Vehicle seat and method for manufacturing vehicle seat

Abstract

To provide a structure which can achieve improvement of synchronism of both reclining units without complicating connection work.SOLUTION: A shaft 24a of a first reclining unit 21a and a shaft 24b of a second reclining unit 21b are formed so that a pair of connection pieces 22c is fixedly welded in a state where the shaft 24a and the shaft 24b face a bottom surface 22b of a connection member 22 in an inclined state where a part of each shaft 24a, 24b contacts with the bottom surface 22b on a flat outer surface 27a. These shafts 24a, 24b are arranged so that rotation centers of the shaft 24a, 24b are located on a predetermined rotation axis L and the outer surface 27a is set having a predetermined inclination angle θ2 relative to the bottom surface 22b when the pair of connection pieces 22 is fixedly welded.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to a vehicle seat having a pair of reclining units that tilt a seat back relative to a seat cushion, and a method for manufacturing the same. [Background technology]

[0002] A conventional vehicle seat equipped with a pair of reclining units that tilt the seat back relative to the seat cushion is the vehicle seat disclosed in Patent Document 1. This vehicle seat is equipped with a right-side reclining unit and a left-side reclining unit that are configured in reverse, and a connecting rod (a long connecting member), and the hinge pin (shaft) of the right-side reclining unit and the hinge pin of the left-side reclining unit are connected by the connecting rod, so that the right-side reclining unit and the left-side reclining unit are synchronously locked off, etc. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-094990 Summary of the Invention [Problem to be solved by the invention]

[0004] In the process of connecting the shafts of the left and right reclining units to the long connecting member, each shaft is rotated to a predetermined rotation position (for example, a position rotated in the lock-off direction) and then welding or other work is performed to connect the components while maintaining the alignment of their rotation center axes. This is because connecting the shafts without aligning their rotation positions will result in misalignment of the lock-off timing of the left and right reclining units.

[0005] However, in the above-described work process of aligning the rotational positions of the shafts for welding, the equipment required is complicated, including jigs for aligning the rotational positions of each shaft, making it difficult to improve production takt time.

[0006] The present invention has been made to solve the above-mentioned problems, and its purpose is to provide a configuration that can improve the synchronization of both reclining units without making the connecting work complicated. [Means for solving the problem]

[0007] In order to achieve the above object, the invention of claim 1 described in the claims is as follows: a seat cushion and a seat back; one reclining unit and another reclining unit that control tilting of the seat back relative to the seat cushion; a long connecting member for connecting the one reclining unit and the other reclining unit so as to rotate synchronously; A vehicle seat comprising: the connecting member includes a main body having a flat bottom surface and a pair of connecting pieces connected to the main body at both ends thereof so as to face each other via the bottom surface, The one reclining unit and the other reclining unit are a shaft to which the pair of connecting pieces are welded and fixed, facing each other in an inclined state with a planar opposing surface partially contacting the bottom surface of the connecting member; A locking member; a first plate attached to the seat cushion; a second plate attached to the seat back; Each equipped with The locking member is pushed and rotated by the rotating shaft, and the first plate and the second plate, which are in a relatively rotatable state, rotate relatively around the rotation center of the shaft in response to the rotation of the shaft, thereby tilting the seat back relative to the seat cushion, The shaft is characterized in that, when fixed by welding, the center of rotation of the shaft is positioned on a predetermined rotation axis and the opposing surface is inclined at a predetermined angle with respect to the bottom surface.

[0008] The invention of claim 2 is as follows: a seat cushion and a seat back; one reclining unit and another reclining unit that control tilting of the seat back relative to the seat cushion; a long connecting member for connecting the one reclining unit and the other reclining unit so as to rotate synchronously; A vehicle seat comprising: the connecting member includes a main body portion having a flat bottom surface, a pair of connecting pieces connected to the main body portion at both ends thereof so as to face each other via the bottom surface, and a protrusion provided on the bottom surface, The one reclining unit and the other reclining unit are a shaft to which the pair of connecting pieces are welded and fixed in a state in which the planar opposing surfaces of the shaft face the bottom surface of the connecting member with a predetermined gap therebetween; A locking member; a first plate attached to the seat cushion; a second plate attached to the seat back; Each equipped with The locking member is pushed and rotated by the rotating shaft, and the first plate and the second plate, which are in a relatively rotatable state, rotate relatively around the rotation center of the shaft in response to the rotation of the shaft, thereby tilting the seat back relative to the seat cushion, When fixed by welding, the shaft is arranged so that its rotation center is located on a predetermined rotation axis line, The protrusion is provided at a position on the bottom surface where it pushes and rotates the opposing surface when the base is welded and fixed.

[0009] The invention of claim 3 is as follows: a seat cushion and a seat back; one reclining unit and another reclining unit that control tilting of the seat back relative to the seat cushion; a long connecting member for connecting the one reclining unit and the other reclining unit so as to rotate synchronously; A method for manufacturing a vehicle seat comprising: the connecting member includes a main body having a flat bottom surface and a pair of connecting pieces connected to the main body at both ends thereof so as to face each other via the bottom surface, The one reclining unit and the other reclining unit are a shaft to which the pair of connecting pieces are welded and fixed, facing each other in an inclined state with a planar opposing surface partially contacting the bottom surface of the connecting member; A locking member; a first plate attached to the seat cushion; a second plate attached to the seat back; Each equipped with The locking member is pushed and rotated by the rotating shaft, and the first plate and the second plate, which are in a relatively rotatable state, rotate relatively around the rotation center of the shaft in response to the rotation of the shaft, thereby tilting the seat back relative to the seat cushion, a step of positioning the one reclining unit and the other reclining unit so that the rotation centers of the respective shafts are positioned on a predetermined rotation axis line; pressing the connecting member against the shaft so that the opposing surface is inclined at a predetermined angle with respect to the bottom surface; welding and fixing the pair of connecting pieces to the shaft while pressing the connecting member against the shaft; The present invention is characterized by comprising:

