JP2007015691A - Control device for vehicle running condition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for vehicle running condition capable of promoting an adequate brake/accelerator operation to a driver while assisting the operation of the driver during the starting operation on an uphill. <P>SOLUTION: In the control device for vehicle running condition, when the actual advancing direction of a vehicle body is opposite to the desired advancing direction of a driver, "No" is determined in S115, and the program advances to S116. It is further determined whether or not the rotational direction of a wheel is matched with the desired advancing direction of the driver. As a result, when the rotational direction of the wheel is matched with the desired advancing direction of the vehicle body, "Yes" is determined in S116, and the program moves to the control ending in and after S130. Thus, by stepping in an accelerator pedal, the slide-down mitigation control is successively completed from the wheel in which the rotational direction is matched with the desired advancing direction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vehicle traveling state control device that functions when a vehicle slides down (slopes down), such as when a brake pedal is switched to an accelerator pedal.

Conventionally, as a vehicle running state control device, a device that automatically applies a braking force when a vehicle slips down a slope on an uphill road when switching from a brake pedal to an accelerator pedal is known. (For example, refer to Patent Document 1). In such a vehicle running state control device, when a backward movement of the vehicle is detected despite the driver performing a forward operation, a braking force is applied to reduce the backward speed of the vehicle. Yes.
Japanese Patent Laid-Open No. 10-16745

  However, in the conventional technology as described above, if the braking force control at the time of slipping is continuously performed, the driver may determine that the vehicle can be moved as it is at the reverse speed during the control. Originally, the control for reducing the sliding speed is a function for temporarily supplementing the operation of the driver by functioning when the brake pedal is switched to the accelerator pedal. Therefore, it is necessary to prompt the driver to perform an appropriate brake / accelerator operation while supplementing the driver's brake / accelerator operation.

  Also, as long as the braking force is temporarily applied to relieve the slipping speed, the brake actuator used for the vehicle turning behavior control for applying the braking force to the predetermined wheel or the traction control for suppressing the acceleration slip is used as it is. Although it can be used, if it is assumed that relaxation control of the sliding speed is continued for a long time, another brake actuator having higher durability is required.

  The present invention has been made to solve such problems, and its purpose is to encourage the driver to perform an appropriate brake / accelerator operation while supplementing the driver's operation when starting up on an uphill road. An object of the present invention is to provide a vehicle running state control device capable of

  In order to solve the above-described problem, the vehicle running state control device according to the present invention controls the braking force when the vehicle travels in the opposite direction to the traveling direction of the vehicle based on the forward operation or the backward operation. It is a vehicle running state control device, an operation state detection means for detecting forward / backward operation, a wheel rotation detection means for detecting the rotation direction of a wheel of the vehicle, and an actual detection direction for actually traveling the vehicle. Separately from the traveling direction detection means and the driver's braking operation, the braking force applying means for applying braking force to the wheels, the driver's desired traveling direction and the actual traveling direction, which are grasped from the detection results of the operation state detecting means, Control means for controlling the braking force applying means to apply the braking force to the wheel when the wheel is in the reverse direction, and the desired traveling direction when the rotational direction of the wheel coincides with the desired traveling direction. Cars with the same direction of rotation Characterized in that it and a termination control means for controlling the operation of the braking force application means to terminate the action of the braking force applied to.

  According to this vehicle running state control device, the control means rotates in the sliding direction when the driver's desired traveling direction and the actual traveling direction are opposite, for example, when the vehicle is sliding down the slope. Operation control of the braking force applying means is performed so that the braking force is applied to the wheels that are moving, so as to reduce the sliding speed of the vehicle. Then, the end control means controls the operation of the braking force applying means so as to end the action of the braking force on the wheel whose rotational direction coincides with the desired traveling direction when the rotational direction of the wheel coincides with the desired traveling direction. . Therefore, the action of the braking force on the wheels can be sequentially terminated from the wheel whose rotation direction coincides with the desired travel direction. Accordingly, it is possible to prompt the driver to perform an appropriate brake / accelerator operation, and it is possible to protect the braking force applying means by avoiding the braking force applying means from operating for a long time.

