JP2007077897A - Control device for engine with supercharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To protect a system, by satisfactorily grasping an abnormality of a bypass valve for suppressing excessive increase in throttle upstream pressure. <P>SOLUTION: An intake pipe 11 of an engine 10 is provided with a throttle valve 14, and a compressor impeller 31 of a turbocharger 30 is disposed upstream of the throttle valve 14. A bypass passage 34 is interposed between an upstream part and a downstream part of the intake pipe 11 to sandwich the compressor impeller 31 therebetween, and a bypass passage 34 is provided with an air bypass valve 35. An ECU 50 instructs to open the air bypass valve 35 when a predetermined working condition is satisfied, and determines whether or not there is any abnormality of the air bypass valve 35 based on a behavior of the throttle upstream pressure after the instruction to open the valve. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a control device for an engine with a supercharger.

  Conventionally, various engines equipped with a turbocharger such as a turbocharger have been put into practical use, and the intake efficiency is improved by the operation of the turbocharger and the output of the engine is improved. In addition, in such an engine with a supercharger, a configuration including a supercharging state variable device for adjusting the supercharging state of the supercharger has been proposed, and as one of them, an intake compressor provided in an intake path is provided. There is a technique in which a bypass passage is provided so as to bypass and an air bypass valve (ABV) as a bypass valve is provided in the bypass passage. For example, if the throttle valve is fully closed in a turbocharged state, the intake pipe pressure on the upstream side of the throttle (throttle upstream pressure) rises excessively, so air bypass is used to reduce the pressure on the upstream side of the throttle. The valve is opened. In this case, by opening the air bypass valve, various problems such as generation of a surge noise through the intake air compressor and breakage of the intake pipe due to excessive increase of the throttle upstream pressure are solved.

  The air bypass valve generally has a configuration in which the bypass passage is opened or closed by the movement of the valve body. However, when the valve body is fixed due to foreign matter biting or oil adhesion, the air bypass valve opens. Cannot be done (closing abnormality occurs). When such an abnormality of the air bypass valve occurs, the throttle upstream pressure excessively rises when the throttle is fully closed, resulting in problems such as the generation of surge noise and breakage of the intake piping. Therefore, in order to solve the above inconvenience, there is a demand for a technique that can suitably detect the abnormality when an abnormality of the air bypass valve occurs.

  Incidentally, for example, a technique disclosed in Patent Document 1 is known as an abnormality detection method for actuators provided in an engine. That is, in Patent Document 1, in a pressure type actuator that operates by controlling two solenoid valves for air introduction and negative pressure introduction, the control state of one solenoid valve is detected, and the other is detected according to the control state. The abnormality of the solenoid valve is judged. At that time, a duty ratio signal output to each solenoid valve is used as an abnormality determination parameter.

However, there is no related technique for the abnormality determination method related to the air bypass valve, and even if the abnormality detection method disclosed in Patent Document 1 is used for the abnormality determination of the air bypass valve, the control output for the controlled object is used as a parameter. The bypass valve abnormality determination cannot be suitably performed.
Japanese Patent Laid-Open No. 10-18919

  The present invention mainly provides a control device for an engine with a supercharger capable of protecting the system by suitably grasping an abnormality of a bypass valve for suppressing an excessive increase in the throttle upstream pressure. It is the purpose.

  In the engine system of the present invention, a passage that bypasses the supercharger is provided in the intake system, and a bypass valve is provided in the passage, and the bypass valve is opened when a predetermined operating condition is established. . In this control device, the behavior of the throttle upstream pressure is monitored, and it is determined whether an abnormality of the bypass valve has occurred based on the behavior of the throttle upstream pressure after the operation condition is satisfied. For example, the operating condition is established when the throttle valve is fully closed as the vehicle decelerates in a supercharged state of intake air by the supercharger. Or when the supercharging pressure by a supercharger rises excessively (when it will be in a supercharging state), an operating condition will be materialized. In the case of using an electrically driven bypass valve, an opening command is output to the bypass valve when the operating condition is satisfied, and the bypass valve is opened according to the opening command.

  If an abnormality occurs in the bypass valve, the bypass valve cannot be opened regardless of whether the operating condition is satisfied (in the case of an electrically driven bypass valve, the output of an opening command). In this case, if the bypass valve is normally opened, the throttle upstream pressure changes (decreases) accordingly, but when the bypass valve is abnormal, the behavior of the throttle upstream pressure becomes different from that in the normal state. Therefore, the abnormality of the bypass valve can be determined by the behavior of the throttle upstream pressure. According to the present invention, it is possible to protect the system and the like by appropriately grasping the abnormality of the bypass valve.

