Rotation transmission device

Abstract

To provide a rotation transmission device capable of efficiently arranging a non-contact sensor as an example.SOLUTION: A rotation transmission device according to an embodiment includes, for example, a rotation body configured to rotate around a first rotation axis, a first gear separated from the rotation body in one axial direction along the first rotation axis, configured to rotate integrally with the rotation body around the first rotation axis, and having an outer diameter smaller than that of the rotation body, a second gear rotatable around a second rotation axis parallel to the first rotation axis, meshing with the first gear, and having an outer diameter different from that of the first gear, and a non-contact sensor having a detection unit separated from the first rotation axis by more than half of the outer diameter of the first gear in a direction orthogonal to the first rotation axis and separated from the rotation body in the axial direction, and configured to detect a rotation angle of the rotation body by the detection unit.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a rotation transmission device. [Background technology]

[0002] Conventionally, there is known a device equipped with a rotation transmission mechanism that transmits rotation. The device further includes a sensor that detects the rotation angle in order to control the rotation angle. For example, the sensor is provided in a motor and detects the rotation angle of the motor (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-075857 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in a conventional configuration, when a device includes a general-purpose motor, it also includes a sensor different from the motor. The placement of the sensor can affect the efficiency of space utilization in the rotation transmission device.

[0005] Therefore, the present invention has been made in view of the above, and provides a rotation transmission device in which a non-contact sensor can be efficiently arranged. [Means for solving the problem]

[0006]

[0010] A rotation transmission device according to an embodiment of the present invention includes, as an example, a rotor configured to rotate about a first rotation axis, a first gear spaced from the rotor in an axial direction along the first rotation axis and configured to rotate integrally with the rotor about the first rotation axis and having an outer diameter smaller than that of the rotor, a second gear rotatable about a second rotation axis parallel to the first rotation axis and meshing with the first gear and having an outer diameter different from that of the first gear, and a non-contact sensor having a detector spaced from the first rotation axis in a direction perpendicular to the first rotation axis by more than half the outer diameter of the first gear and spaced from the rotor in the axial direction, the detector configured to detect the rotation angle of the rotor using the detector. Thus, as an example, the detector can be disposed in a dead space beside the first gear due to the meshing of the first gear and the second gear. Therefore, the rotation transmission device can be prevented from becoming larger in size in the direction along the first rotation axis or the second rotation axis. The detection unit may be located axially farther from the rotating body than the first gear. In other words, the rotation transmission device can prevent restrictions on the placement of the detection unit. As described above, the rotation transmission device can efficiently place the non-contact sensor. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a front view schematically showing a braking device according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view schematically showing a part of the braking device of the first embodiment taken along line F2-F2 in FIG. [Figure 3] FIG. 3 is a cross-sectional view showing a part of the rotation transmission mechanism of the first embodiment. [Figure 4] FIG. 4 is a plan view schematically showing the ratchet gear and the locking device of the first embodiment. [Figure 5] FIG. 5 is a plan view schematically showing a ratchet gear and a locking device according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] (First embodiment) The first embodiment will be described below with reference to FIGS. 1 to 4. In this specification, components according to the embodiment and descriptions of the components may be described using multiple expressions. The components and their descriptions are merely examples and are not limited by the expressions in this specification. The components may also be identified by names different from those in this specification. Furthermore, the components may also be described using expressions different from those in this specification.

[0009] In the following description, "suppress" is defined as, for example, preventing an event, action, or influence from occurring, or reducing the severity of an event, action, or influence. Also, in the following description, "restrict" is defined as, for example, preventing movement or rotation, or allowing movement or rotation within a predetermined range and preventing movement or rotation beyond the predetermined range.

[0010] FIG. 1 is a front view that schematically shows a braking device 10 according to a first embodiment. FIG. 2 is a cross-sectional view that schematically shows a part of the braking device 10 according to the first embodiment, taken along line F2-F2 in FIG. 1. The braking device 10 is a disc brake that is mounted on a vehicle 1 such as a four-wheeled automobile. However, the braking device 10 is not limited to this example. As shown in FIG. 1, the braking device 10 has a disc rotor 11 and an electromechanical brake (EMB) 12. However, the EMB 12 may be an electric parking brake (EPB) that can also function as a hydraulic service brake. The EMB 12 is an example of a rotation transmission device.

[0011] The disc rotor 11 rotates around a central axis Axd integrally with the wheel of the vehicle 1. The central axis Axd is, for example, the central axis of an axle, the central axis of the disc rotor 11, and also the central axis of rotation of the disc rotor 11. Note that the central axis Axd is not limited to this example.

[0012] Hereinafter, the direction along the central axis Axd will be referred to as the axial direction. The axial direction is a direction that is approximately along the width of the vehicle 1, and includes the outward direction Do and the inward direction Di shown in FIG. 2. The outward direction Do is a direction that is along the central axis Axd. The inward direction Di is the opposite direction to the outward direction Do. For example, the outward direction Do is a direction toward the outside of the vehicle 1, and the inward direction Di is a direction toward the inside of the vehicle 1.

