Clutch device

Abstract

A clutch device (1) comprises: 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 rotary member (nut (8)) mounted to rotate integrally with the output member, and a linear motion member (screw shaft (9)) screwed with the rotary member. An outer ring of the first bearing mechanism (6) is an integrated outer ring (61) in which the pressed surface (45) and a first outer ring raceway groove (63) in which a first rolling element (60) of the first bearing mechanism (6) rolls are integrally provided.

Description

Clutch device

[0001] This application claims priority from Japanese Patent Application No. 2024-098127, filed on June 18, 2024, the contents of which are incorporated herein by reference.

[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 an actuator configuration 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 reversely input from the output mechanism to the screw shaft, the axial load is converted into rotational torque of the nut, and this rotational torque is reversely input from the nut to the output member of the reverse input cutoff clutch. The rotational torque reversely input 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.

[0004] International Publication No. 2019 / 216280

[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 having the pressed surface of the reverse input cutoff clutch are formed as separate parts (see also FIG. 11 ), which 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. Therefore, when a rotational force is input in reverse to the output member, only one engaging element will first come into contact with the pressed member, 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, potentially reducing performance.

[0007] Furthermore, in the conventional technology 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. There is also a risk of the device becoming larger. Therefore, in the conventional technology, there is 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.

[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 disposed radially outward of the input member and the output member, each 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, and a ball screw having a rotating member provided to rotate integrally with the output member and a linear member screwed to the rotating member, wherein a rotational torque is input to the input shaft. 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 rotational torque is input in reverse 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 is an integrated outer ring in which the pressed surface and the outer ring raceway surface on which the rolling elements of the bearing mechanism roll are integrally formed.

[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.

[0011] Cross-sectional view of the clutch device according to the first embodiment. Cross-sectional view taken along line II-II in FIG. 1. Schematic configuration diagram of the clutch device according to the first embodiment. Schematic configuration diagram of the clutch device according to the second embodiment. Schematic configuration diagram of the clutch device according to the third embodiment. Schematic configuration diagram of the clutch device according to the fourth embodiment. Schematic configuration diagram of the clutch device according to the fifth embodiment. Schematic configuration diagram of the clutch device according to the sixth embodiment. Schematic configuration diagram of the clutch device according to the seventh embodiment. Schematic configuration diagram of the clutch device according to the eighth embodiment. Schematic configuration diagram of a clutch device according to the prior art. Schematic configuration diagram of a clutch device according to the prior art.

[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 (e.g., 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 a first axial side, and the opposite side may be referred to as a 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 the 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 threadedly engaged with the screw shaft 9 via balls 10. An inner circumferential rolling groove 17, which is a spiral groove, is formed on the inner surface of the nut body 12. The cross-sectional shape of the inner circumferential rolling groove 17 is a Gothic arch including two 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 FIGS. 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 a 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] 1 and 3, a plurality of balls 10 are disposed 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 assembled together, 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 of a spiral rolling path to the other to form an infinite circulation circuit. A plurality of balls 10 are filled in this infinite circulation circuit, and 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 reversely input from the output mechanism side to the screw shaft 9. This realizes a function to suppress 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 engagers 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 and not transmitting it 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 the arms 23 is 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 cylindrically formed about 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 engagers 5. The output side engaging portions 14 are arranged inward in the first radial direction D1 of the input side engaging portions 25 of the input member 2.

