JP4517966B2 - Vehicle braking device, shock reduction method, braking control device - Google Patents

Description

  The present invention relates to a technique for reducing a shock applied to an occupant when a vehicle is stopped.

  Generally, when the brake pressure is kept constant until the moment when the vehicle stops, a stop shock occurs. This is due to the fact that the wheels first stop when the vehicle is stopped, and then the vehicle body to be advanced due to inertia is pulled by the stopped wheels, and the suspension recoils when the vehicle stops. Since this stop shock greatly reduces the ride comfort of the occupant, the driver loosens the brake pedal and reduces the deceleration of the vehicle immediately before the vehicle stops.

In Patent Document 1, in the vehicle brake device that reduces the stopping shock by reducing the braking force when the vehicle is stopped, the stopping shock reduction control is executed so that the stopping shock reduction control is performed or not performed depending on the braking situation. Changing the rate is disclosed.
JP-A-4-5155 JP-A-4-151357 JP-A-5-270376

  However, in Patent Document 1, only the braking state of the vehicle is observed to change the execution rate of the stop shock reduction control. In actual vehicle travel, it is difficult to reduce the stop shock in an arbitrary situation unless the brake pressure is controlled with high accuracy in accordance with the situation of the vehicle.

  The present invention has been made in view of such a situation, and an object of the present invention is to acquire various parameters that affect the deceleration of the vehicle and execute control according to the values of the parameters, so that the vehicle is stopped. It is to provide a technique for reducing shock.

  An aspect of the present invention is a braking device that reduces a shock when the vehicle stops. This device includes a wheel braking unit that brakes a wheel by hydraulic pressure supplied in accordance with an operation of a brake operation member, a vehicle speed detection unit that detects a vehicle speed, and a state immediately before the vehicle stops when the vehicle speed becomes a predetermined value or less. A stop state determining means for determining that the vehicle is in a state, a parameter detecting means for detecting a parameter that affects the deceleration of the vehicle when it is determined that the vehicle is in a state immediately before the stop, and reducing the deceleration immediately before the vehicle is stopped. A hydraulic pressure pattern storage means for storing a plurality of hydraulic pressure patterns corresponding to the parameters, and a hydraulic pressure for selecting a hydraulic pressure pattern corresponding to the parameter detected by the parameter detection means from the hydraulic pressure pattern storage means Pattern selection means, hydraulic pressure pattern correction means for correcting the selected hydraulic pressure pattern in accordance with the value of the parameter, and corrected hydraulic pressure pattern Comprising a hydraulic control means for controlling the hydraulic pressure supplied to the wheel braking means according to over emissions, and.

According to this aspect, a parameter that affects the deceleration of the vehicle is acquired, and a different basic hydraulic pressure pattern is selected according to the state of the vehicle estimated from the parameter, so appropriate shock reduction according to each situation Is possible. Further, since the driver does not need to loosen the brake pedal spontaneously just before stopping, the shock at the time of stopping the vehicle can be reduced regardless of the skill of the driver.
An example of the “wheel braking means” is the wheel cylinder 20 in the embodiment.

  The parameter detection means detects the steering angle of the vehicle, and the hydraulic pressure pattern correction means reduces the pressure reduction width of the turning hydraulic pressure pattern and increases the hydraulic pressure pattern on the opposite side of the turning as the steering angle increases. The reduced pressure range may be increased. According to this, braking is applied more gently when the vehicle is turning than when the vehicle is traveling straight, and the riding comfort can be improved.

  The parameter detecting means may detect the inclination angle of the vehicle, and the hydraulic pressure pattern correcting means may increase the pressure reduction width of the hydraulic pressure pattern as the upward gradient of the inclination angle increases. According to this, when the vehicle stops on an uphill, the deceleration when the vehicle stops increases as the upward gradient increases, so by increasing the pressure reduction width of the hydraulic pressure pattern and setting the braking force lower, The shock at the time of stop can be relieved enough.

  The parameter detecting means may detect the inclination angle of the vehicle, and the hydraulic pressure pattern correcting means may decrease the pressure reduction width of the hydraulic pressure pattern as the downward gradient of the inclination angle increases. According to this, when the vehicle stops on a downhill, the greater the downward slope, the smaller the deceleration at the time of vehicle stop, so by reducing the pressure reduction width of the hydraulic pattern and setting the braking force higher, The braking distance can be shortened while reducing the shock at the time of stopping.

  The parameter detection means may detect the rotational speed of an engine provided in the vehicle, and the hydraulic pressure pattern correction means may decrease the pressure reduction width of the hydraulic pressure pattern as the engine rotational speed increases. According to this, it is possible to prevent the vehicle from jumping out at the time of high engine rotation by decreasing the pressure reduction width of the hydraulic pressure pattern and increasing the braking force.

  Another aspect of the present invention is a shock reduction method for reducing a shock when the vehicle is stopped. This method detects the vehicle speed, determines that the vehicle is in a state immediately before stopping when the vehicle speed is equal to or lower than a predetermined value, and affects the deceleration of the vehicle when it is determined that the vehicle is in a state immediately before stopping. The hydraulic pressure pattern corresponding to the detected parameter is selected from the hydraulic pressure pattern storing means for detecting a given parameter and storing a plurality of hydraulic pressure patterns for reducing the deceleration immediately before the vehicle stops. The pressure pattern is corrected according to the value of the parameter, and the hydraulic pressure supplied to the wheel braking means for braking the wheel is controlled according to the corrected hydraulic pressure pattern.