  Further, the end control means applies the braking force so that the action of the braking force on the wheel is ended even when the rotation direction of the wheel does not coincide with the desired travel direction but the control by the control means continues for a predetermined time. It is preferable to control the operation of the means. In this case, it is possible to further encourage the driver to perform an appropriate brake / accelerator operation, and to further prevent the braking force applying means from operating for a long time.

  According to the present invention, it is possible to prevent the driver from determining that the vehicle can travel down the slope at the controlled speed, and to compensate for the driver's brake / accelerator operation, and to apply the appropriate brake / accelerator. It is possible to prompt the driver to operate. Further, since the braking force applying means can be prevented from operating continuously for a long time, the braking force applying means can be protected from heat generated by continuous energization.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 schematically shows a drive system of a four-wheel drive vehicle according to an embodiment. The rotational output of the engine 1 is shifted via the transmission 2 and further distributed to the front wheel side drive shaft 4F and the rear wheel side drive shaft 4R via the center differential 3. Further, the front wheel side drive shaft 4F is connected to the left and right drive shafts 6FL, 6FR via the front differential 5F, and the drive shafts 6FL, 6FR are connected to the wheels FL, FR serving as the left and right front wheels. Further, the drive shaft 4R on the rear wheel side is connected to the left and right drive shafts 6RL and 6RR via the rear differential 5R, and wheels RL and RR which are left and right rear wheels are connected to the drive shafts 6RL and 6RR. Through such a mechanism, the driving torque of the engine 1 is transmitted to the wheels FL, FR, RL, RR.

  Each wheel FL, FR, RL, RR is provided with a braking device 20. The hydraulic system of the hydraulic fluid that connects the wheel cylinder 21 constituting the braking device 20 and the master cylinder 30 has a driver's brake. Apart from the operation, a brake actuator 200 is provided for increasing and decreasing the hydraulic pressure in the wheel cylinder 21.

  FIG. 2 schematically shows the configuration of the brake actuator 200. The brake actuator 200 has a mechanism capable of independently controlling the hydraulic pressure for each braking device 20 of each wheel FL, FR, RL, RR. FIG. 2 shows the configuration of the brake actuator 200 for one wheel. Is representatively shown, but the other wheels have the same configuration.

  The pipe line 201 connecting the master cylinder 30 and the wheel cylinder 21 is provided with a shut-off valve (non-energized: valve open) 210, which is closed when the hydraulic pressure control of the hydraulic fluid is executed. The pipe line 201 between the cylinder 30 and the wheel cylinder 21 is blocked. Further, the pipe line 201 closer to the wheel cylinder 21 than the shutoff valve 210 is provided with a holding valve (non-energized: valve opening) 220, and the holding valve 220 is closed so that the holding cylinder 220 is connected to the wheel cylinder. The hydraulic system on the 21st side can be closed.

  A pipe line 201 between the holding valve 220 and the wheel cylinder 21 is connected to the reservoir 40 by a pipe line 202, and this pipe line 202 includes a pressure reducing valve (non-energized: valve closed) 230. The communication state of the pipe line 202 can be changed by duty-driving the pressure reducing valve 230 with a binary / state drive control signal in a non-energized state.

  A hydraulic pump 51 that is rotationally driven by the motor 50 functions as a hydraulic pressure source when controlling the braking force. It connects to the pipe line 201 between. A check valve 253 that prevents the flow of hydraulic fluid in the direction opposite to the discharge direction is provided on the discharge port side of the hydraulic pump 51.

  On the other hand, the suction port side of the hydraulic pump 51 is connected to the reservoir 40 via a conduit 204, and a check valve 251 that prevents the flow of hydraulic fluid in the direction opposite to the suction direction is connected to the conduit 204. 252 are arranged.

  The pipe line 204 between the check valves 251 and 252 is connected to the reservoir tank 31 through the pipe line 205, and the hydraulic fluid in the reservoir tank 31 passes through the pipe line 204 to the hydraulic pump 51. Sucked into. In addition, a suction valve (non-energized: valve closed) 240 for opening and closing the pipeline 205 is provided in the middle of the pipeline 205.

  As described above, the operation of the brake actuator 200 configured by the hydraulic pump 51 and various valve devices is controlled by the control device 100.

