JP5799941B2 - Electric braking device for vehicle - Google Patents

Description

  The present invention relates to an electric braking apparatus for a vehicle that drives an electric motor to apply braking force to wheels during vehicle braking.

  For example, the electric braking device for a vehicle described in Patent Document 1 transmits the rotational force of an electric motor (power transmission element) to a shaft member (spindle) via a reduction gear (gear unit) and is screwed to the shaft member. The pressing member (brake piston) is moved straight. Then, the friction member (brake pad) is pressed by the pressing member, and a braking force is generated between the friction member and the rotating member (brake disc), thereby generating a braking force on the wheel. In this electric braking device, the speed reducer and the electric motor are acoustically separated, and the electro-mechanical actuator can be reduced in size and weight.

  Moreover, the electric braking device for a vehicle described in Patent Document 2 has a configuration in which a spherical member is interposed between a nut and a pressing member screwed to a shaft member. The contact surface between the spherical member and the pressing member is formed into a spherical surface, and grease is filled between the contact surfaces. The rotational force of the electric motor is transmitted to the shaft member via the speed reducer, and the spherical member and the pressing member are caused to go straight through the nut screwed to the shaft member. Then, the friction member is pressed by the pressing member, and a braking force is generated between the friction member and the rotating member, thereby generating a braking force on the wheel. After releasing the braking force on the wheels, the electric motor is rotated in the reverse direction to make the spherical member free, and a gap is formed between the contact surfaces of the spherical member and the pressing member.

DE 10 2011 005 517 JP 2012-002316 A

  In the electric braking device for a vehicle described in Patent Document 1, the contact surface of the plate that contacts the shaft member is formed in a spherical shape like a universal ball joint. This plate (spherical member) is supported by a thrust bearing and rotates integrally with the rotational movement of the shaft member that transmits the power of the electric motor to the pressing member. For this reason, when the wear of the friction member increases and the shaft member is displaced, the contact surface of the spherical member always slides (slides) when the shaft member rotates.

  The relationship between the axial displacement of the shaft member and the sliding of the contact surface of the spherical member will be described with reference to FIG. Here, since one end of the shaft member SPD is formed in a spherical shape, it is assumed that the sphere BJT is fixed to the tip of the SPD. The spherical body BJT is slidably in contact with the spherical member PLT. When the friction member does not have uneven wear or the like and the shaft member SPD is not displaced, the shaft member SPD, the sphere BJT, and the spherical member PLT rotate coaxially about the rotation axis ktj. .

  When uneven wear or the like of the friction member occurs, the shaft member SPD has a rotating shaft direction difference (angle) with respect to the rotating shaft (original rotating shaft) ktj of the spherical member PLT while the electric motor is stationary. Deviation) occurs. That is, as shown in FIG. 5A, the relative positional relationship between the point A of the spherical member PLT and the shaft member SPD is in a state having an inclination angle θ1. Next, as shown in FIG. 5B, if the electric motor starts rotating and the spherical member PLT is rotated by 180 ° around the rotation axis ktj, the relative position between the shaft member SPD and the point A is determined. The relationship changes to the state of the tilt angle θ2.

  Since the shaft misalignment of the shaft member SPD is caused by uneven wear of the friction member, the direction of the shaft misalignment (the direction of the SPD with respect to the rotation axis ktj) is always the same direction (the direction that is fixed and does not change). For this reason, the relative positional relationship between the sphere BJT and the spherical member PLT changes from moment to moment as the spherical member PLT rotates. Therefore, when the electric motor rotates, the contact surface between the sphere BJT and the spherical member PLT always slides (slides). Although this contact surface is lubricated with grease or the like, depletion of the grease or the like on the contact surface may occur due to repeated sliding motion.

  Moreover, in this structure, since the above-mentioned sliding (sliding) has always occurred in the power transmission path, there may be a concern about a decrease in transmission efficiency. Furthermore, since it is necessary to rotate the sphere BJT and the spherical member PLT at the time of power transmission from the electric motor, the output of the electric motor is also consumed for these rotational movements. When braking suddenly, it is necessary to ensure the response of braking torque (that is, the response of the electric motor when the electric motor is rapidly increased from the state where the electric motor is stopped). Reduction of the member which performs is desired.

  On the other hand, in the electric braking device for a vehicle described in Patent Document 2, since the spherical member and the pressing member can swing on the spherical surface, the shaft member and the pressing member or the like can be swung (oscillating motion). The Therefore, even if the shaft displacement of the pressing member (corresponding to the shaft displacement of the shaft member described above) occurs, this shaft displacement can be absorbed. However, the conventional hydraulic braking device (for example, hydraulic brake caliper) In comparison, since new components such as an electric motor and a power transmission mechanism are added, it is desired to downsize each component.

  The present invention has been made in view of the above circumstances, and by ensuring the lubrication state of the spherical member, the smooth swinging motion of the pressing member and the like can be maintained, and the response during sudden braking is improved. An object of the present invention is to provide an electric braking device for a small vehicle.

