The modern internal combustion engine incorporates chain guides and chain tensioners in relation to valvetrain or balanceshaft chain drive systems. Such chains replace, for example, gears and timing belts that connect the crankshaft with the camshafts. While providing superior performance and durability when compared with earlier approaches to linking the crankshaft and the camshafts, timing chains must operate under a predetermined amount of tension to minimize wear and to reduce both vibration and noise.
To answer this need, a timing chain is placed under tension over its entire travel by one or more chain tensioners. Chain tensioning arms commonly provided in internal combustion engines respond to longitudinal stretching of the chain and control longitudinal and transverse vibrations of the chain, which may be caused by excitations arising from the camshaft, the crankshaft and associated components. Chain guides are used in conjunction with the chain tensioning arms to maintain the proper course of chain travel.
Chain tensioning arms apply tension to the timing chain of the engine through tensioning mechanisms. Such mechanisms may be mechanically or hydraulically driven. While providing generally satisfactory results, known tensioning mechanisms are bulky and difficult to package in the given engine space. As automotive engines get smaller and more efficient to satisfy consumer demand and government regulation, engine timing drive systems must occupy a smaller footprint. Known technologies generally fail to minimize the size of the timing chain system.
As in so many areas of vehicle technology there is always room for improvements related to the design of timing chain tensioning systems as used in the internal combustion engine.