JP2012158230A - Braking force control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control decrease in an improper deceleration in a vehicle.SOLUTION: The braking force control device controls the braking force of the vehicle (500) that includes a first hydraulic system corresponding to a right front wheel (WFR) and a left rear wheel (WRL), and a second hydraulic system corresponding to a left front wheel (WFL) and a right rear wheel (WRR). The braking force control device includes: a plurality of wheel speed detectors (83) that detect the wheel speeds of wheels respectively; controllers (110, 120) that perform braking force control to each rear wheel independently by controlling the first and the second hydraulic systems based on the differences of wheel speed of the front wheel and the wheel speed of rear wheel respectively; an abnormality detector (130) that can detect abnormalities in the wheel speed detector; a deceleration detector (140) that detects vehicle deceleration; and a control prohibition means (150) that prohibits braking force control by the controller when detecting abnormality in the wheel speed detector and that deceleration is below the predetermined value.

Description

  The present invention relates to a technical field of a braking force control device that can adjust a braking force in a vehicle for each wheel.

  As this type of braking force control device, for example, control (so-called EBD (Electronic Brake force Distribution) control) that automatically distributes and adjusts the distribution of braking force to the front wheels and rear wheels according to various conditions. It has been known. In the EBD control, for example, the wheel speed of the front wheel and the wheel speed of the rear wheel are compared, and when the wheel speed of the rear wheel is higher, the braking force for the rear wheel is strengthened.

  As a device that realizes the above-described EBD control, for example, Patent Document 1 proposes a technique that enables braking force distribution of the rear wheels to be performed independently on the left and right. Patent Document 2 proposes a technique for prohibiting braking force distribution control and performing normal brake control when an abnormality occurs in a wheel speed sensor. Further, Patent Document 3 proposes a technique of performing hydraulic pressure increase, pressure reduction, and holding control in response to an abnormality in the wheel speed sensor.

Japanese Patent Laid-Open No. 10-138895 JP-A-6-2111116 JP 2009-102018 A

  In the EBD control described above, for example, when an abnormality occurs in the wheel speed sensor of the right front wheel, the control is executed based on the wheel speed of the left front wheel that is the other front wheel (that is, the front wheel for which the wheel speed sensor is normal). . However, if the hydraulic system of the left front wheel fails in the above state, control is performed based on the wheel speed of the left front wheel to which no hydraulic pressure is applied. In this case, the left rear wheel that is the hydraulic system in common with the right front wheel (that is, the rear wheel that is normally hydraulically applied) is considered to be relatively large in slip, and the pressure reduction control for the left rear wheel is performed. . As described above, if the abnormality of the wheel speed sensor and the hydraulic pressure failure occur at the same time, pressure reduction is performed on the normal hydraulic system, resulting in an inappropriate reduction in deceleration.

  The present invention has been made in view of, for example, the above-described problems, and an object of the present invention is to provide a braking force control device capable of suppressing an inappropriate reduction in deceleration in a vehicle.

  In order to solve the above problems, the braking force control device of the present invention changes the first hydraulic system for changing the braking force for the right front wheel and the left rear wheel, and the second hydraulic system for changing the braking force for the left front wheel and the right rear wheel. A braking force control device for controlling a braking force of a vehicle comprising: a plurality of wheel speed detection means for detecting wheel speeds of the right front wheel and the left front wheel, and the right rear wheel and the left rear wheel, respectively; By controlling the first hydraulic system and the second hydraulic system based on the difference between the wheel speed of at least one of the right front wheel and the left front wheel and the wheel speed of the right rear wheel and the left rear wheel, Control means for independently performing braking force control on the right rear wheel and the left rear wheel, an abnormality detection means capable of detecting an abnormality in each of the plurality of wheel speed detection means, and detecting a deceleration of the vehicle Deceleration detection means and front When an abnormality is detected in at least one of the wheel speed detection means corresponding to the right front wheel and the left front wheel, respectively, and the detected deceleration is less than a predetermined value, the right rear wheel and the control means Control prohibiting means for prohibiting braking force control for the left rear wheel.

  According to the braking force control apparatus of the present invention, a vehicle is provided with a first hydraulic system that changes the braking force for the right front wheel and the left rear wheel, and a second hydraulic system that changes the braking force for the left front wheel and the right rear wheel. Power is controlled. More specifically, each of the right front wheel, the left front wheel, the right rear wheel, and the left rear wheel of the vehicle is provided with a wheel cylinder, for example, and each of the right front wheel and the left rear wheel has a single pipe. Connected to one pressure chamber. On the other hand, the wheel cylinders of the left front wheel and the right rear wheel are each connected to another pressure chamber via another pipe that is liquid-tightly separated from one pipe. That is, the vehicle controlled by the braking force control apparatus of the present invention is configured as a so-called X-pipe vehicle.

  During the operation of the braking force control apparatus of the present invention, the wheel speeds of the right front wheel and the left front wheel, and the right rear wheel and the left rear wheel are detected by a plurality of wheel speed detection means, respectively. The wheel speed detection means is configured as, for example, a wheel speed (in other words, rotation speed) detection sensor or the like, and is provided so as to correspond to each of the right front wheel and the left front wheel, and the right rear wheel and the left rear wheel.

