Study on the performance of the hottest electronic

Research on the performance of electronically controlled injection ethanol motorcycle engine

Abstract: the relationship between excess air coefficient and ignition advance angle and emission performance of electronically controlled injection 125ml gasoline engine and ethanol engine is experimentally studied in this paper. The reasonable value range of these sensitive parameters affecting the emission of ethanol engine is pointed out, which can be used as a reference for the parameter matching of ethanol engine. The fact that engine burning ethanol fuel can reduce NOx emission concentration is verified, and a method to solve cold start is proposed

key words: ethanol engine gasoline engine emission performance electronic control injection

environmental protection is an important issue of common concern in the world today. Harmful emissions from engines are one of the main sources of atmospheric pollution. Especially in developed countries and areas with developed transportation, this kind of harm is more prominent

burning clean fuel is an effective method to reduce engine emissions [1][2]. Among them, burning alcohol fuel instead of gasoline engine is one of the effective measures, especially for reducing NOx. The electronically controlled injection system can accurately control the parameters of air-fuel ratio and ignition advance angle, and effectively improve the power, economy and emission performance of the engine [3][4]. According to the actual needs, this paper makes a comprehensive study on the emission and performance of electronically controlled injection ethanol engine, which provides a theoretical basis for the parameter matching of ethanol engine

1 test methods and instruments

the engine used for the test is a 125ml four stroke single cylinder air-cooled intake port injection gasoline engine. When burning ethanol, take out the gasoline and add ethanol to use it (the ethanol used is 99.8% industrial ethanol). See Table 1 for technical parameters of gasoline engine. See Table 2 for the main test instruments used in the test. The fuel injection quantity, ignition advance angle and injection advance angle in the test are completed by using the self-developed measurement and control system and the computer input control signal

the measurement and control system can be divided into two parts: Measurement and control. The measuring part measures the engine speed, crankshaft angle, cylinder temperature, throttle opening, fuel injection pulse width and ignition advance angle through the measuring circuit. These signals are used as the basis for judging the engine state and controlling the engine. The control part sends the measured fuel injection pulse width, ignition advance angle and other signals to the lower computer through appropriate amplification, reduction, advance or delay, and sends them to the fuel injector and ignition coil through the control circuit, so as to control the engine [5]

2 test results and analysis

2.1 HC emissions

Figure 1 shows the volume fraction of HC emissions when ethanol engine and gasoline engine have the best ignition advance angle under different loads Φ H C with excess air coefficient Φ Change curve of a (e represents ethanol, G represents gasoline, and the following figures are the same). As can be seen from Figure 1, when Φ When a=0.9 ~ 1.3, the change of HC emission of ethanol engine is smaller than that of gasoline engine, and the change is small. This is because the mixture ratio of fuel and air is appropriate, and the flame propagation is relatively stable, which can make the mixture burn more completely, so the HC emission is low. When Φ At a1.3, the HC emission of the two engines increases rapidly (gasoline engine is faster than ethanol engine), which is caused by too lean mixture, unstable combustion and increased misfire rate

Figure 1 Relationship between HC emission and excess air coefficient Figure 2 Relationship between HC emission and ignition advance angle

Figure 2 is the volume fraction of HC emission of ethanol engine and gasoline engine Φ HC with ignition advance angle θ Change curve of. It can be seen from Figure 2 that with the reduction of ignition advance angle, HC emissions of engines with different fuels and excess air coefficients are reduced. This is because delaying ignition delays the combustion, the exhaust temperature rises, and the incompletely burned fuel continues to undergo oxidation reaction in the exhaust pipe, reducing the HC emission concentration. When it is less than the optimal ignition advance angle (at 7000r/min, the optimal ignition advance angle of gasoline engine is 34 ℃ a, and the optimal ignition advance angle of ethanol engine is about 38 ℃), the HC of gasoline engine decreases faster than that of ethanol engine

from the analysis and comparison, it can be seen that ethanol engine has a wider range of stable and low HC emission air-fuel ratio than gasoline engine. Starting from Reducing HC emissions, it is easier to match the air-fuel ratio and control when burning ethanol Φ The range of a should be 0.85 ~ 1.3; gasoline engine Φ A the range should be 0.95 ~ 1.3. However, considering only the lowest HC emission, there is no advantage between burning ethanol and burning gasoline. Reducing the ignition advance angle can reduce the HC emission of the engine

2.2 CO emissions

Figure 3 shows the volume fraction of CO emissions from two fuel engines φ C o and excess air coefficient Φ Change curve of A. It can be seen that the concentration of CO is high in rich mixture, and the CO emission concentration of both engines increases linearly with the increase of mixture concentration, which is mainly caused by incomplete combustion due to hypoxia. The test shows that the concentration of CO has nothing to do with the load of the engine, and has little to do with the fuel, only with Φ A significant relationship. Just control Φ a> 1. Both ethanol engine and gasoline engine will obtain low CO emission characteristics

Figure 3 Relationship between CO emission and excess air coefficient Figure 4 Relationship between CO emission and ignition advance angle

