JP7388211B2 - Vehicle deceleration calculation device and vehicle braking control device using the device - Google Patents

Description

The present disclosure relates to a vehicle deceleration calculation device and a vehicle braking control device using the device.

As shown in Patent Document 1, the applicant "provides a brake control device for a vehicle that can suppress unnecessary reduction of brake pressure in a front wheel brake for suppressing lifting of a rear wheel." The electronic control unit 40, which is a component of the brake control device of a motorcycle, includes a filter processing unit 44 that outputs a value obtained by filtering the output GX of the acceleration sensor 41, and a front wheel brake 10, when the vehicle body deceleration indicated by the filter value, which is the output value of the filter processing section 44, exceeds a specified lift-up determination value, pressure reduction control is performed to reduce the brake pressure of the front wheel brake 10. The electronic control unit 40 of such a brake control device is provided with a pressure reduction control unit 42. When the rate of increase in vehicle deceleration indicated by the output value of the filter processing unit 44 is equal to or higher than a specified value, the increase rate is set to the specified value. The present invention has been developed to include a judgment value setting section 45 that sets the lift-up judgment value to a larger value than when the lift-up judgment value is less than 1.

In the brake control device of Patent Document 1, a detection signal ("detection reduction") of an acceleration sensor (also called "deceleration sensor") is used to execute control to suppress rear wheel lifting (referred to as "rear wheel lifting suppression control"). speed). If the detection direction of the deceleration sensor is horizontal to the road surface, the deceleration of the vehicle (vehicle body) can be accurately detected without a gravity component being included in the detected deceleration. However, since the detected deceleration includes a zero point drift error, it is necessary to compensate for this error.

JP2017-149378

An object of the present invention is to provide a deceleration calculation device used for rear wheel floating suppression control that can reduce errors in zero point drift. Furthermore, it is an object of the present invention to provide a braking control device for a vehicle that can compensate for errors in zero point drift and can suitably execute rear wheel floating suppression control.

A vehicle deceleration calculation device (GS) according to the present invention adjusts a braking force (Fxf) acting on a front wheel (WHf) of a vehicle to suppress lifting of a rear wheel (WHr) of the vehicle. It is applied to inhibitory control, and includes an "acquisition unit (XA) that acquires a detection signal from a deceleration sensor (GX) as a detected deceleration (Gx)" and a "rotation of the vehicle's wheels (WH)". a calculation unit (XB) that calculates the deceleration of the vehicle as a calculated deceleration (Ge) based on the speed (Vw); a determination unit (XC) that determines an integrated deceleration (Gs) that is a deceleration applied to the rear wheel lift suppression control. The determining unit (XC) determines the calculated deceleration ( Ge) is determined as a reference deceleration (gs), and the cumulative deceleration (Gs) is calculated by sequentially integrating the amount of time change (dGx) of the detected deceleration (Gx) to the reference deceleration (gs). .

The cumulative deceleration Gs calculated by the above configuration is suitably compensated for the zero point drift error. Therefore, the vehicle deceleration applied to the rear wheel floating suppression control can be calculated with high accuracy based on the cumulative deceleration Gs.

A braking control device (SC) for a vehicle according to the present invention adjusts a braking force (Fxf) acting on a front wheel (WHf) of a vehicle to suppress lifting of a rear wheel (WHr) of the vehicle. , "Deceleration sensor (GX) that detects the deceleration of the vehicle as detected deceleration (Gx)" and "Wheel that detects the rotational speed (Vw) of the wheel (WH) of the vehicle as wheel speed (Vw)" A speed sensor (VW), an actuator (HU) that adjusts the braking force (Fxf), and a controller (ECU) that controls the actuator (HU). The controller (ECU) calculates the deceleration of the vehicle as a calculated deceleration (Ge) based on the wheel speed (Vw), and calculates a temporal change amount (dGx) of the detected deceleration (Gx) and the calculated deceleration. The calculated deceleration (Ge) when the time change amount (dGe) of the velocity (Ge) matches is determined as a reference deceleration (gs), and the detected deceleration (Gx) is added to the reference deceleration (gs). The cumulative deceleration (Gs) is calculated by sequentially integrating the amount of change over time (dGx). Then, the controller (ECU) reduces the braking force (Fxf) when the cumulative deceleration (Gs) exceeds a threshold value (gx).

According to the above configuration, the rear wheel lifting suppression control is executed based on the cumulative deceleration Gs in which the error influence of zero point drift has been compensated, so that lifting of the rear wheel WHr can be reliably suppressed.

