Electric brake device

Abstract

To provide an electric brake device which can reduce the number of components of a drive source for braking, and a parking brake.SOLUTION: An electric brake device 100 includes: a motor 3; a rotational shaft 6 in which a parking screw part 60 and a braking screw part 61 are provided with a common center axis line C1, and which is rotated by the motor 3; a parking piston 7 which moves in an axial direction of the center axial line C1 by the rotation of the rotational shaft 6 in one rotational direction R1 in a state of being screwed with the packing screw part 60, and presses a brake pad 9a; and a piston 101 which includes a braking piston 8 that presses the brake pad 9a by moving in the axial direction as the parking piston 7 moves in a direction away from the brake pad 9a in the axial direction by the rotation of the rotational shaft 6 in the other rotation direction in a state of being engaged with the braking screw part 61.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an electric brake device. [Background technology]

[0002] BACKGROUND ART Conventionally, an electric brake device equipped with a motor is known (see, for example, Patent Document 1).

[0003] The above-mentioned Patent Document 1 discloses an electric brake device including a motor, a rotating shaft rotated by the motor, and a single piston threadedly engaged with the rotating shaft. The piston moves back and forth in the axial direction as the rotating shaft rotates. The piston is configured to press a brake pad against a brake disc to brake the brake disc (tire). In other words, the electric brake device is used as a so-called service brake, which is used during normal driving.

[0004] The electric brake device further includes a ratchet mechanism for maintaining a parking state by pressing the brake pads against the brake disc with the piston. The ratchet mechanism is driven by an electric solenoid and is configured to lock the movement of the piston with the brake pads pressed against the brake disc, thereby maintaining the parking state. In other words, the electric brake device can also be used as a parking brake. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-142935 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the electric brake device of Patent Document 1 requires both a motor and an electric solenoid as drive sources for braking and parking braking. Conventionally, there has been a demand for reducing the number of parts in the drive sources for braking and parking braking in electric brake devices.

[0007] The present invention has been made to solve the above-mentioned problems, and one object of the present invention is to provide an electric brake device that can reduce the number of parts in the drive source for braking and parking brakes. [Means for solving the problem]

[0008] In order to achieve the above object, an electric brake device in one aspect of the present invention includes a motor, a rotating shaft rotated by the motor, wherein a parking threaded portion and a braking threaded portion are provided having a common central axis, and a piston including a parking piston portion that moves in the axial direction of the central axis and presses against the brake pads when the rotating shaft rotates in one rotation direction while threadedly engaged with the parking threaded portion, and a braking piston portion that moves in the axial direction and presses against the brake pads when the rotating shaft rotates in the other rotation direction opposite to the one rotation direction while threadedly engaged with the braking threaded portion.

[0009] In one aspect of the present invention, the electric brake device includes a parking piston portion that moves axially along the central axis of the central axis and presses the brake pads when the rotating shaft rotates in one rotational direction while threadedly engaged with the parking threaded portion of the rotating shaft, and a braking piston portion that moves axially and presses the brake pads when the rotating shaft rotates in the other rotational direction opposite the one rotational direction while threadedly engaged with the braking threaded portion of the rotating shaft. This allows the parking piston portion to be moved and the parking state to be maintained by switching the rotational direction of the rotating shaft using a motor as a drive source. Furthermore, the braking piston portion can be moved and the brake pads can be pressed against the disc rotor by switching the rotational direction of the rotating shaft using a motor as a drive source, thereby braking the disc rotor (tire). In other words, braking and parking states can be maintained using only one motor. This eliminates the need for an electric solenoid for maintaining the parking state, as in the prior art. As a result, the number of parts of the drive source for braking and parking brake can be reduced.

[0010] In the electric brake device according to the above aspect, preferably, the piston is provided as a common configuration for the parking piston portion and the braking piston portion so as to cover the parking piston portion and the braking piston portion from the brake pad side, and includes a single pad contact member that comes into contact with the brake pad, and the parking piston portion and the braking piston portion are configured to come into contact with the brake pad via the pad contact member and press the brake pad.

[0011] By configuring it in this manner, a larger contact area can be secured between the brake pad and the pad contact member, which is the member that presses the brake pad, compared to when multiple members are switched to press the brake pad, so that frictional force can be effectively generated between the pad contact member and the brake pad, thereby maintaining the braking and parking state.

[0012] In the electric brake device according to the above aspect, the parking threaded portion is preferably a male parking screw provided on the outer peripheral surface of the rotating shaft and threadedly engaged with the parking piston portion, and the braking threaded portion is preferably a ball screw provided on the inner peripheral surface of the rotating shaft and threadedly engaged with the braking piston portion.

[0013] With this configuration, the parking piston can be screwed onto the parking male thread of the rotating shaft from the outer periphery, which prevents the rotating shaft from becoming too large. Also, the ball screw allows the braking piston to move smoothly relative to the braking thread of the rotating shaft, which improves the responsiveness of the braking piston.

[0014] The electric brake device in the above aspect preferably further includes a housing that accommodates the rotating shaft, the parking piston portion, and the braking piston portion, and the rotating shaft is configured to move in a direction opposite to the direction in which the parking piston portion presses the brake pad against the disc rotor when it receives a reaction force caused by the parking piston portion pressing the brake pad against the disc rotor, and the rotating shaft includes an abutment portion that abuts against the housing when the rotating shaft moves in the direction opposite to the pressing direction.

[0015] With this configuration, the holding force for maintaining the parked state can be increased by the contact portion that contacts the housing, so the parked state can be maintained more stably.

[0016] In the electric brake device according to the above aspect, the following configuration is also possible.

[0017] (Additional note 1) In the above electric brake device, the parking piston portion and the braking piston portion are preferably configured to be in direct contact with the brake pads and press against the brake pads, the parking piston portion being formed in a ring shape when viewed in the axial direction of the central axis, and the braking piston portion being formed in a circular shape located inside the parking piston portion when viewed in the axial direction of the central axis.

[0018] With this configuration, the threaded portion between the parking piston and the rotating shaft can be positioned outside (on the outer periphery) of the threaded portion between the braking piston and the rotating shaft, so that the radial distance from the central axis of the rotating shaft to the threaded portion between the parking piston and the rotating shaft can be secured relatively large, thereby reducing the thread lead angle of the threaded portion for parking, thereby increasing the frictional force of the threaded portion for parking.

[0019] (Additional note 2) In the configuration in which the parking screw portion is a male parking screw provided on the outer peripheral surface of the rotating shaft and screws into the parking piston portion, preferably, the rotating shaft is formed in a cylindrical shape with the male parking screw provided on its outer peripheral surface, and the braking screw portion is a female braking screw provided on the inner peripheral surface of the rotating shaft and screws into the braking piston portion, and at least a portion of the male parking screw and the female braking screw are formed in an overlapping range in the axial direction.

