27
2025
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08
Don't underestimate this small jar, if you don't change it, the brakes may fail
The brake system is a special device that causes the external force on certain parts of the car to promote a certain degree of braking. At present, most of the domestic medium-sized and above trucks use air pressure braking. The driving safety of a car is closely related to braking performance, and brake failure caused by brake system failure is the main cause and the main factor causing traffic accidents.
▎1. Why install an air dryer?
In the air brake system of the automobile, the air compressor outputs air containing impurities such as water vapor, which may be converted into liquid water again if not treated, and combine with other impurities to cause corrosion, and even freeze the gas pipe at extreme temperatures, causing valve body failure.
In the past, the treatment of compressed air mainly used the method of wet gas reservoir, that is, the installation of a wet gas storage simple pre-drainage device with a water release valve in the air path. This device has a certain drying and filtration effect, but it can never remove the water in the air path, and it needs to be discharged and treated with water, oil and other dirt accumulated in the gas storage cylinder regularly, which is very inconvenient to use.
▎2. The role of air dryer
It is installed behind the air compressor and before the four-circuit protection valve to cool, filter and dry the compressed air, remove water vapor, oil, dust and other impurities, and provide dry and clean air for the brake system.
Automotive air dryer is a regenerative dryer that uses molecular sieve as its desiccant. Molecular sieve is an artificial synthetic desiccant product with strong adsorption effect on water molecules. Its main component is an alkali metal aluminosilicate compound with a microporous structure, and there are many uniform and neat pores and holes in the structure.
Water molecules or other molecules are adsorbed on the inner surface when they pass through the pores, which has the effect of sieving out molecules. The molecular sieve has a large adsorption-to-weight ratio and can still hold water molecules well in a high temperature environment of 230°C.
1. Cooling, separation, drying
(1) Cooling: The high-temperature compressed air output by the air compressor is fully in contact with the steel body when it passes through the spiral pipeline between the steel body and the outer cylinder, and the steel body absorbs heat and dissipates it.
(2) Separation: The cooled compressed air rotates at high speed in the spiral channel, and using the principle of centrifugal force, the oil, water droplets, powder and other impurities in the airflow can be used on the channel wall to be separated.
(3) Drying: Molecular sieve desiccant adsorbs moisture in the high-pressure airflow to obtain dry air.
2. Automatic pressure regulation
The dryer is constantly filled and unloaded, and the check valve effectively prevents gas backflow, which can ensure that the air pressure is always maintained within a certain range, which provides a guarantee for the normal operation of the brake system.
3. Desiccant activation and regeneration and automatic sewage discharge
Desiccant activation and regeneration and automatic sewage discharge are realized during the process of unloading and exhausting.
When the dryer is unloaded, a backblow air flow is formed. The backblow air flow takes away the moisture adsorbed on the molecular sieve when passing through the desiccant, realizing the activation and regeneration of the desiccant, which greatly extends the service life of the desiccant, reduces the frequency of dryer replacement, and improves the drying efficiency of the dryer.
At the same time, the blowback air flow discharges the oil, powder and other impurities collected in the cavity into the atmosphere through the exhaust port to realize the function of automatic pollutant discharge. It can clean up the filtered dirt in time, prevent the internal air path blockage of the dryer, reduce the frequency of failure, and also avoid the trouble of manual decontamination, which has a positive effect on the working performance of the dryer and even the entire brake system.
4. Safety pressure protection
When the internal air path of the dryer is blocked, or when the pressure regulator fails, its internal air pressure will continue to rise. If the air pressure rises to the safety protection pressure, the internal air pressure acts on the exhaust valve to overcome the exhaust valve spring force, so that the exhaust valve can be opened, and the exhaust can be unloaded and exhausted, avoiding danger.
5. Automatic heating and exhaust sound reduction
The automatic heating device is composed of an electric heating rod, a temperature control switch, an electric plug, a connecting wire, etc. The heating device can automatically heat the dryer according to the ambient temperature to prevent the pressure regulator and exhaust valve from being frozen, and avoid the occurrence of working failure.
A muffler is installed outside the exhaust port to greatly reduce noise generated during unloading and exhausting.
3. The composition of the air dryer
The air dryer is mainly composed of several parts, such as the shell, drying drum, pressure regulator, exhaust valve, check valve and heater.
There are three working air outlets on the housing, one of which is an air inlet and the other two are air outlets.
The dryer cylinder is sealed and installed at the upper end of the shell, which contains a molecular sieve desiccant to complete the absorption of moisture and the filtration of impurities. The heater's internal heating rod can warm the dryer and prevent the internal moisture from freezing in extremely cold environments.
The check valve is installed in an air outlet to prevent the backflow of dry gas. The pressure regulator and exhaust valve cooperate to complete the process of automatic pressure regulation, unloading and exhaust.
4. Precautions for using air dryers
The performance of the air dryer is directly related to the performance and service life of the automobile air brake system, and the choice of air dryer is crucial to ensure the working stability and driving safety of the brake system.
When using the air dryer, the air compressor should be frequently inspected to prevent the dryer from failing due to excessive oil pollution.
The dryer of the air dryer has a built-in desiccant, which has a certain service life, and should be replaced in time according to the maintenance mileage given by the manufacturer, and it is advisable to replace it before winter.
▎Summary:
Air dryer is small in size, has many functions, is easy to replace, simple maintenance, good cooling, separation, drying effect, stable and reliable performance, low noise, long life, strong load capacity, is currently widely used in the air brake system in the automotive parts, but in the process of use must pay attention to timely replacement to ensure its good effect.
Focus on the research and development of automotive brake systems and pneumatic brake valves to promote the development of the auto parts industry!
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