Electric brake device

Abstract

To downsize an electric brake device.SOLUTION: An electric brake device (10) includes a piston (14) with an exposed portion (14A) exposed from a cylinder (13) within the entire movable range that moves along with the linear motion of a linear motion part (15B), a restricted part (19) extending radially outward beyond the outer periphery of the piston (14) in the radial direction of the piston (14), and a restricting part (18) that restricts the relative rotation of the restricted part (19) with respect to the cylinder (13) around the axis of the piston (14).SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Patent Document 1 discloses an electric braking device including a rotating member that rotates in response to the rotation of an electric motor, a linearly moving member that moves linearly in response to the rotation of the rotating member, and a piston that moves linearly together with the linearly moving member to press a friction member against a brake rotor. In the electric braking device disclosed in Patent Document 1, a groove extending in the moving direction of the linearly moving member is formed on the inner wall surface of a cylinder, an engaging member that engages with the groove is attached to the piston, and the engagement of the engaging member with the groove restricts the piston from rotating around the rotation axis of the rotating member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2023-25962 A Summary of the Invention [Problem to be solved by the invention]

[0004] In an electric braking device, a piston seal may be provided to seal the gap between the outer peripheral surface of the piston and the inner peripheral surface of the cylinder. When attempting to restrict the rotation of the piston around the rotation axis of the rotating member by forming a groove on the inner wall surface of the cylinder and attaching an engaging member to the piston as in Patent Document 1, the electric braking device must be designed so that the groove and the engaging member do not interfere with the piston seal. The direction of the rotation axis of the piston must be longer than the sum of the clearance where the piston seal slides with the piston and the clearance where the engaging member moves linearly while engaging with the groove, making it difficult to reduce the size in the direction of the rotation axis. One aspect of the present disclosure aims to reduce the size of an electric braking device. [Means for solving the problem]

[0005] In order to solve the above problems, an electric braking device according to one embodiment of the present disclosure provides an electric braking device in which a rotating part of a linear motion conversion mechanism rotates in response to the rotational motion of an electric motor, the rotational motion of the rotating part is converted into linear motion in a forward or backward direction of a linear motion part of the linear motion conversion mechanism, and a piston sliding within a cylinder and a friction material are driven by the linear motion in the forward direction of the linear motion part, thereby pressing the friction material against a rotating body that rotates together with a wheel of a vehicle, thereby applying a braking force to the wheel. The piston has an exposed part that is exposed from the cylinder within its entire range of motion in response to the linear motion of the linear motion part, and is provided with a regulated part that is provided on the exposed part and extends radially of the piston outward beyond the outer periphery of the piston, and a regulating part that regulates the relative rotation of the regulated part with respect to the cylinder around the axis of the piston. Effect of the Invention

[0006] According to one aspect of the present disclosure, the electric braking device can be made smaller. [Brief description of the drawings]

[0007] [Figure 1] 1 is a schematic cross-sectional view of an electric braking device according to a first embodiment of the present disclosure. [Diagram 2] FIG. 2 is a schematic diagram showing a cross section taken along line AA in FIG. [Diagram 3] FIG. 11 is a schematic cross-sectional view of an electric braking device according to a third embodiment of the present disclosure. [Figure 4] FIG. 11 is a schematic cross-sectional view of an electric braking device according to a fourth embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] [Embodiment 1] FIG. 1 is a schematic cross-sectional view of an electric braking device according to a first embodiment of the present disclosure. The electric braking device 10 shown in FIG. 1 includes an electric motor 11, a reduction gear mechanism 12, a cylinder 13, brake pads 16 and 17, a restricting portion 18, a restricted portion 19, a claw portion 20, and a bridge portion 21. The cylinder 13 has therein a piston 14 and a linear motion conversion mechanism 15. The linear motion conversion mechanism 15 has a nut 15A and a screw shaft 15B. The brake pads 16 and 17 face each other with a brake rotor 40 therebetween. The brake rotor 40 is an example of a rotating body that rotates together with the wheel of the vehicle. The claw portion 20 is disposed at a position facing the cylinder 13 . The bridge portion 21 is a beam portion of the caliper, and straddles the brake rotor 40 to connect the cylinder 13 and the claw portion 20 . Mount 22 is attached to a non-rotating member of the vehicle and supports brake pads 16 and 17 .

