Braking control device

Abstract

A braking control device (BC) is provided with: a specification unit (102) that specifies a wheel having a relatively small load among a plurality of wheels (W); and a control unit (103) that designates the wheel (W) specified to have a relatively small load by the specification unit (102) as a target wheel, and causes a wheel braking unit (8) corresponding to the target wheel to apply friction braking force to the target wheel in order to remove rust formed in the wheel braking unit (8).

Description

Braking control device

[0001] The present disclosure relates to a braking control device.

[0002] Patent Document 1 discloses a vehicle control device that estimates the amount of rust that has developed on the friction surface of a braking rotating member from the amount of time the vehicle has been left standing, and when the vehicle starts moving after the main power is turned on, increases the time for applying frictional braking force according to the estimated amount of rust. This vehicle control device compensates for the reduction in running force due to the frictional braking force with driving force.

[0003] JP 2012-126288 A

[0004] In Patent Document 1, rust removal is performed by setting control amounts of friction braking force and driving force according to the estimated amount of rust regardless of the state of the vehicle at the time of start. However, when rust removal control such as that in Patent Document 1 is performed, there is a risk of uneven wear occurring in the braking members. One aspect of the present disclosure aims to reduce uneven wear of the braking members through rust removal control.

[0005] In order to solve the above problems, a braking control device according to one embodiment of the present disclosure is applied to a vehicle having a plurality of wheels, and includes a plurality of wheel braking units provided on each of the plurality of wheels and applying a frictional braking force to each of the wheels, an identification unit that identifies a wheel among the plurality of wheels that has a relatively light load, and a control unit that sets the wheel identified by the identification unit as having a relatively light load as a target wheel, and causes the wheel braking unit to apply the frictional braking force to the target wheel in order to remove rust that has occurred in the wheel braking unit corresponding to the target wheel.

[0006] According to one aspect of the present disclosure, uneven wear of braking members can be reduced by rust removal control.

[0007] It is a plan view showing typically the overall configuration of a vehicle equipped with a brake control device according to a first embodiment of the present disclosure. It is a diagram used to explain refresh control executed when accelerating a vehicle. It is a diagram used to explain refresh control executed when suddenly accelerating a vehicle. It is a diagram used to explain refresh control executed when the operation of the accelerator pedal is stopped after suddenly accelerating a vehicle. It is a flowchart showing the flow of processing of a control unit.

[0008] [Embodiment 1] Fig. 1 is a plan view schematically showing the overall configuration of a vehicle equipped with a brake control device according to embodiment 1 of the present disclosure. The vehicle V shown in Fig. 1 is a four-wheel drive vehicle and includes a plurality of wheels W, an ECU (Electronic Control Unit) 1, a wheel braking unit 8, a brake pedal 10, a brake switch 12, a brake booster 14, a master cylinder 15, a first hydraulic line 16, an H / U (Hydraulic Unit) 17, a second hydraulic line 18, a hydraulic pump 19, a third hydraulic line 20, a hydraulic sensor 21, and a load sensor SE. The brake control device BC according to embodiment 1 of the present disclosure is configured by, for example, the wheel braking unit 8 and the ECU 1.

[0009] The wheel braking units 8 are provided on each of the plurality of wheels W, and each include a brake disc 8a and a brake caliper 8b. A load sensor SE is provided on each wheel W, and detects the load applied to each wheel W from the contact surface of each wheel W. The load sensor SE is disposed, for example, on a suspension of the vehicle V. The load sensor SE is electrically connected to the ECU 1.

[0010] The master cylinder 15 is connected to the H / U 17 via a first hydraulic pipe 16. Four second hydraulic pipes 18 and one third hydraulic pipe 20 are connected to the H / U 17. The four second hydraulic pipes 18 each connect the H / U 17 to the wheel braking unit 8. The third hydraulic pipe 20 connects the H / U 17 to a hydraulic pump 19. The master cylinder 15 is provided with a hydraulic pressure sensor 21. The hydraulic pressure sensor 21 detects the hydraulic pressure inside the master cylinder 15. The hydraulic pressure sensor 21 is electrically connected to the ECU 1.

[0011] A master cylinder 15 is connected to the brake pedal 10 via a brake booster 14. When the driver of the vehicle V depresses the brake pedal 10, hydraulic pressure corresponding to the amount of depression of the brake pedal 10 is generated in the master cylinder 15. The hydraulic pressure generated in the master cylinder 15 is supplied to each wheel braking unit 8 via a first hydraulic pipe 16, a H / U 17, and a second hydraulic pipe 18. This hydraulic pressure presses the brake pads against the brake discs 8a in the brake calipers 8b of each wheel braking unit 8, generating a frictional braking force, which is applied to the wheels W.

