Clutch device

Abstract

The clutch device (1) includes an input member (2), an output member (nut (8)), a pressed surface (45), a pair of engaging elements (5), a first bearing mechanism (6) that rotatably supports the output member, and a ball screw (3). The ball screw (3) has a rotating member (nut (8)) that rotates integrally with the output member, and a linear motion member (screw shaft (9)) that threadably engages with the rotating member. The outer ring of the first bearing mechanism (6) is an integrated outer ring (61) in which a first outer ring raceway groove (63) in which a first rolling element (60) of the first bearing mechanism (6) rolls and the pressed surface (45) are integrally formed.

Description

[Technical Field]

[0001] The present invention relates to a clutch device. This application claims priority based on Japanese Patent Application No. 2024-098127, filed June 18, 2024, the contents of which are incorporated herein by reference. [Background technology]

[0002] Conventionally, a reverse input blocking clutch configuration has been known that includes an input member connected to an input mechanism such as a drive source and an output member connected to an output mechanism such as a reducer, and that allows transmission of rotational force from the input member to the output member while blocking reverse input of rotational force from the output member to the input member. Furthermore, a clutch device configuration has also been known in which the reverse input blocking clutch is combined with a rotary-to-linear motion conversion mechanism (e.g., a ball screw). For these clutch devices, various techniques have been proposed to improve performance when the reverse input blocking clutch and the rotary-to-linear motion mechanism are integrated into a single unit.

[0003] For example, Patent Document 1 discloses the configuration of an actuator including a ball screw having a nut that rotates about its axis and a screw shaft that moves linearly in the axial direction, and a reverse input cutoff clutch in which an output member is connected to the nut. Rotational torque input to the input member is transmitted to the output member via a pair of engaging elements, causing the nut to rotate. The rotation of the nut is converted into linear motion of the screw shaft and output to the output mechanism. Meanwhile, when an axial load is input in reverse to the screw shaft from the output mechanism, the axial load is converted into rotational torque of the nut, and this rotational torque is input in reverse from the nut to the output member of the reverse input cutoff clutch. The rotational torque input in reverse to the output member is not transmitted to the input member by the reverse input cutoff clutch. Therefore, according to the technology described in Patent Document 1, when a reverse input (axial load) is input to the ball screw, the reverse input can be cut off by the reverse input cutoff clutch. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2019 / 216280 Summary of the Invention [Problem to be solved by the invention]

[0005] In the technology described in Patent Document 1, the bearing mechanism that rotatably supports the rotating member (nut) of the ball screw and the pressed member that has the pressed surface of the reverse input cutoff clutch are formed as separate parts (see also FIG. 11). This may make it difficult to ensure concentricity between the nut of the ball screw and the pressed surface.

[0006] Here, for example, if the output member (ball screw nut) and the pressed member (pressed surface) are not coaxial, the size of the gap between each engaging element and the pressed member will differ. As a result, when a rotational force is input in reverse to the output member, only one engaging element will come into contact with the pressed member first, and the pressing force will be weak until the other engaging element comes into contact with the output member, preventing the locking function from working properly. As a result, there is a risk of a time loss until the lock is reached. Furthermore, because only one engaging element comes into contact with the output member, bending of the output member may occur, resulting in a decrease in performance.

[0007] Furthermore, in the prior art described in Patent Document 1, the ball screw nut and the reverse input cutoff clutch are attached to the housing via multiple intermediate parts, which increases the number of parts and may complicate assembly work, and may also increase the size of the device. Therefore, in the prior art, there was room for improvement in terms of improving the coaxiality between parts and suppressing an increase in the number of parts in a clutch device that combines a ball screw and a reverse input cutoff clutch.

[0008] Therefore, an object of the present invention is to provide a clutch device that combines a ball screw and a reverse input cut-off clutch, which improves the coaxiality between parts compared to conventional technology and suppresses an increase in the number of parts. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention proposes the following means. A clutch device according to a first aspect of the present invention comprises: an input member having an input shaft; an output member arranged coaxially with the input shaft; a pair of engagers provided radially outward from the input member and the output member, the engagers having a pressed surface facing inward in the radial direction, a pressing surface opposing the pressed surface, an input-side engaged portion engageable with the input member, and an output-side engaged portion engageable with the output member, the engagers being movable relative to each other along a first radial direction; a bearing mechanism having rolling elements and rotatably supporting the output member; a rotating member provided to rotate integrally with the output member; and a linear member screwed into engagement with the rotating member; When this occurs, the pair of engaging elements move toward each other radially inward in the first radial direction based on the engagement between the input member and the input-side engaged portion, and transmit the rotational torque to the output member based on the engagement between the output member and the output-side engaged portion. When the rotational torque is reversely input to the output member, the pair of engaging elements move away from each other radially outward in the first radial direction based on the engagement between the output member and the output-side engaged portion, causing frictional engagement between the pressed surface and the pressing surface, and the outer ring of the bearing mechanism becomes an integrated outer ring in which the pressed surface and an outer ring raceway surface on which the rolling elements of the bearing mechanism roll are integrally provided. The output member and the rotating member are integrated, and the rotating member is integrally formed with an inner ring raceway surface of the bearing mechanism, and the inner ring raceway surface of the bearing mechanism is provided at a position that overlaps with an inner peripheral rolling groove of the rotating member in the axial direction. . [Effects of the Invention]

[0010] According to the reverse input cutoff clutch of the present invention, in a clutch device that combines a ball screw and a reverse input cutoff clutch, it is possible to provide a clutch device that improves the concentricity between parts and suppresses an increase in the number of parts compared to conventional technology. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view of a clutch device according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] 1 is a schematic configuration diagram of a clutch device according to a first embodiment. [Figure 4] FIG. 6 is a schematic configuration diagram of a clutch device according to a second embodiment. [Figure 5] FIG. 10 is a schematic configuration diagram of a clutch device according to a third embodiment. [Figure 6] FIG. 10 is a schematic configuration diagram of a clutch device according to a fourth embodiment. [Figure 7] FIG. 10 is a schematic configuration diagram of a clutch device according to a fifth embodiment. [Figure 8] FIG. 10 is a schematic configuration diagram of a clutch device according to a sixth embodiment. [Figure 9] FIG. 13 is a schematic configuration diagram of a clutch device according to a seventh embodiment. [Figure 10] FIG. 13 is a schematic configuration diagram of a clutch device according to an eighth embodiment. [Figure 11] FIG. 1 is a schematic diagram of a clutch device according to a conventional technique. [Figure 12] FIG. 1 is a schematic diagram of a clutch device according to a conventional technique. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, the axial direction, radial direction, and circumferential direction refer to the axial direction, radial direction, and circumferential direction of the center axis C of the ball screw 3, unless otherwise specified.

[0013] (First embodiment) FIG. 1 is a cross-sectional view of a clutch device 1 according to a first embodiment. FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1. FIG. 3 is a schematic diagram of the clutch device 1 according to the first embodiment. Note that FIG. 3 is a schematic diagram for easily explaining the characteristic configuration of the clutch device 1 according to this embodiment, and is a simplified version of FIG. 1. Also, some components (such as the housing 4) are not shown in FIG. 3.

[0014] As shown in Fig. 1, the clutch device 1 of this embodiment is used in a rear wheel steering device, a vehicle height control device, etc. As shown in Figs. 1 and 3, the clutch device 1 includes a ball screw 3 and a reverse input cutoff clutch 11 having a locking function. In this embodiment, the reverse input cutoff clutch 11 is provided on the input mechanism side in the direction of transmission of rotational force, and the ball screw 3 is provided on the output mechanism side in the direction of transmission of rotational force. In the following description, the side on which the reverse input cutoff clutch 11 is provided relative to the ball screw 3 in the axial direction may be referred to as the first axial side, and the opposite side may be referred to as the second axial side.

[0015] The ball screw 3 is a device that converts rotational motion into linear motion. The ball screw 3 of this embodiment has a screw shaft 9 as a linear motion member, a nut 8 as a rotating member, and a plurality of balls 10. The nut 8 is rotatable about a central axis C but does not move in a direction along the central axis C. The screw shaft 9, which is connected to a driven member (not shown), does not rotate about the central axis C but is movable in a direction along the central axis C. When the nut 8 rotates, the screw shaft 9 moves in a direction along the central axis C.

