and downstream of the intake switching valve. The intake reed valve opens and closes according to the pressure difference, and the controller diagnoses the intake reed valve failure based on the behavior of the intake air amount when the intake switching valve is closed in the single turbo mode. I do.

  When the intake air switching valve is closed, the air flowing into the compressor of the second supercharger is blocked by the intake air switching valve, so the amount of intake air flowing into the second supercharger decreases. At this time, the air flowing into the second supercharger is pushed between the compressor of the second supercharger and the intake air switching valve, and the compressor outlet pressure of the second supercharger increases. When the outlet pressure of the second supercharger becomes larger than the pressure downstream of the intake air switching valve by a predetermined amount, the intake reed valve opens and the amount of intake air flowing into the second supercharger increases. Therefore, it is possible to perform a failure diagnosis of the intake reed valve by confirming the behavior of the intake air amount flowing into the second supercharger in such a state. Further, in the single turbo mode, since the second supercharger is not used for supercharging, the opening / closing operation of the intake air switching valve or the intake reed valve has little influence on the operating state of the internal combustion engine.

  More preferably, the malfunction diagnosis of the intake reed valve is performed when the engine is operated in a partial load state.

  Thereby, it becomes easy to confirm the behavior that the intake reed valve is switched from the closed state to the open state when the exhaust gas appropriately flows into the second supercharger.

  An abnormality determination device for an internal combustion engine according to the present invention includes first and second superchargers arranged in parallel, a compressor inlet side air flow meter for detecting an intake air amount flowing into the second supercharger, and a first The air flow meter for detecting the total intake air amount of the internal combustion engine including the second supercharger, the pressure sensor for detecting the supercharging pressure of the internal combustion engine, and the first and second superchargers are used for supercharging. In the twin turbo mode, the surge diagnosis of the second supercharger is performed based on the intake air amount and the supercharging pressure, and the first supercharger is performed based on the intake air amount, the total intake air amount, and the supercharging pressure. And a control unit for performing surge diagnosis.

  A second operating point on the compressor performance map of the second supercharger is identified from the amount of intake air flowing into the second supercharger and the supercharging pressure, and whether or not the second operating point is within the surging region. By determining whether or not, the surge diagnosis of the second supercharger can be performed as the specification of the abnormal part. Furthermore, the intake air amount flowing into the first supercharger can be calculated from the difference between the total intake air amount to the internal combustion engine and the intake air amount flowing into the second supercharger. Therefore, the first operating point on the compressor performance map of the first supercharger is specified from the supercharging pressure and the intake air amount flowing into the first supercharger, and the first operating point is in the surging region. By determining whether or not, the surge diagnosis of the first supercharger can be performed as specifying the abnormal part.

  As described above, according to the present invention, it is possible to provide an abnormality determination device that identifies an abnormal point in an internal combustion engine having two superchargers.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The internal combustion engine 1 includes a control unit 5, first and second superchargers 13a and 13b, an engine body 30, a compressor inlet side intake passage 51, a compressor outlet side intake passage 52, an intake manifold 55, a turbine inlet side exhaust passage 72, And a turbine outlet side exhaust passage 73.

  The control unit 5 includes a CPU, a ROM storing a control program, a RAM storing various data, and the like. Signals from various sensors such as a compressor inlet side air flow meter 15 are input, and an intake air switching valve 19 and the like are input. A control signal is output to control each part of the vehicle including the internal combustion engine 1. The controller 5 determines whether the internal combustion engine 1 is abnormal, that is, the twin turbo mode, based on the second intake air amount GA2 flowing into the second supercharger 13b detected by the compressor inlet airflow meter 15 in particular. Fault diagnosis of control valves (intake bypass valve 17, intake switching valve 19, intake reed valve 21, and exhaust switching valve 31) used for switching to single turbo mode, and first and second superchargers 13a, The surge diagnosis of 13b is performed.

  During the operation of the internal combustion engine 1, air is sucked into the combustion chamber of each cylinder of the engine body 30 via the compressor inlet side intake passage 51, the compressor outlet side intake passage 52, and the intake manifold 55 (see FIG. 1). (See solid arrow). The fuel injected from the injector mixes with the sucked air to form an air-fuel mixture. The air-fuel mixture is combusted by ignition of the spark plug based on the ignition signal from the control unit 5. A crankshaft (not shown) rotates by the reciprocating motion of the piston according to the explosive force caused by the combustion of the air-fuel mixture. The exhaust gas generated by the combustion is exhausted through the exhaust manifold 71, the turbine inlet side exhaust passage 72, and the turbine outlet side exhaust passage 73 (see the broken line arrow in FIG. 1).

  Next, the configuration of each part of the internal combustion engine 1 will be described focusing on the first and second superchargers 13a and 13b. The first and second superchargers 13a and 13b are arranged in parallel. The first supercharger 13a serves as a main turbocharger, and the second supercharger 13b serves as a sub turbocharger. The first supercharger 13a operates from the low intake air amount region to the high intake air amount region, and the second supercharger 13b stops in the low intake air amount region. Therefore, in the low intake air amount region, the operation is performed in the single turbo mode in which the second supercharger 13b is not used for supercharging and the first supercharger 13a is used for supercharging, and in the high intake air amount region. The first and second superchargers 13a and 13b are operated in a twin turbo mode in which supercharging is used.