[0013] 1, the disc rotor 11 has a rotor body 11a and a hat portion 11b. The rotor body 11a is formed in a disk shape that is substantially perpendicular to the central axis Axd. The hat portion 11b is formed in a substantially cylindrical shape and is coupled to, for example, an axle of the vehicle 1.

[0014] 2, the EMB 12 includes a caliper 21, a pair of brake pads 22, a rotary-to-linear motion conversion mechanism 23, a drive device 24, and an electronic control unit (ECU) 25. The drive device 24 may also be referred to as a motor gear unit (MGU).

[0015] The caliper 21 is, for example, a floating caliper. However, the caliper 21 may be another type of caliper, such as an opposed caliper. The caliper 21 is disposed so as to straddle the rotor body 11a. As shown in FIG. 1, the caliper 21 includes a mounting 31, a caliper body 32, and a piston 33.

[0016] The mounting 31 is fixed to a non-rotating portion of the vehicle 1. The mounting 31 supports the brake pads 22, the caliper body 32, and the piston 33 so that they can move in the axial direction. As shown in Fig. 2, the caliper body 32 has a cylinder 41, a pawl 42, and a bridge 43.

[0017] The cylinder 41 is provided with a bore 45 and a groove 46. The bore 45 penetrates the cylinder 41 along the central axis Axc. Note that the bore 45 may be a recess that is open in the outward direction Do.

[0018] The central axis Axc is the central axis of the bore 45, extending substantially parallel to the central axis Axd of the disc rotor 11. Since the central axis Axc is substantially parallel to the central axis Axd, the outward direction Do and the inward direction Di are also directions along the central axis Axc.

[0019] The cylinder 41 has an inner circumferential surface 45a that defines the bore 45. The inner circumferential surface 45a is a cylindrical curved surface that extends along the central axis Axc. The inner circumferential surface 45a faces the central axis Axc. The groove 46 is provided in the inner circumferential surface 45a and extends in the axial direction.

[0020] The claws 42 are spaced apart in the outward direction Do from the cylinder 41. A bridge 43 connects the cylinder 41 and the claws 42. The rotor body 11a of the disc rotor 11 and the pair of brake pads 22 are disposed between the cylinder 41 and the claws 42.

[0021] The piston 33 is formed in a generally cylindrical shape that is open inwardly Di. The piston 33 has an outer circumferential surface 33a and a key 33b. The outer circumferential surface 33a is a generally cylindrical curved surface that extends along the central axis Axc.

[0022] The piston 33 is fitted into the bore 45 so as to be movable along the central axis Axc. A portion of the piston 33 may be located outside the bore 45. The diameter of the outer peripheral surface 33a of the piston 33 is slightly smaller than the diameter of the inner peripheral surface 45a that defines the bore 45. Therefore, the outer peripheral surface 33a and the inner peripheral surface 45a face each other with a gap therebetween. The key 33b protrudes from the outer peripheral surface 33a and fits into the groove 46.

[0023] The pair of brake pads 22 are spaced apart from each other along the central axis Axc. One of the pair of brake pads 22 contacts the piston 33. The rotor body 11a of the disc rotor 11 is disposed between the pair of brake pads 22.

[0024] The rotary-linear motion conversion mechanism 23 has a rotary member 51 and a linear motion member 52. The rotary member 51 may also be referred to as a bolt. The linear motion member 52 may also be referred to as a nut. The caliper body 32 accommodates at least a portion of the rotary member 51 and at least a portion of the linear motion member 52 in the bore 45.

[0025] The rotation member 51 is formed in a generally cylindrical shape extending along the central axis Axc. On the other hand, the linear motion member 52 is formed in a generally cylindrical shape extending along the central axis Axc. The rotation member 51 extends through the inside of the linear motion member 52.

[0026] For example, a male screw is provided on the rotating member 51, and a female screw is provided on the linear moving member 52. The male screw of the rotating member 51 and the female screw of the linear moving member 52 are meshed with each other. Therefore, when the rotating member 51 rotates around the central axis Axc, the linear moving member 52 moves along the central axis Axc. Note that the rotary-linear motion conversion mechanism 23 may be a ball screw in which a ball is interposed between the rotating member 51 and the linear moving member 52.

[0027] The drive device 24 has an electric motor 61 and a rotation transmission mechanism 62. The electric motor 61 is an example of a motor. The rotation transmission mechanism 62 may also be referred to as a speed reducer. Note that the rotation transmission mechanism 62 is not limited to this example and may be another rotation transmission mechanism such as a speed increaser.

[0028] The electric motor 61 is, for example, a three-phase brushless motor. However, other types of motors may be used as the electric motor 61. The electric motor 61 has a motor body 71 and a motor shaft 72.

[0029] The motor body 71 includes, for example, a rotor, a stator, and a case that houses the rotor and the stator. The motor shaft 72 is coupled to the rotor of the motor body 71. The motor shaft 72 and the rotor of the motor body 71 may be integrally formed.

[0030] The motor shaft 72 is formed in a generally cylindrical shape extending along a central axis Axm. The central axis Axm is an example of a first rotation axis. For convenience, the radial direction and the circumferential direction are defined in this specification. The radial direction is a direction perpendicular to the central axis Axm. The circumferential direction is a direction around the central axis Axm.

