JP2008179200A - Brake control apparatus of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent control from being unstable at an initial starting period of braking operation when deceleration control of its own vehicle is performed by making both brakes operated from a state in which the both of an engine brake (throttle valve opening/closing actuator 20) and a wheel brake (wheel brake operating means 21) are not operated. <P>SOLUTION: The engine brake is started by delaying, for a specific time, from the start of the wheel brake when the deceleration control of the own vehicle is performed by making the both brakes operated from the state in which the both of the engine brake and the wheel brake are not operated. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a brake control device for a vehicle, in which the host vehicle is decelerated and controlled by operating at least one of an engine brake and a wheel brake according to a target deceleration when the host vehicle is running following the preceding vehicle. Belongs to the technical field.

Conventionally, an inter-vehicle distance between the host vehicle and a preceding vehicle ahead thereof is detected by a radar device or the like, and the host vehicle follows the preceding vehicle so that the detected inter-vehicle distance becomes a preset target inter-vehicle distance. Such a control device is well known (see, for example, Patent Documents 1 and 2). In this device, the target acceleration / deceleration of the host vehicle is calculated so that the inter-vehicle distance detected by the radar device or the like maintains the target inter-vehicle distance, and the throttle valve, the brake, etc. operate automatically according to the target acceleration / deceleration. The vehicle is subjected to acceleration / deceleration control.
JP 2001-239855 A JP 2004-330890 A

  By the way, when the target acceleration / deceleration is the deceleration, the own vehicle is controlled to decelerate by operating the engine brake and the wheel brake, but how to operate both brakes becomes a problem. In other words, although wheel brakes can provide a large braking force, they are not responsive to actuate a hydraulic pump or the like, and if they are actuated frequently, their service life may be shortened, and the passenger may feel uncomfortable during operation. high. On the other hand, the engine brake does not cause a problem like a wheel brake, but cannot obtain a large braking force.

  Therefore, it is preferable to operate the engine brake as much as possible so as not to operate the wheel brake. From this point of view, when a large braking force is not necessary, only the engine brake is used while the preceding vehicle and the host vehicle are not operated. When it is necessary to apply a large braking force suddenly, such as when there is an interrupting vehicle in between, it is conceivable to use an engine brake and a wheel brake together.

  However, there is a problem that stable deceleration control cannot be performed when both brakes are started simultaneously from a state where both brakes are not operated. That is, the deceleration control by the wheel brake is normally performed by controlling the hydraulic pressure supplied to the wheel by feeding back the vehicle deceleration detected by the vehicle speed sensor or the like. Since the detection is delayed, the vehicle deceleration tends to overshoot. Here, if only the wheel brake is operated, the overshoot can be suppressed as much as possible, and it can be converged as soon as possible. Since it is not known at the beginning of the operation whether or not it contributes, a large overshoot occurs, and it takes time to converge or the control diverges.

  The present invention has been made in view of such a point, and an object of the present invention is to operate both the brakes from a state in which both the engine brake and the wheel brake of the own vehicle are not operated. The purpose of the deceleration control is to prevent the control from becoming unstable at the beginning of the braking operation.

  In order to achieve the above object, according to the present invention, when both the engine brake and the wheel brake are operated, the both brakes are operated and the own vehicle is decelerated to control the engine brake more than the wheel brake. The operation was started after being delayed by a predetermined time.

  Specifically, in the first aspect of the invention, the preceding vehicle detection means for detecting the preceding vehicle ahead of the host vehicle, and the inter-vehicle distance detection for detecting the inter-vehicle distance between the preceding vehicle detected by the preceding vehicle detection means and the host vehicle. Means, a target inter-vehicle distance setting means for setting a target inter-vehicle distance between the preceding vehicle and the host vehicle, and an inter-vehicle distance detected by the inter-vehicle distance detection means is a target inter-vehicle distance set by the target inter-vehicle distance setting means When the target acceleration / deceleration calculated by the target acceleration / deceleration calculating means is a deceleration, the target acceleration / deceleration calculating means for calculating the target acceleration / deceleration of the host vehicle so as to maintain The present invention is directed to a vehicle brake control device including a deceleration control unit that controls deceleration of the host vehicle by operating at least one of an engine brake and a wheel brake.

