JP4877593B2 - Vehicle control device - Google Patents

Description

  The present invention relates to a parking brake device capable of braking while a vehicle is traveling, and a vehicle control device that cooperatively controls a behavior control device.

  The parking brake is a mechanical brake device used mainly for the purpose of preventing the vehicle from starting to move when the vehicle is parked and stopped. In the case of a four-wheeled vehicle, the rear two wheels are generally braked. Parking brakes that generate braking force by a driver pulling a Bowden wire using a lever or a pedal, for example, are widely used. Such parking brakes are used even when the vehicle is running. Can be used to assist hydraulic service brakes.

The electric parking brake drives a mechanical parking brake that performs braking when the vehicle is parked or stopped using an electric actuator.
The electric parking brake can be operated by an electric switch operation by the driver, or can be automatically driven by determining whether braking is necessary according to the state of the vehicle. On the other hand, the labor of the driver can be reduced.
Such an electric parking brake is also known that enables dynamic braking that generates a braking force while the vehicle is traveling (see, for example, Patent Document 1).

In addition, the behavior control device (stability control device) activates the brakes of some wheels when the yaw rate of the vehicle is smaller (in the case of understeer) or larger (in the case of oversteer). In this way, control for generating a yaw moment that stabilizes the vehicle is performed (see, for example, Patent Document 2).
In general, such a behavior control device can select on / off of behavior control by a driver's operation.
JP 2005-81964 A JP 2003-231428 A

As described above, when braking with the parking brake during traveling, since only the rear wheels are normally braked, the cornering force at which the rear wheels can be generated decreases relative to the front wheels and the vehicle overloads. There is a concern of a tendency to steer. In particular, when the rear wheel is locked, extreme oversteer may occur.
The subject of this invention is providing the vehicle control apparatus which can ensure the steering stability of a vehicle at the time of braking of the parking brake in driving | running | working.

The present invention solves the above-described problems by the following means.
According to a first aspect of the present invention, there is provided a yaw moment control means that generates a yaw moment by braking some of the wheels of the vehicle according to a behavior of the vehicle, and an operation standby state and a non-operation state of the yaw moment control means. Selecting means for selecting by operation of the driver; and dynamic braking detecting means for detecting braking of the parking brake device during traveling, wherein the yaw moment control means is configured to provide the parking brake during traveling in the inoperative state. The vehicle control device changes from the inactive state to the active standby state in response to detection of braking of the device.

  According to a second aspect of the present invention, in the vehicle control device according to the first aspect, the parking brake device is an electric parking brake device that is driven by an electric actuator, and the dynamic braking detecting means includes the electric actuator. It is an electric parking brake control means having a dynamic braking function for controlling and generating a braking force during traveling of the vehicle.

  According to a third aspect of the present invention, in the vehicle control device according to the first or second aspect, a target yaw rate calculating unit that calculates a target yaw rate of the vehicle, and a yaw rate detecting unit that detects an actual yaw rate of the vehicle. The yaw moment control means executes control to generate the yaw moment when a comparison value obtained by comparing the outputs of the target yaw rate calculation means and the yaw rate detection means is larger than a predetermined intervention threshold; The vehicle control apparatus is characterized in that the intervention threshold value is set smaller during braking of the parking brake device than during non-braking.

  According to a fourth aspect of the present invention, in the vehicle control device according to any one of the first to third aspects, a target yaw rate calculating means for calculating a target yaw rate of the vehicle and an actual yaw rate of the vehicle are detected. And a yaw moment control means for controlling a part of the vehicle with a target braking force set in accordance with a comparison value obtained by comparing outputs of the target yaw rate calculation means and the yaw rate detection means. The vehicle control device is characterized in that the yaw moment is generated by braking the wheels of the vehicle, and the target braking force is set larger during braking of the parking brake device than during non-braking.

  According to a fifth aspect of the present invention, in the vehicle control device according to any one of the first to fourth aspects, the yaw moment control means is configured to change the non-operating state to the operational standby state. The vehicle control device is configured to return to the non-operating state in response to detection of braking completion of the parking brake device during traveling.