[0016] The screw shaft 9 is formed in a cylindrical shape centered on a central axis C. The screw shaft 9 is disposed inside a nut 8, which will be described later. As shown in FIG. 1 , a spiral outer circumferential rolling groove 18 is formed on the outer periphery of the screw shaft 9. The cross-sectional shape of the outer circumferential rolling groove 18 is, for example, a Gothic arch including two arcs. The outer circumferential rolling groove 18 is formed over almost the entire screw shaft 9 in the axial direction. A driven member (not shown) is connected to the end of the screw shaft 9 on the second axial side. Note that driven members may be connected to both ends of the screw shaft 9 on the first and second axial sides, respectively.

[0017] The nut 8 (output member in the claims) is formed in a cylindrical shape centered on the central axis C. A screw shaft 9 is inserted inside the nut 8. The nut 8 has a nut body 12 and an insertion portion 13. The nut body 12 is formed in a cylindrical shape centered on the central axis C. The nut body 12 is screwed onto the screw shaft 9 via balls 10. An inner circumferential rolling groove 17, which is a spiral groove, is formed on the inner circumferential surface of the nut body 12. The cross-sectional shape of the inner circumferential rolling groove 17 is a Gothic arch including two circular arcs. The inner circumferential rolling groove 17 is formed over almost the entire nut body 12 in the axial direction.

[0018] The insertion portion 13 is provided on a first axial side of the nut body 12. The insertion portion 13 is connected to the first axial end of the nut body 12 and extends from the first axial end of the nut body 12 toward the first axial side. In this embodiment, the insertion portion 13 is integrally formed with the nut body 12. The inner diameter of the insertion portion 13 is formed to be equal to the inner diameter of the nut body 12. The outer diameter of the insertion portion 13 is formed to be smaller than the outer diameter of the nut body 12. As shown in Figures 1 and 2, the insertion portion 13 is a portion of the nut 8 that is arranged between a pair of engaging elements 5 of the reverse input cutoff clutch 11, which will be described in detail later. The detailed shape of the insertion portion 13 will be described later.

[0019] As shown in Figures 1 and 3, a plurality of balls 10 are arranged between the nut 8 and the screw shaft 9. The balls 10 are, for example, metal spheres. When the nut 8 and the screw shaft 9 are combined, an inner peripheral rolling groove 17 formed in the nut 8 and an outer peripheral rolling groove 18 formed in the screw shaft 9 form a spiral rolling path. The balls 10 move in this spiral rolling path.

[0020] A circulation top (not shown) is disposed on the inner periphery of the nut 8. A circulation path (not shown) is formed in the circulation top, and this circulation path connects one end and the other end of a spiral rolling path to form an infinite circulation circuit. A plurality of balls 10 are filled in this infinite circulation circuit, so that the balls 10 circulate endlessly within the infinite circulation circuit. In other words, the ball screw 3 of this embodiment is a so-called ball circulation type ball screw 3. Note that a plurality of circulation tops may be provided. The circulation top may also be provided on the screw shaft 9. The type of circulation path is not limited to the above-described embodiment. The circulation path may be, for example, an S-groove type, an end deflector type, a tube type, or the like, in which the circulation path is formed in the nut 8.

[0021] The reverse input blocking clutch 11 is provided at a position in the axial direction corresponding to the insertion portion 13 of the ball screw 3. The reverse input blocking clutch 11 has a locking function (reverse input blocking function) that blocks rotational force that is reversely input to the screw shaft 9 from the output mechanism side. This realizes the function of suppressing unintended operation due to external force when the clutch device 1 is used as a rear wheel steering device or the like.

[0022] 1 to 3, the reverse input cutoff clutch 11 includes an input member 2, the nut 8 described above as an output member, a housing 4, a pair of engaging elements 5, and a plurality of bearing mechanisms 6 and 7. The reverse input cutoff clutch 11 transmits the rotational force input to the input member 2 to the nut 8 (output member). On the other hand, the reverse input cutoff clutch 11 has a reverse input cutoff function of cutting off the rotational force that is reversely input to the nut 8 (output member) via the screw shaft 9, so that it is not transmitted to the input member 2, or of transmitting only a portion of the rotational force to the input member 2 and cutting off the remainder.

[0023] The input member 2 is connected to an input mechanism such as an electric motor (not shown). A rotational force from the input mechanism is input to the input member 2. The input member 2 has an input shaft 21 and a pair of arms 23. The input shaft 21 is provided on a first side in the axial direction. The input shaft 21 is formed in a columnar (or cylindrical) shape centered on a central axis C.

[0024] The pair of arms 23 extend from the input shaft 21 toward the second side in the axial direction. The arms 23 are integrally formed with the input shaft 21. A pair of arms 23 are provided at both ends of the input shaft 21 in the first radial direction D1. As shown in FIG. 2 , the arms 23 are formed in an elliptical shape when viewed from the axial direction. The surface of the arms 23 facing inward in the first radial direction D1 is an input-side engaging portion 25 formed in a flat shape. The shape of the arms 23 is not limited to the above-described shape. The shape of the arms 23 may be, for example, a semicircular shape having an arc-shaped curved portion and a flat portion, a polygonal shape, a trapezoidal shape, an elliptical shape, or the like.

[0025] A plurality of arm portions 23 are provided in accordance with the number of engaging elements 5 described below. In this embodiment, a pair of arm portions 23 is provided in accordance with the number of engaging elements 5. The number of arm portions 23 is not limited to two, and may be one, or three or more, in accordance with the number of engaging elements 5.

[0026] As shown in FIGS. 1 to 3 , in this embodiment, the output member of the reverse input cutoff clutch 11 is the same component as the nut 8 of the ball screw 3. The nut 8 is arranged coaxially with the input shaft 21 of the reverse input cutoff clutch 11. The nut 8 is provided on the second axial side of the input member 2. The insertion portion 13 of the nut 8 is formed in a cylindrical shape centered on the central axis C. More specifically, as shown in FIG. 2 , the insertion portion 13 is arranged radially inward of the pair of arm portions 23 of the input member 2. The screw shaft 9 is accommodated inside the insertion portion 13. When viewed from the axial direction, the outer periphery of the insertion portion 13 has planar output-side engaging portions 14 parallel to the second radial direction D2 at two positions corresponding to both ends in the first radial direction D1. Each output-side engaging portion 14 faces the output-side engaged portion 56 of the pair of engaging elements 5. The output-side engaging portions 14 are arranged inward of the input-side engaging portions 25 of the input member 2 in the first radial direction D1.

[0027] A plurality of output side engaging portions 14 of the insertion portion 13 are provided in accordance with the number of engaging elements 5 described below. In this embodiment, a pair of output side engaging portions 14 is provided in accordance with the provision of a pair of engaging elements 5. The number of output side engaging portions 14 is not limited to two, and the number of output side engaging portions 14 may be one, or three or more, in accordance with the number of engaging elements 5.

[0028] As shown in FIG. 1, the base end of the insertion portion 13 (for example, the portion located on the second axial side of the pair of engaging elements 5 in FIG. 1) is supported via a bearing 27 so as to be rotatable relative to the portion of the arm portion 23 of the input member 2 that protrudes on the second axial side of the engaging elements 5.

[0029] The housing 4 is disposed radially outward of the ball screw 3 and reverse input cutoff clutch 11 described above. The housing 4 is a housing component with a cylindrical inner periphery. The housing 4 is fixed to another member (not shown) and its rotation is restricted. The housing 4 accommodates a screw shaft 9, a nut 8, an input member 2, a pair of engaging elements 5, and the like inside the housing 4. The housing 4 accommodates the input member 2 and the nut 8 in a rotatable state via a plurality of bearing mechanisms 6 and 7, which will be described in detail later.

[0030] As shown in Fig. 2, the pair of engaging elements 5 are configured in a fan shape centered on the central axis C and are arranged radially inward of the housing 4 (see also Figs. 1 and 3). The pair of engaging elements 5 face each other in the first radial direction D1 and are configured to be movable toward and away from each other in the first radial direction D1. Each of the pair of engaging elements 5 has a pressing surface 51, a bottom surface 52, an input-side engaged portion 55, and an output-side engaged portion 56.

[0031] The pressing surface 51 is a radially outer surface that presses the pressed surface 45 provided on the integrated outer ring 61 (described later), and is an arc-shaped convex surface. Note that a portion of the outer peripheral surface of the engaging element 5 that faces the pressed surface 45 may be used as the pressing surface 51. The pressing surface 51 presses the pressed surface 45 when the reverse input disconnection clutch 11 is in a locked state (a state in which the reverse input from the output mechanism is disconnected). The pressing surface 51 is formed to increase the frictional engagement force between the engaging element 5 and the pressed surface 45 due to a wedge effect. Note that the pressing surface 51 may be directly formed by the entire or part of the outer peripheral surface of the engaging element 5, or may be formed to have a surface texture with a higher friction coefficient than the remaining portion of the engaging element 5. For example, the pressing surface 51 may be formed by a friction material fixed to the engaging element 5 by adhesion or bonding.

