Liquefied petroleum gas Gasoline dual fuel vehicle - Modification and Technical Analysis

Main features of LPG vehicles

The main components of LPG are propane and butane. At normal temperature and pressure, it exists in gaseous form. However, it can become a liquid that is easy to store and transport when properly pressurized or under certain temperature conditions. When burning LPG in a car, LPG can be decompressed and directly supplied to the engine in gaseous form. Compared with gasoline, the use of LPG as a fuel in a car has the following advantages (1) Excellent emission performance. LPG has good volatility and can be fully mixed with air, so that the combustion is more complete, more uniform, and more stable. The harmful components such as Co, HC, and No in the exhaust gas are greatly reduced. There is no black smoke and carbon deposits. Compared with gasoline vehicles, the CO in the exhaust of LPC vehicles is reduced by about 90%, HC by about 70%, N by nearly 30%, and noise by nearly 40%. There is no dust pollution such as benzene and lead. According to the modification test of FAW on the Jetta sedan, the emission performance can meet the 83S351SEEC standard currently implemented by the European Community (2) Long service life of the parts. LPC fuel does not contain PB and contains very low S Almost no HS and other compounds are produced. During the combustion process, no tar or carbon deposits are produced. It is in a gaseous state. It will not dilute the lubricant. No corrosive substances will be produced on the cylinder wall. The lubricant replacement cycle is about 3 times that of gasoline vehicles. LPG runs smoothly, has low noise, and is durable. The service life is 3 times that of gasoline vehicles. (3) The engine has high thermal efficiency. The octane number of LPG is as high as 100,111S, which is 10% and 20% higher than that of high-quality gasoline. Therefore, it has good anti-knock performance. It can be used in engines with high compression ratios. This has obvious advantages in improving the thermal efficiency of the engine. The same amount of heat released, the consumption of LPC fuel, is about 90% of gasoline. In addition, the LPG car engine runs smoothly and has better low-speed performance than gasoline cars. It is especially suitable for use in large cities with crowded vehicles and dense populations. (4) The use of LPG is safer and more reliable. The LPG system is equipped with a safety protection device. It is not easy to leak. The density of LPG is 0.54. Even if there is a slight leak, the content in the air is difficult to reach 1.8%~9.6% in a very short time. The explosion limit of the LPG is 460°C, which is much higher than the ignition point of gasoline (210~300°C). The flame propagation speed is low and the induction period is long. Even if it is hit by an accident, it will not easily explode and burn. Therefore, the safety issues that people are worried about are guaranteed. (5) Good fuel economy. It is easy to modify the engine. A car can use dual fuels. That is, on the basis of the existing car, a set of LPG devices is installed to form a dual-fuel car. When the car is running in the wild, gasoline can be used. If it enters the city, LPG can be used through the conversion switch. It is very convenient. The price of LPG is lower than gasoline. The fuel cost savings for different models vary. Take Liuzhou Wuling van as an example. It travels an average of 300km a day. Calculated at 1L of fuel consumption per 100km, at least 20L of gasoline is consumed. LPG car modification. At present, the cars in use are still fuel cars. The gas stations have not yet formed a network in the city. Therefore, it is necessary to convert fuel cars into oil and gas dual-fuel cars.

LPG car modification

The cars in use are still fuel cars. Gas stations have not yet formed a network in cities. Therefore, fuel cars need to be modified into oil and gas dual-fuel cars. The main components of LPG car modification (1) LPG gas cylinder. LPG gas cylinder is installed in the trunk of the car. It is specially used to store liquid LPG. The cylinder is equipped with valves and instruments. The valves include filling valve, limit valve, outlet valve, overflow valve and safety valve. When the cylinder is filled to the specified liquid level (generally not more than 85%), the limit valve is closed to prevent it from being filled. If there is an accident such as pipeline rupture and LPG leaks in large quantities, the overflow valve is immediately closed to control the accident to the minimum state. If the pressure in the cylinder exceeds the specified value, the safety valve will start to release the pressure. The bottle is also equipped with a float-type liquid level gauge. It is connected to the dashboard in the cab so that the driver can observe the liquid storage volume at any time. The above valves and instruments are installed in the sealed protection box on the outer wall of the cylinder. When the safety valve exhausts or the valve leaks, The gas is discharged from the vehicle through a dedicated pipeline connected to the outside of the vehicle. The dual fuel gas supply system (2) LPG carburetor (evaporator), liquid LPG enters the carburetor. When the engine starts, its own sensible heat vaporizes. As the radiator hot water circulates through the carburetor, the liquid LPG absorbs heat and vaporizes. Then the pressure regulator is reduced to normal pressure through one or two pressure regulation and sent to the mixer (3) Mixer, gaseous LPG and air are evenly mixed in the mixer to form a combustible gas to supply the engine for combustion (4) Solenoid valves for LPG and gasoline. The engine fuel supply system is equipped with solenoid valves for LPG and gasoline respectively. The driver can change the fuel supply system of the car at any time by controlling the fuel conversion switch in the cab.