1 is an overall configuration diagram for explaining an embodiment of a deceleration calculation device GS and a first embodiment of a brake control device SC according to the present invention. It is a block diagram for explaining calculation processing of deceleration calculation device GS. FIG. 3 is a flowchart for explaining arithmetic processing of rear wheel floating suppression control using the calculation results of the deceleration calculation device GS. FIG. 3 is a time series diagram for explaining the calculation processing of the deceleration calculation device GS and the calculation processing of rear wheel floating suppression control. FIG. 2 is an overall configuration diagram for explaining a second embodiment of a brake control device SC according to the present invention.

<Symbols of component parts, etc., subscripts at the end of the symbol>
In the following description, components, arithmetic processing, signals, characteristics, and values having the same symbol, such as "CW", have the same function. The suffixes "f" and "r" added to the end of each symbol are comprehensive symbols indicating which symbol the symbol refers to 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 a front wheel cylinder, "CWr" represents a rear wheel cylinder, and "CW" represents a front wheel, rear wheel cylinder. In addition, in the connection path HS, the side closer to the master cylinder CM is called the "upper", and the side closer to the wheel cylinder CW is called the "lower".

<First embodiment of deceleration calculation device GS and brake control device SC according to the present invention>
An embodiment of a vehicle deceleration calculation device GS according to the present invention and a first embodiment of a vehicle brake control device SC equipped with the device GS will be described with reference to the overall configuration diagram of FIG. The vehicle is assumed to be a motorcycle (also referred to as a "motorcycle"). A vehicle employs two fluid paths (ie, 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 connecting paths HSf and HSr (=HS) are fluid paths. The "fluid path" is a path for moving the brake fluid BF, which is a working fluid, and includes brake piping, a flow path of the fluid unit HU, a hose, and the like.

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

The brake operation member BP is a member operated by the driver to decelerate the vehicle. For example, a brake lever is used as the front wheel brake operation member BPf, a brake pedal is used as the rear wheel brake operation member BPr, and in a scooter, a brake lever is used as both the brake operation members BPf and BPr. Ru. By operating the brake 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, front wheel and rear wheel braking torques Tqf and Tqr (=Tq) are adjusted, and front and rear wheel braking forces Fxf and Fxr (=Fx) are generated. Here, the front wheel and rear wheel cylinder hydraulic pressures Pwf and Pwr are also referred to as "front wheel and rear wheel braking hydraulic pressures Pwf and Pwr (=Pw)."

Front wheel and rear wheel rotating members KTf and KTr (=KT) are fixed to wheels WH (=WHf, WHr) of the vehicle. Front wheel and rear wheel brake calipers CPf and CPr (=CP) are arranged so as to sandwich the rotating member KT (for example, a brake disc). The brake caliper CP is provided with a wheel cylinder CW, and by increasing the pressure of the brake fluid BF (braking fluid pressure) Pw inside the wheel cylinder CW, a friction member (for example, a brake pad) is pressed against the rotating member KT. . Since the rotating member KT and the wheel WH are fixed so as to rotate integrally, the braking torque Tq is generated at the wheel WH due to the frictional force generated at this time. This braking torque Tq generates a braking force Fx on the wheel 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 operation member BP is operated, the volume of the hydraulic chamber Rm is reduced, and the brake fluid BF is force-fed from the hydraulic chamber Rm to the wheel cylinder CW via the connection path 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, VWr (=VW), and a longitudinal acceleration sensor (also referred to as a "deceleration sensor") GX. Front wheel and rear wheel speeds Vwf and Vwr (=Vw) are detected by wheel speed sensors VW provided on each wheel WH. A deceleration sensor GX provided on the body of the vehicle detects acceleration Gx in the longitudinal direction (progressing direction) of the vehicle (which is longitudinal acceleration and also referred to as "detected deceleration"). The signals of the wheel speed Vw and the detected deceleration Gx are used for anti-lock brake control to suppress the locking tendency of the wheels WH (that is, excessive deceleration slip), rear wheel lifting suppression control to suppress lift-up of the rear wheels WHr, etc. It is used for braking force control. The wheel speed Vw and longitudinal acceleration (detected deceleration) Gx detected by each sensor (such as VW) are input to a brake controller ECU (also simply referred to as "controller"). The controller ECU calculates the vehicle speed Vx based on the wheel speed Vw.

≪Brake controller ECU≫
The brake control device SC includes a brake controller ECU and a fluid unit HU. A brake controller (also referred to as an "electronic control unit") ECU is composed of an electric circuit board on which a microprocessor or the like is mounted, and a control algorithm programmed into the microprocessor.

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

The controller ECU is equipped with a drive circuit to drive the electromagnetic valves VI and 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) 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 energization state (that is, the excitation state) of the electromagnetic valves VI and VO is controlled. The drive circuit is provided with an energization amount sensor that detects the actual energization amount of the electric motor MT and the solenoid valves VI, 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 electromagnetic valves VI and VO.

