Vehicle brake control device

Abstract

A vehicle brake control device comprises an application unit comprising a supply chamber and a servo chamber sealed by a sealing element, a pressure adjustment unit designed to adjust a front wheel pressure by supplying a first servo pressure to the servo chamber and outputting a front wheel supply pressure from the supply chamber to a front wheel cylinder, and a rear wheel pressure by outputting a second servo pressure to a rear wheel cylinder as a rear wheel supply pressure, front wheel and rear wheel supply pressure sensors, each designed to detect the front wheel and rear wheel supply pressures, and a control device designed to select either a dual-system pressure adjustment for individually adjusting the first and second servo pressures or a single-system pressure adjustment for adjusting the first and second servo pressures so that they are the same.The control device calculates front and rear wheel target pressures individually and ensures that the front and rear wheel supply pressures match the front and rear wheel target pressures in dual-system pressure adjustment, and equalizes the front and rear wheel target pressures and then adds a predetermined pressure to calculate a common target pressure and ensures that the rear wheel supply pressure matches the common target pressure in single-system pressure adjustment.

Description

Technical area

[0001] The present disclosure relates to a vehicle brake control device. Background technology

[0002] The applicant has developed a brake control device in which a dimension in a longitudinal direction is reduced and a brake fluid pressure of a front wheel system and a brake fluid pressure of a rear wheel system are individually controlled, as described in PTL1. In this device, a dual-system pressure adjustment in which the brake fluid pressures of the front and rear wheel systems are individually controlled can be switched to a single-system pressure adjustment in which the brake fluid pressures of the front and rear wheel systems are controlled to be the same. Smoothness is required for this switching. Citation listPatent literature

[0003] PTL1: JP 2019-137202 A Summary of the inventionTechnical problem

[0004] An object of the present invention is to provide a vehicle brake control device capable of smoothly performing switching from a two-system pressure adjustment to a one-system pressure adjustment. Solution to the problem

[0005] A vehicle brake control device (SC) according to the present invention adjusts fluid pressures (Pwf, Pwr) of front wheel and rear wheel cylinders (CWf, CWr) according to a required braking amount (Bs) and comprises "an application unit (AP) including a cylinder (CM) and a supply chamber (Rm) and a servo chamber (Ru) partitioned by a piston (NM) inserted into the cylinder (CM) and sealed by a sealing member (SL)";"a pressure adjusting unit (CA) configured to electronically adjust first and second servo pressures (P1, P2), adjust the fluid pressure (Pwf) of the front wheel cylinder (CWf) by supplying the first servo pressure (P1) to the servo chamber (Ru) and outputting a front wheel supply pressure (Pm) from the supply chamber (Rm) to the front wheel cylinder (CWf), and adjust the fluid pressure (Pwr) of the rear wheel cylinder (CWr) by outputting the second servo pressure (P2) to the rear wheel cylinder (CWr) as a rear wheel supply pressure (Pv)"; "front wheel and rear wheel supply pressure sensors (PM, PV), each configured to detect the front wheel and rear wheel supply pressures (Pm, Pv)";and "a control device (EA)" configured to select any one of a two-system pressure adjustment for individually adjusting the first and second servo pressures (P1, P2) and a one-system pressure adjustment for adjusting the first and second servo pressures (P1, P2) so that they are the same.;

[0006] In the vehicle brake control device (SC) according to the present invention, in response to selection of dual-system pressure adjustment, the control device (EA) individually calculates front and rear wheel target pressures (Ptf, Ptr) based on the required braking amount (Bs) and controls the pressure adjusting unit (CA) such that the front and rear wheel supply pressures (Pm, Pv) match the front and rear wheel target pressures (Ptf, Ptr). On the other hand, in response to selection of single-system pressure adjustment, the control device (EA) equalizes the front and rear wheel target pressures (Ptf, Ptr) and then adds a predetermined pressure (ps) to calculate a common target pressure (Px) and controls the pressure adjusting unit (CA) such that the rear wheel supply pressure (Pv) matches the common target pressure (Px). For example, the predetermined pressure (ps) is set to a value corresponding to a sliding resistance of the sealing element (SL).The control device (EA) switches the two-system pressure adjustment to the one-system pressure adjustment at a time when execution of an anti-lock brake control is started.

[0007] In the brake control device SC, the rear wheel supply pressure Pv is used for single-system pressure adjustment control, and the predetermined pressure ps is added to the common target pressure Px of the single-system pressure adjustment to compensate for frictional resistance of the seal member SL. According to the above configuration, switching from the dual-system pressure adjustment to the single-system pressure adjustment is performed smoothly. Short description of drawings Fig. 1 is a schematic diagram showing an overall configuration of a vehicle JV equipped with a brake control device SC according to the present invention. Fig. 2 is a schematic diagram showing a design example of an upper brake unit SA. Fig. 3 is a flowchart showing a processing example of brake adjustment control. Fig. 4 is a block diagram showing a drive control example of upstream side and downstream side pressure adjusting valves, UJ, UK in a two-system pressure adjustment. Fig. 5 is a block diagram showing a drive control example of the downstream side pressure adjusting valve UK in single-system pressure adjustment. Description of embodiments <Symbole von Bestandteilelementen oder dergleichen und Indices an dem Ende von Symbolen>

[0008] In the following description, constituent elements, calculation processing, signals, characteristics, and values ​​denoted by the same symbols, such as "CW," have the same function. Subscripts "f" and "r" added to the end of the symbols referring to respective wheels are detailed symbols indicating which system of the front and rear wheels these subscripts refer to. For example, wheel cylinders CW provided in the wheels are expressed as a "front wheel cylinder CWf" and a "rear wheel cylinder CWr." Furthermore, the subscripts "f" and "r" at the end of the symbols may be omitted. When the subscripts "f" and "r" are omitted, each symbol represents a generic term. For example, "CW" is a generic term for wheel cylinders provided in the front and rear wheels of a vehicle.

[0009] In a fluid passage from a master cylinder CM to the wheel cylinders CW, a side close to the master cylinder CM (a side remote from the wheel cylinders CW) is called an "upper portion," and a side close to the wheel cylinders CW (a side remote from the master cylinder CM) is called a "lower portion." In a circulation flow KN of a brake fluid BF, a side close to a discharge portion of a fluid pump QA (a side remote from a suction portion) is called an "upstream side," and a side close to the suction portion of the fluid pump QA (a side remote from the discharge portion) is called a "downstream side."

[0010] An upper fluid unit YA (also referred to as an "upper actuator") of an upper brake unit SA, a lower fluid unit YB (also referred to as a "lower actuator") of a lower brake unit SB, and the wheel cylinders CW are connected by the fluid passage (a connection passage HS). In addition, in the upper and lower actuators YA, YB, various components (UJ, UK, and the like) are connected by the fluid passage. Here, the "fluid passage" is a passage for moving the brake fluid BF and includes piping, a flow passage in an actuator, a hose, and the like. In the following description, the connection passage HS, a return passage HK, a reservoir passage HR, an input passage HN, a servo passage HV, and the like are fluid passages. <Fahrzeug JV, das mit der Bremssteuerungsvorrichtung SC ausgerüstet ist>

[0011] An overall configuration of a vehicle JV equipped with a brake control device SC according to the present invention will be described with reference to a schematic diagram of Fig. 1. The vehicle JV is a hybrid vehicle including an electric motor for driving, or an electric automatic vehicle. The vehicle JV includes a regeneration device KG. The regeneration device KG includes a generator GN and a control unit EG for the regeneration device (also referred to as a "regeneration control device"). The generator GN is also an electric motor for driving. During regenerative braking, the electric motor / generator GN acts as a power generator, and the generated power is stored in a storage battery BG by means of the regeneration control device EG. For example, the regeneration device KG is provided in front wheels WHf. In this configuration, a regenerative braking force Fg is generated in the front wheels WHf by the regeneration device KG.

[0012] Furthermore, the vehicle JV is provided with a driving assistance device DS in such a manner that control for automatically stopping the vehicle (referred to as "automatic braking control") is executed by the braking control device SC instead of a driver or by assisting the driver. The driving assistance device DS includes a distance sensor OB and a control unit ED (also referred to as a "driving assistance control device") for the driving assistance device. A distance Ob (a relative distance) between an object (another vehicle, a fixed object, a person, a bicycle, a stop line, a sign, a signal, or the like) present in front of the own vehicle JV and the own vehicle JV is detected by the distance sensor OB and is input to the driving assistance control device ED.In the driving assistance control device ED, a required deceleration Gs for automatically stopping the vehicle JV is calculated based on the relative distance Ob. The required deceleration Gs is a target vehicle deceleration value for executing the automatic braking control. The required deceleration Gs is output to a communication bus BS.

[0013] The vehicle JV includes front and rear wheel brake devices SXf, SXr (=SX). The brake device SX includes a brake caliper CP, a friction element MS (e.g., a brake pad), and a rotary element KT (e.g., a brake disc). The brake caliper CP is provided with the wheel cylinder CW. Due to a fluid pressure Pw (referred to as "wheel pressure") in the wheel cylinder CW, the friction element MS is pressed against the rotary element KT fixed to each wheel WH. Accordingly, a friction braking force Fm is generated in the wheel WH. The "friction braking force Fm" is a braking force generated by the wheel pressure Pw.

[0014] The vehicle JV includes a brake operating element BP, a steering operating element SH, and various sensors (BA and the like). The brake operating element BP (e.g., a brake pedal) is an element operated by a driver to decelerate the vehicle JV. The steering operating element SH (e.g., a steering wheel) is an element operated by the driver to steer the vehicle JV.

[0015] The vehicle JV includes various sensors, which are listed below. Detection signals (Ba and the like) from these sensors are input to one of the upper and lower control devices EA and EB. In the upper and lower control devices EA and EB, various controls are executed based on the sensor signals.

[0016] A brake operation amount sensor BA is provided that detects an operation amount Ba (a brake operation amount) of the brake operation member BP. For example, an operation displacement sensor SP that detects an operation displacement SP of the brake operation member BP is provided as the brake operation amount sensor BA. In addition, a simulator pressure sensor PZ that detects a fluid pressure Pz (referred to as a "simulator pressure") of a stroke simulator SS is employed. In the brake control device SC, the brake operation amount BA is a generic term for signals indicating a driver's braking intention, and the brake operation amount sensor BA is a generic term for sensors that detect the brake operation amount Ba. The brake operation amount Ba is input to the upper control device EA.

[0017] - A wheel speed sensor VW that detects a rotational speed Vw (a wheel speed) of the wheel WH is provided. The wheel speed Vw is input to the lower control device EB. In the lower control device EB, a vehicle body speed Vx is calculated based on the wheel speed Vw. In the lower control device EB, anti-lock brake control (an ABS control) to prevent the wheels WH from locking and traction control to prevent the drive wheel WH from spinning are executed based on the wheel speed Vw and the vehicle body speed Vx.