[0032] The bottom surface 52 of the engaging element 5 is located inside the pressing surface 51 in the first radial direction D1. The bottom surface 52 forms a linear portion of the fan-shaped engaging element 5. The bottom surface 52 is located at a position corresponding to both end portions of the engaging element 5 in the second radial direction D2. In this embodiment, the bottom surface 52 is formed in a substantially flat surface shape. The bottom surfaces 52 of the pair of engaging elements 5 face each other in the first radial direction D1. The inner diameter dimension of the pressed surface 45 and the outer dimensions of the engaging elements 5 are set so that when the pair of engaging elements 5 are positioned inside the pressed surface 45, a gap exists between the pressed surface 45 and the pressing surface 51, and between the pair of output side engaged portions 56 and the nut 8.

[0033] The input side engaged portion 55 is a hole that penetrates the center of the engaging element 5 in the axial direction when viewed from the axial direction. The input side engaged portion 55 is formed in an elliptical shape extending in the second radial direction D2. The arm portions 23 of the input member 2 are inserted into the input side engaged portions 55, respectively. The input side engaged portions 55 engage with the arm portions 23. The input side engaged portions 55 have a size that allows the arm portions 23 of the input member 2 to be loosely inserted therein. Specifically, the input side engaged portion 55 is formed so that when the arm portions 23 of the input member 2 are inserted inside the input side engaged portion 55, a gap exists between the arm portions 23 and the inner peripheral surface of the input side engaged portion 55.

[0034] The output-side engaged portions 56 are provided on an arc-shaped portion on the inner diameter side of the engaging element 5, which is formed in a fan shape. Specifically, when viewed in the axial direction, the arc-shaped inner peripheral portion of the engaging element 5 has a pair of output-side engaged portions 56 at two positions corresponding to both end portions in the first radial direction D1. The output-side engaged portions 56 are formed in a plane parallel to the second radial direction D2. Each output-side engaged portion 56 faces a pair of output-side engaging portions 14 in the insertion portion 13 of the nut 8. The output-side engaged portions 56 engage with the insertion portion 13 of the nut 8.

[0035] 1 to 3, in the assembled state of the reverse input cutoff clutch 11, the arm portion 23 of the input member 2 is inserted axially into the input-side engaged portions 55 of the pair of engaging elements 5, and the insertion portion 13 of the nut 8 is inserted axially between the output-side engaged portions 56 of the pair of engaging elements 5. In other words, the pair of engaging elements 5 are arranged so that the output-side engaged portions 56 sandwich the insertion portion 13 of the nut 8 from the radially outer side.

[0036] As shown in FIG. 1 , a retaining ring 39 for positioning the pair of engaging elements 5 is provided on a first axial side of the pair of engaging elements 5. Note that end plates (not shown) or the like for positioning each component may be provided separately on both axial sides of the engaging elements 5. In addition to the positioning function, components such as end plates may be provided to prevent contact between the engaging elements 5 and the nut 8 and the input member 2, thereby suppressing wear, for example. Furthermore, a leaf spring (not shown) may be provided radially between the pair of engaging elements 5 and the insertion portion 13 of the nut 8. The leaf spring may be elastically sandwiched between the engaging elements 5 and the insertion portion 13 and bias the engaging elements 5 radially outward, i.e., toward the pressed surface 45.

[0037] 1 and 3, the reverse input disconnecting clutch 11 has, as a plurality of bearing mechanisms, a first bearing mechanism 6 (a bearing mechanism in the claims) and a second bearing mechanism 7. In this embodiment, the first bearing mechanism 6 and the second bearing mechanism 7 are both deep groove ball bearings.

[0038] The first bearing mechanism 6 supports the nut 8 rotatably relative to the housing 4. The first bearing mechanism 6 has a first rolling element 60 (a rolling element in the claims) that rolls around an axis, an integral outer ring 61, a first outer ring raceway groove 63 (an outer ring raceway surface in the claims) and a pressed surface 45 formed on the integral outer ring 61, and a first inner ring raceway groove 64 (an inner ring raceway surface in the claims) formed on the nut body 12. The integral outer ring 61 is formed in a cylindrical shape centered on the central axis C. The outer peripheral surface of the integral outer ring 61 is attached to the housing 4. The integral outer ring 61 is provided axially from the nut body 12 to a position where the pressing surface 51 of the engaging element 5 is located. The inner peripheral surface of the integral outer ring 61 is formed with a first outer ring raceway groove 63 along which the balls serving as the first rolling elements 60 roll, and a pressed surface 45 that comes into contact with the engaging element 5, aligned in the axial direction. In other words, the outer ring of the first bearing mechanism 6 is an integrated outer ring 61 in which both the first outer ring raceway groove 63 and the pressed surface 45 are formed in a single component.

[0039] The one-piece outer ring 61 is formed of a high-hardness steel material such as bearing steel. An example of a high-hardness steel material is a heat-treated high-carbon steel such as SUJ3 or SUJ2. Note that the steel material is not limited to the above-mentioned materials as long as it has high hardness.

[0040] A first inner ring raceway groove 64 that contacts the first rolling element 60 and allows the first rolling element 60 to roll is integrally formed on the outer peripheral surface of the nut body 12. In other words, the first bearing mechanism 6 of this embodiment is formed without having a separate component that constitutes an inner ring. Therefore, the first rolling element 60 rolls in a rolling element raceway that is formed between the first inner ring raceway groove 64 formed in the nut body 12 and the first outer ring raceway groove 63 formed in the one-piece outer ring 61.

[0041] The second bearing mechanism 7 is provided on a first side in the axial direction relative to the first bearing mechanism 6. The second bearing mechanism 7 rotatably supports the input member 2 relative to the housing 4. The second bearing mechanism 7 has a second rolling element 70 that rolls around the input shaft 21, a second outer ring 71, a second outer ring raceway groove 73 formed in the second outer ring 71, and a second inner ring raceway groove 74 formed in the input shaft 21. The outer peripheral surface of the second outer ring 71 is attached to the housing 4. The second outer ring 71 is provided at a position corresponding to the input shaft 21 in the axial direction. The inner peripheral surface of the second outer ring 71 is formed with a second outer ring raceway groove 73 in which balls, which are the second rolling elements 70, roll.

[0042] A second inner ring raceway groove 74 that comes into contact with the second rolling element 70 and allows the second rolling element 70 to roll is formed on the outer peripheral surface of the input shaft 21. In other words, the second bearing mechanism 7 of this embodiment is formed without having a separate component that constitutes an inner ring, similar to the first bearing mechanism 6. Therefore, the second rolling element 70 rolls in a rolling element raceway that is formed between the second inner ring raceway groove 74 formed on the input shaft 21 and the second outer ring raceway groove 73 formed on the second outer ring 71.

[0043] In the present embodiment, the first bearing mechanism 6 and the second bearing mechanism 7 are each described as a deep groove ball bearing, but this is not limiting. As an example, the type of bearing in the first bearing mechanism 6 and the second bearing mechanism 7 may be any of angular contact ball bearings, deep groove ball bearings, four-point contact ball bearings, tapered roller bearings, and cylindrical roller bearings. Furthermore, the first bearing mechanism 6 and the second bearing mechanism 7 may be different types of bearings. In this case, a combination of the above-mentioned types of bearings may be used.

[0044] (Operation of the clutch device) Next, the operation of the clutch device 1 of this embodiment will be described. First, a description will be given of a case where a rotational force is input to the input shaft 21 from the input mechanism. When a rotational force is input to the input shaft 21, the arm portion 23 of the input member 2 rotates around the central axis C inside the input-side engaging portion 25, as shown by the arrow in FIG. 2 . Then, a part of the input-side engaging portion 25 on the rotational direction side presses the inner surface of the input-side engaged portion 55 radially inward, causing the pair of engaging elements 5 to move in a direction away from the pressed surface 45 (inward in the first radial direction D1). In other words, the pair of engaging elements 5 move radially inward toward each other as the rotational force from the input shaft 21 acts on them via the input-side engaged portion 55. As a result, the bottom surfaces 52 of the pair of engaging elements 5 move toward each other, and the pair of output-side engaged portions 56 clamp the output-side engaging portion 14 of the nut 8 (output member) from both radial sides.

