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Maintenance method of dry air filter for small excavator

The air filter has a great influence on the performance and life of the engine. Doing a good job in the daily maintenance of the air filter can not only effectively prevent the abnormal wear of the engine, but also effectively extend the engine and the air filter. Service life. A brief introduction to the classification and structure of air filters, the cleaning frequency, cleaning methods, and correct replacement and installation methods of dry air filters for small excavators are explained, and possible maintenance misunderstandings and therefore are analyzed. And put forward the correct and effective maintenance methods. The air filter is an important part of the engine’s air intake system. It can separate the dust that enters the engine air to the greatest extent, so as to reduce the early wear of engine cylinders, pistons and piston rings. If the air filter does not function properly, it will cause the engine to have insufficient intake air, insufficient combustion, power drop, black smoke or even scrapping. This will not only affect the power and economy of the engine, but also affect it. Engine emissions cause environmental pollution. Therefore, proper maintenance of the air filter is of great significance to ensure the stable and reliable operation of the engine, and even the reliable operation of the whole machine.

1. Brief introduction of air filter

At present, air filters commonly used on diesel engines can be divided into dry type and wet type according to whether the air is oiled or not. Due to the limitations of its own use, wet air filters are currently used in agricultural machinery and small and medium-sized mining machinery, but have been gradually replaced by dry air filters in construction machinery such as small excavators, especially in China. , Most small excavator manufacturers mainly use rotating dust-collecting dry dual-core air filters. This article mainly introduces the common maintenance misunderstandings and correct maintenance methods of rotating dust-collecting dry dual-core air filters for small excavators (hereinafter referred to as dry air filters).

1) The composition of dry air filter

Dry air filter is mainly composed of 5 parts: shell, safety filter element (also called inner filter element), main filter element (also called outer filter element), end cover and dust exhaust valve. Dry-type air filters are widely used due to their advantages of easy installation, high filtration efficiency, large ash holding capacity, low environmental pollution and easy maintenance.

2) The working principle of the dry air filter

The first stage filter area of ​​the dry air filter is a pre-filter device (between the housing and the main filter element), which can cause the air entering the air filter to generate a swirl Flow, through centrifugal force, the heavier dust particles will be separated from the air intake and collected in the dust valve. The pre-filtering capacity of the high-performance dry air filter can reach more than 85%, and only about 15% of the dust is allowed to enter the second-stage filter area (main filter element). The filtration efficiency of the main filter element can be as high as normal under normal conditions. 99.9% or more. There is also a first-level safety filter element inside the main filter element. Under normal circumstances, the dry air filter filter dust is mainly completed by the pre-filter and the main filter element. The safety filter element does not work. Only when the main filter element is improperly maintained, sealed or damaged , The safety filter can protect the engine. Compared with the main filter element, the safety filter element has high permeability, low flow resistance and low filtration efficiency. It will not increase the overall filtration efficiency and only serves a protective effect. Therefore, it is not allowed to start the engine when there is only the safety filter element.

2. Common maintenance misunderstandings and correct maintenance methods for dry-type air filters. Daily maintenance of dry-type air filters has an important impact on the life, power and economy of the engine, but it often does not receive enough attention. This will not only affect the filtration efficiency and life of the air filter, but also allow dust to enter the engine, causing wear and tear on the internal parts of the engine. The common misunderstandings and correct maintenance methods in the daily maintenance of dry air filters are as follows.

1) When to clean the dry air filter.

In the maintenance process of the dry air filter, many users think that cleaning the air filter regularly can increase the service life of the filter element, but in fact it is the opposite-this is the majority Misunderstandings in maintenance of all users. Because the initial filtration efficiency of dry air filters is generally around 99.5%, during use, as more and more dust adhere to the filter paper, the filtration efficiency will continue to increase, eventually reaching more than 99.99%. If the dry air filter is cleaned too frequently, the filtering capacity of the filter element will not be fully utilized, which will not only increase the amount of dust entering the engine, but also increase the frequency of cleaning will increase the probability of filter element damage. Once the filter element is damaged and not discovered in time, it will aggravate the wear of the engine and reduce the life of the engine rapidly. Therefore, the dry air filter should be cleaned after waiting for the differential pressure alarm to alarm. This not only reduces the workload, but also better protects the engine and saves costs. In addition, according to calculation and experimental verification, the dust holding capacity of the main filter element will be reduced by 20% to 40% after each cleaning. That is, as the number of cleaning increases, the dust holding capacity of the main filter element of the dry air filter will gradually decrease. , When the main filter element has been cleaned up to 6 times, its dust holding capacity is basically lost. At this time, the new main filter element should be replaced immediately, otherwise it will increase the resistance of the intake system and affect the efficiency and fuel economy of the engine.