  The deceleration control means starts the operation by delaying the engine brake by a predetermined time from the wheel brake when the vehicles are decelerated and controlled while the brakes are not operated. It shall be comprised so that it may make it.

  With the above configuration, when both the brakes are operated and the own vehicle is decelerated and controlled from the state where both brakes are not operated, the operation is started from the wheel brakes and the vehicle deceleration is substantially stabilized (this time) The engine brake can be operated after a lapse of a predetermined time). This eliminates instability of control due to the engine brake being applied at the beginning of wheel brake operation. In addition, by operating the wheel brake first, it is possible to cope with a case where it is necessary to apply a large braking force suddenly.

  According to a second aspect of the present invention, in the first aspect of the invention, the deceleration control means is configured such that the magnitude of the target deceleration calculated by the target acceleration / deceleration calculating means is a predetermined value from a state in which the both brakes are not operated. It is assumed that the vehicle is decelerated and controlled by operating both brakes when the vehicle becomes larger.

  As a result, when it is necessary to apply a large braking force suddenly, the engine brake and the wheel brake can be used together to compensate for the drawbacks of the engine brake. Control instability can be prevented.

  According to a third aspect of the present invention, in the first aspect of the invention, the deceleration control means is configured such that when the target deceleration calculated by the target acceleration / deceleration calculating means is greater than a preset set value, The vehicle is decelerated and controlled by operating both brakes, and when the target deceleration is equal to or less than the set value, the vehicle is decelerated and controlled only by the engine brake. To do.

  In this way, the engine brake is actuated as much as possible to prevent the wheel brake from being actuated, and the brake force is suddenly applied while preventing the life of the wheel brake from deteriorating and preventing the passenger from feeling uncomfortable. When necessary, the brakes can be applied more accurately by operating both brakes. In addition, it is possible to prevent instability of control at the beginning of the brake operation start.

  As described above, according to the vehicle brake control device of the present invention, when both the engine brake and the wheel brake are operated and both the brakes are operated to control the deceleration of the host vehicle, Is delayed for a predetermined time from the wheel brake, so that the control at the beginning of the brake operation can be prevented from becoming unstable and the engine brake is used as much as possible. It is possible to prevent the lifespan from being lowered and to prevent the passenger from feeling uncomfortable.

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

  FIG. 1 shows a vehicle W (corresponding to the host vehicle) equipped with a brake control device according to an embodiment of the present invention, and detects a preceding vehicle existing in front of the vehicle W at the front end of the vehicle W. A radar device 1 is provided as detection means. This radar device 1 is a millimeter wave radar device, and transmits a millimeter wave toward the front while transmitting a predetermined angle range in a substantially horizontal direction, and the millimeter wave hits an obstacle in front of the vehicle W. And a receiving unit for receiving the reflected wave reflected. The radar apparatus 1 detects the distance and relative speed of the obstacle received (detected) by the receiving unit and the vehicle W, and transmits the detected data to the control unit 11 as obstacle detection information. ing.

  The vehicle W is provided with a control unit 11 that receives the obstacle detection information from the radar device 1 and controls the vehicle W. In the present embodiment, the control unit 11 applies a braking force to the throttle valve opening / closing actuator 20 and each wheel 31 of the vehicle W based on the obstacle detection information when the obstacle is a preceding vehicle. By following the wheel brake actuating means 21 including a hydraulic pump or the like, follow-up running control is carried out to cause the vehicle W to follow the preceding vehicle (when there is no preceding vehicle, the vehicle W is set at the target vehicle speed set by the passenger). (Constant running speed control is performed). The control unit 11 determines whether the detected obstacle is a moving object or a stationary object based on the relative speed between the vehicle W and the obstacle and the vehicle speed of the vehicle W, and In some cases, it is determined whether the vehicle is a preceding vehicle. When the obstacle is a preceding vehicle, the distance between the obstacle and the vehicle W detected by the radar device 1 is the inter-vehicle distance between the preceding vehicle and the vehicle W. With this, the radar device 1 This constitutes a distance detection means.

  Further, as shown in FIG. 2, the vehicle is provided with a vehicle speed sensor 12 for detecting the vehicle speed of the vehicle W and a yaw rate sensor 13 for detecting a yaw rate generated in the vehicle W. Detection information is input to the control unit 11.

