Reclining seat to mitigate the effects of mine blast load on spine and lower leg injuries

A seat assembly reclines during an under-vehicle explosion or other upward impact on the vehicle to mitigate spinal and lower leg damage to a human occupant. The seat assembly has a back frame portion and a lower frame portion. The lower frame portion has a pivotal connection with an energy absorbing mechanism mounted to the vehicle floor. The pivotal connection includes a stop mechanism to prevent seat assembly tilt during normal vehicle operation but allow tilt due to an explosion. A second mechanism is disposed between the back frame portion and the floor; this mechanism controls the seat assembly pivot and provides further absorbing of energy from the upward impact. Projections from the front of the lower frame portion toward the floor can be used to enhance seat assembly pivoting; specially designed seat engagement levers can be used for this purpose as well.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention herein relates to the structure of seats in vehicles wherein the seats are designed to protect their occupants from violent impacts to the vehicle by means of energy absorbing devices incorporated into the seat structure. The invention more particularly relates to seats that pivot or otherwise move in reaction to the violent impacts so as to enhance occupant protection.

2. Background Art

In U.S. Pat. No. 8,087,729 B2 to Kladde, FIG. 7 in light of FIGS. 57 and 58 shows a seat that pivots on a number of axes; Kladde also shows a shock absorber connected between the back rest of the seat and the floor of the compartment where the seat is installed. European Patent EP 0834271 B1 to Bieselt at FIG. 1 shows a chair whose seat pan and back rest tilt backward wherein a coil spring resists tilting and biases the chair toward an upright position. U.S. Pat. No. 4,790,595 to Hensel et al. shows a pivoting seat where the pivot axis is located at the front edge of the seat pan. European Patent EP 0799741 to Gimbel shows a seat pivoted at the front edge of the seat pan, there being a coil torsion spring to resist tilting motion. U.S. Pat. No. 7,878,312 to Chen et al. shows an energy absorbing mechanism underneath a seat. U.S. Pat. No. 5,082,311 to Melotik shows a pin and slot feature at FIG. 4 wherein a pin forced along a slot narrower than the pin's diameter so as to deform a narrow strip of metal in a collapsible steering column assembly wherein impact energy is absorbed by the strip. A modified pin-and-slot feature preferably having a detent is incorporated into our seat assembly to control the assembly's pivoting.

SUMMARY OF THE INVENTION

The invention is a seat assembly and associated structure in a vehicle which reduces or eliminates damage to the spinal columns and lower legs of vehicle occupants when land mines or like munitions detonate beneath the vehicle, or when other upward impacts on the vehicle occur. The seat assembly reclines under the influence of an upward impact so that the occupant's spinal column is also reclined and thus is better able to tolerate the impact. The seat assembly is constructed so that the occupant's feet are lifted from the floor in the event of an under-vehicle explosion, whereby the sudden rise of the floor relative to the rest of the vehicle does not jolt the feet and cause injury to the lower limbs of the occupant. The seat assembly includes a seat assembly frame having a lower frame portion fixed to a back frame portion. A shock absorber, or other mechanism for absorbing energy, supports the seat assembly on the vehicle floor. A pivotal connection between the lower frame portion and the shock absorber is disposed near the front edge of the lower frame portion. A stop mechanism is incorporated in the pivotal connection for preventing tilting of the seat assembly when less than a predetermined amount of tilting force acts on the seat assembly, whereby the seat assembly tilts when an under-vehicle explosion occurs, but does not tilt during normal vehicle operation. In a second embodiment of our seat assembly, a projection extends down toward the floor from the front edge of the lower frame portion of the seat assembly frame. The projection engages a zone of the floor that rises faster than the rest of the floor during an under vehicle explosion and accelerates the tilting of the seat assembly. The accelerated tilting by the protrusion is enhanced as the seat assembly compresses the energy absorbing mechanism and lowers toward the vehicle floor. In a third embodiment of the seat assembly, the protrusion is replaced by a dog-leg lever pivoted on the floor beneath the assembly. The lever has one leg that engages the faster rising zone of the floor and another leg that pulls on a strut extending from the back frame portion of the seat assembly. Due to the lever's operation the faster rising zone imparts a pivoting force to the seat assembly.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Definitions and Terminology:

The following definitions and terminology are applied as understood by one skilled in the appropriate art.