The brake controller ECU includes a deceleration calculation device GS. The deceleration calculation unit GS is an algorithm programmed into a microprocessor. The deceleration calculation device GS calculates the cumulative deceleration Gs applied to the rear wheel floating suppression control based on the wheel speed Vw and the detected deceleration Gx. Details of the cumulative deceleration Gs will be described later.

≪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 master cylinders CMf and CMr, the front and rear wheel hydraulic pressure chambers Rmf and Rmr, and the front and rear wheel cylinders CWf and CWr are the front and rear wheel connection paths (fluid paths) HSf and HSr (=HS ). In the connection path HS, a fluid unit HU is provided between the master cylinder CM and the wheel cylinder CW. The fluid unit HU includes 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 electromagnetic valves (for example, on-off valves) that close in response to energization. The inlet valve VI is provided in the middle of the connection path HS. The inlet valve VI is controlled based on a drive signal Vi from the controller ECU. The inlet valve VI allows movement of the brake fluid BF between the wheel cylinder CW and the master cylinder CM through the connection path HS when the valve is open, and is blocked when the valve is closed.

In the connection path HS, between the inlet valve VI and the wheel cylinder CW (that is, the lower part of the inlet valve VI), one end of the front wheel and rear wheel return paths HRf and HRr (=HR), which are fluid paths, is connected. Connected. The other end of the return path HR is located between the master cylinder CM and the inlet valve VI (i.e., between the master cylinder CM and the inlet valve VI (i.e., the upper part of the inlet valve VI), and the connection path HS. )” is connected to. In other words, the return path HR is a fluid path that connects the upper part of the inlet valve VI and the lower part of the inlet valve VI in the connection path HS so as to bypass the inlet valve VI.

The front wheel and rear wheel outlet valves VOf, VOr (=VO) are normally closed electromagnetic valves (for example, on-off valves) that open in response to energization. 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 allows 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 opened, and is blocked when the valve is closed.

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

The two fluid pumps HP are driven by one electric motor MT. Electric motor MT is controlled based on a drive signal Mt from a brake controller ECU. Braking fluid BF is pumped up from the low pressure reservoir RW or the wheel cylinder CW by the fluid pump HP and returned 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 anti-lock brake control or rear wheel lifting suppression control, the inlet valve VI is placed in the closed position and the outlet valve VO is placed in the open position. Ru. The 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. Furthermore, in order to increase the brake fluid pressure Pw, the inlet valve VI is placed in the open position, and the outlet valve VO is placed in the closed position. 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, in order to maintain the hydraulic pressure (braking hydraulic pressure) Pw in the wheel cylinder CW, both the inlet valve VI and the outlet valve VO are closed. That is, by controlling the electromagnetic valves VI and VO, the braking fluid pressure Pw (that is, the braking torque Tq, and as a result, the braking force Fx) can be adjusted independently at the wheel cylinder CW of each wheel WH. .

<Calculation processing of deceleration calculation device GS>
The calculation process in the deceleration calculation device GS will be explained with reference to the block diagram of FIG. The deceleration calculation device GS is applied to the brake control device SC including the rear wheel lifting suppression control, and compensates for the zero point drift error of the detected deceleration Gx, which is the output of the deceleration sensor GX, and performs the rear wheel lifting suppression control. This is for proper execution. The deceleration calculation device GS includes a control algorithm programmed in the controller ECU, and is composed of an acquisition section XA, a calculation section XB, and a determination section XC. In addition, in the cumulative deceleration Gs, the detected deceleration Gx, and the calculated deceleration Ge, which will be explained below, the value on the side that decelerates the vehicle is represented by a "plus sign (+)".

The acquisition unit XA acquires the detected deceleration Gx from the deceleration sensor GX. Specifically, in the controller ECU, first, 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 subjected to filter processing to obtain (determine) the detected deceleration Gx.

A calculation unit XB calculates a calculation deceleration Ge based on the wheel speed Vw. Specifically, the calculation unit XB first calculates the vehicle speed Vx based on the faster of the front wheel speed Vwf and the rear wheel speed Vwr. In calculating the vehicle speed Vx, a limit may be set on the amount of change over time. That is, an upper limit value αup of the increasing slope of the vehicle body speed Vx and a lower limit value αdn of the decreasing slope are set, and changes in the vehicle body speed Vx are restricted by the upper and lower limit values αup and αdn. Next, the vehicle speed Vx is time differentiated to calculate the calculated deceleration Ge. That is, in the calculation unit XB, the vehicle speed Vx is calculated based on the wheel speed Vw, and the calculated deceleration Ge is calculated based on the vehicle speed Vx.

