Rotation transmission device

Abstract

This rotation transmission device comprises: a non-separation type rolling bearing (3) that supports an inner member (1) and an outer member (2) so as to be rotatable relative to each other; and a case (4) that surrounds the outer member (2) and accommodates a clutch mechanism. The clutch mechanism has: a retainer (7) that holds an engagement element (6) between the outer member (2) and the inner member (1) and moves in a circumferential direction between an engagement position and a release position; an electromagnet (9) attached to the case (4); an armature (10) that is attracted to the electromagnet (9) from a set position where the armature (10) is directly or indirectly supported in an axial direction by the inner member (1) or the outer member (2); and a separation spring (11) that biases the armature (10) toward a direction away from the electromagnet (9). The rotation transmission device further comprises an elastic member (17) that presses, between the case (4) and either one member (2) of the inner member (1) and the outer member (2), the one member (2) in the axial direction, wherein the pressing force in the axial direction based on the elastic repulsion is received by the case (4) from the one member (2) via the rolling bearing (3) and the member (1) different from the one member (2).

Description

Rotation Transmission Device

[0001] The present invention relates to a rotation transmission device that transmits and cuts off rotational torque.

[0002] A conventional rotation transmission device includes an inner member, an outer member surrounding the inner member, a non-separable rolling bearing supporting the inner member and the outer member for relative rotation, a clutch mechanism for transmitting and interrupting rotational torque between the inner member and the outer member, and a case surrounding the outer member and containing the clutch mechanism. The clutch mechanism includes an engaging element disposed between the outer member and the inner member, a cage that is circumferentially movable between an engaging position where the engaging element is held and engaged with the outer member and the inner member, and a disengaging position where the engaging element is released, an electromagnet attached to the case, an armature that is axially attracted by the electromagnet from a set position where the armature is axially supported directly or indirectly by the inner member or the outer member, and a separation spring that urges the armature away from the electromagnet. The case is generally fixed to a stationary part of another machine. The inner member or the outer member is connected to a rotating shaft of the other machine. The armature is moved axially by the magnetic attraction of the electromagnet or the biasing force of the recoil spring, and the transmission and interruption of rotational torque are switched in response to this axial movement of the armature (see, for example, Patent Documents 1 and 2).

[0003] JP 2023-45468 A JP 2023-5539 A

[0004] In rotation transmission devices such as those described in Patent Documents 1 and 2, when the outer member is press-fitted into the case, it deforms radially, making it difficult to ensure the appropriate contact relationship between the outer member and the engaging element. To avoid this, the case and outer member are not press-fitted together, but the outer member is axially positioned by the shoulder of the case and a retaining ring held in the retaining ring groove of the case. The width of the retaining ring groove formed in the case is set to a dimension that allows a margin compared to the width of the retaining ring, taking into account the dimensional tolerance of the retaining ring. This can cause the retaining ring to wobble axially relative to the retaining ring groove. Axial wobble of the retaining ring also causes the outer member to wobble axially relative to the case, resulting in an inconsistent axial position of the outer member. If the axial position of the outer member changes, the axial position of the inner member also changes via the non-separable rolling bearing, and therefore the set position of the armature, which is axially supported directly or indirectly by the inner or outer member, also changes. The set height of the separation spring that biases the armature and the axial distance between the armature and the electromagnet are dimensions based on the set position of the armature relative to the inner or outer member. These dimensions affect the responsiveness of the clutch mechanism. That is, in a structure such as the rotation transmission devices of Patent Documents 1 and 2, which uses a retaining ring groove in the case and a retaining ring fitted into it to position the outer member, rolling bearing, and inner member integrally relative to the case in the axial direction, there is a problem that the performance of the rotation transmission device is prone to variation due to axial play between the retaining ring groove and the retaining ring.

[0005] Therefore, the problem to be solved by the present invention is to suppress variations in the performance of rotation transmission devices.

[0006] In order to achieve the above object, the present invention provides a clutch mechanism comprising an inner member, an outer member surrounding the inner member, a rolling bearing supporting the inner member and the outer member so as to be rotatable relative to one another, a clutch mechanism for transmitting and interrupting rotational torque, and a case surrounding the outer member and accommodating the clutch mechanism, wherein the clutch mechanism comprises an engaging element disposed between the outer member and the inner member, a retainer disposed so as to be movable in the circumferential direction between an engaging position where the engaging element is held and the outer member is engaged with the inner member, and a releasing position where the engaging element is released, an electromagnet attached to the case, and a retainer disposed so as to be movable in the axial direction by the electromagnet from a set position where the engaging element is supported in the axial direction directly or indirectly by the inner member or the outer member. The rotation transmission device has an armature that is attracted, and a separation spring that urges the armature in a direction away from the electromagnet, and is configured to switch between transmitting and cutting off the rotational torque in accordance with axial movement of the armature by the electromagnet or the separation spring, and further includes an elastic member that is disposed between one of the inner member and the outer member and the case and presses the one of the inner member and the outer member in the axial direction, and the axial pressing force based on the elastic repulsion of the elastic member is received by the case from the one of the members via the rolling bearing and the outer member or the inner member different from the one of the members.

[0007] According to the above-described configuration 1, the axial pressing force due to the elastic repulsion of the elastic member is received by the case from either the inner member or the outer member via the rolling bearing and the outer member or the inner member different from the one member. Therefore, an axial preload is applied to each of the inner member, outer member, and other members that make up the load path, and there is no axial play between these members. Therefore, the set position of the armature supported by the inner member or outer member is constant in terms of its axial position relative to the case. In other words, the axial distance between the electromagnet attached to the case and the armature in its set position, as well as the set height of the separation spring, are constant, thereby suppressing variation in the performance of the rotation transmission device.

[0008] In the above configuration 1, a configuration 2 can be adopted in which the one member is the outer member, and the outer member is arranged in a state where it is prevented from rotating relative to the case.

[0009] According to the above configuration 2, wear of the elastic member can be avoided.

[0010] In the above configuration 2, a configuration 3 can be adopted in which the case has a fitting portion that supports the outer member radially and a groove portion that extends circumferentially at a position axially closer to the fitting portion, the outer member has a side end portion that protrudes at a position radially opposite the groove portion, and the elastic member is held in the groove portion and compressed axially by the groove portion and the side end portion of the outer member.

[0011] According to the above configuration 3, a pushing force can be generated with a simple structure in which the outer member is fitted into the case and the elastic member is fitted into the groove of the case.

[0012] In the above configuration 1, a configuration 4 can be adopted in which the one member is the inner member, and the inner member is arranged in a state where it is prevented from rotating relative to the case.

[0013] According to the above configuration 4, wear of the elastic member can be avoided.

[0014] In the above configuration 4, configuration 5 can be adopted in which the case has a tubular member surrounding the clutch mechanism and a cover member axially connected to the tubular member, and the elastic member is compressed in the axial direction by the inner member and the cover member.

[0015] According to the above-mentioned configuration 5, the above-mentioned pushing force can be generated with a simple structure in which the elastic member is sandwiched between the cover member and the inner member connected to the cylindrical member.

[0016] In the above configuration 5, a configuration 6 can be adopted in which the electromagnet has a core including a spline hole portion penetrating in the axial direction, the core is fixed to the cover member, the inner member has a spline shaft portion fitted into the spline hole portion, and the elastic member is sandwiched in the axial direction between the spline shaft portion and the cover member.

[0017] According to the above-mentioned configuration 6, the electromagnet can be attached to a predetermined position in the case by joining the cylindrical member and the cover member, and the spline hole portion of the core can be engaged with the spline shaft portion of the inner member to prevent the inner member from rotating relative to the case.

[0018] In any one of the above configurations 1 to 6, a configuration 7 can be adopted in which another rolling bearing is further provided that supports the outer member or the inner member different from the one member and the case so that they can rotate freely relative to each other, and the axial pushing force is applied to the case from the other rolling bearing.

[0019] According to this configuration 7, the above-mentioned pressing force can be applied to the case by utilizing another rolling bearing that supports an outer member or an inner member different from one member relative to the case.

[0020] In any one of the above configurations 1 to 7, a configuration 8 can be adopted, in which an intermediate shaft member is connected to the outer member so as to be rotatable together with the outer member about the same axis, the inner member has a center hole portion that accommodates one axial end side of the intermediate shaft member, and the intermediate shaft member has a hollow joint portion extending in the axial direction at a position radially opposite the center hole portion and the outer member.