  After the bypass valve is opened, the throttle upstream pressure decreases at a rate of change determined by the intake system (including the bypass passage and bypass valve). At this time, by determining a decrease pattern of the throttle upstream pressure and comparing the decrease pattern with the actual pressure behavior, it is possible to determine whether the bypass valve is abnormal.

  Therefore, as an abnormality determination method, specifically, as described in claim 2, the pressure determination value is set in accordance with the decrease pattern of the throttle upstream pressure after the bypass valve is opened, and the throttle upstream pressure is set. When the pressure exceeds the pressure determination value and the state continues for a predetermined time, it is preferable to determine that an abnormality of the bypass valve has occurred.

  Alternatively, as set forth in claim 3, the pressure determination value is set in accordance with a decrease pattern of the throttle upstream pressure after the bypass valve is opened, and the throttle upstream pressure exceeds the pressure determination value, and the throttle When the integrated value of the pressure difference between the upstream pressure and the pressure determination value is equal to or greater than a predetermined value, it may be determined that an abnormality of the bypass valve has occurred.

  As described in the second and third aspects, by setting the pressure judgment value in accordance with the decrease pattern of the pressure upstream of the throttle after the bypass valve is opened, erroneous judgment is prevented and the accuracy of abnormality judgment is improved. Can do.

  In the second and third aspects, as described in the fourth aspect, the pressure determination value may be variably set based on a throttle upstream pressure at the time when the operation condition is satisfied. Or as described in Claim 5, it is good to variably set the said pressure judgment value based on the elapsed time from establishment of the said operating condition.

  In this case, the pressure determination value may be variably set based on a differential pressure between the throttle upstream pressure and the atmospheric pressure when the operation condition is satisfied. Thereby, even if the atmospheric pressure changes due to a change in altitude of the vehicle travel location, it can be suitably dealt with.

  Further, as an abnormality determination method, as described in claim 6, if the pressure upstream of the throttle when a predetermined time elapses after establishment of the operating condition is greater than or equal to a predetermined level, an abnormality of the bypass valve has occurred. It is good to judge. When an abnormality occurs in the bypass valve, since the pressure on the upstream side of the throttle is slow to decrease after the operation condition is satisfied, the abnormality determination can be suitably performed by the above method.

  Further, as an abnormality determination method, as described in claim 7, whether an abnormality of the bypass valve has occurred based on a degree of increase in pressure upstream of the throttle accompanying inertial operation of the turbocharger after the operation condition is satisfied. It is good to judge whether. In this case, since the abnormality determination can be performed during the period of increase in the pressure upstream of the throttle accompanying the inertia operation of the supercharger, the abnormality determination can be performed quickly. Specifically, the amount of pressure increase on the upstream side of the throttle from when (or immediately before) the operating condition is established is determined, and an abnormality occurs when the amount of increase exceeds a predetermined value, or the upstream side of the throttle after the operating condition is satisfied. An abnormality may be generated when the pressure peak value exceeds a predetermined value.

  In the invention according to claim 8, when it is determined that the bypass valve is abnormal, the upper limit guard of the supercharging pressure by the supercharger is reduced. In other words, if the bypass valve is abnormal, it will not be possible to suppress an excessive increase in the pressure upstream of the throttle due to the opening of the bypass valve when the vehicle is decelerated (when the throttle is fully closed). Can be reliably protected.

  When the bypass valve becomes abnormal, it may be possible that the abnormality varies in degree. For example, there are abnormalities in which the bypass valve is stuck in a fully closed state and abnormalities in which the bypass valve is stuck in a half-open state, and these differ in the behavior of the throttle upstream pressure. Therefore, as described in claim 9, the degree of abnormality of the bypass valve is determined based on the behavior of the pressure upstream of the throttle after the operation condition is established, and the upper limit guard of the supercharging pressure is made variable according to the degree. It is good to set. As a result, an appropriate supercharging pressure guard can be applied each time an abnormality occurs.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. In the present embodiment, an engine control system is constructed for an in-vehicle multi-cylinder gasoline engine that is an internal combustion engine, and the engine of the control system is provided with a turbocharger as supercharging means. First, an overall schematic configuration diagram of the engine control system will be described with reference to FIG.

