JP2009068339A - Control device for engine with supercharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately detect the sticking of an intake change-over valve in a twin turbo system including a relief valve operated by a pressure difference in a bypass passage for bypassing the upstream and downstream sides of the intake change-over valve for opening/closing the intake passage on the downstream side of a compressor in an auxiliary turbocharger. <P>SOLUTION: Since a pressure difference between the front and rear sides of a relief valve is not relieved (reduced) when an intake change-over valve is closed and fixed, the relief valve is forced to keep open at original closing operation timing (t2). When the pressure difference between the front and rear sides of the relief valve is reduced to a certain extent by the circulation from the relief valve, the relief valve is closed (t3) to change the supercharging pressure to tend to decrease (t3-t4). Since the temporary drop in the supercharging pressure between t3 and t4 is a characteristic decrease when the intake change-over valve is closed and fixed, the close and fix is detected. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a supercharger-equipped engine control apparatus, and more particularly, in a structure having a main turbocharger and a subturbocharger, upstream and downstream of an intake switching valve that opens and closes an intake passage downstream of a compressor of the subturbocharger. The present invention relates to a bypass passage having a relief valve in the bypass passage.

  A so-called twin turbo system that has a main turbocharger and a subturbocharger, operates only the main turbocharger in the low intake air volume range, and operates both the main and sub turbochargers in the high intake air volume range. Adopted supercharged engine is known.

  This type of supercharged engine is configured, for example, as shown in FIG. A main turbocharger 103 and a sub turbocharger 104 are provided in parallel to the engine body 102. An intake switching valve 109 is provided in the intake system connected to the sub turbocharger 104, and an exhaust switching valve 108 is provided in the exhaust system.

  In the low intake air amount region, both the intake switching valve 109 and the exhaust switching valve 108 are fully closed to supercharge only the main turbocharger 103. In the high intake air amount region, both of the switching valves 109 and 108 are fully opened, so that the sub turbocharger 104 is also supercharged, and two turbochargers are operated.

  In such an engine with a supercharger, if the intake switching valve is closed firmly (that is, stuck in the closed state) or openly stuck (that is, stuck in the opened state), control cannot be performed correctly. It is desirable to be able to detect valve sticking as a failure.

  The device disclosed in Patent Literature 1 detects a differential pressure between the upstream side and the downstream side of the intake switching valve by a differential pressure sensor in order to detect the sticking of the intake switching valve, and this differential pressure is set to a predetermined reference value. Comparing.

  The device disclosed in Patent Document 2 compares the supercharging pressure detected by the supercharging pressure sensor downstream of the intake switching valve with a predetermined reference value in order to detect sticking of the intake switching valve.

JP-A-6-346744 JP-A-5-98981

  In the configuration of Patent Document 1, in addition to the supercharging pressure sensor used for controlling the supercharging pressure, it is necessary to newly provide a dedicated differential pressure sensor, which leads to an increase in cost and the detection of the supercharging pressure sensor failure. In addition, it is also necessary to detect a failure of the differential pressure sensor.

  On the other hand, in Patent Document 2, a relief valve 111 is provided in a bypass passage 110 that bypasses the upstream and downstream sides of the intake air switching valve 109. When shifting from the low intake air amount region to the high intake air amount region, when the exhaust gas switching valve 108 is opened and the auxiliary engine speed of the auxiliary turbocharger 104 is increased from the state where the intake gas switching valve 109 and the exhaust gas switching valve 108 are closed. The relief valve 111 is opened by the differential pressure between the downstream of the compressor 103b of the main turbocharger 103 and the downstream of the compressor 104b of the auxiliary turbocharger 104. As a result, the shock when the intake switching valve 109 is subsequently opened is reduced, and the turbocharger can be switched more smoothly. However, in this configuration, since the deviation between the target boost pressure and the actual boost pressure is reduced by the action of the relief valve 111, the boost pressure detected by the boost pressure sensor 131 on the downstream side of the intake air switching valve. It is difficult to detect the sticking of the intake switching valve by a method of comparing with a predetermined reference value, or at least a considerable delay may occur.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an intake system in a twin turbo system having a relief valve that operates by differential pressure in a bypass passage that bypasses the upstream and downstream sides of an intake switching valve that opens and closes an intake passage downstream of a compressor of a sub turbocharger. It is to appropriately detect sticking of a valve for opening and closing the valve.