Figure 4 is the volume fraction of CO emission under different mixture concentrations of two fuel engines φ CO with ignition advance angle θ Change curve of. It can be seen that no matter what the mixture concentration is or what kind of fuel is burned, the emission concentration of CO changes little. It shows that the ignition advance angle has little effect on the emission concentration of Co

therefore, the mixture concentration is the key factor affecting the CO concentration, as long as the control Φ If a is greater than 1, engines with both fuels will obtain excellent CO emission performance

2.3 NOx emissions

Figure 5 shows the NOx emission volume fraction of ethanol engine and gasoline engine at the best ignition advance angle under different loads φ NOx and excess air coefficient Φ Change curve of A. It can be seen that when the concentration of the mixture Φ A when it is near 1.05, the NOx emission of gasoline engine is high, and the NOx emission concentration above 30% load exceeds 2.5 ×， And the NOx emission concentration is higher than that of ethanol engine at full load

Figure 5 Relationship between NOx emission and excess air coefficient Figure 6 Relationship between NOx emission and ignition advance angle

ethanol engine should be switched on again with an interval of 10-20 minutes (depending on the ambient temperature). The peak of NOx emission concentration appears in Φ A is between 0.95 and 1.05, and the maximum peak value of emission is less than 2.7 ×， Moreover, with the reduction of load, the peak value of emissions decreases rapidly and shifts to the direction of rich mixture. The NOx peak value of ethanol engine at 50% load is higher than that of gasoline engine at 30% load Φ A = 0.85 rich mixture or Φ The NOx emission when a = 1.15 lean mixture is even lower, and it is 1/3 of the peak value of 30% load of gasoline engine. It can be seen that the advantage of low NOx emission of ethanol engine is very obvious

Figure 6 shows the volume fraction of NOx emission under different mixture concentrations of two fuel engines φ NOx with ignition advance angle θ Change curve of. It can be seen from the figure that no matter whether the mixture of the two fuels is rich or lean, reducing the ignition advance angle will reduce NOx emissions. The reason is that the ignition advance angle decreases, which reduces the maximum combustion temperature in the cylinder, thereby reducing NOx emissions

from the perspective of NOx emission control, gasoline engines should make Φ A is not in the range of 0.9 ~ 1.15, but for ethanol engines, this range can be reduced to 0.95 ~ 1.05 new GX RTF clearjet syringe

2.4 dynamic performance

Figure 7 shows the full load torque change rate of ethanol engine and gasoline engine Φ Ttq with excess air coefficient Φ Change curve of A. It can be seen from the figure that the maximum torque of the gasoline engine appears in Φ A=0.85; The maximum torque of ethanol engine appears at Φ A=0.95. along with Φ With the increase of a, the torque of gasoline engine decreases faster than that of ethanol engine. This shows that under the condition of ensuring the same torque reduction rate, the ethanol engine can burn thinner mixture than the gasoline engine, that is, under the same air-fuel ratio fluctuation rate, the torque fluctuation of the ethanol engine is smaller than that of the gasoline engine, and the operation is more stable

Figure 7 torque change rate and air volume coefficient φ Figure 8 relationship between torque change rate and relative ignition advance angle of a

figure 8 shows the full load torque change rate of ethanol engine and gasoline engine Φ Ttq varies with ignition advance angle θ Change curve of. It can be seen from the figure that the torque of the two engines varies with the ignition advance angle, but the gasoline engine θ More sensitive. In order to maintain the power of the engine, the ignition advance angle should not deviate too far from the optimal ignition advance angle

bench test shows that the acceleration and deceleration performance of ethanol engine is basically the same as that of gasoline engine, and the acceleration and deceleration emission performance needs to be further studied on the vehicle drum test bench; The cold start performance is inferior to that of gasoline engine, which needs further research and optimization. Cold start technology is one of the key technologies of the practical technology of ethanol engine. At present, when we cold start the ethanol engine, we use the self-developed starting heating device arranged in front of the nozzle to heat for 15 seconds before starting, and its starting performance basically meets the requirements of the laboratory; In addition, the anti ethanol corrosion and lubrication of nozzles and oil pumps are also a major problem in the practical technology of ethanol engines. In the research, the lubrication problem can be solved by adding a certain amount of diesel oil into ethanol, and the service life of nozzles can be appropriately extended

3 conclusion

(1) excess air coefficient φ A is a sensitive parameter that affects the emission performance of ethanol engine and gasoline engine φ The reasonable control of a can realize the control of harmful emissions, and the excess air coefficient of ethanol engine φ A it should be controlled between 1 and 1.2. The left end (1 to 1.1) should optimize the power performance, and the right end (1.1 to 1.2) should improve the emission

(2) fire advance angle θ It has obvious influence on HC and NOx emission performance of ethanol engine and gasoline engine, but has little influence on CO emission

(3) air coefficient φ A and ignition advance angle θ It is a sensitive parameter that affects the torque of two kinds of engines, and these two parameters should be reasonably controlled

(4) under year-on-year conditions, the NOx emission of ethanol engine is significantly lower than that of gasoline engine