  According to the present invention, it is possible to reduce the shock applied to the occupant when the vehicle is stopped.

One embodiment of the present invention relates to a vehicle braking device that reduces deceleration just before stopping in order to reduce a shock when the vehicle stops. This apparatus is characterized in that the target pressure reduction value of the wheel cylinder pressure is corrected using values detected by various sensors mounted on the vehicle.
First, the overall configuration of the vehicle braking apparatus 100 according to the present embodiment will be described, and then a specific configuration according to the present embodiment will be described.

  FIG. 1 shows the overall configuration of the vehicle braking device 100. The vehicle braking device 100 mainly includes an actuator 120, a master cylinder 14 other than the actuator 120, and an electronic control device (hereinafter referred to as “ECU”) 200 that performs overall control of the vehicle braking device 100. The vehicle braking device 100 is an electronically controlled brake system (ECB), which can detect an operation amount of a brake pedal with a stroke sensor, calculate an optimal brake hydraulic pressure, and operate the brakes independently of the four wheels.

  The brake pedal 12 is provided with a stroke sensor 46 for detecting the stroke amount. The master cylinder 14 pumps brake oil, which is hydraulic fluid, in response to the driver's depression of the brake pedal 12.

  One end of a brake hydraulic control conduit 16 for the right front wheel and a brake hydraulic control conduit 18 for the left front wheel are connected to the master cylinder 14, and these brake hydraulic control conduits exhibit the braking force of the right front wheel and the left front wheel, respectively. It is connected to wheel cylinders 20FR and 20FL for the right front wheel and the left front wheel. A right electromagnetic on-off valve 22FR and a left electromagnetic on-off valve 22FL are inserted in the middle of the brake hydraulic control conduits 16, 18 for the right front wheel and the left front wheel. The right electromagnetic on-off valve 22FR and the left electromagnetic on-off valve 22FL are open when not energized, and are switched to a closed state when a brake operation is detected (this is referred to as a “normally open type”).

  A right master pressure sensor 48FR and a left master pressure sensor 48FL for measuring master cylinder pressures on the right front wheel side and the left front wheel side are provided in the middle of the brake hydraulic pressure control conduits 16 and 18, respectively. When the driver depresses the brake pedal 12, the stroke sensor 46 detects the amount of depression, but assuming the failure of the stroke sensor 46, the master cylinder pressure of the right master pressure sensor 48FR and the left master pressure sensor 48FL is controlled. The depressing operation force of the brake pedal 12 is also detected by measurement.

  A reservoir tank 26 is connected to the master cylinder 14, and a stroke simulator 24 that creates an operation amount and reaction force of the driver is connected via an on-off valve 23. The on-off valve 23 is a normally open solenoid valve that is open when de-energized and switches to open when the brake is operated. One end of a hydraulic supply / discharge conduit 28 is connected to the reservoir tank 26. The hydraulic supply / discharge conduit 28 is provided with an oil pump 34 driven by a motor 32. The discharge side of the oil pump 34 is a high-pressure conduit 30, and an accumulator 50 and a relief valve 53 are provided. The accumulator 50 accumulates brake oil that has been brought to a high pressure in the range of 14 to 22 MPa (hereinafter referred to as “control range”) by the oil pump 34. The relief valve 53 opens when the accumulator pressure is abnormally high, for example, 25 MPa, and allows high-pressure brake oil to escape to the hydraulic supply / discharge conduit 28.

  The high pressure conduit 30 is provided with an accumulator pressure sensor 51 that measures the accumulator pressure. The ECU 200 described later receives the accumulator pressure that is the output of the accumulator pressure sensor 51, and controls the motor 32 so that the accumulator pressure falls within the control range.

  Each of the high-pressure conduits 30 is closed when not energized (this is referred to as “normally closed type”). When necessary, the high-pressure conduit 30 is an electromagnetic flow control valve that is used for pressure increase of the wheel cylinder, that is, a linear valve. Via the pressure valves 40FR, 40FL, 40RR, 40RL, the right front wheel wheel cylinder 20FR, the left front wheel wheel cylinder 20FL, the right rear wheel wheel cylinder 20RR, the left rear wheel wheel cylinder 20RL (hereinafter collectively referred to as these (Referred to as “wheel cylinder 20”). Hereinafter, the pressure increasing valves 40FR, 40FL, 40RR, and 40RL are collectively referred to as the pressure increasing valve 40.

  Disc brakes are provided on the right front wheel, left front wheel, right rear wheel, and left rear wheel (not shown) of the vehicle, and are controlled by pressing the brake pads against the disc by driving the wheel cylinders 20FR, 20FL, 20RR, and 20RL, respectively. Demonstrate power.

  The right front wheel cylinder 20FR and the left front wheel cylinder 20FL are hydraulically supplied and discharged via electromagnetic flow control valves used for pressure reduction when necessary, that is, linearly-controlled normally closed pressure reducing valves 42FR and 42FL. Connected to conduit 28. Further, the wheel cylinder 20RR for the right rear wheel and the wheel cylinder 20RL for the left rear wheel are connected to the hydraulic supply / discharge conduit 28 through normally open pressure reducing valves 42RR and 42RL, respectively. Hereinafter, the pressure reducing valves 42FR, 42FL, 42RR, and 42RL are collectively referred to as pressure reducing valves 42.

