JP2012041000A - Vehicle seat - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle seat that can effectively inhibit or alleviate whiplash injury of occupant's cervical vertebrae, while being able to achieve weight saving.SOLUTION: In the vehicle seat 10, a diagonally stretched wire 46 arranged at side of a frame 26 of a backseat frame 14 connects between an upper end side and a lower end side of the backseat frame 14 in a tensioned state. The diagonally stretched wire 46 is given tensile force when the load to the rear side is given to the backseat frame 14, and the backseat frame 14 is made highly rigid. A lower end of the diagonally stretched wire 46 is locked to the base 30 of the backseat frame 14 through a tensile force reducer 54, and when the tensile force which acts on the diagonally stretched wire 46 exceeds a predetermined threshold, the lower end of the diagonally stretched wire 46 is moved towards the upper end side of the diagonally stretched wire 46. Thereby the tensile force which acts on the diagonally stretched wire 46 is reduced, and the backseat frame 14 is made low rigid.

Description

  The present invention relates to a vehicle seat.

  2. Description of the Related Art Conventionally, a vehicular seat is known that reduces whipping injury of a passenger's neck (see, for example, Patent Document 1).

  In addition, the applicant of the present invention prevents or reduces the lashing injury of the occupant's neck by increasing the rigidity of the back seat frame with a wire, and reduces the weight of the vehicle seat. A frame structure is proposed. In this back seat frame structure, wires arranged on the side of the side frame of the back seat frame are stretched between the upper end side and the lower end side of the back seat frame. The wire is positioned so that a tensile force is applied when a load on the vehicle rear side is applied to the back seat frame. Thereby, a part of the load is supported by the wire, and the bending moment of the side frame is reduced. On the other hand, the above-described wire is positioned so as to be loosened when a load on the vehicle front side is applied to the back seat frame. Thereby, the wire does not function as a strength member, and the structural soundness of the wire itself is maintained.

  In such a back seat frame structure, regarding the assumed impact load applied to the back seat frame in the event of a vehicle collision, the impact load applied to the vehicle rear side is more than the impact load applied to the vehicle front side. When it is set to a large value, the sectional modulus of the side frame is set to withstand the bending moment due to the impact load applied to the front side of the vehicle, and the sectional shape is determined. As a result, the difference between the impact load on the front side of the vehicle and the impact load on the rear side of the vehicle can be borne by the wire, and the rigidity of the side frame can be reduced, thereby reducing the mass of the side frame. It becomes possible to do.

  In addition, since the back seat frame is made highly rigid by the wire, the back seat frame is prevented from being tilted backward at the time of a rear collision of the vehicle (hereinafter referred to as “rear collision”). Thereby, since the time until the head of the occupant hits (supports) the headrest is shortened, it is possible to prevent or reduce the lashing injury of the occupant's neck.

JP 2006-56515 A

  By the way, after the passenger's head hits the headrest as described above, the head rebounds to the vehicle front side by the reaction. If the rebound speed of the head at this time is high, cervical lashing injury may be caused. For this reason, in order to effectively prevent or reduce whipping injury of the cervical spine, it is necessary to reduce the rebound speed as described above.

  In consideration of the above facts, the present invention has an object to provide a vehicle seat that can be reduced in weight and can effectively prevent or reduce whipping injury of the cervical spine of an occupant.

  The vehicle seat according to the first aspect of the present invention has a pair of left and right side frames disposed on the left and right side portions of the seat back, and each lower end portion of the pair of side frames is provided on the seat cushion. A back seat frame coupled to the cushion seat frame and having a headrest coupled to the upper end portion, and disposed on the side of the side frame and stretched between the upper end side and the lower end side of the back seat frame, A wire to which a tensile force is applied when a load on the back side is applied to the back seat frame, and provided on the back seat frame on one side of the upper end portion and the lower end portion of the wire, While facing each other in a direction intersecting with the direction in which the tensile force acts, the facing interval becomes narrower toward the other of the upper end and the lower end. A pair of locking surfaces and the one are locked and disposed between the pair of locking surfaces, and the movement to the other side is restricted by contacting the pair of locking surfaces. And a moving member that is deformed by the reaction force from the pair of locking surfaces and is moved to the other side when the tensile force exceeds a predetermined threshold value.