The determining unit XC calculates the cumulative deceleration Gs based on the detected deceleration Gx and the calculated deceleration Ge. The cumulative deceleration Gs is the deceleration of the vehicle (vehicle body) applied to the rear wheel floating suppression control. In the determination unit XC, first, a time change amount dGx of the detected deceleration Gx and a time change amount dGe of the calculated deceleration Ge are calculated. Next, it is determined whether "the amount of change over time dGx and the amount of time change dGe match or not." Then, the calculated deceleration Ge when the time change amount dGx and the time change amount dGe match is determined as the reference deceleration gs. Here, the amount of change over time dGx is also referred to as a "detected gradient" and is a time differential value of the detected deceleration Gx. The time change amount dGe is also called a "calculated gradient" and is a time differential value of the calculated deceleration Ge.

For example, the determination unit XC makes the above determination based on "the deviation (also referred to as "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 predetermined value (constant) set in advance. Furthermore, "coincidence between the detected gradient dGx and the calculated gradient dGe" is defined as "the point in time (corresponding The determination may be made based on the calculation cycle). Here, the reference time tx is a predetermined value (constant) set in advance. In any case, the reference deceleration gs is the calculated deceleration Ge when the detected slope dGx and the calculated slope dGe match.

Then, in the determination unit XC, the reference deceleration gs and the amount of change over time (detected gradient) dGx of the detected deceleration Gx are sequentially integrated in each calculation period to calculate the integrated deceleration Gs. That is, in the next calculation cycle after the calculation cycle in which the reference deceleration gs was set, the cumulative deceleration Gs is calculated using the following equation (1). Note that in the following formula, [n] corresponds to the current calculation cycle, and [n-1] represents a state quantity (variable) corresponding to the previous calculation cycle.
Gs[n]=gs+dGx[n]...Formula (1)

After the first cumulative deceleration Gs is calculated, the detected gradient dGx[n] of the current calculation cycle is added to the cumulative deceleration Gs[n-1] of the previous calculation cycle, resulting in the cumulative deceleration Gs[n]. is calculated. That is, as shown in Equation (2), the detected gradient dGx[n] is sequentially added to the cumulative deceleration Gs[n-1] in each calculation period to calculate the cumulative deceleration Gs[n].
Gs[n]=Gs[n-1]+dGx[n]...Formula (2)

The detected deceleration Gx includes an error of zero point drift. However, since the detected gradient dGx is the amount of change with respect to time, it does not include the error of zero point drift. In the deceleration calculation device GS, the detected gradient dGx is sequentially integrated in each calculation cycle to calculate the cumulative deceleration Gs. Therefore, the error of zero point drift is compensated for in the cumulative deceleration Gs.

Since the calculated deceleration Ge is calculated based on the wheel speed Vw, it is affected by the deceleration slip of the wheel WH (the slip in the rotational direction of the wheel WH, which is the difference between the vehicle body speed Vx and the wheel speed Vw). In particular, when the rear wheel floating suppression control is executed, the deceleration slip is likely to increase because the braking is sudden and the vehicle body deceleration is large. In order to avoid being affected by the deceleration slip of the wheels WH, the deceleration calculation device GS sets the calculated deceleration Ge when the detected slope dGx and the calculated slope dGe match as the reference value (reference deceleration) gs, and then performs the detection. Integration of the gradient dGx is started. Here, "when the detected gradient dGx and the calculated gradient dGe match" is "when the gradient deviation hG between the detected gradient dGx and the calculated gradient dGe becomes less than the predetermined amount hx". Specifically, the calculated deceleration Ge at the time when the state of "hG<hx" continues for a predetermined reference time tx is determined as the reference value gs.

"When the detected gradient dGx and the calculated gradient dGe match" corresponds to "when the calculated deceleration Ge is not affected by the deceleration slip of the wheels WH." Therefore, the reference deceleration gs does not include an error due to deceleration slip, and the detected gradient dGx does not include an error due to zero point drift of the deceleration sensor GX. Therefore, the cumulative deceleration Gs, which is determined by sequentially adding the detected gradient dGx at each calculation cycle starting from the reference deceleration gs, includes both the error caused by the deceleration slip and the zero point drift error. Compensated. In other words, the deceleration of the vehicle (vehicle body) is accurately expressed (determined) by the cumulative deceleration Gs.

<Arithmetic processing for rear wheel floating suppression control>
With reference to the flowchart of FIG. 3, the calculation process of the rear wheel floating suppression control using the calculation result (integrated deceleration) Gs of the deceleration calculation device GS will be described.

