Tire valve is a self-contained valve which opens to admit air to inflate a tire, and is then automatically closed and kept sealed by the pressure in the tire, to prevent the air from escaping. Tire valve stems are made of aluminium, steel or black rubber. It includes tubeless tire valve and tube valves for passenger cars, truck, buses, tractor and ATV etc.
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The increasingly serious energy crisis has become the focus of attention of the internal combustion engine industry in the world, and diesel engines are increasingly favored by users. Compared with gasoline engines, diesel engines have many advantages: they can reduce CO2 emissions by 20% to 25%, and have better acceleration performance when the vehicle speed is low. The average fuel consumption is 25% to 30% lower, which can provide more driving pleasure. Therefore, some people have boldly predicted the development trend of diesel engines in global automobile production, and divided the proportion of diesel engines in the world's automobile production by region. However, diesel engine emissions control is a more difficult problem than gasoline engines. In order to meet the emission standards, the advanced fuel injection system of diesel engines, the high pressure common rail technology, has become the focus of attention in the industry. In previous years, high-pressure common rail technology was dominated by foreign capital, and this situation has now been broken.
Increased emission standards will inevitably promote the development of engine technology
On December 30, 2005, Beijing took the lead in implementing the National III emission standards. On July 31, 2006, new buses in the bus and taxi industries in Shanghai were implemented in the country III emission standards. On September 1, 2006, Guangzhou began to implement the National III emission standards. On July 1, this year, the country will fully implement the National III emission standards. By 2010, China will implement the national IV emission standards.
The improvement of emission standards will inevitably promote the development of engine technology. For gasoline engines, due to the relatively mature technology and post-processing, it is not difficult to meet current emission standards. For diesel engines, since most of them are still mechanical fuel systems and the development history of diesel direct injection technology is short, the engine must be redesigned to meet the emission standards. Most of China's current use of imported technology to meet the current emission standards (State III), but some companies are conducting independent research and development, such as China FAW Wuxi Oil Pump Institute, Chengdu Witt and so on. Under stricter emission standards, in addition to electronically controlled fuel systems, many new technologies have been introduced in the engine. Ricardo, a world-renowned automobile research and development company, recommends engine technical requirements for each stage of emission. It can be seen that the common rail system is one of the most inherited and sustainable fuel injection systems due to its unique advantages.
High pressure common rail system has been widely used abroad
Since the development of diesel fuel injection systems from mechanically controlled to electronically controlled systems, electronic injection systems have undergone three revolutions: positional fuel injection systems, time-based fuel injection systems and time-pressure fuel injection systems (common rail systems). The high-pressure common rail system realizes the separation of the pressure establishment and the injection process, so that the control process is more flexible, and the precise control of the small amount of oil can be more accurately achieved, and multiple injections can be realized better.
Since Nippon Denso launched the ECD-U2 high pressure common rail system paper in 1991, foreign fuel system manufacturers have invested huge amounts of money and manpower in developing common rail systems. Bosch released a high pressure common rail system for passenger cars in 1995. It uses a radial piston rotor type fuel supply pump. The fuel injector solenoid valve adopts a ball valve structure. At present, the common rail system of Bosch has been commonly used in passenger cars and light vehicle diesel engines in Europe, such as German Daimler-Benz C-series cars, Italian Alfa Remeo 156 sedans, and German Volkswagen Audi 3.3L V8 turbocharged diesel engines. , Duramax 6600 diesel engine jointly produced by U.S. General Motors and Japan Isuzu Corporation, and ISBe3.9L and 5.9L all-electrically controlled diesel engine by U.S. Cummins. Delphi and Siemens launched the sedan Multec DCR 1400 common rail system in 1998 and 2000, respectively, using a radial piston rotor type fuel supply pump. Delphi's injector solenoid valve is designed in the injector to make the injector more compact. Small; Siemens fuel injectors use piezo actuators with a shorter response time; and Denso Corporation's first ECD-U2 product was developed in 1991 and matched with Hino's J08C diesel engine and Isuzu's 6HK1 in 1995. Diesel engine, after years of improvement and improvement, the latest product has been used in car ECD-U2P system.
At present, the common rail fuel injection system is widely used. Bosch has produced 25 million common rail systems and invested in a technology center and factory in Wuxi, Jiangsu Province to achieve local production. Great Wall Motor and Bosch have developed high-pressure common-rail diesel engines, and brands such as Audi, Mercedes-Benz and Huatai have also introduced cars using common-rail systems. Some universities, research institutes, and companies in China have also achieved independent research and development through cooperation or independent research. They have obtained dozens of patents. Therefore, China has accumulated certain experience in electronically controlled direct injection diesel engines. However, there is still a gap with foreign countries, which is mainly reflected in the quality control of manufacturing processes and mass production. In addition, the related supporting system of domestic common rail system is not perfect, and some parts and components also rely on imports, such as single-chip chip, common rail pressure sensor and so on.
Competition between foreign companies and Chinese companies is no longer dominant
Compared with gasoline engines, the gap between China and foreign countries in electronically controlled diesel engines is relatively small. This is due to two reasons: First, most of the original diesel vehicles used in China have their own brands, and second, China's diesel engine use vehicles do not require high comfort, low prices, and foreign companies do not have an advantage over Chinese companies.
With the increase of emission standards, diesel engines must use electronically controlled injection systems. At present, domestic diesel electric control systems mainly include common rails, single pumps, etc. Compared with foreign advanced technologies, although they do not have equal strength, they have a good momentum of development. For example, the common rail system developed by the Wuxi Oil Pumps Institute has been used in buses in Wuxi, and at the same time there are a large number of companies engaged in the research and development of electronically controlled diesel engines in China. Therefore, the electronically controlled diesel engine market in the country will certainly make a difference. The prices of products provided by foreign companies are relatively high, and the supply price depends on the volume. Under the premise that the current batch of electronically controlled diesel engines in China is still not large, it is difficult for them to obtain relatively satisfactory prices.
At the same time, in the after-sales service and parts supply, the domestic independent brand system also has obvious advantages. The competitiveness of the domestically-developed electronically controlled fuel system is mainly reflected in the following aspects: First, the price is cheap, and the economic volume is small. Secondly, for the light truck products, matching the common rail technology with a small batch size, the PM type in-line pump + electronic governor + cooling EGR solution with high injection pressure can be selected, which is also our advantage. In addition, for medium- and heavy-duty vehicles, the technical route of common rail, single pump, etc. has been implemented in Phase III of the country.
Of course, there are still many challenges in the field of electronically controlled diesel engine systems in China, such as the immature manufacturing process and the small batch size; the fuel quality is difficult to guarantee; and the post-processing technology of diesel engines is not high. However, these will gradually resolve with time.
Background information:
Song Guomin, senior engineer. He graduated from Southeast University with a Ph.D. degree in precision engineering and mechanical engineering. He is currently the deputy director of the Basic Research Office of Wuxi Oil Pump & Grease Research Institute of China FAW Group Corporation. The main research direction is diesel engine electronic control system development. The research scope includes field bus, fault diagnosis, OSEK real-time operating system, etc. The main projects involved are “Electric Control Common Rail System Research and Its Application in Automotive Diesel Enginesâ€, “Common Rail System Development and Key Technology Research†and so on.