LEG STRUCTURE FOR A SEAT FOR ABSORBING IMPACT ENERGY

Abstract: A leg structure for constituting a seat by mounting a seat bottom (4) and a seat back (5) on a base frame (3) spanning between front and rear beams (1, 2) in which a diagonal member (8) is caused to extend from the front beam (1) supported by a front leg (6) rearwardly of the lower portion of the seat with a rear leg (9) supporting the rear beam (2) being supportedly fixed substantially to an intermediate position of the diagonal member (8), and in which the lower ends of the front leg (6) and diagonal member (8) are fixed, respectively, to floor side rails via metal fixtures. According to this leg structure, impact energy exerted on the seat can be attenuated by virtue of the material characteristics of the diagonal member (8) itself, i.e. plastic deformation by changing the manner in which the diagonal member (8) and leg portions (6,9) that constitute the leg structure are coupled together without the addition of particular shock absorbing devices and members, thereby making it possible to improve the safety of the seat, as well as the safety of passengers by reducing the deformation of the seat after shocks having been absorbed. This leg structure can be used as a leg structure for passenger seat mounted on airplanes, automobiles, trains and so forth.

Description: Technical Field The present invention relates to a technique for absorbing a striking or impact energy exerted on a seat and particularly to a striking energy absorbing seat leg structure according to the upper portion of claim 1 being capable of absorbing an impact load exerted on an front surface side or an upper surface side of a seat upon accident of a vehicle or an aircraft. Background Art For example JP-A-1-145 246 discloses a seat leg structure previously described. US-Patent 4,718,719 discloses a seat leg structure which is designed so that the front and rear support leg members are each of a generally "U"-shape with diverging upper and lower leg portions and with the bends of each "U" secured to each other so that the overall appearance of the structure viewed from the side of the seat is in the shape of an "X". Upon receiving a striking load the leg members are bent accordingly wherein the front leg member maintains a constant curvature in the region of its U-shaped bend near the center of "X". However, various seat shock absorbers have been used. For example, a striking energy generated in the event of failure in landing of an airplane is mostly absorbed by a shock absorber provided on the airplane body side. In the event of automobile collision, the resulting striking energy is absorbed by a shock absorber provided between a bumper and the chassis. In a landing failure accident of an airplane or in an automobile collision accident, however, there is sometimes generated an impact load exceeding the impact absorbing ability of a shock absorber, and in this case a too large impact energy is applied to passengers. As the seat particularly in airplane, in order to absorb such striking energy, there has been used a seat designed so that a special shock absorber is added to a leg portion of the seat or a diagonal member so as to absorb striking energy through a crushing load or a tensile load of the shock absorber. In the conventional seat as described above, the leg structure such as a leg portion, a diagonal member and so on is firmly fixed by bolts and screws at connecting and fixing portions of front and rear beams, the leg portion and the diagonal member, which is not a structure such that when the impact is applied to the leg structure, it is deformed by the impact or the striking energy can be absorbed. Accordingly, in such a case as described, the leg structure should be especially provided with parts or devices for absorbing the shock, resulting in a problem such that not only the leg structure becomes complicated but also the weight constituting the seat increases and the leg structure increases in price. The present invention has been accomplished in view of the aforementioned problems, and it is the object thereof to provide a striking energy absorbing seat leg structure in which a special shock absorber or member is not added to the conventional leg structure but a connecting method of a diagonal member, and a leg portion constituting a leg structure is changed to reduce a striking energy applied to the seat through a material characteristic, that is, a plastic deformation of the diagonal member itself without risking breakage of this diagonal member, thus enhancing safety of a seat. It is further an object of the present invention to provide a striking energy absorbing seat leg structure which can minimize an amount of deformation of a seat after shock absorption to enhance safety for passengers. Disclosure of Invention According to the present invention, there is provided a striking energy absorbing seat leg structure of the kind previously