JP7338492B2 - vehicle braking controller - Google Patents

Description

The present disclosure relates to a vehicle braking control device.

Patent Literature 1 describes the following for the purpose of "accurately and quickly detecting rear wheel lifting in a two-wheeled vehicle". "A simulated vehicle body speed is generated by selecting the larger one of the wheel speeds Vf and Vr of the front wheels and the rear wheels, focusing on the simulated vehicle body deceleration calculated based on the simulated vehicle body speed, and reducing the simulated vehicle body deceleration. When the degree of deceleration is greater than or equal to a predetermined value, it is determined that the rear wheels are floating. (A) When the first condition that the simulated vehicle body deceleration is reduced by a predetermined amount or more is satisfied, and the second condition that the first condition continues for a predetermined period of time or more is satisfied.( B) When satisfying the third condition that the simulated vehicle body deceleration decreases to a predetermined level or more within a predetermined period of time.

In Patent Document 2, for the purpose of "providing a brake control device for a motorcycle that can improve the accuracy of determining rear wheel lift while maintaining the accuracy of ABS control," the control device 20A Front wheel speed acquisition means 21 for acquiring speed, rear wheel speed acquisition means 22 for acquiring rear wheel speed, and estimated vehicle speed calculation means for calculating an estimated vehicle speed using the front wheel speed and rear wheel speed 23, estimated vehicle body deceleration calculation means 24 for calculating estimated vehicle body deceleration using only the front wheel speed as a speed element, and ABS control for suppressing slip during braking of the front and rear wheels based on the estimated vehicle body speed. means 25; rear wheel lift determination means 26 for determining that there is a risk of at least rear wheel lift when the state in which the estimated vehicle deceleration is higher than the reference deceleration continues for a reference time or longer; and at least the rear wheels. and front wheel braking force control means 27 for reducing the braking force of the front wheels when it is determined that there is a risk of lifting.”

In Patent Document 3, the object is to "provide a brake control device for a vehicle capable of suppressing unnecessary reduction of the brake pressure of the front wheel brake for suppressing the lifting of the rear wheel." "The electronic control unit 40, which is a component of the brake control device of the motorcycle, includes a filter processing unit 44 that outputs a value obtained by filtering the output GX of the acceleration sensor 41, and a filter a pressure reduction control unit 42 that performs pressure reduction control to reduce the brake pressure of the front wheel brake 10 when the vehicle body deceleration indicated by the filter value, which is the output value of the processing unit 44, becomes equal to or greater than a prescribed lift-up determination value; In the electronic control unit 40 of such a brake control device, when the rate of increase in vehicle deceleration indicated by the output value of the filter processing section 44 is equal to or greater than a specified value, the lift is higher than when the rate of increase is less than the specified value. It includes a judgment value setting unit 45 that sets the judgment value to a large value."

In Patent Documents 1 and 2, the vehicle body speed is calculated based on the wheel speed, and the vehicle body deceleration (hereinafter referred to as "calculated deceleration Ge") is calculated based on the vehicle body speed. However, when the rear wheel lift suppression control is required, the vehicle is being braked suddenly, and the wheel speed includes wheel slip (slip in the direction of rotation of the wheel, also called "deceleration slip"). include. Here, the error caused by the deceleration slip is called "slip error".

The applicant has developed a braking control device as shown in Patent Document 3, which has a deceleration sensor for detecting vehicle deceleration. Hereinafter, the vehicle body deceleration detected by the deceleration sensor is referred to as "detected acceleration Gx". Since the detected deceleration Gx does not include the influence of deceleration slip, the rear wheel lift suppression control executed according to the detected deceleration Gx is not affected by the slip error. However, the detected deceleration Gx contains an error due to the gradient of the road surface. The error is called the "slope error".

In a braking control device for a vehicle that executes rear wheel lift suppression control, it is desired to reduce the effects of the above two errors.

Japanese Patent Application Laid-Open No. 2002-029403 Japanese Patent Application Laid-Open No. 2007-269290 JP 2017-105397 A

SUMMARY OF THE INVENTION It is an object of the present invention to provide a braking control device for a vehicle that executes rear wheel lift suppression control for suppressing lift of the rear wheels, in which the effects of slip error and gradient error can be preferably compensated for.

A braking control device (SC) for a vehicle according to the present invention executes rear wheel lift suppression control for suppressing lift of a rear wheel (WHr) of a vehicle, and is configured to detect deceleration of the vehicle ( Gx),” a “wheel speed sensor (VW) that detects the rotational speed of the wheel (WH) of the vehicle as a wheel speed (Vw),” and “a front wheel (WHf ), and a controller (ECU) that controls the actuator (HU) based on the detected deceleration (Gx) and the wheel speed (Vw). And prepare.

In the braking control device (SC) for a vehicle according to the present invention, the controller (ECU) controls that "the calculated deceleration (Ge), which is the deceleration of the vehicle calculated based on the wheel speed (Vw), is the first When the state of the threshold value (gx1) or more continues for the determination time (ta), the execution of the rear wheel lift suppression control is determined and the first actuation instruction (Hn1=1) is output. Determination unit (HN1) ”, and ``calculated deceleration ( Ge) is a reference deceleration (gs), and the reference deceleration (gs) is sequentially integrated with the time change amount (dGx) of the detected deceleration (Gx) to calculate the integrated deceleration (Gs), and the integrated A second determination unit (HN2 )”, and when either one of the first actuation instruction (Hn1=1) and the second actuation instruction (Hn2=1) is output, the front wheel (WHf) is braked. Decrease power (Fxf).

The first actuation instruction requires time to determine the necessity of the rear wheel lift suppression control, but is less susceptible to slope errors and the like. On the other hand, the second actuation instruction is affected by slope errors and the like, but it is possible to determine in a short time whether or not the rear wheel lift suppression control is necessary. According to the above configuration, since the execution of the rear wheel lift suppression control is started when one of the two operation instructions is output, the effects of the wheel slip error and the road gradient error are minimized. can be suitably compensated.

1 is an overall configuration diagram for explaining a first embodiment of a braking control device SC according to the present invention; FIG. FIG. 3 is a block diagram for explaining arithmetic processing of rear wheel lift suppression control; FIG. 10 is a time-series diagram for explaining processing in a first decision block HN1; FIG. 11 is a time-series diagram for explaining processing in a second decision block HN2; FIG. 2 is an overall configuration diagram for explaining a second embodiment of a braking control device SC according to the present invention;

<Symbols of component parts, etc., subscripts at the end of the symbol>
In the following description, constituent members, arithmetic processing, signals, characteristics, and values denoted with the same symbols such as "CW" have the same function. The suffixes "f" and "r" attached to the end of various symbols are generic symbols that indicate which of them relates in the longitudinal direction of the vehicle. Specifically, "f" indicates the front wheel, and "r" indicates the rear wheel. For example, the wheels are expressed as a front wheel WHf and a rear wheel WHr. Furthermore, the subscripts "f" and "r" at the end of the symbol may be omitted. When the subscripts "f" and "r" are omitted, each symbol represents its generic name. For example, "CWf" represents the front wheel cylinder, "CWr" represents the rear wheel cylinder, and "CW" represents the front and rear wheel cylinders. In addition, in the connecting path HS, the side closer to the master cylinder CM is called "upper", and the side closer to the wheel cylinder CW is called "lower".

