ELECTRIC BRAKE DEVICE

Abstract

An urging member (56) configured to urge a rotary member (52) from the side of a linear movement member (54) to the side of a transmission mechanism (36) is arranged between the linear movement member (54) and the transmission mechanism (36) in the direction of the rotation axis of the rotary member (52), and the urging member (56) includes a first engagement part engaged with the rotary member (52) and a second engagement part engaged with the housing (14) on the side of the transmission mechanism (36) as the first engagement part.

Description

TECHNICAL FIELD

[0001] The present invention relates to an electric braking device. TECHNICAL BACKGROUND

[0002] Patent Literature 1 discloses a prior art of an electric disc brake, and a configuration of the prior art electric disc brake will be briefly described below.

[0003] An outer side casing, which houses an edge portion of a rotating body (referred to as a drive screw in Patent Literature 1) in a linear motion conversion mechanism (referred to as a thrust generating mechanism in Patent Literature 1), is provided on the opposite side of the cylindrical portion of the brake caliper. An elastic member, which urges the rotating body toward the opposite side (the other side in the axial direction) of a claw portion of the brake caliper, is provided between the inner wall surface of the outer side casing and the edge portion of the rotating body. The elastic member is pressure-welded to the rotating body portion from one side in the axial direction by its elastic force.As a result, the rotating body is held immobile in the axial direction with respect to the caliper by the urging member force, and displacement of the rotating body in the axial direction due to vibration of the wheel is suppressed, so that the vibration resistance of the linear motion conversion mechanism can be improved. CITATION LISTPATENT LITERATURE

[0004] Patent Literature 1: Japanese Patent Application Laid-Open No. 2010-265971 SUMMARY OF THE INVENTION TECHNICAL PROBLEMS

[0005] In Patent Literature 1, the elastic element pushes the rotating body portion from the friction member side to the transmission mechanism side, but the elastic element is supported by the outer side casing, which has a bottom surface on the friction member side. Since the bottom surface of the outer casing supporting the elastic element must be arranged on the linear motion conversion mechanism side, the degree of freedom in the arrangement of the linear motion conversion mechanism is reduced.

[0006] Therefore, one aspect of the present invention is to improve the vibration resistance while increasing the degree of freedom of the arrangement of the linear motion conversion mechanism. SOLUTIONS TO PROBLEMS

[0007] In order to solve the problem described above, an electric brake device according to one aspect of the present invention is an electric brake device in which a rotary motion of an electric motor is transmitted to a linear motion conversion mechanism through a transmission mechanism, a rotary motion transmitted by the transmission mechanism is converted from a rotary motion of a rotary part in the linear motion conversion mechanism into a linear motion of a linear motion part, and a friction member locked to the linear motion of the linear motion part is pressed against a body rotating together with a wheel to generate a braking force on the wheel, the electric brake device includes: a housing configured to accommodate the linear motion conversion mechanism,which is arranged between the friction member and the transmission mechanism in a rotational axis direction of the rotary member, and an urging member which is arranged between the linear movement member and the transmission mechanism in the rotational axis direction and is configured to have a first engagement part which engages with the rotary member and a second engagement part which engages with the housing on the transmission mechanism side which is larger than the first engagement part, and urges the rotary member from the linear movement member side to the transmission mechanism side. ADVANTAGEOUS EFFECTS OF THE INVENTION

[0008] According to one aspect of the present invention, the vibration resistance can be improved while increasing the degree of freedom of the arrangement of the linear motion conversion mechanism. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic cross-sectional view of an electric disc brake according to an embodiment of the present invention. Fig. 2 is an enlarged cross-sectional view of a main part of the Fig. 1 shown electric disc brake. Fig. 3 is an enlarged cross-sectional view taken along line III-III in Fig. 2. Fig. Figure 4 is an enlarged cross-sectional view of IV in Fig. 2. Fig. 5 is an enlarged cross-sectional view for explaining another engagement mode between a peripheral edge portion of a through hole of a leaf spring and a spindle. Fig. 6 is an enlarged cross-sectional view for explaining another engagement mode between the peripheral edge portion of the through hole of the leaf spring and the spindle. DESCRIPTION OF THE EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that in the specification and claims, the rotation axis direction refers to the rotation axis direction of a rotating part. One side in the rotation axis direction refers to a direction toward the outside of the vehicle in the rotation axis direction. The other side in the rotation axis direction refers to a direction toward the inside of the vehicle in the axial direction. In the drawings, "AD" denotes the direction of the rotation axis, "ADo" denotes one side in the rotation axis direction, and "ADi" denotes the other side in the rotation axis direction.

