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Description of structure and working principle of oil saw cutting saw
Oil saw uses two stroke, single cylinder, forced air - cooled gasoline engine as the power, through the high - speed operation of oil saw chain to complete various saw cutting work.
Let's see how the oil saw can make the chain run at high speed.
The structure of oil saw
As a whole system, oil saw is divided into ignition system, oil supply system, inlet and exhaust system, lubricating system, cooling system, starting system, etc.
Cylinder is the core of the chain saw components, including the lining, heat sink, combustion chamber, etc., there are three holes on cylinder, the air inlet and vent and loophole, the three holes respectively by piston closed in a certain moment.
The complete sealing of cylinder is a necessary condition for the continuous operation and power generation of saw.
The cylinder is mounted on the crankcase.
The piston can reciprocate in the cylinder and close the cylinder from the lower part of the cylinder to form a sealing space.
The fuel burns in a sealed space, creating a force that pushes the piston.
The reciprocating motion of the piston is driven by the connecting rod to rotate the crankshaft, which then outputs the power from the flywheel end.
The crankshaft connecting rod mechanism is composed of piston group, connecting rod, crankshaft and flywheel.
The piston group consists of piston, piston ring, piston pin, etc.
The piston is cylindrical and has a piston ring on it to keep the cylinder closed while the piston is moving back and forth to prevent gas leakage in the cylinder.
The piston pin is in a cylindrical shape. It goes through the pin hole on the piston and the small end of the connecting rod to connect the piston and the connecting rod.
The connecting rod is divided into three parts: the head end, the small head end and the rod body. The head end is connected with the crank pin of the crankshaft, and the small head end is connected with the piston pin.
When the connecting rod is working, the small end reciprocates with the piston, the large end rotates around the crankshaft axis with the crank pin, and the shaft body moves in a complicated swing.
The crankshaft converts the reciprocating motion of the piston into rotary motion and transfers the work done by the expansion stroke through the flywheel mounted on the back end of the crankshaft.
The flywheel can store energy so that other piston strokes can work properly and the crankshaft can rotate evenly.
The inlet and exhaust system is usually composed of air filter, inlet pipe, exhaust pipe and muffler.
In order to supply fuel into the cylinder, the saw has an oil supply system.
The air and fuel are mixed by the carburetor installed at the inlet of the intake pipe at a certain concentration and then fed into the cylinder through the inlet pipe. The electric spark controlled by the oil saw ignition system is ignited regularly.
When the fuel in the oil saw cylinder burns, the piston, cylinder and other parts are heated and its temperature rises.
In order to ensure the normal operation of the saw, so that piston, cylinder and other parts will not be damaged due to overheating, it must have a cooling system.
The cooling system of the saw is composed of the flywheel blade and the wind channel formed by the starter cover, shell and other parts.
The saw cannot be transferred from the stopped state to the running state by itself. It must be turned by an external force to start the crankshaft.
The device that produces external forces is called a starter.
Ii. Working principle of oil saw
In order for the saw to work continuously, the piston must return to its original position after pushing the crankshaft so as to push the crankshaft again, which requires the piston to reciprocate in the cylinder.
The piston moves from one end of the cylinder to the other, called a stroke.
The working cycle of the saw consists of inlet, compression, combustion, expansion, exhaust and other processes.
The first stroke: the piston moves upward from the bottom stop point, and the inlet, exhaust and exchange pores on the cylinder are closed at the same time, and the mixture into the cylinder is compressed.
The piston continues to move upwards, further compressing the mixture, and the air inlet will emerge as the piston moves up, and the combustible mixture will flow under the piston into the crankcase.
Second stroke: when the piston is compressed near the upper stop, the spark plug will jump right into the fire and ignite the combustible mixture. The gas expansion will push the piston down for work.
As the piston moves down, the inlet hole is closed, and the combustible mixture sealed in the crankcase is compressed.
When the piston is close to the bottom stop, the vent opens and the exhaust gas bursts out due to strong pressure.
Then the air vent is opened, and the premixed combustible mixture is flushed into the cylinder through the air exchange channel to drive away the exhaust gas and carry out the air exchange process.
Exhaust process of chain saw and collectively called for air intake process, the role of ventilation is to put on a cycle from the clean, make the circulation into the fresh air, so that as many as possible fuel combustion inside the cylinder, to achieve greater power in chain saw.
The quality of the gas exchange process directly affects the service condition of the saw. We should reduce the flow resistance of the inlet and outlet systems, so we need to clean the carbon deposition in the channel and clean the air filter regularly.