[0020] By configuring it in this manner, the parking male thread of the rotating shaft and the braking female thread of the rotating shaft can be overlapped in the axial direction, thereby reducing the size of the rotating shaft in the axial direction and making the device more compact in the axial direction.

[0021] (Additional note 3) In the configuration in which the parking screw portion is a male parking screw provided on the outer peripheral surface of the rotating shaft and threaded onto the parking piston portion, preferably, the braking screw portion is a male braking screw provided on the outer peripheral surface of the rotating shaft and threaded onto the braking piston portion, and the rotating shaft includes a parking rotating shaft portion on which the male parking screw is provided, and a braking rotating shaft portion connected to one axial end of the parking rotating shaft portion and on which the male braking screw is provided, and in the axial direction, the male parking screw and the male braking screw are formed in a shifted range so as not to overlap each other.

[0022] By configuring it in this manner, the parking piston portion and the braking piston portion can be arranged on the outer periphery of the rotating shaft, thereby reducing the size of the rotating shaft in the direction intersecting the axial direction and making the device more compact in the direction intersecting the axial direction.

[0023] (Additional note 4) In a configuration that includes the above-mentioned housing and the rotating shaft including the abutment portion, preferably, a biasing member is further provided that is arranged axially between the housing and the rotating shaft, and the rotating shaft is configured so that when it receives a reaction force caused by the parking piston portion pressing the brake pad against the disc rotor, it moves in a direction opposite to the pressing direction of the brake pad against the biasing force of the biasing member, causing the abutment portion to abut against the housing.

[0024] With this configuration, the biasing member is deformed and the abutting portion of the rotating shaft abuts against the housing only when the rotating shaft receives a reaction force caused by the parking piston pressing the brake pad against the disc rotor. In other words, during braking when the rotating shaft receives a relatively small reaction force from the braking piston, the biasing member is prevented from deforming and causing the abutting portion of the rotating shaft to abut against the housing.

[0025] (Additional note 5) In the above-described configuration including the housing and the rotary shaft including the abutment portion, the abutment portion is preferably a flange portion that extends in a direction intersecting the axial direction and that comes into surface contact with the inner bottom surface of the housing.

[0026] With this configuration, the abutment portion formed by the flange portion can ensure a large contact surface area between the rotating shaft and the housing that generates a holding force for maintaining the parking state, thereby generating a larger holding force for maintaining the parking state.

[0027] (Additional note 6) In the configuration in which the piston includes the pad contact member, it is preferable to further include a biasing member that biases the parking piston portion and the braking piston portion toward the brake pad and biases the pad contact member in the opposite direction to the parking piston portion and the braking piston portion.

[0028] With this configuration, the biasing member can apply pressure to the parking piston portion, the braking piston portion, and the pad contact member in a direction that moves them away from each other, thereby preventing rattling in the relative positions of the pad contact member and the parking piston portion and the braking piston portion when switching between the braking state and the parking state, for example. [Effects of the Invention]

[0029] The present invention can reduce the number of parts in the drive source for braking and parking brake. [Brief explanation of the drawings]

[0030] [Figure 1] 1 is a cross-sectional side view showing an electric brake device and a tire according to a first embodiment. [Figure 2] 1 is a cross-sectional side view showing the electric brake device according to the first embodiment, illustrating a parking state using a parking piston portion. FIG. [Figure 3]1 is a cross-sectional side view showing the electric brake device according to the first embodiment, illustrating a braking state by a braking piston portion. FIG. [Figure 4] FIG. 6 is a cross-sectional side view showing an electric brake device according to a second embodiment. [Figure 5] FIG. 10 is a cross-sectional side view showing an electric brake device according to a third embodiment. [Figure 6] 10A and 10B are diagrams for explaining switching between a braking state, a neutral state, and a parking state of an electric brake device according to a third embodiment. [Figure 7] FIG. 10 is a cross-sectional side view showing a rotating shaft, a parking piston portion, and a braking piston portion of an electric brake device according to a first modified example. [Figure 8] FIG. 10 is a cross-sectional side view showing a rotating shaft, a parking piston portion, and a braking piston portion of an electric brake device according to a second modified example. [Figure 9] FIG. 11 is a cross-sectional side view showing a rotating shaft, a parking piston portion, and a braking piston portion of an electric brake device according to a third modified example. DETAILED DESCRIPTION OF THE INVENTION

[0031] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0032] (First embodiment) The configuration of an electric brake device 100 according to a first embodiment will be described with reference to FIGS.

[0033] The electric brake device 100 shown in Fig. 1 is an electric brake device provided on a tire T of a vehicle. The electric brake device 100 is used to brake the tire T (disc rotor 9b) and to maintain the vehicle in a parking state. The electric brake device 100 may be provided on only some of the tires T, such as only the front wheels or only the rear wheels, or may be provided on all of the tires T.

[0034] The electric brake device 100 is mounted on a shift-by-wire vehicle in which shift switching control is performed based on an operation signal from a shift switching operation unit provided with a shift sensor. As an example, when the control unit receives an operation signal from the shift switching operation unit to switch from the parking release state to the parking state, the electric brake device 100 is driven and controlled to perform an operation to switch from the parking release state to the parking state.

[0035] In the drawings, the axial direction of the central axis C1 of the rotating shaft 6 of the electric brake device 100 is indicated as direction A. Within the direction A, the pressing direction of the brake pad 9a by the parking piston portion 7 and the braking piston portion 8 (described later) is indicated as direction A1, and the opposite direction is indicated as direction A2. The central axis C1 is also the common central axis of the parking screw portion 60 and the braking screw portion 61 (described later). The central axis C2 of the motor shaft 32 of the motor 3 and the central axis C3 of the disc rotor 9b (tire T) also extend in the direction A.

[0036] In the drawings, one rotation direction of the rotating shaft 6 is indicated by the R1 direction, and the other rotation direction opposite to the one rotation direction of the rotating shaft 6 is indicated by the R2 direction. As an example, when the motor 3 rotates forward, the rotating shaft 6 rotates in one rotation direction (the R1 direction), and when the motor 3 rotates reversely, the rotating shaft 6 rotates in the other rotation direction (the R2 direction). As an example, when the motor 3 rotates forward, the parking piston portion 7 moves in the A1 direction and simultaneously the braking piston portion 8 moves in the A2 direction, and when the motor 3 rotates reversely, the parking piston portion 7 moves in the A2 direction and simultaneously the braking piston portion 8 moves in the A1 direction.

