Braking control device for vehicle

Abstract

This braking control device includes: a main housing HGc in which first and second cylinders CM, CC are formed; a first piston NM which is inserted into the first cylinder CM and moves in conjunction with a braking operation member BP, whereby a supply pressure Pm can be generated in the first cylinder CM; an electric motor MT which generates first rotation power Tm; a reduction gear GS which decelerates the first rotation power Tm and outputs second rotation power Tn; a conversion mechanism GH which converts the second rotation power Tn into linear power Fn; a second piston NC which is inserted into the second cylinder CC and moves by the linear power Fn, whereby a servo pressure Pc is generated in the second cylinder CC; and a sub-housing HGs which holds the electric motor MT, the reduction gear GS, the conversion mechanism GH, and the second piston NC and is assembled to the main housing HGc.

Description

Vehicle braking control device

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

[0002] Patent Document 1 describes that in order to reduce the size of the brake fluid pressure supply unit, "the brake fluid pressure supply unit 10 is equipped with a linear motion conversion mechanism 14 that converts the rotational motion of the rotating shaft 112 of the electric motor 11 into linear motion of a ball screw 141 as a linear motion part and moves the piston 122 using the ball screw 141, and a power transmission part 15 that includes a drive gear 151 that rotates together with the rotating shaft 112 and transmits the rotational motion of the rotating shaft 112 to the linear motion conversion mechanism 14, the rotating shaft 112 extending from the main body 111 of the electric motor 11 toward the housing 13, and the drive gear 151 being arranged between the main body 111 of the electric motor 11 and the housing 13."

[0003] Incidentally, the upstream unit U1 (also referred to as the "brake control device") in Patent Document 1 is configured as a single unit. This configuration is called an "integrated type." In an integrated brake control device, a plurality of cylinder holes are formed in the housing, such as the master cylinder 17, the cylinder 121 for the electric cylinder device 12, and the cylinder for the simulator SS. A piston is assembled into each of these cylinder holes via a sealing member. Furthermore, components such as an electromagnetic valve are assembled to complete the integrated brake control device. A large number of components are assembled into an integrated brake control device, and it is preferable that these components be inspected efficiently.

[0004] Japanese Patent Application Laid-Open No. 2022-056252

[0005] In view of the above problems, an object of the present invention is to provide an integrated brake control device that can be efficiently inspected.

[0006] A brake control device (SA) for a vehicle according to the present invention includes a main housing (HGc) in which first and second cylinders (CM, CC) are formed, a first piston (NM) inserted into the first cylinder (CM) and moving in conjunction with a brake operating member (BP) to generate a supply pressure (Pm) in the first cylinder (CM), an electric motor (MT) that generates a first rotational power (Tm), and a reducer (GS) that reduces the speed of the first rotational power (Tm) and outputs a second rotational power (Tn). The main housing (HGc) includes a conversion mechanism (GH) that converts the second rotational power (Tn) into linear power (Fn), a second piston (NC) that is inserted into the second cylinder (CC) and moves using the linear power (Fn) to generate servo pressure (Pc) in the second cylinder (CC), and a sub-housing (HGs) that holds the electric motor (MT), the reducer (GS), the conversion mechanism (GH), and the second piston (NC) and is assembled to the main housing (HGc).

[0007] In the vehicle brake control device (SA) according to the present invention, the sub-housing (HGs) includes a gear housing (HGg) that fixes a bearing (BC) that supports the conversion mechanism (GH). When projected parallel to a direction (Hk) perpendicular to the rotation axis (Jk) of the bearing (BC), the projection of the bearing (BC) overlaps the projection of the gear housing (HGg), but the projection of the second piston (NC) does not overlap the projection of the gear housing (HGg). The sub-housing (HGs) also includes a motor housing (HGm) that supports the electric motor (MT), and the motor housing (HGm) and the gear housing (HGg) are fastened together to the main housing (HGc). This configuration facilitates individual inspection of the sub-assembly SY. As a result, inspection efficiency of the brake control device SA can be improved.

[0008] It is a schematic diagram for explaining an embodiment of the brake control device SA. It is a partial cross-sectional view for explaining the configuration of the hydraulic pressure generating unit PS. It is a schematic diagram for explaining the assembly of the subassembly SY. It is a schematic diagram for explaining a first unit inspection example of the subassembly SY. It is a schematic diagram for explaining a second unit inspection example of the subassembly SY.

[0009] <Symbols of components, etc., and subscripts at the end of symbols> In the following description, components, arithmetic processes, signals, characteristics, and values ​​with the same symbol, such as "CW," have the same function. The subscripts "f" and "r" at the end of the symbol for each wheel are generic symbols that indicate whether the symbol relates to the front or rear wheel system. For example, a wheel cylinder CW provided on each wheel is written as "front wheel cylinder CWf, rear wheel cylinder CWr." Furthermore, the subscripts "f" and "r" at the end of the symbol can 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 on the front and rear wheels of a vehicle. Furthermore, the generic term "CW" can also be written as "CW (= CWf, CWr)."

[0010] The actuator YA of the brake control device SA, the actuator YB of the modulator device SB, and the wheel cylinder CW are connected by a fluid path (communication path HS). Furthermore, the actuators YA and YB are connected to various components (PS, etc.) by fluid paths. Here, the "fluid path" refers to a path for moving the brake fluid BF (working fluid), and includes a flow path within the actuator (e.g., a flow path within the main housing HGc), piping, hoses, etc. In the following explanation, the communication path HS, reservoir path HR, input path HN, servo path HU, supply path HH, etc. are fluid paths.

[0011] <Brake control device SA of vehicle> An embodiment of the brake control device SA will be described with reference to the schematic diagram of Fig. 1. For example, the brake control device SA is applied to a hybrid vehicle equipped with an electric motor for driving, or an electric vehicle.

[0012] The vehicle is equipped with a regenerative device KG. The regenerative device KG is composed of a generator GN for energy regeneration (also referred to as an "electric motor / generator" or "regenerative generator"), a control unit EG for the regenerative device KG (also referred to as a "regenerative controller"), and a regenerative storage battery (not shown). The regenerative generator GN also serves as an electric motor for driving. During regenerative braking, the electric motor / generator GN operates as a generator, and the generated electric power is stored in the regenerative storage battery via the regenerative controller EG. At this time, a regenerative braking force Fg acts on the wheels. That is, the regenerative device KG can generate a regenerative braking force Fg. For example, the regenerative device KG is provided on the front wheels WHf, and a regenerative braking force Fg is generated on the front wheels WHf.

[0013] The front and rear wheels WHf, WHr of a vehicle are equipped with braking devices SX (=SXf, SXr). The braking devices SX are composed of a brake caliper, a friction member (e.g., brake pad), and a rotating member KT (e.g., brake disc). The brake caliper (not shown) is provided with a wheel cylinder CW (=CWf, CWr). A hydraulic pressure Pw (referred to as "wheel pressure") in the wheel cylinder CW presses the friction member (not shown) against a rotating member KT (=KTf, KTr) fixed to each wheel WH. This applies a braking torque Tb to the wheel WH. As a result, a hydraulic braking force Fp is generated in the wheel WH.

[0014] A vehicle is equipped with a brake operating member BP and various sensors (such as SP). The brake operating member BP (e.g., a brake pedal) is an operating member used by the driver to decelerate the vehicle. The vehicle is provided with an operation displacement sensor SP that detects an operation displacement Sp of the brake operating member BP. The operation displacement Sp is one of the state quantities (state variables) that indicate the operation amount of the brake operating member BP, and in a brake-by-wire type brake control device SA, it is a signal that indicates the driver's intention to brake (i.e., a braking command). In addition to the operation displacement sensor SP, a hydraulic pressure Pn (referred to as "input pressure") in an input chamber Rn (described later) is used as another state quantity that indicates the braking operation amount. The input pressure Pn is detected by an input pressure sensor PN. The operation displacement Sp, input pressure Pn, etc. are collectively referred to as the "braking operation amount Ba." Further, a sensor for detecting the braking operation amount Ba, such as the operation displacement sensor SP or the input pressure sensor PN, is referred to as a "braking operation amount sensor BA."

