JP2007153052A - Brake controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brake controller capable of generating a proper braking force at each wheel even in case different diameter wheels are mounted on one vehicle. <P>SOLUTION: The brake controller includes a wheel speed information acquisition part 202 which acquires the wheel speed information value when each wheel is out of braking and also a wheel diameter difference judging part 203 which determines existence or none of any wheel diameter difference by means of comparing the wheel speed information values of the wheels. If there is a difference, i.e. different diameter wheels are mounted on the vehicle, a braking amount correction part 204 calculates a correction factor for the applicable different diameter wheel on the basis of its wheel speed information value and corrects the target braking amount. This permits suppressing the change in the braking amount originating from the wheel diameter difference. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a brake control device, and more particularly to an improvement in brake control in a case where wheels having different diameters exist in wheels mounted on a vehicle.

  In recent years, an increasing number of vehicles are equipped with an anti-lock brake device (ABS braking device) that prevents a wheel from locking against a road surface during a brake operation. The ABS braking device determines the tendency of the wheels to lock based on the rotational speed of each wheel, and controls the brake fluid pressure of the wheel cylinder of each wheel. In such an ABS control device, the rotational speed of the wheel is detected independently for each wheel. The vehicle speed used for the ABS control is a pseudo vehicle speed calculated based on the wheel rotation speed detected for each wheel.

By the way, if the diameter (diameter) of the wheel with which the vehicle is mounted | worn differs, the detected rotational speed will change. For example, an emergency wheel may be temporarily mounted when the wheel is punctured. In general, the emergency wheel has a smaller diameter than the regular wheel, so that the rotational speed of the emergency wheel is faster by that wheel, and the calculated pseudo vehicle speed becomes faster than the actual vehicle speed. As a result, the speed of the wheels other than the emergency wheel becomes smaller than the pseudo vehicle body speed, and the ABS control is sensitively performed. That is, the accuracy of ABS control is reduced. Therefore, there is a technique for correcting the diameter difference for each wheel based on the rotation speed of each wheel, determining the wheel speed for control used for the ABS control, and preventing the ABS control from being performed excessively (for example, Patent Document 1).
JP-A-8-156768

  In the above technique, it is possible to suppress the reaction of ABS excessively. However, when the same brake fluid pressure is applied, the braking force generated between the wheel and the road surface increases as the wheel diameter decreases. For example, when a braking force is generated at each wheel in response to a driver's braking request, the braking force of the emergency wheel is greater than that of the regular wheel. As a result, the braking balance of the vehicle may be shifted during braking. Also, the ABS control is executed only with the emergency wheel first. As a result, a difference between the driver's braking sensation and actual braking may occur, causing the driver to feel uncomfortable. A similar phenomenon occurs when a wheel with a different diameter is mounted during wheel replacement.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a brake control device capable of generating an appropriate braking force at each wheel even when wheels having different diameters are present on wheels mounted on the vehicle. It is to provide.

  In order to solve the above problems, a brake control device according to an aspect of the present invention includes a target braking amount acquisition unit that acquires a target braking amount of each wheel based on a braking request, and the braking amount at each wheel is set to the target braking amount. Braking control means for controlling the wheel, wheel speed information acquisition means for acquiring the wheel speed information value at the time of non-braking of each wheel, and other wheels based on the wheel speed information value acquired at each wheel. Wheel diameter difference determining means for determining a wheel having a wheel diameter difference, and a braking amount correction for correcting the target braking amount based on the wheel speed information value so as to suppress a change in the braking amount due to the wheel diameter difference. Means.

  Here, the wheel speed information acquisition means can process any information that is substantially related to the wheel speed. For example, the information obtained by converting the acquired signal into the wheel speed may be used as the wheel speed information value. Alternatively, raw data such as the number of input pulses within a predetermined time may be used as the wheel speed information value. Further, in the present specification, the wheel diameter difference is assumed to be a wheel diameter difference when there is a difference of a predetermined value or more when, for example, the diameters of two wheels are compared. That is, even if there is a difference in diameter in reality, if the difference is smaller than a predetermined value, no difference in wheel diameter is assumed. For example, the situation where the wheel diameter difference occurs may be caused by an emergency wheel temporarily installed at the time of puncture, or when a large wheel or a small wheel is mounted incorrectly when replacing some wheels. Includes the case where the wheel diameter is changed due to a change in tire air pressure. According to this aspect, the wheel diameter difference is determined based on each wheel speed information value, and the target braking amount is corrected using the wheel speed information value according to the wheel diameter difference. As a result, even if the wheels mounted on the vehicle include those with a wheel diameter difference, the braking amount generated at each wheel is set to a desired value by suppressing the change in the braking amount based on the wheel diameter difference. For example, it is possible to obtain the same braking state as in a case where wheels of different diameters are not included.