Since the center of gravity of the vehicle is higher than the road surface, sudden braking will reduce the rear wheel load, and in extreme cases, the rear wheel WHr will leave the road surface ("rear wheel floating" or "rear wheel lift"). "up") may occur. The rear wheel floating suppression control suppresses the rear wheel floating by reducing the front wheel braking force Fxf based on the deceleration of the vehicle body. The rear wheel floating suppression control according to the cumulative deceleration Gs calculated by the deceleration calculation device GS will be described below.

In step S110, the cumulative deceleration Gs calculated by the deceleration calculation device GS is read (obtained). In step S120, it is determined whether "rear wheel float suppression control is being executed or not." If the rear wheel floating suppression control is not being executed and step S120 is negative, the process proceeds to step S130. On the other hand, if the rear wheel float suppression control is being executed and step S120 is affirmed, the process proceeds to step S140.

In step S130, it is determined whether or not to start executing the rear wheel float suppression control. Specifically, when the following condition 1 (start condition) is satisfied, it is determined to start executing the rear wheel floating suppression control.
Condition 1: The cumulative deceleration Gs is greater than or equal to the starting deceleration gx. Here, the start deceleration gx is a threshold value for starting the reduction of the front wheel braking force Fxf, and is a predetermined value (constant) set in advance.
If "Gs≧gx" and step S130 is affirmed, the process proceeds to step S150. On the other hand, if "Gs<gx" and step S130 is negative, the process returns to step S110.

In step S140, it is determined whether or not to end the execution of the rear wheel float suppression control. Specifically, when the following condition 2 (termination condition) is satisfied, it is determined that the execution of the rear wheel floating suppression control is to be terminated.
Condition 2: The cumulative deceleration Gs is less than the end deceleration gz. Here, the end deceleration gz is a threshold value for ending the reduction of the front wheel braking force Fxf (a threshold value for allowing an increase in the front wheel braking force Fxf), and is a predetermined value (a constant ). The ending deceleration gz is set as a value smaller than the starting deceleration gx (ie, "gx>gz").

If "Gs≧gz" and step S140 is negative, the process proceeds to step S150. On the other hand, if "Gs<gz" and step S140 is affirmed, the increase in front wheel braking force Fxf is permitted (that is, the reduction in front wheel braking force Fxf is ended), and the process returns to step S110. It will be done.

In step S140, the following condition 3 related to the vehicle speed Vx may be added as an end condition for the rear wheel float suppression control.
Condition 3: Vehicle speed Vx is less than end speed vx. Here, the end speed vx is a predetermined value (constant) set in advance.
In step S140, if condition 3 is adopted, execution of the rear wheel float suppression control is ended if either condition 2 or condition 3 is satisfied. Therefore, execution of the rear wheel floating suppression control is continued only when both Condition 2 and Condition 3 are denied.

In step S150, front wheel braking force Fxf is reduced. For example, as described with reference to FIG. 1, the front wheel inlet valve VIf is closed and the front wheel outlet valve VOf is opened. By opening the front wheel outlet valve VOf, the brake fluid BF in the front wheel cylinder CWf flows out to the front wheel low pressure reservoir RWf. Further, by closing the front wheel inlet valve VIf, the braking fluid BF is prevented from flowing from the front wheel master cylinder CMf to the front wheel cylinder CWf. As a result, the front wheel braking hydraulic pressure Pwf is decreased, and the front wheel braking force Fxf is decreased.

In the rear wheel floating suppression control, the performance of the control is improved by employing the integrated deceleration Gs in which the error due to deceleration slip and the zero point drift error are compensated. Specifically, the front wheel braking force Fxf can be reduced at an appropriate timing without being affected by deceleration slip and zero point drift.

<Deceleration calculation device GS and calculation processing of rear wheel floating suppression control>
With reference to the time series diagram of FIG. 4 (transition diagram of state variables Ge, Gx, and Gs with respect to time T), the calculation processing of the deceleration calculation device GS and the rear wheel floating suppression control will be described. The diagram assumes a situation in which, in a running motorcycle, the driver suddenly brakes at time t0, and then rear wheel floating suppression control is executed. Here, in the detected deceleration Gx (indicated by a broken line) acquired by the acquisition unit XA according to the detection signal of the deceleration sensor GX, the zero point has drifted by a value go.

At time t0, sudden braking is started. A calculation unit XB calculates a calculation deceleration Ge based on the wheel speed Vw. Since the detected wheel speed Vw includes deceleration slip, the calculated deceleration Ge (indicated by a solid line) fluctuates, and the deceleration of the vehicle is not calculated correctly.

The determination unit XC calculates a time change amount (detection slope) dGx of the detected deceleration Gx and a time change amount (calculation slope) dGe of the calculated deceleration Ge. Further, the detected gradient dGx and the calculated gradient dGe are compared, and it is determined whether "the detected gradient dGx and the calculated gradient dGe match or not."