[0018] A steering operation amount sensor SK that detects an operation amount Sk (a steering operation amount, for example, a steering angle) of the steering operation member SH is provided. The vehicle JV (specifically, a vehicle body) is provided with a yaw rate sensor YR that detects a yaw rate Yr, a longitudinal acceleration sensor GX that detects a longitudinal acceleration Gx, and a lateral acceleration sensor GY that detects a lateral acceleration Gy. These sensor signals are input to the lower control device EB. In the lower control device EB, oversteer and understeer are prevented based on these signals (Sk, Yr, Gy, and the like), and electronic stability control (ESC) that stabilizes yaw behavior of the vehicle JV is executed.

[0019] The vehicle JV includes the brake control device SC. The brake control device SC adopts a front-to-rear mode (also known as "II mode") for the two braking systems. The actual wheel pressure Pw is adjusted by the brake control device SC.

[0020] The brake control device SC includes two brake units SA and SB. The upper brake unit SA includes the upper actuator YA (the upper fluid unit) and the upper control device EA (an upper control unit). The upper actuator YA is controlled by the upper control device EA. The lower brake unit SB is arranged between the upper brake unit SA and the wheel cylinder CW. The lower brake unit SB includes the lower actuator YB (the lower fluid unit) and the lower control device EB (a lower control unit). The lower actuator YB is controlled by the lower control device EB.

[0021] The upper brake unit SA (specifically, the upper control device EA), the lower brake unit SB (specifically, the lower control device EB), the regeneration device KG (specifically, the regeneration control device EG), and the driving assistance device DS (specifically, the driving assistance control device ED) are connected to the communication bus BS. The "communication bus BS" has a network structure in which a plurality of control devices (control units) are suspended on a communication line. Signal transmission is performed between a plurality of control devices (EA, EB, EG, ED, and the like) through the communication bus BS. That is, the plurality of control devices can transmit signals (detection values, calculation values, control flags, and the like) to the communication bus BS and receive the signals from the communication bus BS. <Obere Bremseinheit SA>

[0022] A design example of the upper brake unit SA of the brake control device SC is described with reference to a schematic diagram in Fig. 2. The upper brake unit SA generates front and rear wheel supply pressures Pm, Pv according to an operation of the brake operating member BP (a brake pedal). The front and rear wheel supply pressures Pm, Pv are finally supplied to the front and rear wheel cylinders CWf, CWr via the connecting passage HS (the fluid passage) and the lower brake unit SB. That is, the fluid pressures PWf, PWr (front and rear wheel pressures) of the front and rear wheel cylinders CWf, CWr are adjusted by the front and rear wheel supply pressures Pm, Pv. The upper brake unit SA includes the upper actuator YA and the upper control device EA. <<Oberer Aktuator YA> >

[0023] The upper actuator YA includes an application unit AP, a pressure adjustment unit CA and an input unit NR. [Application unit AP]

[0024] The front wheel supply pressure Pm is output by the application unit AP. The application unit AP comprises the single-piece master cylinder CM and a master piston NM.

[0025] The master piston NM is inserted into the master cylinder CM of a single-piece design. The interior of the master cylinder CM is divided into three fluid pressure chambers Rm, Ru, and Ro by the master piston NM. The master chamber Rm (also called a "feed chamber") is defined by a side bottom of the master cylinder CM and the master piston NM. Furthermore, the interior of the master cylinder CM is divided into the servo chamber Ru and the reaction force chamber Ro by a flange portion Tu of the master piston NM. That is, the master chamber Rm and the servo chamber Ru are arranged to face each other with the flange portion Tu in between. The fluid pressure chambers Rm, Ru, and Ro are sealed by seal elements SL. Therefore, when the master piston NM is moved, a frictional force is generated between each seal element SL and a surface (a sliding surface) on which the seal element SL slides.A pressure receiving surface rm of the master chamber Rm and a pressure receiving surface ru of the servo chamber Ru are made equal.

[0026] At the time of non-braking, the master piston NM is at a most retracted position (i.e., a position where a volume of the master chamber Rm becomes maximum). In this state, the master chamber Rm of the master cylinder CM communicates with a master reservoir RV. The brake fluid BF is stored in the master reservoir RV (an atmospheric pressure reservoir). When the brake operating member BP is operated, the master piston NM is moved in a forward direction Ha (a direction in which the volume of the master chamber Rm decreases). The communication between the master chamber Rm and the master reservoir RV is blocked by the movement. As the master piston NM continues to move in the forward direction Ha, the front wheel supply pressure Pm is increased from "0 (an atmospheric pressure)".Accordingly, the brake fluid BF, pressurized to the front-wheel supply pressure Pm from the master chamber Rm (supply chamber) of the master cylinder CM, is discharged (pumped). The front-wheel supply pressure Pm is a fluid pressure in the master chamber Rm, and thus the front-wheel supply pressure Pm is also referred to as a "master pressure." [Pressure adjustment unit CA]

[0027] The pressure adjusting unit CA supplies the rear-wheel supply pressure Pv to the rear-wheel cylinder CWr and supplies a downstream-side servo pressure Pk to the servo chamber Ru of the application unit AP. The pressure adjusting unit CA includes an electric motor MA, the fluid pump QA, and the upstream-side and downstream-side pressure adjusting valves UJ, UK.

[0028] The fluid pump QA is driven by the electric motor MA. In the fluid pump QA, the suction section and the discharge section are connected to each other via the return passage HK (the fluid passage). The suction section of the fluid pump QA is also connected to the master reservoir RV via the reservoir passage HR. A check valve is provided at the discharge section of the fluid pump QA.

[0029] The two pressure adjusting valves UJ, UK are provided in series in the return flow passage HK. Specifically, the return flow passage HK is provided with the normally open downstream pressure adjusting valve UK. The normally open upstream pressure adjusting valve UJ is provided between the downstream pressure adjusting valve UK and the discharge portion of the fluid pump QA. Therefore, in the circulation flow KN of the brake fluid BF, the upstream pressure adjusting valve UJ is arranged on the upstream side (the side close to the discharge portion of the fluid pump QA) with respect to the downstream pressure adjusting valve UK. The upstream and downstream pressure adjusting valves UJ, UK are linear solenoid valves in which a valve opening amount (lift amount) is continuously controlled based on an excitation state (e.g., supply flows Ij, Ik).The upstream side and downstream side pressure adjusting valves UJ, UK adjust a difference in fluid pressures (a differential pressure) between the upstream side and the downstream side, and thus the upstream side and downstream side pressure adjusting valves UJ, UK are also called “differential pressure valves”.

[0030] When the fluid pump QA is driven by the electric motor MA, the circulation flow KN (indicated by a broken line arrow) of the brake fluid BF, which includes the fluid pump QA and the upstream and downstream pressure adjusting valves UJ, UK, is generated in the return passage HK. The fluid pressure Pk (referred to as the "downstream side servo pressure") between the upstream side pressure adjusting valve UJ and the downstream side pressure adjusting valve UK is controlled by the downstream side pressure adjusting valve UK. A fluid pressure Pj (referred to as the "upstream side servo pressure") between the upstream side pressure adjusting valve UJ and the discharge portion of the fluid pump QA is controlled by the upstream side pressure adjusting valve UJ.

[0031] When the downstream pressure adjusting valve UK is fully open (at the time of non-energization, since the downstream pressure adjusting valve UK is of a normally closed type), the downstream servo pressure Pk is "0 (atmospheric pressure)." When an excitation amount (supply flow Ik) to the downstream pressure adjusting valve UK increases, the circulation flow KN (the flow of brake fluid BF circulating in the return passage HK) through the downstream pressure adjusting valve UK is throttled. In other words, the flow passage of the return passage HK is narrowed by the downstream pressure adjusting valve UK, and an orifice effect due to the downstream pressure adjusting valve UK is exerted.Accordingly, a differential pressure sPk (referred to as a "downstream side differential pressure") is generated between the downstream side fluid pressure (atmospheric pressure) and the upstream side fluid pressure Pk (referred to as the "downstream side servo pressure") with respect to the downstream side pressure adjusting valve UK. The downstream side differential pressure sPk is adjusted according to the excitation amount (the supply current Ik) to the downstream side pressure adjusting valve UK.

[0032] Similarly, when the upstream-side pressure adjusting valve UJ is in the fully open state (at the time of non-energization, since the upstream-side pressure adjusting valve UJ is of the normally closed type), the upstream-side servo pressure Pj coincides with the downstream-side servo pressure Pk. When the excitation amount (supply flow Ij) to the upstream-side pressure adjusting valve UJ increases, the circulation flow KN (the flow of brake fluid BF circulating in the return passage HK) through the upstream-side pressure adjusting valve UJ is throttled. In other words, the flow passage of the return passage HK is narrowed by the upstream-side pressure adjusting valve UJ, and the orifice effect due to the upstream-side pressure adjusting valve UJ is exerted.Accordingly, a differential pressure sPj (referred to as the "upstream side differential pressure") is generated between the downstream side fluid pressure Pk (the downstream side servo pressure) and the upstream side fluid pressure Pj (the upstream side servo pressure) with respect to the upstream side pressure adjusting valve UJ. The upstream side differential pressure sPj is adjusted according to the excitation amount (the supply current Ij) to the upstream side pressure adjusting valve UJ. With a magnitude relationship between the upstream side servo pressure Pj and the downstream side servo pressure Pk, the upstream side servo pressure Pj is normally equal to or higher than the downstream side servo pressure Pk (ie, "Pj ≥ Pk").Here, when the power is not supplied to the upstream side pressure adjusting valve UJ and the upstream side pressure adjusting valve UJ is in the fully open state, the upstream side servo pressure Pj and the downstream side servo pressure Pk are made equal (ie, "Pj = Pk").

[0033] The fluid pressure supplied from the upper brake unit SA to the lower brake unit SB is referred to as the "supply pressure." In the brake control device SC, a transmission passage of the supply pressure is different between a braking system related to the front wheels WHf and a braking system related to the rear wheels WHr. In the braking system related to the front wheels WHf, the return passage HK is connected to the servo chamber Ru via the servo passage HV (fluid passage) at a portion pk between the upstream-side pressure adjusting valve UJ and the downstream-side pressure adjusting valve UK. Therefore, the downstream-side servo pressure Pk is introduced (supplied) into the servo chamber Ru.When the downstream side servo pressure Pk increases, the master piston NM is pressed in the forward direction Ha, and the internal fluid pressure Pm (the front wheel supply pressure) of the master chamber Rm (supply chamber) increases. A front wheel connection passage HSf is connected to the master chamber Rm. The front wheel connection passage HSf is connected to the front wheel cylinders CWf via the lower brake unit SB (specifically, the lower actuator YB). Therefore, in the braking system related to the front wheels WHf, the brake control device SC supplies the downstream side servo pressure Pk to the front wheel cylinders CWf via the master cylinder CM as the front wheel supply pressure Pm. However, since "ru = rm" is satisfied, "Pk = Pm = Pwf" is satisfied. That is, the front wheel supply pressure Pm (ultimately, the front wheel pressure Pwf) is adjusted by the downstream side servo pressure Pk.

