electric brake

Abstract

The present application provides an electric brake capable of improving reliability and suppressing cost increase and overall size increase. A brake holding mechanism of a first embodiment of a disc brake as the electric brake is provided with: a rotation shaft and a ratchet gear provided on a rotation transmission path from an electric motor to a brake mechanism, which transmits rotation from the electric motor; a restriction mechanism that restricts rotation of the ratchet gear in a release direction; and a clutch unit that allows rotation in an application direction for the rotation shaft when the rotation of the ratchet gear in the release direction is restricted by the restriction mechanism. Thus, in the present disc brake, reliability can be improved, and cost increase and overall size increase can be suppressed.

Description

Technical Field

[0001] This invention relates to an electric brake for braking vehicles. Background Technology

[0002] For example, in the electric braking device described in Patent Document 1, when the parking brake is actuated, in the parking brake locking mechanism, the engaging pawl engages with the ratchet gear fixed to the rotating shaft of the electric motor by the force of the compression spring generated by the energization of the solenoid, thereby maintaining its braking state. On the other hand, when the parking brake is released, by energizing the solenoid of the parking brake locking mechanism, the plunger of the solenoid extends, the engaging pawl disengages from the ratchet gear, and the parking brake is released.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2003-42199 Summary of the Invention

[0006] The technical problem that the invention aims to solve

[0007] In the electric braking device described in Patent Document 1, when the parking brake is activated, after the solenoid is energized to disengage the engaging pawl from the ratchet gear, the electric motor is rotated in the direction of the applied rotational axis. After reaching the specified braking force, the energization of the solenoid is stopped, thereby engaging the engaging pawl with the ratchet gear. Furthermore, relative to the braking force (thrust) of the inner and outer brake blocks on the disc brake, a reduction in the thermal shrinkage of the inner and outer brake blocks is detected. Upon re-clamping, the electric motor is energized, rotating with a torque greater than the reaction force of the spring exerting force on the engaging pawl, thereby increasing the braking force.

[0008] However, in the electric braking device described in Patent Document 1, when the parking brake is activated, the engaging pawl needs to engage with the ratchet gear one tooth at a time. Therefore, the braking force must be set to be at least equal to one tooth of the ratchet gear, which is at least greater than the minimum braking force (thrust) required to keep the vehicle in place. This requires increasing the motor output. As a result, not only is it necessary to improve the motor performance, but also to increase the size of the reduction mechanism, rotary-to-direction conversion mechanism (braking mechanism), etc., which raises concerns about increased costs and the overall size of the device.

[0009] In addition, conventional electric braking devices also include the following type: when the parking brake is activated or when re-clamping, after the electric motor is rotated in the specified direction to achieve the specified braking force, the solenoid is energized to engage the locking pawl with the ratchet gear to maintain the braking force. In this type, especially when re-clamping, the braking force is increased by the electric motor while the locking pawl and ratchet gear are temporarily disengaged (the solenoid is de-energized and released by the force of the compressed coil spring, etc.). Therefore, especially in the event of a solenoid failure, the parking brake (braking force) may disappear, resulting in a lack of reliability.

[0010] Therefore, the object of the present invention is to provide an electric brake that can improve reliability and suppress cost increases and overall device size.

[0011] Technical solutions for solving the above-mentioned technical problems

[0012] As a technical solution to solve the above-mentioned technical problems, the electric brake of the present invention comprises: a motor; a braking mechanism that generates braking force by pressing a braking member against a braked member through rotation from the motor; and a brake holding mechanism that retains the braking force generated by the braking mechanism, the brake holding mechanism comprising: a rotating shaft and a rotating member that transmits rotation from the motor; a limiting mechanism that limits rotation of the rotating member in another direction when the direction of rotation of the rotating shaft and the rotating member when the braking member is pressed against the braked member by the braking mechanism is set to one direction; and a clutch unit that, when the rotation of the rotating member in the other direction is limited by the limiting mechanism, allows relative rotation of the rotating shaft in the one direction and limits relative rotation in the other direction.

[0013] According to an embodiment of the present invention, the electric brake can improve reliability and suppress cost increases and overall device size. Attached Figure Description

[0014] Figure 1 This is an external view of the disc brake according to this embodiment.

[0015] Figure 2 This is a cross-sectional view of the main parts of the disc brake in this embodiment.

[0016] Figure 3 In the disc brake of this embodiment, (a) is a perspective view of the brake holding mechanism of the first embodiment, and (b) is a top view of the brake holding mechanism of the first embodiment.

[0017] Figure 4This is a schematic diagram illustrating the function (control by the electronic control unit) of the brake holding mechanism in the first embodiment, and it shows the initial state of the pawl disengaging from the ratchet gear.

[0018] Figure 5 This is a schematic diagram illustrating the function of the brake holding mechanism in the first embodiment, showing a pre-conceived incomplete engagement state when the pawl engages with the gear part of the ratchet gear.

[0019] Figure 6 This is a schematic diagram illustrating the function of the brake holding mechanism in the first embodiment, showing a pre-conceived incomplete engagement state when the pawl engages with the gear part of the ratchet gear.

[0020] Figure 7 This is a schematic diagram illustrating the function of the brake holding mechanism in the first embodiment, showing the normal engagement state between the pawl and the gear part of the ratchet gear.

[0021] Figure 8 This is a schematic diagram illustrating the function of the brake holding mechanism in the first embodiment. It shows the state in which the rotating shaft rotates relative to the ratchet gear in the application direction by means of the one-way clutch during application and re-clamping.

[0022] Figure 9 This is a schematic diagram illustrating the function of the brake holding mechanism in the first embodiment, showing the state in which the thrust (braking force) is maintained by the reaction force from the ratchet gear.

[0023] Figure 10 This is a schematic diagram illustrating the function of the brake holding mechanism in the first embodiment. It shows the state in which, upon release, the reaction force from the ratchet gear disappears and the engagement between the pawl and the gear portion of the ratchet gear is released.

[0024] Figure 11 This is a schematic diagram illustrating the function of the brake holding mechanism in the first embodiment, showing the state in which the pawl disengages from the ratchet gear and returns to its initial state upon release.

[0025] Figure 12 This is a timing diagram of the braking and holding mechanism in the first embodiment when it operates.

[0026] Figure 13 (a) is a perspective view of the disc brake of this embodiment, and (b) is a perspective view of the brake holding mechanism of the second embodiment, showing the state in which the pawl and the gear part of the ratchet gear are fully engaged.

[0027] Figure 14In the disc brake of this embodiment, (a) is a perspective view of the brake holding mechanism of the third embodiment, (b) is a top view showing the intermediate engagement of the pawl and the gear part of the ratchet gear under the action of the brake holding mechanism of the third embodiment, and (c) is a top view showing the state in which the pawl and the gear part of the ratchet gear are fully engaged.

[0028] Figure 15 In the disc brake of this embodiment, (a) is a perspective view of the brake holding mechanism of the fourth embodiment, and (b) is a top view of the brake holding mechanism of the fourth embodiment, showing the state in which the curved surface of the holding member abuts against the friction member (outer peripheral surface) of the rotating body.

[0029] Figure 16 In the disc brake of this embodiment, (a) is a perspective view of another embodiment of the brake holding mechanism of the fourth embodiment, and (b) is a top view of another embodiment of the brake holding mechanism of the fourth embodiment, showing the state in which the curved surface of the holding member abuts against the friction member (outer peripheral surface) of the rotating body. Detailed Implementation

[0030] The following is based on Figures 1 to 16 This implementation method will be described in detail.

[0031] The disc brake 1 in this embodiment is configured as an electric brake that generates braking force during normal driving by being driven by an electric motor 40. It should be noted that in the following description, the inner side of the vehicle (inner side) will be referred to as one end side (cover member 34 side), and the outer side of the vehicle (outer side) will be referred to as the other end side (brake disc D side), as appropriate. That is, in Figure 1 and Figure 2 In this context, the right side will be referred to as one end side, and the left side as the other end side, as appropriate.