[0009] The electric motor 11 generates a rotational torque by receiving electric power from an external source. The reduction mechanism 12 reduces the speed of the rotation of the electric motor 11 and transmits it to the linear motion conversion mechanism 15. The nut 15A is an example of a rotating part, and rotates by receiving the rotation of the electric motor 11 transmitted via the reduction mechanism 12. The screw shaft 15B is an example of a linear motion part, and moves linearly in the forward or backward direction according to the rotation of the nut 15A. Hereinafter, the forward or backward direction will be referred to as the forward or backward direction. Of the forward or backward movable range of the screw shaft 15B, the forward end will be referred to as the frontmost position, and the backward end will be referred to as the rearmost position.

[0010] The piston 14 is connected to one end of the screw shaft 15B and slides together with the screw shaft 15B in the front-rear direction inside the cylinder 13. When the piston 14 is driven forward, the brake pad 16 is pressed against the brake rotor 40, and a braking force is applied to the vehicle wheels. Here, the piston 14 and the screw shaft 15B are provided with a rotation stopper (not shown) such as a key groove, a two-face width, or a D-cut so that the screw shaft 15B does not rotate relative to the piston 14. As a result, if the relative rotation of the piston 14 with respect to the cylinder 13 is restricted, the relative rotation of the screw shaft 15B with respect to the cylinder 13 is also restricted.

[0011] The piston 14 has an exposed portion 14A. The exposed portion 14A is exposed from the cylinder 13 in the entire movable range of the linear motion of the screw shaft 15B. That is, the exposed portion 14A of the piston 14 is exposed from the cylinder 13 regardless of whether the screw shaft 15B is in any position from the frontmost position to the rearmost position.

[0012] The regulated portion 19 is formed of a rod material having a rigidity that is not deformed by the rotation torque of the electric motor 11. In FIG. 1, the regulated portion 19 has an L-shape. One end of the regulated portion 19 is connected to the exposed portion 14A from the radial direction of the piston 14, and extends outward from the outer periphery of the piston 14. Here, the radial direction of the piston 14 includes not only a direction perpendicular to the central axis of the piston 14, but also a direction parallel to the direction perpendicular to the central axis of the piston 14. The other end 19A of the regulated portion 19 is disposed at a position outside the cylinder 13. In FIG. 1, a connecting portion 14B is provided on a side surface of the exposed portion 14A of the piston 14, and one end of the regulated portion 19 is connected to the connecting portion 14B from the radial direction of the axis of the piston 14.

[0013] The restricting portion 18 is disposed outside the cylinder 13. In Fig. 1, the restricting portion 18 is disposed on the outer periphery of the cylinder 13. The restricted portion 19 passes through the restricting portion 18 on an extension path from one end connected to the connection portion 14B to the other end 19A. The other end 19A of the restricted portion 19 is disposed at a position spaced a predetermined distance from the restricting portion 18 in the backward direction.

[0014] Fig. 2 is a diagram that shows a schematic cross section taken along line AA in Fig. 1. Note that detailed illustration of the cross section of the cylinder 13 is omitted in Fig. 2. Fig. 2(a) shows an outline of the cross section of the regulating portion 18 of the electric braking device 10 according to the first embodiment of the present disclosure.

[0015] 2(a), the restricting portion 18 has a U-shaped cross section and includes a pair of restricting walls 18A and a bottom surface 18B. The restricting portion 18 is disposed such that the bottom surface 18B contacts the outer periphery of the cylinder 13. The restricting portion 18 is fixed so as not to rotate relative to the cylinder 13 due to the rotational torque of the electric motor 11.

