Electric braking device

Abstract

To stabilize fitting of a tooth of a ratchet gear and a pawl of a pawl member.SOLUTION: The ratchet gear (RCH) has an abutted surface (HTM) curved from the tooth tip (HSK) to the first direction (Rvs) side on a tooth surface on the first direction (Rvs) side with respect to the tooth tip (HSK), and the pawl member (TSU) abuts on the abutted surface (HTM) and receives the force (F) including the approaching direction component (Fts) from the ratchet gear (RCH) in a state of being interlocked with the ratchet gear (RCH).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to an electric braking system. [Background technology]

[0002] The parking brake of an electric braking device, in which both the normal brake and the parking brake are performed by an electric motor, functions by restricting the movement of the electric motor with a locking mechanism consisting of a ratchet gear and a pawl member. In general electric braking devices, including the electric braking device described in Patent Document 1, the teeth of the ratchet gear and the pawl of the pawl member are designed to contact each other at their meshing surfaces to prevent disengagement due to friction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-108411 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the electric braking device described in Patent Document 1, depending on manufacturing errors, the tooth tips of the ratchet gear and the pawl tips of the pawl members may come into contact, or the tooth bases of the ratchet gear and the pawl tips of the pawl members may come into contact, preventing contact at the mating surfaces and resulting in unstable engagement. One aspect of the present disclosure is directed to stabilizing the engagement between the teeth of the ratchet wheel and the pawl of the pawl member. [Means for solving the problem]

[0005] In order to solve the above-mentioned problems, an electric braking device according to one aspect of the present disclosure is an electric braking device for a vehicle, comprising: a pressing member that is driven by an electric motor and moves linearly in a forward direction to press a friction member against a rotating member that rotates together with the wheels of the vehicle, and in a reverse direction opposite to the forward direction; and a parking brake mechanism that restricts the linear movement of the pressing member in the reverse direction while pressing the friction member against the rotating member, wherein the parking brake mechanism comprises a ratchet gear that rotates in a first direction when the pressing member moves linearly in the reverse direction and that rotates in a second direction when the pressing member moves linearly in the forward direction; a pawl member that meshes with the teeth of the ratchet gear; The electric braking device includes a solenoid that drives a member in an approach direction that moves the member closer to the ratchet gear and in a separation direction that moves the member away from the ratchet gear, and the solenoid moves the pawl member closer to the ratchet gear and causes the pawl member to mesh with the teeth of the ratchet gear, thereby restricting the linear movement of the pressing member.The tooth flanks of the ratchet gear that are closer to the first direction than the tooth tips have an abutment surface along a tooth profile that curves from the tooth tips toward the first direction, and the pawl member abuts against the abutment surface when meshed with the ratchet gear, and is configured to receive a force from the ratchet gear that includes a component in the approach direction. [Effects of the Invention]

[0006] According to one aspect of the present disclosure, the engagement between the teeth of the ratchet wheel and the pawl of the pawl member is stable. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram illustrating a configuration of an electric braking device according to an embodiment of the present disclosure. [Figure 2] 1A and 1B are diagrams used to explain a parking brake mechanism according to an embodiment of the present disclosure. [Figure 3] 10 is a diagram showing a state in which the contact surface contacts the contacted surface; FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] FIG. 1 is a diagram showing the configuration of an electric braking device according to an embodiment of the present disclosure. The electric braking device BRK shown in Fig. 1 is mounted on a vehicle. The vehicle equipped with the electric braking device BRK includes a brake operating member BP such as a brake pedal, a wheel WHL, and a rotating member KTB that rotates integrally with the wheel WHL. The electric braking device BRK includes a caliper CRP and an electronic control unit ECU.

[0009] The caliper CRP shown in Fig. 1 is a floating-type electric caliper. The caliper CRP includes an electric motor MTR, a parking brake mechanism LOK, a deceleration 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.

[0010] The electric motor MTR is a power source for driving the pressing member PSN. Rotation of the electric motor MTR rotates the power transmission member INP around the rotation axis Jin. The reduction member GSK has a plurality of reduction gears GR. The plurality of reduction gears GR includes 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 a 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 the linear power transmitted from the power conversion member NJB, and presses the friction member MSB. The friction member MSB is disposed in a position facing the rotating member KTB, which rotates integrally with the vehicle 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 for parking the vehicle and includes a ratchet gear RCH and a solenoid SOL. The ratchet gear RCH can rotate around a 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 forward, pressing 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, the pressing member PSN moves linearly backward, and the friction member MSB moves away from the rotating member KTB.