[0032] Reference Figure 1 and Figure 2 The disc brake 1 of this embodiment is an electric brake, comprising a pair of inner brake blocks 2 and outer brake blocks 3 and a brake caliper 4 disposed on both sides of a brake disc D mounted on a rotating part (not shown) of the vehicle, separated by the disc. It should be noted that the inner and outer brake blocks 2 and 3 correspond to braking components. The brake disc D corresponds to the braked component. The disc brake 1 of this embodiment is configured as a floating brake caliper type. It should be noted that the pair of inner brake blocks 2 and outer brake blocks 3 and brake caliper 4 are movably supported on a bracket 5 along the axial direction of the brake disc D. The bracket 5 is fixed to a non-rotating part of the vehicle, such as a steering knuckle (not shown), and is arranged across the outer periphery of the brake disc D.

[0033] The bracket 5 includes: a pair of pin connecting portions 9, 9 that are respectively connected to the sliding pins 7, 7 (described later); an inner support portion 11 and an outer support portion 12 that are integrally connected to the pair of pin connecting portions 9, 9 and independently support the inner brake block 2 and the outer brake block 3, allowing them to move freely axially toward the brake disc D. The pair of pin connecting portions 9, 9 are spaced apart along the rotation direction of the brake disc D. A pair of bottomed cylindrical pin sliding portions 25, 25 are integrally formed in the cylinder portion 23 of the brake caliper body 22, protruding radially outward toward both sides of the brake disc D. The pair of pin sliding portions 25 extend axially along the brake disc D.

[0034] A pair of sliding pins 7 are axially slidably inserted into each of the pair of pin sliding portions 25. Each pin sliding portion 25 is positioned inward of the pair of pin connecting portions 9 of the bracket 5. Furthermore, the pair of sliding pins 7 are axially slidably inserted into each of the pin sliding portions 25 from the outside. Each mounting bolt 17 is inserted into the through holes 18, 18 of each pin connecting portion 9, 9 and fixed to each sliding pin 7, 7. As a result, each sliding pin 7, 7 is fixed to each pin connecting portion 9, 9 by the mounting bolts 17, 17. Thus, as described above, the pair of inner brake blocks 2, outer brake blocks 3, and brake calipers 4 are axially movable and supported on the bracket 5 towards the brake disc D. It should be noted that reference numeral 19 is a pin cover having a corrugated portion that extends and retracts freely in a manner covering the sliding pins 7.

[0035] The brake caliper body 22, which is the main body of the brake caliper 4, includes: a cylindrical cylinder 23, which is disposed on the base end side opposite to the inner brake block 2 and opens opposite to the inner brake block 2; a pair of claw portions 24, 24, which extend outward from the cylinder 23 across the brake disc D and are opposite to the outer brake block 3 and are disposed on the front end side; and a pair of pin sliding portions 25, 25, which are provided to protrude radially outward from the cylinder 23 toward the two outer sides of the brake disc D.

[0036] The piston 28 is housed within the cylinder bore 26 of the cylinder 23 in a manner that prevents relative rotation with respect to the cylinder 23 but allows axial movement. The piston 28 presses against the inner brake block 2, forming a bottomed cylindrical shape. The piston 28 is housed within the cylinder bore 26 of the cylinder 23 with its bottom facing the inner brake block 2. The piston 28 is supported by an anti-rotation engagement between its bottom and the inner brake block 2, preventing relative rotation with respect to the cylinder bore 26 and, consequently, with respect to the brake caliper body 22.

[0037] A sealing member (not shown) is disposed on the inner circumferential surface of the cylinder bore 26 at the other end of the cylinder portion 23. The piston 28 is axially movable within the cylinder bore 26 in contact with this sealing member. A dust cover 30 is installed between the outer circumferential surface of the bottom side of the piston 28 and the inner circumferential surface of the cylinder bore 26 at the other end. These sealing members and the dust cover 30 prevent foreign objects from entering the cylinder bore 26 of the cylinder portion 23. A housing 32 is mounted at the bottom of the cylinder portion 23 of the brake caliper body 22. The open portion at one end of the housing 32 is airtightly sealed by a cover member 34. The housing 32 maintains airtightness. The housing 32 includes: a first housing portion 36, which houses the reduction mechanism 41 and brake holding mechanism 48 (described later) in a manner covering the outer circumference of the bottom of the cylinder portion 23; and a second housing portion 38, which is integrally connected to the first housing portion 36 in a manner parallel to the cylinder portion 23 and houses the electric motor 40 (described later).

[0038] Reference Figure 2 The brake caliper body 22 includes: an electric motor 40; a reduction mechanism 41 that reduces and amplifies the rotation from the electric motor 40 at a predetermined reduction ratio; a braking mechanism 42 that, along with the rotation of the reduction mechanism 41, presses the piston 28 against the inner brake block 2 to generate braking force; and brake holding mechanisms 43A to 43D of the first to fourth embodiments that hold the braking force generated by the braking mechanism 42. The electric motor 40 is a brushless DC motor having a rotor body (permanent magnet) and a stator, etc. It should be noted that the electric motor 40 may also be other known motors such as a brushed DC motor.

[0039] As described above, the electric motor 40 is housed in the second housing portion 38 of the housing 32. The rotation shaft 40A of the electric motor 40 extends within the first housing portion 36 of the housing 32. An electronic control unit 46 for controlling the rotation of the electric motor 40 is electrically connected to the electric motor 40. During braking in normal driving, the electronic control unit 46 controls the drive of the electric motor 40 based on detection signals from detection sensors (not shown) corresponding to the driver's request, various detection sensors (not shown) detecting various conditions requiring braking, the rotation angle detection unit 127 of the electric motor 40 (described later), and the thrust sensor (not shown).

[0040] Furthermore, the electronic control unit 46 is electrically connected to a parking brake switch 48, which is operated when the parking brake, as an example, is engaged / disengaged to maintain the vehicle's stopped state, and a parking brake pedal (not shown) that is operated to indicate parking action. In the electronic control unit 46, for example, when the parking brake is engaged, the energization and de-energization of the solenoid actuators 104 of the first to fourth brake holding mechanisms 43A to 43D (described later) are controlled, and the drive of the electric motor 40 is also controlled. It should be noted that the electronic control unit 46 can also engage the parking brake based on signals from the vehicle side, independent of the operation of the parking brake switch 48 and the parking brake pedal.

[0041] Reference Figure 2 The reduction mechanism 41 consists of a multi-stage gear reduction mechanism 51 and a planetary gear reduction mechanism 52. The multi-stage gear reduction mechanism 51 is composed of spur gears or helical gears. The multi-stage gear reduction mechanism 51 is housed within the first housing portion 36 of the housing 32. The multi-stage gear reduction mechanism 51 includes a first reduction gear 55, a second reduction gear 56, and a third reduction gear 57. These first to third reduction gears 55 to 57 are, for example, made of sintered or forged metal parts or resin molded parts. The first reduction gear 55 is formed into a cylindrical shape and is pressed into and fixed to the rotating shaft 40A of the electric motor 40.

[0042] The second reduction gear 56 has a shaft hole 59 extending axially through its radial center. A gear shaft 60 is inserted through the shaft hole 59 of the second reduction gear 56. The other end of the gear shaft 60 is integrally fixed to the wall of the first housing portion 36 near the second housing portion 38. As a result, the second reduction gear 56 is supported by the gear shaft 60 and can rotate freely. The second reduction gear 56 is constructed by integrally connecting a large-diameter gear 62 that meshes with the first reduction gear 55 and a small-diameter shaft gear 63 that extends concentrically from the large-diameter gear 62 to one end. The small-diameter shaft gear 63 of the second reduction gear 56 meshes with the third reduction gear 57.

[0043] The third reduction gear 57 consists of a large-diameter gear 66 that meshes with the small-diameter shaft gear 63 of the second reduction gear 56, and a small-diameter sun gear 67 that extends concentrically axially from the large-diameter gear 66. The sun gear 67 is part of the planetary gear reduction mechanism 52. One end of the large-diameter gear 66 of the third reduction gear 57 is connected to one end of the sun gear 67 via an annular wall portion 69. An annular space 71 is formed between the inner circumferential surface of the large-diameter gear 66 and the outer circumferential surface of the sun gear 67.