<First embodiment of braking control device SC according to the present invention>
A first embodiment of a vehicle braking control device SC according to the present invention will be described with reference to the overall configuration diagram of FIG. A motorcycle (also referred to as a "motorcycle") is assumed as the vehicle. A vehicle employs two fluid paths (that is, two braking systems). In one of the two braking systems, a front wheel master cylinder CMf is connected to a front wheel cylinder CWf via a front wheel connection path HSf. In the other of the two braking systems, a rear wheel master cylinder CMr is connected to a rear wheel cylinder CWr via a rear wheel connection path HSr. Here, the front wheel and rear wheel connection paths HSf and HSr (=HS) are fluid paths. A "fluid path" is a path for moving the brake fluid BF, which is the working fluid, and corresponds to a brake pipe, a flow path of the fluid unit HU, a hose, and the like.

A vehicle equipped with the brake control device SC is equipped with brake operation members BP (=BPf, BPr), wheel cylinders CW (=CWf, CWr), and master cylinders CM (=CMf, CMr).

The braking operation member BP is a member operated by the driver to decelerate the vehicle. For example, a brake lever is employed as the front wheel braking operating member BPf, and a brake pedal is employed as the rear wheel braking operating member BPr. be. By operating the braking operation member BP, the hydraulic pressures (front and rear wheel cylinder hydraulic pressures) Pwf and Pwr in the front and rear wheel cylinders CWf and CWr (=CW) are adjusted. As a result, the front and rear wheel braking torques Tqf and Tqr (=Tq) are adjusted to generate front and rear wheel braking forces Fxf and Fxr (=Fx). Here, the front and rear wheel cylinder hydraulic pressures Pwf and Pwr are also referred to as "front and rear wheel braking hydraulic pressures Pwf and Pwr (=Pw)".

Front and rear wheel rotary members KTf and KTr (=KT) are fixed to wheels WH (=WHf and WHr) of the vehicle. Front and rear wheel brake calipers CPf and CPr (=CP) are arranged so as to sandwich the rotating member KT (for example, brake disc). The brake caliper CP is provided with a wheel cylinder CW, and a friction member (for example, a brake pad) is pressed against the rotating member KT by increasing the pressure (brake fluid pressure) Pw of the brake fluid BF inside the brake caliper CP. . Since the rotating member KT and the wheels WH are fixed so as to rotate integrally, braking torque Tq is generated in the wheels WH by the frictional force generated at this time. This braking torque Tq produces a braking force Fx on the wheels WH.

Front and rear wheel hydraulic pressure chambers Rmf and Rmr (=Rm) are formed inside the front and rear wheel master cylinders CMf and CMr (=CM). When the brake operating member BP is operated, the volume of the hydraulic pressure chamber Rm is reduced, and the brake fluid BF is pressure-fed from the hydraulic pressure chamber Rm to the wheel cylinder CW via the connecting passage HS. That is, the hydraulic pressure Pw of the wheel cylinder CW is increased by the hydraulic pressure Pm of the master cylinder CM (referred to as "master cylinder hydraulic pressure").

Furthermore, the vehicle is equipped with front wheel and rear wheel speed sensors VWf and VWr (=VW), and a longitudinal acceleration sensor (also referred to as a "deceleration sensor") GX. A wheel speed sensor VW provided for each wheel WH detects front and rear wheel speeds Vwf and Vwr (=Vw). A deceleration sensor GX provided in the body of the vehicle detects acceleration Gx in the longitudinal direction (traveling direction) of the vehicle (longitudinal acceleration, also referred to as "detected deceleration"). Signals of the wheel speed Vw and the detected deceleration Gx are used for antilock brake control that suppresses the locking tendency of the wheels WH (that is, excessive deceleration slip), rear wheel lift suppression control that suppresses lift-up of the rear wheels WHr, and the like. used for braking force control. The wheel speed Vw and longitudinal acceleration (detected deceleration) Gx detected by each sensor (VW, etc.) are input to a brake controller ECU (also simply referred to as "controller").

≪Brake controller ECU≫
The brake control device SC includes a brake controller ECU and a fluid unit HU. A brake controller (also called an "electronic control unit") ECU consists of an electric circuit board on which a microprocessor or the like is mounted, and a control algorithm (rear wheel lift control, etc.) programmed in the microprocessor.

Since the center of gravity of the vehicle is higher than the road surface, sudden braking reduces the load on the rear wheels WHr, and in extreme cases, the rear wheels WHr leave the road surface (“rear wheel lift” or “rear wheel lift”). wheel lift-up") may occur. The "rear wheel lift suppression control" suppresses the rear wheel lift by reducing the front wheel braking force Fxf based on the wheel speed Vw and the detected deceleration Gx. The rear wheel lift suppression control is an algorithm programmed in the controller ECU.

A braking controller ECU (electronic control unit) controls (drives) the electric motor MT of the hydraulic unit HU and the solenoid valves VI and VO. Specifically, drive signals Vi and Vo for controlling the solenoid valves VI and VO are calculated based on a control algorithm in the microprocessor. Similarly, a drive signal Mt for controlling the electric motor MT is calculated.

The controller ECU is provided with drive circuits to drive the solenoid valves VI, VO and the electric motor MT. In the drive circuit, a bridge circuit is formed by switching elements (power semiconductor devices such as MOS-FETs and IGBTs) so as to drive the electric motor MT. Based on the motor drive signal Mt, the energization state of each switching element is controlled, and the output of the electric motor MT is controlled. Further, in the drive circuit, the switching elements are driven based on the drive signals Vi and Vo, and the energized state (that is, the excited state) of the solenoid valves VI and VO is controlled. The drive circuit is provided with energization amount sensors for detecting actual energization amounts of the electric motor MT and the solenoid valves VI and VO. For example, a current sensor is provided as the energization amount sensor to detect the current supplied to the electric motor MT and the solenoid valves VI and VO.

≪Fluid unit HU≫
The fluid unit HU is an actuator that individually controls the braking force Fx of the wheels WH. The front and rear wheel hydraulic chambers Rmf and Rmr of the front and rear wheel master cylinders CMf and CMr and the front and rear wheel cylinders CWf and CWr are defined as the front and rear wheel connection paths (fluid paths) HSf and HSr (=HS). ) are connected. A fluid unit HU is provided between the master cylinder CM and the wheel cylinder CW in the connection path HS. The fluid unit HU is composed of an inlet valve VI, an outlet valve VO, an electric motor MT, a fluid pump HP and a low pressure reservoir RW.

The front wheel and rear wheel inlet valves VIf and VIr (=VI) are normally open solenoid valves (for example, on/off valves) that close when energized. The inlet valve VI is provided in the middle of the connecting path HS. The inlet valve VI is controlled based on a drive signal Vi from the controller ECU. Inlet valve VI permits the movement of brake fluid BF between wheel cylinder CW and master cylinder CM through connection path HS when the valve is open, and blocks it when the valve is closed.

In the connecting passage HS, between the inlet valve VI and the wheel cylinder CW (that is, below the inlet valve VI), one end of each of the front wheel and rear wheel return passages HRf and HRr (=HR), which is a fluid passage, is provided. Connected. The other end of the return path HR is "front wheels, rear wheels RWf, RWr (=RW)" and "in the connection path HS, between the master cylinder CM and the inlet valve VI (that is, the upper part of the inlet valve VI )”. In other words, the return path HR is a fluid path that connects the upper portion of the inlet valve VI and the lower portion of the inlet valve VI at the connection path HS so as to bypass the inlet valve VI.