[0045] As a result, the nut 8 is rotated so that the output side engaging portion 14 is parallel to the output side engaged portions 56 of the engaging elements 5, and the insertion portion 13 of the nut 8 is engaged with the pair of output side engaged portions 56 without any rattle. Therefore, the rotational force input to the input shaft 21 is transmitted to the nut 8 via the pair of engaging elements 5 and output from the nut 8. The rotational force output from the nut 8 is converted into linear motion by the screw shaft 9 and output to the output mechanism. When a rotational force is input to the input member 2, the reverse input cutoff clutch 11 of this embodiment moves each of the pair of engaging elements 5 in a direction away from the pressed surface 45, regardless of the rotational direction of the input member 2. Then, regardless of the rotational direction of the input member 2, the rotational force input to the input member 2 is transmitted to the nut 8 via the pair of engaging elements 5.

[0046] Next, a case where a rotational force is reversely input from the ball screw 3 to the reverse input cutoff clutch 11 will be described. When a rotational force acts on the nut 8 in response to an axial load acting on the screw shaft 9 from the output mechanism, the insertion portion 13 of the nut 8 attempts to rotate in the rotational direction of the nut 8, inside the pair of output-side engaged portions 56. As a result, the end portion of the output-side engaging portion 14 (either of the corners at both ends in the second radial direction D2 in FIG. 2 ) presses the output-side engaged portion 56 outward in the first radial direction D1, moving each of the pair of engaging elements 5 in a direction approaching the pressed surface 45. In other words, based on the engagement between the nut 8 and the output-side engaged portion 56, the pair of engaging elements 5 move away from each other outward in the first radial direction D1. As a result, the pressing surface 51 of each of the pair of engaging elements 5 is pressed against the pressed surface 45. At this time, the pressing surface 51 and the pressed surface 45 are frictionally engaged over the entire range or at least a portion of the circumferential range of the pressing surface 51.

[0047] As a result, the rotational force reversely input to the nut 8 is blocked and not transmitted to the input member 2, or only a portion of the rotational force reversely input to the nut 8 is transmitted to the input member 2 and the remainder is blocked. To completely block the rotational force reversely input to the nut 8 and prevent it from being transmitted to the input member 2, the pair of engaging elements 5 are tensioned between the insertion portion 13 and the pressed surface 45 so that the pressing surface 51 does not slide (rotate relative to) the pressed surface 45, thereby locking the rotation of the nut 8. On the other hand, to transmit only a portion of the rotational force reversely input to the nut 8 to the input member 2 and block the remainder, the pair of engaging elements 5 are tensioned between the insertion portion 13 and the pressed surface 45 so that the pressing surface 51 slides against the pressed surface 45, thereby semi-locking the nut 8. When a rotational force is further input in the reverse direction to the nut 8 in the half-locked state, the pair of engaging elements 5 rotate about the central axis C while sliding the pressing surface 51 against the pressed surface 45 based on the engagement between the insertion portion 13 of the nut 8 and the output-side engaged portion 56. When the pair of engaging elements 5 rotate, the inner surface of the input-side engaged portion 55 presses the radially inner surface of the arm portion 23 of the input member 2 in the circumferential direction (rotational direction), and part of the rotational force is transmitted to the input member 2.

[0048] (Action, effect) According to the clutch device 1 of this embodiment, the clutch device 1 includes a ball screw 3 and a reverse input cutoff clutch 11 having an output member (a nut 8 in this embodiment) that rotates integrally with the rotating member of the ball screw 3. The outer ring of the first bearing mechanism 6 that rotatably supports the nut 8 is an integrated outer ring 61 in which the first outer ring raceway groove 63, in which the first rolling element 60 rolls, and the pressed surface 45 are integrally formed in a single component. Since the pressed surface 45 is integrally formed with the outer ring of the bearing (the integrated outer ring 61 in this embodiment), which is generally made of a hard material, the hardness of the pressed surface 45 can be increased. This makes it possible to suppress wear caused by the pressing surface 51 of the engaging element 5 sliding on the pressed surface 45.

[0049] Furthermore, according to this embodiment, the coaxiality between the components can be improved. Here, a conventional clutch device 101A will be described as a comparative example for explaining the effects of the clutch device 1 of this embodiment. FIG. 11 is a schematic diagram of the conventional clutch device 101A. Note that, in the conventional technology shown in FIG. 11, descriptions of components similar to those of the first embodiment of the present invention will be omitted where appropriate. As shown in FIG. 11, the conventional clutch device 101A includes a ball screw 103 and a reverse input cutoff clutch 111. The ball screw 103 includes a nut 108 as a rotating member, a screw shaft 109 as a linearly acting member, and a plurality of balls 110. The reverse input cutoff clutch 111 includes an input member 102, a nut 108 as an output member, a pair of engaging elements 105, a housing 104, a pressed surface 145 provided on the housing 104, and a first bearing mechanism 106A. The first bearing mechanism 106A has a first rolling element 160, a first inner ring 181, a first inner ring raceway groove 164 formed in the first inner ring 181, a first outer ring 161, and a first outer ring raceway groove 163 formed in the first outer ring 161. The first inner ring 181 is formed as a separate body from the nut 108. The first inner ring 181 is attached to the outer periphery of the nut 108. The first outer ring 161 is also formed as a separate body from a pressed member (the housing 104 in the example shown in FIG. 11 ) having the pressed surface 145. The outer periphery of the first outer ring 161 is fitted into the inner periphery of the housing 104.

[0050] In the conventional clutch device 101A, the first outer ring 161 of the first bearing mechanism 106A, which rotatably supports the rotating member (nut 108) of the ball screw 103, and the pressed member (housing 104) having the pressed surface 145 of the reverse input cutoff clutch 111, are formed as separate components. Furthermore, the first inner ring 181 is formed as a separate component from the nut 108. In this conventional technology, the number of fitting surfaces between the components in the first bearing mechanism 106A is likely to be large, for example, between the first outer ring 161 and the housing 104, or between the nut 108 and the first inner ring 181. This makes it difficult to ensure concentricity, particularly between the nut 108 of the ball screw 103 and the pressed surface 145 of the reverse input cutoff clutch 111. Furthermore, the increased number of components in the first bearing mechanism 106A leads to problems such as increased assembly man-hours and a larger device size.

[0051] In contrast, according to the clutch device 1 of this embodiment, the first outer ring raceway groove 63 and the pressed surface 45 of the first bearing mechanism 6 are integrally formed on the one-piece outer ring 61, making it easier to ensure coaxiality between the output member, i.e., the nut 8, and the pressed surface 45. Therefore, compared to the prior art in which the outer ring in which the first outer ring raceway groove 63 is formed and the pressed surface 45 are each formed on separate components, it is possible to improve the coaxiality between the components. Furthermore, because the first outer ring raceway groove 63 and the pressed surface 45 are formed on the same component, the number of components can be reduced compared to the prior art in which the outer ring on which the first outer ring raceway groove 63 is formed and the pressed member on which the pressed surface 45 is formed are separate components. This also makes it possible to prevent the assembly work from becoming complicated and the device from becoming larger in size. Therefore, in the clutch device 1 that combines the ball screw 3 and the reverse input cutoff clutch 11, it is possible to provide a clutch device 1 that can improve the coaxiality between parts and suppress an increase in the number of parts compared to the prior art.

[0052] Improving the coaxiality between the nut 8 and the pressed surface 45 makes it easier to equalize the gap between the pair of engaging elements 5 and the pressed surface 45. This prevents a decrease in the locking function and bending of the output member, and improves the performance of the reverse input cutoff function of the reverse input cutoff clutch 11. Furthermore, the clutch device 1 of this embodiment can be used in, for example, a rear-wheel steering device. Conventionally, a ball screw mechanism has been adopted in rear-wheel steering devices. Because the ball screw 3 has a higher reverse actuation efficiency than a sliding screw, when a force acting to steer the tires of the rear-wheel steering device due to an external force or the like acts, the ball screw 3 rotates, potentially causing the tires to steer. To prevent the tires from steering, the motor needs to be continuously energized, which increases power consumption. In contrast, the clutch device 1 of this embodiment, which is configured by combining the ball screw 3 with the reverse input blocking clutch 11, can suppress rotation of the rotating member (the nut 8 in this embodiment) even when an axial load acts on the linearly moving member (the screw shaft 9 in this embodiment) due to an external force or the like. Therefore, the ball screw 3 with high reverse actuation efficiency can prevent unintentional tire steering due to an external force. Furthermore, because the reverse input blocking clutch 11 mechanically blocks the reverse input, there is no need to continuously energize the motor to prevent the tires from steering. This suppresses an increase in power consumption.