  As shown in FIG. 3, the control device 100 has wheels provided corresponding to the wheels FL, FR, RL, RR so as to detect the rotation direction and the rotation speed of the wheels FL, FR, RL, RR. Detection results such as a speed sensor 110, a shift position sensor 120 that detects the shift position of the shift lever, a brake pedal sensor 130 that detects the amount of depression of the brake pedal 10, and an accelerator pedal sensor 140 that detects the amount of depression of the accelerator pedal are given. .

  Next, in the control process of the actuator 200 performed by the control device 100, the control process for relieving the slipping state when the vehicle slips down the slope on an uphill road or the like is shown in the flowchart of FIG. It explains along. In addition, since this control is implemented separately for each wheel, the flowchart of FIG. 4 shows a control flowchart relating to one specific wheel.

  This flowchart is activated by turning on the ignition switch. First, the process proceeds to step (hereinafter, “step” is referred to as “S”) 102, and the driver's desired direction of travel is determined based on the detection result of the shift position sensor 120. This is because when the shift lever is operated to the forward shift position, the driver's desired direction of travel is the forward direction, and when the shift lever is operated to the reverse shift position, It is determined that the desired traveling direction is the backward direction.

  In subsequent S104, the actual traveling direction of the vehicle body, which is the direction in which the vehicle body is actually traveling in the forward and backward movements, is determined.

  For example, in a situation where the vehicle starts on a slope, when the brake pedal is switched to the accelerator pedal, a state in which neither the brake pedal 10 nor the accelerator pedal is depressed is temporarily generated, so that the vehicle body slides down the slope. There is. In such a case, the wheels FL, FR, RL, and RR usually rotate in the same direction as the slipping direction of the vehicle body, and therefore, based on the rotation direction of the wheels (specific wheels or all wheels). The actual traveling direction of the vehicle body can be determined.

  In this embodiment, since a four-wheel drive vehicle is described as an example, for example, when there is even one wheel that is rotating in a direction opposite to the driver's desired travel direction determined in S102 (all In the case where the rotational directions of the wheels do not match), it is possible to determine that the actual traveling direction of the vehicle body is opposite to the desired traveling direction.

  After determining the actual traveling direction of the vehicle body by any of the determination methods, the process proceeds to S106, and the value of the flag F indicating whether or not the slip mitigation control is being executed is set to F = 1 indicating that the vehicle is being executed. Judging. Since the value of the flag F is set to F = 0 at the initial stage, it is determined as “No” and the process proceeds to S108.

  In S108, based on the determination results in S102 and S104, it is determined whether the actual traveling direction of the vehicle body matches the desired traveling direction of the driver, and the actual traveling direction of the vehicle body and the desired traveling direction of the driver are determined. If they match, “Yes” is determined in S108, and this routine is terminated as it is.

  On the other hand, when the actual traveling direction of the vehicle body and the desired traveling direction of the driver are opposite ("No" in S108), the process proceeds to S110, and the value of the flag F is set to F = 1. In step S112, the timer for counting the execution time of the slip mitigation control is started.

  As described above, when neither the brake pedal 10 nor the accelerator pedal is depressed, the wheels FL, FR, RL, RR are in the same direction as the direction in which the vehicle slides down. It is rotating. Therefore, in subsequent S114, a pressure increase control for increasing the wheel cylinder pressure by a predetermined ΔP1 is performed, and a relatively small braking force is applied to reduce the rotational speed of the wheel.

  Referring to FIG. 2, during the pressure increase control of the brake actuator 200, the shutoff valve 210 is energized to be closed, and the suction valve 240 is energized to be opened, and the motor 50 is driven to drive the hydraulic pump 51. The hydraulic fluid is pumped from. As a result, the hydraulic fluid is supplied into the wheel cylinder 21 via the pipe line 203 and the pipe line 201. Then, after the time corresponding to the pressure increase of ΔP1 has elapsed, the internal pressure of the wheel cylinder 21 is increased by ΔP1 by energizing the holding valve 220 and closing the valve. This ΔP1 is a pressure increase value defined in advance so that the braking force is applied to such an extent that the wheels do not lock.

  Such a control process is performed on the braking device 20 of each wheel FL, FR, RL, RR, and by this control process, a braking force is applied to each wheel rotating in the slipping direction of the vehicle body. As a result, the sliding speed of the vehicle body is suppressed.