  In order to solve the above-described problem, an electric braking device for a vehicle according to claim 1 includes a friction member (MSB) connected to a rotating member (KTB) fixed to a wheel (WHL) of the vehicle via an electric motor (MTR). In an electric braking device for a vehicle that generates a braking torque on the wheel (WHL), and includes any one of a nut-corresponding portion and a bolt-corresponding portion (NJB), and the friction member A pressing member (PSN) that applies a pressing force (Fba) to (MSB), a shaft member (SFT) that is rotationally driven by the electric motor (MTR) and screwed with the threaded portion (NJB), and the shaft member (SFT) is separated, and the shaft member (SFT) can rotate relative to the shaft member (SFT) around the rotation axis (sfj), and the end surface is a spherical surface (KJM1). The first spherical member (QM1) and the spherical surface (KJM1) of the first spherical member (QM1) are slidably contacted to receive the reaction force (reaction) of the pressing force (Fba), and the shaft member (SFT) ) With respect to the rotational axis (sfj) of the second spherical member (QM2).

  Here, the “nut equivalent part” is a “part corresponding to a nut”, and the “bolt equivalent part” is a “part corresponding to a bolt”. For example, when the screw portion (NJB) is caused by slip transmission, the “nut equivalent portion” is “female screw (also called inner screw)” and the “bolt equivalent portion” is “male screw (also called outer screw). .) ”. Further, when the threaded portion (NJB) is due to rolling transmission via a ball, the “nut equivalent portion” is “a nut with a ball groove (also simply referred to as a nut)” and “bolt equivalent portion”. Is a “ball grooved shaft (also called a screw shaft)”.

  According to a second aspect of the present invention, in the electric braking apparatus for a vehicle according to the first aspect, the shaft member (SFT) is brought into contact with the first spherical member (QM1) via a bearing (BRG). It is.

  The invention according to claim 3 is the electric braking device for a vehicle according to claim 1 or 2, further comprising a restraining member (KSB) fixed to the second spherical member (QM2), wherein the restraining member (KSB) is to constrain the movement of the first spherical member (QM1) in the axis (sfj) direction of the shaft member.

  According to a fourth aspect of the present invention, in the electric braking device for a vehicle according to any one of the first to third aspects, the first spherical member (QM1) has a convex spherical surface (KJM1) as the spherical surface. The second spherical member (QM2) has a concave spherical surface (KJM2) that comes into sliding contact with the convex spherical surface (KJM1).

  According to a fifth aspect of the present invention, in the electric braking apparatus for a vehicle according to any one of the first to fourth aspects, the center of the spherical surface (KJM1, KJM2) is the rotation member (KTB) and the It exists in a contact surface with a friction member (MSB).

  According to a sixth aspect of the present invention, in the electric braking apparatus for a vehicle according to any one of the first to fifth aspects, the first spherical member (QM1) and the second spherical member (QM2) are A through hole (KA1, KA2) is provided at the center, and power from the electric motor (MTR) is transmitted to the shaft member (SFT) through the through holes (KA1, KA2).

  According to the first aspect of the present invention, the second spherical member (QM2) is constrained from rotating with respect to the rotation axis (sfj) of the shaft member (SFT). Furthermore, since the first spherical member (QM1) that contacts the second spherical member (QM2) while sliding is separated from the rotating shaft member (SFT), in relation to the shaft member (SFT), The shaft member can freely rotate around the rotation axis (sfj) of the shaft member. For this reason, when the shaft member (SFT) rotates, the first spherical member (QM1) is kept still or is slightly rotated. Even if the actual rotational axis (sfj) is inclined with respect to the original rotational axis (ktj) in the shaft member (SFT) due to the axial displacement of the shaft member (SFT), the first spherical member (QM1) is Even if it does not rotate around the rotation axis (sfj) of the shaft member, it is slight even if it rotates. As a result, the repeated sliding motion accompanying the rotation of the electric motor (MTR) is reduced, and a reliable lubricating state can be maintained. In addition, a reduction in power transmission efficiency due to sliding (sliding) can be suppressed. In addition, since the rotational movement of the first and second spherical members (QM1, QM2) is prevented or suppressed, the responsiveness of the electric motor MTR at the time of sudden braking can be improved, and the responsiveness of the braking torque increase can be ensured. .

  In the power transmission path, spherical sliding contact surfaces (KJM1 and KJM2 which are contact surfaces between QM1 and QM2) for absorbing shaft misalignment are on the electric motor (MTR) side with respect to the threaded portion (NJB). In the arrangement of the first spherical member (QM1), in addition to the movement in the pressing direction (direction of the shaft member axis (sfj)), the rotation direction (the rotation direction about the axis (sfj) of the shaft member). ) Is given. According to the invention of claim 2, since the first spherical member (QM1) is brought into contact with the shaft member (SFT) via the bearing (BRG), the shaft member (SFT) can be smoothly rotated. . As a result, the power transmission efficiency from the electric motor (MTR) to the pressing member (PSN) can be ensured satisfactorily.

  According to the invention of claim 3, the first spherical member (QM1) and the second spherical member (QM2) are not only rotated in the rotation direction but also in the axis (sfj) direction of the shaft member by the restraining member (KSB). Since the relative movement (mutual position between QM1 and QM2) is constrained, the contact posture of the first spherical member (QM1) with respect to the second spherical member QM2 is properly maintained. That is, the axis of the first spherical member (QM1) and the axis of the second spherical member (QM2) do not tilt more than necessary. As a result, it can be suppressed that the swing function (swing function) of the shaft member (SFT) is impaired.