[0034] In the braking system related to the rear wheels WHr, the return passage HK is connected to the rear wheel cylinders CWr via a rear wheel communication passage HSr (the fluid passage) and the lower brake unit SB (specifically, the lower actuator YB) at a portion pj between the discharge portion of the fluid pump QA and the upstream side pressure adjusting valve UJ. Therefore, in the braking system related to the rear wheels WHr, the brake control device SC directly supplies the upstream side servo pressure Pj to the rear wheel cylinders CWr as the rear wheel supply pressure Pv (ie, Pj = Pv = Pwr). That is, the rear wheel supply pressure Pv (ultimately, the rear wheel pressure Pwr) is adjusted by the upstream side servo pressure Pj.

[0035] A rear-wheel feed pressure sensor PV (also referred to as a "servo pressure sensor") is provided in the rear-wheel connection passage HSr for detecting the rear-wheel feed pressure Pv (= Pj). The rear-wheel feed pressure sensor PV is connected to the upper control device EA. Therefore, a signal of the rear-wheel feed pressure Pv is directly input to the upper control device EA. [Input unit NR]

[0036] The brake actuator BP is actuated by the input unit NR to achieve regenerative coordination control, but a state where the wheel pressure Pw is not generated is established. Regenerative coordination control is designed to cause the friction braking force Fm (the braking force generated by the wheel pressure Pw) and the regenerative braking force Fg (the braking force generated by the generator GN) to cooperate, so that the kinetic energy of the vehicle JV can be efficiently recovered into electrical energy during braking. The input unit NR includes an input cylinder CN, an input piston NN, an introduction valve VA, a release valve VB, the stroke simulator SS, and the simulator pressure sensor PZ.

[0037] The input cylinder CN is fixed to the master cylinder CM. The input piston NN is inserted into the input cylinder CN. The input cylinder NN is mechanically connected to the brake operating element BP via a clevis (U-shaped link), so that it is interlocked with the brake operating element BP (brake pedal). An end surface of the input piston NN and an end surface of the master piston NM have a gap Ks (also called a "separation displacement"). By adjusting the gap Ks by the downstream servo pressure Pk, regenerative coordination control is achieved.

[0038] An input chamber Rn of the input unit NR is connected to the reaction force chamber Ro of the application unit AP via the input passage HN (the fluid passage). The normally closed introduction valve VA is provided in the input passage HN. The input passage HN is connected to the master reservoir RV via the reservoir passage HR between the introduction valve VA and the reaction force chamber Ro. The reservoir passage HR is provided with the normally closed release valve VB. The introduction valve VA and the release valve VB are on-off solenoid valves. The stroke simulator SS (also simply referred to as the "simulator") is connected to the input passage HN between the introduction valve VA and the reaction force chamber Ro.

[0039] When power is not supplied to the introduction valve VA and the release valve VB, the introduction valve VA is closed and the release valve VB is opened. The input chamber Rn is sealed by the closure of the introduction valve VA, and the fluid is confined. Accordingly, the master piston NM is displaced integrally with the brake operating member BP. The simulator SS is connected to the master reservoir RV by opening the release valve VB. When power is supplied to the introduction valve VA and the release valve VB, the introduction valve VA is opened and the release valve VB is closed. Accordingly, the master piston NM can be displaced separately from the brake operating member BP. In this case, since the input chamber Rn is connected to the stroke simulator SS, an operating force Fp of the brake operating member BP is generated by the simulator SS.The simulator pressure sensor PZ is provided in the input passage HN between the introduction valve VA and the reaction force chamber Ro, for detecting the fluid pressure Pz (the simulator pressure) in the simulator SS. Note that since the simulator pressure Pz is also an internal pressure of the input chamber Rn, the simulator pressure Pz is also a state quantity representing the operating force Fp of the brake operating member BP.

[0040] A state in which the master piston NM and the brake operating member BP are displaced separately from each other (at the time of energization of the solenoid valves VA and VB) is referred to as a "first mode (or a by-wire mode)". In the first mode, the brake control device SC functions as a brake-by-wire type device (i.e., a device capable of generating the friction braking force Fm independently of a driver's braking operation). Therefore, in the first mode, the wheel pressure Pw is generated independently of the operation of the brake operating member BP. In contrast, a state in which the master piston NM and the brake operating member BP are displaced integrally (at the time of de-energization of the solenoid valves VA and VB) is referred to as a "second mode (or a manual mode)". In the second mode, the wheel pressure Pw is linked to the driver's braking operation.At the input unit NR, an operation mode of the first mode (the by-wire mode) and the second mode (the manual mode) is selected based on the presence or absence of the power supply to the introduction valve VA and the release valve VB. << Upper control device EA >>

[0041] The upper actuator YA is controlled by the upper control device EA. The upper control device EA includes a microprocessor MP and a drive circuit DR. The upper control device EA is connected to the communication bus BS so that signals (detection values, calculation values, control flags, and the like) can be shared with the various control devices (EB, EG, ED, and the like).

[0042] The brake operation amount Ba and the rear wheel supply pressure Pv are input to the upper control device EA. The brake operation amount Ba is a generic expression for a state quantity representing the operation amount of the brake operation element BP. The detection signal Sp (the operation displacement) of the operation displacement sensor SP and the detection signal Pz (the simulator stroke) of the simulator pressure sensor PZ are directly input to the upper control device EA as the brake operation amount Ba. The detection signal Pv (the rear wheel supply pressure) of the rear wheel supply pressure sensor Pv is directly input to the upper control device EA.

[0043] The front wheel supply pressure Pm, a regenerative limit braking force Fx, the required deceleration Gs, and the like are input to the upper control device EA via the communication bus BS. The front wheel supply pressure Pm is detected by a supply pressure sensor PM provided in the lower actuator YB and transmitted from the lower control device EB. The "regenerative limit braking force Fx" is a maximum value (limit value) of the regenerative braking force Fg that can be generated by the regenerative device KG. The regenerative limit braking force Fx is calculated by the regeneration control device EG and transmitted from the regeneration control device EG. The required deceleration Gs is a target value of vehicle deceleration in the automatic braking control. The required deceleration Gs is calculated by the driving assistance control device ED and transmitted from the driving assistance control device ED.

[0044] A pressure adjustment control algorithm is programmed in the upper control device EA (specifically, the microprocessor MP). "Pressure adjustment control" is a control for adjusting the front and rear wheel supply pressures Pm, Pv (finally, the front and rear wheel pressures Pwf, Pwr) and includes regenerative coordination control. The pressure adjustment control is executed based on the brake application amount Ba (the application displacement Sp, the simulator pressure Pz), the required deceleration Gs, the front and rear wheel supply pressures Pm, Pv, and the regenerative limit braking force Fx. Here, the brake application amount Ba and the required deceleration Gs are generically referred to as a "required braking amount Bs." That is, the required braking amount Bs is an input for commanding the wheel pressure Pw (resulting in the friction braking force Fm) to be generated by the brake control device SC.

[0045] Based on the pressure adjustment control algorithm, the electric motor MA and the various solenoid valves (UJ, UK, and the like) constituting the upper actuator YA are driven by the drive circuit DR. In the drive circuit DR, an H-bridge circuit is implemented by a switching element (e.g., a MOS-FET) for driving the electric motor MA. The drive circuit DR includes a switching element for driving the various solenoid valves (UJ, UK, and the like). In addition, the drive circuit DR includes a motor current sensor (not shown) that detects a supply current Im (an actual value) to the electric motor MA, and upstream and downstream current sensors (not shown) that detect the supply currents Ij, Ik (which are actual values ​​and are referred to as "upstream and downstream currents") to the upstream and downstream pressure adjustment valves UJ, UK.The electric motor MA is equipped with a rotation angle sensor (not shown) that detects a rotation angle Ka (an actual value) of a rotating component of the electric motor MA. Then, a motor rotation speed Na is calculated based on the motor rotation angle Ka.

[0046] In the upper control device EA, upstream and downstream target currents Itj, Itk, which are target values ​​corresponding to the upstream and downstream currents Ij, Ik, are calculated based on the required braking amount Bs. Then, the upstream and downstream currents Ij, Ik (the actual values) are controlled so that they are close to and consistent with the upstream and downstream target currents Itj, Itk (the target values). In the upper control device EA, a target rotation speed Nta (a target value) corresponding to the actual rotation speed Na is calculated based on the required braking amount Bs. The motor supply current Im is controlled so that the actual rotation speed Na is close to and consistent with the target rotation speed Nta.Based on these control algorithms, a drive signal Ma for controlling the electric motor MA and drive signals Uj, Uk, Va, Vb for controlling the various solenoid valves UJ, UK, VA, VB are calculated. Then, according to the drive signals (Ma and the like), switching components of the drive circuit DR are driven, and the electric motor MA and the solenoid valves UJ, UK, VA, VB are controlled. <Untere Bremseinheit SB>

[0047] The lower brake unit SB is a universal unit (device) for executing anti-lock brake control, traction control, electronic stability control, and the like. In anti-lock brake control, traction control, electronic stability control, and the like, the wheel pressure Pw of each wheel cylinder CW is adjusted independently, and therefore, these controls are also generically referred to as "each-wheel independent control." In the lower brake unit SB, the wheel pressure Pw can be individually adjusted for each wheel cylinder CW to execute each-wheel independent control.

[0048] The lower brake unit SB is provided between the upper brake unit SA and the wheel cylinders CW. The front and rear wheel supply pressures Pm and Pv are supplied from the upper brake unit SA to the lower brake unit SB. Then, in the lower brake unit SB, the front and rear wheel supply pressures Pm and Pv are adjusted (increased or decreased) and output as the fluid pressures Pwf and Pwr (the front and rear wheel pressures) of the front and rear wheel cylinders CWf and CWr. When the lower brake unit SB is not operating (at the time of non-execution of each-wheel independent control), the front and rear wheel pressures Pwf and Pwr are equal to the front and rear wheel supply pressures Pm and Pv.