  The supercharged engine control apparatus of the present invention includes a main turbocharger, a sub turbocharger, an intake switching valve that opens and closes an intake passage downstream of a compressor of the sub turbocharger, and the intake switching valve in the intake passage. A bypass passage that bypasses the upstream and downstream, and a relief that is provided in the bypass passage and opens when the pressure downstream of the compressor of the auxiliary turbocharger is higher than the pressure downstream of the compressor of the main turbocharger. And in the low intake air amount region, the intake switching valve is closed to supercharge only the main turbocharger, and in the high intake air amount region, both of the intake switching valves are opened. In the supercharger-equipped engine control apparatus that supercharges the turbocharger, the intake switching valve A supercharging pressure sensor that detects a supercharging pressure on the downstream side, and a switching valve that determines whether or not the intake switching valve is closed and fixed based on the behavior of the supercharging pressure resulting from the operation of the relief valve And a sticking determination means.

  The relief valve operated by the differential pressure between the main turbocharger side and the sub turbocharger side alternately repeats the valve opening due to the differential pressure and the valve closing due to the reduction of the differential pressure immediately after the valve opening. Therefore, even if the deviation between the target boost pressure and the actual boost pressure is reduced by opening the relief valve, if the opening / closing movement of the relief valve is detected from the behavior of the boost pressure as in the present invention, the intake air It is possible to appropriately detect the sticking of the switching valve in the closed state.

  Preferably, the switching valve adhering determination means determines that the intake switching valve is closed and adhering when the supercharging pressure has temporarily decreased after an instruction to open the intake switching valve. is there.

  The switching valve adhering determination means is further configured to determine whether or not the intake switching valve is based on a deviation between the supercharging pressure after the opening operation instruction to the intake switching valve and a predetermined normal 2-turbo supercharging pressure. It may be determined whether or not it is closed and fixed. In this case, it is possible to make the detection of sticking more appropriate by making two types of determinations.

  Further, the switching valve adhering determination means is configured to determine whether the intake switching valve is based on a deviation between the supercharging pressure before the opening operation instruction to the intake switching valve and a predetermined normal 1 turbo supercharging pressure. It may be determined whether or not it is open-fixed. In this case, it is possible to detect not only the case where the intake switching valve is stuck closed but also the case where the intake switching valve is stuck open.

  The determination by the switching valve sticking determination means is preferably performed based on a comparison between the integrated value of the deviation and a predetermined reference value. In this case, the accuracy of determination can be improved.

  Another aspect of the present invention includes a main turbocharger, a sub turbocharger, an intake switching valve that opens and closes an intake passage downstream of a compressor of the sub turbocharger, and upstream and downstream of the intake switching valve in the intake passage. And a relief valve that is provided in the bypass passage and opens when the pressure downstream of the compressor of the auxiliary turbocharger is higher than the pressure downstream of the compressor of the main turbocharger. In the low intake air volume range, only the main turbocharger is supercharged by closing the intake switching valve, and in the high intake air volume range, both turbochargers are excessively opened by opening the intake switching valve. In the supercharger-equipped engine control apparatus configured to perform a charging operation, a supercharging pressure downstream of the intake air switching valve The supercharging pressure sensor to be detected and the sub turbocharger are in supercharging operation, and there is no behavior of the supercharging pressure due to the operation of the relief valve before an instruction to open the intake switching valve In this case, the control apparatus for the supercharged engine further comprises a relief valve sticking determination unit that determines that the relief valve is closed and stuck.

  In this aspect, it is possible to detect the closed sticking of the relief valve based on the behavior of the supercharging pressure.

  In this case, the relief valve adhering determination means further performs the determination based on a comparison between an integrated value of a deviation between the supercharging pressure and a predetermined normal-time supercharging pressure and a predetermined reference value. It is preferable to execute. In this case, the determination accuracy can be improved.

  Another aspect of the present invention includes a main turbocharger, a sub turbocharger, an intake switching valve that opens and closes an intake passage downstream of a compressor of the sub turbocharger, and upstream and downstream of the intake switching valve in the intake passage. And a relief valve that is provided in the bypass passage and opens when the pressure downstream of the compressor of the auxiliary turbocharger is higher than the pressure downstream of the compressor of the main turbocharger. In the low intake air volume range, only the main turbocharger is supercharged by closing the intake switching valve, and in the high intake air volume range, both turbochargers are excessively opened by opening the intake switching valve. In the supercharger-equipped engine control apparatus configured to perform a charging operation, a supercharging pressure downstream of the intake air switching valve And a relief valve adhering determining means for determining that the relief valve is adhering closed based on the amount of change per hour in the supercharging pressure after instructing the opening operation to the intake air switching valve; Is a control device for a supercharged engine. In this case, the determination accuracy can be improved.

  Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, a supercharged engine 1 according to an embodiment of the present invention includes an engine body 2 and a main turbocharger 3 and a sub turbocharger 4 provided in parallel with each other. The turbines 3 a and 4 a of the turbochargers 3 and 4 are connected to the exhaust port of the engine body 2 via the exhaust passage 5, and the compressors 3 b and 4 b are connected to the engine body via the intake passage 7 having the intercooler 6. 2 intake ports.

  The main turbocharger 3 is operated from a low intake air amount region to a high intake air amount region. The auxiliary turbocharger 4 is operated only in the high intake air region and is stopped in the low intake air amount region. In order to enable operation and stop of the sub turbocharger 4, an exhaust gas switching valve 8 is provided upstream of the turbine 4 a of the sub turbocharger 4 and downstream of the branch point of the exhaust passage 5. An intake switching valve 9 is provided downstream of the compressor 4b and upstream of the junction with the intake passage 7 downstream of the compressor 3b. When both the exhaust switching valve 8 and the intake switching valve 9 are opened, the sub turbocharger 4 is operated.

  A bypass passage 10 is provided in the intake passage 7 on the downstream side of the compressor 4b so that the upstream and downstream sides of the intake switching valve 9 communicate with each other. A relief valve 11 is provided in the bypass passage 10. The relief valve 11 is of a differential pressure operation type in which the valve body is always urged in the closing direction by the elasticity of the valve body itself or the spring force of the spring connected to the valve body. When the compressor outlet pressure becomes larger than the main turbocharger 3 side, the differential pressure between the two acts on the valve body to open the valve so that air can flow from the upstream side to the downstream side. The relief valve 11 has a unidirectional direction in another configuration, such as a spherical valve body housed in a valve housing provided with a valve seat, and urging the valve body in the direction of seating on the valve seat with a valve spring. It may be a valve or a check valve.

  The intake passage 7 upstream of the compressors 3b and 4b is opened to the outside air via an air flow meter 12 and an air cleaner 13. The exhaust passage 5 on the downstream side of the turbines 3a and 4a is opened to the outside air via an exhaust gas catalyst and a muffler (not shown).

  The intake switching valve 9 is opened and closed by an actuator 21, and the exhaust switching valve 8 is opened and closed by an actuator 22. These actuators 21 and 22 are electric type, but may be a diaphragm type operated by selective introduction of supercharging pressure or negative pressure by an electromagnetic valve.

  A supercharging pressure sensor 31 is installed in the intake passage 7 at a downstream side of the bypass passage 10 and downstream of the intake switching valve 9. As the detection element of the supercharging pressure sensor 31, for example, a piezoelectric element can be used, but other configurations may be used.

  ECU20 is electrically connected with the various sensors which detect the driving | running condition of an engine, and a signal is input. Such various sensors include a throttle opening sensor 32, a crank angle sensor 33, and an oxygen sensor 34 in addition to the air flow meter 12 and the supercharging pressure sensor 31 described above. The ECU 20 includes a CPU, a ROM, a RAM, an input / output interface, an A / D converter, and a D / A converter. A target boost pressure map in which the engine speed, the fuel injection amount, and the target boost pressure are stored in association with each other is created in advance and stored in the ROM of the ECU 20. In addition, the target boost pressure map may use parameters such as intake air temperature and atmospheric pressure as input variables. Different maps may be used depending on the gear ratio.

  Next, the basic operation of this embodiment will be described. In the high intake air amount range, the intake switching valve 9 and the exhaust switching valve 8 are both opened by the control of the ECU 20. As a result, both turbochargers 3 and 4 are driven, a sufficient amount of supercharged air is obtained, and the output is improved. In the low speed range and at a high load, both the intake switching valve 9 and the exhaust switching valve 8 are closed under the control of the ECU 20. As a result, only the main turbocharger 7 is driven. The reason why the single turbocharger is used in the low intake air amount region is that the single turbocharger supercharging characteristic is superior to the two turbocharger supercharging property in the low intake air amount region. By using a single turbocharger, the boost pressure and torque rise quickly, and the response is quick.

