Multiple ratio manually shiftable transmissions contain a plurality of intermeshing gear sets for providing the range of output torques needed for efficient vehicle operation. Each of the gear sets include at least two intermeshing gears. The teeth on such gears are precisely machined such that the tolerances therebetween are substantially eliminated, however a minimum of gear backlash is required. As with any machining process, however, a build-up of tolerance is unavoidable resulting in a range of gear backlash. Because the transmission is connectable to the engine, the torsional acceleration of the engine excites the rotating gears in the transmission causing them to vibrate within the range of backlash, thus creating gear rattle.
Various devices have been proposed to solve the gear rattle problem. One proposal involves using a brake-like device on the gears. Unfortunately, such devices add friction and, thus, heat to the transmission. Moreover, such devices steal torque from the system. Another proposal involves the use of a scissor gear mechanism. As those skilled in the art may appreciate, scissor gear devices are expensive. Moreover, scissor gear arrangements operate on only one gear set at a time. Accordingly, such approach requires a multiplicity of such devices thereby adding substantial costs to the transmission.
USPTO Backgrounds
USPTO Backgrounds