[0031] The central axis Axm is, for example, the central axis of the motor shaft 72 and the rotor and stator of the motor main body 71. Note that the central axis Axm is not limited to this example. The electric motor 61 rotates the motor shaft 72 around the central axis Axm.

[0032] The central axis Axm extends substantially parallel to the central axes Axd and Axc. Therefore, the outward direction Do and the inward direction Di are also directions along the central axis Axm. The motor shaft 72 protrudes in the inward direction Di from the motor body 71. Note that the motor shaft 72 may also protrude in the outward direction Do from the motor body 71.

[0033] Fig. 3 is a cross-sectional view showing a portion of the rotation transmission mechanism 62 of the first embodiment. As shown in Fig. 3, the rotation transmission mechanism 62 has a case 81, three shafts 82, 83, and 84, two small gears 85 and 86, two large gears 87 and 88, a ratchet gear 91, a locking device 92, a rotation angle sensor 93, and a cover 94. The small gear 85 is an example of a first gear. The large gear 87 is an example of a second gear. The ratchet gear 91 is an example of a rotating body and a third gear. The rotation angle sensor 93 is an example of a non-contact sensor.

[0034] The case 81 is attached to an end of the cylinder 41 in the inward direction Di and closes an end of the bore 45 in the inward direction Di. Furthermore, an end of the motor body 71 in the inward direction Di is attached to the case 81. The case 81 is provided with an accommodation chamber 101 and two through holes 102, 103.

[0035] The accommodation chamber 101 is provided inside the case 81. A portion of the shaft 82, a portion of the shaft 83, the shaft 84, the pinion gears 85 and 86, the gears 87 and 88, the ratchet gear 91, at least a portion of the locking device 92, the rotation angle sensor 93, and the cover 94 are arranged in the accommodation chamber 101.

[0036] The through hole 102 extends along the central axis Axm and connects the accommodation chamber 101 to the outside of the case 81. The through hole 103 extends along the central axis Axc and connects the accommodation chamber 101 to the bore 45 of the cylinder 41.

[0037] The shaft 82 is formed in a generally cylindrical shape extending along the central axis Axm. The shaft 82 passes through the through-hole 102 and extends from the accommodation chamber 101 to the outside of the case 81. The shaft 82 is supported by the case 81, for example via a bearing, so as to be rotatable around the central axis Axm.

[0038] The end of the shaft 82 in the outward direction Do is connected to the end of the motor shaft 72 in the inward direction Di by, for example, an Oldham coupling. As a result, the electric motor 61 rotates the motor shaft 72 and the shaft 82 integrally around the central axis Axm. Note that the motor shaft 72 and the shaft 82 may be formed integrally.

[0039] The shaft 83 is formed in a generally cylindrical shape extending along the central axis Axc. The shaft 83 passes through the through-hole 103 and extends between the accommodation chamber 101 and the bore 45. The shaft 83 is supported by the case 81, for example, via a bearing, so as to be rotatable around the central axis Axc.

[0040] 2, the end of shaft 83 in the outward direction Do is connected to rotating member 51 of rotary-to-linear motion conversion mechanism 23 by, for example, a universal joint. This allows rotating member 51 and shaft 83 to rotate integrally around central axis Axc. Alternatively, rotating member 51 and shaft 83 may be formed integrally.

[0041] As shown in FIG. 3, the shaft 84 is formed in a substantially cylindrical shape extending along the central axis Axi. The central axis Axi is an example of a second rotation axis. The central axis Axi is, for example, the central axis of the shaft 84. However, the central axis Axi is not limited to this example. The central axis Axi extends substantially parallel to the central axes Axd, Axc, and Axm. Therefore, the outward direction Do and the inward direction Di are also directions along the central axis Axi. The shaft 84 is supported by the case 81, for example via a bearing, so as to be rotatable around the central axis Axi.

[0042] The pinion 85 is provided on the shaft 82. Therefore, the pinion 85 is rotatable about the central axis Axm integrally with the shaft 82. The pinion 85 may be attached to the shaft 82 or may be formed integrally with the shaft 82.

[0043] The pinion 86 and the gear 87 are provided on the shaft 84. Therefore, the pinion 86 and the gear 87 are rotatable around the central axis Axi integrally with the shaft 84. The pinion 86 may be attached to the shaft 84, or may be formed integrally with the shaft 84.

[0044] The large gear 87 has a larger outer diameter and a larger pitch circle diameter than the pinion 86. Furthermore, the number of teeth of the large gear 87 is greater than the number of teeth of the pinion 86. The large gear 87 is spaced inwardly Di from the pinion 86. However, the large gear 87 may also be spaced outwardly Do from the pinion 86.

[0045] The large gear 87 meshes with the pinion gear 85. Therefore, the pinion gear 85 and the large gear 87 can transmit rotation to each other. The large gear 87 has a larger outer diameter and a larger pitch circle diameter than the pinion gear 85. In other words, the large gear 87 has a different outer diameter from the pinion gear 85. Furthermore, the number of teeth of the large gear 87 is greater than the number of teeth of the pinion gear 85. Note that the second gear may have a smaller outer diameter and a smaller number of teeth than the first gear.