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 the predetermined amount hx. Then, at time t2, when a predetermined time (reference time) tx has elapsed from time t1, the above-mentioned matching is determined. That is, until just before time t2, "the match between the detected gradient dGx and the calculated gradient dGe" is denied.

At time t2, the calculated deceleration Ge at that time is set as the reference deceleration gs (see point (S)). In the next calculation cycle after time t2, the cumulative deceleration Gs is calculated according to the above equation (1). In the subsequent calculation cycle, the cumulative deceleration Gs is calculated according to the above equation (2). That is, the determination unit XC determines the calculated deceleration Ge when the time change amount dGx of the detected deceleration Gx and the time change amount dGe of the calculated deceleration Ge match as the reference deceleration gs. Then, the cumulative deceleration Gs is calculated by sequentially integrating the amount of change over time dGx of the detected deceleration Gx into the reference deceleration gs.

The detected deceleration Gx includes a 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 oscillatory, and the calculated gradient dGe fluctuates. "A match between dGx and the calculated gradient dGe" means that fluctuations in the calculated deceleration Ge have converged. Therefore, in the deceleration calculation device GS, the calculated deceleration Ge when the detected slope dGx and the calculated slope dGe match is set as the reference deceleration gs, and the detected slope dGx which is not affected by the zero point drift is added to this. The cumulative deceleration Gs is calculated by sequentially adding the values. Therefore, since both the influence of zero point drift and the influence of deceleration slip are excluded from the cumulative deceleration Gs, the deceleration of the vehicle can be accurately determined by the cumulative deceleration Gs.

At time t3, the cumulative deceleration Gs becomes equal to or greater than the start deceleration (threshold) gx, and execution of the rear wheel floating suppression control is started. Along with this, the front wheel braking force Fxf is reduced. Here, the start deceleration gx is a preset threshold for starting the reduction of the front wheel braking force Fxf.

At time t4, the cumulative deceleration Gs becomes less than the end deceleration gz, and the execution of the rear wheel floating suppression control is temporarily ended. Along with this, the front wheel braking force Fxf, which had been reduced, is increased. Here, the end deceleration gz is a preset threshold value for ending the reduction of the front wheel braking force Fxf (that is, allowing the front wheel braking force Fxf to increase) and increasing the front wheel braking force Fxf again. It is. Note that the end deceleration gz is a value less than the start deceleration gx. For example, the ending deceleration gz is smaller than the starting deceleration gx by a value ga.

At time t5, the cumulative deceleration Gs becomes equal to or greater than the starting deceleration gx, and the execution of the rear wheel floating suppression control is started again, and the front wheel braking force Fxf is limited and reduced. At time t6, the cumulative deceleration Gs becomes less than the end deceleration gz, the execution of the rear wheel floating suppression control is ended, and the front wheel braking force Fxf is increased. In this way, the front wheel braking force Fxf is increased and decreased repeatedly until the vehicle stops or the vehicle speed Vx becomes less than the predetermined speed vs.

As described above, the cumulative deceleration Gs is a state variable in which the error effects of zero point drift and deceleration slip are compensated for. Therefore, by using the cumulative deceleration Gs, the rear wheel lifting suppression control is suitably executed, and the lifting phenomenon (lift-up phenomenon) of the rear wheel WHr during sudden braking can be reliably suppressed.

<Second embodiment of brake control device SC according to the present invention>
A second embodiment of the brake control device SC according to the present invention will be described with reference to the overall configuration diagram of FIG. In the second embodiment as well, a motorcycle is assumed as the vehicle. In the second embodiment, it is possible to perform "automatic braking control" that automatically increases the braking force Fx instead of or as an aid to the driver's braking operation. In automatic braking control, wheel cylinder CW is adjusted to avoid collision between the vehicle and the obstacle, based on the required deceleration Gt according to the relative distance Ob between the vehicle and the object (obstacle) in front of the vehicle. The hydraulic pressure (braking hydraulic pressure) Pw (=Pwf, Pwr) is increased from the hydraulic pressure (master cylinder hydraulic pressure) Pm (=Pmf, Pmr) of the master cylinder CM. Hereinafter, differences from the first embodiment will be mainly explained.