[0044] Reference Figure 1 and Figure 2The planetary gear reduction mechanism 52 is housed within the first housing portion 36 of the housing 32. The planetary gear reduction mechanism 52 includes a sun gear 67 of a third reduction gear 57, a plurality of (five in this embodiment) planetary gears 75, and an internal gear 76. Each planetary gear 75 and internal gear 76 is, for example, made of sintered or forged metal or resin-molded components. Each planetary gear 75 has: a gear 79 that meshes with the internal teeth 83 of the sun gear 67 and the internal gear 76; and a hole 80 through which a pin member 89, erected at one end from the bracket 86 (described later), is rotatably inserted. Each planetary gear 75 is arranged at equal circumferential intervals around the sun gear 67. Specifically, each planetary gear 75 is arranged at equal circumferential intervals within the annular space 71 between the inner circumferential surface of the large-diameter gear 66 of the third reduction gear 57 and the outer circumferential surface of the sun gear 67, and on the inner side of the internal teeth 83 of the internal gear 76 (described later). The gear 79 of each planetary gear 75 meshes with the internal teeth 83 of the sun gear 67 and the internal gear 76.

[0045] Reference Figure 1 and Figure 2 The internal gear 76 includes: internal teeth 83 that mesh with the gears 79 of each planetary gear 75; an annular wall portion 84 that extends continuously from one end of the internal teeth 83 toward the radial center, restricting the axial movement of each planetary gear 75; and a cylindrical wall portion 85 that extends from the internal teeth 83 toward the other end. The internal teeth 83 of the internal gear 76 are positioned between the inner circumferential surface of the large-diameter gear 66 of the third reduction gear 57 and each planetary gear 75. The annular wall portion 84 of the internal gear 76 is positioned between each planetary gear 75 and the annular wall portion 69 of the third reduction gear 57. Furthermore, the internal gear 76 is restricted from radial and axial movement by the cylindrical wall portion 58 and the annular wall portion 84, and is supported so that it cannot rotate relative to the housing 32.

[0046] A bracket 86 is disposed at the other end of the planetary gear reduction mechanism 52. The bracket 86 is composed of a circular plate-shaped portion 87 and a cylindrical portion 88 protruding from the radial center of the circular plate-shaped portion 87 toward the other end. In the circular plate-shaped portion 87 of the bracket 86, a plurality of pin members 89 are erected at equal intervals along the circumference toward one end. These pin members 89 are rotatably inserted into the holes 80 of each planetary gear 75. Furthermore, the inner circumferential surface of the cylindrical portion 88 of the bracket 86 engages with the outer circumferential surface of the main shaft 92 of the braking mechanism 42 (described later) in a manner that prevents relative rotation, for example, by spline engagement.

[0047] Reference Figure 1 and Figure 2The braking mechanism 42 is a rotary-to-linear conversion mechanism that converts the rotary motion from the electric motor 40 and the reduction mechanism 41 (multi-stage gear reduction mechanism 51 and planetary gear reduction mechanism 52), i.e., the rotary motion transmitted from each planetary gear 75 of the planetary gear reduction mechanism 52 to the main shaft 92 via the bracket 86, into linear motion relative to the linear motion member 94. The movement of the linear motion member 94 applies a thrust to the piston 28, causing the piston 28 to advance (move to the other end). The main shaft 92 is supported so that it can rotate relative to the cylinder 23.

[0048] The main shaft 92 is configured such that one end face faces the other end face of the sun gear 67 of the third reduction gear 57, and the other end extends rotatably within the cylinder bore 26 of the cylinder section 23. As described above, the main shaft 92 engages with the bracket 86 in a manner that prevents relative rotation between them. As a result, torque can be transmitted between the main shaft 92 and the bracket 86, and the rotation of each planetary gear 75 from the planetary gear reduction mechanism 52 is transmitted to the main shaft 92 via the bracket 86. Furthermore, if the main shaft 92 rotates with the rotation shaft 40A of the electric motor 40, the direct-acting member 94 advances toward the other end side through the action of the braking mechanism 42 (rotational direct-acting conversion mechanism), thereby advancing the piston 28. The piston 28 presses the inner brake block 2 against the brake disc D, generating braking force for the vehicle.

[0049] In addition, such as Figure 2 and Figure 3 As shown, a brake holding mechanism 43A-43D of the first embodiment is provided within the first housing portion 36 of the housing 32. The brake holding mechanisms 43A-43D of the first to fourth embodiments are used to hold the braking force generated by the brake mechanism 42. Firstly, based on... Figures 3 to 12 The brake holding mechanism 43A of the first embodiment is described in detail. (Refer to...) Figure 3 and Figure 4 The brake holding mechanism 43A of the first embodiment includes: a ratchet gear 97 fixed to the rotation shaft 40A of the electric motor 40 and the front end of the rotation shaft 40A; a limiting mechanism 98 that, when the rotation direction of the rotation shaft 40A and the ratchet gear 97 is set to one direction by the brake mechanism 42 pressing the inner brake block 2 and the outer brake block 3 against the brake disc D, limits the rotation of the ratchet gear 97 in the other direction; and a clutch unit 99 that, when the ratchet gear 97 is limited to the other direction by the limiting mechanism 98, allows relative rotation of the rotation shaft 40A in one direction and limits relative rotation in the other direction. It should be noted that, in the following description, the one direction is referred to as the application direction (clockwise direction centered on the rotation shaft 40A in each figure), and the other direction is referred to as the release direction (counterclockwise direction centered on the rotation shaft 40A in each figure).

[0050] Reference Figure 3 The ratchet gear 97 is cylindrical. The ratchet gear 97 is fixed to the front end of the rotating shaft 40A of the electric motor 40 via a one-way clutch 125 (described later). In other words, the ratchet gear 97 and the rotating shaft 40A are coaxially (concentrically) arranged. The ratchet gear 97 is equivalent to a rotating component. The ratchet gear 97 is located at one end closer to the first reduction gear 55. The ratchet gear 97 has a plurality of gear portions 101 arranged at intervals along its circumference. Each gear portion 101, when viewed from above, has an inclined surface 102 that abuts against the inclined surface 118 of the pawl portion 114 (described later), and is formed as a generally rectangular shape when viewed from above, slightly inclined in the release direction. The limiting mechanism 98 includes: a solenoid actuator 104; a retaining member 105 that advances by energizing the solenoid actuator 104, limiting the rotation of the ratchet gear 97 in the release direction; and a compression coil spring 106 that applies force to the retaining member 105 in a direction away from the ratchet gear 97. The solenoid actuator 104 is equivalent to the driving source, and the compression helical spring 106 is equivalent to the elastic component.

[0051] The solenoid actuator 104 includes a main body 109 and a plunger 110 that moves forward and backward toward the main body 109. The plunger 110 is cylindrical. An annular flange 112 is provided at the front end of the plunger 110. The solenoid actuator 104 is a traction type, in which the plunger 110 moves toward the main body 109 by energizing it. The solenoid actuator 104 operates based on commands from the electronic control unit 46.

[0052] The retaining component 105 has a complex shape and integrally includes: a claw portion 114, which can engage with the gear portion 101 of the ratchet gear 97; a plunger connecting portion 115, which connects to the inner side of the annular flange portion 112 of the plunger 110; and a curved portion 116, which is disposed between the claw portion 114 and the plunger connecting portion 115 and extends in a curved shape when viewed from above. The claw portion 114 is shaped to engage with the gear portion 101 of the ratchet gear 97 by abutting against each other's inclined surfaces 118, 102. Specifically, the claw portion 114 has an inclined surface 118 that abuts against the inclined surface 102 of the gear portion 101 of the ratchet gear 97 when viewed from above, and its overall shape is slightly inclined towards the application direction of the ratchet gear 97.