  When shifting from the low intake air amount region to the high intake air amount region, that is, when switching from the single turbocharger to the two turbocharger operation, the ECU 20 starts from the state where the intake switching valve 9 and the exhaust switching valve 8 are closed. By controlling the opening of the exhaust gas switching valve 8, it is possible to increase the running speed of the auxiliary turbocharger 4 and to switch the turbochargers 3 and 4 more smoothly (less shock at the time of switching). Furthermore, the relief valve 11 is opened by the differential pressure between the compressor downstream of the main turbocharger 3 and the compressor downstream of the auxiliary turbocharger 4 when the exhaust switching valve 9 is opened to increase the running speed of the auxiliary turbocharger 3. Thus, the shock when the intake switching valve 9 is subsequently opened is reduced, and the turbocharger can be switched more smoothly.

  In the apparatus of this embodiment, a failure (closed sticking) occurs in the fully closed state of the intake switching valve 9 due to foreign matter adhesion or failure of the actuator 21, or a failure (closed sticking) in the fully closed state of the relief valve 11 occurs. ) May occur. If the intake switching valve 9 is closed and fixed, there is a problem that the compressor is abnormally heated due to a significant rise in the intake air temperature at the inlet of the compressor 4b of the sub turbocharger 4 or the main turbocharger 3 is over-rotated. When the relief valve 11 is closed and fixed, the shock when the intake switching valve 9 is subsequently opened becomes significant, and the amount of fuel injection that is assumed to open the relief valve 11 is performed. If the air fuel ratio is insufficient, the emission of HC (hydrocarbon) / PM (particulate matter) may be deteriorated. In this embodiment, in order to prevent these, various diagnostic processes described below are performed in parallel with each other.

  The first diagnosis process shown in FIG. 2 detects closed adhering of the intake switching valve based on the presence or absence of a temporary decrease in the supercharging pressure. In FIG. 2, the ECU 20 first determines whether or not the drive signal to the intake air switching valve 9 is ON (S10), and if not, exits this routine. This drive signal is an instruction signal for opening the intake air switching valve 9, and ON corresponds to opening.

  If the determination is affirmative, the ECU 20 then obtains a differential value dP / dt obtained by dividing a deviation dP obtained by subtracting the current value from the previous value of the supercharging pressure by a minute time dt (for example, 0.1 second) as a detection interval. Is calculated (S20).

  Next, the ECU 20 determines whether or not the differential value dP / dt is equal to or less than 0 (S30). If the result is affirmative, that is, if the supercharging pressure is equal to or decreased from the previous value, it is the detection interval. The time dt is integrated (S40).

  The processes in steps S20 to S40 are repeatedly executed until the integration time exceeds a predetermined abnormality threshold value T1 (S50). When the accumulated time exceeds the abnormal threshold value T1, a predetermined intake switching valve closed stick flag is turned on (S60). If the differential value dP / dt becomes a positive value at any time, that is, if the supercharging pressure has increased from the previous value, the accumulated time is initialized to 0 (S70). Exit the routine.

  As a result of the above processing, in the first diagnosis processing, when the decrease in the supercharging pressure continues beyond a predetermined time (S50), the intake switching valve closed adhering flag is turned on (S60).

  The change in the supercharging pressure when entering the operation region of the auxiliary turbocharger 4 will be described with reference to FIG. 3. When the intake switching valve 9 operates normally, the time point when the operation region of the auxiliary turbocharger is entered ( Since the exhaust control valve 8 is opened at t0), the auxiliary turbocharger 4 is operated accordingly, and the pressure on the downstream side of the compressor 4b is increased to open the relief valve 11 (t1). Then, after a predetermined delay time from the opening operation of the exhaust control valve 8, the intake switching valve drive signal is turned on (t2), and the intake switching valve 9 is opened. For this reason, the boost pressure downstream of the intake air switching valve 9 rises almost linearly as indicated by the solid line a. The above is the change in the normal supercharging pressure.

  On the other hand, when the intake switching valve 9 is closed and fixed, the exhaust control valve 8 is opened and the relief valve 11 is opened (t1) when the sub-turbocharger enters the operation region (t0). The process is the same as normal. However, even if the intake switching valve drive signal is turned on (t2), since the intake switching valve 9 is closed and fixed, the supercharging pressure does not rise steeply, and by a slight flow of intake air from the relief valve 11, It rises gently (t2 to t3). In the meantime, the pressure difference before and after the relief valve 11 is not relaxed (decreased) by the intake switching valve 9, so that the relief valve 11 continues to open without closing at the original closing operation timing (t2). And if the pressure difference before and behind the relief valve 11 becomes small to some extent by the distribution | circulation from the relief valve 11, this will close the relief valve 11 (t3). Then, since only intake air is supplied from the compressor 3b of the main turbocharger 3 to the intake passage 7 in the vicinity of the supercharging pressure sensor 31, the supercharging pressure starts to decrease (t3 to t4). This temporary decrease in the supercharging pressure between t3 and t4 (region A surrounded by an ellipse) is a characteristic decrease when the intake switching valve 9 is closed and fixed, and is detected in this routine. To do. Therefore, it is preferable to set the abnormal threshold value T1 shorter than a general time between t3 and t4. Since the back pressure of the relief valve 11 increases again by the operation of the sub turbocharger 4, the relief valve 11 opens after a certain delay time, and the boost pressure in the boost pressure sensor 31 increases again. (T4).