[0010] An embodiment of the present invention will be described with reference to the Fig. 1 to 6. Fig. 1 is a schematic cross-sectional view of an electric disc brake according to an embodiment of the present invention. Fig. 2 is an enlarged cross-sectional view of a main part of the Fig. 1 shown electric disc brake. Fig. 3 is an enlarged cross-sectional view taken along line III-III in Fig. 2. Fig. Figure 4 is an enlarged cross-sectional view of IV in Fig. 2. Fig. 5 and Fig. 6 are enlarged cross-sectional views for explaining another engagement mode between a peripheral edge portion of a through hole of a leaf spring and a spindle. (Electric brake device 10, brake caliper housing 14)

[0011] As in Fig. As shown in Figure 1, an electric braking device 10 according to the embodiment is an electric disc brake configured for braking wheels of a vehicle. The electric braking device 10 includes a caliper housing 14 (corresponding to the housing in the claims) provided so as to intersect the peripheral edge portion of a rotating body 12 from both sides in the direction of the rotation axis of the rotating body 12. The rotating body 12 rotates integrally with a vehicle H. (Claw section 16, cylinder section 18)

[0012] As in Fig. 1, the caliper housing 14 is movably supported in the direction of the rotation axis by a bracket (not shown) provided as a non-rotating member near the rotating body 12. The caliper housing 14 has, on one side toward the rotation axis, a claw portion 16 that protrudes in a direction orthogonal to the direction of the rotation axis. The caliper housing 14 has, on the other side toward the rotation axis, a cylindrical cylinder portion 18 that is open on one side toward the rotation axis. (Outer friction component 20, inner friction component 22)

[0013] As in Fig. 1, the electric brake device 10 includes two friction members 20 and 22 disposed between the claw portion 16 of the caliper housing 14 and the cylinder portion 18. The two friction members 20 and 22 are movably supported on the bracket in the direction of the rotation axis. Of the two friction members 20 and 22, the outer friction member 20, located on one side in the direction of the rotation axis, presses on one side surface of the rotating body 12. The outer friction member 20 is in sliding contact with one side surface of the rotating body 12 in a state of pressing one side surface of the rotating body 12. Of the two friction members 20 and 22, the inner friction member 22, located on the other side in the direction of the rotation axis, presses on the other side surface of the rotating body 12.The inner friction member 22 is in sliding contact with the other side surface of the rotating body 12 in a state of pressing the other side surface of the rotating body 12. (Piston 24)

[0014] As in the Fig. 1 and Fig. 2, a bottomed cylindrical piston 24 is provided in the cylinder portion 18 of the caliper housing 14. The piston 24 presses the inner friction member 22 toward the claw portion side (one side toward the rotation axis) and is movable in the direction of the rotation axis. The other side of the piston 24 toward the rotation axis is open. The piston 24 is non-rotatably fixed to the cylinder portion 18 of the caliper housing 14 by a fixed anti-rotation bolt (not shown) of the cylinder portion 18 of the caliper housing 14. Furthermore, a circumferential groove 18g is formed on the inner peripheral surface of the cylinder portion 18. A piston seal 26 is fitted into a circumferential groove 24g of the cylinder portion 18, and the piston seal 26 is in sliding contact with the outer peripheral surface of the piston 24. (Motor gear unit 28, unit housing 30, electric motor 32, transmission mechanism 36)

[0015] As in Fig. 1 and Fig. 2, a motor transmission unit 28 for driving the electric brake device 10 is provided at a side portion of the cylinder portion 18 of the caliper housing 14. The motor transmission unit 28 includes a unit housing 30 provided at a side portion of the cylinder portion 18 of the caliper housing 14, an electric motor 32 provided in the unit housing 30, and a transmission mechanism 36 connected to an output shaft 34 of the electric motor 32 and configured to increase a torque of the electric motor. (Main drive gear 38, large intermediate gear 42, small intermediate gear 44, driven gear 48)