According to the present invention, the following effects can be obtained.
(1) Even when the inoperative state of the yaw moment control means is selected, the parking brake device can be braked by changing to the operation standby state in response to detection of braking of the parking brake device during traveling. It is possible to stabilize the vehicle by generating a yaw moment in the opposite direction at the time of occurrence of oversteering and the like, and to ensure the steering stability of the vehicle.
(2) Yaw moment control is performed even in the case of an electric parking brake device that is difficult to adjust the braking force by the driver during braking of the parking brake device during traveling and is difficult to release immediately when the wheels are locked. Therefore, the steering stability can be ensured.
(3) By setting a small intervention threshold during braking of the parking brake device during traveling, the intervention timing of yaw moment control can be advanced, and steering stability during dynamic braking that tends to be unstable can be ensured. .
(4) By setting a large target braking force for generating a yaw moment during braking of the parking brake device during traveling, the yaw moment in the direction of stabilizing the vehicle is further increased and the behavior becomes unstable. Steering stability during easy dynamic braking can be ensured.

  An object of the present invention is to provide a vehicle control device that can ensure vehicle handling stability during braking (dynamic braking) of a parking brake while traveling. The behavior control device is turned off during dynamic braking by an electric parking brake. However, the problem was solved by automatically entering the standby state and controlling the yaw moment when the behavior became unstable.

Embodiments of a braking control apparatus to which the present invention is applied will be described below.
FIG. 1 is a block diagram illustrating a configuration of a vehicle including the vehicle control device of the embodiment.
In the embodiment, the vehicle is a four-wheeled vehicle such as a passenger car.
The vehicle includes an electric parking brake device including a parking brake 10, an actuator unit 20, a battery 30, an electric parking brake controller (hereinafter simply referred to as “controller”) 40, a parking brake operation switch 50, and an engine control unit 60. , A transmission control unit 70, a behavior control device 100, and the like.

  The parking brake 10 is a braking device that prevents the vehicle from moving when the vehicle is parked or the like, for example, by braking the wheels of the vehicle. The parking brake 10 is provided on each of the wheel hub portions of the left and right rear wheels of the vehicle. The parking brake 10 includes a brake drum (not shown) disposed on the inner diameter side of a rotor of a disc brake used as a foot brake (main brake) and a brake shoe (not shown) that pressurizes and contacts the inner diameter side of the brake drum during braking. It is a so-called drum-in-disk type mechanical brake.

The actuator unit 20 drives the shoe of the parking brake 10 and makes a transition between a braking state in which the parking brake 10 generates a braking force and a released state in which the braking force is not substantially generated. The actuator unit 20 includes a parking brake cable 21 and is fixed to, for example, the under floor side of the luggage floor portion of the vehicle.
The actuator unit 20 is, for example, for reducing the rotational force of the DC motor by a reduction gear train to rotate the lead screw, and pulling or relaxing the parking brake cable 21 by an equalizer screwed to the lead screw.

  The parking brake cables 21 are provided corresponding to the left and right parking brakes 10, respectively, and have flexibility so as to be deformed according to a stroke of a rear suspension (not shown). The parking brake cable 21 is a Bowden cable that brings the parking brake 10 into a braking state by being pulled, and releases the parking brake 10 by being relaxed.

  Here, the actuator unit 20 has a function of adjusting the braking force of the parking brake 10 in the braking state by adjusting the traction force applied to the parking brake cable 21. The adjustment of the traction force is performed by controlling the power supply to the actuator unit 20 to change the stroke for pulling the parking brake cable 21. For this reason, the actuator unit 20 has a stroke sensor (not shown) that detects the traction stroke. It has.

The battery 30 is a secondary battery that is used as a main power source for a vehicle electrical system, and generates, for example, a DC 12V terminal voltage. The battery 30 includes a plus terminal 31 and a minus terminal 32.
The plus terminal 31 is connected to each electrical component such as the controller 40 via wiring (harness). As shown in FIG. 1, the wiring for supplying power from the plus terminal 31 to the controller 40 is provided with an ignition wiring 31a and a constant connection wiring 31b. The ignition wiring 31a is inserted at its intermediate portion with an ignition relay I which is switched between conduction and interruption in conjunction with the on / off of the ignition switch, and is energized when the engine, which is the driving power source of the vehicle, is on (running). is there. The always-connected wiring 31b is always energized regardless of the operation of the ignition switch, and is used for holding various data in the ECU 41 of the controller 40 or the like.
The minus terminal 32 is grounded to the metal part of the vehicle body.

  The controller 40 is an electric parking brake control unit that controls the actuator unit 20 to change the traction force of the parking brake cable 21 to switch between the released state and the braking state of the parking brake 10 and change the braking force. ECU 41, relay 42, and G sensor 43 are provided.