[0021] According to the above-mentioned configuration 8, it is possible to connect the rotating shaft of another machine with the joint portion of the intermediate shaft member to rotate the intermediate shaft member, outer member, and rotating shaft integrally, while the intermediate shaft member reduces the axial length of the outer member, thereby reducing the overall length of the rotation transmission device.

[0022] In any one of the above configurations 1 to 8, a configuration 9 can be adopted in which the clutch mechanism is provided so as to transition to a state in which the rotational torque can be transmitted when the electromagnet is excited.

[0023] According to the above configuration 9, it is possible to make the rotation transmission device an excitation actuation type.

[0024] In any one of the above configurations 1 to 8, a configuration 10 can be adopted in which the clutch mechanism is provided so as to transition to a state in which the rotational torque can be transmitted when the electromagnet is not excited.

[0025] According to the above configuration 10, a rotation transmission device of the non-excitation operation type can be obtained.

[0026] In any one of the above configurations 1 to 10, a configuration 11 can be adopted in which the inner member or the outer member is connected to a rotating shaft provided in a drive system or steering device of a vehicle, a ship, or a construction machine.

[0027] As described above, by adopting the above configuration 1, the present invention can suppress variations in the performance of the rotation transmission device.

[0028] 1 is an enlarged view of the vicinity of the elastic member shown in FIG. 1; FIG. 3 is a cross-sectional view showing a rotation transmission device according to a second embodiment of the present invention; FIG. 4 is a cross-sectional view showing a V-V line in FIG. 4; FIG. 5 is a cross-sectional view showing a rotation transmission device according to a third embodiment of the present invention; FIG. 6 is a cross-sectional view showing a rotation transmission device according to a fourth embodiment of the present invention;

[0029] A rotation transmission device according to a first embodiment of the present invention will be described with reference to the accompanying drawings, FIGS. 1 to 3. FIG.

[0030] The rotation transmission device shown in Figures 1 and 2 comprises an inner member 1, an outer member 2 surrounding the inner member 1, a rolling bearing 3 arranged between the inner member 1 and the outer member 2, a clutch mechanism for transmitting and interrupting rotational torque, a case 4 surrounding the outer member 2 and accommodating the clutch mechanism, and another rolling bearing 5 arranged between the outer member 2 and the case 4.

[0031] Here, the direction along the central axis of relative rotation of the inner member 1 and the outer member 2 is referred to as the "axial direction," and the direction perpendicular to that central axis is referred to as the "radial direction." Furthermore, the circumferential direction centered on that central axis is referred to as the "circumferential direction." Furthermore, in the description of this first embodiment, one axial direction will be simply referred to as the "right side" in FIG. 1 , and the other axial direction opposite to the one axial direction will be simply referred to as the "left side" in FIG. 1 .

[0032] The inner member 1 is connected to a rotating shaft 100 provided in another machine. The case 4 is fixed to a stationary part 101 provided in the other machine. The outer member 2, which is either the inner member 1 or the outer member 2, is fitted into the case 4 in a state where it is prevented from rotating in the circumferential direction relative to the case 4.

[0033] Other machines incorporating this rotation transmission device are, for example, steering devices installed in vehicles, ships, or construction machinery, where the rotating shaft 100 is, for example, the rotating shaft of a steering wheel, and the stationary part 101 is, for example, the body of a vehicle or the housing of a reaction motor installed in the steering device.

[0034] The inner member 1 is a rigid body that can behave as a single unit in any of the axial, radial, and circumferential directions. The outer member 2 is also a rigid body that can behave in a similar manner. The inner and outer members may be formed of a single member or a combination of multiple members, as appropriate.

[0035] The rolling bearing 3 and the other rolling bearing 5 each have an inner ring 3a, 5a, an outer ring 3b, 5b, and a plurality of rolling elements 3c, 5c arranged between the inner ring 3a, 5a and the outer ring 3b, 5b. Each rolling bearing 3, 5 is a non-separable radial bearing capable of bearing axial loads in both directions, and in the illustrated example, each is configured as a deep groove ball bearing. Axial displacement of the inner member 1 and the outer member 2 relative to each other is prevented by the plurality of rolling elements axially engaging the non-separable inner and outer rings.

[0036] The inner member 1 has, seamlessly and integrally, a first bearing seat 1a corresponding to the inner ring 3a, a plurality of cam surfaces 1b, a central shaft portion 1c protruding to the right beyond the cam surface 1b, a second bearing seat 1d corresponding to the inner ring 5a, a joint portion 1e that meshes with the rotating shaft 100, and a recess 1f recessed to the left between the central shaft portion 1c and the cam surface 1b.

[0037] The first bearing seat 1a is shaped to fit into the inner diameter surface of the inner ring 3a and abut against the right end face of the inner ring 3a in the axial direction. The second bearing seat 1d is shaped to fit into the inner diameter surface of the inner ring 5a and abut against the left end face of the inner ring 5a in the axial direction. The first bearing seat 1a is located to the left of the multiple cam surfaces 1b, and the second bearing seat 1d is located to the right of the multiple cam surfaces. The multiple cam surfaces 1e are located in a portion that protrudes radially higher toward the outer member 2 than the first bearing seat 1a and the second bearing seat 1d, and a recess 1f is formed on the right side surface of the protruding portion. The joint portion 1e is a spline hole portion that opens to the left. The rotating shaft 100 is spline-fitted into the joint portion 1e.

[0038] The outer member 2 has, seamlessly and integrally, a bearing seat 2a corresponding to the outer ring 3b, a cylindrical surface 2b extending around the entire circumference, an outer diameter surface 2c that fits into the case 4, and a keyway 2d that is recessed radially from the outer diameter surface 2c. The outer member 2 is a ring that is open to the right and left. The bearing seat 2a of the outer member 2 fits into the outer diameter surface of the outer ring 3b and is shaped to abut against the left side surface of the outer ring 3b in the axial direction.

[0039] The clutch mechanism includes a cam surface 1b formed on the outer periphery of the inner member 1, a cylindrical surface 2b formed on the inner periphery of the outer member 2, an engaging element 6 disposed between the cam surface 1b and the cylindrical surface 2b, a retainer 7 that holds the engaging element 6, a centering spring 8 that is prevented from rotating by the inner member 1 and the retainer 7, an electromagnet 9 attached to the case 4, an armature 10 that is disposed axially movably at a position axially facing the electromagnet 9, a separation spring 11 that biases the armature 10 in a direction away from the electromagnet 9, and a connecting plate 12 that prevents the armature 10 from rotating relative to the retainer 7. A retaining ring 13 for axially positioning the electromagnet 9 is attached to the inner periphery of the case 4. A retaining ring 14 for axially positioning the armature 10 and the connecting plate 12, and a retaining ring 15 for axially positioning the retainer 7 are attached to the outer periphery of the inner member 1.

[0040] The case 4 is a shell including a cylindrical portion 4a that surrounds the outer member 2 and the clutch mechanism, and is fixed to a stationary portion 101 of another machine, thereby becoming a part that belongs to the stationary system. The case 4 is cup-shaped and has a cylindrical portion 4a that opens to the left and a bottom portion 4b that closes the right end of the cylindrical portion 4a, which are integrated into one seamless piece.

[0041] The bottom portion 4b includes a bearing seat 4c corresponding to the outer ring 5b. The cylindrical portion 4a has, seamlessly and integrally, a fitting portion 4d that radially supports the outer diameter surface portion 2c of the outer member 2, a keyway portion 4e that is radially recessed from the fitting portion 4d, a groove portion 4f that extends circumferentially at a position adjacent to the left of the fitting portion 4d, and an outer flange portion 4g that is axially fastened to the stationary portion 101.

[0042] The bearing seat 4c of the case 4 is shaped to fit against the outer diameter surface of the outer ring 5b and to abut against the right side surface of the outer ring 5b in the axial direction.

[0043] The fitting portion 4d extends to a position to the right of the outer diameter surface portion 2c of the outer member 2. The fitting portion 4d and the outer diameter surface portion 2c are not press-fitted together. The fit between the fitting portion 4d and the outer diameter surface portion 2c is set to be a transition fit or a clearance fit.

[0044] As shown in Figure 2, the key grooves 4e, 2d extend in the axial direction. A parallel key 16 is inserted between the key grooves 4e, 2d. This prevents the outer member 2 from rotating relative to the case 4. Each of the key grooves 4e, 2d opens to the left. The key groove 4e intersects with the groove 4f shown in Figure 1. The anti-rotation structure of the outer member 2 relative to the case 4 can also be changed to another joint structure that does not provide a radial interference between the outer member 2 and the case 4, such as a spline fit.

