Hydraulic pressure generation device

Abstract

This hydraulic pressure generation device PS comprises: an electric motor MT that outputs rotation power Tm; a conversion mechanism GH that outputs the rotation power Tm input to a rotation member BK as linear power Fn of a linear motion member BD; a piston NC that is inserted into a cylinder CC and increases hydraulic pressure Pc of the cylinder CC by being moved by the linear power Fn; a housing HG in which the cylinder CC is formed and which holds a sealing member SL1 for sealing the cylinder CC and the piston NC; and a rotation stop member MD that is fixed to the housing HG and prevents the linear motion member BD from rotating around the rotation axis of the rotation member BK. In the hydraulic pressure generation device PS, when parallel projection is performed in a direction perpendicular to the rotation axis, a projection Zms of a sealing groove Ms1 for fixing the sealing member SL1 and a projection Zam of a hole Amd for fixing the rotation stop member MD partially overlap.

Description

Hydraulic Pressure Generator

[0001] The present disclosure relates to a hydraulic pressure generating device.

[0002] Patent Document 1 describes a piston pump assembly including an electric motor, a planetary gear, a worm gear, and a piston displaceable within a cylinder. Specifically, to prevent rotation of the piston within the cylinder, the piston includes a ring connected to the piston by form-fitting, and includes a semicircular groove on its outer periphery, into which a cylinder pin fixed parallel to the ring engages. The device in Patent Document 1 uses an electric motor as a power source to generate hydraulic pressure by movement of the piston, but such a hydraulic pressure generating device is desired to be compact in the axial direction from the viewpoint of installation on a vehicle.

[0003] US Patent Application Publication No. 2021 / 0122342

[0004] In view of the above problems, an object of the present invention is to provide a hydraulic pressure generating device whose axial dimension can be shortened.

[0005] The hydraulic pressure generating device (PS) of the present invention comprises an electric motor (MT) that outputs rotational power (Tm), a conversion mechanism (GH) that outputs the rotational power (Tm) input to a rotating member (BK) as linear power (Fn) of a linearly moving member (BD), a piston (NC) that is inserted into a cylinder (CC) and moves by the linear power (Fn) to increase the hydraulic pressure (Pc) of the cylinder (CC), a housing (HG) in which the cylinder (CC) is formed and which holds a seal member (SL1) that seals the cylinder (CC) and the piston (NC), and a rotation prevention member (MD) that is fixed to the housing (HG) and prevents the linearly moving member (BD) from rotating around the rotation axis (Jk) of the rotating member (BK).

[0006] In the hydraulic pressure generating device (PS) according to the present invention, when projected parallel to a direction (Hk) perpendicular to the rotation axis (Jk), a projection (Zms) of the seal groove (Ms1) that secures the seal member (SL1) and a projection (Zam) of the hole (Amd) that secures the anti-rotation member (MD) partially overlap. For example, the linear motion member (BD) has a notch that engages with the anti-rotation member (MD), thereby preventing the piston from rotating. Alternatively, the piston (NC) has a notch and is fixed to the linear motion member (BD), and the notch engages with the anti-rotation member (MD), thereby preventing the piston from rotating.

[0007] To fix the anti-rotation member MD, the mounting hole Amd needs to have a depth Lz (length in the axial direction Hj). With the above configuration, the depth required for the mounting hole Amd can be reduced, and the axial dimension (axial length) of the device can be shortened.

[0008] Fig. 1 is a schematic diagram for explaining the overall configuration of a brake control device SC; Fig. 2 is a partial cross-sectional view for explaining a first embodiment of a hydraulic pressure generating unit PS; Fig. 3 is a partial cross-sectional view for explaining a method of fixing a rotation-preventing member MD to a housing HG; Fig. 4 is a partial cross-sectional view for explaining a second embodiment of a hydraulic pressure generating unit PS; Fig. 5 is a partial cross-sectional view for explaining a third embodiment of a hydraulic pressure generating unit PS;

[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 first actuator YA of the first brake unit SA, the second actuator YB of the second brake unit SB, and the wheel cylinder CW are connected by a fluid path (communication path HS). Furthermore, the first and second actuators YA and YB are connected to various components (PS, etc.) by fluid paths. Here, the "fluid path" refers to a path for moving brake fluid BF (working fluid), and includes piping, flow paths within the actuators, 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 SC of vehicle> The overall configuration of the brake control device SC including the hydraulic pressure generating unit PS will be described with reference to the schematic diagram of Fig. 1. For example, the brake control device SC 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 called an "electric motor / generator" or "regenerative generator"), a control unit EG for the regenerative device KG (also called a "regenerative controller"), and a regenerative storage battery (not shown). The regenerative generator GN also functions 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. 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 a friction member (not shown) against a rotating member KT (=KTf, KTr) fixed to each wheel WH, thereby applying 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. 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." Furthermore, a sensor that detects the braking operation amount Ba, such as the operation displacement sensor SP or the input pressure sensor PN, is referred to as the "braking operation amount sensor BA."

