WO2009101511A2 - Vehicle seat - Google Patents

Vehicle seat Download PDF

Info

Publication number
WO2009101511A2
WO2009101511A2 PCT/IB2009/000245 IB2009000245W WO2009101511A2 WO 2009101511 A2 WO2009101511 A2 WO 2009101511A2 IB 2009000245 W IB2009000245 W IB 2009000245W WO 2009101511 A2 WO2009101511 A2 WO 2009101511A2
Authority
WO
WIPO (PCT)
Prior art keywords
seatback
vehicle seat
side frames
frame
portions
Prior art date
Application number
PCT/IB2009/000245
Other languages
French (fr)
Other versions
WO2009101511A3 (en
Inventor
Keisuke Ishizaki
Manabu Ishimoto
Original Assignee
Toyota Jidosha Kabushiki Kaisha
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Toyota Jidosha Kabushiki Kaisha filed Critical Toyota Jidosha Kabushiki Kaisha
Publication of WO2009101511A2 publication Critical patent/WO2009101511A2/en
Publication of WO2009101511A3 publication Critical patent/WO2009101511A3/en

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60N—SEATS SPECIALLY ADAPTED FOR VEHICLES; VEHICLE PASSENGER ACCOMMODATION NOT OTHERWISE PROVIDED FOR
    • B60N2/00—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles
    • B60N2/24—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles for particular purposes or particular vehicles
    • B60N2/42—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles for particular purposes or particular vehicles the seat constructed to protect the occupant from the effect of abnormal g-forces, e.g. crash or safety seats
    • B60N2/4207—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles for particular purposes or particular vehicles the seat constructed to protect the occupant from the effect of abnormal g-forces, e.g. crash or safety seats characterised by the direction of the g-forces
    • B60N2/4214—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles for particular purposes or particular vehicles the seat constructed to protect the occupant from the effect of abnormal g-forces, e.g. crash or safety seats characterised by the direction of the g-forces longitudinal
    • B60N2/4228—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles for particular purposes or particular vehicles the seat constructed to protect the occupant from the effect of abnormal g-forces, e.g. crash or safety seats characterised by the direction of the g-forces longitudinal due to impact coming from the rear
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60N—SEATS SPECIALLY ADAPTED FOR VEHICLES; VEHICLE PASSENGER ACCOMMODATION NOT OTHERWISE PROVIDED FOR
    • B60N2/00—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles
    • B60N2/24—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles for particular purposes or particular vehicles
    • B60N2/42—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles for particular purposes or particular vehicles the seat constructed to protect the occupant from the effect of abnormal g-forces, e.g. crash or safety seats
    • B60N2/427—Seats or parts thereof displaced during a crash
    • B60N2/42709—Seats or parts thereof displaced during a crash involving residual deformation or fracture of the structure
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60N—SEATS SPECIALLY ADAPTED FOR VEHICLES; VEHICLE PASSENGER ACCOMMODATION NOT OTHERWISE PROVIDED FOR
    • B60N2/00—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles
    • B60N2/24—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles for particular purposes or particular vehicles
    • B60N2/42—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles for particular purposes or particular vehicles the seat constructed to protect the occupant from the effect of abnormal g-forces, e.g. crash or safety seats
    • B60N2/427—Seats or parts thereof displaced during a crash
    • B60N2/42727—Seats or parts thereof displaced during a crash involving substantially rigid displacement
    • B60N2/42745—Seats or parts thereof displaced during a crash involving substantially rigid displacement of the back-rest
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60N—SEATS SPECIALLY ADAPTED FOR VEHICLES; VEHICLE PASSENGER ACCOMMODATION NOT OTHERWISE PROVIDED FOR
    • B60N2/00—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles
    • B60N2/68—Seat frames