[0045] The groove 4f holds an elastic member 17. The elastic member 17 is compressed in the axial direction by the outer member 2 and the groove 4f, generating a pushing force in the axial direction. A rightward pushing force Fi based on the elastic repulsion of the elastic member 17 is always applied to the side end 2e of the outer member 2.

[0046] The elastic member 17 is an annular spring that extends a finite length in the circumferential direction. The inner diameter of the elastic member 17 is smaller than that of the fitting portion 4d. The elastic member 17 is wavy and vibrates axially at a constant frequency in the circumferential direction. For example, a C-shaped wave washer can be used as this elastic member 17.

[0047] As shown in Figure 3, the outer diameter surface and the outer diameter side of the left side surface of the elastic member 17 are received in the groove 4f. There is an axial gap between the right side surface of the elastic member 17 and the groove 4f. The inner diameter side of the elastic member 17 protrudes radially from the groove 4f, and the right side surface of this protruding portion contacts the side end portion 2e of the outer member 2. The side end portion 2e of the outer member 2 is located radially opposite the groove 4f and protrudes leftward from the fitting portion 4d.

[0048] 1 , the entire right side surface of the outer member 2 faces axially into the annular space g formed between the cylindrical portion 4a and the inner member 1. Because the annular space g is provided, the rightward pushing force Fi is not applied from the right side surface of the outer member 2 to other parts within the case 4, but is applied from the bearing seat 2a of the outer member 2 to the outer ring 3b of the rolling bearing 3, from the outer ring 3b to the inner ring 3a via multiple rolling elements 3c, from the inner ring 3a to the first bearing seat 1a of the inner member 1, from the second bearing seat 1d of the inner member 1 to the inner ring 5a of another rolling bearing 5, from the inner ring 5a to the outer ring 5b via multiple rolling elements 5c, and from the outer ring 5b to the bearing seat 4c of the case 4 as a rightward pushing force Fo. In other words, the rightward pushing force Fi based on the elastic repulsion of the elastic member 17 ultimately becomes a pushing force Fo and is received by the case 4. In this way, a load path is configured that passes in this order from the elastic member 17 through the outer member 2, the rolling bearing 3, the inner member 1, and the other rolling bearing 5. Therefore, no axial play occurs between any of the members that configure this load path (between 2a and 3b, between 3b and 3c, between 3c and 3a, between 3a and 1a, between 1b and 5a, between 5a and 5c, between 5c and 5b, and between 5b and 4c).

[0049] As shown in Figure 2, the cam surface 1b of the clutch mechanism forms a wedge space between itself and the cylindrical surface 2b. This wedge space gradually narrows from the circumferential center of the cam surface 1b toward both circumferential ends. That is, the radial distance between the cam surface 1b and the cylindrical surface 2b gradually decreases from the position of the engaging element 6 in Figure 2, which is located at the circumferential center of the cam surface 1b, toward one circumferential direction (counterclockwise in Figure 2), and also gradually decreases from the position of the engaging element 6 toward the other circumferential direction (clockwise in Figure 2). A plurality of cam surfaces 1b are formed on the outer periphery of the inner member 1 at intervals in the circumferential direction. That is, a plurality of wedge spaces are formed, and an engaging element 6 is disposed in each wedge space.

[0050] As the cage 7 rotates relative to the inner member 1, the engaging elements 6 engage with the cylindrical surface 2b and the cam surface 1b, transmitting rotational torque between the inner member 1 and the outer member 2. The engaging elements 6 are formed in the shape of cylindrical rollers.

[0051] The cage 7 is an annular member in which a plurality of pockets for accommodating the engaging elements 6 are formed at intervals in the circumferential direction. The engaging elements 6 are in circumferential contact with the cage 7, so that their circumferential position relative to the cam surface 1b is restricted and they are forcibly rotated together with the cage 7. The inner flange of the cage 7 is supported radially by the inner member 1. Axial movement of the cage 7 is restricted by a snap ring 15 attached to the inner member 1 so as to be located to the left of the inner flange of the cage 7, and a step of the inner member 1 located to the right of the inner flange of the cage 7.

[0052] The cage 7 can move coaxially in the circumferential direction relative to the inner member 1 between a predetermined engagement position and a release position. The engagement position is a position where the engaging elements 6 are moved circumferentially from the circumferential center of the cam surface 1b to engage with the cam surface 1b and the cylindrical surface 2b. The release position is a position where the engaging elements 6 are moved toward the circumferential center of the cam surface 1b to release the engagement of the engaging elements 6 with the cam surface 1b and the cylindrical surface 2b.

[0053] Although the cam surface 1b is formed by a single plane in the above example, the cam surface may be formed by multiple surfaces or a single curved surface. Furthermore, although the cylindrical surface 2b is formed on the outer member 2 in the above example, it is also possible to form a cylindrical surface on the inner member and a cam surface on the inner periphery of the outer member. Furthermore, sprags may be used as the engaging elements, and the tilting position of the sprags may be controlled by the relative rotation of the cage.

[0054] The centering spring 8 is a spring member that elastically holds the cage 7 in the released position and transmits the rotational torque of the inner member 1 to the cage 7. As shown in Fig. 2, the centering spring 8 is composed of a C-shaped annular portion 8a formed by winding a steel wire in a C shape, and a pair of extension portions 8b that extend radially outward from both ends of the C-shaped annular portion 8a.

[0055] The recess 1f of the inner member 1 is composed of an arcuate groove portion extending in the circumferential direction and radial groove portions extending from both circumferential ends of the arcuate groove portion to the outer periphery of the inner member 1. The C-shaped annular portion 8a of the centering spring 8 is fitted into the arcuate groove portion of the recess 1f. The pair of extension portions 8b are inserted into the radial groove portion of the recess 1f, with their tips protruding from the radial groove portion of the recess 1f. The tips of the pair of extension portions 8b are inserted into engagement groove portions 7a formed in the annular portion on the right side of the cage 7. The radial groove portion of the recess 1f and the engagement groove portion 7a of the cage 7 have the same circumferential width, and the extension portions 8b can contact both circumferential ends of the radial groove portion of the recess 1f and both circumferential ends of the engagement groove portion 7a of the cage 7, respectively. As a result, the centering spring 8 is prevented from rotating by the inner member 1 so as to rotate integrally with the inner member 1, and is also prevented from rotating by the retainer 7. Furthermore, the centering spring 8 applies a circumferential spring force from its extension 8b to the engagement groove 7a of the retainer 7, thereby elastically holding the retainer 7 in the released position.

[0056] 1, the centering spring 8 is restricted by the connecting plate 12 so as not to slip out of the recess 1f. The axial movement of the connecting plate 12 is restricted by a retaining ring 14 located to the right of the connecting plate 12 and a step of the inner member 1 located to the left of the connecting plate 12.

[0057] The connecting plate 12 is prevented from rotating by the cage 7 and the armature 10. The connecting plate 12 is axially inserted into an engaging window 10a formed in the armature 10, has an engaging protrusion that fits into a notch formed on the right side of the cage 7, and has a well-known structure that can engage with the notch of the cage 7 and the engaging window 10a of the armature 10 in the circumferential direction at the engaging protrusion, and this engagement allows the connecting plate 12 to move circumferentially integrally with the cage 7, and also moves circumferentially integrally with the armature 10 over the entire range of the armature 10's axial reciprocating stroke.

[0058] It is also possible to omit the connecting plate 12 and employ a rotation prevention structure in which the flange of the armature or cage prevents the centering spring from escaping from the recess, and the protrusion of the cage is inserted axially into the engagement hole in the armature. It is also possible to provide the connecting plate and the spring retainer member that prevents the centering spring from escaping separately.

[0059] The armature 10 is an annular body slidably fitted onto the outer periphery of the inner member 1. The armature 10 is elastically held in a predetermined set position (the position shown in FIG. 1) by a separation spring 11, and is magnetically attracted from that set position by energizing the electromagnet 9. The set position is set at a position where the armature 10 butts against a retaining ring 14 located to the left of the armature 10 in the axial direction. The armature 10 is indirectly supported in the axial direction by the inner member 1 via the retaining ring 14. Although an example has been shown in which the axial movement of the connecting plate 12 is restricted and the set position is set using the retaining ring 14, the set position can also be set by attaching a retaining ring for setting the set position separate from the retaining ring 14 to the inner member, or by setting the set position at the abutment position between the armature and the cage, which restricts axial movement relative to the inner member, or by providing the inner member with an outer circumferential shoulder that directly supports the armature in the axial direction and setting the set position at the abutment position between the outer circumferential shoulder and the armature.