[0015] The vehicle is equipped with a brake control device SC. The brake control device SC employs a so-called front and rear type (also called "type II") dual brake system. The brake control device SC adjusts the actual wheel pressure Pw of each wheel cylinder CW. The brake control device SC is composed of two brake units SA and SB.

[0016] <First brake unit SA> The first brake unit SA adjusts the hydraulic pressures Pwf and Pwr (front and rear wheel pressures) of the front and rear wheel cylinders CWf and CWr in response to the operation of the brake operating member BP (brake pedal). The first brake unit SA is composed of a first actuator YA and a first controller EA.

[0017] <<First Actuator YA>> The first actuator YA is composed of an apply unit AP, a hydraulic pressure generating unit PS, and an input unit NR.

[0018] [Apply Unit AP] 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 master piston NM is inserted into the single-type master cylinder CM. The master piston NM divides the interior of the master cylinder CM into three hydraulic chambers Rm, Ru, and Rs. The master chamber Rm is formed by the bottom 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 Tu of the master piston NM. The pressure-receiving area rm of the master chamber Rm and the pressure-receiving area ru of the servo chamber Ru are set equal to each other.

[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 (also referred to as a "hydraulic pressure generating device") uses an electric motor MT as its power source to generate front and rear wheel pressures Pwf and Pwr. The front and rear wheel pressures Pwf and Pwr are adjusted by a servo pressure Pc generated by the electric motor MT. Specifically, 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). Furthermore, 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 in the event of a shortage of brake fluid BF in the hydraulic pressure generating unit PS.

[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 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] The input cylinder CN is fixed to the master cylinder CM. 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) 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. The separation distance Ks is adjusted by the servo pressure Pc, thereby realizing regenerative cooperative control.

[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 path HN (fluid path). A normally closed first control valve VA is provided in the input path HN. The input path HN is connected to a master reservoir RV via a reservoir path HR (fluid path) between the first control valve VA and the reaction force chamber Rs. A normally open second control valve VB is provided in the reservoir path HR. On-off solenoid valves are used for the first and second control valves VA and VB. A stroke simulator SS is connected to the input path HN between the first control valve VA and the reaction force chamber Rs.

[0026] 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. Closing the first control valve VA seals the input chamber Rn, creating a fluid lock. This causes the master piston NM to displace integrally with the brake operating member BP. Opening the second control valve VB also connects the stroke simulator SS and the reaction chamber Rs to the master reservoir RV.

[0027] 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. Since the input chamber Rn is connected to the stroke simulator SS, the operating force for the brake operating member BP is generated by the stroke simulator SS. An input pressure sensor PN is provided in the input line HN between the input chamber Rn and the first control valve VA to detect the input pressure Pn. The input pressure Pn is also the hydraulic pressure within the stroke simulator SS.

[0028] <<First Controller EA>> The first controller EA controls the first actuator YA. The first controller EA is composed of a microprocessor MP and a drive circuit DR. The first controller EA is connected to a communication bus BS so that signals (detection values, calculation values, control flags, etc.) can be shared with other controllers (EB, EG, etc.).

[0029] The first 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 first controller EA receives various signals such as the supply pressure Pm and the limit regenerative braking force Fx from the communication bus BS. The first 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.

[0030] The first controller EA (particularly the microprocessor MP) is programmed with a pressure regulation control algorithm. "Pressure regulation control" is 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.) described above. Based on the pressure regulation control algorithm, the drive circuit DR drives the electric motor MT and various solenoid valves (VA, etc.). The drive circuit DR includes an H-bridge circuit (also referred to as an "inverter circuit") configured 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. Additionally, the drive circuit DR includes a motor current sensor (not shown) that detects the current Im (also referred to as "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.

[0031] The first 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 the control of the solenoid valves, power is supplied to the first and second control valves VA and VB based on the drive signals Va and Vb. This opens the first control valve VA and closes the second control valve VB. In the control of 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 first controller EA controls the electric motor MT in response to the target pressure Pt and the drive signal Mt calculated based on the servo pressure Pc, so that the servo pressure Pc (actual value) approaches and matches the target pressure Pt (target value).

[0032] <Second Brake Unit SB> A second brake unit SB is provided between the first brake unit SA and the wheel cylinder CW. The second brake unit SB performs antilock brake control, traction control, and skid prevention control. In the brake system for the front wheels WHf (i.e., the front wheel connecting path HSf), a supply pressure Pm is supplied from the master cylinder CM to the second brake unit SB. Meanwhile, in the brake system for the rear wheels WHr (i.e., the rear wheel connecting path HSr), a servo pressure Pc is directly supplied from the hydraulic pressure generating unit PS to the second brake unit SB. The second brake unit 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 configuration of the second brake unit SB is well known, so a detailed description thereof will be omitted.

[0033] Normally, when the regenerative cooperative control is executed, the operation of the second actuator YB (electric motor, fluid pump, solenoid valve, etc.) is stopped, and therefore the supply pressure Pm is output from the second brake unit SB as the front wheel pressure Pwf, and the servo pressure Pc is output as the rear wheel pressure Pwr.

[0034] <First Embodiment of Hydraulic Pressure Generating Unit PS> A first embodiment of a 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 (hydraulic pressure generating device), 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 then adjusted by the servo pressure Pc.