  When the wheel speed of each wheel is detected, the control means compares the wheel speed of at least one of the right front wheel and the left front wheel with the wheel speed of the right rear wheel and the left rear wheel, and calculates the difference between the calculated wheel speeds. Based on this, the hydraulic pressures of the first hydraulic system and the second hydraulic system are controlled. Specifically, the hydraulic pressure of the second hydraulic system corresponding to the right rear wheel is controlled based on the wheel speed difference of any front wheel and the wheel speed of the right rear wheel. Further, the hydraulic pressure of the first hydraulic system corresponding to the left rear wheel is controlled based on the wheel speed difference of any front wheel and the wheel speed difference of the left rear wheel. According to such hydraulic control, since right and left independent braking force distribution can be performed according to the load movement of the vehicle, a suitable braking operation can be realized.

  The braking force control apparatus according to the present invention further includes an abnormality detecting means capable of detecting an abnormality of each of the plurality of wheel speed detecting means, and a deceleration detecting means for detecting the deceleration of the vehicle. The abnormality detection means is provided so as to correspond to each of the plurality of wheel speed detection means. For example, the wheel speeds of the respective wheels are compared with each other, the wheel acceleration is detected as an abnormal value, and the wheel speed and various sensors mounted on the vehicle. The abnormality of the wheel speed detecting means is detected by comparing with the above. That is, the “abnormality” according to the present invention means a state where the wheel speed detecting means cannot detect a normal value that should be detected. On the other hand, the deceleration detection means detects the deceleration of the vehicle. Since the deceleration detection means is required to detect the deceleration of the vehicle even when an abnormality occurs in the wheel speed detection means as will be described later, the deceleration detection means other than the wheel speed detected by the wheel speed detection means. The vehicle deceleration can also be detected.

  Here, in particular, the abnormality detecting means described above detects an abnormality in at least one of the wheel speed detecting means corresponding to the right front wheel and the left front wheel, and the deceleration detected by the deceleration detecting means is equal to or less than a predetermined value. In this case, the control prohibiting means prohibits the braking force control for the right rear wheel and the left rear wheel by the control means. Therefore, in this case, the braking force distribution control is not performed, and normal braking control is performed.

  The “predetermined value” here is set in advance according to the deceleration that can occur when an abnormality is detected in at least one of the first hydraulic system and the second hydraulic system. “Less than or equal to the value” means that the deceleration that should be originally obtained is not obtained due to an abnormality occurring in at least one of the first hydraulic system and the second hydraulic system. I mean. That is, it can be said that the hydraulic pressure failure is indirectly detected by using the deceleration of the vehicle. Incidentally, when an abnormality has occurred in the wheel speed detection means, it is impossible to detect a hydraulic pressure failure based on the wheel speed, so the method of detecting a hydraulic pressure failure from the vehicle deceleration described above is It is extremely effective.

  Here, it is assumed that a wheel speed abnormality of one front wheel is detected by the wheel speed detecting means, and no hydraulic failure has occurred in the first hydraulic system and the second hydraulic system. In this case, normal braking force control can be performed by using the wheel speed of the other front wheel (that is, the front wheel on which no wheel speed abnormality is detected). However, when a wheel speed abnormality of one front wheel is detected by the wheel speed detection means and a hydraulic pressure failure has occurred in at least one of the first hydraulic system or the second hydraulic system, the wheel speed abnormality is detected. Even if it is the front wheel that is not, the oil pressure may not be applied due to the oil pressure failure. Therefore, the rear wheel of the system in which the hydraulic pressure is normally applied is regarded as a large slip, and the pressure reduction control is performed on the rear wheel. As described above, if the abnormality of the wheel speed detecting means and the hydraulic pressure failure occur at the same time, the pressure reduction control that should not be performed is performed, resulting in an inappropriate decrease in deceleration. .

  However, in the present invention, as described above, it is possible to obtain only a deceleration equal to or less than a predetermined value in a state where the abnormality of the wheel speed detection means has occurred (that is, it is estimated that a hydraulic pressure failure has occurred). In this case, braking force control by the control means is prohibited. Therefore, it is possible to effectively suppress an unintended inappropriate reduction in deceleration.

  In another aspect of the braking force control apparatus of the present invention, the control prohibiting means prohibits pressure reduction control on the first hydraulic system and the second hydraulic system, whereby the right rear wheel and the left by the control means are controlled. The braking force control for the rear wheels is prohibited.

  According to this aspect, when the braking force control by the control means is performed, the pressure reduction control for each hydraulic system that changes the braking force is prohibited. For this reason, it can suppress reliably that the fall of an inappropriate deceleration occurs.

  In the aspect of prohibiting the pressure reduction control described above, the control prohibiting means prohibits the pressure increase control in addition to the pressure reduction control with respect to the first hydraulic system and the second hydraulic system, whereby the right rear wheel by the control means. The brake force control for the left rear wheel may be prohibited.

  When pressure reduction control for each hydraulic system is prohibited, if pressure increase control that is not intended (for example, pressure increase control due to road surface disturbance, etc.) is performed, or if the pressure increase amount becomes excessive, pressure reduction Since it cannot be controlled, the pressure of each hydraulic system remains in an inappropriate state. In this aspect, when the pressure reduction control is prohibited, the pressure increase control is also prohibited, so that the above-described problems can be suppressed and the vehicle behavior can be prevented from becoming unstable.

