JP5988753B2 - Control device - Google Patents

Description

  The present invention relates to a control device for a vehicle equipped with an internal combustion engine and an automatic transmission.

  Modern automobiles are often equipped with automatic transmissions. As an automatic transmission for a vehicle, a continuously variable transmission provided with a torque converter and a belt-type continuously variable transmission mechanism is often employed.

  In the so-called coast driving state where the driver takes his foot off the accelerator pedal and the throttle valve is 0 or almost zero, the engine speed (or the CVT primary pulley speed) It is customary to set a lower limit value for CVT and to control the CVT reduction ratio (speed ratio) so that the engine speed does not fall below the lower limit value (see, for example, Patent Document 1 below) ).

  It is also well known to perform fuel cut that temporarily stops fuel injection of the internal combustion engine during coasting (see, for example, Patent Document 2 below). In general, when the accelerator pedal depression amount is 0 or less than a threshold value close to 0 and the engine speed is equal to or higher than the fuel cut permission speed, the fuel cut is performed assuming that the fuel cut condition is satisfied. Then, when any fuel cut end condition is satisfied, such as when the accelerator pedal depression amount exceeds the threshold value, or the engine speed decreases to the fuel cut return speed, the fuel cut ends and the fuel injection resumes. .

JP 2010-151154 A Japanese Patent Laid-Open No. 10-030477

  In order to improve fuel efficiency and prolong the fuel cut period, the lower limit value of the engine speed during coasting is set relatively high. In other words, during coasting, the reduction ratio of the automatic transmission is controlled as small as possible (low gearing).

  However, in this case, a deviation occurs from the lower limit value during normal traveling that is set to be low. As a result, when the fuel cut condition is satisfied and the fuel cut is entered, the reduction in the output torque of the engine due to the stop of the fuel supply and the reduction in the reduction ratio of the automatic transmission will cause a sudden decrease in the vehicle traveling speed. Some passengers, including the driver, felt a shock.

  The present invention has been made by paying attention to the above-mentioned points for the first time, and intends to suppress giving a feeling of rapid deceleration of the vehicle speed to the passenger at the time of fuel cut.

The present invention controls a vehicle equipped with an internal combustion engine and an automatic transmission, and at least whether or not the internal combustion engine is currently under fuel cut and until fuel cut is started after the fuel cut condition is satisfied. The engine speed during coasting is set with a higher lower limit than when the fuel is being cut or when the fuel is being cut or not. The gear ratio of the automatic transmission is controlled so that the engine speed does not fall below the lower limit rotational speed, and when the delay time is before the fuel cut is started, compared to when the fuel is being cut or not being delayed. The controller is configured to control the speed ratio of the automatic transmission so that the engine speed during traveling does not fall below the lower limit speed while setting a high lower speed limit .

  In other words, after the fuel cut condition is satisfied, during the delay time from the start of the fuel cut that actually stops fuel injection, the lower limit value of the engine speed is increased from that during normal driving, and the reduction ratio of the automatic transmission is made as much as possible. I tried to make it smaller. With such a configuration, it is possible to reduce the risk of a sudden deceleration of the vehicle speed as the fuel cut starts.

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress giving a passenger the rapid deceleration feeling of a vehicle speed at the time of fuel cut.

The figure which shows the whole structure of the internal combustion engine for vehicles in one Embodiment of this invention. The figure which shows the structure of the drive system in the embodiment. The figure which shows the electric circuit for the control apparatus in the same embodiment to operate the compressor of an air conditioner, and various electric loads. The shift diagram of the automatic transmission which the control apparatus in the embodiment controls. The flowchart which shows the example of the procedure of the process which the control apparatus of the embodiment performs. The figure which illustrates transition of the lower limit of engine speed in the modification of the present invention.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of an internal combustion engine for a vehicle in the present embodiment.

  The internal combustion engine in the present embodiment is a spark ignition gasoline engine and includes a plurality of cylinders 1 (one of which is shown in FIG. 1). In the present embodiment, in particular, a two-cylinder engine is assumed. In the vicinity of the intake port of each cylinder 1, an injector 11 for injecting fuel is provided. A spark plug 12 is attached to the ceiling of the combustion chamber of each cylinder 1. The spark plug 12 receives spark voltage generated by the ignition coil and causes spark discharge between the center electrode and the ground electrode. The ignition coil is integrally incorporated in a coil case together with an igniter that is a semiconductor switching element.