[0053] In the ball screw 3, the nut 8 is a rotating member, and the screw shaft 9 is a linear-motion member. The nut 8 is integrated with the output member of the reverse input cutoff clutch 11. As a result, the rotational torque transmitted from the input member 2 via the reverse input cutoff clutch 11 is transmitted to the output member (nut 8), causing the nut 8 to rotate. Therefore, the rotational torque input to the input mechanism is transmitted to the nut 8, converted into linear motion via the screw shaft 9, and output. Meanwhile, when an axial load is reversely input to the screw shaft 9, a force acts on the nut 8 to rotate due to the linear motion of the screw shaft 9. However, the rotation of the nut 8 is blocked by the reverse input cutoff clutch 11, and the rotational torque is not transmitted to the input mechanism. Therefore, even when a ball screw 3 with high reverse actuation efficiency is used, the reverse input from the output mechanism can be effectively blocked. Furthermore, compared to when the output member of the reverse input cutoff clutch 11 and the nut 8 are formed separately, the number of parts can be reduced, and the coaxiality between the reverse input cutoff clutch 11 and the nut 8 can be improved.

[0054] The first inner ring raceway groove 64 of the first bearing mechanism 6 is formed integrally with the nut 8. This eliminates the need to provide a separate component for the inner ring, thereby reducing the number of components. Furthermore, since the first inner ring raceway groove 64 and the nut 8 can be machined in the same process using a single chuck or the like, the coaxiality between the nut 8 and other components can be improved. Furthermore, compared to when a separate inner ring is provided, the number of mating surfaces in the first bearing mechanism 6 is reduced, thereby improving the coaxiality between the components connected via the first bearing mechanism 6.

[0055] The first bearing mechanism 6 and the second bearing mechanism 7 may be any of a four-point contact ball bearing, a deep groove ball bearing, an angular contact ball bearing, a tapered roller bearing, and a cylindrical roller bearing. This allows various types of bearings to be applied to the present invention, thereby increasing the versatility of the clutch device 1.

[0056] (Second embodiment) Next, a second embodiment of the present invention will be described. In the following description, the same components as those in the first embodiment described above will be assigned the same reference numerals and their description will be omitted where appropriate. Note that the specific components are not limited to these embodiments and can be modified as appropriate without departing from the spirit of the present invention. FIG. 4 is a schematic diagram of a clutch device 201 according to the second embodiment. The second embodiment differs from the first embodiment described above in that the inner ring of the first bearing mechanism is formed separately from the nut 8.

[0057] In the second embodiment, a first inner ring 281 is attached to the outer periphery of the nut body 12. A first inner ring raceway groove 264 (inner ring raceway surface in the claims) along which the first rolling element 60 rolls is formed on the outer periphery of this first inner ring 281. In other words, in this embodiment, the first bearing mechanism 206 has the first rolling element 60, the one-piece outer ring 61, the first outer ring raceway groove 63 and the pressed surface 45 formed on the one-piece outer ring 61, the first inner ring 281 attached to the nut 8, and the first inner ring raceway groove 264 formed on the first inner ring 281.

[0058] The clutch device 201 of the second embodiment can achieve the same effects as those of the first embodiment. Specifically, since the pressed surface 45 is integrally formed with the one-piece outer ring 61, the hardness of the pressed surface 45 can be increased. This can reduce wear and other problems caused by the pressing surface 51 of the engagement element 5 sliding on the pressed surface 45. Furthermore, since the first outer ring raceway groove 63 and the pressed surface 45 are provided on the one-piece outer ring 61, which is a single component, the coaxiality between the nut 8, which is the output member, and the pressed surface 45 can be improved. Furthermore, since the first outer ring raceway groove 63 and the pressed surface 45 are formed on the same component, the number of components can be reduced compared to the prior art, in which the outer ring, on which the first outer ring raceway groove 63 is formed, and the pressed member, on which the pressed surface 45 is formed, are separate components. This also reduces the complexity of the assembly process and the size of the device. Therefore, in a clutch device 201 that combines a ball screw 3 and a reverse input cutoff clutch 11, it is possible to provide a clutch device 201 that improves the coaxiality between parts compared to conventional technology and can suppress an increase in the number of parts. Furthermore, a first inner ring 281 of the first bearing mechanism 206 is attached to the outer periphery of the nut 8, and a first inner ring raceway groove 264 is formed on the outer periphery of the first inner ring 281. In this way, even in the case of a configuration in which an inner ring is provided separately, the above-described effects can be achieved, and therefore the versatility of the clutch device 201 can be improved.

[0059] (Third embodiment) Next, a third embodiment of the present invention will be described. In the following description, the same components as those in the second embodiment described above will be denoted by the same reference numerals, and the description thereof will be omitted as appropriate. Figure 5 is a schematic diagram of a clutch device 301 according to the third embodiment. The third embodiment differs from the second embodiment described above in that the nut 8 and the output member are formed as separate bodies.

[0060] In the third embodiment, the nut 8 of the ball screw 3 and the output member 313 of the reverse input cutoff clutch 11 are formed as separate bodies, and are connected to each other so that the nut 8 and the output member 313 can rotate integrally. Specifically, the nut 8 of the third embodiment has a nut body 312. The nut body 312 is formed in a cylindrical shape centered on the central axis C. A cylindrical output member 313 is fitted onto and fixed to the outer periphery of the first end of the nut body 312 in the axial direction. Therefore, the nut body 312 and the output member 313 rotate integrally. The outer periphery of the output member 313 forms an output-side engaging portion 314 that faces and comes into contact with the pair of engaging elements 5.

[0061] According to the clutch device 301 of the third embodiment, the nut 8 of the ball screw 3 and the output member 313 of the reverse input cutoff clutch 11 are formed separately, which simplifies the configuration of each of the nut 8 and the output member 313 and improves the workability of each part. For example, the increased flexibility in the shape of the output side engaging portion 314 increases the versatility of the clutch device 301. Furthermore, even when the nut 8 and the output member 313 are formed separately, the same effects as those of the first or second embodiment can be achieved.

[0062] (Fourth embodiment) Next, a fourth embodiment of the present invention will be described. In the following description, the same components as those in the first embodiment described above will be denoted by the same reference numerals, and the description thereof will be omitted as appropriate. Fig. 6 is a schematic diagram of a clutch device 401 according to the fourth embodiment. The fourth embodiment differs from the first embodiment described above in that a first bearing mechanism 406 and a second bearing mechanism 407 are double-row bearings.

[0063] In the fourth embodiment, the outer rings of the first bearing mechanism 406 and the second bearing mechanism 407 are an integrated outer ring 461 configured from a common component. The integrated outer ring 461, which is a single component, is formed with a first outer ring raceway groove 463 in which the first rolling element 60 of the first bearing mechanism 406 rolls, a pressed surface 445, and a second outer ring raceway groove 473 in which the second rolling element 70 of the second bearing mechanism 407 rolls, which are arranged in this order from the second side in the axial direction. In other words, the pressed surface 445 is disposed between the first outer ring raceway groove 463 and the second outer ring raceway groove 473 in the axial direction. The integrated outer ring 461 is fixed to the housing 4 (see FIG. 1 ).

[0064] According to the clutch device 401 of the fourth embodiment, the first outer ring raceway groove 463 of the first bearing mechanism 406, the pressed surface 445, and the second outer ring raceway groove 473 of the second bearing mechanism 407 are formed in the integrated outer ring 461, which is a single component. This provides the following additional advantages in addition to the advantages of the first embodiment. That is, because the first outer ring raceway groove 463, the pressed surface 445, and the second outer ring raceway groove 473 are integrally formed in the integrated outer ring 461, it becomes easier to ensure coaxiality between the output member (i.e., the nut 8), the pressed surface 445, and the input member 2. This improves the coaxiality between the components compared to conventional techniques in which the outer ring raceway grooves and pressed surfaces are formed in separate components.

[0065] Furthermore, since the outer ring of the first bearing mechanism 406 and the outer ring of the second bearing mechanism 407 are formed from the same part, the number of parts can be further reduced, which also makes it possible to prevent the assembly work from becoming complicated and the device from becoming larger in size. Furthermore, by improving the coaxiality between the input member 2 and the pressed surface 445, the pair of arms 23 can press against the engaging element 5 at the same time, thereby suppressing wear, vibration, and foreign matter contamination of parts that may occur due to poor coaxiality causing one arm 23 to press against the engaging element 5 first. Therefore, the performance of the reverse input cutoff function of the reverse input cutoff clutch 11 can be improved.

