Reclining device

Abstract

The purpose of the invention is to more reliably suppress a phenomenon in which a Taumel-type movement is generated during reclining angle adjustment, and a seat back gradually falls down during locking.　When the reclining angle is stopped, divided gears 221 of a second disk-like gear 22 are pressed in the direction of meshing with internal teeth 10a by a cam 220 arranged at the rotation center of the divided gears 221. A rotational force that cause the divided gears 221 to rotate outward around one support pin 26 is generated in the divided gears 221, and at the same time, a pressing force causing the divided gears 221 to be pressed outward in the radial direction is generated by a cam 220. Since external teeth 221e of the divided gears 221 are engaged with the internal teeth 10a of an internal gear 10 in a state where such rotational force and pressing force are generated, backlash between both gears is also reduced.

Description

Reclining device

[0001] The present invention relates to a reclining device that is attached to a seat of a vehicle or the like and that appropriately adjusts the inclination angle of a seat back relative to a seat cushion.

[0002] Representative seat reclining device mechanisms include the so-called Taumel type and latch type. As shown in Patent Documents 1 and 2, the Taumel type has an internal gear and external gears with fewer teeth than the internal gears. The internal gear adjusts its angle by meshing with an external gear whose rotating shaft is eccentric, and the meshing of the internal and external gears maintains the reclined position. However, there is play due to the difference in the number of teeth and the amount of eccentricity. In addition, the meshing position of the internal and external gears tends to shift under load when the internal and external gears are not meshed together, so the reclined position is not maintained sufficiently, and the seat back tends to gradually collapse. To prevent this, various structures have been adopted, such as a mechanism that connects two wedge-shaped segments via a spring and engages the wedge-shaped segments when locked (see Patent Document 1), a brake mechanism known as a spring coupler device (see Patent Document 2), or an elastic member attached to the rotating shaft that biases the seat back in the returning direction (see Patent Document 2).

[0003] As shown in Patent Documents 3 and 4, the latch type includes a lock gear that has external teeth that mesh with the internal teeth of an internal gear and moves radially to lock the external teeth by meshing with the internal teeth, a guide bracket that guides the operating direction of the lock gear radially, a cam that operates the lock gear radially, and a spiral spring that is stretched between the cam and the guide bracket and rotates the cam.When reclining, the lock gear is pulled toward the center by the cam, allowing the guide bracket to rotate relative to the internal gear, while when locking, the restoring force of the spiral spring causes the cam to rotate in the opposite direction, moving the lock gear radially outward and meshing its external teeth with the internal teeth to lock it.

[0004] Japanese Patent Publication No. 63-47443 Japanese Utility Model Application Laid-Open No. 6-62852 Japanese Patent Laid-Open No. 2006-204896 Japanese Patent Laid-Open No. 2008-131983

[0005] In addition to the rattle described above, the Taumel-type seat back requires a mechanism to prevent the seat back from gradually collapsing under load. However, the prevention measures disclosed in Patent Documents 1 and 2 are both complex in structure and require dedicated locking mechanisms, such as wedge-shaped segments or brake mechanisms. Furthermore, even if the seat back is locked using the wedge-shaped segments or brake mechanisms, backlash remains between the outer and inner teeth, so the gradual collapse of the seat back cannot be fully resolved. Furthermore, rattle can occur due to the backlash. Furthermore, there is also the issue that the pressing force of the wedge-shaped segments and elastic members is insufficient to withstand the input of a large load.

[0006] The latch-type seat belts shown in Patent Documents 3 and 4 have a configuration in which the external teeth of the lock gear bite into the internal teeth of the internal gear, making it less likely for the seat back to gradually collapse and providing high strength even with a large load input. However, because the lock gears need to be slidably stacked on the guide bracket, there are problems with rattle in the stacking direction and the generation of abnormal noise. Furthermore, to ensure synchronization of multiple lock gears, more consideration needs to be given to the design than with the Taumel-type seat belt, and the structure tends to be more complicated.

[0007] The present invention has been made in consideration of the above, and its object is to provide a reclining device with a simple configuration that produces movement similar to that of a Taumel-type device when adjusting the reclining angle, while more reliably suppressing the phenomenon of the seat back gradually tilting when locked, and that exhibits high strength even when a large load is input, like a latch-type device.

[0008] In order to solve the above problems, the present invention provides a seat cushion having an internal gear connected to one of a seat cushion and a seat back, and an external gear connected to the other of the seat cushion and seat back, the external gear having external teeth with a different number of teeth that mesh with the internal teeth of the internal gear, and disposed eccentrically with respect to the internal gear, wherein the external gear has a plurality of sets of disk-shaped gears stacked in the axial direction, Each of the plurality of sets of disk-shaped gears is composed of a combination of split gears that are divided into a plurality of pieces in the circumferential direction, and the plurality of split gears have pin insertion holes formed closer to each circumferential edge than the circumferential center of each arc, and split gears whose pin insertion holes are connected to each other in the axial direction are supported axially outward of each of the plurality of sets of disk-shaped gears by support pins that are hung between a pair of guide plates arranged with the plurality of sets of disk-shaped gears therebetween, and when adjusting the reclining angle, the plurality of sets of disk-shaped gears rotate together while some of their external teeth mesh with the internal teeth of the internal gear, A recliner device is provided in which a cam is provided at the center of rotation of at least one of the disk-shaped gears, which moves the multiple split gears that make up the disk-shaped gears radially; when the reclining angle is locked, the cam rotates, generating an outward rotational force on each of the split gears, with the support pin located near one edge as the center of oscillation, and the cam exerts a radially outward pushing force, which presses a portion of the outer teeth of each of the split gears in a direction that eliminates backlash between them and the inner teeth, thereby locking the device.