  Near the right front wheel, left front wheel, right rear wheel, and left rear wheel wheel cylinders 20FR, 20FL, 20RR, 20RL, the right front wheel, the left front wheel, the right rear wheel, Wheel cylinder pressure sensors 44FR, 44FL, 44RR, 44RL for the left rear wheel (hereinafter collectively referred to as “wheel cylinder pressure sensor 44”) are provided.

The ECU 200 controls the electromagnetic open / close valves 22FR and 22FL, the open / close valve 23, the motor 32, the four pressure increasing valves 40FR, 40FL, 40RR, and 40RL, and the four pressure reducing valves 42FR, 42FL, 42RR, and 42RL. The ECU 200 includes an arithmetic unit using a microcomputer, a ROM that stores various control programs, and a RAM that is used as a work area for data storage and program execution.
In addition, various detection values are input to the ECU 200 from various sensors (collectively indicated as “various sensors 80”) mounted on the vehicle, and a wheel cylinder pressure signal is input from the wheel cylinder pressure sensor 44. A signal indicating the stroke amount of the brake pedal 12 (hereinafter referred to as a stroke signal) is transmitted from the stroke sensor 46, and a signal indicating the master cylinder pressure (hereinafter referred to as a master cylinder pressure signal) is transmitted from the right master pressure sensor 48FR and the left master pressure sensor 48FL. The accumulator pressure sensor 51 receives a signal indicating the accumulator pressure.

  The ROM of ECU 200 stores a predetermined braking control flow. The calculation unit calculates the target deceleration of the vehicle based on the stroke signal and the master cylinder pressure signal, calculates the target wheel cylinder pressure of each wheel based on the calculated target deceleration, and the wheel cylinder pressure of each wheel The pressure increasing valve 40 and the pressure reducing valve 42 are controlled so as to be the cylinder pressure.

  The oil pump 34 driven by the motor 32 draws up brake oil from the reservoir tank 26 through the hydraulic supply / discharge conduit 28 and accumulates the brake oil at high pressure in the accumulator 50. The high hydraulic pressure of the accumulator 50 is supplied to each wheel cylinder 20 by controlling opening / closing of the pressure increasing valve 40 according to the target wheel cylinder pressure.

  When high-pressure brake oil is consumed from the accumulator 50 by depressing the brake pedal 12, the ECU 200 operates the motor 32 to drive the oil pump so that the pressure of the accumulator 50 is always within the control range, Accumulator 50 accumulates the brake oil at a high pressure.

  The above is the overall configuration of the vehicle braking device 100. Next, the shock reduction control for reducing the shock when the vehicle is stopped will be described in detail.

FIG. 2 is a functional block diagram for explaining the details of the portion of the ECU 200 involved in the shock reduction control according to the present embodiment and the sensor 80 collectively described in FIG.
Note that each block shown in FIG. 2 can be realized in hardware by an element and a mechanical device such as a computer CPU and memory, and in software by a computer program, etc. It is drawn as a functional block realized by the cooperation. Therefore, those skilled in the art will understand that these functional blocks can be realized in various forms by a combination of hardware and software.

  The vehicle speed sensor 102 is disposed in the vicinity of a vehicle wheel (not shown) and detects the rotational speed of the wheel to estimate the vehicle speed. The acceleration sensor 104 is installed on the vehicle body and detects the acceleration of the vehicle. The steering angle sensor 106 is attached to a steering wheel of a vehicle (not shown) and detects a rotation angle from a neutral position of the steering wheel. The inclination angle sensor 108 is installed on the vehicle body and detects the inclination of the vehicle in the front-rear direction. Instead of providing the tilt angle sensor 108, the tilt angle may be estimated using the output of the acceleration sensor. The engine speed sensor 110 measures the speed per unit time of an engine provided in the vehicle.

  The outputs of the various sensors described above are input to the ECU 200. Further, the wheel cylinder pressure detected by the wheel cylinder pressure sensor 44 described in FIG. 1 and the stroke amount detected by the stroke sensor 46 are also input to the ECU 200.

  A vehicle interior (not shown) may include a control start switch 112 for inputting whether or not the driver executes the shock reduction control according to the present embodiment. Although details will be described later, the braking distance and the brake feeling are changed by the shock reduction control, and therefore it may be preferable not to execute the shock reduction control depending on the preference of the driver or the traveling environment of the vehicle. If the control start switch 112 is on, shock reduction control is executed. If the control start switch 112 is off, shock reduction control is not executed, and normal braking control is executed.

Subsequently, functional blocks of the ECU 200 will be described.
The vehicle stop determination unit 202 determines that the vehicle is in a state immediately before the stop when the vehicle speed detected by the vehicle speed sensor 102 falls below a predetermined value (for example, 5 km / h). Shock reduction control is executed when it is determined that the vehicle is in a state immediately before stopping, and normal braking control is executed at other times. In addition to the vehicle speed, the vehicle stop determination unit 202 refers to the master cylinder pressure obtained from the master pressure sensor 48 and the deceleration obtained from the acceleration sensor 104 shown in FIG. Also good.