  According to the invention of claim 4, since the first spherical member (QM1) is a convex spherical surface (KJM1) and the second spherical member (QM2) is a concave spherical surface (KJM2), the pressing member (PSN) When a pressing force (Fba) is applied to QM1 and QM2, the force acts toward the center along the slope of the spherical surface (KJM1, KJM2). That is, since the spherical surfaces (KJM1, KJM2) have the effect of self-centering, the positional relationship between the first spherical member (QM1) and the second spherical member (QM2) can be properly maintained. As a result, the shaft misalignment of the shaft member (SFT) can be properly absorbed.

  Due to uneven wear of the friction member (MSB) or the like, the contact between the rotating member (KTB) and the friction member (MSB) becomes a base point, and the shaft member (SFT) is displaced (eccentric between the two shafts). According to the invention of claim 5, since the center of the spherical surface (KJM1, KJM2) of the first and second spherical members (QM1, QM2) is the position of the base point (point O), the shaft member (SFT) ) Can be effectively absorbed.

  According to the sixth aspect of the present invention, the through hole (KA1) is provided at the center of the first spherical member (QM1), and the through hole (KA2) is provided at the center of the second spherical member (QM2). . Power (torque) from the electric motor (MTR) is transmitted by the shaft member (SFT) through these two through holes (KA1, KA2). For example, it can be considered that a counter shaft is provided separately, and the rotational movement of the electric motor is transmitted to the shaft member via the counter shaft, but the configuration is simplified compared to such a case, The whole can be compact.

1 is a diagram illustrating an overall configuration of an electric braking device for a vehicle according to an embodiment of the present invention. It is a fragmentary sectional view which shows the 1st embodiment of the rotation / linear motion conversion mechanism of an electric brake device. It is a fragmentary sectional view which shows the 1st, 2nd spherical member of FIG. 2, and pressing force acquisition means. It is a fragmentary sectional view which shows the 2nd embodiment of the rotation / linear motion conversion mechanism of an electric brake device. It is a figure for demonstrating the problem of the axial shift | offset | difference of the shaft member by the uneven wear etc. of a friction member.

<Overall configuration of electric braking device for vehicle>
An overall configuration of an electric braking device for a vehicle according to an embodiment of the present invention will be described with reference to FIG. As shown in FIG. 1, the electric braking device for a vehicle adjusts the braking torque of a braking operation member (for example, a brake pedal) BP and a wheel WHL that a driver operates to decelerate the vehicle, and applies braking force to the wheel WHL. Electric brake means (electric brake actuator) BRK, an electronic control unit ECU for controlling the BRK, and a storage battery BAT as a power source for supplying electric power to the ECU and the like. In the ECU, control means (control algorithm) CTL for controlling BRK is programmed.

  The vehicle is also provided with a braking operation amount acquisition means BPA for detecting an operation amount (braking operation amount) Bpa of the braking operation member BP. For example, the BPA is a sensor (pressure sensor) that detects the pressure of a master cylinder (not shown), an operation force of the braking operation member BP, and / or a sensor (stepping force sensor, stroke sensor) that detects a displacement amount. Is at least one of these. Accordingly, the braking operation amount Bpa is calculated based on at least one of the master cylinder pressure, the brake pedal depression force, and the brake pedal stroke.

[Electric braking means BRK]
The electric brake means BRK includes a floating brake caliper CPR, a rotary member KTB, a friction member MSB, an electric motor MTR, a motor drive circuit DRV, a reduction gear GSK, a rotation / linear motion conversion mechanism HNK, an energization amount acquisition means IMA, and a position acquisition. Means MKA and pressing force acquisition means FBA are provided.

  For example, the rotating member KTB is a brake disk, the friction member MSB is a brake pad, and the electric motor MTR is a brush motor or a brushless motor.

  The reduction gear GSK decelerates the rotation output (torque) of the electric motor MTR and transmits it to the rotation / linear motion conversion mechanism HNK. As the reduction gear GSK, at least one of a gear transmission mechanism (spur gear, helical gear, etc.), a winding transmission mechanism (belt, chain, etc.), and a friction transmission mechanism can be used. The output member of the reduction gear GSK becomes the input member INP to the rotation / linear motion conversion mechanism HNK, and the power of the electric motor MTR is input (transmitted) from the GSK to the HNK.

  The rotation / linear motion conversion mechanism HNK is a mechanism that converts rotational motion into linear motion, and includes a shaft member SFT and a pressing member (for example, a brake piston) PSN. The shaft member SFT and the pressing member PSN have screw portions NJB that are screwed together. That is, the shaft member SFT having the threaded portion NJB is rotationally driven by the input member INP, and the pressing member PSN having the threaded portion NJB screwed with the shaft member SFT moves forward or backward with respect to the rotating member KTB (for example, a brake disk). To do. Then, the friction member (for example, brake pad) MSB is pressed by the pressing member PSN and pressed against the rotating member KTB. For example, the screw portion NJB of the rotation / linear motion conversion mechanism HNK is configured by a sliding screw (such as a trapezoidal screw) that transmits power by “sliding”. In this case, the “screw portion corresponding to the nut” corresponds to “female screw (also referred to as inner screw)”, and “the screw portion corresponding to the bolt” corresponds to “male screw (also referred to as outer screw)”. Further, a ball screw (ball screw or the like) in which power is transmitted by “rolling” may be employed for the screw portion NJB of HNK. In this case, “the thread portion of the nut equivalent portion” corresponds to “the ball groove of the nut”, and “the screw portion of the bolt equivalent portion” is “the ball groove of the screw shaft (which is screwed into the nut via the ball)”. ".

