Gas Distribution System: Structure? The Damaged And Repaired?

Gas Distribution System: Structure? Damages & Repair?
Latest update date: February 15, 01

Gas distribution system: classification, structure, operating principle? Modern gas distribution systems? The damaged and repaired?

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Working principle of internal combustion engine in car

Over the course of a century of development, the internal combustion engine being on the vehicle today has been greatly improved to increase work efficiency, efficiency, fuel economy ... But there is one thing that during that development it remains constant, that is, the engine cycle. The internal combustion engine equipped in a car, no matter how modern, must perform four operating processes, that is: Load - Compress - Explode - Discharge.

Pictures of Four-Stroke Engines for Cars

In theory, these processes will be divided evenly in two crankshifts, ie 720o, each cycle will be performed in 180o crankshaft rotation. But in fact, in order for the engine to reach its maximum capacity, optimize its performance and give the highest efficiency, the engine must be "Fully Loaded" and "Waste". That means more time spent on charging and discharging, while the remaining two processes will be shortened.

Car Gas Distribution System

Structure of the air distribution system in the car

The gas distribution system is designed to do just that. The gas distribution system is responsible for filling the gas mixture (gasoline + air) or clean air into the cylinder during intake and removing combustion gas from the cylinder during discharge. Based on the above mission, the legal distribution system meets strict requirements such as:

  • Xupap needs to be opened early and closed late depending on the structure of each engine type and operating conditions of the engine.
  • Must open and close at the specified time.
  • Ensure that the combustion chamber is closed during compression and explosion.
  • The valve opening must be large enough for easy air flow into the combustion chamber.
  • Easy to adjust, repair… and other requirements…

Air suspension type air suspension type

Suspension Valve Type Air Distribution Structure

Air suspension type xupap style is commonly used on internal combustion engines fitted to cars and tractors today. The entire gas-mixing mechanism (camshaft, spring, xupap ...) is placed above the machine cover, the camshaft is driven by the crankshaft through a drive belt or by a driving chain.

The rotation speed of the camshaft is half that of the crankshaft

The rotation speed of the camshaft is half that of the crankshaft, that is, when the crankshaft rotates two revolutions, the camshaft rotates one revolution. The reason the camshaft rotates twice as slowly as the crankshaft is because a four-stroke engine completes four “Intake-Compression-Explosion-Exhaust” cycles in two crankshaft revolutions.

Meanwhile, only two cycles "Intake" and "Exhaust" the cam lugs will act to make the intake and exhaust valves open to perform air intake (gasoline engine) or clean air (Diesel engine). into the combustion chamber during the Intake period and expel the exhaust gases from the combustion chamber during the Exhaust period. As a result, the camshaft will rotate twice as slowly as the crankshaft.

The valves can be driven directly by the cam lobes or indirectly through the rocker arm

The xupap can be driven directly by the cam lugs or indirectly through the trigger. These two xupap drive plans are developed and used commonly in TOYOTA, HONDA, BMW, MAZDA, KIA, MERCEDES, AUDI ... models today.

For the direct drive plan, on the tail of the xupap will be arranged teams (also known as blocking cup), the cams when rotating will impact directly on the team, thereby pushing the xupap away. The images above can better describe this process.

For the indirect drive via the stork, the xupap will not be arranged on the tail, but instead the storks. When the camshaft rotates, the cam lugs will impact on the trigger, based on the principle of leverage, the trigger will impact directly on the tail of the xupap with a force many times greater than the other alternative.



A few key details of the gas distribution system


Camshaft is a part designed with very high precision. Camshafts in motor vehicles are usually continuous, with no interconnected segments. The camshafts arranged on the camshaft comply with the explosion order of each type of engine and the function of that cam (loaded or discharged cam or single cam with both cam and waste cam).


SOHC (Single Overhead Camshaft) engines are currently rarely used on automotive engines because the ability to adjust the timing of opening and closing xupap is very difficult and complicated when the engine operates at speed. high. This type of camshaft is easily found on most motorcycle engines (except for a few modern motorcycles and large displacement motorcycles).


DOHC engines using dual camshafts (Dual Overhead Camshaft) are common in today's cars. The ability to independently adjust the opening and closing of the loading and discharging truck becomes easier and more optimal than the single camshaft when the engine operates at high speeds and under a variety of load conditions.


Technologies that change the timing of loading and unloading and discharge of waste trucks on modern vehicles today use this type of dual camshaft structure.


Xupap is responsible for opening and closing the intake and exhaust engines in the order in which the engine operates. The xupap is made of a material that is resistant to high temperatures, little expansion and high rigidity. The structure of xupap can be described as follows:


The xupap has a simple structure, but the manufacturing research is extremely complex. The shape and size of the xupap mushroom greatly affects the ability to fill the engine or air to the engine. The body and tail of the xupap have also been built to a high degree of accuracy to ensure the good working ability of the xupap.

Xupap springs

Xupap springs are parts that always bear the load even when the engine is running or not operating. Xupap springs are made of materials with good elasticity, with very high rigidity. Xupap springs are usually cylindrical springs with a variable pitch to reduce the resonant vibration that causes the spring to break during operation.


There are also other details such as: The stork, the team, the camshaft drive chain, the camshaft drive belt, ...

The modern technology

Internal combustion engines must always operate under a variety of working conditions, so the time the engine completes a period (period) will need to be changed to accommodate those conditions. Today, well-known manufacturers have researched and developed many technologies to optimize the mixing phase on internal combustion engines to increase engine performance. Can list some modern technologies such as:

+. Variable valve technology (VVT-i, dual VVT-i ...) performs adjustment of the camshaft rotation angle or at the same time charging and discharging cam to change the opening and closing of the xupap on TOYOTA and LEXUS models. .


+. Technology to change the lift of i-VTEC lift on cars of HONDA, ACURA.


+. VANOS variable valve timing technology VALVETRONIC is available on all BMW models.


+. And other modern technologies ...

 Damages and faults of gas distribution system

A day-to-day gas distribution system can lead to failures such as:

+. Xupap gap is too large, leading to the engine when operating with a loud knock.


+. The objective cause may also be due to an unsatisfactory previous repair, resulting in a malfunction of the cam, which can lead to an overhaul of the engine again.

Please Contact Us If You Have Any Questions

+. The jammed camshaft causes great abrasion and a loud knock due to the use of poor quality lubricant.

+. And other incidents ...


Please contact us as soon as you have any questions. We are always ready to advise, support, share everything with you!

We are happy to serve you, please contact us at the hotline: 0934 797 179 - 0934 222 763


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2 Commentary

  • Ho Duc Nghia 28/05/2020

    common failures, inspection and repair methods of isuzu engine gas distribution system

  • Deng is filial 19/04/2024

    There are


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