JP2016203677A - Brake control device or brake control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brake control device or brake control method which can suppress the lowering of vehicle deceleration at substitution.SOLUTION: A brake controller 1 (brake control device) of a vehicle having a motor unit (electric brake device) which makes a wheel generate an electric brake force, and a liquid-pressure brake unit (friction brake device) which makes the wheel generate a friction brake force by being operated. The brake controller comprises: a driver requirement brake force calculation part 31 (target brake force calculation part) which calculates a driver requirement brake force Fd (target brake force); a regeneration torque target value decision part 33 which performs substitution as control for decreasing an electronic brake force, and increasing a friction brake force so as to obtain the calculated Fd when a prescribed condition (Tmax<T_Fd) is established; a target liquid-pressure decision part 34; a pre-substitution boosted-pressure calculation part 36 (substitution control part); a pre-substitution boosted-pressure determination part 35 which operates the liquid-pressure brake unit prior to the reduction of the electric brake force; and a pre-substitution boosted-pressure addition part 36 (friction brake control part).SELECTED DRAWING: Figure 2

Description

  The present invention relates to vehicle braking control.

  A braking control device that switches from electric braking to friction braking when a predetermined condition is satisfied is known (for example, Patent Document 1).

JP2013-86626A

  Conventionally, at the time of replacement, there is a possibility that the vehicle deceleration may be reduced due to a response delay of the friction braking device.

  The braking control device of the present invention preferably operates the friction braking device before reducing the electric braking force.

  Therefore, a decrease in vehicle deceleration can be suppressed.

It is a block diagram of the braking / driving control system of the embodiment. It is a block diagram of the regeneration cooperation control part of an embodiment. It is a block diagram of the hydraulic pressure calculation part after clearance correction of an embodiment. The map for determining the offset hydraulic pressure of embodiment is shown. It is a block diagram of a driver demand braking force calculation part of an embodiment. The map for determining the regenerative torque limit value of embodiment is shown. It is a block diagram of the regeneration torque target value determination part of embodiment. It is a block diagram of the target hydraulic pressure determination part of embodiment. It is a block diagram of the pre-replacement pressure increase determination unit of the embodiment. The map for determining the pressure increase start torque deviation of embodiment is shown. It is a block diagram of the pre-replacement pressure increase addition part of embodiment. It is a characteristic view which shows the relationship between a hydraulic pressure and deceleration. It is a time chart in the conventional regenerative cooperative control. It is a time chart in regenerative cooperative control of an embodiment. It is a time chart in regenerative cooperative control when braking operation is performed at the low vehicle speed of embodiment.

  EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing the braking control apparatus and braking control method of this invention is demonstrated based on drawing.

[Embodiment 1]
(Constitution)
First, the configuration will be described. The braking control device of this embodiment is applied to a braking / driving control system in a vehicle. The vehicle is an electric vehicle. The vehicle may be a hybrid vehicle. The vehicle includes a motor unit, a hydraulic braking unit, a hydraulic control unit HU, and various controllers. The motor unit includes a motor, a battery, a power conversion device (inverter), and the like. The motor is an electric motor connected to wheels via a shaft or the like, and an AC synchronous motor, for example, is used. The motor may be an in-wheel motor. The motor functions as a motor that supplies driving torque to the wheels, and also functions as a generator that generates electricity by being rotated by torque from the wheels. In the latter scene, the motor unit is a regenerative braking device (electric braking device) and generates a regenerative braking force (electric braking force) on the wheels.

  The hydraulic braking unit is a friction braking device (hydraulic braking device) that is provided for each predetermined wheel and generates a friction braking force (hydraulic braking force) on the wheel by operating by hydraulic pressure. The hydraulic braking unit is a disc brake and includes a rotor and a caliper. The rotor is a rotating member (disk) that rotates together with the wheels. The caliper includes a pad, a piston, and a cylinder. The pad is a friction member arranged with a predetermined clearance with respect to the rotor (when the caliper is not operated). The piston pushes the pad toward the rotor by the hydraulic pressure supplied to the cylinder. As the pad moves and contacts the rotor, a braking force (friction braking force) due to friction is generated on the wheel. The hydraulic braking unit may be a drum brake, a drum may be used instead of the rotor, and a shoe may be used instead of the pad. The hydraulic control unit HU is connected to the master cylinder and each caliper via a brake pipe. The HU is a unit having a pump motor as a fluid pressure generation source, a fluid pressure circuit, an electromagnetic valve for opening and closing a fluid path, a fluid pressure sensor for detecting fluid pressure in the fluid pressure circuit, and the like. The HU can supply hydraulic pressure to each caliper individually and can operate each hydraulic braking unit individually. The various controllers include a motor controller MC that controls the motor, a braking control controller 1 that controls the HU, and a vehicle integrated controller VCM that controls the braking / driving state of the vehicle.

