Engine connecting rod

The piston and the crankshaft are connected, and the force exerted by the piston is transmitted to the crankshaft, and the reciprocating motion of the piston is converted into the rotational motion of the crankshaft.

The connecting rod set is composed of a connecting rod body, a connecting rod big head cover, a connecting rod small head bushing, a connecting rod big head bearing bush and a connecting rod bolt (or a screw). The connecting rod group is subjected to the force of the gas from the piston pin and its own oscillation and the reciprocating inertial force of the piston group. The magnitude and direction of these forces are periodically changed. Therefore, the connecting rod is subjected to an alternating load such as compression and stretching. The connecting rod must have sufficient fatigue strength and structural rigidity. Insufficient fatigue strength often causes the link body or connecting rod bolt to break, which leads to a major accident of the whole machine. If the rigidity is insufficient, the bending deformation of the rod body and the rounding deformation of the big rod of the connecting rod may occur, resulting in eccentric wear of the piston, the cylinder, the bearing and the crank pin.

Structure and composition

The connecting rod body is composed of three parts, the part connected with the piston pin is called the connecting rod small head; the part connected with the crankshaft is called the big end of the connecting rod, and the connecting rod with the small head and the big head is called the connecting rod shaft.

The small end of the connecting rod is mostly a thin-walled circular ring structure. In order to reduce the wear between the connecting rod and the piston pin, a thin-walled bronze bushing is pressed into the small-head hole. Drill or mill the small head and bushing to allow splashed oil to enter the mating surface of the lubrication bushing and the piston pin.

The connecting rod shaft is a long rod member, and the force is also large during work. To prevent bending deformation, the shaft body must have sufficient rigidity. For this reason, the connecting rod shaft of the vehicle engine mostly adopts an I-shaped section, and the I-shaped section can minimize the mass in the case of sufficient rigidity and strength, and the high-strength engine has an H-shaped section. Some engines use a small rod injection motor to cool the piston, and the through hole must be drilled longitudinally in the shaft. In order to avoid stress concentration, the connecting rod shaft and the small head and the big head joints adopt a large arc smooth transition.

In order to reduce the vibration of the engine, the quality difference of each cylinder connecting rod must be limited to the minimum range. When assembling the engine in the factory, the mass of the connecting rod is generally grouped according to the mass of the connecting rod, and the same engine is selected. Group link.

On the V-type engine, the corresponding cylinders in the left and right columns share a crank pin, and the connecting rod has three types: parallel link, fork link and main and auxiliary link.

The engine parts brand that we have as following:

Cummins, Perkins, Mitsubishi, Caterpillar,VOLVO, Komatsu,Isuzu, Yanmar,Hitachi, DEUTZ, Yuchai, Shangchai, Weichai and so on.