[0046] The large gear 88 is provided on the shaft 83. Therefore, the large gear 88 and the rotating member 51 of the rotary-to-linear motion conversion mechanism 23 can rotate integrally with the shaft 83 around the central axis Axc. The large gear 88 meshes with the pinion gear 86. Therefore, the pinion gear 86 and the large gear 88 can transmit rotation to each other. The large gear 88 has a larger outer diameter and a larger diameter of a pitch circle than the pinion gear 86. Furthermore, the large gear 88 has a larger number of teeth than the pinion gear 86.

[0047] The ratchet gear 91 is provided on the shaft 82. Therefore, the electric motor 61 rotates the ratchet gear 91 and the pinion 85 together around the central axis Axm. The ratchet gear 91 is spaced apart from the pinion 85 in the outward direction Do. The outward direction Do is a direction along the central axis Axm. Therefore, the outward direction Do is an example of an axial direction.

[0048] The ratchet gear 91 is disposed between the pinion 85 and the motor body 71 of the electric motor 61. The ratchet gear 91 is disposed, for example, in approximately the same position in the axial direction as the pinion 86 and the gear 88. However, the position of the ratchet gear 91 is not limited to this example.

[0049] The ratchet gear 91 of this embodiment is made of metal. The ratchet gear 91 is formed in a disk shape that is approximately perpendicular to the central axis Axm. The ratchet gear 91 has two surfaces 111 and 112, an outer surface 113, and a plurality of teeth 114. Note that the rotating body is not limited to the ratchet gear 91, nor is it limited to a disk shape.

[0050] The surface 111 is formed to be substantially flat and faces in the inward direction Di. A portion of the surface 111 faces the large gear 87 with a gap therebetween. The surface 112 is located opposite the surface 111. The surface 112 is formed to be substantially flat and faces in the outward direction Do. The surface 112 faces the motor body 71 with a gap therebetween. The outer surface 113 is provided between the two surfaces 111, 112 and faces radially outward.

[0051] Fig. 4 is a plan view schematically showing the ratchet gear 91 and the locking device 92 of the first embodiment. As shown in Fig. 4, a plurality of teeth 114 protrude from the outer surface 113. That is, the outer surface 113 forms the tooth root of the ratchet gear 91. The plurality of teeth 114 are arranged in the circumferential direction. The teeth 114 protrude from the outer surface 113 in a direction inclined obliquely relative to the radial direction. Therefore, each of the plurality of teeth 114 covers a portion of the outer surface 113 (the tooth root).

[0052] 3, the pinion 85 has a smaller outer diameter and a smaller pitch diameter than the ratchet gear 91. The ratchet gear 91 has a smaller outer diameter and a smaller pitch diameter than the large gear 87. Therefore, the ratchet gear 91 is spaced apart from the shaft 84 and the pinion 86 in the radial direction.

[0053] 4, a plurality of holes 115 are provided in the ratchet gear 91. The holes 115, for example, penetrate the ratchet gear 91 in the axial direction. Therefore, the holes 115 open to the two surfaces 111 and 112. In other words, the plurality of holes 115 are provided in the surface 111. Note that the holes 115 may be recesses provided in the surface 111.

[0054] The holes 115 are arranged at intervals from one another around the central axis Axm. For example, the holes 115 are arranged at approximately equal intervals around the central axis Axm. Therefore, the ratchet gear 91 has a plurality of spokes 116. Each of the plurality of spokes 116 is a part of the ratchet gear 91 located between two adjacent ones of the holes 115.

[0055] The locking device 92 has an engagement member 121 and an actuator 122. The engagement member 121 has a plunger 125 and a pawl 126. The plunger 125 is formed in a rod shape extending approximately in the radial direction. The plunger 125 is supported by the actuator 122 so as to be movable parallel to the radial direction. The pawl 126 protrudes from the tip of the plunger 125 in a direction inclined obliquely relative to the radial direction. The direction in which the pawl 126 protrudes from the plunger 125 and the direction in which the teeth 114 protrude from the outer surface 113 are approximately opposite to each other.

[0056] The engagement member 121 is movable between a first position P1 and a second position P2. At the first position P1, the pawl 126 fits between two adjacent teeth 114. Therefore, at the first position P1, the engagement member 121 engages with the ratchet gear 91, thereby restricting the ratchet gear 91 from rotating around the central axis Axm. At the second position P2, the engagement member 121 is spaced apart from the ratchet gear 91.

[0057] 3 is, for example, an inductive proximity sensor. However, the rotation angle sensor 93 is not limited to this example and may be, for example, a resolver, a Hall element, an encoder, a photoelectric sensor, an ultrasonic sensor, a capacitance proximity sensor, a magnetic proximity sensor, or another non-contact sensor.

[0058] The rotation angle sensor 93 includes a substrate 131 and a coil 132. The coil 132 is an example of a detection unit. The detection unit may be another element such as a light source, a light receiving element, or an ultrasonic element.