The singular forms such as “a,” “an,” and “the” include plural references unless the context clearly indicates otherwise. For example, reference to “a material” includes reference to one or more of such materials, and “an element” includes reference to one or more of such elements.

As used herein, “substantial” and “about”, when used in reference to a quantity or amount of a material, dimension, characteristic, parameter, and the like, refer to an amount that is sufficient to provide an effect that the material or characteristic was intended to provide as understood by one skilled in the art. The amount of variation generally depends on the specific implementation. Similarly, “substantially free of” or the like refers to the lack of an identified composition, characteristic, or property. Particularly, assemblies that are identified as being “substantially free of” are either completely absent of the characteristic, or the characteristic is present only in values which are small enough that no meaningful effect on the desired results is generated.

Concentrations, values, dimensions, amounts, and other quantitative data may be presented herein in a range format. One skilled in the art will understand that such range format is used for convenience and brevity and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a size range of about 1 dimensional unit to about 100 dimensional units should be interpreted to include not only the explicitly recited limits, but also to include individual sizes such as 2 dimensional units, 3 dimensional units, 10 dimensional units, and the like; and sub-ranges such as 10 dimensional units to 50 dimensional units, 20 dimensional units to 100 dimensional units, and the like.

For a vehicle, and a system mounted on or used in connection with the vehicle, forward/reverse (longitudinal) and vertical (up/down) directions are generally relative to the vehicle and system as typically operated (e.g., when the vehicle is operated with the respective powertrain in a forward/reverse mode). As such, lateral (left/right) directions are generally perpendicular to the longitudinal/vertical plane, and are referenced from a vehicle operator (e.g., driver) perspective. A first direction (e.g., forward) and a second direction (e.g., rearward or reverse) where the second direction substantially, but not necessarily wholly, opposes the first direction are also generally or used in connection with the vehicle. Likewise, elements located (mounted, positioned, placed, installed, etc.) on, near, or proximate to the vehicle body are generally referred to as “inner”, while elements that are distal or more remote to the vehicle body are generally referred to as “outer”, unless otherwise noted. As such, inner elements are generally closer to the vehicle body than outer elements. Unless otherwise stated, a vehicle is presumed to be standing on a horizontal surface and vehicle components, such as a body panel or window that are vertically oriented, are disposed normal to the horizontal surface. Likewise, “the vertical” or a “vertical plane” refers to a plane normal to the horizontal surface upon which the vehicle rests.

InFIG. 1is shown a seat assembly100having a generally L-shaped frame102having a lower portion103and a back portion105; these portions are preferably rigid and fixed relative to one another so that the occupant's feet and legs are lifted when seat assembly100reclines. Attached to lower portion103is a bottom cushion104and attached to back portion105is a back cushion106. The seat assembly is mounted to and supported on vehicle floor108by a collapsible energy absorbing mechanism such as a spring loaded cylinder or other type of shock absorber110; this shock absorbing mechanism is the primary means by which energy of vertical force components from under-vehicle explosions is absorbed. The seat assembly has a seat pivotal connection112to shock absorber110at or near the front edge114of frame102, details of this connection being shown inFIGS. 3 through 7. A shock absorbing strut116is connected between the rear of frame102and floor108, strut116typically a being a spring loaded cylinder. Strut116provides a controlled resistance and slowing of the pivoting of seat assembly100. Strut116also is a secondary means to absorb energy of vertical force components from under-vehicle explosions and preferably is less resistant to compression than is shock absorber110. Neither shock absorber110nor strut116needs to be a spring-and-damper arrangement but can alternately be brackets that yield plastically or wires or rods that bend to take up mechanical energy; in some cases plastically deformable elements may preferred to spring-and-damper arrangements. The human occupant118of the seat assembly is shown in dashed lines as is a backpack120worn by the occupant. Backpack120is typically a camel-back water carrier but can be another type of container or personal equipment of the occupant. The occupant is in a forward or upright seating position as is normal for occupants of military vehicles, as opposed to a slightly reclining position normal for civilian passenger vehicles. Preferably in theFIG. 1embodiment, the combined center of gravity of the occupant and the backpack is rearward of pivotal connection112; by this arrangement, when floor108is accelerated by an under-vehicle explosive blast or other upward impact, the inertia of the occupant's mass will cause seat assembly100to swing clockwise about the axis of pivotal connection112as viewed inFIG. 1.

