On door interior trims, the arm rest may be compressed or pushed together upon impingement by a vehicle occupant during a side impact, to absorb shock energy, reduce force application and lower risk of injury to the occupant. It is therefore desirable to configure the arm rest to be compressible, in a yielding and soft manner, transversely to the longitudinal vehicle axis or perpendicularly to a door beam plane. In addition, a need exists to design the arm rest with high rigidity in the vertical direction to ensure its bracing function for the occupant's arm or elbow. The rigidity of the arm rest in the vertical direction furthermore defines the quality perception of the customer and is therefore valuable.
Because arm rests, door interior trims and the beams thereof are usually produced using an injection molding process, the design options are limited by the demolding direction of the molds. Door interior trims are generally released from the mold transversely to the longitudinal vehicle axis. In the injection molding process, rigid structures may be implemented relatively easily in the demolding direction, while structures transverse to the demolding direction are more difficult to implement. Consequently a problem arises when designing door interior trims that are configured to be soft and yielding in the demolding direction, but rigid and firm transversely to the demolding direction, particularly in the arm rest region.
Current solutions may compromise between high rigidity in the vertical direction and impact requirements, or include additional components or complex molds and increase costs.
German Patent Application No. 10 2010 040 021 A1 discloses a beam of a door interior trim and a separate arm rest beam. Both an overhang of the door beam receiving the arm rest beam and the arm rest beam itself may be configured to yield in the transverse vehicle direction. The rigidity in the vertical direction is created by vertically situated ribs, which may be part of the arm rest beam or door beam. The compressibility may be effectuated by openings in the overhang of the door beam and/or of the arm rest beam. The beams may be at least partially bridged by the ribs to improve the lack of rigidity. The disadvantages include that the loads are distributed among at least two components, the components are complex to produce and the components must be configured for integration into each other.
German Patent Application No. 29 43 259 A1 discloses a door-closing handle and arm rest for the passenger compartment of a motor vehicle. The handle may be made of an elastically yielding material and may be stabilized by an insert comprising a rib structure formed perpendicularly to the beam surface to absorb kinetic energy in the event of a side crash.