[0015] A vehicle is equipped with various sensors for braking control, such as antilock brake control and anti-skid control, which individually controls the wheel pressure Pw of each wheel WH. Specifically, each wheel WH is equipped with a wheel speed sensor VW that detects its rotational speed Vw (referred to as "wheel speed"). Also equipped are a steering amount sensor that detects the steering amount Sa (e.g., operation angle) of a steering operation member (e.g., a steering wheel), a yaw rate sensor that detects the yaw rate Yr of the vehicle, a longitudinal acceleration sensor that detects the longitudinal acceleration Gx (also referred to as "deceleration") of the vehicle, and a lateral acceleration sensor that detects the lateral acceleration Gy of the vehicle (all of which are not shown).

[0016] <Brake control device SA> The vehicle is equipped with a brake control device SA. The brake control device SA employs a so-called front and rear type (also called "type II") brake system as its two-system. The brake control device SA adjusts the hydraulic pressures Pwf, Pwr (front and rear wheel pressures) of the front and rear wheel cylinders CWf, CWr in response to the operation of the brake operating member BP (brake pedal). The brake control device SA is composed of an actuator YA and a controller EA. The brake control device SA integrates the actuator YA and the controller EA. The brake control device SA adjusts the actual wheel pressure Pw of each wheel cylinder CW.

[0017] <Actuator YA> The actuator YA is controlled by a controller EA. The actuator YA is composed of an apply unit AP, a hydraulic pressure generating unit PS, and an input unit NR. Each unit (AP, etc.) is formed in or assembled to the main housing HGc.

[0018] [Apply Unit AP] The apply unit AP is mounted to the main housing HGc. The apply unit AP outputs a supply pressure Pm in response to operation of the brake operating member BP. The apply unit AP is composed of a single master cylinder CM and a master piston NM.

[0019] A single-type master cylinder CM (i.e., a cylindrical hole, equivalent to a "first cylinder") is formed in the main housing HGc. A master piston NM is inserted into the single-type master cylinder CM. The interior of the master cylinder CM is divided into three hydraulic chambers Rm, Ru, and Rs by the master piston NM. The master chamber Rm is divided by the bottom of one side of the master cylinder CM and the master piston NM. The interior of the master cylinder CM is further divided into a servo chamber Ru and a reaction chamber Rs by a flange portion Tu of the master piston NM. In other words, the master chamber Rm and the servo chamber Ru are arranged opposite each other with the flange portion Tu in between. Here, the pressure-receiving area rm of the master chamber Rm and the pressure-receiving area ru of the servo chamber Ru are set to be equal.

[0020] When braking is not in progress, the master piston NM is in its most retracted position (i.e., the position where the volume of the master chamber Rm is maximum). In this state, the master chamber Rm of the master cylinder CM is connected to the master reservoir RV. Brake fluid BF is stored inside the master reservoir RV (also called the "atmospheric pressure reservoir"). When the brake operating member BP is operated, the master piston NM is moved forward in the direction Da (a direction in which the volume of the master chamber Rm decreases). This movement blocks communication between the master chamber Rm and the master reservoir RV. When the master piston NM is further moved forward in the direction Da, the supply pressure Pm (the internal pressure of the master chamber Rm, also called the "master pressure") increases from "0 (atmospheric pressure)." This causes brake fluid BF pressurized to the supply pressure Pm to be output (pressurized and fed) from the master chamber Rm of the master cylinder CM.

[0021] [Hydraulic Pressure Generating Unit PS] The hydraulic pressure generating unit PS is mounted in the main housing HGc. The hydraulic pressure generating unit PS generates a servo pressure Pc using an electric motor MT as a power source. The hydraulic pressure generating unit PS and the servo chamber Ru of the apply unit AP are connected via a servo path HU (fluid path). The hydraulic pressure generating unit PS and the rear wheel cylinder CWr are connected via a rear wheel communication path HSr (fluid path). Therefore, the front and rear wheel pressures Pwf and Pwr are regulated by the hydraulic pressure generating unit PS. The hydraulic pressure generating unit PS is connected to a master reservoir RV via a supply path HH (fluid path) so that brake fluid BF can be replenished if it becomes insufficient.

[0022] When the hydraulic pressure generating unit PS is operating (i.e., during braking), the supply line HH is blocked. This disconnects the hydraulic pressure generating unit PS from the master reservoir RV. In the front brake system, servo pressure Pc is supplied to the servo chamber Ru to generate a supply pressure Pm (master pressure). This supply pressure Pm then generates a hydraulic pressure Pwf (front wheel pressure) in the front wheel cylinder CWf. Meanwhile, in the rear brake system, servo pressure Pc is directly supplied to the rear wheel cylinder CWr to generate a hydraulic pressure Pwr (rear wheel pressure) in the rear wheel cylinder CWr. The hydraulic pressure generating unit PS is provided with a servo pressure sensor PC to detect the servo pressure Pc. Details of the hydraulic pressure generating unit PS will be described later.

[0023] [Input Unit NR] The input unit NR is mounted to the main housing HGc. The input unit NR realizes regenerative cooperative control. "Regenerative cooperative control" cooperates the hydraulic braking force Fp (braking force due to wheel pressure Pw) and the regenerative braking force Fg (braking force due to regenerative generator GN) so that the kinetic energy of the vehicle can be efficiently recovered as electrical energy during braking. In regenerative cooperative control, the brake operating member BP is operated, but a state is created in which the wheel pressure Pw is not generated. The input unit NR is composed of an input cylinder CN, an input piston NN, a first control valve VA, a second control valve VB, a stroke simulator SS, and an input pressure sensor PN.

[0024] An input cylinder CN (a cylindrical hole similar to the master cylinder CM) is formed in the main housing HGc. An input piston NN is inserted into the input cylinder CN. The input piston NN is mechanically connected to a brake operating member BP (brake pedal) via a clevis (U-shaped link) so as to move in conjunction with the movement of the brake operating member BP. A gap Ks (also referred to as the "separation distance") is defined between the end face of the input piston NN and the end face of the master piston NM. Cooperative regenerative control is achieved by adjusting the separation distance Ks using the servo pressure Pc.

[0025] The input chamber Rn of the input unit NR is connected to the reaction force chamber Rs of the apply unit AP via an input passage HN (a fluid passage formed in the main housing HGc). A normally closed first control valve VA is provided in the input passage HN. The input passage HN is connected to a master reservoir RV between the first control valve VA and the reaction force chamber Rs via a reservoir passage HR (a fluid passage formed in the main housing HGc). A normally open second control valve VB is provided in the reservoir passage HR. That is, the first and second control valves VA and VB are assembled to the main housing HGc. A stroke simulator SS is connected to the input passage HN between the first control valve VA and the reaction force chamber Rs.

[0026] The first and second control valves VA and VB are on-off solenoid valves. When no power is supplied to the first and second control valves VA and VB, the first control valve VA is closed and the second control valve VB is open. When the first control valve VA is closed, the input chamber Rn is sealed, resulting in a fluid lock. This allows the master piston NM to be displaced integrally with the brake operating member BP. When the second control valve VB is open, the stroke simulator SS and the reaction force chamber Rs are connected to the master reservoir RV. On the other hand, when power is supplied to the first and second control valves VA and VB, the first control valve VA is opened and the second control valve VB is closed. This allows the master piston NM to be displaced separately from the brake operating member BP. At this time, since the input chamber Rn is connected to the stroke simulator SS, the operating force of the brake operating member BP is generated by the stroke simulator SS.

[0027] The stroke simulator SS is mounted to the main housing HGc. Specifically, a simulator cylinder is formed in the main housing HGc. The simulator cylinder includes a simulator piston and an elastic body (e.g., a compression spring) (not shown). When brake fluid BF is moved into the stroke simulator SS, the simulator piston is pushed by the inflowing brake fluid BF. Because the elastic body applies a force to the simulator piston in a direction that prevents the inflow of brake fluid BF, when the brake operating member BP is operated, an operating force corresponding to the operating displacement Sp is generated.

[0028] An input pressure sensor PN is provided in the input passage HN between the input chamber Rn and the first control valve VA to detect the input pressure Pn, which is also the hydraulic pressure in the stroke simulator SS.

