JP5614541B2 - Electric vehicle - Google Patents

Description

  The present invention relates to an electric vehicle.

  2. Description of the Related Art Conventionally, an electric vehicle that travels by driving a motor by supplying power from a battery may travel without being driven by the motor, such as during deceleration. If the driver suddenly drives the accelerator pedal during deceleration due to vehicle inertia when the driver does not depress the accelerator pedal, a so-called chip-in shock occurs in the vehicle. This tip-in shock will be described with reference to FIG. FIG. 6 is a schematic diagram showing that the rotation of the motor is transmitted to the drive wheels via the motor-side gear G1 and the drive wheel-side gear G2 in the vehicle drive system.

  As shown in FIG. 6 (1), at the time of deceleration, the rotational speed of the gear G2 on the driving wheel (hereinafter referred to as the rotational speed of the driving wheel) is determined from the rotational speed of the gear G1 on the motor side (hereinafter referred to as the rotational speed of the motor). Since the driving wheel side gear G2 pushes the motor side gear G1 and the motor side gear G1 rotates, the rotation is transmitted from the driving wheel side gear G2 to the motor side gear G1. . If the accelerator pedal is suddenly depressed (chip-in) in this state, the rotation speed of the motor becomes relatively higher than the rotation speed of the driving wheel, and the rotation is transmitted from the gear G1 on the motor side to the gear G2 on the driving wheel side. It suddenly changes to the state. When the gear changes suddenly in this way, the motor-side gear G1 suddenly speeds up rotation, and as shown in FIG. 6 (2), the tooth surface opposite to the tooth surface contacted at the time of deceleration due to the backlash (play) of the gear. They collide with each other, and are reversed by collision and collide further. In this way, the gear vibrates by repeatedly colliding and reversing between the tooth surfaces. If it does so, it will resonate with the suspension of a drive system by the vibration by the collision of these gears. Thereby, vibration (shock) is generated in the vehicle. This shock is a so-called chip-in shock.

  Such a tip-in shock is transmitted to the vehicle as vibrations, thereby reducing the occupant's feeling.

  In order to reduce such a shock, conventionally, at the time of tip-in, the torque at the time of acceleration is reduced to reduce the impact at the time of collision between the motor-side gear G1 and the drive wheel-side gear G2 (for example, , See Patent Document 1).

Japanese Patent No. 3575479 (Claim 1 etc.)

  However, even if the torque at the time of acceleration is reduced in this way, there is a problem that vibration due to resonance with the suspension system due to impact does not occur, and a decrease in occupant feeling cannot be suppressed. Furthermore, since the vehicle speed that has been accelerated is reduced by reducing the torque during acceleration, there is a problem that the feeling of the driver is also reduced.

  Accordingly, an object of the present invention is to solve the above-described problems of the prior art, and to provide an electric vehicle that can suppress a decrease in feeling due to a tip-in shock.

  An electric vehicle according to the present invention includes a traveling motor driven by power supply from a battery, and driving wheels driven by the traveling motor via gears, and is set based on a required torque requested by a driver. In the electric vehicle in which the traveling motor is driven based on the driving torque, the traveling wheel is driven from a state where the rotational speed of the gear on the driving wheel is relatively higher than the rotational speed of the gear on the traveling motor side. When the rotational speed of the gear on the motor side is relatively higher than the rotational speed of the gear on the drive wheel side, the rotational speed of the gear on the drive wheel and the rotational speed of the gear on the travel motor A rotational speed difference detection unit that detects a rotational difference between the driving motor and the rotational speed of the gear of the traveling motor is higher than the rotational speed of the gear of the driving wheel based on the detected rotational speed difference. Drive torque greater than the required torque of Characterized in that it comprises a torque setting unit for setting a click.

  In the present invention, from the state where the rotational speed of the gear on the driving wheel side is relatively higher than the rotational speed of the gear on the traveling motor side, the rotational speed of the gear on the traveling motor side is relatively relative to the driving wheel. When the rotational speed of the side gear is higher than the rotational speed of the driving wheel, a tip-in shock may occur. Therefore, when the rotational speed of the traveling motor is higher than the rotational speed of the driving wheel. A driving torque larger than the required torque can be set, and a decrease in feeling due to resonance of the driving system due to a gear collision can be suppressed.