  In the aspect of prohibiting the pressure reduction control or the pressure increase / decrease control described above, the control prohibiting means, when prohibiting braking force control on the right rear wheel and the left rear wheel by the control means, the first hydraulic system and the You may comprise so that the said control means may be controlled so that the oil_pressure | hydraulic of a 2nd hydraulic system becomes mutually the same.

  When pressure reduction control or pressure increase / decrease control for each hydraulic system is prohibited, if an unintended hydraulic pressure difference (for example, a hydraulic pressure difference due to road pressure disturbance) occurs, the pressure increase / decrease control cannot be performed. The hydraulic pressure difference between each hydraulic system remains in an inappropriate state. In this aspect, when the pressure reduction control or the pressure increase / decrease control is prohibited, by making the hydraulic pressures of the first hydraulic system and the second hydraulic system the same, the above-described problems are suppressed and the vehicle behavior becomes unstable. Can be prevented.

  In addition, “same” in this aspect means not only the case where the hydraulic pressures of the first hydraulic system and the second hydraulic system completely match, but also a state in which the values are close to each other until the above-described problem can be suppressed. is doing. Therefore, even if the hydraulic pressures of the first hydraulic system and the second hydraulic system are not set to the same value, the above-described effects can be obtained correspondingly by controlling the values to be close to each other.

  The effect | action and other gain of this invention are clarified from the form for implementing invention demonstrated below.

It is a schematic structure figure showing the composition of the braking force control device concerning an embodiment. It is a block diagram which shows the structure of ECU. It is a flowchart which shows operation | movement of the braking force control apparatus which concerns on embodiment. It is a conceptual diagram which shows abnormal operation | movement when abnormality of a wheel speed sensor and hydraulic pressure failure generate | occur | produce.

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

  First, the overall configuration of the braking force control apparatus according to the present embodiment will be described with reference to FIG. FIG. 1 is a schematic configuration diagram showing the configuration of the braking force control apparatus according to the embodiment.

  In FIG. 1, a braking force control device according to the present embodiment mainly includes a braking device 1 that is operated when a braking force is applied to a vehicle, and braking such as ABS control and EBD control by operating the braking device 1. An electronic control unit (ECU) 2 serving as a braking control means for executing control is provided.

  The ECU 2 includes, for example, a CPU (Central Processing Unit) (not shown), a ROM (Read Only Memory) that stores a predetermined braking control program in advance, a RAM (Random Access Memory) that temporarily stores calculation results of the CPU, It is composed of a backup RAM for storing prepared information and the like. Below, the specific structure of this ECU2 is demonstrated with reference to FIG. FIG. 2 is a block diagram showing the configuration of the ECU.

  In FIG. 2, the ECU 2 includes a brake fluid pressure control unit 110, an EBD control unit 120, a wheel speed sensor abnormality detection unit 130, a vehicle deceleration detection unit 140, and a control prohibition unit 150. .

  The brake fluid pressure control unit 110 can change the braking force of each wheel WFR, WFL, WRR, WRL by controlling the brake fluid pressure in the braking device 1. The brake fluid pressure control unit 110 changes the braking force based on, for example, an operation amount of the brake pedal 10 (see FIG. 1) by the driver, a master cylinder pressure associated therewith, or the like. Further, EBD control can be performed by an instruction from the EBD control unit 120 described later.

  For example, the EBD control unit 120 determines whether or not to perform EBD control based on a threshold set for the deceleration of the vehicle, and when it is determined that EBD control should be performed, the brake fluid pressure control unit 110 is instructed to perform EBD control. Wheel speed sensors 83FR, 83FL, 83RR, 83RL (see FIG. 1) for detecting the wheel speed of each wheel WFR, WFL, WRR, WRL are connected to the EBD control unit 120, and each wheel WFR, WFL, WRR is connected. The EBD control is performed according to the wheel speed of the WRL. The EBD control unit 120 functions as an example of the “control unit” of the present invention together with the brake fluid pressure control unit 110 described above. A specific EBD control method will be described in detail later.

  The wheel speed sensor abnormality detection unit 130 is an example of the “abnormality detection unit” in the present invention, and detects abnormality of the wheel speed sensors 83FR, 83FL, 83RR, 83RL. For example, the wheel speed sensor abnormality detection unit 130 detects the wheel speed by comparing each wheel WFR, WFL, WRR, WRL with each other, detecting an abnormal value of wheel acceleration, comparing with other sensors mounted on the vehicle, and the like. Abnormalities of the speed sensors 83FR, 83FL, 83RR, 83RL are detected. The abnormality of the wheel speed sensors 83FR, 83FL, 83RR, 83RL detected here is transmitted to the control prohibition unit 150 described later.

  The vehicle deceleration detection unit 140 is an example of the “deceleration detection unit” of the present invention, and detects the deceleration of the vehicle on which the braking force control device according to the present embodiment is mounted. The deceleration may be detected constantly or periodically, and may be appropriately detected as necessary. The vehicle deceleration detected by the vehicle deceleration detection unit 140 is transmitted to the control prohibition unit 150 described later.

