JP2020169574A - Failure analysis device of supercharger - Google Patents

Abstract

To precisely analyze a failure of a mechanical supercharger.SOLUTION: This failure analysis device of a supercharger has: an electromagnetic clutch (45) for switching the connection of an engine output shaft and a mechanical supercharger (44); a bypass passage (47) bypassing the supercharger; a bypass control valve (48) for opening and closing the bypass passage; a supercharger rotation number sensor (SW8); an engine rotation number sensor (SW9); and a control unit (10a). The control unit connects the electromagnetic clutch at supercharging, closes the bypass control valve, brings the electromagnetic clutch into a non-connection state, and opens the bypass control valve at non-supercharging. When a rotation number of the supercharger is equal to a prescribed rotation number or smaller in a supercharged state, the control unit also brings the electromagnetic clutch into the non-connection state, closes the bypass control valve, and sets an idling state, and when the engine rotation number is lowered in the idling state, determines a failure of the supercharger.SELECTED DRAWING: Figure 5

Description

The present invention relates to a failure diagnosis device for a supercharger, and more particularly to a failure diagnosis device for a supercharger for diagnosing a failure of a mechanical supercharger provided in an intake passage of an engine.

Japanese Unexamined Patent Publication No. 2015-68290 (Patent Document 1) describes a control device for an internal combustion engine. The control device of the internal combustion engine includes a mechanical supercharger provided in the intake passage and transmitting the output of the internal combustion engine, a bypass passage connecting the upstream side and the downstream side of the mechanical supercharger, and a bypass passage. It includes a bypass valve that opens and closes, and a throttle valve that is arranged on the downstream side of the confluence of the bypass passage of the intake passage. In this device, when supercharging is performed by a mechanical supercharger, the intake air is pressurized by the mechanical supercharger and sent to the internal combustion engine by closing the bypass valve. On the other hand, when supercharging is not performed, the intake air is sent to the internal combustion engine through the bypass passage by opening the bypass valve.

Further, the internal combustion engine control device described in Patent Document 1 includes a closed sticking detecting means for detecting the closed sticking of the bypass valve, and when the closed sticking of the bypass valve is detected, the target opening degree of the throttle valve is determined. The opening is set to be equal to or larger than the opening, and fuel cut control that limits fuel injection is executed. In this way, if the bypass valve has a problem such as closing and sticking, an unintended supercharging will be performed on the internal combustion engine, which may cause a problem such as an excessive temperature rise of the intake passage or the like. is there. In the invention described in Patent Document 1, when the bypass valve is detected to be closed and stuck, the occurrence of a problem is avoided by taking appropriate measures such as fuel cut control. In this way, when a problem occurs around the supercharger of the internal combustion engine, it is necessary to detect it at an early stage and take appropriate measures.

JP-A-2015-68290

In addition to the sticking of the bypass valve as described above, the mechanical supercharger itself may also stick, and in such a case, supercharging cannot be performed. The sticking of the mechanical supercharger can be detected based on the rotation speed measured by the supercharger rotation speed sensor provided with the supercharger rotation speed sensor for detecting the rotation speed of the supercharger. However, the measured turbocharger rotation speed may show an abnormal value due to the failure of the supercharger rotation speed sensor itself, and in such a case, the mechanical supercharger itself is normal. Nevertheless, there is a risk that the supercharger will be determined to be out of order. As described above, when the state of failure cannot be accurately determined, there is a problem that appropriate measures cannot be taken due to maintenance or the like, or extra man-hours may be required for maintenance.
Therefore, an object of the present invention is to provide a supercharger failure diagnosis device capable of accurately diagnosing a failure of a mechanical supercharger.

In order to solve the above-mentioned problems, the present invention is a supercharger failure diagnosis device for diagnosing a failure of a mechanical supercharger provided in an intake passage of an engine, and is an engine output shaft and a machine. An electromagnetic clutch that can be switched between connection and non-connection with the turbocharger, and a bypass passage connected to the intake passage so as to bypass the mechanical turbocharger and supply intake air into the cylinder of the engine. A bypass control valve provided in this bypass passage that opens and closes the bypass passage, a turbocharger rotation speed sensor for detecting the rotation speed of the mechanical supercharger, and a rotation speed of the output shaft of the engine are detected. It has an engine speed sensor and a control unit that controls an electromagnetic clutch and a bypass control valve, and the control unit switches the electromagnetic clutch to a connected state when a preset supercharging condition is satisfied. , The bypass control valve is closed, the engine is supercharged, and when the preset supercharging conditions are not met, the electromagnetic clutch is switched to the non-connected state and the bypass control valve is opened. , The control unit is configured to put the engine in a non-supercharged state, and in the supercharged state of the engine, the rotation speed of the mechanical supercharger detected by the supercharger rotation speed sensor is equal to or less than the predetermined rotation speed. If this is the case, the electromagnetic clutch is switched to the disconnected state, and the bypass control valve is set as the closing side to set the idling state in which the intake air flows into the mechanical turbocharger that is not connected to the engine. The unit is characterized in that when a decrease in the engine speed is detected by the engine speed sensor in the idling state, it is determined that the mechanical turbocharger is out of order.

In the present invention configured as described above, in the case of supercharging, the control unit connects the output shaft of the engine and the mechanical supercharger and sets the bypass control valve on the closed side. As a result, the intake air is pressurized through the supercharger side and supplied into the cylinder of the engine. On the other hand, when supercharging is not performed, the control unit disconnects the output shaft of the engine from the mechanical supercharger and sets the bypass control valve on the open side. As a result, the intake air is supplied into the cylinder of the engine mainly through the bypass passage side having low flow path resistance without being pressurized by the mechanical supercharger. Further, in the idling state in which the electromagnetic clutch is disconnected and the bypass control valve is closed, the intake air is mainly sucked through the mechanical turbocharger that is disconnected. Here, when the rotor of the mechanical turbocharger or the like is stuck, the flow path resistance of the air passing through the mechanical turbocharger in the idling state increases, so that the amount of air sucked into the engine increases. descend.

According to the present invention configured as described above, when a decrease in the engine speed is detected by the engine speed sensor in the idling state, the control unit determines that the mechanical turbocharger is out of order. Therefore, it is possible to prevent the failure of the turbocharger rotation speed sensor from being erroneously determined as the failure of the mechanical supercharger. This makes it possible to accurately diagnose the failure of the mechanical turbocharger.

In the present invention, preferably, the control unit determines that the supercharger rotation speed sensor is out of order when the engine rotation speed sensor does not detect a decrease in the engine rotation speed in the idling state.

According to the present invention configured as described above, if the engine speed sensor does not detect a decrease in the engine speed in the idling state, it is determined that the turbocharger speed sensor is out of order. In addition to the turbocharger, it is possible to diagnose a failure of the turbocharger rotation speed sensor.

In the present invention, preferably, the control unit sets an idling state when the engine is idling.
According to the present invention configured in this way, when the engine is idling, the idling state is set and the failure of the mechanical supercharger is determined. Therefore, even if the mechanical supercharger is stuck. It is difficult for the engine to stop, and it is possible to suppress the driver from feeling uncomfortable.

In the present invention, preferably, the control unit sets an idling state when the vehicle equipped with the engine is stopped.
According to the present invention configured in this way, when the vehicle equipped with the engine is stopped, the idling state is set and the failure of the mechanical supercharger is determined, so that the mechanical supercharger is fixed. Therefore, even if the engine is stopped, it is possible to suppress giving a strong sense of discomfort to the driver.

