Safety devices for vehicle seats

Abstract

[Problem] To provide a safety device for a vehicle seat, said safety device being capable of preventing warping in the width direction of a seat back when a vehicle collision occurs, and thus being capable of properly restraining an occupant. [Solution] The present invention relates to a safety device for a vehicle seat that comprises a reclining mechanism capable of adjusting the angle of a seat back and protects an occupant who is seated in the vehicle seat. A seat belt is configured to extend in a diagonal direction, from an upper end section on a first side in the width direction of the seat back, toward a lower end on a second side, which is the opposite side from the first side. In a rotational shaft section that serves as a shaft when the seat back reclines, an adjustment means is provided that allows the rotation quantities on the first side and the second side of the seat back to vary when a vehicle collision occurs.

Description

[Technical Field]

[0001] This invention relates to a safety device for a vehicle seat. More particularly, it relates to a safety device for a retractor-integrated automobile seat equipped with a seat belt retractor. [Background technology]

[0002] Automobiles are equipped with seat belts to restrain occupants to their seats. The most common type of seat belt is the three-point seat belt, which extends diagonally downwards from near one shoulder and horizontally near the hip bone. Furthermore, recent automobiles are equipped with retractors that automatically retract the seat belt just before and / or immediately after a collision.

[0003] Patent Document 1 describes a retractor-integrated automobile seat in which the seat belt retractor is provided on the seat back. In the retractor-integrated seat, for example, as shown in Figure 1(A), the seat belt retractor 12 is positioned at the upper end of the seat back 10, and the upper end 14a of the seat belt 14 extends from above the shoulder of the occupant P. Because the retractor is located close to the occupant's shoulder, there is little gap between the occupant P's shoulder and the seat belt 14, which has the advantage of reliably restraining the occupant to the seat back 10.

[0004] Generally, as shown in Figure 1(A), when a frontal collision occurs with the seatback 12 in a nearly vertical position, the occupant P will lean forward due to inertia, as shown in Figure 1(B). At this time, the pretension function provided in the seatbelt retractor 12 can prevent the occupant P from leaning excessively forward.

[0005] Automotive seats are equipped with a reclining mechanism, allowing the seatback to be tilted backward or raised forward. As shown in Figure 2(A), if a frontal collision occurs with the seatback 10 tilted significantly backward (reclined), as shown in Figure 2(B), a compressive force is applied to the spine from the head to the waist of the occupant P, potentially causing serious injury. This problem is particularly pronounced in seats with integrated retractors. In seats where the retractor is fixed to the B-pillar, a gap is formed between the top of the seatbelt and the occupant's shoulder when the seatback is reclined, so it cannot be discussed in the same way as seats with integrated retractors, but spinal compression remains a concern.

[0006] Incidentally, when a frontal collision (such as a head-on collision) occurs while wearing a seat belt, as shown in Figure 3(B), the seat back 10 on the side where the upper end 14a of the seat belt 14 is located (right side) is more likely to tilt forward than the opposite side (left side). This is because the shoulder of the occupant P is pressed against the seat back 10 by the seat belt 14 on the right side of the seat back 10, causing the seat back 10 and the right shoulder of the occupant P to be in close contact. In this way, if the seat back 10 becomes twisted or deformed (distorted), it becomes difficult to properly restrain the occupant P. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2002-283892 [Overview of the project] [Problems that the invention aims to solve]

[0008] The present invention was made to solve the above-mentioned problems, and aims to provide a safety device for vehicle seats that can prevent distortion (twisting) in the width direction of the seat back when a vehicle collision occurs, thereby enabling proper restraint of the occupant.

[0009] Another object of the present invention is to provide a safety device for a vehicle seat that can reduce the compressive pressure on the occupant's spine in the event of a vehicle collision. [Means for solving the problem]

[0010] The present invention relates to a safety device for a vehicle seat that protects an occupant seated in the vehicle seat, and includes a reclining mechanism that allows adjustment of the angle of the seat back. The seat belt is configured to extend diagonally from the upper end of the first side in the width direction of the seat back to the lower end of the second side opposite to the first side. The rotating shaft portion, which is the axis when the seat back reclines, is provided with an adjustment means that varies the amount of rotation of the first side and the second side of the seat back in the event of a vehicle collision.