[0010] The invention of claim 4 is as follows: a seat cushion and a seat back; one reclining unit and another reclining unit that control tilting of the seat back relative to the seat cushion; a long connecting member for connecting the one reclining unit and the other reclining unit so as to rotate synchronously; A method for manufacturing a vehicle seat comprising: the connecting member includes a main body portion having a flat bottom surface, a pair of connecting pieces connected to the main body portion at both ends thereof so as to face each other via the bottom surface, and a protrusion provided on the bottom surface, The one reclining unit and the other reclining unit are a shaft to which the pair of connecting pieces are welded and fixed in a state in which the planar opposing surfaces of the shaft face the bottom surface of the connecting member with a predetermined gap therebetween; A locking member; a first plate attached to the seat cushion; a second plate attached to the seat back; Each equipped with The locking member is pushed and rotated by the rotating shaft, and the first plate and the second plate, which are in a relatively rotatable state, rotate relatively around the rotation center of the shaft in response to the rotation of the shaft, thereby tilting the seat back relative to the seat cushion, a step of positioning the one reclining unit and the other reclining unit so that the rotation centers of the respective shafts are positioned on a predetermined rotation axis line; pressing the coupling member against the shaft so that the protrusion presses against the opposing surface; welding and fixing the pair of connecting pieces to the shaft while pressing the connecting member against the shaft; The present invention is characterized by comprising: [Effects of the Invention]

[0011] In the invention of claim 1, the long connecting member for connecting one reclining unit and the other reclining unit so that they rotate synchronously is configured to include a main body with a flat bottom surface and a pair of connecting pieces connected to the main body at both ends so as to face each other via the bottom surface. The shafts of the one reclining unit and the other reclining unit are formed so that the pair of connecting pieces are welded and fixed to the bottom surface of the connecting member in an inclined state where their flat opposing surfaces partially contact each other, and the shafts are arranged so that when welded and fixed, the rotation center of the shaft is located on a predetermined rotation axis and the opposing surfaces are at a predetermined inclination angle with respect to the bottom surface.

[0012] As a result, by pressing the connecting member against the shaft before welding, the contact portion of the opposing surface of the shaft is pressed down by the bottom surface of the connecting member, and the shaft is rotated to a position where it can push and turn the locking member. Therefore, simply by welding the pair of connecting pieces of the pressed connecting member to the shaft as described above, the rotational positions of both shafts can be aligned by welding, thereby improving the synchronization of both reclining units without making the connecting work complicated.

[0013] In the invention of claim 2, the long connecting member for connecting one reclining unit and the other reclining unit so that they rotate synchronously includes a main body with a flat bottom surface, a pair of connecting pieces connected to the main body at both ends so as to face each other via the bottom surface, and a protrusion provided on the bottom surface. The one reclining unit and the other reclining unit are arranged so that the rotation center of the shaft is located on a predetermined rotation axis when welded and fixed. The protrusion is provided on the bottom surface at a position that pushes and rotates the opposing surface when welded and fixed.

[0014] As a result, by pressing the connecting member against the shaft before welding, the protrusion on the bottom surface presses down on the contact portion of the opposing surface of the shaft, causing the shaft to rotate to a position where it can push and turn the locking member. Therefore, simply by welding the pair of connecting pieces of the pressed connecting member to the shaft as described above, the rotational positions of both shafts can be aligned by welding, thereby improving the synchronization of both reclining units without making the connecting work complicated.

[0015] In the invention of claim 3, the long connecting member for connecting one reclining unit and the other reclining unit so that they rotate synchronously is configured to include a main body with a flat bottom surface and a pair of connecting pieces connected to the main body at both ends so that they face each other via the bottom surface.The one reclining unit and the other reclining unit are then positioned so that the rotation centers of their respective shafts are located on predetermined rotation axes, and the pair of connecting pieces are welded and fixed to the shafts with the connecting member pressed against the shafts so that the opposing surfaces are inclined at a predetermined angle relative to the bottom surface.

[0016] As a result, when the connecting member is pressed against the shaft, the contact area on the opposing surface of the shaft is pressed down by the bottom surface of the connecting member, causing the shaft to rotate to a position where it can push and turn the locking member. Therefore, simply by welding the pair of connecting pieces of the pressed connecting member to the shaft as described above, the rotational positions of both shafts can be aligned by welding and fixed, thereby improving the synchronization of both reclining units without making the connecting work complicated.

[0017] In the invention of claim 4, the long connecting member for connecting one reclining unit and the other reclining unit so that they rotate synchronously is configured to include a main body with a flat bottom surface, a pair of connecting pieces connected to the main body at both ends of the main body so as to face each other via the bottom surface, and a protrusion provided on the bottom surface.The one reclining unit and the other reclining unit are then positioned so that the rotation centers of their respective shafts are located on predetermined rotation axes, and the pair of connecting pieces are welded and fixed to the shafts with the connecting member pressed against the shafts so that the protrusions press and rotate the opposing surfaces.

[0018] As a result, when the connecting member is pressed against the shaft, the protrusion on the bottom surface presses down on the contact portion of the opposing surface of the shaft, causing the shaft to rotate to a position where it can push and rotate the locking member. Therefore, simply by welding the pair of connecting pieces of the pressed connecting member to the shaft as described above, the rotational positions of both shafts can be aligned by welding and fixed, thereby improving the synchronization of both reclining units without making the connecting process complicated. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a side view showing an outline of the configuration of a vehicle seat according to the present invention; [Figure 2] FIG. [Figure 3] FIG. [Figure 4] 4(A) is a view of the second reclining unit taken along a cross section corresponding to line X1-X1 in FIG. 3, and FIG. 4(B) is an enlarged view of the shaft and its vicinity in FIG. 4(A). [Figure 5] FIG. 3 is a cross-sectional view of the first reclining unit. [Figure 6] 6 is a cross-sectional view taken along a line X2-X2 shown in FIG. 5. [Figure 7] 6 is a cross-sectional view taken along a line X3-X3 shown in FIG. 5. [Figure 8]FIG. 2 is a perspective view of a shaft of the first reclining unit. [Figure 9] 9 is a view of the shaft in FIG. 8 as seen from the connecting member side. [Figure 10] 10A and 10B are explanatory diagrams illustrating the positional relationship between the shaft and the connecting member before and after welding in the first embodiment, where FIG. 10A shows the state before the shaft is pressed by the connecting member, and FIG. 10B shows the state after the shaft is pressed by the connecting member and welded. [Figure 11] FIG. 10 is a perspective view of a shaft in a vehicle seat according to a second embodiment. [Figure 12] 12 is a view of the shaft in FIG. 11 as seen from the connecting member side. [Figure 13] 13A and 13B are explanatory diagrams illustrating the positional relationship between the shaft and the connecting member before and after welding in the second embodiment, where FIG. 13A shows the state before the shaft is pressed by the connecting member, and FIG. 13B shows the state after the shaft is pressed by the connecting member and welded. [Figure 14] FIG. 10 is a cross-sectional view of a reclining unit that is a main part of a vehicle seat according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0020] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a vehicle seat according to the present invention will now be described with reference to the drawings. As shown in FIG. 1, the vehicle seat 10 of the present invention mainly comprises a seat cushion 11, a seat back 12, and a reclining device 20, and a seat bracket (lower bracket) 11a is fixed to the seat cushion 11, and a seat back bracket (upper bracket) 12a is fixed to the seat back 12.