The front and rear wheel outlet valves VOf and VOr (=VO) are normally closed electromagnetic valves (for example, on/off valves) that open when energized. The outlet valve VO is provided in the return path HR. The outlet valve VO is controlled based on a drive signal Vo from the controller ECU. The outlet valve VO permits the movement of the brake fluid BF from the wheel cylinder CW to the master cylinder CM side through the return path HR when the valve is open, and blocks it when the valve is closed.

Front and rear wheel fluid pumps HPf and HPr (=HP) are provided in front and rear wheel return paths HRf and HRr (=HR). A low pressure reservoir RW is also connected to the return path HR. In particular, the fluid pump HP is provided between the outlet valve VO and the "connection between the connection HS and the return HR at the top of the inlet valve VI". A low pressure reservoir RW is also connected to the return line HR between the outlet valve VO and the fluid pump HP.

The two fluid pumps HP are driven by one electric motor MT. The electric motor MT is controlled based on a drive signal Mt from the braking controller ECU. The fluid pump HP pumps the brake fluid BF from the low pressure reservoir RW or the wheel cylinder CW and returns it to the upper part of the inlet valve VI (for example, the hydraulic pressure chamber Rm of the master cylinder CM).

In order to reduce the hydraulic pressure (braking hydraulic pressure) Pw in the wheel cylinder CW by antilock brake control or rear wheel lifting suppression control, the inlet valve VI is closed and the outlet valve VO is opened. be. Inflow of the brake fluid BF from the inlet valve VI is blocked, the brake fluid BF in the wheel cylinder CW flows out to the low pressure reservoir RW, and the brake fluid pressure Pw is reduced. In order to increase the braking fluid pressure Pw, the inlet valve VI is opened and the outlet valve VO is closed. The brake fluid BF is prevented from flowing out to the low-pressure reservoir RW, the hydraulic pressure of the master cylinder CM (master cylinder hydraulic pressure) Pm is introduced into the wheel cylinder CW, and the brake hydraulic pressure Pw is increased. Furthermore, both the inlet valve VI and the outlet valve VO are closed to maintain the hydraulic pressure (brake hydraulic pressure) Pw in the wheel cylinder CW. That is, by controlling the solenoid valves VI and VO, the braking hydraulic pressure Pw (that is, the braking torque Tq, and as a result, the braking force Fx) can be adjusted independently by the wheel cylinder CW of each wheel WH. .

<Arithmetic Processing of Rear Wheel Float Suppression Control>
Arithmetic processing of the rear wheel lift suppression control will be described with reference to the block diagram of FIG. The rear wheel lift suppression control is performed by a calculation deceleration calculation block GE, an integrated deceleration calculation block GS, a first determination block HN1 (corresponding to the "first determination section"), and a second determination block HN2 (corresponding to the "second determination section"). equivalent), and a braking force adjustment block FX. In addition, in the calculated deceleration Ge, the detected deceleration Gx, and the integrated deceleration Gs, which will be described below, the value on the side of decelerating the vehicle is represented by a "plus sign (+)".

In the calculated deceleration calculation block GE, the calculated deceleration Ge is calculated based on the wheel speed Vw. Specifically, in the calculation deceleration calculation block GE, first, the vehicle body speed Vx is calculated based on the faster one of the front wheel speed Vwf and the rear wheel speed Vwr. In the calculation of the vehicle body speed Vx, a limit may be placed on the amount of change over time. That is, the upper limit value αup of the increasing gradient of the vehicle speed Vx and the lower limit value αdn of the decreasing gradient of the vehicle speed Vx are set, and the change in the vehicle speed Vx is restricted by the upper and lower limit values αup and αdn. Next, the vehicle body speed Vx is time-differentiated to calculate the calculated deceleration Ge. That is, in the calculated deceleration calculation block GE, the vehicle body speed Vx is calculated based on the wheel speed Vw, and the calculated deceleration Ge is calculated based on the vehicle body speed Vx. The calculated deceleration Ge is the deceleration of the vehicle (vehicle body) for performing the first determination described later. The calculated deceleration Ge calculated by the calculated deceleration calculation block GE is input to the integrated deceleration calculation block GS in addition to the first determination block HN1.

An integrated deceleration calculation block GS calculates an integrated deceleration Gs based on the detected deceleration Gx and the calculated deceleration Ge. The calculated deceleration Ge is the deceleration of the vehicle (vehicle body) for performing the second determination described later. First, the integrated deceleration calculation block GS acquires the detected deceleration Gx from the deceleration sensor GX. Specifically, in the controller ECU, the output (detection signal) of the deceleration sensor GX, which is an analog signal, is converted into a digital signal by an analog/digital conversion circuit. Then, the output of the deceleration sensor GX after analog/digital conversion is filtered to acquire (determine) the detected deceleration Gx.

Next, in the integrated deceleration calculation block GS, an integrated deceleration Gs is calculated based on the detected deceleration Gx and the calculated deceleration Ge. A method of calculating the integrated deceleration Gs will be described below (see (A) and (B) below).

(A) A time change amount dGx of the detected deceleration Gx and a time change amount dGe of the calculated deceleration Ge are calculated. It is determined whether or not the amount of change over time dGx and the amount of change over time dGe match. Then, the calculated deceleration Ge when the time variation dGx and the time variation dGe match is determined as the reference deceleration gs. Here, the time change amount dGx is also called a "detected gradient" and is a time differential value of the detected deceleration Gx. The time change amount dGe is also referred to as "calculated gradient" and is a time differential value of the calculated deceleration Ge.

For example, the above determination is made when "a deviation (also referred to as a 'gradient deviation') hG between the detected gradient dGx and the calculated gradient dGe has become less than a predetermined amount hx". Here, the predetermined amount hx is a preset predetermined value (constant). Furthermore, "matching between detected gradient dGx and calculated gradient dGe" is defined as "a point in time (corresponding calculation cycle)”. Here, the reference time tx is a preset predetermined value (constant). In any case, the reference deceleration gs is the calculated deceleration Ge when the detected gradient dGx and the calculated gradient dGe match.

(B) The integrated deceleration Gs is calculated by sequentially adding the time change amount (detected gradient) dGx of the detected deceleration Gx to the reference deceleration gs at each calculation cycle. That is, in the calculation cycle next to the calculation cycle in which the reference deceleration gs is set (determined), the integrated deceleration Gs is calculated by the following equation (1). In the following equations, [n] corresponds to the current calculation cycle, and [n-1] indicates the state quantity (variable) corresponding to the previous calculation cycle.
Gs[n]=gs+dGx[n] Expression (1)

After the first integrated deceleration Gs is calculated, the detected gradient dGx[n] for the current computation cycle is added to the integrated deceleration Gs[n−1] for the previous computation cycle to obtain the integrated deceleration Gs[n]. is calculated. That is, as shown in equation (2), the detected gradient dGx[n] is added to the integrated deceleration Gs[n-1] in each computation cycle to compute the integrated deceleration Gs[n]. The integrated deceleration Gs calculated by the integrated deceleration calculation block GS is input to the second determination block HN2.
Gs[n]=Gs[n−1]+dGx[n] Expression (2)

<<First instruction Hn1>>
In the first determination block HN1 (first determination section), the first instruction Hn1 is calculated based on the calculated deceleration Ge and output to the braking force adjustment block FX. The first instruction Hn1 is a determination flag for "whether or not to instruct execution of the rear wheel lift suppression control". As for the first instruction Hn1, "0" represents an "instruction not to execute (stop instruction)", and "1" represents an "instruction to execute (operation instruction)". Here, "Hn1=0" is called "first stop instruction", and "Hn1=1" is called "first operation instruction".