[0066] (Fifth embodiment) Next, a fifth embodiment of the present invention will be described. In the following description, the same components as those in the first embodiment described above will be denoted by the same reference numerals, and the description thereof will be omitted as appropriate. Fig. 7 is a schematic diagram of a clutch device 501 according to the fifth embodiment. The fifth embodiment differs from the first embodiment described above in that the rotating member of the ball screw is a screw shaft, and the linearly moving member is a nut.

[0067] In the fifth embodiment, the ball screw 503 has a screw shaft 509 as a rotating member, a nut 508 as a linear motion member, and a plurality of balls 10. The screw shaft 509 is rotatable about a central axis C but does not move in a direction along the central axis. The nut 508 is connected to a driven member (not shown). The nut 508 does not rotate about the central axis C but is movable in a direction along the central axis C. When the screw shaft 509 rotates, the nut 508 moves in a direction along the central axis C.

[0068] The nut 508 is formed in a cylindrical shape centered on the central axis C. A spiral inner circumferential rolling groove 517 is formed on the inner circumferential surface of the nut 508. The configuration of the inner circumferential rolling groove 517 is the same as the configuration of the inner circumferential rolling groove 17 (see FIG. 1) in the first embodiment, and therefore a description thereof will be omitted. The screw shaft 509 is formed in a cylindrical shape centered on the central axis C. The screw shaft 509 is provided inside the nut 508. A spiral outer circumferential rolling groove 518 is formed on the outer periphery of the screw shaft 509. The configuration of the outer circumferential rolling groove 518 is the same as the configuration of the outer circumferential rolling groove 18 in the first embodiment, so a description thereof will be omitted. A spiral rolling path is formed by the inner circumferential rolling groove 517 formed in the nut 508 and the outer circumferential rolling groove 518 formed in the screw shaft 509. The plurality of balls 10 move in this spiral rolling path.

[0069] In this embodiment, the screw shaft 509 has a screw shaft main body 526, a supported portion 527, and an insertion portion 513. The screw shaft main body 526, the supported portion 527, and the insertion portion 513 are integrally formed. The screw shaft main body 526 is provided on a second axial side of the screw shaft 509. The screw shaft main body 526 is a portion that threadably engages with the nut 508. The supported portion 527 is provided on a first axial side of the screw shaft main body 526. A first inner ring raceway groove 564, in which the first rolling element 60 of the first bearing mechanism 506 rolls, is formed on the outer periphery of the supported portion 527. In other words, the inner ring raceway groove 564 (inner ring raceway surface in claims) of the first bearing mechanism 506 is integrally formed on the screw shaft 509. The insertion portion 513 is provided on a first axial side of the supported portion 527. The insertion portion 513 is inserted between the pair of engagement elements 5 of the reverse input cutoff clutch 11. In this embodiment, the screw shaft 509 of the ball screw 503 and the output member of the reverse input cutoff clutch 11 are integrated.

[0070] The first bearing mechanism 506 has a first rolling element 60 that rolls around the axis, an integral outer ring 61, a first outer ring raceway groove 63 and a pressed surface 45 formed on the integral outer ring 61, and a first inner ring raceway groove 564 formed on a supported portion 527 of the screw shaft 509. The configuration of the first bearing mechanism 506 in the fifth embodiment is the same as the configuration of the first bearing mechanism 6 in the first embodiment except that the first inner ring raceway groove 564 is formed on the screw shaft 509, so a detailed description will be omitted.

[0071] According to the clutch device 501 of the fifth embodiment, even when the screw shaft 509 is a rotating member and the nut 508 is a linear-acting member in the ball screw 503, the same operational effects as those of the first embodiment can be achieved. That is, the rotational torque transmitted from the input member 2 via the reverse input blocking clutch 11 is transmitted to the output member (screw shaft 509), causing the screw shaft 509 to rotate. As a result, the rotational torque input to the input mechanism is transmitted to the screw shaft 509, converted into linear motion via the nut 508, and output. On the other hand, when an axial load is reversely input to the nut 508, a force acts to rotate the screw shaft 509 in association with the linear motion of the nut 508. However, the rotation of the screw shaft 509 (i.e., the output member) is blocked by the reverse input blocking clutch 11, and the rotational torque is not transmitted to the input mechanism. Therefore, in a ball screw with high reverse actuation efficiency, reverse input from the output mechanism can be effectively blocked.

[0072] Furthermore, according to this embodiment, the coaxiality between components can be improved. Here, a conventional clutch device 101B will be described as a comparative example for explaining the effects of the clutch device 501 of this embodiment. FIG. 12 is a schematic diagram of the conventional clutch device 101B. Note that, in the conventional technology shown in FIG. 12, descriptions of components similar to those of the fifth embodiment of the present invention will be omitted as appropriate. As shown in FIG. 12, the conventional clutch device 101B includes a ball screw 103 and a reverse input cutoff clutch 111. The ball screw 103 includes a screw shaft 119 as a rotating member, a nut 118 as a linearly acting member, and a plurality of balls 110. The reverse input cutoff clutch 111 includes an input member 102, a screw shaft 119 as an output member, a pair of engaging elements 105, a housing 104, a pressed surface 145 provided on the housing 104, and a first bearing mechanism 106B. The first bearing mechanism 106B has a first rolling element 160, a first inner ring 191, a first inner ring raceway groove 194 formed in the first inner ring 191, a first outer ring 196, and a first outer ring raceway groove 197 formed in the first outer ring 196. The first inner ring 191 is formed as a separate body from the screw shaft 119. The first inner ring 191 is attached to the outer periphery of the screw shaft 119. The first outer ring 196 is formed as a separate body from a pressed member (the housing 104 in the example shown in FIG. 12) having a pressed surface 145. The outer periphery of the first outer ring 196 is fitted into the inner periphery of the housing 104.

[0073] In the conventional clutch device 101B, the first outer ring 196 of the first bearing mechanism 106B, which rotatably supports the rotating member (screw shaft 119) of the ball screw 103, and the pressed member (housing 104) having the pressed surface 145 of the reverse input cutoff clutch 111, are formed as separate components. Furthermore, the first inner ring 191 is formed as a separate component from the screw shaft 119. In this conventional technology, the number of fitting surfaces between the components in the first bearing mechanism 106B is likely to be large, for example, between the first outer ring 196 and the housing 104, or between the screw shaft 119 and the first inner ring 191. This makes it difficult to ensure concentricity, particularly between the screw shaft 119 of the ball screw 103 and the pressed surface 145 of the reverse input cutoff clutch 111. Furthermore, the increased number of components in the first bearing mechanism 106B leads to problems such as increased assembly man-hours and a larger device size.

[0074] In contrast, according to the clutch device 501 of the fifth embodiment, the first outer ring raceway groove 63 of the first bearing mechanism 506 and the pressed surface 45 are integrally provided on the one-piece outer ring 61, which makes it easier to ensure coaxiality between the output member, i.e., the screw shaft 509, and the pressed surface 45. Therefore, compared to the prior art in which the outer ring in which the first outer ring raceway groove is formed and the pressed surface are each formed on separate components, it is possible to improve the coaxiality between the components. Furthermore, because the first outer ring raceway groove 63 and the pressed surface 45 are formed on the same component, the number of components can be reduced compared to the prior art in which the outer ring on which the first outer ring raceway groove is formed and the pressed member on which the pressed surface is formed are separate components, which also helps prevent the assembly work from becoming complicated and the device from becoming larger in size. Therefore, in a clutch device 501 that combines a ball screw 503 and a reverse input cutoff clutch 11, it is possible to provide a clutch device 501 that improves the coaxiality between parts and suppresses an increase in the number of parts compared to conventional technology.

[0075] Furthermore, compared to when the output member and the screw shaft are formed separately, the number of parts can be reduced and the coaxiality of the reverse input cutoff clutch 11 and the screw shaft 509 can be improved. Furthermore, even when screw shaft 509 is the rotating member and nut 508 is the linearly moving member, the above-described effects can be achieved, and therefore the versatility of clutch device 501 can be improved.