[0059] The substrate 131 is, for example, a printed circuit board. The coil 132 is, for example, a coil-shaped pattern provided on the substrate 131, or an element mounted on the substrate 131. Note that the rotation angle sensor 93 is not limited to this example. For example, the coil 132 may be spaced apart from the substrate 131, or the substrate 131 may be omitted.

[0060] The distance between the rotation angle sensor 93 and the central axis Axm is longer than half the outer diameter of the pinion 85 (the radius of the pinion 85). That is, the coil 132 of the rotation angle sensor 93 is radially spaced from the central axis Axm by a distance longer than half the outer diameter of the pinion 85.

[0061] Furthermore, the coil 132 of the rotation angle sensor 93 is spaced inwardly Di from the ratchet gear 91. That is, both the pinion 85 and the coil 132 are spaced inwardly Di from the ratchet gear 91.

[0062] The rotation angle sensor 93 is disposed, for example, at approximately the same position in the axial direction as the pinion 85 and the gear wheel 87. The rotation angle sensor 93 is also spaced apart in the circumferential direction from the gear wheel 87. That is, the rotation angle sensor 93 is disposed in a dead space in the accommodation chamber 101 that is generated by the meshing of the pinion 85 and the gear wheel 87.

[0063] The position of the rotation angle sensor 93 is not limited to the above example. For example, the rotation angle sensor 93 may be located farther in the inward direction Di from the ratchet gear 91 than the pinion gear 85. That is, the pinion gear 85 may be located between the ratchet gear 91 and the coil 132 in the axial direction. The rotation angle sensor 93 may also be located outside the accommodation chamber 101.

[0064] A portion of the surface 111 of the ratchet gear 91 faces, with a gap therebetween, a coil 132 of the rotation angle sensor 93. When a high-frequency signal is supplied to the coil 132 of the rotation angle sensor 93, an electromagnetic field is generated around the coil 132. The coil 132 generates an electromagnetic field toward the surface 111.

[0065] A plurality of holes 115 are formed at equal intervals on the surface 111. Therefore, when the ratchet gear 91 rotates around the central axis Axm, the inductance changes due to the principle of mutual induction. The rotation angle sensor 93 detects the rotation angle of the ratchet gear 91 based on the change in inductance. In other words, the rotation angle sensor 93 detects the rotation angle of the ratchet gear 91 by the coil 132.

[0066] The coil 132 may generate an electromagnetic field toward the teeth 114. In this case as well, when the ratchet gear 91 rotates, the rotation angle sensor 93 can detect the rotation angle of the ratchet gear 91 based on a change in inductance due to the principle of mutual induction.

[0067] 4, the length of the coil 132 in the circumferential direction is approximately equal to the sum of the length of one hole 115 and the length of one spoke 116. However, the length of the coil 132 is not limited to this example. For example, the length of the coil 132 in the circumferential direction may be approximately equal to the sum of the lengths of n holes 115 and the lengths of n spokes 116, where n is a natural number.

[0068] 3 is made of, for example, synthetic resin. The cover 94 covers the rotation angle sensor 93 and protects the rotation angle sensor 93 from, for example, lubricant. The electromagnetic field generated by the coil 132 passes through the cover 94. Note that the cover 94 may be omitted.

[0069] The ECU 25 has, for example, a circuit board 141 and a cover 142. The circuit board 141 has, for example, a printed circuit board and a plurality of components mounted on the printed circuit board. The circuit board 141 is, for example, spaced apart from the rotation transmission mechanism 62 in the inward direction Di. The circuit board 141 is electrically connected to the electric motor 61, the rotation angle sensor 93, and the actuator 122. The cover 142 is attached to the case 81 of the rotation transmission mechanism 62 and covers the circuit board 141. The ECU 25 may be provided in another position.

[0070] The coil 132 may be provided on the circuit board 141 of the ECU 25. In this case, the electromagnetic field generated by the coil 132 passes through the case 81. The ratchet gear 91 is farther from the circuit board 141 than the pinion gear 85 and the gear wheel 87. However, the rotation angle sensor 93 can detect the rotation angle of the ratchet gear 91 based on the electromagnetic field passing through the space beside the pinion gear 85 and the gear wheel 87.

[0071] The ECU 25 outputs drive power based on the control signal to drive the drive device 24. The electric motor 61 is driven by the drive power supplied from the ECU 25, and rotates the motor shaft 72, the shaft 82, the pinion 85, and the ratchet gear 91 in one direction (forward direction) around the central axis Axm.

[0072] When rotation is transmitted from the pinion 85 to the large gear 87, the shaft 84, the pinion 86, and the large gear 87 rotate around the central axis Axi. When rotation is transmitted from the pinion 86 to the large gear 88, the rotating member 51, the shaft 83, and the large gear 88 rotate around the central axis Axc. In other words, the rotation transmission mechanism 62 decelerates the rotation of the motor shaft 72 and transmits it to the rotating member 51.