  The first supercharger 13a has a first turbine 13a1 and a first compressor 13a2, and the second supercharger 13b has a second turbine 13b1 and a second compressor 13b2. The inlet sides of the first and second turbines 13 a 1 and 13 b 1 are connected to a turbine inlet side exhaust passage 72 communicated with the exhaust manifold 71. The outlet sides of the first and second turbines 13a1 and 13b1 are connected to a turbine outlet side exhaust passage 73 communicated with an exhaust gas purification catalyst (not shown).

  The inlet sides of the first and second compressors 13 a 2 and 13 b 2 are connected to the compressor inlet side intake passage 51. The compressor inlet side intake passage 51 is provided with an air cleaner 11 and an air flow meter 12 for detecting the amount of air that has flowed through the air cleaner, that is, the total intake air amount GA. In the present embodiment, the total intake air amount GA is used for surge diagnosis of the first supercharger 13a. The outlet sides of the first and second compressors 13 a 2 and 13 b 2 are connected to a compressor outlet side intake passage 52 communicated with the intake manifold 55. An intercooler 23 and a throttle valve 25 are provided in the compressor outlet side intake passage 52.

  In order to switch between the twin turbo mode and the single turbo mode, that is, to switch between the operation and stop of the second supercharger 13b, the turbine inlet side exhaust passage 72 is connected to the second turbine 13b1 on the inlet side to the second turbine 13b1. An exhaust gas switching valve 31 is provided for switching between blocking and opening the flow of exhaust gas, and the air flow from the second compressor 13b2 to the intake manifold 55 is provided on the outlet side of the second compressor 13b2 in the compressor outlet side intake passage 52. An intake air switching valve 19 that switches between flow blocking and opening is provided.

  In order to smoothly switch from the single turbo mode to the twin turbo mode, on the compressor outlet side intake passage 52, between the outlet of the second compressor 13b2 and the intake air switching valve 19, and in the compressor inlet side intake passage 51. An intake bypass passage 53 that communicates with the inlet side of one compressor 13a2 is provided. The intake bypass passage 53 is provided with an intake bypass valve 17 that switches between blocking and opening the air flow.

  In the single turbo mode, both the intake air switching valve 19 and the exhaust gas switching valve 31 are closed, but the intake bypass valve 17 is opened, whereby the first supercharger 13a is operated, and the second The supercharger 13b stops. In the twin turbo mode, both the intake switching valve 19 and the exhaust switching valve 31 are opened, but the intake bypass valve 17 is closed, thereby operating the first and second superchargers 13a and 13b. To do.

  An intake reed valve 21 that opens and closes according to the pressure difference is provided in an intake reed passage (bypass passage of the intake air switching valve 19) 54 that communicates the upstream and downstream of the intake switching valve 19. That is, when the intake air switching valve 19 is closed, when the outlet pressure of the second compressor 13b2 becomes larger than the outlet pressure of the first compressor 13a2, the valve is opened, and the air opens the intake reed valve 21. Flows from the upstream side to the downstream side.

  The intake bypass passage 53 and the intake lead passage 54 are set narrower than the compressor inlet side intake passage 51 and the compressor outlet side intake passage 52.

  When the operation state is switched from the single turbo mode to the twin turbo mode, the exhaust gas switching valve 31 is first changed from the closed state to the open state, and then the intake bypass valve 17 is changed from the open state to the closed state. As a result, the outlet pressure of the second compressor 13b2 gradually increases while avoiding the surge of the second compressor 13b2 while the intake bypass valve 17 is kept open and the intake switching valve 19 is kept closed. The bypass valve 17 is closed and the intake reed valve 21 is opened. Thereafter, the intake air switching valve 19 is changed from the closed state to the opened state. When the intake switching valve 19 is opened, the intake reed valve 21 is closed.

  A compressor inlet-side air flow meter 15 that detects the second intake air amount GA2 flowing into the second supercharger 13b is provided upstream of the second compressor 13b2 of the second supercharger 13b, that is, on the inlet side. In the present embodiment, the second intake air amount GA2 is a control valve used for switching between the twin turbo mode and the single turbo mode, that is, the intake bypass valve 17, the intake air switching valve 19, the intake reed valve 21, and the exhaust gas. It is used for failure diagnosis of the switching valve 31 and is used for surge diagnosis of the first and second superchargers 13a and 13b.

  In addition, a pressure sensor 27 that detects the supercharging pressure P is provided in the intake manifold 55. In the present embodiment, the supercharging pressure P is used for surge diagnosis of the first and second superchargers 13a and 13b.

  In the present embodiment, a pressure sensor 27 (intake manifold pressure sensor) that is normally provided in the intake manifold 55 of the internal combustion engine 1 is used as a sensor that detects the supercharging pressure P used for surge diagnosis. However, another pressure sensor arranged on the compressor outlet side intake passage 52 may detect the supercharging pressure P for surge diagnosis.

