WO2023054000A1 - Capteur de charges et système de freinage électrique - Google Patents

Capteur de charges et système de freinage électrique Download PDF

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Publication number
WO2023054000A1
WO2023054000A1 PCT/JP2022/034641 JP2022034641W WO2023054000A1 WO 2023054000 A1 WO2023054000 A1 WO 2023054000A1 JP 2022034641 W JP2022034641 W JP 2022034641W WO 2023054000 A1 WO2023054000 A1 WO 2023054000A1
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WO
WIPO (PCT)
Prior art keywords
load
strain
brake
sensor
amount
Prior art date
Application number
PCT/JP2022/034641
Other languages
English (en)
Japanese (ja)
Inventor
聖 志水
武 金澤
將人 坂田
真宏 巻田
Original Assignee
株式会社デンソー
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP2022133460A external-priority patent/JP2023050103A/ja
Application filed by 株式会社デンソー filed Critical 株式会社デンソー
Publication of WO2023054000A1 publication Critical patent/WO2023054000A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
    • B60T13/74—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with electrical assistance or drive
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D66/00—Arrangements for monitoring working conditions, e.g. wear, temperature
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D66/00—Arrangements for monitoring working conditions, e.g. wear, temperature
    • F16D66/02—Apparatus for indicating wear
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
    • G01L5/16—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring several components of force
    • G01L5/161—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring several components of force using variations in ohmic resistance
    • G01L5/1627—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring several components of force using variations in ohmic resistance of strain gauges
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
    • G01L5/22—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring the force applied to control members, e.g. control members of vehicles, triggers

Definitions

  • the present disclosure relates to a load sensor and an electric brake system including the load sensor.
  • a load sensor including a strain-generating body, two pressure-receiving projections projecting in the pressure-receiving direction from the strain-generating body, and strain sensors for measuring the stress received by each of the pressure-receiving projections, and an electric brake using the load sensor.
  • This electric brake consists of an electric motor that operates based on a control signal sent from an external controller, a linear motion mechanism that converts the rotary motion of the electric motor into linear motion of the piston, and a piston that moves linearly by driving force from the electric motor. , brake pads, discs, etc.
  • the external controller calculates the number of rotations of the electric motor based on the amount of operation of the operation pedal by the driver, and transmits a control signal corresponding to the calculated number of rotations to the electric motor to rotate the electric motor.
  • An electric brake uses an electric motor as a drive source to move a piston straight to press a brake pad against a disc, thereby generating the braking force necessary for the disc.
  • the upper surfaces of the two pressure-receiving protrusions of the load sensor are pressed against the linear motion mechanism when the brake pad is pressed against the disc.
  • the strain sensors arranged at positions corresponding to the two pressure receiving protrusions are deformed.
  • the load sensor detects the load when the brake pad presses the disc based on the strain amounts of the two strain sensors, and transmits a detection signal corresponding to the detected load to an external controller.
  • An external controller performs feedback control of the electric brake based on the detection signal transmitted from the load sensor.
  • the load with which the brake pad presses the disc includes not only the load in the direction in which the piston moves straight, but also the load in the direction other than the direction in which the piston moves straight.
  • the load with which the brake pad presses the disc differs depending on whether the brake pad is unevenly worn or not. That is, even if the electric motor is rotated at a predetermined number of revolutions, the braking force of the electric brake changes depending on whether the brake pads are unevenly worn or not.
  • the method of obtaining the unbalanced load by averaging the strain amount of each of the two strain sensors accurately detects the unbalanced load applied to the load sensor. found it difficult to do.
  • the load sensor described in Patent Document 1 when an uneven load is applied to the upper surface of the pressure receiving projection that receives the load, there is a possibility that the load component in the direction orthogonal to the surface that receives the load cannot be detected with high accuracy. It turns out there is. Therefore, even if the load sensor described in Patent Document 1 is used in an electric brake system, it is difficult to accurately detect the load in the direction in which the piston moves straight. If the load in the direction in which the piston moves straight cannot be detected with high accuracy, it is difficult to adjust the braking force of the electric brake according to the load when the brake pad presses the disc.
  • An object of the present disclosure is to provide a load sensor capable of accurately detecting a load in a direction perpendicular to the load receiving surface when an unbalanced load is applied to the load receiving surface, and an electric brake system including the load sensor. do.
  • a load sensor that detects a load, a housing having a load surface that receives a load, the load surface being deformed by receiving the load;
  • a direction along the load surface is defined as a first direction and a direction along the load surface and a direction intersecting the first direction is defined as a second direction
  • the A strain detection unit that detects at least one of a first strain amount that is a strain amount of a plurality of parts in a first direction and a second strain amount that is a strain amount of a plurality of parts in a second direction in the housing.
  • a load sensor that detects a load, a housing having a load surface that receives a load, the load surface being deformed by receiving the load;
  • a direction along the load surface is defined as a first direction and a direction along the load surface and a direction intersecting the first direction is defined as a second direction
  • the a strain detection unit that detects a first strain amount that is the strain amount of the plurality of parts in the first direction and a second strain amount that is the strain amount of the plurality of parts in the second direction in the housing; Based on the first strain amount of the plurality of parts and the second strain amount of the plurality of parts detected by the strain detection unit, among the loads applied to the load surface, a surface orthogonal load applied in a third direction intersecting the load surface is obtained. and a load calculation unit.
  • the load sensor detects, of the first strain amount of the plurality of parts and the second strain amount of the plurality of parts detected by the strain detection unit, Based on at least one of the strain amounts, it is possible to accurately detect the plane-perpendicular load perpendicular to the load plane.
  • a load sensor as described in one aspect or another aspect of this disclosure; brake pedal and a brake rotor; a friction material that generates a braking force on the brake rotor; a piston that presses the friction material against the brake rotor; an electric motor that outputs rotational force; It has a rotation shaft that rotates around the rotation axis by the rotation force output by the electric motor, and converts the rotation force output by the electric motor, and the piston directs the friction material in the axial direction of the rotation shaft center to brake.
  • a motion conversion mechanism that outputs a driving force for pressing the rotor; a control device that determines a target brake load, which is a target load when the friction material presses the brake rotor, based on the degree of opening of the brake pedal, and controls the rotation speed of the electric motor based on the determined target brake load; , and
  • the load sensor is attached to the motion conversion mechanism so that the third direction is along the axial direction, and detects the reaction force generated in the motion conversion mechanism when the piston presses the friction material due to the driving force of the motion conversion mechanism.
  • the control device is an electric brake system that controls the rotation speed of the electric motor so that the perpendicular load obtained by the load sensor approaches the target brake load.
  • the load sensor detects the direction along the third direction in the brake load. It is possible to detect the perpendicular load, which is the reaction force of
  • the electric motor is controlled using the perpendicular load detected by the load sensor so that the brake load can be adjusted to the target brake load. load can be approached.
  • FIG. 1 is a schematic configuration diagram of an electric brake system according to a first embodiment
  • FIG. 4 is a cross-sectional view of the caliper according to the first embodiment
  • FIG. 2 is a top view of the load sensor according to the first embodiment
  • FIG. FIG. 4 is a sectional view along IV-IV in FIG. 3
  • 3 is a schematic configuration diagram of a load calculation unit according to the first embodiment
  • FIG. 1 is a system block diagram of an electric brake system according to a first embodiment
  • FIG. It is a figure which shows the state by which the unbalanced load was provided to the load sensor which concerns on 1st Embodiment.
  • FIG. 4 is a diagram showing radial loads in experiments in which an unbalanced load is applied to the load sensor according to the first embodiment
  • FIG. 10 is a diagram showing a perpendicular direction load in an experiment in which an unbalanced load is applied to the load sensor according to the first embodiment
  • FIG. 4 is a diagram showing axial loads in experiments in which an unbalanced load is applied to the load sensor according to the first embodiment
  • FIG. 4 is a diagram corresponding to FIG. 3 relating to a comparative load sensor
  • FIG. 10 is a diagram showing a radial load in an experiment in which an unbalanced load is applied to a comparative load sensor
  • FIG. 10 is a diagram showing a perpendicular load in an experiment in which an unbalanced load is applied to a comparative load sensor
  • FIG. 10 is a diagram showing a perpendicular load in an experiment in which an unbalanced load is applied to a comparative load sensor
  • FIG. 5 is a diagram showing axial loads in an experiment in which an unbalanced load is applied to a comparative load sensor;
  • FIG. 5 is a first diagram showing load vectors in an experiment in which an unbalanced load was applied to the load sensor according to the first embodiment;
  • FIG. 7 is a second diagram showing load vectors in an experiment in which an unbalanced load was applied to the load sensor according to the first embodiment;
  • FIG. 9 is a third diagram showing load vectors in an experiment in which an unbalanced load was applied to the load sensor according to the first embodiment;
  • FIG. 11 is a fourth diagram showing load vectors in an experiment in which an unbalanced load was applied to the load sensor according to the first embodiment;
  • FIG. 5 is a first diagram showing load vectors in an experiment in which an unbalanced load was applied to the load sensor according to the first embodiment;
  • FIG. 7 is a second diagram showing load vectors in an experiment in which an unbalanced load was applied to the load sensor according to the first embodiment;
  • FIG. 11 is a fifth diagram showing load vectors in an experiment in which an unbalanced load was applied to the load sensor according to the first embodiment;
  • FIG. 11 is a sixth diagram showing load vectors in an experiment in which an unbalanced load was applied to the load sensor according to the first embodiment; It is a figure which shows the relationship between the axial direction load which the load sensor which concerns on 1st Embodiment detects, and the rotation speed of an electric motor.
  • FIG. 5 is a diagram showing the magnitude of load when the friction material according to the first embodiment is not worn;
  • FIG. 4 is a diagram showing the magnitude of load when the friction material according to the first embodiment is unevenly worn.
  • FIG. 5 is a diagram showing a control flow when the control device according to the first embodiment performs feedback control;
  • FIG. 5 is a diagram showing magnitudes of loads that change according to the state of the friction material according to the first embodiment;
  • FIG. 5 is a diagram showing the motor rotation speed and the load divergence amount that change according to the amount of wear of the friction material according to the first embodiment;
  • FIG. 5 is a diagram showing the relationship between the wear amount of the friction material and the load divergence amount according to the first embodiment; It is a figure which shows the relationship between the target rotation speed and the load divergence amount which concern on 1st Embodiment.
  • FIG. 5 is a diagram showing a load divergence amount that changes according to the inclination of the friction material according to the first embodiment;
  • FIG. 5 is a diagram showing a load divergence amount that changes according to a loss range of the friction material according to the first embodiment;
  • FIG. 5 is a diagram showing a control flow when the control device according to the first embodiment detects the wear amount and wear state of the friction material;
  • FIG. 5 is a cross-sectional view of a load sensor according to a second embodiment; It is a figure which shows the state which the load sensor which concerns on 2nd Embodiment received load.
  • FIG. 1 A first embodiment will be described with reference to FIGS. 1 to 31.
  • FIG. 1 This disclosure describes an embodiment in which the load sensor 70 is applied to the electric brake system 1 shown in FIGS. 1 and 2 .
  • the electric brake system 1 of this embodiment includes a brake pedal P, a disk-shaped brake rotor R that rotates integrally with a wheel (not shown), and a and a control device 80.
  • the load sensor 70 of the present embodiment is provided in the caliper 10, and the first and second brake pads 40 and 50, which will be described later, move to the brake rotor R as the rotating shaft 631, which will be described later, rotates about the rotation axis SC. Detects the load when the is pressed.
  • the plate thickness direction of the brake rotor R is referred to as a brake axial direction DRb.
  • a direction toward one side of the brake shaft direction DRb is also called a first brake direction DRb1
  • a direction toward the other side of the brake shaft direction DRb is also called a second brake direction DRb2.
  • the brake axial direction DRb corresponds to the axial direction.
  • the caliper 10 includes a housing 20, a piston 30 supported by the housing 20, a pair of brake pads 40 and 50, and a moving mechanism 60 that moves the piston 30.
  • the housing 20 is a case portion that accommodates various components of the caliper 10 . As shown in FIG. 2, the housing 20 has a first housing 21 provided on the first braking direction DRb1 side, and a second housing 22 and a cover portion 23 provided on the second braking direction DRb2 side.
  • the first housing 21 has a connecting portion 211 connected to the second housing 22 and a claw portion 212 provided at the end portion in the first braking direction DRb1.
  • the connection portion 211 is formed extending along the brake axial direction DRb.
  • a claw portion 212 is provided at the end portion of the connecting portion 211 in the first braking direction DRb1.
  • the second housing 22 is fixed to the end of the connecting portion 211 in the second braking direction DRb2.
  • the claw portion 212 extends in a direction perpendicular to the direction in which the connection portion 211 extends. Further, the claw portion 212 is arranged at a position facing the surface of the brake rotor R on the first braking direction DRb1 side. The claw portion 212 is arranged with a space from the brake rotor R on the first braking direction DRb1 side of the brake rotor R. As shown in FIG. Of the pair of brake pads 40 and 50, the first brake pad 40 provided on the side of the first braking direction DRb1 is fixed to the claw portion 212. As shown in FIG.
  • the second housing 22 includes a cylinder 221 fixed to the connecting portion 211 of the first housing 21 and an extension plate 222 extending from the cylinder 221 .
  • the cylinder 221 accommodates the piston 30, and the rotating shaft 631 of the moving mechanism 60 is inserted therethrough.
  • the cylinder 221 is formed in a bottomed shape that is open on the first braking direction DRb1 side and closed on the second braking direction DRb2 side.
  • the cylinder 221 has a cylindrical cylinder portion 221a extending along the brake axial direction DRb and a cylinder bottom portion 221b connected to the second brake direction DRb2 side of the cylinder portion 221a.
  • the cylinder tube portion 221 a has a central axis, and is arranged so that the central axis overlaps with the rotation axis SC of the rotation shaft 631 . That is, the cylinder 221 has a bottomed cylindrical shape centered on the rotation axis SC. Further, the cylinder tubular portion 221a is arranged with an end portion in the first braking direction DRb1 spaced from the brake rotor R. As shown in FIG.
  • the cylinder tube portion 221a is fitted with the piston 30 from the opening side in the first brake direction DRb1, and the opening side is closed by the piston 30. Further, a key groove 221c for fitting a key 31e of the piston 30, which will be described later, of the piston 30, and an O-shaped groove provided between the inner peripheral portion of the cylinder tubular portion 221a and the outer peripheral portion of the piston 30. A housing groove 221d for housing the ring 223 is formed.
  • the keyway 221c extends along the brake axial direction DRb.
  • the size of the key groove 221c in the brake axial direction DRb is formed larger than the size of the key 31e in the brake axial direction DRb.