2) The way to clean the main filter element. Many users use the method of tapping when cleaning the main filter element of the dry air filter. Although this is simple and convenient, it is not only easy to cause damage to the main filter element, but also a large amount of dust will enter the inner side of the main filter element. Dust enters the engine. The correct cleaning method is:

(1) Remove the main filter element, use a soft brush to brush away the dust on the surface of the main filter element along the crease direction, and gently tap the end surface of the main filter element to make the dust fall off. When performing the above operations, use a clean cloth or rubber plug to block both ends of the main filter element to prevent splashed dust from falling into the inner surface of the main filter element. You can also use compressed air or an inflator (air pressure should not exceed 0.2 ~ 0.3 MPa to prevent damage to the filter paper) from the main filter element to blow air out to blow off the dust adhering to the outer surface of the main filter element. Do not use liquid to clean the main filter element. During the cleaning process, prevent the liquid from sticking to the main filter element, otherwise it will cause the filter element to block and increase the air intake resistance.

(2) Check whether the main filter element is damaged, the upper and lower end surfaces are not flat, and the rubber sealing ring is damaged or there is dust inside the main filter element. If there are such problems, the main filter element should be replaced immediately even if the replacement time is not reached.

(3) Use a strong light flashlight to check whether the safety filter element is damaged. Do not remove the safety filter element for inspection at this time. If the safety filter element is damaged, it should be replaced immediately.

3) Cleaning of the shell and the dust exhaust valve

The ash capacity of the dry air filter itself includes: the ash capacity of the main filter element, the ash capacity of the shell and the amount of dust discharged through the dust valve. If the housing of the air filter is not cleaned when the filter element is cleaned or the dust valve cannot discharge dust normally, the overall dust holding capacity of the dry air filter will be greatly reduced. If only the main filter element is cleaned, and the air filter housing is not cleaned or the dust exhaust valve does not discharge dust, it will have a great impact on the service life of this series of air filters. When cleaning the air filter housing, carefully clean the inner wall of the air filter housing with a clean cloth, and carefully check whether the dust exhaust valve can discharge dust normally. If the dust valve cannot discharge dust normally, there are mainly two possibilities: First, in rainy days or an environment with extremely high air humidity, the dust separated by the air filter is damp and sticks into blocks and gathers at the port of the dust valve, causing the dust It cannot be eliminated smoothly; second, the dust exhaust valve is not vertically downward when the end cover of the air filter is installed, which causes the separated dust to be unable to be eliminated. Therefore, when cleaning the shell and the main filter element of the air cleaner, the shell and the dust exhaust valve must be cleaned to ensure smooth dust exhaust; when installing the air filter end cover, ensure that the dust exhaust valve faces downwards or deflects left and right. No more than 15°, to ensure that the separated dust can be removed normally.

4) Cleaning of the safety filter

When many users clean the main filter, it is a wrong practice to clean the safety filter together without any protection. Because as long as the main filter element can function normally, the surface of the safety filter element must be clean, so under normal circumstances, the safety filter element does not need to be cleaned. If dust is found on the safety filter element after the main filter element is removed, the most likely reason is that the main filter element is damaged, and the main filter element and the safety filter element should be replaced immediately. When cleaning the dust on the side wall of the air filter, try to avoid dust falling on the safety filter element. In case dust falls on the safety filter element during this process, the safety filter element can be removed and cleaned in a short time. Be sure not to pat, and clean up in accordance with the cleaning method of the main filter element. In addition, it should also be noted that the cleaning of the safety filter element must be done after the air filter housing and end cover are cleaned, and when cleaning the safety filter element, the end cover must be installed first to prevent the dust in the air from directly entering The engine causes the internal parts of the engine to wear; especially in a dusty environment, it is best to prepare a new safety filter for backup, and install the new backup safety filter first when cleaning the safety filter.

5) Inspection of the dust exhaust valve.

Many people think that the damage or fall of the dust exhaust valve will not affect the filtration efficiency and life of the dry air filter. Some people even think that the fall of the dust exhaust valve is beneficial to the smooth discharge of dust. This is a mistake. Understanding. Because when the dry air filter is working normally, due to the resistance of the air intake system, the internal pressure of the dry air filter is lower than the atmospheric pressure, and the dust exhaust valve is closed at this time. However, if the dust exhaust valve is damaged or falls off, or cannot be closed normally during operation, it will cause the unpre-filtered air to enter the dry air filter directly from the dust exhaust valve. According to the working principle of the dry air filter, when air enters the air filter, about 85% of the dust will be discharged through the dust valve. If the dust exhaust valve is damaged or falls off, not only the filtered dust cannot be discharged, but the unprefiltered air will directly enter the air filter. This will greatly reduce the dust holding capacity of the air filter, thereby reducing the life of the air filter and causing a certain economic loss. Therefore, the dust valve should be replaced immediately when the dust valve is damaged or falls off.

3. Through the above analysis, it can be seen that the maintenance of the dry air filter for small excavators has a great impact on its filtration efficiency and life, as well as the efficiency and life of the engine and the whole machine. Correct and reasonable maintenance of the dry air filter has certain practical significance for effectively improving the air intake environment of the small excavator engine and prolonging the service life of the air filter, the engine and the whole machine.

 

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