JP2007056843A - Abnormality determination device for supercharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique capable of determining an abnormality of a waste gate valve before the rotational speed of a turbine exceeds an allowable range in a device for determining the abnormality of the waste gate valve installed in a centrifugal supercharger. <P>SOLUTION: An internal combustion engine comprises an exhaust side bypass path allowing the upstream side of the turbine of the centrifugal supercharger to communicate with the downstream side of the turbine in the exhaust path of the internal combustion engine and the waste gate valve installed in the exhaust side bypass path, In the internal combustion engine, An abnormality determination device determines the abnormality of the waste gate valve with the rotational speed of the turbine when the internal combustion engine is brought into a low rotation/low load operating state used as a parameter. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technique for determining an abnormality of a centrifugal supercharger (turbocharger) attached to an internal combustion engine.

An exhaust system of an internal combustion engine provided with a centrifugal supercharger (turbocharger) is provided with a bypass passage that bypasses the turbine, a wastegate valve that opens and closes the bypass passage, and the like. In such a configuration, a technique for determining an abnormality of the wastegate valve based on the supercharging pressure (intake pressure downstream of the compressor) has been proposed (for example, see Patent Document 1).
JP 7-293302 A JP-A-8-4543 No. 5-11316

  By the way, the abnormality of the wastegate valve is reflected in the supercharging pressure because the internal combustion engine load is in a relatively high operating region, so when the malfunction of the wastegate valve is determined during such high load operation, At that time, the number of turbines may have already exceeded the allowable range.

  The present invention has been made in view of the various circumstances as described above, and an object of the present invention is to provide an apparatus for determining an abnormality of a wastegate valve provided in the centrifugal supercharger, in which the turbine rotational speed is within an allowable range. It is to provide a technology that can determine the abnormality of the wastegate valve before crossing.

  In order to solve the above-described problems, the present invention avoids the turbine rotational speed from deviating from the allowable range by determining abnormality of the wastegate valve when the load of the internal combustion engine is low.

  In detail, the abnormality determination device for a supercharger according to the present invention is provided in an exhaust side bypass passage for communicating a turbine upstream and a turbine downstream of a centrifugal supercharger in an exhaust passage of an internal combustion engine, and the exhaust side bypass passage. A wastegate valve, and a judging means for judging an abnormality of the wastegate valve when the load of the internal combustion engine is equal to or lower than a predetermined load.

  According to the abnormality determination device for a supercharger configured in this way, the abnormality of the wastegate valve is determined at the time of low load operation before the internal combustion engine is operated at high load. It is possible to determine the abnormality of the wastegate valve before starting.

  By the way, when the load of the internal combustion engine is low, the opening degree of the wastegate valve is difficult to be reflected in the supercharging pressure or the exhaust pressure. Therefore, the determination method using the supercharging pressure as a parameter as in the prior art makes accurate abnormality determination. Difficult to do.

  On the other hand, the inventors of the present application have conducted extensive experiments and verifications. As a result, when the opening of the wastegate valve changes normally when the load on the internal combustion engine is low, the turbine speed changes with high sensitivity. I found it.

Therefore, in the abnormality determination device for a supercharger according to the present invention, the determination means acquires the amount of change in turbine speed when control is performed to change the opening of the wastegate valve, and the amount of change acquired If is less than the reference amount, it may be determined that the wastegate valve is abnormal.

  According to such a configuration, it is possible to accurately determine the abnormality of the wastegate valve using the turbine speed as a parameter even in a low load operation region in which the opening degree of the wastegate valve is not easily reflected in the supercharging pressure or the exhaust pressure. it can.

  In addition, when the load on the internal combustion engine is low, even if the opening degree of the wastegate valve is changed, there is little change in the boost pressure or exhaust pressure, so the influence of abnormality determination on the operating state of the internal combustion engine can be reduced. it can. Therefore, it is possible to determine the abnormality of the wastegate valve without making the driver of the internal combustion engine aware of it.

  Note that an intake side bypass passage that communicates the compressor downstream and the compressor upstream of the centrifugal supercharger and an air bypass valve that opens and closes the intake side bypass passage are disposed in the intake passage of the internal combustion engine including the centrifugal supercharger. There is a case.

