JP2008291756A - Failure diagnosis device of fuel pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system using a motor with a brush as a drive source of a fuel pump capable of accurately determining brush deterioration of the motor and improving failure determination accuracy of the fuel pump. <P>SOLUTION: The fuel pump 32 is started with a voltage of an auxiliary battery 31, as a power supply voltage of the fuel pump 32, raised during an engine 11 stops, to detect an inrush current accurately at a start of the fuel pump 32. Based on the inrush current, brush resistance of the motor of the fuel pump 32 is accurately calculated. It is determined whether the brush is deteriorated or not by whether a difference of the brush resistance and reference brush resistance (brush resistance calculated at shipment of a vehicle or immediately after the shipment, or at replacement of the fuel pump 32 or immediately after the replacement) is in a predetermined normal range or not. Thereby, a change of the brush resistance from the new fuel pump 32 is accurately evaluated while eliminating effect of an individual difference (deviation in manufacturing) of such as coil resistance and wiring resistance of the fuel pump 32 to accurately determine whether the brush is deteriorated or not. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel pump failure diagnosis apparatus that uses a brush motor as a drive source of a fuel pump that pumps up fuel in a fuel tank and supplies it to an internal combustion engine.

  The demand for idle stop systems and hybrid electric vehicles is expected to increase in the future in order to meet the recent demands for low emissions and low fuel consumption. In idle stop systems and hybrid electric vehicles, the internal combustion engine automatically stops.・ The number of times the fuel pump is automatically started increases, and the fuel pump is stopped and started in conjunction with the automatic stop / automatic start of the internal combustion engine. Therefore, the number of times the fuel pump is started tends to increase significantly. There is a possibility that the burden increases and a failure is likely to occur.

As described in Patent Document 1 (Japanese Patent Laid-Open No. 2004-190508), the failure diagnosis of the fuel pump is performed based on the applied voltage and power consumption of the motor portion of the fuel pump. There is something that was made.
JP 2004-190508 A (the second page, etc.)

  By the way, while the fuel pump is being driven (that is, while the motor is rotating), a counter electromotive force is generated in the motor, and the rotational speed of the motor changes due to changes in fuel temperature (fuel viscosity), fuel consumption, etc. The power consumption of the motor varies depending on the counter electromotive force and the rotational speed. For this reason, as in the technique of the above-mentioned Patent Document 1, the failure diagnosis that determines the failure of the motor unit based on the power consumption of the motor unit that is driving the fuel pump may not be able to accurately determine the failure of the motor unit. There is sex.

  In addition, fuel pumps mounted on automobiles often use low-cost brush motors as a drive source from the viewpoint of cost reduction. In fuel pumps using brush motors, motor brush deterioration is a fuel problem. It often causes pump failure.

  The present invention has been made in view of such circumstances, and the object of the present invention is to accurately determine the deterioration of the brush of the motor in a fuel pump using a brushed motor as a drive source. An object of the present invention is to provide a fuel pump failure diagnosis device capable of improving the fuel pump failure determination accuracy.

  In order to achieve the above object, an invention according to claim 1 is directed to a fuel pump failure diagnosis apparatus using a brushed motor as a drive source of a fuel pump that pumps up fuel in a fuel tank and supplies the fuel to an internal combustion engine. The brush resistance of the motor is calculated by the brush resistance calculation means based on the inrush current at the start of the pump, and the brush deterioration determination means determines the brush deterioration of the motor based on the brush resistance.

  The inrush current at the start of the fuel pump is determined by the resistance of the fuel pump (brush resistance, coil resistance, wiring resistance, etc.) and the drive voltage, as well as the current value. Since it is hardly affected by the back electromotive force or rotational speed of the motor, the inrush current at the start of the fuel pump can be detected with higher accuracy than the current after the start, and this inrush current detected with high accuracy If the brush resistance is calculated using, the brush resistance can be obtained with high accuracy. In addition, when the brush deteriorates and the chipping or wear of the brush increases, the contact resistance between the brush and the commutator increases and the brush resistance increases. Therefore, the brush resistance accurately evaluates the degree of brush deterioration. It becomes an indicator. Therefore, if the brush deterioration is determined using the brush resistance accurately obtained from the inrush current, the brush deterioration can be accurately determined, and the failure determination accuracy of the fuel pump can be improved (the brush deterioration is the fuel pump). This is often the cause of failure of

