Euro emission matching method for the hottest 50ml

2022-09-27
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Euro II emission matching method for 50ml two-stroke motorcycles

for the motorcycle industry, solving Euro II emission of 50ml two-stroke motorcycles is a technical problem. Hangzhou Saite locomotive Technical Service Co., Ltd. has accumulated certain experience after more than 4 years of exploration. According to the requirements of Euro II, the emission limits of 50ml motorcycle are: CO (1.0g/km), THC and NOx common value of 1.2g/km. During the test, the values of CO and thc are often high, while NOx is generally in an inconspicuous state. Extensometer is the measurement of small deformation of materials. In view of the above difficulties, the reasons are briefly analyzed below

first, according to the fuel transmission process of 50ml two-stroke motorcycle. The fuel passes through the carburetor to the crankcase, enters the scavenging passage, then transfers to the cylinder, and finally reaches the combustion chamber. Compared with four stroke, its transmission process is longer. Moreover, there is oil in the mixture. Part of the oil stays in the crankcase and the piston for lubrication, and part of it burns. The combustion products have been discharged from the combustion chamber when the air is insufficient and the fuel is not completely burned. On the other hand, the engine structure itself is also a defect, which has large cooling area and low temperature. There is a big gap in the cylinder wall itself, which causes the fuel to not burn completely, resulting in the high thc value

secondly, in the design of air filter, sponge with high density is basically used for filtration, and the thickness is about 14mm, which leads to the obstruction of the normal circulation of air. Manufacturers often do not pay attention to this problem, and the co value will be high. However, NOx is generally lower than the Euro II value because the engine has a wide cooling surface, the high temperature lasts for a short time, and the carburetor is in a rich state

the following is the emission matching method of a 50ml two-stroke motorcycle in a factory for the reference of technicians

the original state of the sample vehicle is as follows:

engine displacement: 50ml (two-stroke), vehicle speed 53km/h (Euro II limit 45km/h), carburetor oil needle in the middle grid, air filter sponge thickness 14mm. The exhaust pipe is not equipped with a catalyst, no air replenishment device, and the high nickel 3 yuan is unstoppable. The model of engine oil and gasoline is unknown. When stopping, oil dripping occurs at the bottom of the carburetor (indicating that the oil level is high). The emission test values are: THC (3.131g/km), NOx (0.044g/km), CO2 (0.837g/km)

from the above situation, the original sample car is very unsatisfactory, which is manifested in the high speed and excessive emission value. We have made adjustments and improvements in the following aspects in view of the status of the car

a) adjust the carburetor: lower the oil level (i.e. float). Then observe the position of the oil needle, and it is best to adjust the float to the 2nd or 1st grid (counting from top to bottom)

b) air filter: use a 5mm thick sponge filter as long as it can prevent dust from entering

c) add air replenishment device: add air replenishment valve at the carburetor joint, and the air replenishment valve shall be adjustable, such as "blue sky" air replenishment valve. Install secondary air replenishment at the front end of the exhaust pipe to dilute the concentration of the mixture on the one hand, and conduct secondary full combustion on the other hand

d) adding catalyst: adding catalyst in muffler with specification of 48 × 50mm catalyst section, mainly for the conversion ratio of Co

e) choice of engine oil: choose good engine oil products, such as Mobil, uni president, etc. To control the oil progress, it is best to adjust the oil pump to 50:1

through the above methods, the high-speed emission values reach the following results: THC (0.325g/km) is due to the wide range of involvement, NOx (0.221g/km), CO (0.083g/km). The vehicle speed is 44km/h. when parking, there is no oil dripping at the bottom of the carburetor. This method is mainly to debug the carburetor before it can be put into use, the air replenishing device and the air filter. Professional technology is required in the debugging process, so as to ensure that it meets the requirements of Euro II and the performance of the vehicle. (end)

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