  • An O-ring 223 is arranged as a sealing member in the accommodation groove 221d.
  • the second braking direction DRb2 side of the cylinder tubular portion 221a is closed by the cylinder bottom portion 221b.
  • a through hole 221e is formed in the center of the cylinder bottom portion 221b so as to penetrate in the brake axial direction DRb.
  • the through hole 221e is provided with a rolling bearing 224 that supports the rotating shaft 631 rotatably and immovably in the brake shaft direction DRb.
  • a rotating shaft 631 supported by the rolling bearing 224 is inserted through the through hole 221e.
  • the extension plate 222 is a portion of the moving mechanism 60 to which an electric motor 61, which will be described later, is attached.
  • the extension plate 222 is connected to the cylinder bottom portion 221b.
  • the cover part 23 is a housing part that houses a later-described deceleration mechanism 62 of the moving mechanism 60 .
  • the cover portion 23 is provided at the end portion of the second housing 22 on the second braking direction DRb2 side.
  • the piston 30 presses the second brake pad 50 provided on the second braking direction DRb2 side in the first braking direction DRb1.
  • the piston 30 is arranged at a position facing the surface of the brake rotor R on the second braking direction DRb2 side via the second brake pad 50 .
  • the piston 30 is formed in a bottomed shape that is open on the second braking direction DRb2 side and closed on the first braking direction DRb1 side.
  • the piston 30 has a cylindrical piston cylinder portion 31 extending along the brake axial direction DRb and a piston bottom portion 32 connected to the first brake direction DRb1 side of the piston cylinder portion 31 .
  • the piston 30 is arranged so as to be accommodated in the cylinder tube portion 221 a at a position where its central axis is coaxial with the rotation axis SC of the rotation shaft 631 and the central axis of the cylinder 221 . That is, the piston 30 has a bottomed cylindrical shape centered on the rotation axis SC.
  • the piston cylindrical portion 31 is composed of a small-diameter portion 31b, a medium-diameter portion 31c, and a large-diameter portion 31d having different inner diameters.
  • the piston cylindrical portion 31 has a small-diameter portion 31b, a medium-diameter portion 31c having an inner diameter larger than that of the small-diameter portion 31b, and a large-diameter portion 31d having an inner diameter larger than that of the medium-diameter portion 31c. They are connected in this order along the direction DRb2.
  • the small diameter portion 31b, medium diameter portion 31c, and large diameter portion 31d are integrally formed.
  • the outer diameters of the small-diameter portion 31b, medium-diameter portion 31c, and large-diameter portion 31d are formed substantially equal to the inner diameter of the cylindrical cylinder portion 221a.
  • the piston cylindrical portion 31 has an internal space 31a, and a part of the rotating shaft 631 and a nut member 632, which will be described later, are arranged in the internal space 31a.
  • the nut member 632 is fixed to the surface of the small diameter portion 31b on the second brake direction DRb2 side.
  • a key 31 e that fits into the key groove 221 c of the cylinder 221 is formed on the outer peripheral portion of the piston cylindrical portion 31 .
  • the key 31 e of the piston 30 is fitted into the key groove 221 c of the cylinder 221 .
  • the piston 30 is configured to be non-rotatable in the circumferential direction of the rotation axis SC.
  • the first braking direction DRb1 side of the piston cylindrical portion 31 is closed by the piston bottom portion 32 .
  • the piston bottom 32 protrudes from the end of the cylinder 221 in the first braking direction DRb1 toward the first braking direction DRb1.
  • a second brake pad 50 is fixed to the surface of the piston bottom portion 32 on the side of the first braking direction DRb1.
  • the first brake pad 40 includes a first friction material 41 facing the brake rotor R, and a first back plate 42 arranged on the surface of the first friction material 41 opposite to the surface facing the brake rotor R. have.
  • the second brake pad 50 comprises a second friction material 51 facing the brake rotor R, and a second back plate 52 arranged on the surface of the second friction material 51 opposite to the surface facing the brake rotor R. have.
  • the first friction material 41 and the second friction material 51 are members that generate braking force by friction generated when they come into contact with the brake rotor R. As shown in FIG.
  • the first friction material 41 and the first back plate 42 are superimposed on each other in the brake axial direction DRb and fixed to each other.
  • the first friction material 41 has a first friction surface 411 that generates a braking force by coming into contact with the brake rotor R.
  • the second friction material 51 and the second back plate 52 are also overlapped and fixed to each other in the brake axial direction DRb.
  • the second friction material 51 has a second friction surface 511 that abuts against the brake rotor R to generate a braking force.
  • the moving mechanism 60 outputs a driving force for moving the piston 30 when the driver performs a braking operation.
  • the movement mechanism 60 includes an electric motor 61 , a reduction mechanism 62 and a motion conversion mechanism 63 .
  • the electric motor 61 is attached to the extension plate 222 .
  • the electric motor 61 is a drive generator that generates a rotational force for rotating the rotary shaft 631 of the motion converting mechanism 63 when energized.
  • the number of revolutions of the electric motor 61 is controlled by a control signal transmitted from the control device 80 .
  • the electric motor 61 is connected to a speed reduction mechanism 62 .
  • the deceleration mechanism 62 is a deceleration unit that decelerates the rotation speed of the electric motor 61 .
  • the speed reduction mechanism 62 is housed in the cover portion 23 .
  • the deceleration mechanism 62 has a plurality of gears, decelerates the rotational force generated by the electric motor 61 , and transmits it to the motion conversion mechanism 63 .
  • the motion conversion mechanism 63 has a rotating shaft 631 rotated by the torque generated by the electric motor 61, a nut member 632 attached to the rotating shaft 631, and a thrust bearing 633.
  • a load sensor 70 is attached to the motion conversion mechanism 63 as described later.
  • the motion conversion mechanism 63 is a conversion mechanism that converts the rotary motion of the electric motor 61 transmitted via the speed reduction mechanism 62 into the linear motion of the nut member 632 .
  • the rotation shaft 631 is connected to the speed reduction mechanism 62 inside the cover portion 23 at the end on the second braking direction DRb2 side. Further, the rotating shaft 631 is supported by the housing 20 so as to be immovable in the brake shaft direction DRb while being supported by the rolling bearing 224 and rotatable about the rotation axis SC. The rotary shaft 631 is housed in the internal space 31a of the cylinder tubular portion 221a on the first braking direction DRb1 side.
  • the rotating shaft 631 is processed with a male thread for connecting a nut member 632 to a portion of the outer peripheral portion that is accommodated in the internal space 31a of the piston 30 .
  • a disk-shaped collar portion 631a is provided on the outer peripheral portion of the rotating shaft 631 on the second braking direction DRb2 side of the male threaded portion.
  • the flange portion 631a extends in a disc shape from the outer peripheral portion of the rotating shaft 631 along the radial direction of the rotating shaft 631 in a direction away from the rotation axis SC.
  • a thrust bearing 633 and a load sensor 70 are arranged along the second braking direction DRb2 between the surface of the collar portion 631a on the second braking direction DRb2 side and the surface of the cylinder bottom portion 221b on the first braking direction DRb1 side. are arranged in order. That is, the load sensor 70 is sandwiched between the thrust bearing 633 and the cylinder bottom portion 221b. Thrust bearing 633 and load sensor 70 are arranged in this order along first braking direction DRb1 between the surface of collar portion 631a on the second braking direction DRb2 side and the surface of cylinder bottom portion 221b on the first braking direction DRb1 side. may be placed in between.
  • the thrust bearing 633 is arranged so that the rotary shaft 631 penetrates it.
  • the thrust bearing 633 is configured by, for example, a thrust needle bearing.
  • the thrust bearing 633 supports the load applied to the rotating shaft 631 in the brake axial direction DRb.
  • the thrust bearing 633 may be composed of a thrust roller bearing or a thrust ball bearing.
  • the nut member 632 is a linear motion member that performs linear motion by rotating the rotating shaft 631 .
  • the nut member 632 is formed in a hollow cylindrical shape with both sides opened in the brake shaft direction DRb.
  • the nut member 632 is accommodated in the inner space 31a of the piston 30.
  • the nut member 632 is non-rotatably supported by the piston 30 about the rotation axis SC.
  • a surface of the nut member 632 on the first braking direction DRb1 side is fixed to a surface of the small diameter portion 31b of the piston cylinder portion 31 on the second braking direction DRb2 side.
  • a flange portion 632 a is provided on the outer peripheral portion of the nut member 632 .
  • the outer peripheral portion of the flange portion 632 a contacts the inner peripheral portion of the large diameter portion 31 d of the piston cylinder portion 31 .
  • the inner peripheral portion of the nut member 632 is internally threaded corresponding to the external thread of the rotating shaft 631 .
  • the female thread of the nut member 632 and the male thread of the rotating shaft 631 are engaged to connect the nut member 632, and the rotation of the rotating shaft 631 enables straight movement in one side and the other side of the brake shaft direction DRb. It is configured.
  • the nut member 632 advances straight in the first braking direction DRb1 when the rotating shaft 631 rotates in one circumferential direction around the rotation axis SC, and the rotating shaft 631 rotates in the other circumferential direction. Then, it is configured to be able to go straight in the second braking direction DRb2.
  • the rotation direction of the rotation shaft 631 for causing the nut member 632 to advance straight in the first braking direction DRb1 is referred to as the normal rotation direction
  • the rotation direction of the rotation shaft 631 for causing the nut member 632 to advance straight in the second braking direction DRb2. is called the reverse direction.
  • the nut member 632 configured in this way moves straight in the first braking direction DRb1 to move the piston 30 in the first braking direction DRb1 when the rotating shaft 631 rotates in the normal direction.
  • the amount of movement of the piston 30 in the brake axial direction DRb varies depending on the rotation speed of the rotary shaft 631 , that is, the rotation speed of the electric motor 61 .
  • the position of the piston 30 when the piston 30 moves straight in the first brake direction DRb1 is determined by the rotation speed of the electric motor 61 .
  • the rotary shaft 631 moves the first housing 21 in the second braking direction DRb2.
  • the first friction surface 411 of the first friction material 41 attached to the first brake pad 40 is pressed against the brake rotor R by the claw portion 212 .
  • the motion conversion mechanism 63 converts the rotational force output by the electric motor 61 into a rectilinear force that causes the piston 30 to move straight. Then, the motion conversion mechanism 63 outputs a driving force for pressing the second friction member 51 against the brake rotor R in the brake axial direction DRb. As a result, the first friction material 41 and the second friction material 51 cause the brake rotor R to generate a braking force.
  • the rotating shaft 631 is given a reaction force against the force of the second brake pad 50 pressing the brake rotor R via the piston 30 and the nut member 632 . Furthermore, a reaction force against the force of the first brake pad 40 pressing the brake rotor R is also applied to the rotating shaft 631 via the first housing 21 . These reaction forces are applied to the rotating shaft 631 in the direction opposite to the direction in which the piston 30 moves straight, that is, in the second brake direction DRb2.
  • the reaction force against the force of the second brake pad 50 applied to the rotary shaft 631 to press the brake rotor R and the reaction force against the force of the first brake pad 40 to press the brake rotor R are transmitted to the thrust bearing 633.
  • brake load the force with which the first brake pad 40 and the second brake pad 50 press the brake rotor R
  • brake reaction force against the brake load will also be referred to as brake reaction force.
  • the load sensor 70 is a sensor that detects brake reaction force. Brake reaction force is transmitted to the load sensor 70 from the rotating shaft 631 via the thrust bearing 633 . Load sensor 70 outputs a detection signal relating to the brake reaction force applied to load sensor 70 to control device 80 . Details of the load sensor 70 will be described later.
  • the control device 80 is composed of a CPU, a microcomputer including storage units such as ROM and RAM, and its peripheral circuits.
  • the control device 80 has an input side connected to a stroke sensor and a load sensor 70 (not shown), and an output side connected to the electric motor 61 .
  • the stroke sensor detects the pedal opening amount when the brake pedal P is operated by the driver.
  • the control device 80 detects the pedal opening amount when the driver operates the brake pedal P based on the detection signal transmitted from the stroke sensor, and adjusts the rotation speed of the electric motor 61 based on the pedal opening amount. control. Further, the control device 80 receives a detection signal relating to the brake reaction force from the load sensor 70, and performs feedback control of the electric motor 61 based on the detection signal.
  • control device 80 detects the amount of wear of the first friction material 41 and the second friction material 51 and the states of the first friction surface 411 and the second friction surface 511 based on the detection signal from the load sensor 70. configured as possible. Details of the operation of the control device 80 will be described later.
  • the storage units such as ROM and RAM of the control device 80 are composed of non-transitional physical storage media.
  • the load sensor 70 detects the housing 71 that is deformed by the reaction force transmitted through the thrust bearing 633 and the amount of strain when the housing 71 is deformed, and detects the load applied to the load sensor 70 based on the amount of strain. It has a load calculation unit 72 for obtaining .
  • the housing 71 has an annular shape with a central axis CL extending along the brake axial direction DRb, and has a through hole 73 formed along the central axis CL. ing.
  • the housing 71 is arranged so that its central axis CL is coaxial with the rotational axis SC of the rotating shaft 631 and the central axis of the piston 30 , and the rotating shaft 631 is inserted through the through hole 73 .
  • the housing 71 has a hollow shape with a space S inside, and has an outer wall portion 711 surrounding the space S.
  • the outer wall portion 711 has an inner peripheral portion 712 facing the central axis CL, and an outer peripheral portion 713 surrounding the space S outside the inner peripheral portion 712 in the radial direction of the central axis CL.
  • the outer wall portion 711 has a load receiving portion 714 that is continuous with the inner peripheral portion 712 and the outer peripheral portion 713 on the first brake direction DRb1 side and faces the thrust bearing 633 .
  • the outer wall portion 711 has a sensor bottom portion 715 that is continuous with the inner peripheral portion 712 and the outer peripheral portion 713 on the second brake direction DRb2 side and faces the cylinder bottom portion 221b.
  • the space S is surrounded by the inner peripheral portion 712 , the outer peripheral portion 713 , the load receiving portion 714 , and the sensor bottom portion 715 .
  • the inner peripheral portion 712, the outer peripheral portion 713, the load receiving portion 714, and the sensor bottom portion 715 are integrally formed.
  • the load receiving portion 714 has a load surface 714 a that extends planarly along the radial direction of the central axis CL and contacts the thrust bearing 633 .
  • the load surface 714a is formed by a plane perpendicular to the central axis CL.
  • the load surface 714a is a surface that receives the load transmitted from the thrust bearing 633, that is, the brake reaction force.
  • the direction in which the central axis CL of the load sensor 70 extends is the load axial direction DRz
  • the radial direction of the central axis CL of the load sensor 70 is the load radial direction DRx
  • a direction orthogonal to the radial direction DRx is also called a load orthogonal direction DRy.