  In the vehicle seat according to the first aspect, the wire disposed on the side of the side frame of the back seat frame is stretched between the upper end side and the lower end side of the back seat frame. This wire is given a tensile force between the upper end side and the lower end side of the back seat frame when a rearward load is applied to the back seat frame (for example, at the time of rear-end collision of the vehicle). The Thereby, a part of the load is supported by the wire, and the back seat frame is highly rigid, so that the back tilt of the back seat frame is suppressed. As a result, the time until the head of the occupant hits the headrest can be shortened, so that the lashing injury of the occupant in the initial stage of the rear collision can be prevented or reduced.

  And since the load to the back side loaded on a back seat frame can be borne on a wire, the rigidity of a side frame can be reduced. Thereby, the mass of the side frame can be reduced, and as a result, the weight of the vehicle seat can be reduced.

  Further, one of the upper end portion and the lower end portion of the wire described above is locked to a moving member, and the moving member is disposed between a pair of locking surfaces provided on the side frame. The pair of locking surfaces face each other in a direction intersecting the direction of the tensile force acting on the wire, and the facing interval is narrowed toward the other side of the upper end portion and the lower end portion of the wire, The moving member is restricted from moving to the other side by contacting the pair of locking surfaces. When the tensile force acting on the wire exceeds a predetermined threshold value, the moving member is deformed by the reaction force from the pair of locking surfaces and moved to the other side. Accordingly, one of the upper end portion and the lower end portion of the wire, which is locked by the moving member, is moved to the other side, and the tensile force acting on the wire is gradually reduced. As a result, the back seat frame is lowered in rigidity and tilted backward, and the head of the occupant is moved backward while being supported by the headrest. At this time, since the occupant's energy is absorbed by the deformation of the cam, the rebound speed of the occupant's head caused by the recoil reaction can be reduced. Thereby, it is possible to effectively prevent or reduce the lashing injury of the occupant in the final stage of the rear collision.

  Furthermore, in this invention, since the moving member in which one of the upper end portion and the lower end portion of the wire is locked is deformed by receiving a direct reaction force from the pair of locking surfaces, for example, the moving member moves with the pair of locking surfaces. Compared to a configuration in which a steel ball is interposed between the members, the manufacturing process of the vehicle seat can be simplified.

  A vehicle seat according to a second aspect of the present invention is the vehicle seat according to the first aspect, wherein the moving member has a protrusion protruding toward the locking surface, and a tip of the protrusion is the The movement to the other side is restricted by contact with the locking surface, and the projection is deformed by the reaction force from the locking surface when moved to the other side. Yes.

  In the vehicle seat according to claim 2, the tip of the protrusion provided on the moving member comes into contact with the locking surface of the side frame, so that the wire moves to the other of the upper end portion and the lower end portion. The movement of the member is restricted. When the tensile force acting on the wire exceeds a predetermined threshold, the protrusion of the moving member is deformed by the reaction force from the locking surface, and the moving member is moved to the other side. As described above, since the protrusion provided on the moving member is deformed, the relationship between the tensile force acting on the wire and the moving amount of the moving member can be easily adjusted by appropriately changing the shape of the protrusion. . Thereby, the relationship (load characteristic) between the load to the back side loaded on the back seat frame and the amount of displacement to the back side of the back seat frame can be easily adjusted.

  A vehicle seat according to a third aspect of the present invention is the vehicle seat according to the second aspect, wherein the moving member is moved to the other side when the tip of the protrusion is in line contact with the locking surface. The projection is formed so that the cross-sectional area becomes larger toward the base end side.

  In the vehicle seat according to claim 3, when the tip of the protrusion provided on the moving member is in line contact with the locking surface of the side frame, the wire moves to the other of the upper end portion and the lower end portion of the wire. The movement of the member is restricted. Since this protrusion is formed so that the cross-sectional area increases toward the base end side, when the moving member is moved along with the deformation of the protrusion, the contact portion between the tip of the protrusion and the locking surface Changes from line to surface, and the load required to deform the protrusion gradually increases. Thereby, since the load required for moving the moving member can be gradually increased, the tensile force acting on the wire can be gradually reduced. Thereby, since the rigidity of a back seat frame can be reduced gently, the back inclination of the back seat frame accompanying the reduction in the rigidity can be made smooth.

  According to a fourth aspect of the present invention, there is provided the vehicle seat according to the second aspect, wherein the moving member is moved to the other side when a tip end of the protrusion comes into surface contact with the locking surface. It is characterized by being restricted from moving.

