Electric braking device

Abstract

To manufacture an electric braking device at low cost.SOLUTION: An electric braking device (1) which converts rotation movement of a rotation part (6) into linear movement of a direct-acting part (7), comprises a sleeve (9), and an energization part (12) which energizes a load sensor (14) toward a caliper (2) to which the sleeve (9) is fixed, and the sleeve (9) has a rotation stop part (10) which guides the linear movement of the direct-acting part (7) while stopping the rotation of the direct-acting part (7) in conjunction with the rotation of the rotation part (6), and a support part (11) which supports the energization part (12).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an electric braking device. [Background Art]

[0002] Patent Document 1 discloses a linear actuator comprising: a shaft rotated forward and backward by a motor; a screw nut threadedly mounted on the shaft; and a piston tube fixed to the screw nut and advancing and retracting with rotation of the shaft. The piston tube and the screw nut are connected by a screw nut adapter, and the screw nut adapter prevents rotation of the piston tube. [Prior Art Literature] [Patent Literature]

[0003] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2014-029190 [Summary of the Invention] [Problems to be Solved by the Invention]

[0004] In the linear actuator disclosed in Patent Document 1, the screw nut adapter has a function of preventing rotation of the piston tube, but there is room for improvement in terms of reducing the manufacturing cost of the linear actuator. An object of one aspect of the present invention is to manufacture an electric braking device at low cost. [Means for Solving the Problems]

[0005] To solve the above problems, an electric braking device according to one aspect of the present invention is provided, wherein the rotational motion of an electric motor is transmitted to the rotating part of a linear motion conversion mechanism by a transmission mechanism, the rotational motion of the rotating part is converted into linear motion of the linear motion part of the linear motion conversion mechanism, and a braking force is generated on the wheel by pressing a friction member, which is linked to the linear motion of the linear motion part, against a rotating body that rotates together with the wheel, the electric braking device comprising: a sleeve provided between the transmission mechanism and the friction member in the rotation axis direction of the rotating part and covering the linear motion part; a caliper housing the linear motion conversion mechanism and the sleeve and to which the sleeve is fixed; a load sensor provided between the linear motion part and the caliper in the rotation axis direction and detecting the reaction force of the pressing load on the friction member via the rotating part; and a biasing part having elasticity and biasing the load sensor toward the caliper, wherein the sleeve is configured to have a rotation-preventing part that guides the linear motion of the linear motion part while preventing the rotation of the linear motion part accompanying the rotation of the rotating part, and a support part that supports the biasing part. [Effects of the Invention]

[0006] According to one aspect of the present invention, an electric braking device can be manufactured at low cost. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic cross-sectional view showing an overview of an electric braking device according to Embodiment 1 of the present invention. [Figure 2] Figure 1 is an exploded view showing the disassembled components of the electric braking system, including the linear motion conversion mechanism, sleeve, and load sensor. [Figure 3] Figure 1 is an exploded view showing the disassembled components of the electric braking system, including the linear motion conversion mechanism, sleeve, and load sensor. [Figure 4] This is a schematic cross-sectional view showing an overview of an electric braking device according to Embodiment 2 of the present invention. [Figure 5] Figure 4 is an exploded view showing the disassembled components of the electric braking system, including the linear motion conversion mechanism, sleeve, piston, and load sensor. [Figure 6] Figure 4 is an exploded view showing the disassembled components of the electric braking system, including the linear motion conversion mechanism, sleeve, piston, and load sensor. [Modes for carrying out the invention]

[0008] [Embodiment 1] Hereinafter, Embodiment 1 of the present invention will be described in detail with reference to Figures 1 to 3. In Figure 1, the direction from the transmission mechanism 4 toward the rotating body 16 is the X-axis direction, the direction from the electric motor 3 toward the rotating part 6 is the Y-axis direction, and the direction perpendicular to both the X-axis direction and the Y-axis direction is the Z-axis direction.

[0009] <Overview of Electric Braking System 1> The outline of the electric braking device 1 will be described with reference to Figures 1 to 3. Figure 1 is a schematic cross-sectional view showing an outline of the electric braking device 1 according to Embodiment 1 of the present invention. Figures 2 and 3 are exploded views showing the disassembled state of each component of the electric braking device 1 shown in Figure 1, such as the linear motion conversion mechanism 5, sleeve 9, and load sensor 14. Note that the flange portion 62 is omitted in Figures 2 and 3.