[0076] The first inner ring raceway groove 564 of the first bearing mechanism 506 is formed integrally with the screw shaft 509. This eliminates the need to provide a separate component as an inner ring, thereby reducing the number of components. Furthermore, since the first inner ring raceway groove 564 and the screw shaft 509 can be machined in the same process using one chuck or the like, the coaxiality of the screw shaft 509 and other components can be improved. Furthermore, since the mating surfaces in the first bearing mechanism 506 are smaller than when a separate inner ring is provided, the coaxiality of the components connected via the first bearing mechanism 506 can be improved.

[0077] (Sixth embodiment) Next, a sixth embodiment of the present invention will be described. In the following description, the same components as those in the fifth embodiment described above will be denoted by the same reference numerals, and the description thereof will be omitted as appropriate. Fig. 8 is a schematic diagram of a clutch device 601 according to the sixth embodiment. The sixth embodiment differs from the fifth embodiment described above in that the inner ring of the first bearing mechanism 606 is formed separately from the screw shaft 509.

[0078] In the sixth embodiment, a first inner ring 681 is attached to the outer periphery of the screw shaft 509. A first inner ring raceway groove 664 (inner ring raceway surface in the claims) in which the first rolling element 60 rolls is formed on the outer periphery of this first inner ring 681. In other words, in this embodiment, the first bearing mechanism 606 has the first rolling element 60, the one-piece outer ring 61, the first outer ring raceway groove 63 and the pressed surface 45 formed on the one-piece outer ring 61, the first inner ring 681 attached to the screw shaft 509, and the first inner ring raceway groove 664 formed on the first inner ring 681.

[0079] The clutch device 601 of the sixth embodiment can achieve the same effects as those of the fifth embodiment. That is, in the clutch device 601 in which the ball screw 503 and the reverse input cutoff clutch 11 are combined, it is possible to provide a clutch device 601 that can improve the coaxiality between the parts and suppress an increase in the number of parts compared to the prior art. Furthermore, a first inner ring 681 of the first bearing mechanism 606 is attached to the outer periphery of the screw shaft 509, and a first inner ring raceway groove 664 is formed on the outer periphery of the first inner ring 681. In this way, even in the case of a configuration in which an inner ring is provided separately, the above-mentioned effects can be achieved, and therefore the versatility of the clutch device 601 can be improved.

[0080] (Seventh embodiment) Next, a seventh embodiment of the present invention will be described. In the following description, the same components as those in the above-described fifth embodiment will be denoted by the same reference numerals, and the description thereof will be omitted as appropriate. Fig. 9 is a schematic diagram of a clutch device 701 according to the seventh embodiment. The seventh embodiment differs from the above-described fifth embodiment in that the screw shaft 509 and the output member are formed as separate bodies.

[0081] In the seventh embodiment, the screw shaft 509 of the ball screw 503 and the output member 713 of the reverse input cutoff clutch 11 are formed as separate bodies, and are connected to each other so that the screw shaft 509 and the output member 713 can rotate integrally. Specifically, the screw shaft 509 of the seventh embodiment has an extension portion 799. The extension portion 799 extends from the supported portion 527 of the screw shaft 509 to a first side in the axial direction. A cylindrical output member 713 is fitted onto and fixed to the outer periphery of the extension portion 799. Therefore, the extension portion 799 and the output member 713 rotate integrally. The outer periphery of the output member 713 forms an output-side engaging portion 714 that faces and comes into contact with a pair of engaging elements 5.

[0082] According to the clutch device 701 of the seventh embodiment, the screw shaft 509 of the ball screw 503 and the output member 713 of the reverse input cutoff clutch 11 are formed separately, which simplifies the configuration of each of the screw shaft 509 and the output member 713 and improves the workability of each part. For example, the increased flexibility in the shape of the output side engaging portion 714 increases the versatility of the clutch device 701. Furthermore, even when the screw shaft 509 and the output member 713 are formed separately, the same effects as those of the fifth embodiment can be achieved.

[0083] (Eighth embodiment) Next, an eighth embodiment of the present invention will be described. In the following description, the same components as those in the above-described fifth embodiment will be denoted by the same reference numerals, and description thereof will be omitted where appropriate. Fig. 10 is a schematic diagram of a clutch device 801 according to the eighth embodiment. The eighth embodiment differs from the above-described fifth embodiment in that a first bearing mechanism 806 and a second bearing mechanism 807 are double-row bearings.

[0084] In the eighth embodiment, the outer rings of the first bearing mechanism 806 and the second bearing mechanism 807 are an integrated outer ring 861 configured from a common component. The integrated outer ring 861, which is a single component, is formed with a first outer ring raceway groove 863 in which the first rolling element 60 of the first bearing mechanism 806 rolls, a pressed surface 845, and a second outer ring raceway groove 873 in which the second rolling element 70 of the second bearing mechanism 807 rolls, all of which are arranged in this order from the second side in the axial direction. In other words, the pressed surface 845 is located between the first outer ring raceway groove 863 and the second outer ring raceway groove 873 in the axial direction. The integrated outer ring 861 is fixed to the housing 4 (see FIG. 1 ).

[0085] According to the clutch device 801 of the eighth embodiment, the first outer ring raceway groove 863 of the first bearing mechanism 806, the pressed surface 845, and the second outer ring raceway groove 873 of the second bearing mechanism 807 are formed in the integrated outer ring 861, which is a single component. This provides the following additional advantages in addition to the advantages of the fifth embodiment. That is, because the first outer ring raceway groove 863, the pressed surface 845, and the second outer ring raceway groove 873 are integrally formed in the integrated outer ring 861, it becomes easier to ensure coaxiality between the output member (i.e., the screw shaft 509), the pressed surface 845, and the input member 2. This improves the coaxiality between the components compared to conventional techniques in which the outer ring raceway grooves and pressed surfaces are formed in separate components.

[0086] Furthermore, since the outer ring of the first bearing mechanism 806 and the outer ring of the second bearing mechanism 807 are formed from the same part, the number of parts can be further reduced, which also makes it possible to prevent the assembly work from becoming complicated and the device from becoming larger in size. Furthermore, by improving the coaxiality between the input member 2 and the pressed surface 845, the pair of arms 23 can press against the engaging element 5 at the same time, thereby suppressing wear, vibration, and foreign matter contamination of parts that may occur due to poor coaxiality causing one arm 23 to press against the engaging element 5 first. Therefore, the performance of the reverse input blocking function of the reverse input blocking clutch 11 can be improved.

[0087] According to the first to eighth embodiments described above, various combinations of ball screws and bearing mechanisms can be applied to the present invention, thereby improving the versatility of the clutch devices 1, 201, 301, 401, 501, 601, 701, and 801.

[0088] The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the first embodiment described above, the pressed surface 45 and the first outer ring raceway groove 63 in the one-piece outer ring 61 are formed to have the same radial dimension, but this is not limited to this. The pressed surface 45 and the first outer ring raceway groove 63 in the one-piece outer ring 61 may have different radial dimensions. In this case, a step or the like may be provided between the pressed surface 45 and the first outer ring raceway groove 63 in the axial direction to make the inner diameter dimension different.

[0089] In the first embodiment described above, the first bearing mechanism 6 and the second bearing mechanism 7 have the same type of bearing, but this is not limited to this. The first bearing mechanism 6 and the second bearing mechanism 7 may have different types or sizes of bearings. In the first embodiment, the first bearing mechanism 6 and the second bearing mechanism 7 may have the same size of bearing. 1 in the above-described first embodiment illustrates a configuration in which the bearing size of the first bearing mechanism 6 is smaller than the bearing size of the second bearing mechanism 7, but this is not limiting. For example, when the load on the output mechanism side is greater than that on the input mechanism side, the bearing size of the first bearing mechanism 6 may be formed larger than the bearing size of the second bearing mechanism 7. Alternatively, the basic dynamic load rating of the first bearing mechanism 6 may be formed larger than the load rating of the second bearing mechanism 7.

[0090] In the third and seventh embodiments described above, when the output member of the reverse input cutoff clutch 11 and the rotating member of the ball screw 3 are formed separately, the output member 313, 713 is provided on the outer periphery of the rotating member. However, this is not limited to this. That is, the configuration is not limited to the output member and the rotating member being connected to each other in the radial direction. When the output member of the reverse input cutoff clutch 11 and the rotating member of the ball screw 3 are formed separately, the output member and the rotating member may be connected to each other in the axial direction. In this case, the output member and the rotating member may be connected by, for example, a joint or the like so as to rotate integrally. However, the configuration of the first embodiment, in which the output member and the rotating member are the same part, is advantageous in that it is easy to ensure coaxiality between the output member and the rotating member, the number of parts can be reduced, and the complexity of the work can be suppressed.