[0016] The pair of restricting walls 18A face each other. The pair of restricting walls 18A are perpendicular to the bottom surface 18B and are substantially parallel to the direction from the rotation axis of the cylinder 13 toward the bottom surface 18B. A space is provided between the pair of restricting walls 18A into which the restricted portion 19 can be inserted. The space between the pair of restricting walls 18A extends in the front-rear direction. The other end 19A of the restricted portion 19 is located further backward than the restricting portion 18, regardless of whether the screw shaft 15B is in a position between the rearmost position and the frontmost position.

[0017] The screw shaft 15B may rotate when it moves linearly in the front-rear direction in response to the rotation of the nut 15A. When the screw shaft 15B rotates, the piston 14 and the regulated portion 19 rotate. In the electric braking device 10, when the screw shaft 15B rotates relative to the cylinder 13 by a predetermined angle or more, the regulated portion 19 abuts against one of the pair of regulating walls 18A, and the rotation of the screw shaft 15B, the piston 14, and the regulated portion 19 is locked. This allows the rotation of the nut 15A to be efficiently converted into the linear motion of the screw shaft 15B. The regulated portion 19 can slide in the front-rear direction while abutting against the pair of regulating walls 18A. The pair of regulating walls 18A may be provided with rollers, bearings, or lubricant-applied surfaces on the surfaces abutting against the regulated portion 19, so that the regulated portion 19 can slide smoothly in the front-rear direction.

[0018] The electric braking device 10 is disposed on the wheels of a vehicle, and is therefore disposed in an environment where foreign objects can easily enter, and there is a risk that foreign objects kicked up from the road by the wheels may enter the space between the pair of regulating walls 18A. The regulating portion 18 is provided with an outlet 18C on the entire surface facing the bottom surface 18B. The space between the pair of regulating walls 18A is connected to the outside of the space via the outlet 18C. In a position in which the electric braking device 10 is mounted on a vehicle, the regulating portion 18 may be provided with the outlet 18C located further in the direction of gravity than the bottom surface 18B. Since the space between the pair of regulating walls 18A is connected to the outside of the space in the direction of gravity, foreign objects that have entered the space can be easily discharged.

[0019] The other end 19A of the regulated portion 19 can be disposed in the space between the pair of regulating walls 18A of the regulating portion 18 through the discharge port 18C. The regulated portion 19 can be easily assembled to the electric braking device 10 by matching the direction in which the other end 19A of the regulated portion 19 passes through the discharge port 18C with the direction in which one end of the regulated portion 19 is connected to the connection portion 14B of the exposed portion 14A.

[0020] [Embodiment 2] A second embodiment of the present disclosure will be described below. For ease of explanation, the same reference numerals will be given to members having the same functions as those described in the first embodiment, and the description thereof will not be repeated. Fig. 2(b) is a schematic diagram showing a cross section taken along line AA of an electric braking device according to embodiment 2 of the present disclosure. As shown in Fig. 2(b), the restricting portion 18 in embodiment 2 has a rectangular cross-sectional shape and has a surface 18D facing a bottom surface 18B. This prevents the restricted portion 19 from escaping from the gap between the pair of restricting walls 18A in the radial direction of the cylinder 13, and reduces the deviation in angle between the axial direction of the piston 14 and the axial direction of the cylinder 13.

[0021] [Embodiment 3] 3 is a schematic cross-sectional view of an electric braking device according to a third embodiment of the present disclosure. In the first and second embodiments, the restricting portion 18 is disposed on the outer periphery of the cylinder 13, and the restricted portion 19 is L-shaped. In the third embodiment, the restricting portion 18 is a groove carved in the bridge portion 21. The restricted portion 19 is I-shaped, and moves linearly within the groove of the restricting portion 18 in conjunction with the linear motion of the piston 14. Even if the restricted portion 19 attempts to rotate relative to the cylinder 13, the restricted portion 19 abuts against the side wall of the groove of the restricting portion 18, thereby restricting the relative rotation of the restricted portion 19 and the piston 14 with respect to the cylinder 13.