[0053] It should be noted that after the inclined surface 118 of the pawl portion 114 of the retaining member 105 abuts and engages with the inclined surface 102 of the gear portion 101 of the ratchet gear 97, even if a reaction force (relative to the braking force) is applied to the ratchet gear 97 in the release direction, the pawl portion 114 of the retaining member 105 and the gear portion 101 of the ratchet gear 97 will not disengage, and the retaining member 105 will not retract due to the force of the compression coil spring 106. A shaft portion 120 extending in the same direction as the plunger 110 of the solenoid actuator 104 is integrally connected to the pawl portion 114. A bent portion 116 is integrally connected to the end of the shaft portion 120 opposite to the pawl portion 114. The bent portion 116 extends in a U-shape when viewed from above, folded back from the shaft portion 120, with its open side facing the ratchet gear 97. A plunger connecting portion 115 is integrally connected to the end of the bent portion 116. The plunger connection portion 115 is formed in a semi-circular arc shape to support the outer peripheral surface of the inner side of the annular flange portion 112 of the plunger 110 in a circumferential manner from the side of the cover member 34. A plate-shaped pressing portion 122 extending toward the electric motor 40 side (the other end side) is integrally connected to the shaft portion 120.

[0054] Furthermore, referring to Figure 3 The solenoid actuator 104 is housed and fixed within the first housing portion 36. Viewed from above, the solenoid actuator 104 is positioned to the side of the rotation shaft 40A of the electric motor 40, with its main body 109 positioned to the side of the second reduction gear 56 and the third reduction gear 57, and its plunger 110 positioned away from the second reduction gear 56 and the third reduction gear 57. In other words, the axial direction of the main body 109 and the plunger 110 of the solenoid actuator 104 is perpendicular to the rotation shaft 40A of the electric motor 40 and extends along the length direction of the cover member 34 (the length direction of the first housing portion 36). That is, the direction of movement (forward and backward) of the plunger 110 of the solenoid actuator 104, and consequently the direction of movement of the holding member 105, is perpendicular to the rotation shaft 40A of the electric motor 40 and along the length direction of the cover member 34 (the length direction of the first housing portion 36). The retaining member 105 is supported within the first housing portion 36 and is movable freely along the direction of action (forward and backward directions) of the plunger 110.

[0055] Also refer to Figure 2A compression coil spring 106 is disposed in the receiving recess 37 of the first housing portion 36. The axial direction of the compression coil spring 106 is aligned with the operating direction (forward and backward direction) of the plunger 110 of the solenoid actuator 104. One end of the compression coil spring 106 is configured to abut against the wall surface 37A of the receiving recess 37 near the ratchet gear 97. In addition, a retaining member 105 is disposed on the cover member 34 side (one end side) of the compression coil spring 106. Specifically, the retaining member 105 is configured such that its claw portion 114 faces each gear portion 101 (outer peripheral surface) of the ratchet gear 97, and its shaft portion 120 overlaps with the compression coil spring 106 when viewed from above, and its pressing portion 122 abuts against the other end of the compression coil spring 106.

[0056] Furthermore, the plunger connection portion 115 of the retaining member 105 is connected to the outer peripheral surface of the annular flange portion 112 of the plunger 110 in a manner that surrounds the cover member 34. When the parking brake is activated, such as when the vehicle is stationary, the plunger 110 of the solenoid actuator 104 is energized, causing it to advance towards the main body portion 109. Consequently, the retaining member 105 advances towards each gear portion 101 (outer peripheral surface) of the ratchet gear 97 in a manner that counteracts the force of the compression coil spring 106, and its pawl portion 114 engages with the gear portion 101. At this time, after the pawl 114 (inclined surface 118) of the retaining member 105 engages with the gear portion 101 (inclined surface 102) of the ratchet gear 97, a reaction force in the release direction (a reaction force relative to the braking force) is applied to the ratchet gear 97. Therefore, even if the power supply to the solenoid actuator 104 is stopped and the force of the compression coil spring 106 is applied, the engagement between the pawl 114 of the retaining member 105 and the gear portion 101 of the ratchet gear 97 will not be released, and the braking force can be maintained.

[0057] Reference Figure 3 The clutch unit 99 comprises a one-way clutch 125 disposed between the outer peripheral surface of the rotating shaft 40A of the electric motor 40 and the inner peripheral surface of the ratchet gear 97. The one-way clutch 125 allows relative rotation of the rotating shaft 40A relative to the ratchet gear 97 in the application direction, and restricts relative rotation in the release direction. The one-way clutch 125 may be a coil spring clutch, a cam clutch, or the like. It should be noted that using a coil spring clutch in the one-way clutch 125 reduces costs. Furthermore, using a cam clutch in the one-way clutch 125 reduces torque loss when applying pressure to the clutch.

[0058] It should be noted that, referring to Figure 2A rotation angle detection unit 127 is provided at one end of the ratchet gear 97 of the brake holding mechanism 43A in the first embodiment. The rotation angle detection unit 127 detects the rotation angle of the rotation shaft 40A of the electric motor 40. The rotation angle detection unit 127 includes a magnet component 129 and a magnetic detection IC chip (not shown). The magnet component 129 is supported at one end of the rotation shaft 40A of the electric motor 40. The magnetic detection IC chip is arranged opposite to one end of the magnet component 129. The magnetic detection IC chip detects changes in the magnetic field generated by the magnet component 129. The magnetic detection IC chip is mounted on a control board 47. The control board 47 is electrically connected to an electronic control unit 46. Furthermore, by using the magnetic detection IC chip to detect changes in the magnetic flux from the magnet component 129 that rotates along with the rotation shaft 40A, the electronic control unit 46, including the control board 47, calculates and detects the rotation angle of the rotation shaft 40A of the electric motor 40.

[0059] Next, in the disc brake 1 of this embodiment, the function of braking and brake release during normal driving, that is, the control method of the electronic control unit 46 during braking and brake release during normal driving, will be explained.

[0060] During braking in normal driving, the electric motor 40 is driven according to instructions from the electronic control unit 46. The rotation of the rotating shaft 40A of the electric motor 40 in the applied direction is transmitted to the planetary gear reduction mechanism 52 via the reduction mechanism 41, namely the multi-stage gear reduction mechanism 51 (first to third reduction gears 55 to 57). As the sun gear 67 of the planetary gear reduction mechanism 52 rotates in the applied direction, each planetary gear 70 rotates on its own axis of rotation and revolves around the axis of rotation of the sun gear 67, thereby rotating the bracket 86. In other words, the rotation from the electric motor 40 in the applied direction is reduced and amplified at a predetermined reduction ratio via the multi-stage gear reduction mechanism 51 and the planetary gear reduction mechanism 52 of the reduction mechanism 41 and transmitted to the bracket 86. Furthermore, the rotation from the bracket 86 is transmitted to the main shaft 92.

[0061] Next, as the main shaft 92 rotates along with the bracket 86, the direct-acting component 94 advances due to the action of the braking mechanism 42 (rotational direct-acting conversion mechanism 43), and the piston 28 advances as well. The advance of the piston 28 presses the inner brake block 2 against the brake disc D. Furthermore, the reaction force relative to the pressing force of the piston 28 on the inner brake block 2 causes the brake caliper body 22 to move inward relative to the bracket 5, pressing the outer brake block 3 against the brake disc D via the pawls 24, 24. As a result, the brake disc D is clamped by the pair of inner brake blocks 2 and outer brake blocks 3, generating friction and thus producing braking force for the vehicle.

[0062] On the other hand, when the brake is released, according to the command from the electronic control unit 46, the rotating shaft 40A of the electric motor 40 rotates in the release direction, and this rotation in the release direction is transmitted to the main shaft 92 via the multi-stage gear reduction mechanism 51 and the planetary gear reduction mechanism 52 of the reduction mechanism 41. As a result, as the main shaft 92 rotates in the release direction, the direct-acting component 94 retracts to its initial position through the action of the braking mechanism 42 (rotational direct-acting conversion mechanism), releasing the braking force of the pair of inner brake blocks 2 and outer brake blocks 3 on the brake disc D.

[0063] Next, the function of the parking brake in the disc brake 1 of this embodiment, as an example of maintaining the vehicle's stopped state, will be explained, specifically the control method of the electronic control unit 46 during parking brake operation. First, when the parking brake switch 48 and parking brake pedal are operated, the solenoid actuator 104 of the limiting mechanism 98 is energized according to the command from the electronic control unit 46. Then, from... Figure 4 The initial state shown ( Figure 12 From the (1) range, the plunger 110 of the solenoid actuator 104 moves toward the main body 109, and the holding member 105 moves toward each gear portion 101 (outer peripheral surface) of the ratchet gear 97.

