JP2007303294A - Control device for internal combustion engine with supercharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To favorably detect the abnormality of a supercharging pressure sensor in an internal combustion engine with a supercharger. <P>SOLUTION: An engine 10 contains a suction compressor 31 of a supercharger 30 in a suction pipe 11 and a supercharging pressure sensor 12 on the downstream side of the pipe. An ECU 50 calculates target supercharging pressure from target torque calculated in accordance with driver demand and executes supercharging pressure feedback control so as to make actual supercharging pressure detected by the supercharging pressure sensor 12 coincide with the target supercharging pressure, and determines that the engine is in a supercharging pressure convergent state in which the actual supercharging pressure is converged to the target supercharging pressure. When the actual supercharging pressure is in the supercharging pressure convergent state, the abnormality of the supercharging pressure sensor 12 is determined to exist on the basis of the torque difference between generation torque and target torque of an engine 10. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

  Conventionally, various internal combustion engines provided with a supercharger such as a turbocharger have been put into practical use. The operation of this supercharger improves intake efficiency and improves the output of the internal combustion engine. In addition, a technique has been proposed in which a target boost pressure is calculated according to each target torque, and the boost pressure control is performed based on the target boost pressure. In this case, a supercharging pressure sensor is installed downstream of the supercharger in the intake pipe, and the actual supercharging pressure is detected by the supercharging pressure sensor. Then, the supercharging pressure feedback control is performed so that the actual supercharging pressure matches the target supercharging pressure.

  Here, when the supercharging pressure sensor breaks down, the supercharging pressure feedback control cannot be performed normally, and inconveniences such as excessive increase in supercharging pressure occur. Thus, a method for determining abnormality of the supercharging pressure sensor has been proposed (see, for example, Patent Document 1). Specifically, during boost pressure feedback control, if the feedback correction value is stuck to the upper limit value or lower limit value and the deviation between the actual boost pressure and the target boost pressure is not within the specified range, It is determined that an abnormality has occurred in the pressure sensor.

In the above-described prior art, when the deviation between the actual boost pressure and the target boost pressure is out of the predetermined range due to the abnormality of the boost pressure sensor, it can be determined that the boost pressure sensor is abnormal. However, it is conceivable that the actual supercharging pressure converges to the target supercharging pressure even though the supercharging pressure sensor is abnormal. In such a case, since the deviation between the actual supercharging pressure and the target supercharging pressure is small, a sensor abnormality cannot be detected, resulting in inconvenience that a detection failure occurs.
Japanese Patent No. 3738604

  An object of the present invention is to provide a control device for an internal combustion engine with a supercharger that can preferably detect abnormality of a supercharging pressure sensor.

  In the present invention, the target boost pressure is calculated from the target torque calculated according to the driver request, and the boost pressure feedback control is performed so that the actual boost pressure detected by the boost pressure sensor matches the target boost pressure. carry out. In particular, it is determined that the actual boost pressure is in a boost pressure convergence state in which the actual boost pressure has converged to the target boost pressure. An abnormality of the supercharging pressure sensor is determined based on the torque deviation.

  In short, if an abnormality occurs in the supercharging pressure sensor, even if the actual supercharging pressure converges to the target supercharging pressure by supercharging pressure feedback control, the control becomes uncertain, and an error in supercharging pressure occurs. The generated torque of the internal combustion engine becomes an abnormal value by the control. In this case, since a torque deviation occurs between the generated torque of the internal combustion engine and the target torque, it is possible to determine the occurrence of abnormality of the supercharging pressure sensor based on the torque deviation. Therefore, the detection failure of the supercharging pressure sensor abnormality can be solved, and a suitable abnormality determination can be realized.

More specifically, the abnormality determination of the supercharging pressure sensor may be performed as in the following (1) and (2).
(1) When the torque deviation between the generated torque of the internal combustion engine and the target torque is out of a predetermined range and a predetermined time has passed in that state, it is determined that the supercharging pressure sensor is abnormal.
(2) The torque deviation between the generated torque of the internal combustion engine and the target torque is sequentially integrated, and when the integrated value deviates from a predetermined range, it is determined that the supercharging pressure sensor is abnormal.

  In any of the above (1) and (2), the abnormality of the supercharging pressure sensor can be suitably determined. In particular, according to (2), when the torque deviation with respect to the target torque increases due to the sensor abnormality, the integrated value of the torque deviation quickly reaches the abnormality determination value, and early abnormality determination becomes possible. Therefore, treatments such as fail safe can be implemented at an early stage.

