Vehicle seats

Abstract

The objective is to ensure more appropriate shock absorption in vehicle seats when the rider is leaning backward. [Solution] The support member 30 has a first support portion 31 and a second support portion 32. When the first support portion 31 and the second support portion 32 are unfolded to be continuous in the vertical direction of the seat, the front part of the seat cushion 11 rotates upward toward the upper side of the seat and the seat back 12 tilts backward. In this backward tilted position, a weak portion 60, which is weaker than the other parts of the support member 30, is provided on either the first support portion 31 or the second support portion 32 and is positioned at an intermediate position in the vertical direction of the support member 30.

Description

Technical Field

[0001] The present invention relates to a vehicle seat configured to be able to displace the posture of a seat body on a base portion between a general posture and a reclined posture.

Background Art

[0002] In this type of vehicle seat, a seat body on which an occupant can sit is disposed on a base portion. This seat body has a seat cushion and a seat back, and the seat cushion is arranged such that its seating surface (upper surface) is generally horizontal. And the seat body in the normal state has a posture (general posture) in which the seat back stands up from the rear portion of the seat cushion. Here, the seat body disclosed in Patent Document 1 is configured to be able to be displaced to a reclined posture in which the front portion of the seat cushion is lifted and the seat back is reclined from the viewpoint of ensuring comfort for the occupant. At this time, by tilting the seat cushion and the seat back backward greatly with respect to the base portion, it becomes possible to make the occupant take a reclined comfortable posture like when sleeping. [[ID=…]] [[ID=…]]

[0003] [[ID=…]] By the way, in the field of the vehicle seat described above, various techniques for mitigating the impact applied to the vehicle seat during a vehicle collision have been proposed. For example, the vehicle seat disclosed in Patent Document 2 has a four-bar link structure, and the seat body and the slide rail thereof are connected by links provided at their front and rear portions. In the above-described configuration, the height position of the seat cushion in the general posture can be changed by the vertical rotation of the front and rear links. And by making the rear link vulnerable, when an impact load at the time of rear collision is applied from the seat cushion in the general posture to the link side, the rear link buckles or the like to absorb the impact load.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

[0005] In the field of vehicle seats mentioned above, there is a need to appropriately absorb the impact load applied to the vehicle seat when the passenger is in a reclined position. However, in this field, there is no technology that focuses on impact absorption when the passenger is in a reclined position. For example, the technology described in Patent Document 2 focuses only on the general posture and is therefore not able to appropriately absorb the impact load when the passenger is in a reclined position. The present invention was devised in view of the above points, and the problem that the present invention aims to solve is to more appropriately ensure the impact absorption of vehicle seats when the passenger is in a reclined position. [Means for solving the problem]

[0006] As a means to solve the above problems, the vehicle seat of the first invention is configured such that the seat body in a normal position on the base portion comprises a seat cushion that serves as the seat portion and a seat back that rises from the rear of the seat cushion, so that the position relative to the base portion can be changed. The front portion of the seat cushion is supported by a support member so as to be able to be lifted relative to the base portion, and is able to rotate up and down around a rotation axis provided on the base portion. In this type of vehicle seat, the seat body can be changed to a reclined position, etc., by lifting the front portion of the seat cushion with the support member, but it is desirable to ensure more appropriate shock absorption in this reclined position. Therefore, the support member of the present invention has a first support portion and a second support portion, and by unfolding the first support portion and the second support portion so as to be continuous in the vertical direction of the seat, the front portion of the seat cushion rotates upward toward the upper side of the seat and the seat back tilts backward, resulting in a reclined position. In the reclined position, a weaker part than the other part of the support member is provided on either the first support portion or the second support portion and is positioned at an intermediate position in the vertical direction of the support member. In this invention, the support member and the rotating shaft enable the seat body to be displaced between a normal position and a reclined position. In the reclined position, the weak point provided in the support member midway along the vertical direction of the seat allows for the deformation of one of the support parts to absorb impact loads.

[0007] The vehicle seat of the second invention is a vehicle seat of the first invention in which the first support portion is composed of a link axially connected to the base portion, and the second support portion is composed of a link axially connected to the seat cushion, and the first support portion and the second support portion are axially connected to each other at their respective ends so as to be rotatable. In the present invention, by forming both support portions with links, the configuration is made that helps to secure the vertical expansion amount of both support portions, that is, the desired vertical rotation amount of the seat cushion.