  The control prohibition unit 150 is an example of the “control prohibition unit” in the present invention, and prohibits the EBD control by the EBD control unit 120 based on information from the wheel speed sensor abnormality detection unit 130 and the vehicle deceleration detection unit 140. . That is, it is possible to prevent the EBD control from being performed under a predetermined condition. Specific control regarding prohibition of EBD control will be described in detail later.

  The ECU 2 is an integrated electronic control unit configured to include each of the above-described parts, and all the operations related to the above-described parts are configured to be executed by the ECU 2. However, the physical, mechanical, and electrical configurations of the respective parts are not limited thereto. For example, each of the parts includes a plurality of ECUs, various processing units, various controllers, various computer systems such as a microcomputer device, and the like. It may be configured as.

  Returning to FIG. 1, the braking device 1 according to the first embodiment has a so-called X-pipe brake hydraulic pressure circuit, and is individually controlled with respect to at least the front wheels WFR and WFL and the rear wheels WRR and WRL. Power can be generated.

  More specifically, the braking device 1 generates a brake fluid pressure by supplying brake fluid pressure and brake fluid pressure generating means 20 that generates a brake fluid pressure corresponding to the amount of operation of the brake pedal 10 by the driver. The braking force generating means (for example, wheel cylinder, caliper, etc.) 30FR, 30FL, 30RR, 30RL for each wheel WFR, WFL, WRR, WRL to be made and the brake fluid pressure generated by the brake fluid pressure generating means 20 are used as they are or each Brake fluid pressure adjusting means 40 that adjusts the pressure for each of the wheels WFR, WFL, WRR, and WRL and supplies them to the respective braking force generating means 30FR, 30FL, 30RR, and 30RL.

  The brake fluid pressure generating means 20 includes a brake boosting means (brake booster) 21 for doubling an operation pressure (pedal depression force) accompanying the brake operation of the driver input to the brake pedal 10 by a predetermined boost ratio. A master cylinder 22 for converting the pedal depression force doubled by the brake boosting means 21 into a brake fluid pressure (hereinafter referred to as “master cylinder pressure”) corresponding to an operation amount of the brake pedal 10, and a brake fluid are stored. And a reservoir tank 23.

  Here, two hydraulic chambers (not shown) are provided inside the master cylinder 22, and the master cylinder pressure is generated in each of the hydraulic chambers. One of the master cylinder pressures generated in each hydraulic chamber is supplied to the right front wheel WFR and the left rear wheel WRL via a first brake hydraulic circuit system described later of the brake hydraulic pressure adjusting means 40, and the other is supplied to the brake hydraulic pressure. It is supplied to the left front wheel WFL and the right rear wheel WRR via a second brake hydraulic circuit system described later of the adjusting means 40. In order to realize such an operation, the braking device 1 according to the present embodiment has one end connected to each hydraulic chamber and the other end connected to the first brake hydraulic circuit system and the second brake hydraulic circuit system, respectively. A first hydraulic pipe 24 and a second hydraulic pipe 25 connected to each other are provided.

  The brake fluid pressure adjusting means 40 adjusts the brake fluid pressure (master cylinder pressure) in the first hydraulic pipe 24 and the second hydraulic pipe 25 as described above, or adjusts each brake force generating means 30FR, 30FL, 30RR. , 30RL is a so-called brake actuator. The brake fluid pressure adjusting means 40 operates according to a control command from the brake fluid pressure control unit 110 in the ECU 2.

  The brake fluid pressure adjusting means 40 includes a first brake fluid pressure circuit system that transmits brake fluid pressure to the right front wheel WFR and the left rear wheel WRL, and a brake fluid pressure that transmits brake fluid pressure to the left front wheel WFL and the right rear wheel WRR. 2 brake hydraulic circuit system. The first brake hydraulic circuit system here is an example of the “first hydraulic system” in the present invention, and the second brake hydraulic circuit system is an example of the “second hydraulic system” in the present invention. . Here, the first brake hydraulic circuit system is connected to the first hydraulic pipe 24, while the second brake hydraulic circuit system is connected to the second hydraulic pipe 25.

  The brake fluid pressure adjusting means 40 is provided with a master cylinder pressure sensor 41 for detecting the brake fluid pressure (that is, master cylinder pressure) supplied from the brake fluid pressure generating means 20. The master cylinder pressure sensor 41 is provided in one of the first hydraulic pipe 24 and the second hydraulic pipe 25 and transmits a detection signal to the brake hydraulic pressure control unit 110 in the ECU 2. Here, the master cylinder pressure sensor 41 is illustrated as being provided in the first hydraulic pipe 24.

  The brake fluid pressure adjusting means 40 includes master cut valves 42 and 43 as flow rate adjusting means for each brake fluid in the first and second brake fluid pressure circuit systems. The master cut valves 42 and 43 are so-called normally-open flow rate adjusting electromagnetic valves that are normally open, and the valve opening degree is controlled in accordance with the energization by the brake fluid pressure control unit 110 of the ECU 2. The That is, the master cut valves 42 and 43 adjust the pressure of the brake fluid discharged from the pressurizing pumps 69 and 70, which will be described later, by controlling the valve opening according to the energization amount, and release the master cut valves 42 and 43 to the master cylinder 22 side. .