[0014] FIG. 2 is a diagram used to explain a parking brake mechanism according to an embodiment of the present disclosure. As shown in Fig. 2, the parking brake mechanism LOK includes a ratchet gear RCH, a solenoid SOL, a pawl member TSU, and an elastic member SPR. The pawl member TSU can mesh with the teeth of the ratchet gear RCH. Fig. 2 shows the state in which the pawl member TSU is meshed with the ratchet gear RCH.

[0015] The elastic member SPR is, for example, a spring, and biases the pawl member TSU in a separation direction Dtr in which the pawl member TSU moves away from the ratchet wheel RCH. The solenoid SOL is disposed at a position facing the tip circle C1 of the ratchet gear RCH. The solenoid SOL is a pull solenoid and includes 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 in the housing HSG, which is fixed to the caliper CRP. The push bar PBR has one end in contact with the pawl member TSU and the other end fixed to the plunger PLN.

[0016] A magnetic field is generated when a current flows through the winding of the coil COL. When a magnetic field is generated in the coil COL, the base BAS attracts the plunger PLN in an approaching direction Dts. The approaching direction Dts is opposite to the separating direction Dtr in which the elastic member SPR urges the pawl member TSU. The force with which the base BAS attracts the plunger PLN is stronger than the urging force of the elastic member SPR. As the plunger PLN is attracted to the base BAS against the urging force of the elastic member SPR, the pawl member TSU is pressed by the plunger PLN and moves, protruding in the approaching direction Dts toward the ratchet wheel RCH. On the other hand, when no current flows through the coil COL, the pawl member TSU is urged in the separating direction Dtr by the elastic member SPR. After the power supply to the electric motor MTR is reduced and engagement between the pawl member TSU and the ratchet wheel RCH is confirmed, the power supply to the coil COL is released. After the coil COL is de-energized, the ratchet wheel RCH rotates in the forward direction Fwd, thereby releasing the engagement between the pawl member TSU and the ratchet wheel RCH. An air gap spacer AGS is provided between the plunger PLN and the base BAS.

[0017] The ratchet gear RCH is fixed to the power transmission member INP. In a side view of the ratchet gear RCH, the ratchet gear RCH is coaxial with the power transmission member INP. If a predetermined tooth of the ratchet gear RCH can mesh with the pawl member TSU when the rotation angle of the electric motor MTR is 0 degrees, then a predetermined tooth of the ratchet gear RCH can mesh with the pawl member TSU each time the rotation angle of the electric motor MTR rotates a predetermined angle in the forward rotation direction Fwd. The forward rotation direction Fwd is an example of the second direction.

[0018] The ratchet gear RCH has teeth with a directional nature. When the ratchet gear RCH is engaged with the pawl member TSU, the ratchet gear RCH can rotate in the forward direction Fwd but cannot rotate in the reverse direction Rvs. The reverse direction Rvs is an example of the first direction. When the ratchet gear RCH is engaged with the pawl member TSU, the power transmission member INP cannot rotate in the reverse direction Rvs, and therefore, the linear movement of the pressing member PSN in the backward direction is restricted.

[0019] The tooth tip HSK of each tooth of the ratchet wheel RCH is in contact with the tooth tip circle C1, and the tooth root is in contact with the tooth root circle C2. The tooth flanks of the ratchet wheel RCH on the reverse direction Rvs side of the tooth tip HSK have a contacted surface HTM along a tooth profile that curves from the tooth tip HSK toward the reverse direction Rvs. The contacted surface HTM extends, for example, while curving from the tooth tip HSK toward the tooth root, and includes a convex surface TTM that is convex on the radially outer side of the ratchet wheel RCH.

[0020] The tooth surface of the ratchet wheel RCH on the reverse rotation direction Rvs side has a concave surface OUM that is located closer to the bottom of the tooth than the abutted surface HTM and curved so as to be concave toward the forward rotation direction Fwd, and a first plane DM1 that is connected to the convex surface TTM and the concave surface OUM.