[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 number of engaging elements 5. The number of output-side engaging portions 14 is not limited to two, and 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 the reverse input cutoff clutch 11 described above. The housing 4 is a housing component having 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 against a pressed surface 45 provided on an 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 against the pressed surface 45 when the reverse input cutoff clutch 11 is in a locked state (a state in which the reverse input from the output mechanism is cut off). 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 portions 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 straight 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 the present embodiment, the bottom surface 52 is formed as a substantially flat surface. 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 element 5 are set so that, when the pair of engaging elements 5 are arranged inside the pressed surface 45, a gap exists between the pressed surface 45 and the pressing surface 51, and / or 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 axial direction through the center of the engaging element 5 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 into them. Specifically, the input side engaged portions 55 are formed so that when the arm portions 23 of the input member 2 are inserted inside the input side engaged portions 55, a gap exists between the arm portions 23 and the inner surface of the input side engaged portions 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 ends 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 axially inserted into the input-side engaged portions 55 of the pair of engaging elements 5, and the insertion portion 13 of the nut 8 is axially inserted 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 element 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 a plurality of bearing mechanisms, namely, a first bearing mechanism 6 (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 rotatably supports the nut 8 relative to the housing 4. The first bearing mechanism 6 includes 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 the first outer ring raceway groove 63, along which the balls serving as the first rolling elements 60 roll, and the 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 in which the second rolling element 70 rolls 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 Clutch Device) Next, the operation of the clutch device 1 of this embodiment will be described. First, a case where a rotational force is input to the input shaft 21 from the input mechanism will be described. 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 portion 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 portions 14 are parallel to the output-side engaged portions 56 of the engagers 5, and the insertion portions 13 of the nut 8 are 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 engagers 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 the pair of engagers 5 in directions 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 engagers 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 portions 56 outward in the first radial direction D1, moving each of the pair of engaging elements 5 toward the pressed surface 45. In other words, based on the engagement between the nut 8 and the output-side engaged portions 56, the pair of engaging elements 5 move away from each other outward in the first radial direction D1. As a result, the pressing surfaces 51 of the pair of engaging elements 5 are pressed against the pressed surface 45. At this time, the pressing surface 51 and the pressed surface 45 are frictionally engaged over the entire circumferential range of the pressing surface 51 or at least a portion thereof.

[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) against 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 while the nut 8 is half-locked, 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] (Operations and Effects) 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 integral 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 provided in a single component. Since the pressed surface 45 is integrally formed with the outer ring of the bearing (the integral 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 components can be improved. Here, a conventional clutch device 101A will be described as a comparative example for explaining the operational 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 , description of the same configuration as that of the first embodiment of the present invention will be omitted as 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 separately 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 separately from a pressed member (the housing 104 in the example shown in FIG. 11 ) having a 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 components in the first bearing mechanism 106A is likely to be large, for example, between the first outer ring 161 and the housing 104 and 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 issues 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. This improves the coaxiality between the components compared to the conventional technology in which the outer ring on which the first outer ring raceway groove 63 is formed and the pressed surface 45 are formed on separate components. 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 conventional technology 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 prevents the assembly process from becoming complicated and the device from becoming larger. Therefore, a clutch device 1 can be provided that improves the coaxiality between the components and prevents an increase in the number of components compared to the conventional technology in which the ball screw 3 and the reverse input cut-off clutch 11 are combined.

[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 suppresses deterioration of the locking function and bending of the output member, thereby improving the performance of the reverse input blocking function of the reverse input blocking clutch 11. Furthermore, the clutch device 1 of this embodiment can be used, for example, in 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 may rotate, potentially causing the tires to turn. To prevent the tires from turning, the motor must be kept energized, which increases power consumption. In contrast, the clutch device 1 of this embodiment, which combines 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, in the ball screw 3 with high reverse actuation efficiency, it is possible to prevent the tires from unintentionally turning due to an external force. Also, because the reverse input is mechanically blocked by the reverse input blocking clutch 11, there is no need to keep the motor energized to prevent the tires from turning. Therefore, it is possible to prevent 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, 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, rotational torque input to the input mechanism can be 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 to rotate the nut 8 in conjunction with 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, 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, for example, the coaxiality of 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 of 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 denoted by the same reference numerals, and the description thereof will be omitted as appropriate. Note that the specific configuration is not limited to these embodiments, and can be modified as appropriate without departing from the gist 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 the first embodiment. Specifically, because 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 reduces wear and other problems caused by the pressing surface 51 of the engaging element 5 sliding on the pressed surface 45. Furthermore, because 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, 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 reduces the complexity of the assembly process and the size of the device. Therefore, in the clutch device 201 that combines the ball screw 3 and the reverse input cutoff clutch 11, it is possible to provide a clutch device 201 that can improve the coaxiality between parts and suppress an increase in the number of parts compared to the prior art. Also, the first inner ring 281 of the first bearing mechanism 206 is attached to the outer periphery of the nut 8, and the first inner ring raceway groove 264 is formed on the outer periphery of the first inner ring 281. In this way, even when a configuration is adopted in which the inner ring is provided separately, the above-mentioned 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 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 a 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 description thereof will be omitted as appropriate. Figure 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 the first bearing mechanism 406 and the 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, all of which are arranged in this order from the second side in the axial direction. In other words, the pressed surface 445 is located 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 one-piece outer ring 461, which is a single component. This provides the following additional effect in addition to the effects 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 one-piece outer ring 461, it is 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 the prior art, in which the outer ring raceway groove and the pressed surface are formed in separate components.

