JP2006291814A - Abnormality determining device for turbocharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an abnormality determining device for a turbocharger for accurately determining the abnormality of a turbocharging pressure changing mechanism. <P>SOLUTION: When a difference between target turbocharging pressure PINT and target turbocharging pressure PINT0 before routine is greater than a preset value [-γ] (Step S100) and a difference between actual turbocharging pressure PIN and actual turbocharging pressure PIN0 before routine is greater than a preset value [-δ] (Step S110), whether a difference between the target turbocharging pressure PINT and the actual turbocharging pressure PIN is smaller than a preset value [-α] or not is determined (Step S120). Thus, such abnormality that the actual turbocharging pressure of the turbocharger is excessively higher is accurately determined. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an abnormality determination device for a turbocharger mounted on an internal combustion engine.

  2. Description of the Related Art Conventionally, a turbocharger using exhaust pressure is widely known as a supercharging system that enhances charging efficiency by forcibly feeding intake air into a combustion chamber. In such a turbocharger, it is desirable to appropriately adjust the supercharging pressure according to the operating state of the internal combustion engine. Therefore, a variable nozzle that changes the cross-sectional area of the passage that supplies exhaust to the turbine wheel is provided, and the flow rate and flow velocity of the exhaust gas blown to the turbine wheel is adjusted by adjusting the opening of the variable nozzle, and the boost pressure Turbochargers that have been changed have been put into practical use.

  In such a turbocharger, the opening degree of the variable nozzle is changed so that the target boost pressure set based on the engine operating state matches the actual boost pressure. As a result, the actual supercharging pressure of the turbocharger can be changed to a pressure commensurate with the engine operating state.

By the way, in a turbocharger equipped with such a supercharging pressure changing mechanism, when the supercharging pressure changing function is lowered due to, for example, a variable nozzle being fixed, the supercharging pressure can be appropriately controlled according to the engine operating state. Disappear. Therefore, the degree of deviation between the target supercharging pressure and the actual supercharging pressure is monitored, and if the deviation becomes large, it is determined that there is an abnormality in the turbocharger's supercharging pressure changing mechanism, and the abnormality is dealt with. I have to. In addition, Patent Document 1 proposes a method for determining such an abnormality of the turbocharger.
Japanese Patent Laid-Open No. 10-196381

  By the way, when the abnormality is simply determined based on the degree of deviation between the target boost pressure and the actual boost pressure, the following inconvenience may occur. In other words, when the target boost pressure changes greatly with changes in the engine operating state, the actual boost pressure immediately follows the change in the target boost pressure due to a response delay of the boost pressure change mechanism. There are things you can't do. For this reason, even if there is no abnormality in the supercharging pressure changing mechanism and the actual supercharging pressure converges to the target supercharging pressure after that, such a temporary divergence has occurred. It may be erroneously determined that there is an abnormality in the turbocharger. In order to avoid such an erroneous determination, for example, it may be considered that the abnormality determination is performed when a state in which a deviation occurs between the actual boost pressure and the target boost pressure continues for a predetermined period. However, the time until the actual supercharging pressure converges to the target supercharging pressure varies depending on the amount of change in the target supercharging pressure, changes over time in the response of the supercharging pressure change mechanism, etc. In view of this, the predetermined period must be set longer. Therefore, when an abnormality actually occurs in the supercharging pressure changing mechanism, the abnormality determination may be delayed. In particular, when there is a situation where the actual supercharging pressure greatly exceeds the target supercharging pressure due to an abnormality in the supercharging pressure changing mechanism, knocking due to excessive engine compression ratio or exhaust pressure increase This will cause damage to the exhaust system members.

  The present invention has been made in view of such conventional circumstances, and an object thereof is to provide a turbocharger abnormality determination device capable of accurately determining abnormality of a supercharging pressure changing mechanism.