[0073] As the rotating member 51 rotates in one direction around the central axis Axc, the linearly moving member 52 moves linearly in the outward direction Do. The piston 33 is pushed in the outward direction Do by the linearly moving member 52 moving in the outward direction Do, and presses the brake pad 22 against the rotor body 11a. In this way, the braking device 10 brakes the wheel of the vehicle 1 which rotates integrally with the disc rotor 11.

[0074] When the electric motor 61 rotates the motor shaft 72 in the opposite direction (reverse direction) about the central axis Axm, the rotating member 51 also rotates in the opposite direction about the central axis Axc. This causes the linearly moving member 52 to move inward in the inward direction Di, and the piston 33 also moves in the inward direction Di. The pressing force of the piston 33 on the brake pad 22 decreases, and the piston 33 releases the brake pad 22 from pressing against the rotor body 11a. This causes the braking device 10 to release the braking.

[0075] For example, in a braking state, based on the driver's operation, the ECU 25 drives the actuator 122. As a result, the actuator 122 moves the engagement member 121 from the second position P2 to the first position P1.

[0076] When the engaging member 121 moves to the first position P1, it engages with the ratchet gear 91. As a result, the engaging member 121 restricts the motor shaft 72, the shaft 82, the pinion 85, and the ratchet gear 91 from rotating in the reverse direction. Therefore, even if the electric motor 61 is de-energized, the brake device 10 restricts the linearly moving member 52 from moving backward in the inward direction Di, and can maintain the braked state.

[0077] The pawl 126 fits into the gap between the two teeth 114. The teeth 114 and the pawl 126 are inclined relative to the radial direction. Therefore, even if the actuator 122 is de-energized, the engaging member 121 can be prevented from returning from the second position P2 to the first position P1. Note that, for example, by slightly rotating the ratchet gear 91 in the forward direction, the pawl 126 can escape from the gap between the two teeth 114.

[0078] When the motor shaft 72, the shaft 82, the pinion 85, and the ratchet gear 91 rotate around the central axis Axm, the rotation angle sensor 93 detects the rotation angle of the ratchet gear 91. The ECU 25 can obtain the rotation angle of the motor shaft 72 of the electric motor 61 based on the detection signal of the rotation angle sensor 93. The ECU 25 drives the electric motor 61 based on the rotation angle of the motor shaft 72 and controls braking or braking release.

[0079] In the brake device 10 according to the first embodiment described above, the pinion gear 85 is spaced apart from the ratchet gear 91 in the inward direction Di along the central axis Axm, rotates integrally with the ratchet gear 91 about the central axis Axm, and has a smaller outer diameter than the ratchet gear 91. The gear 87 is rotatable about the central axis Axi parallel to the central axis Axm, meshes with the pinion gear 85, and has a different outer diameter than the pinion gear 85. The coil 132 of the rotation angle sensor 93 is spaced apart from the central axis Axm in the radial direction perpendicular to the central axis Axm by more than half the outer diameter of the pinion gear 85, and is spaced apart from the ratchet gear 91 in the inward direction Di. Therefore, for example, the coil 132 can be disposed in a dead space formed next to the pinion gear 85 due to the meshing of the pinion gear 85 and the gear 87. Therefore, the EMB 12 can be prevented from becoming large in the axial direction along the central axis Axm or the central axis Axi. The coil 132 may be axially spaced farther from the ratchet gear 91 than the pinion gear 85. For example, the coil 132 may be provided on the circuit board 141 of the ECU 25. That is, the EMB 12 can prevent restrictions on the placement of the coil 132. As described above, the EMB 12 allows the rotation angle sensor 93 to be efficiently placed. Furthermore, the rotation angle sensor 93 detects the rotation angle of the ratchet gear 91, which has a larger outer diameter than the pinion gear 85. Therefore, the rotation angle sensor 93 can detect the rotation angles of the pinion gear 85 and the ratchet gear 91, which rotate integrally, with higher accuracy than when detecting the rotation angle of the pinion gear 85. Furthermore, because the outer diameter of the large gear 87 is larger than that of the pinion gear 85, the rotational speed (angular velocity) of the pinion gear 85 is faster than the rotational speed (angular velocity) of the large gear 87. In this case, the rotation angle sensor 93 can detect the rotation angles of the pinion 85 and the ratchet gear 91, which rotate integrally, with higher accuracy than when detecting the rotation angle of the large gear 87.

[0080] The electric motor 61 is configured to rotate the ratchet gear 91 and the pinion gear 85 integrally about the central axis Axm. The engagement member 121 is movable between a first position P1 and a second position P2. At the first position P1, the engagement member 121 engages with the ratchet gear 91, thereby restricting the ratchet gear 91 from rotating about the central axis Axm. At the second position P2, the engagement member 121 is spaced apart from the ratchet gear 91. Therefore, for example, when the electric motor 61 is not energized, the engagement member 121 can prevent the ratchet gear 91 and the pinion gear 85 from rotating due to an external force. Compared to when the engagement member 121 engages with the pinion gear 85, the force received from the ratchet gear 91 can be reduced, and the ratchet gear 91 and the pinion gear 85 can be held at a desired position (angle) with greater precision. That is, since the EMB 12 detects the rotation angle of the ratchet gear 91 that limits the rotation of the pinion 85 using the rotation angle sensor 93, there is no need to add another rotating body for the rotation angle sensor 93 to detect the rotation angle.