[0029] When power cannot be supplied to the components of the brake control device SA (MT, VA, VB, etc.) (i.e., when the power supply fails), the input chamber Rn is sealed, and the master piston NM is displaced integrally with the brake operating member BP. This state is called "manual mode." In manual mode, the master piston NM moves in conjunction with the movement of the brake operating member BP. In other words, the front wheel pressure Pwf is generated and adjusted by the supply pressure Pm, which is generated solely by the driver's muscle force.

[0030] When power can be supplied to the components of the brake control device SA (MT, VA, VB, etc.) (i.e., when the power supply is normal), the master piston NM and the brake operating member BP can be displaced separately. This state is called the "by-wire mode." In the by-wire mode, the front and rear wheel pressures Pwf and Pwr are generated and adjusted by the servo pressure Pc from the hydraulic pressure generating unit PS. In other words, the brake control device SA takes fail-safe into consideration, and generates hydraulic pressure Pw in the wheel cylinder CW by either the supply pressure Pm powered by the operating force of the brake operating member BP or the servo pressure Pc powered by the electric motor MT.

[0031] <Controller EA> The actuator YA is controlled by the controller EA. The controller EA is housed in a controller housing HGe. The controller housing HGe is attached to the main housing HGc. The controller EA is composed of a microprocessor MP and a drive circuit DR. The controller EA is connected to a communication bus BS so that signals (detected values, calculated values, control flags, etc.) can be shared between the various controllers (EB, EG, etc.).

[0032] The controller EA directly receives various signals such as the operation displacement Sp (detection value of the operation displacement sensor SP), the input pressure Pn (detection value of the input pressure sensor PN), the servo pressure Pc (detection value of the servo pressure sensor PC), and the motor rotation angle Ka (detection value of the rotation angle sensor KA). Furthermore, the controller EA also receives various signals such as the supply pressure Pm and the limit regenerative braking force Fx from the communication bus BS. The controller EA also outputs a target regenerative braking force Fh (target value of the regenerative braking force Fg) to the communication bus BS. The regenerative controller EG controls the regenerative braking force Fg (actual value) based on the target regenerative braking force Fh (target value) acquired from the communication bus BS.

[0033] The controller EA (particularly the microprocessor MP) is programmed with a pressure regulation control algorithm. "Pressure regulation control" is a control for adjusting the wheel pressure Pw (= Pwf, Pwr) and includes regenerative cooperative control. Pressure regulation control is performed based on the various signals (Sp, Pc, etc.) mentioned above.

[0034] The drive circuit DR drives the electric motor MT and various solenoid valves (VA, etc.) based on a pressure regulation control algorithm. The drive circuit DR includes an H-bridge circuit (also called an "inverter circuit") formed with switching elements (e.g., MOS-FETs) to drive the electric motor MT. The drive circuit DR also includes switching elements to drive the various solenoid valves. In addition, the drive circuit DR includes a motor current sensor (not shown) that detects the current Im (also called "motor current") supplied to the electric motor MT. The electric motor MT is provided with a rotation angle sensor KA to detect the position Ka (rotation angle) of the motor shaft SM.

[0035] The controller EA calculates drive signals Va and Vb for the first and second control valves VA and VB, and a drive signal Mt for the electric motor MT. The switching elements are then driven in response to the various drive signals (Mt, etc.). Specifically, in controlling the solenoid valves, the drive signals Va and Vb are determined so that power is supplied to the first and second control valves VA and VB. This opens the first control valve VA and closes the second control valve VB. In controlling the electric motor MT, a target pressure Pt is calculated based on the operating displacement Sp, etc. The "target pressure Pt" is a target value corresponding to the servo pressure Pc (actual value). The controller EA controls the electric motor MT in response to the target pressure Pt and the drive signal Mt calculated from the servo pressure Pc, so that the servo pressure Pc (actual value) approaches and matches the target pressure Pt (target value).

[0036] The modulator device SB is provided between the brake control device SA and the wheel cylinder CW. The modulator device SB executes anti-lock brake control to prevent wheel lock, traction control to prevent spin of the drive wheels, and anti-skid control (ESC) to prevent understeer and oversteer to improve the directional stability of the vehicle.

[0037] In the brake system for the front wheels WHf (i.e., the front wheel connecting passage HSf), a supply pressure Pm is supplied from a master cylinder CM to a modulator device SB. On the other hand, in the brake system for the rear wheels WHr (i.e., the rear wheel connecting passage HSr), a servo pressure Pc is supplied directly from a hydraulic pressure generating unit PS to the modulator device SB. The modulator device SB adjusts (increases or decreases) the supply pressure Pm and the servo pressure Pc, and outputs them as hydraulic pressures Pwf and Pwr (front and rear wheel pressures) for the front and rear wheel cylinders CWf and CWr. The modulator device SB is composed of an actuator YB and a controller EB.

[0038] The actuator YB of the modulator device SB is disposed in the communication path HS between the actuator YA of the brake control device SA and the wheel cylinder CW. The actuator YB includes an electric motor, a fluid pump, a solenoid valve, and a supply pressure sensor. The supply pressure Pm is detected by the supply pressure sensor (not shown). The supply pressure Pm is input to the controller EB. The configuration of the actuator YB is well known, so a description thereof will be omitted.

[0039] In the modulator device SB, the actuator YB is controlled by a controller EB. The controller EB is connected to a communication bus BS. Therefore, the controllers EA and EB can share signals via the communication bus BS. Various signals, such as the wheel speed Vw, the steering angle Sa, the yaw rate Yr, the longitudinal acceleration Gx, and the lateral acceleration Gy, are input to the controller EB. The controller EB calculates the vehicle speed Vx based on the wheel speed Vw. The controller EB performs anti-lock brake control, traction control, anti-skid control, etc. based on the various signals (Vw, Yr, etc.).

[0040] Normally, when the regenerative cooperative control is executed, the operation of the actuator YB is stopped. Therefore, the modulator device SB outputs the supply pressure Pm as the front wheel pressure Pwf and the servo pressure Pc as the rear wheel pressure Pwr.

[0041] <Hydraulic Pressure Generating Unit PS> An example configuration of the hydraulic pressure generating unit PS will be described with reference to the partial cross-sectional view of Figure 2. In the hydraulic pressure generating unit PS, an electric motor MT is used as a pressure source (also referred to as a "power source") to generate a servo pressure Pc. The wheel pressure Pw (= Pwf, Pwr) is ultimately adjusted by the servo pressure Pc.

[0042] <<Shapes and Directions of Movement of Constituent Members>> First, the shapes, directions of movement, etc. of the elements that constitute the hydraulic pressure generating unit PS will be defined. In the hydraulic pressure generating unit PS, the rotation axis Jm of the electric motor MT (particularly, the motor shaft SM), the rotation axis Jk of the rotating member BK, the central axis Jn of the control piston NC, and the central axis Jc of the control cylinder CC are aligned on a straight line. The direction along (i.e., the parallel direction to) the axes Jm, Jk, Jn, and Jc is referred to as the "axial direction Hj." In contrast, the direction perpendicular to the axes Jm, Jk, Jn, and Jc is referred to as the "radial direction Hk." Note that the rotation axis Jk of the rotating member BK is also the rotation axis of the bearing BC that supports the conversion mechanism GH (particularly, the rotating member BK).

[0043] In a member (NC, BD, etc.) that is movable along the axial direction Hj, the direction toward the bottom surface Mbc of the control cylinder CC is referred to as the "advance direction Ha." Conversely, the direction away from the bottom surface Mbc of the control cylinder CC is referred to as the "retraction direction Hb." Therefore, when the control piston NC moves in the advancement direction Ha, the volume of the control chamber Rc decreases, and its internal pressure Pc (servo pressure) increases. In contrast, when the control piston NC moves in the retraction direction Hb, the volume of the control chamber Rc increases, and the servo pressure Pc decreases.

[0044] In the relationship between the rotational motion of the electric motor MT and the linear motion of the linearly moving member BD (and consequently the control piston NC), the forward rotation direction Hs of the electric motor MT corresponds to the forward direction Ha of the linearly moving member BD. Conversely, the rotational motion of the electric motor MT in the reverse direction Hg corresponds to the backward direction Hb of the linearly moving member BD. Therefore, when the electric motor MT rotates in the forward rotation direction Hs, the linearly moving member BD moves in the forward direction Ha. This reduces the volume of the control chamber Rc and increases the servo pressure Pc. Conversely, when the electric motor MT rotates in the reverse direction Hg, the linearly moving member BD moves in the backward direction Hb. This increases the volume of the control chamber Rc and decreases the servo pressure Pc.