  In the next routine, similarly, in S102 and S104, after the driver's desired direction of travel and the actual travel direction of the vehicle body are determined, the process proceeds to S106, and if the slip mitigation control is started, the flag F is set. Since the value is set to F = 1, “Yes” is determined in S106, and the process proceeds to S115.

  In the control processing of this flowchart, it is assumed that the driver switches from the brake pedal to the accelerator pedal, and when the accelerator pedal is depressed, the actual traveling direction of the vehicle body is reversed and coincides with the driver's desired traveling direction. In such a case, it is desirable to immediately end the vehicle body slipping mitigation control. Therefore, in S115, based on the determination results in S102 and S104, it is determined again whether the actual travel direction of the vehicle body matches the desired travel direction of the driver. If the directions match, “Yes” is determined in S115, and the process proceeds to S130 and subsequent control end processing. The control end process after S130 will be described later.

Further, paying attention to the movement of each wheel, there is a wheel that has started to rotate in the driver's desired travel direction as a result of the driving force of the engine 1 being transmitted, although the vehicle body is in a state of sliding down the slope. In this case, it is desirable to end the vehicle body slip mitigation control for this wheel. Therefore, when the braking force is applied in the previous routine, but the actual traveling direction of the vehicle body and the desired traveling direction of the driver are still opposite directions, it is determined as “No” in S115 and the process proceeds to S116. Further, it is determined whether the rotation direction of the wheel to be controlled matches the driver's desired travel direction. As a result, when the rotation direction of the wheel to be controlled in this flowchart coincides with the desired travel direction of the vehicle body, “Yes” is determined in S116, and the process proceeds to the control end process after S130. Therefore, when the accelerator pedal is depressed, the slip mitigation control is sequentially terminated from the wheel whose rotation direction coincides with the desired travel direction.

  On the other hand, while the wheel is rotating in the vehicle body sliding direction, “No” is determined in S116 and the process proceeds to S118.

  In S118, it is determined whether the count value T of the timer started in S112 is equal to or less than a predetermined threshold value Ta. This threshold value Ta prevents the driver from determining that the vehicle can travel down the slope at the current speed, and causes each valve device such as the shutoff valve 210 constituting the brake actuator 200 to be continuously energized. In order to protect against heat generation, it is a predetermined time. The Ta time serving as the threshold can be appropriately set according to the design concept, the durability of the brake actuator 200, and the like, and is not particularly limited, but is about 3 seconds as an example.

  When the count value T of the timer is equal to or smaller than the threshold value Ta, “Yes” is determined in S118, and the process proceeds to S120.

  When the slip mitigation control is functioning properly, the wheel gradually rotates downward on the slope, but when the frictional force between the wheel and the road surface is small, such as on a low μ road, The wheel may be locked by the braking force set in S114 in the routine. Therefore, in S120, it is determined whether the wheel to be controlled is in a locked state in which the rotation of the wheel is stopped.

  As a result, when the wheel is not in the locked state, “No” is determined in S120 and the process proceeds to S122, and the wheel cylinder pressure set in the previous routine is held as it is.

  On the other hand, when the wheel to be controlled is in the locked state, “Yes” is determined in S120, and the process proceeds to S124, where the currently set wheel cylinder pressure is reduced by ΔP2 (ΔP1> ΔP2). To implement.

  Referring to FIG. 2, in this pressure reduction control, a drive control signal based on a predetermined duty ratio is supplied to the pressure reducing valve 230 to drive the pressure reducing valve 230 in a duty manner. As a result, the hydraulic fluid stored between the holding valve 220 and the wheel cylinder 21 flows into the reservoir 40 via the pressure reducing valve 230. Then, after the time corresponding to the reduced pressure of ΔP2 has elapsed, the energization of the pressure reducing valve 230 is stopped and the valve is closed, whereby the internal pressure of the wheel cylinder 21 is reduced by ΔP2.

  Also in the routine after the next time, when the wheel to be controlled is in the locked state, the process proceeds to S124 and the same pressure reduction control is performed, and the process of S124 is performed until the wheel is released from the locked state. By performing such a process, it is possible to reduce the rotation speed of the wheel rotating in the sliding direction while preventing the wheel from being locked.

