JP2015094300A - Failure diagnostic device of internal combustion engine with supercharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a failure diagnostic device of an internal combustion engine with a supercharger capable of suppressing degradation of exhausting performance by executing failure diagnosis of an opening and closing motion of a wastegate valve in cold start of the internal combustion engine.SOLUTION: A failure diagnostic device of an internal combustion engine with a supercharger, diagnoses failure of a wastegate valve of the internal combustion engine 1 which includes the supercharger 30 having a turbine 32 disposed in an exhaust passage 21 and a compressor 34 disposed in an intake passage 11, and supercharging intake air by an exhaust pressure, and an exhaust purification catalyst 24 disposed in the exhaust passage, and controls opening of the wastegate valve 31 in a cold start state. The failure diagnostic device includes cold start detecting means 39 for detecting whether the internal combustion engine 1 is in a cold start state or not, exhaust temperature detecting means 22 disposed in the exhaust passage between the wastegate valve and the exhaust purification catalyst, and detecting a temperature of the exhaust gas, and diagnosing means 50 for diagnosing failure in an opening and closing motion of the wastegate valve on the basis of the temperature of the exhaust gas in the cold start state.

Description

  The present invention relates to a failure diagnosis device for an internal combustion engine with a supercharger.

  A wastegate valve of an internal combustion engine with a supercharger may be unable to open and close due to sticking of a rotating shaft or valve, malfunction of an actuator, disconnection, etc. . Providing a waste gate valve with an opening sensor such as a rotary encoder significantly increases the cost, so it has been proposed to use a temperature sensor located downstream of the turbocharger to diagnose the failure of the opening and closing operation of the waste gate valve. (Patent Document 1). In this prior art, a temperature sensor is provided at a position where the temperature of the exhaust gas changes according to the opening degree of the waste gate valve, and a reference exhaust temperature corresponding to the opening degree of the waste gate valve is calculated in advance. And the detected value are compared to diagnose whether there is an abnormality in the opening / closing operation of the waste gate valve.

JP 2011-190778 A

  By the way, at the time of cold start of the internal combustion engine, it is necessary to fully open the waste gate valve and to flow high-temperature exhaust gas to the exhaust purification catalyst to activate the catalyst. However, in the above prior art, the failure diagnosis of the waste gate valve is not performed at the time of cold start of the internal combustion engine, so even though the waste gate valve is seized and fixed in the fully closed position at the time of cold start, this is not the case. If left unattended, there is a problem that the activation of the exhaust purification catalyst is delayed and the emission performance is lowered.

  The problem to be solved by the present invention is to provide a fault diagnosis device for an internal combustion engine with a supercharger that can suppress a deterioration in exhaust performance by performing fault diagnosis of the opening / closing operation of a waste gate valve at the time of cold start of the internal combustion engine. It is.

  The present invention solves the above problem by performing a failure diagnosis of the opening / closing operation of the waste gate valve based on the output of an exhaust temperature sensor provided between the waste gate valve and the exhaust purification catalyst when the internal combustion engine is cold. .

  According to the present invention, since the failure diagnosis of the opening / closing operation of the waste gate valve is performed at the time of cold start of the internal combustion engine, if the waste gate valve is broken at the time of cold start, it is possible to immediately call attention. As a result, it is possible to suppress a decrease in exhaust performance when the internal combustion engine is cold-started.

1 is a block diagram showing an internal combustion engine with a supercharger according to an embodiment of the present invention. It is an expanded sectional view which shows the state which the waste gate valve | bulb of FIG. 1 fully closed. It is an expanded sectional view which shows the state which the waste gate valve | bulb of FIG. 1 opened fully. 3 is a flowchart (No. 1) showing a control procedure by the control unit of FIG. 4 is a flowchart (part 2) illustrating a control procedure by the control unit of FIG. It is a time chart (at the time of a normal diagnosis) which shows the control procedure by the control unit of FIG. It is a time chart (at the time of abnormality diagnosis) which shows the control procedure by the control unit of FIG. FIG. 2 is a graph showing an example of exhaust temperature, upper and lower reference values, and estimated exhaust temperature when the waste gate valve of FIG. 1 is fully opened. 2 is a graph showing an example of an exhaust temperature, an upper limit reference value and a lower limit reference value, and an estimated exhaust temperature at the time of fully closing the waste gate valve of FIG. 1.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an internal combustion engine with a supercharger according to an embodiment of the present invention. In an intake passage 11 of the internal combustion engine 1 (engine), an air filter 12 and an air flow for detecting an intake air flow rate are shown. A meter 13, a throttle valve 14 for controlling the intake air flow rate, and a collector 15 are provided.