According to the supercharger failure diagnosis device of the present invention, the failure of the mechanical supercharger can be accurately diagnosed.

It is a figure which illustrates the structure of the engine to which the failure diagnosis apparatus of the supercharger according to 1st Embodiment of this invention is applied. It is sectional drawing which illustrates the structure of the combustion chamber of the engine to which the failure diagnosis apparatus of the supercharger according to 1st Embodiment of this invention is applied. It is a block diagram which illustrates the structure of the engine to which the failure diagnosis apparatus of the supercharger according to 1st Embodiment of this invention is applied. It is a figure which shows an example of the operation area of the engine to which the failure diagnosis apparatus of the supercharger according to 1st Embodiment of this invention is applied. It is a flowchart which shows the operation of the failure diagnosis apparatus of a supercharger by 1st Embodiment of this invention. It is a flowchart which shows the operation of the failure diagnosis apparatus of a supercharger by 2nd Embodiment of this invention.

Hereinafter, a failure diagnosis device for a turbocharger according to an embodiment of the present invention will be described with reference to the accompanying drawings.

<Device configuration>
First, the configuration of the failure diagnosis device for the turbocharger according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 is a diagram illustrating an engine configuration to which a failure diagnosis device for a supercharger according to the present embodiment is applied. FIG. 2 is a cross-sectional view illustrating the configuration of the combustion chamber of the engine to which the failure diagnosis device of the supercharger according to the present embodiment is applied. The intake side in FIG. 1 is on the left side of the paper, and the exhaust side is on the right side of the paper. The intake side in FIG. 2 is on the right side of the paper, and the exhaust side is on the left side of the paper. FIG. 3 is a block diagram illustrating the configuration of an engine to which the failure diagnosis device of the supercharger according to the present embodiment is applied.

In the present embodiment, the engine 1 is a gasoline engine that performs partial compression ignition combustion (SPark Controlled Compression Ignition: SPCCI) mounted on a four-wheeled automobile. Specifically, the engine 1 includes a cylinder block 12 and a cylinder head 13 mounted on the cylinder block 12. A plurality of cylinders 11 are formed inside the cylinder block 12. Although only one cylinder 11 is shown in FIGS. 1 and 2, the engine 1 is a multi-cylinder engine in the present embodiment.

A piston 3 is slidably inserted in each cylinder 11. The piston 3 is connected to the crankshaft 15 via a connecting rod 14. The piston 3 partitions the combustion chamber 17 together with the cylinder 11 and the cylinder head 13. The "combustion chamber" is not limited to the meaning of the space formed when the piston 3 reaches the compression top dead center. The term "combustion chamber" may be used in a broad sense. That is, the "combustion chamber" may mean a space formed by the piston 3, the cylinder 11, and the cylinder head 13 regardless of the position of the piston 3.

As shown in FIG. 2, the upper surface of the piston 3 is a flat surface. A cavity 31 is formed on the upper surface of the piston 3. The cavity 31 is recessed from the upper surface of the piston 3. The cavity 31 has a shallow dish shape. The cavity 31 faces the injector 6, which will be described later, when the piston 3 is located near the compression top dead center.

The cavity 31 has a convex portion 31a. The convex portion 31a is provided substantially at the center of the cylinder 11. The convex portion 31a has a substantially conical shape and extends upward from the bottom of the cavity 31 along the central axis X of the cylinder 11. The upper end of the convex portion 31a is substantially the same height as the upper surface of the cavity 31. The cavity 31 also has a recessed portion 31b provided around the convex portion 31a.

As shown in FIG. 2, the lower surface of the cylinder head 13, that is, the ceiling surface of the combustion chamber 17, is composed of an inclined surface 13a and an inclined surface 13b. The inclined surface 13a has an upward slope from the intake side toward the axis X. The inclined surface 13b has an upward slope from the exhaust side toward the axis X. The ceiling surface of the combustion chamber 17 has a so-called pent roof shape.
The shape of the combustion chamber 17 is not limited to the shape illustrated in FIG. For example, the shape of the cavity 31, the shape of the upper surface of the piston 3, the shape of the ceiling surface of the combustion chamber 17, and the like can be changed as appropriate.

The geometric compression ratio of the engine 1 is set high for the purpose of improving the theoretical thermal efficiency and stabilizing the CI (Compression Ignition) combustion described later. Specifically, the geometric compression ratio of the engine 1 is 17 or more. The geometric compression ratio may be 18, for example. The geometric compression ratio may be appropriately set in the range of 17 or more and 20 or less.

The cylinder head 13 is formed with two intake ports 18 (FIG. 1) for each cylinder 11. The intake port 18 communicates with the combustion chamber 17. An intake valve 21 is provided at the intake port 18. The intake valve 21 opens and closes between the combustion chamber 17 and the intake port 18. The intake valve 21 is opened and closed at a predetermined timing by the intake valve mechanism. In the present embodiment, the intake valve mechanism has an intake electric VVT (Variable Valve Timing) 23 (FIG. 3) which is a variable valve mechanism. The intake electric VVT 23 is configured to continuously change the rotational phase of the intake camshaft within a predetermined angle range. Thereby, the valve opening timing and the valve closing timing of the intake valve 21 can be continuously changed. The intake valve mechanism may have a hydraulic VVT instead of the electric VVT.

The cylinder head 13 is also formed with two exhaust ports 19 (FIG. 1) for each cylinder 11. The exhaust port 19 communicates with the combustion chamber 17. An exhaust valve 22 is provided at the exhaust port 19. The exhaust valve 22 opens and closes between the combustion chamber 17 and the exhaust port 19. The exhaust valve 22 is opened and closed at a predetermined timing by the exhaust valve mechanism. In the present embodiment, the exhaust valve mechanism has an exhaust electric VVT 24 (FIG. 3) which is a variable valve mechanism. The exhaust electric VVT 24 is configured to continuously change the rotational phase of the exhaust camshaft within a predetermined angle range. Thereby, the valve opening timing and the valve closing timing of the exhaust valve 22 can be continuously changed. The exhaust valve mechanism may have a hydraulic VVT instead of the electric VVT.

Although the details will be described later, in the present embodiment, the engine 1 adjusts the length of the overlap period related to the opening of the intake valve 21 and the opening of the exhaust valve 22 by the intake electric VVT23 and the exhaust electric VVT24. Can be done. As a result, the residual gas in the combustion chamber 17 is scavenged, and the hot burned gas is confined in the combustion chamber 17 (that is, the internal EGR (Exhaust Gas Recirculation) gas is introduced into the combustion chamber 17). be able to. In this configuration example, the intake electric VVT23 and the exhaust electric VVT24 constitute an internal EGR system as one of the state quantity setting devices. The internal EGR system is not always composed of VVT.

As shown in FIG. 2, an injector 6 is attached to the cylinder head 13 for each cylinder 11. The injector 6 is configured to inject fuel directly into the combustion chamber 17. The injector 6 is arranged at a valley portion of the pent roof where the inclined surface 13a on the intake side and the inclined surface 13b on the exhaust side intersect. Further, the injector 6 is arranged so that its injection axis is along the central axis X of the cylinder 11. The injection axis of the injector 6 and the position of the convex portion 31a of the cavity 31 substantially coincide with each other. The injector 6 faces the cavity 31. The injection axis of the injector 6 does not have to coincide with the central axis X of the cylinder 11. Even in that case, it is desirable that the injection axis of the injector 6 and the position of the convex portion 31a of the cavity 31 coincide with each other.

