Electric braking device

Abstract

According to the present invention, a ratchet gear (RCH) has, on a tooth surface on the first direction (Rvs) side relative to a tooth tip (HSK), a surface (HTM) to be contacted which is curved from the tooth tip (HSK) toward the first direction (Rvs) side, while a claw member (TSU), in a state of being engaged with the ratchet gear (RCH), abuts on the contact surface (HTM) and receives, from the ratchet gear (RCH), a force (F) including a component (Fts) in the approach direction.

Description

electric braking device

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

[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, exerts its function 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.

[0003] JP 2015-108411 A

[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 member may come into contact, or the tooth bases of the ratchet gear and the pawl tips of the pawl member may come into contact, preventing contact at the meshing surfaces and resulting in unstable engagement.One aspect of the present disclosure aims to stabilize the engagement between the teeth of the ratchet gear and the pawls of the pawl member.

[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, including: 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 includes 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 brings 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 that follows 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.

[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.

[0007] 1 is a diagram illustrating a configuration of an electric braking device according to an embodiment of the present disclosure. 2 is a diagram used to explain a parking brake mechanism according to an embodiment of the present disclosure. 3 is a diagram illustrating a state in which a contact surface is in contact with a contacted surface.

[0008] Fig. 1 is a diagram showing the configuration of an electric braking device according to one 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, wheels WHL, and a rotating member KTB that rotates integrally with the wheels WHL. The electric braking device BRK includes a caliper CRP and an electronic control unit ECU.

[0009] 1 is a floating-type electric caliper including 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 causes the power transmission member INP to rotate 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 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 due to 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 wheels 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 deceleration member GSK. When the electric motor MTR rotates in the forward direction, the pressing member PSN moves linearly in the forward direction, 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 in the backward direction, 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 one embodiment of the present disclosure. As shown in Fig. 2, the parking brake mechanism LOK has 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 a state in which the pawl member TSU is meshed with the ratchet gear RCH.

[0015] The elastic member SPR is, for example, a spring. The elastic member SPR 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 addendum circle C1 of the ratchet wheel 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 the base BAS are housed within the housing HSG. The housing HSG is fixed to the caliper CRP. One end of the push bar PBR contacts the pawl member TSU, and the other end is fixed to the plunger PLN.

[0016] A magnetic field is generated when a current flows through the windings 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. The current supply to the electric motor MTR is reduced, and after it is confirmed that the pawl member TSU and the ratchet wheel RCH are engaged, the current supply to the coil COL is released. After the current supply to the coil COL is released, 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 wheel RCH is fixed to the power transmission member INP. In a side view of the ratchet wheel RCH, the ratchet wheel RCH is coaxial with the power transmission member INP. If a predetermined tooth of the ratchet wheel RCH can mesh with the pawl member TSU when the rotation angle of the electric motor MTR is 0 degrees, the predetermined tooth of the ratchet wheel 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 a 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, so 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, which are closer to the reverse rotation direction Rvs than the tooth tip HSK, have a contacted surface HTM along a tooth profile that curves from the tooth tip HSK toward the reverse rotation 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 tooth bottom 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] 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 tip of the pawl member TSU can be inserted between the concave surface OUM of the ratchet wheel RCH and the tooth bottom.

[0023] With the tip of the pawl member TSU inserted between the concave surface OUM and the tooth root of the ratchet wheel RCH, the ratchet wheel 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 wheel RCH. The force F applied to the pawl member TSU from the ratchet wheel RCH includes an approaching direction component Fts. The force applied from the ratchet wheel 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, comprising: 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, 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; In an electric braking device that restricts linear movement of the pressing member by using a solenoid to drive the pawl member toward the ratchet gear and to engage the pawl member with the teeth of the ratchet gear, the tooth flank of the ratchet gear on the first direction side of the tooth tip has an abutment surface along a tooth profile that curves from the tooth tip toward the first direction, and the pawl member is configured to abut against the abutment surface when engaged with the ratchet gear and receive a force from the ratchet gear that includes a component in the approach direction. The tooth flank of the ratchet gear of the present disclosure includes an abutment surface along a tooth profile that curves from the tooth tip toward the first direction. The pawl member is also configured to receive a force from the ratchet gear that includes a component in the approach direction. As a result, even if the inclination of the pawl portion changes due to manufacturing errors, the pawl member can receive a force in the approaching direction from the curved abutment surface of the ratchet gear. This prevents the pawl member from coming loose in the separation direction, stabilizing the fit. Furthermore, even when the tooth tips of the ratchet gear and the pawl member abut against each other when the pawl member is driven in the approaching direction, the abutment 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 over the abutment surface, leading to a state in which the abutment surface and the abutment surface abut. This stabilizes the fit between the ratchet gear and the pawl member.

[0025] In an electric braking device according to one aspect 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 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 that curves from the tip of the tooth of the ratchet gear toward the first direction. Therefore, the pawl member can 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 engagement.

[0026] In an electric braking device according to one aspect of the present disclosure, the abutment surface includes a convex surface that curves toward the tooth root of the ratchet gear, and a tooth surface of the ratchet gear that is closer to the tooth tip in the first direction than the tooth tip includes a concave surface that is closer to the tooth root than the abutment surface and curves toward the second direction, and a first plane connecting the convex surface and the concave surface, and the abutment surface includes a second plane, and a second angle formed by a second imaginary plane including the second plane with the approach direction is smaller than a first angle formed by a first imaginary plane including the first plane 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 contacting each other and contacting the tip of the pawl member, even if a manufacturing error occurs. This stabilizes engagement and prevents 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.

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 to press a friction member against a rotating member that rotates together with the vehicle wheels, and in a reverse direction opposite to the forward direction; and a parking brake mechanism which, with the friction member pressed against the rotating member, restricts the linear movement of the pressing member in the reverse direction, wherein the parking brake mechanism comprises a ratchet gear which rotates in a first direction when the pressing member moves linearly in the reverse direction and which rotates in a second direction when the pressing member moves linearly in the forward direction; a pawl member which engages with the teeth of the ratchet gear; and a solenoid which drives the pawl member in an approaching direction to move it closer to the ratchet gear and in a separating direction to move it away from the ratchet gear, wherein the solenoid moves the pawl member closer to the ratchet gear and causes the pawl member to engage with the teeth of the ratchet gear, thereby restricting the linear movement of the pressing member. an abutment surface formed along a tooth profile curved from the tooth tip toward the first direction among the tooth surfaces of the ratchet gear, the abutment surface being formed along a tooth profile curved from the tooth tip toward the first direction; and the pawl member is configured to abut against the abutment surface when meshed with the ratchet gear and to receive a force from the ratchet gear that includes a component in the approach direction.

2. An electric braking device as described in claim 1, characterized in that 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.

3. The electric braking device according to claim 2, wherein 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, and a first plane that connects the convex surface and the concave surface, and the abutting 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.

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