  The throttle valve 14 is provided with a throttle sensor that detects the opening degree of the throttle valve 14 and a throttle valve control device that can control the opening degree of the first throttle valve 14 by an actuator such as a DC motor. . The throttle valve control device electronically controls the opening degree of the throttle valve 14 based on a drive signal from the control unit 50 so as to achieve a required torque calculated based on a driver's accelerator pedal operation amount or the like.

  A fuel injection valve 17 is provided facing the combustion chamber 16 of each cylinder of the internal combustion engine 1. The fuel injection valve 17 is driven to open by a drive pulse signal set in the control unit 50, and pressure is supplied from a fuel pump (not shown) and is controlled to a predetermined pressure by a pressure regulator (not shown). Inject directly into. The internal combustion engine 1 of the present embodiment is not limited to such a direct injection engine, and the fuel from the fuel injection valve 17 is injected into the fuel injection port provided in the intake passage 11 in the vicinity of the combustion chamber 16, and the fuel, air, The internal combustion engine 1 that introduces the air-fuel mixture into the combustion chamber 16 may also be used.

  The spark plug 20 is mounted facing the combustion chamber 16 of each cylinder, and ignites the intake air-fuel mixture based on an ignition signal from the control unit 50. In addition, the internal combustion engine 1 of this example is not limited to a spark ignition engine, but can be applied to a diesel engine or other compression ignition engines.

On the other hand, the exhaust passage 21 is provided with an exhaust purification catalyst 24 for purifying the exhaust. The exhaust purification catalyst 24 oxidizes carbon monoxide CO and hydrocarbon HC in the exhaust in the vicinity of stoichiometric (theoretical air-fuel ratio, λ = 1, air weight / fuel weight = 14.7), and nitrogen oxide NOx. It is possible to use a three-way catalyst that can purify the exhaust gas by reducing the above, or an oxidation catalyst that oxidizes carbon monoxide CO and hydrocarbon HC in the exhaust gas.
In FIG. 1, reference numeral 23 denotes a muffler.

  The internal combustion engine 1 of this example is an engine having a supercharger 30, and the supercharger 30 shown in the figure is a turbine 32 provided in an exhaust passage 21 and a compressor 34 directly connected to the turbine 32 via a rotor shaft 33. The turbine 32 is rotated by the exhaust gas, and the intake air is compressed by the rotating compressor 34 thereby to be sent to the collector 15. On the turbine 32 side of the supercharger 30, a bypass passage 35 is provided in which part or all of the exhaust gas from the combustion chamber 16 bypasses the turbine 32 and reaches the exhaust purification catalyst 24. The surroundings of the turbine 32 and the bypass passage 35 are shown enlarged in FIGS. 2A and 2B. 2A is an enlarged cross-sectional view showing a state where the waste gate valve 31 fully closes the bypass passage 35, and FIG. 2B is an enlarged cross-sectional view showing a state where the waste gate valve 31 fully opens the bypass passage 35.

  A waste gate valve 31 that controls the ratio of the amount of exhaust gas passing through the bypass passage 35 and the amount of exhaust gas passing through the turbine 32 is provided at the outlet of the bypass passage 35. The waste gate valve 31 performs opening / closing control so that a part or all of the exhaust gas is released to the bypass passage 35 side so as to reach a target boost pressure corresponding to the operating state of the internal combustion engine 1. That is, when the target supercharging pressure is large, as shown in FIG. 2A, the opening degree of the waste gate valve 31 is decreased, the amount of exhaust gas passing through the bypass passage 35 is reduced, and the amount of exhaust gas passing through the turbine 32 is increased. To do. On the contrary, when the target supercharging pressure is small, as shown in FIG. 2B, the opening degree of the waste gate valve 31 is increased to increase the amount of exhaust gas passing through the bypass passage 35 and the amount of exhaust gas passing through the turbine 32. Reduce. The opening of the waste gate valve 31 refers to the opening from the position where the outlet of the bypass passage 35 shown in FIG. 2A is closed, and as the outlet of the bypass passage 35 is fully opened as shown in FIG. 2B. Opening is increased.

  The waste gate valve 31 is driven to open and close between a fully closed position shown in FIG. 2A and a fully opened position shown in FIG. An actuator 36 for this purpose is provided in the waste gate valve 31. An opening / closing command from the control unit 50 is output to the actuator 36. In addition, the waste gate valve 31 of this example is not provided with a valve opening degree sensor such as a positioning sensor that exclusively detects the opening degree. The supercharging pressure of the supercharger 30 is controlled by a rotation sensor of a motor built in the actuator 36 and a supercharging pressure sensor provided in the intake passage 11 (detected values of temperature sensors 25 and 26 before and after the compressor 34). The supply pressure may be calculated). An exhaust shut-off valve that controls the amount of exhaust gas passing through the exhaust passage 21 downstream of the turbine 32 may be provided downstream of the turbine 32 in the exhaust passage 21 and upstream of the junction with the bypass passage 35. .