  In the vehicle seat according to claim 4, the movement member moves to the other side of the upper end portion and the lower end portion of the wire when the tip of the protrusion provided on the movement member is in surface contact with the locking surface. Is regulated. Thus, since the tip of the projection is in surface contact with the locking surface from the beginning, the reaction force input from the locking surface to the tip of the projection can be dispersed. As a result, the initial load required to deform the protrusion can be set large, so that when the load on the back side of the back seat frame is loaded, the tensile force acting on the wire is quickly increased. The back seat frame can be made highly rigid quickly. Therefore, this is particularly effective when, for example, the rear impact speed of the vehicle is high.

  As described above, the vehicle seat according to the first aspect of the invention can reduce the weight and can effectively prevent or reduce the whipping injury of the cervical vertebra of the occupant.

  In the vehicle seat according to the second aspect of the present invention, the relationship (load characteristics) between the rearward load applied to the back seat frame and the rearward displacement amount of the back seat frame is easily adjusted. be able to.

  In the vehicle seat according to the third aspect of the present invention, the rearward inclination of the back seat frame accompanying the reduction in the rigidity of the back seat frame can be made smooth.

  In the vehicle seat according to the fourth aspect of the invention, the back seat frame can be rapidly made highly rigid when a load is applied to the back seat frame toward the rear side.

It is a perspective view which shows the structure of the principal part of the vehicle seat which concerns on 1st Embodiment of this invention. It is a side view of the back seat frame shown by FIG. It is a disassembled perspective view which shows the structure of the tensile force reduction means shown by FIG.1 and FIG.2. It is a perspective view of the cam which comprises the tensile-force reduction means shown by FIG. 3 shows the configuration of the main part of the tensile force reducing means shown in FIG. 3, wherein (A) is a side view showing a state in which the cam is restricted from moving upward, and (B) is the cam moving upward. It is a side view which shows the state made. It is a diagram which shows the relationship between the load to the back side loaded to the back seat frame shown by FIG.1 and FIG.2, and the displacement to the back side of a back seat frame. It is a side view which shows the structure of the comparative example of the tensile force reduction means which concerns on 1st Embodiment of this invention. It is a perspective view of the cam which is a structural member of the vehicle seat which concerns on 2nd Embodiment of this invention.

<First Embodiment>
Hereinafter, with reference to FIGS. 1-7, the vehicle seat 10 which concerns on 1st Embodiment of this invention is demonstrated. In addition, arrow FR, arrow UP, and arrow W, which are appropriately shown in the drawings, respectively indicate the front direction, the upper direction, and the width direction of the vehicular rear seat 10. Further, in the present embodiment, the front direction, the upper direction, and the width direction of the vehicle rear seat 10 substantially coincide with the front direction, the upper direction, and the width direction of the vehicle on which the vehicle rear seat 10 is mounted.

  As shown in FIG. 1, the vehicle seat 10 according to the present embodiment includes a cushion seat frame 12 constituting a skeleton of a seat cushion and a back seat frame 14 constituting a skeleton of a seat back. The cushion seat frame 12 is connected to the floor of the passenger compartment, and the back seat frame 14 is connected so that the lower end portion thereof can tilt with respect to the rear end portion of the cushion seat frame 12. The cushion seat frame 12 and the back seat frame 14 are each provided with a pad (both not shown) covered with a skin. In addition, the XX line of FIG. 1 has shown the rotating shaft line of the back seat frame 14 with respect to the cushion seat frame 12. FIG.

  The cushion seat frame 12 includes a pair of left and right side frames 16 extending in the front-rear direction of the vehicle, a front frame 18 that connects the front ends of the pair of side frames 16, and the rear ends of the pair of side frames 16. And a pair of bases 22 fixed to the rear ends of the pair of side frames 16, and these frames form a closed cross-sectional structure (box structure). A cushion spring 24 that is stretched in the front-rear direction of the vehicle is provided between the front frame 18 and the rear frame 20 at the opening of the closed cross-sectional structure.

  On the other hand, the back seat frame 14 is disposed on the left and right side portions of the seat back, and is spanned between a pair of left and right side frames 26 extending in the vertical direction of the seat back and upper ends of the pair of side frames 26. The upper frame 28 and a pair of left and right bases 30 fixed to the lower ends of the pair of side frames 26 are formed in an inverted U shape as a whole.