  Also, when the actual boost pressure is in the boost pressure convergence state where it converges to the target boost pressure, sensor abnormality determination is performed using the torque deviation as an abnormality determination parameter, while the actual boost pressure is the target boost pressure. When the supercharging pressure has not converged to the non-convergence state, the sensor abnormality determination may be performed using the supercharging pressure deviation as an abnormality determination parameter. In this case, the abnormality determination of the supercharging pressure sensor can be suitably performed regardless of the convergence state of the actual supercharging pressure with respect to the target supercharging pressure.

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

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

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

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

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

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

  In the turbocharger 30, the exhaust turbine 32 is rotated by the exhaust gas flowing through the exhaust pipe 24, and the rotational force is transmitted to the intake compressor 31 via the rotation shaft 33. Then, the intake air flowing through the intake pipe 11 is compressed by the intake compressor 31 and supercharging is performed. In this case, the waste gate valve 37 is opened, so that excessive supercharging pressure is prevented from being generated.

  Here, the wastegate valve 37 functions as a supercharging state varying means, and is configured to be able to adjust the supercharging state from an arbitrary state. An example of the configuration will be briefly described. The wastegate valve 37 includes a diaphragm-type movable portion and a pressure control valve (vacuum switching valve) for adjusting the pressure of the pressure chamber defined by the diaphragm. An actuator is attached. An intake pipe pressure (that is, a supercharging pressure) downstream of the intake compressor 31 is introduced into the pressure chamber, and the pressure acting on the pressure chamber is controlled by the duty control of the pressure control valve by the ECU 50. Thereby, the wastegate valve 37 is displaced, and the supercharging state is adjusted.

  In this case, if the control duty ratio is small and the pressure control valve is closed, the intake pipe pressure directly acts on the pressure chamber. Therefore, the wastegate valve 37 operates according to the supercharging pressure. That is, when the supercharging pressure increases and the intake pipe pressure rises, the pressure in the pressure chamber rises, and accordingly, the wastegate valve 37 operates to the open side and the turbine power decreases. As the turbine power decreases, the compressor power also decreases, and the supercharging pressure decreases. Conversely, when the control duty ratio is large and the pressure control valve is opened, the pressure acting on the pressure chamber is reduced accordingly. Therefore, even if the supercharging pressure increases and the intake pipe pressure rises, the pressure in the pressure chamber does not rise, and the wastegate valve 37 is kept closed. Therefore, even if the supercharging pressure increases, the turbine power is maintained, and the supercharging pressure is maintained or the supercharging pressure is increased.

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

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

  As is well known, the ECU (electronic control unit) 50 is mainly composed of a microcomputer composed of a CPU, ROM, RAM, etc., and by executing various control programs stored in the ROM, the engine operating state can be changed each time. In response, various controls of the engine 10 are performed. That is, detection signals are input to the ECU 50 from the various sensors described above. The ECU 50 calculates the fuel injection amount, the ignition timing, and the like based on various detection signals that are input as needed, and controls the drive of the fuel injection valve 19 and the spark plug 25.

  In this embodiment, so-called torque-based control is employed in various types of vehicle control. For example, the throttle opening is controlled to a target value using a torque value required by the driver in electronic throttle control as a basic parameter. In brief, the ECU 50 calculates a target air amount based on the target torque calculated based on the accelerator opening and the engine speed, and calculates the target throttle opening based on the target air amount. In this case, in particular, in addition to the target air amount, a pressure ratio between the throttle upstream pressure and the throttle downstream pressure (= throttle downstream pressure / throttle upstream pressure) is used as a parameter, and the target throttle opening is calculated based on these parameters. Then, a desired air amount control is performed by driving the throttle actuator 15 based on the target throttle opening.

  Note that in this vehicle, control is performed using torque as a unified parameter in a similar manner other than throttle control. For example, torque base control is also performed in transmission control, cruise control, and the like. By using the torque as a unified parameter in this way, it is possible to share parameters for engine control and other vehicle control, and the cooperation of each control is enhanced. There is also an advantage that control can be easily applied to different vehicles and engines.

