What materials are commonly used for automotive engine crankshaft bearings?
wallpapers Products 2020-05-27
The automobile crankshaft bearing bush usually adopts the structure of steel back + friction-reducing alloy. The friction-reducing alloys are commonly used in three categories: babbitt alloy, copper-based alloy, and aluminum-based alloy.
Babbitt alloys are divided into tin-based and lead-based alloys. Babbitt alloys have low fatigue strength, lower allowable specific pressure and lower operating temperature, and are generally used in gasoline engines with a lower degree of strengthening;
Copper-based alloys are divided into lead bronze and copper-lead alloys;
Aluminum-based alloys are divided into two types, high-tin alloys, and low-tin alloys. Aluminum-based alloys are currently the most widely used in internal combustion engine crankshaft bearings.
Bearings are widely used in automobiles and bear important responsibilities. From the engine and chassis to the electrical assembly, bearings are used. Automotive bearings are divided into two categories: sliding bearings and rolling bearings. Sliding bearings are mainly used on engines. Sliding bearings are usually divided into two types, one is a bush-type thin-walled bearing, which is commonly known as a bush like a tile; the other is a bushing, also known as a copper bush, which is a hollow cylindrical body. Liner-type thin-walled bearings are mainly used to support engine crankshafts and connecting rods. The bushing is mainly used to support the camshaft journal and the piston pin, but it is also used in other places in the automobile, such as the knuckle kingpin bushing of the chassis, the shock-absorbing steel plate pin bushing, the gear bushing, and the motor bushing—the role of antifriction intermediates. The crankshaft and connecting rod bearings seem to be a single tile structure, but their performance requirements are high. Although the lubricating oil of the lubricating system separates the machine parts from the contact surface of the bearing, in recent years, as the engine continues to develop at high speed and boost pressure, the oil film pressure of the bearing increases, the oil film thickness decreases, and the working environment of the bearing deteriorates. And the connecting rod bearing materials and manufacturing requirements are getting higher and higher. Generally, the bearing adopts a double-layer metal form, and some is a multi-layer form. The first layer is a steel tile back to ensure mechanical strength, and the second layer is a bearing alloy to ensure surface working performance. A material called Babbitt is commonly used; The third layer is based on the above two layers and then plated with a very thin alloy to further improve the surface performance.