  Further, in the above aspect, the wheel diameter difference determining means compares each wheel speed information value with each other, and if there is a wheel speed information value greater than a predetermined value than other wheel speed information values, the wheel speed information value May be determined to be a small-diameter wheel in comparison with a wheel having another wheel speed information value. When a wheel having a smaller diameter than a regular wheel is mounted, only the small diameter wheel has a wheel speed information value larger than that of the other wheels. That is, when there is a wheel from which a wheel speed information value equal to or greater than a predetermined value is obtained with respect to another wheel speed information value, it can be determined that the wheel is a small-diameter wheel.

  Further, in the above aspect, when the wheel diameter difference determining means has a difference of a predetermined value or more between the maximum value of the wheel speed information value and the quasi-maximum value next to the maximum value, the wheel speed information value is maximum. The wheel which is a value may be determined to be a small-diameter wheel by comparing with other wheels. Here, the quasi-maximum value indicates the second wheel speed information value that is the second largest among all wheels. For example, when an emergency wheel is mounted due to puncture or the like, only one small-diameter wheel is mounted. In this case, only the small-diameter wheel has a larger wheel speed information value than the other wheels. The other wheels have substantially the same wheel speed information value. That is, when there is a difference of a predetermined value or more between the maximum wheel speed information value and the semi-maximum value, it can be determined that the wheel with the maximum value is a small-diameter wheel.

  In the above aspect, the wheel diameter difference determining means compares each wheel speed information value with each other, and if a wheel speed information value smaller than a predetermined value by other wheel speed information values exists, the wheel speed information value. May be determined to be a large-diameter wheel in comparison with a wheel having another wheel speed information value. When a wheel having a larger diameter than a regular wheel is mounted, only the large diameter wheel has a smaller wheel speed information value than the other wheels. That is, when there is a wheel from which a wheel speed information value equal to or less than a predetermined value is obtained with respect to another wheel speed information value, it can be determined that the wheel is a large-diameter wheel.

  Further, in the above aspect, the wheel diameter difference determining means has a minimum wheel speed information value when there is a difference of a predetermined value or more between a minimum value of the wheel speed information value and a quasi-minimum value next to the minimum value. You may determine with the wheel which is a value being a large-diameter wheel by comparing with another wheel. Here, the quasi-minimum value indicates a wheel speed information value that is the second smallest among all wheels. For example, when only one wheel having a larger diameter than the other wheels is mounted due to a mistake during wheel replacement, only the large-diameter wheel has a smaller wheel speed information value than the other wheels. The other wheels have substantially the same wheel speed information value. That is, when there is a difference of a predetermined value or more between the smallest wheel speed information value and the quasi-minimum value, it can be determined that the smallest wheel is a large-diameter wheel.

  In the above aspect, when one small-diameter wheel is present, the braking amount correction unit corrects the determined target braking amount of the small-diameter wheel by determining the ratio between the maximum value of the wheel speed information value and the quasi-maximum value. It is good also as a correction coefficient for doing. According to this aspect, it is possible to suppress a change in the braking amount due to the mounting of the small-diameter wheel.

  In the above aspect, when there is one large-diameter wheel, the braking amount correcting means determines the ratio of the minimum value of the wheel speed information value and the quasi-minimum value to determine the target braking amount of the large-diameter wheel. It is good also as a correction coefficient for correcting. According to this aspect, it is possible to suppress a change in the braking amount due to the mounting of the large-diameter wheel.

  In order to solve the above problems, a brake control device according to another aspect of the present invention includes a target braking amount acquisition unit that acquires a target braking amount of each wheel based on a required braking request, and a braking amount at each wheel. Braking control means for controlling the vehicle to become the target braking amount, wheel speed information acquisition means for acquiring wheel speed information values when each wheel is not braked, an average value of the wheel speed information values, and Braking amount correction means for correcting the target braking amount so as to suppress a change in the braking amount due to a wheel diameter difference of each wheel using a ratio with the wheel speed information value as a correction coefficient. . According to this aspect, even when a plurality of, for example, two or more small-diameter wheels or two or more large-diameter wheels are included, the braking amount generated at each wheel is suppressed by suppressing the change in the braking amount due to the mounting of the different-diameter wheels. It can be set to a desired value.

  According to the brake control device of the present invention, even when the wheels mounted on the vehicle include wheels with different diameters, it is possible to prevent a difference in braking amount generated between the wheels.

  Hereinafter, an embodiment of the present invention (hereinafter referred to as an embodiment) will be described with reference to the drawings.