  As a preferred embodiment of the present invention, from the state where the rotational speed of the gear on the drive wheel side is relatively higher than the rotational speed of the gear on the traveling motor side, the rotational speed of the gear on the traveling motor side is relatively In particular, the case where the rotational speed of the gears on the drive wheel side is higher is the case where the vehicle is switched from the deceleration state to the acceleration.

  An addition value setting unit is provided for setting a torque addition value to be added to the required torque based on the calculated rotational speed difference, and the torque setting unit adds the torque addition value and the required torque value. It is preferable to set the driving torque larger than the required torque. Thus, the drive torque can be easily set by setting the torque addition value and adding the torque addition value to the required torque.

  A determination unit configured to determine whether the calculated rotation speed difference is equal to or greater than a threshold; and when the determination unit determines that the rotation speed difference is equal to or greater than the threshold, the addition value setting unit It is preferable to set the torque addition value based on the number difference. When the rotational speed difference is equal to or larger than the threshold value, the control for reducing the feeling is suppressed by setting the added value based on the rotational speed difference.

  It is preferable that the addition value setting unit sets the torque addition value to be added to the required torque based on an integral value obtained by integrating the rotation speed difference. By setting the torque addition value based on the integral value, it is possible to remove noise and set a more appropriate torque addition value.

  According to the electric vehicle of the present invention, it is possible to achieve an excellent effect that it is possible to suppress a decrease in feeling due to a tip-in shock.

It is a mimetic diagram for explaining an electric vehicle concerning this embodiment. It is a block diagram for demonstrating the control part concerning this embodiment. It is a graph which shows the relationship between a rotation speed and a torque addition value. It is a flowchart which shows the control process concerning this embodiment. It is a graph which shows the control result concerning this embodiment. It is a schematic diagram of the drive system for demonstrating a chip in shock.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, an electric vehicle 1, which is an example of an electric vehicle, includes a traveling motor 2, and the traveling motor 2 is connected to a front wheel side drive shaft 4 via a speed reducer 3. The drive shaft 4 is provided with drive wheels 5 at both ends. The electric vehicle 1 is configured to be able to travel using a travel motor 2 as a drive source. When the travel motor 2 is driven and rotated, the drive shaft 4 rotates via the speed reducer 3 so that the drive wheels 5 rotate. The electric vehicle 1 travels.

  The electric vehicle 1 is equipped with a traveling battery (secondary battery) 6. The traveling battery 6 is electrically connected to the traveling motor 2 via an inverter 7. The traveling motor 2 is driven by electric power supplied from the traveling battery 6.

  Further, the electric vehicle 1 is provided with an ECU 10 that performs integrated control of the vehicle. The ECU 10 will be described with reference to FIG.

  As shown in FIG. 2, the ECU 10 includes a torque setting unit 11 that sets a driving torque that is a torque for driving the traveling motor 2. The torque setting unit 11 acquires the requested torque requested by the driver from the accelerator opening detected by the accelerator opening detecting unit S1, and normally outputs the requested torque as a driving torque for driving the traveling motor. On the other hand, at the time of tip-in (details will be described later), the torque setting unit 11 sets the drive torque to be larger than the required torque requested by the driver, and suppresses resonance due to the collision between the gears.

  That is, since the rotational speed of the driving wheel is relatively higher than the rotational speed of the motor during deceleration, the rotation is transmitted from the driving wheel side gear G2 to the motor side gear G1. If the accelerator pedal is suddenly depressed (chip-in) in this state, the rotation speed of the motor becomes relatively higher than the rotation speed of the driving wheel, and the rotation is transmitted from the gear G1 on the motor side to the gear G2 on the driving wheel side. It suddenly changes to the state. With this sudden change, the tooth surfaces opposite to the tooth surfaces that were in contact with each other at the time of deceleration due to gear backlash collide with each other, and the gear vibrates by repeating this collision between the tooth surfaces. A chip-in shock occurred due to resonance with the suspension of the drive train. In order to prevent this, in the present embodiment, the driving torque is set larger than the required torque required by the driver at the time of chip-in, and the resonance due to the collision between the gears is suppressed.