  Here, in the brake fluid pressure adjusting means 40, the first hydraulic pipe 24 is connected to the connecting passage 44 via the master cut valve 42, while the second hydraulic pipe 25 is connected to the connecting passage via the master cut valve 43. 45. Two branch passages 46 and 47 are connected to the connection passage 44 of the first brake hydraulic circuit system so as to branch from there, and the connection passage 45 of the second brake hydraulic circuit system is connected thereto from there. Two branch passages 48 and 49 are connected so as to be branched. In the first brake hydraulic circuit system, each of the branch passages 46 and 47 is connected to the hydraulic piping 31FR of the right front wheel WFR and the hydraulic piping 31RL of the left rear wheel WRL, respectively. On the other hand, in the second brake hydraulic circuit system, each of the branch passages 48 and 49 is connected to the hydraulic piping 31RR of the right rear wheel WRR and the hydraulic piping 31FL of the left front wheel WFL, respectively.

  On each of the branch passages 46, 47, 48, 49, brake hydraulic pressure adjusting units capable of adjusting the brake hydraulic pressure for the corresponding braking force generating means 30FR, 30FL, 30RR, 30RL are provided on the wheels WFR, WFL, It is arranged for each WRR and WRL. The brake fluid pressure adjusting unit includes holding valves 50, 51, 52, 53 prepared for each wheel WFR, WFL, WRR, WRL, brake fluid pressure discharge passages 54, 55, 56, 57, and pressure reducing valves 58, 59, 60, 61. Here, holding valves 50, 51, 52, and 53 are provided on the respective branch passages 46, 47, 48, and 49, and brake fluid pressure is further provided downstream of the holding valves 50, 51, 52, and 53. The discharge passages 54, 55, 56, and 57 are connected so as to branch from the branch passages 46, 47, 48, and 49, respectively. On the brake fluid pressure discharge passages 54, 55, 56, 57, pressure reducing valves 58, 59, 60, 61 are provided, respectively.

  Each of the holding valves 50, 51, 52, 53 described above is a so-called normally-open electromagnetic valve, and is normally open in a non-excited state, and is energized by the brake fluid pressure control unit 110 in the ECU 2. It is in an excited state and can be closed. On the other hand, each of the pressure reducing valves 58, 59, 60, 61 is a so-called normally closed electromagnetic valve, which is normally closed in a non-excited state, and is in an excited state with energization by the brake fluid pressure control unit 110. It can be opened.

  In addition, here, the brake fluid pressure discharge passages 62 and 55 are arranged together with the brake fluid pressure discharge passages 54 and 55 of the first brake fluid pressure circuit system, and the brake fluid pressure discharges of the second brake fluid pressure circuit system. A brake hydraulic pressure discharge collecting passage 63 is provided to collect the passages 56 and 57 together, and the brake hydraulic pressure discharge collecting passages 62 and 63 are connected to auxiliary reservoirs 64 and 65, respectively.

  Further, in the first brake fluid pressure circuit system, a pump passage 66 that branches from a branch point between the connection passage 44 and each of the branch passages 46 and 47 and is connected to the brake fluid pressure discharge collecting passage 62 is provided. Similarly, the second brake hydraulic circuit system is provided with a pump passage 67 that branches from a branch point between the connection passage 45 and each of the branch passages 48 and 49 and is connected to the brake hydraulic pressure discharge collecting passage 63. .

  The pump passages 66 and 67 are respectively provided with pressure pumps 69 and 70 driven by one electric motor 68. These pressurizing pumps 69 and 70 discharge the brake fluid toward the respective branch points on the master cut valves 42 and 43 side, and are pressurized against the branch passages 46 and 47 and the branch passages 48 and 49. Each brake fluid pressure is supplied. In other words, the pressure pump 69 of the first brake hydraulic circuit system supplies the brake fluid supplied to the corresponding braking force generating means 30FR and 30RL to increase the braking force generated on the right front wheel WFR and the left rear wheel WRL. Increase the pressure. On the other hand, the pressure pump 70 of the second brake hydraulic circuit system supplies the brake fluid supplied to the corresponding braking force generation means 30FL and 30RR to increase the braking force generated on the left front wheel WFL and the right rear wheel WRR, respectively. Increase the pressure. The electric motor 68 is driven by power supply from a battery (not shown). The pump passages 66 and 67 are provided with damper chambers 71 and 72 for avoiding pulsation of the brake fluid discharged from the pressurizing pumps 69 and 70, respectively.

  The brake fluid pressure adjusting means 40 is further provided with suction passages 73 and 74 that are branched from the first hydraulic pipe 24 and the second hydraulic pipe 25 and connected to the auxiliary reservoirs 64 and 65, respectively. Reservoir cut check valves 75 and 76 are provided on the auxiliary reservoirs 64 and 65 side of the suction passages 73 and 74, respectively.

  The operation of the braking device 1 configured as described above is controlled by the ECU 2 as described above. Hereinafter, the normal braking operation of the braking force control apparatus according to the present embodiment will be described with reference to FIGS. 1 and 2.