[0064] Thus, when the plunger 110 of the solenoid actuator 104 advances toward the main body 109 and the holding member 105 advances toward each gear portion 101 (outer peripheral surface) of the ratchet gear 97, as... Figure 5 As shown, this results in an incomplete engagement state where the front end of the pawl 114 of the retaining member 105 interferes with the adjacent gear portions 101, 101 of the ratchet gear 97, or as... Figure 6 As shown, an incomplete engagement state occurs where the front end of the pawl 114 of the retaining member 105 interferes with the top of any gear portion 101 of the ratchet gear 97. Therefore, referring to... Figure 7 as well as Figure 12 Within the range of (2), according to the instruction from the electronic control unit 46, while maintaining the energization of the solenoid actuator 104 of the limiting mechanism 98, the rotating shaft 40A of the electric motor 40 is rotated in the release direction at an appropriate time. Therefore, referring to... Figure 7 The ratchet gear 97 rotates together with the rotating shaft 40A in the release direction via the one-way clutch 125, thereby ensuring that the pawl portion 114 of the component 105 and the gear portion 101 of the ratchet gear 97 can properly engage.

[0065] Furthermore, referring to Figure 8 and Figure 12Within the range of (3), according to the command from the electronic control unit 46, while maintaining the energization of the solenoid actuator 104 of the limiting mechanism 98, the rotating shaft 40A of the electric motor 40 rotates in the application direction, similar to normal braking. Thus, through the action of the one-way clutch 125, only the rotating shaft 40A rotates in the application direction, and this rotation is transmitted to the carrier 86 via the multi-stage gear reduction mechanism 51 and planetary gear reduction mechanism 52 of the reduction mechanism 41. Next, as the main shaft 92 rotates with the rotation from the carrier 86, the piston 28 advances through the action of the braking mechanism 42, and the brake disc D is clamped by a pair of inner brake blocks 2 and outer brake blocks 3 to generate braking force. Afterwards, when the thrust sensor detects that the predetermined braking force has been reached, the energization of the electric motor 40 and the solenoid actuator 104 is stopped.

[0066] At this point, as mentioned above, refer to Figure 9 as well as Figure 12 (4) Because a reaction force (relative to the braking force) is applied to the ratchet gear 97 in the release direction, even if the solenoid actuator 104 is de-energized and the compression spring 106 is applied, the engagement between the pawl 114 of the holding member 105 and the gear portion 101 of the ratchet gear 97 will not be disengaged, thereby maintaining the braking force. Thus, the braking state can be maintained when the electric motor 40 and the solenoid actuator 104 are de-energized.

[0067] Then, refer to Figure 12 The shift of the "thrust" within the range of (4) is such that when the thrust sensor detects a decrease in the braking force (thrust) relative to the inner brake block 2 and the outer brake block 3 on the disc brake D by an amount equivalent to the thermal contraction of the inner brake block 2 and the outer brake block 3, reference is made. Figure 8 and Figure 12 Within the range of (5), according to the command (re-clamping command) from the electronic control unit 46, a rotational force is increased in the applied direction on the rotating shaft 40A of the electric motor 40. Thus, through the action of the one-way clutch 125, the rotational force from the rotating shaft 40A is not transmitted to the ratchet gear 97, but is transmitted to the bracket 86 via the multi-stage gear reduction mechanism 51 and the planetary gear reduction mechanism 52 of the reduction mechanism 41. Through the action of the braking mechanism 42, the braking force of a pair of inner brake blocks 2 and outer brake blocks 3 on the brake disc D is increased, and the power supply to the electric motor 40 and the solenoid actuator 104 is stopped when the specified braking force is reached.

[0068] It should be noted that, referring to Figure 12When the "sole" in the range of (5) is pushed, according to the command from the electronic control unit 46, the rotational force of the rotating shaft 40A of the electric motor 40 is increased in the application direction, so the reaction force (reaction force relative to the braking force) in the release direction of the ratchet gear 97 disappears, and the engagement between the gear part 101 of the ratchet gear 97 and the pawl part 114 of the retaining member 105 is loosened. However, according to the command from the electronic control unit 46, the solenoid actuator 104 is energized, and a thrust is applied to the retaining member 105 in the direction of the ratchet gear 97. Thus, the engagement between the pawl part 114 of the retaining member 105 and the gear part 101 of the ratchet gear 97 is not released due to the force of the compression coil spring 106.

[0069] Next, with the parking brake released, refer to Figure 10 and Figure 12 Within the range of (7), according to the instruction from the electronic control unit 46, the solenoid actuator 104 is not energized, but the electric motor 40 is given a rotational force in the application direction. As a result, the reaction force (reaction force relative to the braking force) in the release direction of the ratchet 97 disappears, the ratchet 97 becomes free in the rotation direction, the engagement between the gear portion 101 of the ratchet 97 and the pawl portion 114 of the retaining member 105 is relaxed, and therefore, by the force of the compression coil spring 106, the retaining member 105 and the pawl portion 114 move backward away from the ratchet 97 and return to the initial position, and the rotation restriction of the ratchet 97 is released.

[0070] Next, refer to Figure 11 and Figure 12 Within the range of (8), similar to normal brake release, according to the command from the electronic control unit 46, the rotating shaft 40A of the electric motor 40 rotates in the release direction, and this rotation is transmitted to the main shaft 92 via the multi-stage gear reduction mechanism 51 and the planetary gear reduction mechanism 52 of the reduction mechanism 41. As a result, as the main shaft 92 rotates in the release direction, the direct-acting component 94 retracts to its initial position through the action of the braking mechanism 42 (rotational direct-acting conversion mechanism), releasing the braking force of the pair of inner brake blocks 2 and outer brake blocks 3 on the brake disc D.

[0071] In the brake holding mechanism 43A of the first embodiment described above, it is particularly provided with: a limiting mechanism 98 that limits the rotation of the ratchet gear 97 in the release direction; and a clutch unit 99 that, while limiting the rotation of the ratchet gear 97 in the release direction by the limiting mechanism 98, allows the rotation of the rotating shaft 40A of the electric motor 40 in the application direction.

[0072] Furthermore, in the brake holding mechanism 43A of the first embodiment, for example, when the parking brake is actuated or re-clamped, while the rotation of the ratchet gear 97 in the release direction is restricted by the limiting mechanism 98, the rotation of the rotating shaft 40A of the electric motor 40 in the application direction is allowed by the clutch unit 99, thereby generating or increasing braking force. Thus, braking is not required with a braking force greater than the minimum braking force (thrust) needed to hold the vehicle, as was previously the case. As a result, there is no need to improve the performance of the electric motor 40, nor is it necessary to increase the size of the reduction mechanism 41, braking mechanism 42, etc., thus suppressing cost increases and the overall size of the device (disc brake 1).

[0073] Furthermore, in the brake holding mechanism 43A of the first embodiment, especially during re-clamping, it is not necessary to temporarily disengage the engagement between the locking pawl and the ratchet gear as in the past. Therefore, the force amplification can be stopped at the moment the required braking force is reached, regardless of the position of each gear portion 101 of the ratchet gear 97. As a result, it is not necessary to perform control such as disengaging the locking pawl from the ratchet gear and re-engaging it during re-clamping, and the control until the required braking force is obtained is also simplified. Therefore, relative to re-clamping, reliability can be improved.

[0074] Furthermore, in the brake holding mechanism 43A of the first embodiment, the clutch unit 99 is composed of a one-way clutch 125 disposed between the outer peripheral surface of the rotating shaft 40A of the electric motor 40 and the inner peripheral surface of the ratchet gear 97, which allows the rotating shaft 40A to rotate relative to the ratchet gear 97 in the application direction and restricts relative rotation in the release direction. This results in a better layout and helps to prevent the overall size of the device from increasing.