[0045] When a current Ims (also referred to as "forward current") is supplied to the electric motor MT to rotate it in the forward direction Hs, the direction of rotation of the electric motor MT is determined by the magnitude relationship between the torque output from the electric motor MT (also referred to as "forward operating torque") and the torque input to the electric motor MT by the servo pressure Pc (also referred to as "reverse operating torque"). Specifically, when the forward operating torque is greater than the reverse operating torque, the electric motor MT rotates in the forward direction Hs, and the servo pressure Pc is increased. When the forward operating torque and the reverse operating torque are equal, the electric motor MT does not rotate, and the servo pressure Pc is maintained. When the reverse operating torque is greater than the forward operating torque, the electric motor MT rotates in the reverse direction Hg, and the servo pressure Pc is decreased. In addition, when a current Img (called a "reverse current" and a current in the opposite direction to the forward current Ims) is supplied to rotate the electric motor MT in the reverse direction Hg, the electric motor MT is driven to rotate in the reverse direction Hg.

[0046] <Configuration of Hydraulic Pressure Generating Unit PS> The hydraulic pressure generating unit PS is made up of a sub-housing HGs, an electric motor MT, a rotation angle sensor KA, a speed reducer GS, a conversion mechanism GH, and a control piston NC, and is assembled to the main housing HGc.

[0047] The sub-housing HGs holds the components (MT, GS, GH, etc.) that make up the hydraulic pressure generating unit PS. The sub-housing HGs is divided into multiple parts to facilitate assembly of the components. For example, the sub-housing HGs is divided into a motor housing HGm and a gear housing HGg. In other words, the sub-housing HGs is a collective term for the motor housing HGm and the gear housing HGg. In other words, the motor housing HGm and the gear housing HGg are parts of the sub-housing HGs.

[0048] An electric motor MT is mounted to the motor housing HGm. The electric motor MT is a power source (pressure source) for generating a servo pressure Pc (hydraulic pressure in the control cylinder CC). Here, "power" refers to the energy required to move the movable members (BK, BD, etc.) in the hydraulic pressure generating unit PS. For example, power is defined as a physical quantity, i.e., energy per unit time (also referred to as "power"). The electric motor MT outputs rotational power Tm (also referred to as "first rotational power"). The rotational power Tm of the electric motor MT is calculated by multiplying the shaft torque of the electric motor MT by the rotational speed of the electric motor MT (particularly, the motor shaft SM). The linear power Fn of the linearly moving member BD (described below) is calculated by multiplying the thrust of the linearly moving member BD (force acting in the axial direction Hj) by the linear speed of the linearly moving member BD (speed in the axial direction Hj).

[0049] A three-phase brushless motor is used for the electric motor MT. The electric motor MT includes a motor coil CL, a motor shaft SM, and a rotation angle sensor KA. The motor coil CL (also simply referred to as a "coil (winding)") is fixed inside the motor housing HGm. The motor coil CL is also called a "stator." A motor line Lm is connected to the motor coil CL. Power is supplied from the controller EA (particularly, the drive circuit DR) via the motor line Lm.

[0050] The motor shaft SM (also simply referred to as the "shaft") is rotatably supported relative to the motor housing HGm (i.e., the motor coil CL) by a bearing BB (e.g., a bearing) fixed within the motor housing HGm. A motor magnet Mm (permanent magnet) is fixed to the outer periphery of the shaft SM of the electric motor MT. For example, the motor magnet Mm is affixed to the motor shaft SM by adhesive or the like. The motor shaft SM is also referred to as the "rotor."

[0051] In the three-phase brushless motor MT, the magnetic pole position of the rotor SM (i.e., the rotation angle relative to the stator CL) is detected to switch the current Im (motor current) flowing through the motor coil CL. Here, the motor current Im is a collective term for the currents flowing through the U, V, and W phases. The three-phase motor current Im corresponding to the U, V, and W phases is switched based on the rotational position Ka (also referred to as the "rotation angle") of the motor shaft SM. The electric motor MT (brushless motor) is provided with a rotational angle sensor KA to detect the rotational angle Ka for switching the three-phase currents. The detected rotational angle Ka is transmitted to the controller EA via the sensor line Ls. The controller EA drives the switching elements of the drive circuit DR in accordance with the rotational angle Ka. This switches the motor current Im flowing through the motor coil CL, thereby rotating the electric motor MT. A first rotational power Tm is then output from the electric motor MT to the reducer GS.

[0052] A reducer GS is attached to the gear housing HGg. A planetary gear mechanism is used for the reducer GS. The reducer GS (planetary gear mechanism) reduces the speed of the first rotational power Tm output from the electric motor MT and outputs a second rotational power Tn. Specifically, the reducer GS reduces the speed input from the electric motor MT and increases the torque input from the electric motor MT. The second rotational power Tn is then output from the reducer GS to the conversion mechanism GH.

[0053] The reducer GS (planetary gear mechanism) is a gear mechanism in which multiple planetary gears Gp revolve around a sun gear Gt while rotating on their own axes. The reducer GS is composed of a sun gear Gt, an internal gear Gu, planetary gears Sp, and a planet carrier Ca. The sun gear Gt (also called the "sun gear") is fixed to the motor shaft SM. Therefore, the sun gear Gt rotates integrally with the motor shaft SM. The internal gear Gu (also called the "inner gear") is fixed to the gear housing HGg so as not to rotate around the rotation axis Jk. The planetary gears Gp are supported by the planet carrier Ca and mesh with the sun gear Gt and the internal gear Gu.

[0054] The planet carrier Ca is rotatably supported on the gear housing HGg via a bearing BC (e.g., a bearing). For example, the planet carrier Ca is integrated with the bearing BC. Specifically, a groove is formed on the outer periphery of the planet carrier Ca, which serves as the inner ring of the bearing BC. The outer ring of the bearing BC is then press-fitted and fixed into the gear housing HGg. The planet carrier Ca is fixed to the rotating member BK of the conversion mechanism GH. In the reducer GS, a first rotational power Tm is input to the sun gear Gt from the electric motor MT (particularly, the motor shaft SM), and a second rotational power Tn is output from the planet carrier Ca to the conversion mechanism GH (particularly, the rotating member BK).

[0055] A partition plate SU is fixed to the internal gear Gu. A lubricant (e.g., grease) is used in the reducer GS, etc. The partition plate SU is provided to prevent the lubricant from scattering and affecting the electric motor MT, rotation angle sensor KA, etc. The partition plate SU has a disk shape and has a through-hole in the center so that the motor shaft SM can pass through. The partition plate SU may be fixed to the gear housing HGg or the motor housing HGm.

[0056] The conversion mechanism GH is held in a gear housing HGg. The conversion mechanism GH is composed of a rotating member BK that rotates and a linearly moving member BD that moves linearly. In the conversion mechanism GH, the rotating member BK is fixed to the reducer GS (particularly, the planetary carrier Ca). The conversion mechanism GH is rotatably supported in the gear housing HGg by a bearing BC (such as a bearing) that supports the planetary carrier Ca. Therefore, the rotation axis Jk of the rotating member BK is also the rotation axis Jk of the bearing BC.

[0057] Since the rotating member BK is connected to the planetary carrier Ca, the second rotational power Tn output from the planetary carrier Ca is input to the rotating member BK. The second rotational power Tn input to the rotating member BK is then converted into linear power Fn of the linearly moving member BD. The conversion mechanism GH is also called a "rotation-to-linear conversion mechanism."

[0058] The conversion mechanism GH is capable of both converting rotational motion to linear motion and converting linear motion to rotational motion. In the operation of the conversion mechanism GH, the former is referred to as "normal operation," and the latter is referred to as "reverse operation." Specifically, in normal operation, the rotational power of the rotating member BK is converted into linear power of the linearly moving member BD. In other words, in normal operation, the power is transmitted from the rotating member BK to the linearly moving member BD. In contrast, in reverse operation, the linear power of the linearly moving member BD is converted into rotational power of the rotating member BK. In other words, in reverse operation, the power is transmitted from the linearly moving member BD to the rotating member BK. The efficiency in normal operation (the ratio of the linear power output to the rotational power input) is referred to as "normal efficiency," and the efficiency in reverse operation (the ratio of the rotational power output to the linear power input) is referred to as "reverse efficiency." The conversion mechanism GH, which can transmit power in both directions, has both normal efficiency and reverse efficiency.