[0021] The lower bracket 11a and the upper bracket 12a are respectively fixed to the relative rotating portions of the pair of left and right round reclining units of the reclining device 20, and are connected to each other so as to be capable of rotating relative to each other. This makes it possible to adjust the tilt angle of the seat back 12 relative to the seat cushion 11.

[0022] As shown in FIGS. 1 to 3, reclining device 20 includes a pair of left and right round reclining units (hereinafter also referred to as first reclining unit 21a and second reclining unit 21b), a long connecting member 22 for connecting first reclining unit 21a and second reclining unit 21b so that they rotate synchronously, and a manual reclining operation lever 23. For convenience, reclining operation lever 23 is not shown in FIGS. 2 and 3. Furthermore, first reclining unit 21a can be an example of "one reclining unit," and second reclining unit 21b can be an example of "the other reclining unit."

[0023] Shaft 24a of first reclining unit 21a and shaft 24b of second reclining unit 21b are connected by connecting member 22 so as to rotate synchronously, and reclining operation lever 23 is attached to shaft 24a. Therefore, in response to operation of reclining operation lever 23, first reclining unit 21a and second reclining unit 21b operate synchronously.

[0024] Specifically, when the reclining operation lever 23 is pulled upward, the reclining device 20 enters an unlocked state, allowing adjustment of the tilt angle of the seat back 12. Here, the range of angle A shown in Fig. 1 when the seat back 12 is tilted backward is the tilt adjustment range in which the seat back 12 is locked at that angle position when the reclining operation lever 23 is released, and the range of angle B shown in Fig. 1 when the seat back 12 is tilted forward is the free rotation range corresponding to a lock-free state in which the unlocked state remains even when the reclining operation lever 23 is released. As can be seen from Fig. 1, the seat back 12 can be rotated from a forward-tilted position in which it contacts the seat cushion 11 to a backward-tilted position in which it is flat against the seat cushion 11.

[0025] Since the first reclining unit 21a and the second reclining unit 21b are basically symmetrical in shape, the first reclining unit 21a will be taken as an example for explanation. As shown in Figures 2, 3 and 5, the first reclining unit 21a is configured by overlapping an approximately circular base plate 30 and an approximately bowl-shaped gear plate 40 and assembling a cover bracket 50, so that the base plate 30 and the gear plate 40 are held so as to be able to rotate relative to each other and relative movement in the axial direction is suppressed.

[0026] A cavity (space) C is formed between the base plate 30 and the gear plate 40. As shown in Figures 5 to 7, this cavity C is provided with a total of four lock gears, namely, a pair of first lock gears 61 and a pair of second lock gears 62, a central cam 70, two biasing members 80, and a substantially disk-shaped cam lever 90, as well as other locking and unlocking components. For convenience, in Figures 6 and 7, only the area near the internal teeth 41 of the gear plate 40 is shown, and the cover bracket 50 is not shown.

[0027] The base plate 30 has a plurality of protrusions formed on its outer side, and is attached to the lower bracket 11a by engaging each of these protrusions with an engaging hole in the lower bracket 11a. The base plate 30 also has a guide surface formed on its side facing the gear plate 40 for guiding the lock gears 61, 62 in the radial direction. The base plate 30 can be an example of a "first plate" attached to the seat cushion 11.

[0028] Internal teeth 41 are formed around the entire inner peripheral surface of the gear plate 40. The gear plate 40 has a plurality of protrusions formed on its back surface (the surface on the other axial side), and is attached to the upper bracket 12a by engaging each of these protrusions with an engaging hole in the upper bracket 12a.

[0029] Furthermore, two arcuate stepped portions formed coaxially with the internal teeth 41 are arranged at 180° intervals on the inner peripheral surface of the gear plate 40. The arcuate stepped portions are intended to realize the above-mentioned lock-free state, and are formed so that the angular range in which a protrusion 61c (described later) of the first lock gear 61 abuts from the inner peripheral side corresponds to the above-mentioned free rotation range. The gear plate 40 can be an example of a "second plate" attached to the seat back 12.

[0030] As shown in Fig. 6, external teeth 61a, 62a that can mesh with the internal teeth 41 of the gear plate 40 are formed on the outer peripheries of both first lock gears 61 and both second lock gears 62. Each lock gear 61, 62 is assembled so as to be guided radially slidably using each guide surface of the base plate 30. Furthermore, protrusions 61b, 61c that are used to control the radial movement of the first lock gear 61 are formed on the gear plate 40 side of both first lock gears 61. Furthermore, protrusions 62b that are used to control the radial movement of the second lock gear 62 are formed on the gear plate 40 side of both second lock gears 62.

[0031] The movable guide 37 is formed in a wedge shape so that its width gradually narrows from one end to the other end, and is disposed so as to be slidable between the first lock gear 61 and the guide surface of the base plate 30. Each movable guide 37 is formed with an engagement hole 37a for engaging one end of a biasing member 80. By engaging one end of the biasing member 80 with the engagement hole 37a, the biasing member 80 biases each movable guide 37 inwardly of the base plate 30. As a result, the movable guide 37 is always wedged between the first lock gear 61 and the guide surface of the base plate 30, and the first lock gear 61, the guide surfaces of the base plate 30, and the movable guide 37 are tightly fitted together (fitted together), eliminating any gap in the rotation direction between each component. This eliminates backlash in the front-rear direction of the seat back 12.

[0032] A plate-shaped cam 70, with a generally cross-shaped through-hole 71 formed in the center for fitting, is rotatably disposed in the center of the base plate 30. The cam 70 is formed so that when rotated in the unlocking direction, it abuts against the lock gears 61, 62 from the radially inner side, thereby causing the external teeth 61a, 62a to mesh with the internal teeth 41 of the gear plate 40. The cam 70 also has two engagement holes 73 with which the other ends of both biasing members 80 engage, and two cylindrical protrusions 74 for assembling the cam lever 90.