  When the vehicle stop determination unit 202 determines that the vehicle is in a state immediately before stopping, the parameter acquisition unit 204 acquires parameters that affect the deceleration of the vehicle from the various sensors described above. In the present embodiment, the steering steering angle, the vehicle inclination angle, and the engine speed are acquired as the parameters, but the present invention is not limited to this.

The hydraulic pressure pattern storage unit 208 stores a plurality of basic hydraulic pressure patterns corresponding to the above-described parameters for reducing the deceleration immediately before the vehicle stops and reducing the shock at the time of stopping. Specifically, the basic hydraulic pressure pattern defines the relationship between the elapsed time from the start of the current braking and the wheel cylinder pressure, and the target wheel cylinder pressure is stored in a table for each elapsed time.
The basic hydraulic pressure pattern selection unit 206 selects a corresponding basic hydraulic pressure pattern from the hydraulic pressure pattern storage unit 208 according to the parameter detected by the parameter acquisition unit 204. The hydraulic pressure pattern correction unit 210 corrects the selected basic hydraulic pressure pattern according to the parameter value. Detailed operations of the basic hydraulic pressure pattern selection unit 206 and the hydraulic pressure pattern correction unit 210 will be described later.

  The hydraulic pressure control unit 212 controls the hydraulic pressure supplied to the wheel cylinder 20 in accordance with the hydraulic pressure pattern corrected by the hydraulic pressure pattern correction unit 210. More specifically, the hydraulic pressure control unit 212 drives the pressure increasing valve 40 or the pressure reducing valve 42 so that the wheel cylinder pressure changes in the same manner as the corrected hydraulic pressure pattern from the time when it is determined that the state is just before stopping. To do. When a predetermined time has elapsed from the start of the control, the control is terminated, and the pressure increasing valve 40 or the pressure reducing valve 42 is driven so as to return the wheel cylinder pressure to the original pressure. In this way, the wheel cylinder pressure is adjusted with the passage of time from the start of braking.

  The normal braking unit 214 executes normal braking control for generating a braking force based on the brake pedal stroke signal and the master cylinder pressure signal when the vehicle stop determination unit 202 determines that the vehicle is not in a state just before stopping. Since this control is a well-known technique, a detailed description thereof will be omitted.

In the present embodiment, selection of the basic hydraulic pressure pattern and correction of the selected pattern are executed as described below.
The hydraulic pressure pattern storage unit 208 includes a normal basic hydraulic pressure pattern, an uphill basic hydraulic pressure pattern to be selected when the vehicle is about to stop on an uphill slope, and an onset on a downhill slope. The basic hydraulic pressure pattern at the time of downward gradient to be selected when the vehicle is in operation and the basic hydraulic pressure pattern at the time of engine high rotation to be selected when the engine speed is high such as when using an air conditioner are stored. Then, the basic hydraulic pressure pattern selection unit 206 acquires parameters of the steering angle, the vehicle inclination angle, and the engine speed, and determines which of the basic hydraulic pressure patterns is selected.

Threshold values are set for each of the steering angle, the tilt angle, and the engine speed, and the basic hydraulic pressure pattern selection unit 206 compares each parameter with each threshold value to determine the state of the vehicle. To do. For example, if the steering angle is in the range of −20 degrees to +20 degrees with respect to the neutral position, it is determined that the vehicle is traveling straight, and if it is any other angle, it is determined that the vehicle is turning. In the case of an inclination angle, it is determined that the slope is flat when it is less than 5 degrees, and when it is 5 degrees or more, it is determined that there is an inclination. Regarding the engine speed, if it is less than 3000 rpm, it is determined as low rotation, and if it is 3000 rpm or more, it is determined as high rotation.
Then, the basic hydraulic pressure pattern selection unit 206 selects the basic hydraulic pressure pattern (FIG. 4) when the inclination is flat and the engine speed is low, and when there is an inclination, the basic hydraulic pressure pattern (when rising) 5) or a basic hydraulic pressure pattern during downward gradient (FIG. 6) is selected, and a basic hydraulic pressure pattern during high engine rotation (FIG. 7) is selected during high engine rotation.
When the engine is inclined and the engine speed is high, a basic hydraulic pressure pattern corresponding to one is selected according to a predetermined priority order. In another embodiment, a basic hydraulic pressure pattern corresponding to a parameter that seems to have a greater effect on deceleration may be selected.

  FIG. 3 shows the relationship between the wheel cylinder pressure and the vehicle speed when the shock reduction control is not executed. In the figure, the horizontal axis represents elapsed time, and the vertical axis represents vehicle speed and wheel cylinder pressure. As shown in FIG. 3, when the wheel cylinder pressure is constant without executing the shock reduction control, the vehicle is stopped with the deceleration being substantially constant. In this case, a shock occurs when the vehicle stops.

4 to 7 show examples of basic hydraulic pressure patterns. 4 shows a normal hydraulic pressure pattern during normal operation, FIG. 5 shows a basic hydraulic pressure pattern during upward gradient, FIG. 6 shows a basic hydraulic pressure pattern during downward gradient, and FIG. 7 shows a basic hydraulic pressure pattern during high engine speed. Show. Each of these basic hydraulic pressure patterns is a pattern in which the wheel cylinder pressure is reduced so that the deceleration immediately before the vehicle stops is reduced and the vehicle is gently stopped.
Note that more basic hydraulic pressure patterns may be prepared according to the type of parameter.