FIG. 2shows details of the connection between strut116and frame102, wherein upper end122of the strut includes apertured flange124. Frame102includes a cross member126from which protrude a pair of ears128having through holes130. A partly threaded pin132passes through ears128and flange124such that relative pivotal motion between the flange and ears is allowed, so that frame102and strut116can have a rotational motion component with respect to one another. The pivotal connection between strut116and floor108can be similar wherein flange134on lower end136of the strut engages with ears138protruding from the floor. It is preferred that strut116as shown inFIG. 1is in its fully extended position so as to prevent forward tilting of assembly100while providing controlled resistance to rearward or clockwise tilting as viewed in that figure. Strut116acts as a stabilizer for seat assembly100in that the strut prevents all motion of the assembly except for controlled rearward tilting or vertical motion.

The pivotal connection between shock absorber110and frame102is shown inFIG. 3wherein a rounded plate-like dog140is affixed to the top of shock absorber110. A lock finger142protrudes from one side of dog140and a bore144is defined through the dog. A complementary plate-like dog146is affixed to a frame cross member148, cross member148typically being attached to frame102in the same fashion as cross member126inFIG. 2. As best seen inFIG. 5, dog146has a through bore150that axially aligns with bore144of dog140. A partly threaded pin152passes through bores144and150, the threaded portion154located at one end of the pin's shaft, where nut157fastens to the pin. The potions of the pin's shaft within the bores are smooth and journal with the bores. Encircling the portion of pin152between dogs140and146is a torsion spring158which resists pivoting of seat assembly100in a backward direction or a clockwise direction inFIG. 1. Spring158engages posts160and162on dogs140and146respectively.

Finger142passes through an opening comprised of aperture164and slot156, the aperture being at one end of arcuate slot156. Aperture164is preferably circular in shape to accommodate finger142and has a diameter or width greater than cross width t of slot156. An enlarged view of slot156is shown inFIG. 7with an annular space between finger142and aperture164; the fit between finger142and the aperture is actually preferred to be close. The annular gap is shown for illustrative purposes to enable a viewer to more easily distinguish finger142from aperture164. The diameter or width of finger142is greater than the cross width t of slot156so that finger142remains in aperture164unless a predetermined sufficient tilting force is exerted seat assembly100. If such a sufficient tilting force acts on assembly100, then finger142is forced it to travel along slot156. As finger142travels along the slot, the slot is deformed and provides resistance to the travel. The combination of finger142, aperture164and slot156comprise a stop mechanism that prevents seat assembly100from tilting about pivotal connection112during normal operation of a vehicle where assembly100is installed; thus, as the vehicle traverses over terrain, seat assembly100will not swing back and forth. However, should a land mine explode under the vehicle, the upward blast force component will create a pivotal force on seat assembly100such that finger142will be forced to travel along slot156. It will be noted that the thickness t of the slot need not be constant but can be varied along the slot's length to provide a programmed resistance to the tilting of seat assembly100.