[0033] As shown in Fig. 7, the cam 70 is strongly urged in the locking direction (clockwise in Figs. 6 and 7) by engaging with each of the two urging members 80. As a result, the cam surface on the outer circumferential side of the cam 70 abuts against the inner end surfaces of the lock gears 61, 62, and the urging forces in the locking direction from the two urging members 80 strongly urge the lock gears 61, 62 radially outward.

[0034] The fitting portion 26 of the shaft 24a is inserted into the through-hole 71 of the cam 70, and by rotating the shaft 24a, the cam 70 can be rotated in the unlocking direction (counterclockwise in FIGS. 6 and 7) against the biasing forces of both biasing members 80. The cam 70 can be an example of a "locking member."

[0035] 7, the cam lever 90 is provided with a through hole 91 into which both protrusions 74 of the cam 70 are fitted, two cam holes 92, and two cam holes 93. The cam lever 90 is assembled to the gear plate 40 side of the cam 70 in a state in which both through holes 91 are fitted into both protrusions 74, respectively, the protrusion 61b is inserted into both cam holes 92, and the protrusion 62b is inserted into both cam holes 93, respectively.

[0036] As a result, when the cam lever 90 rotates in the unlocking direction together with the cam 70, the inner peripheral edge of the cam hole 92 abuts against the protrusion 61b of the first lock gear 61, and the inner peripheral edge of the cam hole 93 abuts against the protrusions 62b of both second lock gears 62. When the cam lever 90 further rotates in the unlocking direction, the protrusions 61b and 62b are urged radially inward by the inner peripheral edges of the cam holes 92 and 93, causing the lock gears 61 and 62 to move radially inward in conjunction with each other, thereby releasing the meshing between the external teeth 61a and 62a and the internal teeth 41 of the gear plate 40. In other words, the locked state and the unlocked state are controlled according to the rotational states of the cam 70 and the cam lever 90. The cam lever 90 may be an example of a "releasing member" that can release the meshing between the external teeth 61a and 62a and the internal teeth 41 by rotating the cam 70 against the biasing force of the biasing member.

[0037] 8 and 9, shaft 24a is formed to have large diameter portion 25, fitting portion 26, and support portion 27. Large diameter portion 25 is formed to be exposed to the outside from base plate 30 when fitting portion 26 fits into through-hole 71 of cam 70, and has a screw hole 25a formed in its end face for assembling reclining operation lever 23. Fitting portion 26 is formed to have a generally cross-shaped cross section so that its rotation center coincides with that of through-hole 71 of cam 70 when fitting.

[0038] The support portion 27 is formed so as to be exposed to the outside from the gear plate 40 when the fitting portion 26 fits into the through hole 71 of the cam 70. The support portion 27 is formed so as to have a substantially rectangular cross section with a pair of outer surfaces 27a facing each other on the long side of the cross section and a pair of outer surfaces 27b facing each other on the short side of the cross section. In particular, as shown in Fig. 9, in this embodiment, the plane of the support portion 27 along the outer surfaces 27a is formed at an acute angle θ1 in the unlocking direction with respect to a plane including one of the cross lines based on the cross-sectional shape of the fitting portion 26 (hereinafter simply referred to as a reference plane S).

[0039] Second reclining unit 21b is formed in a shape that is basically the symmetrical shape to first reclining unit 21a. Shaft 24b has the same shape as shaft 24a, and since reclining operation lever 23 cannot be assembled to shaft 24b, male thread portion 28 is threaded into threaded hole 25a.

[0040] Connecting member 22 has a generally U-shaped cross section and includes main body 22a with flat bottom surface 22b and a pair of connecting pieces 22c connected to main body 22a at both ends thereof so as to face each other via bottom surface 22b. Connecting member 22 has both ends welded to support portion 27 of shaft 24a exposed from gear plate 40 of first reclining unit 21a and support portion 27 of shaft 24b exposed from gear plate 40 of second reclining unit 21b, respectively.

[0041] In particular, in this embodiment, as shown in FIG. 4(B), a pair of connecting pieces 22c of connecting member 22 are welded and fixed to support portion 27 in a state where outer surface 27a of connecting member 22 is partially in contact with bottom surface 22b and faces support portion 27 in an inclined state at a predetermined inclination angle θ2 (see symbol W in FIG. 4(B)). In this welded and fixed state, support portion 27 receives a pressing force from connecting member 22 that rotates support portion 27 in the locking direction. By welding connecting member 22 in this manner, shafts 24a and 24b are connected so that they rotate synchronously, thereby synchronizing the locking and unlocking timings of first reclining unit 21a and second reclining unit 21b. Outer surface 27a can be considered an example of an "opposing surface."

[0042] With this configuration, in first reclining unit 21a and second reclining unit 21b, cam 70, which serves as a locking member, is pushed and rotated by rotating shafts 24a, 24b, and base plate 30 and gear plate 40, which are now in a relatively rotatable state, rotate relatively around the rotation centers of shafts 24a, 24b in response to the rotation of shafts 24a, 24b. As a result, seat back 12 tilts relative to seat cushion 11.

[0043] Here, the manufacturing process (step) of welding the connecting member 22 by utilizing both support portions 27 will be described with reference to FIGS. 10(A) and 10(B). First, first reclining unit 21a and second reclining unit 21b are assembled to the corresponding portions of lower bracket 11a and upper bracket 12a so that the rotation centers of respective shafts 24a, 24b are positioned on predetermined rotation axis L (see FIG. 3). At this time, as shown in FIG. 10(A), first reclining unit 21a and second reclining unit 21b are positioned so that reference plane S of shaft 24a and reference plane S of shaft 24b are approximately perpendicular to the pressing direction F from connecting member 22 (described later) (for example, so that reference plane S is along a horizontal plane) (first step).

[0044] Next, the connecting member 22 is positioned on the shafts 24a, 24b so that the bottom surface 22b is parallel to the reference plane S and the edge of the outer surface 27a is in approximately linear contact with the bottom surface 22b. In this positioned state (a state in which the bottom surface 22b is not pressing the outer surface 27a), as can be seen from FIG. 10(A), the inclination angle of the outer surface 27a relative to the bottom surface 22b is approximately equal to the angle θ1 described above. Then, from the positioned state described above, the connecting member 22 is pressed against the support portion 27 along the pressing direction F (see FIG. 10(A)) (second step).