The hydraulic pressure pattern correction unit 210 corrects the basic hydraulic pressure pattern selected by the basic hydraulic pressure pattern selection unit 206 according to specific parameter values.
First, when the steering angle exceeds the range of −20 degrees to +20 degrees, the basic hydraulic pressure pattern is corrected so that the vehicle stops more gently. The wheel on the turning side (the right front wheel if turning right) corrects the hydraulic pressure pattern so that the minimum wheel cylinder pressure increases as the absolute value of the steering angle increases. The wheel on the opposite side of the turn (the left front wheel in the case of a right turn) corrects the hydraulic pressure pattern so that the minimum wheel cylinder pressure decreases as the absolute value of the steering angle increases. When braking is performed during turning of the vehicle, for example, during turning of the right side, more weight is applied to the left front wheel, and as a reaction, a shock on the left side of the vehicle increases. Therefore, the ride comfort is improved by controlling the braking force of the left front wheel to be lower than that of the right front wheel to reduce the left shock.

Since the wheel cylinder pressure required to stop the vehicle decreases during ascending, the minimum wheel cylinder pressure is set lower than the normal basic hydraulic pressure pattern to lower the braking force in the ascending basic hydraulic pressure pattern. I have to. As the upward gradient increases, the hydraulic pressure pattern correction unit 210 corrects the basic hydraulic pressure pattern during the upward gradient so that the minimum wheel cylinder pressure decreases as indicated by an arrow in FIG.
Since the wheel cylinder pressure required to stop the vehicle increases when the vehicle is going downhill, the basic hydraulic pressure pattern during downhill is set higher than the normal basic hydraulic pressure pattern to increase the braking force. I have to. The hydraulic pressure pattern correction unit 210 corrects the basic hydraulic pressure pattern during the downward gradient so that the minimum wheel cylinder pressure becomes higher as indicated by the arrow in FIG. 6 as the downward gradient increases.

  When the engine is running at high speed, if the braking force is reduced too much, the vehicle may start to run vigorously. Therefore, in the basic hydraulic pressure pattern at high engine speed, the minimum wheel cylinder pressure should be set higher than the normal basic hydraulic pressure pattern. The power is increased. The hydraulic pressure pattern correction unit 210 corrects the basic hydraulic pressure pattern at the time of engine high rotation so that the minimum wheel cylinder pressure increases as the engine speed increases, as indicated by an arrow in FIG.

  In the hydraulic pressure pattern storage unit 208, correction values corresponding to the corresponding parameter values are stored in advance as a table for each of the basic hydraulic pressure patterns described above, and the hydraulic pressure pattern correction unit 210 stores the correction values in the hydraulic pressure. You may read from the pattern storage part 208. FIG. Alternatively, a calculation formula for correction may be prepared for each basic hydraulic pressure pattern described above, and the hydraulic pressure pattern correction unit 210 may correct the basic hydraulic pressure pattern using the calculation formula.

  FIG. 8 is a table briefly summarizing the above-described basic hydraulic pressure pattern correction methods. The hydraulic pressure pattern correction unit 210 increases the value of the minimum wheel cylinder pressure of the wheel on the turning side and decreases the value of the minimum wheel cylinder pressure of the wheel on the opposite side of the turning as the absolute value of the steering angle increases. The larger the upward gradient of the tilt angle, the smaller the value of the minimum wheel cylinder pressure. The value of the minimum wheel cylinder pressure is increased as the downward gradient of the inclination angle is increased. As the engine speed increases, the value of the minimum wheel cylinder pressure increases.

FIG. 9 is a flowchart for performing shock reduction control according to the embodiment. This flow is periodically executed at predetermined intervals when the control start switch 112 installed in the vehicle interior is on.
First, the vehicle stop determination unit 202 detects the vehicle speed (S10), and determines whether or not the vehicle is in a state immediately before stop (S12). If the vehicle is not in a state just before stopping (N in S12), this routine is terminated. If it is determined that the vehicle is in a state just before stopping (Y in S12), the parameter acquisition unit 204 acquires each parameter from the sensor (S14). In accordance with the acquired parameters, the basic hydraulic pressure pattern selection unit 206 selects a basic hydraulic pressure pattern from the hydraulic pressure pattern storage unit 208 (S16). Subsequently, the hydraulic pressure pattern correction unit 210 corrects the selected basic hydraulic pressure pattern according to the acquired parameter value (S18).

  The hydraulic pressure control unit 212 receives the corrected hydraulic pressure pattern from the hydraulic pressure pattern correction unit 210 and drives the pressure increasing valve 40 or the pressure reducing valve 42 according to the pattern to control the hydraulic pressure supplied to the wheel cylinder 20. (S20).