[0010] An example of a device to which the electric braking device 1 is applied is an electromechanical brake called an EMB (Electro Mechanical Brake) installed on a vehicle or the like. As shown in Figure 1, the electric braking device 1 comprises a caliper 2 (corresponding to a housing), a sleeve 9, a biasing part 12, and a load sensor 14. The electric braking device 1 may further comprise an electric motor 3, a transmission mechanism 4, a linear motion conversion mechanism 5, a piston 8, a thrust bearing 13, a friction member 15, and an ECU (Electronic Control Unit) (not shown).

[0011] <Configuration of electric motor 3> The electric motor 3 is the power source for the electric braking system 1. The electric motor 3 is electrically connected to the ECU and is driven based on the control of the ECU. The electric motor 3 is located outside the caliper 2 and is positioned adjacent to the caliper 2. The electric motor 3 has a rotating shaft 31 on which a gear 41 that meshes with gear 42 is provided. When the electric motor 3 is driven, the rotating shaft 31 rotates, and rotational motion is transmitted from gear 41 to gear 42 on the rotating shaft 31.

[0012] <Configuration of transmission mechanism 4> The transmission mechanism 4 is a mechanism that transmits the rotational motion of the electric motor 3 to the rotating part 6 of the linear motion conversion mechanism 5. The transmission mechanism 4 is located outside the caliper 2. The transmission mechanism 4 has gears 41 and 42 to which the rotational motion from the electric motor 3 is transmitted. The transmission mechanism 4 transmits the rotational motion of the electric motor 3 to the rotating part 6 of the linear motion conversion mechanism 5 via the gears 41 and 42. The transmission mechanism 4 has two gears 41 and 42, but it may have three or more gears. The transmission mechanism 4 may also be a reduction mechanism that reduces the rotational motion transmitted from the electric motor 3.

[0013] <Configuration of the Linear Motion Conversion Mechanism 5> The linear motion conversion mechanism 5 is a mechanism that converts the rotational motion of the electric motor 3 transmitted from the transmission mechanism 4 into linear motion. The linear motion conversion mechanism 5 has a rotating part 6 to which the rotational motion of the electric motor 3 is transmitted by the transmission mechanism 4, and a linear motion part 7 that converts the rotational motion of the rotating part 6 into linear motion and moves in a straight line.

[0014] The rotating part 6 comprises a rotating shaft portion 61, a flange portion 62, and a threaded portion 63. The rotating shaft portion 61 has its axis of rotation in the X-axis direction. In other words, the X-axis direction is the axis of rotation of the rotating part 6. The flange portion 62 is provided between the end portion 611 on the friction member 15 side of the rotating shaft portion 61 and the end portion 612 on the transmission mechanism 4 side of the rotating shaft portion 61.

[0015] The flange portion 62 extends from the rotating shaft portion 61 toward the outside of the rotating shaft portion 61 in the radial direction of the rotating shaft portion 61. A gear 42 is provided at an end portion 612 of the rotating shaft portion 61, and meshes with a gear 41. A threaded portion 63 is provided at an end portion 611 of the rotating shaft portion 61. A male thread is formed on the threaded portion 63.

[0016] The linear motion portion 7 is formed with a through hole 71 into which the threaded portion 63 of the rotating portion 6 is inserted. As shown in FIG. 2 and FIG. 3, the linear motion portion 7 has a substantially cylindrical shape. In the present embodiment, the substantially cylindrical shape includes, for example, a shape in which a flat surface is formed on a part of an outer circumferential surface or an inner circumferential surface, and a shape consisting of two cylindrical portions arranged side by side in the X-axis direction and connected to each other. In the case of the linear motion portion 7, the shape of the linear motion portion 7 is a shape in which a flat surface is formed on a part of the outer circumferential surface. Details will be described later.

[0017] A female thread that threadedly engages with the male thread of the threaded portion 63 is formed on an inner circumferential surface of the through hole 71. When the male thread of the threaded portion 63 is threadedly engaged with the female thread of the linear motion portion 7, the rotational motion of the rotating portion 6 is converted into linear motion of the linear motion portion 7. The threaded portion 63 and the linear motion portion 7 may constitute, for example, a ball screw.

