Two-stage energy absorbing system for rotary-wing aircraft seats
A seat and an energy absorbing system for a seat including sequentially activated first and second energy absorbing devices. The first device is resiliently deformable and activates to accommodate less severe dynamic events whereas the second device plastically deforms to accommodate severe dynamic events such as a crash. In use, when a first predetermined load value is exceeded the first device activates until a compressive limit of the first device is reached, after which exceeding a second predetermined load value transfers remaining energy to the second device. In embodiments, the first device operates to permit a limited amount of seat bucket stroking followed by recovery to an original state, and the second device operates to permit continued stroking without recovery to an original state.
1. A seat, comprising:
a seat base;
a seat bucket movable relative to the seat base;
a motion controller coupled between the seat bucket and the seat base configured to control a motion path of the seat bucket, the motion controller including a carrier assembly adjustably coupled to the seat base, and a carriage assembly coupled to the seat bucket and movably coupled to the carrier assembly;
a first energy absorbing device associated with the motion controller and including an elastomeric element, the elastomeric element configured to control stroking motion of the motion controller relative to the seat base; and
a second energy absorbing device associated with the motion controller and including a deformable element, the deformable element movably coupling the carriage assembly to the carrier assembly;
wherein:
when a first predetermined load value on the seat bucket is exceeded, the elastomeric element is configured to undergo resilient deformation to allow the motion controller to stroke relative to the seat base;
when a second predetermined load value on the seat bucket is exceeded, greater than the first predetermined load value, the deformable element is configured to undergo plastic deformation to allow the carriage assembly to stroke relative to the carrier assembly to allow the seat bucket to continue stroking relative to the seat base; and
the first and second energy absorbing devices are separate devices and are configured to activate sequentially such that the first energy absorbing device is configured to absorb first energy from a dynamic event and transfer remaining energy from the dynamic event to the second energy absorbing device.
2. The seat according to claim 1 , wherein the seat base includes guideways and each of the carriage assembly and the carrier assembly include guides configured to travel along the guideways as the motion controller strokes relative to the seat base and/or the carriage assembly strokes relative to the carrier assembly.
3. The seat according to claim 1 , wherein the first energy absorbing device comprises:
a guide member defining an elongated guideway, wherein the elastomeric element is positioned in the guideway; and
a guide positioned in the elongated guideway in contact with the elastomeric element;
wherein, in use, when the first predetermined load value is exceeded, the guide travels along the elongated guideway thereby compressing the elastomeric element.
4. The seat according to claim 3 , wherein the elastomeric element is a natural polymer, a synthetic polymer, a metallic spring, or combinations thereof.
5. The seat according to claim 1 , wherein the deformable element is a singular sheet having an introduced fold, and wherein the sheet is 304 stainless steel sheet and is not heat treated.
6. The seat according to claim 1 , wherein the deformable element is a wire associated with a wire bender system including a plurality of rollers, wherein the wire is threaded through the plurality of rollers such that the wire is configured to be bent and unbent as the wire is pulled through the plurality of rollers.
7. The seat according to claim 1 , wherein the first energy absorbing device is accessible through an opening formed in a back of the seat and the second energy absorbing device is positioned within the seat.
8. An energy absorbing system, comprising:
a first energy absorbing device including an elastomeric element, the first energy absorbing device configured to control stroking motion of a seat motion controller; and
a second energy absorbing device including a deformable element, the second energy absorbing configured to control relative motion within the seat motion controller;
wherein:
when a first predetermined load value on the seat motion controller is exceeded, the elastomeric element is configured to undergo resilient deformation to allow the seat move motion controller to stroke without relative within the seat motion controller; and
when a second predetermined load value on the seat motion controller is exceeded, greater than the first predetermined load value, the deformable element is configured to undergo plastic deformation to allow relative motion within the seat motion controller; and
the first and second energy absorbing devices are separate devices and are configured to activate sequentially such that the first energy absorbing device is configured to absorb first energy from a dynamic event and transfer remaining energy from the dynamic event to the second energy absorbing device.
9. The energy absorbing system according to claim 8 , wherein the seat motion controller is configured to movably couple a seat bucket to a seat base.
10. The energy absorbing system according to claim 9 , wherein the seat motion controller comprises:
a carrier assembly; and
a carriage assembly;
wherein the second energy absorbing device is coupled between the carriage assembly and the carrier assembly and is configured to prevent relative motion between the carriage assembly and the carrier assembly when the first predetermined load value is exceeded and permit relative motion between the carriage assembly and the carrier assembly when the second predetermined load value is exceeded.
11. The energy absorbing system according to claim 8 , wherein the elastomeric element is a natural polymer, a synthetic polymer, a metallic spring, or combinations thereof.
12. The energy absorbing system according to claim 8 , wherein the deformable element is a stainless steel sheet having an introduced fold.
13. The energy absorbing system according to claim 8 , wherein the deformable element is a wire threaded through a plurality of wires of a wire bender system.