Rotational transmission device

Abstract

To provide a rotation transmitting device capable of quickly releasing an adsorption state of an armature when an electromagnetic clutch is not energized, and preventing the generation of friction due to sliding when an input shaft is rotated during non-energization.SOLUTION: In a rotation transmitting device equipped with a two-way clutch 2 and an electromagnetic clutch 3, the electromagnetic clutch 3 has an electromagnet 23 that has a field core 29 and the like equipped with an inner cylinder part 27 and an outer cylinder part 28, an armature 24 that is adsorbed by the field core 29, a friction plate 25 that is disposed opposite the armature 24, and a separating spring 26 that energizes the armature 24 toward the friction plate 25. An axial direction end part of one of the inner cylinder part 27 and the outer cylinder part 28 projects out in an axial direction from the other axial direction end portion or has a bearing 43 permitting relative rotations of the armature 24 and the friction plate 25 around the axis.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This invention relates to a rotational transmission device that switches between transmitting and blocking the rotation from an input shaft to an output shaft.

Background Art

[0002] As a rotational transmission device that switches between transmitting and blocking the rotation from an input shaft to an output shaft, for example, as shown in Patent Document 1, there is one having a two-way clutch 10 and an electromagnetic clutch 20 housed in a housing 1 as main components.

[0003] The two-way clutch 10 has an outer ring 3 with a cylindrical surface 11 formed on its inner circumference, and a cam ring 4 (corresponding to the inner ring of the present application) having a flat cam surface 12 continuously formed in the circumferential direction on its outer circumference and forming a wedge-shaped space with narrow ends in the circumferential direction between the cylindrical surface 11. A roller 13 as an engaging element is incorporated between each cam surface 12 and the cylindrical surface 11. Each roller 13 is held by a pocket 15 formed in a retainer 14. A cylindrical portion 16 is formed on the end face of the cam ring 4, and a switch spring 17 with a part cut off is incorporated in the cylindrical portion 16. A pair of pressing pieces 17a are formed at both ends of the switch spring 17. The pressing piece 17a fits into a notch 19 provided at the end of the retainer 14 from a notch 18 formed in the cylindrical portion 16 and presses a pair of side faces facing each other in the circumferential direction of the notch 18 and the notch 19 in opposite directions. By this pressing, the retainer 14 is elastically held in a position where the roller 13 is disengaged from the cylindrical surface 11 and the cam surface 12.

[0004] The electromagnetic clutch 20 includes an armature 21 (corresponding to the friction plate in this application) positioned opposite the open end face of the outer ring 3, a switching plate 22 (corresponding to the armature in this application) positioned opposite the armature 21, an electromagnet 23 positioned opposite the switching plate 22, and a separation spring 24 provided between the electromagnet 23 and the switching plate 22. The open end face of the outer ring 3 becomes the contact portion of the armature 21. The armature 21 is supported by a cam ring 4 so as to be movable in the axial direction. An engagement hole 26 is formed in the armature 21, and an engagement piece 27 formed on the open end of the retainer 14 engages with the engagement hole 26. This engagement prevents the armature 21 from rotating relative to the retainer 14 and allows it to move in the axial direction. The switching plate 22 is fitted onto a first shaft 5 (corresponding to the input shaft in this application) connected to the cam ring 4 and is movable in the axial direction.

[0005] The electromagnet 23 has an electromagnetic coil 23a and a core 23b that supports the electromagnetic coil 23a. The core 23b has an outer cylindrical portion 23c and an inner cylindrical portion 23d, and the opening of the annular space formed between the outer cylindrical portion 23c and the inner cylindrical portion 23d faces the switching plate 22. A separation spring 24 is incorporated on the outer circumference of the end of the outer cylindrical portion 23c of the core 23b. This separation spring 24 biases the switching plate 22 away from the core 23b.

[0006] When the electromagnetic coil 23a of the electromagnet 23 is energized, the switching plate 22 is attracted to the end faces of the outer cylinder portion 23c and inner cylinder portion 23d of the core 23b, and the coupling of the armature 21 to the outer ring 3 is released. As a result, when the cam ring 4 rotates together with the first shaft 5 due to steering of the steering wheel, that rotation is transmitted to the retainer 14 via the switch spring 17. The retainer 14 then rotates together with the cam ring 4, and the roller 13 rotates while being held in a neutral position disengaged from the cylindrical surface 11 and the cam surface 12. As a result, the rotation of the cam ring 4 is not transmitted to the outer ring 3, and the cam ring 4 (first shaft 5) rotates freely.

[0007] On the other hand, when the electromagnetic coil 23a is de-energized, the restorative elasticity of the separation spring 24 causes the switching plate 22 to move away from the core 23b. This movement causes the armature 21 to press against the contact portion 25 of the outer ring 3, and it becomes coupled to the outer ring 3. Therefore, when the cam ring 4 rotates together with the first shaft 5 due to steering of the steering wheel, the cam ring 4 and the retainer 14 rotate relative to each other, and this relative rotation causes the roller 13 to engage with the cylindrical surface 11 and the cam surface 12, resulting in the two-way clutch 10 coupling the cam ring 4 and the outer ring 3. As a result, the steering gear can be manually operated by the steering wheel (see paragraphs 0012 to 0029 and Figures 1 to 5 of Patent Document 1). [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2008-57625 [Overview of the project] [Problems that the invention aims to solve]

[0009] In the rotary transmission device described in Patent Document 1, the axial ends of the outer cylinder portion 23c and the inner cylinder portion 23d of the core 23b are aligned, so the switching plate 22 is evenly attracted to the outer cylinder portion 23c and the inner cylinder portion 23d. In this case, even if the electromagnetic coil 23a is switched to a non-energized state, the magnetic path on the attraction surface does not decrease easily due to the back electromotive force, which causes a delay in the detachment of the switching plate 22. In addition, in order to suppress the axial rattle of internal components such as the two-way clutch 10 and the electromagnetic clutch 20 due to the operation of the steering wheel and the operation of the electromagnetic clutch, it is necessary to provide many retaining rings, but this presents a problem of costs such as the cost of machining the circumferential grooves for engaging the retaining rings, the cost of parts, and labor.