[0075] Next, based on Figure 13 Also refer to Figure 2 The brake holding mechanism 43B of the second embodiment will be described in detail. It should be noted that when describing the brake holding mechanism 43B of the second embodiment, only the differences from the brake holding mechanism 43A of the first embodiment will be described.

[0076] In the brake holding mechanism 43B of the second embodiment, the pawl portion 114 of the holding member 105 includes: an inclined portion 150, which, when viewed from above, is inclined in a direction toward the ratchet gear 97 and gradually away from the main body portion 109 of the solenoid actuator 104; an extension portion 151, which extends from the front end of the inclined portion 150 toward the ratchet gear 97; and a pawl-side limiting portion 152, which protrudes from the front end of the extension portion 151 toward the gear portion 101 of the ratchet gear 97. In other words, the pawl-side limiting portion 152 protrudes toward the application direction of the ratchet gear 97.

[0077] A claw-side bend 153, slightly curved toward the shaft portion 120 of the retaining member 105, is formed at the front end of the claw-side limiting portion 152. It should be noted that the claw-side limiting portion 152 and the claw-side bend 153 correspond to a locking piece. On the other hand, the gear portion 101 of the ratchet gear 97 has: a main body portion 155, which is generally rectangular in plan view; and a tooth-side limiting portion 156, which protrudes from the outer periphery of the main body portion 155 toward the release direction. A tooth-side bend 157, slightly curved toward the outer peripheral surface of the ratchet gear 97, is formed at the front end of the tooth-side limiting portion 156. It should be noted that the tooth-side limiting portion 156 and the tooth-side bend 157 correspond to an engaging portion.

[0078] Furthermore, in the brake holding mechanism 43B of the second embodiment, for example, when the parking brake is actuated, the solenoid actuator 104 of the limiting mechanism 98 is energized according to the command from the electronic control unit 46. As a result, the plunger 110 of the solenoid actuator 104 advances toward the main body 109, and the holding member 105 advances toward each gear portion 101 (outer peripheral surface) of the ratchet gear 97. At this time, sometimes... Figure 6 The retaining member 105, as shown, is in a partially engaged state with the gear portion 101 of the ratchet gear 97. Based on instructions from the electronic control unit 46, the rotating shaft 40A of the electric motor 40 is rotated in the release direction at an appropriate time. Thus, the ratchet gear 97 rotates together with the rotating shaft 40A via the one-way clutch 125 in the release direction, thereby becoming... Figure 5 The retaining member 105, as shown, is engaged with the gear portion 101 of the ratchet gear 97. In this state, the solenoid actuator 104 is kept energized, and as in normal braking, the rotating shaft 40A of the electric motor 40 rotates in the application direction, and the brake disc D is clamped by a pair of inner brake blocks 2 and outer brake blocks 3 to generate braking force.

[0079] Subsequently, when the thrust sensor detects that the prescribed braking force has been reached, based on the command from the electronic control unit 46, the electric motor 40 increases the ratchet gear 97 in the application direction by at least an amount equivalent to the overlap between the pawl-side limiting portion 152 of the retaining member 105 and the tooth-side limiting portion 156 of the ratchet gear 97. Next, by rotating the rotation shaft 40A of the electric motor 40 in the release direction, the ratchet gear 97 also rotates in the release direction via the action of the one-way clutch 125, causing the pawl-side limiting portion 152 of the pawl portion 114 of the retaining member 105 and the tooth-side limiting portion 156 of the gear portion 101 of the ratchet gear 97 to engage in an overlapping manner. Furthermore, if the power supply to the electric motor 40 is stopped, and the power supply to the solenoid actuator 104 is also stopped, the force of the compressed helical spring 106 keeps the component 105 slightly retracted, thereby keeping the claw-side bent portion 153 of the claw portion 114 of the component 105 engaged with the tooth-side bent portion 157 of the gear portion 101 of the ratchet gear 97 in abutting manner, thus maintaining its braking state.

[0080] Next, in the brake holding mechanism 43B of the second embodiment, when a re-clamping command is output from the electronic control unit 46, a rotational force in the application direction is increased on the rotating shaft 40A of the electric motor 40, thereby increasing the braking force of the pair of inner brake blocks 2 and outer brake blocks 3 on the brake disc D. Power to the electric motor 40 is stopped when the predetermined braking force is reached. During this re-clamping, by increasing the rotational force in the application direction on the rotating shaft 40A of the electric motor 40, the reaction force in the release direction of the ratchet gear 97 (the reaction force relative to the braking force) disappears, but the solenoid actuator 104 is not energized, maintaining the state in which the claw-side bend 153 of the claw portion 114 of the holding member 105 and the tooth-side bend 157 of the gear portion 101 of the ratchet gear 97 abut against each other and are engaged. That is, during this re-clamping, as in the brake holding mechanism 43A of the first embodiment, the solenoid actuator 104 is energized (see...). Figure 12 (5) The "spindle" within the range of the "spindle" is pushed, and no thrust is applied to the retaining member 105 in the direction of the ratchet gear 97, so that the engagement of the pawl 114 of the retaining member 105 with the gear portion 101 of the ratchet gear 97 can be maintained.

[0081] Next, in the brake holding mechanism 43B of the second embodiment, when the parking brake is released, the solenoid actuator 104 is energized according to the command from the electronic control unit 46 to advance the holding member 105, so that the claw-side bend 153 of the claw portion 114 of the holding member 105 does not contact the tooth-side bend 157 of the gear portion 101 of the ratchet gear 97. Then, after increasing the rotational force of the electric motor 40 in the applied direction by an amount equivalent to the overlap between the claw-side restriction portion 152 of the holding member 105 and the tooth-side restriction portion 156 of the ratchet gear 97, the energization of the solenoid actuator 104 is stopped.

[0082] Therefore, the reaction force (relative to the braking force) in the release direction of the ratchet gear 97 disappears, and the engagement between the pawl 114 of the retaining member 105 and the gear portion 101 of the ratchet gear 97 is released by the force of the compressed coil spring 106. Furthermore, by the force of the compressed coil spring 106, the retaining member 105 and its pawl 114 retract away from the ratchet gear 97 and return to their initial position, releasing the rotational restriction of the ratchet gear 97. Afterwards, as with normal brake release, according to the command from the electronic control unit 46, the rotation shaft 40A of the electric motor 40 rotates in the release direction, thereby causing the direct-acting member 94 to retract to its initial position through the action of the braking mechanism 42 (rotational direct-acting conversion mechanism), releasing the braking force of the pair of inner brake blocks 2 and outer brake blocks 3 on the brake disc D.

[0083] In the brake holding mechanism 43B of the second embodiment described above, especially during re-clamping, the claw-side bend 153 of the claw portion 114 of the holding member 105 and the tooth-side bend 157 of the gear portion 101 of the ratchet gear 97 are engaged with each other. Therefore, unlike the brake holding mechanism 43A of the first embodiment, it does not energize the solenoid actuator 104, i.e., it does not energize the solenoid actuator 104 (see reference). Figure 12 (5) The "sowary" within its range is not pushed, and no thrust is applied to the retaining member 105 in the direction of the ratchet gear 97, so that the engagement between the pawl portion 114 of the retaining member 105 and the gear portion 101 of the ratchet gear 97 can be maintained. Therefore, especially during reclamping, even if the solenoid actuator 104 fails, such as the parking brake (braking force) will not disappear, thus improving reliability.

[0084] Next, based on Figure 14 Also refer to Figure 2 The brake holding mechanism 43C of the third embodiment will be described in detail. It should be noted that when describing the brake holding mechanism 43C of the third embodiment, only the differences from the brake holding mechanism 43A of the first embodiment will be described.

[0085] In the brake holding mechanism 43C of the third embodiment, the pawl portion 114 of the holding member 105, when viewed from above, is a generally triangular shape having a pawl-side end face 159 extending along the operating direction of the holding member 105 and a pawl-side inclined surface 160 extending toward the pawl-side end face 159 in a manner that gradually approaches the ratchet gear 97. On the other hand, a plurality of gear portions 101 of the ratchet gear 97 are continuously provided circumferentially on the outer peripheral surface of the ratchet gear 97. The gear portions 101 are formed with a pointed shape that guides the tooth-side inclined surface 162 of the pawl portion 114 of the holding member 105 when viewed from above. The generally triangular space 164 formed between adjacent gear portions 101, 101 of the ratchet gear 97 is substantially consistent with the generally triangular shape of the pawl portion 114 of the holding member 105 when viewed from above.