[0081] The ratchet gear 91 is made of metal and rotates around a central axis Axm. Therefore, as an example, when the ratchet gear 91 rotates, the positions of the teeth 114 of the ratchet gear 91, the holes 115 formed in the surface 111 of the ratchet gear 91, and the spokes 116 change. Therefore, the rotation angle sensor 93 can detect the rotation angle of the ratchet gear 91 based on, for example, changes in induced current, capacitance, or magnetic field caused by the rotation of the ratchet gear 91.

[0082] The ratchet gear 91 has a surface 111 facing the coil 132. A plurality of holes 115 are provided in the surface 111 and spaced apart from one another around the central axis Axm. Therefore, as an example, the rotation angle sensor 93 can detect the rotation angle of the ratchet gear 91 based on, for example, a change in induced current, capacitance, or magnetic field caused by the rotation of the ratchet gear 91.

[0083] (Second embodiment) The second embodiment will be described below with reference to Fig. 5. In the following description of the embodiment, components having the same functions as components already described are given the same reference numerals as the components already described, and further description may be omitted. Furthermore, multiple components given the same reference numerals do not necessarily have all the same functions and properties, and may have different functions and properties according to each embodiment.

[0084] Fig. 5 is a plan view schematically showing a ratchet gear 200 and a locking device 92 according to the second embodiment. As shown in Fig. 5, the rotation transmission mechanism 62 of the second embodiment has a ratchet gear 200 instead of the ratchet gear 91. The ratchet gear 200 is substantially the same as the ratchet gear 91, except for the points described below.

[0085] The ratchet gear 200 is manufactured by, for example, insert molding, and has a resin part 201 and a metal part 202. The resin part 201 is an example of a first part. However, the ratchet gear 200 may be manufactured by other methods.

[0086] The resin portion 201 is made of synthetic resin. The resin portion 201 has two surfaces 111 and 112, an outer surface 113, and a plurality of teeth 114. In the second embodiment, the ratchet gear 200 may be provided with a plurality of holes 115, or the holes 115 may be omitted. The holes 115 can reduce the weight of the ratchet gear 200.

[0087] The metal portion 202 is made of a metal such as iron. The metal portion 202 has, for example, an inner ring 205, an outer ring 206, and a plurality of spokes 207. Note that the metal portion 202 is not limited to this example. The spokes 207 are an example of a second portion.

[0088] The inner ring 205 and the outer ring 206 are formed in a substantially circular ring shape extending in the circumferential direction. The outer ring 206 is spaced radially outward from the inner ring 205 and surrounds the inner ring 205. The outer diameter of the outer ring 206 is smaller than the diameter of the outer surface 113 of the resin portion 201.

[0089] The multiple spokes 207 extend substantially radially between the inner ring 205 and the outer ring 206. That is, the multiple spokes 207 are arranged at intervals from one another around the central axis Axm. For example, the multiple spokes 207 are arranged at substantially equal intervals around the central axis Axm. Note that the spokes 207 may extend in a direction inclined obliquely relative to the radial direction.

[0090] The metal portion 202 is insert-molded together with the resin portion 201, and thereby bonded to the resin portion 201. For example, the metal portion 202 is partially embedded in the resin portion 201 and partially exposed from the surface 111.

[0091] The entire metal portion 202 may be embedded in the resin portion 201. Alternatively, the resin portion 201 may be an annular ring gear extending in the circumferential direction, and the spokes 207 may extend between the annular resin portion 201 and the shaft 82. Alternatively, the inner ring 205 and the outer ring 206 may be omitted.

[0092] In the braking device 10 of the second embodiment described above, the ratchet gear 200 has a resin portion 201 and a plurality of spokes 207. The resin portion 201 is made of synthetic resin. The plurality of spokes 207 are connected to the resin portion 201 and are arranged at intervals around the central axis Axm. Therefore, as an example, the rotation angle sensor 93 can detect the rotation angle of the ratchet gear 200 based on, for example, changes in induced current, capacitance, or magnetic field caused by the rotation of the ratchet gear 200.

[0093]

[0013] The rotation transmission device according to at least one embodiment described above includes, for example, a rotor configured to rotate about a first rotation axis, a first gear spaced from the rotor in an axial direction along the first rotation axis and configured to rotate integrally with the rotor about the first rotation axis and having an outer diameter smaller than that of the rotor, a second gear rotatable about a second rotation axis parallel to the first rotation axis and meshing with the first gear and having an outer diameter different from that of the first gear, and a non-contact sensor having a detector spaced from the first rotation axis in a direction perpendicular to the first rotation axis by more than half the outer diameter of the first gear and spaced from the rotor in the axial direction, the non-contact sensor configured to detect the rotation angle of the rotor using the detector. Thus, for example, the detector can be disposed in a dead space beside the first gear due to the meshing of the first gear and the second gear. Therefore, the rotation transmission device can be prevented from becoming larger in size in the direction along the first rotation axis or the second rotation axis. The detection unit may be located axially farther from the rotating body than the first gear. That is, the rotation transmission device can be prevented from restricting the placement of the detection unit. As described above, the rotation transmission device can efficiently place the non-contact sensor. Furthermore, the non-contact sensor detects the rotation angle of a rotating body having a larger outer diameter than the first gear. Therefore, the non-contact sensor can detect the rotation angle of the first gear and the rotating body, which rotate integrally, with higher accuracy than when detecting the rotation angle of the first gear. Furthermore, when the outer diameter of the second gear is larger than the outer diameter of the first gear, the rotation speed of the first gear is faster than the rotation speed of the second gear. In this case, the non-contact sensor can detect the rotation angle of the first gear and the rotating body, which rotate integrally, with higher accuracy than when detecting the rotation angle of the second gear.