  The pair of side frames 26 are formed in a U-shaped cross section (substantially U-shaped in cross section) that opens toward the inside in the seat width direction. Further, both lower ends of the upper frame 28 are formed in a U-shaped cross section like the pair of side frames 26, and are respectively fitted and connected to the upper ends of the pair of side frames 26. Further, the pair of bases 30 fixed to the lower ends of the pair of side frames 26 are overlapped with the pair of bases 22 provided on the cushion seat frame 12 on the inner side in the seat width direction. These bases 22 and 30 constitute a known recliner mechanism 32, and are connected via a recliner rod 34, a gear (not shown), and the like.

  A flat mat 36 is stretched between the pair of side frames 26, and an upper member 38 that connects the upper ends of the pair of side frames 26 and a lower member 40 that connects the lower ends of the pair of side frames 26. Is provided. A headrest support 44 for connecting a headrest frame 42 constituting the headrest skeleton is attached to an upper end portion of the upper frame 28.

  An oblique wire 46 (wire) is disposed on the side of each side frame 26 (outside in the seat width direction). As shown in FIG. 2, the slanted wire 46 is disposed in an inclined state with respect to the side frame 26, and is stretched between the upper end side and the lower end side of the back seat frame 14. More specifically, the cable-drawn wire 46 is formed in an endless shape, and its length can be finely adjusted by a bolt-nut mechanism 48 provided in an intermediate portion. The upper end portion of the cable 46 is wound around a pulley 50 fixed to a fitting overlap portion 27 (a structurally reinforced portion) between the upper end portion of the side frame 26 and the lower end portion of the upper frame 28. . The lower end portion of the cable 46 is wound around a pulley 52 attached to the front end side of the upper end portion of the base 30, and on the front side of the seat relative to the center of rotation of the back seat frame 14 relative to the cushion seat frame 12. Is arranged.

  For this reason, when a rearward load is applied to the back seat frame 14, the slanted wire 46 is pulled between the pulleys 50 and 52. For example, when a load from an occupant who intends to move to the rear side of the vehicle at the time of a rear collision of the vehicle (hereinafter referred to as “rear collision”) is applied to the back seat frame 14, And a part of the load is supported by the tensile rigidity or the tensile strength of the cable wire 46. Thereby, the bending moment which acts on the side frame 26 is reduced, and the back seat frame 14 is made highly rigid.

  On the other hand, when a load on the front side of the vehicle is applied to the back seat frame 14, the cable 46 is compressed and slackened between the pulleys 50 and 52. In this case, since the cable wire 46 does not function as a strength member, the loaded load is supported by the side frame 26 or the like. In other words, the cable wire 46 has a characteristic that does not resist a compressive force acting from the outside due to a load applied to the back seat frame 14 toward the front side of the vehicle.

  Note that the inclination angle of the cable 46 with respect to the side frame 26 may be appropriately set according to an assumed impact load or the like. Further, the cable is connected so that the line connecting the upper end of the cable staying wire 46 and the rotation center of the back seat frame 14 and the line connecting the lower end of the cable staying wire 46 and the rotation center of the back seat frame 14 are as perpendicular as possible. The wire 46 is preferably positioned. Also, the type and material of the cable 46 are, for example, when a shock load is applied to the vehicle seat 10 in the event of a collision, and the structural integrity of the cable itself is borne by itself while bearing a part of the impact load. Although it is arbitrary as long as it has strength or rigidity that can be secured, it is preferably made of metal or CFRP, for example.

  On the other hand, as shown in FIG. 3, the base 30 of the back seat frame 14 is provided with tensile force reducing means 54. The tensile force reducing means 54 gradually reduces the tensile force acting on the cable wire 46 by moving the lower end portion of the cable wire 46 toward the upper end portion. The tensile force reducing means 54 includes a cam 56 (moving member) interposed between the base 30 and the pulley 52. Through holes 58 and 60 are formed in the pulley 52 and the cam 56, and bolts 62 are inserted into the through holes 58 and 60, respectively. The front end side of the bolt 62 is inserted into a through hole 66 formed in the spacer 64 and screwed into a nut 68. Accordingly, the pulley 52 is fixed so as not to rotate relative to the cam 56, and the pulley 52 and the spacer 64 prevent the cam 56 from dropping from the base 30. Note that a cover 70 is attached to the bolt 62 to prevent the cable 46 from falling off the pulley 52.