Technical solutions for the development of LPG vehicles at home and abroad LPG vehicles have a long history in the world. At the beginning of this century, the United States had developed technologies and products for automobiles to burn liquefied petroleum gas and natural gas. In the early 1960s, Japan's research on the device for burning gas fuel in automobiles (LPG device) had begun to bear fruit. In the 1910s, automobile fuel technology had become a mature technology in developed Western countries. In the 1980s, it had been promoted and applied to varying degrees in Japan, the United States, the former Soviet Union, Southeast Asia and South America. The technology of using gas in gasoline engines can be roughly summarized into three development processes according to the level of its technological development The first generation of LPG device system This system is an open-loop system, suitable for the configuration of carburetors, that is, on the basis of the existing gasoline engine, a gas supply system is added (the system composition is described above). Through the converter, you can choose to burn gasoline or LPG, but basically do not modify the engine itself. This technology is simple to modify and low-cost. At present, my country's modification of the dual-fuel supply system of in-use vehicles mainly adopts this technology. Burning LPG has many advantages, but it also has some disadvantages. For example, when burning LPG, the engine power performance is nearly 10% lower than when using gasoline. 3%, 10%; and it cannot guarantee that the car will obtain the best air-fuel ratio under all operating conditions: the effect of reducing emission pollution varies with different engines and different adjustment conditions. According to the bench test emission test results of the NJG427 engine under working conditions, compared with the normal level of the original car, the better matching can generally reduce CO by 40%, 60%, HC by 30%, 50%, and NO by less, generally not exceeding 15%. The emission level of cars equipped with this kind of simple system cannot meet the European regulations. Therefore, it can be said that the main significance of the first generation of technology is a way to solve the problem of alternative energy, and it also has a certain effect on improving automobile emissions. Second generation LPG device system This system is a closed-loop system with automatic feedback control, suitable for cars with carburetors, three-way catalytic converters and electronic air injection, referred to as a dual-purpose fuel system with electronic air injection and three-way catalytic converter. The principle of this system is based on the oxygen sensor ( The information provided by the sensor is used to control the amount of gas supplied to the engine through the microprocessor to achieve the purpose of controlling the air-fuel ratio, so that the car's power is optimized. The power can be increased by 2% and 5% under full load. This solution can make the car's emission level meet the requirements of European Regulation No. 1. This solution can also be used to transform carburetor gasoline engines. It requires the installation of an automatic air replenishment (fresh air) device at the lower intake pipe of the carburetor, which is also provided by the sensor and controlled by the microprocessor. Therefore, when gasoline is burned, the air-fuel ratio can also be controlled within the range suitable for the operation of the three-way catalytic converter, and the requirements of European Regulation No. 1 can also be met. This solution can also be implemented on electronically injected gasoline engines, that is, the sensors, microcomputers and three-way catalytic converters are shared with the electronically injected gasoline fuel system. It is reported that when Europe began to implement Regulation No. 1, this technology was also an effective method adopted by carburetor-type cars for a period of time. If this solution can make the emissions of the existing major sedan models in my country meet the new standards, the cost is relatively reasonable, and it will be meaningful for promotion and application. Third-generation single fuel gas technology This technology is CNG (natural gas) or LPG According to the experience of Ford, TNO Road Vehicle Research Institute of the Netherlands, Toyota of Japan, etc., the emission of single-fuel natural gas engine with closed-loop electronic multi-point injection and three-way catalytic converter is cleaner and can meet the ultra-low emission standards of California, but the cost is very high and it is not suitable for promotion and application in my country at present.