Gas vehicles using LNG as fuel have seen explosive growth this year. Many card users have replaced their diesel vehicles with gas vehicles.
However, due to some characteristics of gas vehicles, many problems that are not easy to occur in diesel vehicles are more common in gas vehicles. My friend Xiaoqiang sent me a typical failure case of gas vehicles.
A gas tractor came for inspection and maintenance due to lack of power. The owner said that the fault was weak climbing, and the speed increase on the flat road was much slower than before. Through disassembly and inspection, it was found that the bypass valve at the exhaust turbine end of the supercharger was worn and leaked, resulting in insufficient speed of the supercharger and low boost pressure, and the power of the natural vehicle would deteriorate. This is basically a common problem of the gas engine.
Seeing here, some card friends will ask why the gas engine is prone to this problem. This will start from the characteristics of the gas engine. The gas engine uses natural gas as fuel, and the ignition point of natural gas is 650 degrees, which is much higher than that of diesel 220 degrees, which leads to the high working temperature and exhaust temperature of the gas engine.
On the other hand, in order to make the engine have better low-speed performance, the volute at the exhaust end of the turbocharger is relatively small to ensure the normal operation of the turbocharger at low speed. When the engine speed increases and the exhaust pressure increases, the bypass valve will open to avoid excessive intake pressure caused by supercharger overspeed.
Based on the above two factors, the speed of the gas engine is higher than that of the diesel engine, and the exhaust temperature is also higher. The high-temperature exhaust gas is easier to increase the exhaust pressure. At this time, the action of the bypass valve of the supercharger must be frequent, and even the throttle closing bypass valve will open. With high temperature and high pressure and frequent opening, the natural wear of the valve seat intensifies, and it is not surprising that air leakage occurs over a long time.
However, at present, there is no better prevention method for this fault. The only way to solve the problem is to replace the turbocharger volute or supercharger assembly. Therefore, we should pay more attention when using gas vehicles. If we find that there is insufficient power and check that there is no problem in other places, there may be a problem here.
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