  Next, details of the failure diagnosis of the exhaust gas switching valve 31 will be described using the flowchart of FIG. The failure diagnosis of the exhaust gas switching valve 31 is performed immediately after the internal combustion engine 1 is started and in an idle state. The reason why the engine is immediately after the start is that if there is an abnormality in the exhaust gas switching valve 31, the internal combustion engine 1 may be damaged, so that a failure diagnosis is performed at the earliest possible time and the fail-safe mode is set. The condition of the idle state is to suppress the exhaust gas discharged at the time of failure diagnosis as much as possible, and to reduce the influence on the internal combustion engine 1 due to the opening / closing operation of the exhaust gas switching valve 31 etc. different from the normal operation. . Therefore, the failure diagnosis is a problem in the operation of the internal combustion engine 1 even when the exhaust gas switching valve 31 or the like is set in an open / close state different from the open / close state in the normal single turbo mode. As long as the engine is in a low load state and a low engine speed so as not to occur, it may be performed at other times, and the number of times is not limited to one.

The first to ninth air amount threshold values G _{1 to} G ₉ used for failure diagnosis of the exhaust gas switching valve 31 are normally opened or closed according to the control signal from the control unit 5. The second intake air amount GA2 assumed when the operation is performed is shown.

  Before the failure diagnosis of the exhaust gas switching valve 31 is started, the exhaust gas switching valve 31 is closed and the intake air switching valve 19 is closed because the engine is operating in an idle state, that is, a low-load single turbo mode. The intake bypass valve 17 is open. The variable nozzle of the first turbine 13a1 is set to an opening degree corresponding to the operating state.

When failure diagnosis of the exhaust gas switching valve 31 is started, in step S31, the exhaust gas switching valve 31 is opened, the variable nozzle of the first turbine 13a1 is fully closed, and the intake air switching valve 19 is opened. A control signal relating to each instruction for closing the intake bypass valve 17 is output from the control unit 5 to the exhaust gas switching valve 31 or the like. When the exhaust gas switching valve 31 and the like operate normally based on the control signal, most of the exhaust gas discharged from the engine body 30 is supplied to the second turbine 13b1 and the rotation speed of the second supercharger 13b. N rises. Thus, the amount of air flowing from the second compressor 13b2 to the intake switching valve 19, that is, the second intake air amount GA2 increases to a first air amount threshold G ₁ or more.

  In addition, the variable nozzle of the first turbine 13a1 is fully closed to suppress the inflow of exhaust gas to the first turbine 13a1 as much as possible, to secure the exhaust energy to the second turbine 13b1, This is to increase the detection sensitivity of the second intake air amount GA2 in step S35. Therefore, the fully closed state of the variable nozzle of the first turbine 13a1 may not be a state in which the nozzle is completely closed.

In step S32, the control unit 5, the second intake air amount GA2 it is determined whether an increase in the first air amount threshold G ₁ or more. If not increased, the exhaust gas switching valve 31 is not in the open / closed state according to the control signal output in step S31, and the exhaust gas is not properly supplied to the second turbine 13b1, so that the process proceeds to step S33. It is advanced. If it has increased, the process proceeds to step S34.

  In step S33, the control unit 5 determines that there is an abnormality in the opening operation of the exhaust gas switching valve 31, and after setting the fail-safe mode, ends the failure diagnosis of the exhaust gas switching valve 19.

In step S <b> 34, a control signal related to an instruction to close the exhaust gas switching valve 31 is output from the control unit 5 to the exhaust gas switching valve 31. When the exhaust gas switching valve 31 operates normally based on the control signal, the exhaust gas that is discharged from the engine main body 30 is cut off from being supplied to the second turbine 13b1 by the exhaust gas switching valve 31. The rotational speed N of 13b1 decreases. Thus, the amount of air flowing through the second compressor 13b2, that is, the second intake air amount GA2 decreases to a second or less air amount threshold _{G 2.}

In step S35, the control unit 5, the second intake air amount GA2 it is determined whether a decrease in the second less air amount threshold _{G 2 (G 1> G 2} ). If not, it is determined that the exhaust gas switching valve 31 is not closed according to the control signal output in step S34, and the supply of exhaust gas to the second turbine 13b1 is not properly shut off. It is advanced. If so, the process proceeds to step S36.

  In step S34, when the exhaust gas switching valve 31 is closed, the opening of the variable nozzle of the first turbine 13a1 may be returned from the fully closed state to the normal opening. Although it is easier to confirm the decrease in the second intake air amount GA2 when the fully closed state is maintained, it is desirable to set the normal opening from the fully closed state in order to discharge exhaust gas.

  In step S36, the control unit 5 determines that the opening / closing operation of the exhaust gas switching valve 31 is normal, returns each control valve to the open / closed state before the failure diagnosis, and then ends the failure diagnosis of the exhaust gas switching valve 31. In step S <b> 37, the control unit 5 determines that there is an abnormality in the valve closing operation of the exhaust gas switching valve 31, sets the fail safe mode, and then ends the failure diagnosis of the exhaust gas switching valve 31.

  This makes it possible to perform a failure diagnosis of the exhaust gas switching valve 31 without providing the exhaust gas switching valve 31 with an opening degree sensor or the like that monitors the valve opening state and the valve closing state. Since the control from step S31 to S37 can be completed in about several seconds, the opening / closing operation of the exhaust gas switching valve 31 or the like has little influence on the operating state of the internal combustion engine 1.