  • the load axial direction DRz is a direction that coincides with the brake axial direction DRb and intersects the load surface 714a.
  • the load axis direction DRz is substantially orthogonal to the load surface 714a.
  • the load sensor 70 is arranged such that the load axial direction DRz is along the brake axial direction DRb.
  • the load radial direction DRx is a direction that coincides with the radial direction of the rotation axis SC.
  • the load axis direction DRz is substantially orthogonal to the load surface 714a does not mean that the load axis direction DRz is orthogonal to the load surface 714a. It also includes a state of deviation.
  • a load radial direction DRx corresponds to the first direction
  • a load orthogonal direction DRy corresponds to the second direction
  • a load axial direction DRz corresponds to the third direction.
  • the inner peripheral portion 712 and the outer peripheral portion 713 are annular.
  • the inner diameter of the inner peripheral portion 712 is smaller than the inner diameter of the outer peripheral portion 713 .
  • the outer surface of the inner peripheral portion 712 in the load radial direction DRx is surrounded by the inner surface of the outer peripheral portion 713 in the load radial direction DRx.
  • the inner peripheral portion 712 and the outer peripheral portion 713 are formed to have the same size in the load radial direction DRx. That is, the outer peripheral portion 713 and the inner peripheral portion 712 have the same thickness.
  • the load receiving portion 714 and the sensor bottom portion 715 have an annular flat plate shape and extend in a plane along the load radial direction DRx.
  • the load receiving portion 714 and the sensor bottom portion 715 are formed to have the same outer diameter as the outer diameter of the outer peripheral portion 713, and are opposed to each other in the load axial direction DRz. That is, the load receiving portion 714 and the sensor bottom portion 715 overlap each other in the load axis direction DRz.
  • the sensor bottom portion 715 has a diaphragm portion 715a that is recessed toward the space S side, and has a support portion 715b around the diaphragm portion 715a.
  • the diaphragm portion 715a is a portion in which a Wheatstone bridge circuit 721, which will be described later, is provided, and is formed over the entire area of the sensor bottom portion 715 along the circumferential direction of the central axis CL at substantially the center of the sensor bottom portion 715 in the load radial direction DRx.
  • the size of the diaphragm portion 715a in the load axis direction DRz is smaller than the size of the support portion 715b in the load axis direction DRz.
  • the size of the diaphragm portion 715a in the load axis direction DRz is set to be half or less of the size of the support portion 715b in the load axis direction DRz.
  • the supporting portion 715b is formed to have substantially the same size in the load axial direction DRz as the load receiving portion 714 in the load axial direction DRz.
  • the diaphragm part 715a has a thin-film annular shape having a film thickness direction in the load axis direction DRz, and has a mounting surface 715c on the side surrounding the space S.
  • the mounting surface 715c is formed by a plane that intersects the load axis direction DRz. That is, the mounting surface 715c is formed of a plane substantially orthogonal to the load axial direction DRz and extending in the load radial direction DRx and the load orthogonal direction DRy.
  • the mounting surface 715c extending in the load radial direction DRx and the load orthogonal direction DRy does not mean that the mounting surface 715c is strictly parallel to the load radial direction DRx and the load orthogonal direction DRy.
  • the mounting surface 715c extending in the load radial direction DRx and the load orthogonal direction DRy may be slightly displaced from the load radial direction DRx and the load orthogonal direction DRy due to manufacturing errors or the like.
  • the diaphragm portion 715a is formed to be smaller in size in the load axis direction DRz than the load receiving portion 714 and the support portion 715b. Therefore, when the housing 71 deforms due to the load surface 714a receiving a brake reaction force, the diaphragm portion 715a deforms more easily than the load receiving portion 714 and the support portion 715b. In other words, the diaphragm portion 715a is less rigid than the load receiving portion 714 and the support portion 715b.
  • the diaphragm portion 715a of the present embodiment is formed over the entire area of the sensor bottom portion 715 along the circumferential direction of the central axis CL in the sensor bottom portion 715 overlapping the load surface 714a in the load axial direction DRz. Therefore, even if the brake reaction force applied to the load surface 714a is biased with respect to the load surface 714a, the diaphragm portion 715a is likely to deform according to the bias.
  • the diaphragm portion 715a corresponds to the low-rigidity portion.
  • a load calculator 72 is provided in the space S of the housing 71 .
  • the load calculator 72 has three Wheatstone bridge circuits 721 and a load calculator 722, as shown in FIG.
  • the three Wheatstone bridge circuits 721 are connected in parallel to the load calculator 722 . Since the three Wheatstone bridge circuits 721 have the same configuration, only one Wheatstone bridge circuit 721 out of the three Wheatstone bridge circuits 721 will be described below.
  • the Wheatstone bridge circuit 721 has a first strain sensor 721a that detects strain along the load radial direction DRx and a second strain sensor 721b that detects strain along the load orthogonal direction DRy. Furthermore, the Wheatstone bridge circuit 721 has a first resistance portion 721c and a second resistance portion 721d with fixed electrical resistance values.
  • the Wheatstone bridge circuit 721 includes a power supply section VCC and a ground section GND to which a power supply (not shown) is connected.
  • the Wheatstone bridge circuit 721 includes a series circuit having a first strain sensor 721a and a first resistance section 721c and a series circuit having a second strain sensor 721b and a second resistance section 721d between a power supply section VCC and a ground section GND. circuit.
  • a voltage of 5 V is applied to the Wheatstone bridge circuit 721, for example, from the power supply unit VCC.
  • the Wheatstone bridge circuits 721 are arranged on a substrate (not shown) and are fixed to the mounting surface 715c at equal intervals along the circumferential direction of the central axis CL as shown in FIGS. Specifically, substrates (not shown) on which the Wheatstone bridge circuits 721 are arranged are fixed to the mounting surface 715c at intervals of 120° along the circumferential direction of the central axis CL using a bonding member such as an adhesive. .
  • the Wheatstone bridge circuit 721 corresponds to the distortion detector.
  • the first strain sensor 721a and the second strain sensor 721b are composed of elements that detect changes in the amount of strain in the detection direction as changes in electrical resistance.
  • the first strain sensor 721a and the second strain sensor 721b of the present embodiment are composed of semiconductor strain gauges, for example. It should be noted that the first strain sensor 721a and the second strain sensor 721b are not limited to specific types of strain gauges, and may be composed of strain gauges different from semiconductor strain gauges, such as foil strain gauges and wire strain gauges.
  • the first strain sensor 721a and the second strain sensor 721b measure the amount of strain when the diaphragm portion 715a deforms due to the brake reaction force being applied to the load surface 714a and the diaphragm portion 715a and the diaphragm portion 715a deform integrally. Accordingly, the electrical resistance value of itself changes.
  • the first strain sensor 721a has its own electrical resistance value according to the strain amount in the load radial direction DRx on the mounting surface 715c when the diaphragm portion 715a is deformed in the direction including the load radial direction DRx by the brake reaction force. changes. That is, the amount of change in the electrical resistance value of the first strain sensor 721a reflects the amount of strain in the load radial direction DRx on the mounting surface 715c.
  • the second strain sensor 721b has its own electrical resistance depending on the amount of strain in the load orthogonal direction DRy on the mounting surface 715c when the diaphragm portion 715a is deformed in the direction including the load orthogonal direction DRy by the brake reaction force. value changes. That is, the amount of change in the electrical resistance value of the second strain sensor 721b reflects the amount of strain in the load orthogonal direction DRy on the mounting surface 715c.
  • the load calculation unit 722 detects the relative change in the electrical resistance values of the first strain sensor 721a and the second strain sensor 721b that change according to the amount of strain generated in the diaphragm portion 715a, thereby calculating the load applied to the load surface 714a. is calculated.
  • the load calculator 722 has a signal amplifier (not shown) and a calculator (not shown). The signal amplifier and the arithmetic unit are provided on a substrate (not shown) different from the substrate on which the Wheatstone bridge circuit 721 is arranged, and are fixed to the surface of the support portion 715b on the space S side.
  • the signal amplifier is connected to a first intermediate portion 721e between the first strain sensor 721a and the first resistor portion 721c of each of the three Wheatstone bridge circuits 721, and a second intermediate portion 721e between the second strain sensor 721b and the second resistor portion 721d. 721f.
  • the signal amplifier then amplifies the voltage value between the first intermediate portion 721e and the second intermediate portion 721f, and outputs the amplified detection signal to the computing portion.
  • the calculation unit has, for example, a CPU and a storage unit including a ROM and a RAM, and the CPU reads a program stored in the ROM into the RAM and executes it.
  • the calculation unit obtains the brake reaction force applied to the load surface 714a based on the detection signal transmitted from the signal amplifier. Specifically, the calculation unit detects the load of the directional component along each of the load axial direction DRz, the load radial direction DRx, and the load orthogonal direction DRy. The details of how the load sensor 70 detects loads in directions along the load axial direction DRz, the load radial direction DRx, and the load orthogonal direction DRy will be described later. The calculation unit outputs information on the calculated brake reaction force to the control device 80 .
  • FIG. 6 As shown in FIG. 6, when the driver depresses the brake pedal P, information on the pedal opening amount detected by the stroke sensor is input to the control device 80 .
  • the control device 80 When the pedal opening amount information is input from the stroke sensor, the control device 80 causes the first brake pad 40 and the second brake pad 50 to press the brake rotor R based on the pedal opening amount and a predetermined control map. A target brake load Fi is calculated. Then, the control device 80 determines the target rotation speed Wi of the electric motor 61 based on the calculated target brake load Fi, and transmits to the electric motor 61 a control signal for rotating the electric motor 61 by the target rotation speed Wi. .
  • the electric motor 61 rotates the rotating shaft 631 in the forward direction based on a control signal transmitted from the control device 80 to move the piston 30 straight in the first braking direction DRb1, and rotates the first housing 21 to the second direction. It is moved in the braking direction DRb2.
  • the piston 30 moving in the first braking direction DRb1 presses the second friction material 51 against the brake rotor R by pressing the second brake pad 50 in the first braking direction DRb1.
  • the first housing 21 moving in the second braking direction DRb2 presses the first friction material 41 against the brake rotor R by pressing the first brake pad 40 in the second braking direction DRb2.
  • the load sensor 70 detects the brake reaction force generated on the rotary shaft 631 due to the brake load generated on the brake rotor R.
  • the load sensor 70 detects the brake reaction force based on the strain amount of the housing 71.
  • the brake reaction force generated on the rotating shaft 631 by the first friction material 41 and the second friction material 51 pressing against the brake rotor R may have a load component in a direction other than the brake axial direction DRb.
  • the first friction material 41 which is unevenly worn such that the first friction surface 411 is inclined with respect to the brake shaft direction DRb, is pressed against the brake rotor R will be described.
  • the load with which the first friction material 41 presses the brake rotor R is tilted with respect to the brake axial direction DRb according to the tilt of the first friction surface 411 .
  • the brake reaction force generated on the rotating shaft 631 by the first friction member 41 pressing against the brake rotor R has a load component in a direction other than the brake shaft direction DRb.
  • the second friction material 51 which is unevenly worn such that the second friction surface 511 is inclined with respect to the brake shaft direction DRb, is pressed against the brake rotor R.
  • the load with which the second friction material 51 presses the brake rotor R is tilted with respect to the brake axial direction DRb according to the tilt of the second friction surface 511 .
  • the brake reaction force generated on the rotating shaft 631 by the second friction material 51 pressing against the brake rotor R has a load component in a direction other than the brake shaft direction DRb.
  • the load applied to the load surface 714a of the load sensor 70 includes a component in a direction other than the load axial direction DRz.
  • Component loadings will be included. That is, in addition to the load in the load axial direction DRz, one or both of the load in the load radial direction DRx component and the load in the load orthogonal direction DRy is applied to the load surface 714a.
  • the load sensor 70 When a load is applied to the load surface 714a in a direction other than the load axial direction DRz, the load sensor 70 according to the present embodiment has directional components along the load axial direction DRz, the load radial direction DRx, and the load orthogonal direction DRy. can be detected individually. In other words, as shown in FIG. 7, even when an unbalanced load F that is inclined with respect to the load axial direction DRz is applied to the load surface 714a, the load sensor 70 detects the load axial direction DRz and the load radial direction DRx. , and the load orthogonal direction DRy can be individually detected.
  • the load sensor 70 When an unbalanced load F is applied to the load surface 714a in a direction including the load radial direction DRx and the load orthogonal direction DRy, the load sensor 70 is detected in directions along the load axial direction DRz, the load radial direction DRx, and the load orthogonal direction DRy. A specific operation when detecting a load will be described.
  • the first strain sensors 721a of the three Wheatstone bridge circuits 721 of the load sensor 70 correspond to the amount of strain in the load radial direction DRx of the mounting surface 715c. electrical resistance changes.
  • the electric resistance value of the second strain sensor 721b of each of the three Wheatstone bridge circuits 721 changes according to the amount of strain in the load orthogonal direction DRy of the mounting surface 715c.
  • the change in the electrical resistance value of the first strain sensor 721a increases as the amount of strain in the load radial direction DRx of the mounting surface 715c increases. That is, the change in the electrical resistance value of the first strain sensor 721a increases as the load in the load radial direction DRx among the brake reaction forces applied to the load sensor 70 increases. Further, even if the brake reaction force applied to the load sensor 70 is constant, the larger the inclination of the unbalanced load F in the load radial direction DRx with respect to the load axial direction DRz, the larger the load in the load radial direction DRx in the brake reaction force. Become.
  • the change in the electrical resistance value of the second strain sensor 721b increases as the amount of strain in the load orthogonal direction DRy of the mounting surface 715c increases. That is, the change in the electrical resistance value of the second strain sensor 721b increases as the load in the load orthogonal direction DRy among the brake reaction forces applied to the load sensor 70 increases. Further, even if the brake reaction force applied to the load sensor 70 is constant, the load in the load orthogonal direction DRy in the brake reaction force increases as the inclination of the unbalanced load F in the load orthogonal direction DRy with respect to the load axis direction DRz increases. Become.
  • the load calculator 722 detects the voltage value of the first intermediate portion 721e and the voltage value of the second intermediate portion 721f.
  • the signal amplifier in the load computing section 722 amplifies the voltage value of the first intermediate section 721e and the voltage value of the second intermediate section 721f of each of the three Wheatstone bridge circuits 721, and outputs the amplified detection signal to the computing section.
  • the calculation section of the load calculation section 722 calculates the strain amount of the mounting surface 715c of the portion where each of the three Wheatstone bridge circuits 721 is provided, based on the detection signal transmitted from the signal amplifier.