[0037] The electric brake device 100 includes a housing 1, a biasing member 2, a motor 3 serving as a drive source, a transmission gear 4 that transmits the drive force of the motor 3, a driven gear 5 that is rotated by the drive force of the motor 3 transmitted via the transmission gear 4, a rotating shaft 6 that is rotated together with the driven gear 5 by the motor 3, a piston 101, a brake pad 9a, and a disc rotor 9b. The piston 101 includes a parking piston portion 7 and a braking piston portion 8. The parking piston portion 7 and the braking piston portion 8 are configured to directly contact the brake pad 9a and press the brake pad 9a. The parking piston portion 7 and the braking piston portion 8 contact the brake pad 9a at different times. The piston 101 includes only one parking piston portion 7. In other words, the parking piston portion 7 is a single component. The piston 101 includes only one braking piston portion 8. In other words, the braking piston portion 8 has a single structure.

[0038] (Housing configuration) The housing 1 accommodates various components of the electric brake device 100 (motor 3, transmission gear 4, driven gear 5, rotating shaft 6, parking piston portion 7, braking piston portion 8, biasing member 2, and brake pad 9a). The housing 1 also accommodates a portion of the disc rotor 9b that faces the brake pad 9a.

[0039] The housing 1 is configured to be separable into multiple components for ease of assembly. Specifically, the housing 1 includes a cylindrical housing main body 10 and a cover member 11. The cylindrical housing main body 10 accommodates a rotating shaft 6, a parking piston 7, a braking piston 8, and the like. The cover member 11 is attached to the cylindrical housing main body 10 from the A2 direction side.

[0040] The housing 1 is provided with a bearing accommodating recess 12 that accommodates a bearing B that rotatably supports the rotating shaft 6. The bearing accommodating recess 12 is an annular recess in which the bearing B is disposed. The bearing accommodating recess 12 is recessed in the A2 direction along the rotating shaft 6 from a piston accommodating region 13 inside the housing 1 that accommodates the parking piston 7 and the braking piston 8. A biasing member 2 is disposed on the bottom surface of the bearing accommodating recess 12. That is, the biasing member 2 is disposed between the bottom surface of the bearing accommodating recess 12 (housing 1) on the A2 direction side and the rotating shaft 6 on the A1 direction side in the axial direction (A direction). Therefore, the bearing B is disposed between the biasing member 2 and the rotating shaft 6 in the axial direction (A direction). The bottom surface of the bearing accommodating recess 12 (housing 1), the bearing B, and the biasing member 2 are always held in contact with each other in the axial direction (A direction).

[0041] An inner bottom surface 13a provided in the housing 1 and located on the A2 side of the piston accommodating region 13 is configured to come into surface contact with a flange portion that forms a contact portion 64 (described later) of the rotating shaft 6 in the parking state. Details will be described later.

[0042] (Configuration of the biasing member) As an example, the biasing member 2 is a so-called disc spring. The biasing member 2 is formed in an annular shape surrounding the rotary shaft 6 having a central axis C1. The biasing member 2 extends along the bottom surface, which is the end surface in the A2 direction, of the bearing accommodating recess 12. The biasing member 2 has relatively high rigidity, and is deformed (contracts in the A direction) only when subjected to a large compressive force in the A direction. The biasing member 2 is maintained in an undeformed state during the parking release state, which includes when the brake piston portion 8 brakes the disc rotor 9b. On the other hand, the biasing member 2 is maintained in a deformed state during the parking state.

[0043] (Motor and transmission gear configuration) The motor 3 includes a motor body 30 and a motor shaft 32 provided with a motor gear 31. The motor 3 is arranged side by side in a direction intersecting the direction A with respect to the rotating shaft 6, to which the driving force is transmitted. In other words, the motor 3 is not a direct-acting type that directly rotates the rotating shaft 6, but is configured to indirectly rotate the rotating shaft 6. The transmission gear 4 is arranged between the motor shaft 32 and the rotating shaft 6 in a direction intersecting the direction A. A plurality of transmission gears 4 are provided, and are configured to transmit the output of the motor 3 to the rotating shaft 6 after reducing the speed. The plurality of transmission gears 4 are rotatably supported by bearings (not shown). As an example, the motor gear 31 and the transmission gear 4 are configured as spur gears.

[0044] (Configuration of driven gear and rotating shaft) The driven gear 5 is provided on a rotary shaft 6. The driven gear 5 and the rotary shaft 6 have a common central axis C1. As an example, the driven gear 5 is made of a spur gear.

[0045] The rotating shaft 6 is configured to move the parking piston portion 7 and the braking piston portion 8 in the axial direction (direction A). In detail, the rotating shaft 6 is provided with a parking screw portion 60 and a braking screw portion 61 having a common central axis C1.

[0046] The parking threaded portion 60 is a parking male screw that is provided on the outer peripheral surface 62 of the rotating shaft 6 and screws into the parking piston portion 7. The rotating shaft 6 is formed in a cylindrical shape with the parking male screw provided on the outer peripheral surface 62. Therefore, the parking piston portion 7 is provided with a female screw that screws into the parking male screw that is the parking threaded portion 60 of the rotating shaft 6. The screwed portion between the parking threaded portion 60 and the parking piston portion 7 is formed by a trapezoidal thread 60a. A greater frictional force is generated in the parking threaded portion 60 than in the braking threaded portion 61.

[0047] The braking screw portion 61 is a braking female screw that is provided on the inner circumferential surface 63 of the rotating shaft 6 and screws into the braking piston portion 8. Therefore, the braking piston portion 8 is provided with a male screw that screws into the braking female screw that is the braking screw portion 61 of the rotating shaft 6. The screwed portion between the braking screw portion 61 and the braking piston portion 8 is formed by a ball screw 61a. The ball screw 61a is provided on the inner circumferential surface 63 of the rotating shaft 6 and is configured to screw into the braking piston portion 8.

[0048] In the axial direction (direction A), at least a portion of the parking male screw that forms the parking screw portion 60 of the rotating shaft 6 and the braking female screw that forms the braking screw portion 61 of the rotating shaft 6 are formed in an overlapping range.

[0049] As an example, the thread pitch in the axial direction of the parking screw portion 60 of the rotating shaft 6 and the thread pitch in the axial direction of the braking screw portion 61 of the rotating shaft 6 are equal to each other. Naturally, the thread pitch in the axial direction of the female thread of the parking piston portion 7 and the thread pitch in the axial direction of the male thread of the braking piston portion 8 are equal to each other. In addition, the diameter of the female thread of the parking piston portion 7 is larger than the diameter of the male thread of the braking piston portion 8. In addition, the moving speeds of the parking piston portion 7 and the braking piston portion 8, which move simultaneously in opposite directions, are equal to each other.