  In the internal combustion engine 1 of this example, when the temperature of the exhaust purification catalyst 24 has not reached the activation temperature, such as when the cold engine is started, the waste gate valve 31 is fully opened as shown in FIG. 2B. Thus, high-temperature exhaust gas is supplied to the exhaust purification catalyst 24, and the temperature of the exhaust purification catalyst 24 is raised in a short time. The waste gate valve 31 is exposed to high-temperature exhaust gas and becomes high temperature, and the exhaust gas contains various foreign substances such as unburned gas and PM. May stick and cause poor opening / closing operation. The failure diagnosis of the opening / closing operation of the waste gate valve 31 of this example including this malfunction will be described later.

  An exhaust temperature sensor 22 that detects the temperature of the exhaust gas and outputs it to the control unit 50 is provided between the turbine 32 in the exhaust passage 21 and the exhaust purification catalyst 24. The exhaust temperature sensor 22 is provided to prevent the exhaust gas catalyst 24, the exhaust manifold 38, and the turbine 32 from being damaged due to a high temperature of the exhaust gas. A command signal for temporarily increasing the amount of fuel is output from the control unit 50 to the fuel injection valve 17, thereby executing control for returning the exhaust gas temperature to an appropriate temperature.

  In the internal combustion engine 1 of this example, the exhaust temperature sensor 22 is shared, and failure diagnosis of the opening / closing operation of the waste gate valve 31 is performed. For this reason, as shown in FIGS. 2A and 2B, the exhaust temperature sensor 22 is located at the position of the exhaust passage 21 where both the low-temperature exhaust gas that has passed through the turbine 32 and the high-temperature exhaust gas that has passed through the bypass passage 35 can be detected. Is provided. When exhaust gas flowing down from the combustion chamber 16 through the exhaust manifold 38 passes through the turbine 32, heat is absorbed by the turbine 32. Therefore, the exhaust gas temperature that has passed through the turbine 32 by fully closing the waste gate valve 31 as shown in FIG. 2A passes through the bypass passage 35 by fully opening the waste gate valve 31 as shown in FIG. 2B. It has been confirmed by the present inventor that a temperature difference of 100 to 150 degrees occurs as compared with the temperature of the exhaust gas.

  An intercooler 36 is provided between the downstream of the compressor 34 in the intake passage 11 and the throttle valve 14 to cool the intake air that has been compressed by the compressor 34 of the supercharger 30 and has reached a high temperature. The intercooler 36 can be either air-cooled or water-cooled. A recirculation passage 70 that bypasses the intercooler 36 is provided between the upstream side of the compressor 34 and the downstream side of the intercooler 36 in the intake passage 11, and a recirculation valve 71 is provided in the recirculation passage 70. The recirculation valve 71 opens and closes the recirculation passage 70 based on a drive signal from the control unit 50. For example, when the accelerator opening becomes zero and the throttle valve 14 is closed, the intake air compressed by the compressor 34 is recirculated. To the upstream of the intake passage 11.

  Temperature sensors 25 and 26 are provided on the upstream side and the downstream side of the compressor 34 in the intake passage 11, respectively, detecting the temperature of the intake air passing therethrough, and outputting the detection signal to the control unit 50. The temperature difference ΔT detected by the two temperature sensors 25, 26 is a difference in intake air temperature before and after being compressed by the supercharger 30 and heated up, and is thus regarded as a physical quantity corresponding to the work amount of the turbine 32. Can do. As a means for detecting the work amount of the turbine 32, pressure sensors are provided upstream and downstream of the compressor 34 instead of the temperature sensors 25 and 26, and the pressure difference before and after the compressor 34 is regarded as the work amount of the turbine 32. Good. Furthermore, instead of the temperature sensors 25 and 26 and the pressure sensor, a rotation sensor for detecting the rotation speed of the turbine 32 may be provided, and the work amount of the turbine 32 may be calculated from the rotation speed of the turbine 32.

  A crank angle sensor 27 is provided on the crankshaft of the internal combustion engine 1, and the control unit 50 counts a crank unit angle signal output from the crank angle sensor 27 in synchronization with the engine rotation for a certain period of time or By measuring the period of the reference angle signal, the engine speed Ne can be detected. The accelerator pedal operated by the driver is provided with an accelerator opening sensor 29 that detects an accelerator opening corresponding to the amount of depression, and the detection signal is output to the control unit 50. Further, a torque sensor 28 for detecting the torque of the drive system corresponding to the load of the internal combustion engine 1 is provided in the drive system, and the detection signal is output to the control unit 50. Further, a water temperature sensor 39 is provided on the cooling jacket of the internal combustion engine 1 so as to face the cooling jacket, detects the cooling water temperature in the cooling jacket, and outputs it to the control unit 50. The water temperature sensor 39 of this example is also used as means for detecting the cold start state of the internal combustion engine 1.