  As shown in FIG. 4, the above-described cam 56 is a long plate-like member formed in a substantially inverted T shape, with the upper side being a narrow portion 56A and the lower side being more narrow than the narrow portion 56A. The wide portion 56B is wide. From the center part of the lower end of the wide part 56B, the protrusion part 56C is extended toward the downward side. As shown in FIG. 5A, the cam 56 is disposed inside a long hole-shaped through hole 72 formed in the base 30. The through hole 72 has an upper portion as a narrow portion 72A and a lower portion as a wide portion 72B wider than the narrow portion 72A. The wide portion 56B of the cam 56 is fitted to the lower side of the wide portion 72B, and the upper side of the narrow portion 56A of the cam 56 is fitted to the lower side of the narrow portion 72A. In addition, a notch 72C is formed in the central portion on the lower end side of the wide width portion 72B, and the protruding portion 56C of the cam 56 is fitted in the notch 72C.

  The cam 56 and the through hole 72 are arranged so that the longitudinal direction thereof coincides with the direction in which the tensile force acts on the cable wire 46 (the extending direction of the cable wire 46; see the arrow T in FIG. 2). The cam 56 and the through-hole 72 are formed in a line-symmetric shape, and are arranged so that the line-symmetrical axis coincides with the direction in which the tensile force acting on the oblique wire 46 is applied. Thus, when the tension force of the cable 46 is applied to the cam 56 via the pulley 52, all the tension force is applied to the cam 52.

  A pair of guide surfaces 74 are provided on the inner periphery of the narrow width portion 72 </ b> A of the through hole 72 so as to face each other in a direction orthogonal to the direction in which the tensile force acting on the cable 46 is applied. The pair of guide surfaces 74 are formed in parallel to each other along the direction of the tensile force acting on the cable wire 46, and are slidable on the side surface (guided surface) of the narrow portion 56A of the cam 56. It is in contact.

  A pair of guide surfaces 76 are provided on the inner periphery of the cutout portion 72 </ b> C of the through-hole 72 so as to face each other in a direction orthogonal to the direction in which the tensile force acting on the oblique wire 46 acts. The pair of guide surfaces 76 are formed in parallel to each other along the direction of the tensile force acting on the cable wire 46, and are slidably applied to the side surface of the projecting portion 56C (guided surface) of the cam 56. Touching.

  Furthermore, a pair of locking surfaces 78 (inclined surfaces) are provided on the inner periphery of the wide portion 72B of the through-hole 72 so as to face each other in a direction orthogonal to the direction in which the tensile force acting on the cable 46 is applied. The pair of locking surfaces 78 are inclined so that the distance between the opposing surfaces becomes narrower toward the upper end portion of the cable-stayed wire 46, and are formed in a convex curved shape toward the cam 56. The pair of locking surfaces 78 correspond to a pair of protrusions 56 </ b> D (planned deformation portions) provided on the cam 56.

  The pair of protrusions 56 </ b> D are provided at both ends in the width direction on the upper end side of the wide width portion 72 </ b> B and project toward the pair of locking surfaces 78. Each protrusion 56D is formed in a semicircular shape when viewed from the thickness direction of the cam 56, and its cross-sectional area increases as it goes from the distal end side to the proximal end side. The outer periphery of each protrusion 56D is formed in a circular arc shape (curved shape like a part of the outer peripheral surface of the cylinder), and the tip of each protrusion 56D is in line contact with the lower side of each locking surface 78. .

  Here, since each locking surface 78 is inclined so as to approach the cam 56 toward the upper side, the tip of each projection 56D is in line contact with the lower side of each locking surface 78. Therefore, the upward movement is restricted. For this reason, even when a tensile force is applied to the cable 46 and the tensile force is transmitted to the cam 56 via the pulley 52, each projection 56D of the cam 56 receives a reaction force from each locking surface 78. Thus, the movement of the cam 56 and the pulley 52 is restricted (by the locking surfaces 78 acting like wedges).

  However, the cam 56 is formed of a material having a lower hardness than the material of the base 30. When the tensile force acting on the cable 46 exceeds a predetermined threshold, each projection 56D of the cam 56 is engaged with each locking surface 78. It is plastically deformed (crushed) by the reaction force received from it. As a result, the cam 56 starts to move toward the upper end side of the cable tension wire 46 by the tensile force of the cable tension wire 46 transmitted through the pulley 52. At this time, in the cam 56, the side surface of the narrow portion 56A on the upper end side is in sliding contact with the guide surface 74, and the side surface of the projecting portion 56C on the lower end side is in sliding contact with the guide surface 76. As a result, the cam 56 is stably guided in the moving direction, and the cam 56 and the pulley 52 are moved toward the upper end of the cable wire 46 along the direction in which the tensile force of the cable wire 46 is applied. As a result, the tensile force acting on the cable wire 46 is gradually reduced, and the rigidity of the back seat frame 14 is reduced.