[0050] Therefore, when the same power is used to move the parking piston portion 7 and press the brake pad 9a against the disc rotor 9b with the parking piston portion 7, and to move the braking piston portion 8 and press the brake pad 9a against the disc rotor 9b with the braking piston portion 8, a higher movement responsiveness can be obtained with the braking piston portion 8. In other words, the braking piston portion 8 can be moved more efficiently than the parking piston portion 7.

[0051] As shown in FIG. 2, when the rotating shaft 6 receives a reaction force caused by the parking piston portion 7 pressing the brake pad 9a against the disc rotor 9b, the rotating shaft 6 is configured to move slightly in the direction (A2 direction) opposite to the direction (A1 direction) in which the parking piston portion 7 presses the brake pad 9a.

[0052] The rotating shaft 6 includes a contact portion 64. The contact portion 64 is configured to come into contact with the inner bottom surface 13a of the housing 1 when the rotating shaft 6 moves in the direction opposite to the pressing direction of the brake pad 9a. The contact portion 64 is a flange portion that extends in a direction intersecting the axial direction and comes into surface contact with the inner bottom surface 13a of the housing 1. The contact portion 64 is formed in an annular shape with the central axis C1 located at the center.

[0053] (Configuration of parking piston and braking piston) 2 is configured to move in the axial direction (A1 direction) of the central axis C1 and press against the brake pad 9a when the rotary shaft 6 rotates in one rotation direction (R1 direction) while threadedly engaged with the parking threaded portion 60 of the rotary shaft 6. When pressing against the brake pad 9a, the parking piston portion 7 comes into direct contact with the brake pad 9a. The parking piston portion 7 presses the brake pad 9a against the disc rotor 9b, locking the rotation of the rotary shaft 6 by the frictional force between the parking threaded portion 60 and the parking piston portion 7, thereby switching from the parking release state to the parking state.

[0054] The parking piston portion 7 is configured to be separable into multiple members in consideration of ease of assembly. As a specific example (not shown), the parking piston portion 7 is configured to be separable into two members, one on one side and the other on the other side in the axial direction. A predetermined tilt suppression mechanism including a spring member is provided between the two members that configure the parking piston portion 7 to suppress tilting of the parking piston portion 7 with respect to the opposing disc rotor 9b.

[0055] 3 is configured such that, when the rotating shaft 6 rotates in the other rotation direction (R2 direction) opposite to one rotation direction (R1 direction) while threadedly engaged with the braking threaded portion 61 of the rotating shaft 6, the parking piston portion 7 moves in a direction away from the brake pad 9a in the axial direction, and also moves in the opposite direction (A1 direction) from the parking piston portion 7 along the axial direction of the central axis C1 to press the brake pad 9a. When pressing the brake pad 9a, the braking piston portion 8 comes into direct contact with the brake pad 9a. The braking piston portion 8 presses the brake pad 9a that it is in contact with against the disc rotor 9b, thereby braking the disc rotor 9b.

[0056] The pressing force with which the braking piston portion 8 presses the brake pad 9a is smaller than the pressing force with which the parking piston portion 7 presses the brake pad 9a. As an example, the area of the annular pressing surface 7a of the brake pad 9a, which is the end face of the parking piston portion 7 in the A1 direction, is larger than the area of the circular pressing surface 8a of the brake pad 9a, which is the end face of the braking piston portion 8 in the A1 direction.

[0057] The parking piston portion 7 and the braking piston portion 8 are always threadedly engaged with the parking screw portion 60 and the braking screw portion 61 of the rotating shaft 6, respectively. Therefore, the parking piston portion 7 and the braking piston portion 8 move simultaneously as the rotating shaft 6 rotates. The parking screw portion 60 and the braking screw portion 61 of the rotating shaft 6 each have a helical thread that runs in opposite directions so that the parking piston portion 7 and the braking piston portion 8 always move in opposite directions along the axial direction (direction A). In other words, the parking piston portion 7 has one of a right-handed thread and a left-handed thread, and the braking piston portion 8 has the other of a right-handed thread and a left-handed thread.

[0058] The parking piston portion 7 is formed in an annular shape when viewed in the axial direction (direction A) of the central axis C1. The braking piston portion 8 is formed in a circular shape and disposed inside the parking piston portion 7 when viewed in the axial direction. In other words, the parking piston portion 7 is configured to come into contact with the brake pad 9a at a position farther from the central axis C1 than the braking piston portion 8.

[0059] Although not shown, the parking piston portion 7 and the braking piston portion 8 are provided with a predetermined anti-rotation structure that prevents the parking piston portion 7 and the braking piston portion 8 from rotating around the central axis C1 in accordance with the rotation of the rotary shaft 6. As one example, this anti-rotation structure is a guide structure formed by engaging a convex portion and a concave portion that extend in the axial direction and are provided on the parking piston portion 7, the braking piston portion 8, and the housing 1.

[0060] (Brake pad and disc rotor configuration) The brake pads 9a and disc rotor 9b shown in FIG. 1 are arranged on the A1 direction side of the parking piston portion 7 and the braking piston portion 8. A pair of brake pads 9a are provided facing each other in the axial direction (direction A). A disc rotor 9b is arranged between the pair of brake pads 9a. A tire T is fixed to the disc rotor 9b outside the housing 1. In other words, the disc rotor 9b is configured to rotate together with the tire T. The pair of brake pads 9a are configured to be pressed against the disc rotor 9b using the driving force of the motor 3, thereby generating a braking force that reduces the torque of the disc rotor 9b (tire T) or a braking force that suppresses an increase in torque.

[0061] (Regarding the holding force that maintains the electric brake device in the parking position) The holding force for holding the parking state of the electric braking device 100 will be described with reference to Fig. 2. There are two holding forces for holding the parking state of the electric braking device 100.

[0062] As described above, the first holding force is the frictional force between the parking piston portion 7 and the parking screw portion 60. The parking piston portion 7 is configured to lock the rotation of the rotary shaft 6 by this frictional force, thereby switching from the parking release state to the parking state.

[0063] The second holding force is the frictional force between the housing 1 and the abutment portion 64 configured as a flange portion of the rotating shaft 6. In detail, when the rotating shaft 6 receives a reaction force caused by the parking piston portion 7 pressing the brake pad 9a against the disc rotor 9b, the rotating shaft 6 moves in the direction (A2 direction) opposite to the pressing direction (A1 direction) of the brake pad 9a against the biasing force of the biasing member 2, causing the abutment portion 64 to abut against the housing 1. In addition to the frictional force between the parking screw portion 60 and the parking piston portion 7, the abutment portion 64 is configured to maintain a parking state in which the rotation of the rotating shaft 6 is locked by the frictional force with the housing 1.

