Recently, the Ministry of Industry and Information Technology (MIIT) has publicly solicited opinions on the new version of the mandatory national standard "Technical Requirements and Test Methods for Passenger Car Brake Systems" (Draft for Comments) (hereinafter referred to as the "Draft for Comments") on its website. Subsequently, there was news that the "one-pedal brake" used by some models represented by Tesla will withdraw from the historical stage due to the introduction of the new national standard, and there was a heated discussion inside and outside the industry for a while.
In fact, compared with the previous "Technical Requirements and Test Methods for Passenger Car Brake System" (GB21670-2008) (hereinafter referred to as the "original national standard"), the "Draft for Comments" is not only updated in the detail of "one-pedal braking". It should be said that the issuance of the "Draft for Comments" is a timely adjustment of the brake system standards for passenger cars in the context of the rapid development of vehicle electrification and intelligence; At the same time, it will also have an important impact on the further evolution of the braking system.
One-pedal braking is not a "ban"
Although most of the public discussion on the Consultation Paper revolves around a certain brand's model and its one-pedal braking function. However, the new national standard is not a ban on specific technologies, and safety is still the primary concern.
"The public's controversy or concern about the one-pedal mode is more related to the driver's driving habits, and cannot be simply understood as the new national standard will stop or limit the one-pedal braking function. The Consultation Paper proposes that 'the braking effect achieved by releasing the accelerator pedal in forward gear cannot cause the vehicle to slow down to a stop', and there is no clear limit on deceleration. In my opinion, on the premise of ensuring safety, this is equivalent to giving car companies as much discretion as possible. Fu Zhengjun, director of brake products, electronics and software research and development of Beijing West Group in China, told the reporter of China Automotive News.
Zhou Xuan, director of VIE Science and Technology Technology Center, told reporters that the energy recovery of B-type electric regenerative braking system (which belongs to the electric regenerative braking system of the service braking system) can be divided into two ways: superimposed braking energy recovery and coordinated braking energy recovery. Superimposed braking energy recuperation, the motor anti-drag braking is superimposed on the normal hydraulic/pneumatic braking (friction braking), as long as the brake is pressed, the hydraulic/pneumatic braking with normal pedal opening and part of the electric braking (i.e. energy recuperation) will be generated. This method will lead to the actual braking force obtained under some working conditions greater than the required braking force, so that the vehicle abnormally enters the anti-lock braking state. Under normal circumstances, the electric braking will be quickly canceled after the vehicle enters the anti-lock braking state, and the deceleration given by the electric braking will be suddenly lost, resulting in an accident when the vehicle rushes forward. Stacked regenerative braking is typically used in conventional, non-decoupled braking systems. With the iteration of technological development, the brake-by-wire system is gradually moving towards the stage, and the brake-by-wire system can realize coordinated braking energy recovery due to its mechanical decoupling characteristics, that is, the braking force required by the vehicle is equal to the sum of electric braking and hydraulic braking, and the maximum use of electric braking to increase the recovery efficiency. For both the driver and the vehicle, the requirement of braking force and the final output are more secure and reliable, which is one of the reasons why the industry is developing brake-by-wire systems. "Looking back at the development history of B-type electric regenerative braking, we can find that its ultimate foothold is safety. The braking system is a key core component that has a great impact on the safety of the driver and the vehicle, and safety should come first, followed by convenience. He stressed.
It is reported that drivers who are accustomed to one-pedal braking may subconsciously step on the accelerator pedal in an emergency, and there are many traffic accidents and potential safety hazards caused by this in recent years. The Consultation Paper does not explicitly prohibit one-pedal braking, but stipulates that "for Type A vehicles and vehicles with both Type A and Type B electric regenerative braking systems, the braking effect achieved by releasing the accelerator pedal in forward gear cannot cause the vehicle to slow down to a stop." ”
"I very much agree with this approach, drawing the bottom line of safety with standards, and the choice of specific technologies should still be left to enterprises and consumers, and the market will make judgments. Moreover, the Consultation Paper provides a separate transition period for this amendment, so that enterprises have sufficient time to adjust their technology, redesign their products and transform their production lines. Zhang Junhui (pseudonym), a R&D engineer of an independent brand vehicle company, told reporters, "As far as I know, some vehicle companies have estimated that the functional requirements of single-pedal braking will change, so they are ready to modify or launch alternative technical solutions." At present, many models can enjoy OTA, which also brings a lot of convenience to the subsequent technical upgrade work. Of course, car companies need to communicate more with the public to explain the need for this change and ensure a good user experience. ”
The new requirements are in line with the trend of technological progress
In addition to the widespread attention caused by the one-pedal mode, there are also a number of detailed changes in the Consultation Paper, which confirm the positive interaction between the revision of the standard and the technological progress of the industry. Specifically, the Draft adds the requirement that "in the event of an electrical failure in the ECU or a damage to the internal circuit of the electronic control transmission between the ECU and the actuator (except for the power supply line), the parking brake shall be able to be carried out from the driver's position and the fully loaded vehicle shall remain stationary at 8% of the on- and downhill ramps", which is an echo of the technological progress of the parking brake system.