[0049] The front-wheel supply pressure sensor PM is provided for detecting the actual fluid pressure Pm (the front-wheel supply pressure) supplied from the upper actuator YA (specifically, the master chamber Rm). The front-wheel supply pressure sensor Pm is also referred to as a "master pressure sensor" and is installed in the lower actuator YB. A signal of the front-wheel supply pressure Pm is directly input to the lower control device EB and output to the communication bus BS. <Verarbeiten der Druckanpassungsteuerung>

[0050] A processing example of the pressure adjustment control will be explained with reference to a flowchart of Fig. 3. Pressure adjustment control is a control of the front and rear wheel supply pressures Pm, Pv (in effect, the front and rear wheel pressures Pwf, Pwr) based on the required braking amount Bs (Ba, Gs, etc.). In pressure adjustment control, dual-system pressure adjustment is implemented by the upper brake unit SA. "Dual-system pressure adjustment" is a pressure adjustment control in which the front and rear wheel pressures Pwf, Pwr are adjusted independently and individually. In contrast to dual-system pressure adjustment, a pressure adjustment control in which the front and rear wheel pressures Pwf, Pwr are adjusted so that they are equal is called "single-system pressure adjustment." In regenerative coordination control, dual-system pressure adjustment improves regeneration efficiency and makes the braking force distribution between the front and rear wheels more appropriate than single-system pressure adjustment.The pressure adjustment control algorithm is programmed in the microprocessor MP of the upper control device EA.

[0051] When describing the processing example, the following is assumed. - The regeneration device KG is only provided for the front wheel WHf. Therefore, the regenerative braking force Fg acts on the front wheel WHf, but not on the rear wheel WHr. - In the upper actuator YA, the pressure receiving area rm (also called a "master area") of the master chamber rm and the pressure receiving area ru (also called a "servo area") of the servo chamber Ru are set to be equal. Therefore, "rm = ru" is satisfied, and in a static state, "Pk = Pm" is satisfied (here, the friction or the like of the sealing element SL is ignored). - The front wheel feed pressure sensor PM is installed in the lower brake unit SB, and the front wheel feed pressure Pm is input to the upper brake unit SA via the communication bus BS. In contrast, the rear wheel feed pressure sensor PV is installed in the upper brake unit SA, and the rear wheel feed pressure Pv is input directly to the upper brake unit SA.

[0052] Different braking forces are as follows. - A "total vehicle body braking force Fu" is the actual braking force acting on the entire vehicle. A target value corresponding to the total vehicle body braking force Fu is a "target vehicle body braking force Fv." - The "friction braking force Fm" is a braking force actually generated according to the wheel pressure Pw. A target value corresponding to the friction braking force Fm is a "target friction braking force Fn." - The "regenerative braking force Fg" is a braking force actually generated by the regeneration device KG. A target value corresponding to the regenerative braking force Fg is a "target regenerative braking force Fh." The target regenerative braking force Fh is calculated by the upper braking unit SA (specifically, the upper control device EA) or the lower braking unit SB (specifically, the lower control device EB) and transmitted to the regeneration device KG (specifically, the regeneration control device EG) via the communication bus BS. In the regeneration device KG, the generator GN is controlled by the regeneration control device EG so that the actual regenerative braking force Fg is close to and consistent with the target regenerative braking force Fh. - The "regenerative limit braking force Fx" is the regenerative braking force Fg that can be generated by the regeneration device KG. In other words, the regenerative limit braking force Fx is the maximum value (limit value) of the regenerative braking force Fg that can be generated by the regeneration device KG. Therefore, in the regeneration device KG, the regenerative braking force Fg is generated within a range (limit) of the regenerative limit braking force Fx. The regenerative limit braking force Fx is calculated by the regeneration device KG (specifically, the regeneration control device EG) and transmitted to the upper brake unit SA (specifically, the upper control device EA) via the communication bus BS.

[0053] At step S110, power is supplied to the supply valve VA and the release valve VB. Accordingly, the normally closed supply valve VA is opened, the normally closed release valve VB is closed, and the first mode, in which the master piston NM and the brake operating member BP can be displaced separately, is selected. In the first mode, the front and rear wheel supply pressures Pm, Pv (i.e., the front and rear wheel pressures Pwf, Pwr) are adjusted independently of the operation of the brake operating member BP. In this case, the operating force Fp of the brake operating member BP is generated by the stroke simulator SS.

[0054] At step S120, various signals (Ba and the like) are read out. The brake operation amount Ba (Sp, Pz and the like) is detected by the brake operation amount sensor BA (SP, PZ and the like) and input to the upper control device EA. The rear wheel supply pressure Pv is detected by the rear wheel supply pressure sensor PV and input to the upper control device EA. The required deceleration Gs is obtained from the drive assistance control device ED via the communication bus BS. The front wheel supply pressure Pm is obtained from the lower control device EB via the communication bus BS. The regenerative limit braking force Fx is obtained from the regeneration control device EG via the communication bus BS.

[0055] At step S130, the required braking amount Bs is calculated based on the braking operation amount Ba and the required deceleration Gs. For example, the braking operation amount Ba and the required deceleration Gs are compared in the dimension of vehicle deceleration, and the larger one is determined as the required braking amount Bs. The required braking amount Bs is an instruction value for the supply pressures Pm, Pv (=Pw) ​​required for the brake control device SC. Furthermore, at step S130, the target vehicle body braking force Fv (the target value of the braking force acting on the entire vehicle) is calculated based on the required braking amount Bs and a calculation map Zfv. The target vehicle body braking force Fv is calculated so that it increases as the required braking amount Bs increases, in accordance with the calculation map Zfv.That is, the target vehicle body braking force Fv is determined so that it increases as the required braking amount Bs increases.

[0056] At step S140, it is determined whether "single-system pressure adjustment" is to be executed. This determination is referred to as a "switching determination." In the pressure adjustment control, the dual-system pressure adjustment is selected as the initial control. For example, in the lower brake unit SB, based on the start of execution of the anti-lock brake control (control for preventing wheel WH from locking based on the wheel speed Vw and the vehicle body speed Vx), the switching determination is affirmative, and the pressure adjustment control is switched from the dual-system pressure adjustment to the single-system pressure adjustment. Here, the presence or absence of execution of the anti-lock brake control (the ABS control) is transmitted from the lower control device EB through a control flag FA (also referred to as an "execution flag").For the execution flag FA, "0" indicates that "ABS control is not executed," and "1" indicates that "ABS control is executed." Therefore, the switching determination is affirmative at a time point (a corresponding calculation cycle) when the execution flag FA switches from "0 (non-execution)" to "1 (execution)."

[0057] The switching determination may be determined based on the operation state of the regeneration device KG. Specifically, when the regenerative braking force Fg generated by the regeneration device KG is not generated, the switching determination is affirmative. An example includes a case where the storage battery BG is fully charged and the regeneration device KG is no longer able to generate the regenerative braking force Fg, or a case where some kind of failure occurs in the regeneration device KG. Operation information of the regeneration device KG is transmitted to the upper control device EA when the limit regenerative braking force Fx (i.e., the generateable regenerative braking force) is "0."

[0058] If the switching determination at step S140 is negative, processing proceeds to step S150, and dual-system pressure adjustment (processing at steps S150 to S170) is executed. Conversely, if the switching determination is positive, processing proceeds to step S180, and single-system pressure adjustment (processing at steps S180 to S210) is executed. <<Verarbeitung der Zweisystemdruckanpassung> >

[0059] At step S150, required front and rear wheel braking forces Fqf, Fqr (= Fq) are calculated based on the target vehicle body braking force Fv. Specifically, the required front and rear wheel braking forces Fqf, Fqr are calculated such that the following two conditions are met. The "required front wheel braking force Fqf" is a target value of the total braking force acting on the front wheel WHf. Therefore, the required front wheel braking force Fqf agrees with a sum of the target regenerative braking force Fh and a target front wheel friction braking force Fnf (ie, "Fqf = Fh + Fnf"). The "required rear wheel braking force Fqr" is a target value of the total braking force acting on the rear wheel WHr. Therefore, the required rear wheel braking force Fqr agrees with a target rear wheel friction braking force Fnr (ie, "Fqr = Fnf").

[0060] Condition 1: The sum of the required front wheel braking force Fqf and the required rear wheel braking force Fqr is consistent with the target vehicle body braking force Fv (ie, Fv = Fqf + Fqr).

[0061] Condition 2: A ratio of the required rear wheel braking force Fqr to the required front wheel braking force Fqf agrees with a predetermined value hb (ie, "Fqr / Fqf = hb"). Here, the predetermined value hb is a ratio of a rear wheel friction braking force Fmr to a front wheel friction braking force Fmf when the regenerative braking force Fg is "0." Therefore, the predetermined value hb is a constant set in advance based on specifications of the braking device SX.

[0062] The required front and rear wheel braking forces Fqf, Fqr are determined by the following expression (1) so that they satisfy conditions 1 and 2. Fqf=Fv / (1+hb) and Fqr=Fv⋅hb / (1+hb)

[0063] Furthermore, at step S150, the target regenerative braking force Fh and the front and rear target friction braking forces Fnf, Fnr are calculated based on the required front and rear braking forces Fqf, Fqr and the limit regenerative braking force Fx. Specifically, the target regenerative braking force Fh is determined to be equal to or less than the limit regenerative braking force Fx. For example, when the required front wheel braking force Fqf is equal to or less than the limit regenerative braking force Fx, the target regenerative braking force Fh is made equal to the required front wheel braking force Fqf, the target front wheel friction braking force Fnf is set to "0", and the rear wheel friction braking force Fnr is made equal to the required rear wheel braking force Fqr (ie, when "Fqf ≤ Fx", then "Fh = Fqf, Fnf = 0, Fnr = Fqr").On the other hand, when the required front wheel braking force Fqf is greater than the regenerative limit braking force Fx, the target regenerative braking force Fh is made equal to the regenerative limit braking force Fx, the target front wheel friction braking force Fnf is set to a “value obtained by subtracting the regenerative limit braking force Fx (=Fh) from the required front wheel braking force Fqf”, and the rear wheel friction braking force Fnr is made equal to the required rear wheel braking force Fqr (ie, when “Fqf > Fx”, then “Fh = Fx, Fnf = Fqf - Fx = Fqf - Fh, Fnr = Fqr”).

[0064] At step S160, front and rear wheel target pressures Ptf, Ptr are calculated based on the front and rear wheel target frictional braking forces Fnf, Fnr (= Fn). The front and rear wheel target pressures Ptf, Ptr are determined by converting the target frictional braking force Fn into dimensions of the front and rear wheel applied pressures Pm, Pv (i.e., the front and rear wheel pressures Pwf, Pwr) based on the specifications of the braking device SX and the like (the pressure receiving area of ​​the wheel cylinder CW, an effective braking radius of the rotary member KT, a friction coefficient of the friction member MS, an effective radius of the wheel (tire), and the like). That is, the front wheel and rear wheel target pressures Ptf, Ptr are calculated based on the braking amount Bs and the regenerative limit braking force Fx (the regenerative braking force that can be generated by the regeneration device KG).The front wheel supply pressure Pm is the same as the front wheel pressure Pwf and the rear wheel supply pressure Pv is the same as the rear wheel pressure Pwr and thus the front wheel and rear wheel target pressures Ptf, Ptr are also target values ​​for the front wheel and rear wheel pressures Pwf, Pwr.