[0035] <<Shapes and Directions of Movement of Constituent Members>> First, the shapes, directions of movement, etc. of the elements that make up 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." Therefore, the radial direction Hk is perpendicular to the axial direction Hj.

[0036] 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 is moved in the advancement direction Ha, the volume of the control chamber Rc is reduced and its internal pressure Pc (servo pressure) is increased. Conversely, when the control piston NC is moved in the retraction direction Hb, the volume of the control chamber Rc is increased and the servo pressure Pc is reduced.

[0037] 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. Therefore, 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. In other words, 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.

[0038] <Configuration of Hydraulic Pressure Generating Unit PS> The hydraulic pressure generating unit PS is made up of a housing HG, an electric motor MT, a rotation angle sensor KA, a reducer GS, a conversion mechanism GH, a rotation stop member MD, and a control piston NC.

[0039] The housing HG holds the components (MT, GS, etc.) that make up the hydraulic pressure generating unit PS. The interior of the housing HG is separated into two spaces by a partition plate SK. One of the two spaces is a first storage chamber Ra (also simply referred to as the "first chamber"). The first chamber Ra houses the electric motor MT. The other of the two spaces is a second storage chamber Rb (also simply referred to as the "second chamber"). The second chamber Rb houses the reducer GS, conversion mechanism GH, etc.

[0040] The housing HG is divided into multiple parts so that the components can be assembled. For example, the housing HG is divided into a cylinder housing HGc and a motor housing HGm. The motor housing HGm and the cylinder housing HGc are assembled and ultimately integrated into the housing HG. In other words, the housing HG is a collective term for the cylinder housing HGc and the motor housing HGm. In other words, the cylinder housing HGc and the motor housing HGm are parts of the housing HG.

[0041] Furthermore, the housing HG may be integrated with the first controller EA. Specifically, the first controller EA is composed of a control board on which the microprocessor MP and the drive circuit DR are mounted, and a controller housing (not shown) that houses the control board. The controller housing is then assembled and integrated with the housing HG. The housing HG (particularly, the cylinder housing HGc) holds the reducer GS and the conversion mechanism GH. The housing HG (particularly, the motor housing HGm) also holds the electric motor MT.

[0042] A control cylinder CC (corresponding to a "cylinder") is formed in the housing HG (particularly, the cylinder housing HGc). A control piston NC (corresponding to a "piston") is inserted into the control cylinder CC. The control cylinder CC and the control piston NC form a control chamber Rc (hydraulic pressure chamber). A discharge portion Au is provided in the control cylinder CC (particularly, the control chamber Rc). The servo path HU and the rear wheel communication path HSr are connected to the discharge portion Au. That is, the control chamber Rc is connected to the servo chamber Ru and the rear wheel cylinder CWr. As a result, the servo pressure Pc is supplied (output) to the servo chamber Ru and the rear wheel cylinder CWr.

[0043] The electric motor MT is a power source (pressure source) for generating the 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).

[0044] A three-phase brushless motor is employed as the electric motor MT. The electric motor MT is mounted within a motor housing HGm. 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 within the motor housing HGm. The motor coil CL is also referred to as a "stator." A motor line Lm is connected to the motor coil CL. Power is supplied to the motor coil CL from a first controller EA (particularly, a drive circuit DR) via the motor line Lm.

[0045] 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 bearings BB 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."

[0046] 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, and the current Im (motor current) flowing through the motor coil CL is switched accordingly. 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 first controller EA drives the switching elements of the drive circuit DR (inverter circuit) in accordance with the rotational angle Ka. This switches the motor current Im flowing through the motor coil CL, driving the electric motor MT to rotate. Rotational power Tm is then output from the electric motor MT to the reducer GS.

[0047] A rotation angle sensor KA is provided in the electric motor MT (brushless motor) to detect a rotation angle Ka. The rotation angle sensor KA is composed of a sensor disk Ds, a sensor magnet Ms, a sensor board Kb, and a sensor wire Ls. The sensor disk Ds is fixed to the motor shaft SM so as to rotate integrally with the motor shaft SM. The sensor disk Ds is provided with a sensor magnet Ms. The sensor board Kb is fixed to the motor housing HGm. A hole is formed in the sensor board Kb so that the motor shaft SM passes through. A detection unit using a magnetic field detection element is provided around the hole to detect changes in the magnetic field that occur when the motor shaft SM (i.e., the sensor magnet Ms) rotates. A signal detected by the magnetic field detection element is transmitted to the first controller EA (particularly, the microprocessor MP) via the sensor wire Ls.

[0048] The reducer GS reduces the speed of the first rotational power Tm output from the electric motor MT and outputs a second rotational power Tn. Specifically, the input shaft of the reducer GS is fixed to the motor shaft SM. The output shaft of the reducer GS is also fixed to the rotating member BK of the conversion mechanism GH. 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.