  FIG. 1 shows the configuration of the braking / driving control system. The braking / driving control system has the various controllers described above. MC receives or receives an input from the sensor, and detects or calculates the torque (actual motor torque T) and the rotational speed (actual motor rotational speed N) actually generated by the motor. The MC receives the motor torque command T * from the VCM, controls T, and outputs T and N to the VCM. The brake controller 1 detects or calculates the driver's braking operation amount (hereinafter simply referred to as detection) in response to an input from the sensor. The braking operation amount is, for example, a brake pedal stroke amount BPS. The braking operation amount may be a master cylinder hydraulic pressure or the like. The braking controller 1 receives the hydraulic pressure sensor value Ps from the HU, and outputs the drive current I of the solenoid valve and the pump motor to the HU. The VCM outputs regenerative cooperative control permission signals CLR, T, and N to the braking controller 1. The braking controller 1 receives an input such as CLR and calculates a regenerative torque target value tT. The regenerative torque is an electric braking torque corresponding to a regenerative braking force (electric braking force). The VCM receives tT input from the braking controller 1 and outputs a regenerative torque command T * to the MC.

  The braking controller 1 includes a driver request equivalent hydraulic pressure calculation unit 2, a regenerative cooperation control unit 3, and a boost control unit 4. When a driver's braking operation is detected, the driver request equivalent hydraulic pressure calculation unit 2 sets a braking operation detection flag FLG1 (for example, the flag is changed from 0 to 1, and so on). Further, the driver request equivalent hydraulic pressure Pd is calculated based on the detected braking operation amount BPS. Regenerative cooperative control unit 3 receives inputs such as FLG1 and Pd from driver request equivalent hydraulic pressure calculation unit 2 and CLR from VCM, and calculates regenerative cooperative hydraulic pressure commands P * and tT. The boost control unit 4 receives the detected BPS, Pd from the driver request equivalent hydraulic pressure calculation unit 2, and P * from the regenerative cooperative control unit 3, and calculates a final hydraulic pressure command. , I is output to HU. The regenerative cooperative control unit 3 calculates when a predetermined condition is satisfied when the driver is performing a braking operation, the hydraulic braking unit is inactive, and the regenerative braking device is operating (regenerative braking force is generated). Regenerative cooperative control (hereinafter referred to as replacement (control)) is performed to reduce the regenerative braking force and increase the frictional braking force so as to realize the target braking force (driver required braking force Fd). FIG. 2 shows a configuration of the regeneration cooperative control unit 3. The regenerative cooperative control unit 3 includes a clearance-corrected hydraulic pressure calculation unit 30, a driver required braking force calculation unit 31, a regenerative torque limit value determination unit 32, a regenerative torque target value determination unit 33, and a target hydraulic pressure determination unit. 34, a pre-replacement pressure increase determination unit 35, and a pre-replacement pressure increase addition unit 36.

  The hydraulic pressure calculation unit 30 after clearance correction receives the input of Pd from the hydraulic pressure calculation unit 2 corresponding to the driver request, and calculates the hydraulic pressure Pd_h after clearance correction and the offset pressure increase value (pressure increase liquid pressure target value) tΔP. calculate. FIG. 3 shows the configuration of the fluid pressure calculation unit 30 after clearance correction. The post-clearance hydraulic pressure calculation unit 30 includes an offset hydraulic pressure determination unit 300, a subtraction unit 301, a first comparison unit 302, and a second comparison unit 303. The offset hydraulic pressure determination unit 300 determines an offset hydraulic pressure (increase in partial pressure) ΔP based on Pd. FIG. 4 shows a map used by the offset hydraulic pressure determination unit 300. When Pd is less than the predetermined value Pd1, ΔP is a value corresponding to Pd, and when Pd is high, ΔP is larger than when it is low. Specifically, ΔP is proportional to Pd. When Pd is equal to or greater than Pd1, ΔP becomes a constant value ΔP1 regardless of the size of Pd. The subtractor 301 calculates a value obtained by subtracting ΔP from Pd. The first comparison unit 302 compares 0 with a value obtained by subtracting ΔP from Pd, and outputs the larger one of the two values as the fluid pressure Pd_h after clearance correction. The second comparison unit 303 compares Pd and ΔP, and outputs the smaller one of them as an offset pressure increase value tΔP.

  The driver required braking force calculation unit 31 receives the input of FLG1 from the driver request equivalent hydraulic pressure calculation unit 2 and the input of Pd_h from the hydraulic pressure calculation unit 30 after clearance correction, and calculates the driver required braking force Fd. calculate. FIG. 5 shows a configuration of the driver request braking force calculation unit 31. The driver required braking force calculation unit 31 includes a comparison unit 310, a switch unit 311, a front and rear wheel distribution unit 312, a front wheel side integration unit 313, a front left and right wheel distribution unit 314, a rear wheel side integration unit 315, A rear left / right wheel distributor 316 and an adder 317 are provided. The comparison unit 310 compares Pd_h with 0 and outputs the larger of the two. The switch unit 311 outputs the value input from the comparison unit 310 when FLG1 is standing, and outputs 0 when FLG1 is not standing. The front and rear wheel distribution unit 312 distributes the hydraulic pressure value input from the switch unit 311 to the front wheel side and the rear wheel side at a predetermined ratio. The front wheel side integration unit 313 multiplies a predetermined front wheel braking coefficient Cbf by the hydraulic pressure value distributed to the front wheel side to convert this into braking force. The front left and right wheel distribution unit 314 distributes the braking force value input from the front wheel side integration unit 313 to the front left wheel side and the front right wheel side at a predetermined ratio. The rear wheel side integrating unit 315 multiplies the predetermined rear wheel braking coefficient Cbr by the hydraulic pressure value distributed to the rear wheel side to convert this into braking force. The rear left and right wheel distribution unit 316 distributes the braking force value input from the rear wheel side integration unit 315 to the rear left wheel side and the rear right wheel side at a predetermined ratio. The adding unit 317 calculates the driver required braking force Fd by adding the braking force values input from the front left and right wheel distributing unit 314 and the rear left and right wheel distributing unit 316.