  In this case, as in claim 2, the brush resistance calculated at the time of vehicle shipment or immediately after it or at the time of replacement of the fuel pump or immediately after that is used as the reference brush resistance, and this reference brush resistance is compared with the brush resistance calculated this time. The brush deterioration of the motor may be determined. In this way, the reference brush resistance is compared with the current brush resistance based on the brush resistance when the fuel pump currently in use is new (when the vehicle is shipped or when the fuel pump is replaced). Since the brush deterioration can be determined, the influence of individual differences (manufacturing variation) such as coil resistance and wiring resistance of the fuel pump is eliminated, and the fuel pump from when it is new (when the vehicle is shipped or when the fuel pump is replaced) Brush deterioration can be accurately determined by accurately evaluating the change in brush resistance (change in contact resistance due to brush chipping or wear).

  In the present invention, the brush resistance may be calculated based on the inrush current when the fuel pump is started in conjunction with the start of the internal combustion engine, but in this case, the drive voltage of the starter that starts the internal combustion engine The drive voltage of the fuel pump may be affected and the inrush current of the fuel pump may fluctuate. Therefore, the detection accuracy of the inrush current is lowered, and the accuracy of the brush resistance calculated from the inrush current is lowered. there is a possibility.

  Therefore, as in claim 3, the brush resistance may be calculated based on the inrush current when the fuel pump is started while the internal combustion engine is stopped. In this way, the inrush current can be accurately detected without being affected by the starter drive voltage and the fuel pump drive voltage is stable, and the accuracy of the brush resistance calculated from the inrush current can be improved. Can do.

  Further, as in claim 4, the brush resistance may be calculated based on the inrush current when the fuel pump is started in a state where the power supply voltage (battery voltage) of the fuel pump is boosted. In this way, the inrush current detection accuracy can be further increased by increasing the inrush current value, and the brush resistance accuracy calculated from the inrush current can be further improved.

Hereinafter, an embodiment in which the best mode for carrying out the present invention is applied to a hybrid electric vehicle will be described.
First, the configuration of a vehicle drive control system for a hybrid electric vehicle will be described with reference to FIG. The hybrid electric vehicle includes an engine 11 (internal combustion engine) and a starter AC motor 12 as drive sources, and these powers are transmitted to a differential device 15 via a torque converter 13 and a transmission 14 for further driving. It is transmitted to the drive wheel 17 through the shaft 16.

  The powertrain control device 18 is based on the engine operating state detected by the crank angle sensor 21, the intake air amount sensor 22, the cooling water temperature sensor 23, etc., and vehicle state information transmitted from the vehicle control device 19. The engine 11 controls the output torque of the engine 11 by controlling the intake air amount, fuel injection amount, and ignition timing of the engine 11, and also controls the torque generated by the AC motor 12. Further, the lockup state of the torque converter 13 and the transmission 14 are controlled. The transmission gear ratio is controlled.

  On the other hand, the vehicle control device 19 outputs output signals from various sensors such as an accelerator pedal sensor 24, a shift sensor 25, a vehicle speed sensor 26, and a brake master cylinder pressure sensor 27, and an engine operating state transmitted from the power train control device 18. The traveling state of the vehicle is controlled based on the information. Specifically, the vehicle control device 19 includes an engine 11, an AC motor 12, a transmission 14, a high-voltage DC battery via a powertrain control device 18, an inverter 28, and an auxiliary battery control device 29 (DC / DC converter). 30, the auxiliary battery 31 and the like are cooperatively controlled, and function as idle stop control means for executing idle stop when a predetermined idle stop condition is satisfied, and also control start, acceleration assist, deceleration regeneration, and the like.

  For example, when the driver performs a predetermined operation for starting the vehicle (depressing the accelerator pedal, releasing the brake, operating the shift lever, etc.) in the idle stop state, the AC motor 12 (starter) is activated to start the engine 11. , The fuel pump 32 is started by the fuel pump control device 37, the fuel injection control and the ignition control are started by the power train control device 18, and the engine 11 is started. The power is transmitted to the drive wheels 17 via the torque converter 13, the transmission 14, and the differential device 15 to start the vehicle.

