JP6241122B2 - Vehicle control device - Google Patents

Description

  The present invention relates to control of a vehicle having an engine automatic stop function and a collision avoidance assist brake function.

  As a function for improving environmental performance, a stop engine automatic stop function (idle stop function) that stops an engine while a vehicle is stopped when a predetermined permission condition is satisfied is known. In recent years, in order to further enhance the effect of the engine automatic stop function, a pre-stop engine automatic stop function for stopping the engine before the vehicle stops is also known. On the other hand, when the risk of collision with an obstacle increases, the vehicle is stopped even if the driver does not step on the brake pedal, and when the driver steps on the brake pedal, the braking force (braking force) is increased. A collision avoidance assist brake function for controlling the brake fluid pressure (hydraulic pressure) in order to increase is known. As a control of a vehicle having both of these functions, Non-Patent Document 1 discloses prohibiting the pre-stop engine automatic stop function when the collision avoidance assist brake function is operating.

"Daihatsu Move Instruction Manual", November 30, 2012, p. 213

  However, there may be a situation in which the collision avoidance support brake is activated after the engine is automatically stopped before stopping. In the technique of the above document, when the collision avoidance assist brake is activated after the engine is automatically stopped before stopping, the engine automatic stop function is prohibited, and the engine is restarted by operating a starter device such as a starter motor. At this time, the starting device and the collision avoidance assistance brake are simultaneously operated, and power is taken out from the battery at the same time, which is not preferable. This measure is not disclosed at all in the above document, leaving room for examination.

  Therefore, an object of the present invention is to prevent the starting device and the collision avoidance support brake from operating simultaneously in a vehicle having an automatic engine stop function before stopping and a collision avoidance support brake function.

According to an aspect of the present invention, the case where the engine automatic stop control means is automatically stopped the engine before the vehicle stops, the collision avoidance assist braking means, the vehicle and the failure to operate the brake for collision avoidance The collision avoidable distance that can be stopped without collision when the brake is operated at the current vehicle speed is set as the distance to the object, and the engine automatic stop control means The engine restart distance obtained by adding the distance required for engine start to the collision avoidable distance is set as the distance of the vehicle so that the engine automatic stop control means restarts the engine before starting the collision avoidance support brake means. A control device is provided.

  According to the above aspect, it is possible to prevent the starting device and the collision avoidance assistance brake from operating simultaneously.

FIG. 1 is a system configuration diagram of a vehicle to which an embodiment of the present invention is applied. FIG. 2 is a timing chart for explaining the problem to be solved by the present invention. FIG. 3 is a flowchart of a control routine executed by the brake controller. FIG. 4 is a diagram showing the relationship between the vehicle speed and the distance D to the obstacle. FIG. 5 is a timing chart when the control routine of this embodiment is executed.

  FIG. 1 is a system configuration diagram of a vehicle to which an embodiment of the present invention is applied. The vehicle includes an engine (internal combustion engine) 1 as a driving source, and driving force generated by the engine 1 is transmitted to driving wheels 8 via an automatic transmission 2 and a driving shaft 6.

  The engine 1 includes a starter motor 4 as a starting device. The starter motor 4 may be a motor generator capable of generating and powering as a starter device, or a starter motor that engages with the flywheel of the engine 1 and performs cranking. May be. In addition, power to the starter motor 4 is supplied from the battery 5.

  The engine controller 20 executes fuel injection control, ignition timing control, engine automatic stop control, and the like of the engine 1. The engine controller 20 reads the detected values of the brake switch 30 that detects whether or not the brake pedal is depressed and the accelerator pedal sensor 31 that detects the accelerator pedal opening.

  The vehicle brake 7 includes a brake rotor 7B attached to the drive shaft 6 and a hydraulic brake caliper 7A attached to the vehicle body. The brake caliper 7A is operated by a hydraulic pressure supplied from the master cylinder 10 that operates according to a driver's brake pedal operation or a hydraulic pressure supplied from a hydro unit 22 described later. The vehicle includes a brake booster 9 that amplifies the driver's pedal force using the negative pressure in the collector tank 3, and the master cylinder 10 generates a hydraulic pressure corresponding to the amplified pedal force.