[0018] More specifically, when rotational motion in a first rotation direction of the electric motor 3 is transmitted to the rotating portion 6, the linear motion portion 7 linearly moves in the positive X-axis direction, and when rotational motion in a second rotation direction opposite to the first rotation direction of the electric motor 3 is transmitted to the rotating portion 6, the linear motion portion 7 linearly moves in the negative X-axis direction. A tip end 711 of the linear motion portion 7 on the friction member 15 side is fixed to the piston 8. The linear motion portion 7 is, for example, a nut member. Note that the linear motion portion 7 and the piston 8 may be integrated with each other.

[0019] <Configuration of Piston 8> The piston 8 is provided between the linear motion portion 7 and the friction member 15 in the X-axis direction, and covers an outer circumferential surface of the first cylindrical portion 101. The piston 8 has a cylindrical shape. An outer diameter of the piston 8 is not less than an inner diameter of the second cylindrical portion 102, and an inner diameter of the piston 8 is not more than an outer diameter of the second cylindrical portion 102.

[0020] As the linear motion unit 7 moves linearly in the positive X-axis direction, the piston 8 also moves linearly in the positive X-axis direction and is pressed toward the friction member 15 by the linear motion unit 7. Conversely, as the linear motion unit 7 moves linearly in the negative X-axis direction, the piston 8 also moves linearly in the negative X-axis direction. In this way, the piston 8 is linked to the linear motion of the linear motion unit 7. An opening 81 is formed in the piston 8, into which the threaded portion 63, the linear motion unit 7, and the first cylindrical portion 101 of the sleeve 9 are inserted.

[0021] <Configuration of friction member 15> The friction member 15 is a member that presses against a rotating body 16 that rotates together with the wheels H of the vehicle, thereby generating a braking force on the wheels H. The friction member 15 consists of a first friction member 151 located on the side of the linear motion conversion mechanism 5 relative to the rotating body 16, and a second friction member 152 located on the opposite side of the rotating body 16 from the first friction member 151.

[0022] The first friction member 151 is attached to the piston 8 via the mounting plate A1. The second friction member 152 is attached to the caliper 2 via the mounting plate A2. The first friction member 151 is linked to the linear motion of the piston 8. In other words, the first friction member 151 is a member that presses against the rotating body 16 and generates a braking force on the wheel H by being linked to the linear motion of the linear motion unit 7.

[0023] When the first friction member 151 moves linearly in the positive X-axis direction toward the rotating body 16, the rotating body 16 is pressed by the first friction member 151 and the second friction member 152, sandwiching the rotating body 16 between them. When the rotating body 16 is pressed by the first friction member 151 and the second friction member 152, a frictional force is generated between each of the first friction member 151 and the second friction member 152 and the rotating body 16. This frictional force acts on the wheel H as a force in the opposite direction to the rotation of the rotating body 16. As a result, a braking force is generated on the wheel H.

[0024] If the pressing load by the friction member 15 is strong, the frictional force against the rotating body 16 will be strong, and the braking force against the wheel H will be strong. If the pressing load by the friction member 15 is weak, the frictional force against the rotating body 16 will be weak, and the braking force against the wheel H will be weak. On the other hand, when the first friction member 151 moves in the negative X-axis direction, which is the direction away from the rotating body 16, the pressing of the rotating body 16 by the first friction member 151 and the second friction member 152 is released. Since no frictional force is generated against the rotating body 16, the braking force against the wheel H disappears.

[0025] <Caliper 2 Configuration> The caliper 2 is provided on both sides of the rotating body 16 so as to straddle the peripheral edge of the rotating body 16. The caliper 2 houses the linear motion conversion mechanism 5, the piston 8, the sleeve 9, the biasing part 12, the thrust bearing 13, the load sensor 14, and the friction member 15. The caliper 2 has a cylinder portion 21, which opens on the positive X-axis side.