  The motor drive circuit DRV controls the energization amount (finally the current value) to the electric motor MTR based on the target energization amount (target value) Imt commanded from the control means CTL. Specifically, the motor drive circuit DRV includes a bridge circuit using a switching element (a power transistor, for example, a MOS-FET), and the switching element is driven based on the target energization amount Imt. The output (output torque) of the electric motor MTR is controlled. That is, the rotation direction and the output torque of the electric motor MTR are adjusted by switching the energization / non-energization state of the switching element.

  The energization amount acquisition means (for example, current sensor) IMA is provided in the motor drive circuit DRV in order to detect an actual energization amount (for example, current that actually flows through the electric motor MTR) Ima. The position acquisition means (for example, angle sensor) MKA is provided in the electric motor MTR in order to detect the position (for example, rotation angle) Mka of the rotor of the MTR. A pressing force acquisition means (for example, a pressing force sensor) FBA is provided in the rotation / linear motion conversion mechanism HNK in order to detect a force (actual value of pressing force) Fba by which the friction member MSB actually presses the rotating member KTB. ing.

  According to the electric braking means (electric brake actuator) BRK configured as described above, the output of the electric motor MTR is transmitted to the rotation / linear motion conversion mechanism HNK via the reduction gear GSK and the input member INP. . Accordingly, the pressing member (brake piston) PSN moves forward toward the rotating member (brake disc) KTB. Then, when the pressing member PSN presses the friction member (brake pad) MSB toward the rotating member KTB, the friction member MSB is pressed against the rotating member KTB. Since rotating member KTB is fixed to wheel WHL, a frictional force is generated between friction member MSB and rotating member KTB, and a braking force is generated on wheel WHL.

[Control means CTL]
The control means CTL includes a target pressing force calculation block FBT, an instruction energization amount calculation block IST, a pressing force feedback control block IPT, and an energization amount adjustment calculation block IMT. The control means (control program) CTL is programmed in the electronic control unit ECU.

  The target pressing force calculation block FBT calculates the target pressing force Fbt of each wheel WHL using a preset target pressing force calculation characteristic (calculation map) CHfb based on the braking operation amount Bpa. Fbt is a target value of the pressing force with which the friction member (brake pad) MSB presses the rotating member (brake disc) KTB in the electric braking means BRK.

  The command energization amount calculation block IST calculates the command energization amount Ist based on the target pressing force Fbt using preset command energization amount calculation characteristics (calculation maps) CHs1 and CHs2. Ist is a target value of the energization amount to the electric motor MTR for driving the electric motor MTR of the electric braking means BRK and achieving the target pressing force Fbt. The calculation map of Ist is composed of two characteristics CHs1 and CHs2 in consideration of the hysteresis of the electric braking means BRK. The characteristic CHs1 corresponds to the case where the pressing force is increased, and the characteristic CHs2 corresponds to the case where the pressing force is decreased. Therefore, compared with the characteristic CHs2, the characteristic CHs1 is set to output a relatively large command energization amount Ist.

  Here, the energization amount is a state amount (variable) for controlling the output torque of the electric motor MTR. Since the electric motor MTR outputs a torque substantially proportional to the current, the current target value of the electric motor MTR can be used as the target value of the energization amount. Further, if the supply voltage to the electric motor MTR is increased, the current is increased as a result, so that the supply voltage value can be used as the target energization amount. Furthermore, since the supply voltage value can be adjusted by the duty ratio in pulse width modulation (PWM), this duty ratio can be used as the energization amount.

  The pressing force feedback control block IPT calculates the pressing force feedback energization amount Ipt based on the target pressing force (target value) Fbt and the actual pressing force (actual value) Fba. The command energization amount Ist is calculated as a value corresponding to the target pressing force Fbt, but an error (steady error) occurs between the target pressing force Fbt and the actual pressing force Fba due to the efficiency variation of the electric braking means BRK. There is. The pressing force feedback energization amount Ipt is calculated based on a deviation (pressing force deviation) ΔFb between the target pressing force Fbt and the actual pressing force Fba and a calculation characteristic (calculation map) CHp so as to reduce the above error. It is determined. The actual pressing force Fba is acquired (detected) by a pressing force acquisition unit FBA described later.

  The energization amount adjustment calculation block IMT calculates a target energization amount Imt that is a final target value for the electric motor MTR. The command energization amount Ist is adjusted by the pressing force feedback energization amount Ipt, and the target energization amount Imt is calculated. Specifically, the energization amount adjustment calculation block IMT adds the feedback energization amount Ipt to the command energization amount Ist and calculates the target energization amount Imt. The target energization amount Imt is a final energization target value for controlling the output of the electric motor MTR, and is calculated based on the FBA detection result (Fba). Then, the rotation direction (forward or reverse direction) of the electric motor MTR is determined based on the sign of the target energization amount Imt (positive or negative value), and the output of the electric motor MTR is determined based on the magnitude of the target energization amount Imt. Is controlled.