[0060] The electromagnet 9 includes an annular core 9a with a C-shaped cross section that opens axially toward the armature 10, and a solenoid coil 9b wound around the core 9a. The core 9a is a bobbin made of a ferromagnetic material that functions as a yoke. The outer periphery of the core 9a is fitted into the cylindrical portion 4a, thereby positioning the electromagnet 9 radially. Axial movement of the electromagnet 9 relative to the case 4 is restricted by a bottom portion 4b located to the right of the core 9a and a retaining ring 13 located to the left of the core 9a. The bottom portion 4b also includes a recess 4d that circumferentially engages with a protrusion 9c formed on the core 9a. The circumferential engagement between the protrusions 4b and 9c prevents the electromagnet 9 from rotating relative to the case 4. The electromagnet 9 switches from a non-excited state to an excited state when current is applied to the solenoid coil 9b. When the electromagnet 9 enters the excited state, a magnetic circuit is generated that magnetically attracts the armature 10 through the core 9a and the armature 10.

[0061] The bottom portion 4b is formed with a through hole for passing a lead wire that supplies power to the solenoid coil 58. A rubber grommet is attached to the bottom portion 4b to fill the gap between the through hole and the lead wire.

[0062] The separation spring 11 is disposed between the armature 10 and the left end face of the core 9a. The separation spring 11 stores energy when the armature 10 is moved rightward from the set position. The separation spring 11 is, for example, a metal spring in the shape of a wave washer or a coil. The armature 10 has a recess formed therein for holding the separation spring 11 between the armature 10 and the core 9a. The biasing force of the separation spring 11 pushing the armature 10 leftward is always smaller than the rightward biasing force Fi of the elastic member 17.

[0063] When the electromagnet 9 is in a de-energized state, the retainer 7 is held in the released position by the spring force of the centering spring 8, the engaging element 6 is held in a position where it does not engage with the cylindrical surface 2b and the cam surface 1b, and the armature 10 is held in the set position by the separation spring 11 and a retaining ring 14 supported by the inner member 1. Therefore, regardless of whether the inner member 1 rotates forward or backward relative to the case 4 and the outer member 2, the rotational torque is not transmitted between the inner member 1 and the outer member 2, and the inner member 1 and the outer member 2 can rotate freely relative to each other. In other words, this rotation transmission device is in a disengaged state in which the transmission of rotational torque between the inner member 1 and the outer member 2 is interrupted.

[0064] In this disengaged state, when the inner member 1 and the outer member 2 rotate relative to each other, the rotation is transmitted to the cage 7 via the centering spring 8, and the cage 7 and the engaging member 6 rotate together. The armature 10, which is prevented from rotating by the cage 7, also rotates together. For example, when the inner member 1 rotates forward relative to the outer member 2 from the disengaged state, the inner member 1 and the cage 7, which are elastically connected by the centering spring 8, both rotate forward, the engaging member 6 held by the cage 7 also moves in the forward rotation direction, and the armature 10, which is prevented from rotating relative to the cage 7, also rotates forward together with the cage 7.

[0065] In a disengaged state in which the inner member 1 and the outer member 2 rotate relative to each other, when the electromagnet 9 is switched from a de-energized state to an energized state, the armature 10 is magnetically attracted against the elasticity of the separation spring 11 and is attracted to the left end surface of the core 9a. The frictional resistance acting on the attracting surfaces of the core 9a and the armature 10 becomes the rotational resistance of the retainer 7. This frictional resistance is preset to a value greater than the spring force of the centering spring 8. As a result, the rotation of the retainer 7 is delayed relative to the inner member 1, and the centering spring 8, which is prevented from rotating by the inner member 1, is elastically deformed, causing the retainer 7 to rotate relative to the inner member 1 and moving the engaging element 6 toward the narrow portion of the wedge space between the cylindrical surface 2b and the cam surface 1b. As a result, the retainer 7 moves to the engaged position, causing the engaging element 6 to engage with the cylindrical surface 2b and the cam surface 1b. As a result, the rotational torque of the inner member 1 is transmitted to the outer member 2 via the engaging elements 6. In other words, this rotation transmission device switches to an engaged state in which rotational torque is transmitted between the inner member 1 and the outer member 2.

[0066] In this engaged state, when the electromagnet 9 switches from an excited state to a de-excited state, the biasing force of the separation spring 11 moves the armature 10 away from the electromagnet 9, and the armature 10 is quickly returned to the set position. Furthermore, when the armature 10 moves away from the electromagnet 9, the spring force of the centering spring 8 causes the retainer 7 to rotate relative to the inner member 1 in the opposite direction to that during engagement. As a result, the retainer 7 moves to the release position, and the engagement of the engaging elements 6 with the cylindrical surface 2b and cam surface 1b is released. This returns the rotation transmission device to the disengaged state.

[0067] In this way, the clutch mechanism switches between a state in which rotational torque can be transmitted and a state in which it can be cut off between the inner member 1 and the outer member 2 in response to the magnetic attraction of the electromagnet 9 or the axial movement of the armature 10 due to the biasing force of the separating spring 11, and is provided so as to transition to a state in which rotational torque can be transmitted between the inner member 1 and the outer member 2 when the electromagnet 9 is excited. In this rotation transmission device, since the outer member 2 is prevented from rotating relative to the case 4, when the electromagnet 9 is excited, the rotational torque of the inner member 1 is received by the stationary case 4, stopping the rotation of the inner member 1 and also stopping the rotation of the rotating shaft 100 input to the inner member 1.

[0068] The assembly of this rotation transmission device can be roughly divided into a process of assembling a unit centered around the inner member 1 and a process of housing it in the case 4.

[0069] In the unit assembly process, the inner member 1 is assembled from the left side and from the right side. When assembling from the left side, first, the cage 7 is inserted into the inner member 1 from the left side, and a retaining ring 15 is attached to position the cage 7 in the axial direction. Then, the inner ring 3a of the rolling bearing 3 is fitted into the first bearing seat 1a. On the other hand, when assembling from the right side, first, the centering spring 8 is inserted into the inner member 1 from the right side and accommodated in the recess 1f. Then, the connecting plate 12 is inserted into the inner member 1 from the right side and combined with the cage 7. In this state, a retaining ring 14 is attached to position the connecting plate 12 in the axial direction.

[0070] In the process of housing the unit in the case 4, first, the outer ring 5b of the other rolling bearing 5 is fitted into the bearing seat 4c of the case 4. Then, the electromagnet 9 is placed on the bottom 4b of the case 4, and the retaining ring 13 is attached to the cylindrical portion 4a to position the electromagnet 9 axially. The unit is then inserted through the left opening of the cylindrical portion 4a. The unit can be inserted with the retainer 7 holding the engaging element 6 and the armature 10, which is inserted through the inner member 1 from the right, holding the separation spring 11. By inserting the unit, the second bearing seat 1d of the inner member 1 is fitted into the inner ring 5a of the other rolling bearing 5, positioning the unit axially relative to the case 4, compressing the separation spring 11 in the axial direction, and the armature 10, biased by the separation spring 11, coming into contact with the retaining ring 14, and positioned in a set position indirectly supported axially by the inner member 1.

[0071] After the unit is inserted, the outer member 2 is fitted into the fitting portion 4d of the case 4. Here, as shown in FIGS. 1 and 3, the outer member 2 is positioned in the axial direction so that its side end 2e protrudes leftward beyond the fitting portion 4d of the case 4 and faces the groove 4f radially, leaving a space g. After the outer member 2 is fitted, a parallel key 16 is inserted between the key grooves 4e and 2d as shown in FIG. 2. Finally, as shown in FIGS. 1 and 3, the elastic member 17 is fitted into the groove 4f. When the elastic member 17 is fitted into the groove 4f, the elastic member 17 held in the groove 4f is sandwiched axially between the side end 2e of the outer member 2 and the left side groove shoulder of the groove 4f, and the elastic member 17 is compressed in the axial direction. As a result, a rightward pushing force Fi is applied from the elastic member 17 to the side end 2e of the outer member 2, and is then transmitted sequentially via the rolling bearing 3, the inner member 1, and the other rolling bearings 5 ​​to the outer ring 5b as a rightward pushing force Fo applied to the bearing seat 4c of the case 4 and received by the bottom 4b of the case 4. Therefore, an axial preload is applied between each component on the load path from the elastic member 17 held in the groove 4f to the bearing seat 4c of the case 4. Even if, at the time the elastic member 17 is fitted into the groove 4f, a state in which axial play could occur between the components constituting the load path, in which they are misaligned in the axial direction, the outer member 2, which is movable rightward relative to the fitting portion 4d, is pushed rightward by the rightward pushing force Fi applied from the elastic member 17, and this behavior is transmitted sequentially to the rolling bearing 3, the inner member 1, and the other rolling bearings 5, thereby disallowing axial play between the components constituting the load path and establishing a series of load paths. In this way, there is no axial rattle between the members that make up the load path, and therefore the outer member 2 and the inner member 1 are positioned at fixed axial positions relative to the case 4, which is a stationary part relative to the inner member 1 and the outer member 2. Therefore, the retaining ring 14 on the inner member 1 that determines the set position of the armature 10 is also positioned at a fixed axial position, and therefore the axial set height of the separating spring 11 relative to the armature 10 in the set position and the axial distance (magnetic gap) between the armature 10 in the set position and the electromagnet 9 attached to the case 4 are also determined to be constant.The axial compression allowance of the elastic member 17 may be set appropriately so as to ensure the rightward pushing forces Fi and Fo based on the elastic rebound of the elastic member 17, taking into account the cumulative dimensional tolerances between the various components in the axial direction.