  The vehicle also includes a brake controller 23 that includes a brake control unit 21 and a hydro unit 22. The hydro unit 22 includes a motor and a hydraulic control valve, and can generate hydraulic pressure to be supplied to the brake caliper 7A in accordance with an instruction from the brake control unit 21 regardless of the state of the master cylinder 10. Note that the motor and the hydraulic control valve of the hydro unit 22 are operated by electric power supplied from the battery 5.

  The brake control unit 21 includes a brake hydraulic pressure sensor 32 that detects the hydraulic pressure of the brake hydraulic line, a brake negative pressure sensor 33 that detects negative pressure at the brake booster 9, and a G sensor that detects acceleration, vehicle speed, and the like. The detection value is read. Note that a vehicle speed sensor may be provided for the vehicle speed.

  Further, distance information to the obstacle is input to the brake control unit 21 from the radar 35 for detecting the obstacle in front of the vehicle. The radar 35 is a known one such as a millimeter wave radar or an infrared laser radar. Further, instead of the radar 35, a camera system that can calculate the distance from the image information may be used.

  The engine controller 20 and the brake control unit 21 are connected by a so-called CAN bus, and cooperative control is possible.

  The engine controller 20 and the brake control unit 21 are constituted by a microcomputer having a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface). The It is also possible to configure the engine controller 20 and the brake control unit 21 with a plurality of microcomputers.

  Next, the engine automatic stop function, that is, the engine automatic stop control executed by the engine controller 20 will be described.

  The engine automatic stop control according to the present embodiment automatically stops the engine 1 when a predetermined engine automatic stop permission condition is satisfied during traveling of the vehicle. The predetermined automatic engine stop permission condition is, for example, that the vehicle speed is about 10 km / h or less, that the brake pedal is depressed, that the accelerator pedal is not depressed, and that power consumption such as headlights and wipers is reduced. Large electrical components are not working. When all these conditions are satisfied, the fuel supply to the engine 1 is stopped and the engine is stopped before the vehicle stops. When a predetermined engine automatic stop cancellation condition is satisfied during engine automatic stop, the engine 1 is restarted.

  The predetermined engine automatic stop cancellation condition is satisfied, for example, when the foot is released from the brake pedal, when the accelerator pedal is depressed, when a request for charging the battery 5 is issued, or the like. In addition, the engine automatic stop cancellation condition may be satisfied by cooperative control with a collision avoidance support brake described later.

  Next, the collision avoidance assistance brake function, that is, the collision avoidance assistance brake control executed by the brake control unit 21 will be described.

  The collision avoidance assist brake control is a control for avoiding a collision with an obstacle ahead in the vehicle traveling direction. Specifically, there is one (first pattern) that generates a braking force (braking force) when the driver (driver) does not operate the brake pedal despite the high possibility of a collision. Further, the driver is operating the brake pedal, but when a larger braking force is required, the driver further generates a braking force so that the braking force is greater than the braking force corresponding to the brake pedal operation (second Pattern). In each pattern, the brake hydraulic pressure at which the braking force necessary for collision avoidance is obtained is determined based on the relative speed with the obstacle, the distance to the obstacle, etc., and according to the driver's brake pedal operation (brake pedal stroke) It is determined whether the required brake force can be obtained with the brake hydraulic pressure. If it is determined that the necessary braking force cannot be obtained, the hydraulic pressure is increased so that the hydro unit 22 is operated to obtain the necessary braking force.

  If it is the first pattern, the driver does not operate the brake pedal, so the determined brake hydraulic pressure is generated by the hydro unit 22.

  On the other hand, in the case of the second pattern, the hydro unit 22 generates a differential pressure between the determined brake hydraulic pressure and the brake hydraulic pressure corresponding to the brake pedal operation (brake pedal stroke). In other words, in order to generate a braking force necessary for avoiding a collision, this is a control for generating a braking force larger than the braking force corresponding to the driver's brake pedal operation.

  The first pattern is executed when it is determined that the driver does not operate the brake pedal from the detected value of the brake switch 30 or the like when the distance to the obstacle is equal to or less than a predetermined threshold during traveling. The Note that the driver may be prompted to operate the brake pedal when the distance from the obstacle approaches the threshold before the first pattern is executed. Further, when the driver operates the brake pedal during the execution of the first pattern, the hydraulic pressure supplied from the hydro unit 22 is reduced or the collision avoidance assist brake control is performed according to the braking force generated by the driver's brake pedal operation. You may make it cancel.