  As described above, the detection signals from the various sensors 13, 14, 22, 25, 26, 27, 28, 29, 39 include the CPU, ROM, RAM, A / D converter, input / output interface, and the like. The control unit 50 is configured to control the opening of the throttle valve 14 in accordance with the operating state detected based on signals from the sensors, and to inject fuel. The valve 17 is driven to control the fuel injection amount, the ignition timing is set, and the ignition plug 20 is ignited at the ignition timing.

  Next, a control procedure relating to failure diagnosis of the waste gate valve 31 in the control unit 50 will be described. 3 and 4 are flow charts showing the control procedure by the control unit 50, FIGS. 5 and 6 are also time charts at the time of control, FIG. 5 shows at the time of normal diagnosis, and FIG.

  First, in step ST1, it is determined whether or not the internal combustion engine 1 has been driven. The failure diagnosis of the waste gate valve 31 in this example is executed while the internal combustion engine 1 is being driven. The driving of the internal combustion engine 1 can be determined, for example, based on whether or not the output from the crank angle sensor 27 input to the control unit 50 is ON / OFF at a predetermined cycle. If the internal combustion engine 1 is driven, the process proceeds to step ST2, and if not, step ST1 is repeated until the internal combustion engine 1 is driven.

  In step ST2, it is determined whether or not the internal combustion engine 1 is in a cold start state. The cold start state of the internal combustion engine 1 is detected when the temperature of the engine coolant detected by the water temperature sensor 39 is equal to or lower than a predetermined value, and is determined to be a cold start state. Judge that there is no. The cold start state is detected by measuring or estimating the temperature of the exhaust purification catalyst 24 in addition to the temperature of the engine coolant by the water temperature sensor 39, and in the cold start state when the temperature of this catalyst is a predetermined value or less. If it is determined that there is a predetermined value, it may be determined that the engine is not in the cold start state. If the internal combustion engine 1 is in the cold start state, the process proceeds to step ST3. If not, the process proceeds to step ST14.

  In step ST3, a command to fully open the waste gate valve (WGV) 31 is output to the actuator 36. As a result, the outlet of the bypass passage 35 is opened as shown in FIG. 2B, so that most of the exhaust gas flowing down from the exhaust manifold 38 passes through the bypass passage 35 and flows into the exhaust purification catalyst 24. As described above, the exhaust gas that has passed through the bypass passage 35 is about 100 to 150 degrees higher than the exhaust gas that has passed through the turbine 32, so that by introducing this into the exhaust purification catalyst 24, The temperature can be raised to the activation temperature in a short time. Note that the opening of the waste gate valve 31 here is not limited to full opening, but may be any opening that is substantially fully open.

In step ST4, and is stored in advance in the memory of the control unit 50 reads out the first basic exhaust gas temperature T ₁₀ at the time of full opening of the waste gate valve 31. The first basic exhaust gas temperature T ₁₀ is obtained in advance measured exhaust gas temperature within, for example, 20 seconds after start the internal combustion engine 1 (so-called fast idling state), and then stores it in memory.

In step ST5, it is determined whether or not the engine rotation speed Ne is stable. The stability determination of the engine rotation speed can be determined based on whether or not the variation in the rotation speed Ne detected by the crank angle sensor 27 has converged within a predetermined range. 5 and as shown in the time chart of FIG. 6, the engine speed immediately after engine start t ₀ enters the stable region from soaring Once engine start t ₀ immediately after the period (until the start of diagnosis t ₁₎ in the exhaust gas This is because the temperature is not stable and is not suitable for failure diagnosis. If the engine speed is stable, the process proceeds to step ST6, and if it is not stable, steps ST4 and 5 are repeated.

In step ST6, and inputs the actual temperature T ₁ of the exhaust gas between the by the exhaust temperature sensor 22 and the turbine 32 and the exhaust purification catalyst 24. Then, in step ST7, and correcting the first basic exhaust gas temperature _{T 10} read in step ST4 to the current operating condition, to calculate a first estimated exhaust gas temperature _{T 1e.} The calculation of the first estimated exhaust temperature according to the operating state is performed by calculating the rotational speed Ne of the internal combustion engine 1, the ignition timing of the spark plug 20, the intake air amount, the air-fuel ratio of the injected fuel from the fuel injection valve 17, the intake valve and the exhaust valve. This is performed in consideration of the opening / closing timing, the coolant temperature of the internal combustion engine 1, the intake air temperature, the outside air temperature, and the response delay time of the exhaust temperature sensor 22.