  The control unit 11 stores a preset inter-vehicle time (when the preceding vehicle stops, the time from when the preceding vehicle stops until the vehicle W reaches the preceding vehicle at the current speed). Sometimes, the target inter-vehicle distance is set based on the inter-vehicle time and the vehicle speed of the preceding vehicle (obtained from the relative speed detected by the radar device 1 and the speed of the vehicle W detected by the vehicle speed sensor 12). Then, the target acceleration / deceleration is calculated based on the difference between the set target inter-vehicle distance and the current inter-vehicle distance and the relative speed (for example, according to the difference between the target inter-vehicle distance and the current inter-vehicle distance and the relative speed). A map for determining the target acceleration / deceleration is created in advance, and the target acceleration / deceleration is calculated from this map). Based on the calculated target acceleration / deceleration, the throttle valve opening / closing actuator 20 and the wheel brake operating means 21 are controlled. To do.

  When the target acceleration / deceleration is acceleration (positive value), the control unit 11 controls the acceleration of the vehicle W by operating the throttle valve opening / closing actuator 20, while the target acceleration / deceleration is deceleration (negative value). In some cases, the vehicle W is decelerated and controlled by at least one of the throttle valve opening / closing actuator 20 and the wheel brake operating means 21 (that is, engine brake and wheel brake) according to the target deceleration. As a result, the control unit 11 constitutes a deceleration control means. In the present embodiment, as will be described later, the vehicle W is decelerated and controlled by operating only the engine brake or both the engine brake and the wheel brake in accordance with the target deceleration. The engine brake may be a combination of the throttle valve opening / closing actuator 20 and the transmission.

The control unit 11 is configured to estimate the turning radius of the vehicle W, that is, the curvature radius of the traveling path of the vehicle W based on the detection values of the vehicle speed sensor 12 and the yaw rate sensor 13. Specifically, the turning radius (curvature radius of curvature of the traveling path) R of the vehicle W is set such that the yaw rate is φ, the speed of the vehicle W is V,
R = V / φ
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  Then, the control unit 11 determines whether or not the preceding vehicle exists on the estimated traveling path during the follow-up traveling control, and determines that the preceding vehicle is the vehicle W when it is determined that the preceding vehicle is present. If it is determined that the vehicle is traveling in the same lane as described above and the follow-up traveling control is continued as it is, while it is determined that the preceding vehicle does not exist on the traveling path, it is determined that the preceding vehicle or the vehicle W has changed the lane. Thus, the constant speed traveling control is performed.

  Here, the deceleration control by the control unit 11 will be described in detail.

In the present embodiment, when the magnitude of the target deceleration (the absolute value of the target acceleration / deceleration) is greater than a preset set value (corresponding to a “set value” in claim 3), While the vehicle W is decelerated and controlled by operating both the engine brake and the wheel brake, the vehicle W is decelerated and controlled only by operating the engine brake when the target deceleration is less than the set value. Yes. The set value may be a deceleration corresponding to the brake force close to the maximum obtained by the operation of only the throttle valve opening / closing actuator 20, and is set to 0.3 m / s ² , for example. When the vehicle W is decelerated and controlled by operating only the engine brake, open control is performed.

  Therefore, the control unit 11 is in a state where the magnitude of the target deceleration becomes larger than the set value from the state where both the brakes are not operated (that is, from acceleration (including neither acceleration nor deceleration)). The vehicle W is decelerated and controlled by operating both the brakes. Thus, the set value corresponds to a “predetermined value” in claim 2.

  Then, the control unit 11 starts the operation by delaying the engine brake by a predetermined time from the wheel brake when the vehicles W are decelerated and controlled by operating both the brakes from the state where the both brakes are not operated. It is configured as follows. That is, the deceleration control by the wheel brake feeds back the vehicle deceleration detected by the vehicle speed sensor 12 (which may be a wheel speed sensor that detects the rotation speed of the wheel 31) for controlling the hydraulic pressure supplied to the wheel. However, since the deceleration of the vehicle W is detected with a delay while applying a large braking force, the deceleration of the vehicle W tends to overshoot. Here, if only the wheel brake is operated, the overshoot can be suppressed as much as possible and converged as soon as possible. However, when the deceleration by the engine brake is added, how much the operation of the engine brake contributes to the deceleration. However, since it is not known at the beginning of the operation, the overshooting is too much, and it takes time to converge or the control diverges. Therefore, in this embodiment, the engine brake is operated after waiting for a predetermined time (for example, 0.5 s) in which the deceleration is substantially stabilized by the operation of the wheel brake. Due to the operation of the engine brake, the braking force by the wheel brake is reduced by the amount of the braking force by the engine brake.