[0072] As described above, this rotation transmission device comprises the inner member 1, the outer member 2 surrounding the inner member 1, the rolling bearing 3 supporting the inner member 1 and the outer member 2 so that they can rotate freely relative to each other, a clutch mechanism that transmits and cuts off rotational torque, and a case 4 that surrounds the outer member 2 and houses the clutch mechanism, in which the clutch mechanism comprises an engaging element 6 arranged between the outer member 2 and the inner member 1, a retainer 7 arranged to be movable circumferentially between an engaging position that holds the engaging element 6 and engages the outer member 2 with the inner member 1, and a releasing position that releases the engagement, an electromagnet 9 attached to the case 4, an armature 10 that is attracted in the axial direction by the electromagnet 9 from a set position indirectly supported in the axial direction by the inner member 1, and a separating spring 11 that urges the armature 10 away from the electromagnet 9, and is configured to switch between transmitting and cutting off rotational torque in accordance with the axial movement of the armature 10 by the electromagnet 9 or the separating spring 11.

[0073] This rotation transmission device further includes an elastic member 17 disposed between the outer member 2 (one of the inner and outer members 1 and 2) and the case 4, and pressing the outer member 2 (one of the members) in the axial direction. Axial pressing forces Fi and Fo based on the elastic repulsion of the elastic member 17 are received by the case 4 from the outer member 2 (one of the members) via the rolling bearing 3 and the inner member 1, which is different from the one of the members. This eliminates axial play between the members 1 to 6, such as the outer member 2 and the inner member 1, that form the load path for the pressing forces Fi and Fo. Therefore, the set position of the armature 10, which is indirectly supported by the inner member 1, is constant in terms of its axial position relative to the case 4. In other words, this rotation transmission device constantizes the axial distance between the electromagnet 9 and the armature 10 in the set position and the set height of the separation spring 11, thereby suppressing variations in performance, particularly variations in the responsiveness of the clutch mechanism to electromagnetic switching control of the electromagnet 9.

[0074] Furthermore, in this rotation transmission device, one of the components, the outer member 2, is positioned in a state where it is prevented from rotating relative to the case 4, so that relative rotation between the outer member 2 and the case 4 that would wear out the elastic member 17 does not occur, and wear on the elastic member 17 can be avoided.

[0075] Furthermore, in this rotation transmission device, the case 4 has a fitting portion 4d that radially supports the outer member 2 and a groove portion 4f that extends circumferentially at a position axially away from the fitting portion 4d, the outer member 2 has a side end portion 2e that protrudes at a position radially opposite the groove portion 4f, and the elastic member 17 is held in the groove portion 4f and compressed axially by the groove portion 4f and the side end portion 2e of the outer member 2, so that a pressing force Fi can be generated with a simple structure in which the outer member 2 is fitted into the case 4 and the elastic member 17 is fitted into the groove portion 4f of the case 4.

[0076] In addition, this rotation transmission device further includes another rolling bearing 5 that supports an inner member 1 different from the one member and the case 4 so that they can rotate freely relative to each other, and an axial pressing force Fo based on the elastic rebound of the elastic member 17 is applied to the case 4 from the other rolling bearing 5, so that the axial pressing force Fo can be applied to the case 4 by utilizing the other rolling bearing 5 that supports the inner member 1 relative to the case 4.

[0077] Furthermore, this rotation transmission device is configured to transition to a state in which rotational torque can be transmitted between the inner member 1 and the outer member 2 when the electromagnet 9 is excited, thereby making it an excitation-operated rotation transmission device.

[0078] A rotation transmission device according to a second embodiment of the present invention is shown in Figures 4 and 5. The following description will focus on the differences from the first embodiment. In the description of this second embodiment, one axial direction will be simply referred to as the "left" side in Figure 4, and the other axial direction opposite to the one axial direction will be simply referred to as the "right" side in Figure 4.

[0079] 4 and 5, the rotation transmission device employs the inner member 21 as one of the inner member 21 and the outer member 22. The inner member 21 is arranged in a state where it is prevented from rotating in the circumferential direction relative to the case 23.

[0080] The case 23 has a cylindrical member 24 that surrounds the clutch mechanism and a cover member 25 that is connected to the cylindrical member 24. The cylindrical member 24 has a shape that opens to the left and opens to the right with a larger diameter than the left opening. The cover member 25 has a flat, straight plate shape in the radial direction. The cylindrical member 24 and the cover member 25 are each made of a single, seamless member. The right end face of the cylindrical member 24 and the left end face of the cover member 25 are fastened in the axial direction by a plurality of male thread members 26. The joint between the cover member 25 and the cylindrical member 24 is sealed with a sealant 27.

[0081] Another rolling bearing 28 is disposed between the outer member 22 and the cylindrical member 24. The outer member 22 has an outer peripheral bearing seat 22a corresponding to the inner ring 28a of the other rolling bearing 28. The outer peripheral bearing seat 22a is shaped to fit against the inner diameter surface of the inner ring 28a and to abut against the right side surface of the inner ring 28a in the axial direction. The cylindrical member 24 has a bearing seat 24a corresponding to the outer ring 28b of the other rolling bearing. The bearing seat 24a of the cylindrical member 24 is shaped to fit against the outer diameter surface of the outer ring 28b and to abut against the left side surface of the outer ring 28b in the axial direction. A retaining ring 29 is attached to the inner periphery of the cylindrical member 24. Axial movement of the outer ring 28b is restricted by the bearing seat 24a of the cylindrical member 24 and the retaining ring 29.

[0082] The outer member 22 has a shape that opens to the left and has a larger diameter opening to the right than the left opening. In order to arrange the rolling bearing 30 and the other rolling bearing 29 radially opposite to each other, the bearing seat 22b on the inner periphery of the outer member 22 is positioned radially opposite to the outer peripheral bearing seat 22a. A retaining ring 31 is attached to the inner periphery of the outer member 22. Axial movement of the outer ring of the rolling bearing 30 is restricted by the bearing seat 22b of the outer member 22 and the retaining ring 31.

[0083] The outer member 22 has an outer peripheral bearing seat 22a and a joint portion 22c that protrudes leftward beyond the bearing seat 22b. The joint portion 22c is connected to a rotating shaft 100 of another machine by spline fitting.

[0084] The electromagnet 32 ​​is fixed to the cover member 25. As a fixing means, for example, an appropriate means such as welding or adhesive between the core 32a and the cover member 25 can be used. A retaining ring for restricting the leftward movement of the electromagnet 32 ​​is not required.

[0085] The armature 33 is set in a position where it is directly supported in the axial direction by the right end face of the outer member 22. A friction surface portion 22d is formed on the right end face of the outer member 22, and transmits rotational torque between the outer member 22 and the armature 33. The retaining ring 35, which restricts rightward movement of the connecting plate 34, is not subjected to the leftward axial load from the armature 33.

[0086] The core 32a of the electromagnet 32 ​​has a spline hole 32c that penetrates axially between the left and right side surfaces of the core 32a on the radially opposite side from the side on which the solenoid coil 32b is wound. The central axis of the inner member 21 is a spline shaft 21a that is fitted into the spline hole 32c. The inner member 21 is arranged in a state where it can move leftward relative to the case 23 via the spline hole 32c of the core 32a, which is fixed to the cover member 25 of the case 23, but is prevented from rotating relative to the case 23. At a position to the left of the rolling bearing 30, there is no other portion that hinders the leftward movement of the inner member 21, and an axial gap is secured between the rotating shaft 100 and the outer member 22.