Although detailed illustration is omitted, the injector 6 is composed of a multi-injection type fuel injection valve having a plurality of injection ports. As shown by the arrow in FIG. 2, the injector 6 injects fuel so that the fuel spray spreads radially from the center of the combustion chamber 17.

As will be described later, the injector 6 may inject fuel at a timing when the piston 3 is located near the compression top dead center. In that case, when the injector 6 injects fuel, the fuel spray flows downward along the convex portion 31a of the cavity 31 while mixing with the fresh air, and also flows downward along the bottom surface and the peripheral side surface of the concave portion 31b. It spreads radially outward from the center of 17 and flows. After that, the air-fuel mixture reaches the opening of the cavity 31 and flows from the outer side in the radial direction toward the center of the combustion chamber 17 along the inclined surface 13a on the intake side and the inclined surface 13b on the exhaust side.
The injector 6 is not limited to the multi-injection type injector. As the injector 6, an externally open valve type injector may be adopted.

As shown in FIG. 1, a fuel supply system 61 is connected to the injector 6. The fuel supply system 61 includes a fuel tank 63 configured to store fuel, and a fuel supply path 62 that connects the fuel tank 63 and the injector 6 to each other. A fuel pump 65 and a common rail 64 are provided in the fuel supply path 62. The fuel pump 65 is configured to pump fuel to the common rail 64. In the present embodiment, the fuel pump 65 is a plunger type pump driven by the crankshaft 15. The common rail 64 is configured to store the fuel pumped from the fuel pump 65 at a high fuel pressure. When the injector 6 opens, the fuel stored in the common rail 64 is injected into the combustion chamber 17 from the injection port of the injector 6. The fuel supply system 61 is configured to be able to supply fuel having a high pressure of 30 MPa or more to the injector 6. The maximum fuel pressure of the fuel supply system 61 may be, for example, about 120 MPa. The pressure of the fuel supplied to the injector 6 may be changed according to the operating state of the engine 1. The configuration of the fuel supply system 61 is not limited to the above configuration.

A spark plug 25 is attached to the cylinder head 13 for each cylinder 11. The spark plug 25 forcibly ignites the air-fuel mixture in the combustion chamber 17. As shown in FIG. 2, in the present embodiment, the spark plug 25 is arranged on the intake side of the cylinder 11 with the central axis X in between. The spark plug 25 is located between the two intake ports 18. The spark plug 25 is attached to the cylinder head 13 so as to be inclined from the upper side to the lower side toward the center of the combustion chamber 17. The electrodes of the spark plug 25 face the combustion chamber 17 and are located near the ceiling surface of the combustion chamber 17.

As shown in FIG. 1, an intake passage 40 is connected to one side surface of the engine 1. The intake passage 40 communicates with the intake port 18 of each cylinder 11. The intake passage 40 is a passage through which the gas introduced into the combustion chamber 17 flows. An air cleaner 41 for filtering fresh air is disposed at the upstream end of the intake passage 40. A surge tank 42 is arranged near the downstream end of the intake passage 40. The intake passage 40 downstream of the surge tank 42 constitutes an independent passage that branches for each cylinder 11, although detailed illustration is omitted. The downstream end of the independent passage is connected to the intake port 18 of each cylinder 11.

A throttle valve 43 is provided between the air cleaner 41 and the surge tank 42 in the intake passage 40. The throttle valve 43 is configured to adjust the amount of fresh air introduced into the combustion chamber 17 by adjusting the opening degree of the valve.

In the intake passage 40, a supercharger 44 is also arranged downstream of the throttle valve 43. The supercharger 44 is configured to supercharge the gas to be introduced into the combustion chamber 17. In the present embodiment, the supercharger 44 is a mechanical supercharger driven by the engine 1. The mechanical turbocharger 44 may be, for example, a roots type. The configuration of the mechanical turbocharger 44 may be any configuration. The mechanical turbocharger 44 may be a Rishorum type or a centrifugal type.

An electromagnetic clutch 45 is interposed between the supercharger 44 and the output shaft of the engine 1. The electromagnetic clutch 45 transmits a driving force from the engine 1 to the supercharger 44 or cuts off the transmission of the driving force between the supercharger 44 and the engine 1. As will be described later, when the ECU 10 (FIG. 3) switches between the connected state and the non-connected state of the electromagnetic clutch 45, the supercharger 44 is switched on and off. That is, the engine 1 can switch between supercharging the gas introduced into the combustion chamber 17 by the supercharger 44 and not supercharging the gas introduced into the combustion chamber 17 by the supercharger 44. It is configured so that it can be done.

An intercooler 46 is arranged downstream of the supercharger 44 in the intake passage 40. The intercooler 46 is configured to cool the compressed gas in the turbocharger 44. The intercooler 46 may be configured to be water-cooled, for example.

A bypass passage 47 is connected to the intake passage 40. The bypass passage 47 connects the upstream portion of the supercharger 44 and the downstream portion of the intercooler 46 in the intake passage 40 to each other so as to bypass the supercharger 44 and the intercooler 46. An air bypass valve 48, which is a bypass control valve, is provided in the bypass passage 47. The air bypass valve 48 adjusts the flow rate of gas flowing through the bypass passage 47.

When the supercharger 44 is turned off (that is, when the electromagnetic clutch 45 is disengaged), the air bypass valve 48 is fully opened. As a result, the gas flowing through the intake passage 40 bypasses the supercharger 44 and is introduced into the combustion chamber 17 of the engine 1. The engine 1 operates in a non-supercharged state, that is, in a naturally aspirated state.
When the turbocharger 44 is turned on (that is, when the electromagnetic clutch 45 is connected), a part of the gas that has passed through the turbocharger 44 flows back to the upstream of the turbocharger through the bypass passage 47. .. Since the reverse flow rate can be adjusted by adjusting the opening degree of the air bypass valve 48, the boost pressure of the gas introduced into the combustion chamber 17 can be adjusted. In this configuration example, the supercharging system 49 is configured by the supercharger 44, the bypass passage 47, and the air bypass valve 48.

An exhaust passage 50 is connected to the other side surface of the engine 1. The exhaust passage 50 communicates with the exhaust port 19 of each cylinder 11. The exhaust passage 50 is a passage through which the exhaust gas discharged from the combustion chamber 17 flows. Although detailed illustration is omitted, the upstream portion of the exhaust passage 50 constitutes an independent passage that branches for each cylinder 11. The upstream end of the independent passage is connected to the exhaust port 19 of each cylinder 11. An exhaust gas purification system having one or more catalytic converters 51 is arranged in the exhaust passage 50. The catalyst converter 51 is configured to include a three-way catalyst. The exhaust gas purification system is not limited to the one containing only the three-way catalyst.

An EGR passage 52 constituting an external EGR system is connected between the intake passage 40 and the exhaust passage 50. The EGR passage 52 is a passage for returning a part of the burnt gas to the intake passage 40. The upstream end of the EGR passage 52 is connected to the downstream of the catalytic converter 51 in the exhaust passage 50. The downstream end of the EGR passage 52 is connected to the upstream of the turbocharger 44 in the intake passage 40.

A water-cooled EGR cooler 53 is provided in the EGR passage 52. The EGR cooler 53 is configured to cool the burnt gas. An EGR valve 54 is also provided in the EGR passage 52. The EGR valve 54 is configured to regulate the flow rate of the burnt gas flowing through the EGR passage 52. By adjusting the opening degree of the EGR valve 54, the recirculation amount of the cooled burnt gas, that is, the external EGR gas can be adjusted.