[0010] Furthermore, in the rotary transmission device described in Patent Document 1, when the first shaft 5 is rotated when no power is supplied, sliding occurs between the switching plate 22, the retaining ring provided on the outer diameter portion of the core 23b, and the separation spring 24, resulting in a problem of wear occurring at the sliding parts.

[0011] Therefore, the first objective of this invention is to quickly release the suction state when the electromagnetic clutch is de-energized, while suppressing axial rattle of internal components and reducing costs. The second objective is to prevent wear caused by sliding when the input shaft is rotated when the power is off. [Means for solving the problem]

[0012] In order to solve the first problem described above, in this invention, A two-way clutch that switches between transmitting and interrupting rotation between the input shaft and the output shaft, An electromagnetic clutch that performs the switching operation of the two-way clutch, A case housing the two-way clutch and the electromagnetic clutch inside, In a rotary transmission device equipped with, The case has an elastic member that presses the two-way clutch and the electromagnetic clutch in the axial direction, The aforementioned electromagnetic clutch An electromagnet having a field core with a C-shaped circumferential cross-section, comprising a cylindrical inner portion and an outer portion with a larger diameter than the inner portion, and a solenoid coil wound between the inner and outer portions of the field core, An armature is positioned so as to face the opening end of the field core from the axial direction, and is attracted to the field core when the electromagnet is excited, A friction plate positioned opposite the armature, A separation spring biases the armature toward the friction plate, It has, A rotational transmission device is configured characterized in that one axial end of the inner cylinder portion or the outer cylinder portion of the field core protrudes more in the axial direction than the other axial end.

[0013] In this configuration, the armature, which is unevenly attracted to the inner and outer cylinders with different axial protrusions, undergoes elastic deformation when the solenoid coil is energized. When the solenoid coil is de-energized and the armature is released from its attraction to the inner and outer cylinders, the elastically deformed armature returns to its original shape, and the repulsive force associated with this restoration quickly releases the armature from its attraction to the inner and outer cylinders. Furthermore, because the internal components are pre-pressurized in the axial direction by the pressing force of the elastic member, the number of retaining rings required to prevent axial rattle of the internal components within the case can be kept to a minimum.

[0014] In the above configuration, it is preferable that the axial end of the outer cylinder portion protrudes more in the axial direction than the axial end of the inner cylinder portion.

[0015] In this way, the armature is held in close contact by the outer cylinder, which has a longer circumferential length than the inner cylinder, making the adsorption more stable.

[0016] In each of the above configurations, it is preferable that the difference in the amount of axial protrusion between the axial end of the inner cylinder and the axial end of the outer cylinder is within the range of 0.01 mm to 2 mm.

[0017] In this way, the armature can be stably adsorbed while generating sufficient repulsive force as the elastically deformed armature recovers.

[0018] In each of the above configurations, it is preferable to have a bearing that allows the armature and the friction plate to rotate relative to each other around an axis.

[0019] By doing so, it is possible to prevent wear due to sliding between the separation spring and the field core when rotating the input shaft when the electromagnet is de-energized.

[0020] Also, in order to solve the above-mentioned second problem, in this invention, a two-way clutch that switches between transmission and interruption of rotation between the input shaft and the output shaft, an electromagnetic clutch that performs the switching operation of the two-way clutch, in a rotation transmission device provided with the electromagnetic clutch is a field core having a cylindrical inner cylinder portion and an outer cylinder portion having a larger diameter than the inner cylinder portion, the circumferential cross-section of which is C-shaped, and a solenoid coil wound between the inner cylinder portion and the outer cylinder portion of the field core, an electromagnet having an armature arranged so as to face the opening side end portion of the field core in the axial direction and adsorbed to the field core when the electromagnet is excited, a friction plate arranged to face the armature, a separation spring that biases the armature toward the friction plate, having constitutes a rotation transmission device characterized by having a bearing that allows relative rotation around the axis between the armature and the friction plate.

[0021] By doing so, it is possible to prevent wear due to sliding between the separation spring and the armature when rotating the input shaft when the electromagnet is de-energized.

[0022] In each of the above configurations, the two-way clutch is an inner ring provided on one of the input shaft or the output shaft, an outer ring provided on the other shaft from the shaft provided with the inner ring of the input shaft or the output shaft, an engaging element arranged between the outer circumference of the inner ring and the inner circumference of the outer ring, A retainer is provided that holds the engaging element and is circumferentially movable between an engagement position in which the engaging element engages the outer circumference of the inner ring and the inner circumference of the outer ring, and a release position in which the engagement is released. A centering spring is provided to the inner ring and the retainer so as to be fixed to the retainer and to be fixed to the retainer so as to be elastically held in the released position and to rotate integrally with the inner ring. It is preferable to have.