[0087] The spline shaft portion 21a has an open end 21b that opens toward the right. The open end 21b holds an elastic member 36. A compression coil spring is used as the elastic member 36. The elastic member 36 is compressed in the axial direction by the open end 21b of the spline shaft portion 21a and the cover member 25. The elastic member 36 pushes the inner member 21 to the left. The leftward pushing force based on the elastic rebound of the elastic member 36 is received by the cylindrical member 24 of the case 23, passing from the inner member 21 through the rolling bearing 30, the outer member 22, and another rolling bearing 28 in that order.

[0088] When the electromagnet 32 ​​is in a de-energized state, the armature 33 is supported at a set position away from the electromagnet 32 ​​by the separation spring 37, and is pressed against the friction surface portion 22d of the outer member 22 by the biasing force of the separation spring 37. Therefore, it is possible to transmit the rotational torque of the outer member 22 between the armature 33 and the friction surface portion 22d of the outer member 22. When the outer member 22 is stationary in a de-energized state, the retainer 38 is elastically held by the centering spring 40 in a release position where the engaging element 39 is not engaged with the cylindrical surface 22e of the outer member 22 and the cam surface 21c of the inner member 21. When the outer member 22 rotates, the armature 33 is rotated therewith, and the connecting plate 34 and retainer 38, which are prevented from rotating relative to the armature 33, are also rotated together. That is, the retainer 38 is rotated relative to the inner member 21, and the engaging element 39 is directed toward the narrow portion of the wedge space between the cylindrical surface 22e of the outer member 22 and the cam surface 21c of the inner member 21. As a result, the retainer 38 moves to the engaging position, and the engaging element 39 held by the retainer 38 is engaged with the cam surface 21c of the inner member 21 and the cylindrical surface 22e of the outer member 22. This switches the rotation transmission device to an engaged state in which rotational torque is transmitted between the inner member 21 and the outer member 22.

[0089] In this engaged state, when the electromagnet 32 ​​is switched from a de-energized state to an energized state, the armature 33 is magnetically attracted to the right against the biasing force of the separation spring 37. As a result, the armature 33 is moved to the right, compressing the separation spring 37 in the axial direction and weakening the pressure of the armature 33 against the friction surface portion 22d, eventually resulting in a state in which rotational torque cannot be transmitted between the armature 33 and the friction surface portion 22d. In this state, the spring force of the centering spring 40 causes the retainer 38 to rotate relative to the inner member 21 in the opposite direction to the engaged state. As a result, the retainer 38 moves to the release position, disengaging the engaging element 39 from the cylindrical surface 22e and the cam surface 21c. This switches the rotation transmission device to a disengaged state in which rotational torque transmission between the inner member 1 and the outer member 2 is interrupted. While the electromagnet 32 ​​is in an excited state in the disengaged state, regardless of whether the outer member 22 rotates forward or backward relative to the case 23 and the inner member 21, the rotational torque is not transmitted between the inner member 21 and the outer member 22, and the inner member 21 and the outer member 22 can rotate freely relative to each other.

[0090] When the electromagnet 32 ​​is switched to a non-excited state in this disengaged state, the armature 33 is returned to the set position by the biasing force of the separation spring 37 .

[0091] In this way, the clutch mechanism is provided to switch between a state in which rotational torque can be transmitted and a state in which it can be cut off between the inner member 21 and the outer member 22 in response to the magnetic attraction of the electromagnet 32 ​​or the axial movement of the armature 33 due to the biasing force of the separating spring 11, and to transition to a state in which rotational torque can be transmitted between the inner member 21 and the outer member 22 when the electromagnet 32 ​​is not excited. In this rotation transmission device, the inner member 21 is prevented from rotating relative to the case 23, so that when the electromagnet 32 ​​is not excited, the rotational torque of the outer member 22 is received by the stationary case 23, stopping the rotation of the outer member 22 and also stopping the rotation of the rotating shaft 100 input to the outer member 22.

[0092] The assembly of this rotation transmission device can be roughly divided into a process of assembling a subunit centered on the inner member 21, a process of assembling a connecting unit between the subunit and the outer member 22, and a process of housing it in the case 23.

[0093] The sub-unit assembly process differs from the unit assembly process of the first embodiment only in that the rolling bearing 30 is not attached to the inner member 21 .

[0094] In the process of assembling the connecting unit, first, the rolling bearing 30 is inserted from the opening on the right side of the outer member 22, and the outer ring of the rolling bearing 30 is fitted into the bearing seat 22b of the outer member 22. Then, the retaining ring 31 is attached to the outer member 22 to position the rolling bearing 30 in the axial direction. Then, the sub-unit is inserted from the opening on the left side of the outer member 22, and the inner ring of the rolling bearing 30 is fitted into the inner member 21. The sub-unit is inserted with the engaging element 39 held by the cage 38.

[0095] In the process of accommodating the bearing in the case 23, the other rolling bearing 28 is inserted from the right opening of the cylindrical member 24, and the outer ring 28b of the other rolling bearing 28 is fitted into the bearing seat 24a of the cylindrical member 24. Thereafter, a retaining ring 29 is attached to the cylindrical member 24 to position the other rolling bearing 28 in the axial direction. Thereafter, the connecting unit is inserted from the right opening of the cylindrical member 24, and the inner ring 28a of the other rolling bearing 28 is fitted into the outer peripheral bearing seat 22a of the outer member 22. Thereafter, a separation spring 37 is placed on the armature 33 passed through the inner member 21 from the right, an elastic member 36 is held by the open end 21b of the inner member 21, and a sealing material 27 is placed in the cylindrical member 24. Thereafter, the cover member 25 to which the electromagnet 32 ​​has been fixed is placed on the right end face of the cylindrical member 24, and the spline hole portion 32c of the core 32a is fitted into the spline shaft portion 21a of the inner member 21. Thereafter, the cover member 25 and the cylindrical member 24 are fastened together in the axial direction with the male screw member 27.

[0096] At the start of this fastening, the elastic member 36 is in an uncompressed state, with its right end protruding axially from the open end 21b. As the fastening of the cover member 25 and the tubular member 24 progresses, the elastic member 36 is sandwiched axially between the open end 21b and the cover member 25 and compressed, and the separation spring 37 is sandwiched axially between the armature 33, which is directly supported on the outer member 22 (friction surface portion 22d), and the core 32a and compressed. As a result, a pushing force to the left is applied from the elastic member 36 to the open end 21b of the inner member 21, and is then passed through the rolling bearing 30, the outer member 22, and the other rolling bearing 28 to the outer ring 28b, the bearing seat 24a of the tubular member 24, and is received by the tubular member 24 of the case 23. Even if, at the time when the tightening of the cover member 25 begins, there is a state in which axial play is possible between the components that form the load paths (between 24 and 28, between 28 and 22, between 22 and 30, between 30 and 21), causing them to shift axially relative to each other, the inner member 21, which can move to the left relative to the outer member 22, tubular member 24, etc., is pushed to the left by the leftward pushing force applied by the elastic member 36, and this behavior is transmitted in sequence to the rolling bearing 30, the outer member 22, and the other rolling bearings 28, thereby creating a state in which no axial play is permitted between the components that form the load paths, and a series of load paths is established. As a result, an axial preload is applied between the members 21, 30, 22, and 24 on the load path from the elastic member 36 to the bearing seat 24a of the case 23, the connecting unit is positioned in the axial direction relative to the case 23, and the armature 33, pressed against the friction surface 22d by the biasing force of the separation spring 37, is disposed at a set position where it is directly supported in the axial direction by the outer member 22. Therefore, the axial set height of the separation spring 37 relative to the armature 33 in the set position and the axial distance (magnetic gap) between the armature 33 in the set position and the electromagnet 32 ​​attached to the case 23 are also determined to be constant.

[0097] As described above, this rotation transmission device includes the elastic member 36, which is disposed between the inner member 21 (one of the inner and outer members 21 and 22) and presses the inner member 21 (one of the members) in the axial direction while being disposed between the inner member 21 and the case 23. The axial pressing force based on the elastic repulsion of the elastic member 36 is received by the case 23 from the inner member 21 (one of the members) via the rolling bearing 30 and the outer member 22, which is different from the inner member 21 (one of the members). As a result, an axial preload is applied to each of the members constituting the load path, such as the inner member 21 and the outer member 22, and there is no axial play between these members. Therefore, the set position of the armature 33 supported by the outer member 22 is constant in terms of its axial position relative to the case 23. In other words, in this rotation transmission device, the axial distance between the electromagnet 32 ​​and the armature 33 at the set position and the set height of the separation spring 37 are constant, thereby suppressing variation in the performance of the rotation transmission device.