In the present embodiment, the EGR system 55 is composed of an external EGR system including an EGR passage 52 and an EGR valve 54, and an internal EGR system including the above-mentioned intake electric VVT23 and exhaust electric VVT24. It is configured. The EGR valve 54 also constitutes one of the state quantity setting devices.

As shown in FIG. 3, the engine 1 is provided with an ECU (Engine Control Unit) 10 for operating the engine 1, and the ECU 10 is one of the failure diagnosis devices for the turbocharger according to the first embodiment of the present invention. The control unit 10a constituting the unit is built in. The ECU 10 is a controller based on a well-known microcomputer, and is composed of a central processing unit (CPU) for executing a program, and for example, a RAM (Random Access Memory) or a ROM (Read Only Memory). It is equipped with a memory for storing programs and data, and an input / output bus for inputting / outputting electrical signals. The ECU 10 is an example of a controller.

As shown in FIGS. 1 and 3, various sensors SW1 to SW16 are connected to the ECU 10. The sensors SW1 to SW16 output a detection signal to the ECU 10. The sensors include the following sensors.

That is, the air flow sensor SW1 which is arranged downstream of the air cleaner 41 in the intake passage 40 and detects the flow rate of fresh air flowing through the intake passage 40, the first intake air temperature sensor SW2 which detects the temperature of the fresh air, and the intake passage. Supercharging in the intake passage 40, the first pressure sensor SW3, which is located downstream of the connection position of the EGR passage 52 in 40 and upstream of the supercharger 44 and detects the pressure of the gas flowing into the supercharger 44. It is located downstream of the machine 44 and upstream of the connection position of the bypass passage 47, and is attached to and excessively attached to the second intake air temperature sensor SW4 and the surge tank 42 that detect the temperature of the gas flowing out from the supercharger 44. The second pressure sensor SW5 that detects the pressure of the gas downstream of the turbocharger 44, and the finger pressure sensor SW6 that is attached to the cylinder head 13 corresponding to each cylinder 11 and detects the pressure (in-cylinder pressure) in each combustion chamber 17. , The exhaust temperature sensor SW7 which is arranged in the exhaust passage 50 and detects the temperature of the exhaust gas discharged from the combustion chamber 17, and the supercharger rotation which is attached to the supercharger 44 and detects the rotation speed of the supercharger 44. The number sensor SW8, the engine rotation speed sensor SW9 which is arranged near the output shaft of the engine 1 and detects the rotation speed of the output shaft, the water temperature sensor SW10 which is attached to the engine 1 and detects the temperature of the cooling water, and the engine 1 It is attached to the crank angle sensor SW11 that detects the rotation angle of the crank shaft 15, the accelerator opening sensor SW12 that is attached to the accelerator pedal mechanism and detects the accelerator opening corresponding to the amount of operation of the accelerator pedal, and the engine 1. Intake cam angle sensor SW13 that detects the rotation angle of the intake cam shaft, exhaust cam angle sensor SW14 that is attached to the engine 1 and detects the rotation angle of the exhaust cam shaft, and is arranged in the EGR passage 52 and is an EGR valve. The EGR differential pressure sensor SW15 that detects the differential pressure upstream and downstream of the 54, and the fuel pressure sensor SW16 that is attached to the common rail 64 of the fuel supply system 61 and detects the pressure of the fuel supplied to the injector 6.

Based on these detection signals, the ECU 10 determines the operating state of the engine 1 and calculates the control amount of each device. The ECU 10 transmits a control signal related to the calculated control amount to the injector 6, the spark plug 25, the intake electric VVT23, the exhaust electric VVT24, the fuel supply system 61, the throttle valve 43, the EGR valve 54, and the electromagnetic clutch 45 of the supercharger 44. , And output to the air bypass valve 48. For example, the ECU 10 adjusts the opening degree of the air bypass valve 48 based on the front-rear differential pressure of the supercharger 44 obtained from the detection signals of the first pressure sensor SW3 and the second pressure sensor SW5 to adjust the boost pressure. adjust. Further, the ECU 10 adjusts the opening degree of the EGR valve 54 based on the front-rear differential pressure of the EGR valve 54 obtained from the detection signal of the EGR differential pressure sensor SW15, thereby introducing an external EGR gas amount into the combustion chamber 17. To adjust.

Further, the control unit 10a built in the ECU 10 is an air bypass valve provided in the electromagnetic clutch 45 and the bypass passage 47 based on the signals detected by the turbocharger rotation speed sensor SW8 and the engine rotation speed sensor SW9. The 48 is controlled to diagnose the failure of the mechanical turbocharger 44. Therefore, the electromagnetic clutch 45, the bypass passage 47, the air bypass valve 48, the supercharger rotation speed sensor SW8, the engine rotation speed sensor SW9, and the control unit 10a constitute a failure diagnosis device for the supercharger.

Next, the operating region of the engine will be described with reference to FIG.
FIG. 4 illustrates the operating region of the engine 1. The operating region of the engine 1 is determined by the load and the rotation speed, and is roughly divided into four regions according to the high and low load and the high and low rotation speed. Specifically, the four regions include the low load region (A) including idle operation and extend to the low rotation and medium rotation regions, and the load is higher than the low load region and extend to the low rotation and medium rotation regions. A high load region (C) and a low load region (A), which are regions where the load is higher than the medium load region (B) and the medium load region (B) and include a fully open load extending to the low rotation and medium rotation regions. , The medium load region (B), and the high rotation region (D) having a higher rotation speed than the high load region (C).

Here, in the low rotation region, the medium rotation region, and the high rotation region, when the entire operation region of the engine 1 is divided into substantially three equal parts of the low rotation region, the medium rotation region, and the high rotation region in the rotation speed direction, respectively. It may be a low rotation region, a medium rotation region, and a high rotation region. In the example of FIG. 4, a rotation speed of less than N1 is defined as a low rotation speed, a rotation speed of N2 or more is defined as a high rotation speed, and a rotation speed of N1 or more and less than N2 is defined as a medium rotation speed. The rotation speed N1 may be, for example, 1200 rpm, and the rotation speed N2 may be, for example, 4000 rpm. Further, the high load region (C) may be a region where the combustion pressure is 900 kPa or more.

The engine 1 performs combustion by compression self-ignition in a low load region (A), a medium load region (B), and a high load region (C) for the main purpose of improving fuel efficiency and exhaust gas performance. The engine 1 also burns by spark ignition in the high speed region (D). Hereinafter, the operation of the engine 1 in each region of the low load region (A), the medium load region (B), the high load region (C), and the high rotation region (D) will be described.

When the engine 1 is operating in the low load region (A), the fuel injection amount is small and the temperature inside the combustion chamber 17 is also low. Therefore, CI combustion (compressive self-ignition combustion) that self-ignites when a predetermined pressure and temperature are reached cannot be stably performed. Since the amount of fuel is small, ignition by ignition is difficult and SI combustion (spark ignition combustion) becomes unstable. The air-fuel ratio (A / F) of the entire inside of the combustion chamber 17 in the low load operation region of the engine 1 is, for example, 30 or more and 40 or less.

Here, around the stoichiometric air-fuel ratio (A / F = 14.7), the combustion temperature is high, so that a large amount of NOx is generated. The fuel concentration is high and the air is insufficient for the fuel, such that the A / F is less than 10, or the fuel concentration is low and the air is too low for the fuel, such that the A / F is more than 30. The generation of NOx is suppressed by the excessive air condition.