  The intake passage 3 for supplying intake air takes in air from the outside and guides it to the intake port of each cylinder 1. On the intake passage 3, an air cleaner 31, an electronic throttle valve 32, a surge tank 33, and an intake manifold 34 are arranged in this order from the upstream.

  The exhaust passage 4 for discharging the exhaust guides the exhaust generated as a result of burning the fuel in the cylinder 1 from the exhaust port of each cylinder 1 to the outside. An exhaust manifold 42 and an exhaust purification three-way catalyst 41 are disposed on the exhaust passage 4.

  FIG. 2 shows an example of a drive system provided in the vehicle. This drive system includes a torque converter 7 and automatic transmissions 8 and 9. In particular, in the present embodiment, a forward / reverse switching device 8 using a planetary gear mechanism and a belt type CVT 9 which is a type of continuously variable transmission are adopted as components of the automatic transmissions 8 and 9.

  The rotational torque output from the internal combustion engine is input from the crankshaft of the internal combustion engine to the pump impeller 71 on the input side of the torque converter 7 and transmitted to the turbine runner 72 on the output side. The rotation of the turbine runner 72 is transmitted to the drive shaft 94 of the CVT 9 via the forward / reverse switching device 8 and rotates the driven shaft 95 through a shift in the CVT 9. The rotation of the driven shaft 95 is transmitted to the output gear 101. The output gear 101 meshes with the ring gear 102 of the differential device, and rotates the axle 103 and the drive wheels (not shown) via the differential device.

  The torque converter 7 includes a lockup mechanism. The lock-up mechanism is known in this field, and a lock-up clutch 73 that fastens the input side and the output side of the torque converter 7 so as not to rotate relative to each other, and an operation for switching the connection of the lock-up clutch 73. The lock-up solenoid valve 57 that controls the hydraulic pressure (hydraulic pressure) is used as an element. The lockup solenoid valve 57 is a flow rate control valve that receives an opening degree control signal l that is a control input and changes the opening degree.

  In a vehicle equipped with CVT 9, when the vehicle speed is a predetermined value (for example, 10 km / h) or more, the torque converter 7 is almost always locked up. When the vehicle speed is equal to or lower than the predetermined value, the lockup of the torque converter 7 is released. During lockup, the lockup clutch 73 is pressed against the torque converter cover 74 and rotates together with the torque converter cover 74. The engine torque input to the input side (drive plate) of the torque converter 7 at the time of lock-up is output from the torque converter cover 74 via the lock-up clutch 73 and thus to the forward / reverse switching device 8. Communicated directly to. At the time of lockup, the speed ratio, which is the ratio of the output side rotational speed of the torque converter 7 to the input side rotational speed, is 1.

  When the lockup is not performed, the lockup clutch 73 is separated from the torque converter cover 74. At the time of non-lock-up, the engine torque input to the input side of the torque converter 7 is transmitted from the torque converter cover 74 to the pump impeller 71 and the turbine 72 and is transmitted to the forward / reverse switching device 8. At the time of non-lock-up, the speed ratio of the torque converter 7 becomes smaller or larger than 1 depending on the driving state.

  In the forward / reverse switching device 8, the sun gear 81 communicates with the turbine runner 72, and the ring gear 82 communicates with the drive shaft 94. Between the planetary carrier 83 that supports the planetary gear 831 and the transmission case, a forward brake 84 that is a hydraulic clutch that can be connected and disconnected is interposed. Further, a reverse clutch 85, which is a hydraulic clutch capable of switching connection / disconnection, is also interposed between the planetary carrier 83 and the sun gear 81 (or the output side of the torque converter 7).

  In the D range of the traveling range, the forward brake 84 is engaged and the reverse clutch 85 is disconnected. As a result, the rotation of the output shaft of the torque converter 7 is reversed and decelerated and transmitted to the drive shaft 94 for forward travel. In turn, in the R range, the reverse clutch 85 is engaged and the forward brake 84 is disconnected. As a result, the sun gear 81 and the planetary carrier 83 rotate integrally, and the output shaft of the torque converter 7 and the drive shaft 94 are directly connected to perform reverse travel. A solenoid valve (not shown) that controls the hydraulic pressure for driving the forward brake 84 or the reverse clutch 85 to connect / disconnect is a flow rate control valve that receives a control signal m and changes its opening.