[0045] 10(B), both support portions 27 rotate in the locking direction by the amount of pressure applied, so that shaft 24a of first reclining unit 21a and shaft 24b of second reclining unit 21b rotate to their locking positions and stop rotating. In this rotated state, the inclination angle of outer surface 27a relative to bottom surface 22b decreases from angle θ1 to the predetermined inclination angle θ2 described above.

[0046] In this state, the pair of connecting pieces 22c are welded and fixed to the support parts 27 of the shafts 24a and 24b, respectively, while the connecting member 22 is pressed against the support parts 27 until the rotation of both shafts 24a and 24b stops (third step).

[0047] In this way, the pair of connecting pieces 22c are welded to both support portions 27 while the connecting member 22 is pressed against both shafts 24a, 24b, so the welding work can be performed without the need for jigs or the like for adjusting the rotational positions of both shafts 24a, 24b to synchronize the first reclining unit 21a and the second reclining unit 21b.

[0048] As described above, in vehicle seat 10 according to this embodiment, elongated connecting member 22 for connecting first reclining unit 21a and second reclining unit 21b so as to rotate synchronously is configured to include main body 22a having a flat bottom surface 22b and a pair of connecting pieces 22c continuing to main body 22a at both ends of main body 22a so as to face each other via bottom surface 22b. Shaft 24a of first reclining unit 21a and shaft 24b of second reclining unit 21b are formed such that pair of connecting pieces 22c are welded and fixed to bottom surface 22b of connecting member 22 in an inclined state where a portion of flat outer surface 27a contacts bottom surface 22b of connecting member 22, and when welded and fixed, the rotation centers of shafts 24a, 24b are positioned on predetermined rotation axis L and outer surface 27a is at a predetermined inclination angle θ2 with respect to bottom surface 22b.

[0049] As a result, by pressing connecting member 22 against shafts 24a, 24b before welding, the contact portions of outer surfaces 27a of shafts 24a, 24b are pressed down by bottom surface 22b of connecting member 22, and shafts 24a, 24b are rotated to positions for pushing and rotating cam 70, etc. Therefore, simply by welding pair of connecting pieces 22c of connecting member 22 pressed as described above to shafts 24a, 24b, respectively, both shafts 24a, 24b can be welded and fixed so that their rotational positions are aligned, thereby improving the synchronization of both reclining units 21a, 21b without making the connection process complicated.

[0050] In addition, the manufacturing method for vehicle seat 10 according to this embodiment involves positioning first reclining unit 21a and second reclining unit 21b so that the rotation centers of respective shafts 24a, 24b are located on a predetermined rotation axis L, and then welding and fixing a pair of connecting pieces 22c to shafts 24a, 24b while pressing connecting member 22 against shafts 24a, 24b so that outer surface 27a is at a predetermined inclination angle θ2 relative to bottom surface 22b.

[0051] As a result, when connecting member 22 is pressed against shafts 24a, 24b, contact portions of outer surfaces 27a of shafts 24a, 24b are pressed down by bottom surface 22b of connecting member 22, causing shafts 24a, 24b to rotate to positions for pushing and rotating cam 70. Therefore, simply by welding pair of connecting pieces 22c of connecting member 22 pressed as described above to shafts 24a, 24b, both shafts 24a, 24b can be welded and fixed so that their rotational positions are aligned, thereby improving the synchronization of both reclining units 21a, 21b without making the connecting process complicated.

[0052] [Second embodiment] Next, a vehicle seat according to a second embodiment of the present invention will be described. In the second embodiment, the main difference from the first embodiment is the shape of the shaft and the connecting member that pushes and turns the shaft with the connecting member when the shaft is fixed by welding. Therefore, the same reference numerals are used for components that are substantially the same as those in the first embodiment, and descriptions thereof will be omitted.

[0053] In this embodiment, shafts 110a, 110b and a connecting member 120 are employed instead of the shafts 24a, 24b and the connecting member 22 of the first embodiment. As shown in Figures 11 and 12, the shafts 110a, 110b are formed with respect to the shaft 24a such that a plane along the outer surface 27a of the support portion 27 is parallel to the reference plane S. Therefore, the pair of connecting pieces 22c of the shafts 110a, 110b are welded and fixed to the bottom surface 22b of the connecting member 120 at the outer surface 27a in a state where they face each other with a predetermined gap therebetween.

[0054] 13(A) and 13(B), in addition to the main body 22a and the pair of connecting pieces 22c described above, the connecting member 120 has embosses 121 provided as protrusions on both longitudinal end portions of the bottom surface 22b. The embosses 121 are formed at positions that push and rotate the outer surface 27a in the locking direction when the bottom surface 22b is brought close to the outer surface 27a during welding and fixation.

[0055] In this embodiment, in the manufacturing process (step) of welding connecting member 120 to both shafts 110a, 110b, shaft 110a assembled to first reclining unit 21a and shaft 110b of second reclining unit 21b are assembled to corresponding portions of lower bracket 11a and upper bracket 12a so that the rotation centers of shaft 110a assembled to first reclining unit 21a and shaft 110b of second reclining unit 21b are positioned on predetermined rotation axis L. At this time, as shown in FIG. 13(A), first reclining unit 21a and second reclining unit 21b are positioned so that reference plane S of shaft 110a and reference plane S of shaft 110b are approximately perpendicular to the pressing direction F from connecting member 120 (so that outer surface 27a is approximately perpendicular to the pressing direction F).

[0056] Next, the connecting member 120 is positioned on the shafts 110a, 110b so that the bottom surface 22b is parallel to the reference plane S and the embossments 121 are in contact with the outer surface 27a. In this positioned state (a state in which the embossments 121 are not pressing against the outer surface 27a), as can be seen from FIG. 13(A), the outer surface 27a of the support portion 27 faces the bottom surface 22b of the connecting member 120 in a substantially parallel state with a predetermined gap therebetween. Then, from the positioned state described above, the connecting member 120 is pressed against the support portion 27 along the pressing direction F (see FIG. 13(A)) so that the embossments 121 press and rotate the outer surface 27a (second step).

[0057] As a result, as shown in Figure 13 (B), both support parts 27 rotate in the locking direction by the amount of pressure applied, so that shaft 110a of first reclining unit 21a and shaft 110b of second reclining unit 21b each rotate to the locking position and stop rotating.

