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Teknikimobil.com-After in the previous article we discussed the working principles of automotive four-stroke engines, now we will discuss the types of cylinder arrangement and valve drive. Various types of cars and light trucks usually have 3, 4, 5, 6, 8 or more cylinders.
Honda Acura V8©autoblog
The cylinders are arranged in three ways, namely inline , V-shape, or opposite each other. These three arrangements are simply shown in the following figure.
Type of cylinder arrangement.
Actually, there is another type of cylinder arrangement, namely the radial arrangement, but this kind of cylinder arrangement was used in aircraft engines and was used before the jet engine era (mid-20th century).
Mitsubishi Galant VII 2.0 24 V V6 ©AutoData1
Engines with V-arranged cylinders like this are often used in passenger vehicles ( passanger cars ) which prioritize acceleration rather than engine torque. This is clearly commensurate with the purpose for which the vehicle was made, namely passenger vehicles, especially city cars , which require vehicles to be small in size but have fairly good acceleration, in addition to other purposes. This is in contrast to the purpose of goods transport vehicles and public transportation, namely trucks and buses. These two types were made with the aim of being able to carry a large number of goods and/or passengers. So acceleration is not really a consideration, but large torque is the main requirement for making these two types of vehicles. Therefore, it is not a problem if a vehicle like this uses in-line cylinders, even 6 or 8 cylinders, as shown in the following picture.
-3d-1-300×258.jpg The cylinders are arranged in a row (shown in the picture is only the cylinder block) © ebay
Meanwhile, in an engine it cannot be separated from the valve actuation. In one full cycle of a four-stroke engine, completing one stroke requires the crankshaft to rotate twice. Two 360 degree rotations of the crankshaft mean the crankshaft has covered a total angle of 720 degrees for one total cycle. During these two revolutions, each cylinder’s intake and exhaust valves open once. These valves are opened by the camshaft , which is sometimes referred to as the “heart” of the engine. The valve axle has a kind of “protrusion” ( lobe ) which functions to push the valve retaining component so that when it is right in the middle of the valve axle protrusion the valve or valve will open. The overall components of the valve driver are as shown in pictures (a) and (b) below.
One of the cars with a DOHC type engine ©google
Especially for the OHC type, usually some use more than one valve axle and are referred to as DOHC ( Double Overhead Camshaft ). Whether using one or two valve axles, everything is driven through the rotation of the crankshaft using several combinations, including a set of gears ( timing gear ) or using a chain ( timing chain) and also a belt ( timing belt ). The crankshaft must rotate twice to produce one movement of the valve shaft.
Timing gear ©Offroad
Valve drives that use several gears ( timing gear ) are usually used for trucks and buses. The advantage of this type of valve actuation is that it is long-lasting provided that lubrication is well maintained. However, the weakness of this type is that the engine will be a little noisier compared to the chain and belt valve drive type.
-3i-300×225.jpg Timing chain ©ToyotaHilux
The Toyota Hilux is an example of a machine that uses a chain type valve drive. The choice of using a chain type is a choice that takes the middle path between gears and belts. This is seen from the engine noise level. The engine sound is not too harsh but can still be well received by passengers in the wheelhouse. Chain drive engines are usually used for small trucks. Although quite a few have used this type of belt on the pretext of a smooth engine sound.
-3j-300×210.png Timing belt © dennisservice
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Among the valve drives most often used in private vehicles is the belt type ( timing belt ). Even though it is not very durable in terms of material strength, this type of belt offers comfort, namely providing a very smooth engine sound. Cars such as the Mitsubishi Lancer, Honda Jazz, Toyota Yaris, all use this type of valve actuation.[]