  In the engine 10 shown in FIG. 1, the intake pipe 11 is provided with a throttle valve 14 as an air amount adjusting means whose opening is adjusted by a throttle actuator 15 such as a DC motor. The throttle actuator 15 incorporates a throttle opening sensor for detecting the throttle opening. An upstream side of the throttle valve 14 is provided with a boost pressure sensor 12 for detecting the pressure upstream of the throttle (a boost pressure by a turbocharger described later), and an intake air temperature sensor 13 for detecting the intake air temperature upstream of the throttle. It has been.

  A surge tank 16 is provided on the downstream side of the throttle valve 14, and an intake pressure sensor 17 for detecting the intake pressure on the downstream side of the throttle is provided in the surge tank 16. The surge tank 16 is connected to an intake manifold 18 that introduces air into each cylinder of the engine 10. In the intake manifold 18, an electromagnetically driven fuel injection that injects fuel near the intake port of each cylinder. A valve 19 is attached.

  An intake valve 21 and an exhaust valve 22 are respectively provided in the intake port and the exhaust port of the engine 10, and an air / fuel mixture is introduced into the combustion chamber 23 by the opening operation of the intake valve 21, and the exhaust valve 22. The exhaust after combustion is discharged to the exhaust pipe 24 by the opening operation. A spark plug 25 is attached to the cylinder head of the engine 10 for each cylinder, and a high voltage is applied to the spark plug 25 at a desired ignition timing through an ignition device (not shown) including an ignition coil. By applying this high voltage, a spark discharge is generated between the opposing electrodes of each spark plug 25, and the air-fuel mixture introduced into the combustion chamber 23 is ignited and used for combustion.

  The cylinder block of the engine 10 includes a water temperature sensor 26 that detects the temperature of engine cooling water, and a crank that outputs a rectangular crank angle signal at every predetermined crank angle (for example, at a cycle of 30 ° CA) as the engine 10 rotates. An angle sensor 27 is attached.

  A turbocharger 30 is disposed between the intake pipe 11 and the exhaust pipe 24. The turbocharger 30 has a compressor impeller 31 provided in the intake pipe 11 and a turbine wheel 32 provided in the exhaust pipe 24, which are connected by a rotary shaft 33. A bypass passage 34 is provided between the upstream portion and the downstream portion of the intake pipe 11 with the compressor impeller 31 interposed therebetween, and an air bypass valve (ABV) 35 is provided in the bypass passage 34. Further, a bypass passage 36 is provided between the upstream portion and the downstream portion of the exhaust pipe 24 with the turbine wheel 32 interposed therebetween, and a waste gate valve (WGV) 37 is provided in the bypass passage 36.

  In the turbocharger 30, the turbine wheel 32 is rotated by the exhaust gas flowing through the exhaust pipe 24, and the rotational force is transmitted to the compressor impeller 31 via the rotation shaft 33. The intake air flowing through the intake pipe 11 is compressed by the compressor impeller 31 to perform supercharging. In this case, when the air bypass valve 35 is opened, the pressure on the downstream side of the compressed turbocharger is reduced, and an excessive increase in the supercharging pressure (an excessive increase in the throttle upstream pressure) is suppressed. Further, the waste gate valve 37 is opened, so that excessive supercharging pressure is prevented from being generated.

  Here, the air bypass valve 35 is known to have, for example, a normally closed type electromagnetically driven structure, and the valve body moves based on an electrical signal (energization) to the electromagnetic drive unit, and the valve body moves. Thus, the bypass passage 34 is opened or closed.

  The air supercharged by the turbocharger 30 is cooled by the intercooler 38 and then fed downstream. As the intake air is cooled by the intercooler 38, the charging efficiency of the intake air is increased.

  Further, on the upstream side of the turbocharger 30, an air flow meter 41 for detecting the intake air amount and an intake air temperature sensor 42 for detecting the intake air temperature in the intake upstream portion are provided. In addition, the present control system is provided with an accelerator opening sensor 43 that detects an operation amount (accelerator opening) of an accelerator pedal by a driver, and an atmospheric pressure sensor 44 that detects atmospheric pressure.

  As is well known, the ECU 50 is mainly composed of a microcomputer including a CPU, ROM, RAM, and the like, and executes various control programs stored in the ROM, so that various types of the engine 10 can be set according to the engine operating state each time. Implement control. That is, detection signals are input to the ECU 50 from the various sensors described above. The ECU 50 calculates the fuel injection amount, the ignition timing, and the like based on various detection signals that are input as needed, and controls the drive of the fuel injection valve 19 and the spark plug 25.

  Further, the ECU 50 calculates a target throttle opening based on various detection signals, and performs a desired air amount control by driving the throttle actuator 15 based on the target throttle opening. In this case, in particular, the target air amount is calculated based on the accelerator opening, the target throttle opening is calculated using the target air amount as a parameter, and the throttle opening is controlled based on the target throttle opening.