  • the calculation unit determines the amount of change in the voltage value of the first intermediate portions 721e that changes when the first strain sensor 721a is distorted.
  • the calculation unit calculates the amount of change in the voltage value of the second intermediate portions 721f that changes due to the strain of the second strain sensor 721b. do. Further, the calculation unit calculates the potential difference between the first intermediate portion 721e and the second intermediate portion 721f of each of the three Wheatstone bridge circuits 721.
  • the computing unit calculates 3 The distortion amounts of the three portions where the two Wheatstone bridge circuits 721 are provided are calculated.
  • the calculation unit calculates the amount of strain in the load radial direction DRx for each portion where the three first strain sensors 721a are provided and the three portions where the three second strain sensors 721b are provided.
  • the amount of strain in the load orthogonal direction DRy is calculated for each.
  • the calculation unit calculates the calculated distortion amount in the load radial direction DRx and the distortion amount in the load orthogonal direction DRy for each portion where the Wheatstone bridge circuit 721 is provided, and based on the predetermined Poisson's ratio of the housing 71, the three The amount of strain in the load axis direction DRz is calculated for each part.
  • the strain amount in the load axis direction DRz is calculated for each portion where the three Wheatstone bridge circuits 721 are provided.
  • the strain amount in the load radial direction DRx is also called a first strain amount
  • the strain amount in the load orthogonal direction DRy is also called a second strain amount
  • the strain amount in the load axial direction DRz is also called a third strain amount.
  • the calculation unit calculates the load radial direction DRx and the load orthogonal direction DRy of the braking reaction force applied to the entire load surface 714a. , and load-axis directions DRz. Then, the calculation unit outputs to the control device 80 the information of the load estimated value in each of the load radial direction DRx, the load orthogonal direction DRy, and the load axial direction DRz applied to the calculated load surface 714a.
  • the load estimated value along the load radial direction DRx calculated by the load sensor 70 is the radial load Fx
  • the load estimated value along the load orthogonal direction DRy is the orthogonal direction load Fy
  • the load estimated value along the load axial direction DRz is The load estimate is also called axial load Fz.
  • the load in the direction from the central axis CL toward the outer side of the load radial direction DRx will be described as a positive value
  • the load in the direction from the outer side of the load radial direction DRx toward the central axis CL will be described as a negative value.
  • the load in the direction toward one side of the load orthogonal direction DRy is assumed to be a positive value, and the load in the direction toward the other side is assumed to be a negative value.
  • the load in the direction opposite to the direction in which the load is applied to the load surface 714a is assumed to be a positive value, and the load in the direction in which the load is applied to the load surface 714a is assumed to be a negative value.
  • the radial load Fx corresponds to the first load
  • the orthogonal load Fy corresponds to the second load
  • the axial load Fz corresponds to the perpendicular load.
  • the inventor applied an unbalanced load F having various patterns of sizes to the load sensor 70 and changed the load direction of the unbalanced load F to change the diameter.
  • An experiment was conducted to detect a directional load Fx, a perpendicular load Fy, and an axial load Fz.
  • the magnitude of the unbalanced load F applied to the load surface 714a was set to various magnitudes
  • the angle of the unbalanced load F applied to the load surface 714a was set to various angles with respect to the load axial direction DRz.
  • a radial load Fx, an orthogonal load Fy, and an axial load Fz was set to various angles with respect to the load axial direction DRz.
  • FIG. 8 to 10 show calculation results of the radial load Fx, orthogonal load Fy, and axial load Fz of the load sensor 70 with respect to various set values of the unbalanced load F applied to the load sensor 70.
  • the vertical axis indicates the set value of the load applied to the load surface 714 a in the radial direction DRx
  • the horizontal axis indicates the radial load Fx calculated by the load sensor 70
  • the vertical axis indicates the set value of the load applied to the load surface 714 a in the load orthogonal direction DRy
  • the horizontal axis indicates the orthogonal direction load Fy calculated by the load sensor 70
  • the vertical axis indicates the set value of the load applied to the load surface 714a in the load axial direction DRz
  • the horizontal axis indicates the axial load Fz calculated by the load sensor .
  • the radial direction load Fx calculated by the load sensor 70 is the load surface 714a when the set value of the load in the load radial direction DRx is changed within the range of ⁇ 0.7 to +0.6 kN.
  • the load in the radial direction DRx substantially coincided with each set value.
  • the radial standard deviation ⁇ x the value obtained by multiplying the radial standard deviation ⁇ x by three is the radial deviation 3 ⁇ x
  • the deviation 3 ⁇ x was 0.01 kN.
  • the value of the radial deviation 3 ⁇ x was 1.4% of the maximum set value of the load in the load radial direction DRx, which was sufficiently small compared to the detection error of a general sensor.
  • the orthogonal direction load Fy calculated by the load sensor 70 is the load
  • the load in the load orthogonal direction DRy applied to the surface 714a substantially coincides with the set value of each load.
  • the orthogonal standard deviation ⁇ y the standard deviation of the error of the orthogonal direction load Fy with respect to the set value of the load in the load orthogonal direction DRy
  • the orthogonal direction deviation 3 ⁇ y the value obtained by multiplying the orthogonal standard deviation ⁇ y by three is defined as the orthogonal direction deviation 3 ⁇ y
  • the orthogonal direction deviation 3 ⁇ y was 0.014 kN.
  • the value of the orthogonal direction deviation 3 ⁇ y was 1.9% of the maximum set value of the load in the load orthogonal direction DRy, which was sufficiently small compared to the detection error of a general sensor.
  • the axial load Fz calculated by the load sensor 70 is applied to the load surface 714a when the set value of the load in the load axial direction DRz is changed within the range of -25 to -1 kN.
  • the applied load in the axial direction DRz substantially coincided with each set value.
  • the axial standard deviation of the error of the axial load Fz with respect to the set value of the load in the load axial direction DRz is defined as the axial standard deviation ⁇ z
  • the value obtained by multiplying the axial standard deviation ⁇ z by three is defined as the axial deviation 3 ⁇ z
  • the axial deviation 3 ⁇ z was 0.03 kN.
  • the value of the axial deviation 3 ⁇ z was 0.14% of the maximum set value of the load in the load axial direction DRz, which was sufficiently small compared to the detection error of a general sensor.
  • the comparison load sensor 90 differs from the load sensor 70 of this embodiment in the configuration of the Wheatstone bridge circuit 721 .
  • the comparison load sensor 90 has comparison Wheatstone bridge circuits 91 at intervals of 120° along the circumferential direction of the central axis CL.
  • the comparative Wheatstone bridge circuit 91 includes a strain sensor that detects strain along either one of the load radial direction DRx and the load orthogonal direction DRy, and three resistors with fixed electrical resistance values. there is That is, the comparative Wheatstone bridge circuit 91 has fewer strain sensors than the Wheatstone bridge circuit 721 of the load sensor 70 of the present embodiment. In the experiments shown in FIGS. 12 to 14, for example, the comparative Wheatstone bridge circuit 91 has the first strain sensor 721a but does not have the second strain sensor 721b. Other configurations are the same as those of the load sensor 70 of the present embodiment.
  • the radial load Fx and the orthogonal load Fy calculated by the load sensor 90 for comparison are equal to the radial load Fx and the orthogonal load Fy calculated by the load sensor 70 of the present embodiment.
  • the error of the calculated value with respect to the set value is large compared to Fy.
  • the value of the radial deviation 3 ⁇ x of the radial load Fx calculated by the comparative load sensor 90 was 0.20 kN, which was 29% of the maximum set value of the load in the load radial direction DRx.
  • the value of the orthogonal direction deviation 3 ⁇ y of the orthogonal direction load Fy detected by the comparative load sensor 90 was 0.23 kN, which was 33% of the maximum set value of the load in the load orthogonal direction DRy.
  • the value of the axial deviation 3 ⁇ z of the axial load Fz calculated by the comparative load sensor 90 was 0.06 kN, which was about 0.3% of the maximum set value of the load in the load axial direction DRz.
  • the variation in the errors in the radial load Fx, the orthogonal load Fy, and the axial load Fz calculated by the load sensor 90 for comparison is Fy and axial load Fz are larger than the variations in error.
  • the value of the radial deviation 3 ⁇ x of the radial load Fx and the value of the orthogonal direction deviation 3 ⁇ y of the orthogonal load Fy calculated by the load sensor 90 for comparison are the values of 3 ⁇ indicating the deviation of the detection error of a general sensor. It was a relatively large value by comparison.
  • the load sensor 70 of the present embodiment can improve the detection accuracy by providing the first strain sensor 721a and the second strain sensor 721b in the Wheatstone bridge circuit 721. .
  • the direction of the unbalanced load F applied to the load surface 714a was tilted by a first angle ⁇ in the load radial direction DRx with respect to the load axial direction DRz, and tilted by a second angle ⁇ .
  • the first angle ⁇ and the second angle ⁇ were set to different angles. 15 to 20, the load in the load radial direction DRx, the load orthogonal direction DRy, and the load axial direction DRz is set to different sizes.
  • solid lines indicate load vectors consisting of the load in the load radial direction DRx and the load in the load orthogonal direction DRy in the unbalanced load F applied in each of the six patterns. Further, in FIGS. 15 to 20, a load vector consisting of the load in the load orthogonal direction DRy and the load in the load axial direction DRz in the unbalanced load F, and a load vector consisting of the load in the load radial direction DRx and the load in the load axial direction DRz are shown. Shown with a solid line.
  • a load vector composed of the radial load Fx and the orthogonal load Fy, a load vector composed of the orthogonal load Fy and the axial load Fz, and a load vector composed of the radial load Fx and the axial load Fz of each of the six patterns. is indicated by a dashed line.
  • the magnitude of the load in the load radial direction DRx was set to -0.2 kN
  • the magnitude of the load in the load orthogonal direction DRy was set to 0.3 kN
  • the magnitude of the load in the load axial direction DRz was set to -13 kN. bottom.
  • the calculation results of the load sensor 70 are -0.08% for the radial load Fx, 0.5% for the orthogonal load Fy, and -0 for the axial load Fz. 0.01%.
  • a load vector composed of the radial load Fx and the orthogonal load Fy, a load vector composed of the orthogonal load Fy and the axial load Fz, and a load vector composed of the radial load Fx and the axial load Fz are each set to a set value almost matched. Further, the error of the combined load obtained by synthesizing the radial load Fx, orthogonal load Fy, and axial load Fz was 0.001 kN.
  • the load magnitude in the load radial direction DRx was set to 0.1 kN
  • the load magnitude in the load orthogonal direction DRy was set to 0.3 kN
  • the load magnitude in the load axial direction DRz was set to ⁇ 11 kN.
  • the calculation results of the load sensor 70 are as follows: the radial load Fx has an error of 0.24%; 07%. A load vector composed of the radial load Fx and the orthogonal load Fy, a load vector composed of the orthogonal load Fy and the axial load Fz, and a load vector composed of the radial load Fx and the axial load Fz are each set to a set value almost matched. Further, the error of the combined load obtained by synthesizing the radial load Fx, orthogonal load Fy, and axial load Fz was 0.014 kN.
  • the load magnitude in the load radial direction DRx was set to -0.5 kN
  • the load magnitude in the load orthogonal direction DRy was set to 0.45 kN
  • the load magnitude in the load axial direction DRz was set to -23 kN. bottom.
  • the calculation results of the load sensor 70 show an error of 0.09% for the radial load Fx, an error of 0.32% for the orthogonal load Fy, and an error of 0.02% for the axial load Fz. %Met.
  • a load vector composed of the radial load Fx and the orthogonal load Fy, a load vector composed of the orthogonal load Fy and the axial load Fz, and a load vector composed of the radial load Fx and the axial load Fz are each set to a set value almost matched.
  • the error of the combined load obtained by synthesizing the radial load Fx, orthogonal load Fy, and axial load Fz was 0.003 kN.
  • the magnitude of the load in the load radial direction DRx was set to 0.1 kN
  • the magnitude of the load in the load orthogonal direction DRy was set to -0.2 kN
  • the magnitude of the load in the load axial direction DRz was set to -20 kN. bottom.
  • the calculation results of the load sensor 70 show an error of 0.52% in the radial load Fx, an error of 0.5% in the orthogonal load Fy, and an error of 0.02 in the axial load Fz. %Met.
  • a load vector composed of the radial load Fx and the orthogonal load Fy, a load vector composed of the orthogonal load Fy and the axial load Fz, and a load vector composed of the radial load Fx and the axial load Fz are each set to a set value almost matched.
  • the error of the combined load obtained by synthesizing the radial load Fx, orthogonal load Fy, and axial load Fz was 0.005 kN.
  • the error in the angle calculated by the load sensor 70 with respect to the set value of the first angle ⁇ is 1.31°
  • the error calculated by the load sensor 70 with respect to the set value of the second angle ⁇ is 1.31°
  • the angular error was 0.0°.
  • the load magnitude in the load radial direction DRx was set to 0.3 kN
  • the load magnitude in the load orthogonal direction DRy was set to 0.25 kN
  • the load magnitude in the load axial direction DRz was set to ⁇ 21 kN.
  • the calculation results of the load sensor 70 are -0.11% for the radial load Fx, 0.88% for the orthogonal load Fy, and 0.88% for the axial load Fz. 08%.
  • a load vector composed of the radial load Fx and the orthogonal load Fy, a load vector composed of the orthogonal load Fy and the axial load Fz, and a load vector composed of the radial load Fx and the axial load Fz are each set to a set value almost matched.
  • the error of the combined load obtained by synthesizing the radial load Fx, orthogonal load Fy, and axial load Fz was 0.017 kN.
  • the load magnitude in the load radial direction DRx was set to -0.5 kN
  • the load magnitude in the load orthogonal direction DRy was set to 0.0 kN
  • the load magnitude in the load axial direction DRz was set to -15 kN. bottom.
  • the calculation results of the load sensor 70 are -0.05% for the radial load Fx, -0.06% for the orthogonal load Fy, and 0 for the axial load Fz. 0.08%.
  • a load vector composed of the radial load Fx and the orthogonal load Fy, a load vector composed of the orthogonal load Fy and the axial load Fz, and a load vector composed of the radial load Fx and the axial load Fz are each set to a set value almost matched. Further, the error of the combined load obtained by synthesizing the radial load Fx, orthogonal load Fy, and axial load Fz was 0.016 kN.
  • the error in the angle calculated by the load sensor 70 with respect to the set value of the first angle ⁇ is 0.05°
  • the error calculated by the load sensor 70 with respect to the set value of the second angle ⁇ is 0.05°.
  • the angular error was 0.0°.
  • the load sensor 70 outputs to the controller 80 a detection signal containing information on each of the radial load Fx, orthogonal load Fy, and axial load Fz thus calculated.