  Regenerative torque limit value determining unit 32 receives an input of N from VCM, and determines an upper limit value (hereinafter referred to as a regenerative torque limit value) Tmax of the magnitude of the regenerative torque. FIG. 6 shows a map used by the regenerative torque limit value determination unit 32. The horizontal axis indicates the actual motor rotation speed N (rpm). The vertical axis represents the regenerative torque T (Nm). A thin solid line indicates a regenerative torque limit value Tmax1 set by regenerative cooperative control. The dotted line indicates the regenerative torque limit value Tmax2 by the motor / battery. The thick solid line indicates the final regenerative torque limit value Tmax. Note that the alternate long and short dash line indicates the regenerative torque (driver-required braking force equivalent regenerative torque T_Fd) corresponding to Fd. Tmax1 is 0 when N ranges from 0 to the first predetermined value N0, and is proportional to N when N is greater than or equal to N0 (increases at a first rate as N increases). N corresponds to the vehicle speed V. That is, Tmax1 is a parameter for switching from regenerative braking to hydraulic braking at low vehicle speeds, and is set to a value corresponding to V. Tmax2 is 0 when N is in the range from 0 to N0, and is proportional to N when N is greater than or equal to N0 and less than the second predetermined value N1 (increase by a second ratio as N increases) Become). Tmax2 is a constant value Tmax0 regardless of N in a range where N is N1 or more. Tmax2 is a parameter for protecting the motor unit, and is set to a value corresponding to N. The regenerative torque limit value determining unit 32 sets the smaller one of Tmax1 and Tmax2 as a final regenerative torque limit value (hereinafter simply referred to as a regenerative torque limit value) Tmax. In the map of FIG. 6, Tmax is Tmax1 in a range less than N2 where a thin solid line indicating Tmax1 and a dotted line indicating Tmax2 intersect. Tmax is Tmax2 (Tmax0) in the range of N2 or more.

  Regenerative torque target value determination unit 33 receives Fd input from driver-requested braking force calculation unit 31 and Tmax input from regenerative torque limit value determination unit 32, and determines regenerative torque target value tT. FIG. 7 shows the configuration of the regenerative torque target value determination unit 33. The regenerative torque target value determination unit 33 includes an integration unit 330 and a comparison unit 331. The accumulating unit 330 converts this into torque (driver-required braking force equivalent regenerative torque T_Fd) by multiplying Fd by a predetermined braking force-torque conversion constant Cf-t. The comparison unit 331 compares T_Fd and Tmax, and outputs the smaller of them as tT. For example, in the map of FIG. 6, when T_Fd exceeds Tmax0, Tmax is tT in the entire range of N. When T_Fd is lower than Tmax0, Tmax is tT in a range of less than N where the alternate long and short dash line indicating T_Fd and the thick solid line indicating Tmax intersect, and T_Fd is tT in the range of N or more intersecting.

  The target hydraulic pressure determination unit 34 receives the input of T from the VCM and the input of Fd from the driver request braking force calculation unit 31, and determines the regenerative cooperation target hydraulic pressure tP. FIG. 8 shows the configuration of the target hydraulic pressure determination unit 34. The target hydraulic pressure determination unit 34 includes a first integration unit 340, a subtraction unit 341, and a second integration unit 342. The first integrating unit 340 converts this to a braking force (actual regenerative braking force Fr) by multiplying T by a predetermined torque-braking force conversion constant Ct-f. The subtractor 341 calculates the target friction braking force tFf by subtracting Fr from Fd. The second integrating unit 342 multiplies tFf by a predetermined braking force-torque conversion constant Cf-t to convert this into hydraulic pressure (regenerative coordination target hydraulic pressure tP).

  The pre-replacement pressure increase determination unit 35 inputs Tmax from the regenerative torque limit value determination unit 32, inputs Tt (T_Fd) from the regenerative torque target value determination unit 33, and the driver request equivalent hydraulic pressure calculation unit 2 In response to the input of Pd, it is determined whether or not to increase pressure before replacement. If a positive determination is made, the pre-replacement pressure increase control flag FLG2 is set. FIG. 9 shows the configuration of the pre-replacement pressure increase determination unit 35. The pre-replacement pressure increase determination unit 35 includes a subtraction unit 350, a first comparison unit 351, a pressure increase start torque deviation determination unit 352, and a second comparison unit 353. The subtraction unit 350 calculates the regenerative torque deviation ΔT by subtracting T_Fd from Tmax. The first comparison unit 351 compares δT with 0 and outputs the larger of the two. The pressure increase start torque deviation determining unit 352 determines the pressure increase start torque deviation ΔT based on Pd. ΔT is a threshold value for determining whether or not to perform caliper (cylinder) pressure increase before replacement. FIG. 10 shows a map used by the pressure increase start torque deviation determining unit 352. When Pd is less than the predetermined value Pd2, ΔT becomes a value corresponding to Pd. When Pd is high, ΔT is larger than when Pd is low. Specifically, ΔT is proportional to Pd. When Pd is equal to or greater than Pd2, ΔT is a constant value regardless of the size of Pd. The second comparison unit 353 compares the value input from the first comparison unit 351 with ΔT, and when the former falls below the latter, sets the pre-replacement pressure increase control flag FLG2.