  Further, the ECU 50 is electrically connected to the air bypass valve 35 when the throttle valve 14 is fully closed as the vehicle is decelerated in a state where the turbocharger 30 is supercharged (under a supercharged state). A signal is output, and the air bypass valve 35 is opened. As a result, even if the throttle is fully closed under the supercharging state, the inconvenience that the throttle upstream pressure is excessively increased and a surge noise is generated or the intake pipe or the like is damaged is eliminated.

  By the way, if an operation abnormality occurs in the air bypass valve 35 due to sticking of the valve body or the like, the operating condition is satisfied and the air bypass valve 35 does not operate (opens) in a state where it should operate, and the throttle upstream pressure excessively increases. Resulting in. In this case, there is a risk that surge noise may be generated or intake pipes may be damaged. Therefore, in the present embodiment, an abnormal operation of the air bypass valve 35 is detected based on the behavior of the throttle upstream pressure, and when the abnormality occurs, a warning or the like is issued and the upper limit guard for the supercharging pressure is lowered. Treatment is performed as appropriate.

  FIG. 2 is a flowchart showing an abnormality determination process of the air bypass valve 35. This process is repeatedly executed by the ECU 50 at a predetermined time period.

  In FIG. 2, in step S101, it is determined whether or not the throttle is fully closed. At this time, when the throttle valve 14 is operated to the fully closed position during vehicle deceleration or the like, it is detected that the throttle is fully closed based on the detection signal of the throttle opening sensor. Further, in the subsequent step S102, it is determined whether or not the valve opening condition of the air bypass valve 35 is satisfied. This valve opening condition is determined based on the supercharging state by the turbocharger 30 when the throttle is fully closed, and when the differential pressure between the throttle upstream pressure (supercharging pressure) and the atmospheric pressure is a predetermined value or more. Then, it is determined that the valve opening condition of the air bypass valve 35 is satisfied. If both steps S101 and S102 are YES, the air bypass valve 35 is opened in each subsequent step, and abnormality determination of the air bypass valve 35 is performed.

  That is, in step S103, a valve opening command is output to the air bypass valve 35, and in a subsequent step S104, the boost pressure sensor 12 provided on the upstream side of the throttle in a state after the valve opening command of the air bypass valve 35 is obtained. The throttle upstream pressure Pb calculated from the detection result is read. Thereafter, in step S105, the pressure determination value Pth1 for performing the abnormality determination of the air bypass valve 35 is set using the throttle upstream pressure Pb as the abnormality determination parameter. At this time, the pressure determination value Pth1 is determined according to a change pattern of the throttle upstream pressure in a state where the air bypass valve 35 is opened after the throttle is fully closed. In this embodiment, (a) It is set based on the differential pressure between the throttle upstream pressure (supercharging pressure) and the atmospheric pressure at the time of opening command of the air bypass valve 35, and (b) the elapsed time after the opening of the air bypass valve 35. .

  Specifically, as shown in FIG. 3, the pressure determination value Pth1 is set to a larger value as the differential pressure between the throttle upstream pressure and the atmospheric pressure at the time of opening the air bypass valve 35 is larger, and the air bypass It is determined to decrease at a predetermined change rate with the passage of time after the valve opening command. Note that, after the air bypass valve is opened, the throttle upstream pressure decreases at a change rate determined by the intake system (including the bypass passage 34 and the air bypass valve 35), so that the pressure determination value Pth1 is in accordance with the change rate. The slope of is specified.

  The differential pressure value used to set the pressure determination value Pth1 (the differential pressure between the throttle upstream pressure and the atmospheric pressure) can be simply replaced with the throttle upstream pressure. In addition to reducing the pressure determination value Pth1 with time, as shown in FIG. 3, the pressure determination value Pth1 can be reduced in a non-linear manner or stepwise. is there.

  In step S106, the throttle upstream pressure Pb at that time is compared with the pressure determination value Pth1, and it is determined whether Pb ≧ Pth1. When Pb <Pth1, the process proceeds to step S107, and after the pressure excess counter is cleared to 0, this process is terminated. If Pb ≧ Pth1, the process proceeds to step S108. In step S108, the pressure excess counter is incremented by 1. In subsequent step S109, it is determined whether or not the value of the pressure excess counter is equal to or greater than a predetermined determination value K1. If the counter value ≧ K1, the process proceeds to step S110, where it is determined that the air bypass valve 35 is abnormal, and then this process is terminated.