[0059] For example, a "ball screw" is employed as the conversion mechanism GH. Specifically, in the conversion mechanism GH, a rotating member BK, which is a shaft member, is fixed to a planetary carrier Ca of the reducer GS. The rotating member BK is inserted into a linearly moving member BD having a cylindrical shape. A ball screw groove Mzk is formed on the outer peripheral surface Mok of the rotating member BK. Similarly, a ball screw groove Mzd is also formed on the inner peripheral surface Mid of the linearly moving member BD. A plurality of balls BL (steel balls) are fitted into the ball screw grooves Mzk and Mzd (see blow-out section XGH for the above).

[0060] In a ball screw mechanism employed as the conversion mechanism GH, a ball screw shaft (an inner member, also referred to as a "shaft member") serves as the rotating member BK, and a ball screw nut (an outer member, also referred to as a "nut member") serves as the linear motion member BD. In this configuration, a screw groove Mzk is formed on the outer peripheral surface Mok of the rotating member BK (inner member), and a screw groove Mzd is formed on the inner peripheral surface Mid of the linear motion member BD (outer member). The outer peripheral groove Mzk and the inner peripheral groove Mzd are engaged with each other via a ball BL. Conversely, in a ball screw mechanism, the nut member (outer member) may serve as the rotating member BK, and the shaft member (inner member) may serve as the linear motion member BD.

[0061] The control piston NC (corresponding to the "second piston") is fixed to the linear motion member BD. A control cylinder CC (a cylindrical hole, corresponding to the "second cylinder") is formed in the main housing HGc. The control piston NC is inserted into the control cylinder CC. Specifically, the control piston NC has a cylindrical shape with a bottom. The outer peripheral surface Mon of the control piston NC is inserted into the inner peripheral surface Mic of the control cylinder CC. Specifically, two seal members SL are fitted into seal grooves formed in the inner peripheral surface Mic of the control cylinder CC. The seal members SL seal the outer peripheral surface Mon of the control piston NC and the inner peripheral surface Mic of the control cylinder CC.

[0062] A control chamber Rc (hydraulic pressure chamber) is formed inside the control cylinder CC by the control piston NC. The control cylinder CC (particularly the control chamber Rc) is provided with a discharge port (not shown, a hole that penetrates the main housing HGc). The discharge port (through hole) is connected to the servo path HU and the rear wheel communication path HSr. That is, the control chamber Rc is connected to the servo chamber Ru and the rear wheel cylinder CWr, so that the servo pressure Pc is supplied to the servo chamber Ru and the rear wheel cylinder CWr.

[0063] A rotation-preventing member MD is fixed to the main housing HGc. For example, the rotation-preventing member MD is a long, thin rod-shaped member (e.g., a pin member). The rotation-preventing member MD prevents the rotation of the linear motion member BD (rotation around the rotation axis Jk). The linear motion member BD has a flange portion Fd, and a notch into which the rotation-preventing member MD can be fitted is formed in the flange portion Fd. The rotation-preventing member MD engages with the notch, thereby restraining (limiting) the rotation of the linear motion member BD. Therefore, when the rotating member BK is rotationally driven, the linear motion member BD moves in the axial direction Hj (forward direction Ha or backward direction Hb).

[0064] The state in which the electric motor MT, speed reducer GS, conversion mechanism GH, and control piston NC are assembled into the sub-housing HGs (a collective term for HGm and HGg) is referred to as the "sub-assembly SY." Specifically, the components (CL, SM, KA, etc.) that make up the electric motor MT are assembled into the motor housing HGm. Furthermore, the speed reducer GS, conversion mechanism GH, and control piston NC are assembled into the gear housing HGg.

[0065] When the subassembly SY is viewed in the radial direction Hk, the bearing BC that supports the conversion mechanism GH is housed in the subhousing HGs (particularly the gear housing HGg), but the control piston NC protrudes from the subhousing HGs. Specifically, when projected parallel to the direction perpendicular to the rotation axis Jk of the bearing BC (i.e., in the radial direction Hk), the projection of the bearing BC overlaps with the projection of the gear housing HGg, but the projection of the control piston NC does not overlap with the projection of the gear housing HGg. Here, "projection" refers to the shadow of an object being projected onto a plane (projection surface), and refers to the projected image.

[0066] <Adjustment of Servo Pressure Pc> In the brake control device SA, the wheel pressure Pw is adjusted by the servo pressure Pc, which is the output of the hydraulic pressure generating unit PS. In the hydraulic pressure generating unit PS, the rotational power Tm (i.e., shaft torque) of the electric motor MT is converted by the conversion mechanism GH into linear power Fn (i.e., thrust) of the linearly moving member BD (resulting in the control piston NC). As a result, the servo pressure Pc is generated and adjusted as the control piston NC moves in the axial direction Hj. Specifically, the servo pressure Pc increases as the control piston NC moves in the forward direction Ha, and decreases as the control piston NC moves in the backward direction Hb. The adjustment (increase / decrease) of the servo pressure Pc will be described below. The hydraulic pressure generating unit PS is provided with a servo pressure sensor PC to detect the servo pressure Pc.

[0067] <<Increase in Servo Pressure Pc>> In Figure 2, above the rotation axis Jk, a state in which the hydraulic pressure generating unit PS does not generate the servo pressure Pc is illustrated. In this state, the control chamber Rc is connected to the master reservoir RV via the supply line HH, and the servo pressure Pc is "0 (atmospheric pressure)." The position of the linearly moving member BD in this state is referred to as the "initial position." Furthermore, the rotation angle Ka of the electric motor MT corresponding to the initial position is referred to as the "initial angle." In other words, the initial position corresponds to the zero point of the linearly moving member BD, and the initial angle corresponds to the zero point of the rotation angle Ka.

[0068] When the braking demand value (a state quantity indicating a demand for braking force, for example, the operating displacement Sp of the brake operating member BP) increases, the target pressure Pt is increased from "0". The target pressure Pt is a target value corresponding to the servo pressure Pc (actual value). The target pressure Pt increases as the braking demand value increases. As the target pressure Pt increases, the electric motor MT is driven in the forward rotation direction Hs to generate rotational power Tm. The rotational power Tm is transmitted to the conversion mechanism GH via the reducer GS and output as linear power Fn of the linearly moving member BD. The linearly moving member BD then moves the control piston NC in the forward direction Ha (the direction in which the volume of the control chamber Rc decreases). After the communication between the control chamber Rc and the master reservoir RV is cut off, the servo pressure Pc (the internal pressure of the control chamber Rc) is increased from "0 (atmospheric pressure)". As a result, brake fluid BF pressurized to servo pressure Pc is output from the control chamber Rc of the control cylinder CC to the servo chamber Ru via the servo path HU, and is also output to the rear wheel cylinder CWr via the rear wheel connection path HSr.

[0069] <<Maintaining Servo Pressure Pc>> When the braking demand value becomes constant, the target pressure Pt is maintained, and the servo pressure Pc is kept constant. For example, the linearly moving member BD is maintained at a position displaced from the initial position (see the lower part of the rotation axis Jk in FIG. 2). At this time, the rotational force input to the electric motor MT by reverse operation due to the servo pressure Pc (i.e., reverse operation torque) and the rotational force output from the electric motor MT by direct operation (i.e., direct operation torque) are balanced.

[0070] <<Decrease in Servo Pressure Pc>> When the braking demand value is decreased, the target pressure Pt is decreased. This decreases the rotational power Tm of the electric motor MT. The reverse acting torque of the servo pressure Pc becomes greater than the forward acting torque of the electric motor MT, causing the electric motor MT to rotate in the reverse direction Hg. The linearly moving member BD is moved in the reverse direction Hb, and the volume of the control chamber Rc is increased. The brake fluid BF that had been moved to the servo chamber Ru and the rear wheel cylinder CWr is returned toward the control chamber Rc, thereby decreasing the servo pressure Pc. Then, when the target pressure Pt is set to "0," the linearly moving member BD is returned to its initial position, and the servo pressure Pc is set to "0." As described above, in the hydraulic pressure generating unit PS, the control piston NC is moved along the rotation axis Jk by the linear power Fn, thereby adjusting (increasing, maintaining, or decreasing) the servo pressure Pc of the control cylinder CC.