[0009] It is preferable that the disk-shaped gear, with the cam arranged at the center of rotation, has a pin insertion hole near the edge on the circumferential opposite side of the pin insertion hole at the swing center, which is formed with a larger diameter than the diameter of the support pin inserted into the pin insertion hole.

[0010] It is preferable that when a large load equal to or greater than a predetermined value is input, the support pin and the split gear are deformed, and the depth of engagement between the external teeth and the internal teeth is changed, thereby receiving the load.

[0011] At least one other set of disc-shaped gears other than the disc-shaped gear at the rotation center of which the cam is arranged has an integrating member arranged at the rotation center that integrates the divided gears, which are divided into multiple pieces, into a disc-shaped form, the integrating member has engaging protrusions protruding at predetermined intervals from its outer periphery, and each of the divided gears has a protrusion notch groove on its inner periphery that engages with the engaging protrusions, and it is preferable that the disc-shaped form is maintained when the reclining angle is adjusted and when locked, and when a large load greater than a predetermined value is input, a resistance is generated by the engaging protrusions of the integrating member and the protrusion notch groove.

[0012] The pair of guide plates are provided with pin support holes for supporting each of the support pins, and it is preferable that the pin support hole corresponding to one of the two pin insertion holes formed in the split gear is formed with a diameter larger than the diameter of the support pin.

[0013] It is preferable that the split gear is divided into three in the circumferential direction. It is preferable that a pair of the disk-shaped gear with the cam disposed at the rotation center and a pair of the disk-shaped gear with the integrated member disposed at the rotation center are stacked in the axial direction.

[0014] According to this invention, when adjusting the reclining angle, the internal gear's internal teeth mesh with the external teeth of the disk-shaped external gear, causing rotation. This allows adjustment to any angle, and when adjustment is stopped, the external teeth mesh with the internal teeth at a predetermined angle. When this occurs, a cam positioned at the rotation center of the divided gears of a set of disk-shaped gears presses the divided gears in a direction that meshes with the internal teeth. A rotational force that tends to rotate each divided gear outward around a single support pin is generated in each divided gear, while a pressing force is generated by the cam that pushes each divided gear radially outward. With this rotational force and pressing force generated, the external teeth of the divided gear mesh with the internal teeth of the internal gear, increasing the number of meshings between the external and internal teeth compared to when adjusting the reclining angle. Furthermore, the outward rotational force and pressing force also eliminate backlash between the external and internal teeth. In other words, there is a backlash-free meshing between the external teeth of the disk-shaped external gear and the internal teeth of the internal gear, suppressing rattle caused by backlash and effectively reducing rattle when locked. Therefore, while the movement is similar to that of the Taumel type during normal angle adjustment, when locked, the external teeth and internal teeth mesh without backlash, which is excellent at suppressing the phenomenon of the seat back gradually reclining. Furthermore, because the multiple split gears rotate and mesh when locked, they mesh more easily than the lock gears used in conventional latch types, which move linearly in the radial direction. Furthermore, the multiple split gears are not dedicated to locking, but function as external teeth when adjusting the angle, simplifying the configuration and facilitating design.

[0015] The external gear, a disk-shaped gear, is composed of a combination of multiple split gears, each supported by a support pin. The gearbox has multiple sets of these disk-shaped gears. Therefore, when a large load exceeding a predetermined level is applied, the gearbox exhibits high load-bearing characteristics due to the resistance of the support pins, the increased depth of meshing between the external teeth of each split gear and the internal teeth, and the resistance to deformation of each split gear.

[0016] FIG. 1 is an exploded perspective view of a recliner according to one embodiment of the present invention. FIG. 2(a) is a diagram illustrating the configuration of a first disk-shaped gear, and FIG. 2(b) is a diagram illustrating the configuration of a second disk-shaped gear. FIG. 3 is an enlarged view illustrating the relationship between the second disk-shaped gear and a cam. FIG. 4 is a diagram illustrating a state in which the split gear of the second disk-shaped gear is pulled toward the center by the L-shaped protrusion of the cam. FIG. 5 is a diagram illustrating the movement of the split gear of the second disk-shaped gear when locked. FIGS. 6(a) to 6(c) are diagrams illustrating the movement of the first disk-shaped gear when a load is applied. FIG. 7 is a diagram illustrating the experimental method for the load-bearing capacity experiment. FIGS. 8(a) and 8(b) are diagrams illustrating the structure of a test specimen used in the load-bearing capacity experiment. FIG. 9 is a graph illustrating the results of the load-bearing capacity experiment. 10(a) to (c) are photographs showing the deformation state of the split gears corresponding to the first disk-shaped gears in the Example and Comparative Examples 1 and 2 after the experiment, where (a) is a photograph for the Example, (b) is a photograph for Comparative Example 1, and (c) is a photograph for Comparative Example 2.

[0017] The present invention will be described in further detail below with reference to the embodiments shown in the drawings. Figures 1 to 6 show a reclining device 1 according to one embodiment of the present invention. The reclining device 1 is attached between a seat cushion frame and a seat back frame, and is configured with an internal gear 10 and an external gear 20. For example, the internal gear 10 is connected to the seat cushion side, and the external gear 20 is connected to the seat back side.