  • the control device 80 detects the axial load Fz based on the detection signal from the load sensor 70, and when the detected axial load Fz deviates from the target brake load Fi, the axial load Fz does not exceed the target brake load Fi. Feedback control of the electric motor 61 is performed so as to approach .
  • the control device 80 also detects the wear amount of the first and second friction members 41 and 51 and the state of the first and second friction surfaces 411 and 511 based on the detection signal from the load sensor 70 . Details of the operation of the control device 80 when performing feedback control and the operation of detecting the wear amount of the first and second friction materials 41 and 51 and the states of the first and second friction surfaces 411 and 511 will be described below. will be explained.
  • FIG. 21 The brake load for which the control device 80 performs feedback control increases as the rotation speed of the electric motor 61 increases. Therefore, each of the radial load Fx, the orthogonal load Fy, and the axial load Fz in the brake reaction force also increases as the rotation speed of the electric motor 61 increases.
  • the controller 80 determines the target rotation speed Wi of the electric motor 61 based on the target brake load Fi, and rotates the electric motor 61 by the target rotation speed Wi. to move the first housing 21 and the piston 30.
  • the load sensor 70 receives a reaction force generated when the first housing 21 is moved in the second braking direction DRb2 and a reaction force generated when the piston 30 is moved in the first braking direction DRb1.
  • the reaction force generated when moving the first housing 21 and the reaction force generated when moving the piston 30 have a constant magnitude until the first friction surface 411 and the second friction surface 511 come into contact with the brake rotor R. is. Therefore, the axial load Fz calculated by the load sensor 70 is constant until the first friction surface 411 and the second friction surface 511 come into contact with the brake rotor R, as shown in FIG.
  • the amount of change in the brake load generated by the first friction material 41 and the second friction material 51 is proportional to the amount of change in the rotation speed of the electric motor 61 . Therefore, the amount of change in the brake reaction force with respect to the brake load is also proportional to the amount of change in the rotational speed of the electric motor 61 . Therefore, the amount of change in the axial load Fz calculated by the load sensor 70 is, as shown in FIG. Proportional to the amount of change in rotation speed. Note that the horizontal axis shown in FIG. 21 indicates the rotation speed of the electric motor 61, and the vertical axis indicates the axial load Fz.
  • the electric motor The way in which the axial load Fz changes with respect to the change in the rotation speed of 61 is different. Moreover, even when the first friction surface 411 and the second friction surface 511 are not missing and when the first friction surface 411 and the second friction surface 511 are missing, the rotation speed of the electric motor 61 changes. The way in which the axial load Fz changes is different.
  • the dashed line indicates the axial load Fz when the first friction material 41 and the second friction material 51 are not worn and the first friction surface 411 and the second friction surface 511 are not damaged. Show change.
  • the solid line shows the change in the axial load Fz when the first friction material 41 and the second friction material 51 are worn although the first friction surface 411 and the second friction surface 511 are not chipped.
  • the dashed line shows the axial load Fz when the first friction material 41 and the second friction material 51 are not worn but the first friction surface 411 and the second friction surface 511 are partially missing. Show change.
  • the size of the first friction material 41 in the brake axial direction DRb becomes smaller than when the first friction material 41 is not worn.
  • the size of the second friction material 51 in the brake axial direction DRb becomes smaller than when the second friction material 51 does not wear. Therefore, the amount of movement of the first housing 21 and the piston 30 necessary for the first friction surface 411 and the second friction surface 511 to abut on the brake rotor R is greater than when the wear is not occurring. That is, as shown in FIG. 21, the number of rotations of the electric motor 61 required until the first friction surface 411 and the second friction surface 511 come into contact with the brake rotor R increases.
  • the amount of change in the brake load is the same proportional coefficient as in the case where the worn first friction member 41 and the second friction member 51 are not worn. is proportional to the amount of change in Therefore, when the first friction material 41 and the second friction material 51 wear, the brake generated by the first friction material 41 and the second friction material 51 when the electric motor 61 is rotated by the target rotation speed Wi is reduced. The load becomes smaller compared to when there is no wear.
  • the brake reaction force against the brake load after the worn first friction member 41 and the second friction member 51 come into contact with the brake rotor R changes in the same manner as the brake load. Therefore, when the first friction material 41 and the second friction material 51 are worn and the brake load when the electric motor 61 is rotated by the target rotation speed Wi becomes small, the brake load when the electric motor 61 is rotated by the target rotation speed Wi is reduced. The reaction force also becomes smaller.
  • the axial load Fz when the electric motor 61 is rotated by the target number of revolutions Wi is, as shown in FIGS. become. That is, when the first friction material 41 and the second friction material 51 are worn, even if the electric motor 61 is rotated by the target rotation speed Wi set on the assumption that the first friction material 41 and the second friction material 51 are not worn, The friction material 51 cannot apply the target brake load Fi to the brake rotor R.
  • the area of the first friction surface 411 that contacts the brake rotor R becomes smaller than when the first friction surface 411 is not damaged.
  • the area of the second friction surface 511 that contacts the brake rotor R becomes smaller than when the second friction surface 511 is not missing.
  • the braking load that the first friction material 41 and the second friction material 51 can generate on the brake rotor R is It becomes smaller than when the surface 511 is not damaged. That is, the brake load when the first friction surface 411 and the second friction surface 511 are missing is the same as the first friction surface 411 and the second friction surface 511 even if the movement amounts of the first housing 21 and the piston 30 are the same. It becomes smaller than when the surface 511 is not damaged. Accordingly, when a part of the first friction surface 411 and the second friction surface 511 is lost, the brake reaction force with respect to the brake load becomes smaller than when there is no loss.
  • the amount of change in the brake load and the brake reaction force generated by the first friction material 41 and the second friction material 51 after the missing first friction surface 411 and the second friction surface 511 come into contact with the brake rotor R is It is proportional to the amount of change in the rotation speed of the electric motor 61 .
  • the proportionality coefficient of the amount of change in the brake load and the brake reaction force proportional to the amount of change in the rotation speed of the electric motor 61 becomes It is smaller than when 411 and second friction surface 511 are not chipped. That is, as shown in FIG. 21, the proportional coefficient of the amount of change in the axial load Fz, which is proportional to the amount of change in the rotational speed of the electric motor 61, is becomes smaller compared to
  • the first friction surface 411 and the second friction surface 511 are lost, the first friction material 41 and the second friction material 51 when the electric motor 61 is rotated by the target number of revolutions Wi will generate a brake on the brake rotor R.
  • the load becomes smaller than when there is no defect. Then, as the brake load decreases, the brake reaction force when the target rotation speed Wi is rotated also decreases.
  • the axial load Fz when the electric motor 61 is rotated by the target rotation speed Wi becomes an insufficient brake load Fo smaller than the target brake load Fi, as shown in FIG. That is, when the first friction surface 411 and the second friction surface 511 are missing, even if the electric motor 61 is rotated by the target rotation speed Wi set on the premise that the first friction surface 411 and the second friction surface 511 are not missing, the brake rotor R does not reach the target speed. Brake load Fi cannot be applied.
  • the control device 80 of the present embodiment performs the control processing shown in FIG. Bring the axial load Fz closer to the target brake load Fi.
  • step S10 the control device 80 detects the transition of the axial load Fz calculated by the load sensor 70 when the electric motor 61 is rotated to the target rotation speed Wi. Then, based on the transition of the axial load Fz calculated by the load sensor 70, the control device 80 determines the number of rotations of the electric motor 61 after the first friction surface 411 and the second friction surface 511 come into contact with the brake rotor R. and the relational expression Fz(W) of the axial load Fz.
  • Equation 1 The amount of change in the axial load Fz after the first friction surface 411 and the second friction surface 511 come into contact with the brake rotor R is proportional to the amount of change in the rotation speed of the electric motor 61 as described above. Therefore, the relational expression Fz(W) between the number of rotations of the electric motor 61 and the axial load Fz can be represented by a linear function shown in Equation 1 below.
  • the proportional coefficient ⁇ when the first friction material 41 and the second friction material 51 are worn is substantially equal to the proportional coefficient ⁇ when the first friction material 41 and the second friction material 51 are not worn.
  • the intercept ⁇ when the first friction material 41 and the second friction material 51 are worn is smaller than the intercept ⁇ when the first friction material 41 and the second friction material 51 are not worn.
  • the proportional coefficient ⁇ when the first friction surface 411 and the second friction surface 511 are missing is compared to the proportional coefficient ⁇ when the first friction surface 411 and the second friction surface 511 are not missing. become smaller.
  • the intercept ⁇ when the first friction material 41 and the second friction material 51 are missing is substantially equal to the intercept ⁇ when the first friction material 41 and the second friction material 51 are not missing. .
  • the proportionality coefficient ⁇ and the intercept ⁇ when the first friction material 41 and the second friction material 51 are not worn or missing are obtained when the electric motor 61 is operated when the first and second brake pads 40 and 50 are new. It can be detected from the transition of the axial load Fz when rotating up to the target rotational speed Wi.
  • the control device 80 previously detects and stores the proportional coefficient ⁇ and the intercept ⁇ when the first friction material 41 and the second friction material 51 are not worn or missing.
  • step S12 the control device 80 obtains the post-correction rotational speed Wo of the electric motor 61 based on the relational expression Fz(W) and the target brake load Fi.
  • the post-correction rotation speed Wo is the rotation speed of the electric motor 61 required to obtain the target brake load Fi in the relational expression Fz(W).
  • step S14 the control device 80 calculates the corrected rotational speed dW of the electric motor 61 based on the target rotational speed Wi and the post-correction rotational speed Wo.
  • the corrected rotational speed dW is the difference between the target rotational speed Wi and the post-correction rotational speed Wo.
  • step S16 the control device 80 outputs to the electric motor 61 a control signal for changing the rotation speed of the electric motor 61 by the correction rotation speed dW.
  • the electric motor 61 rotates the rotating shaft 631 according to the corrected rotational speed dW. This changes the positions of the first housing 21 and the piston 30 . Then, the axial load Fz approaches the target brake load Fi.
  • the control device 80 determines the amount of wear of the first and second friction members 41, 51 and the first and second friction surfaces 411, 411 and 411. , 511 are detected.
  • the radial load Fx, orthogonal load Fy, and axial load Fz calculated by the load sensor 70 are the wear amounts of the first and second friction members 41 and 51 and the first and second friction members 41 and 51 .
  • the change according to the state of the two friction surfaces 411 and 511 will be described.
  • the radial load Fx, orthogonal load Fy, and axial load Fz calculated by the load sensor 70 change depending on the wear amount and state of at least one of the first friction member 41 and the second friction member 51 . Therefore, the case where the first friction material 41 is worn or its state is changed will be described below.
  • the radial load Fx and the orthogonal load Fy calculated by the load sensor 70 are shown when the first friction material 41 is not worn and when the state of the first friction material 41 is changed due to wear or the like. , and the axial load Fz.
  • the case where the first friction material 41 is not worn is assumed to be, for example, an initial state in which the first friction material 41 has not yet been used. Further, when the state of the first friction surface 411 is changed, for example, the first friction surface 411 is worn uniformly or unevenly due to long-term use of the first friction material 41 for braking the vehicle. It is assumed that the state and a part of the first friction surface 411 are missing.
  • the dashed line a indicates the case where the first friction material 41 is in the initial state, the case where the first friction surface 411 is uniformly worn, and the case where the first friction surface 411 is partially damaged.
  • the radial load Fx is shown for each of the case and state.
  • a dashed-dotted line b indicates the radial load Fx when the first friction surface 411 is unevenly worn.
  • the dashed line c indicates the initial state of the first friction material 41, the evenly worn state of the first friction surface 411, and the partially missing state of the first friction surface 411. and the orthogonal direction load Fy for each case.
  • a dashed line d indicates the orthogonal direction load Fy when the first friction surface 411 is unevenly worn.
  • the solid line e indicates the axial load Fz when the first friction material 41 is in the initial state.
  • a solid line f indicates the axial load Fz when the first friction surface 411 is uniformly worn.
  • a solid line h indicates the axial load Fz when a part of the first friction surface 411 is missing.
  • a solid line k indicates the axial load Fz when the first friction surface 411 is unevenly worn.
  • the radial load Fx calculated by the load sensor 70 when the controller 80 rotates the electric motor 61 at the target rotation speed Wi when the first friction member 41 is in the initial state is the initial radial load Fx0.
  • the magnitude of the orthogonal direction load Fy is assumed to be an initial orthogonal direction load Fy0. Further, when the control device 80 rotates the electric motor 61 at the target rotation speed Wi when the first friction material 41 is in the initial state, the magnitude of the axial load Fz calculated by the load sensor 70 is changed to Assume that the load is Fz0.
  • the brake reaction force does not include loads in directions other than the brake axial direction DRb.
  • the magnitudes of the initial radial load Fx0 and the initial orthogonal load Fy0 are approximately 0, as shown in FIG. That is, when the first friction member 41 is in the initial state, no load is applied to the load surface 714a in the load radial direction DRx and the load orthogonal direction DRy.
  • the initial axial load Fz0 is approximately equal to the target brake load Fi.
  • the number of revolutions of the electric motor 61 required until the first friction surface 411 comes into contact with the brake rotor R is the first friction material It becomes larger than when 41 is not worn. Also, the brake load when the electric motor 61 is rotated at the target rotation speed Wi becomes smaller than when the first friction member 41 is not worn.
  • the axial load Fz calculated by the load sensor 70 when the electric motor 61 is rotated at the target rotation speed Wi when the first friction member 41 is worn is less than the initial axial load Fz0. become smaller. That is, the axial load Fz calculated by the load sensor 70 is smaller than the target brake load Fi.
  • the number of revolutions of the electric motor 61 required until the first friction surface 411 comes into contact with the brake rotor R increases as the amount of wear of the first friction material 41 increases, as shown in FIG. Therefore, the brake load when the electric motor 61 is rotated at the target rotation speed Wi decreases as the wear amount of the first friction member 41 increases.
  • the axial load Fz calculated by the load sensor 70 when the electric motor 61 is rotated at the target rotation speed Wi when the first friction member 41 is worn is The larger it is, the smaller it becomes compared to the initial axial load Fz0. That is, the axial load Fz calculated by the load sensor 70 becomes smaller than the initial axial load Fz0 as the amount of wear of the first friction member 41 increases. In other words, the difference between the axial load Fz calculated by the load sensor 70 and the initial axial load Fz0 increases as the wear amount of the first friction member 41 increases.
  • the absolute value of the axial deviation ⁇ Fz is the first friction coefficient as shown in FIG. It increases as the amount of wear of the material 41 increases. 27 to 30, the solid line indicates the axial deviation ⁇ Fz.