[0071] <<Subassembly SY>> In the subassembly SY, the electric motor MT, the speed reducer GS, the conversion mechanism GH, and the control piston NC are assembled to the subhousing HGs (a collective term for HGm and HGg). Here, the speed reducer GS, the conversion mechanism GH, and the control piston NC transmit the power of the electric motor MT to generate the servo pressure Pc, and are therefore also referred to as "power transmission members." In other words, the power transmission members are assembled to the gear housing HGg. The motor housing HGm and the gear housing HGg are then combined to form the subassembly SY. Therefore, in the hydraulic pressure generating unit PS, the subassembly SY is both a power generation source and a power transmission member.

[0072] The main housing HGc is fitted with a plurality of cylinders (CM, CC, etc.) and a plurality of solenoid valves (VA, VB, etc.). The cylinders, solenoid valves, etc. are connected by fluid paths (HS, HU, etc.). The braking control device SA performs to its full potential when all of these components function (operate) normally.

[0073] The hydraulic pressure generating unit PS is the most important component of the brake control device SA. Furthermore, the hydraulic pressure generating unit PS is both complex and expensive. For this reason, in an integrated brake control device SA, the hydraulic pressure generating unit PS is inspected individually to ensure efficient inspection. Specifically, in the brake control device SA, only the subassembly SY is inspected. A suitability inspection of the subassembly itself is called a "unit inspection." In contrast, a suitability inspection of the entire brake control device SA, including the subassembly SY, is called a "total inspection." In the inspection of the brake control device SA, the unit inspection is first performed prior to the total inspection.

[0074] Once the unit inspection has confirmed that the subassembly SY operates normally, the sub-housing HGs (i.e., the sub-assembly SY) is assembled to the main housing HGc. This completes the brake control device SA (particularly the actuator YA). A final inspection (i.e., an overall inspection) of the brake control device SA is then performed. The overall inspection checks for leaks, the operation of the brake control device SA as a whole, and so on.

[0075] For example, let us consider an inspection procedure in which inspection at the subassembly stage (i.e., unit inspection) is omitted and inspection is only carried out after all elements constituting the brake control device SA are assembled. In such an inspection procedure, even if an abnormality in the brake control device SA is detected, it is not possible to identify which part is abnormal. Therefore, even if the abnormality is minor, the entire brake control device SA will be discarded.

[0076] In contrast, in the braking control device SA, a subassembly SY is first determined to be abnormal or normal (suitable or unsuitable) through a unit inspection. Then, a subassembly SY that is confirmed to be operating normally is assembled into the main housing HGc. Therefore, if an abnormality is determined in the overall inspection, the abnormality occurs in a location other than the subassembly SY. A subassembly SY that is confirmed to be operating normally is removed from the main housing HGc where the abnormality occurred and reassembled into another main housing HGc. In this way, in the braking control device SA, the inspection procedure is made more efficient through inspection through unit inspection. As a result, waste associated with scrapping components is reduced.

[0077] In the subassembly SY, the bearing BC that supports the reducer GS and the conversion mechanism GH (particularly the rotating member BK) is housed in the subhousing HGs, but at least the control piston NC protrudes from the subhousing HGs. Specifically, when projected parallel to the radial direction Hk (a direction perpendicular to the rotation axis Jk of the bearing BC), the projected image of the bearing BC and the projected image of the gear housing HGg overlap on the projection plane. In other words, the projections of the reducer GS and the conversion mechanism GH overlap in part with the projection of the gear housing HGg. In contrast, the projected image of the control piston NC and the projected image of the gear housing HGg do not overlap. By adopting this structure in the subassembly SY, unit inspection can be easily performed.

[0078] Furthermore, in the subassembly SY, the electric motor MT (particularly the electromechanical components) is positioned further outward relative to the main housing HGc. This allows the electric motor MT to be positioned appropriately and also allows the radial dimensions Hk of the components housed in the motor housing HGm to be increased. As a result, the degree of freedom in the mounting layout of the brake control device SA is improved.

[0079] <Assembling the Subassembly SY> A method for assembling the subassembly SY to the main housing HGc will be described with reference to the schematic diagram of FIG. 3 . The subassembly SY is detachably assembled to the main housing HGc. For example, the gear housing HGg, which supports the reducer GS and the conversion mechanism GH (particularly the rotating member BK), has a flange portion Fg extending in the radial direction Hk. The flange portion Fg of the gear housing HGg is provided with through holes Ag (through holes) for the bolts BT. Similarly, the motor housing HGm, which supports the electric motor MT, also has a flange portion Fm extending in the radial direction Hk. The flange portion Fm of the motor housing HGm is also provided with through holes Am (through holes) for the bolts BT.

[0080] The main housing HGc has female-threaded screw holes (also called "tapped holes"). The gear housing HGg and the motor housing HGm are fastened together to the main housing HGc via the through holes Ag and Am. "Fastened together" means that two or more members are fastened together while stacked. Specifically, bolts BT are passed through the through holes Ag and Am (through holes in the flange portions Fg and Fm) and tightened into the female-threaded holes in the main housing HGc. This allows the subassembly SY to be detachably fixed to the main housing HGc.

[0081] <First Unit Inspection Example of Subassembly SY> A first unit inspection example of the subassembly SY will be described with reference to the schematic diagram of FIG. 4. In the unit inspection, the subassembly SY is inspected individually before being assembled into the main housing HGc. Specifically, in the unit inspection, the operation of the components constituting the subassembly SY (i.e., the electric motor MT, the speed reducer GS, the conversion mechanism GH, and the control piston NC) is confirmed. If an abnormality is found in at least one of the electric motor MT, the speed reducer GS, the conversion mechanism GH, and the control piston NC, the subassembly SY is determined to be abnormal. On the other hand, if all of the electric motor MT, the speed reducer GS, the conversion mechanism GH, and the control piston NC are normal, the operation of the subassembly SY is determined to be normal.

[0082] In unit testing, the subassembly SY is attached to an inspection housing HGk, which is different from the main housing HGc. Then, unit testing is performed by combining the subassembly SY and the inspection housing HGk. An inspection cylinder CK is formed in the inspection housing HGk. Two seal members SL are fitted into seal grooves machined into the inner surface of the inspection cylinder CK. A rotation prevention member MD is also attached to the inspection cylinder CK. In the subassembly SY, a notch formed in the flange portion Fd of the linear motion member BD is fitted into the rotation prevention member MD. This prevents the linear motion member BD from rotating around the rotation axis Jk.

[0083] The subassembly SY (particularly, the control piston NC) is inserted into the inspection cylinder CK and sealed with a seal member SL. That is, the control piston NC forms an inspection chamber Rk (hydraulic chamber) in the inspection cylinder CK. A mechanism that generates elastic deformation due to hydraulic pressure is connected to the inspection chamber Rk. This mechanism is also called a "load mechanism" and corresponds to the wheel cylinder CW of the brake control device SA. The inspection chamber Rk and the load mechanism are filled with brake fluid BF. When the control piston NC is moved forward in the forward direction Ha by the electric motor MT, the brake fluid BF discharged from the inspection chamber Rk is absorbed by the load mechanism. The elastic deformation generated at this time applies a load to the electric motor MT. A test pressure sensor PK is provided in the inspection chamber Rk or the load mechanism to detect the hydraulic pressure Pk (also called "test pressure") in the inspection cylinder CK.

[0084] The subassembly SY is detachably fixed to the mounting holes At drilled in the inspection housing HGk. Specifically, the subassembly SY is fastened to the inspection housing HGk using fasteners (bolts, rings, etc.). For example, the subassembly SY is assembled to the inspection housing HGk using a method similar to the assembly method described with reference to FIG. 3. Specifically, the subhousing HGs and the inspection housing HGk are fastened together by bolts BT through through holes Ag and Am formed in the subhousing HGs (motor housing HGm and gear housing HGg). Alternatively, knock pins may be fixed to the inspection housing HGk, and positioning holes may be formed in the subhousing HGs. The position of the subassembly SY relative to the inspection housing HGk may be determined by the knock pins and positioning holes. In either case, the subassembly SY is fixed to the inspection housing HGk in a manner that allows it to be removed from the inspection housing HGk.