  The second pattern is that when the driver is operating the brake pedal, the current braking force is an obstacle based on the distance to the obstacle, vehicle speed, brake fluid pressure, brake negative pressure, vehicle deceleration G, etc. This is executed in order to generate a stronger braking force when it is determined that the vehicle cannot be stopped before colliding with the vehicle.

  In the following description, the state in which the brake 7 is operated by the collision avoidance support brake control may be expressed as “the collision avoidance support brake is operated”.

  By the way, in the case of a vehicle having both an engine automatic stop function for stopping the engine before the vehicle stops and a collision avoidance support brake function, the collision avoidance support brake is activated after the engine is stopped before stopping by the engine automatic stop function. There is a risk that the situation will be explained.

  Since the engine automatic stop control is not executed unless the driver operates the brake pedal, the situation where the first pattern collision avoidance support brake is activated after the engine 1 automatically stops before the vehicle stops cannot occur. . Therefore, the situation described below occurs not in the first pattern but in the second pattern.

  FIG. 2 is a timing chart for explaining the above situation. This timing chart is for a driving scene in which the driver continues to depress the brake pedal and continues to decelerate.

  An engine automatic stop condition is satisfied at timing T11 during vehicle travel, and an engine stop request is issued. The engine is automatically stopped before the vehicle stops. At this time, as described above, the driver is stepping on the brake pedal and the collision avoidance assist brake is not operating, so that the brake hydraulic pressure has a magnitude corresponding to the brake pedal operation (brake pedal stroke).

  At time T12, the distance from the obstacle becomes equal to or less than the threshold value, and a collision avoidance assistance brake operation instruction is issued. That is, it is determined that the brake force is insufficient in the brake hydraulic pressure corresponding to the brake pedal operation (brake pedal stroke), and the collision avoidance support brake is activated. As a result, the brake hydraulic pressure becomes a magnitude obtained by combining the hydraulic pressure corresponding to the brake pedal operation (brake pedal stroke) and the hydraulic pressure from the hydro unit 22. That is, the brake hydraulic pressure is increased by the hydro unit 22 to a larger brake hydraulic pressure than the brake hydraulic pressure corresponding to the driver's brake pedal operation.

  With the operation of the collision avoidance support brake, the automatic engine stop during running is prohibited, and the engine 1 is restarted at timing T13. In order to restart the engine, it is necessary to perform cranking by the starter motor 4, but when the starter motor 4 is operated, a voltage drop called a so-called instantaneous drop occurs. And by this voltage drop, the hydro unit 22 stops and a collision avoidance assistance brake stops. As a result, after timing T13, the brake hydraulic pressure is not increased by the collision avoidance assist brake, and braking is performed in a state where the brake hydraulic pressure is reduced to the brake hydraulic pressure corresponding to the driver's brake pedal operation.

  Therefore, in the present embodiment, control is performed so that the engine 1 is restarted before the collision avoidance support brake is operated so that the starter motor, which is a starting device, and the collision avoidance support brake do not operate simultaneously. Hereinafter, the contents of this control will be specifically described.

  FIG. 3 is a flowchart of a control routine executed by the brake control unit 21.

  In step S10, the brake control unit 21 determines whether or not the pre-stop engine is automatically stopped. This determination is repeatedly performed until the engine stops before stopping. Whether the engine is stopped before stopping is determined based on information from the engine controller 20.

  In step S20, the brake control unit 21 determines whether the distance D to the obstacle is equal to or less than the threshold value DA. If it is equal to or less than the threshold value DA, the process of step S30 is executed. Otherwise, the process of step S60 described later is executed. The distance D to the obstacle is detected by the radar 35 as described above.

  Here, a setting method of the threshold value DA and the threshold value DB used in step S40 described later will be described.

  FIG. 4 is a diagram showing the relationship between the vehicle speed and the distance D to the obstacle.

  The threshold value DA is obtained by adding the distance DC that the vehicle travels during cranking to the threshold value DB that activates the collision avoidance assistance brake. Specifically, this is a distance traveled by the vehicle from when the starter motor 4 is operated to start cranking of the engine 1 to when the engine 1 completes explosion. That is, it is the distance required to stop after the collision avoidance support brake is activated after cranking and restarting the engine 1.

