JP2007022135A - Automatic braking device of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automatic braking device for a vehicle for controlling the brake application while the vehicle is at a standstill, capable of guaranteeing the hold of the vehicle stopping condition and a proper operation of an ACC system even if the brake system is put in the condition out of function. <P>SOLUTION: A vehicle running control device having a braking control means to execute the running control by controlling the brake system is equipped with a non-function sensing means (Step 16A) to sense the brake system nonfunction and a non-function control means (Step 18A) to actuate a running function stopping means other than the brake system in case nonfunction is sensed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an automatic braking device for a vehicle, and more particularly to an automatic braking device for a vehicle that controls braking while the vehicle is stopped.

  2. Description of the Related Art A travel control device that automatically adjusts a brake amount to adjust the speed of a host vehicle is known. Such a travel control device is used together with accelerator control in a travel control device that detects a preceding vehicle using, for example, a camera or a radar, and travels following the vehicle while controlling the distance from the preceding vehicle. This technology is called the ACC (Adaptive Cruise Control) system. When there is no preceding vehicle, constant speed control is performed to maintain the predetermined vehicle speed set by the driver. Vehicle speed control is performed according to the vehicle speed, and follow-up control is performed to maintain a constant inter-vehicle distance.

In recent years, as disclosed in Patent Document 1, for example, a system (hereinafter referred to as full vehicle speed ACC) in which the application range of the ACC system is expanded to a low speed range to have a tracking function has been proposed. In this full vehicle speed ACC system, when the preceding vehicle stops, the brake hydraulic pressure is raised to follow the preceding vehicle and stop the own vehicle, and control is performed to maintain this stopped state. In addition, when the preceding vehicle starts, the vehicle is started automatically following the preceding vehicle, or the driver starts the vehicle by notifying the driver that the preceding vehicle has transmitted. It has become.
JP 2003-034240 A

  Some full vehicle speed ACC systems are configured to return to creep within a few seconds after the vehicle stops when the vehicle stops following the preceding vehicle. In this case, the driver must step on the brake after the vehicle stops following. Therefore, in order to further improve the convenience of the full-speed ACC system, it is considered to add the use for maintaining this stop state to the full-speed ACC system after the own vehicle stops following the stop of the preceding vehicle. It is done.

  However, if the brake system is unable to maintain the hydraulic pressure required to hold the vehicle stopped for some reason while the vehicle is stopped by control, the vehicle suddenly starts moving. The driver expects the full speed ACC system to keep the vehicle in automatic stop. For this reason, when the driver sees the above condition, the vehicle suddenly starts moving even though the preceding vehicle holds the stop, and it is impossible to cope with this and the risk increases. A point arises.

  The present invention has been made in view of the above points, and provides a travel control device for a vehicle that can maintain the stop state of the vehicle and ensure the proper operation of the ACC system even when the brake system is inoperative. With the goal.

  In order to solve the above-described problems, the present invention is characterized by the following measures.

The invention described in claim 1
In a vehicle travel control device having a braking control means for controlling travel by controlling a brake system,
A non-operation detecting means for detecting non-operation of the brake system when the vehicle is stopped by a brake operation of the brake system by the braking control means;
When the non-operation is detected by the non-operation detection means, the non-operation control means for operating the traveling function stop means other than the brake system is provided.

  According to the above invention, the malfunction detection means detects malfunction of the brake system while the vehicle is stopped. When the malfunction detection means detects the malfunction of the brake system, the travel function stop means other than the brake system is activated by the malfunction control means to prevent the vehicle from moving. As a result, even if the brake system is inoperative, the vehicle can be kept stopped by the other travel function stop means, so that safety when the vehicle is stopped can be improved.

The invention according to claim 2
In a vehicle travel control device having a braking control means for controlling travel by controlling a brake system,
Non-operation detecting means for detecting non-operation of the brake system during follow-up running control including control operation by the braking control means;
When the non-operation is detected by the non-operation detection means, the non-operation control means for operating the traveling function stop means other than the brake system is provided.

  According to the above invention, the malfunction detection means detects malfunction of the brake system during the follow-up running control. When the malfunction detection unit detects the malfunction of the brake system, the malfunction function control unit other than the brake system is activated by the malfunction control unit, thereby preventing the follow-up traveling control from being disabled. This makes it possible for the vehicle to maintain a constant distance from the preceding vehicle by the other travel function stop means even when the brake system is inoperative, thereby improving safety during follow-up travel control. it can.