[0085] The motor wires Lm and the sensor wires Ls are drawn out from the sub-housing HGs and connected to an inspection controller EK (also called an "inspection device"), which includes a drive circuit for driving the electric motor MT and a microprocessor programmed with the inspection pattern PT.

[0086] The electric motor MT is driven by the inspection controller EK based on the inspection pattern PT. Specifically, a three-phase current Im is supplied to the electric motor MT via the motor line Lm to realize the inspection pattern PT. At this time, the three-phase current Im is switched based on the rotation angle Ka input via the sensor line Ls. The inspection controller EK determines whether the subassembly SY is operating normally. Specifically, the inspection pattern PT includes a time-series waveform for increasing, maintaining, and decreasing the inspection pressure Pk. The subassembly SY is determined to be operating normally or abnormally based on the inspection pressure Pk generated in response to the inspection pattern PT. Specifically, if the difference between the target pressure Pt in the inspection pattern PT and the detection value Pk (inspection pressure) of the inspection pressure sensor PK is within a predetermined range, the subassembly SY is determined to be normal.

[0087] Alternatively, the conformance of the subassembly SY may be determined based on the relationship between the rotation angle Ka and the test pressure Pk. The relationship between the rotation angle Ka and the test pressure Pk is predetermined in the characteristics of the load mechanism. Therefore, if the relationship between the rotation angle Ka and the test pressure Pk is within a predetermined range, the subassembly SY is determined to be normal. On the other hand, if the relationship is outside the predetermined range, the subassembly SY is determined to be abnormal. In either case, the conformance of the subassembly SY is determined based on the test pressure Pk.

[0088] When the subassembly SY operates normally, the electric motor MT, the reducer GS, the conversion mechanism GH, and the control piston NC all function normally. On the other hand, when the difference between the target pressure Pt and the test pressure Pk exceeds a predetermined range, an abnormality in the subassembly SY is identified. In this case, an abnormality has occurred in at least one of the electric motor MT, the reducer GS, the conversion mechanism GH, and the control piston NC. For example, when an abnormality is found in a unit test, it could be due to a "poor output of the electric motor MT," "reduced efficiency in the reducer GS and the conversion mechanism GH," or "fluid leakage in the control piston NC."

[0089] After the unit inspection is completed, the subassembly SY is removed from the inspection housing HGk. If the operation of the subassembly SY is normal, the subassembly SY is assembled to the main housing HGc. The assembly of the subassembly SY to the main housing HGc is also fixed in a removable state with fasteners. The subassembly SY is assembled to the main housing HGc, and an overall inspection is performed. If an abnormality is determined in the overall inspection, the subassembly SY is removed from the main housing HGc and assembled to another main housing HGc. Then, an overall inspection is performed again. In this way, in the braking control device SA, the subassembly SY is inspected individually in advance, thereby reducing waste associated with disposal.

[0090] <Second Unit Inspection Example of Subassembly SY> A second unit inspection example of subassembly SY will be described with reference to the schematic diagram of Figure 5. In the first unit inspection example, the inspection cylinder CK (particularly the inspection chamber Rk) formed in the inspection housing HGk was filled with hydraulic fluid BF (brake fluid), and a load was applied to the electric motor MT, which is the power source of the hydraulic pressure generating unit PS, by a load member connected to the inspection chamber Rk. Instead, in the second inspection example, the load is applied by an elastic body DK (e.g., a compression spring) arranged in the inspection cylinder CK. The following mainly describes the differences.

[0091] As in the first unit inspection example, in the second unit inspection example, the subassembly SY is mounted in an inspection housing HGk, which is different from the main housing HGc. An inspection cylinder CK is formed in the inspection housing HGk. An elastic body DK and a load sensor FK are provided in the inspection housing HGk between the bottom of the inspection cylinder CK and the bottom of the control piston NC. When the electric motor MT is driven and the control piston NC moves in the forward direction Ha, the elastic body DK is compressed and deformed. The inspection cylinder CK is provided with a load sensor FK that detects the elastic force Fk (also referred to as the "inspection load") of the elastic body DK against the control piston NC. In the second inspection example, the inspection cylinder CK is not filled with brake fluid BF.

[0092] The inspection force Fk in the second unit inspection example corresponds to the inspection pressure Pk in the first unit inspection example. The electric motor MT is driven by the inspection controller EK based on the inspection pattern PT. The inspection pattern PT includes a time-series waveform for increasing, maintaining, and decreasing the inspection force Fk. The subassembly SY's conformance (i.e., whether it is operating normally or abnormally) is determined based on the inspection force Fk generated in response to the inspection pattern PT. For example, in the second inspection example, the conformance of the subassembly SY is determined based on the relationship between the rotation angle Ka and the inspection force Fk. The relationship between the rotation angle Ka and the inspection force Fk is predetermined in the characteristics of the elastic body DK. Therefore, if the relationship between the rotation angle Ka and the inspection force Fk is within a predetermined range, the subassembly SY is determined to be normal. Conversely, if the relationship is outside the predetermined range, the subassembly SY is determined to be abnormal. In other words, the conformance of the subassembly SY (i.e., the unit inspection) is determined based on the inspection force Fk.

[0093] In the second unit inspection example, since the inspection chamber Rk is not filled with brake fluid BF, a leak at the control piston NC is determined by a leak test using gas (air, etc.). For example, in a leak test, gas is injected into the inspection chamber Rk, and the pressure (atmospheric pressure) in the inspection chamber Rk is increased. The presence or absence of a leak is then determined based on the change in air pressure. That is, if there is a leak, the air pressure will decrease, but if everything is normal, the air pressure will be maintained. Therefore, in the second unit inspection example, a unit inspection of the subassembly SY is performed, and the same effects as in the first unit inspection example are achieved.

[0094] <Other Embodiments of the Brake Control Device SA> Other embodiments of the brake control device SA will be described. In these other embodiments, the brake control device SA also achieves the same effects as those described above (such as improving the efficiency of unit inspections and eliminating waste due to disposal).

[0095] In the above-described embodiment of the brake control device SA, a single-type master cylinder CM is employed. However, the brake control device SA may also employ a tandem-type master cylinder CM. In this configuration, two master chambers Rm are formed inside the master cylinder CM. The hydraulic pressure generating unit PS supplies a servo pressure Pc to the servo chamber Ru, and the master chamber Rm supplies a wheel pressure Pw to the wheel cylinder CW. In this configuration, the brake control device SA may employ not only a front-rear type but also a diagonal type (also referred to as an "X type") brake system as the two-system brake system. In a diagonal-type brake control device SA, one of the two master chambers Rm is connected to the right front wheel cylinder and the left rear wheel cylinder. The other of the two master chambers Rm is connected to the left front wheel cylinder and the right rear wheel cylinder.

[0096] Even in a configuration employing a tandem master cylinder CM, in the event of a power failure, the input chamber Rn is sealed, causing the master piston NM and the brake operating member BP to displace together. In this state (manual mode), the front and rear wheel pressures Pwf and Pwr are generated and adjusted by the pressure Pm supplied by the driver's muscle force. On the other hand, when the power is normal, the master piston NM and the brake operating member BP can be displaced separately. In this state (by-wire mode), the front and rear wheel pressures Pwf and Pwr are generated and adjusted by the servo pressure Pc from the hydraulic pressure generating unit PS.

