Zhang You, Weichai Power: Research Progress on Truck Powertrain Technology

The 2011 (4th) China Commercial Vehicles Development Exchange Symposium organized by the China Automotive Technology and Research Center and organized by the China Automotive Industry Information Network was held on June 23-24, 2011 in Beijing Guangxi Tower. The conference continued to focus on the permanent theme of “Exploring the Road to the Development of Commercial Vehicles with Chinese Characteristics” and discussed the theme of the year with “Technology Upgrade and Core Competence”.

The following is the speech of Mr. Zhang You , the director of the Weichai Powertrain Research Institute . The topic of his speech is "Research Progress on Truck Powertrain Technology":

Zhang You: Good morning, ladies and gentlemen, thank you very much for China Automotive Technology and Research Center and China Automotive Industry Information Network for providing us with opportunities for communication. The theme of this year is technology upgrades and core competitiveness. Since yesterday, leaders and experts have started commercializing The car industry has done some analysis. Now that we are a big automobile country, we are big but not strong. This consensus has come from our country to the enterprise. The important factor here is the lack of core competitiveness. So I think this year's theme of the year defines it as a technology upgrade and core competitiveness is just the right time. I come from the Weichai Powertrain Research Institute. Weichai Power is a manufacturing group of complete vehicles and parts. Now our company mainly uses complete vehicles as the leader, and the main power car as the core, production, R&D, automotive, vehicle and automobile. Parts and Equipment Manufacturing Group. Last year, Weichai Power's sales exceeded 90 billion yuan, and it is expected that it will exceed 100 billion yuan this year.

What I report to you today is the work of Weichai on truck powertrain technology. Please give us more valuable opinions.

The main content: First, the powertrain matching significance. Second, the main content of the powertrain matching work. Third, the powertrain matching research methods. Fourth, We Weichai power to do the work.

First, the powertrain matching significance.

The powertrain is the core of the car. The driving factors are more people talking about. Let me talk briefly. The first is our emission regulations, which is the driving factor. The second is fuel consumption. Experts spoke a lot. In fact, the situation of fuel consumption is very serious, including the emission of greenhouse gas carbon dioxide. Our country has made a commitment to the world. In fact, we all know that Euro VI will no longer have stricter emission requirements. It is the emission limitation of carbon dioxide, so actually reducing fuel consumption means reducing carbon dioxide emissions. From the point of view of user requirements, basically from the point of view of the application cost of the entire vehicle, the fuel consumption is basically 1/3, but with the continuous increase of fuel, the price of scarce resources. It is expected that the subsequent consumption of fuel will account for half of the total operating costs. The work we have to do to provide users with the lowest operating costs, so that your product competitiveness can be highlighted.

Why do we say that the powertrain is the core of a commercial vehicle? The power, economy, comfort, cost, reliability, and safety and environmental protection of the entire vehicle are all related to the powertrain. Therefore, the position of the powertrain is decided. Its core role. We have accelerated, climbed, and withdrawn lawsuits in terms of dynamics, fuel economy and fuel consumption in terms of economy, safety and environmental protection, and braking performance and emissions. From now on, the reliability of the engine is improving. It is basically 400,000 kilometers in our country. There is no less than 800,000 kilometers in development and 1.2 million kilometers in foreign countries. Reliability is mainly overhaul mileage and so on.

This table shows the main factors that affect the fuel economy of trucks. Considering the entire vehicle, the fuel energy is 100%. For the city's operating vehicles, the idle parking is relatively high, and the accessories consumption is relatively large. Of course, the main engine fuel consumption is Consumption factor, but accounted for 62% of urban transport vehicles. The consumption on the highway is relatively high, 62.4%, the loss of the shipyard system is 5.6%, the air resistance consumption is 2.6%, the highway is about 10.9%, and there is rolling resistance and braking. The difference between cities and highways is still very large.

Second, the power system assembly matches the main content.

There are several advantages to integrating from the powertrain:

1, to improve the efficiency of economy-oriented.

Based on the best match of operating conditions and road spectrum, the fuel economy of the vehicle is the lowest. Through the optimization analysis of the assembly, the engine, transmission and rear axle design parameters are reasonably selected so that the advantages of the powertrain system can be fully utilized. The design of the system optimizes the vehicle cooling and heat balance capabilities to give full play to engine performance and emission potential. The powertrain assembly as a whole, to carry out NVH optimization design to ensure that the entire vehicle comfort.