FIG. 14shows a variation of the pin-and-slot arrangement ofFIG. 7wherein a detent170is mounted on pivot connection112, the detent being a flexible member and preferably being a finger-like cantilever spring. The detent is attached to pivotal connection112at base171by screws or a welding or other conventional fastening means. Affixed to pivotal connection112is a post172, the detent being biased against post172at a side of the post faced away from aperture164. The detent extends across arcuate slot156and is elastically deformed by lock finger142as the lock finger moves from itsFIG. 14position to the opposite end of the arcuate slot. Slot156optionally has a widened portion155where the detent crosses the slot so that finger142can more easily pass post172and detent170. After lock finger142has completely passed by the detent, the detent reassumes its position shown at170and the detent then prevents lock finger from travelling back toward aperture164. Consequently, seat assembly100is retained in a reclined position. The detent's use may be preferred when either shock absorber110or strut116exhibits at least party elastic deformation—as opposed to completely inelastic deformation—when the seat assembly tilts due to an under-vehicle explosion. The detent is a post-impact retention means in that the detent keeps the seat assembly tilted until the vehicle hits the ground after being lifted by the explosion. The detent counters any tendency of shock absorber110or strut116to return the seat assembly to its upright or pre-explosion position.

Typically, portions of a vehicle floor rise relative to the rest of the vehicle as a result of under-vehicle explosions and the floor rise contributes to lower limb injuries of personnel in the vehicle. To address this problem, it may be preferred that the pivoting of seat assembly100be completed relatively quickly, before shock absorber110is fully compressed or before the shock absorber is compressed by a chosen percentage of its total compression distance. The resistance to the seat assembly's pivot provided by pivotal connection112and strut116can be controlled accordingly by the design of these elements. The advantage of the relatively quick pivoting of seat assembly100is that the occupant's legs and feet will be swung upward before vehicle floor imparts force from an under-vehicle blast to the occupant's feet, so that the occupant's feet and legs are less likely to be injured.

InFIGS. 8 and 9is shown a second embodiment of our invention, which is the same as the first embodiment but has two modifications thereto. InFIGS. 8 and 9seat assembly200has a generally L-shaped frame202to which is attached a bottom cushion204and a back cushion206. The seat assembly is mounted to vehicle floor208on an energy absorbing mechanism such as shock absorber210. The seat assembly has a pivotal connection212to shock absorber210wherein the pivotal connection and shock absorber are disposed underneath a central region of bottom cushion204. A shock absorbing strut216is connected between the rear of frame202and floor208, strut216and its connections being similar to what is shown in the first embodiment.

The first modification is that pivotal connection212is more remote from front edge214of frame202than pivotal connection112is from front edge114of frame102in the first embodiment. It is recognized that having pivotal connection212more rearward or remote from the front edge of the L-shaped frame may slow pivoting of the seat assembly as influenced by the occupant's center of gravity. However such a location of pivotal connection212still allows the occupant's center of gravity to cause pivoting of assembly200, and such a location of pivotal connection212may be advantageous in light of overall design considerations when constructing the cabin area of a military vehicle.

The second modification is used to enhance the pivoting of seat assembly200, the second modification being a protrusion extending downward from the front of frame202. The protrusion can be one or more posts extending from edge214toward floor or posts extending from floor208toward edge214, or similar structures. InFIGS. 8 and 9, the protrusion takes the form of a U-shaped channel218fastened to the front edge214of frame202. Channel218has two vertically oriented legs220and a lower channel portion222connected therebetween, and rubber grommets224or other elastomeric bodies are disposed between channel portion222and floor208. Grommets224can be eliminated so that there is a gap between lower channel portion222and floor208or channel member can be disposed on the floor so that the protrusion extends the entire span between edge214and floor208.