  The ECU 10 of the electric vehicle 1 according to this embodiment is provided with a chip-in determination unit 12 that determines whether or not the vehicle is switched from the deceleration state to the acceleration. The chip-in determination unit 12 acquires the vehicle speed and determines whether or not the vehicle is in a decelerating state. When the vehicle is in a decelerating state, the tip-in determining unit 12 determines whether or not the accelerator opening detected by the accelerator opening detecting unit S1 has increased. Then, it is determined whether or not the vehicle has switched from the deceleration state to the acceleration.

  The ECU 10 is provided with an acceleration control unit 20 for suppressing resonance caused by a collision between gears when the vehicle travels from the deceleration state to the acceleration. The acceleration control unit 20 includes a rotation speed difference calculation unit 21, a determination unit 22, and an addition value setting unit 23.

  The rotation speed difference calculation unit 21 acquires the rotation speed of the drive wheel 5 detected by the drive wheel rotation speed detection unit S2 provided in each of the two drive wheels 5 constituting the front wheel, and acquires an average value thereof. . In this case, the drive wheel rotation speed detection unit S2 may directly detect the rotation speed of the drive wheel 5, and also detects the wheel speed of the drive wheel 5 and uses this wheel speed as the total reduction ratio and the drive wheel. The rotational speed of the drive wheel 5 may be detected based on the radius. Moreover, the rotation speed difference calculation part 21 acquires the motor rotation speed detected by the motor rotation speed detection part S3 provided in the traveling motor. In the present invention, the rotational speed of the drive wheel 5 and the rotational speed of the traveling motor 2 mean the rotational speed of the gear on the driving wheel 5 side and the rotational speed of the gear on the traveling motor 2 side in the drive system, respectively. These rotational speeds coincide with or substantially coincide with the rotational speeds of the drive wheels 5 and the traveling motor 2 detected by the drive wheel rotational speed detection unit S2 and the motor rotational speed detection unit S3 as described above. To do.

  Then, the rotation speed difference calculation unit 21 calculates the rotation speed difference between the rotation speed of the traveling motor 2 and the rotation speed of the drive wheel 5. The calculated rotational speed difference is input to the determination unit 22.

  When the determination unit 22 determines that the chip-in determination unit 12 of the ECU 10 is in a state where the vehicle is switched from the deceleration state to the acceleration (that is, at the time of chip-in), the rotational speed difference is greater than or equal to a predetermined value. Determine whether or not. This is because the drive torque is made larger than the required torque when the rotational speed difference is greater than or equal to a predetermined threshold value. That is, in the present embodiment, it is possible to detect that the vehicle has switched from the deceleration state to the acceleration by providing the chip-in determination unit 12, but at this time, if the rotational speed difference is small, the collision between the gears is small, It can be considered that the shock hardly occurs. In this embodiment, in such a case, not only the chip-in determination unit 12 but also the determination unit 22 is provided in order to set the torque addition value to 0, which is unexpected when no chip-in shock occurs. The driver's feeling is prevented from decreasing due to acceleration. When the rotational speed difference is greater than or equal to a predetermined value, it is determined that a tip-in shock that reduces the driver's feeling occurs, and the determination unit 22 inputs the rotational speed difference to the added value setting unit 23. To do. Here, the predetermined threshold value can be changed according to various factors such as the motor power of the vehicle, the type of the vehicle, and the weight of the vehicle body.

  The addition value setting unit 23 sets a torque addition value from, for example, a map shown in FIG. 3 based on the input rotational speed difference. As shown in this map, when the rotational speed difference becomes larger than the threshold value, the torque addition value increases linearly with respect to the rotational speed difference. The torque addition value set using such a map is input to the torque setting unit 11.

  When the torque addition value is input from the acceleration control unit 20 as described above, the torque setting unit 11 adds the torque addition value to the previously calculated required torque and outputs it as a drive torque. The traveling motor 2 is driven based on this driving torque.