[0065] At step S170, the front and rear wheel pressures Pwf, Pwr (the actual values) are adjusted based on the front and rear wheel target pressures Ptf, Ptr (the target values). The upper control device EA performs control to drive the electric motor MA and the upstream and downstream pressure adjusting valves UJ, UK, and cause the front and rear wheel pressures Pwf, Pwr to be close to and consistent with the front and rear wheel target pressures Ptf, Ptr. Specifically, at step S170, the electric motor MA is driven, and the circulation flow KN including the fluid pump QA and the upstream and downstream pressure adjusting valves UJ, UK is generated.Then, the downstream side pressure adjusting valve UK is subjected to fluid pressure control based on the front wheel target pressure Ptf and the front wheel supply pressure Pm so that the front wheel supply pressure Pm (= Pwf) coincides with the front wheel target pressure Ptf. That is, the inflow flow Ik (which is an actual value and is also referred to as the "downstream side flow") to the downstream side pressure adjusting valve UK is adjusted so that a deviation hPf (referred to as a "front wheel deviation") between the front wheel supply pressure Pm and the front wheel target pressure Ptf becomes "0." The upstream side pressure adjusting valve UJ is subjected to fluid pressure control based on the rear wheel target pressure Ptr and the rear wheel supply pressure Pv so that the rear wheel supply pressure Pv (= Pwr) coincides with the rear wheel target pressure Ptr.That is, the supply flow Ij (which is an actual value and is also referred to as the “upstream side flow”) to the upstream side pressure adjusting valve UJ is adjusted such that a deviation hPr (referred to as a “rear wheel deviation”) between the rear wheel supply pressure Pv and the rear wheel target pressure Ptr becomes “0”. <<Verarbeitung der Einsystemdruckanpassung> >

[0066] If the switching determination at step S140 is affirmative, at step S180, the power supply to the upstream-side pressure adjusting valve UJ is stopped, and the upstream-side pressure adjusting valve UJ is opened. Since the upstream-side pressure adjusting valve UJ is a normally closed solenoid valve, the upstream-side pressure adjusting valve UJ is brought into a fully open state when the power supply is stopped. Accordingly, switching from the dual-system pressure adjustment to the single-system pressure adjustment is performed. The switching from the dual-system pressure adjustment to the single-system pressure adjustment is referred to as "pressure adjustment switching."

[0067] At step S190, a sum Fnt (also referred to as a "target sum") of the target regenerative braking force Fh and the target friction braking force Fn is calculated based on the target vehicle body braking force Fv and the regenerative limit braking force Fx. Here, the "target sum Fnt" is a sum of the front wheel target friction braking force Fnf and the rear wheel target friction braking force Fnr (ie, "Fnt = Fnf + Fnr"). At step S190, as in the processing of step S150, the target regenerative braking force Fh is determined as a value equal to or less than the regenerative limit braking force Fx. For example, when the target vehicle body braking force Fv is equal to or smaller than the regenerative limit braking force Fx, the regenerative target braking force Fh is made equal to the target vehicle body braking force Fv, and the sum Fnt of the target friction braking forces Fn is set to “0” (i.e., if “Fv ≤ Fx” then “Fh = Fv, Fnt = 0”).When the target vehicle body braking force Fv is greater than the regenerative limit braking force Fx, the regenerative target braking force Fh is made equal to the regenerative limit braking force Fx, and the target sum Fnt is set to a value obtained by subtracting the regenerative target braking force Fh (= Fx) from the target vehicle body braking force Fv (ie, if "Fv > Fx", then "Fh = Fx, Fnt = Fv - Fh = Fv - Fx"). The regenerative target braking force Fh is transmitted to the communication bus BS.

[0068] At step S200, a common target pressure Px is calculated based on the target sum Fnt. Specifically, the common target pressure Px is determined by further adding a predetermined pressure ps after two conditions including the target sum Fnt and "Ptf = Ptr" are satisfied. Here, the predetermined pressure ps is a value corresponding to the sliding resistance of the seal member SL and is a preset predetermined value (constant). Note that even with the common target pressure Px, fluid pressure conversion of the target sum Fnt is performed based on the specifications of the braking device SX and the like (the pressure receiving area of ​​the wheel cylinder CW, the effective braking radius of the rotary member KT, the friction coefficient of the friction member MS, the effective radius of the wheel (tire), and the like).

[0069] The "common target pressure Px" is a common target value unified in the braking system related to the front and rear wheels, which corresponds to the front and rear wheel supply pressures Pm, Pv. When "Fv ≤ Fx", the common target pressure Px (= Ptf = Ptr) is determined to be "0". When "Fv > Fx", the common target pressure Px is calculated under the relationship "Ptf = Ptr", so that the sum Fnt (the target sum) of the target friction braking forces Fn corresponding to the common target pressures Px is made equal to the value "Fv - Fh", and is determined by further adding the predetermined pressure ps.

[0070] At step S200, when the single-system pressure adjustment is performed, the actual regenerative braking force Fg can be set to "0." This is achieved by setting the regenerative braking force Fx (the limit regenerative braking force) that can be generated by the regenerative device KG or the target regenerative braking force Fh to "0." When the switching determination at the upper brake unit SA is affirmative, the regenerative coordination control is terminated, and the actuation of the regenerative device KG can be stopped. When "Fg = 0 (Fx = 0 or Fh = 0)", as in the above, the common target pressure Px is determined by adding the predetermined pressure ps after "Ptf = Ptr, Fnf + Fnr = Fv" is satisfied, based on the specifications of the brake device SX and the like.

[0071] At step S210, the upper actuator YA is driven based on the common target pressure Px and the rear-wheel supply pressure Pv. At the pressure adjusting unit CA, the upstream-side servo pressure Pj and the downstream-side servo pressure Pk are equalized while the upstream-side pressure adjusting valve UJ is in the fully open state. That is, since a condition of "Pk = Pm = Pwf = Pj = Pv = Pwr" is satisfied, the downstream-side pressure adjusting valve UK is subjected to fluid pressure control so that the rear-wheel supply pressure Pv is close to and consistent with the common target pressure Px. Specifically, the supply flow Ik (the downstream-side flow) to the downstream-side pressure adjusting valve UK is adjusted so that a deviation hPx (referred to as a "common deviation") between the rear-wheel supply pressure Pv and the common target pressure Px becomes "0."

[0072] The brake control device SC is a brake-by-wire device capable of independently controlling the operation of the brake operating element BP (the brake pedal) and the fluid pressure (the wheel pressure Pw) of the wheel cylinder CW. The upper brake unit SA is provided with the master chamber Rm (the supply chamber) and the servo chamber Ru. The master chamber Rm and the servo chamber Ru are sealed by the sealing element SL and then partitioned by the master cylinder CM and the master piston NM. In the upper brake unit SA (specifically, the pressure adjusting unit CA), the upstream and downstream servo pressures Pj and Pk are electrically and individually adjusted by the two linear solenoid valves UJ and UK (the upstream and downstream pressure adjusting valves).

[0073] In dual-system pressure adjustment, the front wheel pressure Pwf is adjusted by the downstream side servo pressure Pk based on the required braking amount Bs and the front wheel supply pressure Pm. The downstream side servo pressure Pk is supplied to the servo chamber Ru, so that the front wheel supply pressure Pm is output from the master chamber Rm, and finally the front wheel pressure Pwf is adjusted. That is, the downstream side servo pressure Pk is transmitted as the front wheel supply pressure Pm (ultimately the front wheel pressure Pwf) via the master cylinder CM and the master piston NM. On the other hand, the rear wheel pressure Pwr is adjusted by the upstream side servo pressure Pj based on the required braking amount Bs and the rear wheel supply pressure Pv.The upstream-side servo pressure Pj is supplied as the rear-wheel supply pressure Pv (ultimately the rear-wheel pressure Pwr) directly from the pressure adjusting unit CA to the rear-wheel cylinder CWr without passing through the master cylinder CM and the master piston NM. The upstream-side and downstream-side pressure adjusting valves UJ, UK are subjected to feedback control so that the front-wheel and rear-wheel supply pressures Pm, Pv are close to and consistent with the front-wheel and rear-wheel target pressures Ptf, Ptr, which are calculated based on the required braking amount Bs.

[0074] When the dual-system pressure adjustment is switched to the single-system pressure adjustment (i.e., when the pressure adjustment switching is performed), the power supply to the upstream-side pressure adjustment valve UJ is stopped, and a state is established where the upstream-side servo pressure Pj and the downstream-side servo pressure Pk are equalized. That is, the individual adjustment of the front-wheel supply pressure Pm and the rear-wheel supply pressure Pv is eliminated. In the single-system pressure adjustment, the target values ​​corresponding to the front-wheel and rear-wheel supply pressures Pm, Pv are determined as the same target value Px (common target pressures) in the front and rear wheel systems. Here, the predetermined pressure ps is added to the common target pressure Px, taking into account an influence of the sliding resistance of the seal member SL.Based on the common target pressure Px and the rear wheel supply pressure Pv, the front and rear wheel pressures Pwf and Pwr are adjusted by the downstream side servo pressure Pk. The downstream side pressure adjustment valve UK is subjected to feedback control so that the rear wheel supply pressure Pv is close to and consistent with the common target pressure Px.

[0075] A supply pressure signal related to the single-system pressure adjustment can be selected from the front-wheel supply pressure Pm or the rear-wheel supply pressure Pv. The sliding resistance of the seal member SL can act as a disturbance, and the front-wheel supply pressure Pm includes the sliding resistance, whereas the rear-wheel supply pressure Pv does not include the sliding resistance. The front-wheel supply pressure Pm is acquired through the communication bus BS, and thus a communication delay is included, but the rear-wheel supply pressure Pv is directly input to the upper control device EA and is therefore not affected by the communication delay. When the communication bus BS is abnormal, the front-wheel supply pressure Pm cannot be acquired, but the rear-wheel supply pressure Pv can. Therefore, in the brake control device SC, the rear-wheel supply pressure Pv is used for the single-system pressure adjustment.

[0076] When the rear-wheel supply pressure Pv is assumed when the dual-system pressure adjustment is switched to the single-system pressure adjustment (i.e., at the time of pressure adjustment switching), the control of the front-wheel pressure Pwf transitions from that including the sliding resistance (i.e., control by the front-wheel supply pressure Pm) to that not including the sliding resistance (i.e., control by the rear-wheel supply pressure Pv). Therefore, a discontinuity (resulting in a change in the fluid pressure) of the front-wheel pressure Pwf is generated at the time of pressure adjustment switching. Specifically, the rear-wheel supply pressure Pv does not include the frictional resistance of the seal member SL, and thus, at the time of pressure adjustment switching, the front-wheel pressure Pwf is reduced by an amount of the frictional resistance.