<First embodiment of rotation / linear motion conversion mechanism HNK of electric braking means BRK>
A first embodiment of the rotation / linear motion conversion mechanism HNK of the electric braking means BRK will be described with reference to FIG. As shown in FIG. 2, the rotation / linear motion conversion mechanism HNK1 includes a pressing member PSN, a shaft member SFT, a first spherical member QM1, a second spherical member QM2, a bearing BRG, a restraining member KSB, a holding member SPT, and the like. It is prepared for. A part of the constituent members of the rotation / linear motion conversion mechanism HNK1 also serves as the pressing force acquisition means FBA.

  The pressing member (piston) PSN presses the friction member MSB against the rotating member KTB to generate a frictional force. The movement of the pressing member PSN relative to the brake caliper (floating caliper) CPR is limited by the key member KYA and the key groove KYM. A key groove KYM is formed in the brake caliper CPR so as to extend in the direction of the rotation axis ktj (hereinafter referred to as the input shaft ktj) of the input member INP. Then, the key member KYA fixed to the pressing member PSN is fitted into the key groove KYM. Therefore, the pressing member PSN is restricted from rotating around the input shaft ktj, and is allowed to move linearly in the direction of the input shaft ktj (key groove KYM direction). Here, the input member INP is a structural member that transmits (inputs) the torque output (rotational output) of the electric motor MTR transmitted through the reduction gear GSK to the shaft member SFT.

  The shaft member SFT is rotationally driven around the axis of INP (centered around ktj) by the input member INP, and transmits a torque output (rotational output) generated by the electric motor MTR to the pressing member PSN. The shaft member SFT is inserted into the through hole KA1 of the first spherical member QM1 and the through hole KA2 of the second spherical member QM2. That is, the input member INP, the shaft member SFT, the first spherical member QM1, and the second spherical member QM2 are configured coaxially. When there is no axial deviation, the rotation axis sfj of the shaft member SFT (hereinafter referred to as the shaft axis sfj) coincides with the rotation axis of the input member INP (input axis ktj). However, the deflection (brake caliper) CPR of the brake caliper, the uneven wear of the friction member MSB, etc. cause the shaft member SFT to oscillate (oscillate), resulting in eccentricity (axial misalignment) between the two shafts (ktj and sfj). obtain. The first spherical member QM1 and the second spherical member QM2 absorb this axial deviation (for example, change in angle) and transmit the rotational force. In other words, the first spherical member QM1 and the second spherical member QM2 are paired to exhibit the function of a universal joint.

  The pressing member PSN is provided with a male screw portion (also referred to as an outer screw portion, corresponding to a “bolt equivalent portion”) ONJ that can be screwed together. The shaft member SFT is provided with a female screw portion (also referred to as an inner screw portion, corresponding to a “nut equivalent portion”) MNJ that meshes with the male screw portion ONJ. In the threaded portion NJB where the female threaded portion MNJ of the shaft member SFT and the male threaded portion ONJ of the pressing member PSN are screwed together, the rotational motion (torque) of the shaft member SFT is converted into the linear motion (thrust) of the pressing member PSN. The

  A bearing (for example, between the flat surface HM1 of the shaft member SFT and the flat surface HM1 of the first spherical member QM1 (the back surface of KJM1, which will be described later) is located on the opposite side to the pressing member PSN side with respect to the screw portion NJB. Thrust bearing) BRG is provided. The bearing BRG reduces friction (resistance) in the rotational direction, and smoothes the relative rotational movement between the shaft member SFT and the first spherical member QM1. Since power loss due to friction is reduced by the bearing BRG, highly efficient power transmission from the electric motor MTR to the pressing member PSN can be ensured. Note that the bearing BRG can be omitted. In this case, a surface treatment (for example, a contact surface between the SHM and the HM1) for reducing friction is applied to the contact end surface between the shaft member SFT and the first spherical member QM1 (for example, , Teflon coating) can be applied.

  The restraining member KSB is fixed to the second spherical member QM2, and restricts the movement of the first spherical member QM1 in the direction of the shaft axis sfj (the left-right direction on the paper surface). Specifically, a gap (space) is formed between the restraining member KSB and the second spherical member QM2, and the first spherical member QM1 is provided in this gap. For this reason, QM1 can move only within the gap between KSB and QM2. Here, even if the input shaft (INP rotation shaft) ktj and the shaft shaft (SFT rotation shaft) sfj are decentered (shaft misalignment), the angle is slight, so in the movement of QM1, ktj The direction and the sfj direction are equivalent.

  The pressing force acquisition unit FBA includes a strain detection element (for example, strain gauge) HZM, an arithmetic processing unit (for example, arithmetic circuit) ENZ, and a lead wire (detection signal line) LDS. Reaction of pressing force) Fba is detected. The strain detection element HZM is bonded to the plane HM2 (the back surface of KJM2 described later) of the second spherical member QM2. The distortion amount (signal) Hzm detected by the HZM is transmitted to the arithmetic processing unit ENZ via the lead wire LDS. In ENZ, Fba is calculated based on Hzm.

  The holding member SPT holds the pressing force acquisition means FBA (particularly the arithmetic processing unit ENZ), the second spherical member QM2, and the restraining member KSB. The holding member SPT is fixed to the brake caliper CPR. Therefore, the pressing force acquisition means FBA, the second spherical member QM2, and the restraining member KSB are fixed to the brake caliper CPR. The holding member SPT can be omitted, and in this case, the pressing force acquisition means FBA (particularly the arithmetic processing unit ENZ), the second spherical member QM2, and the restraining member KSB can be directly fixed to the brake caliper CPR. .