[0023] In this way, the electromagnetic clutch can be easily switched between a state in which the engaging element is engaged between the inner and outer rings, enabling rotational transmission between the input and output shafts, and a state in which the engaging element between the inner and outer rings is disengaged, allowing the input and output shafts to rotate freely relative to each other.

[0024] In each of the above configurations, it is preferable that the input shaft or the output shaft and the inner ring are integrally configured.

[0025] This prevents circumferential play in the input or output shaft caused by the rotation of the inner ring.

[0026] In each of the above configurations, it is preferable to use a configuration that is used as a clutch to connect both the input shaft and the output shaft when the steer-by-wire system fails.

[0027] This approach allows for a quick transition to manual operation in the event of a failure in the electromagnet or other components, thus ensuring operability and safety. [Effects of the Invention]

[0028] The rotary transmission device according to this invention has different axial protrusion amounts for the inner and outer cylinder portions of the field core of the electromagnet, so that the attracted state can be quickly released when the solenoid coil is de-energized. Furthermore, since an elastic member is provided inside the case to pre-pressure the internal components in the axial direction, the number of retaining rings required to prevent axial rattle of the internal components inside the case can be kept to a minimum. In addition, since the rotary transmission device according to this invention is provided with bearings that allow relative rotation of the armature and friction plate around the axis, wear due to sliding can be prevented when rotating when de-energized. [Brief explanation of the drawing]

[0029] [Figure 1] Cross-sectional view showing the first embodiment of the rotary transmission device according to this invention. [Figure 2] Cross-sectional view of the main part of the rotary transmission device shown in Figure 1. [Figure 3] Cross-sectional view of the main part of the rotary transmission device shown in Figure 1. [Figure 4] Cross-sectional view along line IV-IV in Figure 1 [Figure 5] Cross-sectional view of the key part showing the armature's adsorption state. [Figure 6] Diagram showing the configuration of a steer-by-wire system employing the rotary transmission device shown in Figure 1. [Figure 7] Cross-sectional view of the main part of a modified rotary transmission device shown in Figure 1. [Figure 8] Cross-sectional view showing a second embodiment of the rotary transmission device according to this invention. [Figure 9] Cross-sectional view showing a third embodiment of the rotary transmission device according to this invention. [Figure 10] Cross-sectional view of the main part of the rotary transmission device shown in Figure 9. [Modes for carrying out the invention]

[0030] A first embodiment of the rotary transmission device 1 according to this invention will be described with reference to Figures 1 to 5. As shown in Figure 1, the rotary transmission device 1 includes a two-way clutch 2 and an electromagnetic clutch 3. Internal components such as the two-way clutch 2 are housed inside a case 4.

[0031] The two-way clutch 2 has the function of switching between transmitting and disconnecting rotation between the input shaft 5 and the output shaft 6. This two-way clutch 2 has an inner ring 8 integrally formed with the input shaft 5 at the shaft end of the input shaft 5 which is connected to a steering wheel 7 (see Figure 6), an outer ring 9 integrally formed with the output shaft 6 at the shaft end of the output shaft 6, an engaging element 10 positioned between the outer circumference of the inner ring 8 and the inner circumference of the outer ring 9, a retainer 11 that holds the engaging element 10, and a centering spring 12.

[0032] As shown in Figure 4, multiple cam surfaces 13 are formed on the outer circumferential surface of the inner ring 8 at equal intervals in the circumferential direction. In this embodiment, eight cam surfaces 13 are formed, but the number may be changed as appropriate. A cylindrical surface 14 is formed on the inner circumferential surface of the outer ring 9. Between the inner ring 8 and the outer ring 9, rollers (hereinafter referred to as the same reference numerals as the engaging elements 10) are arranged to face each cam surface 13. Each roller 10 is held by a retainer 11.

[0033] The retainer 11 is a cylindrical member with a flange 15 extending radially inward on one axial end. Pockets 16 are formed on its cylindrical surface at equal intervals in the circumferential direction, and each roller 10 is rotatably held within the pockets 16. The flange 15 is hooked onto a stepped portion of the inner ring 8, and a retaining ring 17 is provided to restrict the axial movement of the retainer 11.

[0034] Between each cam surface 13 and cylindrical surface 14, a wedge space is formed where the radial gap between the cam surface 13 and the cylindrical surface 14 is narrower on both sides of the circumferential direction compared to the central part. The radial gap in the central part is wider than the diameter of the roller 10, while on both sides of the central part the radial gap is narrower than the diameter of the roller 10. The retainer 11 is movable in the circumferential direction between an engaged position in which the roller 10 engages with the cam surface 13 formed on the outer circumference of the inner ring 8 and the cylindrical surface 14 formed on the inner circumference of the outer ring 9, and a released position in which this engagement is released.

[0035] The centering spring 12 is an elastic member that is prevented from rotating by the inner ring 8 and the retainer 11 so as to elastically hold the retainer 11 in the released position and rotate integrally with the inner ring 8. The centering spring 12 consists of a C-shaped annular portion 18 made by winding steel wire in a C shape, and a pair of extensions 19 that extend radially outward from both ends of the C-shaped annular portion 18.

[0036] A recess 20 and a radial groove 21 are formed on the axial end face of the inner ring 8 for holding the centering spring 12. The recess 20 is an arc-shaped groove extending along the circumferential direction. The radial groove 21 penetrates radially outward from the recess 20 to the outer circumference of the inner ring 8. A concave retainer groove 22 is formed on the axial end of the retainer 11. The radial groove 21 and the retainer groove 22 have the same circumferential width. The C-shaped annular portion 18 of the centering spring 12 is fitted into the recess 20. A pair of extensions 19 are inserted into the radial groove 21 formed in the inner ring 8 and the retainer groove 22 formed in the retainer 11.