Since the exhaust gas after burning in the combustion chamber 16 varies in time to reach the exhaust temperature sensor 22 in accordance with the rotational speed Ne of the internal combustion engine 1, the exhaust manifold 38 and the exhaust temperature sensor 22 are provided from the combustion chamber 16. correcting the first basic exhaust gas temperature T ₁₀ from the volume of the exhaust passage 21 to the position. Further, as the ignition timing of the spark plug 20 is retarded, the exhaust gas at the end of combustion is exhausted more, so the exhaust gas temperature becomes higher than when the ignition timing is advanced. The relationship between the ignition timing and the exhaust gas temperature to correct the first basic exhaust gas temperature T _10. Further, when the intake air amount increases, the combustion energy increases, so that the exhaust gas temperature increases. When the air-fuel ratio of the injected fuel deviates from the stoichiometry, the combustion energy decreases, so the exhaust gas temperature decreases. The relationship between the intake air amount and the exhaust gas temperature and the air-fuel ratio and the exhaust gas temperature to correct the first basic exhaust gas temperature T _10. Similarly, the relationship between the opening and closing timing of the intake valve and the exhaust valve and the exhaust gas temperature, the relationship between the cooling water temperature and the exhaust gas temperature, the relationship between the intake air temperature and the exhaust gas temperature, the relationship between the outside air temperature and the exhaust gas temperature, response delay time of the exhaust gas temperature sensor 22 and previously acquired in advance by actual experiments or simulations such as the relationship between the exhaust gas temperature, corrects the first basic exhaust gas temperature T ₁₀ on the basis of these relationships. The step ST7 above, the first estimated exhaust gas temperature T _{1e (dashed} line) obtained by adding the correction to the first basic exhaust gas temperature T ₁₀ indicated by a dotted line at the top of FIG. 5 and FIG. 6 are calculated.

In step ST8, an upper limit value T _1emax and a lower limit value T _1emin are set for the first estimated exhaust gas temperature T _1e calculated in step ST7. The predetermined widths | T _1emax −T _1e | and | T _1e −T _1emin | with respect to the first estimated exhaust gas temperature T _1e are acquired in advance by actual machine experiments and simulations. FIG. 7 is a graph showing an example of the actual exhaust temperature, the first estimated exhaust temperature, and the upper limit value / lower limit value when the waste gate valve 31 is fully opened. Since the first reference temperature range T _{1emax to} T _1emin centered on the first estimated exhaust temperature T _1e is set by the above steps, in step ST9, the actual exhaust temperature T ₁ detected by the exhaust temperature sensor 22 is determined. It is determined whether the temperature is within the first reference temperature range. If the actual exhaust temperature _{T 1} is in the first reference temperature range _{T 1emax ~T 1emin} proceeds to step ST10, the process proceeds to step ST11 otherwise.

In step ST10, it is determined that the exhaust gas temperature sensor 22 has detected high-temperature exhaust gas by fully opening the waste gate valve 31, and the opening / closing operation at the opening degree near the fully open state of the waste gate valve 31 is a problem such as seizure sticking. Not diagnosed as normal. It corresponds to the start of the diagnosis t ₁ later in the time chart of FIG. 5.

In step ST11, since the actual exhaust gas temperature _{T 1} is not within the first reference temperature range _{T 1emax ~T 1emin,} determines whether less than the lower limit value _{T 1Emin} the first reference temperature range. In fact when the exhaust gas temperature _{T 1} is less than the lower limit value _{T 1Emin} the first reference temperature range, the process proceeds to step ST12, if not, that the actual exhaust temperature _{T 1} is the upper limit _{T 1Emax} the first reference temperature range When exceeding, it progresses to step ST13. In step ST12, since the actual exhaust gas temperature T ₁ is less than the lower limit value T _1Emin the first reference temperature range, the waste gate valve 31 is a malfunction, such as whole closed or fixed at close to this closed state caused As a result, it is determined that the exhaust gas flowing down from the exhaust manifold 38 has passed through the turbine 32. Then, the waste gate valve 31 is diagnosed as having an abnormal opening / closing operation at an opening degree near the fully closed state, and a predetermined alert is given, such as turning on a warning indicator lamp. It corresponds to the start of the diagnosis t ₁ later in the time chart of FIG. 6.

In contrast, in step ST13, since the actual exhaust gas temperature T ₁ is is at a temperature exceeding the upper limit T _1Emax the first reference temperature range, high temperature exhaust temperature anomaly by the internal combustion engine 1 itself is misfiring or partial misfire It is diagnosed as having become, and a predetermined alert is given, such as turning on a warning indicator.

  On the other hand, even when the internal combustion engine 1 is not in the cold start state in step ST2 in FIG. 3, that is, when the internal combustion engine 1 is in the warm state, the failure diagnosis of the opening / closing operation of the waste gate valve 31 can be performed. If the internal combustion engine 1 is in a warm-up state, a command to fully close the waste gate valve 31 is output to the actuator 36 in step ST14. As a result, the outlet of the bypass passage 35 is closed as shown in FIG. 2A, so that most of the exhaust gas flowing down from the exhaust manifold 38 passes through the turbine 32 and flows into the exhaust purification catalyst 24. Note that the opening degree of the waste gate valve 31 here is not limited to being fully closed, but may be any opening degree that is substantially fully closed.