[0011] Here, "the first side in the width direction of the seatback" and "the second side" can be said to be the left and right sides of the occupant when the occupant is seated in a normal position facing forward. Also, when the seat is facing the direction of travel (forward), they can be said to be the left and right sides of the seatback in the direction of travel.

[0012] Furthermore, the description states that "the seat belt extends diagonally from the upper end of the first side in the width direction of the seat back toward the lower end of the second side opposite to the first side," which applies to at least a typical three-point seat belt.

[0013] In addition, the "rotation axis portion of the seat back that serves as an axis when reclining" refers to the portion connected to the reclining mechanism at the lower end of the seat back, and means the portion that serves as the axis of rotation of the seat back. For example, it may be a circular hole formed in the seat back frame, a portion connected to the hole, or a shaft-shaped axis that passes through the hole and is connected to the left and right seat back frames.

[0014] In the present invention, as the "adjusting means for making the rotation amounts of the first side and the second side of the seat back variable when a vehicle collision occurs", in addition to providing a torsion bar described later on the rotation axis portion, the rigidity of the seat frame (such as the seat back frame and the seat side frame) may be set differently in the width direction of the seat back, or a member such as a stopper that restricts the rotation of the seat back may be provided on one side in the width direction of the seat back.

[0015] In the present invention, by making the rotation amounts of the first side and the second side of the seat back variable when a vehicle collision occurs, when a force is applied in the direction in which the seat back falls forward due to inertia, it is possible to suppress the torsion (distortion) generated in the width direction of the seat back. As a result, the occupant can be restrained in a balanced manner, and the restraint performance of the occupant is significantly improved. In particular, the rotational component of the occupant's head in the Z direction (with respect to the vertical axis) is reduced, contributing to the reduction of head injuries. Furthermore, the rebound behavior of the occupant after the collision is suppressed, and as a result, it is possible to reduce the risk of secondary collisions inside the vehicle.

[0016] The adjusting means may include a second torsion bar connected to at least the rotation axis portion of the second side of the seat back.

[0017] Here, "connected" to the rotation axis portion means being continuously coupled coaxially with the rotation axis portion and being in a state where they can rotate integrally. Also, the "rotation axis portion" can be specified as the end portion of a torsion bar provided through a hole formed in the seat back frame.

[0018] By connecting a second torsion bar to the second side of the seatback, when a vehicle collision occurs, the second side of the seatback can be made to fall forward (rotate more easily) compared to the first side, and torsional deformation in the width direction of the seatback can be suppressed.

[0019] The adjusting means may further include a first torsion bar connected to the rotary shaft portion on the first side of the seatback. And it is preferable to set the torque characteristic T1 (N·m) with respect to the displacement angle of the first torsion bar to be larger than the torque characteristic T2 (N·m) with respect to the displacement angle of the second torsion bar.

[0020] Here, the "torque characteristic with respect to the displacement angle" represents the difficulty (ease) of twisting of the torsion bar. When the torque characteristic is high, the torsion bar is difficult to twist, and when the torque characteristic is low, it is easy to twist. The "displacement angle" can also be referred to as the "twist angle". The torque characteristic of the torsion bar can be adjusted by changing the thickness and length of the bar or the material of the bar.

[0021] Note that the "torque characteristic with respect to the displacement angle" is generally synonymous with the "torsional rigidity" in the case of a round bar torsion bar. When the torsional rigidity is large, it is difficult to twist, and when the torsional rigidity is small, it is easy to twist.

[0022] When a vehicle collision occurs while the seatback is in a backward fallen state, as shown in Fig. 2(B), a large compressive pressure is applied to the occupant's spine. However, according to the present invention, since torsion bars are connected to both the left and right sides of the rotary shaft portion of the seatback, even when the seatback is lying backward, the torsion bars twist (absorb energy), causing the seatback to move in the direction of standing forward. As a result, the compressive pressure on the occupant's spine is significantly reduced.