Therefore, at present, when the engine is operating in a low load region, a rich air-fuel mixture like the former is formed around the spark plug to serve as a fire source, and a lean mixture like the latter is formed around the air-fuel mixture. Stratified lean combustion that forms qi and compresses and ignites is performed. However, in such stratified lean combustion, an air-fuel mixture having an A / F of 10 to 25, which generates a large amount of NOx, is inevitably generated between the rich air-fuel mixture and the lean air-fuel mixture. Therefore, NOx cannot be suppressed.

Further, in a lean air-fuel mixture having an A / F of more than 30, even if it can be ignited by spark ignition, the flame propagation is slow and combustion does not proceed, so stable SI combustion cannot be performed. On the other hand, when the A / F is around 25 (20 to 35), stable SI combustion can be performed and the generation of NOx can be suppressed. Therefore, the engine 1 performs SPCCI combustion (partial compression ignition combustion) that combines SI combustion and CI combustion in the low load region (A). Then, by applying the air-fuel mixture distribution control technology using the swirl flow, stable SPCCI combustion can be performed in the low load operation region of the engine 1, and low NOx and low fuel consumption combustion can be realized.

Specifically, a small amount of fuel in which a lean air-fuel mixture having an A / F of more than 30 is formed in the entire inside of the combustion chamber 17 is injected into the inside of the combustion chamber 17, and combustion in which an ignition plug is arranged is performed. It is located in the central part of the chamber 17 and is located in the region that becomes the fire type (for example, A / F is 20 or more and 35 or less) and in the peripheral part of the combustion chamber 17, and is compressed and ignited by the combustion pressure and combustion heat of the combustion type. A stratified air-fuel mixture distribution having a region (for example, A / F of 35 or more and 50 or less) is formed inside the combustion chamber 17 at the timing of ignition.

In SPCCI combustion, the ignition plug 25 forcibly ignites the air-fuel mixture in the combustion chamber 17, so that the air-fuel mixture undergoes SI combustion by flame propagation, and the heat generated by SI combustion causes SI combustion in the combustion chamber 17. As the temperature rises and the pressure in the combustion chamber 17 rises due to flame propagation, the unburned air-fuel mixture undergoes CI combustion by self-ignition.

By adjusting the calorific value of SI combustion, it is possible to absorb the variation in temperature in the combustion chamber 17 before the start of compression. Even if the temperature in the combustion chamber 17 before the start of compression varies, the timing of self-ignition can be controlled by adjusting the start timing of SI combustion, for example, by adjusting the ignition timing. When SPCCI combustion is performed, the spark plug 25 ignites the air-fuel mixture near the compression top dead center, more precisely, at a predetermined timing before the compression top dead center, whereby combustion by flame propagation starts.

In order to improve the fuel efficiency of the engine 1, the EGR system 55 introduces the EGR gas into the combustion chamber 17 when the engine 1 is operating in the low load region (A). When the engine 1 operates in the low load region (A), the ECU 10 controls the injector 6 to inject fuel at a pressure in the range of 30 MPa to 120 MPa, as described above. Further, when the engine 1 is operated in the low load region (A), the air-fuel ratio (A / F) of the air-fuel mixture is leaner than the theoretical air-fuel ratio in the entire combustion chamber 17. That is, the excess air ratio λ of the air-fuel mixture exceeds 1 in the entire combustion chamber 17. More specifically, the A / F of the air-fuel mixture in the entire combustion chamber 17 is 30 or more and 40 or less. By doing so, the generation of RawNOx can be suppressed, and the exhaust gas performance can be improved. In the low load region (A), the engine 1 leans the air-fuel mixture from the stoichiometric air-fuel ratio to perform SPCCI combustion. Therefore, the low load region (A) can be referred to as a "SPCCI lean region".

Next, even when the engine 1 is operating in the medium load region (B), the engine 1 performs SPCCI combustion as in the low load region (A).
The EGR system 55 introduces the EGR gas into the combustion chamber 17 when the operating state of the engine 1 is in the medium load region (B). Further, when the engine 1 is operated in the medium load region (B), the air-fuel ratio (A / F) of the air-fuel mixture is the theoretical air-fuel ratio (A / F = 14.7) in the entire combustion chamber 17. The three-way catalyst purifies the exhaust gas discharged from the combustion chamber 17, so that the exhaust gas performance of the engine 1 is improved. The A / F of the air-fuel mixture may be contained in the purification window of the three-way catalyst. Therefore, the excess air ratio λ of the air-fuel mixture may be 1.0 ± 0.2.

When the engine 1 operates in the medium load region (B), the injector 6 injects fuel into the combustion chamber 17 in two steps, a front stage injection and a rear stage injection. The first-stage injection injects fuel at a timing away from the ignition timing, and the second-stage injection injects fuel at a timing close to the ignition timing. The first-stage injection may be performed, for example, in the first half of the compression stroke, and the second-stage injection may be performed, for example, in the second half of the compression stroke. The first half and the second half of the compression stroke may be the first half and the second half when the compression stroke is bisected with respect to the crank angle, respectively.

The injector 6 injects fuel radially outward from the central portion of the combustion chamber 17 from a plurality of inclined injection holes. When the injector 6 performs the pre-stage injection within the first half of the compression stroke, the piston 3 is separated from the top dead center, so that the injected fuel spray is the upper surface of the piston 3 rising toward the top dead center. Reach the outside of the cavity 31. When the injector 6 performs post-stage injection in the latter half of the compression stroke, the injected fuel spray enters the cavity 31 because the piston 3 is close to top dead center. The fuel injected by the post-stage injection forms an air-fuel mixture in the region inside the cavity 31.

As the fuel is injected into the cavity 31 by the subsequent injection, gas flow is generated in the region inside the cavity 31. If the time until the ignition timing is long, the turbulent energy in the combustion chamber 17 is attenuated as the compression stroke progresses. However, since the injection timing of the post-stage injection is closer to the ignition timing than that of the pre-stage injection, the spark plug 25 ignites the air-fuel mixture in the region inside the cavity 31 while the turbulent energy in the cavity 31 remains high. be able to. As a result, the combustion rate of SI combustion increases. As the combustion rate of SI combustion increases, as described above, the controllability of CI combustion by SI combustion increases.

When the injector 6 performs the pre-stage injection and the post-stage injection, a substantially homogeneous air-fuel mixture having an excess air ratio λ of 1.0 ± 0.2 is formed in the combustion chamber 17 as a whole. To. Since the air-fuel mixture is substantially homogeneous, it is possible to improve fuel efficiency by reducing unburned loss and improve exhaust gas performance by avoiding the generation of smoke. The excess air ratio λ is preferably 1.0 to 1.2.

When the spark plug 25 ignites the air-fuel mixture at a predetermined timing before the compression top dead center, the air-fuel mixture is burned by flame propagation. After the start of combustion by flame propagation, the unburned air-fuel mixture self-ignites and CI burns. The fuel injected by the subsequent injection mainly burns SI. The fuel injected by the pre-stage injection mainly burns CI. When the pre-stage injection is performed during the compression stroke, it is possible to prevent the fuel injected by the pre-stage injection from inducing abnormal combustion such as premature ignition. In addition, the fuel injected by the post-stage injection can be stably burned by flame propagation. Since the engine 1 performs SPCCI combustion with the air-fuel ratio as the stoichiometric air-fuel ratio in the medium load region (B), the medium load region (B) can be referred to as “SPCCIλ = 1 region”.