The invention according to claim 3
The vehicle travel control apparatus according to claim 1 or 2,
The travel function stop means is one means selected from an electric parking brake, a parking range control means, and an engine stop control means.

  As in the above invention, the electric parking brake, the parking range control means, and the engine stop control means can be used as the travel function stop means other than the brake system.

The invention according to claim 4
The vehicle travel control apparatus according to any one of claims 1 to 3,
When the non-operation control unit detects the non-operation, a warning unit is provided to notify the driver that the non-operation has occurred.

  According to the above invention, it is possible to notify the driver that a malfunction has occurred in the brake system by the warning means.

  According to the present invention, even when the brake system is inoperative, the vehicle can be kept stopped by the other travel function stop means, so that the safety when the vehicle is stopped and the follow-up control can be improved.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the description, the same reference numerals are given to the same components in the drawings as much as possible, and duplicate descriptions are omitted.

  Hereinafter, a travel control device (ACC (adaptive cruise control) system) that detects the preceding vehicle and automatically operates the accelerator and the brake so that the vehicle travels following the vehicle will be described as an example. FIG. 1 is a schematic view of a vehicle equipped with the traveling control apparatus according to the present invention, and FIG. 2 is a block diagram of the vehicle.

  In the traveling control device 60, a laser radar sensor 1 that irradiates a laser beam forward as a means for detecting a preceding vehicle and detects the reflected light is disposed at the front of the vehicle. The detection of the preceding vehicle and the traveling control of the vehicle are performed by the control ECU 2. As shown in FIG. 2, the control ECU 2 includes an inter-vehicle distance control ECU 20, an engine ECU 21, a brake ECU 22, and a meter ECU 23.

  Among these, the engine ECU 21 controls the operation of the engine 3, and the control includes the operation control of the throttle motor 31 of the electronically controlled throttle. Further, the ECU 21 according to the present embodiment is configured to perform so-called fuel cut control for stopping (cutting) the supply of fuel to the engine 3.

  The brake ECU 22 controls the operation of the brakes disposed on each wheel, and the braking force of each brake is controlled by controlling the hydraulic pressure applied by the brake actuator 4. In this embodiment, the brake ECU 22 is also configured to control the braking operation by the electric parking brake 34. Further, the meter ECU 23 controls the operation of the display panel 35 and the speaker 36.

  The ECU 2 includes a wheel speed sensor 50 that detects the wheel speed of each wheel, a hydraulic sensor 51 that detects the hydraulic pressure applied to each brake, an output of the G sensor 52 that detects acceleration in the longitudinal direction of the vehicle, and the laser radar described above. An output signal of the sensor 1 is input.

  Next, the operation of this travel control device will be described. FIG. 3 is a diagram illustrating states of the preceding vehicle and the host vehicle. Hereinafter, the preceding vehicle is represented by P and the host vehicle is represented by M. The laser radar sensor 1 irradiates laser light forward, detects the laser light reflected by the preceding vehicle P, detects the time from irradiation to light reception and the light receiving position or angle, and the inter-vehicle distance control ECU 20 detects the preceding vehicle. The presence / absence of P is determined, and when the preceding vehicle P exists, a distance (inter-vehicle distance) Dr and a relative speed Vr from the host vehicle M are obtained.

  In the follow-up control, the target inter-vehicle distance Dt is set based on the vehicle speed V of the host vehicle, and the measured inter-vehicle distance Dr is matched with the target inter-vehicle distance Dt and the relative speed Vr is controlled to be zero. When the vehicle speed of the preceding vehicle P exceeds a predetermined value, the vehicle travels at a constant speed.

  Specifically, when the inter-vehicle distance Dr is longer than Dt, the engine ECU 21 opens the throttle by driving the throttle motor 31 or accelerates by shifting up, and the relative speed Vr is made positive and the inter-vehicle distance is increased. Stuff. When the brake control is currently being performed, the above control is performed when the braking force is decreased by reducing the hydraulic pressure applied by the brake actuator 4 by the brake ECU 4 and sufficient acceleration cannot be obtained even when the braking force is zero. I do.

  When the inter-vehicle distance Dr is shorter than Dt, the engine ECU 21 closes by driving the throttle motor 31 or shifts down and decelerates to open the inter-vehicle distance with a negative relative speed Vr. If the target deceleration cannot be obtained by throttle control or downshifting, the brake ECU 22 increases the hydraulic pressure applied by the brake actuator 4 to increase the braking force and further decelerate.