[0023] If the torsional rigidity of the torsion bars on both the left and right sides were to be the same, the seatback would tilt significantly forward on the first side where the seatbelt contacts the occupant's shoulder, as shown in Figure 3(B). This would cause the seatback to twist or deform (distort), causing the occupant's body to rotate in a direction where the right side (right shoulder, etc.) moves forward, making it difficult to properly restrain the occupant. For example, the rotational component of the occupant's head in the Z direction (relative to the vertical axis) would increase, raising concerns about the occurrence of head injury.

[0024] In this invention, the torque characteristic T1 (N·m) of the first torsion bar with respect to the displacement angle is set to be greater than the torque characteristic T2 (N·m) of the second torsion bar with respect to the displacement angle. As a result, the first torsion bar becomes less prone to twisting, and the twisting of the seat back in the vehicle width direction as described above is suppressed during a vehicle collision. Consequently, the occupant restraint performance is improved. In particular, the rotational component of the occupant's head in the Z direction (relative to the vertical axis) is reduced, contributing to the reduction of head injuries. Furthermore, the rebound behavior of the occupant after a collision is suppressed, and as a result, the risk of secondary collisions inside the vehicle can be reduced.

[0025] The vehicle seat may further include a seat belt retractor for winding up the seat belt.

[0026] Here, "equipped with a seat belt retractor" means that the retractor is located and fixed to some part of the seat, excluding cases where it is fixed to a structural part of the vehicle such as the pillar. This would be a location that does not affect the extension and retraction of the seat belt, such as the upper or lower part of the seat back.

[0027] The seat belt retractor can be positioned near the upper end of the first side of the seat back.

[0028] If the seat belt retractor is located at the upper end of the seat back, the weight of the retractor, combined with the initial movement of the first side of the seat back, makes it even easier for the seat back to move forward. Therefore, employing a torsion bar with appropriately adjusted torque characteristics, as in the present invention, becomes even more beneficial. The seat belt retractor can also be installed near the lower back of the seat back, rather than at the upper end. In this case, it is necessary to provide a member to guide the seat belt at the upper end of the seat back.

[0029] The seat belt retractor is equipped with a load limiter that restricts the tension of the seat belt, and the load at which the load limiter activates is F L Let L be the distance from the center of the rotating shaft portion to the upper end of the seat back when the seat is viewed from the side in the width direction, and let ΔT be the difference between torques T1 and T2. barI-II Given this, the following equation can be constructed to hold true. ΔT barI-II ≒F L ×L ····(1)

[0030] The distance L can be the distance from the center of the rotating shaft to the belt extension portion of the retractor. Here, "≒" means approximately equal. Load F at which the load limiter activates L For example, it can be set to 2kN to 5kN.

[0031] In the event of a head-on collision, the occupants are restrained by seat belts, and the load limiter activates when a certain level of tension is applied to the seat belts. In the above embodiment, since the seat belt retractor is located on the first side of the seat back, the load F when the load limiter is activated is... L The product of (F) the distance L from the first rotating shaft portion of the seatback to the belt pull-out portion. L A moment represented by (F × L) is applied to the first side of the seat back's pivot point. L×L), and the difference (ΔT barI-II ) between the torque T1 of the first torsion bar and the torque T2 of the second torsion bar are made to generally coincide, thereby cancelling out the torque difference between the first side and the second side of the seat back. As a result, it becomes possible to effectively suppress the torsion in the width direction of the seat back.

[0032] The reclining mechanism can adopt a structure including a worm gear mechanism composed of a worm wheel connected to an end portion of the first or second torsion bar on the side opposite to the seat back, and a worm meshing with the worm wheel.

[0033] When a worm gear mechanism composed of a worm wheel and a worm is adopted, the rotation of the worm shaft having a worm formed on its outer periphery rotates the worm wheel via the worm, thereby enabling the reclining of the seat back. When a vehicle collision occurs, since the worm shaft does not rotate, the reclining operation of the seat back cannot be performed, and the torque for the seat back to fall forward is absorbed by the torsion bar.

[0034] The reclining mechanism can adopt a structure including a gear member connected to an end portion of the first or second torsion bar on the side opposite to the seat back, a lock member for restricting the rotation of the gear member, and an adjustment member for releasing the meshing between the gear member and the lock member and adjusting the angle of the seat back frame.

