Electric braking device

Abstract

The electric braking system can be miniaturized while suppressing the engagement of the locking mechanism with the ratchet gear when the vehicle is not parked. [Solution] The electric braking device (BRK) includes an actuator (SOL) that drives a locking portion (LKP) in an approaching direction (Dts) toward the ratchet gear (RCH) and an awaying direction (Dtr) toward the ratchet gear (RCH), an elastic member (SPR) that biases the locking portion (LKP) in the awaying direction (Dtr), and a damper mechanism (DMP) that applies greater resistance to the locking portion (LKP) the faster it tries to move in the approaching direction (Dts).

Description

Technical Field

[0001] The present disclosure relates to an electric brake device.

Background Art

[0002] Patent Document 1 discloses an electric brake device including a ratchet gear attached to the motor shaft of an electric motor, a locking pin that engages with the ratchet gear, a mounting seat that guides the locking pin, a solenoid that presses the locking pin, and a spring for pulling back the locking pin.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of Invention

Problem to be Solved by the Invention

[0004] In conventional electric brake devices, the force of the spring that pulls back the locking pin tends to be set large so that the locking portion such as the locking pin does not engage with the ratchet gear due to externally input vibrations or the like during non-parking periods. The larger the force of the spring that pulls back the locking portion, the greater the force required for the solenoid to press the locking portion to engage the locking portion with the ratchet gear, which hinders miniaturization of the electric brake device. An aspect of the present disclosure aims to miniaturize the electric brake device while suppressing the locking portion from engaging with the ratchet gear during non-parking periods.

Means for Solving the Problem

[0005] To solve the above problems, an electric braking device according to one aspect of the present disclosure applies a braking force to a wheel by bringing a friction body into contact with a rotating body that rotates together with the wheel of a vehicle, and maintains the braking force applied to the wheel by locking a ratchet gear that rotates in sync with an electric motor that drives the friction body with a locking part, characterized in that the device comprises an actuator that drives the locking part in an approaching direction toward the ratchet gear and an awaying direction toward the ratchet gear, an elastic member that biases the locking part in the awaying direction, and a damper mechanism that applies greater resistance to the locking part the faster the locking part tries to move in the approaching direction. [Effects of the Invention]

[0006] According to one aspect of this disclosure, the electric braking device can be miniaturized while suppressing the engagement of the locking portion with the ratchet gear when the vehicle is not parked. [Brief explanation of the drawing]

[0007] [Figure 1] This figure shows the configuration of the electric braking device according to Embodiment 1 of this disclosure. [Figure 2] This is a diagram used to explain the parking brake mechanism according to Embodiment 1 of this disclosure. [Figure 3] This figure is used to explain the parking brake mechanism according to Embodiment 2 of the present disclosure. [Modes for carrying out the invention]

[0008] [Embodiment 1] Figure 1 shows the configuration of an electric braking device according to Embodiment 1 of this disclosure. The electric braking system BRK shown in Figure 1 is mounted on the vehicle. A vehicle equipped with the electric braking system BRK includes a braking operating member BP such as a brake pedal, a wheel WHL, and a rotating member KTB (rotating body) that rotates integrally with the wheel WHL. The electric braking system BRK also includes a caliper CRP and an electronic control unit ECU.

[0009] The caliper CRP shown in Figure 1 is a floating electric caliper. The caliper CRP comprises an electric motor MTR, a parking brake mechanism LOK, a reduction member GSK, a shaft SFT, a power conversion member NJB, a pressing member PSN, a pressing force acquisition unit FBA, and two friction members MSB (friction bodies).

[0010] The electric motor MTR is the power source for driving the pressing member PSN. The rotation of the electric motor MTR causes the power transmission member INP to rotate around the rotation axis Jin. The reduction member GSK has multiple reduction gears GR. The multiple reduction gears GR include a first gear GR1 fixed to the power transmission member INP and a second gear GR2 fixed to the shaft SFT. The reduction member GSK transmits the rotation of the power transmission member INP to the shaft SFT at a reduced rotational speed. The shaft SFT is rotatable around the rotation axis Jps.

[0011] The power conversion member NJB is, for example, a ball screw mechanism. The power conversion member NJB converts the rotational power of the shaft SFT into linear power and transmits it to the pressing member PSN. The pressing member PSN is, for example, a piston. The pressing member PSN moves in a direction parallel to the rotation axis Jps by linear power transmitted from the power conversion member NJB, and presses against the friction member MSB. The friction member MSB is positioned opposite the rotating member KTB, which rotates integrally with the vehicle's wheel WHL. The pressing force acquisition unit FBA acquires the pressing force, which is the force with which the pressing member PSN presses the friction member MSB.