  • the amount of change in the brake load after the worn first friction member 41 comes into contact with the brake rotor R is proportional to the same proportional coefficient as when the first friction member 41 is not worn, and the number of revolutions of the electric motor 61 is Proportional to the amount of change. Therefore, the axial deviation ⁇ Fz after the worn first friction member 41 comes into contact with the brake rotor R is constant regardless of the target rotational speed Wi, as shown in FIG.
  • the brake reaction force is generated along the brake axial direction DRb, as in the case where the first friction material 41 is in the initial state. Therefore, when the first friction member 41 is evenly worn, the respective magnitudes of the radial load Fx and the orthogonal direction load Fy are equal to the initial radial load Fx0 and It is approximately 0, similar to the initial orthogonal direction load Fy0.
  • the amount of divergence between the radial load Fx calculated by the load sensor 70 and the initial radial load Fx0 is the radial divergence ⁇ Fx
  • the amount of divergence between the orthogonal load Fy calculated by the load sensor 70 and the initial orthogonal load Fy0 is Let the deviation in the orthogonal direction be ⁇ Fy.
  • the radial deviation ⁇ Fx and the orthogonal direction deviation ⁇ Fy are approximately 0 regardless of the amount of wear of the first friction member 41, as shown in FIG.
  • the one-dot dashed line indicates the radial divergence ⁇ Fx
  • the dashed line indicates the orthogonal divergence ⁇ Fy.
  • the brake reaction force is such that the load with which the first friction material 41 presses the brake rotor R is inclined with respect to the brake axial direction DRb as described above. Therefore, it includes load components in directions other than the brake axial direction DRb. Therefore, at least one of the radial load Fx and the orthogonal load Fy is applied to the load surface 714a. In the description of this embodiment, the case where both the radial load Fx and the orthogonal load Fy are applied to the load surface 714a will be described.
  • each of the radial load Fx and the orthogonal load Fy when the electric motor 61 is rotated at the target rotation speed Wi is equal to the initial radial load greater than Fx0 and the initial orthogonal load Fy0. That is, when the first friction member 41 is unevenly worn, each of the radial load Fx and the orthogonal load Fy when the electric motor 61 is rotated at the target rotation speed Wi becomes a value away from zero.
  • the radial load Fx and the orthogonal load Fy calculated by the load sensor 70 are the initial radial load Fx0 and the initial orthogonal load Fy as the target brake load Fi increases.
  • the difference from Fy0 increases. That is, the radial deviation ⁇ Fx and the orthogonal deviation ⁇ Fy increase as the target rotation speed Wi increases, as shown in FIG.
  • the amount of change in the radial deviation ⁇ Fx and the amount of change in the orthogonal direction deviation ⁇ Fy decrease in proportion to the target rotational speed Wi.
  • the greater the inclination of the first friction surface 411 with respect to the brake axial direction DRb when the first friction member 41 is unevenly worn the greater the amount of change in the radial deviation ⁇ Fx with respect to the amount of change in the target rotational speed Wi. , and the ratio of the amount of change in the orthogonal deviation ⁇ Fy increases.
  • the greater the inclination of the first friction surface 411 the greater the absolute value of the radial coefficient kx, which is a proportional coefficient when the correlation between the radial deviation ⁇ Fx and the target rotational speed Wi is represented by a linear function.
  • the unevenly worn friction surface of the first friction surface 411 and the second friction surface 511 is As the inclination increases, the absolute values of the radial coefficient kx and the orthogonal coefficient ky increase.
  • the radial load Fx and the orthogonal load Fy when the electric motor 61 is rotated at the target rotation speed Wi are , away from 0.
  • the load Fx and the orthogonal load Fy are further away from zero.
  • the axial load Fz becomes smaller than the initial axial load Fz0.
  • the axial load Fz when the first friction member 41 is unevenly worn decreases as the radial load Fx and the orthogonal load Fy increase. That is, the absolute value of the axial deviation ⁇ Fz decreases as the radial load Fx and the orthogonal load Fy increase.
  • the absolute value of the axial deviation ⁇ Fz increases as the absolute values of the radial deviation ⁇ Fx and the orthogonal direction deviation ⁇ Fy increase. Also, the greater the inclination of the first friction surface 411, the greater the absolute value of the axial coefficient kz, which is the proportional coefficient when the correlation between the axial deviation ⁇ Fz and the target rotational speed Wi is represented by a linear function.
  • the first friction material 41 is hardly worn but a part of the first friction surface 411 is missing.
  • the brake reaction force is the same as when the first friction material 41 is worn substantially evenly. It occurs along the axial direction DRb. Therefore, when a part of the first friction surface 411 is missing, the magnitude of each of the radial load Fx and the orthogonal direction load Fy when the electric motor 61 is rotated at the target rotation speed Wi is the initial radial direction Similar to the load Fx0 and the initial orthogonal direction load Fy0, it is approximately zero.
  • the axial load Fz calculated by the load sensor 70 when the electric motor 61 is rotated at the target rotation speed Wi when the first friction surface 411 is partially missing is , becomes smaller compared to the initial axial load Fz0. That is, the axial load Fz calculated by the load sensor 70 is smaller than the target brake load Fi.
  • the difference between the axial load Fz calculated by the load sensor 70 and the initial axial load Fz0 increases as the target brake load Fi increases. That is, as shown in FIG. 30, the absolute value of the axial deviation ⁇ Fz increases as the target rotational speed Wi increases. Then, the absolute value of the axial deviation ⁇ Fz increases in proportion to the amount of change in the target rotation speed Wi.
  • step S20 similarly to step S10, the control device 80 controls the rotation speed and the axial load Fz of the electric motor 61 after the first friction surface 411 and the second friction surface 511 come into contact with the brake rotor R. Obtain the relational expression Fz(W).
  • the control device 80 determines whether at least one of the first friction material 41 and the second friction material 51 is worn, and determines whether the first friction surface 411 and the second friction surface 411 are worn. It is determined whether or not at least one of the surfaces 511 is missing. Specifically, the control device 80 calculates the difference between the intercept of the obtained relational expression Fz(W) and the intercept of the relational expression Fz(W) when the first and second friction members 41 and 51 are in the initial state. It is determined whether or not the absolute value of a certain intercept difference is greater than or equal to a predetermined threshold.
  • control device 80 determines that the absolute value of the intercept difference is equal to or greater than the predetermined threshold value, it determines that at least one of the first friction material 41 and the second friction material 51 is worn. On the other hand, if the control device 80 does not determine that the absolute value of the intercept difference is equal to or greater than the predetermined threshold value, it determines that neither the first friction material 41 nor the second friction material 51 is worn.
  • control device 80 calculates the difference between the proportional coefficient in the obtained relational expression Fz(W) and the proportionality coefficient in the relational expression Fz(W) when the first and second friction members 41 and 51 are in the initial state. It is determined whether or not the absolute value of a certain proportionality coefficient difference is greater than or equal to a predetermined threshold.
  • control device 80 determines that the absolute value of the proportionality coefficient difference is equal to or greater than the predetermined threshold value, it determines that at least one of the first friction surface 411 and the second friction surface 511 is missing. On the other hand, if the control device 80 does not determine that the absolute value of the proportionality coefficient difference is equal to or greater than the predetermined threshold value, it determines that neither the first friction surface 411 nor the second friction surface 511 is defective. do.
  • step S22 the control device 80 calculates the radial deviation ⁇ Fx, the orthogonal direction deviation ⁇ Fy, Axial deviation ⁇ Fz is calculated.
  • step S24 the control device 80 calculates the radial coefficient kx, the orthogonal direction coefficient ky, the axial direction coefficient kz based on the target rotation speed Wi and the calculated radial deviation ⁇ Fx, orthogonal direction deviation ⁇ Fy, and axial direction deviation ⁇ Fz.
  • step S26 the control device 80 detects the amount of wear of the first and second friction members 41, 51 based on the calculated axial deviation ⁇ Fz. Specifically, when the control device 80 determines in step S20 that at least one of the first friction material 41 and the second friction material 51 is worn, the value of the axial deviation ⁇ Fz and the predetermined determination The amount of wear of the first and second friction members 41 and 51 is calculated with reference to the reference value.
  • a first wear threshold and a second wear threshold that is smaller than the first wear threshold are set as determination reference values for calculating the wear amounts of the first and second friction materials 41 and 51 . Then, when the absolute value of the axial deviation ⁇ Fz is smaller than the first wear threshold, the control device 80 determines that the amount of wear is relatively small, and the absolute value of the axial deviation ⁇ Fz is larger than the first wear threshold and the second wear threshold. If it is smaller than the wear threshold, it is determined that the wear amount is relatively large. Further, when the absolute value of the axial deviation ⁇ Fz is greater than the second wear threshold, the control device 80 reduces the first and second friction members 41 and 51 to such an extent that the first and second brake pads 40 and 50 need to be replaced. is determined to be worn.
  • step S26 the control device 80 detects the states of the first and second friction surfaces 411 and 511 based on the calculated radial coefficient kx, orthogonal direction coefficient ky, and axial direction coefficient kz. Specifically, when it is determined in step S20 that at least one of the first friction material 41 and the second friction material 51 is worn, the first friction material 41 and the second friction material 51 are worn based on the radial coefficient kx and the orthogonal coefficient ky. It is determined whether or not the friction surfaces 411 and 511 are unevenly worn.
  • the controller 80 determines that at least one of the radial coefficient kx and the orthogonal coefficient ky is not approximately 0, at least one of the first friction surface 411 and the second friction surface 511 is biased. Determined to be worn.
  • the control device 80 determines that both the radial coefficient kx and the orthogonal coefficient ky are approximately 0, neither the first friction surface 411 nor the second friction surface 511 is unevenly worn. I judge.
  • the control device 80 determines that at least one of the first friction surface 411 and the second friction surface 511 is unevenly worn, the degree of inclination of the first friction surface 411 and the second friction surface 511 Calculate
  • the control device 80 refers to the value of the radial direction coefficient kx, the value of the orthogonal direction coefficient ky, and a predetermined criterion value to determine the magnitude of the inclination of the first friction surface 411 and the second friction surface 511 with respect to the brake axial direction DRb. to calculate the
  • a first tilt threshold and a second tilt threshold that is larger than the first tilt threshold are set as determination reference values for calculating the magnitude of the tilt of the first friction surface 411 and the second friction surface 511 . Then, when the absolute values of both the radial coefficient kx and the orthogonal direction coefficient ky are smaller than the first tilt threshold, the control device 80 determines that the tilts of the first friction surface 411 and the second friction surface 511 are relatively small. .
  • the controller 80 controls the first and second friction coefficients It is determined that the inclination of the surfaces 411 and 511 is relatively large. Furthermore, when the absolute values of both the radial coefficient kx and the orthogonal coefficient ky are greater than the second tilt threshold, the control device 80 controls the first and second brake pads 40 and 50 to require replacement. It is determined that at least one of the second friction members 41 and 51 is unevenly worn.
  • control device 80 refers to the value of the axial coefficient kz and a predetermined determination reference value to calculate the magnitude of the inclination of the first friction surface 411 and the second friction surface 511 with respect to the brake axial direction DRb. good too.
  • control device 80 determines in step S20 that at least one of the first friction surface 411 and the second friction surface 511 is missing, the value of the axial coefficient kz and the predetermined determination reference value , and calculate the size of the missing area.
  • a first wear threshold and a second wear threshold larger than the first wear threshold are set as criteria values for calculating the sizes of the wear ranges of the first friction surface 411 and the second friction surface 511. . If the axial coefficient kz is smaller than the first loss threshold, the control device 80 determines that the loss range is relatively small, and if the axial coefficient kz is greater than the first loss range threshold and smaller than the second loss threshold, , the missing range is determined to be relatively large. Further, if the axial coefficient kz is greater than the second loss threshold, the control device 80 controls at least the first friction surface 411 and the second friction surface 511 to require replacement of the first and second brake pads 40 and 50 . It is determined that one is missing.
  • step S28 the control device 80 outputs the detected wear amounts of the first and second friction materials 41 and 51 and the states of the first and second friction surfaces 411 and 511 to the outside.
  • the control device 80 displays the determination result regarding the wear amount of the first and second friction members 41 and 51 and the state of the first and second friction surfaces 411 and 511 on a display device (not shown) provided in the vehicle interior. By outputting, it may be configured to be able to notify the driver of the determination result.
  • the control device 80 transmits the determination result regarding the wear amount of the first and second friction materials 41 and 51 and the state of the first and second friction surfaces 411 and 511 to a server (not shown) outside the vehicle or the cloud. It may be configured to be possible.
  • the load sensor 70 of the present embodiment detects the axial load Fz applied to the load surface 714a based on the first strain amount of the three parts and the second strain amount of the three parts detected by the load calculation unit 72. Calculate Thereby, even when the unbalanced load F is applied to the load surface 714a, the load in the load axial direction DRz can be detected with high accuracy.
  • the load sensor 70 is used in the electric brake system 1 of this embodiment. Therefore, even if the brake load includes a component in a direction other than the brake axial direction DRb due to uneven wear of at least one of the first friction member 41 and the second friction member 51, the axial direction of the brake reaction force The load Fz can be detected with high accuracy.
  • the electric motor 61 can be controlled using the axial load Fz. , the axial load Fz can be brought close to the target brake load Fi.
  • the control device 80 adjusts the rotation speed of the electric motor 61 based on the corrected rotation speed Wo required to obtain the target brake load Fi. Therefore, when the brake load deviates from the target brake load Fi, compared to the method of rotating the electric motor 61 by a preset number of revolutions to adjust the brake load, the axial load Fz is adjusted to the target brake load Fi. You can get close fast.
  • the Wheatstone bridge circuit 721 of the load calculator 72 has the first strain sensor 721a that detects the first strain amount and the second strain sensor 721b that detects the second strain amount. Then, the load calculation unit 722 calculates the third strain amount based on the first strain amount and the second strain amount. For this reason, compared to the case where the load calculation unit 72 includes a third strain sensor that detects the third strain amount in addition to having the first strain sensor 721a and the second strain sensor 721b, the load calculation unit 72 can have a simple configuration.
  • the housing 71 has the diaphragm portion 715a that deforms more easily than the supporting portion 715b when the housing 71 deforms due to the load applied to the load surface 714a.
  • the first strain sensor 721a and the second strain sensor 721b are attached to the diaphragm portion 715a, and the electrical resistance value changes according to the strain amount when they are distorted integrally with the diaphragm portion 715a. Therefore, the first strain sensor 721a and the second strain sensor 721b can easily detect the strain amount of the housing 71 compared to a configuration in which the housing 71 does not have the diaphragm portion 715a.