[0049] For example, a planetary gear mechanism is used as the reducer GS. A "planetary gear mechanism" is a gear mechanism in which multiple planetary gears revolve around a sun gear while rotating on their axes. The reducer GS is composed of a sun gear, planetary gears, an internal gear, and a planetary carrier. In a planetary gear mechanism, the planetary gears are supported by the planetary carrier, and orbital motion is extracted. For example, in the reducer GS, the internal gear (also called the "inner gear") is fixed to the cylinder housing HGc. The sun gear (also called the "sun gear") is fixed to the motor shaft SM, and a first rotational power Tm is input to the sun gear from the electric motor MT. The planetary carrier of the reducer GS is fixed to the rotating member BK, and a second rotational power Tn is output from the planetary carrier to the conversion mechanism GH.

[0050] The conversion mechanism GH is composed of a rotating member BK that performs rotational motion and a linearly moving member BD that performs linear motion. In the conversion mechanism GH, the second rotational power Tn output from the reducer GS 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."

[0051] 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 the output shaft 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).

[0052] In the conversion mechanism GH, the member having a thread groove on its outer circumferential surface is referred to as the "inner member." The member having a thread groove on its inner circumferential surface is referred to as the "outer member." The outer member is disposed so as to cover the inner member, and the thread groove of the inner member and the thread groove of the outer member are engaged with each other. Specifically, in the ball screw mechanism, two thread grooves are engaged with each other via a plurality of balls BL.

[0053] In the 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.

[0054] A flange portion Fd is provided on the end of the linear motion member BD away from the control cylinder CC (particularly the control chamber Rc). The flange portion Fd is formed by extending the cylindrical end of the linear motion member BD in the radial direction Hk in a flange shape. A notch (an intentionally formed missing portion) is machined into the flange portion Fd. Here, the portion of the flange portion Fd where the notch is formed is referred to as the "fitting portion Kd."

[0055] The anti-rotation member MD is fixed to the cylinder housing HGc. For example, the anti-rotation member MD may be a long, thin rod-shaped member (e.g., a pin member). The housing HG has a plurality of holes Amd formed on the outer side of the linear motion member BD (i.e., on the side away from the rotation axis Jk of the linear motion member BD). These holes Amd are evenly spaced in the axial direction Hj around the rotation axis Jk. A anti-rotation member MD is inserted into and fixed to each of the holes Amd. A semicircular notch is formed in the flange portion Fd of the linear motion member BD. The notch (i.e., the fitting portion Kd) engages with the anti-rotation member MD, thereby preventing (restricting) rotation of the linear motion member BD around the rotation axis Jk. As a result, when the rotating member BK is rotationally driven, the linear motion member BD moves along the axial direction Hj (forward direction Ha or backward direction Hb).

[0056] The control piston NC is inserted into a control cylinder CC formed in the cylinder housing HGc. Specifically, the control piston NC has a cylindrical shape with a bottom Btn. That is, the control piston NC is cup-shaped. The control piston NC is inserted into the control cylinder CC. Inside the control cylinder CC, a control chamber Rc (hydraulic pressure chamber) is formed by the control piston NC (particularly the bottom Btn).

[0057] The outer peripheral surface Mon of the control piston NC and the inner peripheral surface Mic of the control cylinder CC are sealed by two seal members SL1 and SL2. The first and second seal members SL1 and SL2 are fitted into first and second seal grooves Ms1 and Ms2 formed in the inner peripheral surface Mic of the control cylinder CC. Specifically, the first seal groove Ms1 is formed on the side of the control cylinder CC far from the bottom surface Mbc. The first seal member SL1 is fixed to the first seal groove Ms1. Similarly, the second seal groove Ms2 is formed on the side of the control cylinder CC closer to the bottom surface Mbc, and the second seal member SL2 is fixed to the second seal groove Ms2. Between the two seal grooves Ms1 and Ms2, the cylinder housing HGc is provided with a hole (not shown, also referred to as a "housing hole") that penetrates the control cylinder CC. The housing hole is connected to the master reservoir RV via a supply line HH. The control piston NC is provided with a hole (not shown, also referred to as a "piston hole") that penetrates from the outer peripheral surface Mon to the bottom Btn to connect the housing hole and the control chamber Rc.

[0058] <Adjustment of Servo Pressure Pc> In the brake control device SC, 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). The control piston NC is then moved by the linear power Fn, thereby generating and adjusting the servo pressure Pc. Note that the hydraulic pressure generating unit PS is provided with a servo pressure sensor PC to detect the servo pressure Pc.

[0059] The conversion mechanism GH is capable of both converting rotary motion to linear motion and converting linear motion to rotary motion. The former operation of the conversion mechanism GH is called "direct operation," and the latter operation is called "reverse operation." Therefore, the movement of the control piston NC is determined by the magnitude relationship between the torque output from the electric motor MT (also called "direct operation torque Qmt") and the torque input to the electric motor MT by the servo pressure Pc (also called "reverse operation torque Qpc"). Adjustment (increase or decrease) of the servo pressure Pc will be described below.