[0035] By releasing the meshing between the gear member and the lock member with a lever, the seat back can move freely and reclining becomes possible. When a vehicle collision occurs, since the gear member and the lock member are meshed, the reclining operation of the seat back cannot be performed, and the torque for the seat back to fall forward is absorbed by the torsion bar.

Brief Description of the Drawings

[0036] [Figure 1]Figure 1 is a side view illustrating the background of the present invention, where (A) shows the state before the vehicle collision and (B) shows the state immediately after the vehicle collision. [Figure 2] Figure 2 is a side view illustrating the background of the present invention, where (A) shows the state before the vehicle collision and (B) shows the state immediately after the vehicle collision. [Figure 3] Figure 3 is a side view (perspective view) illustrating the background of the present invention, where (A) shows the state before the vehicle collision and (B) shows the state immediately after the vehicle collision. [Figure 4] Figure 4 is a perspective view showing the frame structure and safety device of a vehicle seat according to the first embodiment of the present invention. [Figure 5] Figure 5 is a perspective view showing the power unit of a reclining mechanism applicable to the present invention. [Figure 6] Figure 6 is a perspective view showing the structure of a safety device according to the first embodiment of the present invention, and is an enlarged view of a portion of Figure 4. [Figure 7] Figure 7 is a top view showing the structure of a safety device according to the first embodiment of the present invention, where (A) corresponds to the right side of the seat and (B) corresponds to the left side of the seat. [Figure 8] Figure 8 is an exploded perspective view showing the structure of a safety device according to the first embodiment of the present invention, and corresponds to a part of Figure 6. [Figure 9] Figures 9(A) and 9(B) are schematic diagrams (A) and graphs (B) illustrating the configuration and characteristics of a safety device according to a first embodiment of the present invention. [Figure 10] Figure 10 is a graph showing another aspect of the characteristics of the safety device according to the first embodiment. [Figure 11] Figures 11(A) and (B) are perspective views showing the reclining operation of a vehicle seat according to the first embodiment of the present invention. [Figure 12] Figure 12 is a perspective view showing the operation of a safety device according to the first embodiment of the present invention. [Figure 13] Figure 13 is a side view illustrating the operation of a safety device according to the first embodiment of the present invention, where (A) shows the state before the vehicle collision and (B) shows the state immediately after the vehicle collision. [Figure 14]Figure 14 is a perspective view showing the structure of a safety device according to a second embodiment of the present invention, which is applied to a seat in which the seat back reclining operation is performed manually. [Figure 15] Figure 15 is an exploded perspective view of the structure shown in Figure 14. [Figure 16] Figure 16 is a perspective view of the assembled (completed) structure shown in Figures 14 and 15. [Figure 17] Figure 17 is an exploded perspective view showing the structure of a safety device according to a second embodiment of the present invention, and shows the structure on the opposite side (right side) of Figure 15 (left side). [Figure 18] Figure 18 is a perspective view showing the unlocking operation of a vehicle seat reclining mechanism according to a second embodiment of the present invention. [Figure 19] Figure 19 is a side view showing the unlocking operation of a vehicle seat reclining mechanism according to a second embodiment of the present invention, where (A) shows the locked state and (B) shows the unlocked state. [Modes for carrying out the invention]

[0037] The embodiments for carrying out the present invention will be described in detail below with reference to the attached drawings. First, the background to the creation of the present invention will be briefly explained with reference to Figures 1 to 3.

[0038] Figure 1(A) shows a vehicle seat in which a seat belt retractor 12 for winding up a seat belt 14 is provided on the seat back 10, with the occupant P seated with the seat back 10 not reclined much. From this state, if an event such as a head-on collision occurs, the occupant P will move forward due to inertia, as shown in Figure 1(B).

[0039] Figure 2(A) shows the seatback 10 reclined far to the rear. In this position, when an event such as a head-on collision occurs, unlike in Figure 1(B), the occupant P does not move much in the direction of leaning forward, as shown in Figure 2(B). This is because the occupant P is restrained in a direction that brings it into close contact with the seatback 10 by the upper end 14a of the seat belt 14. As a result, compressive pressure is applied to the occupant P's spine, raising concerns about the occurrence of serious injury.