[0016] As in Fig. 2, the transmission mechanism 36 includes a main drive gear 38 integrally provided with the output shaft 34 of the electric motor 32, and a large intermediate gear 42 rotatably mounted in the unit housing 30 via a gear shaft 40. The large intermediate gear 42 meshes with the main drive gear 38, and the outer diameter of the large intermediate gear 42 is larger than the outer diameter of the main drive gear 38. The transmission mechanism 36 includes a small intermediate gear 44 coaxially disposed with the large intermediate gear 42, and a driven gear 48 rotatably mounted in the unit housing 30 via a radial bearing 46. The outer diameter of the small intermediate gear 44 is smaller than the outer diameter of the large intermediate gear 42.The driven gear 48 meshes with the small intermediate gear 44, and the outer diameter of the driven gear 48 is larger than the outer diameter of the small intermediate gear 44. An internal toothing 48s is formed in a central portion of the driven gear 48. (Linear motion conversion mechanism 50, rotary part 52)

[0017] As in Fig. 2, a linear motion conversion mechanism 50 is provided in the cylindrical portion 18 of the caliper housing 14, which is configured to convert the rotational motion transmitted from the transmission mechanism 36 into linear motion. In other words, the cylindrical portion 18 in which the linear motion conversion mechanism 50 is housed is arranged between the inner friction member 22 and the transmission mechanism 36 in the direction of the rotation axis. The linear motion conversion mechanism 50 includes a rotary part 52 that rotates due to the rotational motion transmitted from the transmission mechanism 36. The rotary part 52 extends in the direction of the rotation axis, and a male spline portion 52s to be splined with the female spline portion 48s of the output gear 48 is formed at a position on the other side in the direction of the rotation axis on the outer peripheral surface of the rotary part 52.When the male portion 52s of the rotary member 52 and the female portion 48s of the driven gear 48 mesh, the rotary member 52 is connected to the driven gear 48. An externally threaded portion 52m is formed at a position on one side toward the rotation axis on the outer peripheral surface of the rotary member 52, and an outer diameter of the externally threaded portion 52m is larger than an outer diameter of the externally geared portion 52s. A concave portion 52g serving as a circumferentially extending portion is formed near the externally threaded portion 52s in the outer peripheral portion of the rotary shaft portion (a position between the externally threaded portion 52m and the externally threaded portion 52s) and has a cylindrical shape concentric with the shaft center of the rotary member 52. (Linear motion part 54)

[0018] As in Fig. As shown in Figure 2, the linear motion conversion mechanism 50 includes a linear motion part 54 that moves linearly in the direction of the rotation axis in conjunction with the rotation of the rotary part 52. The linear motion part 54 is threadedly coupled to the externally threaded portion 52m of the rotary part 52 and is located on an inner side of the piston 24. The linear motion part 54 is formed with an internally threaded portion 54f that is threadedly coupled to the externally threaded portion 52m of the rotary part 52. (Leaf spring 56)

[0019] As in the Fig. 2 to 4, in the cylinder portion 18 of the caliper housing 14, at the end portion on the other side in the direction of the rotation axis, a band-shaped leaf spring 56 is disposed as an urging member and configured to urge the rotary part 52 from the linear motion part 54 side to the transmission mechanism 36 side. In other words, the band-shaped leaf spring 56 is disposed between the linear motion part 54 and the transmission mechanism 36 in the direction of the rotation axis. The leaf spring 56 exerts pressure on the rotary part 52 by pressing the rotary part 52 toward the transmission mechanism 36 side. Moreover, a through hole 56h through which the rotary part 52 is inserted is formed in the central portion of the leaf spring 56, and the inner diameter of the through hole 56h is smaller than the outer diameter of the male spline portion 52s of the rotary part 52 and its surroundings.Note that the shape of the leaf spring 56 is not limited to a band shape.