In step ST15, and is stored in advance in the memory of the control unit 50 reads the wastegate second basic exhaust gas temperature T ₂₀ fully closed the valve 31. The second basic exhaust gas temperature T ₂₀ is one in which the internal combustion engine 1 is measured in advance exhaust gas temperature in a state of fully closed wastegate valve 31 in the warm-up state, was stored into the memory.

  In step ST16, it is determined whether or not the engine rotation speed Ne is stable. The stability determination of the engine rotation speed can be determined based on whether or not the variation in the rotation speed Ne detected by the crank angle sensor 27 has converged within a predetermined range. This is because if the engine speed varies, the temperature of the exhaust gas is not stable and is not suitable for failure diagnosis. If the engine speed is stable, the process proceeds to step ST17. If the engine speed is not stable, step ST15 is repeated.

In step ST17, inputs an actual temperature T ₂ of the exhaust gas between the exhaust gas temperature sensor 22 and the turbine 32 and the exhaust purification catalyst 24. Then, in step ST18, and correcting the second basic exhaust gas temperature _{T 20} read out in step ST15 to the current operating condition, to calculate a second estimated exhaust gas temperature _{T 2e.} The calculation of the second estimated exhaust gas temperature according to the operating state is similar to step ST7 in FIG. 3. The rotational speed Ne of the internal combustion engine 1, the ignition timing of the spark plug 20, the intake air amount, the amount of fuel injected from the fuel injection valve 17 are calculated. This is performed in consideration of the air / fuel ratio, the opening / closing timing of the intake valve and the exhaust valve, the cooling water temperature of the internal combustion engine 1, the intake air temperature, the outside air temperature, and the response delay time of the exhaust temperature sensor 22.

In step ST19, it sets the upper limit value _{T 2Emax} and the lower limit value _{T 2Emin} the second estimated exhaust gas temperature _{T 2e} calculated in step ST18. The predetermined widths | T _2emax −T _2e | and | T _2e −T _2emin | with respect to the second estimated exhaust gas temperature T _2e are acquired in advance by actual machine experiments and simulations. FIG. 8 is a graph showing an example of the actual exhaust temperature, the second estimated exhaust temperature, and the upper limit value / lower limit value when the waste gate valve 31 is instructed to be fully closed. Since the second reference temperature range T _{2emax to} T _2emin centering on the second estimated exhaust temperature T _2e is set by the above steps, the actual exhaust temperature T ₂ detected by the exhaust temperature sensor 22 is set in step ST20. It is determined whether the temperature is within the second reference temperature range. If the actual exhaust temperature _{T 2} is within the second reference temperature range _{T 2emax ~T 2emin} proceeds to step ST21, the process proceeds to step ST22 otherwise.

  In step ST21, it is determined that the exhaust gas temperature sensor 22 has detected low-temperature exhaust gas by fully closing the waste gate valve 31, and the opening / closing operation at the opening degree near the fully closed state of the waste gate valve 31 is seizure sticking or the like. Diagnose that it was done normally without any problems.

In step ST22, since the actual exhaust temperature _{T 2} is not within the second reference temperature range _{T 2emax ~T 2emin,} determines whether less than the lower limit value _{T 2Emin} the second reference temperature range. In fact when the exhaust temperature _{T 2} is less than the lower limit value _{T 2Emin} the second reference temperature range, the process proceeds to step ST23, if not, that the actual exhaust temperature _{T 2} the upper limit _{T 2Emax} the second reference temperature range When exceeding, it progresses to step ST24. In step ST23, since the actual exhaust temperature T ₂ is less than the lower limit value T _2Emin the second reference temperature range, it is diagnosed as outputs a low-temperature detection signal failed those that exhaust gas temperature sensor 22 . Then, a predetermined warning is given, such as turning on a warning indicator light indicating that the exhaust temperature sensor 22 has a failure.

In contrast, in step ST24, since the actual exhaust temperature T ₂ is at a temperature above the upper limit T _2Emax the second reference temperature range, high temperature exhaust temperature anomaly by the internal combustion engine 1 itself is misfiring or partial misfire It is determined that the exhaust gas flowing down from the exhaust manifold 38 has passed through the bypass passage 35 as a result of malfunction such as the waste gate valve 31 being fully opened or being stuck in an open state close thereto. . Then, the waste gate valve 31 is diagnosed as having an abnormal opening / closing operation at an opening degree near the full opening, or the exhaust gas temperature has become abnormally high due to misfire or partial misfire, etc. Precise alerts such as turning on.