[0064] More specifically, when the parking piston portion 7 moves in the A1 direction as the rotating shaft 6 rotates and the pressing force pressing the brake pad 9a against the disc rotor 9b increases, the parking piston portion 7 cannot move any further in the A1 direction. As a result, a reaction force from the disc rotor 9b generates a particularly large force that presses the female thread of the parking piston portion 7 in the A2 direction against the parking screw portion 60 of the rotating shaft 6. As the reaction force increases, the force pressing the parking screw portion 60 of the rotating shaft 6 in the A2 direction increases, and when the force reaches a size that can deform the biasing member 2, the biasing member 2 changes from a non-deformed state (see FIG. 3) to a deformed state in which it contracts in the A direction.

[0065] As a result, the rotating shaft 6 moves slightly in the direction A2 so as to close the gap S (see FIG. 3) between the contact portion 64 and the inner bottom surface 13a of the housing 1 against the biasing force of the biasing member 2. As a result, the contact portion 64 of the rotating shaft 6 comes into surface contact with the inner bottom surface 13a of the housing 1. The electric brake device 100 is configured to suppress rotation of the rotating shaft 6 and more reliably maintain the parking state by the frictional force of the surface contact portion between the contact portion 64 of the rotating shaft 6 and the inner bottom surface 13a of the housing 1.

[0066] (Effects of the first embodiment) In the first embodiment, the following effects can be obtained.

[0067] As described above, the first embodiment includes the parking piston portion 7, which moves in the axial direction of the central axis C1 and presses the brake pad 9a when the rotating shaft 6 rotates in one rotation direction while threadedly engaged with the parking threaded portion 60 of the rotating shaft 6, and the braking piston portion 8, which moves axially and presses the brake pad 9a when the rotating shaft 6 rotates in the other rotation direction opposite to the one rotation direction while threadedly engaged with the braking threaded portion 61 of the rotating shaft 6. As a result, by switching the rotation direction of the rotating shaft 6 using the motor 3 as a drive source, the parking piston portion 7 can be moved to maintain a parking state. Furthermore, by switching the rotation direction of the rotating shaft 6 using the motor 3 as a drive source, the braking piston portion 8 can be moved to press the brake pad 9a against the disc rotor 9b, thereby braking the disc rotor 9b (tire T). In other words, the braking and parking states can be maintained using only one motor 3. Therefore, there is no need for an electric solenoid to maintain the parking state as in the past, and as a result, the number of parts required for the drive source for braking and parking brakes can be reduced.

[0068] In the first embodiment, as described above, the parking screw portion 60 is a male parking screw that is provided on the outer peripheral surface 62 of the rotating shaft 6 and screws into the parking piston portion 7, and the braking screw portion 61 is a ball screw 61a that is provided on the inner peripheral surface 63 of the rotating shaft 6 and screws into the braking piston portion 8. This allows the parking piston portion 7 to be screwed into the male parking screw of the rotating shaft 6 from the outer peripheral side, thereby preventing the rotating shaft 6 from becoming larger. Furthermore, the ball screw 61a allows the braking piston portion 8 to operate smoothly relative to the braking screw portion 61 of the rotating shaft 6, thereby improving the responsiveness of the braking piston portion 8.

[0069] As described above, the first embodiment further includes a housing 1 that accommodates the rotating shaft 6, the parking piston portion 7, and the braking piston portion 8, and the rotating shaft 6 is configured to move in the direction opposite to the pressing direction of the brake pad 9a by the parking piston portion 7 when it receives a reaction force caused by the parking piston portion 7 pressing the brake pad 9a against the disc rotor 9b, and the rotating shaft 6 includes an abutment portion 64 that abuts against the housing 1 when the rotating shaft 6 moves in the direction opposite to the pressing direction, and is configured to maintain a parking state in which rotation of the rotating shaft 6 is locked by the frictional force between the parking threaded portion 60 and the parking piston portion 7 and the abutment portion 64 and the housing 1. This makes it possible to increase the holding force for maintaining the parking state by the abutment portion 64 abutting against the housing 1, and therefore the parking state can be maintained more stably.

[0070] In the first embodiment, as described above, the parking piston portion 7 and the braking piston portion 8 are configured to directly contact the brake pad 9a and press against the brake pad 9a, the parking piston portion 7 being formed in an annular shape when viewed in the axial direction of the central axis C1, and the braking piston portion 8 being formed in a circular shape disposed inside the parking piston portion 7 when viewed in the axial direction. This allows the threaded portion between the parking piston portion 7 and the rotating shaft 6 to be disposed outside (on the outer periphery) of the threaded portion between the braking piston portion 8 and the rotating shaft 6, thereby ensuring a relatively large radial distance from the central axis C1 of the rotating shaft 6 to the threaded portion between the parking piston portion 7 and the rotating shaft 6, and thereby reducing the thread lead angle of the parking threaded portion 60. As a result, the frictional force of the parking threaded portion 60 can be increased.

[0071] In the first embodiment, as described above, the rotating shaft 6 is formed in a cylindrical shape with a parking male thread provided on the outer circumferential surface 62, the braking screw portion 61 is a braking female thread provided on the inner circumferential surface 63 of the rotating shaft 6 and threadedly engages with the braking piston portion 8, and at least a portion of the parking male thread and the braking female thread are formed in a range where they overlap each other in the axial direction. This allows the parking male thread of the rotating shaft 6 and the braking female thread of the rotating shaft 6 to overlap in the axial direction, thereby reducing the size of the rotating shaft 6 in the axial direction and making it possible to miniaturize the device in the axial direction.

[0072] As described above, the first embodiment further includes the biasing member 2 arranged axially between the housing 1 and the rotating shaft 6, and is configured so that when the rotating shaft 6 receives a reaction force caused by the parking piston portion 7 pressing the brake pad 9a against the disc rotor 9b, the rotating shaft 6 moves in a direction opposite to the pressing direction of the brake pad 9a against the biasing force of the biasing member 2, causing the abutment portion 64 to abut against the housing 1. In this way, when the rotating shaft 6 receives a reaction force caused by the parking piston portion 7 pressing the brake pad 9a against the disc rotor 9b, the biasing member 2 is deformed by the biasing member 2, causing the abutment portion 64 of the rotating shaft 6 to abut against the housing 1. In other words, during braking when the rotating shaft 6 receives a relatively small reaction force from the braking piston portion 8 side, the biasing member 2 can be prevented from deforming and causing the abutment portion 64 of the rotating shaft 6 to abut against the housing 1.