[0037] The extension portion 19 is in contact with the inner surfaces of the radial grooves 21 at both circumferential ends and with the inner surfaces of the retainer grooves 22 at both circumferential ends. As a result, the centering spring 12 is prevented from rotating by the inner ring 8 so as to rotate integrally with the inner ring 8, and is also prevented from rotating by the retainer 11. The circumferential force acting on the contact portion between the extension portion 19 and the retainer grooves 22 elastically holds the retainer 11 in the released position.

[0038] The electromagnetic clutch 3 has the function of braking the two-way clutch 2 and comprises an electromagnet 23, an armature 24, a friction plate 25, and a separation spring 26.

[0039] The electromagnet 23 has a field core 29 with a C-shaped circumferential cross-section, comprising a cylindrical inner cylinder portion 27 and an outer cylinder portion 28 with a larger diameter than the inner cylinder portion 27, and a solenoid coil 30 wound between the inner cylinder portion 27 and the outer cylinder portion 28 of the field core 29. The axial length A of the outer cylinder portion 28 of the field core 29 is longer than the axial length B of the inner cylinder portion 27 (see Figure 2), and the axial end of the outer cylinder portion 28 protrudes slightly in the axial direction compared to the axial end of the inner cylinder portion 27.

[0040] The amount of protrusion can be appropriately determined by considering the strength of the magnetic force from the electromagnet 23 and the shape (thickness, etc.) of the armature 24 that is attracted by the electromagnet 23. For example, it can be in the range of 0.01 mm to 2 mm, preferably in the range of 0.05 mm to 1.5 mm, and more preferably in the range of 0.1 mm to 1 mm. If the amount of protrusion is less than 0.01 mm, it may not be possible to cause sufficient elastic deformation (described later) to quickly release the armature 24 from attraction, and if the amount of protrusion is greater than 2 mm, it may be difficult to obtain sufficient attraction force on the armature 24.

[0041] The armature 24 is a disc-shaped member made of a magnetic material with a through hole formed in the center. The armature 24 is positioned to face the opening end of the field core 29 from the axial direction. An annular projection 31 is formed on the surface of the armature 24 that faces the friction plate 25. This annular projection 31 is configured to bias the vicinity of the outer edge of the friction plate 25. The radial position of this annular projection 31 corresponds to the radial position of the friction surface portion 32 formed on the axial end face of the outer ring 9, which generates frictional resistance by contacting the friction plate 25.

[0042] The friction plate 25 is a disc-shaped member made of a non-magnetic material with a through hole formed in the center. Two friction plate holes 33 are formed on its surface in the circumferential direction. At the axial end of the retainer 11, retainer protrusions 34 are formed at two locations in the circumferential direction, which are inserted into the friction plate holes 33. By inserting the retainer protrusions 34 into the friction plate holes 33 from the axial direction, the friction plate 25 can move in the axial direction while being prevented from rotating relative to the retainer 11. The friction plate 25 is also positioned to block a recess 20 formed in the inner ring 8, and also functions as a retaining member for the centering spring 12 provided in this recess 20. A retaining ring 35 is provided on the inner circumferential edge of the friction plate 25, restricting the axial movement of the inner circumferential edge of the friction plate 25.

[0043] A separation spring 26 is provided between the end of the field core 29 (inner cylinder portion 27) and the armature 24, biasing the armature 24 toward the friction plate 25. An annular spring, such as a wave washer, can be used as this separation spring 26.

[0044] Case 4 is a cup-shaped member made of a non-magnetic material, which houses internal components such as a two-way clutch 2 and an electromagnetic clutch 3, and through which the input shaft 5 and output shaft 6 are inserted. An elastic member 36 is provided on the output shaft 6 side inside Case 4, which presses the two-way clutch 2 and the electromagnetic clutch 3 in the axial direction (towards the input shaft 5 side in this embodiment). As this elastic member 36, an annular spring such as a wave washer, or coil springs provided at multiple locations in the circumferential direction can be used.

[0045] Bearings 37, 38, and 39 are provided between the input shaft 5 (inner ring 8) and the case 4, between the inner ring 8 and the outer ring 9, and between the output shaft 6 (outer ring 9) and the case 4, respectively, allowing for relative rotation around the axis between them. Retaining rings 40 and 41 are provided at the input shaft end of the case 4 to prevent the bearings 37 and field core 29, which are located between the input shaft 5 and the case 4, from coming out of the case 4.

[0046] The operation of this rotational transmission device 1 will now be described. When the solenoid coil 30 is energized, the field core 29 is energized as shown in Figure 5 (see the dashed line in Figure 5), and the armature 24 is attracted to the field core 29 against the biasing force of the release spring 26. Since the axial end of the outer cylinder portion 28 of the field core 29 protrudes axially more than the axial end of the inner cylinder portion 27, the attracted armature 24 elastically deforms so that its central portion is concave toward the inner cylinder portion 27. In the attracted state of the armature 24, no pressing force acts from the armature 24 to the friction plate 25, and the friction surface portion 32 does not make frictional contact, so the outer ring 9 and the retainer 11 can rotate relative to each other around the axis. Then, the retainer 11 is rotated along with the centering spring 12 which rotates integrally with the inner ring 8, and is held in the released position by the elastic restoring force of the centering spring 12. Therefore, the roller 10 held by the retainer 11 does not engage with the cam surface 13 on the outer circumference of the inner ring 8 and the cylindrical surface 14 on the inner circumference of the outer ring 9, allowing the input shaft 5 (inner ring 8) to rotate freely in either forward or reverse direction relative to the output shaft 6 (outer ring 9).