[0012] The drive of the hydraulic pump 19 is controlled by the ECU 1. By driving the hydraulic pump 19, the ECU 1 can supply hydraulic pressure to the wheel braking unit 8 even when the brake pedal 10 is not depressed.

[0013] The ECU 1 functions as an operation amount acquisition unit 100, a load acquisition unit 101, an identification unit 102, and a control unit 103. The operation amount acquisition unit 100 acquires the operation amount of an operation member operated by the driver of the vehicle V. The operation members include, for example, a brake pedal 10, an accelerator pedal, and a steering wheel.

[0014] The load acquisition unit 101 receives a detection signal from the load sensor SE to acquire the load applied to each wheel W from the contact surface of each wheel W. The identification unit 102 identifies, among the multiple wheels W, a wheel W for which the load acquired by the load acquisition unit 101 is relatively small. Hereinafter, the wheel W identified by the identification unit 102 will be referred to as a target wheel W.

[0015] The control unit 103 causes the wheel braking unit 8 corresponding to the target wheel W to apply a friction braking force to the target wheel W, thereby removing rust that has developed on the wheel braking unit 8 corresponding to the target wheel W. The rust that has developed on the wheel braking unit 8 is, for example, rust that has developed on the friction surface of the brake disc 8a. Hereinafter, the control that the control unit 103 performs to remove rust from the wheel braking unit 8 will be referred to as refresh control.

[0016] The refresh control will be described with reference to Figures 2 to 4. Figure 2 is a diagram used to explain the refresh control executed when the vehicle V accelerates. In the situation shown in Figure 2, the vehicle V is accelerated by a driving force A1 applied to the wheels W at an acceleration rate that does not cause squat. Squat refers to the state in which the front part of the vehicle lifts up and the rear part sinks when the vehicle suddenly starts moving.

[0017] In the state shown in Figure 2, the load on all wheels W of the vehicle V is approximately uniform, and the difference between the maximum and minimum loads on the wheels W is less than a predetermined value. The identification unit 102 identifies all wheels W of the vehicle V as target wheels W for refresh control. The control unit 103 supplies hydraulic pressure from the hydraulic pump 19 to all wheel brake units 8 of the vehicle V, applies frictional braking force B1 to all wheels W of the vehicle V, and removes rust that has occurred in all wheel brake units 8 of the vehicle V. The control unit 103 applies driving force A2 to all wheels W of the vehicle V to compensate for the reduction in the running force of the vehicle V caused by the refresh control.

[0018] FIG. 3 is a diagram used to explain the refresh control executed when the vehicle suddenly accelerates. In the situation shown in FIG. 3 , the vehicle V suddenly accelerates due to a driving force A1 applied to the wheels W, causing the front portion of the vehicle V to lift, and the load on the front portion becomes smaller than the load on the rear portion. The identification unit 102 identifies the left and right front wheels W of the wheels W of the vehicle V as target wheels W for the refresh control. The wheel brake units 8 of the left and right front wheels of the vehicle V are an example of a first wheel brake unit. The control unit 103 supplies hydraulic pressure from the hydraulic pump 19 to the wheel brake units 8 of the left and right front wheels, applying a frictional braking force B1 to the left and right front wheels and removing rust that has occurred in the wheel brake units 8 of the left and right front wheels. The control unit 103 applies a driving force A2 to the left and right rear wheels to compensate for the reduction in the running force of the vehicle V caused by the refresh control.

[0019] FIG. 4 is a diagram used to explain the refresh control executed when the accelerator pedal is released after sudden acceleration and the vehicle V is decelerating. In the situation shown in FIG. 4 , the vehicle V is decelerating after sudden acceleration, the rear portion of the vehicle V begins to lift, and the load on the rear portion is smaller than the load on the front portion. The identification unit 102 identifies the left and right rear wheels W of the vehicle V as target wheels W for the refresh control. The wheel brake units 8 of the left and right rear wheels of the vehicle V are an example of a second wheel brake unit. The control unit 103 supplies hydraulic pressure from the hydraulic pump 19 to the wheel brake units 8 of the left and right rear wheels, applying a frictional braking force B1 to the left and right rear wheels and removing rust that has occurred in the wheel brake units 8 of the left and right rear wheels. The control unit 103 applies a driving force A2 to the left and right front wheels to compensate for the reduction in the running force of the vehicle V caused by the refresh control.