[0026] The linear motion conversion mechanism 5, piston 8, sleeve 9, biasing part 12, thrust bearing 13, and load sensor 14 are arranged within an opening formed in the cylinder part 21. The rotating shaft part 61 is inserted into a through hole 22 formed in the cylinder part 21 and a through hole 43 formed in the outer wall of the transmission mechanism 4.

[0027] <Configuration of sleeve 9 and biasing section 12> The sleeve 9 is provided between the transmission mechanism 4 and the friction member 15 in the X-axis direction and covers the linear motion part 7. The sleeve 9 has an anti-rotation part 10 and a support part 11 and is fixed to the cylinder part 21 of the caliper 2. The sleeve 9 has a cylindrical shape with a first cylindrical part 101 and a cylindrical shape with a second cylindrical part 102 arranged in the X-axis direction. The anti-rotation part 10 prevents the linear motion part 7 from rotating when the rotating part 6 rotates, while guiding the linear motion of the linear motion part 7. In other words, the anti-rotation part 10 prevents the rotation of the linear motion part 7 that accompanies the rotation of the rotating part 6, while guiding the linear motion of the linear motion part 7. Details are described below.

[0028] As shown in Figures 2 and 3, the shape of the anti-rotation portion 10 is substantially cylindrical. More specifically, the anti-rotation portion 10 has a first cylindrical portion 101 and a second cylindrical portion 102 that are arranged side by side in the X-axis direction and connected to each other.

[0029] A through hole 103 is formed in the first cylindrical portion 101 into which the linear motion portion 7 is fitted. In other words, the linear motion portion 7 is fitted into the inner circumferential surface of the first cylindrical portion 101. The first planes 721 and 722, which are planes formed on a part of the outer circumferential surface of the linear motion portion 7, are in contact with the second planes 104 and 105, which are planes formed on a part of the inner circumferential surface of the through hole 103 of the first cylindrical portion 101.

[0030] The linear motion section 7 moves linearly in the X-axis direction while the first planes 721 and 722 are in contact with the second planes 104 and 105, respectively. The through hole 106 formed in the second cylindrical section 102 communicates with the through hole 103. The inner diameter of the second cylindrical section 102 is larger than the inner diameter of the first cylindrical section 101, and the outer diameter of the second cylindrical section 102 is larger than the outer diameter of the first cylindrical section 101. As shown in Figure 1, the threaded section 63 is located inside the through hole 103, and the rotating shaft section 61, flange section 62, thrust bearing 13, and load sensor 14 are located inside the through hole 106.

[0031] As described above, the linear motion part 7 fits into the through hole 103 formed in the substantially cylindrical anti-rotation part 10, and the first planes 721 and 722 formed on a part of the outer circumferential surface of the linear motion part 7 come into contact with the second planes 104 and 105 formed on a part of the inner circumferential surface of the anti-rotation part 10. As a result, the anti-rotation part 10 can prevent the rotation of the linear motion part 7 from occurring due to the rotation of the rotating part 6.

[0032] Furthermore, the process of forming the first planes 721 and 722 on the linear motion section 7 and the second planes 104 and 105 on the anti-rotation section 10 is simpler than the process of forming a protrusion on the linear motion section 7 and forming a groove in the member into which the linear motion section 7 is fitted for the protrusion to fit. Therefore, the electric braking device 1 can be manufactured at a low cost.

[0033] Furthermore, since the rotation-preventing part 10 can prevent the rotation of the linear motion part 7, it becomes unnecessary to form a protrusion on the linear motion part 7 and to form a groove in the member into which the linear motion part 7 is fitted for the protrusion to fit. Also, it becomes unnecessary to form a protrusion on the piston 8 and to form a groove in the cylinder part 21 into which the protrusion to fit. Moreover, in order to fix the load sensor 14, it becomes unnecessary to form a male thread on the piston 8 and to form a female thread in the cylinder part 21 with a diameter larger than the diameter of the piston 8 for the male thread to screw into. Because these processes are unnecessary, the electric braking device 1 can be manufactured at a low cost.

[0034] Furthermore, a second plane 104 may be formed on the inner circumferential surface of the through hole 103, but a second plane 105 may not be formed. In other words, one second plane 104 may be formed on the inner circumferential surface of the through hole 103. In this case, a first plane 721 will be formed on the outer circumferential surface of the linear motion section 7, but a first plane 722 will not be formed. Also, the first cylindrical section 101 and the second cylindrical section 102 may be integrally formed with each other.