  During operation of the braking force control apparatus according to the present embodiment, the operation amount of the brake pedal 10 and the master cylinder pressure detected by the master cylinder pressure sensor 41 are input to the brake hydraulic pressure control unit 110 in the ECU 2. That is, the brake pedal operation amount detected when the driver makes a braking request by operating the brake pedal 10 and the master cylinder pressure generated by the operation are input to the ECU 2. The amount of operation of the brake pedal 10 includes, for example, the amount of depression of the brake pedal 10 and the pedal depression force, and is detected by a pedal stroke sensor, a pedal depression force sensor, and the like (not shown).

  The brake fluid pressure control unit 110 in the ECU 2 calculates the driver's requested vehicle braking force based on the operation amount of the brake pedal 10. Then, the brake fluid pressure control means of the ECU 2 controls the brake fluid pressure adjusting means 40 so that the required vehicle braking force acts on the vehicle by the sum of the braking forces of all the wheels WFR, WFL, WRR, WRL. Note that the brake fluid pressure is distributed to each of the braking force generation means 30FR, 30FL, 30RR, and 30RL at a predetermined or distribution ratio according to the state of the vehicle.

  When the brake fluid pressure control unit 110 performs the pressure increase control to increase the braking force, the master cut valves 42 and 43 and the holding valves 50, 51, and 52 corresponding to the wheels WFR, WFL, WRR, and WRL to be controlled are performed. , 53 are opened, while the pressure reducing valves 58, 59, 60, 61 are closed. As a result, in the wheels WFR, WFL, WRR, WRL to be controlled, the braking force is increased by increasing the brake fluid pressure supplied to the braking force generating means 30FR, 30FL, 30RR, 30RL.

  If the required vehicle braking force can be generated without driving the pressurizing pumps 69 and 70 when the brake fluid pressure is increased (in other words, the required vehicle braking force is applied to the vehicle by the master cylinder pressure). If it can be activated), the brake fluid pressure control means stops the pressurizing pumps 69 and 70 by stopping the electric motor 68. At this time, the brake fluid pressure according to the master cylinder pressure is supplied to the braking force generation means 30FR, 30FL, 30RR, 30RL to be controlled, and the brake force according to the brake fluid pressure is applied to each wheel WFR, WFL, WRR, WRL. Therefore, the vehicle braking force that satisfies the required vehicle braking force acts on the vehicle. Hereinafter, the sum of the braking forces of the wheels WFR, WFL, WRR, and WRL generated without driving the pressurizing pumps 69 and 70 will be appropriately referred to as “reference vehicle braking force”.

  When the brake fluid pressure is increased, even if the reference vehicle braking force is generated with the maximum magnitude, the reference vehicle braking force may not satisfy the required vehicle braking force. That is, there are cases where the required vehicle braking force cannot be generated in the vehicle only with the reference vehicle braking force based on the master cylinder pressure. Therefore, the brake fluid pressure control means in this case opens the holding valves 50, 51, 52, 53 corresponding to the wheels WFR, WFL, WRR, WRL to be controlled, while the master cut valves 42, 43 and the pressure reducing valve 58, 59, 60, 61 are closed, and the electric motor 68 and the pressure pumps 69, 70 are set so that a vehicle braking force corresponding to the shortage (hereinafter referred to as “differential pressure vehicle braking force” as appropriate) is generated. Drive. That is, here, the master cut valves 42, 43, the electric motor 68, and the pressure pumps 69, 70 are driven so that the brake fluid is pressurized with a pressurization amount (ie, discharge amount or discharge pressure) corresponding to the shortage. Is done. As a result, the insufficient brake fluid pressure is increased with respect to the braking force generation means 30FR, 30FL, 30RR, 30RL to be controlled, so that the reference vehicle braking force and the differential pressure vehicle braking force that satisfy the required vehicle braking force are satisfied. The vehicle braking force combined with the above acts on the vehicle.

  The brake fluid pressure control unit 110 closes the holding valves 50, 51, 52, 53 corresponding to the wheels WFR, WFL, WRR, WRL to be controlled when performing the pressure reduction control to reduce the braking force, The pressure reducing valves 58, 59, 60, 61 are opened. Thereby, in the wheels WFR, WFL, WRR, and WRL to be controlled, the braking force is reduced by reducing the brake fluid pressure supplied to the braking force generating means 30FR, 30FL, 30RR, and 30RL.

  The brake fluid pressure control unit 110 also holds the holding valve 50 corresponding to the wheels WFR, WFL, WRR, WRL to be controlled after the brake fluid pressure of the braking force generating means 30FR, 30FL, 30RR, 30RL is increased or decreased. , 51, 52, 53 and the pressure reducing valves 58, 59, 60, 61 may be closed to hold the brake fluid pressure. According to the holding control, the brake hydraulic pressure of the braking force generating means 30FR, 30FL, 30RR, 30RL is kept constant at the wheels WFR, WFL, WRR, WRL to be controlled, so that the braking force is kept constant. It is.

  Next, EBD control by the braking force control apparatus according to the present embodiment will be described in detail with reference to FIG. 3 in addition to FIG. 1 and FIG. FIG. 3 is a flowchart showing the operation of the braking force control apparatus according to this embodiment.