  In the present embodiment, when the deceleration state is switched to the acceleration, the driving motor 2 is driven with a driving torque larger than the required torque in this way, thereby causing a collision between the gear on the motor side and the gear on the driving wheel side. Resonance due to vibration caused by collision between gears is prevented. In other words, if the motor side gear rotates at a value about the normal required torque, vibration due to the collision between the gears due to the backlash of the gear occurs at the time of the collision between the gear on the motor side and the gear on the driving wheel side, and resonance in the suspension occurs. Will occur. On the other hand, in the present embodiment, when the gear on the motor side collides with the gear on the driving wheel side so that the tooth surface does not collide and reverse, the driving torque that turns the driving wheel side gear as it is without being reversed. Is output to the traveling motor 2 to prevent vibration caused by a collision between gears. And by preventing the vibration by the collision of gears, the resonance with the other components (for example, suspension) of the vehicle body can be suppressed, and the vibration of the vehicle body (chip-in shock) can be suppressed. That is, since the force generated between the tooth surfaces at the time of collision is proportional to the difference in rotation speed, in this embodiment, the gear on the drive wheel exceeds the force generated at the time of collision by the motor side gear according to the rotation speed difference. A torque addition value that can be rotated is set, and this torque addition value is added to the required torque to generate a desired drive torque. Thus, the drive torque is a drive torque that can maintain the rotation on the acceleration side when a gear reaction occurs due to a gear collision when the vehicle suddenly changes from deceleration to acceleration. The torque addition value is set so that

  In this embodiment, the occurrence of a tip-in shock is predicted, and an added value of torque that can prevent vibration due to a collision between gears is set based on the relationship between the rotational speed difference and the generated tip-in shock. The traveling motor 2 is driven based on a driving torque larger than the required torque to prevent the vibration of the vehicle body due to the vibration caused by the collision between the gears.

  Further, since the traveling motor 2 is driven based on a driving torque larger than the required torque, only the force transmitted from the motor side gear to the driving wheel side gear is maintained, and the motor side gear and the driving wheel are maintained. The shock caused by the collision with the side gear gives an acceleration feeling and can suppress a decrease in the driver's feeling.

  A control flow at the time of chip-in of the electric vehicle according to the present embodiment will be described with reference to FIG.

  First, when the vehicle is driven, the ECU 10 starts control for suppressing chip-in shock (step S1). When the control is started, the torque setting unit 11 of the ECU 10 acquires the accelerator opening from the accelerator opening detecting unit S1, and calculates the required torque from the accelerator opening (step S2).

  On the other hand, the rotation speed difference calculation unit 21 of the acceleration control unit 20 of the ECU 10 acquires the drive wheel rotation speed from the drive wheel rotation speed detection unit S2, acquires the average value thereof (step S3), and detects the motor rotation speed. The motor rotation speed is acquired from the part S3 (step S4).

  The rotation speed difference calculation unit 21 of the acceleration control unit 20 calculates the rotation speed difference between the acquired drive wheel rotation speed and motor rotation speed (step S5).

  Next, the ECU 10 determines whether or not the driver requests acceleration from the deceleration state based on the vehicle speed and the accelerator opening (step S6). If it is not acceleration from deceleration (NO), it is not during chip-in, so the torque setting unit 11 of the ECU 10 outputs the required torque as drive torque as it is (step S7).

  In the case of acceleration from deceleration in step S6 (YES), that is, at the time of chip-in, the determination unit 22 of the acceleration control unit 20 determines whether the rotation speed difference calculated by the rotation speed difference calculation unit 21 is equal to or greater than a threshold value. Is determined (step S8). When the determination unit 22 determines that the value is less than the threshold (NO), the addition value setting unit 23 sets the torque addition value to 0 (step S9). If it is equal to or greater than the threshold (YES), the added value setting unit 23 sets the torque added value from the rotation speed difference input from the determining unit 22 using a map as shown in FIG. 3 (step S10).

  The addition value setting unit 23 sends the set torque addition value to the torque setting unit 11. The torque setting unit 11 of the ECU 10 outputs a value obtained by adding the torque addition value to the required torque as the drive torque (step S11).

  The traveling motor 2 is driven according to a driving torque that is larger than the required torque from the torque setting unit 11 by a torque addition value (step S12).

  Then, the ECU 10 determines whether or not the rotational speed difference has fallen below the threshold value (step S13). If the rotational speed difference has fallen below the threshold value, it is determined that the tip-in shock no longer occurs (YES), and the process Ends. On the other hand, if it is not below the threshold value (NO), the process returns to step S8, the torque addition value is set, and a driving torque larger than the required torque is set. In this way, when the rotational speed difference of the torque setting unit 11 is large and vibration due to a collision between gears is likely to occur, a driving torque larger than the required torque is continuously set, and the traveling motor 2 is set according to the driving torque. Driven. The threshold value here may be the same as the threshold value used in step S8, or may be another predetermined threshold value with which it can be determined that no chip-in shock occurs.