  The brake control apparatus of this embodiment acquires the wheel speed information value at the time of non-braking of each wheel, and determines the presence or absence of a wheel diameter difference by comparing the wheel speed information value of each wheel. When there is a difference in wheel diameters, that is, when wheels with different diameters are included in the vehicle-mounted wheels, the target braking amount of the different diameter wheels is corrected using a correction value based on the wheel speed information value. As a result, a change in braking amount due to the wheel diameter difference is suppressed.

  FIG. 1 is an explanatory diagram illustrating the overall configuration of a brake control device 100 according to the present embodiment and an electronic control unit 200 (hereinafter referred to as “ECU 200”) included therein.

  The brake control device 100 mainly includes an actuator 80 and a master cylinder 14 other than the actuator 80. The brake control device 100 is an ECB system (Electronically Controlled Brake System), and can detect the operation amount of the brake pedal with a sensor, calculate the optimum brake hydraulic pressure, and operate the brakes independently of the four wheels.

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

  One end of a brake hydraulic control conduit 16 for the right front wheel (FR) and one of the brake hydraulic pressure control conduit 18 for the left front wheel (FL) are connected to the master cylinder 14, and these brake hydraulic control conduits 16, 18 are respectively connected to the right front wheel. The right front wheel and the left front wheel wheel cylinders 20FR and 20FL are connected to the left front wheel and exhibit the braking force of the left front wheel. A right master cut valve 22FR and a left master cut 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 master cut valve 22FR and the left master cut 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 the master cylinder fluid pressure 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 brake pedal 12 is depressed by the driver, the stroke sensor 46 detects the amount of depression, but the master cylinder fluid by the right master pressure sensor 48FR and the left master pressure sensor 48FL is assumed on the assumption that the stroke sensor 46 has failed. The depressing operation force of the brake pedal 12 is also detected by measuring the pressure. The master cylinder hydraulic pressure is monitored by two pressure sensors from the viewpoint of fail-safe.

  A reservoir tank 26 is connected to the master cylinder 14, and a stroke simulator 24 that creates a driver's operation amount and reaction force is connected via a simulator cut valve 23. The simulator cut valve 23 is a normally closed electromagnetic valve that is in a closed state when not energized and switches to an open state when a 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, for example, 14 to 22 MPa by the oil pump 34. The relief valve 53 opens when the accumulator pressure is abnormally high, such as 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. Although not shown, the accumulator pressure that is the output of the accumulator pressure sensor 51 is input to the ECU 200, and the motor 32 is controlled so that the accumulator pressure falls within the control range.

  The high-pressure conduits 30 are closed when not energized, and are normally closed electromagnetic flow rate control valves used for pressure increase of the wheel cylinder when necessary, that is, pressure increase valves 40FR, 40FL, 40RR which are linear valves. , 40RL, right front wheel wheel cylinder 20FR, left front wheel wheel cylinder 20FL, right rear wheel wheel cylinder 20RR, left rear wheel wheel cylinder 20RL (hereinafter collectively referred to as "wheel cylinder 20"). )It is connected to the. Hereinafter, the reference numeral 40 is used to collectively refer to the pressure increasing valves 40FR, 40FL, 40RR, and 40RL.

  Disc brakes are provided on the right front wheel, left front wheel, right rear wheel, and left rear wheel of the vehicle, and the braking force is applied by pressing the brake pads against the disc by driving the wheel cylinders 20FR, 20FL, 20RR, and 20RL, respectively. It comes to show.

  The right front wheel wheel cylinder 20FR and the left front wheel wheel cylinder 20FL are hydraulically fed and discharged through normally closed pressure reducing valves 42FR and 42FL which are electromagnetic flow control valves used for pressure reduction when necessary, that is, linear valves. 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, when the pressure reducing valves 42FR, 42FL, 42RR, and 42RL are collectively referred to, reference numeral 42 is used.

  Near the right front wheel, left front wheel, right rear wheel, and left rear wheel wheel cylinders 20FR, 20FL, 20RR, and 20RL, the right front wheel, the left front wheel, the right rear wheel, Pressure sensors 44FR, 44FL, 44RR, 44RL for the left rear wheel are provided.

  Near the right front wheel, left front wheel, right rear wheel, left rear wheel axles 21FR, 21FL, 21RL, 21RR (hereinafter collectively referred to as "axle 21"), wheel speed information values of wheels, for example, wheels Wheel speed sensors 49FR, 49FL, 49RL, 49RR (hereinafter collectively referred to as “wheel speed sensor 49”) functioning as wheel speed information acquisition means for acquiring the speed are arranged.

  The ECU 200 controls the master cut valves 22FR and 22FL, the simulator cut 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.