Definitions

  • the invention relates to a vehicle seat.
  • the seatback is constituted of side frames provided with ribs and notches.
  • the seat back is ensured of rigidity by the ribs.
  • the side frames are deformed due to the notches, thereby absorbing the impact force.
  • the seatback frame is provided with a dynamic damper.
  • the dynamic damper restrains vibrations of the vehicle seat.
  • JP-A- 11 -348628 JP-A- 11 -348628
  • the side frames are ensured of rigidity in preparation for the application of an impact force in the event of a collision of a vehicle
  • resonance of the vehicle body and the side frames during normal operation of the vehicle reduces the seating comfort of the vehicle seat if the rigidity of the side frames is high.
  • the invention provides a vehicle seat that ensures both adequate rigidity of the seatback side frames in the event of a collision and appropriate seating comfort during normal operation of the vehicle with minimal increases in cost and weight
  • a vehicle seat includes seatback side frames that extend vertically to form a right lateral portion and a left lateral portion of the seatback and may be changed from a first position to a second position that has higher rigidity in the front-back direction of the seat than the first position, and a load transmission portion that, if a rearward load equal to or larger than a predetermined value in the front-back direction of the seat is applied, changes the position of the seatback side frames from the first position to the second position,
  • the seatback side frames when the load applied to the load transmission portion is small during normal operation of the vehicle, the seatback side frames are in the first position.
  • the rigidity of the seatback side frames in the front-back direction is held low. Accordingly, even when vibrations are transmitted to the vehicle seat as a result of, for example, the movement of the vehicle or the operation of the engine during normal running of the vehicle, vibration of the seatback side frames is minimized.
  • the seating comfort of vehicle seat during normal operation of the vehicle may be ensured.
  • the seatback side frames are changed from the first position to the second position due to the rearward load.
  • the rigidity of the seatback side frames in the front-back direction is higher than when the seatback side frames are in the first position.
  • vibration of the seatback side frames is minimized by the seatback frames. Therefore, there is no need to provide a vibration damping device, for example, a dynamic damper or the like. Thus, increases in cost and weight may be reduced in comparison with the case where a vibration damping device is used.
  • the described vehicle seat ensures both sufficient rigidity of the seatback side frames in the event of a collision of the vehicle and appropriate seating comfort of the vehicle seat during normal operation of the vehicle with minimal increases in cost and weight.
  • each of the seatback side frames may have a flexible wall portion that is inclined with respect to the front-back direction so that the front of the wall portion is located further outside in a width direction than the rear portion of the wall portion in the first position and forms a smaller angle with the front-back direction in the second position.
  • the flexible wall portions constituting the seatback side frames are inclined with respect to the front-back direction so that the front regions of the seatback side frames are located further outside in the width direction than the rear regions. Accordingly, the geometric moment of inertia of the seatback side frames around axes thereof hi the width direction is small. Therefore, the rigidity of the seatback side frames in the front-back direction may be held low.
  • the flexible wall portions constituting these seatback side frames form a smaller angle with the front-back direction than when the seatback side frames are in the first position. Accordingly, the geometric moment of inertia around the axes of the seatback side frames in the width direction is large. Therefore, the rigidity of the seatback side frames in the front-back direction is made higher than in the first position.
  • the load transmission portion may be a seatback upper frame having an upper frame portion that extends in the width direction to constitute an upper portion of the seatback and couples upper regions of the seatback side frames to each other.
  • the vehicle seat if a rearward load equal to or larger than a predetermined value is applied to the upper frame portion constituting the upper portion of the seatback from, for example, the head of an occupant in the event of, for example, a head-on collision, the upper frame portion is deformed rearward into an arcuate shape. A torsional moment is then applied to both sides of the seatback upper frame in such a direction that turns the flexible wall portions inward in the width direction. Thus, the flexible wall portions are turned to form a smaller angle with the front-back direction than in the first position, and the seatback side frames change from the first position to the second position.
  • the load transmission portion may be a coupling member that extends in the width direction to couple the flexible wall portions to each other.
  • the flexible wall portions are pulled backward by the coupling member.
  • the flexible wall portions are turned to form a smaller angle with the front-back direction than in the first position, and the seatback side frames are changed from the first position to the second position.
  • the seatback side frames have side frame lower portions that are coupled to a seat cushion frame, and side frames upper portions that are disposed above and widthwise inside the side frame lower portions.
  • the seatback side frames may also have coupling frame portions that couple the upper regions of the side frame lower portions to the lower regions of the side frame upper portions respectively and that extend in the width direction in the first position and in the vertical direction in the second position.
  • the load transmission portion of each seatback side frame may be a seatback upper frame that has an upper frame portion, which extends in the width direction to constitute an upper portion of the seatback, to couple the upper regions of each side frame upper portion to each other.
  • the coupling frame portions extend in the width direction. Accordingly, the seatback side frames are flexed at coupling portions between the side frame lower portions and the coupling frame portions and at coupling portions between the side frame upper portions and the coupling frame portions respectively. Therefore, the rigidity of the seatback side frames in the front-back direction may be held low.
  • the entire seatback side frames including the coupling frame portions extend in the vertical direction.
  • the rigidity of the seatback side frames in the front-back direction may be made higher than in the first position.
  • the aspect of the invention ensures both sufficient rigidity of the seatback side frames in the event of a vehicle collision and appropriate seating comfort of the vehicle seat during normal operation of the vehicle with minimal increases in cost and weight.
  • FIG 1 is a perspective view showing an overall construction of a vehicle seat according to the first embodiment of the invention
  • FIG 2 is a plan view showing the overall construction of the vehicle seat according to the first embodiment of the invention.
  • FIG 3 is a lateral view showing the overall construction of the vehicle seat according to the first embodiment of the invention.
  • FIG 4A is a plan sectional view of a seatback side frame in the first embodiment of the invention.
  • FlG 4B shows a post-deformation state of the seatback side frame shown in FIG. 4 A;
  • FIG 5A is a view schematically showing the seatback side frame with a flexible wall portion extending along a front-back direction;
  • FIG 5B is a view schematically showing the seatback side frame with the flexible wall portion inclined with respect to the front-back direction;
  • FIG 6 is a view showing a relationship between a geometric moment of inertia of the seatback side frame around an axis thereof in a width direction of the seat and an angle of inclination of the flexible wall portion with respect to the front-back direction;
  • FIG 7 is a view showing a comparison between the vehicle seat according to the first embodiment of the invention an ⁇ a vehicle seat according to a comparative example
  • FIG 8 is a view showing a comparison between the vehicle seat according to the first embodiment of the invention and the vehicle seat according to the comparative example;
  • FIG 9 is a view showing a modification example of the vehicle seat according to the first embodiment of the invention.
  • FIG 10 is a view showing another modification example of the vehicle seat according to the first embodiment of the invention.
  • FIG 11 is a view showing still another modification example of the vehicle seat according to the first embodiment of the invention.
  • FIG 12 is a perspective view showing an overall construction of a vehicle seat according to the second embodiment of the invention.
  • FIG 13A is a plan sectional view of seatback frames in the second embodiment of the invention.
  • FIG 13B shows a post-deformation state of the seatback frames shown in FIG 13 A
  • FIG 14A is a perspective view showing an overall construction of a vehicle seat according to the third embodiment of the invention.
  • FIG 14B shows a post-deformation state of the vehicle seat shown in FIG 14A.
  • FIGS. 1 to 4 show a vehicle seat 10 according to the first embodiment of the invention.
  • Arrows X, Y, Z shown in these drawings indicate a rearward direction of the seat, an outward direction with respect to a width of the seat, and an upward direction of the seat respectively in this vehicle seat 10.
  • the vehicle seat 10 is preferably used for a front seat of a vehicle, for example, a passenger automobile or the like.
  • the vehicle seat 10 is composed of a seat frame 12, a cushion material (not shown) supported by this seat frame 12, and a seat skin (not shown) covering this cushion material.
  • the seat frame 12 is composed of a seat cushion frame 16 constituting a seat cushion 14, a seatback frame 20 constituting a seatback 18, and a headrest frame 24 constituting a headrest 22.
  • the seatback frame 20 is composed of a pair of seatback side frames 26 and a seatback upper frame 28, which serves as a load transmission portion.
  • each seatback side frame 26 extends vertically to form a right lateral portion of the seatback 18 and a left lateral portion of the seatback 18 respectively.
  • each seatback side frame 26 is composed of a base portion 30 that extends in a width direction, and a flexible portion 32 that extends forward (forward with respect to a front-back direction of the seat) from a widthwise outer region of the base portion 30.
  • the flexible wall portion 32 is inclined by an angle ⁇ ( ⁇ > 0°) with respect to the front-back direction so that a front region 32A thereof is located further outside in the width direction than a rear region 32B thereof.
  • a reinforcing wall portion 34 is formed on an inner region of the base portion 30, and a bent portion 36 is formed inward in the width direction on a front region of the flexible wall portion 32.
  • the seatback upper frame 28 is composed of an upper frame portion 38 that extends in the width direction to constitute an upper portion of the seatback 18, side frame shoulder portions 40 coupled to both ends of the upper frame portion 38 in the width direction respectively and curved downward, and side frame upper portions 42 coupled to lower regions of the side frame shoulder portions 40 respectively and extended in the vertical direction.
  • a headrest frame 24 is coupled to the upper frame portion 38, and lower regions of the side frame upper portions 42 are coupled to upper regions of the pair of the seatback side frames 26 respectively.
  • the geometric moment of inertia of the flexible wall portion 32 shown in FIG 4A around an axis in the width direction (around a Y-axis) is set sufficiently larger than the geometric moments of inertia of the reinforcing wall portion 34 and the base portion 30 around the axis in the width direction (around the Y-axis).
  • the bending rigidity of the upper frame portion 38 for a rearward load is set lower than the torsional rigidity of the seatback side frames 26.
  • the torsional rigidity of the side frame shoulder portions 40 is set higher than the torsional rigidity of the seatback side frames 26.