[0008] In the third invention, the vehicle seat is a vehicle seat of the second invention in which the first support portion is made weaker than the second support portion by providing a weak portion. The base portion is provided with a stopper portion that can receive the second support portion in the normal posture, so that the front of the seat cushion in the normal posture is supported only by the second support portion. In the present invention, the stopper portion provided in the base portion allows the front of the seat cushion in the normal posture to be supported by the second support portion, which has relatively high rigidity. When the seat is tilted backward, the front of the seat cushion is supported by both the first and second support portions, and the first support portion can be deformed by the action of the weak portion.

[0009] In the vehicle seat of the fourth invention, the stopper portion is provided directly below or further forward of the seat than the upper shaft portion that axially connects the seat cushion and the second support portion. In the present invention, by positioning the stopper portion appropriately, the front part of the seat cushion in a normal posture can be more appropriately supported by the second support portion, and furthermore, the configuration contributes to securing the vertical expansion amount of both support portions.

[0010] The fifth invention is a vehicle seat in which, in addition to the vehicle seat of either the third or fourth invention, a stopper portion and a drive portion for driving the support member are provided on the base portion side. In this invention, by arranging the components for the support member on the base portion side, it is possible to ensure shock absorption while avoiding complexity of the seat body structure. [Effects of the Invention]

[0011] According to the first invention of the present invention, the shock absorption of a vehicle seat when in a reclined position can be more appropriately ensured. According to the second invention, the posture of the seat body can be more appropriately displaced while ensuring shock absorption when in a reclined position. According to the third invention, both shock absorption when in a reclined position and support when in a normal position can be achieved. According to the fourth invention, the posture of the seat body can be further appropriately displaced while ensuring support when in a normal position. According to the fifth invention, shock absorption when in a reclined position can be ensured while minimizing the complexity of the seat body's structure. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic side view of a vehicle seat in a normal riding position. [Figure 2] This is a schematic side view of a vehicle seat in a reclined position. [Figure 3] This is a schematic front view of a portion of the seat cushion and the base. [Figure 4] This is a schematic enlarged side view of a vehicle seat showing the support members. [Figure 5] This is a schematic perspective view of the first support point. [Figure 6] This is a schematic side view of a vehicle seat subjected to impact load in a reclined position. [Figure 7] This is a schematic enlarged side view of a vehicle seat subjected to impact load. [Modes for carrying out the invention]

[0013] Hereinafter, embodiments for carrying out the present invention will be described with reference to Figures 1 to 7. Each figure appropriately illustrates arrows indicating the front-to-back direction, up-and-down direction (height direction), and left-to-right direction (seat width direction) of the vehicle seat. In each figure, for convenience, the vehicle seat is partially simplified in the illustration, and reference numerals corresponding to the left-side members are given in detail, while reference numerals corresponding to the right-side members are given in a simplified manner.

[0014] [Overview of vehicle seats] First, let's describe the basic structure of the vehicle seat 2 shown in Figure 1. The vehicle seat 2 has a basic configuration consisting of a seat body 10 on which an occupant can sit, and a base part 20 installed on the floor 3 side of the vehicle. The seat body 10 has a seat cushion 11 (seat part) and a seat back 12 (backrest part). The seat cushion 11 is formed in a rectangular shape that is long from front to back when viewed from above, and the seat back 12 is formed in a rectangular shape that is long from top to bottom when viewed from the front. An airbag device 14 can be installed in the front of the seat cushion 11, for example, in front of the hip point, as needed. In the event of a vehicle collision, the airbag body deployed from the airbag device 14 causes the front part of the seating surface of the seat cushion 11 to rise upward.

[0015] As shown in Figure 1, the seat body 10 is mounted on the base 20 and can assume a normal sitting position in which the occupant can sit with their back straight. In this normal sitting position, the lower part of the seat back 12, which is generally upright, is connected to the rear of the seat cushion 11 via a recliner (not shown). The upright position of the seat back 12 means that it can support the back of an occupant who is seated facing forward, and includes not only a vertically upright position but also a slightly reclined position (as shown in Figure 1) that allows the occupant to drive comfortably. The seat body 10 is configured so that the seat cushion 11 and the seat back 12 can be tilted together as a single unit relative to the base 20, which will be described later.