In the first determination block HN1, first, it is determined whether or not an instruction to execute the rear wheel lift suppression control is given. For example, the determination is made based on whether "Hn1=1 (operation instruction)" or "Hn1=0 (stop instruction)". When "Hn1=0" and the execution of the rear wheel floating suppression control based on the calculated deceleration Ge is not instructed (the state of the first stop instruction), the next step is to determine the execution start instruction (" (referred to as "first start instruction") is performed. On the other hand, when "Hn1=1" and the execution of the rear wheel floating suppression control based on the calculated deceleration Ge is instructed (the state of the first actuation instruction), as the next step, an execution end instruction (" (referred to as "first end instruction") is performed.

The determination of "whether to start the rear wheel lift suppression control execution instruction or not" (determination of the first actuation instruction) is performed when the following start condition 1a is satisfied, the rear wheel lift suppression control execution instruction is started. be done. That is, the first instruction Hn1 output from the first determination block HN1 is switched from "0 (stop instruction)" to "1 (operation instruction)".
Start condition 1a: The state in which the calculated deceleration Ge is equal to or greater than the first start deceleration gx1 (corresponding to the "first threshold value") continues for the determination time ta. Here, the first start deceleration gx1 is a threshold value for the first start instruction, and is a preset predetermined value (constant). The determination time ta is a predetermined value (constant) longer than the reference time tx.
When the determination time ta (predetermined time) elapses from the time when "Ge≧gx1" is satisfied for the first time, and the start condition 1a is affirmative, "Hn1=1 (first operation instruction)" becomes the first determination. Output from block HN1. On the other hand, if "Ge<gx1" or "Ge≧gx1" but the determination time ta has not elapsed and the start condition 1a is denied, "Hn1=0 (first stop instruction)". is output from the first decision block HN1.

The determination of "whether or not to terminate the execution instruction of the rear wheel lift prevention control" (determination of the first stop instruction) terminates the execution instruction of the rear wheel lift prevention control when the following termination condition 1b is satisfied. It is determined that That is, the first instruction Hn1 output from the first determination block HN1 is switched from "1" to "0".
End condition 1b: The calculated deceleration Ge is less than the first end deceleration gz1. Here, the first termination deceleration gz1 is a threshold value for the first termination instruction, and is a preset predetermined value (constant). The first end deceleration gz1 is set as a value smaller than the first start deceleration gx1 (that is, "gx1>gz1").
When "Ge≧gz1" and the termination condition 1b is denied, "Hn1=1 (first operation instruction)" is output from the first determination block HN1. On the other hand, when "Ge<gz1" and the end condition 1b is affirmative, "Hn1=0 (first stop instruction)" is output from the first determination block HN1.

As a termination condition, the following termination condition 1c related to the vehicle body speed Vx may be added.
End condition 1c: Vehicle body speed Vx is less than first end speed vx1. Here, the first end speed vx1 is a predetermined value (constant) set in advance.
When the termination condition 1c is adopted, the output Hn1 from the first decision block HN1 when (at the time of satisfaction) any one of the termination condition 1b and the termination condition 1c is satisfied. is switched from "1 (operation instruction)" to "0 (stop instruction)". Therefore, only when both the termination condition 1b and the termination condition 1c are denied, the execution instruction (Hn1=1) of the rear wheel lift suppression control is continuously output.

<<Second instruction Hn2>>
A second instruction Hn2 is calculated in the second determination block HN2 (second determination section) based on the integrated deceleration Gs and output to the braking force adjustment block FX. Like the first instruction Hn1, the second instruction Hn2 is a determination flag for "whether or not to instruct the execution of the rear wheel lift suppression control". As for the second instruction Hn2, "0" represents an "instruction not to execute (stop instruction)", and "1" represents an "instruction to execute (operation instruction)". Here, "Hn2=0" is referred to as "second stop instruction", and "Hn2=1" is referred to as "second actuation instruction".

In the second determination block HN2, first, it is determined whether or not an instruction to execute rear wheel lift suppression control has been given. For example, the determination is made based on whether "Hn2=2 (operation instruction)" or "Hn2=0 (stop instruction)". When "Hn2=0" and the execution of the rear wheel floating suppression control based on the integrated deceleration Gs is not instructed (state of the second stop instruction), the next step is determination of the execution start instruction (" (referred to as "second actuation instruction") is performed. On the other hand, when "Hn2=1" and execution of the rear wheel floating suppression control based on the integrated deceleration Gs is instructed (state of the second actuation instruction), as the next step, an execution end instruction (" (referred to as "second stop instruction") is performed.

The determination of "whether to start the execution instruction of the rear wheel lift prevention control or not" (determination of the second start instruction) is performed when the following start condition 2a is satisfied, the execution instruction of the rear wheel lift prevention control is started. be done. That is, the second instruction Hn2 output from the second determination block HN2 is switched from "0 (stop instruction)" to "1 (operation instruction)".
Starting condition 2a: The cumulative deceleration Gs is greater than or equal to the second starting deceleration gx2. Here, the second start deceleration gx2 (corresponding to "second threshold") is a threshold for the second start instruction and is a predetermined value (constant) set in advance.
When "Gs≧gx2" and the start condition 2a is affirmative, "Hn2=1 (second actuation instruction)" is output from the second decision block HN2. On the other hand, when "Gs<gx2" and the start condition 2a is denied, "Hn2=0 (second stop instruction)" is output from the second determination block HN2.

The determination of "whether or not to terminate the execution instruction of the rear wheel lift prevention control" (determination of the second termination instruction) terminates the execution instruction of the rear wheel lift prevention control when the following termination condition 2b is satisfied. It is determined that That is, the second instruction Hn2 output from the second determination block HN2 is switched from "1" to "0".
End condition 2b: The cumulative deceleration Gs is less than the second end deceleration gz2. Here, the second termination deceleration gz2 is a threshold value for the second termination instruction, and is a preset predetermined value (constant). The second end deceleration gz2 is set as a value smaller than the second start deceleration gx2 (that is, "gx2>gz2").
When "Gs≧gz2" and the termination condition 2b is denied, "Hn2=1 (second operation instruction)" is output from the second determination block HN2. On the other hand, when "Gs<gz2" and the termination condition 2b is affirmative, "Hn2=0 (second stop instruction)" is output from the second determination block HN2.

As a termination condition, the following termination condition 2c related to the vehicle body speed Vx may be added.
End condition 2c: Vehicle speed Vx is less than second end speed vx2. Here, the second end speed vx2 is a predetermined value (constant) set in advance.
When the termination condition 2c is adopted, the output Hn2 from the second decision block HN2 when (at the time of satisfaction) any one of the termination condition 2b and the termination condition 2c is satisfied. is switched from "1" to "0". Therefore, only when both the end condition 2b and the end condition 2c are denied, the execution instruction (Hn2=1) of the rear wheel lift suppression control is continuously output.