  5B, when the upper end surface 56E of the cam 56 contacts the upper end surface 72D of the through hole 72, the upward movement of the cam 56 and the pulley 52 is restricted again. As a result, the tensile force acting on the cable wire 46 is increased again, and the back seat frame 14 is made highly rigid again.

  As a material of the cam 56, for example, S45C (carbon steel) can be adopted, and as a material of the base 30, for example, SCM415 (chrome molybdenum steel) can be adopted.

  In addition, the inclination angle (indicated by α in FIG. 5A) of the locking surface 78 with respect to the direction in which the tensile force acting on the cable 46 is applied is such that the occupant's head hits the headrest at the time of rear-end collision of the vehicle. After that, it is necessary to determine so as to gradually reduce the tensile force acting on the cable wire 46 until the head starts to rebound forward from the headrest.

  Specifically, when the inclination angle α is increased, the wedge action is strengthened and the predetermined threshold value of the tensile force is increased. In particular, when an initial tensile force is applied to the cable 46 by the bolt-nut mechanism 48, the inclination angle α is determined according to the initial tensile force, the assumed collision load due to the rear impact of the vehicle, and the hardness of the cam. Is good.

  Further, since each locking surface 78 is formed in a convex curved shape toward the cam 56, the resistance to the movement decreases as the cam 56 moves toward the upper end of the cable wire 46. As a result, it is possible to gradually reduce the tensile force acting on the cable wire 46. The pair of locking surfaces 78 can adopt various forms as long as the pair of locking surfaces 78 have inclined portions that are inclined so as to approach each other toward the upper end of the cable-stayed wire 46.

  Next, the operation and effect of this embodiment will be described.

  When the vehicle collides from the rear (rear collision), the rearward load applied to the back seat frame 14 of the vehicle seat 10 and the rearward displacement of the back seat frame 14 (shown in FIG. 2). The relationship with “frame displacement” is shown in FIG.

  That is, in FIG. 6, the back seat frame 14 is highly rigid by the tensile force acting on the cable tension wire 46 until the frame displacement a is reached after the occurrence of the collision, and the cable tension wire 46 from the frame displacement a to the frame displacement b. The back seat frame 14 is reduced in rigidity by gradually reducing the tensile force acting on the back seat frame 14. When the frame displacement b is exceeded, the back seat frame 14 is increased in rigidity again.

  More specifically, from the occurrence of the collision until the frame displacement a is reached, the cam 56 tries to move toward the upper end of the cable wire 46 by the tensile force acting on the cable wire 46, thereby causing a pair of cams 56. The protrusion 56D is pressed against the pair of locking surfaces 78, but the cam 56 is restricted from moving upward by the reaction force from the pair of locking surfaces 78 until the pair of protrusions 56D are deformed. In this state, the tensile force acting on the cable wire 46 is not reduced, and the back seat frame 14 is highly rigid. Thereby, the backward inclination of the back seat frame 14 in the initial stage of the collision is suppressed, and the head of the occupant is quickly supported by the headrest. Thereby, it is possible to prevent or reduce the lashing injury of the occupant's neck in the initial stage of the collision.

  Next, when the frame displacement a is exceeded, the tensile force acting on the cable tension wire 46 exceeds a predetermined threshold value, so that the pair of protrusions 56D of the cam 56 begins to be plastically deformed, thereby causing the wedge action of the pair of locking surfaces 78. I can't speak. As a result, the cam 56 begins to move toward the upper end of the cable wire 46, and the tensile force acting on the cable wire 46 is reduced. At that time, since the locking surface 78 is inclined with respect to the direction of application of the tensile force and is convex toward the cam 56, the resistance to the movement is reduced as the cam 56 moves, whereby the tensile force is reduced. Is gradually reduced. As a result, the back seat frame 14 is reduced in rigidity, so that the occupant's head can be moved rearward together with the headrest until the headrest is rebounded by the reaction of the rearward movement while being supported from the rear by the headrest. It becomes possible. Thereby, compared with the case where the back seat frame 14 is not reduced in rigidity, the impact on the head of the occupant is relieved, and the rebound speed when rebounding to the front side of the vehicle is reduced. Therefore, it is possible to prevent or reduce the lashing injury of the occupant's neck even at the end of the collision.