  • the upper frame portion 38 is deformed toward the rear into an arcuate shape as indicated by an imaginary line (alternate long and two short dashes lines) of FIG 2.
  • a deformation force acting at this moment is then transmitted to the side frame upper portions 42 via the side frame shoulders 40 respectively, and a torsional moment is applied to each of these side frame upper portions 42 in a direction that turns the flexible wall portion 32 inward in the width direction as indicated by an arrow Mz or -Mz of FIG 2.
  • vibration of the seatback side frames is minimized by the seatback frames. Therefore, there is no need to provide a vibration damping device, for example, a dynamic damper or the like. Thus, increases in cost and weight are minimal in comparison with a case where a vibration damping device is provided
  • the vehicle seat 10 ensures both rigidity of the seatback side frames 26 in the event of a collision of the vehicle and sitting comfort in the vehicle seat 10 during normal operation of the vehicle with minimal increases in cost and weight.
  • FIQ 5 A schematically shows one of the seatback side frames 26 with the flexible wall portion 32 extended along the front-back direction.
  • FIG 5B schematically shows one of the seatback side frames 26 with the flexible wall portion 32 inclined with respect to the front-back direction.
  • the geometric moment IyI of inertia of the flexible wall portion 32 around the axis in the width direction (around the Y-axis), the geometric moment Iy2 of inertia of the base portion 30 around the axis in the width direction (around the Y-axis), and the geometric moment Iy3 of inertia of the reinforcing wall portion 34 around the axis in the width direction (around the Y-axis) may be calculated from equations (1) to (3) shown below.
  • IyI thVl2+thx ! 2 ...
  • Iy2 d£l ⁇ 2+a&2 ...
  • Iy3 tb 3 /12+tbxj 2 ... (3)
  • a geometric moment Iy' of inertia of the seatback side frame 26 shown in FIG 5 B around the axis in the width direction (around the Y-axis) is the sum of IyI 1 , Iy2 ⁇ and Iy3' as indicated by an expression (11) shown below.
  • Iy' Iyl I +Iy2'+Iy3 ⁇ .. (ll)
  • FIG 6 shows how the geometric moment of inertia Iy 1 of the seatback side frame 26 around the axis in the width direction (around the Y-axis) and the angle ⁇ of inclination of the flexible wall portion 32 with respect to the front-back direction of the seat are related to each other when predetermined values are assigned to t, h, a, and b in FIG 5B.
  • the angle of inclination ⁇ of the flexible wall portion 32 is increased from 0° to 90°, the geometric moment Iy' of inertia of the seatback side frame 26 around the axis in the width direction (around the Y-axis) decreases.
  • the angle of inclination ⁇ of the flexible wall portion 32 is set to 40°, the angle of inclination ⁇ is made equal to 0° in the event of, for example, a head-on collision of the vehicle. Therefore, the geometric moment Iy 1 of inertia as in the case of the structure in which the angle of inclination ⁇ of the flexible wall portion 32 is 0° (i.e., a structure in which the flexible wall portion 32 extends in the front-back direction of the seat) can be ensured.
  • FIGS. 7 and 8 each show a comparison between the vehicle seat 10 according to the first embodiment of the invention and the vehicle seat according to the comparative example. More specifically, FIG 7 shows the relationship between a rearward load applied to the upper frame portion 38 and the deflection of the seatback side frames 26. FIG. 8 shows the relationship between the vibration level of the seatback side frames 26 and the frequency thereof.
  • the vehicle seat according to the comparative example has a structure in which, for example, the flexible wall portion 32 extends in the front-back direction, which increases the rigidity of each of the seatback side frames 26.
  • graphs Gl and G3 show the relationship about the vehicle seat 10 according to the first embodiment of the invention
  • graphs G2 and G4 show the relationship about the vehicle seat according to the comparative example.
  • a load range Al indicates a case where the load applied to the upper frame portion 38 is small, for example, when a seated occupant leans back against the seatback 18 or has his/her head supported by the headrest 22 during normal operation of the vehicle.
  • a load range A2 indicates a case where a load equal to or larger than a predetermined value is applied to the upper frame portion 38 from, for example, the head of the occupant via the headrest frame 24 in the event of, for example, a head-on collision of the vehicle.
  • a frequency range A3 indicates a band coincident with a idle speed of the engine.
  • a reference symbol FnI denotes a resonance frequency of the seatback side frames 26 in the vehicle seat 10 according to the first embodiment of the invention
  • a reference symbol Fn2 denotes a resonance frequency of the seatback side frames 26 in the vehicle seat according to the comparative example.
  • the gradient of the graph G2, namely, the bending rigidity of the seatback side frames 26 for rearward load is constant in the load range Al in which the load applied to the upper frame portion 38 is small and in the load range A2 in which a load equal to or larger than the predetermined value is applied to the upper frame portion 38.
  • the bending rigidity of the seatback side frames 26 for a rearward load is high during normal operation of the vehicle, namely, when the load applied to the upper frame portion 38 is small. Therefore, as shown in FIG 8, the resonance frequency Fn2 exists in a rotational speed range during idle operation of the engine.
  • a vehicle body and the side frames vibrate sympathetically when the engine is idling, which reduces seating comfort of the vehicle seat.
  • the gradient of the graph Gl is equal to the gradient of the graph G2
  • the same bending rigidity of the seatback side frames 26 may be ensured of more or less as in the vehicle set according to the comparative example.
  • the resonance frequency FnI is outside the rotational speed range when the engine is idling. Therefore, the vehicle seat 10 can be ensured of seating comfort even when the engine is idling.
  • the same bending rigidity of the seatback side frames 26 may be ensured of more or less as in the vehicle set according to the comparative example, while also ensuring appropriate seating comfort in the vehicle seat 10 even when the engine is idling during normal operation of the vehicle.
  • each of the entire seatback side frames 26, including the flexible wall portion 32 may be turned inward in the width direction of the seat.
  • ⁇ 0°
  • the flexible wall portion 32 may be turned from being inclined outward in the width direction by the angle ⁇ with respect to the front-back direction to being inclined outward in the width direction by an angle ⁇ l ( ⁇ > ⁇ l) with respect to the front-back direction.
  • the flexible wall portion 32 may be turned from being inclined outward in the width direction by the angle ⁇ with respect to the front-back direction to being inclined inward in the width direction by an angle ⁇ 2 (Q > ⁇ 2) with respect to the front-back direction.
  • the constructions shown in FIGS. 9 to 11 also ensure both sufficient rigidity of the seatback side frames 26 in the event of a vehicle collision and appropriate seating comfort of the vehicle seat 10 during normal operation of the vehicle.
  • FIGS. 12 to 13B each show a vehicle seat 50 according to the second embodiment of the invention.
  • the arrows X, Y, and Z shown in these drawings indicate a rearward direction of the seat, an outward direction with respect to a width of the seat, and an upward direction of the seat respectively in this vehicle seat 50.
  • the vehicle seat 50 according to the second embodiment of the invention is constructed by adding a plurality of coupling members 52 to the seatback frame 20 in the vehicle seat 10 according to the foregoing first embodiment of the invention.
  • the coupling members 52 are formed in the shape of belts that extend in the width direction, and are coupled to a pair of flexible wall portions 32.
  • the coupling members 52 are deflected rearward in an arcuate shape, and are disposed behind a cushioning material of the seatback (not shown).
  • the flexible wall portion 32 is held inclined by the angle ⁇ with respect to the front-back direction as shown in FIG 13 A.
  • the vehicle seat 50 according to the second embodiment of the invention has a construction in which vibration of the seatback side frames is minimized by the seatback side frames. Therefore, there is no need to provide a separate vibration damping device, for example, a dynamic damper or the like. Thus, increases in cost and weight may be suppressed in comparison with a case where a vibration damping device is provided in the vehicle seat
  • the vehicle seat 50 according to the second embodiment of the invention ensures both sufficient rigidity of the seatback side frames 26 in the event of a vehicle collision and appropriate seating comfort in the vehicle seat 50 during normal operation of the vehicle with minimal increases in cost and weight.
  • the flexible wall portions 32 are changed from being inclined with respect to the front-back direction to being extended along the front-back direction by a torsional force from the seatback upper frame 28 as well as tensile forces of the coupling members 52.
  • the flexible wall portions 32 may also be changed from being inclined with respect to the front-back direction to being extended along the front-back direction by only the tensile forces of the coupling members 52.
  • FIGS. 14A and 14B each show a vehicle seat 60 according to the third embodiment of the invention.
  • the arrows X, Y, and Z shown in these drawings indicate a rearward direction of the seat, an outward direction with respect to a width of the seat, and an upward direction of the seat respectively in this vehicle seat 60.
  • the vehicle seat 60 according to the third embodiment of the invention uses the seatback frame 70 instead of the seatback frame 20 in the vehicle seat 10 according to the first embodiment of the invention.
  • the seatback frame 70 is composed of side frame lower portions 72, side frame upper portions 74, coupling frame portions 76, and an upper frame portion 78.
  • the side frame lower portions 72 are coupled to the seat cushion frame 16, and extend in the vertical direction.
  • the side frame upper portions 74 are disposed above and widthwise inside the side frame lower portions 72 respectively, and extend in the vertical direction.
  • the coupling frame portions 76 extend in the width direction to couple upper regions of the side frame lower portions 72 to lower regions of the side frame upper portions 74 respectively.
  • the upper frame portion 78 constitutes an upper region of the seatback 18, and extends in the width direction to couple upper regions of the pair of the side frame upper portions 74 to each other.
  • the side frame lower portions 72, the side frame upper portions 74, and the coupling frame portions 76 constitute seatback side frames 86 respectively.
  • the upper frame portion 78 constitutes a seatback upper frame 88 as the load transmission portion.
  • the coupling frame portions 76 which couple the upper regions of the side frame upper portions 74 to the lower regions of the side frame lower portions 72 respectively, extend in the width direction of the seat as shown in FIG. 14A.
  • the seatback side frames 86 are flexed at coupling portions thereof between the side frame upper portions 74 and the coupling frame portions 76 and at coupling portions thereof between the side frame lower portions 72 and the coupling frame portions 76 respectively. Therefore, the rigidity of the seatback side frames 86 in the front-back direction is held low.
  • the vehicle seat 60 according to the third embodiment of the invention has a construction in which vibration of the seatback side frames 86 is minimized by the seatback side frames 86; Therefore, there is no need to provide a vibration damping device, for example, a dynamic damper or the like. Thus, increases in cost and weight may be minimized in comparison with the case where a vibration damping device is provided in the vehicle seat.
  • the vehicle seat 60 according to the third embodiment of the invention ensures both sufficient rigidity of the seatback side frames 86 in the event of a vehicle collision and appropriate seating comfort of the vehicle seat 60 during normal operation of the vehicle with minimal increases in cost and weight.