  When such slip-off mitigation control continues beyond the threshold value Ta time, “No” is determined in S118 and the process proceeds to S126, and the count value T is further changed to another threshold value Tb (Ta <Ta < Tb) It is determined whether or not The threshold time Tb is a time during which the slow pressure reduction control performed in S128 is continued, giving the driver sufficient time to step on the brake pedal 10 and the accelerator pedal, and a rapid pressure. It is a predetermined time so as to prevent the omission and draw a predetermined gentle pressure reduction gradient. Although it does not specifically limit, it is about 8 seconds as an example.

  When the count value T of the timer exceeds Ta and Ta <T ≦ Tb, it is determined as “Yes” in S126, and the process proceeds to S128, and the gentle pressure reduction control for gradually ending the slip mitigation control is performed. .

  Normally, when the control on the brake actuator 200 is finished, the motor 50 is stopped and the energization of each valve device (the shut-off valve 210, the holding valve 220, the pressure reducing valve 230, and the suction valve 240) is stopped. To be implemented. In the normal termination process, the shutoff valve 210 is in the open state, the holding valve 220 is in the open state, the pressure reducing valve 230 is in the closed state, and the suction valve 240 is in the closed state in order to turn off each valve device. . As shown in FIG. 5, the wheel cylinder pressure is maintained at a predetermined pressure from the start of control at T = 0 until T = Ta, and such termination processing is performed immediately after the Ta time has elapsed. Assuming that the wheel cylinder pressure is implemented, the wheel cylinder pressure changes so as to rapidly decrease as shown by a one-dot chain line in FIG.

  Therefore, the slow pressure reduction control performed in S128 is performed so that the wheel cylinder pressure is reduced so as to have a gentler slope than that indicated by the one-dot chain line a in FIG. That is, in this slow pressure reduction control, the shutoff valve 210 and the holding valve 220 are energized to be closed, and a drive control signal having a duty ratio of, for example, about 10% is supplied to the pressure reduction valve 230 to drive the pressure reduction valve 230 in duty. To do. The pressure reducing valve 230 is fully opened when a drive control signal having a duty ratio of 100% is supplied.

  As a result, the hydraulic fluid stored between the holding valve 220 and the wheel cylinder 21 flows out to the reservoir 40 via the pipe line 202 while the flow rate is controlled by the pressure reducing valve 230. As indicated by the solid line b, the wheel cylinder pressure gradually decreases.

  While performing such slow pressure reduction control, if “No” in the previous S126, that is, if the count value T of the timer exceeds the threshold value Tb, the process proceeds to S130 and the normal control as described above is performed. Perform termination processing. That is, the motor 50 is stopped and each valve device is de-energized. By this processing, the shut-off valve 210 is opened, the holding valve 220 is opened, the pressure reducing valve 230 is closed, and the suction valve 240 is closed, so that the wheel cylinder pressure is greatly reduced as compared with the slow pressure reducing control. Although it becomes a gradient, since the threshold value Tb is set in advance so that the end control process is started in a sufficiently decompressed state, the braking force does not change greatly.

  Thereafter, the process proceeds to S132 to reset the count value of the timer, and in the subsequent S134, the value of the flag F is reset to F = 0 to prepare for the next and subsequent routines.

  When the count value T of the timer is T ≦ Tb as described above, the actual traveling direction of the vehicle body matches the desired traveling direction of the vehicle by the driver's accelerator operation (“Yes” in S115). Alternatively, if the wheel rotation direction matches the driver's desired direction of travel ("Yes" in S116), the process proceeds to S130 to S134 in order to end the vehicle body slippage mitigation control.

  Although omitted in the flowchart, when the brake pedal 10 is depressed under the situation where the slip mitigation control is being executed (flag F = 1), when the depression of the brake pedal 10 is detected, S130 is performed. ˜S134 is executed to immediately end the slip mitigation control.

  In the embodiment described above, the case where the pressure reducing valve 230 is opened / closed by the drive control signal having a duty ratio of about 10% while the count value T of the timer is Ta <T ≦ Tb is illustrated. It is not limited to the case where the ratio is kept constant. For example, the wheel cylinder is set so as to have a gradual decrease gradient than the decrease gradient indicated by the one-dot chain line a in FIG. 5, for example, the duty ratio of the drive control signal is changed stepwise so that the wheel cylinder pressure decreases stepwise. It is only necessary to perform a gentle pressure reduction control.