  Next, the second diagnosis process in the present embodiment will be described. The second diagnosis process shown in FIG. 4 is based on the difference between the supercharging pressure after the opening operation instruction to the intake switching valve 9 and a predetermined normal-time 2-turbo supercharging pressure. It is determined whether or not is closed and fixed. In FIG. 4, the ECU 20 first determines whether or not the drive signal to the intake air switching valve 9 is ON (S110), and if not, exits this routine. This drive signal is an instruction signal for opening the intake air switching valve 9, and ON corresponds to opening.

  If the determination is affirmative, the ECU 20 then calculates a deviation ΔP obtained by subtracting the current supercharging pressure from a predetermined normal 2-turbo supercharging pressure (S120).

  Next, the ECU 20 determines whether the deviation ΔP is larger than a predetermined value (S130). If the determination is affirmative, that is, if the supercharging pressure is considerably lower than the normal 2-turbo supercharging pressure, the detection interval is detected. Is accumulated (S140).

  The processes in steps S120 to S140 are repeatedly executed until the integration time exceeds a predetermined abnormality threshold value T2 (S150). When the accumulated time exceeds the abnormal threshold value T2, a predetermined intake switching valve closed sticking flag is turned on (S160). If the deviation ΔP becomes equal to or smaller than the predetermined value at any time, that is, if the supercharging pressure is close to the normal value, the accumulated time is initialized to 0 (S170), and this routine is exited. .

  As a result of the above processing, in the second diagnosis processing, the state where the deviation between the normal value of the supercharging pressure and the current value is larger than the predetermined value under the condition that the drive signal to the intake air switching valve 9 is ON is the predetermined time. Is exceeded (S150), the intake switching valve closed adhering flag is turned on (S160). Referring to FIG. 3 described above, when the intake switching valve 9 indicated by the broken line b is closed and fixed, the relief valve 11 is closed after the opening operation (t3), and the back pressure accompanying the operation of the auxiliary turbocharger 4 is increased. The boost pressure tends to increase more slowly than normal, such as reopening when it rises. Therefore, by detecting such a characteristic transition based on the value of the deviation ΔP, it becomes possible to further detect the sticking.

  Next, the third diagnosis process in this embodiment will be described. The third diagnosis process shown in FIG. 5 is based on the deviation between the supercharging pressure before the opening operation instruction to the intake air switching valve 9 and the predetermined normal time 1 turbo supercharging pressure. It is determined whether or not is stuck open. In FIG. 5, the ECU 20 first determines whether or not the drive signal to the intake air switching valve 9 is OFF (S210), and if not, exits this routine. This drive signal is an instruction signal for opening the intake air switching valve 9, and OFF corresponds to closing.

  If the determination is affirmative, the ECU 20 next calculates a deviation ΔP obtained by subtracting the current supercharging pressure from a predetermined normal 1 turbocharging pressure (S220).

  Next, the ECU 20 determines whether the deviation ΔP is larger than a predetermined value (S230). If the determination is affirmative, that is, if the supercharging pressure is considerably lower than the normal 1 turbo supercharging pressure, the detection interval is determined. Is accumulated (S240).

  The processes in steps S220 to S240 are repeatedly executed until the integration time exceeds a predetermined abnormality threshold value T3 (S250). When the accumulated time exceeds the abnormal threshold value T3, a predetermined intake switching valve open fixing flag is turned on (S260). If the deviation ΔP becomes equal to or smaller than the predetermined value at any time, that is, if the supercharging pressure is close to the normal value, the accumulated time is initialized to 0 (S270) and the routine is exited.