  The pre-replacement pressure increase addition unit 36 receives tP input from the target hydraulic pressure determination unit 34, tΔP input from the hydraulic pressure calculation unit 30 after clearance correction, FLG1 input from the driver request equivalent hydraulic pressure calculation unit 2, In response to the input of FLG2 from the pre-replacement pressure increase determination unit 35, the regeneration cooperative hydraulic pressure command P * is calculated. FIG. 11 shows a configuration of the pre-replacement pressure increase addition unit 36. The pre-replacement pressure increase addition unit 36 includes a first switch unit 360, a second switch unit 361, a third switch unit 362, a subtraction unit 363, a comparison unit 364, a first addition unit 365, and a second addition. Part 366. The first switch unit 360 outputs 1 when FLG2 is standing, and outputs the previous value of the output of the second switch unit 361 when FLG2 is not standing. The second switch unit 361 outputs an input from the first switch unit 360 when FLG1 is standing, and outputs 0 when FLG1 is not standing. The third switch unit 362 outputs tΔP when the input from the second switch unit 361 is 1, and outputs 0 when the input from the second switch unit 361 is 0. That is, tΔP is output when FLG2 and FLG1 are standing together, and 0 is output otherwise. The subtracting unit 363 calculates a value obtained by subtracting the previous value of the output of the first adding unit 365 (offset pressure increase command tΔP * described later) from the value input from the third switch unit 362. The comparison unit 364 compares the value input from the subtraction unit 363 with a predetermined pressure increase rate value dP, and outputs the smaller one of the two. The first addition unit 365 adds the value input from the comparison unit 364 to the previous value of the output (tΔP *) of the first addition unit 365, so that the current offset pressure increase command (pressure increase partial pressure command) ) Calculate tΔP *. That is, tΔP * is basically calculated by accumulating dP. The second addition unit 366 calculates P * by adding tΔP * input from the first addition unit 365 to tP. That is, when tΔP is added to tP, basically, dP is gradually added to tP until the cumulative total of dP reaches tΔP.

(Function)
Next, the function and effect will be described. The hydraulic braking unit does not generate the deceleration G of the vehicle unless the hydraulic pressure exceeds a certain level. This is because there is a hydraulic pressure region where friction braking force is not generated due to the clearance between the rotor and the pad. FIG. 12 shows the relationship between the hydraulic pressure P and the deceleration G. In actual friction braking, as indicated by the solid line, G does not occur in the hydraulic pressure region from P0 to P1, and G occurs when P becomes P1 or more. On the other hand, in the conventional regenerative cooperative control, as indicated by the dotted line, the hydraulic pressure P at which G is generated is set to P0 instead of P1. Therefore, at the start of switching to reduce the regenerative braking force and increase the friction braking force, no G due to the friction braking force is generated until P rises from P0 to P1, while G due to the friction braking force occurs. The regenerative braking force is reduced on the assumption that For this reason, the braking force as a whole is temporarily insufficient, and G decreases. This temporary decrease in G may give the passenger a sense of incongruity and may lead to a decrease in ride comfort. For example, when switching is performed in a state where the amount of braking operation by the driver is constant (because the vehicle speed decreases, etc.), there is a high possibility that the driver will feel uncomfortable. In addition, if P rises to P3 in FIG. 12, the drop of G of the solid line with respect to a dotted line will be eliminated. Therefore, the temporary shortage of braking force as a whole is also eliminated.

  FIG. 13 is a time chart showing a state in which the decrease in G occurs at the time of replacement in the conventional regenerative cooperative control. At time t1, the braking operation amount BPS exceeds the threshold value BPS *. It is determined that a braking operation has been performed, and regenerative cooperative control is started. After t1, until t2, the vehicle speed V is sufficiently high, so the driver-requested braking force Fd corresponding to BPS is provided only by the regenerative braking force. The braking force F_tT corresponding to the regenerative torque target value (which can be equated with the actual torque T generated by the motor) matches Fd. G corresponding to the regenerative braking force F_tT is generated, and V gradually decreases. At time t2, V falls below the replacement start vehicle speed Vst. Therefore, replacement is started. After t2, switching is executed until t3 when V becomes the switching end vehicle speed Ved or less. That is, F_tT is decreased and F_tP is increased so as to realize Fd. F_tP is a friction braking force corresponding to the target hydraulic pressure tP in the regenerative cooperative control. Here, in the hydraulic pressure region from P0 to P3, tP is set on the assumption that G is generated according to P (as shown by the dotted line in FIG. 12). After time t2, when tP is increased from P0, the friction braking force that is actually generated is shorter than F_tP until tP increases to P3. For this reason, immediately after t2, the braking force as a whole is temporarily less than Fd and G decreases.