"Compared with the original national standard, the "Draft for Comments" specifically clarifies and refines the meaning of the control loop, that is, a failure backup requirement for the electronically controlled parking brake (internal control loop)." Fu Zhengjun explained.
Zhou Xuan analyzed: "This requirement is actually to clarify the use of dual-control dual-redundant EPB (electronic parking brake system), discrete EPB and other electronic control methods to achieve 8% parking brake requirements under single-point failure." ”
"Such changes are based on maintaining the bottom line of safety and echoing the progress of technology." Chen Yujue (pseudonym), a professor in the Department of Automotive Engineering at a university in China, believes that "it focuses on system redundancy. This means that even if the main control system fails, the vehicle will still be able to perform basic braking functions with a backup system. This requirement focuses on the driver's control problem, and when the critical braking system fails, the driver should realize the parking brake through the control device in the driver's seat to avoid the vehicle losing control; The focus on terrain adaptability, with the vehicle remaining stationary on 8% of ramps when fully loaded, meant that the braking system had to have sufficient braking force to cope with emergencies in different terrain conditions; At the same time, there is also a focus on failure mode management, and car companies need to design systems that can remain functional in specific failure modes, which can help reduce the safety risks caused by a single failure. In his view, this new technical requirement is intended to improve the safety performance of the vehicle in extreme situations, ensuring that the vehicle can still be safely parked even if the electrical system partially fails, thereby protecting the safety of passengers and pedestrians, reflecting the regulator's continued focus on improving the reliability and safety of automotive electronic systems.
In addition, the Consultation Paper also adds a requirement to allow the parking brake to be lifted by a remote control device, i.e., "the disengagement of the braking surface of the parking brake system can only be controlled by the driver in his driver's seat through a system that does not function due to leakage." This requirement does not apply to the Remote Controlled Parking (RCP) function."
"This is mainly adapted to some of the needs of autonomous parking and unmanned driving scenarios. With the development of autonomous driving and connected car technology, more and more cars are equipped with advanced driver assistance systems, including the ability to remotely control parking. The remote-controlled parking feature allows the driver to control the parking from outside the vehicle using a device such as a remote control or smartphone. This feature relieves the driver of the burden of maneuvering the vehicle in tight spaces and provides additional assistance for situations that the automated parking system cannot handle. "The application of these smart technologies also brings new challenges and security risks, and how to ensure the reliability of remote control systems, how to prevent signal interference and hacker attacks and other issues need to be addressed by the industry." ”
Clarify the scope of application of functional safety requirements
"There is another detail in the Draft for Comments that deserves attention." Chen Yujue said, "It clarifies the scope of application of the functional safety requirements of the braking electronic control system, that is, 'the braking electronic control system with functions such as anti-lock braking, electric regenerative braking, parking brake with electronic transmission, service brake with electronic control transmission'." ”
"Functional safety standards provide a detailed set of methods and processes for the design, verification and maintenance of electronic control systems, and the development process of functional safety helps to minimize the risk of vehicle failure caused by electronic control system failures and improve the safety and reliability of the system." Fu Zhengjun said, "The braking system is related to driving safety, whether from the perspective of improving the maturity and reliability of component development, or from the perspective of vehicle safety, the introduction of functional safety requirements has a huge role in promoting." ”
Chen Yujue told reporters that the definition of this scope of application includes not only the traditional anti-lock braking system before, but also the emerging electric regenerative braking and electronic parking systems in recent years. "For functional safety, the object is comprehensive and extensive, with uniform requirements for braking systems in different life cycles." He believes that the clarity of the scope of application of the "functional safety requirements for brake electronic control systems" in the "Draft for Comments" aims to ensure the safety and reliability of the braking system under various working conditions, which is crucial for improving the overall safety performance of the vehicle. At the same time, it also provides clear guidelines for R&D and production for enterprises, which helps to promote the innovation and development of braking technology.
Chen Yujue further analyzed that this statement concretizes the functional safety requirements, clarifies which types of brake electronic control systems need to meet the requirements of functional safety, and provides a clear direction for car companies and parts suppliers in the design and production process. Second, it also makes the development of braking system further standardized, more and more advanced braking technology is applied to automobiles, and clarifying the scope of application will help standardize the promotion of these new technologies; Third, it can effectively improve the safety performance of the whole vehicle, especially in emergency braking, energy recovery braking, etc., to ensure the stability and safety of the vehicle under various working conditions; Fourth, it can guide R&D and testing, and clarify the scope of application can help enterprises fully consider safety requirements in the R&D stage, so as to design products that meet standards and are competitive, and also provide a basis for testing and certification bodies to ensure that products meet relevant regulations and standards; Fifth, it will promote market competition, and unified functional safety requirements can help consumers understand the safety performance of different brands and models of automobiles, thereby promoting the healthy development of the market.