[0073] In the first embodiment, as described above, the contact portion 64 is a flange portion that extends in a direction intersecting the axial direction and comes into surface contact with the inner bottom surface 13a of the housing 1. This makes it possible to ensure a large contact surface area between the housing 1 and the rotating shaft 6 that generates a holding force for maintaining the parking state, by the contact portion 64 formed by the flange portion. As a result, a larger holding force for maintaining the parking state can be generated.

[0074] (Second embodiment) A second embodiment will be described with reference to Fig. 4. In this second embodiment, unlike the first embodiment in which the braking screw portion 61 of the rotating shaft 6 that screws into the braking piston portion 8 is configured with a female thread, an example will be described in which the braking screw portion 261 that screws into the braking piston portion 208 is configured with a male thread. In the drawings, the same components as those in the first embodiment are denoted by the same reference numerals.

[0075] The electric brake device 200 of the second embodiment includes a rotary shaft 206 and a piston 201. The piston 201 includes a parking piston portion 207 and a braking piston portion 208.

[0076] The rotary shaft 206 includes a parking screw portion 60 formed by a parking female screw, and a braking screw portion 261 formed by a braking female screw.

[0077] The braking screw portion 261 is provided on the outer circumferential surface 62 of the rotary shaft 206 and is a braking male screw that screws into the braking piston portion 208 .

[0078] The rotating shaft 206 includes a parking rotating shaft portion 206a provided with a parking male screw that forms the parking screw engagement portion 60. The rotating shaft 206 also includes a braking rotating shaft portion 206b connected to one end 206c in the axial direction (A1 direction) of the parking rotating shaft portion 206a and provided with a braking male screw that forms the braking screw engagement portion 261.

[0079] The diameter of the parking rotating shaft portion 206a is larger than the diameter of the braking rotating shaft portion 206b. Therefore, the parking rotating shaft portion 206a and the braking rotating shaft portion 206b form a stepped shape in which the A1 direction side becomes thinner. In the axial direction, the parking male thread that forms the parking screw portion 60 of the rotating shaft 206 and the braking male thread that forms the braking screw portion 261 of the rotating shaft 206 are formed in a shifted range so as not to overlap each other.

[0080] The parking piston portion 207 has a female thread that screws into the parking screw portion 60 (parking male thread) of the rotating shaft 206. The braking piston portion 208 has a female thread that screws into the braking screw portion 261 (braking male thread) of the rotating shaft 206.

[0081] The other configurations of the second embodiment are the same as those of the first embodiment.

[0082] (Effects of the second embodiment) In the second embodiment, the following effects can be obtained.

[0083] As described above, the second embodiment includes the parking piston portion 207 that moves in the axial direction of the central axis C1 and presses the brake pad 9a when the rotating shaft 206 rotates in one rotation direction while threadedly engaged with the parking threaded portion 60 of the rotating shaft 206, and the braking piston portion 208 that moves in the axial direction away from the brake pad 9a and also moves axially to press the brake pad 9a when the rotating shaft 206 rotates in the other rotation direction opposite to the one rotation direction while threadedly engaged with the braking threaded portion 261 of the rotating shaft 206. This makes it possible to reduce the number of parts in the drive source for braking and parking brake, as in the first embodiment.

[0084] In the second embodiment, as described above, the braking screw portion 261 is a braking male screw that is provided on the outer circumferential surface 62 of the rotating shaft 206 and screws into the braking piston portion 208, and the rotating shaft 206 includes a parking rotating shaft portion 206a on which the parking male screw is provided, and a braking rotating shaft portion 206b connected to one axial end 206c of the parking rotating shaft portion 206a on which the braking male screw is provided, and the parking male screw and the braking male screw are formed in a shifted range in the axial direction so as not to overlap each other. This makes it possible to arrange the parking piston portion 207 and the braking piston portion 208 on the outer circumferential side of the rotating shaft 206, thereby reducing the size of the rotating shaft 206 in a direction intersecting the axial direction and making it possible to miniaturize the device in the direction intersecting the axial direction.

[0085] Other effects of the second embodiment are the same as those of the first embodiment.

[0086] (Third embodiment) A third embodiment will be described with reference to Figures 5 and 6. In this third embodiment, unlike the first embodiment in which there are two members that come into direct contact with the brake pad 9a from the rotating shaft 6 side, an example will be described in which there is only one member that comes into direct contact with the brake pad 9a from the rotating shaft 6 side. Note that in the figures, the same components as in the first embodiment are denoted by the same reference numerals.

[0087] 5 and 6 includes a rotary shaft 6, a piston 301, a biasing member 302, and a sealing member 303. The piston 301 includes a parking piston portion 307, a braking piston portion 308, and a pad contact member 309.

[0088] The parking piston portion 307 is configured to move in the axial direction of the central axis C1 (direction A1) and press against the brake pad 9a when the rotary shaft 6 rotates in one rotation direction (direction R1) about the central axis C1 while threadedly engaged with the parking threaded portion 60. The parking piston portion 307 is formed in a cylindrical shape extending in the A direction and centered on the central axis C1. The parking piston portion 307 has a flange-shaped contact portion 307a at its end in the A1 direction, which is a portion that contacts the pad contact member 309. In addition, a guide portion 307b is provided on the contact portion 307a. The guide portion 307b is configured to guide the movement of the parking piston portion 307 in the A direction while restricting the rotation of the parking piston portion 307 about the central axis C1 relative to the pad contact member 309.

[0089] When the rotating shaft 6 rotates in the other rotation direction (R2 direction) opposite to the one rotation direction about the central axis C1 while threadedly engaged with the braking screw portion 61, the braking piston portion 308 moves along the axial direction of the central axis C1 in the opposite direction (A1 direction) from the parking piston portion 307 to press the brake pad 9a. In the A direction, the braking piston portion 308 always moves in the opposite direction to the pad contact member 309 simultaneously with the movement of the pad contact member 309. The braking piston portion 308 is formed in a cylindrical shape extending in the A direction along the central axis C1. The braking piston portion 308 has a flange-shaped contact portion 308a at its end in the A1 direction, which is the portion that contacts the pad contact member 309. In addition, a guide portion 308b is provided on the contact portion 308a. The guide portion 308b is configured to guide the movement of the braking piston portion 308 in the A direction while restricting the rotation of the braking piston portion 308 relative to the pad contact member 309 about the central axis C1.

[0090] The pad contact member 309 is a single component that contacts the brake pad 9a. The pad contact member 309 is provided as a component common to the parking piston portion 307 and the braking piston portion 308, covering the parking piston portion 307 and the braking piston portion 308 from the brake pad 9a side. The pad contact member 309 is formed in a hollow cylindrical shape with an end facing the A1 direction closed and an end facing the A2 direction open. That is, the pad contact member 309 is formed in a horizontal cup shape with the opening facing the A2 direction. The cylindrical pad contact member 309 is centered on a central axis C1. The pad contact member 309 is fitted to the inner circumferential surface of the housing 1 so as to be movable in the A direction. A guide portion (not shown) is provided on the outer circumferential surface of the pad contact member 309 to guide movement of the pad contact member 309 in the A direction while restricting rotation of the pad contact member 309 about the central axis C1 relative to the housing 1.