Abstract

Flexible wall portions inclined with respect to a front-back direction are formed on seatback side frames respectively. During normal operation of a vehicle, the flexible wall portions are held inclined by an angle θ, and the rigidity of the seatback side frames in the front-back direction is held low. Therefore, appropriate seating comfort in the vehicle seat may be ensured. In the event of a head-on collision of the vehicle, the deformation of an upper frame portion toward the rear causes the flexible wall portions to extend along the front-back direction, thereby increasing the rigidity of the seatback side frames.

Description

VEHICLE SEAT
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] The invention relates to a vehicle seat.
2. Description of the Related Art
[0002] The following vehicle seats are known (e.g., see Japanese Patent Application Publication No. 11-348628 (JP-A-U-348628) and Japanese Patent Application Publication No. 2003-226179 (JP-A-2003-226179)).
[0003] The vehicle seat described in Japanese Patent Application Publication No. 11-348628 (JP-A-11-348628), the seatback is constituted of side frames provided with ribs and notches. When a certain impact force is applied to the seat back, the seat back is ensured of rigidity by the ribs. When a very large impact force is applied to the seat back, the side frames are deformed due to the notches, thereby absorbing the impact force.
[0004] In the vehicle seat described in Japanese Patent Application Publication No. 2003-226179 (JP-A-2003-226179), the seatback frame is provided with a dynamic damper. The dynamic damper restrains vibrations of the vehicle seat.
[0005] However, in the vehicle seat described in Japanese Patent Application Publication No. 11-348628 (JP-A- 11 -348628), although the side frames are ensured of rigidity in preparation for the application of an impact force in the event of a collision of a vehicle, resonance of the vehicle body and the side frames during normal operation of the vehicle reduces the seating comfort of the vehicle seat if the rigidity of the side frames is high.
[0006] Further, in the vehicle seat described in Japanese Patent Application Publication No. 2003-226179 (JP-A-2003-226179), although vibrations during normal operation of the vehicle may be suppressed by the dynamic damper, the provision of the dynamic damper increases the cost and weight of the seat.
SUMMARY OF THE INVENTION [0007] The invention provides a vehicle seat that ensures both adequate rigidity of the seatback side frames in the event of a collision and appropriate seating comfort during normal operation of the vehicle with minimal increases in cost and weight
(0008] A vehicle seat according to a first aspect of the invention includes seatback side frames that extend vertically to form a right lateral portion and a left lateral portion of the seatback and may be changed from a first position to a second position that has higher rigidity in the front-back direction of the seat than the first position, and a load transmission portion that, if a rearward load equal to or larger than a predetermined value in the front-back direction of the seat is applied, changes the position of the seatback side frames from the first position to the second position,
[0009] According to the described vehicle seat, when the load applied to the load transmission portion is small during normal operation of the vehicle, the seatback side frames are in the first position. When the seatback side frames are in the first position, the rigidity of the seatback side frames in the front-back direction is held low. Accordingly, even when vibrations are transmitted to the vehicle seat as a result of, for example, the movement of the vehicle or the operation of the engine during normal running of the vehicle, vibration of the seatback side frames is minimized. Thus, the seating comfort of vehicle seat during normal operation of the vehicle may be ensured.
[0010] On the other hand, if a rearward load equal to or larger than the predetermined value is applied to the load transmission portion as a result of, for example, a head-on collision, the seatback side frames are changed from the first position to the second position due to the rearward load. When the seatback side frames are in the second position, the rigidity of the seatback side frames in the front-back direction is higher than when the seatback side frames are in the first position. Thus, sufficient rigidity of the seatback side frames may be ensured in the event of a collision.
[0011] In addition, according to the vehicle seat as described above, vibration of the seatback side frames is minimized by the seatback frames. Therefore, there is no need to provide a vibration damping device, for example, a dynamic damper or the like. Thus, increases in cost and weight may be reduced in comparison with the case where a vibration damping device is used.
[0012] As described above, the described vehicle seat ensures both sufficient rigidity of the seatback side frames in the event of a collision of the vehicle and appropriate seating comfort of the vehicle seat during normal operation of the vehicle with minimal increases in cost and weight.
[0013] In the vehicle seat according to the first aspect of the invention, each of the seatback side frames may have a flexible wall portion that is inclined with respect to the front-back direction so that the front of the wall portion is located further outside in a width direction than the rear portion of the wall portion in the first position and forms a smaller angle with the front-back direction in the second position.
[0014] According to the vehicle seat, when the seatback side frames are in the first position, the flexible wall portions constituting the seatback side frames are inclined with respect to the front-back direction so that the front regions of the seatback side frames are located further outside in the width direction than the rear regions. Accordingly, the geometric moment of inertia of the seatback side frames around axes thereof hi the width direction is small. Therefore, the rigidity of the seatback side frames in the front-back direction may be held low.
[0015] However, if the seatback side frames are in the second position, the flexible wall portions constituting these seatback side frames form a smaller angle with the front-back direction than when the seatback side frames are in the first position. Accordingly, the geometric moment of inertia around the axes of the seatback side frames in the width direction is large. Therefore, the rigidity of the seatback side frames in the front-back direction is made higher than in the first position.
[0016] In the vehicle seat according to the first aspect of the invention, the load transmission portion may be a seatback upper frame having an upper frame portion that extends in the width direction to constitute an upper portion of the seatback and couples upper regions of the seatback side frames to each other.
[0017] According to the vehicle seat, if a rearward load equal to or larger than a predetermined value is applied to the upper frame portion constituting the upper portion of the seatback from, for example, the head of an occupant in the event of, for example, a head-on collision, the upper frame portion is deformed rearward into an arcuate shape. A torsional moment is then applied to both sides of the seatback upper frame in such a direction that turns the flexible wall portions inward in the width direction. Thus, the flexible wall portions are turned to form a smaller angle with the front-back direction than in the first position, and the seatback side frames change from the first position to the second position.
[0018] In the vehicle seat according to the first aspect of the invention, the load transmission portion may be a coupling member that extends in the width direction to couple the flexible wall portions to each other.
[0019J According to the vehicle seat, if a rearward load equal to or larger than a predetermined value is applied to the coupling member from, example,, the torso of an occupant in the event of, for example, a head-on collision of the vehicle, the flexible wall portions are pulled backward by the coupling member. Thus, the flexible wall portions are turned to form a smaller angle with the front-back direction than in the first position, and the seatback side frames are changed from the first position to the second position.
[0020] In the vehicle seat according to the first aspect of the invention, the seatback side frames have side frame lower portions that are coupled to a seat cushion frame, and side frames upper portions that are disposed above and widthwise inside the side frame lower portions. The seatback side frames may also have coupling frame portions that couple the upper regions of the side frame lower portions to the lower regions of the side frame upper portions respectively and that extend in the width direction in the first position and in the vertical direction in the second position. Furthermore, the load transmission portion of each seatback side frame may be a seatback upper frame that has an upper frame portion, which extends in the width direction to constitute an upper portion of the seatback, to couple the upper regions of each side frame upper portion to each other.
[0021] According to the vehicle seat, when the seatback side frames are in the first position, the coupling frame portions extend in the width direction. Accordingly, the seatback side frames are flexed at coupling portions between the side frame lower portions and the coupling frame portions and at coupling portions between the side frame upper portions and the coupling frame portions respectively. Therefore, the rigidity of the seatback side frames in the front-back direction may be held low.
[0022] However, if a rearward Joad equal to or larger than a predetermined value is applied to the upper frame portion of the seatback from, for example, the head of an occupant in the event of, for example, a head-on collision of the vehicle, the upper frame portion is deformed rearward into an arcuate shape. A torsional moment is then applied to both the sides of the seatback upper frame in the width direction in such a direction as to draw the seatback side frames inward in the width direction. Thus, the coupling frame portions are changed from being extended in the width direction to being extended in the vertical direction so that the seatback side frames may be changed from the first position to the second position.
