BACKGROUND OF THE INVENTION

[001] This invention generally relates to elevator systems. More particularly, this invention relates to the cab design of an elevator system.

[002] Elevator cab walls are usually created by mounting exterior structural panels between a platform and ceiling. Complementary interior panels align with the structural panels to provide an architecturally and aesthetically pleasing cab interior. The group of structural panels is often identical and the group of interior panels is often identical for manufacturing and installation ease. Various structural borne noise sources, such as tension member interaction with sheaves and guide interaction with guide rails, generate structural excitation that can be easily transmitted into the elevator cab and eventually get radiated as sound energy. Such noise can disturb a passenger, and thus can be a detriment to perceived ride quality and comfort. These panels of the elevator cab are one of the main transmission paths of sound energy. Because these sound energy sources such as sheaves and guides are symmetrical on both sides of the car and because the cab panels share similar junctions to the adjoining structure such as the ceiling on the top and the platform on the bottom, the energy response of the cab panels are usually the same. Since the panels within each group are identical construction, the modal energy of each cab panel is nominally the same, and therefore there is no flow of noise energy between the panels.

[003] There is a need for an improved cab assembly that provides reduced structure borne noise transmission into the elevator cab. SUMMARY OF THE INVENTION

[004] The present invention is directed to an elevator cab. According to one aspect of the invention, an elevator cab comprises a plurality of panels arranged to at least partially define the elevator cab. At least one of the plurality of panels has at least one dissimilar feature than the other of the plurality of panels. Because of the at least one difference in at least one of the plurality of panels, sound energy is diverted to the at least one of the plurality of panels with the at least on dissimilar feature.

[005] According to yet another aspect of the invention, a method for reducing noise in an elevator cab comprises selecting a first group of one or more panels, each having a feature that affects the transmission of sound energy, and selecting a second group of one or more panels, each having a feature that affects the transmission of sound energy. The feature of the panels of the second group are dissimilar to the features of the panels of the first group such that sound energy diverts from the first group of panels to the second group of panels.

[006] According to another aspect of the invention, an elevator cab comprises a plurality of panels. At least one of the plurality of panels has a dissimilar sound energy than the other of the plurality of panels. Sound energy is diverted from the plurality of panels to the at least one of the plurality of panels having the dissimilar sound energy.

BRIEF DESCRIPTION OF THE DRAWINGS

[007] Fig. 1 schematically shows an exemplary elevator system; and

[008] Fig. 2 is a diagrammatic illustration of a partially assembled elevator car. DETAILED DESCRIPTION

[009] Figure 1 is an exemplary illustration of an elevator system 10 including an elevator car 11 and a counterweight 12. Components not relevant to the present invention (e.g. controller, safeties, machine, etc.) will not be discussed. At least one tension member 13 supports the weight of the elevator car 11 and the counterweight 12 in a known manner. The illustration includes exemplary deflection sheaves 14 attached to the top of the car.

[0010] The interaction between the at least one tension member 13 and deflector sheaves 14 during movement of the elevator car 11 can create structure -borne noise and vibration which is transmitted to the cab. Similarly, the interaction between the guides attached to the side of the car (not shown) and the guiderails that run vertically through the hoistway (not shown) can create structure-borne noise and vibration which is transmitted to the cab.

[0011] Although Figure 1 portrays an overslung roping arrangement, with the deflection sheaves located above the car, the present invention could be used with other arrangements, such as an underslung arrangement with deflection sheaves 14 below the car. Similarly, although Figure 1 portrays a 2: 1 roping arrangement, the present invention could be used in systems with other roping arrangements.

[012] Figure 2 shows an exemplary cab panel configuration. The cab panels 17 are typically identical and run vertically from the ceiling 15 to the platform 16 to define the elevator cab. The panels 17 shown could portray either the group of structural panels that form the walls of the cab, or the group of interior panels that form the aesthetic interior of the cab. [013] In the present invention, one or more panels of a first group of panels 17 has a different construction than the remainder of the group. The one of more panels having a different construction than the first group of panels form a second group of panels. The different construction ensures that the modal energy of the panel is different from rest. Since the modal energy of a plate is a function of its parameters such as material density, radius of gyration, longitudinal wave speed, one or more dissimilar panels could vary in any way including size and/or material properties. For example, the one or more dissimilar panels could have a different thickness than the remainder of the group of panels. Also, the dissimilar panel could be divided into two smaller panels. Similarly, if the group of panels is made from steel, the dissimilar panel could be made from aluminum. By changing the construction of at least one panel of the group of panels 17, the modal energy of each panel is no longer the same. This modal energy difference allows a flow of structural energy such that panels will transfer energy from one another.

[014] The configuration of the panels 17 may be designed such that the flow of noise energy through the panels 17 follows a path of least resistance, thereby diverting the energy to certain panels. Though the specific panel(s) selected to have a dissimilar construction may depend on the actual design of the elevator cab, one example location would be a panel located at a corner of the cab. In fact, any of the panels used in the cab could be the dissimilar panel. An alternate embodiment of the invention incorporates the application of sound and vibration absorbing components to the panels of dissimilar construction, thereby effectively containing and dissipating the noise energy.

[015] Ceilings and platforms are mostly designed as a series of panels and the same principle applies to these structural elements as well. Depending on how the structural energy sources such as vehicle guidance system & sheave sources are attached with respect to the platform and ceilings, they may or may not be participating as equipartition of modal energy. If the structural sources are positioned with respect to a group of panels in such a way that the panels are in equipartition of modal energy with respect to one another, one of the members can be made of dissimilar construction to divert energy efficiently for energy containment purposes.