[0058] In this state, the pair of connecting pieces 22c are welded and fixed to the support parts 27 of the shafts 110a and 110b, respectively, while the connecting member 120 is pressed against the support parts 27 until the rotation of both shafts 110a and 110b stops (third step).

[0059] In this way, the pair of connecting pieces 22c are welded to both support portions 27 while the connecting member 22 is pressed against both shafts 24a, 24b, so the welding work can be performed without the need for jigs or the like for adjusting the rotational positions of both shafts 24a, 24b to synchronize the first reclining unit 21a and the second reclining unit 21b.

[0060] As described above, in vehicle seat 10 according to this embodiment, long connecting member 120 for connecting first reclining unit 21a and second reclining unit 21b so as to rotate synchronously is configured to include main body 22a having a flat bottom surface 22b, a pair of connecting pieces 22c connected to main body 22a at both ends of main body 22a so as to face each other via bottom surface 22b, and embossments (protrusions) 121 provided on bottom surface 22b. First reclining unit 21a and second reclining unit 21b are arranged so that the rotation centers of shafts 110a, 110b are located on predetermined rotation axis L when fixed by welding. Embossments 121 are provided on bottom surface 22b at positions that will push and rotate outer surface 27a when fixed by welding.

[0061] As a result, by pressing connecting member 120 against shafts 110a, 110b before welding, the embossments 121 on bottom surface 22b press down on the contact portions of outer surfaces 27a of shafts 110a, 110b, causing shafts 110a, 110b to rotate to positions for pushing and rotating cam 70. Therefore, simply by welding a pair of connecting pieces 22c of connecting member 120 pressed as described above to shafts 110a, 110b, respectively, the rotational positions of both shafts 110a, 110b can be aligned by welding, thereby improving the synchronization of both reclining units 21a, 21b without making the connecting process complicated.

[0062] In addition, the manufacturing method for vehicle seat 10 according to this embodiment involves positioning first reclining unit 21a and second reclining unit 21b so that the rotation centers of respective shafts 110a, 110b are positioned on a predetermined rotation axis L, and then welding and fixing a pair of connecting pieces 22c to shafts 110a, 110b while pressing connecting member 120 against shafts 110a, 110b so that embossing 121 pushes and rotates outer surface 27a.

[0063] As a result, when connecting member 120 is pressed against shafts 110a, 110b, embossments 121 provided on bottom surface 22b press down on contact portions of outer surfaces 27a of shafts 110a, 110b, causing shafts 110a, 110b to rotate to positions for pushing and rotating cam 70. Therefore, simply by welding pair of connecting pieces 22c of connecting member 120 pressed as described above to shafts 110a, 110b, both shafts 110a, 110b can be welded and fixed so that their rotational positions are aligned, thereby improving the synchronization of both reclining units 21a, 21b without making the connecting process complicated.

[0064] [Third embodiment] Next, a vehicle seat according to a third embodiment of the present invention will be described. The third embodiment differs from the first embodiment mainly in that the structures of both reclining units are modified. Therefore, components that are substantially the same as those in the first embodiment are given the same reference numerals, and descriptions thereof will be omitted.

[0065] The first reclining unit (one of the reclining units) 221a and the second reclining unit (the other reclining unit) 221b in this embodiment operate using the driving force of a motor, and as in the first embodiment described above, each shaft is formed so that a pair of connecting pieces 22c are welded and fixed to face each other in an inclined state with a portion of the outer surface 27a contacting the bottom surface 22b of the connecting member 22, and when welded and fixed, the center of rotation of the shaft is located on a predetermined rotation axis and the outer surface 27a is arranged at a predetermined inclination angle with respect to the bottom surface 22b.

[0066] Specifically, the first reclining unit 221a is configured to include an external gear 230 attached to the lower bracket 11a, an internal gear 240 attached to the upper bracket 12a, a shaft 250, a U-shaped bushing 261 that functions as a locking member, a pair of wedge-shaped cams 262, a spring 263, a plate cover 270, a shaft cover (not shown), etc.

[0067] The external gear 230 has external teeth 231 formed on its outer circumferential surface, and a substantially cylindrical boss portion 232 formed in its center. The external gear 230 can be an example of a "first plate" attached to the seat cushion 11.

[0068] The internal gear 240 is configured to include a cylindrical portion having internal teeth 241 formed on its inner circumferential surface, and a side plate portion having a substantially cylindrical boss portion 242 formed in its center. The internal teeth 241 mesh eccentrically with the external teeth 231, and are therefore formed to have a greater number of teeth than the external teeth 231. A resin bearing 243 is fitted inside the boss portion 242 of the internal gear 240, and a U-shaped bushing 261 and a pair of wedge-shaped cams 262 are arranged between the inner circumferential surface of the boss portion 242 formed by this resin bearing 243 and the outer circumferential surface of the boss portion 232 of the external gear 230. The internal gear 240 can be an example of a "second plate" attached to the seat back 12.

[0069] The shaft 250 is configured to include a support portion 27 exposed to the outside in the positional relationship described above, a U-body portion 251 having serrations formed on its inner surface and coaxially fitted to the inner circumferential surface of the boss portion 232 of the external gear 230, and a U-shaped portion 252 covering part of the outer circumferential surface of the boss portion 232 fitted with the U-body portion 251. The U-shaped portion 252 is configured so that its both end faces in the rotation direction abut against both end faces in the rotation direction of a U-shaped bushing 261 incorporated into the inner circumferential side of the boss portion 242 of the internal gear 240, and so as to push and rotate one wedge-shaped cam 262 when rotating in a rotation direction that tilts the seat back 12 forward (forward tilt rotation direction), and to push and rotate the other wedge-shaped cam 262 when rotating in a rotation direction that tilts the seat back 12 backward (rearward tilt rotation direction).

[0070] The wedge-shaped cam 262 is formed in a wedge shape so that its radial thickness becomes thinner toward the tip. The wedge-shaped cam 262 is interposed between the outer circumferential surface of the boss portion 232 of the external gear 230 and the U-shaped bush 261, with its tip end face facing the end face of the U-shaped portion 252 in the rotation direction, and is arranged so that it is pressed against both the outer circumferential surface of the boss portion 232 and the U-shaped bush 261 by being biased from the base end side by a spring 263.