[0023} When the seatback side frames are in the second position, the entire seatback side frames including the coupling frame portions extend in the vertical direction. Thus, the rigidity of the seatback side frames in the front-back direction may be made higher than in the first position.
[0024] As described in detail above, the aspect of the invention ensures both sufficient rigidity of the seatback side frames in the event of a vehicle collision and appropriate seating comfort of the vehicle seat during normal operation of the vehicle with minimal increases in cost and weight.
BRIEF DESCRIPTION OF THE DRAWINGS [0025] The features, advantages, and technical and industrial significance of this invention wall be described in the following detailed description of example embodiments of the invention with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:
FIG 1 is a perspective view showing an overall construction of a vehicle seat according to the first embodiment of the invention;
FIG 2 is a plan view showing the overall construction of the vehicle seat according to the first embodiment of the invention;
FIG 3 is a lateral view showing the overall construction of the vehicle seat according to the first embodiment of the invention;
FIG 4A is a plan sectional view of a seatback side frame in the first embodiment of the invention;
FlG 4Bshows a post-deformation state of the seatback side frame shown in FIG. 4 A;
FIG 5A is a view schematically showing the seatback side frame with a flexible wall portion extending along a front-back direction;
FIG 5B is a view schematically showing the seatback side frame with the flexible wall portion inclined with respect to the front-back direction;
FIG 6 is a view showing a relationship between a geometric moment of inertia of the seatback side frame around an axis thereof in a width direction of the seat and an angle of inclination of the flexible wall portion with respect to the front-back direction;
FIG 7 is a view showing a comparison between the vehicle seat according to the first embodiment of the invention anά a vehicle seat according to a comparative example;
FIG 8 is a view showing a comparison between the vehicle seat according to the first embodiment of the invention and the vehicle seat according to the comparative example;
FIG 9 is a view showing a modification example of the vehicle seat according to the first embodiment of the invention;
FIG 10 is a view showing another modification example of the vehicle seat according to the first embodiment of the invention;
FIG 11 is a view showing still another modification example of the vehicle seat according to the first embodiment of the invention;
FIG 12 is a perspective view showing an overall construction of a vehicle seat according to the second embodiment of the invention;
FIG 13A is a plan sectional view of seatback frames in the second embodiment of the invention;
FIG 13B shows a post-deformation state of the seatback frames shown in FIG 13 A;
FIG 14A is a perspective view showing an overall construction of a vehicle seat according to the third embodiment of the invention; and
FIG 14B shows a post-deformation state of the vehicle seat shown in FIG 14A.
DETAILED DESCRIPTION OF EMBODIMENTS
[0026] First of all, the first embodiment of the invention will be described.
[0027] FIGS. 1 to 4 show a vehicle seat 10 according to the first embodiment of the invention. Arrows X, Y, Z shown in these drawings indicate a rearward direction of the seat, an outward direction with respect to a width of the seat, and an upward direction of the seat respectively in this vehicle seat 10.
[0028] The vehicle seat 10 according to the first embodiment of the invention is preferably used for a front seat of a vehicle, for example, a passenger automobile or the like. The vehicle seat 10 is composed of a seat frame 12, a cushion material (not shown) supported by this seat frame 12, and a seat skin (not shown) covering this cushion material.
(0029] As shown in FIGS. 1 to 3, the seat frame 12 is composed of a seat cushion frame 16 constituting a seat cushion 14, a seatback frame 20 constituting a seatback 18, and a headrest frame 24 constituting a headrest 22. Further, the seatback frame 20 is composed of a pair of seatback side frames 26 and a seatback upper frame 28, which serves as a load transmission portion.
[0030] The each seatback side frame 26 extends vertically to form a right lateral portion of the seatback 18 and a left lateral portion of the seatback 18 respectively. As shown in FIG 4 A, each seatback side frame 26 is composed of a base portion 30 that extends in a width direction, and a flexible portion 32 that extends forward (forward with respect to a front-back direction of the seat) from a widthwise outer region of the base portion 30. The flexible wall portion 32 is inclined by an angle θ (θ > 0°) with respect to the front-back direction so that a front region 32A thereof is located further outside in the width direction than a rear region 32B thereof.
[0031] A reinforcing wall portion 34 is formed on an inner region of the base portion 30, and a bent portion 36 is formed inward in the width direction on a front region of the flexible wall portion 32. [0032] As shown in FIGS. 1 to 3, the seatback upper frame 28 is composed of an upper frame portion 38 that extends in the width direction to constitute an upper portion of the seatback 18, side frame shoulder portions 40 coupled to both ends of the upper frame portion 38 in the width direction respectively and curved downward, and side frame upper portions 42 coupled to lower regions of the side frame shoulder portions 40 respectively and extended in the vertical direction.
[0033] A headrest frame 24 is coupled to the upper frame portion 38, and lower regions of the side frame upper portions 42 are coupled to upper regions of the pair of the seatback side frames 26 respectively.
[0034] The geometric moments of inertia and bending rigidities for respective portions of this seatback frame 20 are set as follows.
[0035] That is, the geometric moment of inertia of the flexible wall portion 32 shown in FIG 4A around an axis in the width direction (around a Y-axis) is set sufficiently larger than the geometric moments of inertia of the reinforcing wall portion 34 and the base portion 30 around the axis in the width direction (around the Y-axis).
[0036] Further, the bending rigidity of the upper frame portion 38 for a rearward load is set lower than the torsional rigidity of the seatback side frames 26. In addition, the torsional rigidity of the side frame shoulder portions 40 is set higher than the torsional rigidity of the seatback side frames 26.
[0037] According to the vehicle seat 10 constructed as described above, the following specific effects are achieved.
[0038] That is, according to the first embodiment of the invention, when the load applied to the upper frame portion 38 is small, for example, when a sitting passenger leans back against the seatback 18 or has his/her head supported by the headrest 22, the flexible wall portion 32 is held inclined by the angle θ as shown in FIG 4A.
[0039] As shown in FIG 4A, when the flexible wall portion 32 is inclined by the angle θ, the geometric moment of inertia of the seatback side frames 26 around the axis in the width direction (around the Y-axis) is small. Therefore, the rigidity of the seatback side frames 26 in the front-back direction may be held low. [0040] Accordingly, even when vibrations are transmitted to the vehicle seat 10 as a result of, for example, the movement of the vehicle or the operation of an engine, vibration of the seatback side frames is minimized. Thus, appropriate seating comfort of the vehicle seat 10 may be ensured during normal operation of the vehicle.
[0041] However, if a load equal to or larger than a predetermined value is applied to the upper frame portion 38 from, for example, the head of an occupant or the like via the headrest frame 24 as indicated by arrows Fx of FIGS. 1 to 3 in the event of, for example, a head-on collision of the vehicle, the upper frame portion 38 is deformed toward the rear into an arcuate shape as indicated by an imaginary line (alternate long and two short dashes lines) of FIG 2.
[0042] A deformation force acting at this moment is then transmitted to the side frame upper portions 42 via the side frame shoulders 40 respectively, and a torsional moment is applied to each of these side frame upper portions 42 in a direction that turns the flexible wall portion 32 inward in the width direction as indicated by an arrow Mz or -Mz of FIG 2.
[0043] Thus, the flexible wall portion 32 is turned with respect to the base portion 30 from a state of being inclined with respect to the front-back direction by the angle θ as shown in FIG 4A to extending along the front-back direction (i.e., θ = 0°) as shown in FIG 4B.
[0044] Then, when the flexible wall portion 32 is extending along the front-back direction as shown in FIG 4B, the geometric moment of inertia of the seatback side frames 26 around the axis in the width direction (the Y-axis) is large. Therefore, the rigidity of the seatback side frames 26 in the front-back direction is higher than in the inclined state as mentioned above.
[0045] Thus, sufficient rigidity the seatback side frames 26 in the event of a collision of the vehicle may be ensured (i.e., rigidity sufficient to receive a torsional moment indicated by an arrow My of FIG 3).
[0046] In addition, according to the vehicle seat 10, as described above, vibration of the seatback side frames is minimized by the seatback frames. Therefore, there is no need to provide a vibration damping device, for example, a dynamic damper or the like. Thus, increases in cost and weight are minimal in comparison with a case where a vibration damping device is provided
[0047) As described above, the vehicle seat 10 according to the first embodiment of the invention ensures both rigidity of the seatback side frames 26 in the event of a collision of the vehicle and sitting comfort in the vehicle seat 10 during normal operation of the vehicle with minimal increases in cost and weight.
[0048] An example of setting the angle θ of inclination to ensure both adequate rigidity of the seatback side frames 26 in the event of a collision of the vehicle and appropriate sealing comfort in the vehicle seat 10 during normal operation of the vehicle will now be described.