  Further, in the failure diagnosis of the exhaust gas switching valve 31, the open / close instruction procedure of the exhaust gas switching valve 31 and the open / closed state of other valves are preferably in the above-described form from the viewpoint of detection sensitivity, but are not limited thereto. Even in other procedures, the behavior of the second intake air amount GA2 when an instruction to open the exhaust gas switching valve 31 and the instruction to set the exhaust gas switching valve 31 to a closed state are received. The failure diagnosis of the exhaust gas switching valve 31 can be performed based on at least one of the behaviors of the second intake air amount GA2.

  Next, details of the failure diagnosis of the intake air switching valve 19 will be described using the flowchart of FIG. The failure diagnosis of the intake air switching valve 19 is performed immediately after the internal combustion engine 1 is started and in an idle state. The reason immediately after the start and the reason for the idling condition are the same as in the case of the failure diagnosis of the exhaust gas switching valve 31.

  Before the failure diagnosis of the intake switching valve 19 is started, the exhaust switching valve 31 is closed and the intake switching valve 19 is closed because the engine is operating in the idle state, that is, the low-load single turbo mode. The intake bypass valve 17 is open. The variable nozzle of the first turbine 13a1 is set to an opening degree corresponding to the operating state.

  When failure diagnosis of the intake switching valve 19 is started, in step S51, control signals relating to respective instructions for opening the exhaust switching valve 31 and fully closing the variable nozzle of the first turbine 13a1 are sent to the control unit. 5 to the exhaust gas switching valve 31 or the like. When the exhaust gas switching valve 31 and the like operate normally based on the control signal, most of the exhaust gas discharged from the engine body 30 is supplied to the second turbine 13b1 and the rotation speed of the second supercharger 13b. N rises.

As the second turbine 13b1 rotates, the second compressor 13b2 rotates and air is sucked into the second compressor 13b2. Since the intake bypass passage 53 is narrower than the compressor outlet side intake passage 52, a part of the air sucked into the second compressor 13b2 reaches the compressor inlet side intake passage 51 via the intake bypass passage 53. The rest is on the compressor outlet side intake passage 52 and is pushed between the outlet of the second compressor 13 b 2 and the intake air switching valve 19. For this reason, the outlet pressure of the second compressor 13b2 increases. This also, the amount of air flowing into the intake bypass valve 17 from the second compressor 13b2, that is, the second intake air amount GA2 increases to a third air amount threshold G ₃ or more.

  The reason why the variable nozzle of the first turbine 13a1 is fully closed is the same as in the case of the failure diagnosis of the exhaust gas switching valve 31.

In step S52, the control unit 5, after the second intake air amount GA2 it was confirmed that an increase in the third air amount threshold G ₃ or more, proceeds to step S53.

  In step S <b> 53, after the intake switching valve 19 is switched to the open state, a control signal related to an instruction to immediately close the intake valve is output from the control unit 5 to the intake switching valve 19.

When the intake air switching valve 19 operates normally based on the control signal, the air that has flowed into the second compressor 13 b 2 flows into the intake air bypass passage 53 by opening the intake air switching valve 19. well, to flow into the intake manifold 55 via the compressor outlet side intake passage 52, the second intake air amount GA2 is increased in the fourth air amount threshold G ₄ or more. Further, thereafter by the intake switching valve 19 is in the closed state, the flow of air to the intake manifold 55 from the second compressor 13b2 is blocked, it increased the second intake air amount GA2 fifth air amount threshold G ₅ Decreases to:

In step S54, the control unit 5, the second intake air amount GA2 is increased in the fourth air amount threshold G ₄ or more, and then decides whether the decreased below the fifth air amount threshold G ₅ ( _{G 4>} G 5).

When the second intake air amount GA2 does not increase to the fourth air amount threshold G ₄ or is not opened in accordance with the control signal which the intake switching valve 19 is output in step S53, the compressed air from the second compressor 13b2 Is not properly flowing into the intake manifold 55 via the compressor outlet side intake passage 52. The second intake air amount GA2 is even increased to fourth air amount threshold G ₄ or more, then, if not reduced below the fifth air amount threshold G ₅ is an intake switching valve 19 is output in step S53 The valve is not closed according to the control signal, and it is determined that the inflow of the compressed air from the second compressor 13b2 into the intake manifold 55 cannot be properly blocked. For this reason, when at least one of the conditions of step S54 is not satisfied, the process proceeds to step S56. When all the conditions of step S54 are satisfied, the process proceeds to step S55.

  In step S55, the control unit 5 determines that the opening / closing operation of the intake air switching valve 19 is normal, returns each control valve to the open / closed state before failure diagnosis, and ends the failure diagnosis of the intake air switching valve 19. In step S56, the control unit 5 determines that there is an abnormality in the opening / closing operation of the intake air switching valve 19, and after setting the fail safe mode, ends the failure diagnosis of the intake air switching valve 19.