[0035] The support portion 11 supports the biasing portion 12. The biasing portion 12 is elastic and is provided on the support portion 11. The biasing portion 12 is, for example, a coil spring. However, the biasing portion 12 is not limited to a coil spring, and may be, for example, a disc spring. If the biasing portion 12 is a coil spring, multiple biasing portions 12 are provided on the support portion 11. If the biasing portion 12 is a disc spring, at least one biasing portion 12 is provided on the support portion 11. The biasing portion 12 biases the load sensor 14 toward the cylinder portion 21 by biasing the flange portion 62 toward the cylinder portion 21 of the caliper 2.

[0036] The support portion 11 is a first step formed on the inner circumferential surface of the anti-rotation portion 10. More specifically, as shown in Figure 3, the support portion 11 is a first step formed between the inner circumferential surface of the first cylindrical portion 101 and the inner circumferential surface of the second cylindrical portion 102, because the inner diameter of the second cylindrical portion 102 is larger than the inner diameter of the first cylindrical portion 101. In other words, the support portion 11 is a first step formed between the through hole 103 and the through hole 106. The support portion 11 is formed on the transmission mechanism 4 side of the first cylindrical portion 101.

[0037] With the above configuration, the biasing portion 12 can be supported by the first step formed on the inner circumferential surface of the anti-rotation portion 10, and the load sensor 14 can be biased toward the caliper 2. In addition, by connecting the first cylindrical portion 101 and the second cylindrical portion 102, a support portion 11 for supporting the biasing portion 12 can be easily formed on the inner circumferential surface of the anti-rotation portion 10.

[0038] Furthermore, as shown in Figures 1 and 2, a second step ST is formed on the outer circumferential surface of the anti-rotation portion 10. The second step ST formed on the outer circumferential surface of the anti-rotation portion 10 restricts the movement of the piston 8 toward the transmission mechanism 4 in the X-axis direction. More specifically, when the piston 8 moves linearly in the negative X-axis direction, the end portion 82 of the piston 8 on the transmission mechanism 4 side comes into contact with the second step ST. As a result, the movement of the piston 8 toward the transmission mechanism 4 is restricted by the second step ST.

[0039] The second step ST formed on the outer circumferential surface of the anti-rotation portion 10 provides a function to restrict the movement of the piston 8 toward the transmission mechanism 4 in the X-axis direction relative to the sleeve 9. By shaping the sleeve 9 so that a first cylindrical portion 101 and a second cylindrical portion 102 of different diameters are arranged side by side, the first step formed on the inner circumferential surface of the sleeve 9 and the second step ST formed on the outer circumferential surface of the sleeve 9 can be given different functions.

[0040] Therefore, without complicating the shape of the sleeve 9, the sleeve 9 can have three functions: guiding the linear motion of the linear motion unit 7, biasing the load sensor 14 toward the caliper 2, and restricting the movement of the piston 8 toward the transmission mechanism 4. Thus, the number of parts in the electric brake device 1 can be reduced, and the electric brake device 1 can be manufactured at a low cost.

[0041] Furthermore, the second step ST formed on the outer circumferential surface of the anti-rotation portion 10 is a step formed between the outer circumferential surface of the first cylindrical portion 101 and the outer circumferential surface of the second cylindrical portion 102 because the outer diameter of the first cylindrical portion 101 is smaller than the outer diameter of the second cylindrical portion 102. By connecting the first cylindrical portion 101 and the second cylindrical portion 102, the second step ST that restricts the movement of the piston 8 toward the transmission mechanism 4 can be easily formed on the outer circumferential surface of the anti-rotation portion 10. The length of the first cylindrical portion 101 along the X-axis direction is such that the piston 8 does not come out of the first cylindrical portion 101 even if the friction member 15 is worn out.

[0042] <Securing the second cylindrical portion 102 to the cylinder portion 21> The second cylindrical portion 102 is fixed to the cylinder portion 21 of the caliper 2. More specifically, the second cylindrical portion 102 is fixed to the cylinder portion 21 by fastening a screw that passes through a through hole formed in the bottom portion 211 of the cylinder portion 21 to a screw hole formed in the end portion 102E of the second cylindrical portion 102 on the transmission mechanism 4 side. Alternatively, the second cylindrical portion 102 may be fixed to the cylinder portion 21 by fastening a screw that passes through a through hole formed in the end portion 102E to a screw hole formed in the bottom portion 211.