≪Driving support system≫
The vehicle according to the second embodiment is equipped with a driving support system to avoid a collision with an obstacle or to reduce damage in the event of a collision. The driving support system includes a distance sensor OB and a driving support controller ECJ. The distance sensor OB detects the distance (relative distance) Ob between the own vehicle and an object (another vehicle, a fixed object, a person, a bicycle, etc.) that exists in front of the own vehicle. For example, a camera, radar, etc. are employed as the distance sensor OB. The relative distance Ob is input to the driving support controller ECJ. The driving support 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 brake controller ECU and the driving support 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. Collision margin time Tc is the time until a collision occurs between the host vehicle and an object. '' and is determined by dividing by the time derivative value of the relative distance Ob. The headway time Tw is the time taken for the own vehicle to reach the current position of the object in front, and is calculated by dividing the relative distance Ob by the vehicle speed Vx. The required deceleration Gt is calculated such that the larger the collision margin time Tc is, the smaller the required deceleration Gt is. Further, the required deceleration Gt is calculated such that the greater the headway time Tw, the smaller the required deceleration Gt. Note that the vehicle speed Vx is transmitted from the brake controller ECU via the communication bus BS.

Further, in the vehicle according to the second embodiment, front wheel and rear wheel operation amounts Baf and Bar (=Ba) of the front wheel and rear wheel braking operation members (brake lever, brake pedal) BPf and BPr by the driver are detected. Front wheel and rear wheel operation amount sensors BAf and BAr (=BA) are provided. For example, the operation amount sensor BA includes a master cylinder hydraulic pressure sensor PM (=PMf, PMr), an operation displacement sensor SP (=SPf, SPr) that detects the operation displacement Sp of the brake operation member BP, and a control displacement sensor SP (=SPf, SPr) that detects the operation displacement Sp of the brake operation member BP. At least one of the operating force sensors FP (not shown) that detects the operating force Fp is employed. 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. As described above, the fluid unit HU includes the electric motor MT, the fluid pump HP, the inlet valve VI, and the outlet valve VO. Furthermore, in addition to these, the fluid unit HU includes 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 wheel and rear wheel pressure regulating valves UAf and UAr (=UA) are located above the front wheel and rear wheel inlet valves VIf and VIr (=VI) (the part between the master cylinder CM and the inlet valve VI). Connection paths HSf and HSr (=HS) are provided. The pressure regulating valve UA is a normally open linear electromagnetic valve (also referred to as a "differential pressure valve") whose opening amount (lift amount) is continuously controlled according to the amount of energization (current value).

Front wheel and rear wheel circulation paths HKf and HKr (=HK) are provided to connect the upper part of the pressure regulating valve UA and the lower part of the pressure regulating valve UA. The reflux path HK, which is a fluid path, is provided with front wheel 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 brake fluid BF from the upper part of the pressure regulating valve UA, and discharges the brake fluid BF to the lower part 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, KNr (=KN) in the recirculation path HK as shown by the broken line arrows ("HP→UA→ RC → HP” flow). Here, "reflux" means that the brake fluid BF circulates and returns to its original flow.

The pressure regulating valve UA throttles the reflux KN, and a pressure difference (differential pressure) Sa is generated between the upper part (i.e., master cylinder hydraulic pressure Pm) and the lower part (i.e., the brake fluid pressure Pw) of the pressure regulating valve UA. Ru. Specifically, the controller ECU energizes the normally open pressure regulating valve UA, thereby reducing its opening amount and causing the hydraulic pressure Pw of the wheel cylinder CW to increase from the master cylinder hydraulic pressure Pm. adjusted to. For example, in automatic brake control, when the brake operation member BP is not operated (that is, when "Pm=0"), the wheel cylinder hydraulic pressure Pw is automatically increased by the orifice effect of the pressure regulating valve UA. . In automatic braking control, based on the required deceleration Gt, the larger the required deceleration Gt is, the smaller the opening amount of the pressure regulating valve UA is, and the differential pressure Sa (as a result, the brake fluid pressure Pw) is increased.

Front and rear wheel master cylinder hydraulic pressure sensors are installed above the front and rear wheel pressure regulating valves UAf and UAr to detect the hydraulic pressure (master cylinder hydraulic pressure) Pmf and Pmr of the front and rear wheel hydraulic pressure chambers Rmf and Rmr, respectively. 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 hydraulic pressure sensor PM may be omitted. Alternatively, in order to ensure redundancy, both the master cylinder hydraulic pressure sensor PM and the operation displacement sensor SP may be provided.

In the second embodiment, the inlet valve VI (normally open on/off solenoid valve) and the outlet valve VO (normally closed on/off solenoid valve) are arranged similarly to the first embodiment. In the second embodiment, similarly to the first embodiment, in the rear wheel floating suppression control, the front wheel braking fluid pressure Pwf (as a result, the front wheel braking force Fxf ) is reduced. Specifically, when the cumulative deceleration Gs becomes equal to or greater than the starting deceleration gx, the front wheel inlet valve VIf is closed, the front wheel outlet valve VOf is opened, and the front wheel braking fluid pressure Pwf is decreased.