Here, as shown in FIG. 4, the supercharger 44 is turned off in a part of the low load region (A) and a part of the medium load region (B) (S / C in FIG. 4). See OFF). Specifically, the supercharger 44 is turned off in the low rotation side region in the low load region (A). In the region on the high rotation speed side in the low load region (A), the supercharger 44 is turned on in order to secure the required intake air filling amount in response to the increase in the rotation speed of the engine 1. Increase the supply pressure. Further, the supercharger 44 is turned off in the low load low rotation side region in the medium load region (B), and the fuel injection amount increases in the high load side region in the medium load region (B). In order to secure the required intake charge amount correspondingly, the supercharger 44 is turned on, and in the region on the high rotation side, the required intake charge amount is increased in response to the increase in the rotation speed of the engine 1. To secure, the supercharger 44 is turned on. In the high load region (C) and the high rotation region (D), the turbocharger 44 is turned on over the entire area (see S / C ON in FIG. 4).

Even in the high load region (C), the engine 1 performs SPCCI combustion in the same manner as in the low load region (A) and the medium load region (B). The EGR system 55 introduces the EGR gas into the combustion chamber 17 when the operating state of the engine 1 is in the high load region (C). The engine 1 reduces the amount of EGR gas as the load increases. At full open load, the EGR gas may be zero.

When the engine 1 operates in the high load region (C), the air-fuel ratio (A / F) of the air-fuel mixture is richer than the stoichiometric air-fuel ratio or the stoichiometric air-fuel ratio in the entire combustion chamber 17 (that is, the air-fuel ratio). The air-fuel ratio λ of is λ ≦ 1). In the high load region (C) of the engine 1, the injector 6 injects fuel into the combustion chamber 17 in two steps, a pre-stage injection and a post-stage injection, in the compression stroke. The first-stage injection may be performed in the first half of the compression stroke, and the second-stage injection may be performed in the second half of the compression stroke.

When a strong swirl flow is generated in the combustion chamber 17, the fuel of the pre-stage injection forms an air-fuel mixture in the central portion of the combustion chamber 17. The air-fuel mixture in the central part is burned mainly by SI combustion. The fuel for the latter stage injection mainly forms an air-fuel mixture in the outer peripheral portion of the combustion chamber 17. The air-fuel mixture on the outer periphery is mainly burned by CI combustion.

Then, in the fuel injection in which the first stage injection and the second stage injection are performed, the fuel concentration of the air-fuel mixture in the outer peripheral portion of the combustion chamber is higher than the fuel concentration of the air-fuel mixture in the central portion, and the fuel amount of the air-fuel mixture in the outer peripheral portion is increased. Make sure it is greater than the amount of fuel in the air-fuel mixture in the center. The injection amount of the first stage injection may be larger than the injection amount of the second stage injection. The ratio of the injection amount of the first stage injection to the injection amount of the second stage injection may be 7: 3 as an example.

In the high rotation speed region (D), the rotation speed of the engine 1 is high, and the time required for the crank angle to change by 1 ° is short. Therefore, for example, in the high rotation region in the high load region, it becomes difficult to stratify the air-fuel mixture in the combustion chamber 17 by performing the split injection during the compression stroke as described above. When the number of revolutions of the engine 1 becomes high, it becomes difficult to perform the above-mentioned SPCCI combustion. Therefore, when the engine 1 is operating in the high rotation speed region (D), the engine 1 performs SI combustion instead of SPCCI combustion. The high rotation region (D) extends in the load direction from a low load to a high load.

The EGR system 55 introduces the EGR gas into the combustion chamber 17 when the operating state of the engine 1 is in the high rotation speed region (D). The engine 1 reduces the amount of EGR gas as the load increases. At full open load, the EGR gas may be zero. When the engine 1 operates in the high speed region (D), the air-fuel ratio (A / F) of the air-fuel mixture is basically the stoichiometric air-fuel ratio (A / F = 14.7) in the entire combustion chamber 17. Is. The excess air ratio λ of the air-fuel mixture may be 1.0 ± 0.2. In the high load region including the fully open load in the high rotation region (D), the excess air ratio λ of the air-fuel mixture may be less than 1.

When the engine 1 operates in the high speed region (D), the injector 6 starts fuel injection in the intake stroke. The injector 6 injects fuel all at once. In addition, the fuel injection period changes according to the fuel injection amount. By initiating fuel injection during the intake stroke, it becomes possible to form a homogeneous or substantially homogeneous air-fuel mixture in the combustion chamber 17. Further, when the rotation speed of the engine 1 is high, the vaporization time of the fuel can be secured as long as possible, so that the unburned loss can be reduced. The spark plug 25 ignites the air-fuel mixture at an appropriate timing after the fuel injection is completed and before the compression top dead center. Therefore, in the high speed region (D), the engine 1 starts fuel injection in the intake stroke to perform SI combustion, so that the high speed region (4) can be called an "intake-SI region".

Next, with reference to FIG. 5, the operation of the failure diagnosis device of the supercharger according to the first embodiment of the present invention will be described.
FIG. 5 is a flowchart showing the operation of the failure diagnosis device for the turbocharger according to the first embodiment of the present invention. The process according to the flowchart shown in FIG. 5 is repeatedly executed at predetermined time intervals while the engine 1 is operating.

First, in step S1 of FIG. 5, detection signals from each sensor are input to the ECU 10 and the control unit 10a built therein. The detection signals include at least a signal representing the rotation speed of the engine 1 detected by the engine rotation speed sensor SW9, a signal representing the load of the engine 1 detected by the accelerator opening sensor SW12, and a supercharger rotation speed sensor SW8. Contains a signal representing the number of revolutions of the supercharger detected by.

Next, in step S2, it is determined whether or not the operating conditions of the turbocharger (S / C) 44 are satisfied. That is, which region (S / C OFF region or S / C ON region) of FIG. 4 the operating state belongs to based on each signal representing the rotation speed and load of the engine 1 input in step S1. Judged. If the operating state belongs to the S / C ON area, the process proceeds to step S3, and if the operating state belongs to the S / C OFF area, the process proceeds to step S7.

In step S3, the control unit 10a of the ECU 10 sends a control signal to the electromagnetic clutch 45 to switch it to the connected state, and also sends a control signal to the air bypass valve 48 to switch it to the closed side. As a result, the supercharger 44 is driven by the output shaft of the engine 1, and the intake air that has passed through the throttle valve 43 is pressurized by the supercharger 44 and sent to the cylinder 11. In the present embodiment, even when the air bypass valve 48 is switched to the closed side, the bypass passage 47 is not completely blocked, and the bypass passage 47 has a very large flow path resistance. Become.

Next, in step S4, the rotation speed of the supercharger 44 detected by the supercharger rotation speed sensor SW8 (the rotation speed detected after the electromagnetic clutch 45 is connected in step S3) is less than the predetermined rotation speed. Whether or not there is is judged. That is, it is determined whether or not the rotation speed of the supercharger 44 is lower than the rotation speed assumed when the electromagnetic clutch 45 is in the connected state. If the rotation speed of the supercharger 44 is less than the predetermined rotation speed, the process proceeds to step S5, and if the rotation speed is equal to or higher than the predetermined rotation speed, the process proceeds to step S6.

In step S5, the temporary failure flag of the turbocharger 44 is set to "1" (or maintained at "1"), and one process of the flowchart shown in FIG. 5 is completed. That is, when the rotation speed of the supercharger 44 detected by the supercharger rotation speed sensor SW8 is low even though the electromagnetic clutch 45 is connected, the supercharger 44 is stuck and does not rotate. The temporary failure flag is set because it may be. However, even if the supercharger 44 is normal, if the supercharger rotation speed sensor SW8 is out of order, the rotation speed of the supercharger 44 may be detected as low. Therefore, at the stage when step S5 is executed, the failure diagnosis device of the supercharger does not determine that "the supercharger 44 is out of order".

