Analysis of the reasons for the unsatisfactory eff

2022-08-21
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Analysis on the reasons for the unsatisfactory effect of cylinder head rectification for many times

in view of the above-mentioned fault problem of "water seepage due to the connection between cylinder head and engine body", we have carried out rectification for many times, and the main improvement methods are:

(1) since May 2008, we have adopted a cylinder set machine with three water seals

(2) since January 2010, the improved cylinder gasket and cylinder head have been installed; The development prospect of aviation aluminum materials is considerable

(3) since January and February 2010, the situation has improved after tightening the cylinder head bolts with the angle method, but it has not been completely solved. We have repeatedly explored the causes of its occurrence

1.1 cylinder liner projection height

the cylinder liner projection height of this series is required to be 0.02 ~ 0.08 mm, which is the lower limit of the theoretical value of 0.05 ~ 0.15 mm, and the preload is relatively small. In practice, the actual cylinder liner projection height measured is less than 0.05 mm. Under the action of preload, it is possible that the cylinder gasket is not pressed tightly enough, resulting in poor sealing between the cylinder head and the engine body, resulting in cylinder gasket punching or damage. When the diesel engine is working, the high-temperature and high-pressure fuel gas in the cylinder is connected with the waterway, causing "bubbles after confirming that the equipment has been connected with the power supply line" in the auxiliary water tank. When the accelerator is suddenly increased and the accelerator is suddenly retracted, the phenomenon of "water reverse" will appear, and at the same time, the fault of "water seepage due to the connection between the cylinder head and the engine body" will also be caused

1.2 support and seal and cylinder liner positioning

the cylinder liner positioning and support of this series of models have problems of unreasonable structure and poor sealing, resulting in unreasonable and poor sealing of the cooling water flowing up to the cylinder gasket, resulting in water seepage from the cooling water flowing up to the cylinder gasket

after investigation, the main parameters of six cylinder diesel engines of the same type from Yuchai, Weichai, Cummins and Xichai manufacturers

1.2.1 analysis of support and sealing

(1) after comparison, it is found that Yuchai is higher than Weichai in terms of maximum displacement, power, speed and torque, but the cylinder diameter is smaller than Weichai, and the stroke is longer than Weichai, indicating that Yuchai mainly realizes these indicators by increasing the stroke

(2) after investigating the cylinder liner structure of the same type of six cylinder engine from Yuchai, Weichai, Cummins and Xichai manufacturers, it is found that this series of machine adopts wet cylinder liner, with a stroke of l45mm, and the cylinder liner adopts the upper support of the engine body. At present, more than 100million vehicles have been used for the cylinder liner. The check of flatness "generally requires that the length be controlled within 100 mm, and the unevenness should not exceed 0.04 mm"; The cylinder liner projection height is basically not detected with a dial indicator (the standard value is 0.05 ~ 0.12 mm), and some of the out of tolerance values are large, and the cylinder liner projection height does not meet the requirements

This technology is expected to enter the market in 2015

(2) after removing the cylinder head, it was found that there was water rust around the upper part of the cylinder liner and the upper stop of the engine body, and the cylinder liner was not removed in time to check whether the first waterproof ring was ablated or damaged and to find other reasons

(3) for the engine block, cylinder head, engine block cylinder bore, cylinder liner, screw bore (the screw bore is too deep to be cleaned or blown clean) and cylinder head bolts, the cleaning is not enough, and all cylinder head bolts are not replaced in time

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