[0040] Therefore, in this invention, we propose a structure in which a torsion bar is connected to the seat reclining mechanism. That is, a torsion bar is connected to the rotation axis on both the left and right sides of the seat back.

[0041] Figure 3(A) shows an occupant P seated normally on the seat cushion 11. If a vehicle collision occurs from this position, as shown in Figure 3(B), the seat back 10 (10R) tends to tilt significantly forward on the side (right side) where the upper end 14a of the seat belt 14 contacts the occupant P near their shoulder. When this happens, the seat back 10 becomes twisted or deformed (distorted), making it difficult to properly restrain the occupant P. The present invention solves this problem as well.

[0042] As shown in Figure 3(A), the present invention is a safety device for a vehicle seat, which is equipped on a vehicle seat comprising a seat cushion 11 on which an occupant P sits, a seat back 10 located behind the occupant P, a reclining mechanism that allows adjustment of the angle of the seat back 10, and a seat belt retractor 12 that retracts the seat belt 14. The seat belt 14 extends diagonally from the shoulder of the first side (right side) in the width direction of the seat back 10 toward the lower end of the second side (left side) opposite to the first side. The seat belt retractor 12 can be positioned at locations other than the top of the seat back 10, such as the rear lower part of the seat back 10.

[0043] (First embodiment) The first embodiment of the present invention will be described below with reference to Figures 4 to 13. The first embodiment is applied to a vehicle seat that uses motor power to recline the seat back.

[0044] Figure 4 is a perspective view showing the frame structure and safety device of a vehicle seat according to the first embodiment of the present invention. Figure 5 is a perspective view showing the power unit of a reclining mechanism applicable to the present invention. Figure 6 is a perspective view showing the structure of the safety device according to the first embodiment of the present invention, and is an enlarged view of a part of Figure 4. Figure 7 is a top view showing the structure of the safety device according to the first embodiment of the present invention, where (A) corresponds to the right side of the seat and (B) corresponds to the left side of the seat. Figure 8 is an exploded perspective view showing the structure of the safety device according to the first embodiment of the present invention, and corresponds to a part of Figure 6. In each figure, the reference numerals indicate that components with "R" are located on the right side of the seat back and components with "L" are located on the left side.

[0045] As shown in Figures 4 to 8, the reclining mechanism comprises a motor 110 and a center shaft 112 that transmits power from the motor 110. Power from the motor 110 is transmitted from the center shaft 112 to bevel gears 114L, 114R and worm shafts 115L, 115R. The rotation of the worm shafts 115L, 115R is transmitted to the rotating shaft portions 106L, 106R of the seat back frame 104L, 104R via worms 116L, 116R and worm wheels 118L, 118R formed on them.

[0046] The rotating shaft portions 106L and 106R are parts connected to the reclining mechanism at the lower ends of the seat back frames 104L and 104R, and can be identified as circular holes formed in the seat back frames. Alternatively, they can be shaft-shaped axes that pass through these holes and connect to the left and right seat back frames. Furthermore, in this embodiment, they can also be identified as the ends of torsion bars 120L and 120R that are provided passing through the holes formed in the seat back frames.

[0047] The safety device according to this embodiment includes a first torsion bar 120R connected to the first side (right side) of the seat back 10 and a second torsion bar 120L connected to the second side (left side) of the seat back 10. One end (inner end) of the first and second torsion bars 120R and 120L is fixed to the left and right side seat back frames 104R and 104L. The other ends (outer ends) of the first and second torsion bars 120R and 120L are connected to the worm wheels 118R and 118L.

[0048] As shown in Figures 6 to 8, limit switches 122a and 122b are provided on the seat back frame 104L and the seat side frame 102L to restrict the forward reclining angle of the seat back 10 (seat back frame 104L, 104R). When the rotation angle of the seat back frame 104L, 104R reaches its limit, the system detects this and takes measures such as stopping the operation of the motor 110.