  Next, details of the first spherical member QM1, the second spherical member QM2, the restraining member KSB, and the pressing force acquisition means FBA will be described with reference to FIG.

  As shown in FIG. 3, the first spherical member QM1 has one disk-shaped end surface formed on a convex spherical surface (convex spherical surface) KJM1, and the other end surface formed on a flat surface HM1. The first spherical member QM1 slides on the convex spherical surface KJM1 with the concave spherical surface (concave spherical surface) KJM2 of the second spherical member QM2. When the first spherical member QM1 and the second spherical member QM2 slide (slide), the universal joint function is exhibited, and the shaft member SFT can be allowed to be displaced. The plane HM1 (back side surface of KJM1) of the first spherical member QM1 receives a reaction force (reaction) of the pressing force Fba applied from the shaft member SFT (plane SHM perpendicular to sfj), and the reaction force is a convex spherical surface. It is transmitted to the second spherical member QM2 via KJM1. A through hole KA1 is formed in the center of the first spherical member QM1, and the shaft member SFT is penetrated. Further, HM1 receives a reaction force of pressing force (force from PSN) from the plane SHM perpendicular to the rotation axis (shaft axis sfj) of the SFT via the bearing BRG, and is pressed against the plane SHM. Here, the plane SHM is a plane provided on the opposite side to the pressing member PSN with respect to the threaded portion NJB in the shaft member SFT.

  The second spherical member QM2 has one disc-shaped end surface formed as a concave spherical surface KJM2, and the other end surface formed as a plane HM2. The second spherical member QM2 is fixed to the brake caliper CPR. That is, the second spherical member QM2 is not rotated about the input axis ktj or the shaft axis sfj. Further, the second spherical member QM2 is not moved (linearly moved) in either the input axis ktj direction or the shaft axis sfj direction. The second spherical member QM2 slides with the convex spherical surface KJM1 of the first spherical member QM1 on the concave spherical surface KJM2, and receives the reaction force of the pressing force Fba from the first spherical member QM1 on the concave spherical surface KJM2. A strain detection element HZM is attached to the plane HM2 (back side surface of KJM2) of the second spherical member QM2, and the distortion (shape change with respect to force) Hzm of the second spherical member QM2 is measured by this HZM. The pressing force Fba is detected based on the strain Hzm generated by the reaction force of the pressing force. A through hole KA2 is formed at the center of the second spherical member QM2, and the shaft member SFT is penetrated.

  The restraining member KSB is fixed to the second spherical member QM2, and forms a gap (space) between the restraining member KSB and the second spherical member QM2. The first spherical member QM1 is provided in this gap. The restraint member KSB restricts the movement of the first spherical member QM1 in the direction of the shaft axis sfj (also referred to as “movement in the direction of the input axis ktj”). Contact between the rotating member KTB and the friction member MSB becomes a base point (point O), and an axial displacement between the input member INP and the shaft member SFT occurs. This axial misalignment is absorbed by the inclination (sliding) between the first spherical member QM1 and the second spherical member QM2, but it is necessary to absorb the misalignment in the shaft axis sfj direction of the QM1 (input shaft ktj). The amount of movement in the direction is slight. In other words, it is necessary for the QM1 to incline to allow the axial deviation, but the axial displacement of the QM1 generated thereby is small. For this reason, the restraining member KSB allows a slight movement amount Δd in the axial direction to the extent necessary for absorbing the axial deviation, but restricts the movement amount beyond that. That is, the restraining member KSB prevents the first spherical member QM1 from being tilted more than necessary and the first spherical member so that the contact posture of the first spherical member QM1 with respect to the second spherical member QM2 is always appropriate. Restrain the position of QM1.

  Further, the radius R of the convex and concave spherical surfaces KJM1 and KJM2 of the first and second spherical members QM1 and QM2 is the contact between the convex and concave spherical surfaces KJM1 and KJM2 on the ktj and between the rotating member KTB and the friction member MSB. It is set approximately equal to the distance to the surface. That is, the radius R of the spherical surface is determined so that the centers of the spherical surfaces KJM1 and KJM2 exist on the contact surface between the rotating member KTB and the friction member MSB. The shaft member SFT is displaced (oscillating motion of the rotation center axis) with the contact between the rotating member KTB and the friction member MSB as a base point (point O). By properly determining the radius R of KJM1 and KJM2, absorption of axial deviation can be effectively performed. In addition, since the dimension of each structural member (PSN etc.) of the electric braking means BRK is known, the spherical surface radius R is determined based on these dimensions.

  The pressing force acquisition means (for example, force sensor) FBA includes a strain detection element HZM, an arithmetic processing unit ENZ, and a lead wire LDS, and detects the pressing force (reaction force of pressing force) Fba of the pressing member PSN. The strain detection element HZM is configured as a Wheatstone bridge circuit, and a pair of strain detection elements HZM are attached to the plane HM2 opposite to the KJM2 of the second spherical member QM2 with a 180 degree separation, and the strain ( Displacement against force) Hzm is detected. For example, as the strain detection element HZM, a device using a change in electrical resistance (strain gauge), a device using ultrasonic waves, or the like can be used. The strain Hzm detected by the pair of strain detection elements HZM is transmitted to the arithmetic processing unit ENZ via the lead wire LDS. The arithmetic processing unit ENZ is an arithmetic circuit including a program, and an arithmetic mean value of two strains Hzm transmitted from the pair of strain detection elements HZM and a preset characteristic (calculation map, for example, The pressing force Fba is calculated based on the calibration value. The pressing force Fba is transmitted to the electronic control unit ECU via the wiring (wire harness) WRH and used to control the electric motor MTR.