  This makes it possible to perform failure diagnosis of the intake air switching valve 19 without providing the intake air switching valve 19 with an opening degree sensor for monitoring the open state and the closed state. Since the control from step S51 to S56 can be completed in about several seconds, the opening / closing operation of the intake air switching valve 19 or the like has little influence on the operating state of the internal combustion engine 1.

  In addition, in the failure diagnosis of the intake air switching valve 19, the opening / closing instruction procedure of the intake air switching valve 19 and the open / closed state of other valves are preferably in the above-described form from the viewpoint of detection sensitivity, but are not limited thereto. Even in other procedures, the behavior of the second intake air amount GA2 when receiving an instruction to open the intake switching valve 19 and the instruction to set the intake switching valve 19 to a closed state are received. The failure diagnosis of the intake air switching valve 19 can be performed based on at least one of the behaviors of the second intake air amount GA2.

  Next, details of the failure diagnosis of the intake bypass valve 17 will be described with reference to the flowchart of FIG. The failure diagnosis of the intake bypass valve 17 is performed immediately after the internal combustion engine 1 is started and in an idle state. The reason immediately after the start and the reason for the idling condition are the same as in the case of the failure diagnosis of the exhaust gas switching valve 31.

  Before the failure diagnosis of the intake bypass valve 17 is started, the exhaust switching valve 31 is closed and the intake switching valve 19 is closed because the engine is operating in an idle state, that is, a low-load single turbo mode. The intake bypass valve 17 is open. The variable nozzle of the first turbine 13a1 is set to an opening degree corresponding to the operating state.

When failure diagnosis of the intake bypass valve 17 is started, in step S71, the exhaust switching valve 31 is opened, the variable nozzle of the first turbine 13a1 is fully closed, and the intake switching valve 19 is opened. A control signal relating to each instruction for closing the intake bypass valve 17 is output from the control unit 5 to the exhaust gas switching valve 31 or the like. When the exhaust gas switching valve 31 and the like operate normally based on the control signal, most of the exhaust gas discharged from the engine body 30 is supplied to the second turbine 13b1 and the rotation speed of the second supercharger 13b. N rises. Thus, the amount of air flowing from the second compressor 13b2 to the intake switching valve 19, that is, the second intake air amount GA2 increases to a first air amount threshold G ₁ or more.

In step S <b> 72, a control signal related to an instruction to close the intake air switching valve 19 is output from the control unit 5 to the intake air switching valve 19. When the intake air switching valve 19 operates normally based on the control signal, the air flow in the compressor outlet side intake passage 52 and the intake bypass passage 53 is blocked, and the air flowing into the second compressor 13b2 2 It is pushed into the passage between the compressor 13b2, the intake bypass valve 17 and the intake air switching valve 19 and becomes difficult to flow. Therefore, the second intake air amount GA2 is reduced below the sixth air amount threshold G _6.

  The reason why the variable nozzle of the first turbine 13a1 is fully closed is the same as in the case of the failure diagnosis of the exhaust gas switching valve 31.

In step S73, the control unit 5, the second intake air amount GA2 is increased to a first air amount threshold G ₄ or more, and then decides whether the decreased below sixth air amount threshold G ₆ ( _{G 1>} G 6).

When the second intake air amount GA2 does not increase to a first air amount threshold G ₁ or more, or if not then decreased below the sixth air amount threshold G ₆ is closed in accordance with the control signal which the intake bypass valve 17 is output in step S71 Since it is not valved and the inflow of the air that has flowed into the second compressor 13b2 into the compressor inlet side intake passage 51 through the intake bypass passage 53 has not been properly blocked by the intake bypass valve 17, the process proceeds to step S74. It is done. If the second intake air amount GA2 is increased to a first air amount threshold G ₁ or more, and then decreased to below the sixth air amount threshold G _6, it advances to step S75.

  In step S74, the control unit 5 determines that there is an abnormality in the closing operation of the intake bypass valve 17, sets the fail-safe mode, and ends the failure diagnosis of the intake bypass valve 17.

In step S75, a control signal related to an instruction to open the intake bypass valve 17 is output from the control unit 5 to the intake bypass valve 17. When the intake bypass valve 17 operates normally based on the control signal, the air that has flowed into the second compressor 13b2 flows into the intake bypass passage 53 when the intake bypass valve 17 is opened. . Therefore, the second intake air amount GA2 is increased to more than 7 air amount threshold G _7.

In step S76, the control unit 5, the second intake air amount GA2 is, determines whether the increased over the seventh air amount threshold _{G 7 (G 6 <G 7} ). When the second intake air amount GA2 does not increase above 7 air amount threshold G ₇ is not opening operation in accordance with the control signal which the intake bypass valve 17 is output in step S75, the air that has flowed into the second compressor 13b2 Assuming that the air does not properly flow into the intake bypass passage 53, the process proceeds to step S78. If the second intake air amount GA2 is increased to above 7 air amount threshold G _7, it advances to step S77.

  In step S77, the control unit 5 determines that the opening / closing operation of the intake bypass valve 17 is normal, returns each control valve to the opened / closed state before failure diagnosis, and then ends the failure diagnosis of the intake bypass valve 17. In step S78, the control unit 5 determines that there is an abnormality in the opening operation of the intake bypass valve 17, sets the fail-safe mode, and ends the failure diagnosis of the intake bypass valve 17.