  The auxiliary battery control device 29 controls the charge amount of the auxiliary battery 31 based on signals from the vehicle control device 19 and output signals of various sensors such as the auxiliary battery current sensor 35 and the auxiliary battery temperature sensor 36. To do. The vehicle control device 19 is equipped with a self-diagnosis function, and when an abnormality / failure of each part of the vehicle drive control system is detected, the abnormality / failure content is displayed on the warning display unit 40 (warning means) as a warning. Warning the driver.

  A fuel pump 32 that pumps up fuel in a fuel tank (not shown) and supplies it to the engine 11 incorporates a brushed DC motor (not shown) as a drive source and is driven using the voltage of the auxiliary battery 31 as a power supply voltage. Is done. The fuel pump control device 37 that controls the fuel pump 32 controls the drive current of the fuel pump 32 based on output signals from the auxiliary battery voltage sensor 38, the fuel pump coil temperature sensor 39, and the like.

  As shown in FIG. 2, the fuel pump control device 37 is a fuel pump operation determination unit 41 that converts output signals from the auxiliary battery voltage sensor 38, the fuel pump coil temperature sensor 39, and the like and signals from the powertrain control device 18. Based on the determination result of the fuel pump operation determination unit 41, the target drive current calculation unit 42 calculates the target drive current.

  The drive circuit unit 43 includes a switching element 44 that turns ON / OFF the energization of the fuel pump 32, and a control duty calculation unit 45 that controls the duty of the switching element 44. The control duty calculation unit 45 uses the target drive current. The drive current of the fuel pump 32 is controlled to the target drive current by calculating the duty according to the above and varying the duty of the switching element 44.

  In addition, a current detection resistor 46 is provided between the switching element 44 and the ground terminal, and the drive current detection unit 47 uses the terminal voltage of the current detection resistor 46 to drive the drive current of the fuel pump 32 and the inrush at startup. Detect current. While the fuel pump 32 is stopped, the switching element 44 of the drive circuit unit 43 is maintained in the OFF state, and the energization to the fuel pump 32 is cut off.

  By the way, in the hybrid electric vehicle as in the present embodiment, the number of times the engine 11 is automatically stopped / automatically increased due to idle stop or the like increases, and the fuel pump 32 is stopped / linked in conjunction with the automatic stop / automatic start of the engine 11. Since the fuel pump 32 is activated, the number of times the fuel pump 32 is activated tends to increase significantly, and the load on the fuel pump 32 increases, which may easily cause a failure (such as motor brush deterioration).

Therefore, in the present embodiment, failure diagnosis of the fuel pump 32 is executed as follows by executing each routine described later by the fuel pump control device 37.
First, the inrush current when the fuel pump 32 is started while the engine 11 is stopped is detected by the drive current detector 47, and the brush resistance of the motor is calculated based on the inrush current when the fuel pump 32 is started.

  The inrush current at the start of the fuel pump 32 is determined by the resistance (brush resistance, coil resistance, wiring resistance, etc.) of the fuel pump 32 and the driving voltage in addition to the large current value. Thus, since it is hardly affected by the back electromotive force or rotational speed of the motor, the inrush current at the start of the fuel pump 32 can be detected with higher accuracy than the current after the start, and this can be detected with high accuracy. If the brush resistance is calculated using an inrush current, the brush resistance can be obtained with high accuracy. In addition, when the brush deteriorates and the chipping or wear of the brush increases, the contact resistance between the brush and the commutator increases and the brush resistance increases. Therefore, the brush resistance accurately evaluates the degree of brush deterioration. It becomes an indicator.

  The presence or absence of brush deterioration is determined based on whether or not the difference between the brush resistance and the reference brush resistance is within a predetermined normal range. Here, the reference brush resistance is a brush resistance calculated based on an inrush current at the time of starting the fuel pump 32 at the time of vehicle shipment, immediately after that, or after replacement of the fuel pump 32, or immediately after that.