[0077] In the brake control device SC, the predetermined pressure ps is added to the common target pressure Px to compensate for a fluid pressure component due to the friction of the seal member SL. Accordingly, a change in the wheel pressure Pw (particularly, a decrease in the front wheel pressure Pwf due to sliding friction resistance) is prevented when switching from the dual-system pressure adjustment to the single-system pressure adjustment, and smooth pressure adjustment switching is achieved. The rear wheel pressure Pwr is increased by an amount of the predetermined pressure ps at the time of pressure adjustment switching, but since an influence of the front wheel braking force is dominant in the braking force of the entire vehicle, an influence of a change in the rear wheel braking force on the vehicle deceleration is slight.

[0078] Switching from the dual-system pressure adjustment to the single-system pressure adjustment is performed when the anti-lock brake control is executed at the lower brake unit SB. Alternatively, this switching is performed when the regeneration device KG cannot generate the regenerative braking force Fg. For example, this is a case where the storage battery BG of the regeneration device KG is fully charged. Since the charge state of the storage battery BG is normally monitored, when the storage battery BG is almost fully charged, switching from the dual-system pressure adjustment to the single-system pressure adjustment can be completed before the start of the brake application (ie, at the time of non-braking in the state of "Bs = 0"). Accordingly, since a change in the wheel pressure Pw does not occur during the brake application, the driver is less likely to feel discomfort.On the other hand, the anti-lock brake control is executed during brake application, and thus the driver may easily feel discomfort. Therefore, the resistance compensation of the sealing element SL based on the addition of the predetermined pressure ps is particularly effective at the time of executing the anti-lock brake control, which is started during braking. <Antriebssteuerung der Zweisystemdruckanpassung>

[0079] A detailed description of a drive control example of the two-system pressure adjustment (particularly the processing of step S170) will be given with reference to a block diagram of Fig. 4. The control processing is performed by the upper control device EA. During dual-system pressure adjustment, the electric motor MA is driven, and the circulation flow KN of the brake fluid BF, which includes the upstream and downstream pressure adjustment valves UJ, UK, and the fluid pump QA, is generated. <<Antriebssteuerung des Stromabwärtsseitendruckanpassungsventils UK> >

[0080] The drive control of the downstream pressure adjustment valve UK is described. The drive processing according to the downstream pressure adjustment valve UK includes a downstream command current calculation block ISK, a downstream deviation calculation block HPK, a downstream compensation current calculation block IHK, and a downstream current control block IFK.

[0081] In the downstream-side command current calculation block ISK, a downstream-side command current Isk is calculated based on the front-wheel target pressure Ptf and a preset calculation map Zsk. The "downstream-side command current Isk" is a target value related to the feed current Ik (the downstream-side current) of the downstream-side pressure adjusting valve UK, which is necessary to achieve the front-wheel target pressure Ptf. In accordance with the calculation map Zsk, the downstream-side command current Isk is determined to increase in accordance with an increase in the front-wheel target pressure Ptf. The downstream-side command current calculation block ISK corresponds to feedforward control based on the front-wheel target pressure Ptf.

[0082] In the downstream side deviation calculation block HPK, the deviation hPf (the front wheel deviation) between the front wheel target pressure Ptf and the front wheel supply pressure Pm (ie, the wheel pressure Pwf) is calculated. Specifically, the front wheel supply pressure Pm is subtracted from the front wheel target pressure Ptf to calculate the front wheel deviation hPf (ie, "hPf = Ptf - Pm").

[0083] In the downstream side compensation current calculation block IHK, a downstream side compensation current Ihk is calculated based on the front wheel deviation hPf and a preset calculation map Zhk. The downstream side command current Isk is calculated corresponding to the front wheel target pressure Ptf, and an error between the front wheel target pressure Ptf and the front wheel supply pressure Pm may occur. The "downstream side compensation current Ihk" is to compensate (reduce) the error and cause the front wheel supply pressure Pm to match the front wheel target pressure Ptf. The downstream side compensation current Ihk is determined to increase according to an increase in the front wheel deviation hPf in accordance with the calculation map Zhk.Specifically, when the front wheel target pressure Ptf is greater than the front wheel supply pressure Pm and the front wheel deviation hPf has a positive sign, the downstream side compensation current Ihk is determined with the positive sign so that the downstream side command current Isk is increased. Conversely, when the front wheel target pressure Ptf is less than the front wheel supply pressure Pm and the front wheel deviation hPf has a negative sign, the downstream side compensation current Ihk is determined with the negative sign so that the downstream side command current Isk is decreased. Here, a dead zone is provided in the calculation map Zhk. The downstream side compensation current calculation block IHK corresponds to the control (feedback control) based on the front wheel supply pressure Pm.

[0084] The downstream side compensation current Ihk is added to the downstream side command current Isk to calculate the downstream side target current Itk (ie, "Itk = Isk + Ihk"). The "downstream side target current Itk" is a final target value of the current supplied to the downstream side pressure adjustment valve UK. Therefore, the drive control of the downstream side pressure adjustment valve UK is implemented through feedforward control and closed-loop control.

[0085] In the downstream-side current control block IFK, the downstream-side drive signal Uk is calculated based on the downstream-side target current Itk (the target value) and the downstream-side current Ik (the actual value) so that the downstream-side current Ik is close to and consistent with the downstream-side target current Itk. Here, the downstream-side current Ik is detected by a downstream-side current sensor IK provided in the drive circuit DR. In the downstream-side current control block IFK, when "Itk>Ik," the drive signal Uk is determined to increase the downstream-side current Ik. Conversely, when "Itk<Ik," the drive signal Uk is determined to decrease the downstream-side current Ik. That is, in the downstream-side current control block IFK, the control related to the current is performed.Therefore, in the drive control of the downstream side pressure adjusting valve UK, in addition to the control related to the fluid pressure, the control related to the current is provided, and the downstream side servo pressure Pk (= Pm = Pwf) is controlled to coincide with the front wheel target pressure Ptf. <<Antriebssteuerung des Stromaufwärtsseitendruckanpassungsventils UJ> >

[0086] The drive control of the upstream-side pressure adjusting valve UJ is described. The downstream-side pressure adjusting valve UK is controlled based on the front-wheel target pressure Ptf, but the upstream-side pressure adjusting valve UJ is controlled based on a difference sPt between the front-wheel target pressure Ptf and the rear-wheel target pressure Ptr. In addition, the upstream-side pressure adjusting valve UJ is controlled based on feedback control related to the rear-wheel supply pressure Pv. Since other configurations are the same as those of the downstream-side pressure adjusting valve UK, a common section is briefly described.The drive processing related to the upstream side pressure adjustment valve UJ includes a target differential pressure calculation block SPT, an upstream side instruction current calculation block ISJ, an upstream side deviation calculation block HPJ, an upstream side compensation current calculation block IHJ, and an upstream side current control block IFJ.

[0087] In the target differential pressure calculation block SPT, the target differential pressure sPt is calculated based on the front and rear wheel target pressures Ptf, Ptr. The "target differential pressure sPt" is a target value of the differential pressure (a difference between the upstream fluid pressure and the downstream fluid pressure with respect to the upstream pressure adjusting valve UJ) to be generated by the upstream pressure adjusting valve UJ. Specifically, the target differential pressure sPt is determined by subtracting the front wheel target pressure Ptf from the rear wheel target pressure Ptr (ie, "sPt = Ptr - Ptf (≥ 0)"). The upstream pressure adjusting valve UJ increases the downstream servo pressure Pk (= Pm) by an amount corresponding to the target differential pressure sPt to generate the upstream servo pressure Pj (= Pv).

[0088] In the upstream-side command current calculation block ISJ, an upstream-side command current is calculated based on the target differential pressure sPt and a preset calculation map Zsj. The "upstream-side command current Isj" is a target value that refers to the feed current Ij (the upstream-side current) of the upstream-side pressure adjusting valve UJ required to achieve the target differential pressure sPt. According to the calculation map Zsj, the upstream-side command current Isj is determined to increase in accordance with an increase in the target differential pressure sPt. The upstream-side command current calculation block ISJ corresponds to feedforward control based on the target differential pressure sPt.

[0089] In the upstream side deviation calculation block HPJ, the deviation hPr (the rear wheel deviation) between the rear wheel target pressure Ptr and the rear wheel supply pressure Pv (ie, the rear wheel pressure Pwr) is calculated. Specifically, the rear wheel supply pressure Pv is subtracted from the rear wheel target pressure Ptr to calculate the rear wheel deviation hPr (ie, "hPr = Ptr - Pv").

[0090] In the upstream-side compensation current calculation block IHJ, an upstream-side compensation current Ihj is calculated based on the rear-wheel deviation hPr and a preset calculation map Zhj. The "upstream-side compensation current Ihj" is for compensating (reducing) the error between the rear-wheel target pressure Ptr and the rear-wheel supply pressure Pv and causing the rear-wheel supply pressure Pv to coincide with the rear-wheel target pressure Ptr. The upstream-side compensation current Ihj is determined to increase according to an increase in the rear-wheel deviation hPr in accordance with the calculation map Zhj. The upstream-side compensation current calculation block IHJ corresponds to the feedback control based on the rear-wheel supply pressure Pv.

[0091] The upstream side compensation current Ihj is added to the upstream side command current Isj to calculate the upstream side target current Itj (ie, "Itj = Isj + Ihj"). The "upstream side target current Itj" is a final target value of the current supplied to the upstream side pressure adjustment valve UJ. Therefore, the drive control of the upstream side pressure adjustment valve UJ is implemented through feedforward control and closed-loop control.

[0092] In the upstream-side current control block IFJ, the upstream-side drive signal Uj is calculated based on the upstream-side target current Itj (the target value) and the upstream-side current Ij (the actual value) so that the upstream-side current Ij is close to and consistent with the upstream-side target current Itj. Here, the upstream-side current Ij is detected by an upstream-side current sensor IJ provided in the drive circuit DR. In the upstream-side current control block IFJ, feedback control related to current is performed. Therefore, in the drive control of the upstream-side pressure adjusting valve UJ, in addition to feedback control related to fluid pressure, feedback control related to current is provided, and the upstream-side servo pressure Pj (=Pv =Pwr) is controlled to match the rear wheel target pressure Ptr. <Antriebssteuerung der Einsystemdruckanpassung>

[0093] A detailed description of a drive control example of the single-system pressure adjustment (particularly the processing of step S210) will be given with reference to a block diagram of Fig. 5. The control processing is also performed by the upper control device EA in the same manner as the dual-system pressure adjustment. In the single-system pressure adjustment, the electric motor MA is driven, and the circulation flow KN of the brake fluid BF, which includes the upstream and downstream pressure adjustment valves UJ, UK, and the fluid pump QA, is generated. Here, the upstream pressure adjustment valve UJ is in a non-energized state and is in a fully open state. Since the processing (ISK, IHK, IFK) denoted by the same symbols as those of the dual-system pressure adjustment is the same as the processing described above, the detailed description thereof will be omitted.