The ECU 41 determines whether braking of the parking brake 10 is necessary or not according to inputs from the parking brake operation switch 50, the engine control unit 60, the behavior control unit 110 of the behavior control device 100, a brake lamp switch (not shown), and the like. A CPU is provided that performs extra pull control for increasing the braking force when the vehicle stops on the road.
Further, when the parking brake 10 is in a braking state, the ECU 41 outputs a signal (parking brake operation signal) indicating that the parking brake 10 is in a braking state to the behavior control unit 110 of the behavior control device 100 described later.

The relay 42 is a power supply unit that supplies driving power to the actuator unit 20 in accordance with a control signal output from the ECU 41. The relay 42 has a function of reversing the polarity of the drive power in order to make the transition of the parking brake 10 from the braking state to the release state and from the release state to the brake state, and when the actuator unit 20 is not driven. Is in a neutral state where conduction with the actuator unit 20 is interrupted.
The G sensor 43 includes an acceleration sensor that detects acceleration in the front-rear direction of the vehicle, and is an acceleration detection unit that inputs the output to the ECU 41.

The parking brake operation switch 50 is an operation unit through which a user such as a driver inputs a braking operation of the parking brake 10, a manual selection operation of a release state, an additional operation, an auto mode selection operation, and the like. For example, a push button switch mounted on an instrument panel (not shown) of the vehicle is provided. The parking brake operation switch 50 transmits the input to the controller 40, and the controller 40 supplies driving power to the actuator unit 20 in response to this to drive the parking brake 10.
In addition, the electric parking brake of the present embodiment can perform dynamic braking that generates the braking force by driving the parking brake 10 during traveling by operating the parking brake operation switch 50 while the vehicle is traveling. This dynamic braking can be used, for example, as a service brake assist or an emergency brake.

The engine control unit 60 controls the engine of the vehicle and its auxiliary devices, and performs throttle opening control and fuel injection control according to engine output control performed by the behavior control unit 110 of the behavior control device 100 described later. It has a function to adjust engine output.
The transmission control unit 70 controls the automatic transmission of the vehicle and the transfer that distributes the front and rear driving force of the four-wheel drive. The transmission control unit 70 controls the transfer clutch according to the driving force distribution control performed by the behavior control unit 110 of the behavior control device 100. It has a function to control and adjust the driving force distribution of the front and rear axles.

The behavior control device (vehicle stability control device) 100 detects unstable behavior such as excessive oversteer and understeer based on the result of comparing the target yaw rate calculated from the driving conditions of the vehicle with the actual yaw rate. On the other hand, a yaw moment in a direction that cancels the behavior is generated by applying a braking force to some of the wheels, thereby stabilizing the vehicle.
The behavior control apparatus 100 includes a behavior control unit 110, a vehicle speed sensor 120, a yaw rate sensor 130, a rudder angle sensor 140, a brake drive unit 150, a wheel cylinder 160, and a behavior control switch 170.

The behavior control unit 110 comprehensively controls each part of the behavior control device 100.
Also, the behavior control unit 110 sets a target yaw rate that is an appropriate yaw rate to be obtained when excessive understeer or oversteer is not generated in the vehicle based on inputs from the vehicle speed sensor 120, the steering angle sensor 140, and the like. It functions as a target yaw rate calculation means for calculating.
Furthermore, the behavior control unit 110 compares the actual yaw rate of the vehicle detected by the yaw rate sensor 130 with the target yaw rate, and generates a comparison value that is a parameter correlated with the amount of deviation between them. If this comparison value is larger than a predetermined intervention threshold value, a signal is output to the brake drive unit 150, a braking force is generated on some wheels to generate a yaw moment, and an unstable behavior is canceled out. Yaw moment generation control that stabilizes the vehicle. For example, when oversteer occurs during turning, the yaw moment generated by oversteer is canceled by braking the outer front wheel. At this time, the target braking force for braking to generate the yaw moment is set according to the magnitude of the comparison value described above.
The behavior control unit 110 also performs engine output control and driving force distribution control in cooperation with the engine control unit 60 and the transmission control unit 70.

The vehicle speed sensor 120 detects the wheel speed of each wheel of the vehicle. For example, the vehicle speed sensor 120 is provided in a wheel hub portion of each wheel, and outputs a vehicle speed pulse signal corresponding to the rotation speed of a tone wheel that rotates with the wheel. Thus, the traveling speed (vehicle speed) of the vehicle is used for detection.
The vehicle speed sensor 120 includes a right front wheel sensor 120FR, a left front wheel sensor 120FL, a right rear wheel sensor 120RR, and a left rear wheel sensor 120RL.