[0018] The internal gear 10 is formed in a ring shape, and internal teeth 10a are formed on its inner surface. The external gear 20, which rotates relative to the internal gear 10, is supported by a pair of guide plates 23, 24 ("first guide plate 23" and "second guide plate 24"), support pins 25, 26, etc., which will be described later. The heads of the first guide plate 23 and the support pins 25, 26 are located on one axial side of the internal gear 10. To ensure space for these components, the internal gear 10 is integrated with the end face 11b of the peripheral wall portion 11a of the concave first bearing plate 11 by welding after the first guide plate 23 and the support pins 25, 26 are assembled. This leaves a predetermined space between the bottom face 11d of the concave first bearing plate 11 and the internal gear 10, allowing the above-mentioned components to be arranged. The concave first bearing plate 11 may be formed by using a ring that forms the peripheral wall portion 11a and a plate member that forms the bottom surface 11d as separate members, with the ring welded to the internal gear 10 in advance, and then assembling the first guide plate 23 and the like, and then welding them to the plate member.

[0019] The external gear 20 includes multiple sets of disk-shaped gears 21, 22, two sets in this embodiment. Each of the disk-shaped gears 21, 22 is configured by combining gear segments 211, 221, each divided into multiple segments in the circumferential direction, and stacked in the axial direction. In this embodiment, as shown in FIGS. 1 and 2 , each disk-shaped gear 21, 22 includes three gear segments 211, 221, each divided into three segments evenly spaced in the circumferential direction. As described below, the gear segments 211, 221 must be displaced radially outward during locking and shock absorption. Therefore, although two segments are possible, three segments are more adaptable to various input force directions. The gear segments 211, 221 must rotate together within the internal gear 10 when adjusting the reclining angle. However, if the gear segments are divided into four or more segments, it may be difficult to operate them together. Therefore, although a three-division configuration is preferable, the scope of the present invention also includes two-division, four-division or more divisions as long as they operate smoothly.

[0020] Each of the split gears 211, 221 has two pin insertion holes 211a, 211b, 221a, 221b formed therethrough in the thickness direction. The pin insertion holes are formed closer to the circumferential edges 211c, 211d, 221c, 221d than the circumferential center of the arc of each of the split gears 211, 221. By forming the pin insertion holes closer to the circumferential edges 211c, 211d, 221c, 221d, one of the gears displaces in the rotational direction around the pin insertion holes 211a, 211b, 221a, 221b formed on the other side.

[0021] External teeth 211e, 221e are formed on the arc-shaped outer peripheries of the split gears 211, 221, respectively. These external teeth 211e, 221e mesh with the internal teeth 10a of the internal gear 10. When three split gears 211, 221 are combined, the total number of teeth of the external teeth 211e, 221e is smaller than the number of teeth of the internal teeth 10a. In addition, the axes CL1, CL2 of the disk-shaped gears 21, 22 formed by the combination of the split gears 211, 221 and the internal gear 10 are eccentric, resulting in a Taumel-type combination of internal and external teeth. Note that, because the disk-shaped gears 21, 22 mesh with the internal gear 10 while rolling, the external teeth 211e, 221e and the internal teeth 10a are preferably cycloidal teeth, which have a larger root area than an involute tooth profile.

[0022] First and second guide plates 23, 24 are disposed adjacent to and axially outward from the two sets of disk-shaped gears 21, 22. That is, the two sets of disk-shaped gears 21, 22 are sandwiched between a pair of first and second guide plates 23, 24 that face each other in the axial direction. The outer diameters of the first and second guide plates 23, 24 are larger than the inner diameters of the disk-shaped gears 21, 22 and the internal gear 10. When the disk-shaped gears 21, 22 are sandwiched between the first and second guide plates 23, 24, the disk-shaped gears 21, 22 are positioned inside the internal gear 10, and the surfaces of the first and second guide plates 23, 24 near their outer edges 23a, 24a face and rotate in contact with the surface near the inner edge 10b of the internal gear 10.

[0023] Shaft insertion holes 23b, 24b are formed in the centers of the first and second guide plates 23, 24, through which the angle adjustment shaft 30 serving as the rotation axis is inserted, and pin support holes 231a, 231b, 241a, 241b are provided circumferentially around the shaft insertion holes 231a, 231b, 241a, 241b. These pin support holes 231a, 231b, 241a, 241b correspond to the positions of the pin insertion holes 211a, 211b, 221a, 221b formed in the split gears 211, 221, respectively, and communicate with each other in the axial direction. Thus, one support pin 25 can be inserted through the pin support holes 231a, 241a and the pin insertion holes 211a, 221a, which communicate with each other in the axial direction, and the other support pin 26 can be inserted through the pin support holes 231b, 241b and the pin insertion holes 211b, 221b, which also communicate with each other in the axial direction.

[0024] The support pins 25, 26 have the same length and diameter. Heads 25a, 26a are provided at each end to prevent them from slipping out of the pin support holes 231a, 231b, 241a, 241b of the first and second guide plates 23, 24. One end of the heads 25a, 26a of the support pins 25, 26 may be shaped like a nut, for example. After removing the nut from the support pins 25, 26, the support pins 25, 26 are inserted into the holes in the first and second guide plates 23, 24 and the disk-shaped gears 21, 22, and the nut is then reattached to the protruding end. It is sufficient for the support pins 25, 26 to not slip out after assembly, and other retaining structures may be used instead of the heads 25a, 26a.