  On the other hand, the braking control apparatus according to the present embodiment outputs an offset pressure increase command tΔP * before starting replacement, and reduces the clearance between the rotor and the pad in advance. For example, a predetermined hydraulic pressure (offset hydraulic pressure ΔP) higher than P0 in FIG. 12 and up to P1 is output. As a result, a friction braking force is actually generated according to the increase in tP (P *) relatively early after the start of replacement, and this actually generated friction braking force follows F_tP relatively early. It becomes like this. Therefore, temporary decrease in G is suppressed. FIG. 14 is a time chart showing how the decrease in G is suppressed during switching in the regenerative cooperative control of the present embodiment. Only differences from FIG. 13 will be described. The regenerative torque limit value Tmax is used to determine the replacement start. When the deviation ΔT between Tmax and the required braking force equivalent regenerative torque T_Fd becomes 0 (that is, Tmax is less than T_Fd, the same applies hereinafter), replacement is started. As the vehicle speed V (actual motor speed N) decreases, Tmax begins to decrease at time t11, and δT also begins to decrease. Since ΔT becomes 0 at time t2, replacement is started. A caliper pressure increase command is issued at time t12 before starting replacement. That is, at time t12, ΔT is less than the threshold value ΔT, so pressure increase is started. Thereafter, the pressure is increased until time t2. Specifically, FLG2 is set when ΔT falls below ΔT at t12. The regenerative cooperative hydraulic pressure command P * is calculated by adding the offset pressure increasing command tΔP * that gradually increases at the pressure increase rate value dP to the regenerative cooperative target hydraulic pressure tP. After t12, tP is 0 until t2 at which switching is started, so P * matches tΔP *. It is assumed that P * becomes tΔP (ΔP is output) at t2. By outputting tΔP * and increasing the pressure at time t12 to t2 before starting replacement, the clearance becomes small at the time of starting replacement at t2. Therefore, the friction braking force is actually generated relatively early immediately after t2 when the replacement is started. Therefore, a temporary decrease in G is suppressed.

  As described above, when δT becomes 0, switching is started (time t2). Since sufficient regenerative braking force cannot be generated at low vehicle speeds (low motor speed), switching to hydraulic braking is performed. The replacement end vehicle speed Ved for completing the switching is set in advance. In the regenerative cooperative control, the regenerative torque limit value Tmax1 is set so that the replacement can be completed when the vehicle speed V becomes Ved when the replacement is performed with the maximum pressure increase gradient of the caliper. Here, the caliper maximum pressure increase gradient is the upper limit value of the caliper pressure increase gradient by the hydraulic pressure control unit HU. Preferably, the pressure increase is such that the operating sound of the pump motor in the HU does not give the passenger a sense of incongruity. It is a gradient. As shown in FIG. 6, Tmax1 is set according to the actual motor rotational speed N (vehicle speed V). In the range where N is N0 or less, Tmax1 is set to 0 and regenerative braking is prohibited. In the range where N is N0 or more, Tmax1 is set to increase as N increases. The gradient (first ratio) of Tmax1 with respect to N is determined according to the maximum pressure increase gradient. It is assumed that the time it takes for V to decrease to Ved as N increases, but as N increases, Tmax1 increases, so the deviation δT between Tmax1 and T_Fd increases, and the start of replacement is suppressed. The Therefore, regeneration can be performed longer and more energy can be recovered. In addition, it is assumed that the time until V decreases to Ved is shorter as N is lower. As N is lower, Tmax1 is reduced, so that ΔT is reduced and the start of replacement is promoted. Therefore, it is possible to execute replacement appropriately. The characteristic of Tmax1 (gradient with respect to N, etc.) can be set as appropriate for each vehicle. Note that when determining the final Tmax, not only Tmax1 but also Tmax2 is used. Tmax2 is a constant value Tmax0 in a range where N is greater than or equal to N1. That is, the regenerative torque is limited to Tmax0 or less. Thereby, a motor unit can be protected. Note that the replacement may be started when the calculated or detected vehicle speed V falls below a preset vehicle speed (replacement start vehicle speed Vst). In this case, Vst may be changed according to a parameter (braking operation amount BPS or the like) reflecting the driver's required braking force.

  As described above, the pressure increase before switching is started after the driver starts the braking operation. Therefore, it is possible to suppress the occurrence of unnecessary friction braking force (unnecessary load) due to the start of pressure increase at an excessively early stage before replacement. When ΔT falls below ΔT, pressure increase before replacement is started (time t12). As shown in FIG. 10, in the range where Pd is equal to or less than Pd2, ΔT is set to increase as Pd increases. It is assumed that the driver is requesting a larger G as Pd is higher. As Pd is higher, ΔT is increased, so that pressure increase is started earlier than before replacement. Therefore, since the clearance is more reliably reduced and the decrease in G is suppressed, the uncomfortable feeling can be more effectively reduced. Further, as Pd is lower, there is a greater possibility that the generation of unnecessary friction braking force will give a sense of incongruity. However, as Pd is lower, ΔT becomes smaller, so that pressure increase is started immediately before the start of replacement. Therefore, generation | occurrence | production of an unnecessary friction braking force is suppressed more reliably. It should be noted that when Pd becomes higher to some extent (Pd2) or more, ΔT is set to be a constant value ΔT1 without increasing any more. Therefore, it is possible to suppress the occurrence of unnecessary friction braking force due to the start of pressure increase at an excessively early stage before replacement.