described with the features of the characterizing portion of claim 1. According to the above described structure, as shown by the phantom lines in Fig. 8, in a case, when a striking load G is applied frontwardly of the seat, the leg structure is rotated and deformed rearwardly centered on the front beam while being fixed on the fixed structure on the floor side while the rear side of the base frame is rotated so as to be raised upwardly of the seat, and the rear leg having an upper end connected to the rear beam as well as the diagonal member connected to the lower end thereof are flexed and deformed upwardly to absorb the striking energy. Further, as shown by the phantom lines in Fig. 9, in another case, when a striking load G is applied from the upper part of the seat, the rear side of the base frame is downwardly rotated to the lower part centered on the front beam to transmit said load to the diagonal member through the rear leg, so as to absorb the striking energy by flexing and deforming the diagonal member downwardly. In the above described both cases, a torsional action occurs in the front beam and said torsional action brings forth a geometrical effect with respect to the energy absorbing action of the diagonal member. That is, the striking load applied to the leg structure is absorbed through the disappearance of mechanical energy caused by the flexing deformation of the diagonal member and the torsional action of the front beam. Brief Description of Drawings Fig. 1 is a side view of a seat constituting a striking energy absorbing seat leg structure according to the present invention; Fig. 2 is a front view of a seat constituting a striking energy absorbing seat leg structure; Fig. 3 is an enlarged side view of essential parts relating to a striking energy absorbing seat leg structure; Fig. 4 is an enlarged side sectional view showing a structure of a guide member interposed in a diagonal member; Fig. 5 is an enlarged front sectional view showing a structure of a guide member interposed in a diagonal member; Fig. 6 is an enlarged side view of essential parts showing one example of a fixing fitting member for fixing a lower end of a front leg to a floor side rail; Fig. 7 is an enlarged side view of essential parts showing one example of a fixing fitting member for fixing a lower end of a diagonal member to a floor side rail; Fig. 8 is an explanatory view showing a striking energy absorbing action of a leg structure with respect to an impact applied to the front side; and Fig. 9 is a schematic explanatory view showing a striking energy absorbing action of a leg structure with respect to an impact applied from the upper surface. Best Mode for Carrying Out the Invention A preferred embodiment of a striking energy absorbing seat leg structure according to the present invention will by described hereinafter with reference to the drawings. Figs. 1 and 2 show an embodiment of a triple seat for an airplane which constitutes a leg structure according to the present invention. A base frame is mounted bridgewise between front and rear beams 1 and 2, and a seat bottom 4 and a seat back 5 are placed on the front and rear beams 1 and 2, and the base frame 3 to constitute a seat. The seat back is supported tiltably rearwardly of the seat through a suitable reclining device (not shown). A leg structure according to the present invention is designed so that as shown in Fig. 3, an upper end of a front leg 6 is secured to the front beam 1 through a bracket 7, an upper end of a diagonal member 8 is secured to the bracket 7 coaxial with the front beam 1, a lower end of the diagonal member 8 is extended bridgewise rearwardly of a lower portion of a seat, and the lower end can be secured to a floor side. A rear leg 9 supporting the rear beam 2 has an upper end secured to the rear beam 2, and a lower end thereof is fixedly mounted on a substantially intermediate portion of the diagonal member 8, the rear beam 2 being supported on the diagonal member 8 is formed from a metal tubular body, that is, a square member or the like, and has a rigidity to such extent as not to generate a flexing deformation by a normal using load. A guide member 10 is provided at the fixedly supporting portion of the diagonal member 8 at which the rear leg 9 is fixedly mounted. This guide member 10 is formed with a guide surface 10a curved in the form of a boat on the front and rear end sides in a longitudinal direction of the diagonal member 8 as shown in Figs. 4 and 5, the guide member 10 being fixed together with the rear leg 9 by a fixing means 11 such as a bolt which stops the diagonal member 8. When a striking load is applied to the seat by the guide member 10 whereby the diagonal member 8 is flexed and deformed, a deformation guide action along the guide surfaces 10a is brought forth in the flexing direction of the diagonal member 8, and a cutting and breaking preventive action for the diagonal member 8 in the deformed