  Although not shown in detail, the ECU 200 receives pressures in the right front wheel wheel cylinder 20FR from pressure sensors 44FR, 44FL, 44RR, 44RL for the right front wheel, the left front wheel, the right rear wheel, and the left rear wheel, respectively. A signal, a pressure signal in the left front wheel wheel cylinder 20FL, a pressure signal in the right rear wheel wheel cylinder 20RR, and a pressure signal in the left rear wheel wheel cylinder 20RL are input. Further, the ECU 200 receives a signal indicating the depression stroke of the brake pedal 12 from the stroke sensor 46, and a signal indicating the master cylinder hydraulic pressure from the right master pressure sensor 48 FR and the left master pressure sensor 48 FL from the accumulator pressure sensor 51. A signal indicating the accumulator pressure is input. Furthermore, signals indicating wheel speeds from the wheel speed sensors 49FR, 49FL, 49RL, 49RR are input. In addition, signals from the acceleration sensor 81, the yaw rate sensor 82, and the steering sensor 83 are also input to the ECU 200.

  The ROM of ECU 200 stores a predetermined braking control flow. A target braking amount acquisition unit (see FIG. 2) in the ECU 200 calculates a target braking amount of the vehicle based on the stroke signal and the master cylinder hydraulic pressure signal. Then, the braking control unit calculates the target wheel cylinder hydraulic pressure of each wheel based on the calculated target braking amount, and the pressure increasing valve 40 and the pressure reduction valve so that the wheel cylinder hydraulic pressure of each wheel becomes the target wheel cylinder hydraulic pressure. The valve 42 is controlled.

  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 opening / closing the pressure increasing valve 40 in accordance with the target wheel cylinder hydraulic 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. This operation is called “pressure accumulation operation”. This pressure accumulation operation is automatically executed according to the detection value of the accumulator pressure sensor 51.

  FIG. 2 is a block diagram illustrating the configuration of the ECU 200. The ECU 200 includes a target braking amount acquisition unit 201, a wheel speed information acquisition unit 202, a wheel diameter difference determination unit 203, a braking amount correction unit 204, and a braking control unit 205. The target braking amount acquisition unit 201 acquires the target braking amount of each wheel based on the braking request requested by the driver based on the signals from the stroke sensor 46 and the master pressure sensor 48. The wheel speed information acquisition unit 202 acquires a wheel speed information value for each current wheel based on a signal input from a wheel speed sensor 49 disposed on each wheel. The wheel speed information acquisition unit 202 may acquire the number of input pulses within a predetermined time input from the wheel speed sensor 49 as information indicating the wheel speed, or based on the input pulse number, You may acquire what was converted.

  The wheel diameter difference determining unit 203 is based on signals input from the acceleration sensor 81, the yaw rate sensor 82, the steering sensor 83, and the like, and the vehicle is currently running substantially straight, and is not accelerated or decelerated. It is possible to determine whether or not the vehicle is running. When determining whether or not the vehicle is currently traveling straight at a constant speed, it may be performed using a signal from another sensor or a result used in another control. When the vehicle is traveling substantially straight at a constant speed, the wheel diameter difference determination unit 203 compares the wheel speed information values of the wheels provided from the wheel speed information acquisition unit 202 with each other, and It detects whether or not there is a wheel diameter difference. As a situation where the wheel diameter difference occurs, for example, a case in which an emergency wheel is temporarily mounted due to puncture or the like can be considered. Emergency wheels are often smaller in diameter than commonly used wheels. In addition, there may be a case where a small-diameter wheel or a large-diameter wheel is mistakenly attached to a part when a new wheel is attached. Further, although a large wheel diameter difference does not occur, a wheel diameter difference may also occur when the tire air pressure has changed from the recommended value.

  For example, when a wheel having a smaller diameter than a wheel having a regular wheel diameter is mounted, the wheel speed of the small diameter wheel is higher than that of the regular wheel. Conversely, in the case of a wheel having a larger diameter than a wheel having a regular wheel diameter, the wheel speed of this large diameter wheel is slower than that of the regular wheel. The wheel diameter difference determination unit 203 compares the wheel speed information values input from the wheel speed sensors 49 with each other. And when there exists a wheel speed information value larger than a predetermined value, for example, 5% or more with respect to other values, it can be determined that the wheel having the wheel speed information value is a small-diameter wheel. Similarly, the wheel diameter difference determination unit 203 compares the wheel speed information values input from the wheel speed sensors 49 with each other, and a wheel speed information value smaller than a predetermined value, for example, 5% or more smaller than other values. When it exists, it can determine with the wheel which has the wheel speed information value being a large diameter wheel.