As alluded to previously, during an under-vehicle explosion the vehicle floor rises relative to the rest of the vehicle. In many cases the rise of the vehicle floor in front of vehicle occupant seats rises more than does the floor beneath the vehicle seats; such a phenomenon commonly occurs where there are side-facing seat assemblies in rear compartments of some military vehicles. In any case, depending on the exact location of an under-vehicle explosion, the section of the vehicle floor directly in front of a seat assembly can rise faster than the portion of the floor immediately below the seat assembly. Thus inFIG. 8, vehicle floor portion208adirectly in front of seat assembly200can rise more quickly than vehicle floor portion208bimmediately below the seat assembly as the result of an under-vehicle explosion. In this situation, floor section208awill raise channel218or other, equivalent protrusion, whereby seat assembly200is tilted backward or clockwise inFIG. 8. Also in this situation as shock absorber210is compressed, channel218holds up the front of the seat assembly200while allowing the back of the seat assembly to lower, whereby the tilting motion of assembly200is enhanced. It should be noted that the foregoing tilting effects caused by channel218are in addition to, and independent of the tilting effect caused by the occupant's center of gravity.

InFIG. 11is shown a third embodiment of our invention, which again is the same as the first embodiment aside from the two modifications now described. InFIG. 11, seat assembly300has a generally L-shaped seat frame302to which is attached a bottom cushion304and a back cushion306. The seat assembly is mounted to vehicle floor308on shock absorber310. The seat assembly has a pivotal connection312, in all respects the same as pivotal connection112, to shock absorber310at or near the front edge314of frame302. The first modification in theFIG. 11embodiment is the addition of a recline-assist feature not featured in the first embodiment. The recline assist feature comprises a frame316disposed under seat assembly300, the frame having two dog-leg levers wherein each lever has a foreleg320and an aft leg324. Frame316is pivotally connected to floor308at a pivot connection at block318, which is located behind shock absorber310and under a central region of bottom cushion304. Forelegs320extend from the pivot block to a point forward of shock absorber310and forward of310front edge314of seat frame302. The free ends of forelegs320are disposed over a zone308aof the floor immediately in front of seat assembly300and the forelegs can extend further forward along zone308athan is shown inFIG. 11if desired for a particular application. Optionally a rubber grommet322or other elastomeric body can be placed between the free ends of forelegs320and floor zone308aor else the free ends can be in contact with zone308. Preferably, transverse members323are affixed between forelegs320such that frame316is a rigid structure. Aft legs324extend from forelegs320, there being apertures326at the region of frame316where the forelegs and aft legs meet. Pivot pins328(SeeFIG. 11.) pass through apertures326and through blocks318so as to create a rocking or pivoting connection of the dog-leg levers with blocks318.

Seat assembly300includes shock absorbing struts330generally similar in construction to strut116; struts300are pivotably connected in any suitable conventional fashion between the rear of frame302and aft legs324, struts330typically being spring loaded cylinders. As with strut116, struts330need not have a spring-and-damper construction, but can alternately be brackets that yield plastically or wires or rods that bend to take up mechanical energy. The second modification to theFIG. 11embodiment is that struts330are in tension during normal vehicle operation before an under-vehicle explosion occurs. Thus were it not for the stop mechanism in pivotal connection312, which is similar to the stop mechanism in pivotal connection112, seat assembly300would pivot backward or clockwise as seen inFIG. 11.

When an under-vehicle explosion occurs, seat assembly300will swing or pivot backwards due to two independent phenomena. One phenomenon is the effect of the occupant's weight on seat assembly300. As a result of the explosion, the vehicle will rise suddenly and consequently seat assembly300will rise as well, whereby the occupant's weight or inertia will create a downward force vector332relative to assembly300. This force vector will cause assembly300to pivot backward such that the occupant is in a reclined position and the occupant's feet are lifted off floor308. The second phenomenon also occurs as a result of the explosion; namely, floor308will buckle upward such that the floor, or at least portions thereof, will rise faster than the rest of the vehicle. In many cases, and perhaps in the majority of cases, zone308aof the floor will rise faster and further than the rest of the floor and will create an upward force on forelegs320of dog-leg frame316. The upward force pivots frame316and causes the frame to pull struts320downward so as to pivot seat assembly backward300to a reclined position.

Various alterations and modifications will become apparent to those skilled in the art without departing from the scope and spirit of this invention and it is understood this invention is limited only by the following claims.