[0091] In the above-described fourth and eighth embodiments, a configuration has been described in which the pressed surface 445, 845 is arranged between the first outer ring raceway groove 463, 863 and the second outer ring raceway groove 473, 873 in the axial direction for the one-piece outer ring 461, 861, but this is not limited to this. For example, the first outer ring raceway groove 463, 863, the second outer ring raceway groove 473, 873, and the pressed surface 445, 845 may be arranged in this order from the first side in the axial direction. The arrangement order is not limited to this.

[0092] In each of the above-described embodiments, the input shaft 21 and the arm portion 23 of the input member 2 are integrally formed, but this is not limiting. The input member 2 may be formed by combining a plurality of parts. The clutch devices 1, 201, 301, 401, 501, 601, 701, and 801 of the above-described embodiments may be applied to a system in which the direction of the reverse input torque is not constant, or to a system in which the direction of the input torque is not constant.

[0093] In the above-described embodiments, the reverse input cutoff clutch 11 is a linkless type that does not use a link structure as a reverse input cutoff mechanism, but the present invention is not limited to this. A link type reverse input cutoff clutch that uses a link mechanism, which is a known technology, may also be used as the reverse input cutoff mechanism.

[0094] The present disclosure may also be implemented as a combination of the following configurations. (1) an input member having an input shaft; an output member disposed coaxially with the input shaft; a pressed surface that is provided radially outward from the input member and the output member and faces radially inward; a pair of engaging elements each having a pressing surface opposite to the pressed surface, an input-side engaged portion engageable with the input member, and an output-side engaged portion engageable with the output member, the engaging elements being movable relative to each other along a first radial direction; a bearing mechanism having rolling elements and rotatably supporting the output member; a ball screw including a rotating member provided to rotate integrally with the output member and a linear motion member screwed with the rotating member; Equipped with When a rotational torque is input to the input shaft, the pair of engaging elements move toward each other radially inward in the first radial direction based on the engagement between the input member and the input-side engaged portion, and transmit the rotational torque to the output member based on the engagement between the output member and the output-side engaged portion, When a rotational torque is input in reverse to the output member, the pair of engaging elements move radially outward in the first radial direction so as to be separated from each other based on the engagement between the output member and the output-side engaged portion, thereby frictionally engaging the pressed surface and the pressing surface, The outer ring of the bearing mechanism is an integrated outer ring in which the outer ring raceway surface on which the rolling elements of the bearing mechanism roll and the pressed surface are integrally provided. Clutch device. (2) the rotating member is a nut having a spiral inner peripheral rolling groove on its inner peripheral surface, the linear motion member is a screw shaft having a spiral outer peripheral rolling groove on its outer peripheral surface, The output member and the nut are integrated. The clutch device described in (1). (3) The nut is integrally formed with an inner ring raceway surface of the bearing mechanism. (2) A clutch device according to the present invention. (4) An inner ring of the bearing mechanism is attached to an outer periphery of the nut, An inner ring raceway surface on which the rolling elements roll is formed on the outer periphery of the inner ring. (2) A clutch device according to the present invention. (5) the rotating member is a screw shaft having a spiral outer peripheral rolling groove on its outer peripheral surface, the linear motion member is a nut having a spiral inner peripheral rolling groove on its inner peripheral surface, The output member and the screw shaft are integrated. The clutch device described in (1). (6) An inner ring raceway surface of the bearing mechanism is integrally formed on the screw shaft. (5) A clutch device according to the present invention. (7) An inner ring of the bearing mechanism is attached to the outer periphery of the screw shaft, An inner ring raceway surface on which the rolling elements roll is formed on the outer periphery of the inner ring. (5) A clutch device according to the present invention. (8) a second bearing mechanism having a second rolling element and rotatably supporting the input member, wherein the one-piece outer ring is formed with the outer ring raceway surface on which the rolling element of the bearing mechanism rolls, the pressed surface, and a second outer ring raceway surface on which the second rolling element rolls; A clutch device according to any one of (1) to (7). (9) The bearing mechanism is any one of a four-point contact ball bearing, a deep groove ball bearing, an angular contact ball bearing, a tapered roller bearing, and a cylindrical roller bearing. A clutch device according to any one of (1) to (8). [Explanation of symbols]

[0095] 1,201,301,401,501,601,701,801,101A,101B Clutch device 2 Input member 3,503,103 Ball screws 5 Engagement element 6,206,406,506,606,806,106A,106B First bearing mechanism (bearing mechanism) 7,407,807 Second bearing mechanism 8,108 Nut (output member, rotating member) 9,109 Screw shaft (linear motion component) 17,517 Inner rolling groove 18,518 Outer periphery rolling groove 21 Input shaft 45,445,845,145 Pressed surface 51 Pressing surface 55 Input side engaged portion 56 Output side engaged part 60,160 First rolling element (rolling element) 61,461,861 Integrated outer ring (outer ring of bearing mechanism) 63,463,863,163,197 First outer ring raceway groove (outer ring raceway surface) 64,264,564,664,164,194 First inner ring raceway groove (inner ring raceway surface) 70 Second rolling element 73,473,873 Second outer ring raceway groove (second outer ring raceway surface) 281, 681, 181, 191 First inner ring (inner ring of bearing mechanism) 508,118 Nut (linear motion component) 509,119 Screw shaft (rotating member) D1 First radial direction

Claims

1. An input member having an input shaft, An output member arranged coaxially with the input shaft, A surface to be pressed is provided radially outward from the input member and the output member, and facing radially inward, A pair of engaging elements having a pressing surface facing the pressed surface, an input-side engaging portion that can engage with the input member, and an output-side engaging portion that can engage with the output member, and which are movable relative to each other along the first radial direction, A bearing mechanism having rolling elements and rotatably supporting the output member, A ball screw having a rotating member provided to rotate integrally with the output member, and a linear member that screws into the rotating member, Equipped with, When rotational torque is applied to the input shaft, the pair of engaging elements move toward each other radially inward in the first radial direction based on the engagement between the input member and the input-side engaged portion, and transmit the rotational torque to the output member based on the engagement between the output member and the output-side engaged portion. When rotational torque is applied in reverse to the output member, the pair of engaging elements move apart from each other radially outward in the first radial direction based on the engagement between the output member and the output-side engaged portion, causing frictional engagement between the pressed surface and the pressing surface. The outer ring of the bearing mechanism is an integrated outer ring in which the outer ring raceway surface on which the rolling elements of the bearing mechanism roll and the pressed surface are provided together. Clutch device.

2. The rotating member is a nut having a helical inner circumferential rolling groove on its inner surface. The linear motion member is a screw shaft having a helical outer surface rolling groove, The output member and the nut are integrated. The clutch device according to claim 1.

3. The inner ring raceway surface of the bearing mechanism is integrally formed on the nut. The clutch device according to claim 2.

4. The inner ring of the bearing mechanism is attached to the outer circumference of the nut. An inner ring raceway surface is formed on the outer circumference of the inner ring on which the rolling elements roll. The clutch device according to claim 2.

5. The rotating member is a screw shaft having a helical outer surface rolling groove, The linear motion member is a nut having a spiral inner circumferential rolling groove on its inner surface. The output member and the screw shaft are integrated. The clutch device according to claim 1.

6. The inner ring raceway surface of the bearing mechanism is integrally formed on the screw shaft. The clutch device according to claim 5.

7. The inner ring of the bearing mechanism is attached to the outer circumference of the screw shaft. An inner ring raceway surface is formed on the outer circumference of the inner ring on which the rolling elements roll. The clutch device according to claim 5.

8. The inner ring raceway surface of the bearing mechanism is provided in a position that overlaps with the inner circumferential rolling groove of the nut in the axial direction. The clutch device according to claim 3.

9. The inner ring raceway surface of the bearing mechanism is provided in a position that overlaps with the inner circumferential rolling groove of the nut in the axial direction. The clutch device according to claim 4.

10. It has a second rolling element and a second bearing mechanism that rotatably supports the input member, The aforementioned integrated outer ring has an outer ring raceway surface on which the rolling elements of the bearing mechanism roll, a pressed surface, and a second outer ring raceway surface on which the second rolling elements roll. A clutch device according to any one of claims 1 to 9.

11. The bearing mechanism is one of the following: a four-point contact ball bearing, a deep groove ball bearing, an angular contact ball bearing, a tapered roller bearing, or a cylindrical roller bearing. A clutch device according to any one of claims 1 to 9.

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