[0020] A peripheral edge portion of the through-hole 56h of the leaf spring 56 is a first engagement part that engages with the 52g of the rotary member 52. The peripheral edge portion of the through-hole 56h of the leaf spring 56 is relatively rotatable and immovable with respect to the 52g of the rotary member 52. Both end portions 56e of the leaf spring 56 are second engagement parts that engage with the cylinder portion 18 on the transmission mechanism 36 side, while both end portions 56e of the leaf spring 56 serve as first engagement parts. The leaf spring 56 is bent so that a central portion of the leaf spring 56 protrudes to one side in the direction of the rotation axis. In other words, the leaf spring 56 is bent so that both end portions 56e of the leaf spring 56 are located on the side of the transmission mechanism 36 opposite to the peripheral edge portion of the through hole 56h of the leaf spring 56.The peripheral edge portion of the through hole 56h of the leaf spring 56 may be indirectly engaged by another member instead of directly engaging with the circumferential groove 52g of the rotary member 52.

[0021] At the end portion on the other side toward the rotational axis of the cylinder portion 18, two concave portions 18d, each to be engaged with both end portions 56e of the leaf spring 56, are formed so as to be recessed to one side in the rotational axis direction. In other words, the engagement between the two end portions 56e of the leaf spring 56 and the two concave portions 18d of the cylinder portion 18 prevents the two end portions 56e of the leaf spring 56, which constitute the first engagement part, from rotating with respect to the cylinder portion 18. Moreover, the two end portions 56e of the leaf spring 56 are located between the cylinder portion 18 of the caliper housing 14 and the unit housing 30 in a state of engagement with the two concave portions 18d of the cylinder portion 18.

[0022] As in Fig. As shown in FIG. 5, a peripheral edge portion of the through hole 56h of the leaf spring 56 can be engaged with the circumferential groove 52g of the rotating member 52 via a plurality of balls 58 serving as sliding members. In this case, the plurality of balls 58 are configured so as not to be separated from the inside of the circumferential groove 52g of the rotating member 52. Note that the sliding member is not limited to the ball 58, but may be any member that enhances lubrication, such as grease.

[0023] Instead of the circumferential groove 52g, an annular protruding portion 52b may be formed as a convex portion extending in the circumferential direction on the outer peripheral portion of the rotary shaft portion of the rotary member 52, as shown in Fig. 6. The peripheral edge portion of the through hole 56h of the leaf spring 56 may engage with the protruding portion 52b of the rotating member 52. In this case, the inner diameter of the through hole 56h of the leaf spring 56 is smaller than the outer diameter of the protruding portion 52b of the rotating member 52. Instead of forming the annular protruding portion 52b near the male spline portion 52s in the rotating member 52, a plurality of protruding portions may be formed at intervals in the circumferential direction. (Load sensor 62, transmission component 66)

[0024] As in the Fig. 1 and Fig. As shown in Figure 2, a load sensor 62 configured to detect a pressure load of the inner friction member 22, which is a friction member with respect to the rotating body 12, is provided on the opposite side in the cylinder portion 18 of the caliper housing 14. In other words, the load sensor 62 is arranged between the linear motion member 54 and the leaf spring 56 in the direction of the rotation axis. As shown in Fig. 3, a sensor terminal portion 64 of the load sensor 62 is located at a position remote from the leaf spring 56 when viewed from the distal side of the cylinder portion 18 of the caliper housing 14. Note that even if the leaf spring 56 has a shape other than a band shape, the sensor terminal portion 64 is located at a position remote from the leaf spring 56 when viewed from the distal side of the cylinder portion 18 of the caliper housing 14.

[0025] As in the Fig. 1 and Fig. 2, an annular transmission member 66 is provided between the central portion of the rotary member 52 and the load sensor 62 by means of a thrust bearing 68 and a washer 70. The transmission member 66 is configured to transmit a force corresponding to the thrust load of the inner friction member 22 in the direction of the rotation axis from the rotary member 52 to the load sensor 62. In other words, the annular transmission member 66 is provided between the linear motion member 54 and the load sensor 62 in the direction of the rotation axis. (Operation of the electric braking device 10)

[0026] The operation of the electric braking device 10 is described below.