[0091] The parking piston portion 307 and the braking piston portion 308 are configured to come into contact with the brake pad 9a via the pad contact member 309 and press the brake pad 9a.

[0092] Here, it is assumed that the electric brake device 300 is in a parking release state in which there is no braking by the braking piston portion 308 and the disc rotor 9b (tire T (see FIG. 1)) is not locked by the parking piston portion 307. This state is referred to as a neutral state.

[0093] A case where the neutral state is switched to the braking state (a state in which the disc rotor 9b (tire T) is braked) will be described. In this case, the rotary shaft 6 rotates in the other rotation direction (direction R2) opposite to the one rotation direction about the central axis C1. As a result, the braking piston portion 308 moves in the direction A1 toward the brake pad 9a. At the same time, the parking piston portion 307 moves in the direction A2. Then, while contacting the pad contact member 309, the braking piston portion 308 pushes the pad contact member 309 in the direction A1. As a result, the braking piston portion 308 contacts the brake pad 9a via the pad contact member 309 and presses the brake pad 9a.

[0094] Next, a case where the neutral state (parking release state) is switched to the parking state will be described. In this case, the rotating shaft 6 rotates in one rotation direction (direction R1) around the central axis C1. As a result, the parking piston portion 307 moves in the direction A1 toward the brake pad 9a. At the same time, the braking piston portion 308 moves in the direction A2. The parking piston portion 307 then contacts the pad contact member 309 and pushes the pad contact member 309 in the direction A1. As a result, the parking piston portion 307 contacts the brake pad 9a via the pad contact member 309 and presses the brake pad 9a. When the rotating shaft 6 further rotates and presses the pad contact member 309 against the brake pad 9a via the parking piston portion 307 with even greater force, the parking piston portion 307 is pressed in the direction A2 by a reaction force from the brake pad 9a. This reaction force also presses the rotating shaft 6 in the direction A2. When this reaction force becomes greater than the biasing force of the biasing member 2, the contact portion 64 of the rotating shaft 6 is moved in the A2 direction against the biasing force of the biasing member 2 and comes into contact with the housing 1. As an example, the biasing member 2 is formed of a compression coil spring.

[0095] The biasing member 302 biases the parking piston portion 307 and the braking piston portion 308 in the A1 direction toward the brake pad 9a, and biases the pad contact member 309 in the opposite direction (A2 direction) to the parking piston portion 307 and the braking piston portion 308. The biasing member 302 is disposed inside the pad contact member 309. The biasing member 302 is formed of an elastic member that generates a biasing force in the A direction. As an example, the biasing member 302 is formed of a compression coil spring. The biasing member 302 is disposed with its center centered on the central axis C1. The A2 end of the biasing member 302 abuts against the pad contact member 309, and the A1 end of the biasing member 302 abuts against the parking piston portion 307. That is, the biasing member 302 constantly presses the pad contact member 309 in the A2 direction and constantly presses the parking piston portion 307 in the A1 direction. In other words, the biasing member 302 constantly applies a pressure in the outward direction A to the pad contact member 309 and the parking piston portion 307 between the pad contact member 309 and the parking piston portion 307. The braking piston portion 308 is connected to the parking piston portion 307 via the rotation shaft 6 which is slightly movable in the direction A. Therefore, the braking piston portion 308 also constantly receives a pressure in the direction A1 from the biasing member 302.

[0096] The pad contact member 309 is constantly subjected to a pressing force by the biasing member 302 that presses the pad contact member 309 in the direction A2 against the parking piston portion 307. This pressing force is uniform around the central axis C1. When, for example, the parking piston portion 307 and the braking piston portion 308 are moved to switch the usage state between the parking piston portion 307 and the braking piston portion 308, this uniform pressing force prevents the pad contact member 309, the parking piston portion 307, and the braking piston portion 308 from rattling.

[0097] When the rotating shaft 6 is rotated to return from the parking state to the neutral state, the pad contact member 309 moves in the A2 direction together with the parking piston portion 307 due to the biasing member 302. Similarly, when the rotating shaft 6 is rotated to return from the braking state to the neutral state, the pad contact member 309 moves in the A2 direction together with the braking piston portion 308 due to the biasing member 302.

[0098] The seal member 303 is provided at an interface E between the outer peripheral surface of the pad contact member 309 and the inner peripheral surface of the housing 1. In other words, the seal member 303 is provided at the interface E, which is a position where foreign matter and the like should be prevented from entering the inside of the device. In the electric brake device 300, the interface E where the seal member 303 should be provided to prevent foreign matter and the like from entering from the outside is only one location, between the pad contact member 309 and the housing 1.

[0099] As an example, the seal member 303 includes a bellows-shaped seal 303a disposed at the end of the housing 1 in the A1 direction. The bellows-shaped seal 303a is formed of an elastic member. The bellows-shaped seal 303a is formed in an annular shape with a central axis C1 at its center. One end of the bellows-shaped seal 303a is disposed in a recess in the outer peripheral surface of the pad contact member 309, and the other end is disposed in a recess in the inner peripheral surface of the housing 1. Furthermore, as an example, the seal member 303 includes a rectangular seal 303b disposed on the A2 direction side of the bellows-shaped seal 303a at the interface E. The rectangular seal 303b is formed in an annular shape with a central axis C1 at its center. The rectangular seal 303b is formed of an elastic member.

[0100] The other configurations of the third embodiment are the same as those of the first embodiment.

[0101] (Effects of the third embodiment) In the third embodiment, the following effects can be obtained.

[0102] As described above, the third embodiment includes the parking piston portion 307 that moves in the axial direction of the central axis C1 and presses the brake pad 9a when the rotating shaft 6 rotates in one rotation direction while threadedly engaged with the parking threaded portion 60 of the rotating shaft 6, and the braking piston portion 308 that moves in the axial direction away from the brake pad 9a and also moves axially to press the brake pad 9a when the rotating shaft 6 rotates in the other rotation direction opposite to the one rotation direction while threadedly engaged with the braking threaded portion 61 of the rotating shaft 6. This makes it possible to reduce the number of parts in the drive source for braking and parking brake, as in the first embodiment.