When it is determined that the air bypass valve 35 is abnormal, the ECU 50 performs the following processes as fail-safe processes.
(1) Fault diagnosis information (diag code or the like) indicating that the air bypass valve 35 is abnormal is stored in a backup memory such as an EEPROM or a backup RAM in the ECU 50.
(2) Turn on a warning lamp (so-called MIL lamp).
(3) The upper limit guard value of the supercharging pressure by the turbocharger 30 is lowered.

  Next, the abnormality detection operation of the air bypass valve 35 during vehicle deceleration will be described more specifically with reference to the time chart of FIG. FIG. 4 shows two types of pressure behavior of the throttle upstream pressure when the ABV is normal and when the ABV is abnormal. Further, the pressure excess counter and the abnormality determination result shown on the lower side of the throttle upstream pressure indicate those at the time of ABV abnormality.

  In FIG. 4, the throttle opening decreases as the vehicle decelerates, and at timing t1, the throttle is fully closed (throttle opening = 0) to determine that the engine is in the idle state. Thereafter, a valve opening command is output to the air bypass valve 35 at timing t2. At this time, if the air bypass valve 35 is normally opened, the throttle upstream pressure Pb begins to gradually increase as the throttle opening decreases, and starts to decrease as the air bypass valve 35 opens. Thereafter, the throttle upstream pressure Pb decreases until it reaches atmospheric pressure.

  During normal operation of the air bypass valve 35 as described above, the throttle upstream pressure Pb does not exceed the pressure determination value Pth1. Therefore, the pressure excess counter is not counted up. The air bypass valve 35 is closed again (not shown) after the throttle upstream pressure Pb is reduced and stabilized at atmospheric pressure.

  On the other hand, when the operation of the air bypass valve 35 is abnormal, the air bypass valve 35 is not opened even if a valve opening command is output to the air bypass valve 35 at timing t2. Therefore, the throttle upstream pressure Pb continues to increase after the timing t2, and the throttle upstream pressure Pb exceeds the pressure determination value Pth1 after the timing t3. The increase in the throttle upstream pressure Pb after the timing t2 is due to inertial rotation of the compressor impeller 31, and the throttle upstream pressure Pb gradually decreases after reaching the peak value once. As described above, when Pb ≧ Pth1, the pressure excess counter is counted up, and it is determined that an abnormality has occurred with respect to the air bypass valve 35 at timing t4 when the counter value reaches the predetermined value K1.

  According to the present embodiment described in detail above, the abnormality determination of the air bypass valve 35 is performed based on the behavior of the throttle upstream pressure Pb after the opening instruction of the air bypass valve 35. This makes it possible to properly grasp the information, and thus protect the system. In this case, an electrical abnormality and a mechanical abnormality of the air bypass valve 35 can be suitably detected.

  When the air bypass valve 35 malfunctions, the upper limit value of the supercharging pressure by the turbocharger 30 is lowered, so that it is possible to suppress the excessive increase in the throttle upstream pressure during vehicle deceleration (when the throttle is fully closed), thereby protecting the system. It can be done reliably.

(Second Embodiment)
In the above embodiment, the pressure determination value Pth1 is set in accordance with the change pattern of the throttle upstream pressure accompanying the opening of the air bypass valve 35 after the throttle is fully closed, and the throttle upstream pressure Pb is equal to or higher than the pressure determination value Pth1. In this embodiment, the abnormality determination of the air bypass valve 35 is performed based on the continuation time in this state, but this is changed to integrate the pressure difference between the throttle upstream pressure Pb and the pressure determination value Pth1, and the pressure An abnormality determination of the air bypass valve 35 is performed based on the difference integrated value.

  As the arithmetic processing of the ECU 50, the processing in steps S106 to S110 in FIG. 2 is changed to the processing shown in FIG. That is, in FIG. 5, in step S201, it is determined whether or not the throttle upstream pressure Pb at that time is equal to or higher than the pressure determination value Pth1 (same as step S106 in FIG. 2). When Pb <Pth1, the process proceeds to step S202, and after the pressure difference integrated value ΣΔP is cleared to 0, the present process is terminated. If Pb ≧ Pth1, the process proceeds to step S203.

  In step S203, the pressure difference ΔP (= Pb−Pth1) between the throttle upstream pressure Pb and the pressure determination value Pth1 is calculated, and the pressure difference ΔP is added to the previous value of the pressure difference integrated value ΣΔP to calculate the pressure difference integrated value. The current value of ΣΔP is calculated. In subsequent step S204, it is determined whether or not the pressure difference integrated value ΣΔP is equal to or larger than a predetermined determination value K2. If ΣΔP ≧ K2, the process proceeds to step S205 to determine that the air bypass valve 35 is abnormal.