[0043] As a variation, the second cylindrical portion 102 may be fixed to the cylinder portion 21 by fastening a screw that passes through a through hole formed in the side portion 212 of the cylinder portion 21 to a screw hole formed on the outer circumferential surface of the second cylindrical portion 102. Alternatively, the second cylindrical portion 102 may be fixed to the cylinder portion 21 by fastening a screw that passes through a through hole formed on the outer circumferential surface of the second cylindrical portion 102 to a screw hole formed in the side portion 212.

[0044] As yet another variation, the second cylindrical portion 102 may be fixed to the cylinder portion 21 by screwing the male threads formed on the outer circumferential surface of the second cylindrical portion 102 into the female threads formed on the inner circumferential surface of the cylinder portion 21.

[0045] <Configuration of thrust bearing 13 and load sensor 14> The thrust bearing 13 is arranged between the flange portion 62 and the load sensor 14 in the X-axis direction. The load sensor 14 is provided between the linear motion portion 7 and the caliper 2 in the X-axis direction, and detects the reaction force of the pressing load of the friction member 15 via the rotation portion 6. More specifically, the load sensor 14 is provided between the thrust bearing 13 and the cylinder portion 21 in the X-axis direction. As shown in FIG. 2 and FIG. 3, the load sensor 14 is, for example, an annular load sensor. The load sensor 14 is not limited to an annular load sensor, and may be a button-type load sensor.

[0046] <Configuration of ECU> The ECU is a control unit that controls the electric braking device 1. The ECU comprises a computer having a processor such as a CPU (Central Processing Unit) and a memory such as a RAM or a ROM, and further comprises a drive circuit for driving the electric motor 3, and an input / output interface for acquiring data of the reaction force of the pressing load detected by the load sensor 14.

[0047] The ECU is arranged outside the caliper 2, and is electrically connected to the electric motor 3 and the load sensor 14. The ECU controls the braking force applied to the wheel H by controlling the rotation speed per unit time of the electric motor 3 based on the data of the reaction force of the pressing load detected by the load sensor 14.

[0048] As described above, the sleeve 9 fixed to the caliper 2 has two functions: a function of guiding the linear motion of the linear motion portion 7 while preventing rotation of the linear motion portion 7 accompanying rotation of the rotation portion 6, and a function of biasing the load sensor 14 toward the caliper 2. Accordingly, compared with a case where the caliper 2 is provided with the above two functions, machining of the caliper 2 is simplified, and the electric braking device 1 can be manufactured at low cost.

[0049] [Embodiment 2] Embodiment 2 of the present invention will be described below. For the sake of convenience, components having the same function as those described in Embodiment 1 will be denoted by the same reference numerals, and their descriptions will not be repeated. Figure 4 is a schematic cross-sectional view showing an overview of the electric braking device 1A according to Embodiment 2 of the present invention. Figures 5 and 6 are exploded views showing the disassembled state of the components of the electric braking device 1A shown in Figure 4, including the linear motion conversion mechanism 5A, sleeve 9A, piston 8A, and load sensor 14. Note that the flange portion 62 is omitted in Figures 5 and 6.

[0050] As shown in Figure 4, the electric brake 1A differs from the electric brake 1 in that the linear motion conversion mechanism 5 is changed to a linear motion conversion mechanism 5A, the piston 8 is changed to a piston 8A, and the sleeve 9 is changed to a sleeve 9A.

[0051] <Configuration of the linear motion conversion mechanism 5A> The linear motion conversion mechanism 5A differs from the linear motion conversion mechanism 5 in that the rotating part 6 is replaced with a rotating part 6A, and the linear motion part 7 is replaced with a pressing part 7A. The rotating part 6A differs from the rotating part 6 in that it has a screw part 63A instead of a screw part 63, and it also has a connecting part 64. A connecting part 64 is provided at the end 611 of the rotating shaft part 61. The connecting part 64 connects the rotating shaft part 61 and the screw part 63A. An opening hole 65 is formed in the screw part 63A, and a female thread is formed on the inner circumferential surface of the opening hole 65. The screw part 63A is, for example, a nut member.