[0060] <<Increase in Servo Pressure Pc>> In Figure 2, above the rotation axis Jk, a state in which the hydraulic pressure generating unit PS is not generating the servo pressure Pc is illustrated. In this state, the control chamber Rc is connected to the master reservoir RV via the housing hole and the piston hole, and the servo pressure Pc is "0 (atmospheric pressure)." The positions of the linearly acting member BD, the control piston NC, etc. in this state are referred to as the "initial position." In the initial position, the control piston NC is displaced to its maximum in the backward direction Hb, and the volume of the control chamber Rc is at its maximum.

[0061] 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 forward acting torque Qmt becomes greater than the reverse acting torque Qpc, and the electric motor MT rotates in the forward rotation direction Hs. In other words, the electric motor MT generates rotational power Tm in the forward rotation direction Hs. 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 presses the control piston NC. This moves the control piston NC forward in the direction Ha (the direction in which the volume of the control chamber Rc decreases).

[0062] This movement first cuts off communication between the control chamber Rc and the master reservoir RV. As the control piston NC moves further forward in the direction Ha, the servo pressure Pc (internal pressure of the control chamber Rc) increases from "0 (atmospheric pressure)." Brake fluid BF pressurized to the servo pressure Pc is output (pressurized and fed) from the control chamber Rc of the control cylinder CC to the servo chamber Ru and the rear wheel cylinder CWr.

[0063] <Maintaining Servo Pressure Pc> When the braking demand value becomes constant, the target pressure Pt is maintained. The forward acting torque Qmt and the reverse acting torque Qpc become equal, and the rotation of the electric motor MT stops (i.e., the rotational speed of the electric motor MT becomes "0"). By stopping the movement of the control piston NC, the servo pressure Pc is maintained constant (see below the rotation axis Jk in Figure 2).

[0064] <<Decrease in Servo Pressure Pc>> When the braking demand value is reduced, the target pressure Pt is reduced. This reduces the rotational power Tm of the electric motor MT. The reverse acting torque Qpc due to the servo pressure Pc becomes greater than the forward acting torque Qmt due to the electric motor MT, causing the electric motor MT to rotate in the reverse direction Hg. The control piston NC is moved in the reverse direction Hb, increasing the volume of the control chamber Rc. 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 reducing the servo pressure Pc. 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.

[0065] <Fixing the anti-rotation member MD to the housing HG> A method for fixing the anti-rotation member MD to the housing HG (e.g., the cylinder housing HGc) will be described with reference to the partial cross-sectional view of Figure 3. Figure 3(a) shows a structure employed in the hydraulic pressure generating unit PS. Figure 3(b) shows a structure employed in the prior art (e.g., U.S. Patent Application Publication No. 2021 / 0122342).

[0066] A pin member is used as the anti-rotation member MD. The housing HG is provided with a hole Amd (also referred to as a "mounting hole") and a groove Mmd (also referred to as a "mounting groove") for mounting the anti-rotation member MD. For example, a surface Mm (also referred to as a "fixing surface") perpendicular to the rotation axis Jk is formed inside the housing HG (particularly within the second chamber Rb). The mounting hole Amd is then drilled perpendicular to the fixing surface Mm. Therefore, the mounting hole Amd is parallel to the rotation axis Jk (i.e., the axial direction Hj). Furthermore, a semicircular mounting groove Mmd is formed so as to be continuous with the mounting hole Amd. More specifically, the mounting groove Mmd is connected to the mounting hole Amd and is carved in a semicircular shape (i.e., a semicircular shape, also referred to as a "half-moon shape") parallel to the rotation axis Jk (i.e., the axial direction Hj).

[0067] The anti-rotation member MD is fixed by being press-fitted into the mounting hole Amd while fitted into the mounting groove Mmd. The portion of the anti-rotation member MD that protrudes from the mounting groove Mmd (referred to as the "guide portion") engages with the fitting portion Kd. The fitting portion Kd slides along the guide portion, thereby preventing the linear motion member BD from rotating around the rotation axis Jk.

[0068] First and second seal grooves Ms1 and Ms2 are provided on the inner circumferential surface Mic of the control cylinder CC. First and second seal members SL1 and SL2 are fitted into the first and second seal grooves Ms1 and Ms2. The first and second seal members SL1 and SL2 seal between the inner circumferential surface Mic of the control cylinder CC and the outer circumferential surface Mon of the control piston NC. Here, the first seal groove Ms1 and the first seal member SL1 are arranged on the far side (distant side) from the bottom surface Mbc of the control cylinder CC, and the second seal groove Ms2 and the second seal member SL2 are arranged on the closer side from the bottom surface Mbc.

[0069] Referring to FIG. 3A, the positional relationship between the mounting hole Amd and the first seal groove Ms1 employed in the hydraulic pressure generating unit PS will be described. In the hydraulic pressure generating unit PS, the mounting hole Amd of the anti-rotation member MD overlaps with the first seal groove Ms1, to which the first seal member SL1 is attached, in the direction along the rotation axis Jk. This structure is referred to as an "overlapping structure." Specifically, in the overlapping structure, as shown in the blowout portion ZMa, when parallel projection is performed in a direction perpendicular to the rotation axis Jk (i.e., the radial direction Hk), the image Zam (projection) of the mounting hole Amd projected on the projection plane ME and the image Zms (projection) of the first seal groove Ms1 projected on the projection plane ME have an overlapping portion. In other words, in the overlap structure adopted by the hydraulic pressure generating unit PS, the mounting hole Amd exists in a cross section perpendicular to the rotation axis Jk, which includes the first seal groove Ms1 (see the A-A cross section). Note that "projection" refers to the projection of the shadow of an object onto a plane, and refers to the projected image (shadow).