[0016] Further, the base portion 20 shown in FIG. 1 is configured such that the seat body 10 can be slid back and forth in a state of being installed on the floor 3 side. Here, referring to FIGS. 1 and 3, the base portions 20 are respectively disposed on the left side and the right side of the vehicle seat 2 (in FIG. 3, for the sake of convenience, reference numerals corresponding to the left base portion are given, and reference numerals corresponding to the right base portion are given with parentheses). The left and right base portions 20 have a lower rail 21 fixed to the floor 3 side and an upper rail 22 attached to the seat cushion 11 side via a support member 30 and the like to be described later. In the above-described configuration, the upper rail 22 slides back and forth with respect to the lower rail 21, so that the seat cushion 11 slides back and forth with respect to the floor 3. The sliding of the upper rail 22 with respect to the lower rail 21 can be restricted by a slide lock mechanism not shown.

[0017] Then, referring to FIGS. 1 and 2, the vehicle seat 2 is configured such that its seat body 10 can be displaced between a general posture and a reclined posture. That is, the front portion of the seat cushion 11 is supported in a state that it can be lifted by a support member 30 (details will be described later). Further, the front portion of the seat cushion 11 can be rotated up and down about a rotation shaft 40 (details will be described later) provided at the rear portion of the base portion 20. According to the above-described configuration, the seat body 10 is displaced to a reclined posture in which the front portion of the seat cushion 11 is lifted and the seat back 12 is reclined by rotating upward about the rotation shaft 40.

[0018] And in the vehicle seat 2 shown in FIG. 2, it is desirable to more appropriately ensure the shock absorption of the seat body 10 in the reclined posture. Therefore, in the present embodiment, the shock absorption of the vehicle seat 2 in the reclined posture is more appropriately ensured by a configuration (support member 30, rotation shaft 40, stopper portion 51, fragile portion 60, etc.) to be described later. Hereinafter, the configuration of the vehicle seat 2 will be described in detail in the order of the rotation shaft 40, the support member 30 (first support portion 31, second support portion 32, etc.), the stopper portion 51, and the fragile portion 60.

[0019] [Rotation Shaft] First, in the base portion 20 shown in FIG. 1, vertical wall-shaped rear brackets 23 are respectively fixed to the rear portions of the upper apparels 22 on the left and right thereof. Further, a rotating shaft 40 extending in the sheet width direction (left-right direction) is inserted and fixed between the left and right rear brackets 23. And the seat cushion 11 is rotatably shaft-connected to the left and right ends of the rotating shaft 40 at the rear portion of the frame serving as its skeleton. Thereby, in the seat body 10, the front portion of the seat cushion 11 rotates upward (upward rotation) above the seat around the rotating shaft 40 or rotates downward (downward rotation) below the seat around the rotating shaft 40 (see FIGS. 1 and 2).

[0020] [Support member in general posture] Next, the support member 30 shown in FIG. 1 is provided between the front portion of the seat cushion 11 and the base portion 20, and has a first support portion 31, a second support portion 32, and a drive portion 50 (details will be described later). Here, referring to FIGS. 3 and 4, both the first support portion 31 and the second support portion 32 are formed of strip-shaped links. And referring to FIG. 4, in the support member 30 in the general posture, the first support portion 31 is in a state of being generally horizontally tilted forward. Also, the second support portion 32 is in a state of being gradually tilted downward toward the front side of the seat, that is, in a front-downward inclined state. And the front end portion (the upper side in the later-described rearward inclined posture) of the first support portion 31 in this state and the lower end portion of the second support portion 32 are rotatably shaft-connected by a connecting shaft 33.