  In order to achieve the above object, the invention according to claim 1 is directed to a turbocharger including a supercharging pressure changing mechanism capable of changing a supercharging pressure in accordance with an engine operating state. In the abnormality determination device that performs abnormality determination based on the degree of divergence, when the change speed of at least one of the target supercharging pressure and the actual supercharging pressure is relatively large, the abnormality is determined so that it is difficult to determine that there is an abnormality. The mode of determination is changed.

  When the turbocharger abnormality is judged based on the degree of deviation between the target boost pressure and the actual boost pressure, the target boost pressure changes according to the engine operating condition, and the response delay of the boost pressure change mechanism If the difference between the target supercharging pressure and the actual supercharging pressure temporarily increases due to the actual supercharging pressure changing with a delay from the target supercharging pressure, etc., this is abnormal. There is a concern of misjudgment.

  In this regard, according to the configuration of the first aspect, when the change speed of at least one of the target supercharging pressure and the actual supercharging pressure is relatively large, the abnormality determination is performed so that it is difficult to determine that the abnormality is abnormal. Since the aspect is changed, it is possible to suppress an erroneous determination as much as possible due to the temporary divergence between the transient target boost pressure and the actual boost pressure.

  In the above configuration, only one of the target boost pressure and the actual boost pressure is monitored, and the determination mode is changed so that it is difficult to determine that it is abnormal when the rate of change is relatively large. However, in order to appropriately suppress the erroneous determination, it is desirable to monitor both the supercharging pressures and to consider one or both of the changing speeds. Further, in this case, the determination mode can be changed so that it is easy to determine that an abnormality is present when the change speed of either the target supercharging pressure or the actual supercharging pressure is relatively small.

  Further, as a specific example of setting the abnormality determination mode so that it is difficult to determine that it is abnormal, for example, when the deviation between the target boost pressure and the actual boost pressure is equal to or greater than a predetermined determination value When it is determined that there is an abnormality, when the change speed of at least one of the target boost pressure and the actual boost pressure is relatively large, the determination value is set to a relatively large value, while the above change When the speed is relatively small, a configuration in which the determination value is set to a relatively small value can be employed. Further, in addition to the configuration in which the determination value is changed in accordance with the change speed as described above, the change speed of at least one of the target supercharging pressure and the actual supercharging pressure is not less than a predetermined value as in the invention described in claim 2 In such a case, it is possible to adopt a configuration in which the abnormality determination itself is prohibited.

  According to a third aspect of the present invention, in the turbocharger abnormality determination device according to the first or second aspect, when the target supercharging pressure decreases, the abnormality only occurs when the rate of decrease is equal to or greater than a predetermined value. The mode of determination is changed. According to this configuration, when the target supercharging pressure rapidly decreases and the deviation between the target supercharging pressure and the actual supercharging pressure temporarily increases, it is erroneously determined that there is an abnormality in the turbocharger. Can be suppressed as much as possible.

  According to a fourth aspect of the present invention, in the turbocharger abnormality determination device according to any one of the first to third aspects, when the actual supercharging pressure decreases, the rate of decrease is equal to or greater than a predetermined value. Only in this case, the abnormality determination mode is changed.

  According to this configuration, even when the actual supercharging pressure is converging to the target supercharging pressure, the turbocharger is inconsistent between the actual supercharging pressure and the target supercharging pressure. Can be prevented as much as possible from being erroneously determined that there is an abnormality.

  According to a fifth aspect of the present invention, in the turbocharger abnormality determination device according to the third or fourth aspect, it is determined that the abnormality is abnormal on the condition that the actual supercharging pressure exceeds the target supercharging pressure. I am doing so.

  According to this configuration, if there is a temporary divergence between the two in a situation where the target boost pressure has decreased and the actual boost pressure has decreased following this, it is abnormal. However, if the target boost pressure rises when an abnormality occurs in the boost pressure change mechanism and the actual boost pressure rises above the target boost pressure, This can be quickly determined as abnormal. Therefore, it is possible to suppress the occurrence of adverse effects such as knocking due to excessive engine compression ratio due to excessive supercharging, damage to exhaust system members due to an increase in exhaust pressure, and the like.