  FIG. 6 is a time chart showing an abnormality detection operation of the air bypass valve 35 during vehicle deceleration. In FIG. 6, changes in the throttle opening, the opening command of the air bypass valve 35, and the throttle upstream pressure Pb during normal and abnormal time are the same as in FIG.

  In FIG. 6, after the throttle is fully closed (throttle opening = 0) at timing t11, a valve opening command is output to the air bypass valve 35 at timing t12. At this time, if the air bypass valve 35 is normally opened, the throttle upstream pressure Pb begins to gradually increase as the throttle opening decreases, and starts to decrease as the air bypass valve 35 opens. Therefore, the throttle upstream pressure Pb does not exceed the pressure determination value Pth1, and the pressure difference integrated value ΣΔP remains zero.

  On the other hand, when the operation of the air bypass valve 35 is abnormal, the air bypass valve 35 is not opened even if a valve opening command is output to the air bypass valve 35 at timing t12. Therefore, as the throttle upstream pressure Pb increases, after the timing t13, the throttle upstream pressure Pb exceeds the pressure determination value Pth1, and the pressure difference integrated value ΣΔP is calculated as illustrated. Then, at timing t14, ΣΔP ≧ K2 is satisfied, so that it is determined that an abnormality related to the air bypass valve 35 has occurred.

  As described above, according to the second embodiment, similarly to the first embodiment, it is possible to appropriately grasp the abnormality of the air bypass valve, and to protect the system.

(Third embodiment)
In each of the above embodiments, the pressure determination value Pth1 is set in accordance with the change pattern of the throttle upstream pressure Pb accompanying the opening of the air bypass valve 35 after the throttle is fully closed. The pressure judgment value Pth2 that does not change with time is set. If the throttle upstream pressure Pb when a predetermined time has elapsed from the opening command of the air bypass valve 35 is equal to or higher than a predetermined level, it is determined that an abnormality of the air bypass valve 35 has occurred.

  As calculation processing of the ECU 50, processing shown in FIG. 7 is executed instead of the processing shown in FIG. 2 or FIG. Note that steps S301 to S304 are the same as steps S101 to S104 in FIG. 2, and the description will be simplified.

In FIG. 7, a valve opening command is output to the air bypass valve 35 on condition that the throttle is fully closed and the valve opening condition of the air bypass valve 35 is satisfied.
The throttle upstream pressure Pb calculated from the detection result of the supercharging pressure sensor 12 is read (steps S301 to S304). Thereafter, in step S305, a pressure determination value Pth2 for performing an abnormality determination of the air bypass valve 35 is set using the throttle upstream pressure Pb as an abnormality determination parameter. At this time, unlike the pressure determination value Pth1, the pressure determination value Pth2 does not conform to the change pattern of the throttle upstream pressure, and is a constant value regardless of the time change. However, the pressure determination value Pth2 may be variably set based on the differential pressure between the throttle upstream pressure and the atmospheric pressure at the time of opening the air bypass valve 35, and specifically, the throttle upstream pressure and the atmospheric pressure. The pressure determination value Pth2 is increased as the differential pressure increases.

  Thereafter, in step S306, the time elapsed counter for measuring the elapsed time after the opening instruction of the air bypass valve 35 is incremented by 1. In the subsequent step S307, is the value of the time elapsed counter equal to or greater than a predetermined determination value K3? Determine whether or not. If the counter value ≧ K3, the process proceeds to step S308, and it is determined whether or not the throttle upstream pressure Pb at that time is equal to or higher than the pressure determination value Pth2. If Pb <Pth2, the process is terminated as it is. If Pb ≧ Pth2, the process proceeds to step S309, where it is determined that the air bypass valve 35 is abnormal.

  FIG. 8 is a time chart showing an abnormality detection operation of the air bypass valve 35 during vehicle deceleration. In FIG. 8, changes in the throttle opening, the valve opening command for the air bypass valve 35, and the throttle upstream pressure Pb during normal operation and abnormal operation are the same as in FIG.

  In FIG. 8, after the throttle is fully closed (throttle opening = 0) at timing t21, a valve opening command is output to the air bypass valve 35 at timing t22. At this time, if the air bypass valve 35 is normally opened, the throttle upstream pressure Pb begins to gradually increase as the throttle opening decreases, and starts to decrease as the air bypass valve 35 opens. Therefore, the throttle upstream pressure Pb becomes less than the pressure determination value Pth2 at a timing t23 (a timing at which the value of the time elapsed counter becomes the predetermined value K3) after a predetermined time has elapsed after the opening instruction of the air bypass valve 35.