  In this way, the brush resistance when the fuel pump 32 currently in use is new (when the vehicle is shipped or when the fuel pump is replaced) is used as the reference brush resistance, and this reference brush resistance is compared with the current brush resistance. Thus, brush deterioration can be determined. This eliminates the influence of individual differences (manufacturing variation) such as the coil resistance and wiring resistance of the fuel pump 32, and changes in brush resistance from when the fuel pump 32 is new (when the vehicle is shipped or when the fuel pump is replaced). It is possible to accurately determine the presence or absence of brush deterioration by accurately evaluating (change in contact resistance due to brush chipping or wear).

  Hereinafter, processing contents of each routine executed by the fuel pump control device 37 will be described. Note that the processing of each of these routines may be executed by the vehicle control device 19 or the powertrain control device 18.

[Fuel pump fault diagnosis main routine]
The fuel pump failure diagnosis main routine shown in FIG. 3 is executed at a predetermined cycle during a period in which an ignition switch (not shown) is ON. When this routine is started, first, in step 101, output signals from the auxiliary battery voltage sensor 38, the fuel pump coil temperature sensor 39, etc. are read to perform A / D conversion and the like, and in the next step 102, Communication data transmitted / received to / from the vehicle control device 19, the auxiliary battery control device 29, and the powertrain control device 18 is processed.

  Thereafter, the routine proceeds to step 103, where a fuel pump drive command routine of FIG. 4 to be described later is executed, the fuel pump 32 is started while the engine 11 is stopped, and an inrush current when the fuel pump 32 is started is detected.

  Thereafter, the routine proceeds to step 104, where a brush deterioration determination routine shown in FIG. 5 described later is executed to calculate the brush resistance of the motor based on the inrush current when the fuel pump 32 is started up. The presence or absence of brush deterioration is determined depending on whether or not the difference is within a predetermined normal range.

  Thereafter, the process proceeds to step 105, the communication data transmitted / received to / from the vehicle control device 19, the auxiliary battery control device 29, and the powertrain control device 18 are processed, and this routine is terminated.

[Fuel pump drive command routine]
The fuel pump drive command routine shown in FIG. 4 is a subroutine executed in step 103 of the fuel pump failure diagnosis main routine of FIG. When this routine is started, first, at step 201, it is determined whether or not the engine 11 is stopped and the fuel pump 32 is stopped (OFF).

  If it is determined in step 201 that the engine is stopped and the fuel pump is stopped, the process proceeds to step 202, where it is determined whether or not the failure diagnosis execution timing is reached, and the failure diagnosis execution timing is reached. In step 203, the auxiliary battery control device 29 controls the charging voltage and load current of the auxiliary battery 31, and boosts the auxiliary battery 31 voltage, which is the power supply voltage of the fuel pump 32.

  In this way, in a state where the voltage of the auxiliary battery 31 that is the power supply voltage of the fuel pump 32 is increased while the engine is stopped, the process proceeds to step 204, the fuel pump 32 is activated (OFF → ON), and then proceeds to step 205. The count value of the counter CFP that counts the number of times the inrush current of the fuel pump 32 is detected is reset to “0”.

  Thereafter, the process proceeds to step 206, where an inrush current I (i) and a drive voltage V (i), which are drive currents when the fuel pump 32 is started, are detected. Here, i means the number of times the inrush current of the fuel pump 32 is detected.

  Thereafter, the process proceeds to step 207, where the count value of the counter CFP is incremented by “1”. In the next step 208, it is determined whether or not the count value of the counter CFP is equal to or greater than a predetermined value K.

  If it is determined in step 208 that the count value of the counter CFP has not reached the predetermined value K, the process returns to step 206 to detect the inrush current I (i) and the drive voltage V (i) of the fuel pump 32. Then, the process of counting up the count value of the counter CFP (steps 206 and 207) is repeated until the count value of the counter CFP reaches a predetermined value K.

  Thereafter, when it is determined in step 208 that the count value of the counter CFP is equal to or greater than the predetermined value K, the process proceeds to step 209 to stop the boosting of the auxiliary battery 31 voltage, and in the next step 210, the fuel pump 32 is stopped. Is stopped (ON → OFF), and this routine is terminated.

[Brush deterioration judgment routine]
The brush deterioration determination routine shown in FIG. 5 is a subroutine executed in step 104 of FIG. 3 and plays a role as brush deterioration determination means in the claims. When this routine is started, first, at step 301, the brush resistance R is obtained by the following equation using the K inrush currents I (i) and the drive voltage V (i) detected when the fuel pump 32 is started. .