The road to standard revision under the iterative upgrading of technology
The safety of the braking system is the bottom line requirement, and the "Draft for Comments" promotes the industry to build a solid bottom line with standards, and "urges" the industry to improve product safety with the continuous iterative upgrading of technology, which is also a distinctive feature of the new version of the national standard.
It is understood that the "Draft for Comments" clarifies the requirements for the mandatory installation of Class 1 ABS for M1 vehicles. Although ABS is currently standard in relevant vehicles, it is still of great progressive significance to explicitly write it into the standard.
"First of all, this initiative increases the degree of standardization of standards. It is clearly required that M1 vehicles are required to install Class 1 ABS, which makes the standard more specific and clear, helps to standardize the industry's configuration behavior of ABS, and ensures that all M1 vehicles meet this safety standard; Secondly, it strengthens the public's awareness of safety, although ABS has been the standard configuration of most vehicles, but the clear installation requirements can further enhance the public's awareness of vehicle safety, especially for some relatively low-end or cost-sensitive models; Thirdly, the rights and interests of consumers are further protected, and the clarity of the standard means that they can expect all M1 vehicles to have at least Class 1 ABS, providing an important reference for consumers when choosing a vehicle. Zhou Xuan told reporters, "Of course, the clarity of standard requirements also prompts enterprises to continuously optimize and upgrade their ABS systems to meet higher levels of security needs, thereby promoting the technological progress of the entire industry." ”
"The safety needs of the whole vehicle are constantly evolving, and the mandatory installation of ABS reflects such a history. At present, some automotive markets around the world have put forward the mandatory installation of electronic stability control (ESC) integrated ABS in passenger cars. As a state-owned holding company, Jingxi Group has successfully mass-produced localized ESC products and has been stably used for many years. In the future, the development of ADAS will be inseparable from the support of ESC and more advanced brake-by-wire technology. Therefore, we need to rely on standards to continuously raise the bar for vehicle safety, which is very beneficial to the technological progress of the industry, enterprises, and traffic safety, including drivers and passengers. Fu Zhengjun said.
"The technological progress of the automotive industry is very rapid, and consumers can usually pay attention to a lot of information related to intelligent cockpit and autonomous driving, and the braking system is constantly iterating according to its own development logic." Zhang Junhui told reporters, "The brake system of passenger cars has begun to develop from traditional mechanical and hydraulic braking technologies, and the application of new technologies such as electro-hydraulic braking has accelerated; At the same time, due to the popularity of new energy vehicles, the trend of integration and intelligence of braking systems is also very obvious. According to reports, almost all foreign first-class parts suppliers such as Bosch, ZF, and Continental have relevant technology and product reserves, and have also achieved supporting applications. In addition, domestic enterprises in the field of automotive braking are also actively deploying in the direction of forward-looking technologies such as EMB (electromechanical braking). For example, Hengchuang Zhixing (Zhejiang) Electronically Controlled Brake System Co., Ltd., incubated by VIE, focuses on EMB system related technologies and has obtained more than 30 patents. BWI Group's achievements in the EMB field include more precise product control, lower latency, and plug-and-play, which makes it easier for OEMs to develop and deploy as a whole.
"The Consultation Paper sets out the basic safety requirements that braking systems must meet, whether it is traditional mechanical/hydraulic braking or electro-hydraulic braking (EHB), these bottom line requirements must be met. This helps ensure that all braking technologies improve performance and efficiency without sacrificing safety. Zhang Junhui said, "With the rapid development of technology and the continuous upgrading of demand, the issuance of the "Draft for Comments" can be said to echo the demands of the industry. On the basis of the original national standard, the "Draft for Comments" encourages enterprises to continue to carry out technological innovation with high standards, puts forward new requirements for emerging braking technologies (such as energy recovery braking and intelligent braking), and also leads the industry to develop in a more efficient, environmentally friendly and intelligent direction; At the same time, it has raised the entry threshold in the field of braking, promoted technological progress and optimized the industrial structure. ”
"Technology tends to evolve faster than standards and industry regulation. For example, in the field of EMB, there should be higher safety requirements to promote EMB to ensure braking safety in the event of failure on the basis of higher performance and higher redundant safety. Chen Yujue finally said.
Text: Ma Xin Editor: Pang Guoxia Layout: Liu Xiaoye
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