  According to a sixth aspect of the present invention, in the turbocharger abnormality determination device according to any one of the first to fifth aspects, the state in which the target boost pressure and the actual boost pressure have deviated continues for a predetermined time. It is determined that it is abnormal on the condition that

  In this configuration, since it is determined that there is an abnormality on the condition that the state where the target supercharging pressure and the actual supercharging pressure have deviated for a predetermined time, the reliability of the abnormality determination result can be improved. become able to. In this configuration, the abnormality determination mode is changed so that it is difficult to determine that there is an abnormality when the change speed of at least one of the target boost pressure and the actual boost pressure is equal to or greater than a predetermined value. Therefore, it is not necessary to set the predetermined period unnecessarily long, and an abnormality in the supercharging pressure changing mechanism can be quickly determined.

Hereinafter, an embodiment of an abnormality determination device for a turbocharger embodying the present invention will be described with reference to FIGS.
FIG. 1 shows the configuration of a diesel engine equipped with a turbocharger. A piston 12 is provided in the cylinder block 11a of the diesel engine 11 so as to be able to reciprocate. The piston 12 is connected to a crankshaft 14 provided at the lower part of the diesel engine 11 via a connecting rod 13. The reciprocating motion of the piston 12 is converted into the rotational motion of the crankshaft 14 by the connecting rod 13. The cylinder block 11 a is provided with a crank position sensor 16 for detecting the rotation angle of the crankshaft 14.

  A cylinder head 17 is provided on the upper portion of the cylinder block 11a. A combustion chamber 18 is formed by a space surrounded by the bottom surface of the cylinder head 17 and the upper end surface of the piston 12. The cylinder head 17 is provided with a fuel injection nozzle 18 a for injecting fuel into the combustion chamber 18. Further, an intake port 19 and an exhaust port 20 are formed in the cylinder head 17 so as to communicate with the combustion chamber 18. The intake port 19 and the exhaust port 20 are provided with an intake valve 21 and an exhaust valve 22, respectively.

  An intake camshaft 23 and an exhaust camshaft 24 for opening and closing the intake valve 21 and the exhaust valve 22 are provided above the cylinder head 17. The intake / exhaust camshafts 23 and 24 are drivingly connected to the crankshaft 14 by a timing belt (not shown). The intake and exhaust valves 21 and 22 are driven to open and close by the rotation of the intake and exhaust camshafts 23 and 24, whereby the intake and exhaust ports 19 and 20 and the combustion chamber 18 are communicated and disconnected.

  An upstream portion of the intake passage 32 including the intake port 19 and the intake pipe 30 and a downstream portion of the exhaust passage 33 including the exhaust port 20 and the exhaust pipe 31 are connected to the turbocharger 35, respectively. The turbocharger 35 includes a compressor wheel 36 for pressurizing and discharging air to the downstream side of the intake passage 32, and a turbine wheel 37 that rotates by blowing exhaust gas that passes through the exhaust passage 33. The compressor wheel 36 and the turbine wheel 37 are connected by a rotor shaft 38, and the compressor wheel 36 and the turbine wheel 37 are configured to rotate integrally. A nozzle vane 41 as a supercharging pressure changing mechanism is provided in the upstream portion of the turbine wheel 37. The nozzle vane 41 is driven to open and close by the actuator 42 and has a configuration that can change the effective area of the passage from the exhaust passage 33 to the turbine wheel 37. Then, the flow rate / flow velocity of the exhaust gas blown to the turbine wheel 37 is adjusted by the opening / closing operation of the nozzle vane 41.

  Exhaust gas discharged from the combustion chamber 18 is blown to the turbine wheel 37 of the turbocharger 35 through the exhaust passage 33. The turbine wheel 37 is rotated by blowing the exhaust gas, and this rotation is transmitted to the compressor wheel 36 via the rotor shaft 38. When the compressor wheel 36 rotates, the air is pressurized and forced out toward the downstream side of the intake passage 32, and the amount of air taken into the combustion chamber 18 increases. At this time, the flow rate / flow velocity of the exhaust gas blown to the turbine wheel 37 can be adjusted by the opening / closing drive control of the nozzle vane 41, and the supercharging amount of the air sucked into the combustion chamber 18 can be adjusted.