[0027] As in Fig.1, for example, when a driver depresses a brake pedal (not shown), the rotary part 52 is rotated in the forward direction by the drive of the electric motor 32 in a state where the torque of the electric motor 32 is increased by the transmission mechanism 36. Then, the linear movement part 54 moves toward the claw portion 16 side of the caliper housing 14 (one side toward the rotation axis) through the screw connection of the externally threaded portion 52m and the internally threaded portion 54f, and the piston 24 also moves toward the claw portion 16 side of the caliper housing 14 integrally with the linear movement part 54. As a result, the piston 24 abuts the inner friction member 22, and the inner friction member 22 can be pushed toward the claw portion 16 side of the caliper housing 14.When the piston 24 abuts the inner friction member 22, the outer friction member 20 abuts the rotating body 12 as the brake caliper housing 14 moves due to the reaction force received from the rotating body 12 by the slide pin of the caliper housing 14 (not shown). As a result, the two friction members 20 and 22, which are friction members, can be pressed to clamp the rotating body 12 to generate a braking force on the vehicle's wheels. (Operations and Effects)

[0028] The functions and effects of the embodiment of the present invention will be described below.

[0029] In the electric brake device 10, as described above, the leaf spring 56, which urges the linear motion part 52 toward the transmission mechanism 36 side (the other side toward the rotation axis), is disposed between the linear motion part 54 and the transmission mechanism 36 in the rotation axis direction. The two end portions 56e of the leaf spring 56, which are the second engagement portion engaged with the cylinder portion 18, are disposed on the transmission mechanism 36 side as the peripheral edge portion of the through hole 56h of the leaf spring 56, which is the first engagement portion engaged with the rotation part 52 in the rotation axis direction, so that the leaf spring 56, which is the urging member, urges the rotation part 52 from the linear motion part 54 side toward the transmission mechanism 36 side.As a result, the two end portions 56e of the leaf spring 56 do not come into contact with the linear motion part 54, and therefore, the vibration resistance of the linear motion conversion mechanism 50 can be improved by suppressing the displacement of the rotary part 52 in the axial direction due to the vibration (impact) from the wheel while increasing the degree of freedom in the arrangement of the linear motion conversion mechanism 50.

[0030] In particular, when the peripheral edge portion of the through hole 56h of the leaf spring 56 is relatively rotatably engaged with the circumferential groove 52g of the rotating member 52 via a sliding member such as a plurality of balls 58, the rotational movement of the rotating member 52 is less likely to be inhibited by the leaf spring 56. As a result, the operating efficiency of the electric brake device 10 can be improved by further suppressing an increase in lost torque.

[0031] Furthermore, in the electric brake device 10, the load sensor 62 is provided between the linear movement part 54 and the leaf spring 56 in the direction of the rotation axis, and the transmission member 66 is provided between the linear movement part 54 and the load sensor 62 in the direction of the rotation axis. Since the force corresponding to the compression load in the direction of the rotation axis is transmitted from the rotary part 52 to the load sensor 62 through the transmission member 66, when the leaf spring 56 presses the rotary part 52 toward the side of the transmission mechanism 36, the load sensor 62 is pressed via the transmission member 66 to the side of the transmission mechanism 36.As a result, according to the embodiment of the present invention, the displacement of the load sensor 62 in the axial direction due to vibration from the wheels can be suppressed, and effects of suppressing the decrease in the detection accuracy of the load sensor 62 and preventing damage to the load sensor 62 can be obtained. Furthermore, since the transmission member 66 is formed separately from the rotary member 52, there is no portion protruding from the rotary member 52 in the radial direction of the rotary member 53, and thus the rotary member 52 can be formed by rolling, and the rotary member 52 can be manufactured inexpensively.

[0032] Furthermore, in the electric brake device 10, the two end portions 56e of the leaf spring 56, which constitute the second engagement part of the urging member, are prevented from rotating with respect to the cylinder portion 18. That is, since the leaf spring 56 is prevented from rotating with the rotational movement of the rotating member 52, this contributes to suppressing the generation of foreign matter due to sliding and wear of the two end portions 56e of the leaf spring 56 and improving the durability of the leaf spring 56 itself.