  When only the engine brake is operating (that is, when the target deceleration is less than or equal to the set value), when the target deceleration is greater than the set value, the engine brake is The wheel brakes are operated while operating at the same size.

  Next, the processing operation of the follow-up running control in the control unit 11 will be described with reference to the flowcharts of FIGS. This processing operation is repeatedly performed every preset reference time (a time corresponding to the millimeter wave scanning time in the radar apparatus 1).

First, in the first step S1, the vehicle speed V and the yaw rate φ are respectively input from the vehicle speed sensor 12 and the yaw rate sensor 13, and in the next step S2, the radius of curvature R of the traveling path of the vehicle W is based on the vehicle speed V and the yaw rate φ. The
R = V / φ
Thus, the traveling path of the vehicle W is estimated.

  In the next step S3, obstacle detection information is input from the radar device 1, and in the next step S4, it is determined whether or not the preceding vehicle is on the estimated traveling path (that is, on the same lane as the vehicle W). .

  When the determination in step S4 is NO, the process proceeds to step S5 to perform constant speed traveling control processing, and then returns. On the other hand, when the determination in step S4 is YES, the process proceeds to step S6, and the vehicle speed of the preceding vehicle is calculated from the relative speed of the preceding vehicle with respect to the vehicle W and the vehicle speed of the vehicle W detected by the vehicle speed sensor 12.

  In the next step S7, the target inter-vehicle distance is calculated from the inter-vehicle time preset and stored and the vehicle speed of the preceding vehicle, and in the next step S8, the difference between the target inter-vehicle distance and the current inter-vehicle distance and the relative speed are calculated. Based on the above, the target acceleration / deceleration is calculated from the map.

  In the next step S9, it is determined whether or not the target acceleration / deceleration is a deceleration. When the determination in step S9 is NO, the process proceeds to step S10, the timer is set to the predetermined time T, acceleration control is performed by the operation of the throttle valve opening / closing actuator 20 in the next step S11, and then the process returns. .

  On the other hand, when the determination in step S9 is YES, the process proceeds to step S12 to determine whether or not the target deceleration magnitude is larger than the set value. When the determination in step S12 is NO, the process proceeds to step S13, the timer is set to 0, and in the next step S14, the engine brake is operated to perform deceleration control, and then the process returns.

  On the other hand, when the determination in step S12 is YES, the process proceeds to step S15 to determine whether or not the set value of the timer is 0. When the determination in step S12 is YES, the process proceeds to step S16, the engine brake is operated, and in step S17, the wheel brake is operated to perform deceleration control, and then the process returns.

  On the other hand, when the determination in step S15 is NO, the process proceeds to step S18, the timer is set to a value obtained by subtracting the reference time from the set value of the timer, and then the process proceeds to step S17. Return.

  When the target acceleration / deceleration is not a deceleration due to the processing operation of the control unit 11, a timer is set at a predetermined time T and acceleration control is performed by operating the throttle valve opening / closing actuator 20. When the target deceleration magnitude becomes larger than the set value from this state, the operation of the engine brake is suppressed and only the wheel brake is operated until the set value of the timer becomes zero. When the set value of the timer becomes 0, that is, when a predetermined time T has elapsed from the start of the wheel brake operation, the engine brake also starts operating, and deceleration control is performed by both the engine brake and the wheel brake. This eliminates instability of control due to the engine brake being applied at the beginning of wheel brake operation.

  If the target deceleration is less than or equal to the set value, the timer is set to 0 and deceleration control is performed by operating only the engine brake. If the target deceleration magnitude becomes larger than the set value from this state, the set value of the timer is 0, so that deceleration control is immediately performed by both the engine brake and the wheel brake. At this time, the wheel brake is operated from a state in which the deceleration of the vehicle W is substantially stable. From this state, the wheel brake is operated only from the state where both brakes are not operated. The control is not unstable.