[0052] The pressing portion 7A presses the bottom surface of the opening hole 81A formed in the piston 8A toward the friction member 15. The pressing portion 7A has a threaded portion 71A and a pressing plate 72A. The threaded portion 71A has a male thread that screws into the female thread of the opening hole 65. When the male thread of the threaded portion 71A screws into the female thread of the opening hole 65, the rotational motion of the rotating portion 6A is converted into the linear motion of the pressing portion 7A.

[0053] The end portion 711A of the threaded portion 71A on the friction member 15 side is fixed to the pressing plate 72A. The pressing plate 72A extends along the YZ plane. The shape of the pressing plate 72A is approximately disc-shaped. As the pressing portion 7A moves linearly in the positive X-axis direction, the pressing plate 72A comes into contact with the bottom surface of the opening hole 81A. As a result, the piston 8A moves linearly in the positive X-axis direction and is pressed toward the friction member 15 by the pressing portion 7A.

[0054] <Configuration of Piston 8A> The piston 8A differs from the piston 8 in that the opening hole 81 is changed to an opening hole 81A. As shown in Figures 5 and 6, the shape of the piston 8A is substantially cylindrical. The fourth planes 82A and 83A, which are planes formed on a part of the inner circumferential surface of the opening hole 81A, abut against the fifth planes 73A and 74A, which are planes formed on a part of the outer circumferential surface of the pressing plate 72A. The linear motion part according to this embodiment is the part having the piston 8A and the pressing part 7A.

[0055] <Sleeve 9A> Sleeve 9A differs from sleeve 9 in that the anti-rotation portion 10 is changed to anti-rotation portion 10A. The anti-rotation portion 10A differs from anti-rotation portion 10 in that the first cylindrical portion 101 is changed to first cylindrical portion 101A. The shape of the anti-rotation portion 10A is substantially cylindrical. The anti-rotation portion 10A fits into the opening hole 81A formed in piston 8A. More specifically, the first cylindrical portion 101A fits into the opening hole 81A.

[0056] When the first cylindrical portion 101A is fitted into the opening hole 81A, the third planes 104A and 105A, which are planes formed on a part of the outer circumferential surface of the first cylindrical portion 101A, come into contact with the fourth planes 82A and 83A, which are planes formed on a part of the inner circumferential surface of the piston 8A. As the third planes 104A and 105A come into contact with the fourth planes 82A and 83A, respectively, and the fifth planes 73A and 74A come into contact with the fourth planes 82A and 83A, respectively, the pressing portion 7A moves linearly in the X-axis direction.

[0057] With the above configuration, the piston 8A is prevented from rotating relative to the sleeve 9A fixed to the caliper 2, and the pressing part 7A is prevented from rotating relative to the piston 8A. Therefore, the third planes 104A and 105A come into contact with the fourth planes 82A and 83A, respectively, thereby preventing the rotation of the piston 8A and the pressing part 7A from occurring in conjunction with the rotation of the rotating part 6A.

[0058] Furthermore, the process of forming third planes 104A and 105A on the anti-rotation portion 10A and fourth planes 82A and 83A on the piston 8A is simpler than the process of forming a groove on the piston 8A and forming a protrusion on the member fitted to the piston 8A that fits into the groove. Therefore, the electric braking device 1A can be manufactured at a low cost.

[0059] Furthermore, by using a linear motion section having a substantially cylindrical piston 8A and a pressing section 7A that presses the bottom surface of an opening 81A formed in the piston 8A toward the friction member 15, the rotation of the linear motion section accompanying the rotation of the rotating section 6A can be prevented by the rotation-preventing section 10A.

[0060] <Variation> In the electric braking device 1 shown in Figure 1, when the first cylindrical portion 101 is fitted into the opening hole 81, two third planes formed on a part of the outer circumferential surface of the first cylindrical portion 101 may each come into contact with two fourth planes formed on a part of the inner circumferential surface of the piston 8. In this case, the linear motion portion 7 moves linearly in the X-axis direction while the two third planes each come into contact with the two fourth planes.