[0049] Reference numeral 126R and 126L in the figure indicate connecting plates for fixing the first and second torsion bars 120R and 120L to the seat back frames 104R and 104L. Reference numeral 124R and 124L indicate stoppers that prevent the first and second torsion bars 120R and 120L from coming out of the seat side frames 102R and 102L. Reference numeral 128L indicates a spacer positioned between the seat back frame 104L and the seat side frame 102L.

[0050] In the present invention, the torque characteristic T1 (N·m) of the first torsion bar 120R with respect to the displacement angle is set to be greater than the torque characteristic T2 (N·m) of the second torsion bar 120L with respect to the displacement angle.

[0051] Figures 9(A) and 9(B) are schematic diagrams (A) and graphs (B) illustrating the configuration and characteristics of a safety device according to the first embodiment of the present invention. Figure 9(B) shows the torque of the torsion bar with respect to the rotation angle (displacement angle).

[0052] In this embodiment, the seat belt retractor 12 is equipped with a load limiter (not shown) that restricts the tension of the seat belt 14, and the load at which the load limiter activates is F L Let L be the distance from the center of the rotating shafts 106L and 106R when the seat is viewed from the side in the width direction to the upper end of the seat back 10, and let ΔT be the difference between torques T1 and T2. barI-II When this is the case, set it up so that the following equation holds true. ΔT barI-II ≒F L ×L ····(1)

[0053] Note that the load limiter will activate under load F. L This can be set to 2kN to 5kN.

[0054] Figure 10 is a graph showing another aspect of the characteristics of the safety device according to the present invention. In the present invention, the torque characteristic T1 (N·m) of the first torsion bar 120R with respect to the displacement angle and the torque characteristic T2 (N·m) of the second torsion bar 120L with respect to the displacement angle can be set to gradually increase with respect to the displacement angle (progressive setting).

[0055] (Operation of the reclining mechanism) Figures 11(A) and (B) are perspective views showing the reclining operation of a vehicle seat according to a first embodiment of the present invention. When tilting the seat back 10 backward, the power of the motor 110 is transmitted to the rotating shaft portions 106L and 106R of the seat back frame 104L and 104R via the center shaft 112, bevel gears 114L and 114R, worm shafts 115L and 115R, and worm gear mechanism (116L, 118L, 116R, 118R), causing the seat back frame 104L and 104R to rotate (swing) backward, as shown in Figure 11(A).

[0056] On the other hand, when raising the seat back 10 forward, the power from the motor 110 is transmitted to the rotating shaft portions 106L and 106R of the seat back frames 104L and 104R via the center shaft 112, bevel gears 114L and 114R, worm shafts 115L and 115R, and worm gear mechanisms (116L, 118L, 116R, and 118R), causing the seat back frames 104L and 104R to rotate (swing) forward, as shown in Figure 11(B).

[0057] (Safety device operation) Figure 12 is a perspective view showing the operation of a safety device according to the first embodiment of the present invention. Figure 13 is a side view illustrating the operation of a safety device according to the first embodiment of the present invention, where (A) shows the state before the vehicle collision and (B) shows the state immediately after the vehicle collision.

[0058] As shown in Figure 13(B), in the event of a frontal collision, the load limiter activates when a certain level of tension is applied to the seat belt. Simultaneously, inertia causes a force to be applied that tilts the seat back 10 forward. At this time, the reclining mechanism does not function due to the meshing of the worms 116L, 116R and the worm wheels 118L, 118R, but as shown in Figure 12, the torsion bars 120L, 120R twist and absorb energy, causing the seat back 10 (seat back frame 104L, 104R) to rotate forward.