The yaw rate sensor 130 is a yaw rate detection unit that includes, for example, a vibration gyro and detects an actual yaw rate of the vehicle.
The steering angle sensor 140 is a position encoder provided in a steering system (not shown) of the vehicle. When the driver operates a steering wheel (not shown), the steering angle sensor 140 senses the direction and angle of the steering, and outputs a signal corresponding thereto. This is output to the behavior control unit 110.

  The brake drive unit 150 is a hydraulic control unit that controls a brake fluid pressure applied to a wheel cylinder 160 of a hydraulic brake used as a service brake of a vehicle. The brake drive unit 150 includes a pump motor that operates in response to a signal from the behavior control unit 110 and a solenoid valve that changes an oil passage, and controls the hydraulic pressure to each wheel cylinder 160.

The wheel cylinder 160 is provided in a brake caliper (not shown) of a brake device of each wheel, and when a hydraulic pressure of a brake fluid generated by a brake master cylinder (not shown) connected to a brake pedal (not shown) and the brake driving unit 150 is loaded. The brake pad is brought into pressure contact with the rotor to generate a braking force.
The wheel cylinder 160 includes a right front wheel cylinder 160FR, a left front wheel cylinder 160FL, a right rear wheel cylinder 160RR, and a left rear wheel cylinder 160RL.

  The behavior control switch 170 is an operation unit that allows the driver to select an operation standby state and a non-operation state of the behavior control device 100. Here, the operation standby state is a state in which the above-described target yaw rate is compared with the actual yaw rate, and when an unstable behavior is detected, preparation for immediately performing yaw moment generation control is performed. The operating state is an off state in which such an operation is not performed.

  In addition, the controller 40, the engine control unit 60, the transmission control unit 70, the behavior control unit 110, and the like described above can communicate with each other via a CAN communication system that is a kind of in-vehicle LAN.

Next, the control at the time of dynamic braking of the electric parking brake in the vehicle control apparatus of the embodiment will be described.
FIG. 2 is a flowchart showing control during dynamic braking. Hereinafter, the steps will be described step by step.

<Step S01: Behavior control off determination>
The behavior control unit 110 determines whether or not the behavior control device 100 is in an inoperative state by the behavior control switch 170. When the behavior control unit 100 is in an inoperative state, the process proceeds to step S02. repeat.

<Step S02: Electric parking brake dynamic braking execution determination>
Based on the parking brake operation signal from the controller 40 and the output of the vehicle speed sensor 120, the behavior control unit 110 determines whether or not dynamic braking has been performed so that the parking brake 10 is brought into a braking state while the vehicle is traveling.

<Step S03: Standby for behavior control operation>
The behavior control unit 110 changes the behavior control device 100 to the operation standby state regardless of the state of the behavior control switch 170, and proceeds to step S04. As a result, the comparison between the target yaw rate and the actual yaw rate, the generation of the comparison value, and the comparison between the comparison value and the intervention threshold value are started.

<Step S04: Behavior control intervention threshold / characteristic change>
The behavior control unit 110 changes the intervention threshold to an intervention threshold for parking brake dynamic braking that is smaller than a normal value.
In addition, the behavior control unit 110 changes the correlation characteristic between the comparison value and the target braking force for generating the yaw moment so that the target braking force becomes larger with respect to the same comparison value.
If the comparison value exceeds the intervention threshold value for parking brake dynamic braking, yaw moment generation control is performed with a target braking force larger than usual.
Proceed to step S05.

<Step S05: Electric parking brake dynamic braking end determination>
The behavior control unit 110 determines whether or not the dynamic braking of the parking brake 10 has ended. The end of the dynamic braking is detected by determining whether the vehicle is stopped based on the end of the parking brake operation signal from the controller 40 or the output of the vehicle speed sensor 120.
If it is determined that dynamic braking has ended, the process proceeds to step S06. If it is determined that dynamic braking has not ended yet, step S05 is repeated.
<Step S06: Behavior control off>
The behavior control unit 110 returns the behavior control device 100 to the non-operating state.

According to the embodiment described above, the following effects can be obtained.
(1) Even when the driver selects the non-operating state (off state) of the behavior control device 100, the behavior control device 100 is put into an operation standby when the parking brake 10 is dynamically braked. If the vehicle behavior becomes unstable, the yaw moment generation control is performed, and even if oversteering occurs due to braking of the rear two wheels, the yaw moment due to oversteer is canceled out and the vehicle The steering stability can be ensured.
(2) In the case of the electric parking brake as in the embodiment, it is difficult for the driver to finely adjust the braking force as compared with the manual parking brake, and it can be released immediately even if the wheel is locked. Although difficult, the behavior control device can also be used in this case to ensure the steering stability of the vehicle.
(3) By setting the intervention threshold value of the behavior control apparatus 100 to be small during dynamic braking, the intervention of yaw moment generation control can be performed at an early stage, and the steering stability during dynamic braking when the behavior tends to become unstable. Can be secured.
(4) By dynamically setting the target braking force for generating the yaw moment during dynamic braking to increase the yaw moment in the direction that stabilizes the vehicle, and during dynamic braking where the behavior tends to become unstable Steering stability can be ensured.
(5) Since the behavior control device 100 automatically returns to the non-actuated state after the end of the dynamic braking, the operation is not troublesome and user-friendly.