[0021] Referring to Figures 3 and 4, the base end of the first support portion 31 is axially connected to the upper rail 22 at its rear (lower) end. Specifically, vertical wall-shaped front brackets 24 are fixed to the front of the left and right upper rails 22 on the base portion 20. Lower shaft portions 25 extending in the seat width direction are rotatably inserted through the left and right front brackets 24. By fixing and axially connecting the base end of the first support portion 31 to the end (left end or right end) of the lower shaft portion 25, the first support portion 31 can rotate together with the lower shaft portion 25. The upper base end of the second support portion 32 is rotatably connected to the seat cushion 11. Specifically, a pipe-shaped (rod-shaped) front frame 13 extending in the seat width direction is fixed to the front of the seat cushion 11, and this front frame 13 corresponds to the upper shaft portion of the present invention. The base end of the second support portion 32 is rotatably axially connected to the end (left end or right end) of the front frame 13.

[0022] [Stopper Department] Furthermore, in the general orientation shown in Figure 4, the lower end of the second support portion 32 of the support member 30 is supported by a stopper portion 51 provided on the base portion 20 (for convenience, the second support portion and the stopper portion are shown separately in each figure, but in the actual general orientation they are in contact with each other). The stopper portion 51 is formed in the shape of a rod extending in the seat width direction, as shown in Figures 3 and 4, and its left and right ends are fixed to the upper rail 22 via brackets (not shown). The stopper portion 51 is positioned in front of the seat, relative to the front frame 13 (upper shaft portion), that is, at the position where the tip of the inclined second support portion 32 abuts against it. This allows the tip (lower end) of the second support portion 32 to be supported by the stopper portion 51 when the second support portion 32 is in an inclined position.

[0023] Referring to Figures 3 and 4, the first support portion 31 and the second support portion 32 are configured to be interlocked by the driving force of the drive unit 50. This drive unit 50, which is the source of the drive, is fixed to the upper rail 22 side (for example, the stopper portion 51) via a bracket (not shown). A sector gear 251, which is fan-shaped in side view, is fixed to the left side of the lower shaft portion 25 so as to mesh with the drive shaft 501 of the drive unit 50. The sector gear 251 rotates up and down due to the driving force of the drive unit 50, thereby allowing the lower shaft portion 25 to which the sector gear 251 is fixed to rotate (reverse rotation) relative to the front bracket 24. In this embodiment, the configuration for the support member 30, namely the stopper portion 51 and the drive unit 50 described above, is arranged on the base portion 20 side, thereby avoiding complexity in the configuration on the seat body 10 side.

[0024] Referring to Figures 3 and 4, a support base 52 is provided on the base 20 side at a position where it can receive the seat cushion 11 in its normal position from below. This support base 52 is formed in the shape of a plate extending in the seat width direction and is bent into a hat cross-section when viewed from the front. The support base 52 is fixed to the upper rail 22 side of the base 20 by the lower ends of its left and right vertical plate sections 53 and 54 being fixed to the stopper section 51. Between these left and right vertical plate sections 53 and 54, a substantially flat upper plate section 55 is provided so as to extend in the seat width direction. The upper plate section 55 is positioned directly below the seat cushion 11 in its normal position. As a result, if the front part of the seat cushion 11 tries to descend further from its normal position, the front part of the seat cushion 11 will be supported by the upper plate section 55 of the support base 52.

[0025] [Seat body with reclined posture] Referring to Figures 1 and 2, the drive unit 50 is driven to rotate the lower shaft 25, causing the first support portion 31 fixed to the lower shaft 25 to gradually rotate upward. As a result, the support member 30 expands onto the upper side of the seat in a roughly horizontal V shape when viewed from the side, with the first support portion 31 gradually standing upright and the second support portion 32 pushing upward. By expanding the support member 30 upward in this way, the seat body 10 rotates upward so that the front part of the seat cushion 11 is lifted and the seat back 12 is tilted backward. With the above configuration, the first support portion 31 and the second support portion 32, which are connected in a roughly horizontal V shape, can expand and expand upward, which helps to secure the desired amount of vertical expansion of both support portions, i.e., the desired amount of vertical rotation of the seat cushion 11.