[0049] FIQ 5 A schematically shows one of the seatback side frames 26 with the flexible wall portion 32 extended along the front-back direction. FIG 5B schematically shows one of the seatback side frames 26 with the flexible wall portion 32 inclined with respect to the front-back direction.
[0050] In the seatback side frame 26 shown in FIG 5A, the geometric moment IyI of inertia of the flexible wall portion 32 around the axis in the width direction (around the Y-axis), the geometric moment Iy2 of inertia of the base portion 30 around the axis in the width direction (around the Y-axis), and the geometric moment Iy3 of inertia of the reinforcing wall portion 34 around the axis in the width direction (around the Y-axis) may be calculated from equations (1) to (3) shown below. IyI = thVl2+thx! 2 ... (1) Iy2 = d£l\2+a&2 ... (2) Iy3 = tb3/12+tbxj2 ... (3)
[0051] Further, a geometric moment Iy of inertia of the seatback side frame 26 shown in FIG. 5A around the axis in the width direction (around the Y-axis) is the sum of IyI , Iy2, and Iy 3 as indicated by equation (4) shown below, Iy = Iyl+Iy2+Iy3 ... (4)
[0052] In contrast, in the seatback side frame 26 shown in FIG 5B, the geometric moment IyI1 of inertia of the flexible wall portion 32 around the axis in the width direction (around the Y-axis), the geometric moment Ϊy2' of inertia of the base portion 30 around the axis in the width direction (around the Y-axis), and the geometric moment Iy3' of inertia of the reinforcing wall portion 34 around the axis in the width direction (around the Y-axis) can be calculated from equations (5) to (T) shown below, IyI1 = th3/12+thx'i2 ... (5) IyT = ^/l2+&tx'2 2 ... (6) Iy3( = tb3/12+tbx'3 2 ... (7) It should be noted, however, that x'i = xicosθ ... (8), x*2 = x∑cosθ ... (9), and x'3 = x3cosθ ... (10).
[0053] Further, a geometric moment Iy' of inertia of the seatback side frame 26 shown in FIG 5 B around the axis in the width direction (around the Y-axis) is the sum of IyI1, Iy2\ and Iy3' as indicated by an expression (11) shown below. Iy' = IylI+Iy2'+Iy3\.. (ll)
[0054] FIG 6 shows how the geometric moment of inertia Iy1 of the seatback side frame 26 around the axis in the width direction (around the Y-axis) and the angle θ of inclination of the flexible wall portion 32 with respect to the front-back direction of the seat are related to each other when predetermined values are assigned to t, h, a, and b in FIG 5B. [0055] As shown in FIG 6, as the angle of inclination θ of the flexible wall portion 32 is increased from 0° to 90°, the geometric moment Iy' of inertia of the seatback side frame 26 around the axis in the width direction (around the Y-axis) decreases.
[0056J Consequently, when, for example, the angle of inclination θ of the flexible wall portion 32 is set to 40°, the geometric moment Iy' of each seatback side frame 26 around the axis in the width direction (around the Y-axis) is substantially reduced by half in comparison with a structure in which the angle of inclination θ of the flexible wall portion 32 is 0° (i.e., a structure in which the flexible wall portion 32 extends in the front-back direction of the seat, which increases the rigidity of each of the seatback side frames 26).
[0057] Thus, even if the angle of inclination θ of the flexible wall portion 32 is set to 40°, the angle of inclination θ is made equal to 0° in the event of, for example, a head-on collision of the vehicle. Therefore, the geometric moment Iy1 of inertia as in the case of the structure in which the angle of inclination θ of the flexible wall portion 32 is 0° (i.e., a structure in which the flexible wall portion 32 extends in the front-back direction of the seat) can be ensured.
[0058] Subsequently, a comparative study example of the vehicle seat 10 according to the first embodiment of the invention and a vehicle seat according to a comparative example will be described.
[0059] FIGS. 7 and 8 each show a comparison between the vehicle seat 10 according to the first embodiment of the invention and the vehicle seat according to the comparative example. More specifically, FIG 7 shows the relationship between a rearward load applied to the upper frame portion 38 and the deflection of the seatback side frames 26. FIG. 8 shows the relationship between the vibration level of the seatback side frames 26 and the frequency thereof.
[0060] The vehicle seat according to the comparative example has a structure in which, for example, the flexible wall portion 32 extends in the front-back direction, which increases the rigidity of each of the seatback side frames 26.
[0061] In FIGS. 7 and 8, graphs Gl and G3 show the relationship about the vehicle seat 10 according to the first embodiment of the invention, and graphs G2 and G4 show the relationship about the vehicle seat according to the comparative example.
[0062] Further, in FIG 7, a load range Al indicates a case where the load applied to the upper frame portion 38 is small, for example, when a seated occupant leans back against the seatback 18 or has his/her head supported by the headrest 22 during normal operation of the vehicle. On the other hand, a load range A2 indicates a case where a load equal to or larger than a predetermined value is applied to the upper frame portion 38 from, for example, the head of the occupant via the headrest frame 24 in the event of, for example, a head-on collision of the vehicle. [0063] Further, in FIG. 8, a frequency range A3 indicates a band coincident with a idle speed of the engine. A reference symbol FnI denotes a resonance frequency of the seatback side frames 26 in the vehicle seat 10 according to the first embodiment of the invention, and a reference symbol Fn2 denotes a resonance frequency of the seatback side frames 26 in the vehicle seat according to the comparative example.
[0064] As is apparent from FIG 7, in the vehicle seat of the comparative example, the gradient of the graph G2, namely, the bending rigidity of the seatback side frames 26 for rearward load is constant in the load range Al in which the load applied to the upper frame portion 38 is small and in the load range A2 in which a load equal to or larger than the predetermined value is applied to the upper frame portion 38.
[0065] Accordingly, the bending rigidity of the seatback side frames 26 for a rearward load is high during normal operation of the vehicle, namely, when the load applied to the upper frame portion 38 is small. Therefore, as shown in FIG 8, the resonance frequency Fn2 exists in a rotational speed range during idle operation of the engine. Thus, a vehicle body and the side frames vibrate sympathetically when the engine is idling, which reduces seating comfort of the vehicle seat.
[0066] In contrast, in the vehicle seat lOaccording to the first embodiment of the invention, if a head-on collision of the vehicle occurs, namely, when a rearward load equal to or larger than the predetermined value is applied to the upper frame portion 38, the gradient of the graph Gl is equal to the gradient of the graph G2, and the same bending rigidity of the seatback side frames 26 may be ensured of more or less as in the vehicle set according to the comparative example.
[0067] Meanwhile, during normal operation of the vehicle, namely, when the load applied to the upper frame portion 38 is small, the gradient of the graph Gl is smaller than the gradient of the graph G2, and the bending rigidity of the seatback side frames 26 may be held lower than in the vehicle seat according to the comparative example. Thus, as shown in FIG 8, the resonance frequency FnI is outside the rotational speed range when the engine is idling. Therefore, the vehicle seat 10 can be ensured of seating comfort even when the engine is idling. [0068] As described above, according to the first embodiment of the invention, the same bending rigidity of the seatback side frames 26 may be ensured of more or less as in the vehicle set according to the comparative example, while also ensuring appropriate seating comfort in the vehicle seat 10 even when the engine is idling during normal operation of the vehicle.
[0069] Although the first embodiment of the invention has been described above, the invention should not be restricted to the above embodiment. As a matter of course, the invention may be modified and carried out in various manners without departing from the spirit thereof.
[0070] For example, in the first embodiment of the invention', if a load equal to or larger than the predetermined value is applied to the upper frame portion 38, the flexible wall portion 32 is turned with respect to the base portion 30. However, as shown in FIG 9, each of the entire seatback side frames 26, including the flexible wall portion 32, may be turned inward in the width direction of the seat.
[0071] Further, in the first embodiment of the invention, if a rearward load equal to or larger than the predetermined value is applied to the upper frame portion 38, the flexible wall portion 32 is turned from being inclined outward in the width direction by the angle θ with respect to the front-back direction to being extended along the front-back direction (i.e., θ = 0°). However, the following construction is also acceptable.
[0072] That is, as shown in FIG. 10, the flexible wall portion 32 may be turned from being inclined outward in the width direction by the angle θ with respect to the front-back direction to being inclined outward in the width direction by an angle θl (θ > θl) with respect to the front-back direction.
[0073J Further, as shown in FIG 11, the flexible wall portion 32 may be turned from being inclined outward in the width direction by the angle θ with respect to the front-back direction to being inclined inward in the width direction by an angle Θ2 (Q > Θ2) with respect to the front-back direction.
[0074] As is the case with the first embodiment of the invention, the constructions shown in FIGS. 9 to 11 also ensure both sufficient rigidity of the seatback side frames 26 in the event of a vehicle collision and appropriate seating comfort of the vehicle seat 10 during normal operation of the vehicle.
[0075] Next, the second embodiment of the invention will be described.