[0103] In the third embodiment, as described above, the piston 301 is provided as a common component to the parking piston portion 307 and the braking piston portion 308 so as to cover the parking piston portion 307 and the braking piston portion 308 from the brake pad 9a side, includes a single pad contact member 309 that contacts the brake pad 9a, and the parking piston portion 307 and the braking piston portion 308 are configured to contact and press the brake pad 9a via the pad contact member 309. This ensures a larger contact area between the brake pad 9a and the pad contact member 309 that presses the brake pad 9a compared to when multiple members are switched to press the brake pad 9a, thereby effectively generating frictional force between the pad contact member 309 and the brake pad 9a, thereby maintaining the braking and parking states.

[0104] As described above, the third embodiment further includes a biasing member 302 that biases the parking piston portion 307 and the braking piston portion 308 toward the brake pad 9a and biases the pad contact member 309 in the opposite direction to the parking piston portion 307 and the braking piston portion 308. This allows the biasing member 302 to apply pressure to the parking piston portion 307, the braking piston portion 308, and the pad contact member 309 in directions that move them away from each other, thereby preventing rattling between the relative positions of the pad contact member 309, the parking piston portion 307, and the braking piston portion 308 when switching between the braking state and the parking state, for example.

[0105] Other effects of the third embodiment are the same as those of the first embodiment.

[0106] (Variation) The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims rather than the description of the above embodiments, and further includes all modifications (variations) within the meaning and scope of the claims.

[0107] For example, in the first to third embodiments, the braking screw portion of the rotating shaft is formed by a braking male screw, but the present invention is not limited to this. In the present invention, as in an electric brake device 400 of a first modified example shown in Fig. 7, the braking screw portion 461 of the rotating shaft 406 may be formed by a braking female screw.

[0108] Furthermore, in the first and second embodiments, examples have been shown in which the parking piston portion is formed in an annular shape and the braking piston portion is disposed inside the parking piston portion, but the present invention is not limited to this. In the present invention, as in an electric brake device 500 of a second modified example shown in Fig. 8, the braking piston portion 508 may be formed in an annular shape and the parking piston portion 507 may be disposed inside the braking piston portion 508. In this case, as an example, the rotating shaft is formed in a stepped shape similar to that of the second embodiment.

[0109] Furthermore, as in the electric brake device 600 of the third modified example shown in FIG. 9, the parking screw engagement portion 660 of the rotating shaft 606 may be formed by a parking female screw, and the braking piston portion 608 may be formed in a circular ring shape, with the parking piston portion 607 disposed inside the braking piston portion 608.

[0110] In the first to third embodiments, at least one of the parking screw portion of the rotating shaft and the braking screw portion of the rotating shaft is formed by a male thread, but the present invention is not limited to this. In the present invention, both the parking screw portion of the rotating shaft and the braking screw portion of the rotating shaft may be formed by a female thread.

[0111] In the first to third embodiments, a ball screw is used as the braking screw portion of the rotating shaft, but the present invention is not limited to this. In the present invention, a sliding screw, a trapezoidal screw, or the like may be used as the braking screw portion of the rotating shaft.

[0112] In the first to third embodiments, trapezoidal screws are used for the parking screw engagement portion of the rotating shaft, but the present invention is not limited to this. In the present invention, a sliding screw, a ball screw, or the like may be used for the parking screw engagement portion of the rotating shaft.

[0113] In addition, in the first to third embodiments, the driving force of the motor is indirectly transmitted to the rotating shaft via a plurality of transmission gears, but the present invention is not limited to this. In the present invention, the driving force of the motor may be transmitted directly to the rotating shaft without using transmission gears.

[0114] In the first and second embodiments, the biasing member for biasing the rotating shaft is configured by a disc spring, but the present invention is not limited to this. In the present invention, the biasing member for biasing the rotating shaft may be configured by a coil spring, a rubber member, or the like.

[0115] In addition, in the first to third embodiments, the parking piston portion is configured to move in the A1 direction when the motor rotates forward, but the present invention is not limited to this. In the present invention, the parking piston portion may be configured to move in the A2 direction when the motor rotates forward.

[0116] In the first and second embodiments, the parking piston portion is formed in an annular shape, but the present invention is not limited to this. In the present invention, the parking piston portion may be formed in a C-shape or the like.

[0117] In addition, in the first to third embodiments, examples have been shown in which the electric brake device includes a biasing member that biases the rotating shaft, but the present invention is not limited to this. In the present invention, the electric brake device does not necessarily have to include a biasing member that biases the rotating shaft. [Explanation of symbols]

[0118] 1: Housing, 3: Motor, 6, 206, 406, 606: Rotating shaft, 7, 207, 307, 507, 607: Parking piston portion, 8, 208, 308, 508, 608: Braking piston portion, 9a: Brake pad, 9b: Disc rotor, 60, 660: Parking screw portion (of rotating shaft), 61, 261, 461: Braking screw portion (of rotating shaft), 61a: Ball screw, 62: Outer peripheral surface (of rotating shaft), 63: Inner peripheral surface (of rotating shaft), 64: Contact portion (of rotating shaft), 100, 200, 300, 400, 500, 600: Electric brake device, 101, 201, 301: Piston, 309: Pad contact member, C1: Central axis

Claims

1. A motor; a rotation shaft having a parking screw portion and a braking screw portion with a common central axis, the rotation shaft being rotated by the motor; and a piston including: a parking piston portion that moves in the axial direction of the central axis and presses against brake pads when the rotating shaft rotates in one rotation direction while threadedly engaged with the parking threaded portion; and a braking piston portion that moves in the axial direction to press against the brake pads when the rotating shaft rotates in the other rotation direction opposite to the one rotation direction while threadedly engaged with the braking threaded portion, causing the parking piston portion to move in the direction away from the brake pads in the axial direction.

2. the piston is provided as a common configuration for the parking piston portion and the braking piston portion so as to cover the parking piston portion and the braking piston portion from the brake pad side, and includes a single pad contact member that comes into contact with the brake pad; The electric brake device according to claim 1 , wherein the parking piston portion and the braking piston portion are configured to come into contact with the brake pads via the pad contact members and press the brake pads.

3. the parking screw portion is a parking male screw that is provided on an outer circumferential surface of the rotation shaft and that screws into the parking piston portion, 2. The electric brake device according to claim 1, wherein the braking threaded portion is a ball screw that is provided on an inner peripheral surface of the rotary shaft and that threadably engages with the braking piston portion.

4. a housing that accommodates the rotating shaft, the parking piston portion, and the braking piston portion; the rotation shaft is configured to move in a direction opposite to a pressing direction of the brake pad by the parking piston portion when the rotation shaft receives a reaction force caused by the parking piston portion pressing the brake pad against the disc rotor, The electric brake device according to claim 1 , wherein the rotary shaft includes an abutment portion that abuts against the housing when the rotary shaft moves in the direction opposite to the pressing direction.

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