Knowledge explanation of crankshaft
The crankshaft is the most important part of the engine. It receives the force from the connecting rod and converts it into torque that is output through the crankshaft and drives other accessories on the engine to work. Today I will tell you about the crankshaft, and I hope it will be helpful for everyone to understand the crankshaft.
The crankshaft is subject to the combined effects of centrifugal force of the rotating mass, gas inertia force with periodic changes, and reciprocating inertia force, so that the crankshaft is subject to bending and torsional loads. Therefore, the crankshaft is required to have sufficient strength and rigidity, and the journal surface needs to be wear-resistant, uniform in work and good in balance. Generally speaking, the engine speed is the speed of the crankshaft.
The function of the crankshaft balance weight is to balance the rotating centrifugal force and its moment, and sometimes it can also balance the reciprocating inertia force and its moment. When these forces and moments themselves reach equilibrium, the counterweight can also be used to reduce the load on the main bearing. The number, size, and placement of counterweights should be considered based on factors such as the number of cylinders in the engine, the arrangement of the cylinders, and the shape of the crankshaft. The counterweight is generally integrated with the crankshaft by casting or forging. The high-power diesel engine counterweight is manufactured separately from the crankshaft and then bolted together.
The crankshaft will wear the contact surface between the connecting rod head and the journal due to the unclean oil and the uneven stress on the journal. If there are large particles of hard impurities in the oil, there is also the risk of scratching the journal surface. If the wear is severe, it is likely to affect the stroke length of the piston's up and down movement, reduce the combustion efficiency, and naturally reduce the power output. In addition, the crankshaft may also cause burns on the surface of the journal due to insufficient lubrication or too thin oil, which in severe cases will affect the reciprocating movement of the piston. Therefore, it is necessary to use a suitable viscosity lubricant, and to ensure the cleanliness of the engine oil.
Crankshaft classification
Classified according to the type of engine fuel. It can be divided into gasoline engine crankshaft and diesel engine crankshaft.
Classified according to the material of the crankshaft itself. Can be divided into nodular cast iron crankshaft, cast steel crankshaft, alloy steel crankshaft.
Classified according to the structure of the crankshaft. It can be divided into integral crankshaft and combined crankshaft.
Classified according to crankshaft crank mechanical support structure. Can be divided into two points to support the crankshaft, full support crankshaft.
Classified according to the bearing type at both ends of the crankshaft. It can be divided into rolling bearing main journal crankshaft and sliding bearing main journal crankshaft.
The above is an introduction to the knowledge of crankshafts. I hope that everyone will be helpful after understanding the crankshafts knowledge.