  In this embodiment, the occurrence of a tip-in shock is predicted, and an added value of torque that can prevent vibration due to a collision between gears is set based on the relationship between the rotational speed difference and the generated tip-in shock. Based on this, the traveling motor 2 is driven to prevent the vibration of the vehicle body caused by the vibration caused by the collision between the gears. Further, since the traveling motor 2 is driven based on a driving torque larger than the required torque, a shock caused by a collision between the gear on the motor side and the gear on the driving wheel side becomes an acceleration feeling, which reduces the driver's feeling. Suppressed.

  When the control of the present embodiment as described above is performed, the time chart is as shown in FIG. 5, for example. In FIG. 5, the vehicle speed, drive torque, and vehicle body vibration when the control of this embodiment is performed are indicated by solid lines, and the vehicle speed, drive torque, and vehicle body vibration when the control is not performed are indicated by dotted lines.

  First, in the case of time T = T0 to T1, as shown in FIG. 5 (1), the vehicle speed decreases with time, and the vehicle is in a decelerating state. In this case, the driving torque hardly changes.

  Thereafter, as shown in FIG. 5 (2), when the driver depresses the accelerator at time T = T1, the accelerator opening increases and the required torque increases, so that the drive torque set by the torque setting unit increases. start. The tip-in determination unit 12 is accelerating from the deceleration state up to time T = T1, that is, in a state where tip-in occurs, because the accelerator opening increases due to depression of the accelerator at time T = T1. judge. In this case, even if the accelerator opening is increased, the vehicle is not accelerated immediately, but a time difference is generated until acceleration.

  At time T = T1 to T2, since the accelerator opening is increased, the driving torque is also increased at the same time. As a result, the motor rotation speed is increased as shown in FIG. Then, since the vehicle speed has not yet shifted from deceleration to acceleration, the rotational speed difference between the motor rotational speed calculated by the rotational speed difference calculation unit and the driving wheel rotational speed becomes large, and the rotational speed difference becomes the threshold at time T = T2. The determination unit determines that the torque exceeds the value, and a torque addition value is set from the rotation speed difference.

  After time T = T2, as shown in FIG. 5 (3), when the control in this embodiment is not performed, a tip-in shock occurs and the vehicle vibrates greatly. This vibration is transmitted to the driver as a shock. On the other hand, in this embodiment, since the rotational speed difference exceeds the threshold value at time T = T2, a torque addition value is set by the addition value setting unit 23, and the drive torque is obtained by adding the torque addition value to the required torque. Will be. Therefore, the drive torque of the present embodiment is larger than when the drive torque is not controlled (that is, when the required torque matches the drive torque). As a result, the vibration caused by the collision between the gears is suppressed, so that even if a tip-in shock occurs, the vibration of the vehicle is suppressed compared to the case where the control is not performed.

  Further, from time T = T3, the vehicle speed changes to acceleration according to the accelerator opening as shown in FIG. 5 (1). However, if the control in this embodiment is not performed, the vehicle speed is once decelerated at time T = T4. Therefore, the driver may feel that the response of the vehicle is bad, and the feeling may be reduced. On the other hand, in this embodiment, since the driving torque at the time of collision is large, the vehicle speed does not turn to deceleration, and the driver feels good.

  At time T = T5, the rotational speed difference is almost eliminated and falls below the threshold value, whereby the control is completed and the drive torque substantially matches the required torque.

  As described above, in this embodiment, when the vehicle is switched from the deceleration state to the acceleration, the vehicle driving torque is made larger than the required torque in order to suppress the tip-in shock, thereby preventing the vibration between the gears. Resonance with the system is suppressed. Further, since the traveling motor 2 is driven based on a driving torque larger than the required torque, a shock caused by a collision between the gear on the motor side and the gear on the driving wheel side becomes an acceleration feeling, which reduces the driver's feeling. Can be suppressed.