In addition, about the mounting | wearing of a different diameter wheel, the case where only one wheel of different diameter wheels is mounted | worn and the case where two or more wheels are mounted | worn are considered. First, a case where only one wheel has a different diameter will be described. When the wheel diameter difference determination unit 203 acquires the wheel speed information value from the wheel speed information acquisition unit 202, only one of the four wheels is faster than the other three wheels, or only one wheel is the other three wheels. It is judged whether it is late or not. When the wheel diameter difference determining unit 203 determines that there is only one fast wheel, the wheel diameter difference determining unit 203 determines whether there is a wheel diameter difference using the following Equation 1.
(Vmax−Vmedh) / Vmedh ≧ δ (> 0) (Formula 1)
Here, Vmax is a maximum value among wheel speed information values of each wheel, and Vmedh is a quasi-maximum value among wheel speed information values of each wheel, that is, the second largest wheel speed information value. Further, δ is a threshold for determining different diameter wheels, and is, for example, 0.05. If (Equation 1) holds, it can be determined that the wheel having the wheel speed information value Vmax is a small-diameter wheel. In addition, when the wheel speed information value of each wheel is mutually compared and there exists a thing exceeding a threshold value among the differences, you may determine that a wheel speed information value becomes the small diameter wheel.

When the wheel diameter difference determining unit 203 determines that there is one small-diameter wheel among the four wheels, the brake amount correcting unit 204 sets the target brake amount so as to suppress the change in the brake amount due to the wheel diameter difference. A correction coefficient K to be corrected is calculated. The correction coefficient K can be calculated by the following equation 2.
K = Vmedh / Vmax (Formula 2)
When the small-diameter wheel is one wheel, the other three wheels have substantially the same wheel speed information value. Therefore, instead of Vmedh, the average of the wheel speed information values of the other three wheels other than Vmax is used. Also good.

  The braking control unit 205 adjusts the target braking amount requested by the driver acquired by the target braking amount acquisition unit 201 by ABS control, stable control that stabilizes the behavior of the vehicle, traction control, and the like, so that a predetermined braking force hydraulic pressure is obtained. The target hydraulic pressure of each wheel is adjusted using the conversion factor. Further, when the correction coefficient K based on the wheel diameter difference is calculated in the braking amount correction unit 204, the target hydraulic pressure of the wheel determined as the small-diameter wheel is corrected using the correction coefficient K. When the target hydraulic pressure of each wheel is determined, the braking control unit 205 controls the master cut valve 22 and the simulator cut valve 23 to a predetermined state, and controls the pressure increasing valve 40 and the pressure reducing valve 42 to take into account the wheel diameter difference. The braking amount of each wheel is controlled by hydraulic pressure.

When the wheel diameter difference determining unit 203 determines that there is only one slow wheel, the wheel diameter difference determining unit 203 checks whether or not the following Expression 3 is satisfied.
(Vmedl−Vmin) / Vmedh ≧ δ (> 0) (Equation 3)
Here, Vmin is the smallest of the wheel speed information values of each wheel, and Vmedh is the second smallest wheel speed information value of the wheel speed information values of each wheel. Further, δ is a threshold for determining different diameter wheels, and is, for example, 0.05. If (Equation 3) holds, it can be determined that the wheel having the wheel speed information value Vmin is a large-diameter wheel. In this case as well, the wheel speed information values of the wheels are compared with each other, and if there is a difference that exceeds the threshold value, the wheel speed information value that is the smallest is determined to be a large-diameter wheel. Also good.

When the wheel diameter difference determining unit 203 determines that one large-diameter wheel is present among the four wheels, the braking amount correcting unit 204 sets the target braking amount so as to suppress a change in the braking amount due to the wheel diameter difference. A correction coefficient K for correcting is calculated. The correction coefficient K can be calculated by the following equation 4.
K = Vmedh / Vmin (Formula 4)
When the large-diameter wheel is one wheel, the other three wheels have substantially the same wheel speed information value, so the average of the wheel speed information values of the other three wheels other than Vmin is used instead of Vmedh. May be.

  In the same manner as when the small-diameter wheel is determined to be mounted, the braking control unit 205 performs the ABS control or the stable control or the traction control that stabilizes the behavior of the vehicle using the target braking amount requested by the driver acquired by the target braking amount acquisition unit 201. The target hydraulic pressure of each wheel is adjusted using a predetermined braking force hydraulic pressure conversion coefficient. Further, when the correction coefficient K based on the wheel diameter difference is calculated in the braking amount correction unit 204, the target hydraulic pressure of the wheel determined to be a large-diameter wheel is corrected using the correction coefficient K. When the target hydraulic pressure of each wheel is determined, the braking control unit 205 controls the right master cut valve 22FR, the left master cut valve 22FL, and the simulator cut valve 23 to predetermined states, and controls the pressure increasing valve 40 and the pressure reducing valve 42. The braking amount of each wheel is controlled by hydraulic pressure considering the wheel diameter difference.