  Strictly speaking, the resistance R is a resistance value including the coil resistance, wiring resistance, and the like of the fuel pump 32. However, the resistance R is a parameter that changes in accordance with the brush resistance. And The brush resistance may be obtained by subtracting the coil resistance, wiring resistance, or the like from the resistance R. The processing in step 301 serves as a brush resistance calculation means in the claims.

  Thereafter, the routine proceeds to step 302, where it is determined whether or not the fuel pump 32 is in a new state depending on whether the vehicle is shipped or immediately after it, or when or when the fuel pump 32 is replaced. If it is determined in step 302 that the fuel pump 32 is in a new state (at the time of vehicle shipment or immediately after that or when the fuel pump 32 is replaced or immediately after that), the routine proceeds to step 303 where the fuel pump 32 is turned on. The brush resistance R obtained in step 301 in the new state is set as the reference brush resistance R0.

R0 = R
This reference brush resistance R0 is stored in a rewritable nonvolatile memory (a rewritable memory that retains stored data even when the vehicle control device 19 is turned off) such as a backup RAM (not shown) of the vehicle control device 19. To do.

On the other hand, if it is determined in step 302 that the fuel pump 32 is not new, the process of step 303 is skipped and the process proceeds to step 304. In step 304, the difference ΔR between the current brush resistance R and the reference brush resistance R0 is obtained, thereby eliminating the influence of individual differences (manufacturing variation) such as the coil resistance and wiring resistance of the fuel pump 32, and the fuel pump. A brush resistance change ΔR (change amount of contact resistance due to brush chipping, wear, etc.) from when 32 is new (when the vehicle is shipped or when the fuel pump is replaced) is obtained.
ΔR = R−R0

  Thereafter, the process proceeds to step 305, where it is determined whether or not the brush resistance change amount ΔR is within a predetermined normal range (K1 ≦ ΔR ≦ K2). As a result, if it is determined that the brush resistance change amount ΔR is within the normal range (K1 ≦ ΔR ≦ K2), the process proceeds to step 306, where it is determined that there is no brush deterioration, and the fuel pump failure flag Xfail is set to “0”. This routine is terminated while resetting to "."

  On the other hand, if it is determined in step 305 that the brush resistance change amount ΔR is out of the normal range (ΔR <K1 or K2 <ΔR), the process proceeds to step 307, where it is determined that there is brush deterioration. The fuel pump failure flag Xfail is set to “1”, a warning is displayed on the warning display unit 40 to warn the driver, and the abnormality information (abnormality code, etc.) is rewritten to the backup RAM of the vehicle control device 19. Store in the possible non-volatile memory and terminate this routine.

  In the present embodiment described above, considering that the main cause of the failure of the fuel pump 32 is brush deterioration, considering that the brush resistance changes depending on the degree of brush deterioration, and further, after starting the fuel pump 32 In consideration of the fact that it is difficult to accurately detect the brush current due to the influence of the back electromotive force and rotation speed of the motor, the fuel pump is hardly affected by the back electromotive force and rotation speed of the motor. Since the inrush current at the time of start-up 32 is detected and the brush resistance is calculated from this inrush current, the brush resistance can be calculated with high accuracy, and the presence or absence of brush deterioration is accurately determined from this brush resistance. Therefore, the failure determination accuracy of the fuel pump 32 can be improved.

  In addition, in this embodiment, the brush resistance when the currently used fuel pump 32 is new is detected and used as a reference brush resistance, and the difference between the reference brush resistance and the current brush resistance is a predetermined value. Since the presence or absence of brush deterioration is determined based on whether or not it is in the normal range, the influence of individual differences (manufacturing variation) such as coil resistance and wiring resistance of the fuel pump 32 is eliminated, and when the fuel pump 32 is new. Therefore, it is possible to determine the presence or absence of brush deterioration by accurately evaluating the amount of change in brush resistance, and to further improve the failure determination accuracy of the fuel pump 32.

  By the way, if the brush resistance is calculated based on the inrush current when the fuel pump 32 is started in conjunction with the start of the engine 11, it is affected by the drive voltage of the starter (AC motor 12) that starts the engine 11. Since the drive voltage of the fuel pump 32 may fluctuate and the inrush current of the fuel pump 32 may fluctuate, the detection accuracy of the inrush current may decrease, and the accuracy of the brush resistance calculated from the inrush current may decrease. There is sex.