  The drive shaft 61a of the fuel injection pump 61 is connected to the crankshaft 14 of the diesel engine 11 and is driven thereby. The fuel injection pump 61 is connected to the fuel injection nozzle 18 a via the fuel line 62. The fuel injection pump 61 sucks fuel from a fuel tank (not shown) and pressurizes and discharges this fuel toward the fuel injection nozzle 18a. The fuel injection nozzle 18 a is operated by the pressure of the fuel fed from the fuel injection pump 61 and injects the fuel into the combustion chamber 18. The fuel injection amount is adjusted by the electromagnetic spill valve 63, and the fuel discharge start timing is adjusted by the timer device 64. The fuel injection may be performed through a common rail fuel injection device.

  A pressure sensor 71 is provided in the intake passage 32. The pressure sensor 71 detects the pressure of air in the intake passage 32, that is, the supercharging pressure, and outputs a detection signal corresponding to the detected pressure to the ECU 91.

  The accelerator pedal 81 is provided with an accelerator sensor 81a that detects the amount of depression. The accelerator sensor 81a outputs a detection signal corresponding to the detected depression amount of the accelerator pedal 81 to the ECU 91.

The warning lamp 92 is provided in the driver's seat, and when it is determined that there is an abnormality in the turbocharger 35, it is turned on by the output of the ECU 91 and notifies the driver of the occurrence of the abnormality.
Next, control of the ECU 91 will be described. The ECU 91 obtains an engine speed NE and a crank angle based on detection signals from the crank position sensor 16 and a cam position sensor (not shown), and calculates an injection timing target value from the engine speed NE and the crank angle. The ECU 91 grasps the depression amount of the accelerator pedal 81 based on the detection signal from the accelerator sensor 81a, and calculates a command value for the fuel injection amount Q from the depression amount and the engine speed NE. Then, the ECU 91 drives and controls the electromagnetic spill valve 63 and the timer device 64 based on the calculated command value of the fuel injection amount Q and the injection timing target value. Further, the ECU 91 calculates a target value for the supercharging pressure by the turbocharger 35 according to the engine operating state. Then, the ECU 91 compares the target boost pressure PINT with the actual boost pressure PIN detected by the pressure sensor 71, and drives the actuator 42 so that the target boost pressure PINT and the actual boost pressure PIN match. The nozzle vane 41 is opened and closed.

  Next, the control of the abnormality determination device for the turbocharger 35 will be described. FIG. 2 shows a flowchart of an abnormality determination routine by the abnormality determination device. This abnormality determination routine determines an abnormality when the actual supercharging pressure PIN increases excessively with respect to the target supercharging pressure PINT, and the actual supercharging pressure PIN is converging on the target supercharging pressure PINT. This is to prevent erroneous determination in a transient state. Note that α, β, γ, and δ shown in the flowchart are values of 0 or more. The ECU 91 repeats the abnormality determination routine at every predetermined timing. When the abnormality determination routine is started, the ECU 91 determines whether or not the difference between the target boost pressure PINT and the target boost pressure PINT0 one routine before is greater than a predetermined value “−γ” (step S100). In this step, it is determined whether or not the amount of change in the target boost pressure PINT per routine, that is, the rate of decrease in the target boost pressure PINT is equal to or greater than a predetermined value. When the difference is equal to or smaller than the predetermined value “−γ”, this routine is finished as it is. When the rate of decrease in the target boost pressure PINT is equal to or greater than a predetermined value, there is a risk of erroneous determination that there is an abnormality because the deviation between the target boost pressure PINT and the actual boost pressure PIN has temporarily increased. Therefore, abnormality determination is not performed.