  As a result, it is possible to perform failure diagnosis of the intake bypass valve 17 without providing the intake bypass valve 17 with an opening degree sensor for monitoring the open state and the closed state. Since the control from step S71 to S78 can be completed in about several seconds, the opening / closing operation of the intake bypass valve 17 or the like has little influence on the operating state of the internal combustion engine 1.

  Note that the intake bypass valve 17 opening / closing instruction procedure and other valve opening / closing states in the failure diagnosis of the intake bypass valve 17 are preferably in the above-described form from the viewpoint of detection sensitivity, but are not limited thereto. Even in other procedures, the behavior of the second intake air amount GA2 when receiving an instruction to close the intake bypass valve 17 and the instruction to set the intake bypass valve 17 to a closed state The failure diagnosis of the intake bypass valve 17 can be performed based on at least one of the behaviors of the second intake air amount GA2.

  Next, details of the failure diagnosis of the intake reed valve 21 will be described using the flowchart of FIG. The failure diagnosis of the intake reed valve 21 is performed while the internal combustion engine 1 is being operated in the single turbo mode and in the partial load state. Although the intake reed valve 21 is less likely to directly damage the internal combustion engine 1 even if it fails, it is preferable to perform the intake reed valve 21 as soon as possible after starting because it leads to deterioration of drivability. The number of times of failure diagnosis of the intake reed valve 21 is not limited to one.

  The condition of the single turbo mode and the partial load state is that the first supercharger 13a is appropriately supercharged, the downstream pressure of the intake reed valve 21 is increased, and the second supercharger This is to make it easier to confirm the behavior of the intake reed valve 21 switching from the closed state to the open state when the exhaust gas appropriately flows into the machine 13b. In addition, since the failure diagnosis of the intake reed valve 21 is performed in a state where the second supercharger 13b is not used for supercharging, that is, during operation in the single turbo mode, the internal combustion engine 1 is opened and closed by the intake switching valve 19 and the like. It becomes possible to reduce the influence of.

  Before the failure diagnosis of the intake reed valve 21 is started, since it is operated in the single turbo mode, the exhaust switching valve 31 is closed, the intake switching valve 19 is closed, and the intake bypass valve 17 is The valve is open. Further, the variable nozzle of the first turbine 13a1 is set to an opening degree corresponding to the operation state of the partial load.

  When failure diagnosis of the intake reed valve 21 is started, in step S81, instructions for opening the exhaust switching valve 31, opening the intake switching valve 19, and closing the intake bypass valve 17 are performed. Is output from the control unit 5 to the exhaust gas switching valve 31 or the like. When the exhaust gas switching valve 31 and the like operate normally based on the control signal, the exhaust gas discharged from the engine body 30 is supplied not only to the first turbine 13a1 but also to the second turbine 13b1, and the second The rotational speed N of the supercharger 13b increases. As a result, the amount of air flowing into the intake air switching valve 19 from the second compressor 13b2, that is, the second intake air amount GA2, increases.

In step S <b> 82, a control signal related to an instruction to close the intake air switching valve 19 is output from the control unit 5 to the intake air switching valve 19. When the intake air switching valve 19 operates normally based on the control signal, the air flow in the compressor outlet side intake passage 52 and the intake bypass passage 53 is blocked, and the air flowing into the second compressor 13b2 2 It is pushed into the passage between the compressor 13b2, the intake bypass valve 17 and the intake air switching valve 19, and it becomes difficult to flow. Therefore, the second intake air amount GA2 decreases temporarily below the eighth air amount threshold G _8.

Thereafter, as the amount of air pushed into the passage between the second compressor 13b2, the intake bypass valve 17 and the intake air switching valve 19 increases, the pressure in the passage, that is, the outlet pressure of the second compressor 13b increases. When the outlet pressure of the second compressor 13b2, that is, the pressure upstream of the intake reed valve 21, becomes larger by a predetermined amount than the outlet pressure of the first compressor 13a2, that is, the pressure downstream of the intake reed valve 21, the intake reed valve 21 is opened. Then, air flows from the upstream side, that is, the second compressor 13b2 via the intake reed valve 21 to the downstream side, that is, the intake manifold 55 side. Thus, hardly air flowing into the second compressor 13b2 flows state to some extent resolved, the second intake air amount GA2 is increased to more than 9 air amount threshold G _9.

In step S83, the control unit 5, the second intake air amount GA2 is eighth temporarily decreased below the air amount threshold G _8, and then determines whether the increased to a 9 or more air amount threshold G ₉ ( _{G 8} <G 9). If at least one of the conditions is not satisfied, the intake reed valve 21 is not properly opened and closed, and the process proceeds to step S84. If all of these conditions are satisfied, the process proceeds to step S85.

  In step S84, the control unit 5 determines that there is an abnormality in the opening / closing operation of the intake reed valve 21, sets the fail safe mode, and ends the failure diagnosis of the intake reed valve 21. In step S85, the control unit 5 determines that the opening / closing operation of the intake reed valve 21 is normal, returns each control valve to the opened / closed state in the single turbo mode, and then ends the failure diagnosis of the intake reed valve 21.

