Failure of Cylinder Liner and Its Causes

The technical condition of the cylinder has a great influence on the engine dynamics, economy and reliability. Cylinder inner working surface wear, cylinder outer surface cavitation, cylinder liner shoulder fracture is a common fault of tractor engine, which is analyzed and preventive measures are proposed.

Causes of Cylinder Liner Cavitation

Vibration is the main cause of cylinder liner cavitation. When the cylinder liner local strong vibration, part of the vibration energy through the solid-liquid phase interface, in the form of pressure waves spread to the outside of the cylinder liner cooling water, prompting the cooling water bubbles. Specific reasons are.

1. The clearance between the cylinder liner and the piston skirt, the clearance between the lower mounting band and the seat hole is relatively large, the larger the clearance the more likely to produce cavitation.
2. The water jacket is too narrow (on the camshaft side, the minimum clearance of the water jacket is only 1.55 mm).

Solution for Cylinder Liner Cavitation                                                                                                               

1. Reduce the gap between the piston and the cylinder liner can reduce the strength of the liner vibration, thereby reducing the cavitation of one of the effective measures.
2. can be used to increase the water barrier ring to reduce the vibration of the cylinder liner work, strengthen the seal; or use the flat shovel to expand the gap between the water jacket; or the cylinder liner will be transposed to use; or improve the cooling water circuit.

Fracture of Cylinder Liner Cam Shoulder

 Reason

1. The cylinder liner processing process failed to strictly implement the processing technology, resulting in the cylinder liner size is over poor, causing the supporting shoulder fracture.
2. When the body stop plane is unclean, there are debris; or the body support shoulder hole cleaning is not complete, the cylinder set is not at the bottom; or forced compression; pressure installation cylinder sleeve is not used special tools, unreasonable knocking, etc.
3. Poor quality of cylinder gasket or cylinder head bolt tightening force and different cylinder head types lead to improper tightening order, resulting in the cylinder head compression force can not meet the requirements (too loose or too tight).

Measures to Prevent Convex Shoulder Rupture

In order to reduce the thermal load at the first ring groove of the piston in the 1100 diesel engine, the thickness of the shoulder was reduced from 10 mm to 8 mm in the 195 diesel engine. To ensure the strength of the shoulder, special consideration has been made from the structural design, such as increasing the bearing width of the shoulder, so that the shoulder has enough bearing area and reducing the specific pressure of the shoulder. In the head of the cylinder liner, a 1 mm high, 110 mm diameter tab is designed, which not only blocks the direct impact of high temperature gas on the cylinder gasket, but also effectively improves the strength of the shoulder of the cylinder liner. For the key part of the lower edge of the shoulder, the necessary measures were taken to reduce the stress concentration in this part. These measures have solved the problem of fracture of the shoulder better.

2. The height of the cylinder liner projecting out of the plane of the body should not be too high or too low, generally should be controlled at 0. 04 ~ 0. 15 mm, and the amount of projection should be uniform; sharing the same cylinder head of multi-cylinder machine, the amount of projection of each cylinder liner should be basically the same. Cylinder head bolts (mother) torque should be required in the order of uniform torque, should not be too large. Cylinder liner material, casting, processing quality must be strictly controlled by the standard, and annealed according to the provisions, eliminate internal stress.
3. cylinder liner installation hole to clean. After a long time engine work, will make the cylinder liner installation hole up and down the convex shoulder formed very hard deposits and its dirt, repair assembly before to eliminate clean.