[0059] In this embodiment, the torque characteristic T1 (N·m) of the first torsion bar 120R with respect to the displacement angle is set to be greater than the torque characteristic T2 (N·m) of the second torsion bar 120L with respect to the displacement angle. Furthermore, the load limiter load F L The distance L from the center of the rotating shafts 106L and 106R to the upper end of the seat back 10, and the difference between torques T1 and T2 are given by ΔT. barI-II The following equation is set to hold true under these conditions. ΔT barI-II ≒F L ×L ····(1)

[0060] In this embodiment, since the seat belt retractor 12 is provided on the first side (right side) of the seat back 10, the load F when the load limiter is activated L The product of (F) the distance L from the first rotating shaft portion 106R of the seat back 10 to the belt pull-out portion. L A moment represented by (F × L) is applied to the first rotating shaft portion 106R of the seat back 10. L (ΔT) is the difference between the torque T1 of the first torsion bar 120R and the torque T2 of the second torsion bar 120L. barI-II By roughly matching these two values, the torque difference between the first and second sides of the seatback 10 can be offset. This effectively suppresses twisting in the width direction of the seatback 10, improving the occupant restraint performance.

[0061] (Second example) A second embodiment of the present invention will be described below with reference to Figures 14 to 19. The second embodiment is applied to a vehicle seat in which the reclining operation of the seat back 10 is performed manually without using motor power. For components corresponding to those in the first embodiment described above, the same last two digits should be used whenever possible.

[0062] Figure 14 is a perspective view showing the structure of a safety device according to a second embodiment of the present invention. Figure 15 is an exploded perspective view of the structure in Figure 14. Figure 16 is a perspective view of the structure shown in Figures 14 and 15 assembled (completed). Figure 17 is an exploded perspective view showing the structure of a safety device according to a second embodiment of the present invention, showing the structure on the opposite side (right side) of Figure 15 (left side).

[0063] The reclining mechanism according to this embodiment includes gear members 226L, 226R connected to the rotating shaft portions 206L, 206R of the left and right seat back frames 204L, 204R via torsion bars 220L, 220R, lock plates 228L, 228R connected to both left and right ends of the lock plate shaft 230, and levers 224 for releasing the engagement between the gear members 226L, 226R and the lock plates 228L, 228R.

[0064] A lever guide shaft 232 is connected to the lever 224, allowing it to move along the lever guide grooves 234L and 234R. A lock plate shaft 230 is connected to the lock plates 228L and 228R, allowing these lock plates 228L and 228R to move synchronously on the left and right sides. When the lever 224 is lifted upward, the engagement between the lock plates 228L and 228R and the gear members 226L and 226R is released. As a result, the seat back 10 becomes free, allowing the reclining angle to be adjusted.

[0065] The safety device according to this embodiment, similar to the first embodiment, comprises a first torsion bar 220R connected to the seat back frame 204R and a second torsion bar 220L connected to the seat back frame 204L. One end (inner end) of the first and second torsion bars 220R, 220L is fixed to the left and right side seat back frames 204R, 204L via rotating shafts 206L, 206R. The other end (outer end) of the first and second torsion bars 220R, 220L is connected to gear members 226R, 226L.

[0066] As shown in Figure 17, on the right side opposite the lever 224, a lever plate 260 is provided that moves in sync with the lever 224. The main difference between the right side (Figure 15) and the left side (Figure 17) is that the lever 224 and the lever plate 260 are swapped.

[0067] Covers 238L and 238R are provided to cover the lever 224 and lever plate 260. The covers are provided with stoppers 270L and 270R for fixing the ends of the torsion bars 220L and 220R, and stoppers 272L and 270R for fixing the end of the lock plate shaft 230. One end of springs 236L and 236R are connected to the lever 224 and lever plate 260, and the other end of springs 236L and 236R are connected to the covers 238L and 238R.

[0068] In the figure, reference numerals 244R and 224L indicate connecting plates for fixing the first and second torsion bars 220R and 220L to the seat back frames 204R and 204L. Reference numeral 252L indicates a lever guard pin connected between the lever guide shaft 206 and the lever 224. Reference numeral 252R indicates a lever guard pin connected between the lever guide shaft 206 and the lever plate 260. Reference numerals 254L and 254R indicate lock plate shaft extensions, one end of which is connected to the end of the lock plate shaft 230, and the other end of which reaches the covers 238L and 238R via the lock plates 228L and 228R, and is fixed by stoppers 272L and 270R.

[0069] The seat side frames 202L and 202R have lever guide grooves 234L and 234R formed therein, which define the movement of the lever guide shaft 230. In addition, guide grooves 242L and 242R are formed therein, which define the rotation angle of the seat back frames 204L and 204R.