The braking force adjustment block FX adjusts the front wheel braking force Fxf based on the first instruction Hn1 (first determination flag) and the second instruction Hn2 (second determination flag). Specifically, of the first instruction Hn1 and the second instruction Hn2, the one for which the execution of the rear wheel lift suppression control is instructed first (that is, the one for which the operation instruction is output first, Execution of the rear wheel lift suppression control is started based on the "advance instruction Hns"). That is, in the braking force adjustment block FX, when either one of the first actuation instruction (Hn1=1) and the second actuation instruction (Hn2=1) is output (corresponding calculation period), The braking force Fxf of the front wheels WHf is reduced.

For example, rather than transitioning the first instruction Hn1 from "0 (first stop instruction)" to "1 (first actuation instruction)", the second instruction Hn2 transitions from "0 (second stop instruction)" to "1 ( second actuation instruction)" is slow, the first instruction Hn1 (first actuation instruction) is the preceding instruction Hns. In this case, reduction of the front wheel braking force Fxf is started due to the actuation instruction of the first instruction Hn1. Conversely, when the transition from "0" to "1" of the second instruction Hn2 is earlier than the transition from "0" to "1" of the first instruction Hn1, the second instruction Hn2 (second operation instruction) is the preceding instruction Hns. In this case, the reduction of the front wheel braking force Fxf is started by the actuation instruction of the second instruction Hn2.

In the braking control device SC of FIG. 1, the front wheel braking force Fxf is obtained when the front wheel inlet valve VIf is in the closed position and the supply of the brake fluid BF pressurized to the front wheel master cylinder hydraulic pressure Pmf to the front wheel cylinder CWf is cut off. At the same time, when the front wheel outlet valve VOf is in the open position, the brake fluid BF in the front wheel cylinder CWf is reduced by flowing out to the front wheel low pressure reservoir RWf.

In the braking force adjustment block FX, based on the first instruction Hn1 or the second instruction Hn2, whichever corresponds to the side on which the rear wheel lift suppression control is started (that is, the preceding instruction Hns), the rear wheel Execution of the lift suppression control is ended, and the front wheel braking force Fxf is increased (for example, the brake hydraulic pressure Pw is increased by the master cylinder hydraulic pressure Pm). For example, when the rear wheel lift suppression control is started by the first actuation instruction (Hn1=1), the first instruction Hn1 is the preceding instruction Hns, and the second stop instruction (Hn2=0) is output first. Even if the first stop instruction (Hn1=0) is issued, the rear wheel lift suppression control is terminated. Conversely, when the rear wheel lift suppression control is started by the second actuation instruction (Hn2=1), the second instruction Hn2 is the preceding instruction Hns, and the first stop instruction (Hn1=0) is first. Even if it is output, the second stop instruction (Hn2=0) terminates the rear wheel lift suppression control.

In the braking control device SC of FIG. 1, the front wheel braking force Fxf is obtained by supplying the brake fluid BF pressurized to the front wheel master cylinder hydraulic pressure Pmf to the front wheel cylinder CWf when the front wheel inlet valve Vif is in the open position. In the closed position of the front wheel outlet valve VOf, the brake fluid BF in the front wheel cylinder CWf is increased by not flowing out to the front wheel low pressure reservoir RWf.

After the rear wheel floating suppression control is terminated, the integrated deceleration Gs is again calculated (the reference deceleration gs is determined and the detected gradient dGx is integrated), the first instruction Hn1 is calculated, and the second instruction is performed. Hn2 is calculated. Then, similarly to the execution of the previous rear wheel lift suppression control, when either the first operation instruction or the second operation instruction is output (that is, when the operation instruction is first output). At , the rear wheel lift suppression control is started, and the front wheel braking force Fxf is reduced. After that, the rear wheel lift suppression control is ended according to which of the first and second stop instructions corresponds to the preceding instruction Hns (determination result on the execution start side). After that, the calculation cycle is repeated until the vehicle stops or the vehicle body speed Vx becomes less than the predetermined speed vs.

<<Advantages/disadvantages of the first instruction Hn1>>
The first instruction Hn1 is determined (determined) based on the calculated deceleration Ge. Since the calculated deceleration Ge is calculated based on the wheel speed Vw, it is affected by the deceleration slip of the wheels WH (slip in the rotational direction of the wheels WH, which is the difference between the vehicle body speed Vx and the wheel speed Vw). In particular, when the rear wheel lift suppression control is executed, the deceleration slip is likely to increase because the braking is sudden with a large deceleration of the vehicle body. In order to identify whether the calculated deceleration Ge is caused by the deceleration slip of the wheels WH or by the deceleration of the vehicle body, the first instruction Hn1 is issued after a predetermined determination time ta has passed. determined from. This is based on the fact that when the calculated deceleration Ge is caused by a deceleration slip, the calculated deceleration Ge, which has once decreased, is increased again by executing the antilock brake control. Since the above identification requires a relatively long determination time ta (predetermined value), the first actuation instruction (Hn1=1) is delayed, and the start of rear wheel lift suppression control is delayed. There is In other words, it is difficult for the front wheel braking force Fxf to decrease quickly. On the other hand, since the first instruction Hn1 does not use the detected deceleration Gx, it is not affected by the error of the deceleration sensor GX (zero point drift, road gradient error, etc.). Therefore, the calculated deceleration Ge can start the execution of the rear wheel lift suppression control at the intended deceleration of the vehicle.

<<Advantages/disadvantages of the second instruction Hn2>>
The detected deceleration Gx includes a zero-point drift error, but the detected gradient dGx is an amount of change with respect to time T, and therefore does not include a zero-point drift error. Therefore, the integrated deceleration Gs, which is obtained by sequentially accumulating the detected gradient dGx for each calculation cycle, is not affected by the zero point drift of the deceleration sensor GX. Furthermore, the integrated deceleration Gs is calculated by using the calculated deceleration Ge when the detected gradient dGx and the calculated gradient dGe match as a reference value (reference deceleration) gs, and then integrating the detected gradient dGx. , is not affected by the deceleration slip of the wheels WH. The reference time tx used to determine the reference deceleration gs can be set shorter than the determination time ta.

Therefore, on a road that is less affected by the road surface gradient (for example, a flat road), the second actuation instruction (Hn2=1) based on the integrated deceleration Gs is higher than the first actuation instruction (Hn1=1) based on the calculated deceleration Ge. is also done early. Therefore, the second actuation instruction (Hn2=1) based on the integrated deceleration Gs is issued earlier than the first actuation instruction (Hn1=1) based on the calculated deceleration Ge. That is, in the rear wheel lift suppression control, the front wheel braking force Fxf can be quickly reduced by the integrated deceleration Gs.

However, the deceleration sensor GX includes an error (gradient error) due to the gradient of the road surface in addition to the zero-point drift. Therefore, in the control based on the integrated deceleration Gs (that is, the control in response to the second instruction Hn2), the rear wheel lift suppression control may not be started at the intended deceleration of the vehicle.