  On the other hand, when the operation of the air bypass valve 35 is abnormal, the air bypass valve 35 is not opened even if a valve opening command is output to the air bypass valve 35 at timing t22. Therefore, the throttle upstream pressure Pb rises excessively, and the throttle upstream pressure Pb becomes equal to or higher than the pressure determination value Pth2 at a timing t23 when a predetermined time has elapsed after the opening command of the air bypass valve 35. Thereby, it is determined that an abnormality has occurred with respect to the air bypass valve 35.

  As described above, also in the third embodiment, the air bypass valve abnormality can be properly grasped as in the first embodiment, and the system can be protected.

  In addition, this invention is not limited to the content of description of the said embodiment, For example, you may implement as follows.

  The abnormality determination may be performed based on the degree of increase in the throttle upstream pressure associated with the inertial operation of the turbocharger 30 after the air bypass valve 35 is opened. Specifically, an increase amount of the throttle upstream pressure from the throttle upstream pressure Pb at the time of opening the air bypass valve 35 (or immediately before) is obtained, and an abnormality occurs when the increase amount exceeds a predetermined value. . Alternatively, an abnormality occurs when the pressure difference between the throttle upstream pressure Pb at the time of opening the air bypass valve 35 (or immediately before) and the peak value of the throttle upstream pressure Pb after the valve opening command exceeds a predetermined value. To do. In this case, since the abnormality determination can be performed during the period of increase in the throttle upstream pressure accompanying the inertial operation of the turbocharger 30, the abnormality determination can be performed quickly.

  In the third embodiment, it has been described that the pressure determination value Pth2 may be variably set based on the differential pressure between the throttle upstream pressure and the atmospheric pressure when the air bypass valve 35 is instructed to open. Instead of variably setting Pth2, a determination value K3 for determining the value of a time elapsed counter (a counter for measuring the elapsed time after the air bypass valve 35 is opened) is used as a valve opening command for the air bypass valve 35. It may be variably set based on the differential pressure between the throttle upstream pressure and the atmospheric pressure at that time. In this configuration as well, excellent effects can be obtained as described above.

  In the configuration in which the fixed time pressure determination value Pth2 is set as in the third embodiment, the time required until the throttle upstream pressure Pb decreases to the pressure determination value Pth2 after the air bypass valve 35 is opened. Measurement may be made and abnormality determination of the air bypass valve 35 may be performed based on the required time.

  When the air bypass valve 35 becomes abnormal, it is conceivable that a difference in degree occurs in the abnormality. For example, there are abnormalities in which the air bypass valve 35 is stuck in the fully closed state and abnormalities in which the bypass valve 35 is stuck in the half-open state, and these differ in the behavior of the throttle upstream pressure. Therefore, the degree of abnormality of the air bypass valve 35 is determined based on the behavior of the throttle upstream pressure after the opening command of the air bypass valve 35, and the upper limit guard value of the supercharging pressure is variably set according to the degree. May be. As a result, an appropriate supercharging pressure guard can be applied each time an abnormality occurs.

  As a method for determining the degree of abnormality of the air bypass valve 35, it is possible to determine from the integrated value (ΣΔP described above) of the pressure difference between the throttle upstream pressure and the pressure determination value after the air bypass valve 35 is opened. It can be determined from the peak value of the throttle upstream pressure after the valve command, or from the time required for the throttle upstream pressure to drop to a predetermined pressure value after the valve opening command.

  In the above embodiment, a valve opening command is output to the air bypass valve 35 on the assumption that the operating condition of the air bypass valve 35 is satisfied when the turbocharger 30 is in a supercharged state of the intake air and the throttle is fully closed due to vehicle deceleration. However, in addition to this, when the supercharging pressure by the turbocharger 30 is excessively increased (when the supercharging state is reached), a valve opening command is issued to the air bypass valve 35 because the operating condition is satisfied. It may be output.

  It is also possible to configure the air bypass valve 35 so that the opening degree can be adjusted. For example, a configuration having a linear solenoid may be used, and the valve body position may be adjusted in accordance with a control signal from the ECU, and the opening degree may be adjusted accordingly.

