After some engine repairs, about 300 to 500 hours, there is a phenomenon of burning and discharging oil. We have achieved good results through years of groping and improvement.

First, the main reason for the engine burning and discharging oil 

1. The cylinder sleeve and the piston ring wear early, so that the matching clearance between the cylinder liner and the piston and the opening gap of the piston ring increase, and the sealing effect is poor. 

2. The piston ring is of poor quality. Most of the piston rings currently put into the market are made into rectangular rings. This type of ring has poor oil scraping performance and is one of the important factors causing engine oil skimming. 

3. The piston ring mouth is close to or overlaps with the opening, especially if the oil ring overlaps the opposite port, causing the oil to slam and overflow. 

4. The operator does not pay attention to the maintenance of the air filter. We have done tests. When the dust content of the air entering the cylinder is 0.5g/m, the wear of the cylinder is increased by 0.15~0.40mm after 25~100h working. It can be seen that the quality of the air filter is one of the causes of the wear of the cylinder and the piston ring. In addition to modifying the air filter and strengthening the usual maintenance, we have studied and tested the structure and assembly method of the piston ring.

The improvement of the piston ring structure is to process the second and third gas rings and the oil ring by using a semi-circular cymbal, and uniaxially cutting the inner circumference of the second and third pistons into a 1 mm × 45 degree chamfer. It becomes a twisted ring with an inner chamfer and is kneaded by a 0.5 mm × 45 degree chamfer on the thin outer circumference of the cast iron oil ring. The chamfer in the air ring and the outer chamfer of the oil ring are upward when assembling. In the work, the two twisted rings can be twisted in a dish shape, so that the lower corner tension of the ring is greater than the upper corner and has the function of scraping oil upward.

the improvement of assembly methods

In the actual assembly, we did not evenly distribute 120 degrees according to the three air ring openings. The opening of the oil ring and the ring was not installed at 180 degrees, but the three air ring openings were installed at 180 degrees. That is, the adjacent piston ring openings must be installed 180 degrees apart. The piston ring opening installed in WeChat and Shenzhen is more effective than the piston ring opening installed at 120 degrees to avoid overlapping of the openings. 

In the structure with three gas rings, when the opening of the piston ring is installed at 180 degrees, the openings of the first gas ring and the third gas ring are in a straight line, but due to the sealing effect of the second gas ring, The airflow entering from the first air ring opening is directed to the third air ring opening. This is the advantage of the three-way air ring opening installed at 180 degrees. 

However, the work opening position must be perpendicular to the piston pin. In the same way, when installing the oil ring, this principle should also be followed, which can effectively avoid the oil on the cylinder wall, thus avoiding the engine burning and discharging oil. According to this principle, the test of multiple vehicles has a good effect. The engine has been working continuously for more than 2,000 hours, and there is no burning oil.