[0098] Furthermore, in this rotation transmission device, one of the components, the inner member 21, is positioned in a state where it is prevented from rotating relative to the case 23, so that relative rotation between the inner member 21 and the case 23 that would wear out the elastic member 36 does not occur, and wear out of the elastic member 36 can be avoided.

[0099] Furthermore, this rotation transmission device has a case 23 which includes a tubular member 24 that surrounds the clutch mechanism, and a cover member 25 that is axially connected to the tubular member 24, and the elastic member 36 is compressed in the axial direction by the inner member 21 and the cover member 25, so that the aforementioned pressing force can be generated with a simple structure in which the elastic member 36 is sandwiched between the cover member 25 connected to the tubular member 24 and the inner member 21.

[0100] Furthermore, this rotation transmission device has a core 32a including a spline hole portion 32c through which the electromagnet 32 ​​passes in the axial direction, the core 32a is fixed to the cover member 25, the inner member 21 has a spline shaft portion 21a fitted into the spline hole portion 32c, and the elastic member 36 is sandwiched axially between the spline shaft portion 21a and the cover member 25, so that the electromagnet 32 ​​can be attached to a predetermined position in the case 23 by joining the cylindrical member 24 and the cover member 25, and the spline hole portion 32c of the core 32a can be engaged with the spline shaft portion 21a of the inner member 21 to prevent the inner member 21 from rotating relative to the case 23.

[0101] In addition, this rotation transmission device is provided with another rolling bearing 28 that supports an outer member 22 different from the one member and the case 23 so that they can rotate freely relative to each other, and since an axial pressing force is applied to the case 23 from the other rolling bearing 28, the aforementioned pressing force can be applied to the case 23 by utilizing the other rolling bearing 28 that supports the outer member 2 relative to the case 23.

[0102] Furthermore, this rotation transmission device can be made into a non-excitation operation type rotation transmission device by providing a clutch mechanism that transitions to a state in which rotational torque can be transmitted between the inner member 21 and the outer member 22 when the electromagnet 32 ​​is not excited.

[0103] A rotation transmission device according to a third embodiment of the present invention is shown in Fig. 6. Note that the third embodiment is a further modification of the second embodiment, and therefore only the differences from the second embodiment will be described here.

[0104] The rotation transmission device shown in FIG. 6 includes a friction member 41 adjacent to the right of the friction surface portion 22d of the outer member 22. The friction member 41 is disposed between the armature 42 and the outer member 22 so as to be able to move in the axial direction. The friction member 41, like the armature 42, is in the shape of an annular plate. The connecting plate 43 has an engaging protrusion inserted into the engaging window portion 41a of the friction member 41, and is prevented from rotating relative to the friction member 41. The biasing force of the separation spring 37 is transmitted to the friction member 41 via the armature 42. The armature 42 is indirectly supported in the axial direction by the outer member 22 via the friction member 41. Contact between the opposing surfaces of the friction member 41 and the armature 42 is maintained by the biasing force of the separation spring 37. The set position of the armature 42 relative to the friction surface portion 22d is shifted to the right by the thickness of the friction member 41 compared to the second embodiment, but the thickness of the armature 42 is made thinner than in the second embodiment by that amount. Therefore, the axial distance between the armature 42 and the electromagnet 32 ​​in the set position and the set height of the separation spring 37 relative to the armature 42 in the set position are unchanged from the second embodiment. When the armature 42 is magnetically attracted to the right, the friction member 41 is no longer pressed against the friction surface portion 22d of the outer member 22, and the state switches to the disengaged state described above.

[0105] The spring force of the centering spring 40 is set to be weaker than in the second embodiment, making the centering spring 40 more susceptible to elastic deformation. Therefore, it is unnecessary to apply a strong circumferential load to the centering spring 40 when the electromagnet 32 ​​is de-energized, and it is not necessary to employ a thick, rigid iron armature as in the second embodiment. Therefore, the friction member 41 is formed of a material softer than the iron armature 42, thereby increasing the friction coefficient of the surface of the friction member 41 to a value higher than that of the surface of the armature 42. Therefore, the friction resistance between the friction member 41 and the friction surface portion 22d is higher than in the second embodiment, making it less likely for the friction surface portion 22d and the friction member 41 to slide against each other in the circumferential direction. Therefore, when the electromagnet 32 ​​is de-energized, the rotational torque of the outer member 22 can be reliably transmitted to the connecting plate 43.

[0106] A rotation transmission device according to a fourth embodiment of the present invention is shown in Fig. 7. Note that the fourth embodiment is a further modification of the third embodiment, and therefore only the differences from the third embodiment will be described here.

[0107] The rotation transmission device shown in FIG. 7 includes an intermediate shaft 51 connected to an outer member 50. The intermediate shaft 51 is a seamless, hollow shaft extending axially. It has a male coupling portion 51a at its left end on its outer periphery and a coupling portion 51b extending hollowly on its inner periphery. The outer member 50 has a female coupling portion 50a corresponding to the male coupling portion 51a. The connection between the male coupling portion 51a and the female coupling portion 50a enables the intermediate shaft 51 to rotate coaxially with the outer member 50. The inner member 52 has a center hole 52a on its left end surface that accommodates the right end of the intermediate shaft 51. The male coupling portion 51a and the female coupling portion 50a can be structured using, for example, spline fitting or a key. A retaining ring 53 is attached to the outer member 50 at a position adjacent to the left of the intermediate shaft 51. Axial movement of the intermediate shaft member 51 is restricted by a snap ring 53 and the outer ring of the rolling bearing 30. The coupling portion 51b (see also FIG. 4 below) is a portion used for connection to a rotating shaft 100 of another machine, and is a functional portion corresponding to the coupling portion 22c in the outer member of the second and third embodiments. Most of the axial length of the coupling portion 51b is inserted into the center hole portion 52a of the inner member 52, and is located radially opposite the center hole portion 52a and the outer member 50. By this insertion amount, the axial lengths of the outer member 50 and the case 54 are shortened compared to those of the second and third embodiments.

[0108] In this way, this rotation transmission device has the intermediate shaft member 51 connected to the outer member 50 so as to be rotatable together with the outer member 50 about the same axis, the inner member 52 having a center hole portion 52a that accommodates the right end side (one axial end side) of the intermediate shaft member 51, and the intermediate shaft member 51 having a joint portion 51b that extends hollowly in the axial direction at a position radially opposite the center hole portion 52a and the outer member 50.As a result, it is possible to connect the joint portion 51b of the intermediate shaft member 51 to a rotating shaft 100 provided in another machine and rotate the intermediate shaft member 51, outer member 50, and rotating shaft 100 together, while reducing the axial length of the outer member 50 compared to the second and third embodiments, thereby reducing the overall length of the rotation transmission device.

[0109] A rotation transmission device according to a fifth embodiment of the present invention is shown in Figures 8 and 9. Note that the fifth embodiment is a further modification of the second embodiment, and therefore only the differences from the second embodiment will be described here.

[0110] The rotation transmission device shown in FIGS. 8 and 9 is of an excitation-operated type that transitions to a state in which rotational torque can be transmitted between the inner member 61 and the outer member 62 when the electromagnet 32 ​​is excited.

[0111] The inner member 61 has a cylindrical surface 61a of the clutch mechanism, and the outer member 62 has a cam surface 62a of the clutch mechanism. The cam surface 62a has an arcuate shape.

[0112] An engaging projection 64 a formed on the right side of the retainer 64 is inserted into the engaging window 63 a of the armature 63 .

[0113] The C-shaped annular portion 65a of the centering spring 65 is fitted into an arc-shaped groove 64b formed on the right side of the retainer 64. A pair of extension portions of the centering spring 65 extending from both ends of the C-shaped annular portion 65a toward the outer member 62 are inserted into radial groove portions formed on the right side surface of the retainer 64 and the right side surface of the outer member 62, respectively.

[0114] The outer member 62 has an inner peripheral shoulder 62b adjacent to the left of the cage 64 that holds the engaging element 66 on the cam surface 62a. Axial movement of the cage 64 is restricted by the inner peripheral shoulder 62b of the outer member 62 and the armature 63. When the armature 63 and an end face 64c of the cage 64 abut against each other and the cage 64 abuts against the inner peripheral shoulder 62b of the outer member 62, the armature 63 is indirectly supported in the axial direction by the outer member 62 via the cage 64. The position of the armature 63 in this state (the state shown in FIG. 8) is the set position. When the electromagnet 32 ​​is in a de-energized state, the armature 63 is urged toward the set position by the separation spring 67.