[0026] [Vulnerable parts] Referring to Figures 1 and 2, the first support portion 31 is provided with a weak portion 60 that is weaker than other parts of the support member 30. As a result, the first support portion 31 is weaker than the second support portion 32 and is more easily deformed by externally applied loads. This weak portion 60 can be provided at an appropriate position on the first support portion 31, for example, on the upper side (rear side in the rearward tilted position) of the edge portion 311 of the first support portion 31, based on the normal position. Referring to Figures 4 and 5, the first support portion 31 in the normal position is provided with a notched weak portion 60 in the center in the front-rear direction, which forms a roughly inverted T shape in side view. This weak portion 60 extends downward from the edge portion 311 and then divides into front and rear sections, so that the edge portion 311 side of the first support portion 31 is divided into a first piece 61 on the connecting shaft 33 side and a second piece 62 on the lower shaft portion 25 side that face each other. The first piece 61 bends inward (to the right) in the sheet width direction as it approaches its free end, so that its rear end (first tip 611) is positioned shifted to the right of the first support portion 31. Conversely, the second piece 62 bends outward in the sheet width direction as it approaches its free end, so that its front end (second tip 621) is positioned shifted to the left of the first support portion 31. In the above configuration, as will be described later, even if the second support portion 32 deforms with the weak point 60 as its base point and the first piece 61 and the second piece 62 move in a direction that brings them closer together, the first tip 611 and the second tip 621 are separated to the left and right, making it difficult for them to collide with each other.

[0027] [Function of support members in normal posture] Referring to Figures 1 and 4, in the normal position of the seat body 10, the front of the seat cushion 11 is supported by the support member 30. In this case, the first support portion 31 of the support member 30 tilts forward, so that only the second support portion 32 is positioned between the seat cushion 11 and the base portion 20. The base end (lower end) of the second support portion 32 is received by a stopper portion 51 located in front of the seat, and is supported in a downward-sloping position. Furthermore, since the second support portion 32 does not have a weak point 60, it is more rigid than the first support portion 31. Therefore, with the above configuration, the front of the seat cushion 11 can be stably supported by the downward-sloping second support portion 32. During a vehicle collision (frontal impact), the impact load F applied from the seat cushion 11 side in the normal position can be received more stably by the highly rigid second support portion 32 (for convenience, each figure is labeled with a symbol corresponding to the arrow indicating the direction in which the impact load is applied).

[0028] Referring to Figures 1 and 2, the seat body 10 is displaced into a rearward-tilted position, resulting in a state where it is tilted further back than in the normal position. In this type of seat configuration, it is desirable to ensure more appropriate impact absorption in the rearward-tilted position during a vehicle collision. Therefore, the support member 30 shown in Figure 4 has a first support portion 31 and a second support portion 32. When the first support portion 31 and the second support portion 32 are deployed so as to be continuous in the vertical direction of the seat, the front part of the seat cushion 11 rotates upward toward the upper side of the seat and the seat back 12 is tilted backward. In the rearward-tilted position, a weak point 60, which is weaker than other parts of the support member 30, is provided on either the first support portion 31 or the second support portion 32 and is positioned midway along the vertical direction of the support member 30. In the above configuration, the support member 30 and the rotation axis 40 work together to displace the seat body 10 between the normal position and the rearward-tilted position, and in the rearward-tilted position, the weak point 60 works to absorb the impact load. Therefore, the function of the support member 30 (weak part 60) in the reclined position will be explained in more detail below.

[0029] [Function of support members (weak points) when leaning backward] In the support member 30 shown in Figure 2, when the seat is tilted backward, the first support portion 31 and the second support portion 32 extend upward as described above. As a result, the seat body 10 is tilted backward, with the front part of the seat cushion 11 being lifted (rotating upward) and the seat back 12 tilted backward. When the seat is tilted backward, the aforementioned vulnerable portion 60 is located on the first support portion 31, which is generally upright. As a result, the vulnerable portion 60 is positioned at an intermediate vertical position of the extended support member 30, that is, in the transmission path of the impact load applied from the seat cushion 11 side.

[0030] Referring to Figures 6 and 7, during a vehicle collision, an impact load F is applied from the rearward-tilted seat cushion 11 to the unfolded support member 30 (in Figure 6, for convenience, a symbol corresponding to the arrow indicating the direction in which the impact load is applied is used). At this time, the impact load F is transmitted from the second support part 32 to the first support part 31, causing the first support part 31 to deform into a roughly inverted V shape with the top side as the apex in a side view, with the weak point 60 as the starting point (trigger). This deformation of the first support part 31 makes it possible to absorb the impact load F applied from the seat cushion 11. As the support member 30 shortens due to the deformation of the first support part 31, the front part of the seat cushion 11 is lowered to the underside of the seat, allowing the seat body 10 to return to its normal position during a vehicle collision.

