The overall technology of automobiles is changing with each passing day, and the progress of engine technology, which is the heart of automobiles, has attracted more attention. Now when introducing a car engine: variable valve timing technology, dual overhead camshaft technology, in-cylinder direct injection technology, VCM cylinder management technology, turbocharging technology, etc. have been widely used; in use Materials are also developing in the direction of lightweighting: all-aluminum engines are currently widely used; pollution from automobiles is also inevitable, so new energy technologies include high-voltage rails of diesel engines, fuel cells, hybrid power, and pure electric power. Biofuel technology has also become popular, but looking back at the history of engines may better understand the tremendous changes that have occurred in automotive technology over the past 100 years. The rapid development of automobile technology can also be seen from my country's automobile textbooks: the development of new technologies has made it difficult for automobile textbooks to keep up! Today, most automotive textbooks still use Dongfeng Motor's engines as examples, and Dongfeng engines are still old-fashioned engines with carburetors, which are simply centuries apart from today's fully electronic engines. The exploratory stage before the gasoline engine goes back to the beginning of the automobile. At that time, the automobile was ridiculed by horse-drawn carriages and caused serious pollution, but the significance of the start was extraordinary. In the mid-18th century, Watt invented the steam engine. After that, people began to imagine installing the steam engine into a car to carry people. N.J. Cugnot of France was the first person to install a steam engine on a car. In 1770, Guynew built a three-wheeled steam locomotive. This car is 7.23 meters long and has a speed of 3.5 kilometers per hour. It is the world's first steam locomotive. In 1771, Cournot improved the steam car, which could reach a speed of 9.5 kilometers per hour and tow 4-5 tons of cargo. In 1858, Reno, who settled in Paris, France, invented the gas engine and applied for a patent in 1860. The engine replaces the steam of the reciprocating steam engine with a mixture of gas and air, uses batteries and induction coils to generate electric sparks, and uses the electric sparks to ignite the mixture and explode. This kind of engine has cylinders, pistons, connecting rods, flywheels, etc. The gas engine is the primary product of the internal combustion engine because the compression ratio of the gas engine is zero. In 1867, the German Nicolaus August Otto was inspired by the gas engine developed in Reno. He conducted a lot of research on gas engines and produced a horizontal pneumatic gas engine. It was later improved and held in France in 1878. His samples were exhibited at international exhibitions. Due to its high efficiency, the engine attracted great interest from visitors. During the long-term research process, Otto proposed the four-stroke theory of the internal combustion engine, which laid the theoretical foundation for the invention of the internal combustion engine. Germans Aumler and Karl Benz each developed a modern gasoline engine based on the principles of Otto's engine, paving the way for the development of automobiles. Mercedes-Benz No. 1 is equipped with a single-cylinder two-stroke gasoline engine
1886 is regarded as the birth date of the automobile, and that Mercedes-Benz has always been talked about. But its power unit was really "shabby": the first "three-wheeled Mercedes-Benz" was equipped with a horizontal single-cylinder two-stroke gasoline engine with a top speed of 16KM per hour. This was the engine of the first car. At that time, the brave wife of Carl Benz drove this Mercedes-Benz No. 1 uphill and needed her son to push the cart. Of course, it kept stalling along the way and the steering was not working properly. She had to walk 100 kilometers back to her parents' home. All day long. Application of four-stroke engines The four-stroke engine has actually been developed by the German Otto. But Daimler has to be mentioned in the applied cars. He became the first person to install a four-stroke engine in a car because he assisted Otto in developing a four-stroke engine. Obviously, going from a four-stroke to a two-stroke is a huge improvement. The balance and combustion efficiency of the four-stroke engine are better. Today's automobile engine technology has basically all used four-stroke technology. After the basic operating mode of the engine was determined, someone challenged the tradition. Rotary engine
Mazda's dedicated rotary engine
In 1957, the German Wankel invented the rotary piston engine, which is an important branch of the development of gasoline engines.
The characteristic of the rotary engine is that it uses a mechanism that combines the inner rotor circle epitrochoidal line and the outer rotor circle inner cycloid line. It does not have a crankshaft connecting rod and a valve mechanism, and can directly convert the triangular piston motion into rotational motion. It has 40 fewer parts than reciprocating piston gasoline. It is light in weight, small in size, high in speed and high in power. In 1958, Wankel changed the outer rotor to a fixed rotor for planetary motion, creating a new rotary piston engine with a power of 22.79 kilowatts and a speed of 5500 rpm. This machine has important development value and has attracted the attention of various countries. Japan's Toyo Corporation (Mazda Corporation) bought the prototype of the rotary engine and installed the rotary engine in the car. It can be said that the rotary engine was born in Germany and grew up in Japan. Today, the rotary engine is still only used by Mazda. I don’t know when Mazda’s unique technology will fully blossom. After the working form of the engine is determined, the engine technology is perfected. As time goes by, many classic engine designs can no longer meet people's needs. The carburetor engine carburetor was first invented in 1892 by the American Durie. With the evolution of technology, the functions of carburetors have become more complete. Until the middle and late last century, carburetors were divided into five parts: main fuel supply system, starting system, idle system, large-load enrichment system (economizer) and Accelerate the system. The function of the five parts is to vaporize the gasoline according to the needs of the engine under different circumstances, mix it with air in a certain proportion to form a combustible mixture, and enter the cylinder in an appropriate amount in a timely manner.