[0094] In a common target pressure calculation block PX, the common target pressure Px is calculated based on the required braking amount Bs. The required braking amount Bs is a generic expression for the braking amount Ba and the required deceleration Gs, and is a required value for the wheel pressure Pw. The common target pressure Px is calculated by equalizing the front and rear wheel target pressures Ptf, Ptr and then adding the predetermined pressure ps. That is, the common target pressure Px is a unified target value for the front and rear wheel supply pressures Pm, Pv.

[0095] In a common deviation calculation block HPX, the common deviation hPx is calculated based on the common target pressure Px and the rear wheel supply pressure Pv. Specifically, the rear wheel supply pressure Pv is subtracted from the common target pressure Px to determine the common deviation hPx (ie, "hPx = Px - Pv").

[0096] In the downstream-side command current calculation block ISK, the downstream-side command current Isk is calculated based on the common target pressure Px and the calculation map Zsk. In the downstream-side compensation current calculation block IHK, the downstream compensation current Ihk is calculated based on the common deviation hPx and the calculation map Zhk. As in the dual-system pressure adjustment, in the single-system pressure adjustment, the downstream compensation current Ihk is also added to the downstream-side command current Isk to determine the downstream target current Itk. Then, in the downstream-side flow control block IFK, the drive signal Uk of the downstream pressure adjustment valve UK is determined based on the downstream target current Itk.

[0097] In single-system pressure adjustment, the functions of the blocks (i.e., SPT, ISJ, HPJ, IHJ, and IFJ) related to the upstream side pressure adjustment valve UJ are stopped, and the energization of the upstream side pressure adjustment valve UJ is stopped (i.e., "Ij = 0"). For the blocks (specifically, ISK and HPK) related to the downstream side pressure adjustment valve UK, the common target pressure Px is applied instead of the front wheel target pressure Ptf, and the rear wheel supply pressure Pv is applied instead of the front wheel supply pressure Pm. <Anwendung auf das Fahrzeug JV, das die Regenerationsvorrichtung KG in dem Hinterrad WHr umfasst>

[0098] In the above-described embodiment, a vehicle (referred to as a "front wheel regeneration vehicle") in which the regeneration device KG is provided on the front wheel WHf but not on the rear wheels WHr is assumed. Alternatively, the brake control device SC may be applied to a vehicle (referred to as a "rear wheel regeneration vehicle") in which the regeneration device KG is provided on the rear wheel WHr but not on the front wheel WHf. A difference will be described below. The symbols in [] in the block diagram of Fig. 4 correspond to the brake control device SC for the rear wheel regeneration vehicle.

[0099] In the brake control device SC applied to the rear wheel regeneration vehicle, in the schematic diagram of Fig. 2, the servo passage HV is connected to the return passage HK at the section pj, and the rear wheel connection passage HSr is connected to the return passage HK at the section pk. That is, the upstream side servo pressure Pj is supplied to the servo chamber Ru, and the downstream side servo pressure Pk is supplied to the rear wheel cylinder CWr (ie, "Pj = Pm = Pwf, Pk = Pv = Pwr"). When processing the pressure adjustment control (especially the dual-system pressure adjustment) in Fig. 4 and Fig. 5 When calculating the front and rear target friction braking forces Fnf, Fnr, when "Fqr ≤ Fx", "Fh = Fqr, Fnf = Fqf, Fnr = 0" is determined. Conversely, when "Fqf > Fx", "Fh = Fx, Fnf = Fqf, Fnr = Fqr - Fx = Fqr - Fh" is determined. Then, the front and rear target friction braking forces Fnf, Fnr are converted into the front and rear target pressures Ptf, Ptr (here, "Ptf ≥ Ptr").

[0100] In addition, the block diagram of Fig. 4, the rear wheel target pressure Ptr is input to the downstream-side command current calculation block ISK and the downstream-side deviation calculation block HPK instead of the front wheel target pressure Ptf. That is, the downstream-side command current Isk is determined based on the rear wheel target pressure Ptr and the calculation map Zsk, and at the downstream-side deviation calculation block HPK, the rear wheel deviation hPr is calculated as "hPr = Ptr - Pv." Then, at the downstream-side compensation current calculation block IHK, the downstream compensation current Ihk is calculated based on the rear wheel deviation hPr. In the target deviation calculation block sPt, the target differential pressure sPt is calculated as "sPt = Ptf - Ptr (≥ 0)." The upstream-side deviation calculation block HPJ receives the front wheel target pressure Ptf instead of the rear wheel target pressure Ptr.Therefore, in the upstream side deviation calculation block HPJ, the front wheel deviation hPf is calculated as "hPf = Ptf - Pm." Then, in the upstream side compensation current calculation block IHJ, the upstream side compensation current Ihj is calculated based on the front wheel deviation hPf. Note that the single-system pressure adjustment processing is the same for front-wheel and rear-wheel regeneration vehicles.

[0101] In a vehicle in which the regeneration device KG (= KGf, KGr) is provided at both the front and rear wheels WHf and WHr, either of the two configurations described above is adopted depending on a magnitude of a regeneration amount. Specifically, the brake control device SC of the front-wheel regeneration vehicle is applied to a vehicle in which a regeneration amount of the front-wheel regeneration device KGf is greater than a regeneration amount of the rear-wheel regeneration device KGr. Conversely, the brake control device SC of the rear-wheel regeneration vehicle is applied to a vehicle in which the regeneration amount of the front-wheel regeneration device KGf is smaller than the regeneration amount of the rear-wheel regeneration device KGr.

[0102] The pressure adjusting unit CA of the brake control device SC applied to front-wheel and rear-wheel regeneration vehicles is summarized. In the pressure adjusting unit CA, the upstream and downstream pressure adjusting valves UJ, UK of a normally closed type are arranged in series in the circulation flow KN of the brake fluid BF, which includes the fluid pump QA. A pressure of the brake fluid BF discharged from the fluid pump QA is adjusted to the upstream and downstream servo pressures Pj, Pk by the upstream and downstream pressure adjusting valves UJ, UK. In the dual-system pressure adjustment, one of the upstream and downstream servo pressures Pj, Pk (referred to as a "first servo pressure P1") is supplied to the servo chamber Ru, so that the front-wheel supply pressure Pm is output from the supply chamber Rm to the front-wheel cylinder CWf.That is, the front wheel supply pressure Pm is adjusted by the first servo pressure P1, and the front wheel pressure Pwf is adjusted by the front wheel supply pressure Pm (the fluid pressure transmission is in the order of "P1 -> Pm -> Pwf"). The other of the upstream and downstream servo pressures Pj, Pk (referred to as a "second servo pressure P2") is output to the rear wheel cylinder CWr as the rear wheel supply pressure Pv. That is, the rear wheel supply pressure Pv is adjusted by the second servo pressure P2, and the rear wheel pressure Pwr is adjusted by the rear wheel supply pressure Pv (the fluid pressure transmission is in the order of "P2 -> Pv -> Pwr").

[0103] In dual-system pressure adjustment, the first and second servo pressures P1 and P2 are adjusted individually, but in single-system pressure adjustment, the first and second servo pressures P1 and P2 are adjusted to be the same. That is, the front and rear wheel supply pressures Pm and Pv are adjusted to be equal to each other by making the first servo pressure P1 and the second servo pressure P2 equal. The front and rear wheel pressures Pwf and Pwr are adjusted to be equal to each other according to the front and rear wheel supply pressures Pm and Pv. The fluid pressure transmission is in the order of "(P1 = P2) -> (Pm = Pv) -> (Pwf = Pwr)". However, the front wheel supply pressure Pm includes frictional resistance, and the rear wheel supply pressure Pv does not include frictional resistance, so there is a difference between them. It should be noted that the pressure adjustment state of the pressure adjustment unit CA is either the two-system pressure adjustment or the single-system pressure adjustment. <Andere Ausführungsformen>

[0104] Other embodiments will be described below. Even in other embodiments, the same effect as described above (smooth pressure adjustment switching from dual-system pressure adjustment to single-system pressure adjustment, etc.) is achieved.

[0105] In the above-described embodiment, in the brake control device SC, the front wheel supply pressure sensor PM is installed in the lower brake unit SB (specifically, the lower actuator YB). The front wheel supply pressure sensor PM may be installed in the upper brake unit SA (specifically, the upper actuator YA). However, the front wheel supply pressure sensor PM is required for each-wheel independent control, such as anti-lock brake control, and thus, it is advantageous to install the front wheel supply pressure sensor PM in the lower brake unit SB in view of simplifying the entire device. In addition, if the front wheel supply pressure sensor PM is installed in the upper brake unit SA, the each-wheel independent control cannot be executed at the time of a communication failure. Also in this respect, it is advantageous to install the front wheel supply pressure sensor PM in the lower brake unit SB.

[0106] In the above-described embodiment, the target values ​​(Fv, Fx, Fh, Fn, and the like) of various braking forces are calculated in a dimension of a longitudinal force acting on the vehicle JV. Alternatively, the calculation may be performed using the dimension of the deceleration of the vehicle JV or the dimension of the torque of the wheel WH. This is based on a fact that state quantities from the longitudinal force to the deceleration of the vehicle (referred to as "force-related state quantities") are equivalent. Therefore, the target pressures Ptf, Ptr, Px are calculated based on the force-related state quantities from the longitudinal force acting on the vehicle JV to the deceleration of the vehicle JV.

[0107] In the above-described embodiment, examples of the pressure adjusting unit CA include one (a so-called backflow type configuration) that adjusts the front and rear wheel supply pressures Pm, Pv by throttling the circulation flow KN of the brake fluid BF discharged from the fluid pump QA through the upstream and downstream pressure adjusting valves UJ, UK. Alternatively, in the pressure adjusting unit CA, the front and rear wheel supply pressures Pm, Pv may be adjusted based on the pressure stored in the accumulator (a so-called accumulator type configuration). A volume in the cylinder can be increased or decreased by the piston directly driven by the electric motor, and the front and rear wheel supply pressures Pm, Pv can be adjusted (a so-called electric cylinder type configuration).