  Further, the ECU 50 calculates the target boost pressure from the target torque calculated according to the driver request, and the boost pressure feedback so that the actual boost pressure detected by the boost pressure sensor 12 matches the target boost pressure. Implement control. Specifically, at this time, a duty ratio signal for the waste gate valve 37 is calculated based on the actual boost pressure and the target boost pressure, and the waste gate valve opening is controlled by the duty ratio signal. Further, the abnormality determination of the supercharging pressure sensor 12 is performed in parallel with the supercharging pressure feedback control. In this embodiment, in particular, it is determined that the actual boost pressure is in the boost pressure convergence state where the actual boost pressure has converged to the target boost pressure. The abnormality of the supercharging pressure sensor 12 is determined based on the torque deviation from the torque. The details will be described below.

  FIG. 2 is a flowchart showing an abnormality determination process of the supercharging pressure sensor 12, and this process is repeatedly executed by the ECU 50 at a predetermined time period.

  In FIG. 2, first, in steps S101 and S102, it is determined whether or not a precondition for executing the abnormality determination is satisfied. That is, in step S101, it is determined whether or not the supercharging pressure feedback control is currently being performed. In step S102, it is determined whether or not the supercharging pressure is in a steady state. Here, when the accelerator opening is equal to or larger than the predetermined opening and the engine speed is equal to or higher than the predetermined rotation speed, the supercharging pressure feedback control is performed, and in this state, step S101 is affirmed. If the amount of change in the actual supercharging pressure (sensor measurement value) within a predetermined time is equal to or less than the predetermined value, step S102 is affirmed. When both steps S101 and S102 are YES, the process proceeds to the subsequent step S103, and when any of steps S101 and S102 is NO, the present process is terminated.

  In step S103, it is determined whether or not the actual boost pressure detected by the boost pressure sensor 12 has converged to the target boost pressure. Specifically, it is determined whether or not the absolute value of the deviation between the target boost pressure and the actual boost pressure (= | target boost pressure−actual boost pressure |) is less than a predetermined value. If | supercharging pressure deviation | <predetermined value, the process proceeds to step S104. If | supercharging pressure deviation | ≧ predetermined value, the process is terminated.

  In step S104, it is determined whether or not the absolute value of the deviation between the actual torque generated by the engine 10 and the target torque is greater than a predetermined value. At this time, the actual torque is calculated by a map or a mathematical formula based on the actual air amount and the engine speed. Further, the target torque is calculated based on the accelerator operation amount of the driver and the engine speed. If the supercharging pressure sensor 12 is normal, the actual torque converges to the target torque, and it is determined that | torque deviation | ≦ predetermined value. If the supercharging pressure sensor 12 is abnormal, it is determined that the actual torque does not converge to the target torque and | torque deviation |> predetermined value.

  When | torque deviation | ≦ predetermined value and the process proceeds to step S105, the normal counter is added (+1) and the abnormal counter is reset in step S105. Thereafter, in step S106, it is determined whether or not the value of the normal counter is greater than or equal to a predetermined value. The predetermined value (normality determination threshold) for determining the value of the normal counter is a value corresponding to about several seconds. When normal counter value ≧ predetermined value, the process proceeds to step S107 and it is determined that the supercharging pressure sensor 12 is normal.

  On the other hand, if | torque deviation |> predetermined value and the process proceeds to step S108, the normal counter is reset and the abnormal counter is added (+1) in step S108. Thereafter, in step S109, it is determined whether or not the value of the abnormality counter is greater than or equal to a predetermined value. The predetermined value (abnormality determination threshold value) for determining the value of the abnormality counter is a value corresponding to about several seconds. If abnormal counter value ≧ predetermined value, the process proceeds to step S110 to determine that the supercharging pressure sensor 12 is abnormal.

When it is determined that the supercharging pressure sensor 12 is abnormal, diagnostic data indicating the occurrence of abnormality is stored in a backup memory such as an EEPROM, and an abnormality warning lamp is turned on. In addition, as a fail-safe process,
・ Reduce the target torque or target boost pressure and limit the engine output.
・ Stop boost pressure feedback control.
-The wastegate valve 37 is opened (fully opened), and supercharging by the turbocharger 30 is stopped.
A plurality of such processes are performed simultaneously or alternatively.

  Incidentally, when the abnormality of the supercharging pressure sensor 12 is temporary and the abnormal state of the sensor is resolved, when the supercharging pressure feedback control is performed, | supercharging pressure deviation | <predetermined value and | torque deviation Return to the state of | ≦ predetermined value (YES in step S103 and NO in step S104). In such a case, the normal counter is counted up, and accordingly the normal return determination of the supercharging pressure sensor 12 is performed. However, this configuration is based on the premise that the supercharging pressure feedback control is continued even after the sensor abnormality determination.