The vehicle stop determination unit 202 determines whether or not the driver has not increased the brake pedal after determining that the vehicle is in a state immediately before the stop according to the detection value of the stroke sensor 46 (S22). If the brake pedal is stepped on (Y in S22), it is estimated that the driver intends to shorten the braking distance, so the shock reduction control is stopped (S28), and the braking force according to the stroke amount of the brake pedal. The control authority is delegated to the normal braking unit 214 that adjusts. Further, when the master cylinder pressure fluctuates more than the set value for some reason, the shock reduction control may be stopped and the normal braking control may be executed.
If the brake pedal is not depressed (N in S22), the hydraulic pressure control unit 212 determines whether or not the vehicle has stopped by the vehicle speed sensor 102 (S24). If the vehicle is not stopped (N in S24), the control according to the hydraulic pressure pattern is continued. If the vehicle is stopped (Y in S24), the control according to the hydraulic pressure pattern is terminated and the wheel cylinder pressure is finished. To normal pressure (S26).

As described above, according to the present embodiment, when it is determined that the vehicle is immediately before stopping, the wheel cylinder pressure is controlled according to the hydraulic pressure pattern, so the driver does not need to loosen the brake pedal immediately before stopping. In addition, the shock when the vehicle stops can be reduced regardless of the skill of the driver.
In addition, parameters that affect vehicle deceleration are acquired, and different basic hydraulic pressure patterns are selected according to the vehicle state estimated from the parameters, enabling appropriate shock mitigation according to each situation. Become. For example, since the deceleration when the vehicle stops on an uphill is larger than that on a flat road, if the shock mitigation control is executed with the same hydraulic pressure pattern as the flat road, there is a possibility that the shock cannot be absorbed. Alternatively, since the deceleration when the vehicle stops on a downhill is smaller than that on a flat road, if the shock mitigation control is executed with the same hydraulic pressure pattern as that on a flat road, the braking distance may be longer than expected. There is. In the present embodiment, the basic hydraulic pressure pattern during ascending slope is selected for the uphill, and the basic hydraulic pressure pattern during descending slope is selected for the downhill, so the above situation can be avoided.
Furthermore, in this embodiment, since the shock reduction control is performed using a sensor and a braking system that are installed in a normal vehicle, there is no need to add a new device to the vehicle, and only the ECU program is changed. Applicable.

  The present invention has been described above based on the embodiment. It should be understood by those skilled in the art that these embodiments are exemplifications, and that various modifications can be made to the combination of each component and each processing process, and such modifications are also within the scope of the present invention. Such modifications will be described below.

  When the shock mitigation control described in the embodiment is performed, the braking distance of the vehicle increases. Therefore, it is preferable not to perform shock reduction control during an emergency stop. Therefore, an emergency braking determination unit (not shown) may be further provided, and when the deceleration is larger than a predetermined value, normal braking control may be performed without performing shock reduction control. As a result, the braking distance can be kept short during emergency braking while reducing vehicle shock during normal operation.

  In the embodiment, it has been described that the wheel cylinder pressure is controlled according to the hydraulic pressure pattern regardless of the driver's brake operation. Instead, the stroke sensor 46 detects the amount of brake pedal depression and return by the driver, and when recognizing a reduction in deceleration immediately before the driver stops, the wheel cylinder pressure is controlled to an appropriate pressure to reduce the shock. It may be.

  An ultrasonic sensor may be installed in front of or behind the vehicle, and the shock reduction control may not be executed when an obstacle is detected at a predetermined distance from the vehicle, for example, less than 1 m. This is because, for example, if shock mitigation control is executed when entering the garage, the braking distance may increase and the vehicle may collide with an obstacle. From the same way of thinking, the shock reduction control may not be executed when the vehicle speed at the start of the brake depression is a predetermined value (for example, 10 km / h) or less.

When the temperature of the brake pad is higher than a predetermined value (for example, 100 ° C.), the effectiveness of the brake is reduced. Therefore, the hydraulic pressure pattern correction unit 210 increases the braking force so that the minimum wheel cylinder pressure increases. The correction amount of the basic hydraulic pressure pattern may be adjusted so as to increase. The temperature of the brake pad can be estimated from the detection value of an engine water temperature sensor (not shown).
Further, when it is estimated that the brake pad is wet based on the output of the rain sensor, the effectiveness of the brake is reduced, so that the hydraulic pressure pattern correction unit 210 increases the minimum wheel cylinder pressure, that is, more The correction amount of the basic hydraulic pressure pattern may be adjusted so that the braking force is increased.

It is a figure showing the whole vehicle brake device composition concerning an embodiment. It is a functional block diagram explaining the detail of ECU and a sensor of FIG. It is a figure which shows the relationship between the wheel cylinder pressure when not performing shock reduction control, and a vehicle speed. It is a figure which shows a normal time basic hydraulic pressure pattern. It is a figure which shows a basic hydraulic pressure pattern at the time of an up slope. It is a figure which shows a basic hydraulic pressure pattern at the time of a downward gradient. It is a figure which shows a basic hydraulic pressure pattern at the time of engine high rotation. It is a table | surface which shows the correction method of a basic hydraulic pressure pattern. It is a flowchart which implements the shock reduction control which concerns on embodiment.

Explanation of symbols

  12 brake pedal, 14 master cylinder, 20 wheel cylinder, 40 pressure increasing valve, 42 pressure reducing valve, 44 wheel cylinder pressure sensor, 46 stroke sensor, 50 accumulator, 100 vehicle braking device, 102 vehicle speed sensor, 104 acceleration sensor, 106 steering angle sensor , 108 Inclination angle sensor, 110 Engine speed sensor, 120 Actuator, 200 ECU, 202 Vehicle stop determination unit, 204 Parameter acquisition unit, 206 Basic hydraulic pattern selection unit, 208 Hydraulic pattern storage unit, 210 Hydraulic pattern correction unit 212 hydraulic pressure control unit, 214 normal braking unit.