  FIG. 3 is a main flowchart for explaining the procedure of hydraulic control performed by the ECU 200. The ECU 200 acquires signals from the sensors at predetermined intervals when the vehicle is driven. For example, the target braking amount acquisition unit 201 acquires signals from the stroke sensor 46 and the master pressure sensor 48. The wheel speed information acquisition unit 202 acquires a signal from each wheel speed sensor 49. The wheel diameter difference determination unit 203 acquires signals from the acceleration sensor 81, the yaw rate sensor 82, the steering sensor 83, and the like. The braking control unit 205 acquires signals from the pressure sensor 44 for each wheel, the master pressure sensor 48, the accumulator pressure sensor 51, and the like (S100). The target braking amount acquisition unit 201 calculates the target braking amount requested by the driver using the stroke sensor 46 and the master pressure sensor 48 (S101). At this time, the braking control unit 205 adjusts the target braking amount requested by the driver acquired by the target braking amount acquisition unit 201 by ABS control, stable control for stabilizing the behavior of the vehicle, traction control, etc. The target hydraulic pressure Prefxx (xx = FR, FL, RR, RL) of each wheel is calculated using the braking force hydraulic pressure conversion coefficient (S102). Subsequently, the wheel diameter difference determining unit 203 determines whether there is a wheel diameter difference between the wheels based on the wheel speed information value acquired by the wheel speed information acquiring unit 202 (S103). When the wheel diameter difference determining unit 203 determines that there is no wheel diameter difference (N in S103), the oil pressure control is performed by controlling the pressure increasing valve 40 and the pressure reducing valve 42 of each wheel so that the target oil pressure calculated in S102 is obtained. (S106), the process returns to S100 to prepare for the next timing control.

  On the other hand, when the wheel diameter difference determination unit 203 determines that there is a wheel diameter difference in S103 (Y in S103), the braking amount correction unit 204 determines whether there is a small-diameter wheel or a large-diameter wheel. The correction coefficient K is calculated by the above-described (Expression 2) or (Expression 4) (S104). Then, the braking control unit 205 corrects the target hydraulic pressure of the different-diameter wheel based on the target hydraulic pressure Prefxx calculated in S102, the different-diameter wheel determined in S103, and the correction coefficient K calculated in S104 (S105).

  FIG. 4 shows details of the processing in S105 of FIG. The braking control unit 205 determines whether or not the right front wheel (FR) has been determined to have a different diameter (S200). If the right front wheel has been determined to have a different diameter (Y in S200), FIG. PrefFR is corrected by multiplying the target hydraulic pressure PrefFR calculated in S102 by the correction coefficient K (S201). Further, when it is determined in S200 that the right front wheel is not different in diameter (N in S200), the process in S201 is skipped. Subsequently, it is determined whether or not the left front wheel (FL) is determined to have a different diameter (S202). If the left front wheel is determined to have a different diameter (Y in S202), the calculation is performed in S102 of FIG. The corrected target oil pressure PrefFL is multiplied by a correction coefficient K to correct PrefFL (S203). If it is determined in S202 that the right front wheel is not different in diameter (N in S202), the process in S203 is skipped. Similarly, the process for the right rear wheel (RR) (S204, S205) and the process for the left rear wheel (RL) (S206, S207) are performed.

  When the processing in S105 is completed, the pressure increase valve 40 and the pressure reduction valve 42 of each wheel are controlled so that the target hydraulic pressure calculated in S102 and the target hydraulic pressure corrected in S105 are obtained, and the change in the braking amount due to the wheel diameter difference is controlled. Hydraulic control is performed so as to suppress (S106). Then, it returns to S100 and prepares for control of the next timing.

  Thus, according to this embodiment, even when the emergency wheel is mounted, it is possible to suppress the difference in braking amount between the left and right sides of the vehicle. Moreover, since the shift | offset | difference of braking amount can be suppressed with each wheel, it can also suppress that an emergency wheel transfers to ABS control at an early stage more than necessary. Further, even when large-diameter wheels are mounted, it is possible to suppress a difference in braking amount between the left and right sides of the vehicle.

  In the example described above, the case where only one wheel with different diameters is mounted has been described, but the case where two or more wheels with different diameters are mounted will be described below. When two or more wheels with different diameters are mounted, it is necessary to make a detailed comparison with the wheel diameter of the reference wheel in order to determine whether the different diameter wheels are small or large diameter wheels. The calculation process becomes complicated. Therefore, in the present embodiment, when three or more substantially the same wheel speed information values do not exist, it is determined that a plurality of different-diameter wheels are mounted, and the target hydraulic pressures of all four wheels are corrected to Control is performed so that a change in the braking amount due to the diameter difference is suppressed for the entire four wheels. In the configuration of the ECU 200, the wheel diameter difference determination unit 203 is omitted from the configuration of FIG. 2, and the signal from each wheel speed sensor 49 acquired by the wheel speed information acquisition unit 202 is directly provided to the braking amount correction unit 204. Will be.