2, shorten the development cycle

System planning, collaborative development, clear goals, increase work efficiency, reduce collaborative work in the development process, save resources, reduce duplication in development work, avoid ineffective labor, and shorten the time to market.

3, improve the design quality.

The optimized alignment of the powertrain assembly makes it possible to meet the vehicle's design quality objectives with better coordination. Select mature components to reduce early failure rates and risks under new application conditions. Avoid repeating past mistakes and increase knowledge accumulation.

4, improve user satisfaction.

Focus on customer attention, through the application of consistency, improve brand awareness, achieve differentiation with similar products of other brands, and reduce the growth of vehicle warranty.

The matching of powertrain assembly targets is the same: 1. Vehicle power and fuel economy. 2, in line with industry standards and emissions, fuel consumption, noise regulations. 3, to meet the vehicle layout and installation requirements. 4, to meet the vehicle comfort / reliability / safety.

The power system assembly matches the main content:

From the beginning of project planning, simulation calculations are first carried out, various aspects are compared and analyzed, and the road spectrum is collected. Based on this requirement, engine, transmission rear axle development requirements are put forward according to the requirements of vehicle design, and there are performance, cost, structural layout, etc. The requirements are all inside. At the same time, NVH analysis is carried out, and then trial production of the powertrain is performed. The layout, installation, verification, and improvement of the entire vehicle are confirmed. After the program is confirmed, the market application is finally required.

Third, the powertrain matching research methods.

This is the demand for powertrain matching simulation. Generally speaking, we mainly consider the three aspects of power performance, economy, and emission performance. The power performance is mainly the withdrawal of lawsuit, acceleration time, climbing degree, and traction. From the economy will calculate the cycle conditions fuel consumption, constant speed fuel consumption, cruise fuel consumption and so on. Emission performance is cyclic performance emission performance.

The parameter input design parameters are still more, from the vehicle engine, clutch, gearbox, rear axle main reducer parameters, differential, vehicle theory parameters, brakes, cab parameters, and so on.

The output of the calculations is as follows: whether the maximum speed of the vehicle is required to meet the requirements, fuel consumption at constant speed of 100 km, acceleration performance, climbing degree, traction, fuel consumption of the cycle conditions, cruising mining oil consumption, slip characteristics, etc.

Gearbox selection, now the 20-speed gearbox is also out, there is a map, we see one is 9 files, one is a 10-speed transmission, low-speed zone 16 is closer to the low-speed zone.

The rear axle ratio trend is also quite obvious. From the Hanover show, speaking of the Mercedes-Benz speed ratio, it has reached 2.8, and the domestic speed ratio is relatively high. This is mainly related to the characteristics of our previous car use. We used to be a Dora jogging. There are also restrictions on engine power and torque. Now, all of them are scheduled to run fast. Engine distortion does not increase. We have conditions to choose a lower speed ratio, and it is very obvious that the speed ratio is reduced to improve fuel economy.

This is based on the matching of operating conditions and road spectrum. The above vehicle is a typical truck used on a freeway. So everyone sees that the road that it basically runs is a high-efficiency area outside the engine. Everyone looks at this side from the maneuver. The scope is mainly 1200-1400 rpm. The following figure is a typical road map used by urban passenger cars. Basically, its display range is relatively low, 800-1200 megabytes, and the torque is 400-600 kilos. This is basically suitable for the characteristics of urban public transport.

From the matching research of our powertrain, we must be concerned about the conditions used by users. This is the European standard, including urban road sections, suburban road sections, and expressway sections. Actually, it is similar to the regulations of our Ministry of Communications. It is Strong adjustment of comprehensive application of the car.

We feel that comprehensive fuel consumption is an evaluation of the overall performance of the vehicle. However, in actual use, it cannot meet the requirements of some large customers or group users. The power consumption of large customers and group users is relatively single. For example, the expressway is a standard load. I hope the speed is 80 kilometers to 90 kilometers. Our powertrain matching research core hopes to make specific optimizations for different operating conditions, so that the vehicle's fuel consumption reaches a minimum, while satisfying the requirements of power, emissions, and noise.

So we are now proposing a concept that will form a powertrain matching method based on operating conditions and spectrum.