  As a result of the above process, in the third diagnosis process, the state where the deviation between the normal value of the boost pressure and the current value is larger than the predetermined value is a predetermined time under the condition that the drive signal to the intake air switching valve 9 is OFF. Is exceeded (S250), the intake switching valve open fixing flag is turned on (S260). Referring to FIG. 3 described above, when the intake switching valve 9 is fixed open, the compressor-side outlets of the main and auxiliary turbochargers 3 and 4 communicate with each other. Even if the main turbocharger 3 operates, the increase of the supercharging pressure becomes slow, and a deviation from the normal value (solid line a) occurs. Therefore, by detecting such a characteristic transition based on the value of the deviation ΔP, it becomes possible to further detect the sticking. Note that when the intake air switching valve 9 is fixed open, the other diagnostic processing described in the present embodiment cannot be performed, so the third diagnostic processing may be performed prior to other diagnostic processing.

  Next, the fourth diagnosis process in the present embodiment will be described. In the fourth diagnosis process shown in FIG. 6, the relief valve 11 is closed and fixed based on the deviation between the supercharging pressure before the opening operation instruction to the intake air switching valve 9 and a predetermined target supercharging pressure. It is determined whether or not. In FIG. 6, the ECU 20 first determines whether the drive signal to the exhaust gas switching valve 8 is ON (S310) and whether the drive signal to the intake air switch valve 9 is OFF (S320). Exit the routine. These drive signals are instruction signals for individually opening the exhaust switching valve 8 and the intake switching valve 9, and ON corresponds to opening.

  If the determination in step S320 is affirmative, the ECU 20 next calculates the target boost pressure by referring to the above-described target boost pressure map based on the current values of the engine speed and the fuel injection amount (S330). Next, the ECU 20 detects the current boost pressure from the boost pressure sensor 31 (S340), and subtracts the current boost pressure from the target boost pressure to calculate the deviation ΔP (S350).

  Next, the ECU 20 determines whether or not the deviation ΔP is larger than a predetermined value (S360). If the result is affirmative, that is, if the supercharging pressure is considerably lower than the target supercharging pressure, the time that is the detection interval is determined. dt is integrated (S370).

  The processes in steps S330 to S370 are repeatedly executed until the integration time exceeds a predetermined abnormality threshold value T4 (S380). When the accumulated time exceeds the abnormal threshold value T4, a predetermined relief valve closed sticking flag is turned on (S390). Further, when the deviation ΔP becomes equal to or less than a predetermined value at any time, that is, when the current boost pressure is close to the target boost pressure, the accumulated time is initialized to 0 (S400) Exit the routine.

  As a result of the above process, in the fourth diagnosis process, there is a state where the deviation ΔP between the target boost pressure and the current boost pressure is larger than a predetermined value under the condition that the drive signal to the intake air switching valve 9 is OFF. When it continues beyond the predetermined time (S380), the relief valve closed sticking flag is turned on (S390). The transition of the supercharging pressure at this time will be described with reference to FIG. 7. When the relief valve 11 operates normally, the exhaust gas switching valve 8 is opened at the time (t0) when the operation region of the sub turbocharger is entered. Accordingly, the sub turbocharger 4 operates accordingly, the pressure on the downstream side of the compressor 4b rises, and the relief valve 11 opens (t1). Then, after a predetermined delay time from the opening operation of the exhaust control valve 12, the intake switching valve drive signal is turned on (t2), and the intake switching valve 9 is opened. Thus, the temporary opening operation of the relief valve 11 alleviates or suppresses the decrease in the supercharging pressure based on t2, thereby reducing the shock. The above is the change in the normal supercharging pressure.

  On the other hand, when the relief valve 11 is closed and fixed, there is no temporary opening operation of the relief valve 11, so that a drop in the supercharging pressure based on t2 occurs as shown by the broken line d. A deviation occurs from the target supercharging pressure (normal supercharging pressure) (region B surrounded by an ellipse). Therefore, by detecting such a characteristic transition based on the value of the deviation ΔP, it becomes possible to further detect the sticking of the relief valve 11.

  Next, the fifth diagnosis process in the present embodiment will be described. The fifth diagnosis process shown in FIG. 8 determines whether or not the relief valve 11 is closed and fixed based on the amount of change in supercharging pressure per time after the opening operation instruction to the intake air switching valve 9 is given. Is. The fifth diagnostic process may be performed in parallel or in series with the fourth diagnostic process, or may be performed instead of the fourth diagnostic process.

  In FIG. 8, first, the ECU 20 determines whether or not the drive signal to the intake air switching valve 9 is ON (S410). This drive signal is an instruction signal for individually opening the intake switching valve 9, and ON corresponds to opening.

