China Green Freight Action (CGFI) advocates green management, green technology, green driving, namely the "three green" concept. Among them, the green technology action vigorously promote by reducing the weight of the truck, reduce fuel consumption, to reduce costs, improve efficiency, this is the research object of this paper: truck lightweight.

1. the Importance of Promoting the Lightweight of Freight Cars

The size of the car's own mass is one of the important factors affecting fuel consumption, so the lightweight design of the car has become a trend. For the freight and logistics industry, reducing fuel consumption has become the key to energy saving and emission reduction. It is very important for the sustainable development of China's freight and logistics industry to realize the lightweight of freight cars, reduce fuel consumption, increase load quality and improve transportation efficiency.

Relationship between Lightweight and Fuel Consumption of (I) Truck

The power of the engine is mainly consumed to overcome the driving resistance of the car. The driving resistance of the car is composed of air resistance, rolling resistance, acceleration resistance and climbing resistance. Air resistance is mainly related to the shape of the body and the windward area, especially when driving at high speeds, but it has nothing to do with the total mass of the vehicle; and the rolling resistance, acceleration resistance and climbing resistance other than air resistance are all The total mass of the vehicle is proportional, so reducing self-mass is an important factor to reduce the above three resistances and an effective measure to reduce fuel consumption. According to relevant foreign test data, the vehicle can reduce its self-quality by 10% and reduce fuel consumption by 6% ~ 8%. For trucks, reducing self-quality also improves the effective load quality, that is, increases the quality utilization coefficient, thereby improving transportation efficiency and reducing transportation costs, which is relatively low fuel costs.

Relationship between Lightweight and Exhaust Emission of (II) Truck

Fuel consumption is closely related to exhaust emissions. Automobile exhaust is the main cause of greenhouse effect and air pollution, especially carbon dioxide emissions have increased significantly in recent years. Major countries in the world have successively formulated or are formulating strict regulations to limit fuel consumption and emissions. my country's newly revised "Environmental Protection Law" and the introduction of various measures to reduce motor vehicle emissions have prompted the truck industry to find an effective way to reduce emissions through technological innovation. Relevant statistical results show that for every 100kg of car weight loss, fuel consumption per 100 kilometers can be reduced by 0.4 liters, and carbon dioxide emissions can be reduced by 1kg. Therefore, the realization of environmental protection through the lightweight of automobiles is called an important direction for the development of automobiles, especially trucks.

Relationship between lightweight of (III) truck and transportation service

The purpose of lightweight trucks is to reduce the weight of the car as much as possible, enhance the power performance of the car, reduce the fuel consumption of the car, and reduce the emission of exhaust pollution under the premise of ensuring safety performance and strength. At present, my country implements the standard of 49 tons of total vehicle weight. If transportation companies want to make money, they will not be fined. Lightweight trucks are a way to go. From the perspective of freight companies, the reduction of the quality of trucks can save the consumption of raw materials, reduce production costs, improve market competitiveness, and obtain direct economic benefits. Under the same transportation conditions, cargo owners will be more inclined to light weight, low fuel consumption vehicles, lightweight design can better meet customer requirements. Therefore, the realization of truck lightweight has a positive role in promoting the transportation services approved by the cargo owners.

Lightweight Technology of 2. Truck

Use lightweight metal and non-metal materials, or use modern design methods and effective means to optimize and design trucks. Under the condition of ensuring the overall performance of the car, try to reduce the weight of the truck itself, so as to achieve weight reduction, Comprehensive performance indicators of consumption reduction, safety and environmental protection. However, the lightweight truck is not simply to make it lighter, it should be to ensure that it does not affect the original performance of the car, not only to effectively reduce the weight of the car, but also to ensure the safety of the car in the driving process., Crashworthiness, vibration resistance and comfort, at the same time do not increase the cost of the car itself, to avoid increasing the economic pressure on users to buy a car. Therefore, the lightweight technology of trucks mainly includes: structural lightweight technology, key component lightweight technology, and new material technology applications.

Lightweight Technology of (I) Structure

Starting from the change of vehicle structure, through structural optimization, local weight reduction, the use of new structures and other means to achieve the purpose of structural lightweight. For example, the frame longitudinal beam is changed from double layer to single layer, and the parts with large load are locally strengthened.