[0071] When the pair of wedge-shaped cams 262 are pressed as described above, the internal gear 240 becomes eccentric with respect to the external gear 230, and some of the external teeth 231 mesh with the internal teeth 241. In this eccentric state, the external gear 230 rotates relative to the internal gear 240 as described below, and the external gear 230 revolves around the gear axis of the internal gear 240, changing the meshing position between the external teeth 231 and the internal teeth 241. Furthermore, when the pair of wedge-shaped cams 262 are pressed against both the outer circumferential surface of the boss portion 232 and the U-shaped bushing 261 by the spring 263 so as to move them away from each other, the pair of wedge-shaped cams 262 are interposed at predetermined interpositions, and the relative rotation between the external gear 230 and the internal gear 240 is restricted.

[0072] The plate cover 270 is assembled to the internal gear 240 so as to suppress axial misalignment of the external gear 230 relative to the internal gear 240. The shaft cover is assembled to the internal gear 240 so as to suppress axial misalignment of the shaft 250 relative to the internal gear 240.

[0073] The first reclining unit 221a configured in this manner is welded and fixed to the lower bracket 11a using multiple protrusions formed on the side of the external gear 230, and is welded and fixed to the upper bracket 12a using multiple protrusions formed on the side of the internal gear 240.

[0074] The second reclining unit 221b is formed in a shape that is basically the symmetrical shape to the first reclining unit 221a.

[0075] Both ends of connecting member 22 are welded to support portion 27 of exposed shaft 250 of first reclining unit 221a and support portion 27 of exposed shaft 250 of second reclining unit 21b, respectively. By welding connecting member 22 in this manner, both shafts 250 are connected to each other so that they rotate synchronously.

[0076] With this configuration, in the first reclining unit 221a and the second reclining unit 221b, when both shafts 250 do not rotate, the pair of wedge-shaped cams 262 restrict the relative rotation between the external gear 230 and the internal gear 240, thereby maintaining the tilt angle of the seat back 12 relative to the seat cushion 11.

[0077] When the motor is driven in response to a forward tilting operation to rotate both shafts 250 in a forward tilting rotation direction, one of the two wedge-shaped cams 262, which is opposite to the rotation direction, is pushed and rotated by the U-shaped portion 252 against the biasing force of the spring 263, thereby releasing the pressing state of the one wedge-shaped cam 262. As a result, the external gear 230, which rotates relative to the internal gear 240, rotates together with the shaft 250 in the forward tilting rotation direction, and the seat back 12 tilts forward relative to the seat cushion 11.

[0078] On the other hand, when the motor is driven in response to a rearward tilting operation to rotate both shafts 250 in the rearward tilting rotation direction, the other of the two wedge-shaped cams 262, which is opposite to the rotation direction, is pushed and rotated by the U-shaped portion 252 against the biasing force of the spring 263, thereby releasing the pressing state of the other wedge-shaped cam 262. As a result, the external gear 230, which has rotated relatively to the internal gear 240, rotates together with the shaft 250 in the rearward tilting rotation direction, and the seat back 12 tilts rearward relative to the seat cushion 11.

[0079] In the manufacturing process of this embodiment, in which connecting member 22 is welded using both support portions 27, first reclining unit 221a and second reclining unit 221b are positioned so that the rotation centers of respective shafts 250 are located on predetermined rotation axes L, as in the first embodiment described above. Then, pair of connecting pieces 22c are welded and fixed to shaft 250 with connecting member 22 pressed against shaft 250 so that outer surfaces 27a form a predetermined inclination angle with respect to bottom surface 22b. As a result, when connecting member 22 is pressed against both shafts 250, the contact portions of outer surfaces 27a of both shafts 250 are pressed down by bottom surface 22b of connecting member 22, and shaft 250 rotates to a rotation position where U-shaped portion 252 presses wedge-shaped cam 262 and does not rotate further (a state in which shaft 250 has rotated to a position for pushing and rotating wedge-shaped cam 262, which serves as a locking member). Therefore, by simply welding the pair of connecting pieces 22c of the connecting member 22 pressed as described above to both shafts 250, the rotational positions of both shafts 250 can be aligned by welding and fixing, thereby improving the synchronization of both reclining units 221a, 221b without making the connecting work complicated.

[0080] The characteristic configuration of this embodiment may be applied to the configuration of the second embodiment. That is, in the manufacturing process of welding connecting member 120 using both support portions 27, first reclining unit 221a and second reclining unit 221b are positioned so that the rotation centers of their respective shafts are located on predetermined rotation axis L, as in the second embodiment. Then, pair of connecting pieces 22c are welded and fixed to the shaft with connecting member 120 pressed against the shaft so that embossments 121 press and rotate outer surface 27a. As a result, when connecting member 120 is pressed against the shaft, embossments 121 on bottom surface 22b press down on the contact portion of outer surface 27a of the shaft, causing the shaft to rotate to a rotation position where U-shaped portion 252 presses wedge-shaped cam 262 and then to a state where it does not rotate further. Therefore, by simply welding the pair of connecting pieces 22c of the connecting member 120 pressed as described above to the shaft, the rotational positions of both shafts can be aligned by welding and fixing them, thereby improving the synchronization of both reclining units 221a, 221b without making the connecting work complicated.

[0081] [Other embodiments] The present invention is not limited to the above-described embodiments, and may be embodied as follows, for example. (1) The elongated connecting member 22 is not limited to being formed in a substantially U-shape by the main body 22a and the pair of connecting pieces 22c, but may be formed, for example, so that only the ends welded to the shafts 24a, 24b are provided with the pair of connecting pieces 22c, and the central portion has another shape (for example, a flat plate shape or a square ring shape consisting of only the main body 22a). The connecting member 120 can be formed in a similar manner.

[0082] (2) The present invention is not limited to being applied to a vehicle seat 10 having a reclining device 20 in which a base plate 30 is attached to a lower bracket 11a and a gear plate 40 is attached to an upper bracket 12a, but may also be applied to a vehicle seat having a reclining device in which a base plate is attached to an upper bracket 12a and a gear plate is attached to a lower bracket 11a.

[0083] (3) In the first embodiment and the like, instead of reclining units 21a and 21b excluding shafts 24a and 24b, a reclining unit that controls engagement between the external teeth of a lock gear guided to be slidable in the radial direction relative to a base plate and the internal teeth of a gear plate by rotation of a cam, such as the reclining unit disclosed in Japanese Patent Application Laid-Open No. 2018-114095 or the reclining unit disclosed in Japanese Patent Application Laid-Open No. 2013-163474, which have the same basic configuration, may be used. The same applies to the second embodiment and the like.