  When the difference is larger than the predetermined value “−γ”, it is determined whether or not the difference between the actual supercharging pressure PIN and the actual supercharging pressure PIN0 one routine before is larger than the predetermined value “−δ” (step S110). ). In this step, it is determined whether or not the amount of change in the actual boost pressure PIN per routine, that is, the rate of decrease in the actual boost pressure PIN is equal to or greater than a predetermined value. When the difference is equal to or smaller than the predetermined value “−δ”, this routine is finished as it is. When the decrease rate of the actual supercharging pressure PIN is equal to or higher than a predetermined value, the actual supercharging pressure PIN becomes the target supercharging pressure PINT even if there is a difference between the actual supercharging pressure PIN and the target supercharging pressure PINT. It can be determined that the situation is converging. For this reason, since there exists a possibility that it may be misjudged that there exists abnormality because the deviation has arisen between the actual supercharging pressure PIN and the target supercharging pressure PINT, abnormality determination is not performed.

  When the difference is larger than the predetermined value “−δ”, it is determined whether or not the difference between the target boost pressure PINT and the actual boost pressure PIN is smaller than the predetermined value “−α” (step S120). In this step, there is a divergence between the actual boost pressure PIN and the target boost pressure PINT. Specifically, whether or not the actual boost pressure PIN is greater than a predetermined value as compared with the target boost pressure PINT. Judging. When the difference is equal to or larger than the predetermined value “−α”, it is considered that the turbocharger 35 is operating normally, and this routine is finished as it is. This is because when the difference between the actual supercharging pressure PIN and the target supercharging pressure PINT is equal to or less than a predetermined value, there is less possibility of adverse effects such as damage to exhaust system members due to excessive supercharging.

  When the difference is smaller than the predetermined value “−α”, the counter of the abnormality determination routine is incremented by one routine (step S130). Then, it is determined whether or not the counter exceeds a predetermined value β (step S140). This step is to determine that there is an abnormality on the condition that the state where the target supercharging pressure PINT and the actual supercharging pressure PIN have deviated continues for a predetermined time, and to improve the reliability of the abnormality determination result. If the counter is equal to or smaller than the predetermined value β, the process returns to step S100, and the abnormality determination routine is repeated. When the counter exceeds the predetermined value β, the abnormality of the turbocharger 35 is determined, and the warning lamp 92 is turned on (step S150). In this way, when the abnormality occurs in the nozzle vane 41 and the like, the target supercharging pressure PINT increases, and the state where the actual supercharging pressure PIN increases beyond the target supercharging pressure PINT is determined as abnormal. it can.

  Next, the control of the abnormality determination routine when the actual boost pressure PIN rises above the target boost pressure PINT and an abnormality determination is made will be described using the time chart shown in FIG. FIG. 3A shows the time change between the target supercharging pressure PINT and the actual supercharging pressure PIN, and FIG. 3B shows the time change between the target supercharging pressure PINT and the actual supercharging pressure PIN. FIG. 3C shows the degree of divergence between the target boost pressure PINT and the actual boost pressure PIN, specifically the time change of the pressure difference between the two. Here, the target supercharging pressure change speed VPINT and the actual supercharging pressure change speed VPIN shown in FIG. 3 (b) are obtained by changing the target supercharging pressure PINT and the actual supercharging pressure PIN to one routine time rt of the abnormality determination routine, respectively. Differentiated by.

  If the target boost pressure PINT is set to increase at time t0 as shown in FIG. 3A, the actual boost pressure PIN also increases, and the target boost pressure change rate as shown in FIG. 3B. VPINT and actual boost pressure change rate VPIN are positive values. This state continues until time t1. During the period from t0 to t1, the target boost pressure change rate VPINT and the actual boost pressure change rate VPIN are positive values. Therefore, it is determined to be affirmative in steps S100 and S110 of the flowchart shown in FIG. Proceed to In step S120, the pressure difference between the target boost pressure PINT and the actual boost pressure PIN is determined. However, since there is almost no difference as shown in FIG. 3C, it is determined negative in step S120 and abnormal. The determination routine ends.