[0033] By engaging the two end portions 56e of the band-shaped leaf spring 56 with the two concave portions 18d of the cylindrical portion 18, the rotational locking of the leaf spring 56 can be realized with a simple structure. Here, a convex portion can be provided in the cylindrical portion 18 instead of the concave portion 18d, and the rotational locking can be realized by the engagement between the convex portion and the two end portions 56e of the leaf spring 56.

[0034] Furthermore, by engaging the band-shaped leaf spring 56 with the cylindrical cylinder portion 18, a clearance can be provided between the cylinder portion 18 and the leaf spring 56 in the radial direction of the rotary member 52. This allows the components of the electric braking device 10, such as the sensor terminal portion 64, to be arranged, contributing to the miniaturization of the electric braking device 10.

[0035] The rotary member 52 includes a rotary shaft portion having a cylindrical shape concentric with its shaft center, a concave portion (circumferential groove 52g) or a convex portion (protruding portion 52b) extending in the circumferential direction is formed in an outer peripheral portion of the rotary shaft portion of the rotary member 52, and the urging member is configured as a leaf spring 56 in which a through hole 52h is formed through which the rotary shaft portion of the rotary member 52 is inserted. With the peripheral edge portion of the through hole 56h of the leaf spring 56 as the first engagement part, a uniform force can be applied to the rotary shaft portion of the rotary member 52, and the durability of the linear motion conversion mechanism 50 can be improved compared to a case where a preloaded force is applied to the rotary shaft portion of the rotary member 52.In addition, since the leaf spring 56 and the rotary member 52 can be engaged only by the process of passing the rotary member 52 through the through hole 56h of the leaf spring 56, the assembling property of the electric brake device 10 can be improved. [Additional comments]

[0036] The present invention is not limited to the above-described embodiments, and various modified examples can be implemented within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in various embodiments also belong to the technical scope of the present invention. In the present embodiment, the electric brake device 10 was described as an example of an electric disc brake, but it can also be adapted to a drum brake. Furthermore, the present invention can be adapted to a configuration in which the linear movement part 54 rotates and the rotary part 52 moves linearly. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2010

[0004] JP 265971

[0004]

Claims

[1] An electric braking device in which rotation of an electric motor is transmitted to a linear motion conversion mechanism through a transmission mechanism, wherein a rotational motion transmitted by the transmission mechanism is converted into a linear motion of a linear motion part from a rotational motion of a rotating part in the linear motion conversion mechanism, and wherein a friction member locked with the linear motion of the linear motion part is pressed against a rotating body rotating together with a wheel to generate a braking force on the wheel, the electric braking device comprising: a housing designed to house the linear motion conversion mechanism arranged between the friction member and the transmission mechanism in a rotation axis direction of the rotary member; and an urging member disposed between the linear motion part and the transmission mechanism in the rotation axis direction, and configured to have a first engagement part engaged with the rotation part and a second engagement part engaged with the housing on the transmission mechanism side with respect to the first engagement part, and to urge the rotation part from the linear motion part side to the transmission mechanism side. [2] An electric braking device according to claim 1, further comprising: a load sensor provided between the linear movement part and the urging member in the rotation axis direction and configured to detect a pressure load of the friction member with respect to the rotating body; and a transmission member provided between the linear motion member and the load sensor in the rotation axis direction and configured to transmit a force in the rotation axis direction from the rotary member corresponding to the pressure load on the load sensor. [3] The electric brake device according to claim 1, wherein rotation of the second engagement part with respect to the housing is prevented. [4] An electric brake device according to any one of claims 1 to 3, wherein the urging member is a belt-shaped leaf spring and the housing engaged with the leaf spring has a cylindrical shape. [5] Electric braking device according to claim 1, wherein the rotating part has a rotating shaft section having a cylindrical shape concentric with a shaft center thereof, a concave portion or a convex portion extending in a circumferential direction is formed in an outer peripheral portion of the rotary shaft portion, the urging member is a leaf spring in which a through hole into which the rotary shaft portion is inserted is formed, and a peripheral edge portion of the through hole of the leaf spring is the first engaging part. [6] The electric brake device according to claim 3, wherein the urging member is a belt-shaped leaf spring, and the housing is formed with a concave portion or a convex portion engaged with each of both end portions of the leaf spring to regulate co-rotation of the leaf spring with the rotary member.

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