When acquiring the wheel speed information value from the wheel speed information acquisition unit 202, the braking amount correction unit 204 suppresses a change in the braking amount that may be caused by the wheel diameter difference without specifying a different diameter wheel. A correction coefficient M for correcting the target braking amount is calculated. The correction coefficient Mxx (xx = FR, FL, RR, RL) can be calculated by the following equation 5.
Mxx = (VFR + VFL + VRR + VRL) / 4 / Vxx (Formula 5)
In this case, even when there are a plurality of wheels with different diameters and cannot be specified, the correction can be made so as to reduce the deviation of the braking amount at each wheel, so that balanced braking can be performed.

  FIG. 5 is a main flowchart for explaining the procedure of hydraulic control performed by the ECU 200 when all the wheels are corrected. The ECU 200 acquires signals from the sensors at predetermined intervals when the vehicle is driven. For example, the target braking amount acquisition unit 201 acquires signals from the stroke sensor 46 and the master pressure sensor 48. The wheel speed information acquisition unit 202 acquires a signal from each wheel speed sensor 49. Signals from the brake control unit 205, the pressure sensor 44 for each wheel, the master pressure sensor 48, the accumulator pressure sensor 51, and the like are acquired. It should be noted that the wheel speed information value for calculating the correction coefficient M is the same as in the above-described embodiment, in which the vehicle is currently running substantially straight ahead and is running at a constant speed without acceleration or deceleration. It is desirable to calculate using what was obtained when Therefore, the braking amount correction unit 204 may acquire signals from the acceleration sensor 81, the yaw rate sensor 82, the steering sensor 83, and the like in order to detect that the vehicle is traveling straight at a constant speed (S300). When determining whether or not the vehicle is currently traveling straight at a constant speed, it may be performed using a signal from another sensor or a result used in another control. The target braking amount acquisition unit 201 calculates the target braking amount requested by the driver using the stroke sensor 46 and the master pressure sensor 48 (S301). At this time, the braking control unit 205 adjusts the target braking amount requested by the driver acquired by the target braking amount acquisition unit 201 by ABS control, stable control for stabilizing the behavior of the vehicle, traction control, etc. The target hydraulic pressure Prefxx (xx = FR, FL, RR, RL) of each wheel is calculated using the braking force hydraulic pressure conversion coefficient (S302). Subsequently, the braking amount correction unit 204 calculates a correction coefficient M for each wheel based on (Equation 5) described above (S303). Then, the brake control unit 205 corrects the target hydraulic pressure of each wheel based on the target hydraulic pressure Prefxx calculated in S302 and the correction coefficient M calculated in S303 (S304).

  FIG. 6 shows details of the process in S304 of FIG. The braking control unit 205 calculates the corrected PrefFR by multiplying the target hydraulic pressure PrefFR calculated in S302 by the correction coefficient M for the right front wheel (FR) (S400). Subsequently, a corrected PrefFL is calculated by multiplying the target hydraulic pressure PrefFL calculated in S302 by the correction coefficient M for the left front wheel (FL) (S401). Similarly, the process for the right rear wheel (RR) (S402) and the process for the left rear wheel (RL) (S403) are performed.

  When the process in S304 is completed, the pressure increasing valve 40 and the pressure reducing valve 42 of each wheel are controlled so that the target hydraulic pressure corrected in S304 is obtained, so as to suppress the change in the braking amount that may be caused by the wheel diameter difference. The hydraulic control is performed (S305). Thereafter, the process returns to S300 to prepare for the next timing control.

  According to each of the above-described embodiments, even when there is a wheel diameter difference between the wheels on which the vehicle is mounted, the target oil pressure of the pressure increasing valve 40 and the pressure reducing valve 42 is corrected according to the wheel diameter difference. Thus, it is possible to prevent a difference in the braking amount due to the wheel diameter difference and to generate an appropriate braking force in each wheel and perform good braking. For example, it can contribute to prevention of deflection during braking and improvement of controllability of ABS control.

  In each of the above-described embodiments, the case of dealing with the wheel diameter difference that occurs when wheels of different diameters are mounted has been described. For example, even if all wheels have wheels that have regular wheel diameters, When the air pressure changes, the state may be the same as the state in which different diameter wheels are mounted. Also in this case, since the wheel speed information value changes, the target oil pressure of the pressure increasing valve 40 and the pressure reducing valve 42 can be corrected according to the wheel diameter difference by performing the same correction process as described above. As a result, it is possible to prevent a difference in the braking amount due to the wheel diameter difference, and to generate an appropriate braking force in each wheel and perform good braking.