[0021] The pawl member TSU has an abutment surface KMM that is inclined toward the forward rotation direction Fwd with respect to the approach direction Dts. When the pawl member TSU is driven in the approach direction Dts, the pawl member TSU abuts against the tooth root of the ratchet wheel RCH. When the ratchet wheel RCH is rotated in the reverse direction Rvs, the abutment surface KMM abuts against the abutted surface HTM. Even if the tip of the pawl member TSU abuts against the tooth tip HSK of the ratchet wheel RCH when the pawl member TSU is driven in the approach direction Dts, the tip of the pawl member TSU slides along a surface curved from the tooth tip HSK of the ratchet wheel RCH and is inserted between the concave surface OUM and the tooth root of the ratchet wheel RCH. When the ratchet wheel RCH is rotated in the reverse direction Rvs, the abutment surface KMM abuts against the abutted surface HTM. Therefore, the ratchet wheel RCH and the pawl member TSU are unlikely to be in a so-called half-engaged state.

[0022] FIG. 3 is a diagram showing a state in which the contact surface contacts the contacted surface. In FIG. 3, the pawl member TSU contacts the tooth bottom of the ratchet wheel RCH. The contact surface KMM of the pawl member TSU contacts the contacted surface HTM of the ratchet wheel RCH. The second angle θ2 formed by a second imaginary plane including a plane of the contact surface KMM that contacts the contacted surface HTM (hereinafter referred to as the second plane) and the approach direction Dts is smaller than the first angle θ1 formed by a first imaginary plane including the first plane DM1 and the approach direction Dts. Therefore, even if there is a manufacturing error, the pawl tip of the pawl member TSU can be inserted between the concave surface OUM and the tooth bottom of the ratchet wheel RCH.

[0023] With the tip of the pawl member TSU inserted between the concave surface OUM and the tooth root of the ratchet gear RCH, the ratchet gear RCH rotates in the reverse direction Rvs, causing the second flat surface of the abutting surface KMM to abut against the abutted surface HTM. When the second flat surface of the abutting surface KMM abuts against the abutted surface HTM, the pawl member TSU receives a force F from the ratchet gear RCH. The force F applied to the pawl member TSU from the ratchet gear RCH includes an approaching direction component Fts. The force applied from the ratchet gear RCH prevents the pawl member TSU from coming off in the separating direction Dtr.

[0024] 〔summary〕 An electric braking device according to one aspect of the present disclosure is an electric braking device for a vehicle, the electric braking device including: a pressing member driven by an electric motor, which moves linearly in a forward direction to press a friction member against a rotating member that rotates together with the wheels of the vehicle, and in a reverse direction opposite to the forward direction; and a parking brake mechanism that restricts the linear movement of the pressing member in the reverse direction while pressing the friction member against the rotating member, the parking brake mechanism including a ratchet gear that rotates in a first direction when the pressing member moves linearly in the reverse direction and that rotates in a second direction when the pressing member moves linearly in the forward direction; a pawl member that meshes with the teeth of the ratchet gear; and a parking brake mechanism that restricts the linear movement of the pressing member in the reverse direction while pressing the friction member against the rotating member. and a solenoid that drives the pawl member in an approach direction that brings it closer to the ratchet gear and in a separation direction that moves it away from the ratchet gear, and the solenoid brings the pawl member closer to the ratchet gear and causes the pawl member to mesh with the teeth of the ratchet gear, thereby regulating the linear movement of the pressing member.In this electric braking device, the tooth flanks of the ratchet gear that are closer to the tooth tips in the first direction have an abutment surface along a tooth profile that curves from the tooth tips toward the first direction, and the pawl member abuts against the abutment surface when meshed with the ratchet gear, and is configured to receive a force from the ratchet gear that includes a component in the approach direction. The tooth flanks of the ratchet gear of the present disclosure include abutment surfaces along a tooth profile that curves from the tooth tip toward the first direction. The pawl members are configured to receive a force from the ratchet gear that includes a component in the approaching direction. This allows the pawl members to receive a force in the approaching direction from the curved abutment surfaces of the ratchet gear, even if the inclination of the pawl portions changes due to manufacturing errors. This prevents the pawl members from slipping out in the separating direction, stabilizing the engagement. Furthermore, when the pawl member is driven in the approaching direction, even if the tooth tips of the ratchet gear and the pawl member come into contact with each other, the abutted surface of the ratchet gear is curved from the tooth tips toward the first direction, so the driving force of the solenoid causes the pawl member to slide along the abutted surface, leading to a state in which the abutted surface and the abutting surface come into contact with each other. This stabilizes the engagement between the ratchet gear and the pawl member.