  In this control, the target acceleration is set according to the inter-vehicle distance and the relative vehicle speed, and feedback control is performed so that the actual acceleration matches the target acceleration. In addition, the travel control apparatus according to the present embodiment is a full vehicle speed ACC in which the application range of the ACC system is expanded to a low speed range and a tracking function is provided. For this reason, when the preceding vehicle stops, the brake hydraulic pressure of the brake actuator 4 is raised to follow the preceding vehicle and stop the own vehicle, and the stopped state is maintained.

  By the way, when the preceding vehicle stops as described above, in the traveling control device that follows and stops and holds the vehicle, the brake system becomes inoperative for some reason while the vehicle is stopped (braking cannot be performed). As described above, the vehicle suddenly starts moving, causing a problem in terms of safety.

  Therefore, in the vehicle travel control apparatus according to the first embodiment, when the own vehicle stops and holds the preceding vehicle at the full vehicle speed ACC, the brake system is detected to be inactive, If detected, the vehicle is prohibited from moving by activating the travel function stop means other than the brake system. Hereinafter, a control process performed by the control ECU 2 to prohibit the movement of the vehicle when the vehicle is stopped will be described.

  FIG. 4 is a flowchart for explaining the control operation of the vehicle travel control apparatus according to the first embodiment of the present invention, and FIG. 5 shows the brake hydraulic pressure, wheel speed, and electric parking when the present embodiment is implemented. 3 is a timing chart showing the operation of a brake 34. The control operation shown in FIG. 4 is a routine process that is repeatedly performed every predetermined time.

  When the process shown in FIG. 4 is started, first, in step 10 (step is abbreviated as S in the figure), it is determined whether or not an ACC execution command is issued to the control ECU 2. If it is determined in step 10 that an ACC execution instruction is not currently issued, the process ends without performing the processes in and after step 12.

  On the other hand, if an ACC execution command is currently issued in step 10, the process proceeds to step 12 to execute the known full vehicle speed ACC. During execution of the full vehicle speed ACC in step 12, the control ECU 2 determines whether or not the vehicle has stopped based on the wheel speed information from the wheel speed sensor 50 (step 14A). When it is determined in step 14A that the vehicle is not stopped, the process is terminated without executing the processes after step 16A. On the other hand, when it is determined in step 14A that the vehicle has stopped following the preceding vehicle, the processing of step 16A to step 24 is executed.

  In step 16A, based on the hydraulic pressure information from the hydraulic pressure sensor 51, the hydraulic pressures P (1) to P (4) applied to each brake are detected. In the following description, for convenience of explanation, only one hydraulic pressure (denoted as P) is shown and described among the hydraulic pressures P1 to P4 of the brake cylinders of the four wheels.

In step 16A, the detected detected pressure P determines whether less than a predetermined threshold pressure P _0. The processing executed in step 16A will be described with reference to FIG. FIG. 5 shows (A) brake hydraulic pressure, (B) change in wheel speed, and (C) operation of the electric parking brake 34 over time. The time t1 shown in the figure is the time when the control ECU 2 gives a command to the brake actuator 4 to stop the vehicle. The process of the control ECU 2 is started when the speed of the preceding vehicle is reduced.

  The brake system is driven by a command from the control ECU 2 and hydraulic pressure (the hydraulic pressure at this time is P) is supplied to the brake actuator 4. If there is no defect in the brake system, the hydraulic pressure P with respect to the brake actuator 4 should not change as shown by a two-dot chain line A in FIG. However, when a defect occurs in the brake system, the brake hydraulic pressure cannot be maintained, and the hydraulic pressure P gradually decreases with time as shown by a solid line B in FIG.

  In the example shown in the figure, although the brake hydraulic pressure P gradually decreases, the braking force corresponding to the brake hydraulic pressure P is output, and therefore the vehicle is braked and stopped at time t2. However, the brake hydraulic pressure P continues to decrease even after the vehicle stops.

In the figure, the dashed line indicated by an arrow C is the threshold pressure P ₀ of the brake hydraulic pressure. This threshold oil pressure P ₀ is a hydraulic pressure value that may cause the vehicle to move when the brake oil pressure is lower than this. In the present embodiment as described above, the brake hydraulic pressure P due to a defect of the braking system gradually has decreased, resulting in lower than the threshold pressure P ₀ at time t3. Therefore, after time t3, the vehicle may move if no measures are taken.

However, in this embodiment, when the control ECU 2 detects the fluctuation of the brake hydraulic pressure P based on the output from the hydraulic pressure sensor 51 and detects that the brake hydraulic pressure P has decreased below the threshold hydraulic pressure P ₀ , the electric parking brake It is configured to perform braking by driving 34.