  If the determination in step S410 is affirmative, the ECU 20 next detects the current boost pressure from the boost pressure sensor 31 (S420), and detects a deviation dP obtained by subtracting the current value from the previous value of the boost pressure. A differential value dP / dt divided by a minute time dt (for example, 0.1 second) as an interval is calculated (S430).

  Next, the ECU 20 determines whether or not the differential value dP / dt is larger than a predetermined value (S440). If the result is affirmative, that is, the amount of change in supercharging pressure per hour is large, and the supercharging pressure rapidly increases. If so, the predetermined relief valve closed sticking flag is turned on (S450). Further, when the differential value dP / dt is equal to or smaller than the predetermined value, that is, when the change amount of the current supercharging pressure per time is close to the normal time, step S450 is skipped.

  The processes in steps S420 to S450 are repeatedly executed until a predetermined time elapses after the intake switching valve drive signal is turned on (S460), and the present routine is exited on the condition that the predetermined time elapses.

  As a result of the above processing, in the fifth diagnosis processing, when the amount of change in the supercharging pressure is large and the supercharging pressure has increased rapidly after the drive signal to the intake air switching valve 9 is turned on. Then, a predetermined relief valve closed adhering flag is turned on (S450). The transition of the supercharging pressure at this time will be described with reference to FIG. 7. When the relief valve 11 is closed and fixed, there is no temporary opening operation of the relief valve 11. When the intake pressure switching valve 9 is opened at the time t2, the supercharging pressure suddenly increases (region C surrounded by an ellipse. The sudden increase in torque accompanying this causes a shock). Therefore, by detecting such a characteristic transition based on the value of the differential value dP / dt, it is possible to further appropriately detect the sticking of the relief valve 1.

  The open sticking / close sticking flag set in various diagnostic processes in the above embodiment is referred to as appropriate in other control processes. For example, when each flag is set, supercharging pressure control is prohibited. The failure information may be displayed on the display in the passenger compartment by referring to each flag. Further, each open sticking / close sticking flag is stored as a failure history in a predetermined diagnosis memory of the ECU 20, and is output to a maintenance worker during maintenance.

  In the above embodiment, an example in which various diagnostic processes are executed in parallel has been described. However, at least one of the various diagnostic processes in the present invention may be executed, and a plurality of arbitrary combinations may be combined. May be executed. In the above embodiment, the abnormal threshold values T1 to T5, which are reference values, are fixed values. However, any one of the abnormal threshold values T1 to T5 and other reference values may be set to an operating state (for example, required load ) May be changed dynamically according to

  Further, in the above embodiment, when the time when the supercharging pressure, the deviation or the differential value is abnormal exceeds a predetermined reference time, it is determined as abnormal, but instead of such a configuration, the supercharging pressure, deviation or An abnormality may be determined based on a comparison between an integrated value of deviation between the differential value and the predetermined value and a predetermined reference value (for example, an abnormality is determined when the integrated value exceeds the reference value). In this case, it is possible to make an appropriate abnormality determination according to the magnitude of the deviation. Further, in the above embodiment, the presence or absence of abnormality or failure is detected in a binary manner, but the degree of abnormality or failure may be detected in a multistage or stepless manner.

  Moreover, in the said embodiment, since various diagnoses were performed based on the supercharging pressure detected on the downstream side of the intake switching valve 9, the output of the supercharging pressure sensor 31 for detecting the supercharging pressure can be used. Although there is an advantage, in the present invention, the behavior of the supercharging pressure resulting from the operation of the relief valve 11 can be detected upstream of the intake air switching valve.

  In the above embodiment, an example in which the present invention is applied to a diesel engine has been described. However, the engine in the present invention can be applied to various types of internal combustion engines such as a gasoline engine and a gas fuel engine. It belongs to the category of the present invention.

It is a functional block diagram which shows the control apparatus of the engine with a supercharger which concerns on embodiment of this invention. It is a flowchart which shows the 1st diagnostic process in embodiment of this invention. FIG. 6 is a timing chart showing the transition of the supercharging pressure when normal and when the intake switching valve is stuck closed and opened. It is a flowchart which shows the 2nd diagnostic process in embodiment of this invention. It is a flowchart which shows the 3rd diagnostic process in embodiment of this invention. It is a flowchart which shows the 4th diagnostic process in embodiment of this invention. It is a timing diagram which shows transition of a supercharging pressure about the time of a normal time, and the case where a relief valve adheres closed. It is a flowchart which shows the 5th diagnostic process in embodiment of this invention. It is a functional block diagram which shows the control apparatus of the conventional supercharged engine.