[0065] Furthermore, because 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. This also prevents the assembly work from becoming complicated and the device from becoming larger. 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 preventing wear, vibration, and foreign matter from entering the parts, which would otherwise occur if one arm 23 pressed against the engaging element 5 first due to poor coaxiality. 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 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 linearly moving 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 C. 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 equivalent to the configuration of the inner circumferential rolling groove 17 (see FIG. 1 ) in the first embodiment, so 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 equivalent to the configuration of the outer circumferential rolling groove 18 in the first embodiment, so a description thereof will be omitted. The inner circumferential rolling groove 517 formed in the nut 508 and the outer circumferential rolling groove 518 formed in the screw shaft 509 form a spiral rolling path. 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 (referred to as an inner ring raceway surface in the 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 a 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 operational 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, the description of the same configuration as that 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 separately from the threaded shaft 119. The first inner ring 191 is attached to the outer periphery of the threaded shaft 119. The first outer ring 196 is formed separately 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 components in the first bearing mechanism 106B tends 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 issues such as increased assembly man-hours and a larger device.

[0074] In contrast, in the clutch device 501 of the fifth embodiment, the first outer ring raceway groove 63 and the pressed surface 45 of the first bearing mechanism 506 are integrally formed on the integrated outer ring 61, making it easier to ensure coaxiality between the output member, i.e., the screw shaft 509, and the pressed surface 45. This improves the coaxiality between the components compared to conventional technology in which the outer ring, on which the first outer ring raceway groove is formed, and the pressed surface are formed on separate components. 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 conventional technology 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. This also reduces the complexity of assembly work and the size of the device. Therefore, a clutch device 501 combining a ball screw 503 and a reverse input cutoff clutch 11 can be provided that improves the coaxiality between the components and minimizes the number of components 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 the screw shaft 509 is the rotating member and the nut 508 is the linearly acting member, the above-mentioned effects can be achieved, and therefore the versatility of the 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 a single chuck, 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 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) along 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 includes 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 that combines the ball screw 503 and the reverse input cutoff clutch 11, it is possible to provide a clutch device 601 that can improve the coaxiality of the components and suppress an increase in the number of components compared to the conventional technology. Furthermore, the first inner ring 681 of the first bearing mechanism 606 is attached to the outer periphery of the screw shaft 509, and the first inner ring raceway groove 664 is formed on the outer periphery of the first inner ring 681. In this way, even when a configuration is adopted in which the inner ring is provided separately, the above-mentioned effects can be achieved, thereby increasing the versatility of the clutch device 601.

[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 fifth embodiment described above will be denoted by the same reference numerals, and description thereof will be omitted as appropriate. Figure 9 is a schematic diagram of a clutch device 701 according to the seventh embodiment. The seventh embodiment differs from the fifth embodiment described above 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 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 fifth embodiment described above 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 fifth embodiment described above 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 effect in addition to the effects 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 the prior art, in which the outer ring raceway grooves and pressed surfaces are formed in separate components.