  In the N range and P range, which are non-traveling ranges, both the forward brake 84 and the reverse clutch 85 are disconnected.

  The CVT 9 includes a primary pulley (driving pulley) 91, a secondary pulley (driven pulley) 92, and a belt 93 wound around the pulleys 91 and 92 as elements. The primary pulley 91 is disposed behind the movable sheave 912, a fixed sheave 911 fixed to the drive shaft 94, a movable sheave 912 supported on the drive shaft 91 so as to be displaceable in the axial direction via a roller spline. A hydraulic servo 913 is provided, and the reduction ratio can be changed steplessly by operating the hydraulic servo 913 and displacing the movable sheave 912. The secondary pulley 92 is disposed on the back of the movable sheave 922, a fixed sheave 921 fixed to the driven shaft 95, a movable sheave 922 supported on the driven shaft 95 via a roller spline so as to be displaceable in the axial direction. A hydraulic servo 923 is provided, and a belt thrust necessary for torque transmission is applied by operating the hydraulic servo 923 and displacing the movable sheave 922.

  The vehicle is accompanied by a plurality of external loads. Specific examples of external loads include air conditioner refrigerant compression compressors, various electrical loads such as air conditioner blowers, defoggers for removing fog on rear glass, audio equipment, car navigation systems, and lighting (heads) Lamps, tail lamps, fog lamps, turn signals (turn signal lamps, etc.), radiator fans for cooling cooling water, electric power steering devices, and the like.

  The compressor of the air conditioner is rotationally driven in response to transmission of rotational torque from the crankshaft of the internal combustion engine, and compresses the refrigerant. As shown in FIG. 3, a magnet clutch 61 that can be connected and disconnected is interposed between the compressor and the crankshaft. When operating the air conditioner, the magnet clutch 61 is energized with current from the in-vehicle battery 62 and / or the alternator 63 and the magnet clutch 61 is engaged. On the contrary, when the air conditioner is not operated, the magnet clutch 61 is not energized and the clutch 61 is disconnected. Energization and disconnection of the magnet clutch 61 is performed by turning ON / OFF the relay switch 64.

  A motor 66 that rotationally drives the blower for blower and a heating wire heater 68 laid on the rear glass as a defogger operate by receiving power supply from the battery 62 and / or the alternator 63. Energization and interruption of the motor 66 and the heater 68 are performed by turning on / off the relay switch 67 or starting / extinguishing a semiconductor switching element (power device represented by a power transistor, power MOSFET, etc.) 69.

  Audio devices, car navigation systems, illumination lights, motors for rotating the radiator fan, and other electrical loads are the same as described above.

  An alternator 63, which is a source of power supply to the electric load, is rotationally driven in response to transmission of rotational torque from the crankshaft of the internal combustion engine to generate electric power. The alternator 63 is connected to the crankshaft via a winding transmission mechanism having a belt and a pulley as elements. The magnitude of the voltage generated and output by the alternator 63 can be controlled via the regulator 65. The regulator 65 is a known IC type attached to the alternator 63 and performs a switching operation for switching ON / OFF the energization of the field coil of the alternator 63.

  The output voltage of the alternator 63, that is, the voltage induced in the stator coil of the alternator 63 increases in proportion to fDUTY which is the DUTY ratio of the field current flowing through the field coil. The regulator 65 receives a signal r for instructing an output voltage of an alternator from an ECU (Electronic Control Unit) 0, and performs PWM control for adjusting fDUTY so as to realize the instructed output voltage. With this PWM control, the power generated by the alternator 63 can be increased or decreased. The amount of power generated by the alternator 63, in other words, the amount of charge to the battery 62 and / or the amount of power supplied to the electrical load increases as fDUTY increases and decreases as fDUTY decreases.

  In the regulator 65 of the vehicular alternator 63 that is widely used, the output voltage of the alternator 63 can be switched to two stages, for example, 14.5V or 12.8V. In this case, the ECU 0 inputs to the regulator 65 a signal r that instructs whether the output voltage of the alternator 63 is HI potential = 14.5V or LO potential = 12.8V.