  In such a case, an abnormality determination of the air bypass valve is required in addition to the abnormality determination of the wastegate valve. When an abnormality occurs in the air bypass valve, the supercharging pressure when the internal combustion engine is in a high load operation state deviates from a predetermined range. However, the supercharging pressure when the internal combustion engine is in a high-load operation state varies depending on the abnormality of the wastegate valve in addition to the abnormality of the air bypass valve. For this reason, it is difficult to specify that the air bypass valve is abnormal only under the condition that the supercharging pressure during high-load operation deviates from a predetermined range.

  On the other hand, in the abnormality determination device for a supercharger according to the present invention, when the internal combustion engine is operated at a high load after it is determined that the wastegate valve is normal, the intake pressure ( If the (supercharging pressure) deviates from a predetermined range, it may be determined that the air bypass valve is abnormal.

  According to such a configuration, it is possible to specify that the abnormality of the supercharging pressure when the internal combustion engine is operated at a high load is caused by the abnormality of the air bypass valve.

  According to the present invention, it is possible to determine the abnormality of the wastegate valve when the load of the internal combustion engine is low. Therefore, the abnormality of the wastegate valve can be detected before the turbine rotation speed exceeds the allowable range.

  Hereinafter, specific embodiments of the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine to which the present invention is applied. In FIG. 1, an internal combustion engine 1 is an in-line multi-cylinder engine having a plurality of cylinders 2.

  An exhaust passage 3 and an intake passage 4 are connected to the internal combustion engine 1. A turbine housing 50 of a centrifugal supercharger (turbocharger) 5 is disposed in the middle of the exhaust passage 3. In the exhaust passage 3, the upstream portion and the downstream portion of the turbine housing 50 communicate with each other through the exhaust-side bypass passage 30. A waste gate valve 31 is disposed in the middle of the exhaust side bypass passage 30.

Next, a compressor housing 51 of a centrifugal supercharger (turbocharger) 5 is disposed in the intake passage 4. In the intake passage 4, the upstream portion and the downstream portion of the compressor housing 51 communicate with each other through the intake side bypass passage 40. An air bypass valve 41 is disposed in the intake side bypass passage 40.

  The centrifugal supercharger (turbocharger) 5 is provided with a rotational speed sensor 52 that detects the rotational speed of the turbine wheel 500. At this time, if the rotational speed sensor 52 is attached to the turbine housing 50, it is necessary to improve the heat resistance of the rotational speed sensor 52, which may increase costs. Therefore, the rotational speed sensor 52 may be attached to the bearing portion 53 of the shaft 502 that connects the turbine wheel 500 and the compressor wheel 501 to detect the rotational speed of the shaft 502.

  An intercooler 6 is disposed downstream of the compressor housing 51 in the intake passage 4. A throttle valve 7 is disposed in the intake passage 4 downstream from the intercooler 6. An intake pressure sensor 11 is attached to the intake passage 4 downstream of the throttle valve 7.

  The internal combustion engine 1 is also provided with an ECU 8. The ECU 8 controls the throttle valve 7, the wastegate valve 31, and the air bypass valve 41 based on output signals from various sensors such as the crank position sensor 9, the accelerator position sensor 10, the intake pressure sensor 11, and the rotation speed sensor 52. Then, abnormality determination processing of the wastegate valve 31 and abnormality determination processing of the air bypass valve 41 are executed.

  Hereinafter, abnormality determination processing of the wastegate valve 31 and the air bypass valve 41 will be described with reference to FIGS. 2 and 3. FIG. 2 is a flowchart showing an abnormality determination routine for the wastegate valve 31, and FIG. 3 is a flowchart showing an abnormality determination routine for the air bypass valve 41.

  First, in the abnormality determination routine of FIG. 2, the ECU 8 reads the engine speed Ne calculated based on the output signal of the crank position sensor 9 and the output signal (Accp) of the accelerator position sensor 10 in S101.

  In S102, the ECU 8 determines whether or not the internal combustion engine 1 is in a low speed / low load operation state, that is, the engine speed Ne is equal to or lower than the predetermined speed Nes, and the accelerator opening Accp is equal to or lower than the predetermined opening Acps. It is determined whether or not.

  The predetermined rotation speed Nes and the predetermined opening degree Acps are determined within a range in which the supercharging pressure and the exhaust pressure hardly change even when the opening degree of the waste gate valve 31 is changed when the waste gate valve 31 is normal. It is a value and is a value obtained experimentally in advance.

  If a negative determination is made in S102, the ECU 8 ends the execution of this routine. On the other hand, if an affirmative determination is made in S102, the ECU 8 proceeds to S103 and controls the wastegate valve 31 to be fully closed.