  In order to keep the clearance as small as possible before starting the replacement (pumping), for example, it is preferable to output P1 in FIG. However, the fluid pressure (offset fluid pressure ΔP) that does not generate excessive friction between the rotor and the pad and the clearance becomes 0 is actually due to running conditions such as rain, pad wear, etc. Because it fluctuates, it is not easy to specify. Therefore, for example, as shown in FIG. 4, the offset hydraulic pressure ΔP is set in advance. ΔP is set to be a constant value ΔP1 when Pd is increased to some extent (Pd1) or more. For example, ΔP1 is set to a value such that the clearance is substantially zero and the frictional force generated between the rotor and the pad is substantially zero under predetermined traveling conditions. ΔP1 can be set by experiment or simulation. Thus, by setting ΔP to be equal to or less than ΔP1, it is possible to suppress a situation in which the clearance is excessively small (the pressing force of the pad or the like is excessively large) and unnecessary friction braking force is generated before replacement. In a range where Pd is equal to or less than Pd1, ΔP is set to increase as Pd increases. The higher the Pd, the greater the possibility that the decrease in G will give a sense of incongruity. However, the higher the Pd, the greater the ΔP, so that the clearance is more reliably reduced and the decrease in G is suppressed. Therefore, a sense of incongruity can be reduced more effectively. In addition, the lower the Pd, the greater the possibility that the generation of unnecessary friction braking force will cause a sense of incongruity, but the lower the Pd, the smaller ΔP will reduce the generation of unnecessary friction braking force more reliably. The

  When calculating P * in the pre-replacement pressure increase addition unit 36, the clearance-corrected hydraulic pressure Pd_h calculated by subtracting ΔP from Pd in the clearance-corrected hydraulic pressure calculation unit 30 (tP calculated based on this) Is used. Therefore, even if P is increased to ΔP before replacement (time t12 to t2), ΔP is subtracted in advance from tP (P *) used at the time of replacement (time t2 to t3). Therefore, the actual P is prevented from becoming excessive.

  When the driver performs braking operation at low vehicle speed, or when the braking operation is suddenly performed (when the brake pedal is suddenly depressed), the pressure is increased before switching (P * = tΔP * There are times when it is unavoidable to start switching before t reaches ΔP. At this time, if the pre-replacement pressure increase is to be completed before the start of replacement (P * should be set to tΔP in advance), the pre-replacement pressure increase gradient becomes excessively large, which causes G to fluctuate and shock. May occur. On the other hand, in the apparatus of this embodiment, it is assumed that the pressure increase before the replacement does not have to be completed at the start of the replacement, and the pressure increase gradient before the replacement (dP which is the increase gradient of tΔP *) is a constant value. It is. FIG. 15 is a time chart in the case where the driver performs a braking operation at a low vehicle speed in the regenerative cooperative control of the present embodiment, and the pressure increase before the replacement is not completed at the start of the replacement. Only differences from FIG. 14 will be described. The braking operation is performed at a low vehicle speed. Therefore, the difference between the vehicle speed V during the braking operation (time t1) and the replacement start vehicle speed Vst is small. That is, the replacement is started relatively early. The period from time t12 when δT falls below ΔT and pressure increase before switching to time t2 when δT becomes 0 and switching is started is short. In pressure increase before replacement, tΔP * is increased by dP. At time t21 after elapse of a predetermined time from t12, tΔP * reaches tΔP, and the pressure increase before the replacement is completed. At t21, replacement has already started. dP is set to a predetermined value at which the occurrence of the shock is suppressed. Therefore, the occurrence of the shock due to the pressure increase before replacement is suppressed. As described above, the temporary decrease in G is suppressed by increasing the pressure before time t2 when the replacement is started. Note that dP is not a constant value, and may be a value that changes according to Pd or tΔP. For example, dP may be changed so that dP becomes larger when tΔP is larger than when tΔP is small. In this case, the pressure increase before the replacement can be completed at a more appropriate timing, and the above-described effects can be obtained by setting dP within a range in which the occurrence of the shock is suppressed.

(effect)
Hereinafter, effects exhibited by the braking control device or the braking control method of the present embodiment will be listed.
(1) A vehicle including a motor unit (electric braking device) that generates electric braking force on wheels and a hydraulic braking unit (friction braking device) that generates friction braking force on wheels by operating. A braking control controller 1 (braking control device) of a driver requested braking force calculation unit 31 (target braking force calculation unit) for calculating a driver requested braking force Fd (target braking force), and a predetermined condition (Tmax When <T_Fd) is established, a regenerative torque target value determining unit 33, a target hydraulic pressure determining unit 34, which performs switching, which is a control for decreasing the electric braking force and increasing the friction braking force so as to realize the calculated Fd, and Pre-replacement pressure increase addition unit 36 (replacement control unit), pre-replacement pressure increase determination unit 35 that operates the hydraulic braking unit before reducing the electric braking force, and pre-replacement pressure increase addition unit 36 (friction braking control unit) And with.
By operating the hydraulic braking unit before reducing the electric braking force, the decrease in the deceleration G can be suppressed.