The advantages of the "ancient" carburetor are: it can control the oil-gas ratio of the internal combustion engine at an ideal level, and it will always work unchanged regardless of weather and temperature. Moreover, the carburetor has low cost, high reliability, and is easy to repair and maintain. Of course, carburetors also have many weaknesses: for example, during cold starts, idling, rapid acceleration or low pressure environments, such a fixed oil supply method cannot actually fully meet the engine's operating needs, and may even produce black smoke. , incomplete combustion and insufficient horsepower. Therefore, since 2002, China has banned the sale of carburetor cars, and since then all models have switched to electronic injection engines. Of course, carburetor-type engines are currently running on the road. As time goes by, carburetor-type engines will completely withdraw from the stage of history. EFI engine EFI first appeared in 1967 with the D-type electronic injection device developed by the German Porsche Company, and was subsequently used in German cars such as Volkswagen. This device uses the pressure inside the intake pipe as a parameter, but compared with the carburetor, it still has the disadvantages of complex structure, high cost, and instability. In response to these shortcomings, Pausch has developed an L-type electronically controlled gasoline injection device. It uses the air flow in the intake pipe as a parameter and can directly determine the air intake volume based on the relationship between the intake air flow and the engine speed. According to This injects the corresponding gasoline. Due to its reasonable design and reliable operation, this device is widely used by automobile manufacturing companies in Europe and Japan, and laid the prototype of today's electronically controlled fuel injection device.
Electronic injection engines have been fully popularized so far. The driving computer of the EFI system will detect the engine temperature, intake air flow, speed changes, and vibration conditions at any time, and adjust the fuel supply and ignition according to actual needs. time, so it can achieve a pretty good balance in power output, fuel economy and emission performance. At the same time, in order to increase the engine air intake and improve fuel efficiency, the engine evolved from early single-point injection to multi-point injection, and the number of valves increased from two to five. The most advanced currently is the electronic injection engine equipped with VVT variable valve technology. Generally speaking, the biggest advantage of the electronic fuel injection system is that the fuel supply is very precisely controlled, allowing the engine to have a correct air-fuel ratio under any condition. Not only does the engine keep running smoothly, but its exhaust gas can also comply with environmental regulations. . However, the electronic fuel injection system is not the most scientific. Due to the inherent limitations of the internal combustion engine structure, the electronic injection nozzle is installed next to the valve, and the fuel and gas injection can only be completed when the valve is opened. Therefore, the injection will be affected by the opening and closing cycle, causing a delay, thus affecting the computer's control of the injection time. Fortunately, this problem has been solved by in-cylinder direct injection technology.
In the past two years, when European and American manufacturers realized that the research and development of electronic injection technology has entered a bottleneck period, in-cylinder direct injection technology has become the main focus of major manufacturers. At present, the in-cylinder direct injection engines that have attracted much attention on the market include: Audi FSI in-cylinder direct injection engine and Cadillac SIDI dual-mode direct injection engine. Compared with EFI engines, the fuel injector of in-cylinder direct injection engines is moved inside the cylinder. Therefore, the amount of oil and gas in the cylinder will not be affected by the opening and closing of the valve. Instead, the computer automatically determines the timing and amount of fuel injection. As for the valve, it only controls the entry time of the air, and the two are mixed only after entering the cylinder. Since the mixing space and time of oil and gas are quite short, the in-cylinder direct injection system must rely on high pressure to press the fuel from the injector into the cylinder to achieve a high degree of atomization, thereby better mixing the oil and gas. Among them, the higher the compression ratio of the mixed oil and gas engine, the more powerful its power performance, and the corresponding energy-saving effect is more obvious. The compression ratio of Audi's 3.2-liter FSI direct-injection engine reaches 10.3:1; the compression ratio of Cadillac's 3.6-liter SIDI dual-mode in-cylinder direct injection engine reaches 11.3:1. In addition, most of the combustion chambers and pistons of the in-cylinder direct injection system also have special guide grooves, so that the oil and gas can generate cyclonic vortices after entering the combustion chamber to improve the atomization effect and combustion efficiency of the mixed oil and gas. Generally speaking, the peak power of an engine using in-cylinder direct injection technology is 10 to 15 times higher than that of a multi-point injection engine of the same displacement, and the peak torque can be increased by 5 to 10 times. Such an improvement can be described as a qualitative change, and it is difficult to achieve this effect simply by increasing the number of valves. New engine technologies continue to emerge. After the engine's working mode and fuel injection method are determined, the evolution of the engine does not end. The previous generations of car people have made unremitting efforts to improve the engine technology. Some improvements cannot even be recorded. It is obvious that the engine now runs smoother and the vibration is not so intense. The fuel economy is also better and the horsepower is more. And these all rely on the use of new technologies. In order to improve the air intake, there are: Honda's ECVT, Toyota's VVT-I, Hyundai's CVVT, GM's DVVT and other variable valve timing technologies; in order to obtain a better air-fuel ratio, there is Volkswagen's TFSI stratified injection technology, VIS variable intake technology, turbocharged intercooling technology, etc.; in order to minimize environmental pollution, an oxygen sensor, a three-way catalytic converter, and waste recycling technology are added to the exhaust pipe. At present, due to the severe impact of environmental pollution, the requirements for automobile exhaust emissions are getting higher and higher. The elimination of old engine technology has become inevitable, and more technologies that fully utilize energy are also being developed continuously. At the same time, due to the huge impact of the global energy crisis, more energy-saving new energy technologies will surely play a major role in the development of engine technology. The car engine eventually dies. If we look at the encouragement direction of China's automobile policy, pure electric vehicles have become the focus of international policy support, and supporting facilities have begun operation in pilot cities. Cars without engines are changing our century-old automobile history. Outside of China, other important automobile manufacturers are also developing their own new energy technologies. They have also made many breakthroughs in the research and development of hydrogen power and pure electric vehicles. The development trend of automobiles in the 21st century is to let the roar of engines withdraw from the stage of history.