  As shown in FIG. 3A, when the target boost pressure PINT reaches a steady state at time t1, the target boost pressure change rate VPINT gradually approaches 0 as shown in FIG. Originally, the actual supercharging pressure PIN is controlled so as to coincide with the target supercharging pressure PINT, so that the actual supercharging pressure PIN also becomes a steady state, and the actual supercharging pressure change speed VPIN gradually approaches 0. Then, for reasons such as abnormality of the nozzle vane 41, the actual supercharging pressure PIN continues to increase as shown in FIG. When the actual boost pressure PIN continues to rise, as shown in FIG. 3C, the pressure difference between the target boost pressure PINT and the actual boost pressure PIN increases, and at time t2, the pressure difference becomes a predetermined value “−”. α ”is reached. During the period from t1 to t2, as in the period from t0 to t1, it is determined negative in step S120 and the abnormality determination routine ends. However, after the time t2, the target supercharging is performed as shown in FIG. The pressure difference between the pressure PINT and the actual supercharging pressure PIN becomes smaller than the predetermined value “−α”. For this reason, in the abnormality determination routine after time t2, the process proceeds to step S130 and step S140, and when the counter is incremented to become larger than the predetermined value β, that is, at time t3, the process proceeds to step S150 to display abnormality determination. The

  Next, when the target supercharging pressure PINT decreases, the target supercharging pressure PINT and the actual supercharging are in a transitional state where the actual supercharging pressure PIN tends to converge due to a response delay of the nozzle vane 41 or the like. The control of the abnormality determination routine in the case where a deviation from the pressure PIN occurs will be described using the time chart shown in FIG. FIG. 4A shows the time change between the target supercharging pressure PINT and the actual supercharging pressure PIN, and FIG. 4B shows the time change of the pressure change rate between the target supercharging pressure PINT and the actual supercharging pressure PIN. FIG. 4C shows the change over time in the pressure difference between the target boost pressure PINT and the actual boost pressure PIN. Here, the target supercharging pressure change speed VPINT and the actual supercharging pressure change speed VPIN shown in FIG. 4 (b) are obtained by changing the target supercharging pressure PINT and the actual supercharging pressure PIN to one routine time rt of the abnormality determination routine, respectively. Differentiated by.

  When the target boost pressure PINT is set to decrease at time t0 as shown in FIG. 4A, the actual boost pressure PIN also starts to decrease, and as shown in FIG. The change rate VPINT and the actual boost pressure change rate VPIN are negative values. The change in the actual supercharging pressure change speed VPIN is smaller than the change in the target supercharging pressure change speed VPINT due to the response delay of the nozzle vane 41 and the like. During the period from t0 to t2, the target boost pressure change speed VPINT is a value smaller than the predetermined value “−γ”, so that it is determined negative in step S100 of the flowchart shown in FIG. 2, and the abnormality determination routine ends. At time t1, the pressure difference between the target boost pressure PINT and the actual boost pressure PIN becomes smaller than the predetermined value “−α”. However, since the abnormality determination routine ends in step S100, no abnormality determination is made. .

  As shown in FIG. 4 (a), when the target boost pressure PINT reaches a steady state at time t2, the target boost pressure change rate VPINT gradually approaches 0 as shown in FIG. 4 (b). On the other hand, since the actual boost pressure PIN tends to converge to the target boost pressure PINT, it continues to decrease at time t2, and the actual boost pressure change rate VPIN also continues to decrease. During the period from t2 to t3, the target boost pressure change rate VPINT is larger than the predetermined value “−γ”, so that it is determined affirmative in step S100 of the flowchart shown in FIG. Since the supply pressure change speed VPIN is smaller than the predetermined value “−δ”, it is determined negative in step S110, and the abnormality determination routine ends. In this way, in a transient situation where the target boost pressure PINT decreases and the actual boost pressure PIN tends to converge, even if there is a divergence between the target boost pressure PINT and the actual boost pressure PIN. Control is performed so that abnormality determination is not performed.