[0012] The parking brake mechanism LOK is used as a parking brake for a vehicle and includes a ratchet gear RCH and a solenoid SOL. The ratchet gear RCH can rotate in sync with the electric motor MTR. For example, the ratchet gear may be mounted on the rotation axis Jin or on the reduction member GSK. When the ratchet gear RCH is mounted on the rotation axis Jin, the ratchet gear RCH rotates around the rotation axis Jin.

[0013] The rotation of the electric motor MTR is transmitted to the pressing member PSN by the reduction member GSK. When the electric motor MTR rotates in the forward direction, the pressing member PSN moves linearly in the forward direction, pressing (contacting) the friction member MSB against the rotating member KTB. On the other hand, when the electric motor MTR rotates in the reverse direction opposite to the forward direction, it moves linearly in the backward direction, and the friction member MSB moves away from the rotating member KTB.

[0014] Figure 2 is a diagram used to explain the parking brake mechanism according to Embodiment 1 of this disclosure. As shown in Figure 2, the parking brake mechanism LOK includes a solenoid SOL, a damper mechanism DMP, a lock pin LKP, an elastic member SPR, and a ratchet gear RCH.

[0015] A solenoid (SOL) is an example of an actuator. A solenoid (SOL) consists of a coil (COL), a base (fixed iron core) (BAS), a plunger (movable iron core) (PLN), a push bar (PBR), a housing (HSG), and an air gap spacer (AGS). The coil COL and base BAS are housed inside the housing HSG. The housing HSG is secured to the caliper CRP. The push bar PBR has one end in contact with the lock pin LKP and the other end fixed to the plunger PLN.

[0016] The lock pin LKP is an example of a locking mechanism, having a claw portion TSU at one end and a flange portion TSB at the other end. The flange portion TSB is in contact with the push bar PBR. The lock pin LKP is driven by a solenoid SOL in an approaching direction Dts toward the ratchet gear RCH and an awaying direction Dtr toward the ratchet gear RCH.

[0017] The damper mechanism DMP includes, for example, a guide section GUD, a first seal section SL1, and a second seal section SL2. The guide portion GUD guides the movement of the lock pin LKP. The guide portion GUD has, for example, an insertion hole INS through which one end side of the lock pin LKP is inserted. The insertion hole INS has an opening on one end side facing the tooth surface of the ratchet gear RCH, and an opening on the other end side facing the solenoid SOL. When the lock pin LKP is driven in the approaching direction Dts, the claw portion TSU of the lock pin LKP protrudes from one end side of the insertion hole INS.

[0018] The ratchet gear RCH has directionality in its teeth. With the claw portion TSU protruding from the insertion hole INS, when the ratchet gear RCH rotates in the reverse rotation direction Rvs, the claw portion TSU meshes with the teeth of the ratchet gear RCH. An elastic member SPR is accommodated in the air chamber AIR. The elastic member SPR is, for example, a coil spring, and biases the flange portion TSB of the lock pin LKP in the separation direction Dtr.

[0019] A first seal portion SL1 is provided at the opening on the other end side of the insertion hole INS. The first seal portion SL1 is, for example, an O-ring, through which the lock pin LKP is inserted. The first seal portion SL1 blocks the movement of air between the air chamber AIR and the insertion hole INS. A second seal portion SL2 is provided on the flange portion TSB of the lock pin LKP. The second seal portion SL2 is, for example, an O-ring, and is fixed to the flange portion TSB of the lock pin LKP. The second seal portion SL2 blocks the movement of air from the air chamber AIR to the solenoid SOL side. The first seal portion SL1 and the second seal portion SL2 may be lip seals. By being lip seals, the frictional force that hinders the driving of the lock pin LKP is reduced while maintaining sealing performance. In addition, since the first seal portion SL1 or the second seal portion SL2 elastically connects the lock pin LKP and the guide portion GUD, it is possible to suppress the situation where the lock pin LKP rotates relative to the guide portion GUD and the claw portion TSU is less likely to engage with the teeth of the ratchet gear RCH.

[0020] The guide section GUD has an air chamber AIR between the opening at the other end of the insertion hole INS and the flange TSB of the lock pin LKP. This air chamber AIR is partitioned by the lock pin LKP, the guide section GUD, the first seal section SL1, and the second seal section SL2. The guide section GUD has a through hole HL that connects the air chamber AIR to the atmospheric pressure section outside the guide section GUD. This through hole HL is an example of a connection section.

[0021] A magnetic field is generated when current flows through the windings of coil COL. When a magnetic field is generated in coil COL, base BAS attracts plunger PLN in the approaching direction Dts. The force with which base BAS attracts plunger PLN is stronger than the biasing force of elastic member SPR. As plunger PLN is attracted to base BAS against the biasing force of elastic member SPR, lock pin LKP is pressed by plunger PLN and slides in the approaching direction Dts. When the flange TSB of lock pin LKP slides in the approaching direction Dts, compressed air inside the air chamber AIR is discharged through the through hole HL.

