The crankshaft bearing structure, cooperate with and support

A, the crankshaft bearing function and use requirement of crankshaft bearing including connecting rod bearing and main bearing. Their function is to protect the shaft and bearing hole, reduce the friction and wear. The piston connecting rod set of gas from the physical to foreign output torque. Also used to drive the engine steam distribution agencies and other auxiliary devices. Use requirement: they all carry alternating load and high speed friction, therefore must have sufficient bearing material fatigue resistance, and smaller friction, wear resistance and corrosion resistance. Second, the main bearing of crankshaft bearing structure of the connecting rod bearing and are composed of upper and lower two pieces of axle bush involution. Each bearing shell are made by steel back and anti-friction alloy layer and steel back, anti-friction alloy layer and flexible coating composition, the former is called the second bearing shell structure, which is known as the three layers of structure bearing shell. 1, steel back and anti-friction layer steel back is the substrate bearing shell, made from 1 to 3 mm mild steel. Anti-friction layer is 0. 3 to 0. 7 mm anti-friction alloy layer and soft can protect the journal. ( Anti-friction material] ( 1) The white metal ( Babbitt) : antifriction performance is good, but the low mechanical strength, and heat resistance is poor. They can be used for small gasoline engine load. ( 2) Copper lead: high mechanical strength, large carrying capacity, good heat resistance. More used in high load of diesel engine. But the anti-friction performance is poor. ( 3) Aluminum alloy, with low antimony aluminium magnesium alloy, tin alloy and plastic aluminum alloy 3 kinds. Before two kinds of good mechanical performance, load capacity is strong, but the anti-friction performance is poor. Mainly used for diesel engine; After a mechanical performance and antifriction performance are better, widely used in diesel and gasoline engine. 2, positioning convex key and the groove on the connecting rod bearing shell has a positioning convex, for installation embedded into the positioning groove of big end and connecting rod cover, to prevent the bearing bush back and forth motion or rotation. Also on bearing system have oil hole and the groove, install aligned with the corresponding oil hole. Three, and cooperate with the free play of crankshaft bearing potential interference 1, free play potential bearing shell under free state in curvature radius is slightly greater than the pore radius, the diameter difference is called free play potential or open quantity. Gasoline engine is commonly 0. 8 to 1. 5 mm, diesel engine is 1. 5 ~ 2. 5mm。 2, cooperate with interference because of bearing outside diameter circumference relatively larger hole circumference, connecting rod bolts, will produce certain interference fit. Ensure bearings do not turn, do not move at work, and make the bearing work closely with a hole for heat dissipation. Bearing higher quantity generally is 0. 04 ~ 0. 09mm。 Inspection: the bearing load bearing hole, according to the bolt tightening torque of the original provisions of tight on both sides of the, then loosen the fastening bolts on one side of the completely, with a feeler gauge to check the bearing bearing hole interval subdivision surface, and higher than that of the clearance of bearing. Four, the role of crankshaft crankshaft thrust bearing thrust bearing, the car, because the trample clutch and impose axial thrust on the crankshaft, result in axial channeling move of the crankshaft. Excessive axial channeling move, will affect the normal work of the piston connecting rod set and damage the right valve timing and the fuel injection timing of diesel engine. Axial positioning, in order to ensure the crankshaft to furnish thrust bearings. Thrust bearing can only be set up in a place, to ensure that the crankshaft is heated expands can free elongation. Mainly include: flange bearings, half circle thrust sheet and circular thrust piece of 3 kinds of forms. 1, flanging bearing 2, a half circle thrust 3, circular thrust the installation note: side thrust sheet has the anti-friction layer ( Have a groove side) Toward the rotating parts, when the crankshaft darted forward, after the thrust piece bear axial thrust; Back up to move, the former thrust under axial thrust. Axial clearance adjustment: the replacement of different thickness of the thrust piece, or change the thickness of the thrust piece. ( As a standard to 0. 7 ~ 0. 17 mm, allowing the limit of 0. 25毫米) 。 Five, the way of crankshaft bearing is set between the adjacent two crank a crankshaft main journal, known as the full support of the crankshaft, otherwise known as the full support of the crankshaft. 1, the full support of the crankshaft: advantage: improve the stiffness of the crankshaft and the bending strength, reduce the load of main bearing. Faults: crankshaft machining surface increased, main bearing number increase, make the body length. As much broader, diesel engine using this kind of bearing. 2, the full support of the crankshaft: advantage: to shorten the length of the crank shaft, make the engine overall length decreased. Weakness: the main bearing load is bigger. Application: load bearing small gasoline engine can use this way.