[0025] The pin support holes 231a, 231b, 241a, 241b formed in the first and second guide plates 23, 24 are not all the same shape. Instead, the pin support holes 231a, 241a are formed at 120-degree intervals in the circumferential direction, and the other pin support holes 231b, 241b are provided at equal intervals therebetween. The pin support holes 231a, 241a are formed with a small inner diameter that is approximately the same as the diameter of the shaft portion 25b of one support pin 25, and the one support pin 25 is inserted through each of the pin support holes 231a, 241a. The other support pin 26 is inserted through the other pin support holes 231b, 241b, but the other pin support holes 231b, 241b are formed with a larger diameter than the diameter of the shaft portion 26b of the other support pin 26, so that the other support pin 26 can be relatively displaced radially within the other pin support holes 231b, 241b. In this case, one support pin 25 cannot be displaced radially, so when the other support pin 26 is displaced, one support pin 25 becomes the center and the other support pin 26 is displaced in the rotational direction. Furthermore, during normal reclining angle adjustment, the gear segments 211, 221 of the disk-shaped gears 21, 22 are closely spaced to form a single disk, so that both support pins 25, 26 are normally positioned closest to the axis. Therefore, as shown in Figures 1 and 6(c), the other pin support holes 231b, 241b are preferably shaped so that the diameter of the portion closest to the axis is approximately the same as the diameter of the shaft portion 26b of the other support pin 26, and gradually increases circumferentially outward.

[0026] On the other hand, the two pin insertion holes 211a, 211b, 221a, 221b formed in each of the split gears 211, 221 of the two sets of disk-shaped gears 21, 22 are configured as follows: In the following, one of the two sets of disk-shaped gears 21, 22 will be referred to as the first disk-shaped gear 21 and the other as the second disk-shaped gear 22.

[0027] The pin insertion holes 211a, 211b formed in the split gear 211 of the first disk-shaped gear 21 are both the same size, and are formed with an inner diameter that is approximately the same as the diameter of the shaft portions 25b, 26b of the support pins 25, 26. When assembling, one support pin 25 is inserted into one pin insertion hole 211a so that one pin support hole 231a, 241a of the first and second guide plates 23, 24 communicates with each other, and the other support pin 26 is inserted into the other pin insertion hole 211b so that the other pin support holes 231b, 241b of the first and second guide plates 23, 24 communicate with each other. Therefore, each split gear 211 of the first disk-shaped gear 21 can be displaced in the direction of rotating outward, with the edge side through which the other support pin 26 is inserted, centered around one support pin 25, within the range of the other large-diameter pin support hole 231b, 241b of the first and second guide plates 23, 24.

[0028] The first disk-shaped gear 21 normally rotates as a unit with its three split gears 211. Therefore, a merging member 210 for merging the three gears is disposed at the rotation center of the first disk-shaped gear 21. In this embodiment, the merging member 210 is formed from the same steel as that used for the split gears 211 and is ring-shaped. The inner periphery of the annular portion 210a forms a shaft insertion hole 210b for the angle adjustment shaft 30, which serves as the rotation axis. On the outer periphery of the annular portion 210a, engagement protrusions 210c extending outward in a generally V-shape are formed at predetermined intervals in the circumferential direction at three locations corresponding to the number of split gears 211. A protrusion notch groove 211g into which the engagement protrusions 210c fit is formed at the circumferential center of the arc forming each inner periphery 211f of the three split gears 211. The inner peripheral edge 211f of the split gear 211 abuts against the outer surface of the annular portion 210a of the integrated member 210, and the projection notch groove 211g is formed in a generally elliptical shape with the inner peripheral edge 211f side open so as to embrace the outer periphery of the engaging projection 210c. Furthermore, of the circumferential edges 211c, 211d of the three split gears 211, one is a concave edge 211c and the other is a convex edge 211d, and the adjacent edges of adjacent split gears 211, 211 are arranged so that the concave edge 211c and the convex edge 211d are adjacent. The fit between the two increases friction and suppresses misalignment of the disks.

[0029] The three split gears 211 are arranged adjacent to each other so that the concave edge 211c and the convex edge 211d fit together, and the engaging protrusion 210c of the integrated member 210 is fitted into the protrusion notch groove 211g, so that the three split gears 211 take on a disk-like shape and form the first disk-shaped gear 21.

[0030] As shown in FIGS. 2B and 3, a cam 220 is disposed at the rotation center of the second disk-shaped gear 22. The cam 220 has an annular portion 220a and an L-shaped protrusion 220b extending outward from the annular portion 220a in a generally L-shaped configuration in a plan view. More specifically, the L-shaped protrusion 220b has a base portion 220b1 extending outward from the annular portion 220a by a predetermined width, and a protrusion 220b2 protruding circumferentially beyond the width of the base portion 220b1 toward the outside of the base portion 220b1. Three L-shaped protrusions 220b are formed at equal intervals in the circumferential direction, and each corresponds to one of the three split gears 221. The inner peripheral edges 221f of the three split gears 221 are formed with a radius such that the outer end faces 220b3 of the L-shaped protrusions 220b contact the inner peripheral edges 221f. On the other hand, one circumferential end side of the inner peripheral edge 221f has an inclined abutment piece 221g that extends obliquely toward the base portion 220b1 of the L-shaped protrusion 220b until it contacts the outer surface of the annular portion 220a of the cam 220. The part where the inner peripheral edge 221f and the inclined abutment piece 221g form an acute angle constitutes the protrusion engagement groove 221h.

[0031] The circumferential edges 221c, 221d of the three split gears 221 are formed so that one is a convex edge 221c and the other is a convex edge 221d, similar to the split gear 211 of the first disk-shaped gear 21, and the two fit together to prevent misalignment as disks.