[0115] In assembling this rotation transmission device, a subunit is assembled in which the retainer 64, centering spring 65, and engaging element 66 are arranged from the opening on the right side of the outer member 62 with the outer member 62 at the center.

[0116] When the electromagnet 32 ​​is in a de-energized state, the retainer 64 is held in a released position by the spring force of the centering spring 65, the engaging element 66 is held in a position where it does not engage with the cylindrical surface 61 a and the cam surface 62 a, and the armature 63 is held in a set position by the separation spring 67 and the retainer 64 supported by the outer member 62. Therefore, regardless of whether the outer member 62 rotates in the forward or reverse direction relative to the inner member 61, the rotational torque is not transmitted between the inner member 61 and the outer member 62, and the inner member 61 and the outer member 62 can rotate freely relative to each other. In other words, this rotation transmission device is in a disengaged state in which the transmission of rotational torque between the inner member 61 and the outer member 62 is interrupted.

[0117] In this disengaged state, when the inner member 61 and the outer member 62 rotate relative to each other, the rotation is transmitted to the retainer 64 via the centering spring 65, and the retainer 64 and the engaging member 62 rotate together. The armature 63, which is prevented from rotating by the retainer 64, also rotates together. For example, when the outer member 62 rotates forward relative to the inner member 61 from the disengaged state, the outer member 62 and the retainer 64, which are elastically connected by the centering spring 65, both rotate forward, and the engaging member 66 also moves forward together with the retainer 64 and the outer member 62, and the armature 63, which is prevented from rotating relative to the retainer 64, also rotates forward together with the retainer 64.

[0118] In a disengaged state in which the inner member 61 and the outer member 62 rotate relative to each other, when the electromagnet 32 ​​switches from a de-energized state to an energized state, the armature 63 is magnetically attracted against the elasticity of the separation spring 67 and is attracted to the left end face of the electromagnet 32. Due to frictional resistance at the attracted portion, the rotation of the retainer 64 is delayed relative to the outer member 62, elastically deforming the centering spring 65, which is prevented from rotating by the outer member 62. This causes the retainer 64 to rotate relative to the outer member 62, and moves the engaging element 66 toward the narrow portion of the wedge space between the cylindrical surface 61 a of the inner member 61 and the cam surface 62 a of the outer member 62. As a result, the retainer 64 moves to the engaged position, engaging the engaging element 66 with the cylindrical surface 61 a and the cam surface 62 a. This allows the rotational torque of the outer member 62 to be transmitted to the inner member 61 via the engaging element 66. That is, the rotation transmission device switches to an engaged state in which rotational torque is transmitted between the inner member 61 and the outer member 62 .

[0119] In this engaged state, when the electromagnet 32 ​​switches from an excited state to a de-excited state, the biasing force of the separation spring 37 moves the armature 63 away from the electromagnet 32, and the armature 63 is quickly returned to the set position. Furthermore, when the armature 63 moves away from the electromagnet 32, the spring force of the centering spring 65 causes the retainer 64 to rotate relative to the outer member 62 in the opposite direction to that during engagement. As a result, the retainer 64 moves to the release position, and the engagement of the engaging element 66 with the cylindrical surface 61 a of the inner member 61 and the cam surface 62 a of the outer member 62 is released. This returns the rotation transmission device to the disengaged state.

[0120] In this way, the clutch mechanism is configured to switch between a state in which rotational torque can be transmitted between the inner member 61 and the outer member 62 and a state in which it can be cut off in response to the axial movement of the armature 63 due to the magnetic attraction of the electromagnet 32 ​​or the biasing force of the recoil spring 37, and to transition to a state in which rotational torque can be transmitted between the inner member 61 and the outer member 62 when the electromagnet 32 ​​is excited.

[0121] The rotation transmission device in each embodiment is exemplified as being suitable for use in performing steering lock on a steering device, but it can also be applied to other uses, such as a rotating shaft provided in the drive system of a vehicle, ship, or construction machinery.

[0122] In the above-described embodiments, the case is assumed to belong to a stationary system, but if the rotation angle in the rotation transmission system of the other machine is limited to a range of less than 360°, it is also possible to not connect the case to the stationary system of the other machine, but to connect a case that is prevented from rotating with one of the members to a first rotating shaft of the rotation transmission system, and to connect a second rotating shaft of the rotation transmission system to an inner member or outer member different from the one member. The allowable range of rotation angle is a range in which the lead wires of the electromagnet will not be broken due to relative rotation between the case and the inner member or outer member different from the one member.

[0123] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. Therefore, the scope of the present invention is defined by the claims rather than the above description, and it is intended to include all modifications within the meaning and scope of the claims.

[0124] 1, 21, 52, 61 Inner member 2, 22, 50, 62 Outer member 2e Side end portion 3, 30 Rolling bearing 4, 23, 54 Case 4d Fitting portion 4f Groove portion 5, 28 Other rolling bearing 6, 39, 66 Engagement piece 7, 38, 64 Cage 9, 32 Electromagnet 10, 33, 42, 63 Armature 11, 37, 67 Separation spring 17, 36 Elastic member 21a Spline shaft portion 24 Cylindrical member 25 Cover member 32a Core 32c Spline hole portion 51 Intermediate shaft member 51b Joint portion 52a Center hole portion 100 Rotating shaft

Claims

1. A rotation transmission device comprising an inner member, an outer member surrounding the inner member, a rolling bearing supporting the inner member and the outer member so that they can rotate relative to one another, a clutch mechanism for transmitting and interrupting rotational torque, and a case surrounding the outer member and accommodating the clutch mechanism, wherein the clutch mechanism has an engaging element disposed between the outer member and the inner member, a retainer disposed so as to be movable in the circumferential direction between an engaging position where the engaging element is held and engages the outer member with the inner member, and a releasing position where the engaging element is released, an electromagnet attached to the case, an armature that is attracted in the axial direction by the electromagnet from a set position where the armature is supported in the axial direction directly or indirectly by the inner member or the outer member, and a separating spring that urges the armature away from the electromagnet, and is configured to switch between transmitting and interrupting the rotational torque in accordance with the axial movement of the armature by the electromagnet or the separating spring, a rotation transmission device further comprising an elastic member disposed between one of the inner and outer members and the case and pressing the one of the members in the axial direction, wherein the axial pressing force based on the elastic rebound of the elastic member is received by the case from the one of the members via the rolling bearing and the outer member or the inner member different from the one of the members.

2. A rotation transmission device according to claim 1, wherein said one member is said outer member, and said outer member is arranged in a state where it is prevented from rotating relative to said case.

3. A rotation transmission device as set forth in claim 2, wherein the case has a fitting portion that radially supports the outer member and a groove portion that extends circumferentially at a position axially away from the fitting portion, the outer member has a side end portion that protrudes at a position radially opposite the groove portion, and the elastic member is held in the groove portion and is compressed axially between the groove portion and the side end portion of the outer member.

4. A rotation transmission device according to claim 1, wherein said one member is said inner member, and said inner member is arranged in a state where it is prevented from rotating relative to said case.

5. A rotation transmission device as set forth in claim 4, wherein the case has a cylindrical member surrounding the clutch mechanism and a cover member axially connected to the cylindrical member, and the elastic member is compressed in the axial direction by the inner member and the cover member.

6. A rotation transmission device as set forth in claim 5, wherein the electromagnet has a core including a splined hole portion that penetrates in the axial direction, the core is fixed to the cover portion, the inner member has a splined shaft portion that is fitted into the splined hole portion, and the elastic member is sandwiched in the axial direction between the splined shaft portion and the cover member.

7. A rotation transmission device as claimed in any one of claims 1 to 6, further comprising another rolling bearing that supports the outer member or the inner member different from the one member and the case so that they can rotate freely relative to each other, and the axial pushing force is applied to the case from the other rolling bearing.

8. A rotation transmission device according to any one of claims 1 to 7, comprising an intermediate shaft member connected to said outer member so as to be coaxially rotatable together therewith, said inner member having a center hole portion that accommodates one axial end of said intermediate shaft member, and said intermediate shaft member having a hollow joint portion extending axially at a position radially opposite said center hole portion and said outer member.

9. A rotation transmission device according to any one of claims 1 to 8, wherein the clutch mechanism is provided so as to transition to a state in which the rotational torque can be transmitted when the electromagnet is excited.

10. A rotation transmission device according to any one of claims 1 to 8, wherein the clutch mechanism is arranged to transition to a state in which the rotation torque can be transmitted when the electromagnet is not excited.

11. A rotation transmission device according to any one of claims 1 to 10, wherein the inner member or the outer member is connected to a rotating shaft provided in a drive system or steering device of a vehicle, ship or construction machine.

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