[0084] (4) In the above third embodiment, etc., instead of reclining units 221a, 221b excluding the shaft, a reclining unit may be adopted, such as the reclining unit disclosed in Patent Publication No. 2021-146833 or the reclining unit disclosed in Patent Publication No. 2021-83659, which have the same basic configuration, in which some of the external and internal teeth are meshed by eccentrically positioning two plates, restricting the relative rotation of the two plates when the shaft does not rotate, and controlling the two plates to a state in which they can rotate relative to each other by pushing and rotating a cam due to the rotation of the shaft. [Explanation of symbols]

[0085] 10...Vehicle seat 11...Seat cushion 12...Seat back 20...Reclining device 21a, 221a...First reclining unit (one of the reclining units) 21b, 221b...Second reclining unit (the other reclining unit) 22...Connecting member 22a...Main body 22b…Bottom surface 22c...Connection piece 24a, 24b, 110a, 110b, 250... shaft 26...Mating part 27...Support part 27a...Outer surface (opposing surface) 30...Base plate (first plate) 40...Gear plate (second plate) 41...Inner teeth 61...1st lock gear 61a…external teeth 62...Second lock gear 62a...external teeth 70...Cam (locking component) 80... Urging member 90...Cam lever 120...Connecting member 121...Embossment (protrusion) 230...External gear (first plate) 240...Internal gear (second plate) 262...Wedge-shaped cam (locking member) L…Rotation axis

Claims

1. a seat cushion and a seat back; one reclining unit and another reclining unit that control tilting of the seat back relative to the seat cushion; a long connecting member for connecting the one reclining unit and the other reclining unit so as to rotate synchronously; A vehicle seat comprising: the connecting member includes a main body having a flat bottom surface and a pair of connecting pieces connected to the main body at both ends thereof so as to face each other via the bottom surface, The one reclining unit and the other reclining unit are a shaft to which the pair of connecting pieces are welded and fixed, facing each other in an inclined state with a planar opposing surface partially contacting the bottom surface of the connecting member; A locking member; a first plate attached to the seat cushion; a second plate attached to the seat back; Each equipped with The locking member is pushed and rotated by the rotating shaft, and the first plate and the second plate, which are in a relatively rotatable state, rotate relatively around the rotation center of the shaft in response to the rotation of the shaft, thereby tilting the seat back relative to the seat cushion, The vehicle seat is characterized in that, when fixed by welding, the shaft is positioned so that the center of rotation of the shaft is located on a predetermined rotation axis and the opposing surface is at a predetermined inclination angle with respect to the bottom surface.

2. a seat cushion and a seat back; one reclining unit and another reclining unit that control tilting of the seat back relative to the seat cushion; a long connecting member for connecting the one reclining unit and the other reclining unit so as to rotate synchronously; A vehicle seat comprising: the connecting member includes a main body portion having a flat bottom surface, a pair of connecting pieces connected to the main body portion at both ends thereof so as to face each other via the bottom surface, and a protrusion provided on the bottom surface, The one reclining unit and the other reclining unit are a shaft to which the pair of connecting pieces are welded and fixed in a state in which the planar opposing surfaces of the shaft face the bottom surface of the connecting member with a predetermined gap therebetween; A locking member; a first plate attached to the seat cushion; a second plate attached to the seat back; Each equipped with The locking member is pushed and rotated by the rotating shaft, and the first plate and the second plate, which are in a relatively rotatable state, rotate relatively around the rotation center of the shaft in response to the rotation of the shaft, thereby tilting the seat back relative to the seat cushion, When fixed by welding, the shaft is arranged so that its rotation center is located on a predetermined rotation axis line, The vehicle seat, wherein the protrusion is provided on the bottom surface at a position that pushes and rotates the opposing surface when the seat is welded and fixed.

3. a seat cushion and a seat back; one reclining unit and another reclining unit that control tilting of the seat back relative to the seat cushion; a long connecting member for connecting the one reclining unit and the other reclining unit so as to rotate synchronously; A method for manufacturing a vehicle seat comprising: the connecting member includes a main body having a flat bottom surface and a pair of connecting pieces connected to the main body at both ends thereof so as to face each other via the bottom surface, The one reclining unit and the other reclining unit are a shaft to which the pair of connecting pieces are welded and fixed, facing each other in an inclined state with a planar opposing surface partially contacting the bottom surface of the connecting member; A locking member; a first plate attached to the seat cushion; a second plate attached to the seat back; Each equipped with The locking member is pushed and rotated by the rotating shaft, and the first plate and the second plate, which are in a relatively rotatable state, rotate relatively around the rotation center of the shaft in response to the rotation of the shaft, thereby tilting the seat back relative to the seat cushion, a step of positioning the one reclining unit and the other reclining unit so that the rotation centers of the respective shafts are positioned on a predetermined rotation axis line; pressing the connecting member against the shaft so that the opposing surface is inclined at a predetermined angle with respect to the bottom surface; welding and fixing the pair of connecting pieces to the shaft while pressing the connecting member against the shaft; A method for manufacturing a vehicle seat, comprising:

4. a seat cushion and a seat back; one reclining unit and another reclining unit that control tilting of the seat back relative to the seat cushion; a long connecting member for connecting the one reclining unit and the other reclining unit so as to rotate synchronously; A method for manufacturing a vehicle seat comprising: the connecting member includes a main body portion having a flat bottom surface, a pair of connecting pieces connected to the main body portion at both ends thereof so as to face each other via the bottom surface, and a protrusion provided on the bottom surface, The one reclining unit and the other reclining unit are a shaft to which the pair of connecting pieces are welded and fixed in a state in which the planar opposing surfaces of the shaft face the bottom surface of the connecting member with a predetermined gap therebetween; A locking member; a first plate attached to the seat cushion; a second plate attached to the seat back; Each equipped with The locking member is pushed and rotated by the rotating shaft, and the first plate and the second plate, which are in a relatively rotatable state, rotate relatively around the rotation center of the shaft in response to the rotation of the shaft, thereby tilting the seat back relative to the seat cushion, a step of positioning the one reclining unit and the other reclining unit so that the rotation centers of the respective shafts are positioned on a predetermined rotation axis line; pressing the coupling member against the shaft so that the protrusion presses against the opposing surface; welding and fixing the pair of connecting pieces to the shaft while pressing the connecting member against the shaft; A method for manufacturing a vehicle seat, comprising:

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