  In S103, the ECU 8 reads the output signal (turbine rotational speed) Nt1 of the rotational speed sensor 52. Since the response delay occurs until the wastegate valve 31 is actually fully closed after the control of S102 is performed, the ECU 8 detects the rotational speed sensor after the response delay time has elapsed from the end of the execution of S102. Preferably, 52 output signals are read.

In S104, the ECU 8 determines whether or not the turbine rotational speed Nt1 read in S103 is equal to or higher than a predetermined rotational speed Nts1. The predetermined rotational speed Nts1 is a value corresponding to the turbine rotational speed when the wastegate valve 31 is normally fully closed, and is a value obtained experimentally in advance.

  If an affirmative determination is made in S104 (Nt1 ≧ Nts1), the ECU 8 proceeds to S106 and controls the wastegate valve 31 to be fully opened.

  In S107, the ECU 8 reads an output signal (turbine rotational speed) Nt2 of the rotational speed sensor 52. Also in this case, since a response delay occurs until the wastegate valve 31 is actually fully opened after the control of S106 is performed, the ECU 8 performs the rotation speed after the response delay time has elapsed from the end of the execution of S106. Assume that the output signal of the sensor 52 is read.

  In S108, the ECU 8 determines whether or not the turbine rotational speed Nt2 read in S107 is equal to or higher than a predetermined rotational speed Nts2. The predetermined rotation speed Nts2 is a value corresponding to the turbine rotation speed when the wastegate valve 31 is normally fully opened, and is a value obtained experimentally in advance.

  If an affirmative determination is made in S108 (Nt2 ≦ Nts2), the ECU 8 proceeds to S109 and determines that the wastegate valve 31 is normal.

  On the other hand, if a negative determination is made in S105 (Nt1 <Nts1) or a negative determination in S108 (Nt2> Nts2), the ECU 8 proceeds to S110 and determines that the wastegate valve 31 is abnormal. .

  As described above, the ECU 8 executes the abnormality determination routine shown in FIG. 2, whereby it is possible to determine the abnormality of the wastegate valve 31 when the internal combustion engine 1 is in the low rotation / low load operation state. For this reason, it is possible to avoid the internal combustion engine 1 from being operated at a high speed and a high load in a state where the abnormality occurs in the wastegate valve 31, and the turbine rotational speed may exceed an allowable range. It can be avoided.

  Furthermore, when the wastegate valve 31 is forcibly controlled to be fully open and fully closed, the turbine rotational speed changes with high sensitivity, but the supercharging pressure and exhaust pressure hardly change. A decrease in drivability can also be suppressed.

  FIG. 4 shows the turbine rotation when the normal wastegate valve 31 is operated from fully closed to fully open under the condition that the engine speed Ne is equal to or lower than the predetermined speed Nes and the accelerator opening degree Accp is equal to or lower than the predetermined opening degree Acps. It is a figure which shows the result of having measured several Nt, supercharging pressure Pt, and exhaust pressure (exhaust pressure upstream from the turbine housing 50).

  As shown in FIG. 4, when the wastegate valve 31 operates from fully closed to fully opened when the engine speed Ne is equal to or less than the predetermined speed Nes and the accelerator opening degree Accp is equal to or less than the predetermined opening degree Acps, the turbine speed Nt is greatly increased. However, the amount of decrease in the supercharging pressure Pt and the exhaust pressure is extremely small.

  Therefore, according to the abnormality determination method of the present embodiment, when the internal combustion engine 1 is in the low rotation / low load operation state, the wastegate valve 31 while suppressing a decrease in drivability (a change in supercharging pressure or exhaust pressure). Can be accurately determined.

In the above-described abnormality determination routine of FIG. 2, when the turbine rotational speed Nt1 when the wastegate valve 31 is controlled to be fully open is equal to or higher than the predetermined rotational speed Nts1, and the wastegate valve 31 is controlled to be fully closed. It is determined that the wastegate valve 31 is normal on the condition that the turbine rotational speed Nt2 is equal to or less than the predetermined rotational speed Nts2. However, the turbine rotational speed Nt1 and the wastewater when the wastegate valve 31 is controlled to fully open The waste gate valve 31 may be determined to be normal on the condition that the difference from the turbine rotational speed Nt2 when the gate valve 31 is controlled to be fully closed is a predetermined amount or more.