[0032] When the protruding piece 220b2 of the L-shaped protrusion 220b is engaged with the protrusion engagement groove 221h, each split gear 221 is pulled toward the center (see FIG. 4). By maintaining this state, the external teeth 221e of each split gear 221 of the second disk-shaped gear 22 mesh with the internal teeth 10a of the internal gear 10 and rotate during normal reclining adjustment. As described above, the split gear 221 of the second disk-shaped gear 22 is formed with pin insertion holes 221a, 221b. Support pins 25, 26 are inserted through these pin insertion holes 221a, 221b, thereby sandwiching and integrating the split gear 221 together with the first disk-shaped gear 21 between the pair of first and second guide plates 23, 24. As a result, the split gears 221 of the second disk-shaped gear 22 and the split gears 211 of the first disk-shaped gear 21 are aligned in the axial direction, and the positions of the external teeth 211e, 221e are also the same without any radial misalignment. Therefore, during normal reclining adjustment, the first disk-shaped gear 21 and the second disk-shaped gear 22 rotate together while meshing with the internal teeth of the internal gear 10. In contrast, when the cam 220 rotates in a direction that disengages the protruding piece 220b2 of the L-shaped protrusion 220b from the protrusion engagement groove 221h, the outer end surface 220b3 of the L-shaped protrusion 220b presses against the inner peripheral edge 221f of each split gear 221 (see FIG. 5). This movement will be described in more detail below.

[0033] A hollow cam support pipe 220k is integrated with the cam 220 along the axial direction. Three notches are formed on the inner periphery of the shaft insertion hole 220c of the annular portion 220a of the cam 220, while three circumferentially extending protrusions 220k1 are formed on the cam support pipe 220k. These protrusions 220k1 fit into the notches in the annular portion 220a of the cam 220 to form an integrated structure. A cam operating member 27 is connected to the cam support pipe 220k. The cam operating member 27 has an annular portion 27a and a bent portion 27b formed by bending an end of the annular portion 27a. Three grooves 27c are formed on the inner periphery of the annular portion 27a. The cam operating member 27 is attached around the cam support pipe 220k by engaging the grooves 27c with the protrusions 220k1. The bent portion 27b of the cam operating member 27 is biased to one side by, for example, a spring member (not shown). By setting the biasing direction to the direction in which the engagement between the protruding piece 220b2 of the L-shaped protrusion 220b and the protrusion engagement groove 221h is released, a force is applied that causes the outer end surface 220b3 of the L-shaped protrusion 220b to press against the inner peripheral edge 221f of each split gear 221.

[0034] The bent portion 27b of the cam operating member 27 is provided so as to protrude outward from an arc-shaped guide hole 28a formed in a second bearing plate 28 disposed axially outward of the second guide plate 24, and is biased by the spring member as described above to be displaced along the arc-shaped guide hole 28a. The second bearing plate 28 is integrated with the second guide plate 24 by welding or the like.

[0035] The angle adjustment shaft 30 has a first shaft portion 32 that protrudes from one end of the flange 31 and is rotatably inserted into the bearing hole 11c of the first bearing plate 11. A second shaft portion 33 that protrudes from the other end of the flange 31 is rotatably inserted into the shaft insertion hole 23b of the first guide plate 23, the shaft insertion hole 210b of the integrated member 210 of the first disk-shaped gear 21, the shaft insertion hole 220c of the cam 220 of the second disk-shaped gear 22, the shaft insertion hole 24b of the second guide plate 24, and the bearing hole 28b of the second bearing plate 28. The second shaft portion 33 has, from the flange 31 side, a large diameter portion 33a, a small diameter portion 33b, and an irregularly shaped portion 33c formed with flat sides, and the small diameter portion 33b is inserted so as to be positioned within each of the shaft insertion holes 23b, 210b, 220c, 24b and the bearing hole 28b of the second bearing plate 28. Of these, the shaft insertion hole 23b of the first guide plate 23, the shaft insertion hole 210b of the integrated member 210 of the first disk-shaped gear 21, and the bearing hole 28b of the second bearing plate 28 have inner diameters formed to be approximately the same as the diameter of the small diameter portion 33b, so that the small diameter portion 33b can rotate therein. The shaft insertion hole 220c of the cam 220 of the second disk-shaped gear 22 and the shaft insertion hole 24b of the second guide plate 24 have inner diameters larger than the diameter of the small diameter portion 33b, but since the second disk-shaped gear 22 and the second guide plate 24 are assembled together via support pins 25, 26, during normal angle adjustment, they end up rotating along the outer periphery of the small diameter portion 33b.

[0036] The angle adjustment shaft 30 is provided so that the axis 32A of the first shaft portion 32 and the axis 33A of the second shaft portion 33 are eccentric via the flange 31. Therefore, the axis of the internal gear 10 integrated with the first bearing plate 11 is the axis CL1 of the first shaft portion 32, and the axis of the first disk-shaped gear 21 and the second disk-shaped gear that make up the external gear 20 is the axis CL2 of the second shaft portion 33. Therefore, when the angle adjustment shaft 30 rotates, the second shaft portion 33 rotates eccentrically relative to the first shaft portion 32, thereby pressing outward against the inner surfaces of the shaft insertion hole 23b of the first guide plate 23, the shaft insertion hole 210b of the integrated member 210 of the first disk-shaped gear 21, and the bearing hole 28b of the second bearing plate 28, and the outer teeth 211e, 221e rotate while meshing with the inner teeth 10a of the internal gear 10.