[0022] [Embodiment 4] 4 is a schematic cross-sectional view of an electric braking device according to a fourth embodiment of the present disclosure. The restricting portion 18 in the fourth embodiment is longer in the front-rear direction than the restricting portion 18 in the first embodiment, and the other end 19A of the restricted portion 19 is housed inside the restricting portion 18. The restricting portion 18 in the fourth embodiment is provided with a dust boot 30 at an opening 18E into which the restricted portion 19 is inserted, thereby preventing the intrusion of foreign matter into the restricting portion 18.

[0023] [Modifications] In the above-mentioned first, second and fourth embodiments, the restricting portion 18 is disposed on the outer periphery of the cylinder 13, and in the third embodiment, the restricting portion 18 is disposed in the gap between the bridge portion 21 and the brake rotor 40. However, the restricting portion 18 can be disposed in any position as long as the relative position with respect to the cylinder 13 does not change. For example, the restricting portion 18 may be disposed in a mount 22 attached to a non-rotating member of the vehicle.

[0024] In the above-mentioned embodiments 1-4, the restricting portion 18 and the restricted portion 19 have a rectangular cross-sectional shape. However, the cross-sectional shape of the restricting portion 18 and the restricted portion 19 is not limited to a rectangle. The cross-sectional shape of the restricting portion and the restricted portion 19 may be, for example, a circle. Moreover, the restricted portion 19 may be twisted like the tip of a drill to promote the discharge of foreign matter to the outside of the restricting portion 18.

[0025] The restricting portion 18 may be formed by providing a hole in the side wall of the cylinder 13. In this case, the restricted portion 19 has an L-shape so as to be inserted into the hole provided in the side wall of the cylinder 13.

[0026] 〔summary〕 In one aspect of the electric braking device of the present disclosure, a rotating part of a linear motion conversion mechanism rotates in response to the rotational motion of an electric motor, the rotational motion of the rotating part is converted into linear motion in a forward or backward direction of a linear motion part of the linear motion conversion mechanism, and a piston sliding within a cylinder and a friction material are driven by the linear motion in the forward direction of the linear motion part, thereby pressing the friction material against a rotating body that rotates together with the wheels of a vehicle, thereby applying a braking force to the wheels.In this electric braking device, the piston has an exposed portion that is exposed from the cylinder within its entire range of motion in response to the linear motion of the linear motion part, and is equipped with a regulated portion that is provided on the exposed portion and extends radially of the piston outward beyond the outer periphery of the piston, and a regulating portion that regulates the relative rotation of the regulated portion with respect to the cylinder centered on the axis of the piston. Since the regulated portion is provided on the exposed portion that is exposed from the cylinder over the entire movable range of the piston, the regulated portion does not interfere with components provided between the cylinder and the piston due to linear motion of the piston. Also, since the regulated portion extends from the exposed portion in the radial direction of the piston, the friction material does not interfere with the regulated portion when the linear motion portion drives the piston and the friction material. By restricting the relative rotation of the restricted portion with respect to the cylinder, the axial length of the piston does not need to be increased in order to avoid interference between the components, and therefore the electric braking device can be made smaller.

[0027] In the electric braking device according to one aspect of the present disclosure, the regulated portion has one end connected to the exposed portion and the other end disposed at a position different from the one end in the axial direction of the piston. According to the above-mentioned configuration, since one end and the other end of the regulated portion are disposed at different positions in the piston axial direction, the position of the regulated portion in the piston axial direction can be set at a position different from the position where the one end of the regulated portion is located, thereby improving the degree of freedom of the position of the regulated portion.

[0028] In one embodiment of the electric braking device of the present disclosure, the regulating portion has a pair of regulating walls facing each other, and the regulated portion passes from the exposed portion through the space between the pair of regulating walls, and when the exposed portion rotates relative to the cylinder by a predetermined angle, the regulated portion abuts against one of the pair of regulating walls, thereby regulating the relative rotation of the regulated portion with respect to the cylinder, and when the electric braking device is in a position mounted on a vehicle, the space between the pair of regulating walls is connected to the outside of the space between the pair of regulating walls in the direction of gravity. According to the above configuration, when the electric braking device is in a position mounted on a vehicle, the space between the pair of regulating walls is open in the direction of gravity. This makes it possible to prevent a foreign object from remaining in the space between the pair of regulating walls even if the foreign object enters the space between the pair of regulating walls from the outside. This makes it difficult for a foreign object to become caught between the pair of regulating walls, which are the regulating portion, and the regulated portion, thereby making it possible to prevent the regulated portion and, ultimately, the linear motion of the piston from being hindered.