As described above, according to the failure diagnosis apparatus for an internal combustion engine with a supercharger according to this embodiment, the following effects can be obtained.
(1) In this example, since the failure diagnosis of the opening / closing operation of the waste gate valve 31 is performed when the internal combustion engine 1 is cold-started, if the waste gate valve 31 is broken at the time of cold-start, the user can be alerted immediately. it can. As a result, it is possible to suppress a decrease in exhaust performance when the internal combustion engine 1 is cold-started. In particular, since the waste gate valve 31 needs to be fully opened in order to raise the temperature of the exhaust purification catalyst 24 at the time of cold start, the failure can be diagnosed using this period.

(2) In this example, if the cold start state of the internal combustion engine 1 is detected by the temperature of the engine cooling water, the temperature drop of the cooling water is slower than the temperature drop of the exhaust purification catalyst 24. In other words, the temperature of the cooling water Is lower than the predetermined value, the exhaust purification catalyst 24 is always at an inactive temperature, so that the cold state of the exhaust purification catalyst 24 can be detected with high accuracy.

(3) In this example, the exhaust temperature according to the operating state is estimated, the first reference temperature range is set based on this, and the first reference temperature range is compared with the actual temperature. Can be prevented.

(4) In this example, based on the knowledge that if the waste gate valve 31 is fully opened, high-temperature exhaust gas is detected, while if the waste gate valve 31 is fully closed, low-temperature exhaust gas is detected. The abnormality of the opening / closing operation of the waste gate valve 31 in the vicinity of full opening and in the vicinity of full closing is diagnosed. When the actual temperature of the detected exhaust gas is within the first reference temperature range on the high temperature side, it is considered that the waste gate valve is normally fully opened. Can be diagnosed as normal. On the other hand, when the actual temperature of the detected exhaust gas is lower than the first reference temperature range, the waste gate valve 31 does not open but is stuck and stuck in the closed state. Since it is considered that some trouble has occurred on the valve closing side of the valve 31, it can be diagnosed that the opening / closing operation on the valve closing side is abnormal. Further, when the detected actual temperature of the exhaust gas is higher than the first reference temperature range on the high temperature side, it is considered that the waste gate valve 31 is no longer malfunctioning, so that it is diagnosed that the internal combustion engine 1 is abnormal. can do.

(5) In this example, a failure of the waste gate valve 31 can be diagnosed even in a warm-up state other than the cold-start state. For this diagnosis as well, waste gas is detected when the waste gate valve 31 is fully opened, while low temperature exhaust gas is detected when the waste gate valve 31 is fully closed. Abnormalities in the opening / closing operation of the gate valve 31 in the vicinity of the fully opened state and in the vicinity of the fully closed state are diagnosed. In this case, when the waste gate valve 31 is fully closed and the actual temperature of the detected exhaust gas is within the second reference temperature range of the low temperature side exhaust gas, the waste gate valve 31 is normal. Therefore, it can be diagnosed that the opening / closing operation of the waste gate valve on the closed side is normal. On the other hand, when the detected actual temperature of the exhaust gas is lower than the second reference temperature range on the low temperature side, it is considered that the waste gate valve 31 is no longer malfunctioning. Can be diagnosed. Further, when the actual temperature of the detected exhaust gas is higher than the second reference temperature range on the low temperature side, the waste gate valve 31 does not normally fully close and flows down the bypass passage 35 to detect the high temperature exhaust gas. It is considered that either high temperature exhaust gas has been detected due to misfire or the like of the internal combustion engine 1, so that an abnormal opening / closing operation of the waste gate valve 31 or an abnormality of the internal combustion engine 1 Can be diagnosed.

  The water temperature sensor 39 corresponds to cold start detection means according to the present invention, the exhaust temperature sensor 22 corresponds to exhaust temperature detection means according to the present invention, and the control unit 50 corresponds to diagnostic means according to the present invention.

1 ... Internal combustion engine
DESCRIPTION OF SYMBOLS 11 ... Intake passage 12 ... Air filter 13 ... Air flow meter 14 ... Throttle valve 15 ... Collector 16 ... Combustion chamber 17 ... Fuel injection valve 20 ... Spark plug 21 ... Exhaust passage 22 ... Exhaust temperature sensor 23 ... Muffler 24 ... Exhaust purification catalyst 25 ... Temperature sensor 26 ... Temperature sensor 27 ... Crank angle sensor 28 ... Torque sensor 29 ... Accelerator opening sensor 30 ... Supercharger 31 ... Waste gate valve 32 ... Turbine 33 ... Rotor shaft 34 ... Compressor 35 ... Bypass passage 36 ... Actuator 37 ... Intercooler 38 ... Exhaust manifold 39 ... Water temperature sensor 50 ... Control unit (control means)
70 ... Reflux passage 71 ... Reflux valve

Claims (11)