  As the regulator 65, a linear regulator capable of continuously changing the output voltage of the alternator 63 within a predetermined range, for example, between 12V and 15.5V may be employed. In this case, the ECU 0 inputs a signal r that instructs the regulator 65 to set the output voltage of the alternator 63 to any value within the range.

  The LO potential or minimum output voltage of the alternator 63 is preferably set to a voltage lower than the voltage of the battery 62 or a low voltage close to the voltage of the battery 62. The battery voltage varies depending on the state of charge of the battery 62 and the like, but is usually a predetermined voltage, for example, 12 V or more.

  The alternator 63 becomes a mechanical load when viewed from the internal combustion engine. When the output voltage of the alternator 63 exceeds the voltage of the battery 62, the battery 62 is charged and power is supplied from the alternator 63 to the electric load. That is, the alternator 63 performs the work of generating electric energy by consuming energy of rotation of the crankshaft. The amount of charge to the battery 62 and the amount of power supplied to the electrical load depend on the potential difference between the output voltage of the alternator 63 and the battery voltage.

  Conversely, when the output voltage of the alternator 63 is less than or close to the battery voltage, the battery 62 is not charged, and no power is supplied from the alternator 63 to the electric load (power supply from the battery 62 to the electric load). Sometimes). That is, the alternator 63 does not perform work that consumes the energy of rotation of the crankshaft, or the work is reduced.

  In short, when a high output voltage is commanded from the ECU 0 to the regulator 65, the mechanical load of the alternator 63 with respect to engine rotation increases, and when a low output voltage is commanded, the mechanical load of the alternator 63 with respect to engine rotation decreases.

  Incidentally, the upper limit of the power generation amount by the alternator 63 is determined according to the vehicle speed. The higher the vehicle speed, the higher the upper limit of power generation.

  The ECU 0 as the control device of the present embodiment is a microcomputer system having a processor, a memory, an input interface, an output interface, and the like.

  The input interface includes a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed of the vehicle, a crank angle signal (N signal) b output from an engine rotation sensor that detects the rotation angle of the crankshaft and the engine speed, An accelerator opening signal c output from a sensor that detects the amount of depression of the accelerator pedal or the opening of the throttle valve 32 as an accelerator opening (so-called requested load, requested output), an amount of depression of the brake pedal, Brake pedaling amount signal d output from a sensor that detects the master cylinder pressure, intake air temperature / intake pressure output from a temperature / pressure sensor that detects intake air temperature and intake pressure in the intake passage 3 (particularly, surge tank 33). Signal e, coolant temperature signal f output from a coolant temperature sensor for detecting the coolant temperature of the engine, intake camshaft or exhaust The cam angle signal (G signal) g output from the cam angle sensor at multiple cam angles of the shaft and the index (battery current, battery voltage, and / or battery temperature) suggesting the charging state of the in-vehicle battery 62 are detected. An operation request signal s regarding whether or not to activate the battery state signal h, the air conditioner, and various electric loads output from the sensor is input. The operation request signal s is a signal issued from an operation switch (or control panel) for each air conditioner or electric load that is manually operated by a driver or a passenger who desires to operate the air conditioner and various electric loads. Or a signal issued from an auto air conditioner ECU or the like that controls the auto air conditioner system.

  From the output interface, an ignition signal i for the igniter of the spark plug 12, a fuel injection signal j for the injector 11, an opening operation signal k for the throttle valve 32, and a lock for connection / disconnection switching of the lockup clutch 73. Opening control signal 1 for up solenoid valve 57, opening control signal m for solenoid valve for switching connection / disconnection of forward brake 84 or reverse clutch 85, reduction ratio control signal n for CVT 9, magnet clutch 61 Clutch engagement signal o for the switch 64 on the electric circuit energizing the motor, and the switch ON signals o, p, q for the switches 67, 69 on the electric circuit energizing the motor 66, heater 68 and other electric loads A voltage instruction signal r is sent to a voltage regulator 65 that controls the voltage generated by 63. To output.