1. The application of high-strength steel on the tractor frame changes the frame longitudinal beam from double layer to single layer;

2. Shorten the wheelbase and rear suspension of the tractor, improve the maneuverability, reduce the self-weight and meet the requirements of national standards for the length of the car train.

Lightweight Technology of Key (II) Parts

Under the premise of meeting the requirements of use, the vehicle is deployed around the weight reduction of the core purchased parts of the vehicle. For example, a new type of axle, a suspension system with few leaf springs, and disc brakes are used to replace drum brakes.

1. Axle lightweight technology;

2. Air suspension technology;

3. Less leaf spring suspension system;

4. Single wide tire technology.

Application of (III) New Material Technology

Use lightweight materials (such as aluminum, magnesium, ceramics, plastics, glass fiber or carbon fiber composites, etc.) Vehicle structure design, such as the use of aluminum alloy shell transmission and other new materials transmission.

1. Application of new material technologies such as aluminum alloy rims, transmission housings, fuel tanks, radiators, bumpers, rims, etc. on vehicles;

2. The promotion and application of disc brakes on tractors.

3. status of lightweight of freight cars in China

At present, China has accelerated the pace of technological development of new models through joint ventures, cooperation and technology introduction with international advanced automobile production countries, and the application of lightweight materials for trucks has also accelerated. With the increasingly fierce international competition in China's automobile market, domestic vehicles should reach the level of similar foreign vehicles, so it is urgent to expand the application of new lightweight materials. At present, the major domestic truck manufacturers have put forward the strategy of independent development, and some have started lightweight research. Domestic trucks have more development potential due to their larger self-quality than foreign cars of the same level and a larger gap in quality utilization coefficients.

According to the survey of relevant institutions, in terms of the energy efficiency level of bicycles, the energy consumption level of heavy trucks in China is about 20%-30% higher than that of the United States. The reason is that the research on lightweight of trucks in China started late, and the lightweight technology has not been paid enough attention to in the manufacturing and use of ordinary trucks. At the same time, there are many brands and structures of trucks in my country, uneven performance and quality, insufficient application of new structures, new processes, and new technologies, and low levels of specialization and standardization are all important factors for the unsatisfactory development of truck lightweight in my country.

However, with the proposal of the overall requirements of energy conservation and emission reduction in China, the Ministry of transport has proposed that it will focus on promoting the introduction of the standardization policy of commercial truck models in the future, as well as the proposal of the concept of standardization, specialization, lightweight and cleaning of freight vehicles under the advocacy of China's green freight action. China's freight and logistics enterprises, especially professional freight enterprises, are developing in the direction of lightweight.

Taking cold chain transportation as an example, with the continuous increase of transportation vehicles nowadays, 'lightweight design' has become an urgent need to reduce global transportation vehicle emissions. Lightweight products is one of the development trends of refrigerated thermal insulation automobile technology. With the continuous improvement of the quality utilization coefficient of automobile chassis and the rapid development of highway construction, in the face of high logistics and transportation costs, the momentum of accelerating the development of heavy vehicles will be further strengthened. This is to improve the strength and rigidity of the chassis, and pay special attention to reducing its own weight, increasing the dimensional stability and impact resistance after loading, and ensuring the reliability and safety of the whole vehicle, to meet the needs of freight companies Dora Run Lido.

4. CGFI green freight vehicle lightweight requirements

In view of the fact that the development of lightweight trucks in China is relatively lagging behind and the needs of the development direction of lightweight trucks in the future, one of the important contents of the "CGFI Green Freight Vehicle Standard" formulated by China's Green Freight Action is to encourage lightweight trucks, that is, to encourage the improvement of the load quality utilization coefficient of commercial trucks. This is an important part of the vehicle lightweight technology to promote the development of green freight.

The difference between operating trucks and ordinary vehicles is that operating trucks are produced by transporting goods, so the transportation capacity of trucks is a very important indicator. The load mass utilization coefficient reflects the ability of the transport vehicle to transport goods under the same quality, and under the premise of ensuring safety, the higher the load mass utilization coefficient, the higher the technical level of the vehicle. Therefore, in the CGFI green freight vehicle standard, the technical requirements for green freight vehicles are put forward by drawing on the requirements of the utilization coefficient of vehicle load quality in the draft of "Technical Requirements for Urban Logistics Distribution Vehicles.