[0037] The irregular-shaped portion 33c of the second shaft portion 33 of the angle adjustment shaft 30 protrudes outward from the bearing hole 28b of the second bearing plate 28 and is connected to an operating member (not shown) composed of a lever, dial, or the like. By rotating this operating member, the angle adjustment shaft 30 rotates, and the external teeth 211e, 221e of the external gear 20 rotate and move while meshing with the internal teeth 10a of the internal gear 10, as described above, thereby adjusting the reclining angle.

[0038] One of the pin insertion holes 221a, 221b formed in each split gear 221 of the second disk-shaped gear 22, specifically, the pin insertion hole 221a corresponding to the pin support hole 231a, 241a having a smaller diameter through which one support pin 25 is inserted in the first and second guide plates 23, 24, is formed with a larger diameter than the other pin insertion hole 221b. The other pin insertion hole 221b, like the pin insertion hole 211a formed in each split gear 211 of the first disk-shaped gear 21, has an inner diameter substantially the same as the diameter of the support pin 26. Therefore, in each split gear 221 of the second disk-shaped gear 22, the other support pin 26 inserted into the other pin insertion hole 221b cannot move relative to the other in the radial direction, but can be displaced in the direction in which one pin insertion hole 221a located near the opposite edge in the circumferential direction swings around the other support pin 26 as the center.

[0039] Therefore, when the protrusion 220b2 of the L-shaped protrusion 220b of the cam 220 rotates in a direction that disengages it from the protrusion engagement groove 221h, and the outer end face 220b3 of the L-shaped protrusion 220b presses the inner peripheral edge 221f of each split gear 221, each split gear 221 rotates around the other support pin 26, causing one of the pin insertion holes 221a to swing outward (see Figure 5).

[0040] Next, the operation of the reclining device 1 of this embodiment will be described. (When adjusting the reclining angle) The angle adjustment shaft 30 is rotated by operating the operating member (not shown). The angle adjustment shaft 30 rotates the first and second disk-shaped gears 21, 22 that constitute the external gear 20 because the axis CL1 of the first shaft portion 32 and the axis CL2 of the second shaft portion 33 are eccentric. Because the axis CL2 is eccentric, the first and second disk-shaped gears 21, 22 rotate while the external teeth 211e, 221e, which have fewer teeth, move toward the internal teeth 10a of the internal gear 10. This functions as a Taumel-type gear mechanism, allowing the reclining angle to be adjusted. At this time, the meshing relationship between the external teeth 211e of the first disk-shaped gear 21 and the internal teeth 10a of the internal gear 10 is as shown in FIG. 2(a). Furthermore, since the protruding piece 220b2 of the L-shaped protrusion 220b of the cam 220 of the second disk-shaped gear 22 is engaged with the protrusion engagement groove 221h and pulls the split gear 221 toward the center, the meshing relationship between the external teeth 221e and the internal teeth 10a of the internal gear 10 is as shown in Figures 2(b), 3 and 4. During angle adjustment, the meshing ratio of the external teeth 211e, 221e to the internal teeth 10a of the internal gear 10 is, for example, about 30 to 50%.

[0041] (When locked) When the operation of the operating member is stopped, the rotation of the first and second disk-shaped gears 21, 22 stops, and the external teeth 211e, 221e remain engaged with the internal teeth 10a at that position, and the reclining angle becomes the desired angle.

[0042] The cam operating member 27 is biased by, for example, a spring member (not shown). Therefore, when the operation of the operating member is stopped, the rotation of the cam 220 (clockwise rotation in FIG. 5) causes the outer end surface 220b3 of the L-shaped projection 220b to press against the inner peripheral edge 221f of each split gear 221 constituting the second disk-shaped gear 22. As a result, each split gear 221 of the second disk-shaped gear 22 rotates around the other support pin 26, causing one pin insertion hole 221a side to swing outward. Note that this other support pin 26 corresponds to the "support pin arranged near one edge (which serves as the swing center)" defined in the claims.

[0043] For example, when the operation of the operating member is stopped, the meshing between the external teeth 221e of each split gear 221 constituting the second disk-shaped gear 22 and the internal teeth 10a of the internal gear 10 is in the state shown in Figure 5. In the figure, the external teeth 221e and the internal teeth 10a are in contact and stopped at a-1, b-1, c-1, etc. In this state, when a rotational force is applied in association with the clockwise rotation of the cam 220, the outer end surface 220b3 of the L-shaped protrusion 220b moves along the inner peripheral edge 221f of each split gear 221 constituting the second disk-shaped gear 22 from the other pin insertion hole 221b side to one pin insertion hole 221a side, and presses radially outward. This generates a rotational force with the other support pin 26 inserted into the other pin insertion hole 221b as the center of rotation, and at the same time, a pressing force is applied by the outer end surface 220b3 of the L-shaped protrusion 220b of the cam 220 to push each split gear 221 radially outward.

[0044] As a result, the entire external teeth 221e of each split gear 221 approach the internal teeth 10a of the internal gear 10, thereby locking (primary lock). At the same time, as the number of meshed teeth increases, the rotational force also causes a wedge-like lock (secondary lock). Therefore, backlash on the order of microns is eliminated at a-1, b-1, c-1, etc., which were in contact when rotation stopped. Furthermore, the primary lock eliminates play between the internal gear 10, and the secondary lock also functions to prevent the primary lock from being released during resonance. Furthermore, because each of the three split gears 221 is pushed radially outward while also moving in the oscillating direction, wedge engagement occurs at various locations with respect to the internal gear 10, and the sum of these frictional forces results in locking.