Here, returning to FIG. 4, the description of the control processing by the control ECU 2 will be continued. The state in which it is determined in step 14A that the vehicle has been stopped is equivalent to the time t2 in FIG. Control ECU2 in step 16A, the brake hydraulic pressure P based on the output from the oil pressure sensor 51 determines whether or not lower than the threshold pressure P _0. When in step 16A the brake hydraulic pressure P is determined to be lower than the threshold pressure P _0, the process proceeds to step 18A, the electric parking brake 34 is driven (ON).

  In the present embodiment, the electric parking brake 34 is driven in step 18A, an abnormality is displayed on the display panel 35 via the meter ECU 23 in step 20, and a warning is given by the speaker 36. With this configuration, it is possible to notify the driver that a malfunction has occurred in the brake system, and thus it is possible to improve safety.

  As described above, according to the present embodiment, even if the brake system is defective, the vehicle can be kept stopped by the electric parking brake 34 that is a travel function stop means other than the brake system. As a result, when the driver expects the vehicle to hold the automatic stop by the full vehicle speed ACC system, the vehicle does not suddenly move, and safety when the vehicle is stopped can be improved. .

In step 16A, when the brake hydraulic pressure P is determined to be higher than the threshold pressure P ₀ releases the drive if the electric parking brake 34 is driven at step 22A, also the display panel 35 And the warning from the speaker 36 is stopped.

  Subsequently, the control operation of the vehicle travel control apparatus according to the second embodiment of the present invention will be described.

FIG. 6 is a flowchart for explaining the control operation of the vehicle travel control apparatus according to the second embodiment of the present invention. FIG. 7 shows the brake hydraulic pressure, wheel speed, and engine when the second embodiment is implemented. 3 is a timing chart showing the operation of the ECU 21. 6 and 7, the same contents and processes as those shown in FIGS. 5 and 6 are denoted by the same reference numerals and description thereof is omitted.

  In the first embodiment described above, the malfunction of the brake system is detected in a state where the vehicle is stopped, and when the malfunction has occurred, the travel function stop means (electric parking brake 34) other than the brake system is detected. ) To keep the vehicle stopped, thereby preventing the vehicle from moving. In contrast, in this embodiment, the brake system is detected to be inoperative when the ACC is executed, and the vehicle is braked by the travel function stop means other than the brake system when the malfunction has occurred. It is.

  Steps 10 and 12 shown in FIG. 6 are the same as those in the first embodiment shown in FIG. In step 14B, the control ECU 2 determines from the control processing of the inter-vehicle control ECU 20 whether or not the deceleration control is currently being performed (step 14B). The deceleration control is a control for decelerating the own vehicle in order to follow the deceleration of the preceding vehicle.

  When it is determined in step 14B that the deceleration control is not being performed, the process is terminated without executing the processes after step 16B. On the other hand, when it is determined in step 14B that deceleration control is being performed, the processing from step 16B to step 24 is executed.

  In step 16B, based on the hydraulic pressure information from the hydraulic pressure sensor 51, the hydraulic pressures P (1) to P (4) applied to each brake are detected. In this embodiment as well, only one hydraulic pressure (denoted as P) is shown and described.

  In step 16B, it is determined whether or not the detected hydraulic pressure P is smaller than a predetermined threshold hydraulic pressure P1. The processing performed in step 16B will be described with reference to FIG.

  FIG. 7 shows (A) brake hydraulic pressure, (B) change in wheel speed, and (C) fuel cut operation performed by the engine ECU 21 over time. The time t1 shown in the figure is the time when the control ECU 2 starts the deceleration control. The process of the control ECU 2 is started when the speed of the preceding vehicle is reduced.

  The control ECU 2 drives the brake system and supplies hydraulic pressure (the hydraulic pressure at this time is P) to the brake actuator 4. When there is no defect in the brake system, the hydraulic pressure P should not change as shown by the two-dot chain line A in FIG. 7A, but when there is a defect, the solid line B in FIG. As shown, the hydraulic pressure P gradually decreases as time passes, as described above. The same applies to the deceleration control performed while the vehicle is traveling. When the brake hydraulic pressure P gradually decreases in this way, the brake system eventually cannot output a braking force that keeps the distance between the preceding vehicle and each wheel constant for each wheel.