[0061] Furthermore, in the modified example, the first planes 721 and 722 are not formed on the outer circumferential surface of the linear motion section 7, and the second planes 104 and 105 are not formed on the inner circumferential surface of the through hole 103 of the first cylindrical section 101. In this case, the shapes of the linear motion section 7 and the first cylindrical section 101 are cylindrical. As a result, a plane is formed on at least a part of the inner circumferential surface or the outer circumferential surface of the first cylindrical section 101.

[0062] The present invention is not limited to the embodiments described above, 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 invention. [Explanation of symbols]

[0063] 1. 1A Electric braking system 2. Caliper 3. Electric motor 4. Transmission mechanism 5, 5A Linear motion conversion mechanism 6, 6A Rotating part 7. Linear motion section 7A. Pressing section 8, 8A Piston 9, 9A Sleeve 10, 10A Anti-rotation part 11 Support part 12 biasing unit 14 load sensor 15 Friction member 16 Rotating body 103 Through hole 81A Open hole 101, 101A First cylindrical section 102 Second cylindrical section 721, 722 1st plane 104, 105 2nd plane 104A, 105A 3rd plane 82A, 83A 4th plane ST 2nd step H Wheel

Claims

1. In an electric braking device in which the rotational motion of an electric motor is transmitted by a transmission mechanism to the rotating part of a linear motion conversion mechanism, the rotational motion of the rotating part is converted into linear motion of the linear motion part of the linear motion conversion mechanism, and a braking force is generated on the wheel by pressing a friction member, which is linked to the linear motion of the linear motion part, against a rotating body that rotates together with the wheel, In the rotational axis direction of the rotating part, a sleeve is provided between the transmission mechanism and the friction member, covering the linear motion part, A housing that houses the linear motion conversion mechanism and the sleeve, and in which the sleeve is fixed, A load sensor is provided between the linear motion part and the housing in the rotation axis direction, and detects the reaction force of the pressing load on the friction member via the rotating part. It comprises an elastic biasing part that biases the load sensor toward the housing, The electric braking device is configured such that the sleeve has a rotation-preventing portion that guides the linear motion of the linear motion portion while preventing the rotation of the linear motion portion that occurs with the rotation of the rotating portion, and a support portion which is a first step formed on the inner circumferential surface of the rotation-preventing portion that supports the biasing portion.

2. The shape of the anti-rotation part is substantially cylindrical. The linear motion part is fitted to the inner circumferential surface of the anti-rotation part, The electric braking device according to claim 1, wherein the rotation of the linear motion part is prevented by the contact between a first plane, which is a plane formed on a part of the outer circumferential surface of the linear motion part, and a second plane, which is a plane formed on a part of the inner circumferential surface of the anti-rotation part.

3. The shape of the anti-rotation part and the linear motion part is substantially cylindrical. The anti-rotation part fits into the opening hole formed in the linear motion part. The electric braking device according to claim 1, wherein the rotation of the linear motion part is prevented by the contact between a third plane, which is a plane formed on a part of the outer circumferential surface of the anti-rotation part, and a fourth plane, which is a plane formed on a part of the inner circumferential surface of the linear motion part.

4. The sleeve comprises a first cylindrical portion and a portion whose inner and outer diameters are both larger than the first cylindrical portion. The second cylindrical part is a large cylindrical shape, and the two cylindrical parts are arranged in the direction of the rotation axis. A cylindrical piston that is interlocked with the linear motion section, the piston covers the outer surface of the first cylindrical section, has an outer diameter greater than or equal to the inner diameter of the second cylindrical section, and an inner diameter less than or equal to the outer diameter of the second cylindrical section. The first step is formed between the inner surface of the first cylindrical portion and the inner surface of the second cylindrical portion because the inner diameter of the second cylindrical portion is larger than the inner diameter of the first cylindrical portion. The electric braking device according to claim 1 or 2, wherein the outer diameter of the first cylindrical portion is smaller than the outer diameter of the second cylindrical portion, and a second step is formed between the outer circumferential surface of the first cylindrical portion and the outer circumferential surface of the second cylindrical portion, thereby restricting the movement of the piston toward the transmission mechanism.

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