Patent Application
20090184561
1. Technical Field
The present invention relates to school bus seats and more particularly to a structural member used to reinforce seat joints and thereby control the location and degree of deformation of the seat back upon rear impact by an object.
2. Description of the Problem
School bus seats are built to meet many differing customer specifications. For example, some bus seats must accommodate three point safety belts by providing a compatible upper back rest, other specifications call for a universal child restraint attachment equipped lower frame, while still others provide standard DOT (United States Department of Transportation) seat backs. Alternatively, customers can specify seats in different widths or heights and can demand various strength requirements. School bus passenger seats vary in height and width resulting in different seat back performance characteristics. FMVSS (Federal Motor Vehicle Safety Standard) 222 requirements dictate the seat back deflection be controlled to fall within a specified window of force versus deflection. The specified window has minimum as well as maximum limits for this deflection.
Differing customers' specifications have required substantially or entirely different component sets. The need to supply such component sets has even occurred relative to completed vehicles that have been put into service where the vehicle has been moved from one state or municipality to another, based on differing requirements of the new jurisdiction. The variability in size has contributed to varying component sets meant to meet strength standards. Multiple tubes, brackets and gussets are incorporated into welded seat assembly. Components were added to the various seat assemblies until the resulting design was compliant. Various seat widths and heights may use different hardware based on these changes. Therefore, seats have exhibited additional variation in component parts to meet the FMVSS 222 requirements.
The invention provides for placing the variability relating to seat back strength and the degree of allowed deflection under force to be focused into one reinforcement component. In a modular seat frame the seat back has its foundation in an aisle riser and a wall riser, and includes a perimeter frame provided by a partial perimeter tube mounted at opposed ends in necks extending from the aisle riser and wall riser. A reinforcement member fits into the neck/partial perimeter tube joint. The length of the reinforcement member can be varied, and the reinforcement member itself weakened at some point along its length to vary the strength and allowed deflection under rear impact of the seat back. In the preferred embodiment the length of the reinforcement member can be varied, as well as features such as holes can be added to limit the strength, and increase the amount of energy that is absorbed at the joint. It also allows control of where the bending takes place. This allows common frames to be used across height and width variation, with their resulting differences in the amount of loads that they will absorb.
Additional effects, features and advantages will be apparent in the written description that follows.
The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself however, as well as a preferred mode of use, further objects and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein:
Referring now to the drawings and in particular to
Referring to
Back panel 54 includes a partial perimeter lip 74 by which the panel is attached to tube 52. Risers 46, 48 include inner face contours 76 which position the ends of rear and front supports 56, 60. Risers 46, 48 have integral inwardly turned flanges 78 along their top and front edges. In addition, risers 46, 48 have a back edge flange 71, which are also inwardly turned. Flanges 71 and 78 provide surfaces against which opposite surfaces of the front and rear cross members 60, 56 may be placed to be secured by self pierce rivets (not shown), or other methods such as low temperature welding. Front cross member 60 is substantially formed in three panels, front panel 61, intermediate panel 63, and top panel 65 with panel 63 being intermediate to panels 61 and 65. The angle between panels 61 and 65 corresponds to the angle between the front and top edge sections of flange 78, allowing the cross member to be brought into contact with both portions of the flange concurrently. Panel 63 intersects both panels 61 and 65 obliquely along the respective interior side (i.e. the underside of the member relative to the risers) and positioned between the two panels functions as a cross brace between the flange 78 portions.
Rear cross member 56 incorporates two major sections, a top section 57 and a back section 59. The ends of top section 57 and back section are angled (essentially a right angle) to allow them flush mating of the sections to the under surface of the top portion of flange 78 and the forward surface of flange 71. Self pierce rivets (not shown), glue or welding are used to connect the member to the riser.
Aisle riser 46 includes legs which support the structure from the floor. A plate 68 is provided for securing fasteners between the riser 46 and a vehicle floor. Wall riser 48 includes an attachment lip 72 allowing securing of the wall riser to a wall support. Plate 68 and washer 70 are provided as part of the attachment process.
In one embodiment, reinforcement member 64 is a three sided sleeve having opposed legs 90 and an open face, with examples positioned on the ends of perimeter tube 52 by welds 100. After introduction of the ends of perimeter tube into risers 50, the reinforcement member 64 is sandwiched between a lower riser stamping (46, 48) and the upper seat partial perimeter tube 52 with its open face aligned with the open side of the neck 50 in which it is situated. Thus the member 64 is located at the joint formed between the necks 50 and the ends of the partial perimeter tube 52. It overlaps the tube 52 of the upper frame, and extends above the joint for a distance that is varied according to the loading characteristics that are required. It can also be extended downward. Holes 92 are provided through which bolts 66 can be positioned and which strategically weaken the reinforcement member 64 at the desired locations. Members 64 are positioned to align holes 92 with holes 122 (see
In its preferred embodiment, reinforcement member 64 MIG welded to the inside of neck 50 with its open side coinciding with the open side of the neck. Both neck 50 and reinforcement member 64 are three sided sleeves and an open face. Upon assembly, the reinforcement member becomes sandwiched between the lower riser stamping (46, 48) and the upper seat partial perimeter tube 52 as in the prior embodiment. Again the member 64 is located at the joint formed between the necks 50 and the ends of the partial perimeter tube 52. It overlaps the tube 52 of the upper frame, and extends above the joint for a distance that is varied according to the loading characteristics that are required. It can also be extended downward. Holes 92 of the reinforcement member 52 are provided through which bolts 66 can be positioned and which strategically weaken the reinforcement member 64 at the desired locations. Members 64 are positioned to align holes 92 with holes 122 through the partial perimeter tube 52 and with holes 104 through the necks 50. Member 64 is also attached to the inside of neck 50 using spot MIG (Metal in Inert Gas) welds.
While the invention is shown in only one of its forms, it is not thus limited but is susceptible to various changes and modifications without departing from the spirit and scope of the invention.