  The threshold value DB is a distance required from when the collision avoidance support brake is operated until the vehicle stops. Specifically, it is the shortest braking distance from the start of the collision avoidance support brake operation to the stop when the collision avoidance support brake exerts the maximum braking force, and after the vehicle speed and the collision avoidance support brake are operated It is a value obtained by multiplying the time required to stop. For this reason, as shown in FIG. 4, the threshold value DB increases as the vehicle speed increases.

  Here, the time required for the vehicle to stop after the collision avoidance support brake is operated is the current vehicle speed divided by the deceleration G when the collision avoidance support brake is operated. The deceleration G when the collision avoidance support brake is activated is set in advance.

  Further, the distance DC that the vehicle travels during cranking is represented by the product of the vehicle speed and the cranking time at that time, and therefore becomes larger as the vehicle speed increases as shown in FIG. Note that the cranking time is the time from when the starter motor 4 is operated to start cranking of the engine 1 until the engine 1 completes explosion, and an appropriate value is used.

  Therefore, the threshold value DA, which is the sum of the threshold value DB and the distance traveled by the vehicle during cranking, also becomes larger as the vehicle speed is higher as shown in FIG. 4, and the difference between the threshold value DA and the threshold value DB is also higher. It gets bigger.

  In step S20, a threshold value DA is set by searching a table as shown in FIG. 4 at the current vehicle speed.

  If it is determined in step S20 that the distance D to the obstacle is equal to or less than the threshold value DA, the brake control unit 21 transmits an engine restart request to the engine controller 20 in step S30. In response to this, the engine controller 20 operates the starter motor 4 to restart the engine 1. If engine restart request is received again after starting cranking, engine controller 20 continues cranking or engine operation as it is. That is, after starting cranking, the process proceeds from step S40 to step S60 and step S20, which will be described later, and when the process of step S30 is executed again, the cranking is not performed again.

  If the engine restart request is transmitted in step S30, the brake control unit 21 determines in step S40 whether the distance D to the obstacle is equal to or less than the threshold DB described above. If not, the process of step S60 is executed.

  In step S50, the brake control unit 21 starts a collision avoidance assistance brake control that is set separately. That is, the hydraulic unit 22 is operated to supply hydraulic pressure to the brake caliper 7A, and the brake 7 is operated. Since the content of the collision avoidance assistance brake control is the same as that of a known one, detailed description is omitted.

  On the other hand, in step S60 executed when the distance D to the obstacle is larger than the threshold value DA in step S20 or when the distance D to the obstacle is larger than the threshold value DB in step S40, the brake control unit 21 stops. It is determined whether or not. This routine is complete | finished when it has stopped, and when not stopping, it returns to the process of step S20.

  As described above, when the engine is automatically stopped before stopping, the brake control unit 21 restarts the engine 1 when the distance D to the obstacle is equal to or less than the threshold value DA, and the distance D to the obstacle is further increased. When it shrinks and falls below the threshold DB, the collision avoidance assistance brake is activated.

  Thus, since the engine 1 is restarted before operating the collision avoidance assistance brake, it is possible to avoid the situation where the hydraulic control for the collision avoidance assistance brake becomes impossible due to the instantaneous drop during cranking, and the necessary braking force Can be generated. Note that the control routine ends immediately when there is an acceleration request such as when the accelerator pedal is depressed.

  FIG. 5 is a timing chart when the above control is executed. This timing chart is also for the driving scene where the driver continues to decelerate by stepping on the brake pedal as in FIG.

  The engine automatic stop permission condition is satisfied at the timing T21 during traveling, and an engine stop request is generated, and the engine is stopped before the vehicle stops. At this time, the driver is stepping on the brake pedal as described above, and the collision avoidance assist brake is not operating, so the brake hydraulic pressure is set to a magnitude corresponding to the brake pedal operation.

  Thereafter, the engine stop request is canceled at timing T22 when the distance D to the obstacle becomes the threshold value DA (S20, S30 in FIG. 3), and the engine 1 is restarted by cranking. Here, a voltage sag occurs due to cranking, but the collision avoidance assist brake is not operated, and thus is not affected by the voltage sag.

  Thereafter, the collision avoidance assistance brake is operated at timing T23 when the distance D to the obstacle becomes the threshold value DB (S40, S50 in FIG. 3).