[0031] Thus, in the vehicle seat 2 shown in Figure 6, the support member 30 (weak part 60) allows the inertial load on the object to be released, and the object during a vehicle frontal collision can be supported by the gradually rising seat back 12. By returning the seat body 10 to its normal position during a vehicle frontal collision, the object on the seat body 10 is less likely to slide forward (the submarine effect is less likely to occur). In addition, in the vehicle seat 2, from the viewpoint of suppressing the submarine effect, the front part of the seat cushion 11 can be raised by the action of the airbag device 14. At this time, by returning the seat body 10 to its normal position, the object on the seat body 10 can be received by the raised front part of the seat surface in a state where forward sliding is suppressed.

[0032] Here, the support member 30 shown in Figure 6 can deform while absorbing the impact load F as the front part of the seat cushion 11 rotates downward in the reclined position. The seat body 10 in the reclined position is tilted significantly backward from the normal position, taking into consideration a comfortable position (see angle θ in Figure 6). As a result, the support member 30 has sufficient deformation stroke, and the impact load F is absorbed when the seat body 10 returns to roughly the normal position. Furthermore, even if the seat body 10 is unintentionally lowered further from the normal position, the seat cushion 11 is supported by the receiving base 52 provided on the base part 20, so excessive downward movement of the front part of the seat cushion 11 is suppressed.

[0033] As described above, in this embodiment, the support member 30 and the rotating shaft 40 work together to displace the seat body 10 between a normal position and a reclined position. In the reclined position, the weak point 60 provided in the middle of the support member 30 in the vertical direction of the seat deforms the first support portion 31, making it possible to absorb impact loads. Therefore, according to this embodiment, the impact absorption performance of the vehicle seat 2 in the reclined position can be more appropriately ensured.

[0034] Furthermore, in this embodiment, by forming the first support portion 31 and the second support portion 32 with a link, the configuration helps to secure the desired vertical rotation amount of both support portions, i.e., the vertical rotation amount of the seat cushion 11. Also in this embodiment, the stopper portion 51 provided on the base portion 20 allows the front of the seat cushion 11 in a normal position to be supported by the relatively rigid second support portion 32. When tilted backward, the front of the seat cushion 11 is supported by the first support portion 31 and the second support portion 32, and the first support portion 31 can be deformed by the action of the weak portion 60. Also in this embodiment, by positioning the stopper portion 51 appropriately, the front of the seat cushion 11 in a normal position can be more appropriately supported by the second support portion 32, and the configuration helps to secure the vertical rotation amount of both support portions. Also in this embodiment, by arranging the configuration for the support member 30 on the base portion 20 side, it is possible to ensure shock absorption while avoiding complexity of the configuration on the seat body 10 side.

[0035] The vehicle seat of this embodiment is not limited to the embodiment described above, and can take various other forms. In this embodiment, the configuration of the support member is illustrated, but this is not intended to limit the configuration of the support member. In addition to links, various actuators and cylinders can be used as this type of support member. For example, as a cylinder, a configuration can be adopted in which a rod (made of metal) is housed inside a cylinder tube (made of metal) in a state in which it can protrude, and a weak point can be provided in the rod. In the above configuration, the seat body in a normal position can be supported by the cylinder tube, and the seat body in a reclined position can be supported by the rod with the weak point and the cylinder tube.

[0036] Referring to Figure 1, in the normal position, the second support portion may be extended forward, and the first support portion may be extended vertically downward from a connecting shaft provided at its tip (front end). In this case, a weak point can be provided in the second support portion. The first and second support portions support the seat body in the rearward tilted position, while the first support portion alone supports the seat body in the normal position. In the above configuration, the second support portion may be rotated by the drive unit on the seat body side, and the tip of the first support portion can be received by the stopper portion on the seat body side.