  Therefore, in this embodiment, when the target deceleration magnitude is larger than the set value, the vehicle W is decelerated and controlled by operating both the engine brake and the wheel brake, while the target deceleration magnitude is set to the set value. In the following cases, since the vehicle W is controlled to be decelerated only by operating the engine brake, the engine brake is operated as much as possible so that the wheel brake is not operated, so that the life of the wheel brake can be prevented from being shortened. When it is necessary to apply a large braking force abruptly while preventing a sense of incongruity, the brakes can be applied accurately by operating both brakes.

  In addition, in the present embodiment, when both the brakes are operated and the vehicle W is decelerated and controlled from a state in which both brakes are not operated, the engine brake is delayed from the wheel brake by a predetermined time so that the operation is started. Therefore, it is possible to prevent instability of control due to the engine brake being applied at the beginning of the wheel brake operation.

  In the above embodiment, when the target deceleration magnitude is larger than the set value, the vehicle W is decelerated and controlled by operating both the engine brake and the wheel brake, while the target deceleration magnitude is set to the set value. In the following cases, the vehicle W is controlled to be decelerated only by operating the engine brake. However, there are cases where both the brakes are activated and the own vehicle is decelerated and controlled from a state where both brakes are not activated. If present, the present invention can be applied.

  In the above embodiment, the radar apparatus 1 is a millimeter wave radar apparatus, but any kind of radar apparatus may be used.

  The present invention relates to a brake control device for a vehicle, in which the host vehicle is decelerated and controlled by operating at least one of an engine brake and a wheel brake according to a target deceleration when the host vehicle is running following the preceding vehicle. This is particularly useful for a case where there is a case in which both the brakes are operated to decelerate and control the own vehicle from a state where both brakes are not operated.

It is a block diagram of the vehicle front side which mounts the brake control apparatus which concerns on embodiment of this invention. It is a block diagram which shows the structure of the said brake control apparatus. It is a flowchart which shows the first half part of the processing operation of the follow-up running control in a control unit. It is a flowchart which shows the latter half part of the processing operation of the said follow-up driving control.

Explanation of symbols

W vehicle (own vehicle)
1 Radar device (preceding vehicle detection means) (vehicle distance detection means)
11 Control unit (Target vehicle distance setting means)
(Target acceleration / deceleration calculation means) (Deceleration control means)

Claims (3)

A preceding vehicle detecting means for detecting a preceding vehicle ahead of the own vehicle; an inter-vehicle distance detecting means for detecting an inter-vehicle distance between the preceding vehicle detected by the preceding vehicle detecting means and the own vehicle; and a target of the preceding vehicle and the own vehicle. The target acceleration / deceleration of the host vehicle is set so that the target inter-vehicle distance setting means for setting the inter-vehicle distance and the inter-vehicle distance detected by the inter-vehicle distance detection means maintain the target inter-vehicle distance set by the target inter-vehicle distance setting means. When the target acceleration / deceleration calculation means to be calculated and the target acceleration / deceleration calculated by the target acceleration / deceleration calculation means are decelerations, depending on the target deceleration, the operation is automatically performed by at least one of the engine brake and the wheel brake. A vehicle brake control device comprising a deceleration control means for controlling the vehicle deceleration,
The deceleration control means starts the operation by delaying the engine brake by a predetermined time from the wheel brake when the deceleration control of the host vehicle is performed by operating both the brakes from a state where the both brakes are not operating. A brake control device for a vehicle, comprising: The vehicle brake control device according to claim 1,
The deceleration control means operates both brakes when the target deceleration calculated by the target acceleration / deceleration calculation means exceeds a predetermined value from a state where both brakes are not operated. The vehicle brake control device is configured to decelerate and control the host vehicle. The vehicle brake control device according to claim 1,
When the magnitude of the target deceleration calculated by the target acceleration / deceleration calculating means is larger than a preset set value, the deceleration control means performs deceleration control of the host vehicle by operating both brakes, A brake control apparatus for a vehicle, wherein when the magnitude of the target deceleration is equal to or less than the set value, the host vehicle is decelerated and controlled by operating only the engine brake.

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