  That is, the brake hydraulic pressure corresponding to the brake pedal operation is determined to be insufficient for the brake force, the collision avoidance assist brake is operated, and the hydraulic pressure is also supplied from the hydro unit 22 to increase the brake hydraulic pressure. In this state, the vehicle stops.

  By setting the threshold value DA and the threshold value DB as described above, the cranking has been completed by the timing T23 at which the collision avoidance support brake is operated. Therefore, the voltage drop due to the cranking affects the operation of the collision avoidance support brake. Never give.

  The operational effects of the present embodiment described above will be summarized.

  (1) Brake larger than the braking force generated by the driver's brake pedal operation based on the distance between the engine controller 20 (engine automatic stop control means) that automatically stops the engine 1 before the vehicle stops and the obstacle ahead of the vehicle traveling direction And a brake control unit 21 (collision avoidance support brake means) capable of generating force. Then, when the collision avoidance assistance brake is activated after the engine 1 is automatically stopped before the vehicle stops, the engine controller 20 restarts the engine 1 before the collision avoidance assistance brake is activated. Thereby, it can avoid that the starter motor 4 and the collision avoidance assistance brake act | operate simultaneously. As a result, it is possible to avoid a voltage drop due to the starter motor 4 operating during the collision avoidance assistance brake operation, so that it is possible to generate a braking force necessary for the collision avoidance assistance brake.

  (2) When the engine is stopped before the vehicle stops, the brake control unit 21 operates the brake 7 at the current vehicle speed as the distance between the own vehicle that operates the collision avoidance support brake and the obstacle. The collision avoidable distance that can stop without colliding is set. On the other hand, in this case, the engine controller 20 sets the engine restart distance obtained by adding the distance required to start the engine to the collision avoidable distance as the distance between the vehicle that restarts the engine 1 and the obstacle. As a result, the voltage drop due to cranking for restarting the engine ends before the collision avoidance assistance brake is actuated. That is, it is possible to avoid a voltage drop during the operation of the collision avoidance assist brake.

  (3) The engine controller 20 and the brake control unit 21 set the engine restart distance and the collision avoidable distance to be smaller as the vehicle speed is lower. The lower the vehicle speed is, the shorter the distance required from the brake operation to the stop is. Therefore, by setting as described above, unnecessary engine restart can be avoided and deterioration of fuel consumption performance can be suppressed.

  (4) The engine controller 20 sets the difference between the engine restart distance and the collision avoidable distance, that is, the distance required for engine start to be smaller as the vehicle speed is lower. The lower the vehicle speed, the shorter the distance traveled by the vehicle during cranking. Therefore, it is possible to set a short distance necessary for finishing cranking before starting the brake operation. By combining this with the above (3), it is possible to further suppress the deterioration of fuel consumption performance.

  The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made within the scope of the technical idea described in the claims.

1 Engine 2 Automatic transmission 4 Starter 7 Brake 9 Brake booster 10 Master cylinder 20 Engine controller 21 Brake controller 22 Hydro unit

Claims (3)

An engine automatic stop control means for automatically stopping the engine when a predetermined permission condition is satisfied while the vehicle is running, and restarting the engine when a predetermined release condition is satisfied;
A collision avoidance assisting brake means capable of generating a braking force larger than a braking force by a driver's brake pedal operation based on a distance from an obstacle ahead of the vehicle traveling direction;
In a vehicle control device comprising:
The case that automatically stop the engine before the vehicle stops the engine automatic stop control means,
Collision avoidable distance at which the collision avoidance support brake means can stop without colliding when the brake is operated at the current vehicle speed as the distance between the vehicle that activates the brake to avoid collision and the obstacle. And the engine automatic stop control means sets the engine restart distance obtained by adding the distance required for engine start to the collision avoidable distance as the distance between the vehicle that restarts the engine and the obstacle. Thus, the engine automatic stop control means restarts the engine before the operation of the collision avoidance assistance brake means is started. The vehicle control device according to claim 1 ,
The vehicle automatic control device and the collision avoidance assistance brake unit set the engine restart distance and the collision avoidable distance as small as the vehicle speed is low. The vehicle control device according to claim 2 ,
The engine automatic stop control means sets the difference between the engine restart distance and the collision avoidable distance to be smaller as the vehicle speed is lower.

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