  Next, when the frame displacement b is exceeded, the upper end surface 56E of the cam 56 comes into contact with the upper end surface 72D of the through-hole 72, thereby restricting the upward movement of the cam 56 again. As a result, the tensile force acting on the cable wire 46 increases again, and the back seat frame 14 becomes highly rigid again.

  As described above, according to the vehicle seat 10 according to the present embodiment, it is possible to effectively prevent the occupant's whipping injury in the initial stage of the rear collision, and also effectively prevent the lashing injury of the occupant in the final stage of the rear collision. be able to. In addition, since the rearward load applied to the back seat frame 14 can be borne by the slanted wire 46, the rigidity of the side frame 26 can be reduced. Thereby, the mass of the side frame 26 can be reduced, and as a result, the weight of the vehicle seat 10 can be reduced.

  Furthermore, in this vehicle seat 10, the cam 56 in which the lower end portion of the cable staying wire 46 is locked is plastically deformed by receiving a direct reaction force from the pair of locking surfaces 78, as shown in FIG. Compared to the configuration in which the steel ball 74 is interposed between the cam 56 and the pair of locking surfaces 78, the manufacturing process can be simplified.

  That is, in the configuration shown in FIG. 7 (comparative example), the pair of steel balls 74 is pushed by the pair of locking surfaces 78 and bites into the side surfaces of the cam 56, thereby allowing the cam 56 to move upward. Thereby, basically the same effect as the present embodiment can be obtained, but in such a configuration, the cam 56 and a small pair of steel balls 74 are set in the through hole 72 of the back seat frame 14, and these This requires a detailed manufacturing operation of attaching a cover (not shown) for preventing the steel balls 74 from dropping off, and the manufacturing process becomes complicated. Moreover, since the presence or absence of the steel ball 74 cannot be confirmed unless the above-mentioned cover is removed, there is a problem that the inspection process becomes complicated and is not suitable for mass production.

  In this respect, the vehicle seat 10 can omit the fine manufacturing work as described above, and does not require an inspection process for confirming the presence or absence of the steel ball 74. Therefore, the vehicle seat 10 is easy to manufacture and suitable for mass production. A vehicle seat can be provided.

  In the present embodiment, since the protrusion 56D provided on the cam 56 is plastically deformed, the setting of the shape of the protrusion 56D is appropriately changed, so that the tensile force acting on the cable 56 and the amount of movement of the cam 56 are reduced. The relationship can be easily adjusted. Thereby, it is possible to easily adjust the relationship (load characteristic) between the rearward load applied to the back seat frame 14 and the frame displacement.

  Moreover, since the projection 56D is deformed while being in sliding contact with the locking surface 78, for example, the load characteristics can be stabilized by setting the projection 56D to be scraped from the tip side by the sliding contact. That is, in the case of the comparative example shown in FIG. 7, when the steel ball 74 bites into the cam 56, the cam 56 is compressed and deformed, so that the reaction force from the cam 56 acts to push the through hole 72 in the width direction. End up. As a result, when the width dimension of the through-hole 72 changes, it becomes difficult to obtain load characteristics as set, but this can be avoided in the present embodiment. In addition, the hardness of the material of the cam 56 may vary depending on the location. However, since the steel ball 74 may inadvertently move in the thickness direction of the cam 56, the load due to the influence of the variation as described above. Although the characteristics may not be stable, this embodiment can also solve such a problem.

Further, in the present embodiment, the tip of the projection 56D provided on the cam 56 is in line contact with the locking surface 78 of the side frame, so that the movement of the cam 56 toward the upper end side of the oblique wire 46 is restricted. . Since the protrusion 56D is formed to have a cross-sectional area that increases toward the base end side, when the cam 56 is moved along with the deformation of the protrusion 56D, the distal end of the protrusion 56D and the locking surface 78 are moved. The contact portion changes from a line to a surface, and the load necessary to deform the projection 56D gradually increases. As a result, the load necessary to move the cam 56 can be gradually increased, so that the tensile force acting on the cable wire 46 can be gradually reduced. Thereby, since the rigidity of the back seat frame 14 can be gradually reduced, the back inclination of the back seat frame 14 accompanying the reduction in the rigidity can be made smooth.
<Second Embodiment>
Next, a second embodiment of the present invention will be described. In addition, about the structure and effect | action similar to the said 1st Embodiment, the same code | symbol as the said 1st Embodiment is provided, and the description is abbreviate | omitted.