  The present invention is not limited to the embodiment described above. In the present embodiment, the control is performed on the assumption that a tip-in shock may occur when the vehicle is switched from the deceleration state to the acceleration. However, the present invention is not limited to this. For example, when the vehicle descends on a hill and then approaches a flat ground, when the accelerator is depressed, a tip-in shock may occur without switching from the deceleration state to acceleration. In such a case, the rotational speed of the driving wheel 5 (the rotational speed of the gear G2 on the driving wheel 5 side) is relatively the rotational speed of the traveling motor 2 (the gear on the traveling motor 2 side). When the rotational speed of the traveling motor 2 is higher than the rotational speed of the drive wheels 5 from a state higher than the rotational speed of the G1), such control may be performed. In this case, it may be configured to always detect only the rotational speed and determine the chip-in.

  In the present embodiment, the determination unit 22 determines whether the rotational speed difference is equal to or greater than the threshold value, but is not limited thereto. For example, an addition value may be set whenever the vehicle is switched from a deceleration state to acceleration without providing the determination unit 22.

  In the present embodiment, the determination is made based on the difference in rotational speed between the motor rotational speed and the drive wheel rotational speed, but the present invention is not limited to this. The determination may be made based on the rotation speed difference integrated value obtained by integrating the rotation speed difference with time. By performing the determination based on the rotational speed difference integration value in this way, noise can be removed and the determination can be performed more accurately.

  In the present embodiment, the drive torque is obtained by adding the torque addition value to the required torque, but is not limited to this. For example, the driving torque may be obtained by obtaining a torque coefficient and multiplying the required torque by the torque coefficient. Further, a three-dimensional map showing the relationship among the required torque, the rotational speed difference, and the driving torque may be provided, and the driving torque may be directly obtained from the required torque and the rotational speed difference.

  In this embodiment, the average value of the rotational speeds of the drive wheels constituting the two front wheels is obtained, but the average value of the rotational speeds of all the drive wheels may be obtained.

DESCRIPTION OF SYMBOLS 1 Electric vehicle 2 Driving motor 3 Reduction gear 4 Driving shaft 5 Driving wheel 6 Driving battery 7 Inverter 11 Torque setting unit 12 Chip-in determination unit 20 Acceleration control unit 21 Rotational speed difference calculation unit 22 Determination unit 23 Addition value setting unit G1 Gear
G2 gear
S1 Accelerator opening degree detection unit S2 Drive wheel rotation number detection unit S3 Motor rotation number detection unit

Claims (5)

A travel motor driven by power supply from the battery; and drive wheels driven by the travel motor via gears, the travel based on the drive torque set based on the required torque requested by the driver An electric vehicle in which a motor is driven,
From the state where the rotational speed of the gear on the driving wheel side is relatively higher than the rotational speed of the gear on the traveling motor side, the rotational speed of the gear on the traveling motor side is relatively higher than that of the gear on the driving wheel side. When the rotational speed is higher than the rotational speed, a rotational speed difference detection unit that detects a rotational difference between the rotational speed of the gear of the driving wheel and the rotational speed of the gear of the traveling motor;
Torque for setting a driving torque larger than the required torque when the rotational speed of the gear of the traveling motor becomes higher than the rotational speed of the gear of the driving wheel based on the detected rotational speed difference An electric vehicle comprising a setting unit.   From the state where the rotational speed of the gear on the driving wheel side is relatively higher than the rotational speed of the gear on the traveling motor side, the rotational speed of the gear on the traveling motor side is relatively higher than that of the gear on the driving wheel side. The electric vehicle according to claim 1, wherein the case where the rotational speed is higher than the rotational speed is a case where the vehicle is switched from a deceleration state to an acceleration state. An addition value setting unit for setting a torque addition value to be added to the required torque based on the calculated rotation speed difference;
The electric vehicle according to claim 1, wherein the torque setting unit sets the driving torque larger than the required torque by adding the torque addition value and the required torque value. A determination unit for determining whether or not the calculated rotation speed difference is equal to or greater than a threshold;
The said addition value setting part sets the said torque addition value based on the said rotation speed difference, when this determination part determines with the said rotation speed difference being more than a threshold value, The said torque addition value is characterized by the above-mentioned. The electric vehicle according to any one of the above. The said addition value setting part sets the said torque addition value added to the said request torque based on the integral value which integrated the said rotation speed difference, The Claim 1 characterized by the above-mentioned. Electric vehicle.

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