≪Action and effect≫
In the braking control device SC, considering the advantages/disadvantages of the first and second instructions Hn1 and Hn2, the first operation instruction (Hn1=1) and the second operation instruction (Hn2=1) is output, the execution of the rear wheel lift suppression control is started, and the braking force Fxf of the front wheels WHf is reduced. That is, when both the first and second instructions Hn1 and Hn2 are in a state of a stop instruction (state of "Hn1=Hn2=0"), the operation instruction is output first among the first and second instructions Hn1 and Hn2. Execution of the rear wheel lift suppression control is started according to whichever is given (that is, the preceding instruction Hns). As a result, on a substantially flat road that is not affected by the road gradient, the rear wheel lift suppression control is started according to the integrated deceleration Gs, and the front wheel braking force Fxf is reduced at an appropriate timing. On the other hand, when it is difficult to perform the second operation instruction (Hn2=1) based on the integrated deceleration Gs due to the influence of the road surface gradient, execution of the rear wheel lift suppression control is started according to the calculated deceleration Ge, Also, the front wheel braking force Fxf is reduced. That is, the demerits of the first and second instructions Hn1 and Hn2 complement each other, and the effects of wheel slip error and road gradient error can be preferably compensated for.

<Processing in First Determination Block HN1>
Arithmetic processing in the first determination block HN1 will be described with reference to the time series diagram of FIG. 3 (transition diagram of state variable Ge with respect to time T and first instruction Hn1). The diagram assumes a situation in which the driver suddenly brakes the motorcycle at time u0 and then issues the first instruction Hn1 in the motorcycle that is running. Note that the calculated deceleration Ge, which is a state variable, indicates a value on the side of decelerating the vehicle with a "plus sign (+)".

At time u0, sudden braking is initiated. In the calculated deceleration calculation block GE, the calculated deceleration Ge is calculated based on the wheel speed Vw. Since the detected wheel speed Vw includes deceleration slip, the calculated deceleration Ge fluctuates and the deceleration of the vehicle cannot be calculated correctly.

At time u1, the calculated deceleration Ge becomes greater than or equal to the first start deceleration gx1. At time u1, time counting (accumulation) of "that the calculated deceleration Ge is equal to or greater than the first start deceleration gx1" is started. At time u2, the calculated deceleration Ge becomes less than the first start deceleration gx1. Since the duration of "Ge≧gx1" is less than the determination time ta, the first instruction Hn1 remains "0". That is, "Hn1=1" is not output.

At time u3, the calculated deceleration Ge becomes equal to or greater than the first start deceleration gx1 again, and the time count for the continuous state is started. At time u4, when the duration reaches the determination time ta, the start condition 1a is satisfied, and the first instruction Hn1 is switched from "0 (stop instruction)" to "1 (operation instruction)". That is, at time u4, "Hn1=1 (first operation instruction)" is output. After that, since the state of "Ge≧gx1" continues, the first instruction Hn1 is maintained at "1".

At time u5, the calculated deceleration Ge becomes less than the first end deceleration gz1. At the time point u5, the termination condition 1b is satisfied, and the first instruction Hn1 is switched from "1 (operation instruction)" to "0 (stop instruction)". That is, at time u5, "Hn1=1 (first operation instruction)" is no longer output.

At time u6, the calculated deceleration Ge becomes equal to or greater than the first start deceleration gx1 again, and at time u7, the duration of "Ge≧gx1" becomes equal to or greater than the judgment time ta, and the first instruction Hn1 becomes "0". to "1", and "Hn1=1" is output. After that, since the state of "Ge≧gx1" continues, the first instruction Hn1 is maintained at "1". At time u8, the calculated deceleration Ge becomes less than the first end deceleration gz1, the first instruction Hn1 is switched from "1" to "0", and the first instruction Hn1 is set to "0". After that, this situation is repeated until the vehicle stops or becomes less than the predetermined speed vs.

<Processing in second judgment block HN2>
Arithmetic processing in the second determination block HN2 will be described with reference to the time series diagram of FIG. Similarly to the above, the diagram assumes a situation in which the driver suddenly brakes the motorcycle at time t0, and then the second instruction Hn2 is issued. Note that for the state variables Ge, Gx, and Gs, the value on the side that decelerates the vehicle is displayed with a "plus sign (+)". Also, in the detected deceleration Gx (indicated by the dashed line) corresponding to the detection signal of the deceleration sensor GX, the zero point drifts by a value go.

At time t0, sudden braking is initiated. In the calculated deceleration calculation block GE, the calculated deceleration Ge is calculated based on the wheel speed Vw. Since the detected wheel speed Vw includes deceleration slip, the calculated deceleration Ge (indicated by the solid line) fluctuates, and the deceleration of the vehicle is not correctly calculated.

In the integrated deceleration calculation block GS, the amount of change over time (detected gradient) dGx of the detected deceleration Gx and the amount of change over time (calculated gradient) dGe of the calculated deceleration Ge are calculated. Furthermore, the detected gradient dGx and the calculated gradient dGe are compared to determine whether or not the detected gradient dGx and the calculated gradient dGe match.

For example, at time t1, it is determined that the comparison result (gradient deviation) hG (=|dGx-dGe|) between the detected gradient dGx and the calculated gradient dGe is less than a predetermined amount hx. Then, at time t2 after a predetermined time tx (which is a reference time and is a predetermined value smaller than the determination time ta) has elapsed from time t1, determination of matching is performed. In other words, “matching between the detected gradient dGx and the calculated gradient dGe” is denied until immediately before time t2.

At time t2, the calculated deceleration Ge at that time is set as the reference deceleration gs (see point (S)). In the calculation cycle following time t2, the integrated deceleration Gs is calculated according to the above equation (1). In subsequent calculation cycles, the integrated deceleration Gs is calculated according to the above equation (2). That is, in the integrated deceleration calculation block GS, the calculated deceleration Ge when the time variation dGx of the detected deceleration Gx matches the time variation dGe of the calculated deceleration Ge is determined as the reference deceleration gs. Then, the integrated deceleration Gs is calculated by sequentially adding the time change amount dGx of the detected deceleration Gx to the reference deceleration gs.

The detected deceleration Gx includes the zero point drift of the value go, but the detected gradient dGx does not include this error. Further, since the wheel speed Vw includes deceleration slip, the calculated deceleration Ge becomes oscillating and the calculated gradient dGe fluctuates. "Coincidence between the detected gradient dGx and the calculated gradient dGe" means that fluctuations in the calculated deceleration Ge have converged. Therefore, in the integrated deceleration calculation block GS, the calculated deceleration Ge when the detected gradient dGx and the calculated gradient dGe match is used as the reference deceleration gs, and the detected gradient dGx which is not affected by the zero point drift is used as the reference deceleration gs. are sequentially added to calculate the integrated deceleration Gs. Therefore, the integrated deceleration Gs eliminates both the effects of zero-point drift and the effects of deceleration slip, so the deceleration of the vehicle is accurately determined by the integrated deceleration Gs.

At time t3, the integrated deceleration Gs becomes greater than or equal to the first start deceleration gx1. The start condition 2a is satisfied, and the second instruction Hn2 is switched from "0 (stop instruction)" to "1 (operation instruction)". That is, at time t3, "Hn2=1 (second actuation instruction)" is output. After that, since the state of "Ge≧gx2" continues, the second instruction Hn2 is maintained at "1".