  As a countermeasure, in this embodiment, since the brush resistance is calculated based on the inrush current when the fuel pump 32 is started while the engine is stopped, the fuel pump 32 is not affected by the drive voltage of the starter. The inrush current can be detected with high accuracy while the drive voltage is stable, and the brush resistance can be accurately calculated from the detected value of the inrush current.

  Further, in this embodiment, the inrush current when the fuel pump 32 is started up with the power supply voltage (auxiliary battery 31 voltage) of the fuel pump 32 boosted is detected, and the brush resistance is calculated from the detected value. Therefore, the inrush current detection accuracy can be further increased by increasing the inrush current value, and the brush resistance calculation accuracy based on the inrush current can be further improved.

  However, according to the present invention, the inrush current when the fuel pump 32 is started in conjunction with the start of the engine 11 is detected to calculate the brush resistance, or the power supply voltage of the fuel pump 32 (auxiliary battery 31 voltage). The brush resistance may be calculated by detecting an inrush current when the fuel pump 32 is started in a state where the pressure is not increased.

  In the above embodiment, the presence or absence of brush deterioration is determined based on whether or not the difference between the brush resistance and the reference brush resistance is within the normal range. However, the method for determining brush deterioration may be changed as appropriate. For example, the presence or absence of brush deterioration may be determined based on whether or not the ratio between the brush resistance and the reference brush resistance is within a normal range.

  In addition, it is not always necessary to use the reference brush resistance (brush resistance calculated at the time of vehicle shipment or immediately after that, or at the time of replacement of the fuel pump 32 or immediately after that). The presence or absence may be determined.

  Moreover, although the said Example is an Example which applied this invention to the hybrid electric vehicle, it can apply also to the vehicle carrying an idle stop system, and of course, the vehicle which is not carrying an idle stop system. It can also be applied to.

1 is a diagram schematically showing the overall configuration of a vehicle drive system in an embodiment of the present invention. It is a figure which shows roughly the circuit structure of a fuel pump control apparatus. It is a flowchart explaining the flow of a process of a fuel pump failure diagnosis main routine. It is a flowchart explaining the flow of a process of a fuel pump drive command routine. It is a flowchart explaining the flow of a process of a brush deterioration determination routine.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... AC motor, 13 ... Torque converter, 14 ... Transmission, 18 ... Powertrain control device, 19 ... Vehicle control device, 28 ... Inverter, 29 ... Auxiliary battery control device, 30 DESCRIPTION OF SYMBOLS ... High voltage DC battery, 31 ... Auxiliary battery, 32 ... Fuel pump, 37 ... Fuel pump control apparatus (brush resistance calculation means, brush deterioration determination means), 40 ... Warning display part, 43 ... Drive circuit part, 46 ... Current detection Resistor, 47... Drive current detector

Claims (4)

In a fuel pump failure diagnosis device using a brushed motor as a drive source of a fuel pump that pumps up fuel in a fuel tank and supplies it to an internal combustion engine,
Brush resistance calculating means for calculating the brush resistance of the motor based on the inrush current at the start of the fuel pump;
A failure diagnosis device for a fuel pump, comprising: brush deterioration determination means for determining brush deterioration of the motor based on the brush resistance calculated by the brush resistance calculation means.   The brush deterioration determining means uses, as a reference brush resistance, a brush resistance calculated by the brush resistance calculating means at the time of vehicle shipment or immediately after that, or when the fuel pump is replaced or immediately after that, and the reference brush resistance and the brush resistance calculating means. 2. The fuel pump failure diagnosis apparatus according to claim 1, wherein the brush resistance of the motor is determined by comparing with the brush resistance calculated this time.   3. The fuel pump failure according to claim 1, wherein the brush resistance calculating unit calculates the brush resistance based on an inrush current when the fuel pump is started while the internal combustion engine is stopped. 4. Diagnostic device.   4. The brush resistance calculation unit calculates the brush resistance based on an inrush current when the fuel pump is started in a state where the power supply voltage of the fuel pump is boosted. 5. The fuel pump failure diagnosis device according to claim 1.

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