[0070] 3B, the positional relationship between the mounting hole Amd and the first seal groove Ms1 employed in the above-described conventional technology will be described. In the conventional technology, the mounting hole Amd of the anti-rotation member MD does not overlap with the first seal groove Ms1 for mounting the first seal member SL1. Therefore, in a parallel projection in the radial direction Hk, the projection Zam of the mounting hole Amd and the projection Zms of the first seal groove Ms1 do not overlap. In other words, the mounting hole Amd does not exist in a cross section perpendicular to the rotation axis Jk that includes the first seal groove Ms1 (see the B-B cross section).

[0071] The adoption of an overlap structure makes it possible to shorten the dimension in the axial direction Hj (also referred to as the "axial length") of the hydraulic pressure generating unit PS. The mounting hole Amd for fixing the anti-rotation member MD requires a certain length Lz (hole depth). The flange portion Fd of the linear motion member BD slides in engagement with the guide portion of the anti-rotation member MD (the portion that protrudes from the mounting groove Mmd). The guide portion is the portion of the anti-rotation member MD that is not inserted into the mounting hole Amd and corresponds to the mounting groove Mmd. The length of the guide portion (i.e., the mounting groove Mmd) in the axial direction Hj must be equal to or greater than the maximum displacement of the control piston NC.

[0072] For example, if an overlapping structure is not adopted, the mounting groove Mmd would need to be separated from the first seal groove Ms1 by at least the length Lz of the mounting hole Amd. Therefore, in the hydraulic pressure generating unit PS, the mounting hole Amd is positioned so that it overlaps the first seal groove Ms1 when viewed in the radial direction Hk. By adopting an overlapping structure in the hydraulic pressure generating unit PS, the length Lz (depth) required for the mounting hole Amd can be saved, thereby reducing the size of the device (i.e., shortening the axial length). Although the overlapping structure shortens the axial length, it is disadvantageous in terms of the dimensions in the radial direction Hk. However, in the hydraulic pressure generating unit PS, the rotational axis Jm of the electric motor MT and the rotational axis Jk of the rotating member BK are aligned, so there is dimensional margin in the radial direction Hk. Therefore, shortening the axial length is a higher priority than reducing the size in the radial direction Hk.

[0073] <Second Embodiment of Hydraulic Pressure Generating Unit PS> A second embodiment of the hydraulic pressure generating unit PS will be described with reference to the partial cross-sectional view of FIG. 4 . In the first embodiment, a notch (i.e., first fitting portion Kd) formed in a flange portion Fd (also referred to as the "first flange portion") of the linear motion member BD is fitted into a rotation prevention member MD (particularly, a guide portion that is not inserted into the mounting hole Amd but protrudes from the mounting groove Mmd), thereby preventing rotation of the linear motion member BD. In the second embodiment, a flange portion Fe (also referred to as the "second flange portion") is provided at the end of the control piston NC, and a fitting portion Ke formed by machining a notch into the flange portion Fe is provided. The fitting portion Ke (second fitting portion) then engages with a guide portion of the rotation prevention member MD. The following mainly describes the differences. Note that the shapes of the components and the directions of movement are the same as those of the first embodiment.

[0074] In the second embodiment, as in the first embodiment, a ball screw mechanism is employed for the conversion mechanism GH. In the conversion mechanism GH, a linear motion member BD (ball screw nut), which is an outer member, is disposed so as to cover a rotating member BK (ball screw shaft), which is an inner member, and the respective screw grooves Mzk and Mzd are engaged with each other via a ball BL. The control piston NC is fixed to the linear motion member BD and can move integrally therewith.

[0075] In the second embodiment, a flange portion Fe is provided on the end of the control piston NC farther from the bottom surface Mbc of the control cylinder CC. Similar to the flange portion Fd in the first embodiment, the flange portion Fe extends the cylindrical end of the control piston NC in a flange-like shape in the radial direction Hk. The flange portion Fe has a fitting portion Ke (a portion having a notch). The anti-rotation member MD is fixed to the housing HG by the overlap structure described above. The fitting portion Ke of the flange portion Fe engages with the guide portion of the anti-rotation member MD (a portion that is not inserted into the mounting hole Amd but protrudes from the mounting groove Mmd). The fitting portion Ke then slides along the guide portion. This limits the rotational movement of the control piston NC (and consequently, the linearly acting member BD).

[0076] <Third Embodiment of Hydraulic Pressure Generating Unit PS> A third embodiment of a hydraulic pressure generating unit PS will be described with reference to the partial cross-sectional view of Figure 5. In the first and second embodiments, the linearly moving member BD is used as the outer member and the rotating member BK is used as the inner member in the conversion mechanism GH. Conversely, in the third embodiment, the outer member (nut member) is the rotating member BK and the inner member (shaft member) is the linearly moving member BD. The following description will focus on differences from the first and second embodiments. Note that the shapes of the constituent members and the directions of their movements are the same as in the first and second embodiments.

