Overview of Engine Bearing Design

     There are many bearing in the car engine, the most important of which is the rod bearing and 

crankshaft main bearing. After years of development, the engine with lubricated bearings in the 

structure has been basically stereotypes.Connecting rod small head is pressed into the bushing, 

connecting rod bulk bearing and shaft main bearing are generally devided into upper and lower 

half, the embedded a bearing. Bearing wall thickness is generally not more than 3mm, by the 

"steel back" cover friction alloy layer composition, also in the friction alloy layer plus soft 

alloy composed of three thinwalled bearing.

     At present, the domestic bearing alloy raw material manufacturing process is the use of 

centrifugal casting technology  of Babbitt alloy bushings, copper-based alloy bearing most of the 

centrifugal casting, some of manufactures use copper-lead alloy powder sintering process billet, 

and aluminum-based alloy bearing generally by the professional manufacturers supply bimetallic 

strip. A large number of foreign production of copper-based alloypad are used continuous casting 

method and continuous powder sintering method. The machanical processing of the bearing pad is 

carried out in the professional bearing factory, and towards the mechanization, automation, 

continuous production mode of development.

     Engine Sliding Bearing Design General Steps:

    (1) Combined with the overall design, to determine the bearing structure type and the main 

size.

    (2) Combined with the power calculation, determine the bearing load, draw the load map.

    (3) Check the bearing pressure and linear velocity, determine the bearing alloy material.

    (4) For hydrodynamic performance calculation, drawing the axis of the track and and oil film 

pressure distribution map, select the lubricating oil, determine the bearing clearance, 

lubricating oil inlet temperature, pressure and other relevant parametersof the reasonable value.

    (5) For the bearing, sleeve and other parts of the structural design, drawing work map.

     Bearing Design to Consider the main issues:

    (1) Select the appropriate bearing friction-reducing alloy material and surface coating, so that it has sufficient anti-fatigue strength, to resist the oil film pressure caused by the pulse load, to ensure that the innormal use without damage, abrasions and too fast wear.

    (2) Choose a reasonable bearing width ratio, oil tank, bearing clearance and inlet position, etc, to create a hydrodynamiclubrication.

    (3) Choose a reasonable degree of transparency and free play. To ensure that the bearing will not rotate in the hole and can come out of friction heat.

     (4) To ensure that the steel back of the thin-walled bearing has a high compression yield 

limit, the bearing in the circumferential direction of the uniformity of the bearing bolts layout

and design to maintain the joint surface in all conditions sufficient preload pressure.Although 

there are many empirical data, data and some theoretical calculations can be designed at the time 

of reference, but some factors are difficult to set, and some factors are not included in the 

theoretical analysis, so the evaluation of bearing design can only be engine test.

      (5) With three-layer bearing can significantly improve the anti-corrosion, anti-bite, 

vabration-resistant ability , and thus the highest fatigue strength. Surface coating appropriate 

selection, the initial overheating caused by the alloy surface flow, adhesion from the "ironing" 

role. The strain of the alloy layer has the effect of damping vibration.

      (6) Thin-walled bearing should be fully tightened, so that tile back in the bottom hole in 

order to improve the cooling effect and improve the stress distribution.

      (7) In the structural design to change the unsuitable oil tank, oil hole location and size.