[0020] The refresh control executed when the vehicle V is decelerating is equivalent to the refresh control executed when the vehicle V is accelerating or rapidly accelerating. More specifically, the friction braking force B1 applied to the left and right rear wheels in the refresh control executed when the vehicle V is decelerating is approximately the same as the friction braking force B1 applied to the left and right front wheels in the refresh control executed when the vehicle V is accelerating or rapidly accelerating.

[0021] 5 is a flowchart showing the flow of processing by the control unit. The ECU 1 repeatedly executes the processing of FIG. 5 while the vehicle V is traveling, and once the processing of FIG. 5 is completed, the ECU 1 starts the processing of the next cycle.

[0022] In S100, the ECU 1 determines whether the vehicle V is in an unstable state. The vehicle V being in an unstable state means, for example, when the vehicle is traveling at high speed, when the vehicle V is turning, when the vehicle V is traveling on a road surface with a small friction coefficient μ, etc. Here, the vehicle V being in a high speed means, for example, when the vehicle speed of the vehicle V is 80 km / h or higher. A road surface with a small friction coefficient μ is, for example, a snowy road. If the vehicle V is not in an unstable state (S100: NO), the ECU 1 proceeds to processing S110, and if the vehicle V is in an unstable state (S100: YES), the ECU 1 proceeds to processing S190.

[0023] In S110, the ECU 1 determines whether the vehicle speed of the vehicle V is equal to or less than a predetermined threshold value. Here, the threshold value is the vehicle speed during creeping, for example, 5 to 10 km / h. If the vehicle speed of the vehicle V is greater than the predetermined threshold value (S110: NO), the ECU 1 proceeds to the processing of S120. If the vehicle speed of the vehicle V is equal to or less than the predetermined threshold value (S110: YES), the ECU 1 proceeds to the processing of S190.

[0024] In S120, the ECU 1 determines whether the temperature of the brake pads of the brake caliper 8b is low. The ECU 1 estimates the temperature of the brake pads of the brake caliper 8b based on, for example, the number of control operations of the refresh control and the number of braking operations by the wheel braking unit 8. The ECU 1 determines that the temperature of the brake pads of the brake caliper 8b is low if the estimated temperature of the brake pads of the brake caliper 8b is equal to or lower than a predetermined value. If the temperature of the brake pads of the brake caliper 8b is low (S120: YES), the ECU 1 proceeds to the processing of S130, and if the temperature of the brake pads of the brake caliper 8b is not low (S120: NO), the ECU 1 proceeds to the processing of S190.

[0025] In S130, the ECU 1 determines whether the accelerator pedal has been operated. For example, the ECU 1 acquires the accelerator pedal operation amount using the operation amount acquisition unit 100, and determines whether the accelerator pedal has been operated based on the acquired operation amount. If the accelerator pedal has been operated (S130: YES), the ECU 1 proceeds to processing S140, and if the accelerator pedal has not been operated (S130: NO), the ECU 1 proceeds to processing S150.

[0026] In S140, the ECU 1 determines whether the load on the front wheels of the vehicle V acquired by the load acquisition unit 101 is smaller by a predetermined value or more than the load on the rear wheels of the vehicle V. If the load on the front wheels of the vehicle V is smaller by a predetermined value or more than the load on the rear wheels of the vehicle V (S140: YES), for example, in the situation described using Fig. 3, the ECU 1 proceeds to the processing of S160, and if the load on the front wheels of the vehicle V is not smaller by a predetermined value or more than the load on the rear wheels of the vehicle V, that is, if the load on the front wheels of the vehicle V is substantially the same as the load on the rear wheels of the vehicle V, the ECU 1 proceeds to the processing of S170.

[0027] In S160, the ECU 1 performs refresh control to apply a friction braking force B1 to the left and right front wheels of the vehicle V and a driving force A2 to the left and right rear wheels, as shown in Fig. 3. In S170, the ECU 1 performs refresh control to apply a friction braking force B1 to all wheels W of the vehicle V and a driving force A2 to all wheels W of the vehicle V, as shown in Fig. 2.

[0028] In S150, the ECU 1 determines whether the accelerator pedal is released immediately after the vehicle V accelerates. If a predetermined time has not elapsed since the accelerator pedal was released after the vehicle V accelerated (S150: YES), the ECU 1 proceeds to the processing of S180. If a predetermined time has elapsed since the vehicle V accelerated (S150: NO), the ECU 1 proceeds to the processing of S190.