[0077] In the third embodiment, as in the first and second embodiments, a ball screw mechanism is employed for the conversion mechanism GH. In the conversion mechanism GH according to the third embodiment, a linear motion member BD, which is a ball screw shaft, and a rotating member BK, which is a ball screw nut, are engaged with each other via balls BL. In the third embodiment, the control piston NC is also fixed to the linear motion member BD and can move integrally therewith.

[0078] In the third embodiment, similar to the second embodiment, a flange portion Fe (second flange portion) is provided on the end of the control piston NC (the side farther from the bottom surface Mbc of the control cylinder CC). The flange portion Fe extends radially in the Hk direction, forming a flange-like shape at the end of the cylindrical control piston NC. The flange portion Fe is provided with a fitting portion Ke (second fitting portion) having a notch to engage with the anti-rotation member MD. The anti-rotation member MD is fixed to the housing HG by the above-described overlap structure (i.e., a structure in which the projection Zms of the seal groove Ms1 of the first seal member SL1 overlaps with the projection Zam of the mounting hole Amd of the anti-rotation member MD). The fitting portion Ke slides along the guide portion of the anti-rotation member MD, thereby restricting the rotational movement of the control piston NC (and consequently, the linearly acting member BD).

[0079] Other Embodiments of the Hydraulic Pressure Generating Unit PS Other embodiments of the hydraulic pressure generating unit PS will be described. In these other embodiments, the hydraulic pressure generating unit PS also achieves the same effects as those described above (such as a reduction in the axial dimension due to the overlap structure).

[0080] In the above-described embodiment 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 occurs even in a conversion mechanism GH in which a sliding screw is used.

[0081] In the embodiment of the hydraulic pressure generating unit PS described above, a configuration is adopted in which the axis Jm and the axes Jc, Jn, and Jk are aligned in a straight line. This configuration is referred to as a "coaxial configuration (or single-shaft configuration)" because the axis Jm and the axis Jc, etc. are coaxial. In a coaxial configuration, a reducer GS is used in which the rotation axis of the input shaft and the rotation axis of the output shaft are coaxial (e.g., a planetary gear mechanism). Alternatively, a "separate-shaft configuration (or two-shaft configuration)" may be adopted in which the axis Jm and the axes Jc, Jn, and Jk are on separate axes. In a separate-shaft configuration, a reducer GS is used in which the rotation axis of the input shaft and the rotation axis of the output shaft are different (e.g., a gear train). In a separate-shaft configuration, the axis Jm and the axes Jc, Jn, and Jk are separate axes but arranged parallel to each other. Even in the separate-axis configuration, the axes Jc, Jn, and Jk are aligned. However, as mentioned above, in the coaxial configuration, shortening the axial length is more desirable, so the overlap structure is very effective.

[0082] In the embodiment of the hydraulic pressure generating unit PS described above, the mounting hole Amd overlaps the first seal groove Ms1. Alternatively, the mounting hole Amd may overlap both the first and second seal grooves Ms1, Ms2. That is, two seal grooves Ms1, Ms2 are formed in the housing HG of the hydraulic pressure generating unit PS, and the mounting hole Amd is machined to overlap at least the first seal groove Ms1 (the side farthest from the bottom surface Mbc).

[0083] In the embodiment of the hydraulic pressure generating unit PS described above, two seal members SL1, SL2 are used to seal the control piston NC and the control cylinder CC. Alternatively, in the hydraulic pressure generating unit PS, the second seal member SL2 may be omitted, and sealing may be performed by a single seal member SL1. In this configuration, the mounting hole Amd also overlaps with the seal groove Ms1 that holds the seal member SL1.

[0084] The above-described braking control device SC is 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 SC can also be applied to a vehicle in which the regenerative device KG is power-saving and in which regenerative cooperative control is not performed. In other words, the braking control device SC can be applied to various vehicles regardless of whether regenerative cooperative control is performed or not.

[0085] In the above-described exemplary configuration of the brake control device SC, a single-type master cylinder CM is employed. However, the brake control device SC may also employ a tandem-type master cylinder CM. In this configuration, two master chambers Rm are formed inside the CM. A servo pressure Pc is supplied from the hydraulic pressure generating unit PS to the servo chamber Ru, and a wheel pressure Pw is supplied from the master chamber Rm to the wheel cylinder CW. In this configuration, the brake control device SC may employ not only a front-rear type but also a diagonal type (also called an "X type") brake system as the two-system brake system. In a diagonal-type brake control device SC, 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.

[0086] In the above-described exemplary configuration of the brake control device SC, the first brake unit SA outputs the supply pressure Pm 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 second 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 second actuator YB or the connection between the apply unit AP and the second 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 case, 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 the operation of the brake operating member BP is output as the supply pressure Pm. In this case, the apply unit AP is disconnected from the stroke simulator SS.