According to the above embodiment, the following effects can be obtained.
(1) In the above embodiment, even if the pressure difference between the target boost pressure PINT and the actual boost pressure PIN is smaller than the predetermined value “−α”, the target corresponding to the decreasing speed of the target boost pressure PINT. When the supercharging pressure change speed VPINT is smaller than a predetermined value “−γ”, the abnormality determination is not performed. As a result, when the target boost pressure PINT is suddenly reduced, the pressure difference between the actual boost pressure PIN and the target boost pressure PINT is a predetermined value “−” under a transient condition where the actual boost pressure PIN is converged. Even if the value is smaller than “α”, the abnormality determination is not performed, so that erroneous determination can be suppressed.

  (2) In the above embodiment, even if the difference between the target boost pressure PINT and the actual boost pressure PIN is smaller than the predetermined value “−α”, the actual excess corresponding to the decrease rate of the actual boost pressure PIN. When the supply pressure change rate VPIN is smaller than the predetermined value “−δ”, it can be determined that the actual boost pressure PIN is in a direction of convergence with respect to the target boost pressure PINT, and thus no abnormality determination is performed. As a result, in a transient situation where the actual supercharging pressure PIN tends to converge, even if the difference between the actual supercharging pressure PIN and the target supercharging pressure PINT becomes smaller than the predetermined value “−α”, an abnormality determination is not made, so that an error is detected. Judgment can be suppressed.

  (3) In the above-described embodiment, it is determined that the actual supercharging pressure PIN is abnormal on the condition that the actual supercharging pressure PIN exceeds the target supercharging pressure PINT by a predetermined pressure. As a result, an abnormality such that the supercharging efficiency of the supercharging pressure changing mechanism becomes excessive due to the fixing of the nozzle vane 41, etc. occurs, the target supercharging pressure PINT rises and the actual supercharging pressure PIN becomes the target supercharging pressure. When rising beyond PINT, it is possible to quickly determine an abnormality. Therefore, the engine compression ratio becomes excessive due to excessive supercharging, and it is possible to suppress the occurrence of adverse effects such as knocking and damage to exhaust system members accompanying an increase in exhaust pressure.

  (4) In the above embodiment, it is determined that there is an abnormality on the condition that the state where the target boost pressure PINT and the actual boost pressure PIN have deviated continues for a predetermined time. Thereby, the abnormality determination accuracy can be improved and the reliability of the abnormality determination result can be increased.

In addition, you may change the said embodiment as follows.
In the above embodiment, the abnormality determination is performed when the counter exceeds the predetermined value β in step S140. However, the predetermined value β may be variably set according to the value of the supercharging pressure. In general, the follow-up characteristic often deteriorates in a high load / high rotation region where the boost pressure is high. For example, as the target boost pressure PINT at the start of the abnormality determination routine increases, the value of the predetermined value β increases. A setting method can be considered. In addition to this, the predetermined value β may be set according to the value of the engine speed NE and the fuel injection amount Q, which are correlation values of the supercharging pressure. Thus, by setting the predetermined value β so as to match the engine operating state, it is not necessary to set the time required for the abnormality determination unnecessarily long, and the abnormality determination can be performed promptly.

  In the above embodiment, the abnormality determination is prohibited under a transient situation where the actual supercharging pressure PIN as shown in FIG. 4 converges. For example, the predetermined value “−α” is set to a relatively small value. Alternatively, the abnormality determination mode may be changed so that it is difficult to determine the abnormality by setting the predetermined value “−γ” or “−δ” to a relatively large value. Thus, even if the abnormality determination mode is changed, a situation in which an erroneous determination is made can be suppressed as much as possible.

  In the above embodiment, the determination of abnormality is prohibited by comparing the decrease rate of the target supercharging pressure PINT or the actual supercharging pressure PIN with a predetermined value. For example, without making such a comparison, the target supercharging pressure PINT or By setting the predetermined value “−α” to be relatively small as the rate of decrease in the actual supercharging pressure PIN is large, the abnormality determination mode may be changed so that it is difficult to determine that there is an abnormality.

  In the above embodiment, the degree of divergence between the actual supercharging pressure PIN and the target supercharging pressure PINT is determined based on the pressure difference between the actual supercharging pressure PIN and the target supercharging pressure PINT. You may make it perform based on ratio (PIN / PINT) of actual supercharging pressure PIN and target supercharging pressure PINT.