[0029] In S180, the ECU 1 performs refresh control to apply a friction braking force B1 to the left and right rear wheels of the vehicle V and a driving force A2 to the left and right front wheels, as shown in Fig. 4. In S190, the ECU 1 does not perform refresh control.

[0030] [Embodiment 2] Embodiment 2 of the present disclosure will be described below. For ease of explanation, components having the same functions as those described in embodiment 1 will be denoted by the same reference numerals, and their descriptions will not be repeated. Embodiment 2 of the present disclosure differs from embodiment 1 in that the vehicle V is a front-engine, front-drive (FF) vehicle. In embodiment 2, the rear wheels of the vehicle V are driven wheels, and therefore, driving force A2 cannot be applied to the left and right rear wheels of the vehicle V. Therefore, embodiment 2 differs from embodiment 1 in that driving force A2 is applied only to the left and right front wheels of the vehicle V in the refresh control performed when the vehicle V accelerates and in the refresh control performed when the vehicle rapidly accelerates.

[0031] [Embodiment 3] A second embodiment of the present disclosure will be described below. For ease of explanation, components having the same functions as those described in the first and second embodiments will be denoted by the same reference numerals, and their descriptions will not be repeated. The third embodiment of the present disclosure differs from the first and second embodiments in that the vehicle V is a front-engine, rear-drive (FR) vehicle. In the third embodiment, the front wheels of the vehicle V are driven wheels, and therefore the driving force A2 cannot be applied to the left and right front wheels of the vehicle V. Therefore, the third embodiment differs from the first and second embodiments in that the driving force A2 is applied only to the left and right rear wheels of the vehicle V in the refresh control performed when the vehicle V accelerates and when the accelerator pedal is released after rapid acceleration of the vehicle V.

[0032] (Modification) In the above embodiment, when the accelerator pedal is released after sudden acceleration of the vehicle V and the vehicle V is decelerating, a frictional braking force B1 is applied to the left and right rear wheels and a driving force A2 is applied to the left and right front wheels, as shown in Fig. 4. However, the situation in which a frictional braking force B1 is applied to the left and right rear wheels and a driving force A2 is applied to the left and right front wheels is not limited to when the accelerator pedal is released after sudden acceleration of the vehicle V and the vehicle V is decelerating. For example, when the brake pedal 10 of the vehicle V is operated and the vehicle V is decelerating, a frictional braking force B1 may be applied to the left and right rear wheels and a driving force A2 may be applied to the left and right front wheels.

[0033] In the above embodiment, the vehicle V is described as being four-wheel drive, front engine / front drive, or front engine / rear drive, but the vehicle V is not limited to these. For example, the vehicle V may be a rear engine / rear drive or a rear engine / front drive vehicle.

[0034] In the above embodiment, the ECU 1 makes the determination in S140 of FIG. 5 based on the load on the wheels W of the vehicle V acquired by the load acquisition unit 101. However, this is not limiting. For example, the ECU 1 may make the determination in S140 of FIG. 5 based on the accelerator pedal depression amount. For example, the ECU 1 may determine that the vehicle V is rapidly accelerating when the accelerator pedal depression amount is equal to or greater than a predetermined value, or when the rate at which the accelerator pedal depression amount is increasing is equal to or greater than a predetermined value. For example, in S140, the ECU 1 may proceed to processing in S160 when the accelerator pedal depression amount is equal to or greater than the predetermined value, and may proceed to processing in S170 when the accelerator pedal depression amount is less than the predetermined value. The determination that the vehicle V is rapidly decelerating may be based, for example, on the rate at which the accelerator pedal depression amount decreases due to a sudden accelerator release from a state in which the accelerator pedal depression amount is equal to or greater than a predetermined value.

[0035] In the above embodiment, the load obtaining unit 101 obtains the load applied to each wheel W from the contact surface of each wheel W by receiving a detection signal from the load sensor SE, but this is not limiting. For example, the load obtaining unit 101 may obtain an estimated value of the load on each wheel W based on an actual value or an estimated value of a longitudinal G sensor or a wheel speed sensor of the vehicle V.

[0036] In the above embodiment, the refresh control executed when the vehicle V is decelerating is equivalent to the refresh control executed when the vehicle V is accelerating or rapidly accelerating. However, the refresh control executed when the vehicle V is accelerating or rapidly accelerating may be equivalent to the refresh control executed when the vehicle V is decelerating. The friction braking force B1 applied to the left and right front wheels in the refresh control executed when the vehicle V is accelerating or rapidly accelerating may be substantially the same as the friction braking force B1 applied to the left and right rear wheels in the refresh control executed when the vehicle V is decelerating.