The first step is to determine the main working conditions and major performance requirements for research, and to classify and study the working conditions. On the basis of previous studies, market conditions were used to classify conditions and enter boundary conditions for different conditions.

In the second step, product development and performance development, input boundary conditions according to operating conditions, evaluate product performance adaptability, and perform powertrain matching development.

The third step, single-point system, according to the principle of maximizing user revenue, establish the relationship between operating conditions and products, through the single-point system, to achieve the power requirements to meet user requirements.

Fourth, Weichai Powertrain Research Introduction.

We all know that Weichai Power has a truck powertrain gold industry chain and has laid a good research foundation for the optimization of powertrain assembly. The market share of heavy-duty vehicles is 10.3%, ranking fourth in our heavy-duty trucks. Last year, the sales situation was slightly higher than Futian, which is basically the same. Everyone is familiar with the engine, we have a market share of 36% for the heavy-duty vehicles with more than 14 tons and the industry first. The transmission has a market share of 89% in the heavy-duty vehicle market of over 14 tons, and the industry is the first. The drive axle has a 35% share of the heavy-duty vehicle market of over 14 tons, and it ranks first in the industry. This is the company below Weichai Power.

In 2009, Weichai Power Construction National Engineering Research Center for Commercial Vehicle Powertrain Assembly has been completed. Now it has settled in. Our total investment is 570 million yuan and the building area is 83,000 square meters. In addition to the engine experimental platform, we also build momentum. Assembly test bench.

Last year, I established the Powertrain Research Office. I was the first director responsible for this development organization. According to the company's planning and market demand, we are currently mainly researching the optimization and matching of the powertrain system for developers' vehicles and construction machinery. This has also taken over the national powertrain development project, as we now assume some projects of the Ministry of Science and Technology. At the same time doing it.

Judging from the matching of our power system, at present, our powertrain analysis and calculation are currently mainly dynamic and economical. We have the highest speed, climbing speed, continuous shifting, direct shift acceleration, and constant speed fuel consumption. There are weighted fuel consumption and so on.

When we conducted the screening of multiple projects, we listed a figure by calculation. We are now most concerned about dynamics and economy. The abscissa is the acceleration time that we directly block, and the ordinate is our constant speed fuel consumption.

This figure is a continuous shift acceleration time, weighted oil consumption scatter plot. At the same time, we have calculated the acceleration time for the rear axle speed ratio and the speed ratio of the gearbox. There is an analysis of the same gearbox and four speed ratios. The first option is our benchmark. We only recommend three gearboxes. The speed ratio of No. 4 gearbox is the closest to our benchmark vehicle. Finally, we chose this data to develop it.

From the power system assembly to the calculation of multiple programs, we will put forward requirements for engine performance development. At the same time, the engine installation requirements and the cost of the engine will be required. We will also put forward requirements for the development of transmissions. For example, transmission input torque, gear requirements, connection methods, drive axles, etc. will be required. The load and speed ratio of the drive axle will be required, including the cost of the drive axle. This ratio is based on the vehicle requirements for analysis.

This is an example we have done. This is an example done on a medium-sized card. The above line is a 16-ton sub-high-end isokinetic optimization before our conversion. After our improvement, we used our own engine to adjust the With characteristics, the speed ratio of gearbox and gearbox was adjusted. After the improvement, we saw that the fuel consumption improvement effect of 5 tons of 16 tons is very obvious. The fuel consumption of the entire constant speed has been reduced to varying degrees, and the reduction range is very obvious. This is the increase in the highest grade of constant speed fuel consumption before and after improvement. The green line is the highest grade, which is one kilometer. The red line is a five kilometer route. It should be said that we also feel very obvious.

At the same time as fuel consumption is declining, everyone can see that dynamics are still acceptable. This is our direct shifting, continuous shifting, from 0 to 90 kilometers, basically no change before and after improvement. The time for the direct shift improvement was slightly longer, but it was also within the acceptable range. From the lowest stable speed of the vehicle, the straight line of 12 tons was 29.1 kilometers. After the improvement, it was 22 kilometers. Before the 16 tons was changed, it was 27.1 kilometers. After 21.9 km. The maximum withdrawal of 12 tons was 109 kilometers, 112.8 kilometers after modification, and the former 16 tons was 106 kilometers after modification, and 112.6 kilometers after modification. In addition, the noise reduction is also very obvious.

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