  As a result, it is possible to perform failure diagnosis of the intake bypass valve 17 without providing the intake reed valve 21 with an opening degree sensor for monitoring the open state and the closed state. Since the control from step S81 to S85 can be completed in about several seconds, the opening / closing operation of the intake air switching valve 19 or the like has little influence on the operating state of the internal combustion engine 1.

  It should be noted that in the failure diagnosis of the intake reed valve 21, the above-described form is desirable for the other valve open / close instruction procedure for opening / closing the intake reed valve 21 and the open / closed state of the other valve from the viewpoint of detection sensitivity. However, the present invention is not limited to this, and even in other procedures, the failure diagnosis of the intake reed valve 21 is performed based on the behavior of the second intake air amount GA2 when the intake switching valve 19 is closed. Is possible.

  In this embodiment, the exhaust gas switching valve 31 is diagnosed, the intake gas switching valve 19 is diagnosed, the intake bypass valve 17 is diagnosed, and the intake reed valve 21 is diagnosed in order. 31, when one of the intake air switching valve 19, the intake bypass valve 17, and the intake reed valve 21 fails, such a failure can be found before the other control valve fails.

  Next, details of surge diagnosis of the first and second superchargers 13a and 13b will be described with reference to the flowchart of FIG. The surge diagnosis of the first and second superchargers 13a and 13b is performed in the twin turbo mode, that is, the internal combustion engine with both the intake switching valve 19 and the exhaust switching valve 31 opened and the intake bypass valve 17 closed. This is always done while 1 is in operation.

  When the surge diagnosis of the first and second superchargers 13a and 13b is started, the pressure at the inlet and the outlet of the second compressor 13b2 calculated from the second intake air amount GA2 and the supercharging pressure P in step S91. Based on the ratio π, the second operating point on the compressor performance map of the second supercharger 13b is calculated.

The compressor performance map is such that the vertical axis represents the pressure ratio π between the inlet and outlet of the compressor, and the horizontal axis represents the amount of air flowing into the compressor, that is, the intake air amount, and the compressor rotation speed N, the pressure ratio π, and the intake air amount Represents relationships and surge limits. FIG. 7 shows an example of a compressor performance map of the second compressor 13b2. Solid lines N _{11 to} N ₁₄ on the compressor performance map are equal rotation speed curves of the turbocharger including the compressor, and the rotation speed increases toward the upper right (N ₁₁ <N ₁₂ <N ₁₃ <N ₁₄ ). A broken line SL on the compressor performance map is a surging line (surge limit), and a region on the left side of the surging line SL is a surging region. Such a compressor performance map is unique to the compressor to be used, and its performance characteristics are obtained in advance by experiments and recorded in the ROM of the control unit 5 or the like. A similar compressor performance map is prepared for the first compressor 13a2.

  In step S92, it is determined whether or not the second operating point is within the surging area. If it is within the surging area, it is determined that surging may occur for the second supercharger 13b, and the process proceeds to step S93. If not in the surging area, the process proceeds to step S94.

  In step S93, feedback for avoiding surging of the second supercharger 13b is performed for the nozzle position control of the variable nozzle of the second supercharger 13b, and the process proceeds to step S94.

  In step S94, the first intake air amount GA1 flowing into the first compressor 13b1 is calculated from the difference between the total intake air amount GA and the second intake air amount GA2.

  In step S95, the first operating point on the compressor performance map of the first supercharger 13a is calculated based on the pressure ratio π calculated from the supercharging pressure P and the first intake air amount GA1. In step S96, it is determined whether or not the first operating point is within the surging area. If it is within the surging area, it is determined that surging may occur for the first supercharger 13a, and the process proceeds to step S97. If it is not within the surging area, the process returns to step S91 and the surge diagnosis is repeated.

  In step S97, feedback for avoiding surging of the first supercharger 13a is performed with respect to the nozzle position control of the variable nozzle of the first supercharger 13a. Thereafter, the process returns to step S91, and the surge diagnosis is repeatedly performed. Is called.

  As a result, surge diagnosis of the first and second superchargers 13a and 13b can be performed. In addition, since the procedure of steps S94 to S96 is performed in a time of about several tens of ms, the feedback of the nozzle position control of the second supercharger 13b in step S93 and the nozzle position of the first supercharger 13a in step S97. Control feedback occurs almost simultaneously.

  In the present embodiment, based on the total intake air amount GA obtained by the air flow meter 12, the second intake air amount GA2 obtained by the compressor inlet side air flow meter 15, and the intake pressure P obtained by the pressure sensor 27, An abnormality determination of the internal combustion engine 1, that is, failure diagnosis of the intake bypass valve 17, the intake switching valve 19, the intake reed valve 21, and the exhaust switching valve 31 used for switching between the twin turbo mode and the single turbo mode may be performed. In addition, surge diagnosis of the first and second superchargers 13a and 13b can be performed.

  In addition, by checking the behavior of the second intake air amount GA2 under different conditions for each control valve, it becomes possible to identify the failed valve, so that it is possible to easily repair the failure. Have.