  According to the present embodiment described above in detail, the abnormality of the supercharging pressure sensor 12 based on the torque deviation of the engine 10 when the actual supercharging pressure converges to the target supercharging pressure. Since the determination is made, the actual sensor abnormality can be properly determined even if the control is seemingly normal in supercharging pressure feedback control. Therefore, the detection failure of the supercharging pressure sensor abnormality can be solved, and a suitable abnormality determination can be realized.

  Thus, if the abnormality determination of the supercharging pressure sensor 12 can be properly performed, the reliability of the sensor 12 can be improved. Accordingly, the reliability of throttle opening control performed using the throttle upstream pressure (supercharging pressure) as a parameter is improved.

[Second Embodiment]
Next, the second embodiment will be described with a focus on differences from the first embodiment. In this embodiment, in the supercharging pressure convergence state in which the actual supercharging pressure has converged to the target supercharging pressure by the supercharging pressure feedback control, an abnormality of the supercharging pressure sensor 12 is determined based on the integrated value of the torque deviation. . The details will be described below.

  FIG. 3 is a flowchart showing an abnormality determination process for the supercharging pressure sensor 12 in the present embodiment. This process is executed in place of FIG.

  In FIG. 3, in step S201, it is determined whether or not the supercharging pressure feedback control is currently being performed. In step S202, it is determined whether or not the supercharging pressure is in a steady state. In step S203, it is determined whether or not the actual boost pressure detected by the boost pressure sensor 12 has converged to the target boost pressure. The processes in steps S201 to S203 are the same as those in steps S101 to S103 of FIG. 2, and if all of these are YES, the process proceeds to step S204, and if any of them is NO, the process is terminated.

  In step S204, it is determined whether or not the absolute value of the deviation (torque deviation) between the actual torque and the target torque is greater than a predetermined value. Here, if the supercharging pressure sensor 12 is normal, it is determined that | torque deviation | ≦ predetermined value, and if the supercharging pressure sensor 12 is abnormal, it is determined that | torque deviation |> predetermined value. (This is the same as above.)

  When | torque deviation | ≦ predetermined value and the process proceeds to step S205, the integrated value ΣT of the torque deviation is cleared to 0 and the normal counter is added (+1) in step S205. Thereafter, in step S206, it is determined whether or not the value of the normal counter is greater than or equal to a predetermined value. When normal counter value ≧ predetermined value, the process proceeds to step S207 to determine that the supercharging pressure sensor 12 is normal.

  On the other hand, if | torque deviation |> predetermined value and the process proceeds to step S208, the torque deviation integrated value ΣT is updated and the normal counter is reset in step S208. At this time, the currently calculated torque deviation ΔT (= | target boost pressure−actual boost pressure |) is added to the previous value of “ΣT” to calculate the current value of “ΣT”. Thereafter, in step S209, it is determined whether or not the torque deviation integrated value ΣT is equal to or greater than a predetermined value. When ΣT ≧ predetermined value, the process proceeds to step S210, and it is determined that the supercharging pressure sensor 12 is abnormal.

  As described above, according to the second embodiment, similarly to the first embodiment, the omission of the supercharging pressure sensor abnormality can be eliminated, and a suitable abnormality determination can be realized. In particular, according to the present embodiment, when the torque deviation with respect to the target torque becomes large due to the sensor abnormality, the integrated value ΣT of the torque deviation quickly reaches the abnormality determination value, and early abnormality determination becomes possible. Therefore, treatments such as fail safe can be implemented at an early stage.

[Other Embodiments]
The present invention is not limited to the description of the above embodiment, and may be implemented as follows, for example.

  When the actual boost pressure has converged to the target boost pressure, the sensor error is determined using the torque deviation as the error determination parameter, while the actual boost pressure converges to the target boost pressure. In the non-convergence state of the supercharging pressure that has not been performed, it is also possible to carry out sensor abnormality determination using the supercharging pressure deviation as an abnormality determination parameter. An outline of the processing by the ECU 50 is shown in the flowchart of FIG.