[0097] In the embodiment of the brake control device SA described above, the supply pressure Pm is output via the master cylinder CM. That is, the apply unit AP and the hydraulic pressure generating unit PS are arranged in series in the hydraulic pressure transmission path, and the servo pressure Pc supplied from the hydraulic pressure generating unit PS is transmitted as the supply pressure Pm via the master piston NM. Alternatively, the apply unit AP and the hydraulic pressure generating unit PS may be arranged in parallel. Specifically, the apply unit AP (particularly the master cylinder CM) and the hydraulic pressure generating unit PS are each directly connected to the actuator YB. An on-off solenoid valve (referred to as a "switching valve") selects either the connection between the hydraulic pressure generating unit PS and the actuator YB or the connection between the apply unit AP and the actuator YB. When the former is selected, the servo pressure Pc generated by the hydraulic pressure generating unit PS is directly output as the supply pressure Pm without passing through the apply unit AP. In this configuration, the apply unit AP is connected to the stroke simulator SS, and the operating force of the brake operating member BP is generated by the stroke simulator SS. On the other hand, when the latter is selected, the hydraulic pressure in the master chamber Rm generated by operating the brake operating member BP is output as the supply pressure Pm. In this configuration, the apply unit AP is disconnected from the simulator SS. In this configuration, the input cylinder CN, input piston NN, and first and second control valves VA and VB are omitted from the main housing HGc, and the above-mentioned selector valve is provided instead.

[0098] In a configuration in which the apply unit AP and the hydraulic pressure generating unit PS are arranged in parallel, the master piston NM always moves in conjunction with the brake operating member BP. In the event of a power failure, the apply unit AP is connected to the actuator YB, and the front and rear wheel pressures Pwf and Pwr are generated and adjusted by the supply pressure Pm generated by the driver's muscle force. On the other hand, when the power is normal, the hydraulic pressure generating unit PS is connected to the actuator YB, and the front and rear wheel pressures Pwf and Pwr are generated and adjusted by the servo pressure Pc generated by the hydraulic pressure generating unit PS. Even in this configuration, for fail-safe purposes, the hydraulic pressure Pw in the wheel cylinder CW is generated by either the supply pressure Pm powered by the operating force of the brake operating member BP or the servo pressure Pc powered by the electric motor MT. When the power is normal, the brake fluid BF discharged from the master cylinder CM is absorbed by the stroke simulator SS.

[0099] The above-described braking control device SA has been applied to a vehicle in which a regenerative device KG is provided on the front wheels WHf and in which regenerative cooperative control is performed. In a vehicle in which regenerative cooperative control is performed, the regenerative device KG only needs to be provided on at least one of the front wheels WHf and the rear wheels WHr. The braking control device SA can also be applied to a vehicle in which the regenerative device KG is omitted and in which regenerative cooperative control is not performed. In other words, the braking control device SA can be applied to various vehicles, regardless of whether regenerative cooperative control is performed or not.

[0100] In the above-described exemplary configuration of the hydraulic pressure generating unit PS, the conversion mechanism GH is fixed to the reducer GS, and the reducer GS is rotatably supported by the gear housing HGg via the bearing BC. That is, the conversion mechanism GH is supported by the bearing BC via the reducer GS. Alternatively, the conversion mechanism GH may be directly supported by the gear housing HGg. That is, a bearing supporting the conversion mechanism GH and a bearing supporting the reducer GS are provided separately. Even in this configuration, when the bearing supporting the conversion mechanism GH is projected parallel to the rotation axis Jk of the bearing (i.e., in the radial direction Hk), the projection of the bearing overlaps the projection of the gear housing HGg.

[0101] In the above-described exemplary configuration of the hydraulic pressure generating unit PS, a ball screw is used as the conversion mechanism GH. Alternatively, a sliding screw (e.g., a trapezoidal screw) may be used as the conversion mechanism GH. In a configuration in which a sliding screw mechanism is used, a male thread is formed as a screw groove on the inner member. Furthermore, a female thread is formed as a screw groove on the outer member. The male thread and the female thread are directly engaged with each other. Reverse operation can also occur in a conversion mechanism GH that uses a sliding screw.

[0102] Summary of the embodiment The embodiment of the brake control device SA will be summarized. The brake control device SA adjusts the wheel pressure Pw of the wheel cylinder CW to control the braking force of the wheel WH. The brake control device SA is composed of a main housing HGc, a master piston NM (first piston), an electric motor MT, a speed reducer GS, a conversion mechanism GH, a control piston NC (second piston), and a sub-housing HGs. A master cylinder CM (first cylinder) and a control cylinder CC (second cylinder) are formed in the main housing HGc.

[0103] The master piston NM is inserted into the master cylinder CM and moves in conjunction with the brake operating member BP to generate a supply pressure Pm within the master cylinder CM. In other words, if the power supply that supplies power to the brake control device SA fails, the supply pressure Pm is generated solely by the operating force of the brake operating member BP. The wheel pressure Pw is then generated by the supply pressure Pm.

[0104] The electric motor MT generates a first rotational power Tm. The reducer GS reduces the speed of the first rotational power Tm and outputs a second rotational power Tn. The conversion mechanism GH converts the second rotational power Tn into linear power Fn. The control piston NC is inserted into the control cylinder CC and is moved by the linear power Fn from the conversion mechanism GH, thereby generating a servo pressure Pc within the control cylinder CC. That is, when the power supply is normal, the wheel pressure Pw is generated by the servo pressure Pc.

[0105] The electric motor MT, the reducer GS, the conversion mechanism GH, and the control piston NC are supported (held) by a sub-housing HGs, which is then assembled to the main housing HGc.

[0106] The subassembly SY is a subhousing HGs to which the electric motor MT, reducer GS, conversion mechanism GH, and control piston NC are attached. The subassembly SY is the most important element of the brake control device SA (i.e., the power generation source for the hydraulic pressure generating unit PS and the power transmission member). In the brake control device SA, a unit inspection is performed before a full inspection so that at least the subassembly SY can be confirmed for suitability. Specifically, the subassembly SY is attached to an inspection housing HGk, which is different from the main housing HGc. The operation of the subassembly SY is then confirmed by combining the inspection housing HGk and the subassembly SY.

[0107] In the brake control device SA, the electric motor MT, the reducer GS, the conversion mechanism GH, and the control piston NC are held in a sub-housing HGs to facilitate individual inspection of the sub-assembly SY. The sub-housing HGs includes a gear housing HGg to which a bearing BC supporting the conversion mechanism GH is fixed. When the sub-assembly SY is projected parallel to the direction perpendicular to the rotation axis Jk of the bearing BC (i.e., the radial direction Hk), the projection of the bearing BC overlaps the projection of the gear housing HGg, but the projection of the control piston NC does not overlap the projection of the gear housing HGg. In other words, the bearing BC supporting the conversion mechanism GH is housed in the gear housing HGg, but the control piston NC protrudes from the sub-housing HGs. This structure allows the sub-assembly SY to be easily assembled to both the inspection housing HGk and the main housing HGc. This facilitates individual inspection of the brake control device SA. That is, the inspection efficiency can be improved and wasteful disposal can be reduced.

[0108] The subassembly SY is assembled to both the inspection housing HGk and the main housing HGc in a manner that allows for easy removal. For example, the motor housing HGm and the gear housing HGg have through holes Ag and Am. The motor housing HGm and the gear housing HGg are fastened together to the main housing HGc with bolts BT via the through holes Ag and Am. Similarly, the motor housing HGm and the gear housing HGg are fastened together to the inspection housing HGk with bolts BT via the through holes Ag and Am. This allows the subassembly SY to be fixed to the main housing HGc and the inspection housing HGk in a manner that allows for easy removal.

Claims

1. A vehicle brake control device comprising: a main housing in which first and second cylinders are formed; a first piston inserted into the first cylinder and capable of generating supply pressure in the first cylinder by moving in conjunction with a brake operating member; an electric motor that generates a first rotational power; a speed reducer that reduces the speed of the first rotational power and outputs a second rotational power; a conversion mechanism that converts the second rotational power into linear power; a second piston inserted into the second cylinder and moves using the linear power to generate servo pressure in the second cylinder; and a sub-housing that supports the electric motor, the speed reducer, the conversion mechanism, and the second piston and is assembled to the main housing.

2. A vehicle brake control device as described in claim 1, wherein the sub-housing includes a gear housing that fixes a bearing that supports the conversion mechanism, and when projected parallel to a direction perpendicular to the rotation axis of the bearing, the projection of the bearing overlaps with the projection of the gear housing, but the projection of the second piston does not overlap with the projection of the gear housing.

3. A vehicle brake control device as described in claim 2, wherein the sub-housing includes a motor housing that supports the electric motor, and the motor housing and the gear housing are fastened together to the main housing.

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