[0086] Furthermore, in the brake holding mechanism 43C of the third embodiment, for example, when the parking brake is actuated, the solenoid actuator 104 of the limiting mechanism 98 is energized according to the instruction from the electronic control unit 46. As a result, the plunger 110 of the solenoid actuator 104 moves toward the main body 109, and the holding member 105 moves toward each gear portion 101 (outer peripheral surface) of the ratchet gear 97.

[0087] Thus, when the retaining member 105 advances toward each gear portion 101 (outer peripheral surface) of the ratchet gear 97 and the pawl portion 114 of the retaining member 105 reaches each gear portion 101 of the ratchet gear 97, the pawl-side inclined surface 160 of the pawl portion 114 of the retaining member 105 is guided by the tooth-side inclined surface 162 of the gear portion 101 of the ratchet gear 97, and the ratchet gear 97 rotates slightly in the release direction, thereby engaging the entire pawl portion 114 of the retaining member 105 with the space 164 between the adjacent gear portions 101, 101 of the ratchet gear 97 without gap. Next, according to the instructions from the electronic control unit 46, while maintaining the solenoid actuator 104 of the limiting mechanism 98 energized, as in normal braking, when the rotating shaft 40A of the electric motor 40 rotates in the application direction, only the rotating shaft 40A rotates in the application direction through the action of the one-way clutch 125, and the brake disc D is clamped by a pair of inner brake blocks 2 and outer brake blocks 3 to generate braking force.

[0088] Subsequently, when the thrust sensor detects that the predetermined braking force has been reached, the power supply to the electric motor 40 and the solenoid actuator 104 is stopped. At this time, similar to the brake holding mechanism 43A of the first embodiment, a reaction force in the release direction (a reaction force relative to the braking force) is applied to the ratchet gear 97. Therefore, even if the power supply to the solenoid actuator 104 is stopped and the force of compressing the helical spring 106 is applied, the engagement between the pawl 114 of the holding member 105 and the gear portions 101, 101 of the ratchet gear 97 will not be disengaged, and the braking force can be maintained. Thus, the braking state can be maintained when the power supply to the electric motor 40 and the solenoid actuator 104 is stopped.

[0089] It should be noted that the function of the brake holding mechanism 43C in the third embodiment when the electronic control unit 46 outputs a re-clamping command and when the parking brake is released is the same as that of the brake holding mechanism 43A in the first embodiment, so detailed descriptions are omitted here.

[0090] In the brake holding mechanism 43C of the third embodiment described above, when the solenoid actuator 104 of the limiting mechanism 98 is energized, the holding member 105 moves toward each gear portion 101 (outer peripheral surface) of the ratchet gear 97. When the pawl portion 114 of the holding member 105 reaches each gear portion 101 of the ratchet gear 97, the pawl-side inclined surface 160 of the pawl portion 114 of the holding member 105 is guided by the tooth-side inclined surface 162 of the gear portion 101 of the ratchet gear 97, and the ratchet gear 97 rotates slightly in the release direction, thereby engaging the entire pawl portion 114 of the holding member 105 with the space 164 between the adjacent gear portions 101, 101 of the ratchet gear 97 without gap.

[0091] Furthermore, in the brake holding mechanism 43C of the third embodiment, as in the brake holding mechanism 43A of the first embodiment, no problem occurs when the holding member 105 is advanced by energizing the solenoid actuator 104. Figure 5 and Figure 6 Even with the incomplete engagement of the pawl 114 of the retaining member 105 with the gear portion 101 of the ratchet gear 97, the space 164 between the adjacent gear portions 101, 101 of the ratchet gear 97 can be properly engaged regardless of the phase of the ratchet gear 97. Therefore, unlike the brake retaining mechanism 43A of the first embodiment, there is no need for the electronic control unit 46 to control the proper engagement of the pawl 114 of the retaining member 105 with the gear portion 101 of the ratchet gear 97, simplifying the control of the electronic control unit 46 and improving reliability.

[0092] Next, based on Figure 15 and Figure 16Also refer to Figure 2 The brake holding mechanism 43D of the fourth embodiment will be described in detail. It should be noted that when describing the brake holding mechanism 43D of the fourth embodiment, only the differences from the brake holding mechanism 43A of the first embodiment will be described.

[0093] Reference Figure 15 In the brake holding mechanism 43D of the fourth embodiment, there is no ratchet gear 97 with multiple gear sections 101 as in the brake holding mechanism 43A of the first embodiment, but instead there is a cylindrical rotating body 170 with friction members 171 provided on its entire outer peripheral surface. Of course, a one-way clutch 125 is installed between the outer peripheral surface of the rotating shaft 40A of the electric motor 40 and the inner peripheral surface of the rotating body 170.

[0094] On the other hand, unlike the brake holding mechanism 43A of the first embodiment, the retaining member 105 does not have a claw portion 114. The front end face of the shaft portion 120 of the retaining member 105, which faces the outer peripheral surface (friction member 171) of the rotating body 170, is formed as a curved surface 173 with the same curvature as the outer peripheral surface of the rotating body 170 including the friction member 171. That is, when the solenoid actuator 104 is energized to move the retaining member 105 forward, the curved surface 173 of the shaft portion 120 of the retaining member 105 abuts against the friction member 171 of the rotating body 170. In addition, the shaft portion 120 of the retaining member 105 is supported between the opposing wall portions 36A, 36A of the first housing portion 36 so that it can slide freely along the operating direction (forward and backward direction) of the plunger 110.

[0095] Furthermore, in the brake holding mechanism 43D of the fourth embodiment, for example, when the parking brake is actuated, the solenoid actuator 104 of the limiting mechanism 98 is energized according to the command from the electronic control unit 46. As a result, the plunger 110 of the solenoid actuator 104 advances toward the main body 109, and the holding member 105 advances toward the friction member 171 (outer peripheral surface) of the rotating body 170. At this time, the shaft portion 120 of the holding member 105 advances while sliding along the opposing wall portions 36A, 36A of the first housing portion 36.

[0096] Furthermore, the retaining member 105 moves towards the rotating body 170, causing the curved surface 173 of the shaft portion 120 of the retaining member 105 to abut against the friction element 171 of the rotating body 170. Next, according to instructions from the electronic control unit 46, while maintaining energization to the solenoid actuator 104 of the limiting mechanism 98, similar to normal braking, when the rotating shaft 40A of the electric motor 40 rotates in the application direction, only the rotating shaft 40A rotates in the application direction via the action of the one-way clutch 125, and the brake disc D is clamped by a pair of inner brake blocks 2 and outer brake blocks 3 to generate braking force. Then, when the thrust sensor detects that the predetermined braking force has been reached, energization to the electric motor 40 and the solenoid actuator 104 is stopped.

[0097] At this time, similar to the brake holding mechanism 43A of the first embodiment, a reaction force in the release direction (a reaction force relative to the braking force) is applied to the rotating body 170, and a torque in the release direction is applied to the shaft portion 120 of the holding member 105. Furthermore, the circumferential end of the curved surface 173 of the shaft portion 120 of the holding member 105 bears the reaction force in the release direction of the rotating body 170 (an increase in friction), and a wall portion 36A of the first housing portion 36 (in...) Figure 15 (b) The lower wall portion 36A) bears the torque (increased friction) on the shaft portion 120 of the retaining member 105, thereby overcoming the force of the compression coil spring 106. The engagement between the curved surface 173 of the shaft portion 120 of the retaining member 105 and the friction element 171 of the rotating body 170 is not released, thus maintaining the braking force. Therefore, the braking state can be maintained when the electric motor 40 and the solenoid actuator 104 are not energized.

[0098] It should be noted that the function of the brake holding mechanism 43D in the fourth embodiment when the electronic control unit 46 outputs a re-clamping command and when the parking brake is released is the same as that of the brake holding mechanism 43A in the first embodiment, so detailed descriptions are omitted here.