[0045] Therefore, the lock is released by moving along the slope where the teeth of the internal gear 10 and the external gear 20 come into contact, which is highly effective in preventing the seat back from gradually reclining. Moreover, in this embodiment, locking is not performed using a separate wedge member or the like that is not a component of the external gear 20, but rather the second disk-shaped gear 22, which functions as one of the external gears 20, itself functions as a locking member during angle adjustment. This eliminates the need for a separate locking member, contributing to a simplified structure.

[0046] (Action against Load) The action against load will be explained with reference to FIGS. 6(a) to 6(c). While FIGS. 6(a) to 6(c) show the first disk-shaped gear 21, the same action occurs for the second disk-shaped gear 22. First, assume that a load is input to the seat back in the direction indicated by the arrow in FIG. 6(a). In this case, a moment load is received with the external gear 20, which is formed by combining the first disk-shaped gear 21 and the second disk-shaped gear 22, the internal gear 10, the integrated member 210 of the first disk-shaped gear 21, and the cam 220 of the second disk-shaped gear 22 acting as a force point, a point of application, and a fulcrum. These components generate a predetermined resistance against a predetermined load. The point of contact between the internal teeth 10a of the internal gear 10 and the external teeth 211e, 221e of each split gear 211, 221 serves as a fulcrum, the integrated member 210 and the cam 220 serve as points of application, and the support pins 25, 26 serve as fulcrums. As shown in FIG. 6B, the load input to the seat back is distributed to the integrated member 210 and the support pins 25 and 26, and a couple of forces is generated in each split gear 211.

[0047] Three of the support pins 25 on one side are inserted into small-diameter pin support holes 231a, 241a in the guide plates 23, 24 connected to the back frame via the second bearing plate 28, and three of the support pins 26 on the other side are inserted into large-diameter pin support holes 231b, 241b in the guide plates 23, 24 (see FIG. 1). Therefore, when a large load is input due to an impact, as shown in FIG. 6(c), the split gear 211 of the first disk-shaped gear 21 tends to rotate outward around one support pin 25, with the other support pin 26 inserted into the larger-diameter pin support holes 231b, 241b being pressed against the internal gear 10. As a result, the external teeth 211e of the split gear 211 bite deeply into the internal gear 10, changing the depth of meshing between them. Furthermore, the engaging projection 210c of the integrated member 210 that integrates the split gear 211 and the engaging projection notch groove 211g of the split gear 211 also attempt to deform, but a resistance force that resists this deformation is also generated. These actions allow the large load to be absorbed efficiently.

[0048] (Load-bearing capacity experiment) Experimental method: As shown in FIG. 7, a universal testing machine (AG-xplus 30 kN; Shimadzu Corporation) was used to measure the load-bearing capacity by applying a moment around the eccentric shaft to the test specimen at a loading speed of 1 mm / s. FIGS. 8(a) and 8(b) show the structure of the test specimen. In FIG. 8(a), two 4 mm thick (590 MPa) steel plates were used. For the purpose of load measurement, the external gear was constructed by stacking the first disk-shaped gear 21 in the axial direction, each of which had three divided gear segments (Example). FIG. 8(b) shows an image of a comparative test specimen, showing the structure of a disk-shaped gear that serves as the external gear, constructed from a single 6 mm thick steel plate (Comparative Example 1) and a single 4 mm thick steel plate (Comparative Example 2). The external teeth of the split gears, which are all external gears, have a module of 1.7 and 39 teeth, and six M10 bolts are used as support pins.

[0049] Experimental Results Figure 9 shows moment-displacement curves for the Example and Comparative Examples 1 and 2. For the Example (two-plate structure (4 mm + 4 mm)), the load-bearing strength was 9000 N m, and the maximum value that constituted the allowance was 10,650 N m. The ratio of load-bearing strength to allowance was 10,650 / 9000 = 1.18. For Comparative Example 1 (single-plate structure (6 mm)), the load-bearing strength was 6000 N m, and the maximum value that constituted the allowance was 8,150 N m. The ratio of load-bearing strength to allowance was 8,150 / 6000 = 1.36. For Comparative Example 2 (single-plate structure (4 mm)), the load-bearing strength was 4,600 N m, and the maximum value that constituted the allowance was 6,250 N m. The ratio of load-bearing strength to allowance was 6,250 / 4,800 = 1.36. In the case of a conventional Taumel type reclining device, the maximum value is about 1600 N·m.

[0050] The slope of the moment-displacement curve was 270 N·m / mm for the Example, 190 N·m / mm for Comparative Example 1, and 140 N·m / mm for Comparative Example 2. From the above experimental results, it was found that in the Example, the deformation behavior of the split gear is such that a shear force is applied via the support pin, whereas in Comparative Examples 1 and 2, which have a single plate structure, a shear and bending force is applied, and that a two-plate structure like the Example is the structure that is least likely to produce deformation errors in the deformation behavior.

[0051] Figures 10(a) to (c) show the deformation state of the split gear 211, etc., corresponding to the first disk-shaped gear 21 in the Example and Comparative Examples 1 and 2, after a moment strength experiment. In this experiment, the split gears of the Example and Comparative Examples 1 and 2 were all constructed using a material with a strength of 590 MPa, and their deformation behavior was captured. In the photographs shown in Figures 10(a) to (c), 87% of the total number of teeth were engaged in all cases. The deformation of the shaft insertion hole at the center of the integrated member, which serves as the center of rotation of the split gear, was greater in Comparative Examples 1 and 2 than in the Example. This is because in the case of Comparative Examples 1 and 2, not only shear force but also bending moment from the support pin was applied.