[0086] Furthermore, because 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. This also prevents the assembly work from becoming complicated and the device from becoming larger. 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 preventing wear, vibration, and foreign matter from entering the parts, which would otherwise occur if one arm 23 pressed against the engaging element 5 first due to poor coaxiality. 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 above-described first embodiment, 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 bearing type, but this is not limited thereto. The first bearing mechanism 6 and the second bearing mechanism 7 may have different bearing types or sizes. In the first embodiment, the first bearing mechanism 6 and the second bearing mechanism 7 may have the same bearing size. In FIG. 1 of the first embodiment described above, the first bearing mechanism 6 has a smaller bearing size than the second bearing mechanism 7, but this is not limited thereto. For example, when the load on the output mechanism side is greater than that on the input mechanism side, the first bearing mechanism 6 may have a larger bearing size than the second bearing mechanism 7. Alternatively, the first bearing mechanism 6 may have a basic dynamic load rating greater 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 coupling 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 fourth and eighth embodiments described above, the one-piece outer ring 461, 861 has been described as having a configuration 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, 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 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, for example. Similarly, they may be applied 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 a combination of the following configurations: (1) An input member having an input shaft, an output member arranged coaxially with the input shaft, a pressed surface provided radially outward of the input member and the output member and facing inward in the radial direction, a pair of engagers each having 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, and being movable relative to each other along a first radial direction, a bearing mechanism having rolling elements and rotatably supporting the output member, and a ball screw having a rotating member provided to rotate integrally with the output member and a linear member screwed with the rotating member, wherein when a rotational torque is input to the input shaft, the pair of engagers 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, (1) The clutch device according to (1), wherein, when a 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 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 is an integrated outer ring in which the pressed surface is integrally provided with an outer ring raceway surface on which the rolling elements of the bearing mechanism roll. (2) The clutch device according to (1), wherein the rotating member is a nut having a spiral inner circumferential rolling groove on its inner circumferential surface, and the linear moving member is a threaded shaft having a spiral outer circumferential rolling groove on its outer circumferential surface, and the output member and the nut are integrated. (3) The clutch device according to (2), wherein the nut is integrally formed with an inner ring raceway surface of the bearing mechanism. (4) The clutch device according to (2), wherein an inner ring of the bearing mechanism is attached to an outer periphery of the nut, and an inner ring raceway surface on which the rolling elements roll is formed on an outer periphery of the inner ring.(5) The clutch device according to (1), wherein the rotating member is a threaded shaft having a spiral outer peripheral rolling groove on its outer peripheral surface, and the linear motion member is a nut having a spiral inner peripheral rolling groove on its inner peripheral surface, and the output member and the threaded shaft are integrated. (6) The clutch device according to (5), wherein an inner ring raceway surface of the bearing mechanism is integrally formed with the threaded shaft. (7) The clutch device according to (5), wherein an inner ring of the bearing mechanism is attached to the outer peripheral portion of the threaded shaft, and an inner ring raceway surface on which the rolling elements roll is formed on the outer peripheral portion of the inner ring. (8) The clutch device according to any one of (1) to (7), further comprising a second bearing mechanism having second rolling elements and rotatably supporting the input member, and wherein the integrated outer ring is formed with the outer ring raceway surface on which the rolling elements of the bearing mechanism roll, the pressed surface, and a second outer ring raceway surface on which the second rolling elements roll. (9) The clutch device according to any one of (1) to (8), wherein the bearing mechanism is 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.

[0095] DESCRIPTION OF SYMBOLS 1,201,301,401,501,601,701,801,101A,101B Clutch device 2 Input member 3,503,103 Ball screw 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 (linearly acting member) 17,517 Inner peripheral rolling groove 18,518 Outer peripheral rolling groove 21 Input shaft 45,445,845,145 Pressed surface 51 Pressing surface 55 Input side engaged portion 56 Output side engaged portion 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 (linearly acting member) 509, 119 Screw shaft (rotating member) D1 First radial direction

Claims

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. 　 the rotating member is a nut having a spiral inner circumferential rolling groove on its inner circumferential 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.

2. The clutch device according to claim 1. 　 The nut is integrally formed with an inner ring raceway surface of the bearing mechanism.

3. The clutch device according to claim 2. 　 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.

3. The clutch device according to claim 2. 　 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.

2. The clutch device according to claim 1. 　 An inner ring raceway surface of the bearing mechanism is integrally formed on the screw shaft.

6. The clutch device according to claim 5. 　 An inner ring of the bearing mechanism is attached to an 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.

6. The clutch device according to claim 5. 　 a second bearing mechanism having a second rolling element and rotatably supporting the input member; The one-piece outer ring is formed with the outer ring raceway surface on which the rolling elements of the bearing mechanism roll, the pressed surface, and a second outer ring raceway surface on which the second rolling elements roll. The clutch device according to any one of claims 1 to 7. 　 The bearing mechanism is 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 claims 1 to 8.

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