  Next, in the abnormality determination routine of FIG. 3, the ECU 8 reads the engine speed Ne calculated based on the output signal of the crank position sensor 9 and the output signal (Accp) of the accelerator position sensor 10 in S201.

  In S202, the ECU 8 determines whether or not the internal combustion engine 1 is in a high speed / high load operation state, that is, the engine speed Ne is equal to or higher than the predetermined speed Net and the accelerator opening degree Accp is equal to or higher than the predetermined opening degree Acpt. It is determined whether or not.

  The predetermined rotational speed Net and the predetermined opening degree Acpt are values determined within a range in which the opening degree of the air bypass valve 41 is highly sensitive and reflected in the supercharging pressure, and are values obtained experimentally in advance. is there.

  If a negative determination is made in S202, the ECU 8 ends the execution of this routine. On the other hand, if an affirmative determination is made in S202, the ECU 8 proceeds to S203, and determines whether or not the wastegate valve 31 is determined to be normal in the abnormality determination routine of FIG.

  If a negative determination is made in S203, the ECU 8 ends the execution of this routine. On the other hand, if an affirmative determination is made in S203, the ECU 8 proceeds to S204 and reads the output signal (supercharging pressure) Pt of the intake pressure sensor 11.

  In S205, the ECU 8 determines whether or not the supercharging pressure Pt read in S204 is a value within a predetermined range. The predetermined range is a range of values that can be taken by the supercharging pressure when both the wastegate valve 31 and the air bypass valve 41 are normal, and has been experimentally obtained in advance. Since the supercharging pressure when the wastegate valve 31 and the air bypass valve 41 are normal changes according to the accelerator opening degree Accp and the engine speed Ne, the supercharging pressure, the accelerator opening degree Accp, and the engine speed are changed. The relationship with Ne may be mapped in advance.

  If an affirmative determination is made in S205, the ECU 8 proceeds to S206, determines that the air bypass valve 41 is normal, and ends the execution of this routine. On the other hand, if a negative determination is made in S205, the ECU 8 proceeds to S207, determines that the air bypass valve 41 is abnormal, and ends the execution of this routine.

  According to the abnormality determination routine of FIG. 3, in order to determine the abnormality of the air bypass valve 41 using the supercharging pressure Pt at the time of high rotation / high load operation after determining that the wastegate valve is normal as a parameter, It becomes possible to accurately determine the abnormality of the bypass valve 41.

1 is a diagram showing a schematic configuration of an internal combustion engine to which the present invention is applied. It is a flowchart which shows the abnormality determination routine of a waste gate valve. It is a flowchart which shows the abnormality determination routine of an air bypass valve. It is a figure which shows the behavior of a turbine speed, a supercharging pressure, and an exhaust pressure at the time of operating a wastegate valve from a fully closed state to a fully open state at the time of low rotation and low load operation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Cylinder 3 ... Exhaust passage 4 ... Intake passage 5 ... Centrifugal supercharger (turbocharger)
8 ... ECU
DESCRIPTION OF SYMBOLS 11 .... Intake pressure sensor 30 ... Exhaust side bypass passage 31 ... West gate valve 40 ... Intake side bypass passage 41 ... Air bypass valve 50 ... Turbine housing 51 .... Compressor housing 52 ... Rotational speed sensor

Claims (3)

An exhaust-side bypass passage that connects the turbine upstream and downstream of the centrifugal supercharger in the exhaust passage of the internal combustion engine;
A wastegate valve provided in the exhaust-side bypass passage;
When the load of the internal combustion engine is equal to or less than a predetermined load, determination means for determining an abnormality of the wastegate valve;
An abnormality determination device for a supercharger comprising:   In Claim 1, the said determination means acquires the variation | change_quantity of the turbine speed when performing control to change the opening degree of the said wastegate valve, and if the acquired variation | change_quantity is less than a reference amount, the said A supercharger abnormality determination device characterized by determining that a wastegate valve is abnormal. In Claim 1 or 2, in the intake passage of the internal combustion engine, an intake side bypass passage communicating the compressor downstream and the compressor upstream of the centrifugal supercharger,
An air bypass valve provided in the intake side bypass passage,
When the internal combustion engine is operated at a high load after it is determined that the wastegate valve is normal, the determination means is the air bypass valve if the intake pressure downstream of the compressor deviates from a predetermined range. Is determined to be abnormal, a supercharger abnormality determination device.

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