  • the diaphragm portion 715a is provided at a position overlapping the load surface 714a in the load axis direction DRz, and the magnitude of the load axis direction DRz is greater than that of the support portion 715b around the diaphragm portion 715a. formed small. According to this, compared with the case where the diaphragm portion 715a is formed of a member having a lower rigidity than the supporting portion 715b, it is possible to provide the housing 71 with a portion that is easily deformed with a simple structure.
  • the diaphragm portion 715a has the mounting surface 715c extending along the direction in which the load surface 714a extends.
  • the first strain sensor 721a is provided on the mounting surface 715c and detects the first strain amount on the mounting surface 715c.
  • the second strain sensor 721b is provided on the mounting surface 715c and detects the second strain amount on the mounting surface 715c. Therefore, when the brake reaction force is applied to the load surface 714a, the diaphragm portion 715a extending parallel to the load surface 714a deforms in the direction in which the mounting surface 715c extends, compared to the direction orthogonal to the load surface 714a.
  • the Wheatstone bridge circuit 721 has a strain sensor for detecting the strain amount in the direction orthogonal to the load surface 714a, it becomes easier to detect the strain amount of the diaphragm portion 715a.
  • the housing 71 has a hollow shape with the space S inside, and has the outer wall portion 711 surrounding the space S.
  • the Wheatstone bridge circuit 721 is provided at a portion of the outer wall portion 711 on the side surrounding the space S. As shown in FIG. According to this, the Wheatstone bridge circuit 721 can be housed inside the housing 71 and protected by the outer wall portion 711 .
  • the load calculation unit 722 calculates the radial load Fx and the orthogonal load Fy applied to the load surface 714a based on the first strain amount of the three parts and the second strain amount of the three parts. calculate. As a result, even when an unbalanced load F is applied to the load surface 714a, the radial load Fx and the orthogonal load Fy can be accurately detected.
  • the control device 80 determines the target rotation speed Wi of the electric motor 61 based on the target brake load Fi determined when the brake pedal is operated. Then, the axial deviation ⁇ Fz, which is the difference between the axial load Fz obtained by the load sensor 70 and the target brake load Fi when the electric motor 61 is rotated at the target rotation speed Wi, is calculated. Based on this, the wear amounts of the first and second friction materials 41 and 51 are calculated.
  • a load sensor is used as a detection sensor for detecting that the amount of wear of the first and second friction members 41 and 51 reaches a predetermined threshold value.
  • a method of providing it separately from 70 for example, by setting the predetermined threshold to a value that requires replacement of the first and second brake pads 40 and 50, the amount of wear of the first and second friction members 41 and 51 is reduced to a predetermined value. When the threshold value is reached, the driver or the like can be urged to replace the first and second brake pads 40 and 50 .
  • the method of providing a detection sensor for detecting the amount of wear of the first and second friction members 41 and 51 separately from the load sensor 70 is a factor that increases the cost of the electric brake system 1 . Become.
  • the method of detecting when the wear amounts of the first and second friction materials 41 and 51 reach a predetermined threshold Wear amount cannot be detected. Therefore, with this method, it is difficult to notify the driver of information for predicting when to replace the first and second brake pads 40 and 50 .
  • the electric brake system 1 of this embodiment can calculate the wear amounts of the first and second friction members 41 and 51 based on the detection result of the load sensor 70 that detects the brake load. Therefore, the cost of the electric brake system 1 can be reduced compared to a configuration in which a detection sensor for detecting the amount of wear of the first and second friction members 41 and 51 is provided separately from the load sensor 70 . In addition, for example, by notifying the driver of the amount of wear of the first and second friction materials 41 and 51, the driver can predict in advance when to replace the first and second brake pads 40 and 50. Become.
  • the control device 80 determines the target rotation speed Wi of the electric motor 61 based on the target brake load Fi determined when the brake pedal is operated. Then, based on the axial direction coefficient kz based on the axial direction deviation ⁇ Fz, which is the difference between the axial direction load Fz obtained by the load sensor 70 and the target brake load Fi when the electric motor 61 is rotated at the target rotation speed Wi, the first , the defect of the second friction surfaces 411 and 511 is detected.
  • the first and second friction surfaces 411 and 511 when the first and second friction surfaces 411 and 511 are lost, the first and second friction surfaces 411 and 511 can be replaced without removing the first and second brake pads 40 and 50 from the electric brake system 1 . 511 defects can be detected.
  • the load sensor 70 detects the radial load Fx and the orthogonal load Fx. Find the directional load Fy. Based on the radial load Fx and the orthogonal load Fy obtained by the load sensor 70, the control device 80 calculates the magnitude of the inclination of the friction surface with respect to the load axial direction DRz. According to this, when the first and second friction members 41 and 51 are unevenly worn, the first and second friction surfaces 411 can be removed without removing the first and second brake pads 40 and 50 from the electric brake system 1 . , 511 can be detected.
  • the housing 71 has an annular shape with the through hole 73 extending along the brake axial direction DRb.
  • a rotary shaft 631 is inserted through the through hole 73 of the load sensor 70 .
  • the load calculator 72 detects the first strain amount and the three second strain amounts of three portions of the housing 71 along the circumferential direction of the rotating shaft 631 . This makes it easier to detect the reaction force of the brake load generated by the rotation of the rotating shaft 631 than when the load sensor 70 does not have such a configuration.
  • the present embodiment differs from the first embodiment in that the load sensor 70 has a deformation enhancing section 74 in addition to the housing 71 and the load calculating section 72 . Other than this, it is the same as the first embodiment. Therefore, in this embodiment, parts different from the first embodiment will be mainly described, and explanations of parts similar to the first embodiment may be omitted.
  • the load sensor 70 is arranged apart from the cylinder 221 of the second housing 22 in the housing 20 .
  • the load sensor 70 has a deformation emphasizing portion 74 provided between the housing 71 and the cylinder 221 .
  • the deformation enhancing portion 74 is arranged in the gap between the housing 71 and the cylinder 221 .
  • three deformation enhancing portions 74 are arranged in the gap between the housing 71 and the cylinder 221 .
  • the deformation emphasizing portion 74 is for increasing the amount of deformation of the diaphragm portion 715a when the diaphragm portion 715a is deformed by receiving a braking reaction force.
  • the deformation enhancing portion 74 is fixed to the cylinder bottom portion 221b of the cylinder 221. As shown in FIG. Specifically, each of the three deformation enhancing portions 74 is fixed at a position facing the diaphragm portion 715a of the sensor bottom portion 715 on the inner peripheral surface of the cylinder bottom portion 221b on the first braking direction DRb1 side. That is, each of the three deformation emphasizing portions 74 is arranged at a position overlapping the diaphragm portion 715a in the brake axial direction DRb and on the second brake direction DRb2 side of the diaphragm portion 715a.
  • the second braking direction DRb2 corresponds to the pressing direction
  • the first braking direction DRb1 corresponds to the reaction force direction.
  • the three deformation emphasizing portions 74 are arranged on the cylinder bottom portion 221b at 120° intervals along the circumferential direction of the central axis CL, and overlap the three Wheatstone bridge circuits 721 in the brake axial direction DRb. are placed in A portion of the three deformation enhancing portions 74 is inserted into a recessed portion 715 d that is recessed toward the space S side in the sensor bottom portion 715 .
  • the deformation enhancement portion 74 has a shape that protrudes toward the first brake direction DRb1 in the brake shaft direction DRb, and is configured separately from the housing 71 . Further, the deformation enhancing portion 74 has a base portion 741 and a pressing portion 742 .
  • the base portion 741 and the pressing portion 742 are made of metal such as iron, for example, and are integrally formed. However, the material of the base portion 741 and the pressing portion 742 is not limited, and the base portion 741 and the pressing portion 742 may be formed of a metal other than iron (for example, aluminum), or may be made of a material different from metal. (for example, resin).
  • the base portion 741 is a portion fixed to the cylinder bottom portion 221b.
  • the base portion 741 has a disc shape whose plate thickness direction is in the brake axial direction DRb, and the plate surface on the second brake direction DRb2 side is fixed to the cylinder bottom portion 221b. Further, the base portion 741 has a plate surface on the side of the first braking direction DRb1, and a pressing portion 742 continues therefrom.
  • the base portion 741 is a support member that supports the pressing portion 742 . Note that the base portion 741 may have a shape different from the disk shape (for example, a rectangular parallelepiped shape) as long as it can support the pressing portion 742 .
  • the pressing portion 742 is a member that presses the diaphragm portion 715a when receiving brake reaction force.
  • the pressing portion 742 has a columnar shape extending along the brake axial direction DRb, and has a substantially perfect circular cross-sectional shape perpendicular to the brake axial direction DRb.
  • the pressing portion 742 continues to the base portion 741 on the second brake direction DRb2 side.
  • the pressing portion 742 is formed to have a size larger in the brake axial direction DRb than the size of the recess 715d in the brake axial direction DRb (that is, the size in the depth direction), and an outer diameter of the recess 715d. It is formed smaller than the inner diameter. That is, the pressing portion 742 is formed with a size that allows it to be inserted into the recess 715d.
  • a portion of the pressing portion 742 of the present embodiment is inserted into the recess 715d, and the end on the first brake direction DRb1 side faces the diaphragm portion 715a. Also, the pressing portion 742 is in contact with the diaphragm portion 715a, but is not connected. The pressing portion 742 does not press the diaphragm portion 715a when the load sensor 70 does not receive the brake reaction force.
  • the shape of the pressing portion 742 is not limited to a columnar shape having a substantially perfect circle in cross section perpendicular to the brake shaft direction DRb.
  • the pressing portion 742 may have a cylindrical shape with an elliptical cross-sectional shape perpendicular to the brake shaft direction DRb.
  • the shape of the pressing portion 742 may be a prismatic shape whose cross-sectional shape perpendicular to the brake shaft direction DRb is a polygon such as a quadrangle.
  • the end portion of the pressing portion 742 on the first braking direction DRb1 side may have a shape that bulges toward the first braking direction DRb1 side.
  • load sensor 70 When the driver depresses the brake pedal P, a braking load is generated on the brake rotor R and a braking reaction force is generated on the rotating shaft 631 . The generated brake reaction force is transmitted to load sensor 70 via thrust bearing 633 . Load sensor 70 detects brake reaction force transmitted via thrust bearing 633 .
  • the load sensor 70 detects the brake reaction force based on the distortion amount of the housing 71 when the load surface 714a is pressed by the thrust bearing 633 toward the second braking direction DRb2 and the housing 71 is deformed. Specifically, when the diaphragm portion 715a of the housing 71 is deformed by the brake reaction force, the load sensor 70 detects the first strain sensor 721a and the second strain sensor 721b of the Wheatstone bridge circuit 721 provided in the diaphragm portion 715a. Detect changes in strain amount.
  • the load sensor 70 of this embodiment is provided with a deformation enhancing portion 74 at a position facing the diaphragm portion 715a.
  • the load sensor 70 is pressed by the thrust bearing 633 and moves in the second braking direction DRb2
  • the diaphragm portion 715a on the second braking direction DRb2 side is pressed by the pressing portion 742 of the deformation enhancing portion 74 in the first braking direction DRb1.
  • the deformation enhancing portion 74 moves toward the first braking direction DRb1 opposite to the second braking direction DRb2 where the load surface 714a is pressed.
  • the diaphragm portion 715a is pressed.
  • the diaphragm portion 715a is deformed so as to expand toward the first braking direction DRb1.
  • the first strain sensor 721a and the second strain sensor 721b provided in the diaphragm portion 715a also deform.
  • the electrical resistance values of the first strain sensor 721a and the second strain sensor 721b change.
  • the difference in the amount of deformation of the diaphragm portion 715a between when the load sensor 70 is provided with the deformation enhancing portion 74 and when it is not provided will be described.
  • the load sensor 70 when the load surface 714a is pressed by the brake reaction force, the load sensor 70 moves toward the second braking direction DRb2 while the housing 71 moves toward the second braking direction DRb2. The whole is transformed. At this time, the brake reaction force affects the entire housing 71 and deforms the entire housing 71 .
  • the load sensor 70 when the load surface 714a is pressed by the brake reaction force, the load sensor 70 detects that the portion of the housing 71 excluding the diaphragm portion 715a is the first 2 Move to the DRb2 side in the braking direction.
  • the diaphragm portion 715a is pressed in the first braking direction DRb1 by the deformation enhancing portion 74 as the portion of the housing 71 excluding the diaphragm portion 715a moves in the second braking direction DRb2.
  • the brake reaction force concentrates on the diaphragm portion 715a of the housing 71, and deforms the diaphragm portion 715a more than other portions. That is, the deformation emphasizing portion 74 can increase the amount of deformation of the diaphragm portion 715a as compared with the case where the load sensor 70 does not include the deformation emphasizing portion 74 .
  • the load calculation unit 722 detects the relative change in the electrical resistance values of the first strain sensor 721a and the second strain sensor 721b that change according to the amount of strain generated in the diaphragm portion 715a, the relative change in the electrical resistance value is detected. can be done easily. According to this, it is possible to improve the detection sensitivity when the load sensor 70 detects the load applied to the load surface 714a.
  • the deformation enhancing portion 74 is configured separately from the housing 71 and the pressing portion 742 is not connected to the diaphragm portion 715a has been described, but the present invention is not limited to this.
  • the deformation enhancement section 74 may be configured integrally with the housing 71 .
  • the pressing portion 742 and the diaphragm portion 715a may be connected by a method such as welding or adhesion.
  • the deformation enhancing portions 74 may be provided in the load sensor 70 in a number less than three, or may be provided in a number greater than three. Further, the deformation emphasizing portion 74 may be arranged at a position not overlapping with each of the three Wheatstone bridge circuits 721 in the brake axial direction DRb.
  • the Wheatstone bridge circuit 721 of the load calculator 72 has the first strain sensor 721a that detects the first strain amount and the second strain sensor 721b that detects the second strain amount. Then, an example in which the load calculation unit 722 calculates the third strain amount based on the first strain amount detected by the first strain sensor 721a and the second strain amount detected by the second strain sensor 721b has been described. It is not limited to this.
  • the load calculator 72 may have a strain sensor for detecting the third strain amount in addition to the Wheatstone bridge circuit 721 having the first strain sensor 721a and the second strain sensor 721b.
  • the load calculator 72 has three Wheatstone bridge circuits 721 and the load calculator 722 .
  • each of the three Wheatstone bridge circuits 721 includes a first strain sensor 721a that detects strain in the load radial direction DRx, a second strain sensor 721b that detects strain in the load orthogonal direction DRy, a first resistance unit 721c, a 2 resistor portions 721d.