[0047] On the other hand, when the solenoid coil 30 is de-energized, the armature 24 is released from its attraction to the inner cylinder 27 and outer cylinder 28. In the un-attracted state of the armature 24, the armature 24, biased by the release spring 26, presses against the friction plate 25, and the friction plate 25 and the friction surface 32 of the outer ring 9 against which the friction plate 25 is pressed are in frictional contact. At this time, when the input shaft 5 (inner ring 8) rotates in either forward or reverse direction, the rotational force of the input shaft 5 (inner ring 8) is transmitted to the retainer 11 from the centering spring 12 which rotates integrally with it. However, the braking force due to the frictional contact between the friction plate 25, which is prevented from rotating by the retainer 11, and the friction surface 32 acts on the retainer 11 via the friction plate 25, causing the input shaft 5 (inner ring 8) to rotate relative to the retainer 11. As a result, the retainer 11, which moves circumferentially relative to the inner ring 8, presses one of the pair of extensions 19 of the centering spring 12 circumferentially on the inner surface of the retainer groove 22, causing it to bend elastically, and thus moves circumferentially from the release position to the engagement position against the centering spring 12. When this circumferential movement reaches a predetermined angular amount, the retainer 11 reaches the engagement position, and the input shaft 5 (inner ring 8) and the output shaft 6 (outer ring 9) rotate together.

[0048] In this embodiment, the axial end of the outer cylinder portion 28 protrudes axially more than the axial end of the inner cylinder portion 27. Therefore, when the solenoid coil 30 is energized and the armature 24 is attracted to the inner cylinder portion 27 and outer cylinder portion 28 of the field core 29, the armature 24 undergoes elastic deformation. When the solenoid coil 30 is de-energized and the attraction of the armature 24 is released, the elastically deformed armature 24 returns to its original shape. As a result, the repulsive force associated with this restoration quickly releases the attraction between the inner cylinder portion 27 and outer cylinder portion 28 of the field core 29.

[0049] Conversely to this embodiment, it may also be possible to obtain a similar effect by making the axial end of the inner cylinder portion 27 protrude axially more than the axial end of the outer cylinder portion 28, thereby elastically deforming the armature 24 that is adsorbed onto the field core 29.

[0050] Furthermore, in this embodiment, an elastic member 36 is provided inside the case 4 to pre-pressure internal components such as the two-way clutch 2 and the electromagnetic clutch 3 in the axial direction, thereby minimizing the number of retaining rings required to prevent axial rattle of the internal components.

[0051] Furthermore, in this embodiment, since the input shaft 5 and the inner ring 8 are integrated, it is possible to prevent circumferential play of the input shaft 5 caused by the rotation of the inner ring 8.

[0052] Furthermore, in this embodiment, since the case 4 and friction plate 25 are made of non-magnetic material, the magnetic force of the electromagnet 23 is less likely to leak to the outside of the case 4. Therefore, sufficient attraction force of the armature 24 by the electromagnet 23 can be ensured.

[0053] In this embodiment, the input shaft 5 and inner ring 8, and the output shaft 6 and outer ring 9 are integrated into a single unit. However, in some cases, the input shaft 5 and inner ring 8, and the output shaft 6 and outer ring 9 may be constructed from separate components.

[0054] Furthermore, although the separation spring 26 and the elastic member 36 are separate components in this embodiment, the separation spring 26 may also perform the function of the elastic member 36. In this case, the separation spring 26 pre-pressures the electromagnetic clutch 3 toward the input shaft 5 and the two-way clutch 2 toward the output shaft 6, thereby suppressing axial play of the internal components of the case 4. In addition, since the elastic member 36 as a separate component is not required, costs can be reduced.

[0055] This rotational transmission device 1 can be used, for example, as a clutch in a vehicle's steer-by-wire system, as shown in Figure 6. Under normal conditions, the electromagnet 23 is energized, and the steering wheel 7 side (input shaft 5 side) and the steering device 42 side (output shaft 6 side) are not mechanically connected. However, in the event of a failure of the electromagnet 23 or other components, the input shaft 5 side and the output shaft 6 side are connected, allowing the steering wheel 7 to mechanically perform steering operations. This allows for a quick transition to manual operation in the event of a failure, thereby ensuring the operability and safety of the vehicle.

[0056] A modified example of the rotary transmission device 1 according to the first embodiment is shown in Figure 7. The basic configuration of the rotary transmission device 1 in this modified example is the same as described above, but it differs in that an elastic member 36 is provided between the field core 29 and the retaining ring 41 that prevents the field core 29 from coming out of the case 4. In Figure 7, the elastic member 36 pre-pressures the two-way clutch 2 and the electromagnetic clutch 3 toward the output shaft 6. In this configuration as well, axial rattle of the internal components of the case 4 can be suppressed.

[0057] A second embodiment of the rotary transmission device 1 according to this invention will be described with reference to Figure 8. The rotary transmission device 1 according to the second embodiment includes a two-way clutch 2 and an electromagnetic clutch 3. Internal components such as the two-way clutch 2 are housed inside a case 4. The configuration of the two-way clutch 2 and the case 4 is the same as that of the first embodiment, so a description will be omitted.

[0058] The electromagnetic clutch 3 has the function of braking the two-way clutch 2 and comprises an electromagnet 23, an armature 24, a friction plate 25, a separation spring 26, and a bearing 43.