[0108] In the above-described embodiment, the pressure receiving area rm (the master area) of the master chamber Rm and the pressure receiving area ru (the servo area) of the servo chamber Ru are set equal to each other at the application unit AP. The master area rm and the servo area ru do not need to be equal. In a configuration where the master area rm and the servo area ru are different, a conversion calculation between the front wheel supply pressure Pm and the downstream side servo pressure Pk (or the upstream side servo pressure Pj) can be performed based on the ratio of the servo area ru to the master area rm (that is, the conversion based on "Pm rm = Pk ru (or Pj ru)").

[0109] In the brake control device SC, in the transmission passage of the front-wheel and rear-wheel supply pressures Pm, Pv, the fluid passage (which is a movement passage of the brake fluid BF and is referred to as the "connection passage") connects a portion where the front-wheel supply pressure Pm acts and a portion where the rear-wheel supply pressure Pv acts. A normally open solenoid valve (referred to as a "connection valve") is provided in the connection passage. In the case of dual-system pressure adjustment, the connection valve is closed and the connection passage is blocked. Accordingly, the front-wheel and rear-wheel supply pressures Pm, Pv are individually adjusted. In contrast, in the case of single-system pressure adjustment, the connection valve is opened and the portions related to the front-wheel and rear-wheel supply pressures Pm, Pv are connected.Accordingly, the front and rear wheel supply pressures Pm, Pv are adjusted with the same fluid pressure. Here, the portions (referred to as "acting portions") where the front and rear wheel supply pressures Pm, Pv act correspond to portions such as generation sources of the front and rear wheel supply pressures Pm, Pv and the transmission passage (the fluid passage, the fluid pressure chamber). The acting portions include not only the portions where the front and rear wheel supply pressures Pm, Pv act directly, but also portions where the forces generated by the front and rear wheel supply pressures Pm, Pv act via the element (e.g., the master piston NM). For example, in the embodiment shown in FIG. Fig.In the configuration shown in Figure 2, the sections pj, pk are the effective sections, and the upstream side pressure adjustment valve UJ corresponds to the connecting valve. Here, the rear wheel supply pressure Pv acts directly on the section pj, but the front wheel supply pressure Pm acts indirectly on the section pk via the master piston NM. <Zusammenfassung von Ausführungsformen>

[0110] The following summarizes the embodiments of the brake control device SC. The brake control device SC is a brake-by-wire device capable of independently adjusting the fluid pressures Pwf, Pwr (front and rear wheel pressures) of the front and rear wheel cylinders CWf, CWr according to the required braking amount Bs.

[0111] The brake control device SC includes the application unit AP, the pressure adjustment unit CA, the control device EA, the front wheel supply pressure sensor PM, and the rear wheel supply pressure sensor Pv. The application unit AP includes the cylinder CM and the supply chamber Rm (master chamber) and the servo chamber Ru, which are divided by the piston NM inserted into the cylinder CM. Here, the supply chamber Rm and the servo chamber Ru are sealed by the sealing element SL.

[0112] The first and second servo pressures P1, P2 are electrically adjusted by the pressure adjusting unit CA. For example, the first and second servo pressures P1, P2 are generated using the electric motor as a power source. The first servo pressure P1 is supplied to the servo chamber Ru. Accordingly, the front-wheel supply pressure Pm is output from the supply chamber Rm to the front-wheel cylinder CWf. That is, the front-wheel supply pressure Pm is adjusted by the first servo pressure P1, and the front-wheel pressure Pwf is adjusted by the front-wheel supply pressure Pm. Therefore, the front-wheel pressure Pwf is adjusted by the first servo pressure P1.

[0113] The second servo pressure P2 is directly output to the rear wheel cylinder CWr as the rear wheel supply pressure Pv. That is, the rear wheel supply pressure Pv is adjusted by the second servo pressure P2, and the rear wheel pressure Pwr is adjusted by the rear wheel supply pressure Pv. Therefore, the rear wheel pressure Pwr is adjusted by the second servo pressure P2. In the control device EA, any one of the two-system pressure adjustment for individually adjusting the first and second servo pressures P1, P2 and the single-system pressure adjustment for adjusting the first and second servo pressures P1, P2 so that they are the same is selected. The front and rear wheel supply pressures Pm, Pv are detected by the front and rear wheel supply pressure sensors PM, PV.

[0114] In the control device EA, when dual-system pressure adjustment is selected, the front and rear wheel target pressures Ptf and Ptr are individually calculated based on the required braking amount Bs. The pressure adjustment unit CA is controlled so that the front and rear wheel supply pressures Pm and Pv match the front and rear wheel target pressures Ptf and Ptr. Specifically, the first and second servo pressures P1 and P2 are controlled so that the front and rear wheel supply pressures Pm and Pv match the front and rear wheel target pressures Ptf and Ptr. In dual-system pressure adjustment, the front wheel target pressure Ptf and the rear wheel target pressure Ptr are different from each other, and thus the first servo pressure P1 and the second servo pressure P2 are adjusted to be different from each other. As a result, the front wheel supply pressure Pm and the rear wheel supply pressure Pv are different from each other, and the front wheel pressure Pwf and the rear wheel pressure Pwr are different from each other.

[0115] On the other hand, when single-system pressure adjustment is selected, the common target pressure Px is calculated. The common target pressure Px is determined by equalizing the front and rear wheel target pressures Ptf, Ptr and further adding the predetermined pressure ps. The pressure adjustment unit CA is controlled so that the rear wheel supply pressure Pv agrees with the common target pressure Px. Specifically, the first and second servo pressures P1, P2 are controlled so that the rear wheel supply pressure Pv agrees with the common target pressure Px. Note that the predetermined pressure ps is a predetermined value (constant) corresponding to the sliding resistance of the seal member SL and is set in advance. In single-system pressure adjustment, the front wheel target pressure Ptf and the rear wheel target pressure Ptr are equal, and the first servo pressure P1 and the second servo pressure P2 are adjusted to be equal.As a result, the front wheel supply pressure Pm and the rear wheel supply pressure Pv become equal, and the front wheel pressure Pwf and the rear wheel pressure Pwr become equal. However, there is a difference in the frictional resistance of the sealing element SL.

[0116] The first servo pressure P1 is transmitted to the front-wheel cylinder CWf as the front-wheel supply pressure Pm via the cylinder CM and the piston NM. On the other hand, the second servo pressure P2 is directly transmitted to the rear-wheel cylinder CWr as the rear-wheel supply pressure Pv without passing through the cylinder CM and the piston NM. The cylinder CM and the piston NM are sealed by the seal element SL, and the front-wheel supply pressure Pm is affected by the sliding resistance of the seal element SL, but the rear-wheel supply pressure Pv is not affected.

[0117] In the brake control device SC, a signal of the rear-wheel supply pressure Pv is used for the single-system pressure adjustment. In this configuration, when the dual-system pressure adjustment is switched to the single-system pressure adjustment (at the time of pressure adjustment switching), a change (specifically, a decrease) in the front-wheel pressure Pwf occurs. This is because the control on the front-wheel pressure Pwf changes from one controlled by the front-wheel supply pressure Pm, which includes the sliding resistance of the seal member SL, to one controlled by the rear-wheel supply pressure Pv, which does not include the sliding resistance. In the brake control device SC, the influence of the sliding resistance is reduced by adding the predetermined pressure ps to the target pressure Px (the common target pressure) of the single-system pressure adjustment. Accordingly, the change in the front-wheel pressure Pwf that occurs at the time of pressure adjustment switching is prevented.

[0118] At the time of pressure adjustment switching, the change in the front wheel pressure Pwf is inhibited, but a change occurs in the rear wheel pressure Pwr. However, in the braking force of the entire vehicle (as a result of the deceleration of the vehicle JV), the influence of the front wheel braking force is much greater than the influence of the rear wheel braking force. Therefore, a change in the rear wheel braking force due to a change in the rear wheel pressure Pwr has a slight influence on the entire vehicle. Therefore, in the entire vehicle, switching from the dual-system pressure adjustment to the single-system pressure adjustment is smoothly performed using the common target pressure Px to which the predetermined pressure ps (for example, a value corresponding to the sliding resistance of the seal member SL) is added.

[0119] Pressure adjustment switching based on the common target pressure Px is particularly effective when anti-lock brake control is started and the dual-system pressure adjustment is switched to single-system pressure adjustment. This is because anti-lock brake control is started during a series of brake applications, allowing the driver to easily detect changes in wheel pressure Pw. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2019

[0003] JP 137202 A

[0003]

Claims

[1] A vehicle brake control device (SC) that adjusts fluid pressures (Pwf, Pwr) of front wheel and rear wheel cylinders (CWf, CWr) according to a required braking amount (Bs), the vehicle brake control device (SC) comprising: an application unit (AP) comprising a cylinder (CM) and a feed chamber (Rm) and a servo chamber (Ru) divided by a piston (NM) inserted into the cylinder (CM) and sealed by a sealing element (SL); a pressure adjusting unit (CA) configured to electrically adjust first and second servo pressures (P1, P2), adjust the fluid pressure (Pwf) of the front wheel cylinder (CWf) by supplying the first servo pressure (P1) to the servo chamber (Ru) and outputting a front wheel supply pressure (Pm) from the supply chamber (Rm) to the front wheel cylinder (CWf), and adjust the fluid pressure (Pwr) of the rear wheel cylinder (CWr) by outputting the second servo pressure (P2) to the rear wheel cylinder (CWr) as a rear wheel supply pressure (Pv); Front wheel and rear wheel feed pressure sensors (PM, PV), each designed to detect the front wheel and rear wheel feed pressures (Pm, Pv); and a control device (EA) configured to select any one of a two-system pressure adjustment for individually adjusting the first and second servo pressures (P1, P2) and a one-system pressure adjustment for adjusting the first and second servo pressures (P1, P2) so that they are the same, wherein the control device (EA) is designed to in response to a selection of the dual-system pressure adjustment, to individually calculate front wheel and rear wheel target pressures (Ptf, Ptr) based on the required braking amount (Bs) and to control the pressure adjustment unit (CA) such that the front wheel and rear wheel supply pressures (Pm, Pv) match the front wheel and rear wheel target pressures (Ptf, Ptr), and in response to a selection of the single-system pressure adjustment, to make the front wheel and rear wheel target pressures (Ptf, Ptr) equal and then add a predetermined pressure (ps) to calculate a common target pressure (Px) and to control the pressure adjusting unit (CA) such that the rear wheel supply pressure (Pv) agrees with the common target pressure (Px). [2] A vehicle brake control device according to claim 1, wherein the predetermined pressure (ps) is set to a value corresponding to a sliding resistance of the sealing member (SL). [3] A vehicle brake control device according to claim 1 or 2, wherein the control device (EA) switches the two-system pressure adjustment to the one-system pressure adjustment at a time when execution of an anti-lock brake control is started.

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