[0094] As an example, the rotation transmission device further includes a motor configured to rotate the rotating body and the first gear integrally about the first rotation axis, and an engagement member movable between a first position that engages with the rotating body to restrict rotation of the rotating body about the first rotation axis and a second position that is spaced apart from the rotating body. Thus, as an example, the engagement member can prevent the rotating body and the first gear from rotating due to an external force, for example, when the motor is not energized. Compared to when the engagement member engages with the first gear, the engagement member can reduce the force received from the rotating body and more accurately hold the rotating body and the first gear at a desired position (angle). In other words, the rotation transmission device detects the rotation angle of the rotating body that restricts rotation of the first gear using a non-contact sensor, eliminating the need for an additional component for detecting the rotation angle using a non-contact sensor.

[0095] In the rotation transmission device, for example, the rotating body includes a third gear made of metal and configured to rotate around the first rotation axis. Therefore, as the third gear rotates, for example, the positions of the teeth of the third gear and holes formed in the surface of the third gear change. Therefore, the non-contact sensor can detect the rotation angle of the rotating body based on, for example, changes in induced current, capacitance, or magnetic field caused by the rotation of the third gear.

[0096] In the rotation transmission device, for example, the third gear has a surface facing the detection unit, and a plurality of holes are provided on the surface, spaced apart from one another around the first rotation axis. Therefore, for example, the non-contact sensor can detect the rotation angle of the rotating body based on, for example, a change in induced current, capacitance, or magnetic field caused by the rotation of the third gear.

[0097] In the rotation transmission device, as one example, the rotating body has a first portion made of synthetic resin and a plurality of second portions made of metal, connected to the first portion, and arranged at intervals around the first rotation axis. Therefore, as one example, the non-contact sensor can detect the rotation angle of the rotating body based on, for example, changes in induced current, capacitance, or magnetic field caused by the rotation of the rotating body.

[0098] While the embodiments of the present invention have been described above, the above-described embodiments and modifications are merely examples and are not intended to limit the scope of the invention. The above-described embodiments and modifications can be implemented in various other forms, and various omissions, substitutions, combinations, and modifications can be made without departing from the spirit of the invention. Furthermore, the configurations and shapes of each embodiment and each modification can be partially interchanged. [Explanation of symbols]

[0099] 12...EMB (rotation transmission device), 61...electric motor (motor), 85...pinion gear (first gear), 87...gear (second gear), 91, 200...ratchet gear (rotating body, third gear), 93...rotation angle sensor (non-contact sensor), 111...surface, 115...hole, 121...engaging member, 132...coil (detection part), 201...resin part (first part), 207...spoke (second part), Axm...central axis (first rotation axis), Axi...central axis (second rotation axis), Di...inner direction (axial direction), P1...first position, P2...second position.

Claims

1. a rotor configured to rotate about a first axis of rotation; a first gear configured to be spaced apart from the rotating body in an axial direction along the first rotation axis, to rotate integrally with the rotating body around the first rotation axis, and having an outer diameter smaller than that of the rotating body; a second gear that is rotatable around a second rotation axis parallel to the first rotation axis, that meshes with the first gear, and that has an outer diameter different from that of the first gear; a non-contact sensor having a detection unit that is spaced apart from the first rotation axis in a direction perpendicular to the first rotation axis by a distance greater than half the outer diameter of the first gear and that is spaced apart from the rotating body in the axial direction, and that is configured to detect a rotation angle of the rotating body by the detection unit; A rotation transmission device comprising:

2. a motor configured to rotate the rotating body and the first gear integrally around the first rotation axis; an engaging member movable between a first position where the engaging member engages with the rotating body to restrict rotation of the rotating body about the first rotation axis and a second position where the engaging member is spaced from the rotating body; The rotation transmission device of claim 1 further comprising:

3. the rotating body has a third gear made of metal and configured to rotate around the first rotation axis; The rotation transmission device according to claim 1 or 2.

4. the third gear has a surface facing the detection unit, and a plurality of holes are formed in the surface, the holes being spaced apart from one another around the first rotation axis; The rotation transmission device according to claim 3.

5. The rotating body has a first portion made of synthetic resin and a plurality of second portions made of metal, connected to the first portion, and arranged at intervals around the first rotation axis. The rotation transmission device according to claim 1 or 2.

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