  In FIG. 4, in step S301, it is determined whether or not the supercharging pressure feedback control is currently being executed. If the feedback control is being executed, in step S302, the actual overpressure detected by the supercharging pressure sensor 12 is detected. It is determined whether or not the supply pressure has converged to the target supercharging pressure. If the actual boost pressure has converged to the target boost pressure, the process proceeds to step S303, and abnormality determination of the boost pressure sensor 12 is performed using the torque deviation as an abnormality determination parameter. On the other hand, if the actual boost pressure has not converged to the target boost pressure, the process proceeds to step S304, and abnormality determination of the supercharging pressure sensor 12 is performed using the supercharging pressure deviation as an abnormality determination parameter. Here, in step S303, the abnormality determination process described in FIG. 2 or FIG. 3 is performed (for example, steps S104 to S110). In step S304, a deviation between the actual supercharging pressure (sensor detection value) and the target supercharging pressure is calculated, and the supercharging pressure deviation is sequentially accumulated. Based on the accumulated value of the supercharging pressure deviation. An abnormality determination of the supercharging pressure sensor 12 is performed. According to this configuration, in the supercharging pressure feedback control, the abnormality determination of the supercharging pressure sensor 12 can be suitably performed regardless of the convergence state of the actual supercharging pressure with respect to the target supercharging pressure.

Depending on the degree of abnormality of the supercharging pressure sensor 12, it is possible to change the content of the fail-safe process. Specifically, as a fail-safe process,
(1) Reduce the target torque or target boost pressure and limit the engine output.
(2) Stop boost pressure feedback control.
(3) The wastegate valve 37 is opened (fully opened), and supercharging by the turbocharger 30 is stopped.
When each process is defined, each of the processes (1) to (3) is selectively performed according to the degree of sensor abnormality. The degree of abnormality may be determined based on the magnitude of the torque deviation or the duration when the torque deviation is excessive. In this case, it is preferable to switch the fail safe process from (1) to (2) to (3) as the degree of abnormality increases.

  If a bypass passage is provided between the upstream portion and the downstream portion of the intake pipe 11 with the intake compressor 31 interposed therebetween, and an air bypass valve is provided in this bypass passage, the supercharging pressure sensor 12 can be operated when an abnormality occurs. As the fail-safe process, the air bypass valve may be opened (fully open), thereby stopping supercharging by the turbocharger 30.

  In the above embodiment, an example in which a turbocharger is applied as a turbocharger has been described. Effect. In addition to gasoline engines, it can also be applied to diesel engines.

The block diagram which shows the outline of an engine control system. The flowchart which shows the abnormality determination process of the supercharging pressure sensor in 1st Embodiment. The flowchart which shows the abnormality determination process of the supercharging pressure sensor in 2nd Embodiment. The flowchart which shows the abnormality determination process of the supercharging pressure sensor in other embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Engine, 12 ... Supercharging pressure sensor, 14 ... Throttle valve, 30 ... Turbocharger, 37 ... Wastegate valve, 50 ... ECU.

Claims (4)

Applied to an internal combustion engine having a supercharger that supercharges intake air and a supercharging pressure sensor that detects supercharging pressure by the supercharger, and a target supercharging pressure from a target torque calculated according to a driver request In the control device for an internal combustion engine that performs supercharging pressure feedback control so that the actual supercharging pressure detected by the supercharging pressure sensor matches the target supercharging pressure,
State determination means for determining that the actual supercharging pressure is in a supercharging pressure convergence state in which the actual supercharging pressure has converged to a target supercharging pressure;
An abnormality determining means for determining an abnormality of the supercharging pressure sensor based on a torque deviation between the generated torque of the internal combustion engine and the target torque in the supercharging pressure convergence state;
A control device for an internal combustion engine with a supercharger.   The said abnormality determination means determines that the said supercharging pressure sensor is abnormal when the said torque deviation remove | deviates from the predetermined range and predetermined time passes in the state. Control device for an internal combustion engine with a supercharger.   2. The supercharging according to claim 1, wherein the abnormality determination unit sequentially accumulates the torque deviation and determines that the supercharging pressure sensor is abnormal when the accumulated value is out of a predetermined range. Control device for internal combustion engine with a machine.   The abnormality determining means performs sensor abnormality determination using the torque deviation as an abnormality determination parameter when the actual supercharging pressure is in a supercharging pressure convergence state in which the actual supercharging pressure has converged to a target supercharging pressure. 4. The sensor abnormality determination is performed using the supercharging pressure deviation as an abnormality determination parameter when the engine pressure is in a supercharging pressure non-convergence state that has not converged to the target supercharging pressure. 5. The control apparatus of the internal combustion engine with a supercharger as described.

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