[0070] A lock plate pin guide groove 249 is formed in the lever 224, into which the lock plate pin 248L is inserted, guiding the movement of the lock plates 228L and 228R. Similarly, a lock plate pin guide groove 262 is formed in the lever plate 260, into which the lock plate pin 248R is inserted, guiding the movement of the lock plates 228L and 228R.

[0071] Figure 18 is a perspective view showing the reclining operation of a vehicle seat according to a second embodiment of the present invention. Figure 19 is a side view showing the reclining operation of a vehicle seat according to a second embodiment of the present invention, where (A) shows the locked state and (B) shows the unlocked state.

[0072] As shown in Figure 19(A), in the seat according to this embodiment, when the lever 224 is in a specified position (for example, horizontal), the gear member 226L connected to the torsion bar 220L is engaged with the lock plate 228L, and therefore the seat cannot be reclined.

[0073] On the other hand, as shown in Figures 18 and 19(B), when the lever 224 is pulled upward, the lock plate pin 248L moves along the lock plate pin guide 262, and the lock plate 228L rotates counterclockwise. This disengages the gear member 226L from the lock plate 228L, allowing the seat back 10 to recline. The mechanism on the right side of the seat also operates in sync with the one on the left side.

[0074] The characteristics, functions, and operation of the torsion bars 220L and 220R used in this embodiment are the same as those of the first embodiment described above, so redundant explanations will be omitted.

[0075] While the present invention has been described in relation to the above exemplary embodiments, many equivalent modifications and variations of this disclosure will be obvious to those skilled in the art. Therefore, the above exemplary embodiments of the present invention are illustrative but not limiting. Various modifications can be made to the described embodiments without departing from the spirit and scope of the invention.

Claims

1. A vehicle seat safety device that includes a reclining mechanism that allows adjustment of the seatback angle, and protects occupants seated in the vehicle seat, The seat belt is configured to extend diagonally from the upper end of the first side in the width direction of the seat back toward the lower end of the second side opposite to the first side. The rotating shaft portion that serves as the axis when the seat back reclines is provided with an adjustment means for varying the amount of rotation of the first side and the second side of the seat back in the event of a vehicle collision. The adjustment means includes a second torsion bar connected to the rotating shaft portion on at least the second side of the seat back, The adjustment means further comprises a first torsion bar connected to the first rotating shaft portion on the first side of the seat back, A safety device for a vehicle seat, characterized in that the torque characteristic T1 (N·m) of the first torsion bar with respect to the displacement angle is set to be greater than the torque characteristic T2 (N·m) of the second torsion bar with respect to the displacement angle.

2. The vehicle seat safety device according to claim 1, further comprising a seat belt retractor for winding up the seat belt.

3. The vehicle seat safety device according to claim 2, characterized in that the seat belt retractor is positioned near the upper end of the first side of the seat back.

4. The seat belt retractor is equipped with a load limiter that limits the tension of the seat belt, The load at which the load limiter activates is F. Ｌ Let L be the distance from the center of the rotation axis to the upper end of the seat back when the vehicle seat is viewed from the side in the width direction, and let ΔT be the difference between the torque characteristics T1 and T2. ｂａｒＩ－ＩＩ The vehicle seat safety device according to claim 3, characterized in that it is configured such that the following equation holds true. ΔT ｂａｒＩ－ＩＩ ≒F Ｌ ×L

5. The vehicle seat safety device according to claim 4, characterized in that the distance L is the distance from the center of the rotating shaft to the belt extension portion of the seat belt retractor.

6. The safety device for a vehicle seat according to any one of claims 1 to 5, characterized in that the reclining mechanism comprises a worm gear mechanism consisting of a worm wheel connected to the end of the first or second torsion bar opposite to the seat back, and a worm that meshes with the worm wheel.

7. The reclining mechanism comprises a gear member connected to the end of the first or second torsion bar opposite to the seat back, a locking member that restricts the rotation of the gear member, and an adjusting member that releases the engagement between the gear member and the locking member and adjusts the angle of the seat back frame, as described in any one of claims 1 to 5.

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