portion is also brought forth. While in the illustrated example, the guide member 10 has been formed into a block, it is to be noted that the guide member 10 formed of a plate material having a shape similar to that of the former may be lined and fixed to the inner end surface of th diagonal member 8. In the striking energy absorbing seat leg structure according to the present invention, a lower end of the front leg 6 and a lower end of the diagonal member 8, which constitute the leg structure, are secured to a fixing structure 14 such as a rail on the floor side through fixing fitting members 12 and 13 as shown in Figs. 6 and 7. According to the leg structure of the present invention, when a striking load (indicated by an arrow G) is applied frontwardly of the seat, the leg structure itself is rotated and deformed about (indicated by an arrow A) of the front beam 1 while the front leg 6 and the lower end of the diagonal member 8 remain fixed onto the fixing structure 14 such as a rail, the rear portion side of the base frame 3 is simultaneously rotated (indicated by an arrow B) so as to be raised upwardly of the seat to raise (indicated by an arrow C) the rear leg 9 interposed in a substantially central portion between the rear beam2 and the diagonal member 8, and the diagonal member 8 is upwardly flexed and deformed (indicated by an arrow D) by the tensile force to absorb striking energy. When the striking load (indicated by the arrow G) is applied from the above the seat, the rear portion side of the base frame is rotated downwardly (indicated by the arrow B) about (arrow A) of the front beam 1, the load is transmitted to the diagonal member 8 to flex and deform (indicated by the arrow D) it, and the striking energy is absorbed. At that time, the front leg 6 and the upper end side of the diagonal member 8 of the leg structure are forced forwardly (indicated by an arrow E) about the front beam 1. In either case described above, a torsional action is generated in the front beam 1, the torsional action bringing forth the geometrical shock absorbing action together with the energy absorbing action of the diagonal member 8. That is, in the striking energy absorbing seat leg structure, the striking load (G) applied to the leg structure is absorbed by the flexing deformation of the diagonal member 8 and the disappearance of mechanical energy caused by the torsional action of the front beam 1. The striking energy absorbing seat leg structure according to the present invention is constructed as described above. Therefore, a shock absorbing function resulting from a mechanical energy absorbing action caused by flexing and deformation of the diagonal member is imparted to the diagonal member as reinforcing member of the leg structure without increasing and decreasing or changing constituent members in a conventional leg structure, to enable provision of an efficient shock absorbing seat leg structure. In addition, an increase of weight constituting the seat, and since the leg structure is almost the same as that of prior art, it can be simply repaired and adjusted. As just mentioned, there are extremely effects. Industrial Applicability Specifically the striking energy absorbing seat leg structure according to the present invention is provided as a seat leg structure for passengers in an aircraft, an automobile and a railway vehicle. In the event when an airplane fails to land, or a collision accident of an automobile or a railway vehicle is happened, the structure absorbs the generated striking energy to secure safety of passengers.

Claims: A striking energy absorbing seat leg structure wherein a seat bottom (4) and a seat back (5) are mounted on a base frame (3) mounted bridgewise between front (1) and rear (2) beams to constitute a seat wherein a diagonal member (8) is extended bridgewise from said front beam (1) supported by a front leg (6) rearwardly to a lower portion of the seat, a rear leg (9) for supporting the rear beam (2) is supported and fixedly mounted on a substantially intermediate part of said diagonal member (8), and lower end portions of the front leg (6) and the diagonal member (8) are secured to a floor side rail through fixing fitting members (12, 13), characterized in that in the diagonal member (8) for fixedly supporting the rear leg (9) a guide member (10) is provided on said fixedly supporting portion, and that the guide member (10) is fixed to the rear leg (9) and formed with a curved guide surface (10a) coacting with the inner surface of the diagonal member (8) upon flexure of this diagonal member (8) by a striking load applied to the seat structure, so that the deformation action is guided along the guide surface (10a).

Inventors: BAYLISS BRIAN S, SIMPSON LESLIE, BAYLISS, BRIAN, S., SIMPSON, LESLIE,, SIMPSON, LESLIE, JAMES 5 CLIFTON ROAD
Applicants: KOITO KOGYO KK, KOITO INDUSTRIES, LTD.
Application year: 1992
Main classification: B60N2
IPC codes: B60N2, B64D25