  Further, as a method for determining the actual traveling direction of the vehicle body performed in S104, in addition to the above-described determination method, for example, when the rotational directions of three wheels are aligned, the rotational direction is set as the actual traveling direction of the vehicle body. There is no particular limitation. In the case of a two-wheel drive vehicle, the rotation direction of the driven wheel that is a non-drive wheel is determined as the actual traveling direction of the vehicle body.

  In addition to this, the actual traveling direction of the vehicle body can also be directly detected using a ground speed sensor. For example, an ultrasonic wave with a predetermined frequency is transmitted from a vehicle-mounted ground speed sensor toward the road surface behind the vehicle, and the reflected wave is received. At this time, for example, when the frequency of the received wave is higher than the frequency of the transmitted wave, it can be determined that the vehicle body is moving backward, and when the frequency of the received wave is lower than the frequency of the transmitted wave, the vehicle body moves forward. Can be determined.

  In the embodiment described above, the flowchart of FIG. 4 has been described as being activated by turning on the ignition switch. However, the present invention is not limited to this example. For example, the shift position of the shift lever is the forward position or the backward position. Therefore, this flowchart may be activated under a situation where neither the brake pedal 10 nor the accelerator pedal is depressed.

  Further, in the embodiment described above, the case where the braking force is controlled by the hydraulic pressure of the hydraulic fluid has been described. However, in addition to this, in the operation control of the electronic motor brake that generates the braking force by the driving force generated by the motor. However, it can be applied as it is. Also in this case, when the count value T of the timer is between Ta <T ≦ Tb, the driving generated by the electronic motor brake is such that the braking force tends to decrease more slowly than the braking force decreases in the normal control termination process. Slow reduction control that gradually reduces the force is implemented.

  In the embodiment described above, the actuator in the vacuum booster type brake system is illustrated as shown in FIG. 2, but in addition to this, the braking force is applied to the wheel by the actuator of the brake system including the hydro booster or the motor. The actuator may be an actuator, and is not particularly limited as long as it is a brake actuator that can apply a braking force to the wheels separately from the driver's brake operation.

1 is a configuration diagram schematically showing a vehicle drive system and a hydraulic control system according to an embodiment. FIG. It is a block diagram which shows typically the hydraulic-pressure control system regarding the braking force control of one wheel among the structures of a brake actuator. It is a block diagram which shows roughly the structure of the whole control system of an electric system and a hydraulic system. It is a flowchart which shows the slipping-down speed relaxation control of a vehicle. It is a graph which shows the transition example of the wheel cylinder pressure with respect to the continuation time of vehicle slipping speed relaxation control.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Engine, 10 ... Brake pedal, 20 ... Braking device, 21 ... Wheel cylinder, 100 ... Control device, 200 ... Brake actuator, 210 ... Shut-off valve, 220 ... Holding valve, 230 ... Pressure reducing valve, 240 ... Suction valve

Claims (2)

A vehicle traveling state control device that controls braking force when a vehicle travels in a direction opposite to a traveling direction of the vehicle based on a forward operation or a backward operation,
Operation state detection means for detecting forward / backward operation;
Wheel rotation detection means for detecting the rotation direction of the wheel of the vehicle;
An actual traveling direction detection means for detecting the actual traveling direction in which the vehicle actually travels;
Separately from the driver's braking operation, braking force applying means for applying braking force to the wheels;
When the driver's desired travel direction and the actual travel direction ascertained from the detection result of the operation state detection means are opposite, the operation control of the braking force applying means is performed to control the wheels. Control means for applying power;
Termination control means for controlling the operation of the braking force applying means to terminate the action of the braking force on the wheel whose rotational direction coincides with the desired traveling direction when the rotational direction of the wheel coincides with the desired traveling direction. And a vehicle running state control device.   The termination control means terminates the action of the braking force on the wheel even when the rotation direction of the wheel does not coincide with the desired traveling direction, but the control by the control means continues for a predetermined time. 2. The vehicle travel state control device according to claim 1, wherein operation control of the braking force applying means is performed.

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