  The air flow meter 12 and the pressure sensor 27 are normally provided in an internal combustion engine equipped with a supercharger even when such abnormality determination is not performed. For this reason, in the present embodiment, it is possible to determine the abnormality of the internal combustion engine 1 only by newly adding the compressor inlet-side air flow meter 15, so that the apparatus is not complicated for the abnormality determination. Absent. In particular, there is an advantage that a wire harness and a circuit can be simplified as compared with a mode in which an opening degree sensor is provided for each valve for performing failure diagnosis and failure diagnosis is performed.

It is a block diagram of the internal combustion engine in this embodiment. It is a flowchart which shows the procedure of failure diagnosis of an exhaust gas switching valve. It is a flowchart which shows the procedure of a failure diagnosis of an intake switching valve. It is a flowchart which shows the procedure of a failure diagnosis of an intake bypass valve. It is a flowchart which shows the procedure of a failure diagnosis of an intake reed valve. It is a flowchart which shows the procedure of the surge diagnosis of a 1st, 2nd supercharger. It is a figure which shows the compressor performance map of a 2nd compressor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 5 Control part 11 Air cleaner 12 Air flow meter 13a, 13b 1st, 2nd supercharger 13a1, 13b1 1st, 2nd turbine 13a2, 13b2 1st, 2nd compressor 15 Compressor inlet side air flow meter 17 Intake bypass valve DESCRIPTION OF SYMBOLS 19 Intake switching valve 21 Intake reed valve 23 Intercooler 25 Throttle valve 27 Pressure sensor 30 Engine body 31 Exhaust switching valve 51 Compressor inlet side intake passage 52 Compressor outlet side intake passage 53 Intake bypass passage 54 Intake lead passage 55 Intake manifold 71 Exhaust manifold 72 Turbine inlet side exhaust passage 73 Turbine outlet side exhaust passage

Claims (8)

First and second superchargers arranged in parallel;
Twin turbo mode in which the first and second superchargers are used for supercharging, and a single in which the second supercharger is not used for supercharging and the first supercharger is used for supercharging A plurality of control valves used to switch between turbo mode;
A compressor inlet-side air flow meter that is provided upstream of the compressor of the second supercharger and detects an intake air amount flowing into the second supercharger;
Failure of one control valve of the plurality of control valves based on the intake air amount when at least one of the opening operation and the closing operation is performed for at least one control valve of the plurality of control valves An abnormality determination device for an internal combustion engine, comprising: a control unit that performs diagnosis. The plurality of control valves have an exhaust gas switching valve that switches between blocking and opening an exhaust passage connected to the second supercharger,
In the single turbo mode, the control unit includes the intake air amount when the exhaust switching valve receives an instruction to open the valve and the exhaust air when the exhaust switching valve receives an instruction to close the valve. The abnormality determination device according to claim 1, wherein a failure diagnosis of the exhaust gas switching valve is performed based on at least one of an intake air amount. The plurality of control valves include an intake switching valve that switches between blocking and opening an intake passage connected to the second supercharger,
In the single turbo mode, the control unit includes the intake air amount when the intake switching valve receives an instruction to open the valve and the intake air valve when the intake switching valve receives an instruction to close the valve. The abnormality determination device according to claim 1, wherein a failure diagnosis of the intake switching valve is performed based on at least one of an intake air amount. The plurality of control valves include an intake switching valve that switches between blocking and releasing an intake passage connected to the second supercharger, and an outlet of a compressor of the second supercharger and the intake switching valve. An intake bypass valve that switches between blocking and releasing an intake bypass passage that communicates with the compressor inlet of the first supercharger,
The control unit, in the single turbo mode, the intake air amount when the intake bypass valve receives an instruction to close the valve, and the intake air amount when the intake bypass valve receives an instruction to open the valve The abnormality determination device according to claim 1, wherein a failure diagnosis of the intake bypass valve is performed based on at least one of an intake air amount.   5. The abnormality determination device according to claim 2, wherein failure diagnosis for one of the plurality of control valves is performed when the internal combustion engine is operated in an idle state immediately after starting. . The plurality of control valves are provided in an intake switching valve that switches between blocking and releasing an intake passage connected to the second supercharger, and an intake lead passage that communicates upstream and downstream of the intake switching valve. It has an intake reed valve that opens and closes according to the difference,
The said control part performs the failure diagnosis of the said intake reed valve based on the behavior of the said intake air amount when the said intake switching valve is closed in the said single turbo mode. The abnormality determination device described.   The abnormality determination device according to claim 6, wherein the failure diagnosis of the intake reed valve is performed when the vehicle is operated in a partial load state. First and second superchargers arranged in parallel;
A compressor inlet side air flow meter for detecting an intake air amount flowing into the second supercharger;
An air flow meter for detecting the total intake air amount of the internal combustion engine including the first and second superchargers;
A pressure sensor for detecting a supercharging pressure of the internal combustion engine;
In the twin turbo mode in which the first and second superchargers are used for supercharging, a surge diagnosis of the second supercharger is performed based on the intake air amount and the supercharging pressure, and the intake air An abnormality determination device for an internal combustion engine, comprising: a control unit configured to perform a surge diagnosis of the first supercharger based on the amount, the total intake air amount, and the supercharging pressure.

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