Technical Comparison Analysis And Research On Passenger Car Braking Standards And Regulations

GB 12676-1999 Automotive braking system structure, performance and testing requirements, the current braking standard in force developed several years ago according to series 06 ECE R13, are not able to keep up with the developments of passenger car braking technologies. Especially some errors and unreasonable requirements in the standard had impacted its effectiveness. The National Automotive Standardization Technical Committee set out to develop a new compulsory standard for passenger car braking with the aim to adapt the standard to the latest development of passenger car products and technologies, regulate and improve the requirements for passenger car braking. This paper will be used as the technical reference for the drafting of this standard.This paper analyzes the importance and necessity of drafting a new standard for passenger car, gives a brief description of braking standards & regulations system in major countries and regions as well as the harmonization activities among them. Started with the differences of certification system, major technical characteristics of braking standards & regulations system in Europe and USA are compared and analyzed, and some suggestions for new National Standard for passenger cars are proposed based on the administrative system and standards & regulations system in China combined with the international harmonization trend.For the purpose of comparison and analysis, several key braking theories are described briefly. Begun with braking dynamics, this paper researches the relations between slip and adhesion coefficient, discusses working behaviors of locked wheels during braking and analyzes braking procedure and factors which may affect braking performances.With ECE R13-H as the baseline and GB 12676 and FMVSS 135 as important references, major technical differences among the above three standards are compared and analyzed, especially with regard to performance and testing requirements, evaluations methods and testing items. As regards testing conditions and requirements, this paper describes the external conditions for tests such as wind speed, environmental temperature, road conditions, etc, analyzes key vehicle conditions such as vehicle load, tyres and brake temperature etc affecting braking performances. Based on the above, major evaluating parameters and controlled testing conditions are proposed finally.With regard to testing items, major differences of regular braking tests, including o-type test, I-type test and parking braking test etc, specified in ECE R13-H and GB 12676-1999 are listed and compared with each other. Combined with the technical status of Chinese passenger cars products, this paper researchs and analyzes what problems could occur when requirements of ECE R13-H are applied. As one of the key issues, performances and testing requirements in the failure of service braking system are also researched. This paper summarizes and analyzes definition of service braking failure as well as the performance and structure requirements when a failure occurs in the service braking system, discusses structure requirements of different braking system in the event of energy failure. For each category of braking system, failure conditions are analyzed and theirs simulation scenarios are proposed. Specifications of braking distribution, consisting of performance requirements, checking method and performance in failure,etc, specified in GB 12676, ECE R13-H and FMVSS 135 are analyzed. This paper also gives a brief description of principle and major testing requirements of ABS adopted by ECE R13-H and GB 12676(including GB/T 13594-2003) and discusses the design theory and problems of ABS testing method used in Europe.In addition, some points on vehicle type approval are discussed and principles for selection of Representative vehicle and Extension of type approval are proposed.For the purpose of verification, two different vehicles were selected for tests to verify the technical requirements of all applicable items and analyze the major differences of ECE R13-H and GB 12676-1999 and their influences on the conformity of the standard. Although technical requirements of ECE R13-H and GB 12676-1999 would not have an critical impact on the conformity according to the verification test, proper modifications are necessary to be made adapt to the technical characteristics and testing conditions of Chinese vehicles.In summary, this paper proposes a programme, based on the administrative system in China and consistency and future development of Chinese standards & Regulations, to draft a new National Standard for passenger car with ECE R13-H as the chief source and FMVSS 135 as an important reference. In order to investigate the feasibility of new technical specification applying to the products in existence, technical differences among GB 12676-1999,ECE R13-H and FMVSS 135 with regard to performance and testing requirements, testing items and type approval are analyzed, and verification tests are also conducted on two different vehicles. As the first attempt to compare and analyze braking standards & regulations at home and abroad, conclusions and suggestions proposed in this paper will be taken as one of references for the development of new standard for passenger cars in China.