1 The function of the air filter
The air filter is one of the most important supporting products for construction machinery engines. It protects the engine, filters out hard dust particles in the air, provides clean air to the engine, prevents dust from causing engine wear, and affects the reliability and durability of the engine. Play a key role.
Therefore, the selection and use of air filters for construction machinery engines must pay attention to the following aspects:
1.The structure and capacity of the air filter must meet the performance and working conditions of the engine.
2.The quality of the air filter must meet the national inspection standards.
3.The pipes and interfaces connected to the air filter must be tightly sealed, must not leak air, and must be reliable and durable.
4.The inlet of the intake pipe of the air filter should be located in a place with the least dust, no rain or snow, low temperature, no hot air and exhaust gas, and corresponding measures should be taken.
5.The air filter must be maintained regularly and the filter element must be replaced.
6.For use in dusty environments and areas, an air filter with an increased capacity must be selected, and the replacement cycle of the filter element should be shortened accordingly.
If the above points are not paid attention to, it will cause serious damage to the construction machinery engine: for example, it will cause the early wear of the engine cylinder, and then the engine will blow-by the oil, the power will drop, and the engine will enter the overhaul ahead of time.
2 The basic parameters and selection principles of air filter products
The most basic technical parameter of an air filter is the air flow of the air filter, referred to as “flow”, in cubic meters per hour (m/h), which represents the maximum air flow allowed to pass through the air filter. Generally, the larger the allowable flow rate of the air filter, the larger the overall size and the filter area of the filter element, and the larger the corresponding dust-holding capacity.
The basic principle of selecting an air filter is: the rated air flow of the air filter must be greater than the air flow of the engine at the rated speed and rated power, that is, the maximum air intake of the engine. At the same time, if the installation space permits, it is necessary to appropriately use a large-capacity and large-flow air filter, which helps to reduce the resistance of the air filter, increase the dust storage capacity and extend the maintenance cycle.
The maximum air intake of the engine at rated speed and rated load is related to the following factors:
1. Engine displacement
2. Rated engine speed
3. The aspiration form of the engine. Due to the function of the supercharger, the intake air volume of the supercharged engine is much larger than that of the naturally aspirated engine
4. The rated power of the supercharged model. The higher the degree of supercharging or the use of supercharged and intercooled type, the greater the rated power of the engine, and the relatively larger intake air volume.
3 The basic structure and maintenance of the air filter
Take the above air filter as an example, its basic structure is shown in the figure:
1. Swirl vane (blade ring)
The air rotates after passing through the swirl plate, and more than 80% of the dust is separated under the action of centrifugal force, and the dust is deposited in the dust accumulation disc, so that the finer dust reaching the filter paper is about 20% of the suction volume.
2. Dust tray
The dust tray is the dust tray that collects the coarser dust thrown out by the swirling vanes.
3. Dust bag
The dust in the dust tray can be automatically collected and discharged into the dust bag under the vibration of the vehicle, and sometimes the user can open the bag mouth regularly for complete removal.
4. Safety filter
In order to prevent accidents of the main filter element, sometimes it may be damaged or ash leakage, so a safety filter element is added to protect the engine from damage.
5. Rain cap
Prevent dust, foreign objects, rain or snow from directly entering the intake pipe.
6. Clogging indicator
When the air filter needs maintenance and the air intake resistance reaches the set value, the indicator light will light up and a maintenance signal will be issued to remind the driver that the air filter should be maintained or replaced immediately.
4 The maintenance and precautions of the air filter during use:
1. The filter element of the air cleaner must be cleaned and inspected regularly. When cleaning the air filter element, first gently tap the end face of the filter element on the flat plate, and blow back from the inside of the filter element with compressed air for maintenance. It is strictly forbidden to clean with oil or water.
2. If a filter element clogging alarm is installed, when the indicator light is on, the filter element must be cleaned in time.
3. Replace the filter element of the air filter in strict accordance with the provisions of the maintenance manual.
4. Clean the dust bag frequently, and don’t accumulate too much dust in the dust pan.
5. If you are in a dusty area, the cycle of cleaning and replacing the filter element should be shortened according to the situation.
6. After maintenance of the filter element, attention should be paid to correct installation. Do not miss any parts. Do not knock the air filter housing flat, otherwise the filter element cannot be taken out for maintenance and replacement, and the dust bag should be vertically downward.
Post time: Sep-10-2021