[0037] Furthermore, the configuration of the stopper section can be changed as appropriate, and it can take various shapes such as a rod, vertical wall, or block. The position of the stopper section can also be set as appropriate according to the configuration of each support part, and as long as the amount of extension of the support member can be secured, it can be positioned directly below the front frame (direct position) or further forward of the seat than the direct position.

[0038] Furthermore, the configuration of the weak points can be changed as appropriate. For example, in the first support portion shown in Figure 1 (in the general position), a weak point can be provided on at least one of its upper edge and lower edge. In the first support portion, a weak point is provided at approximately the center in the front-to-back direction (length direction), but the position of this weak point can also be set as appropriate. For example, the first support portion can have weak points at the center, the front end, and the rear end, and it is also possible to have weak points at multiple locations. Various configurations such as holes, slits, beads, and thin-walled sections can be used as weak points. Weak points such as beads and thin-walled sections can be provided so as to be continuous from the upper edge to the lower edge of the support portion. In addition, in the support portion, it is possible to make a section that is bent in the sheet width direction a weak point, or a section made of a low-rigidity material a weak point. In such cases, part or all of the support portion can be made a weak point.

[0039] Furthermore, the configuration of the seat body and base can be modified as appropriate. For example, an airbag device can be provided in the seat body as needed, or it can be omitted. The upper shaft can also be provided separately from the frame. The base does not necessarily have a front-to-back sliding function. When the seat body is installed directly on the floor, the floor portion where it is installed can be considered as the base. The rotation axis on the base side only needs to be configured to allow the front of the seat cushion to rotate up and down, and can pivot at an appropriate position such as the rear or center of the seat body. The support base has a shape and dimensions that can receive the seat cushion in a normal position and can be installed at an appropriate position on the base side, or it can be omitted if not needed. The support base may also be provided on the seat cushion side and configured to be pressed against the base side when in a normal position. The configuration of the vehicle seat in this embodiment can be applied to vehicle seats in general, such as those in cars, aircraft, trains, and ships. [Explanation of Symbols]

[0040] 2. Vehicle seats 3 floors 10 Sheets 11 Seat cushions 12 seatback 13 Front frame (upper shaft portion of the present invention) 14. Airbag system 20 Base section 21 Lower Rail 22 Upper Rail 23 Rear bracket 24 Front Bracket 25 Lower shaft part 30 Support member 31 First support part 311 Edge (of the first support area) 32 Second support part 33 Connecting shaft 40 Rotation axis 50 Drive unit 51 Stopper section 52 Cradle part 53, 54 Vertical board section 55 Upper plate section 60 Vulnerable parts 61 First piece 611 First tip 62 Second piece 621 Second tip 251 Sector Gear 501 Drive shaft

Claims

1. In a vehicle seat, the seat body in a normal position on a base is configured to be able to change its position relative to the base, comprising a seat cushion that serves as the seat portion and a seat back that rises from the rear of the seat cushion, The front portion of the seat cushion is supported by a support member so as to be able to be lifted relative to the base portion, and is therefore able to rotate up and down around a rotation axis provided on the base portion. The support member has a first support portion and a second support portion, and when the first support portion and the second support portion are unfolded so as to be continuous in the vertical direction of the seat, the front part of the seat cushion rotates upward toward the upper side of the seat and the seat back is tilted backward. A vehicle seat in which, in the aforementioned reclined posture, a weaker portion than the other parts of the support member is provided in either the first support portion or the second support portion, and is positioned at an intermediate position in the vertical direction of the support member.

2. The first support portion is composed of a link axially connected to the base portion, and the second support portion is composed of a link axially connected to the seat cushion. The vehicle seat according to claim 1, wherein the first support portion and the second support portion are axially connected to each other at their respective ends so as to be rotatable.

3. The first support portion is made weaker than the second support portion by the provision of the weak portion. The vehicle seat according to claim 2, wherein the base portion is provided with a stopper portion that can receive the second support portion in the normal posture, so that the front portion of the seat cushion in the normal posture is supported only by the second support portion.

4. The vehicle seat according to claim 3, wherein the stopper portion is provided directly below or further forward of the seat than the upper shaft portion that axially connects the seat cushion and the second support portion.

5. The vehicle seat according to claim 3 or 4, wherein the stopper portion and the drive portion for driving the support member are provided on the base portion side.

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