At time t4, the calculated deceleration Ge becomes less than the second end deceleration gz2. At time t4, the end condition 2b is satisfied, and the second instruction Hn2 is switched from "1 (operation instruction)" to "0 (stop instruction)". That is, at time t4, "Hn2=1 (second actuation instruction)" is no longer output.

At time t5, the calculated deceleration Ge becomes equal to or greater than the second start deceleration gx2 again, the second instruction Hn2 is switched from "0" to "1", and "Hn2=1" is output. After that, since the state of "Ge≧gx2" continues, the second instruction Hn2 is maintained at "1". At time t6, the calculated deceleration Ge becomes less than the second end deceleration gz2, the second instruction Hn2 is switched from "1" to "0", and the second instruction Hn2 is set to "0." After that, this situation is repeated until the vehicle stops or becomes less than the predetermined speed vs.

The first and second start decelerations gx1 and gx2 are set as the same value. Also, the first and second start decelerations gx1 and gx2 may be set as different values. Similarly, the first and second end decelerations gz1 and gz2 are set to the same value. Also, the first and second end decelerations gz1 and gz2 may be set as different values.

<Execution of rear wheel lifting suppression control>
When one of the first and second instructions Hn1 and Hn2 is switched to "1 (operation instruction)" while the first and second instructions Hn1 and Hn2 are "0 (stop instruction)" , execution of the rear wheel lift suppression control is started, and the front wheel braking force Fxf is reduced. Reduction of front wheel braking force Fxf (execution of rear wheel lift suppression control) is continued until preceding instruction Hns is returned from "1" to "0". Then, according to the preceding instruction Hns, the execution of the rear wheel lift suppression control is terminated, and the front wheel braking force Fxf is increased.

Since the reference time tx is set shorter than the determination time ta, normally (for example, when traveling on a flat road), the first instruction Hn1 is executed before the first instruction Hn1 in the state of "Hn1=Hn2=0". 2 instruction Hn2 is switched to "1". That is, the second instruction Hn2 is adopted as the preceding instruction Hns. Then, the execution of the rear wheel lift suppression control is started according to the integrated deceleration Gs. As a result, the front wheel braking force Fxf is quickly reduced at appropriate timing.

On the other hand, due to the influence of the road surface gradient, the first instruction Hn1 may switch to "1" before the second instruction Hn2 when "Hn1=Hn2=0". In this case, the rear wheel lift suppression control is started in accordance with the calculated deceleration Ge so that the influence of the road surface gradient is compensated. As a result, the front wheel braking force Fxf is reliably reduced. Note that when the first instruction Hn1 is switched to "1" before the second instruction Hn2, the integrated deceleration Gs is once reset. That is, after the first instruction Hn1 is adopted as the preceding instruction Hns, the reference deceleration gs is determined again, and the detected gradient dGx is added to the reference deceleration gs to calculate a new integrated deceleration Gs. be.

Since the rear wheel lift suppression control is executed based on the two instructions (determination flags) Hn1 and Hn2, the effect of the wheel slip error and the effect of the road gradient error can be preferably compensated for.

<Second Embodiment of Brake Control Device SC According to the Present Invention>
A second embodiment of the braking control device SC according to the present invention will be described with reference to the overall configuration diagram of FIG. Also in the second embodiment, a motorcycle is assumed as the vehicle. In the second embodiment, "automatic braking control" can be executed to automatically increase the braking force Fx in place of or assisting the driver's braking operation. In the automatic braking control, based on the object (obstacle) in front of the vehicle and the required deceleration Gt corresponding to the relative distance Ob between the vehicle and the vehicle, the wheel cylinder CW is operated to avoid collision between the vehicle and the obstacle. The hydraulic pressure (brake hydraulic pressure) Pw (=Pwf, Pwr) is increased from the hydraulic pressure (master cylinder hydraulic pressure) Pm (=Pmf, Pmr) of the master cylinder CM. The following description focuses on differences from the first embodiment.

≪Driving support system≫
A vehicle according to the second embodiment is provided with a driving support system so as to avoid a collision with an obstacle or reduce damage in the event of a collision. The driving assistance system includes a distance sensor OB and a driving assistance controller ECJ. A distance sensor OB detects a distance (relative distance) Ob between an object (another vehicle, a fixed object, a person, a bicycle, etc.) present in front of the own vehicle and the own vehicle. For example, a camera, radar, or the like is adopted as the distance sensor OB. The relative distance Ob is input to the driving assistance controller ECJ. The driving assistance controller ECJ calculates the required deceleration Gt based on the relative distance Ob. The required deceleration Gt is a target value of vehicle deceleration for executing automatic braking control. The braking controller ECU and driving assistance controller ECJ are network-connected through a communication bus BS. The requested deceleration Gt is transmitted to the brake controller ECU via the communication bus BS.

For example, the required deceleration Gt is calculated based on the collision margin time Tc and the headway time Tw. The collision margin time Tc is the time until the vehicle collides with an object. ” and is determined by dividing by the time derivative value of the relative distance Ob). The headway time Tw is the time it takes for the host vehicle to reach the current position of the forward object, and is calculated by dividing the relative distance Ob by the vehicle body speed Vx. The required deceleration Gt is calculated so as to decrease as the time to collision Tc increases. Further, the required deceleration Gt is calculated so that the larger the headway time Tw, the smaller the required deceleration Gt. The vehicle body speed Vx is transmitted from the brake controller ECU via the communication bus BS.

Furthermore, in the vehicle according to the second embodiment, front wheel and rear wheel operation amounts Baf, Bar (=Ba) of front wheel and rear wheel braking operation members (brake levers, brake pedals) BPf, BPr by the driver are detected. Therefore, front wheel and rear wheel operation amount sensors BAf and BAr (=BA) are provided. For example, as the operation amount sensor BA, a master cylinder hydraulic pressure sensor PM (=PMf, PMr), an operation displacement sensor SP (=SPf, SPr) for detecting an operation displacement Sp of the braking operation member BP, and a At least one operating force sensor FP (not shown) is employed to detect the operating force Fp. That is, the braking operation amount Ba is at least one of the master cylinder hydraulic pressure Pm, the operation displacement Sp, and the operation force Fp.

<<Brake control device SC>>
Similar to the first embodiment, the fluid unit HU is provided in the connection path HS. Fluid unit HU includes electric motor MT, fluid pump HP, inlet valve VI and outlet valve VO, as described above. Furthermore, the fluid unit HU includes, in addition to these, a pressure regulating valve UA (=UAf, UAr), a pressure regulating reservoir RC (=RCf, RCr), and a master cylinder hydraulic pressure sensor PM (=PMf, PMr). .

The front and rear wheel pressure regulating valves UAf and UAr (=UA) are positioned above the front and rear wheel inlet valves VIf and VIr (=VI) (the portion between the master cylinder CM and the inlet valve VI) to It is provided on the connection paths HSf and HSr (=HS). The pressure regulating valve UA is a normally open linear solenoid valve (also referred to as a "differential pressure valve") whose valve opening amount (lift amount) is continuously controlled according to the amount of energization (current value).

Front and rear wheel return paths HKf and HKr (=HK) are provided to connect the upper portion of the pressure regulating valve UA and the lower portion of the pressure regulating valve UA. The return path HK, which is a fluid path, is provided with front and rear wheel fluid pumps HPf and HPr (=HP), and is connected to front and rear wheel pressure regulating reservoirs RCf and RCr (=RC).