On the other hand, when the rotation speed of the supercharger 44 is equal to or higher than the predetermined rotation speed, the process proceeds to step S6, and the temporary failure flag of the supercharger 44 is set to "0" (or maintained at "0"). One process of the flowchart is completed. That is, when the electromagnetic clutch 45 is in the connected state and the rotation speed of the supercharger 44 is high, it is considered that the supercharger 44 is rotating normally, so that a temporary failure flag is set. There is no.

On the other hand, if it is determined in step S2 that the operating conditions of the turbocharger 44 are not satisfied, the process proceeds to step S7. In step S7, the electromagnetic clutch 45 is disconnected. That is, when the operating condition of the supercharger 44 is not satisfied, the supercharger 44 is not driven because the supercharger is not performed.

Next, in step S8, it is determined whether or not the temporary failure flag of the turbocharger 44 is set, and if the flag is set, the process proceeds to step S9, and if the flag is not set, the step is performed. Proceed to S14.

In step S14, the air bypass valve 48 is switched to the open side (or is maintained on the open side), and one process of the flowchart shown in FIG. 5 is completed. In this state, the air that has passed through the throttle valve 43 is mainly sucked into the cylinder 11 through the bypass passage 47 having a small flow path resistance. As a result, the engine 1 is normally operated with naturally aspirated engine (non-supercharged state).

On the other hand, in step S8, if the temporary failure flag of the turbocharger 44 is set, the process proceeds to step S9, and in step S9, it is determined whether or not the engine 1 is in the idling state. If the engine 1 is not in the idling state, the process proceeds to step S14, where the air bypass valve 48 is switched to the open side (or is maintained on the open side), and one process of the flowchart shown in FIG. 5 is completed. That is, even if the temporary failure flag is set, the engine 1 is operated by naturally aspirated engine if it is not in the idling state.

On the other hand, if it is determined in step S9 that the engine 1 is in the idling state, the process proceeds to step S10, and in step S10, the air bypass valve 48 is switched to the closed side. That is, when the non-supercharging operation is performed and the idling state is set in the state where the temporary failure flag of the supercharger 44 is set, the control unit 10a does not connect the electromagnetic clutch 45 and the air bypass valve. A "idling state" with 48 as the closing side is set. In this "idling state", since the air bypass valve 48 is closed, the gas is mainly drawn into the cylinder 11 through the supercharger 44 to which the electromagnetic clutch 45 is disconnected. Become. That is, when the air bypass valve 48 is closed, the gas mainly passes through the supercharger 44 into the cylinder 11 instead of the bypass passage 47 having a large flow path resistance even in the non-supercharged state. Be drawn in.

Next, in step S11, it is determined whether or not the engine speed is less than the predetermined speed, and if it is less than the predetermined speed, the process proceeds to step S12, and if it is more than the predetermined speed, step S13 is performed. move on.

In step S12, the control unit 10a determines that the supercharger 44 has a sticking failure, resets the temporary failure flag to the state of "0", and ends one process of the flowchart shown in FIG. To do. Further, the control unit 10a lights a warning light (not shown) indicating a failure of the turbocharger 44. That is, when the supercharger 44 is stuck, the flow path resistance of the supercharger 44 in the "idle state" becomes large, so that the amount of intake air sucked into the cylinder 11 is greatly reduced, and the engine The number of revolutions of 1 is greatly reduced. Therefore, when the rotation speed of the engine 1 drops below the predetermined rotation speed in the "idle state", it can be determined that the supercharger 44 is stuck.

If it is determined in step S9 that the vehicle is not in the idling state, the setting of the "idling state" (step S10) is not executed as described above. This is because if the "idling state" is set in the state where the load is applied to the engine 1 and the output of the engine 1 decreases, the rotation speed of the engine 1 greatly decreases, which may give the driver a sense of discomfort. is there. In the present embodiment, since the "idling state" is set in the idling state in which the engine 1 is not loaded, the decrease in the number of revolutions is small even when the engine output is reduced, and the discomfort given to the driver is suppressed. Can be done. Further, in the present embodiment, when the "idling state" is set, the sticking failure of the supercharger 44 is determined based on whether or not the rotation speed of the engine 1 has decreased to less than the predetermined rotation speed. As an example, the present invention can be configured to determine a sticking failure based on the amount of decrease in engine speed.

On the other hand, if it is determined in step S11 that the engine speed is equal to or higher than the predetermined speed, the process proceeds to step S13. In step S13, the control unit 10a determines that the turbocharger rotation speed sensor SW8 has failed, resets the temporary failure flag to the state of "0", and performs one process of the flowchart shown in FIG. To finish. Further, the control unit 10a lights a warning light (not shown) indicating a failure of the turbocharger rotation speed sensor SW8. That is, when the supercharger 44 is not fixed, the flow path resistance of the supercharger 44 in the "idle state" is relatively small. Therefore, the amount of intake air sucked into the cylinder 11 through the supercharger 44 does not decrease so much, and the rotation speed of the engine 1 does not decrease significantly. That is, when the rotation speed of the engine 1 is equal to or higher than the predetermined rotation speed in the "idle state", the supercharger 44 is operated by the supercharger rotation speed sensor SW8 even though the supercharger 44 is not fixed. A decrease in the number of revolutions was detected (step S4), and a temporary failure flag was set (step S5). Therefore, when the rotation speed of the engine 1 is equal to or higher than the predetermined rotation speed in the "idle state", it can be determined that the supercharger rotation speed sensor SW8 is out of order.

In the present embodiment, in the state where the temporary failure flag is set (temporary failure flag = 1), the "idling state" is set when it is determined that the "idling state" is set (step). S9 → S10). On the other hand, as a modification, the present invention is configured so that the "idling state" is set when it is determined that "the vehicle is stopped" in the state where the temporary failure flag is set. You can also. In this way, if the vehicle is stopped, the mechanical turbocharger is stuck, and even if the engine stops due to the setting of "idle state", it gives the driver a strong sense of discomfort. Can be reliably avoided.

According to the failure diagnosis device of the turbocharger according to the first embodiment of the present invention, when a decrease in the engine speed is detected by the engine speed sensor SW9 in the idling state (step S10 in FIG. 5) (step). From S11 to S12), the control unit 10a determines that the mechanical turbocharger 44 is out of order. Therefore, it is possible to prevent the failure of the turbocharger rotation speed sensor SW8 from being erroneously determined as the failure of the mechanical supercharger 44. As a result, the failure of the mechanical turbocharger 44 can be accurately diagnosed.

Further, according to the failure diagnosis device of the turbocharger of the present embodiment, when the engine rotation speed sensor SW9 does not detect a decrease in the rotation speed of the engine 1 in the idling state (steps S11 → S13), the supercharger It is determined that the rotation speed sensor is out of order. As a result, it is possible to diagnose the failure of the supercharger rotation speed sensor SW8 as well as the mechanical supercharger 44.

Further, according to the failure diagnosis device of the supercharger of the present embodiment, when the engine is in the idling state, the idling state is set (steps S9 → S10 in FIG. 5), and the failure of the mechanical supercharger 44 is determined. Therefore, even when the mechanical supercharger 44 is stuck, the engine 1 is unlikely to stop, and it is possible to suppress giving a sense of discomfort to the driver.