Claims (9)

A vehicle braking device that reduces shock when the vehicle stops,
Wheel braking means for braking the wheel by the hydraulic pressure supplied in accordance with the operation of the brake operation member;
Vehicle speed detection means for detecting the vehicle speed;
When the vehicle speed is equal to or lower than a predetermined value, stop state determination means for determining that the vehicle is in a state immediately before stop;
Parameter detecting means for detecting a parameter affecting the deceleration of the vehicle when it is determined that the vehicle is in a state immediately before stopping;
Hydraulic pressure pattern storage means for storing a plurality of hydraulic pressure patterns for decreasing the deceleration immediately before the vehicle stops in correspondence with the parameters;
A hydraulic pressure pattern selecting means for selecting a hydraulic pressure pattern corresponding to the parameter detected by the parameter detecting means from the hydraulic pressure pattern storing means;
Hydraulic pressure pattern correcting means for correcting the selected hydraulic pressure pattern according to the value of the parameter;
Hydraulic control means for controlling the hydraulic pressure supplied to the wheel braking means according to the corrected hydraulic pressure pattern;
Equipped with a,
The parameter detecting means detects a steering angle of the vehicle,
The hydraulic pressure pattern correction means decreases the width of the hydraulic pressure pattern on the turning side as the steering angle increases, and increases the pressure reduction width of the hydraulic pressure pattern on the opposite side of the turning. apparatus. A vehicle braking device that reduces shock when the vehicle stops,
Wheel braking means for braking the wheel by the hydraulic pressure supplied in accordance with the operation of the brake operation member;
Vehicle speed detection means for detecting the vehicle speed;
When the vehicle speed is equal to or lower than a predetermined value, stop state determination means for determining that the vehicle is in a state immediately before stop;
Parameter detecting means for detecting a parameter affecting the deceleration of the vehicle when it is determined that the vehicle is in a state immediately before stopping;
Hydraulic pressure pattern storage means for storing a plurality of hydraulic pressure patterns for decreasing the deceleration immediately before the vehicle stops in correspondence with the parameters;
A hydraulic pressure pattern selecting means for selecting a hydraulic pressure pattern corresponding to the parameter detected by the parameter detecting means from the hydraulic pressure pattern storing means;
Hydraulic pressure pattern correcting means for correcting the selected hydraulic pressure pattern according to the value of the parameter;
Hydraulic control means for controlling the hydraulic pressure supplied to the wheel braking means according to the corrected hydraulic pressure pattern;
With
The parameter detecting means detects a tilt angle of the vehicle,
The vehicle brake device according to claim 1, wherein the hydraulic pressure pattern correction means increases the pressure reduction width of the hydraulic pressure pattern as the upward gradient of the inclination angle increases. A vehicle braking device that reduces shock when the vehicle stops,
Wheel braking means for braking the wheel by the hydraulic pressure supplied in accordance with the operation of the brake operation member;
Vehicle speed detection means for detecting the vehicle speed;
When the vehicle speed is equal to or lower than a predetermined value, stop state determination means for determining that the vehicle is in a state immediately before stop;
Parameter detecting means for detecting a parameter affecting the deceleration of the vehicle when it is determined that the vehicle is in a state immediately before stopping;
Hydraulic pressure pattern storage means for storing a plurality of hydraulic pressure patterns for decreasing the deceleration immediately before the vehicle stops in correspondence with the parameters;
A hydraulic pressure pattern selecting means for selecting a hydraulic pressure pattern corresponding to the parameter detected by the parameter detecting means from the hydraulic pressure pattern storing means;
Hydraulic pressure pattern correcting means for correcting the selected hydraulic pressure pattern according to the value of the parameter;
Hydraulic control means for controlling the hydraulic pressure supplied to the wheel braking means according to the corrected hydraulic pressure pattern;
With
The parameter detecting means detects a tilt angle of the vehicle,
The vehicle brake device according to claim 1, wherein the hydraulic pressure pattern correction means decreases the pressure reduction width of the hydraulic pressure pattern as the downward slope of the inclination angle increases. A shock reduction method for reducing shock when the vehicle is stopped,
Detect vehicle speed,
When the vehicle speed falls below a predetermined value, it is determined that the vehicle is in a state just before stopping,
When it is determined that the vehicle is in a state just before stopping, the steering steering angle of the vehicle is detected as a parameter that affects the deceleration of the vehicle ,
Select a hydraulic pressure pattern corresponding to the detected steering angle from hydraulic pressure pattern storage means for storing a plurality of hydraulic pressure patterns for reducing the deceleration immediately before the vehicle stops,
The higher the steering angle is large, so that a slight proportion pressure reducing width of the hydraulic pattern of the turning side to increase the pressure decrease in the hydraulic pattern of turning opposite to correct the hydraulic pressure pattern that is selected,
A shock reduction method comprising: controlling a hydraulic pressure supplied to a wheel braking means for braking a wheel according to a corrected hydraulic pressure pattern. A shock reduction method for reducing shock when the vehicle is stopped,
Detect vehicle speed,
When the vehicle speed falls below a predetermined value, it is determined that the vehicle is in a state just before stopping,