  According to the electric braking means BRK provided with the rotation / linear motion conversion mechanism HNK1 having the above-described configuration, the output torque (rotational force) of the electric motor MTR is transmitted as the rotational motion of the shaft member SFT via the reduction gear GSK. The The rotational motion of the shaft member SFT is converted into a linear motion of the pressing member PSN (forward / reverse motion with respect to the rotational member KTB) by the rotation / linear motion conversion mechanism HNK1. Specifically, a portion (nut equivalent portion) MNJ in which a female screw (inner screw) provided in the shaft member SFT is formed, and a male screw (outer screw) provided in the pressing member PSN to be screwed therewith are formed. Power is converted by the part (bolt equivalent) ONJ. The friction member MSB is pressed against the rotating member KTB by the pressing member PSN to generate a pressing force Fba, and a braking force is generated on the wheel WHL.

  As described above, according to the present embodiment, the second spherical member QM2 is fixed to the brake caliper CRP, and the rotational movement of the shaft member SFT relative to the shaft axis sfj is restricted. Furthermore, the first spherical member QM1 that contacts the second spherical member QM2 while sliding is a member separate from the rotating shaft member SFT and is separated from each other. For this reason, the first spherical member QM1 can freely rotate around the shaft axis sfj in relation to the shaft member SFT. Since the convex and concave spherical surfaces KJM1 and KJM2 of the first and second spherical members QM1 and QM2 are disposed on the electric motor MTR side with respect to the screw portion NJB, the first spherical member QM1 has a pressing direction (shaft shaft). In addition to the movement in the sfj direction), the movement in the rotation direction (around the shaft axis sfj) is given, but since the shaft member SFT and the first spherical member QM1 are separate members, the shaft member SFT is rotated. Even so, the first spherical member QM1 is maintained stationary or slightly rotated. That is, even when the shaft member SFT is displaced due to the MSB uneven wear or the like and the shaft axis sfj is inclined with respect to the input shaft ktj (that is, when the shaft displacement occurs), the first spherical member QM1 is not rotated around the shaft axis sfj or is slight even if it is rotated. As a result, repeated sliding movements accompanying the rotation of the electric motor MTR are reduced, grease breakage is suppressed, and a reliable lubricating state can be maintained. In addition, a reduction in power transmission efficiency due to sliding (sliding) can be suppressed. In addition, since the rotational movement of the first and second spherical members QM1, QM2 is prevented or suppressed, the power loss of the electric motor MTR can be reduced, and the response of the braking torque increase during sudden braking can be ensured.

  Further, the first spherical member QM1 is in contact with the shaft member SFT via a bearing BGR. Specifically, between the plane SHM of the shaft member SFT (a plane opposite to the PSN side with respect to NJB and perpendicular to sfj) and the plane HM1 of the first spherical member QM1 (the back side of KJM1) Is provided with a bearing (for example, a thrust bearing) BRG. For this reason, the shaft member SFT can be smoothly rotated with respect to the first spherical member QM1, and the stationary state of the QM1 can be generally maintained. As a result, a reliable lubricating state can be maintained and the efficiency of power transmission from the electric motor MTR to the pressing member PSN can be ensured satisfactorily.

  Also, the relative movement in the shaft axis sfj direction (the left-right direction of the drawing) between the first spherical member QM1 and the second spherical member QM2 by the restraining member KSB fixed to the second spherical member QM2 (“input shaft ktj”). "Movement in the direction") is restrained. Specifically, QM1 is installed in a space (gap) formed by QM2 and KSB. For this reason, the amount of movement caused by the inclination of QM1 necessary for absorbing the axial deviation is allowed, but the amount of movement beyond that is limited. As a result, the contact posture of the first spherical member QM1 with respect to the second spherical member QM2 is properly maintained and does not tilt unnecessarily, so that the swing function (swing function) can be prevented from being impaired.

  Since the first spherical member QM1 is a convex spherical surface KJM1 and the second spherical member QM2 is a concave spherical surface KJM2, a reaction force from the pressing member PSN (that is, a reaction of the pressing force Fba) is applied to QM1 and QM2. In this case, the force acts toward the central direction (ktj direction) along the slopes of the convex and concave spherical surfaces KJM1 and KJM2 of the first and second spherical members QM1 and QM2. For this reason, the first spherical member QM1 is moved so that its central axis is directed to ktj. That is, since there is an effect of self-centering, the positional relationship between the first spherical member QM1 and the second spherical member QM2 can be properly maintained.

  The centers of the convex spherical surface KJM1 and the concave spherical surface KJM2 are set to be on the contact surface between the rotating member KTB and the friction member MSB. That is, the radius R of KJM1 and KJM2 is determined to be equal to the distance from KJM1 and KJM2 to the contact surface between KTB and MSB at ktj. The contact between the rotating member KTB and the friction member MSB, such as uneven wear of the friction member MSB, becomes a base point (point O), and shaft misalignment of the shaft member SFT (difference between ktj and sfj) occurs. Since the centers of the convex and concave spherical surfaces KJM1 and KJM2 of the two spherical members QM1 and QM2 are at appropriate positions (point O on ktj on the contact surface between KTB and MSB), the shaft member SFT is effectively displaced. Can be absorbed.

