Why is the intake valve larger than theexhaust valve? designers have special an interpretation in designing everything, and also so are valves.

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This write-up contains the following:

Why is the input valve bigger than theexhaust valve

Influence of airflow resistance

Influence of engine speed

1.Why is the entry valve bigger than theexhaust valve

The valve is opened by the cam and also the valve spring is closed. Once the mixture needs to be sucked right into the cylinder, theintake valve will open; as soon as the exhaust gas after burning needs to it is in discharged, theexhaust valvewill open.

Since the intake waiting is \"sucked in\" and the exhaust gas is \"pushed\" out, the intake waiting is more daunting than the exhaust gas, and also the an ext intake air, the much better the combustion and also the far better the engine performance. The intake wait is suck by vacuum, and the exhaust gas is pushed out to push the exhaust gas. Therefore, exhaust is easier than intake. In order to get an ext fresh air to get involved in the combustion, therefore, an ext intake waiting is needed. For this reason, the input valve demands to be larger, and the as whole size has not changed, and also theexhaust valvecan just be make smaller. Therefore, the intake valve is normally designed to be bigger than theexhaust valveto reduce the challenge of intake and increase the amount of intake air. Some just design an additional intake valve, i m sorry only has 3 valves (2 right into 1 row) and 5 valves (3 into 2 rows) design.

2.Influence of airflow resistance

In theory, the amount of inflation and also the lot of exhaust are equal, and the opening and also closing time of theexhaust valveand the opening and also closing time that the entry valve are additionally equal.

But this is no the case, since the throttle valve controls the rotation speed, the valve opening and also closing are large and small, and also the cylinder have to be filled through a mixture of air same to atmospheric push (about 1 kg / cm2) when the suction is completed. But when the gas flows v the intake pipe and also the input valve, it is topic to resistance. In stimulate to get rid of these resistances and permit the mixture to circulation at a particular speed, component of the pressure have to be consumed by the wave, so the air pressure in the cylinder is always lower than atmospheric pressure. The gas density alters with the pressure, and also the low pressure thickness is reduced, and also the actual load of the mixed gas is reduced. Come solve and also reduce the influence of air circulation resistance, the cross-sectional area the the air flow path in ~ the intake valve should be increased, that is, the area the the waiting valve need to be increased. In the case of slim air in the plateau area, the area that the waiting intake passage should be increased, otherwise the engine will certainly not with its rated strength in these areas.

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3. Affect of engine speed

In the instance of the original airway size unchanged, the suction pressure will also change according to the speed and also load. When the accelerator valve is kept completely open, the speed varies with the load. Assuming the the inflation weight is 1, the speed is raised from 700 come 2 per minute, and also the pressure is diminished from 0.95 to 0.80 in ~ 100 rpm, which reflects that the cylinder

The thickness of stick air is reduced, and also the air flow can not keep up with the need of the inflation amount. Because when the rotation speed is tripled, the piston motion speed is likewise tripled, and the airflow rate is also tripled come ensure that the very same weight air rest enters the cylinder. However, due to the increased force in the airway in ~ high speeds, the airflow cannot be boosted in the exact same proportion. The is, the inflation result is much better when decelerating, and as a result, the average effective pressure and also torque are additionally larger (torque is proportional to the average reliable pressure).