  In the above embodiment, the air bypass valve 35 as a bypass valve has an electromagnetically driven structure, and the air bypass valve 35 is opened and closed by an electrical valve opening command from the ECU 50. Adopt a mechanical air bypass valve using a diaphragm. For example, a diaphragm type movable part is provided, and two pressure chambers (first pressure chamber and second pressure chamber) are defined by the diaphragm, and the throttle downstream pressure is provided in the first pressure chamber and the throttle upstream is provided in the second pressure chamber. Pressure (supercharging pressure) is introduced. During normal times, the valve body is held in the closed position by the pressure in the first pressure chamber (throttle downstream pressure) and the urging force of the coil spring or the like, and when the throttle upstream pressure rises, the pressure in the second pressure chamber (throttle upstream pressure) To actuate the valve body to the open position.

  When the mechanical air bypass valve as described above is adopted, the air bypass valve is activated as the throttle upstream pressure rises when the intake air is supercharged by the turbocharger and the throttle is fully closed due to vehicle deceleration ( Open). In addition, when the supercharging pressure by the turbocharger increases excessively (when the supercharging state is reached), the air bypass valve is activated (opened) as the throttle upstream pressure increases. Even in such a configuration, the abnormality of the bypass valve can be determined based on the behavior of the throttle upstream pressure after the operation condition is satisfied as described above.

It is a block diagram which shows the outline of the engine control system in embodiment of invention. It is a flowchart which shows the abnormality determination process of an air bypass valve. It is a figure for demonstrating pressure judgment value Pth1. It is a time chart which shows the abnormality detection operation | movement of an air bypass valve at the time of vehicle deceleration. It is a flowchart which shows the abnormality determination process of an air bypass valve in 2nd Embodiment. It is a time chart which shows abnormality detection operation | movement of the air bypass valve at the time of vehicle deceleration in 2nd Embodiment. It is a flowchart which shows the abnormality determination process of an air bypass valve in 3rd Embodiment. It is a time chart which shows abnormality detection operation | movement of the air bypass valve at the time of vehicle deceleration in 3rd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Engine, 11 ... Intake pipe, 30 ... Turbocharger, 34 ... Bypass passage, 35 ... Air bypass valve, 50 ... ECU.

Claims (9)

A throttle valve provided in the intake system for adjusting the intake air amount, a supercharger provided upstream of the throttle valve for supercharging intake air, and a passage bypassing the supercharger in the intake system And is applied to an engine system in which the bypass valve is opened when a predetermined operating condition is established,
Pressure monitoring means for monitoring the behavior of the throttle upstream pressure,
An abnormality determining means for determining whether or not an abnormality of the bypass valve has occurred based on the behavior of the pressure upstream of the throttle after establishment of the operating condition;
A control device for an engine with a supercharger.   The abnormality determining means sets a pressure determination value in accordance with a decrease pattern of the pressure upstream of the throttle after the bypass valve is opened, and the pressure upstream of the throttle exceeds the pressure determination value, and the state continues for a predetermined time. 2. The control device for an engine with a supercharger according to claim 1, wherein it is determined that an abnormality of the bypass valve has occurred.   The abnormality determining means sets a pressure determination value in accordance with a decrease pattern of the throttle upstream pressure after the bypass valve is opened, the throttle upstream pressure exceeds the pressure determination value, and the throttle upstream pressure and pressure The supercharger-equipped engine control device according to claim 1, wherein when the integrated value of the pressure difference from the determination value is equal to or greater than a predetermined value, it is determined that an abnormality of the bypass valve has occurred. .   4. The supercharger-equipped engine control device according to claim 2, wherein the pressure determination value is variably set based on a throttle upstream pressure when the operating condition is satisfied.   The control device for an engine with a supercharger according to claim 2 or 3, wherein the pressure determination value is variably set based on an elapsed time from establishment of the operating condition.   The abnormality determining means determines that an abnormality of the bypass valve has occurred if a pressure upstream of the throttle when a predetermined time has elapsed after the activation of the operating condition is greater than or equal to a predetermined level. 1. A control device for an engine with a supercharger according to 1.   The abnormality determining means determines whether or not an abnormality of the bypass valve has occurred based on a degree of increase in pressure upstream of the throttle accompanying inertial operation of the turbocharger after the operation condition is established. The supercharger-equipped engine control device according to claim 1.   The supercharger according to any one of claims 1 to 7, wherein when the bypass determination unit determines that the bypass valve is abnormal, an upper limit guard for a supercharging pressure by the supercharger is reduced. Engine control unit.   The degree of abnormality of the bypass valve is determined based on the behavior of the throttle upstream pressure after the operation condition is satisfied, and the upper limit guard for the supercharging pressure is variably set according to the degree. 8. A control device for an engine with a supercharger according to 8.

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