[0052] The 4 mm thick single plate in Comparative Example 2 showed significant deformation, the 6 mm thick single plate in Comparative Example 1 showed moderate deformation, and when two 4 mm thick plates in the Example were stacked, the deformation was uniform. The strength characteristics of the two-plate Example were outstanding. The breaking point at the time of maximum load application was shear fracture in the support pin of the Example with a two-plate structure. The 6 mm thick single plate in Comparative Example 1 broke one of the gear segments. The 4 mm thick single plate in Comparative Example 2 experienced tooth slippage. From these findings, in the case of the single-plate Comparative Examples 1 and 2, it is necessary to increase the material strength in order to improve the load-bearing strength. However, in the Example, the two-plate structure distributes the load, allowing materials with lower strength than those in Comparative Examples 1 and 2 to achieve the desired load-bearing strength, which contributes to cost reduction.

[0053] The designed tooth strength is 11,522 N·m for the Example, 8,624 N·m for Comparative Example 1, and 5,761 N·m for Comparative Example 2. The test results for an 87% engagement rate showed a maximum load value of 10,649 N·m for the Example, 8,149 N·m for Comparative Example 1, and 6,248 N·m for Comparative Example 2. From these results, it can be said that the effect of shear fracture of the bolt was reflected in the test results for the Example, and that the material strength was reflected in the test results for Comparative Examples 1 and 2.

[0054] By using the configuration of the embodiment, it is possible to select a material with high tensile strength, further reduce the plate thickness, and reduce weight. For example, ferritic and martensitic DP steel and bainitic steel can be used as materials. However, in fine blanking, the thinner the plate, the more warping occurs during processing. Therefore, the aspect ratio of the shape is designed to prevent warping, and processing pressure is set higher. This improves punching workability. Furthermore, since the height of burrs is reduced by thinning the plate, the burr height can be reduced, and by arranging the burred surface in a direction that does not affect gear movement, the burr removal process can be eliminated. This contributes to simplifying the manufacturing process and shortening manufacturing time.

[0055] REFERENCE SIGNS LIST 1 Reclining device 10 Internal gear 10a Internal teeth 11 First bearing plate 20 External gear 21 First disc-shaped gear 211 Split gear 211e External teeth 210 Integrated member 22 Second disc-shaped gear 221 Split gear 221e External teeth 220 Cam 23 First guide plate 24 Second guide plate 25, 26 Support pin 27 Cam operating member 28 Second bearing plate 30 Angle adjustment shaft

Claims

1. An internal gear connected to one of the seat cushion and the seat back, and an external gear connected to the other, having external teeth with a different number of teeth that mesh with the internal teeth of the internal gear, and disposed eccentrically with respect to the internal gear, wherein the external gear has multiple sets of disk-shaped gears stacked in the axial direction, Each of the plurality of sets of disk-shaped gears is composed of a combination of split gears that are divided into a plurality of pieces in the circumferential direction, and the plurality of split gears have pin insertion holes formed closer to each circumferential edge than the circumferential center of each arc, and split gears whose pin insertion holes are connected to each other in the axial direction are supported axially outward of each of the plurality of sets of disk-shaped gears by support pins that are hung between a pair of guide plates arranged with the plurality of sets of disk-shaped gears therebetween, and when adjusting the reclining angle, the plurality of sets of disk-shaped gears rotate together while some of their external teeth mesh with the internal teeth of the internal gear, A recliner device is provided in which a cam is provided at the rotation center of at least one of the disk-shaped gears to move the multiple split gears constituting the disk-shaped gears radially, and when the reclining angle is locked, the rotation of the cam generates an outward rotational force on each of the split gears, with the support pin located near one edge as the swing center, and the cam exerts a radially outward pushing force, which presses a portion of the outer teeth of each of the split gears in a direction that eliminates backlash between them and the inner teeth, thereby locking them.

2. The reclining device according to claim 1, wherein the disc-shaped gear, with the cam disposed at its center of rotation, has a pin insertion hole located near the edge on the opposite side of the circumference from the pin insertion hole at the center of oscillation, the pin insertion hole being formed with a diameter larger than the diameter of the support pin inserted into said pin insertion hole.

3. A reclining device according to claim 1, wherein when a large load greater than a predetermined value is input, the support pin and the split gear are deformed, and the depth of engagement between the external teeth and the internal teeth changes to support the load.

4. A reclining device as claimed in claim 1, wherein at least one other set of disc-shaped gears other than the disc-shaped gear at the rotation center of which the cam is arranged has an integrating member arranged at the rotation center that integrates the divided gears, which are divided into multiple pieces, into a disc-shaped form, the integrating member having engaging protrusions protruding at predetermined intervals from its outer periphery, and each of the divided gears having a protrusion notch groove on its inner periphery that engages with the engaging protrusions, the disc-shaped form is maintained when the reclining angle is adjusted or locked, and when a large load greater than a predetermined value is input, a resistance is generated by the engaging protrusions of the integrating member and the protrusion notch groove.

5. A reclining device according to claim 4, wherein the pair of guide plates are provided with pin support holes for supporting the respective support pins, and the pin support hole corresponding to one of the two pin insertion holes formed in the split gear is formed with a diameter larger than the diameter of the support pin.

6. The reclining device according to claim 1, wherein the split gear is divided into three parts in the circumferential direction.

7. The reclining device according to claim 4, wherein the disk-shaped gear with the cam disposed at its rotation center and the disk-shaped gear with the integrated member disposed at its rotation center are stacked in pairs in the axial direction.

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