  In FIG. 3, in the braking force control apparatus according to the present embodiment, a first predetermined value that is a threshold value corresponding to vehicle deceleration is set as a start condition for EBD control. The vehicle deceleration is detected by a vehicle deceleration detector 140 (see FIG. 2). The first predetermined value is stored in advance in a memory or the like of the EBD control unit 120 in the ECU 2 and is compared with the detected deceleration. Note that the first predetermined value may be set in advance through experiments and simulations, taking into account, for example, the riding state and loading state of the vehicle.

  When the vehicle deceleration is greater than the first predetermined value (step S01: YES), EBD control is started (step S02). That is, when the vehicle is decelerated so much that EBD control should be performed, the brake fluid pressure control unit 110 is controlled by the EBD control unit 120 in the ECU 2.

  Specifically, the wheel speed of at least one of the right front wheel WFR and the left front wheel WFL is first compared with the wheel speed of the right rear wheel WRR and the left rear wheel WRL, and the first wheel speed is calculated based on the calculated wheel speed difference. The brake fluid pressure of the brake fluid pressure circuit system and the second brake fluid pressure circuit system is controlled. More specifically, the brake fluid pressure of the second brake fluid pressure circuit system corresponding to the right rear wheel WRR is determined based on the wheel speed of either the right front wheel WFR or the left front wheel WFL and the wheel speed difference of the right rear wheel WRR. Be controlled. Further, the brake fluid pressure of the first brake fluid pressure circuit system corresponding to the left rear wheel WRL is controlled based on the wheel speed of either the right front wheel WFR or the left front wheel WFL and the wheel speed difference of the left rear wheel WRL. According to such control, since appropriate braking force distribution can be performed according to the load movement of the vehicle, extremely appropriate braking can be realized.

  Here, in this embodiment, in particular, the wheel speed sensor abnormality detection unit 130 in the ECU 2 determines whether or not an abnormality has occurred in the wheel speed sensors 83FR and 83FL corresponding to the front wheels WFR and WFL (step S03). . Then, when an abnormality is detected in any of wheel speed sensors 83FR and 83FL (step S03: YES), whether or not the vehicle deceleration detected by vehicle deceleration detection unit 140 is equal to or less than a second predetermined value. Is determined (step S04).

  The second predetermined value is an example of the “predetermined value” in the present invention, and a deceleration that may occur when an abnormality is detected in at least one of the first brake hydraulic circuit system and the second brake hydraulic circuit system. It is preset according to For this reason, the situation where the deceleration is equal to or less than the second predetermined value can be obtained originally because an abnormality has occurred in at least one of the first brake fluid pressure circuit and the second brake fluid pressure circuit. It means that the deceleration that should be achieved cannot be obtained. That is, here, the hydraulic pressure failure is indirectly detected using the deceleration of the vehicle. The second predetermined value may be set as the same value as the first predetermined value described above, or may be set as a different value.

  If it is determined that the deceleration of the vehicle is equal to or less than the second predetermined value (step S04: YES), the brake fluid pressure control unit 110 prohibits the pressure reduction control to each rear wheel WRR, WRL (step S05), and increases the speed. Pressure control is prohibited (step S06), and control is performed to maintain the brake fluid pressure of the first brake fluid pressure circuit system and the second brake fluid pressure circuit system at the same pressure (step S07). That is, the EBD control for independently controlling the braking force for the rear wheels WRR and WRL is prohibited. On the other hand, when no abnormality is detected in the wheel speed sensors 83FR and 83FL (step S03: NO), the deceleration of the vehicle is larger than a second predetermined value (that is, the first brake hydraulic circuit system and the second brake hydraulic pressure). If a hydraulic pressure failure is not detected in the circuit system (step S04: NO), normal EBD control is performed (step S08).

  Here, if any of the wheel speed sensors 83FR and 83FL has detected an abnormality, the vehicle deceleration is greater than a second predetermined value (that is, the first brake hydraulic circuit system and the second brake hydraulic circuit system). No hydraulic failure has occurred). In this case, normal EBD control can be performed by using the wheel speed detected by the wheel speed sensor 83 on which no wheel speed abnormality is detected. However, an abnormality is detected by one of the wheel speed sensors 83FR and 83FL, and the deceleration of the vehicle is equal to or less than a second predetermined value (that is, the first brake hydraulic circuit system and the second brake hydraulic circuit system). In this case, there is a possibility that the hydraulic pressure is not applied due to the hydraulic pressure failure even if the front wheel has no detected wheel speed abnormality. In this case, inappropriate pressure reduction control is performed on the rear wheel where the hydraulic pressure is normally applied.

  Hereinafter, a situation in which the above-described problem may occur will be specifically described with reference to FIG. FIG. 4 is a conceptual diagram showing an abnormal operation when an abnormality of the wheel speed sensor and a hydraulic pressure failure occur.

  Consider a case where an abnormality is detected in the wheel speed sensor 83FR corresponding to the right front wheel WFR as shown in FIG. In this case, if no abnormality is detected in the wheel speed sensor 83FL corresponding to the left front wheel WFL, the braking force control can be performed using the left front wheel WFL wheel speed. However, if a hydraulic pressure failure occurs in the second brake hydraulic circuit system corresponding to the left front wheel WFL, since the wheel speed of the left front wheel WFL to which no hydraulic pressure is applied is used as a reference, the hydraulic pressure is normally applied. The left rear wheel WRL that is present (that is, the rear wheel corresponding to the second brake hydraulic circuit system in which the hydraulic pressure has not failed) is considered to be relatively large in slip, and the left rear wheel WRL that should not be subjected to pressure reduction control. Therefore, the decompression control will be performed.