[0099] In the brake holding mechanism 43D of the fourth embodiment described above, the gear portions 101 are not formed on the outer peripheral surface of the rotating body 170. During braking, the reaction force in the release direction of the rotating body 170 is borne by the circumferential end of the curved surface 173 of the shaft portion 120 of the holding member 105, and the torque on the shaft portion 120 of the holding member 105 is borne by a wall portion 36A of the first housing portion 36. As a result, the engagement between the curved surface 173 of the shaft portion 120 of the holding member 105 and the friction member 171 of the rotating body 170 is not released, thus maintaining the braking force. Therefore, in the brake holding mechanism 43D of the fourth embodiment, similar to the brake holding mechanism 43C of the third embodiment, the control in the electronic control unit 46 for properly engaging the pawl portion 114 of the holding member 105 with the gear portion 101 of the ratchet gear 97 (brake holding mechanism 43A of the first embodiment) is not required. This simplifies the control of the electronic control unit 46 and improves reliability.

[0100] It should be noted that in the brake holding mechanism 43D of the fourth embodiment, the shaft portion 120 of the holding member 105 is supported between the opposing wall portions 36A, 36A of the first housing portion 36 so that it can slide freely along the operating direction of the plunger 110, but if Figure 16 As shown, in order to reduce the sliding resistance of the retaining member 105 during forward and backward movement, a wall portion 36A can be provided on the shaft portion 120 of the retaining member 105. Figure 16 (b) In the first protrusion 175 protruding from the lower wall portion 36A and towards the other wall portion 36A (in Figure 15 In (b), a second protrusion 176 is provided protruding from the upper wall portion 36A. Furthermore, when the retaining member 105 moves forward and backward, the first protrusion 175 of the retaining member 105 slides relative to one wall portion 36A, and the second protrusion 176 of the retaining member 105 slides relative to the other wall portion 36A. Preferably, the first protrusion 175 is positioned closer to the rotating body 170 than the second protrusion 176.

[0101] Furthermore, in the brake holding mechanisms 43A-43D of the first to fourth embodiments, a ratchet gear 97 is arranged coaxially with the rotating shaft 40A of the electric motor 40. However, the ratchet gear 97 can also be arranged in a position that rotates synchronously with the rotating components of the rotating shaft 40A of the electric motor 40, the multi-stage gear reduction mechanism 51 of the reduction mechanism 41, and the planetary gear reduction mechanism 52, or synchronously with the rotating component of the brake mechanism 42, in the rotational transmission path from the electric motor 40 to the brake mechanism 42. In short, the ratchet gear 97 can also be arranged in a position that rotates synchronously with the rotating components arranged in the rotational transmission path of the electric motor 40 rotating shaft 40A → first to third reduction gears 55-57 (multi-stage gear reduction mechanism 51) → planetary gear reduction mechanism 52 → bracket 86 → brake mechanism 42. On the other hand, the ratchet gear 97 can also be arranged in a position that is offset from the rotational transmission path and rotates synchronously with the rotating shaft 40A of the electric motor 40.

[0102] Furthermore, the brake holding mechanisms 43A to 43D of the first to fourth embodiments are applied to disc brakes 1 that use an electric motor 40 to drive both the service brake and the parking brake. However, they can also be applied to disc brakes that use hydraulic pressure to operate the service brake and use the electric motor 40 to operate the parking brake.

[0103] It should be noted that the present invention is not limited to the embodiments described above, and includes various modifications. For example, the embodiments described above are detailed embodiments for the purpose of easily understanding and illustrating the present invention, and are not limited to having all the structures described. In addition, a part of the structure of a certain embodiment can be replaced with the structure of another embodiment, and it is also possible to add the structure of another embodiment to the structure of a certain embodiment. Furthermore, regarding a part of the structure of each embodiment, other structures can be added, deleted, or replaced.

[0104] This application claims priority based on Japanese Patent Application No. 2024-95259, filed on June 12, 2024. The entire disclosure of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2024-95259, filed on June 12, 2024, is incorporated herein by reference in its entirety.

[0105] Explanation of reference numerals in the attached figures

[0106] 1: Disc brake; 2: Inner brake block (brake component); 3: Outer brake block (brake component); 32: Housing; 36: First housing portion; 36A: Wall portion; 40: Electric motor (motor); 40A: Rotating shaft; 42: Braking mechanism; 43A: Brake holding mechanism of the first embodiment; 43B: Brake holding mechanism of the second embodiment; 43C: Brake holding mechanism of the third embodiment; 43D: Brake holding mechanism of the fourth embodiment; 97: Ratchet gear (rotating component); 98: Restriction mechanism; 99: Clutch unit; 101: Gear Wheel section; 104: Solenoid actuator (drive source); 105: Holding component; 106: Compression coil spring (elastic component); 114: Claw section; 125: One-way clutch; 152: Claw side limiting part (engaging part); 153: Claw side bending part (engaging part); 156: Tooth side limiting part (locking plate); 157: Tooth side bending part (engaging plate); 160: Claw side inclined surface; 162: Tooth side inclined surface; 164: Space; 170: Rotating body (rotating component); 171: Friction component; 173: Bending surface; D: Brake disc (braken component).

Claims

1. An electric brake, characterized in that, This electric brake has the following features: motor; A braking mechanism that generates braking force by pressing a braking component against a braked component through rotation from the motor; and A brake holding mechanism that retains the braking force generated by the braking mechanism. The brake holding mechanism includes: A rotating shaft and rotating components, which transmit rotation from the motor; A limiting mechanism that, when the rotation axis of the rotating member and the rotation direction of the rotating member are set in one direction by the braking mechanism pressing the braking member against the braked member, restricts the rotation of the rotating member in another direction; and A clutch unit that, while restricting the rotation of the rotating component in the other direction by means of the limiting mechanism, allows relative rotation of the rotating shaft in one direction and restricts relative rotation in the other direction.

2. The electric brake according to claim 1, characterized in that, The clutch unit is composed of a one-way clutch disposed between the outer peripheral surface of the rotating shaft and the inner peripheral surface of the cylindrical rotating component, allowing relative rotation of the rotating shaft relative to the rotating component in one direction and restricting relative rotation in the other direction.

3. The electric brake according to claim 1, characterized in that, After the rotation of the rotating component in the other direction is restricted by the limiting mechanism, the rotating axis is rotated in the first direction by the motor, and the braking force is generated by the braking mechanism.

4. The electric brake according to claim 1, characterized in that, After the braking force generated by the braking mechanism is maintained by the limiting mechanism, the rotating shaft is rotated again in the first direction by the motor, thereby increasing the braking force based on the braking mechanism.

5. The electric brake according to claim 1, characterized in that, The rotating component has multiple engaging portions formed on the outer peripheral surface of the rotating component and spaced apart circumferentially. The limiting mechanism includes: a locking piece that engages with the engaging portion; a drive source that propels the locking piece forward; and an elastic member that retracts the locking piece to an initial position. After the locking piece of the limiting mechanism is engaged with the locking part of the rotating component by the drive source, the rotating axis is rotated in the direction by the motor when the drive source is disconnected.

6. The electric brake according to claim 1, characterized in that, The rotating component has a pointed gear portion, of which multiple pointed gear portions are continuously arranged circumferentially on the outer peripheral surface of the rotating component, and have an inclined surface that guides the claw portion constituting the limiting mechanism. The front end of the claw has an inclined surface that abuts against the inclined surface of the gear. The top view shape of the front end of the claw is approximately the same as the top view shape of the space between the adjacent gears of the rotating component.

7. The electric brake according to claim 1, characterized in that, A friction element is provided on the outer peripheral surface of the rotating component. The front end face of the retaining member constituting the limiting mechanism, which faces the outer peripheral surface of the rotating member, is formed as a curved surface capable of abutting against the outer peripheral surface of the rotating member. The retaining member is slidably supported between the opposing walls of the housing in which the retaining member is housed.

8. The electric brake according to claim 2, characterized in that, The one-way clutch is a cam-type clutch.

9. The electric brake according to claim 2, characterized in that, The one-way clutch is a helical spring clutch.

Images