[0076] FIGS. 12 to 13B each show a vehicle seat 50 according to the second embodiment of the invention. The arrows X, Y, and Z shown in these drawings indicate a rearward direction of the seat, an outward direction with respect to a width of the seat, and an upward direction of the seat respectively in this vehicle seat 50.
[0077] The vehicle seat 50 according to the second embodiment of the invention is constructed by adding a plurality of coupling members 52 to the seatback frame 20 in the vehicle seat 10 according to the foregoing first embodiment of the invention. The coupling members 52 are formed in the shape of belts that extend in the width direction, and are coupled to a pair of flexible wall portions 32.
[0078] In order to prevent the cushioning properties of the seatback 18 from being lost, the coupling members 52 are deflected rearward in an arcuate shape, and are disposed behind a cushioning material of the seatback (not shown).
[0079] According to the vehicle seat 50 having the above construction, the following specific effects are achieved.
[0080] That is, according to the vehicle seat 50 according to the second embodiment, when the load applied to the upper frame portion 38 and the coupling members 52 is small, for example, when a seated occupant leans against the seatback 18 or has his/her head supported by the headrest 22, the flexible wall portion 32 is held inclined by the angle θ with respect to the front-back direction as shown in FIG 13 A.
[0081] As shown in FIQ 13 A, when the flexible wall portions 32 are inclined by the angle θ, the geometric moment of inertia around the axis of the seatback side frames 26 is small in the width direction (around the Y-axis), Therefore, the rigidity of the seatback side frames 26 in the front-back direction may be held low.
[0082] Accordingly, even if vibrations are transmitted to the vehicle seat 50 as a result of, for example, the movement of the vehicle or the operation of the engine during normal operation of the vehicle, vibration of the seatback side frames is minimized. Thus, appropriate seating comfort of the vehicle seat 50 may be ensured during normal operation of the vehicle.
[0083] On the other hand, if loads equal to or larger than a predetermined value are applied to the coupling members 52 from the torso or the like of an occupant as indicated by arrows FxI in FIG 12 as a result of, for example, a head-on vehicle collision, the coupling members 52 are pulled rearward. The pair of the flexible wall portions 32 are pulled inward in the width direction by these coupling members 52.
[0084] Thus, the flexible wall portions 32 are turned with respect to the base portions 30 from being inclined by the angle θ as shown in FIG 13A to being extended along the front-back direction as shown in FIG 13B (i.e., θ = 0°).
[0085] At this moment, as in the case of the vehicle seat 10 according to the foregoing first embodiment, if a rearward load equal to or larger than the predetermined value is applied to the upper frame portion 38 from, for example, a head of a passenger via the headrest frame 24, as indicated by an arrow Fx of FIG 12, the torsional force from the seatback upper frame 28 as well as tensile forces of the coupling members 52 is applied to the flexible wall portions 32. Thus, the flexible wall portions 32 are more swiftly brought to extend along the front-back direction.
[0086] When the flexible wall portions 32 extends along the front-back direction as shown in FIG 13B, the geometric moment of inertia around the axis of the seatback side frames 26 in the width direction (around the Y-axis) is large. Therefore, the rigidity of the seatback side frames 26 in the front-back direction is higher than in the normal state. Thus, sufficient rigidity of the seatback side frames 26 may be ensured in the event of a vehicle collisioa
[0087] Besides, as in the case of the vehicle seat 10 according to the first embodiment of the invention, the vehicle seat 50 according to the second embodiment of the invention has a construction in which vibration of the seatback side frames is minimized by the seatback side frames. Therefore, there is no need to provide a separate vibration damping device, for example, a dynamic damper or the like. Thus, increases in cost and weight may be suppressed in comparison with a case where a vibration damping device is provided in the vehicle seat
[0088] As described above, the vehicle seat 50 according to the second embodiment of the invention ensures both sufficient rigidity of the seatback side frames 26 in the event of a vehicle collision and appropriate seating comfort in the vehicle seat 50 during normal operation of the vehicle with minimal increases in cost and weight.
[0089] Although the second embodiment of the invention has been described above, the invention should not be restricted to the second embodiment. As a matter of course, the invention may be modified and carried out in various manners without departing from the spirit thereof.
[0090] For example, in the second embodiment, the flexible wall portions 32 are changed from being inclined with respect to the front-back direction to being extended along the front-back direction by a torsional force from the seatback upper frame 28 as well as tensile forces of the coupling members 52. However, the flexible wall portions 32 may also be changed from being inclined with respect to the front-back direction to being extended along the front-back direction by only the tensile forces of the coupling members 52.
[0091] Next, a third embodiment of the invention will be described.
[0092] FIGS. 14A and 14B each show a vehicle seat 60 according to the third embodiment of the invention. The arrows X, Y, and Z shown in these drawings indicate a rearward direction of the seat, an outward direction with respect to a width of the seat, and an upward direction of the seat respectively in this vehicle seat 60.
[0093] The vehicle seat 60 according to the third embodiment of the invention uses the seatback frame 70 instead of the seatback frame 20 in the vehicle seat 10 according to the first embodiment of the invention. The seatback frame 70 is composed of side frame lower portions 72, side frame upper portions 74, coupling frame portions 76, and an upper frame portion 78.
[0094] The side frame lower portions 72 are coupled to the seat cushion frame 16, and extend in the vertical direction. The side frame upper portions 74 are disposed above and widthwise inside the side frame lower portions 72 respectively, and extend in the vertical direction.
[0095) Further, the coupling frame portions 76 extend in the width direction to couple upper regions of the side frame lower portions 72 to lower regions of the side frame upper portions 74 respectively. The upper frame portion 78 constitutes an upper region of the seatback 18, and extends in the width direction to couple upper regions of the pair of the side frame upper portions 74 to each other.
[0096] In the third embodiment of the invention, the side frame lower portions 72, the side frame upper portions 74, and the coupling frame portions 76 constitute seatback side frames 86 respectively. The upper frame portion 78 constitutes a seatback upper frame 88 as the load transmission portion.
[0097] According to the vehicle seat 60 having the above construction, the following specific effects are achieved.
[0098J That is, according to the third embodiment of the invention, when the load applied to the upper frame portion 78 is small, for example, when an occupant leans back against the seatback 18 or has his/her head supported by the headrest 22, the coupling frame portions 76. which couple the upper regions of the side frame upper portions 74 to the lower regions of the side frame lower portions 72 respectively, extend in the width direction of the seat as shown in FIG. 14A.
[0099] Thus, the seatback side frames 86 are flexed at coupling portions thereof between the side frame upper portions 74 and the coupling frame portions 76 and at coupling portions thereof between the side frame lower portions 72 and the coupling frame portions 76 respectively. Therefore, the rigidity of the seatback side frames 86 in the front-back direction is held low.
[0100] Accordingly, when vibrations are transmitted to the vehicle seat 60 as a result of, for example, the movement of the vehicle or the operation of the engine, vibration of the seatback side frames is minimized. Thus, appropriate seating comfort of the vehicle seat 60 may be ensured during normal operation of the vehicle.
[0101] However, if a load equal to or larger than a predetermined value is applied to the upper frame portion 78 of the seat back 18 from, for example, the head of an occupant via the headrest frame 24, as indicated by the arrow Fx, in the event of, for example, a head-on collision of the vehicle, the upper frame portion 78 is deformed toward the rear into an arcuate shape as shown in FIG 14B.
[0102] As indicated by arrows Mz and -Mz, a torsional moment is applied to each side of the seatback upper frame 88 in such a direction as to draw a corresponding one of the seatback side frames 86 inward in the width direction. Thus, the coupling frame portions 16 are changed from a being extended in the width direction as shown in FIG 14A to being extended in the vertical direction as shown in FIG 14B.
[0103J As shown in FIG 14B, when the coupling frame portions 76 extend in the vertical direction, the entire seatback side frames 86. including the coupling frame portions 76, extend in the vertical direction. Thus, the rigidity of the seatback side frames 86 in the front-back direction is higher than during normal use, as described above. Thus, sufficient rigidity of the seatback side frames 86 may be ensured in the event of a vehicle collision.
[0104] Besides, as described above, the vehicle seat 60 according to the third embodiment of the invention has a construction in which vibration of the seatback side frames 86 is minimized by the seatback side frames 86; Therefore, there is no need to provide a vibration damping device, for example, a dynamic damper or the like. Thus, increases in cost and weight may be minimized in comparison with the case where a vibration damping device is provided in the vehicle seat.
[0105] As described above, the vehicle seat 60 according to the third embodiment of the invention ensures both sufficient rigidity of the seatback side frames 86 in the event of a vehicle collision and appropriate seating comfort of the vehicle seat 60 during normal operation of the vehicle with minimal increases in cost and weight.