  The processor of the ECU 0 interprets and executes a program stored in the memory in advance, calculates operation parameters, and controls the operation of the internal combustion engine. The ECU 0 acquires various information a, b, c, d, e, f, g, h, and s necessary for operation control of the internal combustion engine via the input interface, knows the engine speed, and fills the cylinder 1 Estimate the amount of intake air. Based on the engine speed and intake air amount, etc., the required fuel injection amount, fuel injection timing (including the number of times of fuel injection for one combustion), fuel injection pressure, ignition timing, and torque converter 7 lock-up are adjusted. Whether to perform, reduction ratio of automatic transmissions 8 and 9, air conditioner compressor ON / OFF, blower ON / OFF, defogger ON / OFF, other various electric loads ON / OFF, output by alternator 63 Various operating parameters such as voltage are determined. As the operation parameter determination method itself, a known method can be adopted. The ECU 0 applies various control signals i, j, k, l, m, n, o, p, q, r corresponding to the operation parameters via the output interface.

  The ECU 0 of this embodiment is configured so that the engine speed (or the CVT 9) is adjusted in a so-called coast driving state in which the driver removes his / her foot from the accelerator pedal and the throttle valve opening degree is zero or substantially zero. A lower limit value is set for the rotation speed of the primary pulley 91, and the reduction ratio of the CVT 9 is controlled so that the engine speed does not fall below the lower limit value.

  FIG. 4 is an example of a shift diagram showing the transition of the change in the reduction ratio of the CVT 9 during coasting. In FIG. 4, the solid line is the shift line, the broken line is the lower limit value of the engine speed during normal travel, and the chain line is the lower limit value of the engine speed during coast travel. The lower limit value of the engine speed during normal running is set near the limit at which engine stall does not occur. On the other hand, the lower limit value of the engine speed during coasting is set higher than that during normal traveling. Although the lower limit value of the engine speed during coasting is substantially constant, strictly speaking, it has a tendency of decreasing to the left (rising to the right) that varies according to the vehicle speed, which decreases as the vehicle speed decreases.

  In a situation where the vehicle speed is relatively high, the vehicle speed decreases with the engine speed (so that the vehicle speed and the engine speed are substantially proportional). That is, the reduction ratio of CVT 9 is kept substantially constant. However, when the vehicle speed decreases and reaches the lower limit value, the vehicle speed is decreased while gradually reducing the reduction ratio of the CVT 9 (while changing the gear ratio to low gear) so that the engine speed does not fall below the lower limit value. .

  FIG. 5 shows a procedure of processing executed when the ECU 0 determines the lower limit value of the engine speed during coasting. First, the ECU 0 determines whether the air conditioner is currently operating, more specifically, whether the magnet clutch 61 is engaged (step S1), and selects the lower limit value A accordingly (step S2). , S3). The lower limit A1 when the magnet clutch 61 is engaged is higher than the lower limit A2 when the magnet clutch 61 is not engaged. This is intended to prevent engine stall due to compressor load.

  Next, the ECU 0 determines whether or not the driver is currently stepping on the brake pedal (step S4), and selects the lower limit value B accordingly (steps S5 and S6). The lower limit B1 when the brake pedal is depressed is higher than the lower limit B2 when the brake pedal is not depressed. In addition to the intention of preventing engine stall due to braking, this is to reduce the reduction ratio of the CVT 9 (the transmission ratio is lower gear side) in situations where the vehicle is currently on a downhill road. This is also to strengthen the engine brake and suppress the acceleration of the vehicle according to the driver's intention. The lower limit value A1 is higher than the lower limit value B1.

  Subsequently, the ECU 0 determines whether or not the internal combustion engine is currently cutting fuel (step S7), and selects the lower limit value C accordingly (steps S8 and S9). The lower limit C1 when the fuel is being cut is higher than the lower limit C2 when the fuel is not being cut. In the fuel cut that temporarily stops fuel injection from the injector 11 (and ignition by the spark plug 12), the amount of depression of the accelerator pedal is 0 or below a threshold value close to 0, and the engine speed is the fuel cut permission speed. This is triggered by the fact that the fuel cut conditions such as described above are satisfied. The fuel cut ends when one of the fuel cut end conditions is satisfied, such as when the accelerator pedal depression amount exceeds a threshold or the engine speed decreases to the fuel cut return speed. The reason why the lower limit C1 is higher than C2 is that the reduction ratio of the CVT 9 is controlled so as to suppress the decrease in the engine speed, thereby extending the fuel cut period to increase the fuel consumption.