[0025] In one aspect of the electric braking device of the present disclosure, the pawl member has an abutment surface that is inclined toward the second direction relative to the approach direction, and when the pawl member is driven in the approach direction, the abutment surface abuts against the abutted surface. The abutment surface of the pawl member is inclined toward the second direction relative to the approach direction. Therefore, when the pawl member is driven in the approach direction, the abutment surface approaches the abutted surface, which curves from the tooth tip of the ratchet gear toward the first direction. This allows the pawl member to receive a sufficiently large force in the approach direction from the abutted surface of the ratchet gear. This prevents the pawl member from coming loose in the separation direction, stabilizing the fit.

[0026] In one embodiment of the electric braking device of the present disclosure, the abutted surface includes a convex surface that curves toward the tooth root side of the ratchet gear, and the tooth surface of the ratchet gear that is on the first direction side of the tooth tip has a concave surface that is located on the tooth root side of the abutted surface and curves toward the second direction side, and a first plane that connects the convex surface and the concave surface, the abutment surface includes a second plane, and a second angle that a second imaginary plane that includes the second plane forms with the approach direction is smaller than a first angle that a first imaginary plane that includes the first plane forms with the approach direction. In the present disclosure, the second angle is set smaller than the first angle. This prevents the mating surfaces of the ratchet gear and the pawl member from coming into contact with each other even in the event of manufacturing errors, thereby stabilizing the engagement and preventing the parking brake mechanism from being released. Furthermore, by providing a flat surface on the pawl member so that the flat surface comes into contact with the mating surface of the ratchet gear, the direction of the force that the pawl member receives from the ratchet gear is uniform. Therefore, even if a manufacturing error occurs, the force is received in the same direction, and it is possible to prevent the tips of the teeth of the ratchet gear and the tips of the teeth of the pawl member from coming into contact with each other. This stabilizes the engagement and prevents the parking brake mechanism from being released.

[0027] [Additional Notes] The present disclosure is not limited to the above-described embodiments, 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 the present disclosure. [Explanation of symbols]

[0028] DM1 1st plane Dtr Separation direction Dts approach direction F force Fts: The component of force F in the approach direction Fwd Forward rotation direction Rvs Reverse direction HSK tooth tip HTM contact surface KMM contact surface LOK parking brake mechanism RCT ratchet gear TSU claw material θ1 1st angle θ2 2nd angle

Claims

1. An electric braking device for a vehicle, comprising: a pressing member driven by an electric motor, which moves linearly in a forward direction and a backward direction opposite to the forward direction, pressing a friction member against a rotating member which rotates together with a wheel of the vehicle; and a parking brake mechanism which restricts the linear movement of the pressing member in the backward direction while pressing the friction member against the rotating member, The parking brake mechanism includes a ratchet gear that rotates in a first direction when the pressing member moves linearly in the backward direction and that rotates in a second direction when the pressing member moves linearly in the forward direction, a pawl member that meshes with teeth of the ratchet gear, and a solenoid that drives the pawl member in an approach direction to approach the ratchet gear and a separation direction to move the pawl member away from the ratchet gear, and the solenoid moves the pawl member closer to the ratchet gear and causes the pawl member to mesh with teeth of the ratchet gear, thereby restricting the linear movement of the pressing member. a tooth surface of the ratchet gear that is closer to the first direction than the tooth tip has an abutment surface along a tooth profile that curves from the tooth tip toward the first direction, an electric braking device characterized in that the pawl member is configured to abut against the abutted surface while meshing with the ratchet gear, and to receive a force from the ratchet gear that includes a component in the approach direction.

2. the pawl member has an abutment surface inclined toward the second direction with respect to the approach direction, 2. The electric braking device according to claim 1, wherein the contact surface contacts the contacted surface when the pawl member is driven in the approaching direction.

3. the abutted surface includes a convex surface that curves toward the tooth root side of the ratchet gear, a tooth surface of the ratchet gear that is located on the first direction side of the tooth tip has a concave surface that is located on the tooth bottom side of the abutted surface and curved toward the second direction side, and a first plane that connects the convex surface and the concave surface, the abutment surface includes a second plane; 3. The electric braking device according to claim 2, wherein a second angle formed by a second imaginary plane including the second plane and the approach direction is smaller than a first angle formed by a first imaginary plane including the first plane and the approach direction.

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