Next, with reference to FIG. 6, the failure diagnosis device of the supercharger according to the second embodiment of the present invention will be described.
The supercharger failure diagnosis device of the present embodiment is different from the above-described first embodiment in that the algorithm for diagnosing the failure of the supercharger executed by the control unit 10a built in the ECU 10 is different. Therefore, here, only the part of the second embodiment of the present invention that is different from the first embodiment will be described, and the description of the same configuration, action, and effect will be omitted. FIG. 6 is a flowchart showing the operation of the failure diagnosis device for the turbocharger according to the second embodiment of the present invention.

First, since steps S21 to S28 of the flowchart shown in FIG. 6 are the same as steps S1 to S8 of the flowchart of FIG. 5, description thereof will be omitted. In the present embodiment, if it is determined in step S28 that the temporary failure flag is not set (temporary failure flag = 0), the process proceeds to step S35, where the air bypass valve 48 is switched (or opened) to the open side. (Maintained on the side), and one process of the flowchart shown in FIG. 6 is completed.

On the other hand, in step S28, if it is determined that the temporary failure flag is set (temporary failure flag = 1), the process proceeds to step S29, and in step S29, it is determined whether or not the ECU 10 is in the diagnostic mode. To. That is, it is determined whether or not the vehicle equipped with the engine 1 is brought to a dealer or the like and a failure diagnosis is performed. For example, the ECU 10 can be set to the diagnostic mode by connecting a vehicle maintenance plug (not shown) to the ECU 10. If the ECU 10 is set to the diagnostic mode, the process proceeds to step S30, and if the ECU 10 is not set to the diagnostic mode, the process proceeds to step S35 to end one process of the flowchart shown in FIG.

On the other hand, in step S30, it is determined whether or not the engine 1 is in the idling state. If the engine 1 is not in the idling state, the process proceeds to step S35, where the air bypass valve 48 is switched to the open side (or is maintained on the open side), and one process of the flowchart shown in FIG. 6 is completed. That is, even if the temporary failure flag is set and the diagnostic mode is set, the engine 1 is operated by naturally aspirated engine if it is not in the idling state.

If the engine is idling, the process proceeds to step S31, and in step S31, the air bypass valve 48 is gradually switched to the closed side. As a result, the flow path resistance of the bypass passage 47 gradually increases, and the intake air drawn into the cylinder 11 mainly passes through the supercharger 44 to which the electromagnetic clutch 45 is not connected. When the air bypass valve 48 is switched in this way, when the supercharger 44 is stuck, the flow path resistance of the supercharger 44 in the idling state increases, and the amount of intake air drawn into the cylinder 11 decreases. Then, the rotation speed of the engine 1 decreases. Further, in the present embodiment, since the idling state is set in the state set in the diagnostic mode, the air bypass valve 48 is gradually closed, and it is determined whether or not the rotation speed of the engine 1 is reduced over time. be able to.

Next, in step S32, it is determined whether or not the engine speed is less than the predetermined speed, and if it is less than the predetermined speed, the process proceeds to step S33, and if it is more than the predetermined speed, step S34 is performed. move on. In step S33, it is determined that the supercharger 44 has a sticking failure, and the temporary failure flag is reset to the "0" state to end one process of the flowchart shown in FIG. On the other hand, in step S34, it is determined that the supercharger rotation speed sensor SW8 has failed, the temporary failure flag is reset to the state of "0", and one process of the flowchart shown in FIG. 6 is completed. To do. These processes in steps S32 to S34 are the same as the processes in steps S11 to S13 of the first embodiment shown in FIG.

According to the failure diagnosis device for the turbocharger according to the second embodiment of the present invention, the supercharger 44 is set in the state where the vehicle is brought to a dealer or the like and the ECU 10 is in the diagnosis mode. Alternatively, when a failure of the turbocharger rotation speed sensor SW8 is determined, prompt measures can be taken.

In the first embodiment, when a failure of the turbocharger 44 or the turbocharger rotation speed sensor SW8 is diagnosed, a warning light (not shown) provided in the vehicle is turned on. On the other hand, in the present embodiment, the present invention may be configured so that a warning is displayed on a vehicle warning light (not shown) and / or a vehicle maintenance plug (not shown).

Although the preferred embodiment of the present invention has been described above, various modifications can be made to the above-described embodiment. In particular, in the above-described embodiment, the present invention has been applied to an engine that performs SPCCI combustion under predetermined operating conditions, but the supercharger failure diagnosis device according to the present invention includes a mechanical supercharger. It can be applied to any type of engine.

1 engine 3 piston 6 injector 10 ECU
10a Control unit 11 Cylinder 12 Cylinder block 13 Cylinder head 13a Inclined surface 13b Inclined surface 14 Connecting rod 15 Crankshaft 17 Combustion chamber 18 Intake port 19 Exhaust port 21 Intake valve 22 Exhaust valve 23 Intake electric VVT
24 Exhaust electric VVT
25 Spark plug 31 Cavity 31a Convex 31b Concave 40 Intake passage 41 Air cleaner 42 Surge tank 43 Throttle valve 44 Supercharger (mechanical supercharger)
45 Electromagnetic clutch 46 Intercooler 47 Bypass passage 48 Air bypass valve (bypass control valve)
49 Supercharging system 50 Exhaust passage 51 Catalytic converter 52 EGR passage 53 EGR cooler 54 EGR valve 55 EGR system 61 Fuel supply system 62 Fuel supply path 63 Fuel tank 64 Common rail 65 Fuel pump SW8 Supercharger rotation speed sensor SW9 Engine rotation speed sensor SW12 Accelerator opening sensor

Claims (4)

It is a supercharger failure diagnosis device for diagnosing the failure of the mechanical supercharger provided in the intake passage of the engine.
An electromagnetic clutch that can switch between connecting and disconnecting the output shaft of the engine and the mechanical turbocharger,
A bypass passage connected to the intake passage so as to bypass the mechanical supercharger and supply intake air into the cylinder of the engine.
A bypass control valve provided in this bypass passage to open and close the bypass passage,
The turbocharger rotation speed sensor for detecting the rotation speed of the above mechanical supercharger, and
An engine speed sensor for detecting the speed of the output shaft of the engine and
A control unit that controls the electromagnetic clutch and the bypass control valve,
Have,
The above control unit
When the preset supercharging condition is satisfied, the electromagnetic clutch is switched to the connected state, the bypass control valve is closed, and the engine is supercharged.
When the preset supercharging condition is not satisfied, the electromagnetic clutch is switched to the non-connected state, the bypass control valve is opened, and the engine is put into the non-supercharging state.
Further, the control unit is
In the supercharged state of the engine, when the rotation speed of the mechanical supercharger detected by the supercharger rotation speed sensor is equal to or less than the predetermined rotation speed, the electromagnetic clutch is switched to the disconnected state and the electromagnetic clutch is switched to the non-connected state. With the bypass control valve as the closing side, it is configured to set the idling state in which intake air flows in the mechanical turbocharger that is not connected to the engine.
The supercharger is characterized in that when the engine speed sensor detects a decrease in the engine speed in the idling state, the control unit determines that the mechanical supercharger is out of order. Machine failure diagnosis device. The supercharging according to claim 1, wherein the control unit determines that the supercharger rotation speed sensor is out of order when the engine rotation speed sensor does not detect a decrease in the engine rotation speed in the idling state. Machine failure diagnosis device. The failure diagnosis device for a supercharger according to claim 1 or 2, wherein the control unit sets the idling state when the engine is in the idling state. The control unit is the failure diagnosis device for a supercharger according to claim 1 or 2, which sets the idling state when the vehicle equipped with the engine is stopped.

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