When it is determined that the vehicle is in a state just before stopping, the vehicle tilt angle is detected as a parameter that affects the deceleration of the vehicle,
From the hydraulic pressure pattern storage means for storing a plurality of hydraulic pressure patterns for reducing the deceleration immediately before the vehicle stops, the hydraulic pressure pattern corresponding to the detected parameter is selected,
Correct the selected hydraulic pressure pattern to increase the pressure reduction width of the hydraulic pressure pattern as the upward slope of the inclination angle increases,
A shock reduction method comprising: controlling a hydraulic pressure supplied to a wheel braking means for braking a wheel according to a corrected hydraulic pressure pattern. A shock reduction method for reducing shock when the vehicle is stopped,
Detect vehicle speed,
When the vehicle speed falls below a predetermined value, it is determined that the vehicle is in a state just before stopping,
When it is determined that the vehicle is in a state just before stopping, the vehicle tilt angle is detected as a parameter that affects the deceleration of the vehicle,
From the hydraulic pressure pattern storage means for storing a plurality of hydraulic pressure patterns for reducing the deceleration immediately before the vehicle stops, the hydraulic pressure pattern corresponding to the detected parameter is selected,
Correct the selected hydraulic pressure pattern so that the downward slope of the hydraulic pressure pattern decreases as the downward slope of the inclination angle increases,
A shock mitigation method comprising: controlling a hydraulic pressure supplied to a wheel braking means for braking a wheel according to a corrected hydraulic pressure pattern. A braking control device that reduces shock when the vehicle stops,
A stop state determination unit that determines that the vehicle is in a state immediately before stop when the vehicle speed is equal to or less than a predetermined value;
A parameter detection unit that detects a parameter that affects the deceleration of the vehicle when it is determined that the vehicle is in a state immediately before stopping;
A hydraulic pressure pattern storage unit for storing a plurality of hydraulic pressure patterns for reducing the deceleration immediately before the vehicle stops in correspondence with the parameters;
A hydraulic pressure pattern selection unit that selects a hydraulic pressure pattern corresponding to the parameter detected by the parameter detection unit from the hydraulic pressure pattern storage unit;
A hydraulic pressure pattern correction unit that corrects the selected hydraulic pressure pattern according to the value of the parameter;
Hydraulic pressure control means for controlling the hydraulic pressure supplied to the wheel braking means for braking the wheel according to the corrected hydraulic pressure pattern;
Equipped with a,
The parameter detection unit detects a steering angle of the vehicle,
Said hydraulic pattern correction unit, the higher the steering angle is large, a slight proportion pressure reducing width of the hydraulic pattern of the orbiting side, the brake control, characterized in that to increase the pressure decrease in the hydraulic pattern of turning opposite apparatus. A braking control device that reduces shock when the vehicle is stopped,
A stop state determination unit that determines that the vehicle is in a state immediately before stop when the vehicle speed is equal to or less than a predetermined value;
A parameter detection unit that detects a parameter that affects the deceleration of the vehicle when it is determined that the vehicle is in a state immediately before stopping;
A hydraulic pressure pattern storage unit for storing a plurality of hydraulic pressure patterns for reducing the deceleration immediately before the vehicle stops in correspondence with the parameters;
A hydraulic pressure pattern selection unit that selects a hydraulic pressure pattern corresponding to the parameter detected by the parameter detection unit from the hydraulic pressure pattern storage unit;
A hydraulic pressure pattern correction unit for correcting the selected hydraulic pressure pattern according to the value of the parameter;
Hydraulic pressure control means for controlling the hydraulic pressure supplied to the wheel braking means for braking the wheel according to the corrected hydraulic pressure pattern;
With
The parameter detection unit detects the inclination angle of the vehicle,
The braking control device according to claim 1, wherein the hydraulic pressure pattern correction unit increases the pressure reduction width of the hydraulic pressure pattern as the upward gradient of the inclination angle increases. A braking control device that reduces shock when the vehicle is stopped,
A stop state determination unit that determines that the vehicle is in a state immediately before stop when the vehicle speed is equal to or less than a predetermined value;
A parameter detection unit that detects a parameter that affects the deceleration of the vehicle when it is determined that the vehicle is in a state immediately before stopping;
A hydraulic pressure pattern storage unit for storing a plurality of hydraulic pressure patterns for reducing the deceleration immediately before the vehicle stops in correspondence with the parameters;
A hydraulic pressure pattern selection unit that selects a hydraulic pressure pattern corresponding to the parameter detected by the parameter detection unit from the hydraulic pressure pattern storage unit;
A hydraulic pressure pattern correction unit for correcting the selected hydraulic pressure pattern according to the value of the parameter;
Hydraulic pressure control means for controlling the hydraulic pressure supplied to the wheel braking means for braking the wheel according to the corrected hydraulic pressure pattern;
With
The parameter detection unit detects the inclination angle of the vehicle,
The braking control device according to claim 1, wherein the hydraulic pressure pattern correction unit decreases the pressure reduction width of the hydraulic pressure pattern as the downward slope of the inclination angle increases.

Images