Sliding valve

摘要

A valve includes a film (22) having side edges and an opening (24) to extend across a passage (54) in a housing (20) of a HVAC system. The film (22) has a circular aperture (28) in the film (22) adjacent each rounded corner of each opening (24) for relieving stress. Either or both of the leading edge and the trailing edge of the film (22) are undulated (32) to prevent deformation of the edges. A pair of the racks (34) is disposed on the film (22) and sprockets (38) engage the teeth (36) of the racks (34) for moving the racks (34) and the film (22) linearly. Each rack (34) includes a strap (44) and a bearing member (46) for retaining the associated sprocket (38) in engagement with the teeth (36). The bearing member (46) is in rolling engagement with a bearing surface (48) of the associated strap (44) as it rotates with the sprockets (38).