In the second embodiment, rear wheel floating suppression control may be performed by the front wheel pressure regulating valve UAf. Specifically, when the cumulative deceleration Gs becomes equal to or greater than the starting deceleration gx, the amount of current applied to the front wheel pressure regulating valve UAf is decreased and the amount of opening thereof is increased. As a result, the front wheel braking hydraulic pressure Pwf is reduced, and the front wheel braking force Fxf is reduced. The second embodiment also provides the same effect as described above (execution of highly accurate rear wheel floating suppression control using the cumulative deceleration Gs).

<Other embodiments>
Other embodiments will be described below. Other embodiments also provide the same effects as described above.
In the above embodiment, the hydraulic unit HU via the brake fluid BF is exemplified as the actuator that adjusts the braking torque Tq (result, braking force Fx) of the wheel WH. Alternatively, an electric actuator driven by an electric motor may be employed. In the electric actuator, the rotational power of the electric motor is converted into linear power, thereby pressing the friction member against the rotating member KT. Therefore, braking torque Tq is directly applied by the electric motor to generate braking force Fx, regardless of braking fluid pressure Pw. Furthermore, it may be a composite type in which a hydraulic actuator via brake fluid BF is used for the front wheels WHf, and an electric actuator is used for the rear wheels WHr.

In the above embodiment, a motorcycle is used as the vehicle, and the deceleration calculation device GS and the braking control device SC including the deceleration calculation device GS are applied. Alternatively, the deceleration calculation device GS and the brake control device SC including the deceleration calculation device GS can also be applied to four-wheeled vehicles (passenger cars, trucks, etc.). However, the deceleration calculation device GS and the braking control device SC including the deceleration calculation device GS are more effective in motorcycles. The reason for this will be explained below.

Because motorcycles need to tilt their bodies when turning, the tread surface of automobile tires is flat, whereas the cross-sectional shape of motorcycle tires is close to a circle. . Therefore, in a motorcycle, when the vehicle body is tilted for turning, the tire diameter (distance between the axle and the tire contact surface) becomes smaller, and the detection result of the wheel speed sensor VW (i.e., the wheel speed) Vw becomes smaller. becomes smaller. That is, the wheel speed Vw of the motorcycle includes an error caused by turning (turning error) in addition to a deceleration slip error. Since this turning error is also compensated for by the integrated deceleration Gs, the deceleration calculation device GS and the braking control device SC equipped with the deceleration calculation device GS are more efficient than when applied to four-wheeled vehicles. It is extremely effective to apply it to two-wheeled vehicles.

GS...Deceleration calculation device, XA...Acquisition unit, XB...Calculation unit, XC...Decision unit, SC...Brake control device, BP...Brake 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 speed, Gx...detected deceleration, Ge...calculated deceleration, Gs...integrated deceleration, gs...standard deceleration, dGx...detected slope (time change amount of detected deceleration Gx), dGe...calculated slope (time of calculated deceleration Ge) amount of change), Fx...braking force.

Claims (2)

A vehicle deceleration calculation device applied to rear wheel lifting suppression control that adjusts the braking force acting on the front wheels of the vehicle to suppress lifting of the rear wheels of the vehicle,
an acquisition unit that acquires a detection signal from the deceleration sensor as a detected deceleration;
a calculation unit that calculates the deceleration of the vehicle as a calculated deceleration based on the rotational speed of the wheels of the vehicle;
a determining unit that determines an integrated deceleration that is a deceleration to be applied to the rear wheel floating suppression control based on the detected deceleration and the calculated deceleration;
Equipped with
The determining unit is
The calculated deceleration when the detected deceleration time change amount and the calculated deceleration time change amount match is determined as a reference deceleration, and the time change amount of the detected deceleration is sequentially added to the reference deceleration. A vehicle deceleration calculation device that calculates the cumulative deceleration by integrating the deceleration. A braking control device for a vehicle that adjusts a braking force acting on a front wheel of a vehicle to suppress lifting of a rear wheel of the vehicle,
a deceleration sensor that detects the deceleration of the vehicle as a detected deceleration;
a wheel speed sensor that detects the rotational speed of the vehicle's wheels as a wheel speed;
an actuator that adjusts the braking force;
a controller that controls the actuator;
Equipped with
The controller includes:
Calculating the deceleration of the vehicle as a calculated deceleration based on the wheel speed,
determining the calculated deceleration as a reference deceleration when the amount of change over time of the detected deceleration and the amount of change over time of the calculated deceleration match;
calculating an integrated deceleration by sequentially integrating the amount of change over time in the detected deceleration on the reference deceleration;
A braking control device for a vehicle that reduces the braking force when the cumulative deceleration exceeds a threshold value.