[0022] When the flange portion TSB of the locking pin LKP slides in the approaching direction Dts, the pawl portion TSU of the first portion P1 protrudes from the insertion hole INS. The ratchet gear RCH has directional teeth. When the ratchet gear RCH rotates in the reverse direction Rvs with the pawl portion TSU protruding from the insertion hole INS, the pawl portion TSU engages with the teeth of the ratchet gear RCH. With the pawl portion TSU engaged with the pawl portion TSU of the locking pin LKP, the ratchet gear RCH is locked and can rotate in the forward direction Fwd, but cannot rotate in the reverse direction Rvs. In this way, the locking pin LKP locks the ratchet gear RCH, maintaining the braking force applied to the wheel.

[0023] After the energization to coil COL is released, the ratchet gear RCH rotates in the forward direction Fwd, disengaging the pawl member TSU from the ratchet gear RCH. Due to the biasing force of the elastic member SPR, the lock pin LKP slides in the separation direction Dtr. When the flange portion TSB of the lock pin LKP slides in the separation direction Dtr, air is drawn into the air chamber AIR through the through hole HL.

[0024] When a vehicle equipped with an electric braking system BRK is not parked, for example, when the vehicle equipped with the electric braking system BRK is in motion, the vehicle body may vibrate violently. If the vibration of the vehicle body causes the lock pin LKP to move in the approach direction Dts, there is a risk that the claw portion TSU of the lock pin LKP may become locked to the ratchet gear RCH even though the vehicle is in motion. In the electric braking system BRK according to Embodiment 1 of this disclosure, the damper mechanism DMP functions like an air damper. When the lock pin LKP is about to move rapidly in the approach direction Dts, such as when vibration is applied to the vehicle, the damper mechanism DMP applies resistance to the flange portion TSB of the lock pin LKP in proportion to its acceleration. The resistance applied to the flange portion TSB of the lock pin LKP increases as the lock pin LKP tries to move faster in the approach direction Dts.

[0025] The through-hole HL is designed with an opening diameter and other specifications such that the resistance is low when the lock pin LKP moves relatively slowly due to the driving force of the solenoid SOL, and high when the lock pin LKP moves relatively quickly, such as during vibrations when the vehicle is not parked.

[0026] [Embodiment 2] Other embodiments of this disclosure are described below. For the sake of clarity, components having the same function as those described in the above embodiments are denoted by the same reference numerals, and their descriptions are not repeated.

[0027] Figure 3 is a diagram used to explain the parking brake mechanism according to Embodiment 2 of this disclosure. In the parking brake mechanism LOK shown in Figure 3, the damper mechanism DMP does not have a through hole HL in the guide portion GUD, and instead a groove GR provided on the outer peripheral side surface of the lock pin LKP extends in the axial direction of the lock pin LKP. The groove GR is an example of a connection portion and extends in the axial direction of the lock pin LKP from a position near the flange portion TSB located in the air chamber AIR to a position near the claw portion TSU (tip) located in the atmospheric pressure portion. In the damper mechanism DMP according to Embodiment 2, the air chamber AIR and the atmospheric pressure portion outside the guide portion GUD are connected by this groove GR.

[0028] When the lock pin LKP moves relatively slowly in the approaching direction Dts due to the driving force of the solenoid SOL, air from the air chamber AIR is discharged from the groove GR to the outside of the guide part GUD. When the lock pin LKP moves relatively slowly in the away direction Dtr due to the driving force of the solenoid SOL, air is drawn into the air chamber AIR through the groove GR. The damper mechanism DMP according to Embodiment 2 functions as an air damper when the lock pin LKP is attempting to move rapidly in the approaching direction Dts, such as when vibration is applied to the vehicle, and applies resistance to the flange portion TSB of the lock pin LKP in proportion to its acceleration. The resistance applied to the flange portion TSB of the lock pin LKP increases as the lock pin LKP attempts to move faster in the approaching direction Dts.

[0029] [Variation] In Embodiment 1 described above, the air chamber AIR between the flange portion TSB of the lock pin LKP and the insertion hole ISR is connected to the atmospheric pressure outside the guide portion GUD via a through hole HL provided in the guide portion GUD. In Embodiment 2 described above, the air chamber AIR is connected to the atmospheric pressure outside the guide portion GUD via a groove GR provided on the outer peripheral side surface of the lock pin LKP. However, the method of connecting the air chamber AIR to the atmospheric pressure is not limited to the through hole HL and groove GR. For example, the air chamber AIR may be connected to the atmospheric pressure via a through hole and insertion hole INS provided in the first seal portion SL1.