  For such inconvenience, in the braking force control apparatus according to the present embodiment, as described above, an abnormality is detected in the wheel speed sensors 83FR and 83FL, and the deceleration of the vehicle is equal to or less than a second predetermined value ( That is, in the case where a hydraulic pressure failure has occurred in the first brake fluid pressure circuit system or the second brake fluid pressure circuit system), pressure reduction control for each rear wheel WRR, WRL is prohibited (step S05 in FIG. 3). reference). Therefore, it is possible to suppress the occurrence of an inappropriate reduction in deceleration.

  In addition, when pressure reduction control for the first brake fluid pressure circuit system and the second brake fluid pressure circuit system is prohibited, unintended pressure increase control (for example, pressure increase control due to road surface disturbance or the like) is not performed. If the amount of pressure increase is excessive, the brake fluid pressure of the first brake fluid pressure circuit system or the second brake fluid pressure circuit system may remain in an inappropriate state because the pressure reduction control cannot be performed. is there. For this reason, in this embodiment, in addition to the pressure reduction control, the pressure increase control is also prohibited (see step S06 in FIG. 3). Therefore, it is possible to suppress the above-described problems and prevent the vehicle behavior from becoming unstable.

  Furthermore, when pressure reduction control or pressure increase / decrease control on the first brake hydraulic circuit system and the second brake hydraulic circuit system is prohibited, an unintended hydraulic pressure difference (for example, a hydraulic pressure difference when maintaining hydraulic pressure due to road surface disturbance, etc.) ), The pressure difference between the first brake hydraulic circuit system and the second brake hydraulic circuit system may remain in an inappropriate state because the pressure increase / decrease control cannot be performed. For this reason, in this embodiment, when the pressure reduction control or the pressure increase / decrease control is prohibited, the control is performed so that the brake fluid pressures in the first brake fluid pressure circuit system and the second brake fluid pressure circuit system are the same (FIG. 3). (See Step S07). Therefore, the malfunction mentioned above is suppressed and a vehicle behavior can be stabilized more reliably.

  It should be noted that the above-described prohibition of pressure increase control and the same pressure holding control are not necessarily performed, and an inappropriate decrease in deceleration can be suppressed as long as the pressure decrease control is prohibited.

  As described above, according to the braking force control apparatus according to the present embodiment, since the EBD control is prohibited under a predetermined condition, it is possible to appropriately suppress an inappropriate decrease in deceleration in the vehicle. is there.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the spirit or idea of the invention that can be read from the claims and the entire specification. The apparatus is also included in the technical scope of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Brake device, 2 ... ECU, 10 ... Brake pedal, 20 ... Brake hydraulic pressure generation means, 24 ... 1st hydraulic piping, 25 ... 2nd hydraulic piping, 30 ... Braking force generation means, 40 ... Brake hydraulic pressure adjustment means , 83: Wheel speed sensor, 110: Brake fluid pressure control unit, 120 ... EBD control unit, 130 ... Wheel speed sensor abnormality detection unit, 140 ... Vehicle deceleration detection unit, 150 ... Control prohibition unit, WFR, WFL, WRR, WRL ... Wheel

Claims (4)

A braking force control device that controls a braking force of a vehicle including a first hydraulic system that changes a braking force for a right front wheel and a left rear wheel, and a second hydraulic system that changes a braking force for a left front wheel and a right rear wheel. ,
A plurality of wheel speed detecting means for detecting wheel speeds of the right front wheel and the left front wheel, and the right rear wheel and the left rear wheel, respectively;
By controlling the first hydraulic system and the second hydraulic system based on the difference between the wheel speed of at least one of the right front wheel and the left front wheel and the wheel speed of the right rear wheel and the left rear wheel, Control means for independently performing braking force control on the right rear wheel and the left rear wheel;
Abnormality detecting means capable of detecting abnormality of each of the plurality of wheel speed detecting means;
Deceleration detecting means for detecting deceleration of the vehicle;
When an abnormality is detected in at least one of the wheel speed detection means corresponding to the right front wheel and the left front wheel, respectively, and the detected deceleration is less than a predetermined value, the right rear wheel by the control means And a control prohibiting means for prohibiting the braking force control for the left rear wheel.   The control prohibiting unit prohibits the braking force control on the right rear wheel and the left rear wheel by the control unit by prohibiting pressure reduction control on the first hydraulic system and the second hydraulic system. The braking force control apparatus according to claim 1.   The control prohibiting means prohibits the pressure increase control in addition to the pressure reduction control for the first hydraulic system and the second hydraulic system, thereby controlling the braking force for the right rear wheel and the left rear wheel by the control means. The braking force control device according to claim 2, wherein the braking force control device is prohibited.   When the control prohibiting unit prohibits braking force control on the right rear wheel and the left rear wheel by the control unit, the first hydraulic system and the second hydraulic system have the same hydraulic pressure. 44. The braking force control apparatus according to claim 2 or 43, wherein the control means is controlled.

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