Explanation of symbols

2 Engine body 3 Main turbocharger 4 Sub turbocharger 5 Exhaust passage 7 Intake passage 8 Exhaust switching valve 9 Intake switching valve 10 Bypass passage 11 Relief valve 31 Intake pressure sensor 20 ECU

Claims (8)

A main turbocharger, a sub turbocharger, an intake switching valve that opens and closes an intake passage downstream of the compressor of the sub turbocharger, a bypass passage that bypasses upstream and downstream of the intake switching valve in the intake passage, and the bypass A relief valve that is provided in a passage and opens when the pressure downstream of the compressor of the auxiliary turbocharger is higher than the pressure downstream of the compressor of the main turbocharger. A turbocharger that supercharges only the main turbocharger by closing the intake switching valve and supercharges both turbochargers by opening the intake switching valve in the high intake air amount range In the control device of the attached engine,
A supercharging pressure sensor that detects a supercharging pressure downstream of the intake air switching valve;
Switching valve adhesion determining means for determining whether or not the intake switching valve is closed and fixed based on the behavior of the supercharging pressure resulting from the operation of the relief valve; Control device for engine with a feeder. It is a control apparatus of the engine with a supercharger of Claim 1, Comprising:
The switching valve adhering determination means determines that the intake switching valve is adhering closed when there is a temporary decrease in the supercharging pressure after instructing the opening operation to the intake switching valve. A control device for a supercharged engine. A control device for a supercharged engine according to claim 1 or 2,
The switching valve adhering determination means is configured to close the intake switching valve based on a deviation between the supercharging pressure after the opening operation instruction to the intake switching valve and a predetermined normal 2-turbo supercharging pressure. A control device for an engine with a supercharger, characterized by determining whether or not A control device for a supercharged engine according to any one of claims 1 to 3,
The switching valve sticking determination means is configured to open and stick the intake switching valve based on a deviation between the supercharging pressure and a predetermined normal time turbo boost pressure before instructing the opening operation to the intake switching valve. A control device for an engine with a supercharger, characterized by determining whether or not A control device for a supercharged engine according to claim 3 or 4,
The supercharger-equipped engine control device, wherein the switching valve adhering determination means performs the determination based on a comparison between an integrated value of the deviation and a predetermined reference value. A main turbocharger, a sub turbocharger, an intake switching valve that opens and closes an intake passage downstream of the compressor of the sub turbocharger, a bypass passage that bypasses upstream and downstream of the intake switching valve in the intake passage, and the bypass A relief valve that is provided in a passage and opens when the pressure downstream of the compressor of the auxiliary turbocharger is higher than the pressure downstream of the compressor of the main turbocharger. A turbocharger that supercharges only the main turbocharger by closing the intake switching valve and supercharges both turbochargers by opening the intake switching valve in the high intake air amount range In the control device of the attached engine,
A supercharging pressure sensor that detects a supercharging pressure downstream of the intake air switching valve;
The relief valve is closed when the auxiliary turbocharger is in a supercharging operation and there is no behavior of the supercharging pressure due to the operation of the relief valve before an instruction to open the intake switching valve. A control device for an engine with a supercharger, further comprising: a relief valve adhering determining unit that determines that the adhering unit is adhering. It is a control apparatus of the engine with a supercharger of Claim 6, Comprising:
The relief valve adhering determination means performs the determination based on a comparison between an integrated value of a deviation between the supercharging pressure and a predetermined normal-time supercharging pressure and a predetermined reference value. A control device for a supercharged engine. A main turbocharger, a sub turbocharger, an intake switching valve that opens and closes an intake passage downstream of the compressor of the sub turbocharger, a bypass passage that bypasses upstream and downstream of the intake switching valve in the intake passage, and the bypass A relief valve that is provided in a passage and opens when the pressure downstream of the compressor of the auxiliary turbocharger is higher than the pressure downstream of the compressor of the main turbocharger. A turbocharger that supercharges only the main turbocharger by closing the intake switching valve and supercharges both turbochargers by opening the intake switching valve in the high intake air amount range In the control device of the attached engine,
A supercharging pressure sensor that detects a supercharging pressure downstream of the intake air switching valve;
It is determined that the relief valve is closed and fixed based on the amount of change of the supercharging pressure per time after the sub turbocharger is in supercharging operation and after the opening operation instruction to the intake switching valve A control device for the supercharged engine, further comprising: a relief valve adhering determination means.

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