(9) The braking controller 1 (vehicle braking control device) calculates the driver request braking force Fd (target braking force) based on the brake pedal stroke amount BPS (driver braking operation state). The regenerative braking force generated by the power calculation unit 31 (target braking force calculation unit) and the motor unit (regenerative braking device) provided in the vehicle is calculated so that the calculated Fd is obtained, and a predetermined condition (Tmax <T_Fd ) Is established, the regenerative braking force is reduced, and before the reduction of the regenerative braking force, a regenerative torque target value determination unit 33 that performs switching control to increase the friction braking force generated by the hydraulic braking unit (friction braking device), A target hydraulic pressure determination unit 34, a pre-replacement pressure increase determination unit 35, and a pre-replacement pressure increase addition unit 36 (replacement friction braking control unit) are provided.
By increasing the friction braking force before reducing the regenerative braking force, the decrease in the deceleration G can be suppressed.

(2) The pre-replacement pressure increase determination unit 35 and the pre-replacement pressure increase addition unit 36 (friction braking control unit, replacement friction brake control unit) are connected to the hydraulic braking unit (Tmax <T_Fd) before the predetermined condition (Tmax <T_Fd) is satisfied. Activate the friction braking device.
By operating the hydraulic braking unit prior to the replacement, it is possible to suppress the decrease in the deceleration G during the replacement.

(3) (11) The hydraulic braking unit (friction braking device) includes a rotor that rotates together with the wheel, a pad that is arranged with a predetermined clearance with respect to the rotor, and generates friction braking force by contacting the rotor. The pre-replacement pressure increase determination unit 35 and the pre-replacement pressure increase addition unit 36 (friction braking control unit, replacement friction brake control unit) reduce clearance before a predetermined condition (Tmax <T_Fd) is satisfied. Actuate the hydraulic braking unit.
By operating the hydraulic braking unit so as to reduce the clearance, it is possible to more reliably suppress the decrease in the deceleration G at the time of replacement.

(6) The switching end vehicle speed Ved, which is the vehicle speed at which the switching by the regenerative torque target value determination unit 33, the target hydraulic pressure determination unit 34, and the pre-replacement pressure increase addition unit 36 (replacement control unit, replacement friction braking control unit) is terminated. Set the regenerative torque limit value to set the limit value Tmax so that the replacement with Ved is completed when the electric braking torque (regenerative torque), which is the torque equivalent to the electric braking force, is reduced along the limit value Tmax. The unit 32 (electric braking torque limit value setting unit) is provided, and the predetermined condition is when Tmax falls below the driver-requested braking force equivalent regenerative torque T_Fd (electric braking torque corresponding to the target braking force).
If the limit value Tmax (which is set to end the replacement with Ved) falls below T_Fd, the replacement can be performed with high accuracy by performing the replacement.

(7) (15) The pre-replacement pressure increase determination unit 35 and the pre-replacement pressure increase addition unit 36 (friction braking control unit, replacement friction brake control unit) are the driver-requested braking force equivalent regenerative torque T_Fd (equivalent to the target braking force). In the state where the limit value Tmax is larger than the electric braking torque), when the deviation ΔT between T_Fd and Tmax becomes equal to or less than the predetermined deviation ΔT, the operation of the hydraulic braking unit (friction braking device) is started.
By starting the operation of the hydraulic braking unit when ΔT becomes equal to or smaller than ΔT, the operation start timing of the hydraulic braking unit can be appropriately set. For example, useless load can be suppressed.

(8) (14) The driver required braking force calculating unit 31 (target braking force calculating unit) is configured to provide the driver required braking force Fd (target braking force) according to the brake pedal stroke amount BPS (driver braking operation state). ) And a pre-replacement pressure increase determination unit 35 and a pre-replacement pressure increase addition unit 36 (friction braking control unit, replacement friction brake control unit) are set to a predetermined condition (Tmax <T_Fd) after the driver starts the braking operation. The hydraulic braking unit (friction braking device) is operated before the above is established.
By operating the hydraulic brake unit after the driver starts the braking operation, the operation start timing of the hydraulic brake unit can be set appropriately. For example, useless load can be suppressed.

(10) Based on the brake pedal stroke amount BPS (driver's braking operation state), the driver's required braking force Fd (target braking force) is calculated, and the motor installed in the vehicle to realize the calculated Fd A vehicle braking control method for operating a unit (regenerative braking device) and a hydraulic braking unit (friction braking device), wherein the hydraulic braking unit is inactive and is regenerated by a motor unit during a driver's braking operation. When the braking force is generated, the regenerative braking force is reduced when a predetermined condition (Tmax <T_Fd) is satisfied, and the hydraulic braking unit is operated prior to the reduction of the regenerative braking force.
By operating the hydraulic braking unit prior to the reduction of the regenerative braking force, the reduction in the deceleration G can be suppressed.

(16) The operation of the hydraulic braking unit (friction braking device) is performed after a driver's braking operation is started and before a predetermined condition (Tmax <T_Fd) is satisfied.
The operation of the hydraulic braking unit is performed after the driver starts the braking operation, whereby the operation start timing of the hydraulic braking unit can be appropriately set. For example, useless load can be suppressed.

[Embodiment 2]
In the present embodiment, the predetermined value ΔP1 of the offset hydraulic pressure ΔP is set to a value such that the rotor and the pad are in contact with each other under predetermined traveling conditions. As in the first embodiment (FIG. 4), ΔP is set to a constant value ΔP1 when Pd increases to some extent (Pd1) or more. Other configurations are the same as those of the first embodiment. Therefore, if ΔP1 occurs before replacement, the rotor and the pad come into contact with each other in advance, and a minute friction braking force is generated. For this reason, the temporary fall of G is suppressed more reliably. Note that ΔP1 is preferably set to a value that does not excessively press the rotor and the pad and suppresses the generation of unnecessary friction braking force (waste load).