  FIG. 8 is a perspective view of a cam 56 that is a constituent member of the vehicle seat according to the second embodiment. In this embodiment, the tip of the protrusion 56D provided on the cam 56 is provided with an abutment surface 56F that comes into surface contact with a locking surface 78 (not shown in FIG. 8). The configuration is the same as that of the first embodiment.

  In this embodiment, the tip (abutment surface 56F) of the projection 56D provided on the cam 56 is in surface contact with the locking surface 78, so that the cam 56 moves toward the upper end side of the oblique wire 46. Be regulated. As described above, since the tip of the projection 56D is in surface contact with the locking surface 78 from the beginning, the reaction force input from the locking surface 78 to the tip of the projection 56D is dispersed. This makes it possible to set a large initial load necessary for deforming the protrusion 56D, so that when the load on the back seat frame 14 is loaded on the back seat frame 14, the tension acting on the cable tension wire 46 is applied. The force can be increased quickly, and the back seat frame 14 can be rapidly increased in rigidity. Therefore, this is particularly effective when, for example, the rear impact speed of the vehicle is high.

  In the first embodiment, the upward movement of the cam 56 is restricted when the tip of the projection 56D of the cam 56 is in line contact with the locking surface 78. In the second embodiment, the cam 56 According to the first and second aspects of the present invention, the cam 56 is prevented from moving upward by the contact surface 56F formed at the tip of the projection 56D of the 56 being in surface contact with the locking surface. The invention is not limited to this, and the tip of the projection 56 may be point-contacted with the locking surface 78 to restrict the upward movement of the cam 56.

  In the first embodiment and the second embodiment, the projection 56 (deformation scheduled portion) provided on the cam 56 is deformed by the reaction force from the locking surface 78. The invention which concerns is not restricted to this, The shape of the deformation | transformation scheduled part of the cam 56 can be changed suitably.

  Further, in the first embodiment and the second embodiment, the cam 56 (which constitutes the tensile force reducing means 54 between the lower end of the cable 46 and the base 30 (the lower end side of the back seat frame 14). However, the invention according to claims 1 to 4 is not limited thereto, and the upper end portion of the slanted wire 46 and the upper end side of the back seat frame 14 are provided. The moving member constituting the tensile force reducing means and the pair of locking surfaces may be provided between the two.

  In addition, the present invention can be implemented with various modifications without departing from the scope of the invention. Needless to say, the scope of rights of the present invention is not limited to the above embodiments.

10 Vehicle Seat 14 Back Seat Frame 26 Side Frame 46 Cable Wire
56 Cam (moving member)
56D Protrusion 78 Locking surface

Claims (4)

It has a pair of left and right side frames disposed on the left and right sides of the seat back, each lower end of the pair of side frames is connected to a cushion seat frame provided on the seat cushion, and a headrest is provided at the upper end. A connected back seat frame;
It is arranged on the side of the side frame and is stretched between the upper end side and the lower end side of the back seat frame, and gives a tensile force when a load on the back side is applied to the back seat frame. Wire to be
The wire is provided on the back seat frame on one side of the upper end portion and the lower end portion of the wire, and is opposed to each other in a direction intersecting with the direction in which the tensile force is applied, and the other of the upper end portion and the lower end portion. A pair of locking surfaces whose facing interval becomes narrower toward the side,
The one side is locked and disposed between the pair of locking surfaces, and the movement to the other side is restricted by contacting the pair of locking surfaces, and the tensile force is a predetermined threshold value. A moving member that is deformed by the reaction force from the pair of locking surfaces and is moved to the other side,
Vehicle seat equipped with   The moving member has a protrusion protruding to the side of the locking surface, and the tip of the protrusion is restricted from moving to the other side by contacting the locking surface, and the other side The vehicle seat according to claim 1, wherein the protrusion is deformed by a reaction force from the locking surface when moved to a position.   The moving member is restricted from moving to the other side when the tip of the protrusion comes into line contact with the locking surface, and the protrusion has a cross-sectional area that increases toward the proximal side. The vehicle seat according to claim 2, wherein the vehicle seat is formed.   The vehicle seat according to claim 2, wherein the moving member is restricted from moving to the other side when a tip of the protrusion comes into surface contact with the locking surface.

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