[0087] In the above-described exemplary configuration of the brake control device SC, the pressure-receiving area rm (master area) of the master chamber Rm and the pressure-receiving area ru (servo area) of the servo chamber Ru in the apply unit AP are set equal. The master area rm and the servo area ru do not have to be equal. In a configuration in which the master area rm and the servo area ru are different, the supply pressure Pm (master pressure) can be converted to the servo pressure Pc based on the ratio of the servo area ru to the master area rm (i.e., conversion based on "Pm rm = Pc ru").

[0088] Summary of the Embodiments The following summarizes the embodiments of the hydraulic pressure generating unit PS (hydraulic pressure generating device). The hydraulic pressure generating unit PS is applied to a braking control device SC that adjusts the wheel pressure Pw of the wheel cylinder CW to control the braking force of the wheel WH.

[0089] The hydraulic pressure generating unit PS includes a housing HG, an electric motor MT, a conversion mechanism GH, a control piston NC (corresponding to a "piston"), a seal member SL1, and a rotation-preventing member MD. The housing HG holds the conversion mechanism GH and other components. A control cylinder CC (corresponding to a "cylinder") is formed in the housing HG. The electric motor MT outputs rotational power Tm. The conversion mechanism GH outputs the rotational power Tm input to the rotating member BK as linear power Fn of the linearly moving member BD. The control piston NC is inserted into the control cylinder CC and moves forward in the forward direction Ha (toward the bottom surface Mbc of the control cylinder CC) due to the linear power Fn, thereby increasing the hydraulic pressure Pc of the control cylinder CC. The seal member SL1 is fixed (held) in a seal groove Ms1 provided in the housing HG and seals the control cylinder CC (particularly, the inner circumferential surface Mic) and the control piston NC (particularly, the outer circumferential surface Mon). The anti-rotation member MD is fixed to the housing HG and prevents (restricts) the linear motion member BD from rotating around the rotation axis Jk of the rotating member BK. Here, the anti-rotation member MD is fixed to a mounting hole Amd provided in the housing HG.

[0090] When the hydraulic pressure generating unit PS is parallel-projected in a direction perpendicular to the rotation axis Jk (i.e., the radial direction Hk), the projection (image) Zms of the seal groove Ms1 that secures the seal member SL1 overlaps with a portion of the projection (image) Zam of the hole Amd (mounting hole) that secures the anti-rotation member MD. In other words, the mounting hole Amd exists in a cross section in the radial direction Hk that includes the seal groove Ms1. While the mounting hole Amd requires a certain length to secure the anti-rotation member MD, the adoption of an overlapping structure makes it possible to shorten the axial length required for the mounting hole Amd. As a result, the hydraulic pressure generating unit PS can be made more compact.

[0091] In the hydraulic pressure generating unit PS, a fitting portion Kd (first fitting portion) having a notch is provided on the linear motion member BD. The fitting portion Kd is engaged with the anti-rotation member MD, thereby restricting rotation of the linear motion member BD (i.e., preventing rotation). Alternatively, the control piston NC is fixed to the linear motion member BD, and a fitting portion Ke (second fitting portion) having a notch is provided on the control piston NC. The fitting portion Ke is engaged with the anti-rotation member MD, thereby preventing rotation.

[0092] For example, a pin member with a circular cross section is used as the anti-rotation member MD. A plurality of circular mounting holes Amd are formed in the housing HG along the rotation axis Jk. The mounting holes Amd are formed at equal intervals around the rotation axis Jk. The plurality of anti-rotation members MD (pin members) are inserted into each of the mounting holes Amd, thereby fixing the plurality of anti-rotation members MD. A fitting portion Kd (or a fitting portion Ke) having a semicircular notch is provided on the flange portion Fd of the linear motion member BD (or the flange portion Fe of the control piston NC). The fitting portion Kd (or the fitting portion Ke) engages with the anti-rotation member MD (particularly, the guide portion not inserted into the mounting hole Amd), thereby restraining (restricting) the rotational movement of the linear motion member BD.

[0093] The anti-rotation member MD may be a key member having a square cross section. In a configuration in which a key member is used, the mounting hole Amd is a square hole. The fitting portion Kd (or the fitting portion Ke) is machined with a square notch that can fit the anti-rotation member MD (key member).

Claims

1. A hydraulic pressure generating device comprising: an electric motor which outputs rotational power; a conversion mechanism which outputs the rotational power input to a rotating member as linear power for a linearly moving member; a piston which is inserted into a cylinder and moves by the linear power to increase the hydraulic pressure in the cylinder; a housing in which the cylinder is formed and which holds a seal member which seals the cylinder and the piston; and a rotation prevention member which is fixed to the housing and prevents the linearly moving member from rotating around the rotation axis of the rotating member, wherein, when projected parallel in a direction perpendicular to the rotation axis, a projection of a seal groove which fixes the seal member and a projection of a hole which fixes the rotation prevention member partially overlap.

2. A hydraulic pressure generating device as described in claim 1, wherein the linear motion member has a notch, and the prevention is performed by engaging the notch with the rotation prevention member.

3. A hydraulic pressure generating device as described in claim 1, wherein the piston has a notch and is fixed to the linear motion member, and the notch is engaged with the anti-rotation member to prevent the rotation.

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