  Further, the ECU 0 determines whether or not the internal combustion engine is currently in a delay time before the fuel cut is started (step S10), and selects the lower limit value D accordingly (steps S11 and S12). The lower limit value D1 when it is during the delay time is higher than the lower limit value D2 when it is not during the delay time. Even if the fuel cut condition is satisfied, the fuel cut does not start immediately but waits for a certain delay time to elapse. The lower limit value D1 being higher than D2 means that the fuel cut will be started soon during the delay time, and before the output torque of the internal combustion engine is lowered because the fuel supply is actually cut off. The intention is to reduce the reduction ratio of the CVT 9 as much as possible (transition of the transmission ratio to the low gear side). The lower limit value C1 is higher than the lower limit value D1.

  In addition, the ECU 0 selects the lower limit value E according to the amount of power generated by the alternator 63, that is, the magnitude of the output voltage of the alternator 63 (the value of the voltage command signal r or fDUTY) (step S13). The lower limit E increases as the amount of power generated by the alternator 63 increases, that is, as the output voltage of the alternator 63 increases. This is to make the feeling of deceleration of the vehicle speed constant regardless of the amount of power generated by the alternator 63.

  Then, the ECU 0 sets the maximum of the lower limit values A, B, C, D, and E as the lower limit value of the engine speed during coasting (step S14). Here, A (A1 or A2), B (B1 or B2), C (C1 or C2), and D (D1 or D2) other than E are functions of the vehicle speed that decrease as the vehicle speed decreases.

  In the present embodiment, the vehicle equipped with the internal combustion engine and the automatic transmissions 8 and 9 is controlled, and at least whether or not the fuel cut of the internal combustion engine is currently in progress and the fuel cut after the fuel cut condition is satisfied. Judgment is made whether or not it is during the delay time until the start of the vehicle, and if it is during fuel cut or delay time, set a lower lower limit rotation speed than when not, and during coast driving The control device 0 is configured to control the speed ratio of the automatic transmissions 8 and 9 so that the engine speed of the engine does not fall below the lower limit speed.

  According to the present embodiment, after the fuel cut condition is satisfied, the lower limit value of the engine speed is set higher than that during normal driving during the delay time from the start of fuel cut to actually stopping fuel injection, and the automatic transmission is decelerated. The ratio can be made as small as possible, and the risk of sudden deceleration of the vehicle speed as the fuel cut starts can be reduced.

The present invention is not limited to the embodiment described in detail above. For example, as shown in FIG. 6, the lower limit value D1 of the engine speed during the delay time from when the fuel cut condition is satisfied t ₀ to when the fuel cut is started t ₁ elapses from the time t ₀ when the fuel cut condition is satisfied. It may be variable so as to increase (become higher) as the time elapses. The speed of the increase may not be constant (linear). Immediately after the fuel cut condition is satisfied t _{0, if} the lower limit value D1 is increased rapidly and then gradually increased, a great feeling of deceleration can be obtained at the moment when the driver removes his / her foot from the accelerator pedal. A drive feeling that matches your will.

  The automatic transmission is not limited to the belt type CVT. The present invention can also be applied to a vehicle equipped with a stepped transmission.

  In addition, the specific configuration of each unit, the processing procedure, and the like can be variously modified without departing from the spirit of the present invention.

  The present invention can be used for control of a vehicle including an internal combustion engine and an automatic transmission.

0 ... Control unit (ECU)
8, 9 ... Automatic transmission (forward / reverse switching device, CVT)

Claims (1)

Control a vehicle equipped with an internal combustion engine and an automatic transmission,
At least, it is determined whether or not the fuel cut of the internal combustion engine is currently in progress, and whether or not the delay time until the fuel cut is started after the fuel cut condition is satisfied,
When the fuel is being cut, a higher lower limit speed is set than when the fuel is being cut or the delay time is not being set, and the engine speed during coasting is automatically set so as not to fall below the lower limit speed. While controlling the gear ratio of the transmission,
Even during the delay time before the start of fuel cut, the engine speed during driving is lower than the lower limit speed after setting a higher lower limit speed than when the fuel is cut or not during the delay time. A control device for controlling a gear ratio of an automatic transmission so as not to occur.

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