In the figure, one-dot chain line indicated by the arrow D is a threshold pressure P ₁ of the brake hydraulic pressure. The threshold pressure P ₁ is, when the brake hydraulic pressure is lower than this, a hydraulic value as a inability to perform deceleration control. In this embodiment as described above, the brake hydraulic pressure P due to a defect of the braking system is gradually reduced, lowered than the threshold value the hydraulic P ₁ at time t2. Therefore, after time t2, if no measures are taken, the ACC deceleration control cannot be performed properly, and the inter-vehicle distance from the preceding vehicle may be shortened.

However, in this embodiment, when the control ECU2 detects variations in brake pressure P based on the output from the oil pressure sensor 51, it detects that the brake hydraulic pressure P becomes lower than the threshold pressure P ₁ is the engine ECU21 The engine 3 is configured to perform fuel cut.

Here, returning to FIG. 6, the description of the control processing by the control ECU 2 will be continued. The state determined to be during deceleration control in step 14B is equivalent to the time t1 in FIG. Control ECU2 in step 16B, the brake hydraulic pressure P based on the output from the oil pressure sensor 51 determines whether or not lower than the threshold pressure P _1.

When in step 16B brake hydraulic pressure P is determined to be lower than the threshold pressure P _1, the process proceeds to step 18B, performing fuel cut. In the present embodiment, at the same time, an abnormality is displayed on the display panel 35 via the meter ECU 23 in step 20, and a warning is given by the speaker 36.

Therefore, according to the present embodiment, the vehicle speed can be reduced by reducing the output of the engine ECU 21 even if the brake system is defective, so that the vehicle maintains a constant distance from the preceding vehicle. Thus, safety during follow-up running control can be improved. Also in this embodiment, in step 16B, when the brake hydraulic pressure P is determined to be higher than the threshold pressure P ₁ is a fuel cut is stopped in step 22B, also a warning from the display panel 35 and speaker 36 To stop.

  In the embodiment described above, the fuel cut control by the electric parking brake 34 and the engine ECU 21 is used as the travel function stop means. However, other travel function stop means such as parking range control may be used.

  In the above description, the case where the travel control device is used for inter-vehicle distance control has been described as an example. However, the travel control device according to the present invention can be similarly applied to automatic travel and parking assistance.

  Further, in the first embodiment described above, when the vehicle is stopped by the ACC, the other travel function stop means different from the brake system is operated. However, the driver generates a braking force by the foot brake, thereby In a state where the vehicle is stopped, it is also possible to detect the non-operation of the brake system similar to that described in the first embodiment and to activate the travel function stop means other than the brake system when the non-operation is detected. Good.

FIG. 1 is a schematic diagram of a vehicle equipped with a vehicle travel control apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram of a vehicle travel control apparatus according to an embodiment of the present invention. FIG. 3 is a diagram illustrating states of the preceding vehicle and the host vehicle. FIG. 4 is a flowchart for explaining the control operation of the vehicle travel control apparatus according to the first embodiment of the present invention. FIG. 5 is a timing chart for explaining the control operation of the vehicle travel control apparatus according to the first embodiment of the present invention. FIG. 6 is a flowchart for explaining a control operation of the vehicle travel control apparatus according to the second embodiment of the present invention. FIG. 7 is a timing chart for explaining the control operation of the vehicle travel control apparatus according to the second embodiment of the present invention.

Explanation of symbols

1 Laser radar sensor 2 Control ECU
3 Engine 4 Brake actuator 20 Inter-vehicle control ECU
21 Engine ECU
22 Brake ECU
23 Meter ECU
31 Throttle motor 34 Electric parking brake 35 Display panel 36 Speaker 50 Wheel speed sensor 51 Hydraulic sensor 52 G sensor

Claims (4)

In a vehicle travel control device having a braking control means for controlling travel by controlling a brake system,
A non-operation detecting means for detecting non-operation of the brake system when the vehicle is stopped by a brake operation of the brake system by the braking control means;
A vehicle travel control device comprising: a non-operation control unit that activates a travel function stop unit other than the brake system when the non-operation is detected by the non-operation detection unit. In a vehicle travel control device having a braking control means for controlling travel by controlling a brake system,
Non-operation detecting means for detecting non-operation of the brake system during follow-up running control including control operation by the braking control means;
A vehicle travel control device comprising: a non-operation control unit that activates a travel function stop unit other than the brake system when the non-operation is detected by the non-operation detection unit. The vehicle travel control apparatus according to claim 1 or 2,
The travel function stop means is a means selected from an electric parking brake, a parking range control means, and an engine stop control means. The vehicle travel control apparatus according to any one of claims 1 to 3,
A vehicle travel control device, comprising: warning means for notifying a driver of the occurrence of the malfunction when the malfunction control means detects the malfunction.

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