(Modification)
The present invention is not limited to the embodiments described above, and various modifications and changes are possible, and these are also within the technical scope of the present invention.
(1) In the embodiment, the parking brake device is an electric parking brake device, but the present invention is not limited to this, and can also be applied to a vehicle equipped with a manual lever type or foot pedal type parking brake device. In this case, dynamic braking can be detected based on the parking brake switch signal and the vehicle speed.
(2) In the embodiment, the behavior control device brakes some of the wheels to generate a yaw moment. However, the present invention is not limited to this, for example, adjustment of left / right driving force distribution or automatic by active steering. A yaw moment may be generated by steering, or each wheel braking force, each wheel driving force may be adjusted and automatic steering may be performed in combination.
(3) The configuration of the electric parking brake device is not limited to that of the embodiment, and can be changed as appropriate.
For example, the parking brake of the embodiment uses a drum arranged on the inner diameter side of a brake disc for a foot brake, but the parking brake may be of other types, for example, a foot brake. The disc brake or drum brake for brake and its friction material may be shared and integrated with the parking brake.
Further, the parking brake of the embodiment uses an electric actuator fixed on the body side and drives the parking brake via a parking brake cable. However, the present invention is not limited to this, and for example, the electric actuator is a wheel. The present invention can also be applied to a so-called built-in type electric parking brake provided on the hub side and integrated with the parking brake.

It is a figure which shows the structure of the Example of the vehicle control apparatus to which this invention is applied. It is a flowchart which shows the control at the time of dynamic braking of the electric parking brake in the vehicle control apparatus of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Parking brake 20 Actuator unit 30 Parking brake cable 40 Electric parking brake controller 41 ECU
43 G sensor 50 parking brake operation switch 60 engine control unit 70 transmission control unit 100 behavior control device 110 behavior control unit 120 vehicle speed sensor 130 yaw rate sensor 140 rudder angle sensor 150 brake drive unit 160 wheel cylinder 170 behavior control switch

Claims (5)

A yaw moment control means for generating a yaw moment by braking some of the wheels of the vehicle according to the behavior of the vehicle;
A selection means for selecting an operation standby state and a non-operation state of the yaw moment control means by a driver's operation ;
Dynamic braking detecting means for detecting braking of the parking brake device during traveling,
The vehicle control device, wherein the yaw moment control means changes from the non-operating state to the operation standby state in response to detection of braking of the parking brake device during traveling in the non-operating state. The vehicle control device according to claim 1,
The parking brake device is an electric parking brake device driven by an electric actuator,
The vehicle control apparatus, wherein the dynamic braking detecting means is an electric parking brake control means having a dynamic braking function for controlling the electric actuator to generate a braking force during traveling of the vehicle. In the vehicle control device according to claim 1 or 2,
Target yaw rate calculating means for calculating a target yaw rate of the vehicle;
A yaw rate detecting means for detecting an actual yaw rate of the vehicle,
The yaw moment control means executes control to generate the yaw moment when a comparison value obtained by comparing the outputs of the target yaw rate calculation means and the yaw rate detection means is larger than a predetermined intervention threshold, The vehicle control device according to claim 1, wherein the intervention threshold value is set smaller during braking of the parking brake device than during non-braking. In the vehicle control device according to any one of claims 1 to 3,
Target yaw rate calculating means for calculating a target yaw rate of the vehicle;
A yaw rate detecting means for detecting an actual yaw rate of the vehicle,
The yaw moment control means brakes some of the wheels of the vehicle with a target braking force set according to a comparison value obtained by comparing the outputs of the target yaw rate calculation means and the yaw rate detection means. A vehicle control device that generates a yaw moment and sets the target braking force larger when braking the parking brake device during traveling than when not braking. In the vehicle control device according to any one of claims 1 to 4,
The yaw moment control means returns to the non-operating state in response to detection of braking completion of the parking brake device during traveling after the change from the non-operating state to the operation standby state. Vehicle control device.

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