[0029] In the electric braking device according to one aspect of the present disclosure, the regulated portion has a rigidity that prevents it from being deformed by the rotational torque generated by the electric motor when the regulated portion abuts against one of the pair of regulating walls. According to the above configuration, the regulated portion has a rigidity that does not deform due to the rotational torque generated by the electric motor, and therefore when the regulated portion abuts against one of the pair of restricting walls, the regulated portion does not deform, and therefore the relative rotation of the regulated portion with respect to the cylinder can be effectively restricted.

[0030] In the electric braking device according to one aspect of the present disclosure, the restricting portion is disposed at a position where the relative position with respect to the cylinder does not change in accordance with the linear motion of the linear moving portion. In the electric braking device according to one aspect of the present disclosure, the restricting portion is disposed on an outer periphery of the cylinder. In one aspect of the present disclosure, the electric braking device includes a claw portion facing the cylinder, and a beam portion connecting the claw portion and the cylinder and spanning the rotor. The restricting portion is a groove formed in the beam portion. The restricting portion may be disposed between the rotor and the beam portion. If the position of the regulating part relative to the cylinder changes in accordance with the linear motion of the linear moving part, it is necessary to increase the length from one end to the other end of the regulated part by the amount of the position change. With the above configuration, the relative position of the regulating part with respect to the cylinder does not change, so there is no need to increase the length from one end to the other end of the regulated part.

[0031] [Additional Notes] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present disclosure. [Explanation of symbols]

[0032] 10 Electric braking device 11 Electric motor 13 Cylinder 14 Piston 14A Exposed part 15 Linear motion conversion mechanism 15A Nut 15B Screw shaft 16 Brake pads 18 Regulatory Department 18A Regulatory Wall 19 Regulated part 19A other end 20 Claw part 21 Bridge section

Claims

1. An electric braking device in which a rotating part of a linear motion conversion mechanism rotates in response to the rotational motion of an electric motor, the rotational motion of the rotating part is converted into linear motion in a forward or backward direction of a linear motion part of the linear motion conversion mechanism, a piston sliding within a cylinder and a friction material are driven by the linear motion in the forward direction of the linear motion part, and the friction material is pressed against a rotating body that rotates together with the wheels of a vehicle, thereby applying a braking force to the wheels, the piston has an exposed portion that is exposed from the cylinder within an entire movable range in response to the linear motion of the linear motion portion, a restricted portion provided on the exposed portion and extending outward beyond an outer periphery of the piston in a radial direction of the piston; a restricting portion that restricts relative rotation of the restricted portion with respect to the cylinder about the axis of the piston.

2. The electric braking device according to claim 1 , wherein the regulated portion has one end connected to the exposed portion and the other end disposed at a position different from the one end in the axial direction of the piston.

3. The restricting portion has a pair of restricting walls facing each other, the regulated portion extends from the exposed portion through a space between the pair of regulating walls, 3. The electric braking device according to claim 1 or 2, wherein when the exposed portion rotates relative to the cylinder by a predetermined angle, the regulated portion abuts against one of the pair of regulating walls, thereby regulating the relative rotation of the regulated portion with respect to the cylinder, and when the electric braking device is in a position mounted on a vehicle, the space between the pair of regulating walls is connected to the outside of the space between the pair of regulating walls in the direction of gravity.

4. The electric braking device according to claim 1 , wherein the restricting portion is disposed at a position where a relative position of the restricting portion with respect to the cylinder does not change in accordance with the linear motion of the linear motion portion.

Images