[0030] In embodiments 1 and 2 described above, the damper section DMP functions as an air damper, and when the lock pin LKP is about to move rapidly in the approaching direction Dts, such as when vibration is applied to the vehicle, it applies resistance to the flange TSB of the lock pin LKP in proportion to its acceleration. However, the damper section DMP may function as an oil damper instead of an air damper. When the damper section DMP according to embodiment 1 functions as an oil damper, oil is stored in the air chamber AIR. When the damper section DMP according to embodiment 1 functions as an oil damper, it is preferable to provide an oil reservoir in the middle of the through hole HL.

[0031] 〔summary〕 An electric braking device according to one aspect of the present disclosure applies a braking force to a wheel by bringing a friction body into contact with a rotating body that rotates together with the wheel of a vehicle, and maintains the braking force applied to the wheel by locking a ratchet gear that rotates in sync with an electric motor that drives the friction body with a locking portion, the electric braking device comprising: an actuator that drives the locking portion in an approaching direction toward the ratchet gear and an awaying direction toward the ratchet gear; an elastic member that biases the locking portion in the awaying direction; and a damper mechanism that applies greater resistance to the locking portion the faster the locking portion tries to move in the approaching direction. In an electric braking system that applies braking force to a wheel by contacting a friction body with a rotating body that rotates with the vehicle's wheels, and maintains the braking force applied to the wheel by locking a ratchet gear that rotates in sync with an electric motor that drives the friction body, the locking part is kept away from the ratchet gear while the vehicle is running to prevent contact between the locking part and the ratchet gear. However, vibrations of the vehicle body may cause the locking part to approach the ratchet gear, potentially leading to contact between the locking part and the ratchet gear. If an elastic member is used to bias the locking part in the away direction to prevent contact between the locking part and the ratchet gear due to vehicle body vibrations, the driving force required to drive the locking part in the approach direction by the actuator will increase, leading to a larger actuator and hindering the miniaturization of the electric braking system. In this regard, in the electric braking device according to the present disclosure, the damper mechanism prevents the locking portion from approaching the ratchet gear. Specifically, the rate of change of external force applied to the locking portion due to vehicle body vibrations, etc., is faster than the rate of change of driving force applied to the locking portion by the actuator. Therefore, the force applied to the locking portion due to vehicle body vibrations, etc., is attenuated by the damper mechanism more than the driving force when the actuator drives the locking portion in the approaching direction. Accordingly, according to the present disclosure, it is possible to miniaturize the electric braking device while suppressing contact of the locking portion with the ratchet gear during vehicle operation.

[0032] An electric braking device according to one aspect of the present disclosure, in the embodiment, the damper mechanism has a locking portion, a guide portion that guides the movement of the locking portion in the approaching direction, and a sealing portion that together with the locking portion and the guide portion partitions an air chamber, and a connecting portion that connects the air chamber to an atmospheric pressure portion which is at atmospheric pressure is provided on at least one of the members that partition the air chamber. The force applied to the locking part due to vibrations of the road body, etc., is attenuated by the relative velocity generated between the locking part and the guide part, which compresses the air in the air chamber and discharges it from the connection part. Therefore, according to this disclosure, it is possible to miniaturize the electric braking device while suppressing contact of the locking part with the ratchet gear during vehicle operation.

[0033] [Additional Notes] This disclosure is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of this disclosure. [Explanation of Symbols]

[0034] BRK electric braking device DMP Damper Mechanism GR groove (connecting part) GUD Guide Department HL through hole (connection part) LKP Lock Pin (Locking Part) RCH Ratchet Gear SL1 First seal section SL2 Second seal section SOL Solenoid (Actuator) SPR elastic material

Claims

1. In an electric braking device, a friction body is brought into contact with a rotating body that rotates together with the vehicle's wheels to apply braking force to the wheels, and a ratchet gear that rotates in sync with an electric motor that drives the friction body is locked in a locking mechanism to maintain the braking force applied to the wheels, An actuator drives the locking portion in an approaching direction towards the ratchet gear and in an awaying direction away from the ratchet gear, The locking portion is provided with an elastic member that biases it in the separation direction, A damper mechanism that applies greater resistance to the locking portion the faster the locking portion attempts to move in the approaching direction, An electric braking system characterized by having the following features.

2. The damper mechanism includes a locking portion, a guide portion that guides the movement of the locking portion in the approaching direction, and a sealing portion that together with the locking portion and the guide portion partitions the air chamber. The electric braking device according to claim 1, characterized in that a connecting portion for connecting the air chamber and the atmospheric pressure portion, which is at atmospheric pressure, is provided on at least one of the members that partition the air chamber.

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