  In the above embodiment, in steps S100 and S110 of the flowchart shown in FIG. 2, the pressure change speed is determined based on the difference between the current pressure and the pressure one routine before. You may make it carry out based on the ratio of a pressure and the pressure before one routine.

  In the above embodiment, in the flowchart shown in FIG. 2, it is determined whether or not the rate of decrease in the target boost pressure PINT and the actual boost pressure PIN is equal to or higher than a predetermined value. Only one of the actual supercharging pressures PIN may be determined.

  In the above embodiment, an abnormality determination is made for a state where the actual boost pressure PIN rises above the target boost pressure PINT, but the actual boost pressure PIN falls below the target boost pressure PINT. Also, the abnormality determination may be performed using the same technical idea.

  In the above embodiment, “−α”, “−γ”, and “−δ” are set as the predetermined values, but these are variable depending on the engine operating state parameters such as the engine speed NE and the fuel injection amount Q. You may make it set.

  In the above embodiment, the abnormality determination is performed according to the flowchart shown in FIG. 2, but it may be added as a determination element for the abnormality determination that the absolute value of the actual supercharging pressure PIN is equal to or greater than a predetermined pressure.

  In the above embodiment, when the target boost pressure PINT and the actual boost pressure PIN are decreased, the abnormality determination is prohibited when the decrease speed is equal to or higher than a predetermined value, but the target boost pressure PINT and the actual boost pressure are When at least one of the PINs rises, the abnormality determination may be prohibited or the abnormality determination mode may be changed when the rising speed is equal to or higher than a predetermined value.

-Although the turbocharger 35 of the diesel engine 11 is used in the said embodiment, you may apply to the turbocharger of a gasoline engine.
In the above embodiment, the single-stage turbocharger 35 is used, but it may be applied to a multistage turbocharger or a parallel turbocharger.

A block diagram of a diesel engine equipped with a turbocharger. The flowchart of an abnormality determination routine. (A), (b), (c) is a time chart when the target supercharging pressure increases. (A), (b), (c) is a time chart when a target supercharging pressure falls.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Diesel engine, 16 ... Crank position sensor, 35 ... Turbocharger, 37 ... Turbine wheel, 41 ... Nozzle vane, 71 ... Pressure sensor, 91 ... ECU, 92 ... Warning light.

Claims (6)

In the abnormality determination device that performs abnormality determination based on the degree of divergence between the target supercharging pressure and the actual supercharging pressure for a turbocharger having a supercharging pressure changing mechanism capable of changing the supercharging pressure according to the engine operating state,
A turbocharger abnormality determination device that changes the abnormality determination mode so that it is difficult to determine that an abnormality is detected when a change rate of at least one of the target supercharging pressure and the actual supercharging pressure is relatively large. In the turbocharger abnormality determination device according to claim 1,
A turbocharger abnormality determination device that prohibits the abnormality determination when a changing speed of at least one of the target supercharging pressure and the actual supercharging pressure is a predetermined value or more. In the turbocharger abnormality determination device according to claim 1 or 2,
A turbocharger abnormality determination device that changes the abnormality determination mode only when the target supercharging pressure decreases and the rate of decrease is equal to or greater than a predetermined value. In the turbocharger abnormality determination device according to any one of claims 1 to 3,
A turbocharger abnormality determination device that changes the abnormality determination mode only when the actual supercharging pressure decreases and the rate of decrease is equal to or greater than a predetermined value. In the turbocharger abnormality determination device according to claim 3 or 4,
An abnormality determination device for a turbocharger that determines that an abnormality is found on the condition that the actual supercharging pressure exceeds the target supercharging pressure.   The turbocharger abnormality determination device according to any one of claims 1 to 5, wherein the abnormality is a condition that a state where the target supercharging pressure and the actual supercharging pressure deviate continues for a predetermined time. Turbocharger abnormality determination device for determining.

Images