Limits Requirements for Utilization Coefficient of Load Mass of Green Freight Vehicles

Vehicle type	N1		N2		N3
Total mass M(kg)	M≤ 1800	1800≤ 3500	3500≤ 4500	4500≤ 12000	12000< M≤ 16000	16000< M≤ 20000	20000< M≤ 24000	M＞ 24000
Ordinary truck	≥ 0.65		≥ 0.75	≥ 0.85	≥ 1.0	≥ 1.1	≥ 1.2	≥ 1.3
Dump truck	≥ 0.55		≥ 0.65	≥ 0.75
van	≥ 0.50		≥ 0.60	≥ 0.90	≥ 1.3
closed truck	≥ 0.35	≥ 0.60	≥ 0.65	≥ 1.10	—

Restrictive Factors of Lightweight Development of 5. Truck

At the beginning of 2014, the Ministry of Transport proposed the "Four Transportation" development strategy, and the industry began to comprehensively deepen reforms. Transformation and upgrading, low-carbon green cycles and sustainability have become important directions for industry development. Under the policy of energy conservation and emission reduction in the establishment of a resource-saving and environment-friendly society, the concept of lightweight trucks has been valued by more and more institutions. However, the current practice of truck lightweight effect is not good, because there are the following constraints.

(I) overload hinders lightweight

Overloading can be said to be a stubborn disease of road transportation in our country. With more efforts, the phenomenon of overloading will become less. Once it is relaxed, it will revive. This is also recognized as a major obstacle to the continued development of China's truck lightweight. On the one hand, overloading offsets the energy-saving and efficiency-enhancing effects of lightweight. On the other hand, in order to be overloaded, individual freight companies have made direct agreements with refitting factories and even vehicle manufacturers to require manufacturers to make trucks heavier. Therefore, only by thoroughly solving the problem of overload can lightweight be implemented.

(II) materials hinder lightweight

The application of new materials is one of the three major technologies for truck lightweight. However, the real difficulty is the research and use of new materials. After research, the application of new materials is the main way to reduce the weight of foreign trucks. The main way to reduce the weight of trucks is to apply new materials. Aluminum, magnesium alloys and engineering plastics are widely used. For some automatic valves, if plastic is used instead of metal parts, the weight of the car can be reduced by at least half. Developed countries in Europe and the United States began to study the application of new materials 20 years ago, but China started late, compared with them, there is still a big gap.

(III) related standards and regulations need to speed up the development

Any innovative technology is closely related to the national policy orientation. The practice of truck lightweight in foreign countries shows that the guidance of policies, the improvement of legal system, the basic role of standards and norms, and the application of industry management measures coordinated with vehicle manufacturing and vehicle use departments are all important driving forces for truck lightweight. At the same time, the advocacy industry self-discipline document issued by the freight and logistics industry association is also an important supplement. However, there are no national standards and industry standards on lightweight in China, and the laws and regulations are not perfect in lightweight, which is an important constraint on the lightweight of trucks.

6. policy recommendations

In order to speed up the development of lightweight trucks in China, the following policy recommendations are made to the competent government departments:

1. Systematic study of foreign vehicle lightweight research and application status;

2. Improve national standards and relevant laws, regulations and industry rules;

3. Strengthen the research on structural lightweight technology in truck lightweight;

4. The application of lightweight parts certified by third-party testing institutions shall be regarded as legal modification;

5. Strengthen the research of new material technology and increase the promotion of new material application;

6. Amend the GB1589 national standard on the truck lightweight "truck total mass limit" provisions;

7. After technical demonstration, the relevant provisions of the vehicle quality utilization coefficient in the green freight vehicle standard promoted by China's green freight action shall be adopted in the policy formulation;

8. Include lightweight models in the field of financial subsidies, and give higher subsidies to models with air suspension and other configurations.

Realizing the lightweight of trucks is not only one of the important signs for my country to become an industrial power, but also one of the important promoters of the sustainable development of my country's freight and logistics industry. It is also an important means for my country's transportation industry, especially road freight industry, to save energy and reduce emissions. One, this is a major issue in the long-term pursuit of green technology in China's green freight action. Although there is still a gap between my country's truck lightweight and the international advanced level, as long as policies, clear goals, and effective measures are formulated, my country's truck lightweight business will appear in front of people with a new look.