  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.

1 is an overall configuration diagram for explaining a brake control device and an ECU included in the brake control device according to an embodiment of the present invention. It is a block diagram explaining the structure of ECU contained in the brake control apparatus which concerns on embodiment of this invention. In the brake control device concerning an embodiment of the present invention, it is a flow chart explaining operation in case a different diameter wheel is one wheel. It is a flowchart which shows the detail of S105 in the flowchart of FIG. In the brake control device concerning an embodiment of the present invention, it is a flow chart explaining operation in case a plurality of wheels of different diameter exist. It is a flowchart which shows the detail of S304 in the flowchart of FIG.

Explanation of symbols

  12 brake pedal, 14 master cylinder, 16 brake hydraulic control conduit, 18 brake hydraulic control conduit, 20 wheel cylinder, 21 axle, 22 master cut valve, 23 simulator cut valve, 24 stroke simulator, 26 reservoir tank, 28 hydraulic supply / discharge conduit , 30 high pressure conduit, 32 motor, 34 oil pump, 40 pressure increasing valve, 42 pressure reducing valve, 46 stroke sensor, 48 master pressure sensor, 49 wheel speed sensor, 50 accumulator, 51 accumulator pressure sensor, 53 relief valve, 80 actuator, 81 Acceleration sensor, 82 Yaw rate sensor, 83 Steering sensor, 100 Brake control device, 200 ECU, 201 Target braking amount acquisition unit, 202 car Wheel speed information acquisition unit, 203 wheel diameter difference determination unit, 204 braking amount correction unit, 205 braking control unit.

Claims (8)

Target braking amount acquisition means for acquiring a target braking amount of each wheel based on a braking request;
Braking control means for controlling the braking amount at each wheel to be the target braking amount;
Wheel speed information acquisition means for acquiring a wheel speed information value at the time of non-braking of each wheel;
A wheel diameter difference determining means for determining a wheel having a wheel diameter difference with respect to other wheels based on the wheel speed information value acquired at each wheel;
Braking amount correction means for correcting the target braking amount based on the wheel speed information value so as to suppress a change in the braking amount caused by the wheel diameter difference;
A brake control device comprising:   The wheel diameter difference determining means compares each wheel speed information value with each other, and when a wheel speed information value larger than a predetermined value by other wheel speed information values exists, the wheel having the wheel speed information value is changed to another wheel speed information value. The brake control device according to claim 1, wherein the brake control device determines that the wheel is a small-diameter wheel as compared with a wheel having a wheel speed information value.   If there is a difference of a predetermined value or more between the maximum value of the wheel speed information value and the quasi-maximum value next to the maximum value, the wheel diameter difference determination means may change the wheel whose wheel speed information value is the maximum value. The brake control device according to claim 1, wherein the brake control device is determined to be a small-diameter wheel in comparison with the other wheel.   The wheel diameter difference determining means compares each wheel speed information value with each other, and when a wheel speed information value smaller than a predetermined value by other wheel speed information values exists, the wheel having the wheel speed information value is changed to another wheel speed information value. The brake control device according to claim 1, wherein the brake control device determines that the wheel is a large-diameter wheel as compared with a wheel having a wheel speed information value.   The wheel diameter difference determining means, when there is a difference of a predetermined value or more between the minimum value of the wheel speed information value and the quasi-minimum value next to the minimum value, determines the wheel whose wheel speed information value is the minimum value. The brake control device according to claim 1, wherein the brake control device is determined to be a large-diameter wheel in comparison with the other wheel.   When there is one small-diameter wheel, the braking amount correction unit is configured to calculate a ratio between the maximum value of the wheel speed information value and the quasi-maximum value, and a correction coefficient for correcting the determined target braking amount of the small-diameter wheel. The brake control device according to claim 2 or claim 3, wherein   The braking amount correcting means corrects the ratio of the minimum value of the wheel speed information value and the quasi-minimum value when there is one large-diameter wheel, to correct the determined target braking amount of the large-diameter wheel. 6. The brake control device according to claim 4, wherein the brake control device is a coefficient. Target braking amount acquisition means for acquiring a target braking amount of each wheel based on a braking request;
Braking control means for controlling the braking amount at each wheel to be the target braking amount;
Wheel speed information acquisition means for acquiring a wheel speed information value at the time of non-braking of each wheel;
Braking that corrects the target braking amount so as to suppress a change in the braking amount due to the wheel diameter difference of each wheel by using a ratio between the average value of the wheel speed information value and the wheel speed information value of each wheel as a correction coefficient. An amount correction means;
A brake control device comprising:

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