The fluid pump HP sucks the braking fluid BF from the upper portion of the pressure regulating valve UA and discharges the braking fluid BF to the lower portion of the pressure regulating valve UA via the pressure regulating reservoir RC. When the fluid pump HP is rotationally driven by the electric motor MT, the brake fluid BF is returned to the front and rear wheels KNf and KNr (=KN) in the return path HK as indicated by the dashed arrows ("HP→UA→ RC→HP” flow). Here, "reflux" means that the brake fluid BF circulates and returns to its original flow.

The return KN is throttled by the pressure regulating valve UA, and a pressure difference (differential pressure) Sa is generated between the upper portion (that is, the master cylinder hydraulic pressure Pm) and the lower portion (that is, the braking hydraulic pressure Pw) of the pressure regulating valve UA. be. Specifically, the controller ECU energizes the normally open pressure regulating valve UA to reduce the amount of opening of the valve, so that the hydraulic pressure Pw of the wheel cylinder CW increases from the master cylinder hydraulic pressure Pm. adjusted to For example, in automatic braking control, when the braking operation member BP is not operated (that is, when "Pm=0"), the orifice effect of the pressure regulating valve UA automatically increases the wheel cylinder hydraulic pressure Pw. . In the automatic braking control, based on the required deceleration Gt, the greater the required deceleration Gt, the smaller the valve opening amount of the pressure regulating valve UA, and the differential pressure Sa (resultingly, the braking hydraulic pressure Pw) is increased.

Above the front and rear wheel pressure regulating valves UAf and UAr, front and rear wheel master cylinder hydraulic pressure sensors are installed to detect the hydraulic pressures (master cylinder hydraulic pressures) Pmf and Pmr in the front and rear wheel hydraulic chambers Rmf and Rmr. PMf and PMr are provided. The master cylinder hydraulic pressure sensor PM (=PMf, PMr) corresponds to the manipulated variable sensor BA, and the master cylinder hydraulic pressure Pm corresponds to the manipulated variable Ba. For example, when the operation displacement sensor SP is employed as the operation amount sensor BA, the master cylinder pressure sensor PM may be omitted. Alternatively, both the master cylinder pressure sensor PM and the operation displacement sensor SP may be provided to ensure redundancy.

In the second embodiment, inlet valve VI (normally open on/off solenoid valve) and outlet valve VO (normally closed on/off solenoid valve) are arranged in the same manner as in the first embodiment. In the second embodiment, as in the first embodiment, the rear wheel lift suppression control controls the front wheel inlet valve VIf and the front wheel outlet valve VOf to control the front wheel brake fluid pressure Pwf (resulting in the front wheel braking force Fxf ) is reduced. Specifically, when the front wheel braking force Fxf needs to be reduced, the front wheel inlet valve VIf is closed, the front wheel outlet valve VOf is opened, and the front wheel brake fluid pressure Pwf is reduced.

In the second embodiment, the rear wheel lift suppression control may be performed by the front wheel pressure regulating valve UAf. Specifically, when it becomes necessary to reduce the front wheel braking force Fxf, the amount of energization to the front wheel pressure regulating valve UAf is reduced, and the valve opening amount is increased. As a result, the front wheel braking hydraulic pressure Pwf is reduced, and the front wheel braking force Fxf is reduced. Also in the second embodiment, the same effects as described above (compensation for wheel slip error and road gradient error) can be obtained.

<Other embodiments>
Other embodiments will be described below. Other embodiments also have the same effect as described above.
In the above embodiment, the hydraulic unit HU via the brake fluid BF was exemplified as an actuator for adjusting the braking torque Tq (resulting in the braking force Fx) of the wheels WH. Alternatively, a motorized actuator driven by an electric motor may be employed. In the electric actuator, the rotary power of the electric motor is converted into linear power, which forces the friction member against the rotary member KT. Therefore, the braking torque Tq is directly applied by the electric motor to generate the braking force Fx without depending on the braking fluid pressure Pw. Furthermore, a composite type in which a hydraulic actuator via a brake fluid BF is employed for the front wheels WHf and an electric actuator is employed for the rear wheels WHr may be used.

In the above embodiment, a motorcycle is employed as the vehicle, and the braking control device SC is applied. Alternatively, the braking control device SC can also be applied to four-wheeled vehicles (passenger cars, trucks, etc.). However, the braking control SC with and is more effective on motorcycles. The reason for this will be explained below.

Since motorcycles need to tilt their bodies when turning, tires for four-wheeled vehicles have a flat tread surface, whereas tires for two-wheeled vehicles have a cross-sectional shape that is close to a circle. . Therefore, in a motorcycle, when the vehicle body is tilted for turning, the tire diameter (the distance between the axle and the contact surface of the tire) becomes smaller, and the detection result of the wheel speed sensor VW (that is, the wheel speed) Vw decreases. become smaller. That is, the wheel speed Vw of the motorcycle includes an error due to turning (turning error) in addition to the deceleration slip error. Since this turning error is also compensated for by the integrated deceleration Gs, it is extremely effective to apply the braking control device SC to a motorcycle as compared to applying it to a four-wheeled vehicle.

SC: Braking control device, GE: Calculation deceleration calculation block, GS: Integrated deceleration calculation block, HN1: First determination block (first determination section), HN2: Second determination block (second determination section), FX: Braking force adjustment block Hn1 First instruction (first judgment flag) Hn2 Second instruction (second judgment flag) Hns Advance instruction BP Braking operation member CM Master cylinder CW Wheel cylinder HU...fluid unit, MT...electric motor, HP...fluid pump, VI...inlet valve, VO...outlet valve, UA...pressure regulating valve, ECU...controller, VW...wheel speed sensor, GX...deceleration sensor, Vw...wheel speed , Vx... vehicle body speed, Gx... detected deceleration, Ge... calculated deceleration, Gs... integrated deceleration, gs... reference deceleration, dGx... detected gradient (amount of time change in detected deceleration Gx), dGe... calculated gradient ( Amount of change in calculated deceleration Ge over time), Fx...braking force.

Claims (1)

A braking control device for a vehicle that executes rear wheel lift suppression control for suppressing lift of the rear wheels of the vehicle,
a deceleration sensor that detects deceleration of the vehicle as a detected deceleration;
A wheel speed sensor that detects the rotational speed of the wheel of the vehicle as a wheel speed;
an actuator that adjusts the braking force of the front wheels of the vehicle;
a controller that controls the actuator based on the detected deceleration and the wheel speed;
The controller is
When the calculated deceleration, which is the deceleration of the vehicle calculated based on the wheel speed, is equal to or greater than a first threshold value and continues for a determination time, the execution of the rear wheel lift suppression control is determined. a first determination unit that outputs a first operation instruction by
The calculated deceleration when the amount of time change in the calculated deceleration and the amount of time change in the detected deceleration match is set as a reference deceleration, and the amount of time change in the detected deceleration is sequentially added to the reference deceleration. a second determination unit for determining execution of the rear wheel lift suppression control and outputting a second actuation instruction when the integrated deceleration reaches a second threshold value or more; including
A braking control device for a vehicle, which reduces the braking force of the front wheels when either one of the first actuation instruction and the second actuation instruction is output.