[0059] The electromagnet 23 has a field core 29 with a C-shaped circumferential cross-section, comprising a cylindrical inner portion 27 and an outer portion 28 with a larger diameter than the inner portion 27, and a solenoid coil 30 wound between the inner portion 27 and the outer portion 28 of the field core 29. The axial end of the outer portion 28 of the field core 29 protrudes slightly in the axial direction compared to the axial end of the inner portion 27.

[0060] The amount of protrusion can be appropriately determined by considering the strength of the magnetic force from the electromagnet 23 and the shape (thickness, etc.) of the armature 24 that is attracted by the electromagnet 23. For example, it can be in the range of 0.01 mm to 2 mm, preferably in the range of 0.05 mm to 1.5 mm, and more preferably in the range of 0.1 mm to 1 mm. If the amount of protrusion is less than 0.01 mm, it is not possible to cause sufficient elastic deformation (described later) to quickly release the armature 24 from attraction, and if the amount of protrusion is greater than 2 mm, it becomes difficult to obtain sufficient attraction force on the armature 24.

[0061] The armature 24 is a disc-shaped member made of a magnetic material with a through hole formed in the center. The armature 24 is positioned to face the opening end of the field core 29 from the axial direction. An annular projection 31 is formed on the surface of the armature 24 that faces the friction plate 25. This annular projection 31 is configured to bias the vicinity of the outer edge of the friction plate 25. The radial position of this annular projection 31 corresponds to the radial position of the friction surface portion 32 formed on the axial end face of the outer ring 9, which generates frictional resistance by contacting the friction plate 25.

[0062] The friction plate 25 is a disc-shaped member made of a non-magnetic material with a through hole formed in the center. Two friction plate holes 33 are formed on its surface in the circumferential direction. At the axial end of the retainer 11, retainer protrusions 34 are formed at two locations in the circumferential direction, which are inserted into the friction plate holes 33. By inserting the retainer protrusions 34 into the friction plate holes 33 from the axial direction, the friction plate 25 can move in the axial direction while being prevented from rotating relative to the retainer 11. The friction plate 25 is also positioned to block a recess 20 formed in the inner ring 8, and also functions as a retaining member for the centering spring 12 provided in this recess 20. A retaining ring 35 is provided on the inner circumferential edge of the friction plate 25, restricting the axial movement of the inner circumferential edge of the friction plate 25.

[0063] A separation spring 26 is provided between the end of the field core 29 (inner cylinder portion 27) and the armature 24, biasing the armature 24 toward the friction plate 25. An annular spring, such as a wave washer, can be used as this separation spring 26.

[0064] The bearing 43 is a thrust bearing consisting of rollers with a cage, and has the function of enabling the armature 24 and the friction plate 25 to rotate relative to each other around the axis. This bearing 43 is housed in a circumferential groove 44 formed on the outer circumference of the side of the armature 24 that faces the friction plate 25.

[0065] When the solenoid coil 30 is energized, the armature 24 is attracted to the field core 29 against the biasing force of the separation spring 26. Since the axial end of the outer cylinder portion 28 of the field core 29 protrudes axially more than the axial end of the inner cylinder portion 27, the attracted armature 24 elastically deforms so that its central portion is concave toward the inner cylinder portion 27. In the attracted state of the armature 24, no pressing force acts from the armature 24 to the friction plate 25, and the friction surface portion 32 does not make frictional contact, so the outer ring 9 and the retainer 11 can rotate relative to each other around the axis. As a result, the retainer 11 is rotated along with the centering spring 12, which rotates integrally with the inner ring 8, and is held in the released position by the elastic restoring force of the centering spring 12. Therefore, the roller 10 held by the retainer 11 does not engage with the cam surface 13 on the outer circumference of the inner ring 8 and the cylindrical surface 14 on the inner circumference of the outer ring 9, allowing the input shaft 5 (inner ring 8) to rotate freely in either forward or reverse direction relative to the output shaft 6 (outer ring 9). In the suction state of the armature 24, the axial gap between the armature 24 and the friction plate 25 expands, but the bearing 43 is held in place by the circumferential groove 44 formed in the armature 24.

[0066] On the other hand, when the solenoid coil 30 is de-energized, the armature 24 is released from its attraction to the inner cylinder 27 and outer cylinder 28. In the un-attracted state of the armature 24, the armature 24, biased by the release spring 26, presses against the friction plate 25 via the bearing 43, and the friction plate 25 and the friction surface 32 of the outer ring 9 against which the friction plate is pressed are in frictional contact. At this time, when the input shaft 5 (inner ring 8) rotates in either forward or reverse direction, the rotational force of the input shaft 5 (inner ring 8) is transmitted to the cage 11 from the centering spring 12 which rotates integrally with it. However, the braking force due to the frictional contact between the friction plate 25, which is prevented from rotating by the cage 11, and the friction surface 32 acts on the cage 11 via the friction plate 25, causing the input shaft 5 (inner ring 8) to rotate relative to the cage 11. As a result, the retainer 11, which moves circumferentially relative to the inner ring 8, presses one of the pair of extensions 19 of the centering spring 12 circumferentially on the inner surface of the retainer groove 22, causing it to bend elastically, and thus moves circumferentially from the release position to the engagement position against the centering spring 12. When this circumferential movement reaches a predetermined angular amount, the retainer 11 reaches the engagement position, and the input shaft 5 (inner ring 8) and the output shaft 6 (outer ring 9) rotate together.