[0037] [Summary] A braking control device according to one aspect of the present disclosure is applied to a vehicle having multiple wheels, and includes: multiple wheel braking units provided on each of the multiple wheels and applying a frictional braking force to each of the multiple wheels; an identification unit that identifies a wheel among the multiple wheels with a relatively light load; and a control unit that controls the wheel identified by the identification unit as a target wheel to apply the frictional braking force to the target wheel in order to remove rust that has occurred in the wheel braking unit corresponding to the target wheel. When applying braking force to a wheel, if braking force is applied when there is a large external disturbance occurring to the wheel, i.e., when the load occurring on the wheel is large, uneven wear of the braking member may occur. According to the above embodiment, the load acquisition unit acquires the load of each wheel, the identification unit identifies a wheel with a relatively light load based on the acquired load, and the control unit designates the wheel identified by the identification unit as a target wheel for control, and activates the wheel braking unit of the target wheel to remove rust. This allows rust removal to be performed on wheels that are under relatively light load and in a stable state, such as the front wheels when the vehicle is accelerating and the rear wheels when it is decelerating, thereby reducing uneven wear of the braking members that occurs when the braking force is applied as described above.

[0038] In a braking control device according to one aspect of the present disclosure, when the vehicle is accelerating, the identification unit identifies a front wheel of the vehicle as the wheel with a relatively light load, and the control unit causes the first wheel braking unit to apply the friction braking force to the front wheel to remove rust that has occurred in the first wheel braking unit, which is the wheel braking unit corresponding to the front wheel. When the vehicle is accelerating, the front wheel side of the vehicle may lift up. In the above embodiment, braking force is applied to a wheel that is less susceptible to external disturbances when the vehicle is accelerating, thereby reducing uneven wear of the braking member that occurs when applying braking force to remove rust.

[0039] In a braking control device according to one aspect of the present disclosure, when the vehicle is decelerating, the identification unit identifies the rear wheels of the vehicle as the wheels with a relatively small load, and the control unit causes the second wheel braking unit to apply the friction braking force to the rear wheels to remove rust that has occurred in the second wheel braking unit, which is the wheel braking unit corresponding to the rear wheels. When the vehicle is decelerating, the front wheels of the vehicle may sink and the rear wheels of the vehicle may rise. In the above embodiment, braking force is applied to wheels that are less susceptible to external disturbances when the vehicle is decelerating, thereby reducing uneven wear of the braking members that occurs when braking force is applied to remove rust.

[0040] In a brake control device according to one aspect of the present disclosure, the control unit sets the braking force of the control performed to remove rust that has occurred in the second wheel braking portion when the vehicle decelerates to be equal to the braking force of the control performed to remove rust that has occurred in the first wheel braking portion when the vehicle accelerates. Because the control performed to remove rust that has occurred in the second wheel braking portion when the vehicle decelerates and the control performed to remove rust that has occurred in the first wheel braking portion when the vehicle accelerates are equal controls, the control to remove rust can be performed evenly on the wheel braking portions of the vehicle.

[0041] [Additional Notes] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present disclosure.

Claims

1. A braking control device applied to a vehicle having a plurality of wheels, comprising: a plurality of wheel braking units provided on each of the plurality of wheels and applying a frictional braking force to each of the wheels; an identification unit that identifies a wheel among the plurality of wheels with a relatively light load; and a control unit that sets the wheel identified by the identification unit as having a relatively light load as a target wheel, and causes the wheel braking unit to apply the frictional braking force to the target wheel in order to remove rust that has occurred in the wheel braking unit corresponding to the target wheel.

2. A braking control device as described in claim 1, wherein the identification unit identifies the front wheel of the vehicle as the wheel with a relatively small load when the vehicle is accelerating, and the control unit causes the first wheel braking unit to apply the frictional braking force to the front wheel in order to remove rust that has occurred in the first wheel braking unit, which is the wheel braking unit corresponding to the front wheel.

3. A braking control device as described in claim 2, wherein the identification unit identifies the rear wheel of the vehicle as the wheel with a relatively small load when the vehicle is decelerating, and the control unit causes the second wheel braking unit to apply the frictional braking force to the rear wheel in order to remove rust that has occurred in the second wheel braking unit, which is the wheel braking unit corresponding to the rear wheel.

4. A braking control device as described in claim 3, wherein the control unit makes the braking force of the control performed to remove rust that has occurred in the second wheel braking unit when the vehicle decelerates equal to the braking force of the control performed to remove rust that has occurred in the first wheel braking unit when the vehicle accelerates.

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