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  • Hand-held power tools operating safety technology
    2019-06-14 18:29:31

    The chain saw is powered by a gasoline engine and is mainly used for gardening tools for logging and timber production. The power part of the chain saw is a gasoline engine. The body of the chain saw engine is the main part of the power generation. It directly determines the function and service life of the chain saw. The body of the chain saw engine mainly has cylinders, pistons, connecting rods, crankcases, and Flywheel and other components. Let's take a look at these important chain saw accessories that make up the body of the chain saw engine.


    First, the cylinder


    The cylinder is a cylinder for the piston to move therein, and it is a place for the combustion of the mixture to burst. In order to increase the wear resistance of the inner wall of the cylinder and increase the heat dissipation of the cylinder, the oil saw cylinder is mostly made of aluminum alloy casting, and the inner wall is chrome-plated. The upper part of the cylinder is the main working place of the chain saw engine, so the upper part of the cylinder is worn more than the lower part. At the same time, the connecting rod swings left and right when moving in the cylinder, and the degree of wear on the left and right sides is large. After grinding to a certain extent, the cylinder of the chain saw engine should be replaced.


    Second, the piston


    The piston is subjected to the pressure of the working gas of the chain saw engine, reciprocates, and transmits the pressure to the crank mechanism through the connecting rod. At the same time, it is driven by the connecting rod and the crankshaft (by inertia force) to complete the intake, compression and exhaust work. The piston top of the piston engine is mostly arc-shaped, and the flow of the mixed gas is higher in the upper part of the piston, so the upper diameter is smaller than the lower diameter at the time of manufacture as the flow rate of expansion. In order to ensure the tight coupling between the piston and the cylinder wall surface, it is ensured that the compression is good. There are 2-4 piston rings in the ring groove on the piston, and the opening gap is 0.10-0.15 mm as the flow rate of expansion.


    Third, the connecting rod


    The connecting rod is used to connect the piston to the crankshaft of the engine, transmit the pressure of the gas received by the piston to the crankshaft, and change the reciprocating linear motion of the piston into the rotational motion of the crankshaft. The small end of the connecting rod is connected with the piston, and the big end is connected with the crankshaft.


    Fourth, the crankshaft


    The crankshaft changes the linear motion of the piston to a rotary motion by means of a cylinder, a piston and a connecting rod. At the same time, it can push the piston to make a reciprocating linear motion. In order to simplify the manufacture of the crankshaft, the crankshaft of the chain saw engine is composed of two half shafts, two crank arms and a crank pin. The half shaft end and the crank pin are pressed into the crank arm and finally joined into a crankshaft. The crankshaft is typically mounted in the crankcase by means of ball bearings.


    Five, flywheel


    The basic function of the flywheel is to maintain the balance of engine operation. In addition to this, the flywheel makes the engine easy to start. When the explosion stroke begins, the rotational energy of the crankshaft is stored. Before the piston reaches the maximum through the ignition, the top dead center, and the mixture compression, the flywheel releases the energy to continue the rotation of the crankshaft.


    Sixth, crankcase and flywheel housing


    The crankcase is the base of the engine on which the components and parts of the engine, such as cylinders, ignition devices, etc., are mounted. The crankcase of the two-stroke chain saw engine functions as a scavenging pump in addition to the rotating parts of the engine. In order to maintain a certain pressure in the body and avoid the mixed fuel or gas in the body, an oil seal is arranged between the crankshaft and the crankcase. The flywheel has a flywheel housing on the outside for protection. The outer side of the flywheel housing has a spiral conduit that is part of the chain saw engine cooling system. Therefore, the flywheel housing is also the outer casing of the blower.


    Chain saw engine


    Two problems in the burning process of the chain saw engine


    (1) After the engine is ignited, a deflagration phenomenon sometimes occurs, which is an abnormal combustion. When the engine is deflagrating, the flame burns at a very fast speed, which can reach 2000-3000 m/s, while the normal flame burning speed is 20-40 m/s. Therefore, the temperature of the engine is remarkably increased, and the pressure of the cylinder is also greatly increased. The characteristic of deflagration is that there is a metal knocking sound in the cylinder, the engine is unstable, overheating, and the power is lowered, and black smoke is emitted from the exhaust pipe. Due to the deflagration of the engine, its economy deteriorates, the lubricating oil deteriorates, and even its lubricating performance is lost, so that the wear of the bearing is increased. Therefore, the deflagration phenomenon is not allowed. The main cause of engine deflagration is due to poor fuel quality or improper combination of fuel grade and engine compression ratio. In addition, it is also related to the temperature of the engine itself, the position of the spark plug, the form of the combustion chamber, and the magnitude of the pre-ignition angle. Also, carbon deposits can cause deflagration. Immediately after the occurrence of deflagration, close the throttle (throttle), find out the cause, and eliminate it.


    (2) Pre-ignition: that is, the ignition is not equal, and the combustible mixture in the cylinder burns itself. The reason for the pre-ignition is that the temperature in the cylinder has reached the temperature at which the fuel spontaneously ignites during the compression process. Therefore, it does not need to be ignited to burn itself. When pre-ignition occurs, the engine overheats, producing a lot of charcoal, and the engine is not working properly. Ke Ruipu chain saw quality and price concessions, welcome to buy.


    By analyzing and understanding the two problems in the combustion process of the chain saw engine, we can better understand the performance of the chain saw. Only by knowing and mastering the performance of the machine can we improve work efficiency and quality, thus realizing the goal of saving labor and reducing costs.