Claims

CLAIMS:
1. A vehicle seat characterized by comprising: seatback side frames that extend vertically to constitute a right lateral portion and a left lateral portion of a seatback and that may be changed from a first position to a second position, wherein the second position has a higher rigidity in a front-back direction of the seat than in the first position; and a load transmission portion that changes the seatback side frames from the first position to the second position if a rearward load equal to or larger than a predetermined value is applied.
2. The vehicle seat according to claim 1, wherein each of the seatback side frames has a flexible wall portion that are inclined with respect to the front-back direction so that a front region of the wall portion is located further outside in a width direction than a rear region of the wall portion in the first position and that forms a smaller angle with the front-back direction in the second position than in the first position.
3. The vehicle seat according to claim 2, wherein the load transmission portion is a seatback upper frame that has an upper frame portion extending in the width direction to constitute an upper portion of the seatback and that couples upper regions of the seatback side frames to each other.
4. The vehicle seat according to claim 3, wherein each of the seatback side frames has a base portion rearward of the seatback side frame, and the seatback upper frame is coupled to the base portions and applies a torsional moment to the flexible wall portions so that the flexible wall portions turn inward in the width direction when the rearward load is applied,
5. The vehicle seat according to claim 2, wherein the load transmission portion is a coupling member that extends in the width direction to couple each of the flexible wall portion to each other.
6. The vehicle seat according to claim 5, wherein the coupling member is coupled to front regions of the flexible wall portions, and the coupling member curves toward the rear and thereby turns the flexible wall portions inward in the width direction when the rearward load is applied to the coupling member.
7. The vehicle seat according to claim 1, wherein the seatback side frames have i) side frame lower portions that are coupled to a seat cushion frame constituting a seat cushion, ii) side frame upper portions that are disposed above and widthwise inside the side frame lower portions, and iii) coupling frame portions that couple upper regions of the side frame lower portions to lower regions of the side frame upper portions respectively and that extend in the width direction in the first position and in the vertical direction in the second position, and the load transmission portion is a seatback upper frame having an upper frame portion that extends in the width direction to constitute an upper portion of the seatback and that couples upper regions of each side frame upper portion to each other.
PCT/IB2009/000245 2008-02-12 2009-02-12 Vehicle seat WO2009101511A2 (en)

Applications Claiming Priority (2)

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JP2008031143A JP4569642B2 (en) 2008-02-12 2008-02-12 Vehicle seat
JP2008-031143 2008-12-05

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WO2009101511A2 true WO2009101511A2 (en) 2009-08-20
WO2009101511A3 WO2009101511A3 (en) 2009-10-08

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EP2468566A4 (en) * 2009-08-21 2018-01-10 Delta Tooling Co., Ltd. Vehicle seat
CN107878275A (en) * 2013-04-08 2018-04-06 提爱思科技股份有限公司 Auto use chair and its seat frame

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JP5123901B2 (en) * 2009-06-29 2013-01-23 本田技研工業株式会社 Seat back frame for vehicle seat
BRPI1014713A2 (en) 2009-06-29 2019-04-02 Honda Motor Co Ltd seat backrest structure for vehicle seat.
JP2012144135A (en) * 2011-01-12 2012-08-02 Nissan Motor Co Ltd Frame structure of vehicle seat

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WO2006095454A1 (en) * 2005-03-11 2006-09-14 Recaro Japan Co., Ltd. Backrest frame for automobile seat

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2468566A4 (en) * 2009-08-21 2018-01-10 Delta Tooling Co., Ltd. Vehicle seat
CN107878275A (en) * 2013-04-08 2018-04-06 提爱思科技股份有限公司 Auto use chair and its seat frame

Also Published As

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WO2009101511A3 (en) 2009-10-08
JP2009190482A (en) 2009-08-27
JP4569642B2 (en) 2010-10-27

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