A cooler starter comprising a turbocharger provided in the exhaust passage and a compressor provided in the intake passage for supercharging intake air by exhaust pressure, and an exhaust purification catalyst provided in the exhaust passage. In the internal combustion engine for controlling the opening of the waste gate valve in a state, in the internal combustion engine failure diagnosis device for diagnosing a failure of the waste gate valve,
Cold start detection means for detecting whether or not the internal combustion engine is in a cold start state;
An exhaust temperature detecting means provided in the exhaust passage between the waste gate valve and the exhaust purification catalyst for detecting the temperature of the exhaust gas;
A failure diagnosis apparatus for an internal combustion engine with a supercharger, comprising: diagnosis means for diagnosing a failure in the opening / closing operation of the waste gate valve based on a temperature of the exhaust gas in the cold start state. The cold start detection means includes a water temperature sensor for detecting the temperature of the cooling water of the internal combustion engine,
The failure diagnosis device for an internal combustion engine with a supercharger according to claim 1, wherein when the temperature of the cooling water is equal to or lower than a predetermined value, it is detected that the engine is in the cold start state. The diagnostic means includes
Calculating an estimated exhaust temperature based on the operating state of the internal combustion engine, and setting a first reference temperature range for the estimated exhaust temperature;
3. The turbocharger according to claim 1, wherein a failure in the opening / closing operation of the waste gate valve is diagnosed by comparing an actual temperature of the exhaust gas detected by the exhaust temperature detecting means with the first reference temperature range. Fault diagnosis device for internal combustion engine with a valve.   The operating state of the internal combustion engine includes the rotational speed of the internal combustion engine, the ignition timing, the intake air amount, the air / fuel ratio of the injected fuel, the intake valve and exhaust valve opening / closing timing, the cooling water temperature of the internal combustion engine, the intake air temperature, the outside air temperature, The failure diagnosis device for an internal combustion engine with a supercharger according to claim 3, comprising a response time of the temperature detection means.   The diagnostic means diagnoses that the opening / closing operation on the valve opening side of the waste gate valve is normal when the actual temperature of the exhaust gas is within the first reference temperature range in the cold start state. Or a failure diagnosis device for an internal combustion engine with a supercharger as described in 4;   The diagnosis means diagnoses that the opening / closing operation on the valve closing side of the waste gate valve is abnormal when the actual temperature of the exhaust gas is lower than the first reference temperature range in the cold start state. The failure diagnosis device for an internal combustion engine with a supercharger according to any one of claims 5 to 6.   The diagnosis means diagnoses that the internal combustion engine is abnormal when the actual temperature of the exhaust gas is higher than the first reference temperature range in the cold start state. Diagnostic apparatus for internal combustion engine with supercharger. The diagnostic means includes
Output a command signal to close the waste gate valve when not in the cold start state,
8. The diagnosis according to claim 3, wherein when the actual temperature of the exhaust gas is within a preset second reference temperature range of the exhaust gas, the opening / closing operation on the valve closing side of the waste gate valve is diagnosed as normal. The failure diagnosis device for an internal combustion engine with a supercharger according to claim 1.   The supercharging according to claim 8, wherein the diagnosis unit diagnoses that the exhaust temperature detection unit is abnormal when the actual temperature of the exhaust gas is lower than the second reference temperature range when not in the cold start state. Fault diagnosis device for internal combustion engine with a machine.   When the actual temperature of the exhaust gas is higher than the second reference temperature range when the engine is not in the cold start state, the diagnosis means is caused by an abnormality in an opening / closing operation on the valve opening side of the waste gate valve or an abnormality in the internal combustion engine. The failure diagnosis device for an internal combustion engine with a supercharger according to claim 8 or 9, which diagnoses that there is a turbocharger. A cooler starter comprising a turbocharger provided in the exhaust passage and a compressor provided in the intake passage for supercharging intake air by exhaust pressure, and an exhaust purification catalyst provided in the exhaust passage. In the internal combustion engine that controls the opening of the waste gate valve in a state, in the internal combustion engine failure diagnosis method for diagnosing a failure of the waste gate valve,
Detecting whether the internal combustion engine is in a cold start state,
When the internal combustion engine is in a cold machine vibration state, the waste gate valve is opened, and in this state, the temperature of the exhaust gas between the waste gate valve and the exhaust purification catalyst is detected,
When the actual temperature of the exhaust gas in the cold start state is within a preset first reference temperature range of the exhaust gas, the opening / closing operation on the valve opening side of the waste gate valve is diagnosed as normal,
When the actual temperature of the exhaust gas in the cold start state is lower than the first reference temperature range, it is diagnosed that the opening / closing operation on the valve closing side of the waste gate valve is abnormal,
A failure diagnosis method for a supercharged internal combustion engine that diagnoses that the internal combustion engine is abnormal when an actual temperature of the exhaust gas in the cold start state is higher than the first reference temperature range.

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