  • An example in which the load calculation unit 722 calculates the strain amounts in the load radial direction DRx, the load orthogonal direction DRy, and the load axial direction DRz based on the voltage values of the three Wheatstone bridge circuits 721 has been described. is not limited to
  • the load calculator 72 may be configured to have six Wheatstone bridge circuits 721 and a load calculator 722 .
  • three Wheatstone bridge circuits 721 may have a first strain sensor 721a for detecting strain in the load radial direction DRx and three resistance units.
  • the remaining three Wheatstone bridge circuits 721 may be configured to have a second strain sensor 721b for detecting strain in the load orthogonal direction DRy and three resistance units.
  • the load calculation unit 722 may calculate the strain amounts in the load radial direction DRx, the load orthogonal direction DRy, and the load axial direction DRz.
  • each of the three Wheatstone bridge circuits 721 has the first strain sensor 721a that detects the strain amount in the load radial direction DRx and the second strain sensor 721b that detects the strain amount in the load orthogonal direction DRy is described.
  • the Wheatstone bridge circuit 721 detects only the strain amount in either one of the load radial direction DRx and the load orthogonal direction DRy. It may be configured to detect.
  • the load calculation unit 72 may be configured to include two or more Wheatstone bridge circuits 721 having only the first strain sensor 721a and two or more Wheatstone bridge circuits 721 having only the second strain sensor 721b. .
  • the load calculator 72 may have two Wheatstone bridge circuits 721 or four or more Wheatstone bridge circuits 721 .
  • the configuration having two Wheatstone bridge circuits 721 can reduce the cost of the load sensor 70 compared to the configuration having three Wheatstone bridge circuits 721 .
  • the detection accuracy of the load sensor 70 can be improved as the number of the Wheatstone bridge circuits 721 is increased.
  • first strain sensor 721a and the second strain sensor 721b are provided on the mounting surface 715c
  • present invention is not limited to this.
  • the first strain sensor 721a and the second strain sensor 721b may be provided on the load receiving portion 714 or may be provided on the support portion 715b.
  • the load calculation section 72 is provided at a portion on the space S side of the outer wall section 711 surrounding the space S, but the present invention is not limited to this.
  • the load calculator 72 may be provided at a portion of the outer wall portion 711 opposite to the space S side.
  • the housing 71 has the easily deformable diaphragm portion 715a and the first strain sensor 721a and the second strain sensor 721b are attached to the diaphragm portion 715a has been described, but the present invention is not limited to this.
  • the housing 71 may be configured without the diaphragm portion 715a.
  • the first strain sensor 721a and the second strain sensor 721b may be attached to the support portion 715b, for example.
  • the housing 71 of the load sensor 70 has a hollow annular shape
  • the present invention is not limited to this.
  • the shape of the housing 71 of the load sensor 70 can be appropriately designed according to the installation location and the load to be detected.
  • the diaphragm portion 715a is formed to have a smaller size in the load axis direction DRz than the support portion 715b surrounding the diaphragm portion 715a, and is easily deformed compared to the support portion 715b.
  • the diaphragm part 715a may be made of a member having a lower rigidity than the support part 715b, so that the diaphragm part 715a may be configured to deform more easily than the support part 715b.
  • control device 80 calculates the axial deviation ⁇ Fz and calculates the wear amounts of the first and second friction members 41 and 51 based on the calculated axial deviation ⁇ Fz has been described. It is not limited to this.
  • the control device 80 may be configured not to calculate the wear amounts of the first and second friction materials 41 and 51 .
  • the control device 80 calculates the magnitude of the inclination of the first and second friction surfaces 411 and 511 with respect to the brake axial direction DRb based on the radial load Fx and the orthogonal load Fy. but not limited to this.
  • the control device 80 may be configured not to calculate the magnitude of the inclination of the first and second friction surfaces 411 and 511 with respect to the brake axial direction DRb.
  • control device 80 calculates the axial coefficient kz and detects loss of the first and second friction members 41 and 51 based on the calculated axial coefficient kz has been described. is not limited to For example, the control device 80 may be configured not to calculate the loss of the first and second friction materials 41 and 51 .
  • the control device 80 when the control device 80 performs feedback control, the relational expression Fz(W) is obtained based on the transition of the axial load Fz calculated by the load sensor 70 . Then, an example in which the control device 80 rotates the electric motor 61 by the corrected rotational speed dW calculated based on the relational expression Fz(W) and the target brake load Fi, and controls the brake load to approach the target brake load Fi. has been described, but is not limited to this.
  • the control device 80 rotates the electric motor 61 by a preset number of revolutions so that the brake load approaches the target brake load Fi. can be controlled as follows.
  • the control device 80 refers to the value of the axial coefficient kz and the first and second wear thresholds as predetermined determination reference values, and the first and second friction members 41, 51
  • the present invention is not limited to this.
  • the control device 80 refers to the value of the axial coefficient kz and one predetermined criterion value or three or more criterion values to determine the wear amounts of the first and second friction members 41 and 51. You can judge.
  • the control device 80 refers to the value of the axial coefficient kz and a control map obtained in advance through experiments or the like to calculate specific wear amount values of the first and second friction members 41 and 51. good too.
  • the control device 80 refers to the value of the axial coefficient kz and the first loss threshold and the second loss threshold as predetermined determination reference values, and the first and second friction surfaces 411, 511
  • the control device 80 refers to the value of the axial coefficient kz and one predetermined criterion value or three or more criterion values to determine the loss range of the first and second friction surfaces 411 and 511. size may be determined.
  • the control device 80 refers to the value of the axial coefficient kz and a control map previously obtained by experiments or the like to calculate the specific size of the loss range of the first and second friction surfaces 411 and 511. may
  • the control device 80 refers to the value of the radial coefficient kx, the value of the orthogonal coefficient ky, and the first tilt threshold and the second tilt threshold as determination reference values to determine the first and second friction surfaces.
  • the control device 80 refers to the value of the radial direction coefficient kx, the value of the orthogonal direction coefficient ky, and one predetermined criterion value or three or more criterion values to determine the first and second friction surfaces.
  • the magnitude of the slope of 411, 511 may be determined.
  • control device 80 refers to the value of the radial direction coefficient kx, the value of the orthogonal direction coefficient ky, and a control map obtained in advance by experiments or the like, and determines the specific inclinations of the first and second friction surfaces 411 and 511. can be calculated.
  • the Wheatstone bridge circuit 721 of the load calculator 72 has the first strain sensor 721a that detects the first strain amount and the second strain sensor 721b that detects the second strain amount. Then, an example in which the load calculation unit 722 calculates the third strain amount based on the first strain amount detected by the first strain sensor 721a and the second strain amount detected by the second strain sensor 721b has been described. It is not limited to this.
  • the Wheatstone bridge circuit 721 of the load calculation unit 72 has only one of a first strain sensor 721a that detects the first strain amount and a second strain sensor 721b that detects the second strain amount. It may be a configuration.
  • the load calculation unit 722 calculates the third strain based on only one of the first strain amount detected by the first strain sensor 721a and the second strain amount detected by the second strain sensor 721b. A strain amount may be calculated.
  • a load sensor that detects a load, a housing (71) having a load surface (714a) for receiving a load, the load surface being deformed by receiving the load;
  • a direction along the load surface is defined as a first direction (DRx) and a direction along the load surface and a direction crossing the first direction is defined as a second direction (DRy)
  • the load applied to the load surface causes the
  • a first strain amount that is a strain amount in the first direction of a plurality of parts of the housing and a second strain that is a strain amount of a plurality of parts in the housing in the second direction.
  • a distortion detection unit (72) that detects at least one distortion amount among the amounts; Based on the amount of strain of at least one of the first strain amount of the plurality of portions and the second strain amount of the plurality of portions detected by the strain detection unit, the load surface is subjected to the strain amount.
  • a load sensor that detects a load, a housing (71) having a load surface (714a) for receiving a load, the load surface being deformed by receiving the load;
  • a direction along the load surface is defined as a first direction (DRx) and a direction along the load surface and a direction crossing the first direction is defined as a second direction (DRy)
  • the load applied to the load surface causes the
  • a first strain amount that is a strain amount in the first direction of a plurality of parts of the housing and a second strain that is a strain amount of a plurality of parts in the housing in the second direction.
  • the strain detection unit includes a plurality of first strain sensors (721a) that detect the first strain amounts of the plurality of parts and a plurality of second strain sensors (721b) that detect the second strain amounts of the plurality of parts.
  • the load calculation unit is configured to calculate the load based on the first strain amount of the plurality of parts detected by the plurality of first strain sensors and the second strain amount of the plurality of parts detected by the plurality of second strain sensors. and calculating a third strain amount that is a strain amount in the third direction of a plurality of parts of the housing, and obtaining the perpendicular load based on the calculated third strain amount of the plurality of parts.
  • Load sensor as described.
  • the housing has a low-rigidity portion (715a) that is more easily deformed than its surrounding portion when the load surface is deformed by receiving a load,
  • the plurality of first strain sensors and the plurality of second strain sensors are attached to the low-rigidity portion, and the electric resistance value changes according to the amount of strain when strained integrally with the low-rigidity portion.
  • the load sensor according to 3.
  • the low-rigidity portion is provided at a position overlapping with the load surface in the third direction, and the size in the third direction is formed to be smaller than a portion surrounding the low-rigidity portion.
  • the low-rigidity portion has a mounting surface (715c) extending along the direction in which the load surface extends,
  • the plurality of first strain sensors are provided on the mounting surface and detect the first strain amount on the mounting surface
  • the load sensor according to claim 5 wherein the plurality of second strain sensors are provided on the mounting surface and detect the second strain amount on the mounting surface.
  • a deformation emphasizing section (74) that increases the amount of deformation when the low-rigidity section deforms,
  • the deformation enhancing portion overlaps with the low-rigidity portion in the third direction when the direction in which the load surface is pressed in the third direction is the pressing direction, and the direction opposite to the pressing direction is the reaction force direction.
  • the housing has a hollow shape with a space (S) inside, and has an outer wall (711) surrounding the space, 8.
  • the load calculation unit calculates the first strain amount of the load applied to the load surface based on the first strain amount of the plurality of portions and the second strain amount of the plurality of portions detected by the strain detection unit.
  • the load sensor according to any one of claims 2 to 8, wherein a first load (Fx) applied in a direction and a second load (Fy) applied in the second direction are calculated.
  • [Claim 10] a load sensor according to any one of claims 1 to 9; a brake pedal (P); a brake rotor (R); friction materials (41, 51) that generate a braking force on the brake rotor; a piston (30) for pressing the friction material against the brake rotor; an electric motor (61) that outputs rotational force; It has a rotating shaft (631) that rotates about a rotation axis (SC) by the torque output from the electric motor, and converts the torque output from the electric motor so that the piston moves the friction material to the friction material.
  • a brake pedal P
  • R brake rotor
  • friction materials 41, 51
  • a piston for pressing the friction material against the brake rotor
  • an electric motor (61) that outputs rotational force
  • It has a rotating shaft (631) that rotates about a rotation axis (SC) by the torque output from the electric motor, and converts the torque output from the electric motor so that the piston moves the friction material to the friction material.
  • a target brake load which is a target load when the friction material presses the brake rotor, is determined based on the degree of opening of the brake pedal, and the rotational speed of the electric motor is adjusted based on the determined target brake load.
  • the control device determines a target rotation speed of the electric motor based on the target brake load determined when the brake pedal is operated, and determines a target rotation speed of the electric motor when the electric motor is rotated at the target rotation speed.
  • a difference between the perpendicular plane load obtained by the load sensor and the target brake load is calculated, and loss of the friction material is detected based on the calculated difference between the perpendicular plane load obtained by the load sensor and the target brake load.
  • the load sensor obtains the load applied in the first direction and the load applied in the second direction when the reaction force received by the load surface becomes an unbalanced load due to uneven wear of the friction material
  • the control device calculates the magnitude of the inclination of the surface of the friction material contacting the brake rotor with respect to the axial direction based on the load applied in the first direction and the load applied in the second direction determined by the load sensor.
  • the electric brake system according to any one of claims 9 to 12.
  • the housing has an annular shape with a through hole (73) extending along the third direction,
  • the load sensor has the rotating shaft inserted through the through hole, 14.
  • strain detector according to any one of claims 9 to 13, wherein the strain detector detects the first strain amount of a plurality of portions along the circumferential direction of the rotating shaft and the second strain amount of a plurality of portions of the housing.

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  • Braking Arrangements (AREA)

Abstract

L'invention concerne un capteur de charges permettant de détecter une charge et comprenant : un boîtier (71), dont une surface de charges (714a) permet de recevoir une charge et se déformant en la recevant; une unité de détection de distorsions (72) qui détecte, parmi un premier degré de distorsion, c'est-à-dire le degré de distorsion en une pluralité de sites selon une première direction (DRx), c'est-à-dire la direction suivant la surface de charges du boîtier, et un second degré de distorsion, c'est-à-dire le degré de distorsion en une pluralité de sites selon une deuxième direction (DRy), c'est-à-dire la direction suivant la surface de charges et croisant la première direction du boîtier, au moins l'un des degrés de distorsion, lorsque le boîtier est déformé en recevant la charge sur la surface de charges; et une unité de calcul de charges (722) qui calcule, parmi des charges reçues sur la surface de charges, une charge orthogonale en surface (Fz) appliquée selon une troisième direction (DRz) croisant la surface de charges, d'après ledit au moins un degré de distorsion au niveau de la pluralité de sites, parmi les premier et second degrés de distorsion au niveau de la pluralité de sites et détectés par l'unité de détection de distorsions.
PCT/JP2022/034641 2021-09-29 2022-09-15 Capteur de charges et système de freinage électrique WO2023054000A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP2021159815 2021-09-29
JP2021-159815 2021-09-29
JP2022-133460 2022-08-24
JP2022133460A JP2023050103A (ja) 2021-09-29 2022-08-24 荷重センサ、電動ブレーキシステム

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WO2023054000A1 true WO2023054000A1 (fr) 2023-04-06

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20140157906A1 (en) * 2012-12-11 2014-06-12 Goodrich Corporation Circular load cell strain sensor configuration
JP2015187483A (ja) * 2014-03-27 2015-10-29 Ntn株式会社 電動ブレーキ装置
JP2018205217A (ja) * 2017-06-07 2018-12-27 日立オートモティブシステムズ株式会社 荷重センサ

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20140157906A1 (en) * 2012-12-11 2014-06-12 Goodrich Corporation Circular load cell strain sensor configuration
JP2015187483A (ja) * 2014-03-27 2015-10-29 Ntn株式会社 電動ブレーキ装置
JP2018205217A (ja) * 2017-06-07 2018-12-27 日立オートモティブシステムズ株式会社 荷重センサ

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