Industry information
Since the reform and opening up, China's automobile industry has developed rapidly. As one of the key components of automobile, the steering system has also been developed accordingly, and has basically formed a situation of professional and serial production. According to the data, many foreign countries' steering gear factories have developed into professional factories with large-scale production, with an annual output of more than one million units, monopolizing the production of steering gear, and the sales points are all over the world.
Application trends of modern automobile steering gear
With the rapid development of automobile industry, the structure of steering device has also changed greatly. There are many structures of automobile steering gear. From the general degree of use, there are four main types of steering gear: worm Shaw type (WP type), worm roller type (WR type), circulating ball type (BS type) and rack and pinion type (RP type). These four types of steering gear have been widely used in automobiles.
It is understood that around the world, the automobile recirculating ball steering gear accounts for about 45%, the rack and pinion steering gear accounts for about 40%, the worm roller steering gear accounts for about 10%, and other types of steering gear account for 5%. Recirculating ball steering gear has been developing steadily. Rack and pinion steering gear has been greatly developed in passenger cars in Western Europe. The characteristic of Japanese automobile steering gear is that the proportion of recirculating ball steering gear is increasing. Various types of vehicles equipped with different types of engines in Japan adopt different types of steering gear. The recirculating ball steering gear used in buses has developed from 62.5% in the 1960s to 100% today (worm roller steering gear has been eliminated in buses). Most large and small trucks use recirculating ball steering gear, but rack and pinion steering gear has also developed. The circulating ball steering gear for minivans accounts for 65% and rack and pinion steering gear for 35%.
Based on the above analysis on the use of relevant steering gear varieties, the following conclusions are drawn:
·Recirculating ball steering gear and rack and pinion steering gear have become the two main steering gears in the world; Worm gear #0; Worm steering gear and worm Shaw steering gear are being phased out or retained in a small position.
·There are different views on the development of steering gear on passenger cars. The United States and Japan focus on the development of recirculating ball steering gear, and the ratio has reached or exceeded 90%; Western Europe focuses on the development of rack and pinion steering gear, with a ratio of more than 50%, and France has reached 95%.
·Due to the advantages of rack and pinion steering gear, its application in small vehicles (including passenger cars, small trucks or passenger and freight vehicles) has developed by leaps and bounds; The main structure of large vehicles is the recirculating ball steering gear.
Features of recirculating ball steering gear
·The circulating ball steering gear is characterized by high efficiency, light operation and a smooth control force characteristic curve.
·Convenient layout. It is especially suitable for large and medium-sized vehicles and power steering system; Easy to transmit driver control signal; High reverse efficiency, good return, and good coordination with the action of hydraulic power assisted device.
·It can realize the characteristics of speed ratio and meet the requirements of portability. The steering force in the middle position is small and often used, which requires sensitive steering. Therefore, it is hoped that the speed ratio near the middle position is small to improve sensitivity. The large angle steering position has large steering resistance, but it is used less times. Therefore, it is hoped that the speed ratio at the large angle position will be larger to reduce the steering force. Because the recirculating ball steering gear can realize the speed ratio, it is being used more and more widely.
·The steering force is transmitted through the rolling contact of a large number of steel balls, which has greater strength and better wear resistance. And the steering gear can be designed with equal strength structure, which is one of the reasons why it is widely used.
·The transmission ratio structure has high stiffness, which is especially suitable for increasing the speed of high-speed vehicles. High speed vehicles need good steering stability at high speed, and the steering gear must be guaranteed to have high stiffness.
·The clearance is adjustable. It is also one of the advantages of this kind of steering gear that the clearance can be readjusted after the rack tooth fan pair is worn to make it have appropriate transmission clearance of the steering gear, so as to improve the service life of the steering gear.
In the production of steering gear in China, except for the worm roller steering gear for Jiefang brand automobile and the worm Shaw steering gear for Dongfeng Automobile, most other models adopt circular ball structure and have certain production experience. Jiefang and Dongfeng are also actively developing circulating ball steering gear, and circulating ball steering gear has been widely used in the second generation vehicles. It can be seen that China's steering gear is also developing towards mass production of circulating ball steering gear.
Specialization of steering gear production
The recirculating ball steering gear has achieved professional production abroad. At the same time, it has been mainly carried out by professional factories, and vigorously carried out tests and research, which has greatly improved the output and quality of products. In Japan, the circulating ball steering gear of "Seiko" (NSK) company has gradually occupied the Japanese market with low cost, good quality and large output, and sold its products to the world. German ZF company is also famous as a large professional steering gear factory. It began to produce ZF steering gear in 1948, with an annual output of more than 2 million steering gears. There are also some relatively large steering gear manufacturers, such as the Saginaw branch of Delphi company in the United States; British Burman companies are well-known professional manufacturers with large production and sales. Specialized production has become a trend. Only by taking this road can we make products with high quality, large output, low cost and competitive in the market.
Power steering is the development direction
The application of power steering system is becoming more and more extensive. It must be equipped not only in heavy vehicles, but also in high-class cars. It is also gradually popularized in medium-sized vehicles. Mainly from reducing driver fatigue and improving handling portability and stability; The main purpose is to reduce the accidents caused by the sudden tire burst of the front wheel during high-speed driving. Although it brings problems such as high cost and complex structure, it has developed rapidly due to its obvious advantages.
There are three forms of power steering: integral, semi split and combined valve power steering structure. The three forms have their own characteristics and develop rapidly. The integral type is mostly used for front axle load 3 ~ 8t vehicles, and the combined valve type is mostly used for front axle load 5#0; 18t vehicle, semi split type, mostly used for super heavy vehicles with front axle load of more than 6T.
From the development trend, the development of integrated steering gear abroad is rapid, and the transfer valve structure of integrated steering gear is the development direction.