Timing is everything when it comes to the efficient operation of the internal combustion engine. For instance, the sparkplugs must fire at the right moment to ignite the fuel/air mixture in the combustion chambers. A premature firing may result in the incomplete combustion of the fuel or the production of very minimal mechanical output. On the other hand, delayed firing may cause the internal moving parts of the engine to lock at awkward positions. Both premature and delayed firings of the sparkplugs have serious consequence on the performance of the engine.
Power might be lost and fuel might be wasted if the firing of the sparkplugs does not follow proper timing. Timing is important in coordinating with the other components of the engine. A timing belt like the Toothed Belt is one mechanism that allows the proper timing and coordination of the different components of the engine. A timing belt connects the camshaft to the crankshaft. Typically, timing belts are toothed belts that relay the rotational motion of the crankshaft to the camshafts.
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Toothed Belt |
Most engines utilize the timing belt because it allows simpler and bigger engine designs. Unlike gear timing mechanisms, timing belt directly connects the crankshaft to the camshaft. Gear timing system may require several gears to connect the camshaft and the crankshaft. This results in a more complex engine design that requires meticulous and expensive maintenance. If one gear becomes misaligned or defective, the entire gear system must be checked and repaired.
On the other hand, engines utilizing Toothed Belts are less prone to malfunction because there are fewer moving parts that need to be maintained. A timing belt like the Toothed Belt regulates the opening and closing of the valves. Since the valves are operated by the camshaft, their timing must be coordinated with the motion of the pistons, which are connected directly to the crankshaft. Although engine mechanical output is produced by the pistons, the crankshaft is the one that translates the linear motion of the pistons into rotational motion.
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Toothed Belt - 8M Section |
Initially, during ignition, the pitons are moved by the crankshaft. The crankshaft initially derives its power from the starter motor that is powered by the automobile batteries. Hence, when the ignition key is turned, electricity from the automobile batteries flows to the starter motor to initiate crankshaft motion. However, the flow of electricity from the automobile batteries is not straightforward. It requires that the electricity must first be amplified several times to be utilized by the starter motor. Hence, the electricity first flows through the ignition coil.
The ignition coil is a step up transformer that increases the voltage of the electricity from the batteries. When the crankshaft is already spinning for some short period of time, real combustion then takes over in powering the engine. When the pistons are in certain positions (e.g., exhaust stroke) the valves must also be in precise positions corresponding to the positions of the pistons. This allows the efficient flow of gases and delivery of mechanical output. To accomplish this, the camshaft rotates at half the rotation rate of the crankshaft. The pulley or gear of the crankshaft is half the diameter of the camshaft. Hence, one complete revolution of the crankshaft is only equivalent to half revolution of the camshaft.
