Pull out sofa bed

Abstract

This pull out sofa bed is an improvement of the sofa bed disclosed in U.S. Pat. No. 3,984,883 dated Oct. 12, 1976 and assigned to the assignee of the present application. In said patent bed there is in effect a lost motion during which no work of compressing the mattress is being performed while slack is being taken up. Consequently the work required to compress the mattress and create the necessary locking of the compressed mattress, is concentrated over a relatively short part of the closing cycle of the folding of the bed. The result of this is that a relatively high 'peak' force is required at this portion of the cycle to close the bed and compress the mattress and lock the bed in closed position, thereby requiring exertion of considerable strength by the person closing the bed. The patented bed is satisfactory when the mattresses were made of polyfoam. However, heavy inner-spring mattresses are now being used also and it takes greater strength to fold the beds when using such heavy inner-spring mattresses. The bed disclosed herein has means for spreading the work necessary to compress the mattress over a much larger portion of the closing cycle, thereby reducing the peak force required to close the bed. Another shortcoming of the bed of U.S. Pat. No. 3,984,883 was that the installation of the helical spring when used in a maximum tension position of multi-tension positions, was very difficult. Another shortcoming was that the high force required to stretch the helical coincided in the bed closing cycle with the peak of the mattress compression force and was additive in causing an excessively high closing requirement. In the present design, one end of the main helical spring is anchored to one of a plurality of holes equidistant from the pivot point of the main lever controlled by the spring thus permitting a far simpler installation.