The effects of this embodiment are listed below.
(4) (12) The pre-replacement pressure increase determination unit 35 and the pre-replacement pressure increase addition unit 36 (friction braking control unit, replacement friction brake control unit) are configured so that the predetermined condition (Tmax <T_Fd) is A friction braking force equal to or less than a predetermined value (a friction braking force corresponding to ΔP1) is generated by a pressure braking unit (friction braking device).
By generating the friction braking force in advance, the delay in the operation of the friction braking device can be reduced, and the reduction in the deceleration G can be more effectively suppressed. Moreover, the increase of load can be suppressed by making the friction braking force to generate into a predetermined value or less.

(5) (13) The pre-replacement pressure increase determination unit 35 and the pre-replacement pressure increase addition unit 36 (friction braking control unit, replacement friction brake control unit) are connected to the rotor before a predetermined condition (Tmax <T_Fd) is satisfied. Touch the pad.
By bringing the rotor and the pad into contact with each other in advance, the delay in the operation of the friction braking device can be reduced, and the reduction in the deceleration G can be more effectively suppressed.

[Other Embodiments]
As mentioned above, although the form for implementing this invention has been demonstrated based on embodiment, the concrete structure of this invention is not limited to embodiment, The design change of the range which does not deviate from the summary of invention Are included in the present invention. For example, the conditions for starting replacement may be defined using appropriate parameters other than the regenerative torque deviation ΔT and the vehicle speed V.

1 Braking control controller (braking control device)
31 Driver required braking force calculation unit (target braking force calculation unit)
32 regenerative torque limit value determining unit (electric braking torque limit value setting unit)
33 Regenerative torque target value determination unit (replacement control unit, replacement friction braking control unit)
34 Target hydraulic pressure determination unit (replacement control unit, replacement friction braking control unit)
35 Pre-replacement pressure increase determination unit (friction braking control unit, replacement friction braking control unit)
36 Pre-replacement pressure increase addition unit (replacement control unit, friction braking control unit, replacement friction braking control unit)

Claims (10)

An electric braking device for generating an electric braking force on the wheel;
A braking control device for a vehicle, comprising: a friction braking device that generates a friction braking force with respect to a wheel by being actuated;
A target braking force calculator for calculating the target braking force;
When a predetermined condition is satisfied, a switching control unit that performs switching, which is control for decreasing the electric braking force and increasing the friction braking force so as to realize the calculated target braking force;
A braking control device comprising: a friction braking control unit that activates the friction braking device before reducing the electric braking force. The braking control device according to claim 1, wherein
The brake control device, wherein the friction brake control unit operates the friction brake device before the predetermined condition is satisfied. The braking control device according to claim 2, wherein
The friction braking device is
A rotor that rotates with the wheels;
A pad that is arranged with a predetermined clearance with respect to the rotor and that generates the friction braking force by contacting the rotor;
The brake control device, wherein the friction brake control unit operates the friction brake device so as to reduce the clearance before the predetermined condition is satisfied. In the braking control device according to claim 3,
The friction control device, wherein the friction braking device generates the friction braking force below a predetermined value by the friction braking device before the predetermined condition is satisfied. In the braking control device according to claim 3,
The braking control device, wherein the friction braking control unit contacts the rotor and the pad before the predetermined condition is satisfied. The braking control device according to claim 2, wherein
Set a replacement end vehicle speed, which is a vehicle speed at which the replacement control unit ends the replacement,
An electric braking torque limit value setting unit configured to set the limit value so that the switching is completed at the replacement end vehicle speed when the electric braking torque, which is a torque corresponding to the electric braking force, is decreased along the limit value; ,
The predetermined condition is when the limit value falls below the electric braking torque corresponding to the target braking force. The braking control device according to claim 6, wherein
The friction braking control unit is configured such that a deviation between the electric braking torque corresponding to the target braking force and the limiting value is a predetermined deviation in a state where the limiting value is larger than the electric braking torque corresponding to the target braking force. When the following condition is satisfied, the operation of the friction braking device is started. The braking control device according to claim 2, wherein
The target braking force calculation unit calculates the target braking force according to the braking operation state of the driver,
The brake control device, wherein the friction brake control unit operates the friction brake device after the driver starts a braking operation and before the predetermined condition is satisfied. A target braking force calculation unit for calculating a target braking force based on a driver's braking operation state;
Calculating a regenerative braking force generated by a regenerative braking device provided in the vehicle so as to achieve the calculated target braking force;
A vehicle comprising: a switching friction braking control unit that performs switching control to reduce the regenerative braking force when a predetermined condition is satisfied and to increase the friction braking force generated by the friction braking device before the decrease of the regenerative braking force. Braking control device. A vehicle braking control method for calculating a target braking force based on a driver's braking operation state and operating a regenerative braking device and a friction braking device provided in the vehicle so as to realize the calculated target braking force. And
When the driver is performing a braking operation, the friction braking device is inactive, and the regenerative braking force is generated by the regenerative braking device, the regenerative braking force is decreased when a predetermined condition is satisfied, and the regenerative braking force is reduced. A braking control method for operating the friction braking device prior to power reduction.

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