  A through hole KA1 is provided at the center of the first spherical member QM1, and a through hole KA2 is provided at the center of the second spherical member QM2. The power from the electric motor MTR passes through the two through holes KA1 and KA2. (Torque) is transmitted to the shaft member SFT. Although it is conceivable that a counter shaft is provided separately and the rotational motion of the electric motor MTR is transmitted to the shaft member SFT via the counter shaft, the configuration is simplified compared to such a case, and the device The whole can be compact.

<Second embodiment of rotation / linear motion conversion mechanism HNK of electric braking means BRK>
A second embodiment of the rotation / linear motion conversion mechanism HNK of the electric braking means BRK will be described with reference to FIG. 4 corresponding to FIG. In FIG. 4, constituent members having the same functions as those shown in FIG. 2 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the rotation / linear motion conversion mechanism HNK1 of the first embodiment shown in FIG. 2, the male screw portion ONJ is provided on the pressing member PSN and the female screw portion MNJ is provided on the shaft member SFT, whereas the second embodiment shown in FIG. In the rotation / linear motion conversion mechanism HNK2, the nut NUT fitted into the pressing member PSN is provided with a female thread portion (nut equivalent portion) MNJ, and the shaft member SFT is provided with a male screw portion (bolt equivalent portion) ONJ. . The nut NUT is fixed to the pressing member PSN, and when the shaft member SFT is rotated, the pressing member PSN is advanced / retreated relative to the rotating member KTB.

  The holding member SPT provided in the rotation / linear motion conversion mechanism HNK1 of the first embodiment is omitted in the rotation / linear motion conversion mechanism HNK2 of the second embodiment, and the pressing force acquisition means FBA (particularly arithmetic processing) Part ENZ), the second spherical member QM2, and the restraining member KSB are directly fixed to the brake caliper CPR.

  According to the electric braking means BRK provided with the rotation / linear motion conversion mechanism HNK2 of the second embodiment, the same operation and effect as the electric braking means BRK provided with the rotation / linear motion conversion mechanism HNK1 of the first embodiment are obtained. Play.

  As described above, the case where the sliding screw such as the trapezoidal screw is adopted as the screw portion NJB of the rotation / linear motion conversion mechanism HNK has been described. However, a rolling screw such as a ball screw can be adopted instead of the sliding screw. In this case, the female screw part MNJ can be replaced with a “(ball grooved) nut” and the male screw part can be replaced with a “(ball grooved) screw shaft”. A plurality of balls are arranged in the respective ball grooves, and the rotational motion is converted into linear motion. Even when a rolling screw is used, the same operations and effects as described above are obtained.

BRK ... electric braking means, CTL ... control means, CPR ... brake caliper, KTB ... rotating member, MSB ... friction member, MTR ... electric motor, PSN ... pressing member, SFT ... shaft member, ONJ ... male screw part, MNJ ... female screw part , NJB ... threaded portion, QM1 ... first spherical member, KJM1 ... convex spherical surface, HM1 ... plane, KA1 ... through hole, QM2 ... second spherical member, KJM2 ... concave spherical surface, HM2 ... flat surface, KA2 ... through hole, KSB: restraining member, FBA: pressing force acquisition means, HZM: strain detecting element, LDS ... lead wire, ENZ ... arithmetic processing unit, WRH ... wiring, SPT ... holding member

Claims (6)

In an electric braking device for a vehicle that presses a friction member to a rotating member fixed to a wheel of the vehicle via an electric motor and generates a braking torque on the wheel.
A pressing member that has a screw portion of any one of a nut equivalent portion and a bolt equivalent portion, and applies a pressing force to the friction member;
A shaft member that is rotationally driven by the electric motor and screwed with the screw portion;
A first spherical member separated from the shaft member, capable of rotating relative to the shaft member around a rotation axis of the shaft member, and having a spherical end surface;
An electric braking device for a vehicle, comprising: a second spherical member that is in sliding contact with the spherical surface of the first spherical member, receives a reaction force of the pressing force, and is constrained to rotate with respect to a rotation axis of the shaft member. . The electric braking device for a vehicle according to claim 1,
The electric braking device for a vehicle, wherein the shaft member is in contact with the first spherical member via a bearing. The electric braking device for a vehicle according to claim 1 or 2,
A restraining member fixed to the second spherical member;
The restraining member is an electric braking device for a vehicle that restrains the axial movement of the shaft member of the first spherical member. The electric braking device for a vehicle according to any one of claims 1 to 3,
The first spherical member has a convex spherical surface as the spherical surface,
The electric braking device for a vehicle, wherein the second spherical member has a concave spherical surface that is in sliding contact with the convex spherical surface. The electric braking device for a vehicle according to any one of claims 1 to 4,
The electric braking device for a vehicle, wherein a center of the spherical surface is on a contact surface between the rotating member and the friction member. The electric braking device for a vehicle according to any one of claims 1 to 5,
The electric braking device for a vehicle, wherein the first spherical member and the second spherical member have a through hole in the center, and power from the electric motor is transmitted to the shaft member through the through hole.

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