[0067] At this time, the friction plate 25 rotates along with the output shaft 6 (outer ring 9), but since a bearing 43 is provided between the armature 24 and the friction plate 25, the rotation of the friction plate 25 is not transmitted to the armature 24. Therefore, when the input shaft 5 is rotated when the electromagnet 23 is not energized, wear due to sliding between the separation spring 26 and the armature 24 can be prevented.

[0068] Furthermore, since there is no sliding at the contact point of the separation spring 26 and no wear occurs at this contact point, it becomes possible to set the load of the separation spring 26 to a higher level. As a result, the spring load of the separation spring 26 can be set so that the internal components of the case 4 do not vibrate due to axial vibration acceleration, thereby preventing axial movement of the internal components and making it possible to eliminate some retaining rings.

[0069] A third embodiment of the rotary transmission device 1 according to this invention will be described with reference to Figures 9 and 10. This rotary transmission device 1 includes a two-way clutch 2 and an electromagnetic clutch 3. Internal components such as the two-way clutch 2 are housed inside a case 4. The configuration of the two-way clutch 2 and the case 4 is the same as in the first embodiment, so a description will be omitted.

[0070] The electromagnetic clutch 3 has the function of braking the two-way clutch 2 and comprises an electromagnet 23, an armature 24, a friction plate 25, a separation spring 26, and a bearing 43.

[0071] The electromagnet 23 includes a field core 29 having a C-shaped circumferential cross-section, comprising a cylindrical inner cylinder portion 27 and an outer cylinder portion 28 with a larger diameter than the inner cylinder portion 27, and a solenoid coil 30 wound between the inner cylinder portion 27 and the outer cylinder portion 28 of the field core 29.

[0072] The armature 24 is a disc-shaped member made of a magnetic material with a through hole formed in the center. The armature 24 is positioned to face the opening end of the field core 29 from the axial direction. An annular projection 31 is formed on the surface of the armature 24 that faces the friction plate 25. This annular projection 31 is configured to bias the vicinity of the outer edge of the friction plate 25. The radial position of this annular projection 31 corresponds to the radial position of the friction surface portion 32 formed on the axial end face of the outer ring 9, which generates frictional resistance by contacting the friction plate 25.

[0073] The friction plate 25 is a disc-shaped member made of a non-magnetic material with a through hole formed in the center. Two friction plate holes 33 are formed on its surface in the circumferential direction. At the axial end of the retainer 11, retainer protrusions 34 are formed at two locations in the circumferential direction, which are inserted into the friction plate holes 33. By inserting the retainer protrusions 34 into the friction plate holes 33 from the axial direction, the friction plate 25 can move in the axial direction while being prevented from rotating relative to the retainer 11. The friction plate 25 is also positioned to block a recess 20 formed in the inner ring 8, and also functions as a retaining member for the centering spring 12 provided in this recess 20. A retaining ring 35 is provided on the inner circumferential edge of the friction plate 25, restricting the axial movement of the inner circumferential edge of the friction plate 25.

[0074] A separation spring 26 is provided between the end of the field core 29 (inner cylinder portion 27) and the armature 24, biasing the armature 24 toward the friction plate 25. An annular spring, such as a wave washer, can be used as this separation spring 26.

[0075] The bearing 43 is a thrust bearing consisting of rollers with a cage, and has the function of enabling the armature 24 and friction plate 25 to rotate relative to each other around the axis. This bearing 43 is held in a circumferential groove 44 formed on the outer circumference of the side of the armature 24 that faces the friction plate 25.

[0076] When the solenoid coil 30 is energized, the armature 24 is attracted to the field core 29 against the biasing force of the separation spring 26. In the attracted state of the armature 24, no pressing force acts from the armature 24 to the friction plate 25, and the friction surface portion 32 does not make frictional contact, so the outer ring 9 and the retainer 11 can rotate relative to each other around the axis. As a result, the retainer 11 is rotated along with the centering spring 12, which rotates integrally with the inner ring 8, and is held in the released position by the elastic restoring force of the centering spring 12. Therefore, the roller 10 held by the retainer 11 does not engage with the cam surface 13 on the outer circumference of the inner ring 8 and the cylindrical surface 14 on the inner circumference of the outer ring 9, and the input shaft 5 (inner ring 8) can rotate freely in either forward or reverse direction relative to the output shaft 6 (outer ring 9). In the state of adsorption of the armature 24, the axial gap between the armature 24 and the friction plate 25 expands, but the bearing 43 is held in place by the circumferential groove 44 formed in the armature 24.

[0077] On the other hand, when the solenoid coil 30 is de-energized, the armature 24 is released from its attraction to the inner cylinder 27 and outer cylinder 28. In the un-attracted state of the armature 24, the armature 24, biased by the release spring 26, presses against the friction plate 25 via the bearing 43, and the friction plate 25 and the friction surface 32 of the outer ring 9 against which the friction plate 25 is pressed are in frictional contact. At this time, when the input shaft 5 (inner ring 8) rotates in either forward or reverse direction, the rotational force of the input shaft 5 (inner ring 8) is transmitted to the cage 11 from the centering spring 12 which rotates integrally with it. However, the braking force due to the frictional contact between the friction plate 25, which is prevented from rotating by the cage 11, and the friction surface 32 acts on the cage 11 via the friction plate 25, causing the input shaft 5 (inner ring 8) to rotate relative to the cage 11. As a result, the retainer 11, which moves circumferentially relative to the inner ring 8, presses one of the pair of extensions 19 of the centering spring 12 circumferentially on the inner surface of the retainer groove 22, causing it to bend elastically, and thus moves circumferentially from the release position to the engagement position against the centering spring 12. When this circumferential movement reaches a predetermined angular amount, the retainer 11 reaches the engagement position, and the input shaft 5 (inner ring 8) and the output shaft 6 (outer ring 9) rotate together.

[0078] At this time, the friction plate 25 rotates along with the output shaft 6 (outer ring 9), but since a bearing 43 is provided between the armature 24 and the friction plate 25, the rotation of the friction plate 25 is not transmitted to the armature 24. Therefore, when the input shaft 5 is rotated when the electromagnet 23 is not energized, wear due to sliding between the separation spring 26 and the armature 24 can be prevented.

[0079] Furthermore, since there is no sliding at the contact point of the separation spring 26 and no wear occurs at this contact point, it becomes possible to set the load of the separation spring 26 to a higher level. As a result, the spring load of the separation spring 26 can be set to a higher level to prevent the internal components of the case 4 from vibrating due to axial vibration acceleration, thereby preventing axial movement of the internal components and making it possible to eliminate some retaining rings.

[0080] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0081] 2 2-way clutch 3. Electromagnetic clutch 4 cases 5 Input axes 6 Output shaft 8 Inner Ring 9 Outer ring 10 Engaging element (roller) 11 Cage 12 Centering spring 23 Electromagnet 24 Armature 25 Friction plate 26 Detachment spring 27 Inner cylinder 28 Outer cylinder 29 Field Core 30 Solenoid coil 36 Elastic members 43 Bearings

Claims

1. A two-way clutch (2) that switches between transmitting and interrupting rotation between the input shaft (5) and the output shaft (6), An electromagnetic clutch (3) that brakes the two-way clutch (2), A case (4) that houses the two-way clutch (2) and the electromagnetic clutch (3) inside, In a rotary transmission device equipped with, The case (4) has an elastic member (36) that presses the two-way clutch (2) and the electromagnetic clutch (3) in the axial direction, The electromagnetic clutch (3) An electromagnet (23) having a field core (29) having a circumferential cross-section that is C-shaped and includes a cylindrical inner cylinder portion (27) and an outer cylinder portion (28) that has a larger diameter than the inner cylinder portion (27), and a solenoid coil (30) wound between the inner cylinder portion (27) and the outer cylinder portion (28) of the field core (29), An armature (24) is positioned to face the opening end of the field core (29) from the axial direction, and is attracted to the field core (29) when the electromagnet (23) is energized, A friction plate (25) is positioned opposite the armature (24), A separation spring (26) biases the armature (24) toward the friction plate (25), It has, A rotational transmission device characterized in that one axial end of the inner cylinder portion (27) or the outer cylinder portion (28) of the field core (29) protrudes more in the axial direction than the other axial end.

2. The rotational transmission device according to claim 1, wherein the axial end of the outer cylinder portion (28) protrudes more in the axial direction than the axial end of the inner cylinder portion (27).

3. The rotational transmission device according to claim 1 or 2, wherein the difference in the amount of axial protrusion between the axial end of the inner cylinder portion (27) and the axial end of the outer cylinder portion (28) is within the range of 0.01 mm or more and 2 mm or less.

4. The rotational transmission device according to claim 1 or 2, further comprising a bearing (43) that enables the armature (24) and the friction plate (25) to rotate relative to each other around an axis.

5. A two-way clutch (2) that switches between transmitting and interrupting rotation between the input shaft (5) and the output shaft (6), An electromagnetic clutch (3) that brakes the two-way clutch (2), In a rotary transmission device equipped with, The electromagnetic clutch (3) An electromagnet (23) having a field core (29) having a circumferential cross-section that is C-shaped and includes a cylindrical inner cylinder portion (27) and an outer cylinder portion (28) that has a larger diameter than the inner cylinder portion (27), and a solenoid coil (30) wound between the inner cylinder portion (27) and the outer cylinder portion (28) of the field core (29), An armature (24) is positioned to face the opening end of the field core (29) from the axial direction, and is attracted to the field core (29) when the electromagnet (23) is energized, A friction plate (25) is positioned opposite the armature (24), A separation spring (26) biases the armature (24) toward the friction plate (25), It has, The bearing (43) allows relative rotation of the armature (24) and the friction plate (25) around their respective axes. A rotational transmission device characterized in that the bearing (43) is provided spaced radially outward from the separation spring (26).

6. The aforementioned two-way clutch (2) An inner ring (8) provided on one of the input shafts (5) or the output shaft (6), An outer ring (9) is provided on the shaft other than the shaft on which the inner ring (8) of the input shaft (5) or the output shaft (6) is provided, An engaging element (10) is positioned between the outer circumference of the inner ring (8) and the inner circumference of the outer ring (9), A retainer (11) is arranged to be movable in the circumferential direction between an engagement position in which the engaging element (10) is engaged with the outer circumference of the inner ring (8) and the inner circumference of the outer ring (9), and a release position in which the engagement is released. A centering spring (12) is attached to the inner ring (8) and the retainer (11) so as to be fixed to the inner ring (8) and the retainer (11) so as to be elastically held in the released position and to rotate integrally with the inner ring (8), A rotational transmission device according to claim 1 or 5, having the following features.

7. The rotational transmission device according to claim 6, wherein the input shaft (5) or the output shaft (6) and the inner ring (8) are integrally configured.

8. The rotational transmission device according to claim 1 or 5, used as a clutch for connecting both the input shaft (5) and the output shaft (6) when a steer-by-wire system fails.

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