Future metro train will be more energy-saving, more comfortable and more intelligent. On 18th September 2018, CRRC Qingdao Sifang Co., Ltd. revealed its new generation carbon fiber metro vehicle “CETROVO” at the Innotrans in Berlin.
This vehicle is the brand new generation metro vehicle. Developed with a number of new materials and technologies, it is a comprehensive upgrade in terms of energy saving, environmental protection, comfort, intelligence, etc. compared with traditional metro vehicle. The vehicle represents the newest technological achievements in metro industry and the trend of future metro vehicle. It is a symbol that metro vehicle is striding ahead in a “new age” of green and intelligence.
What does the new generation metro vehicle look like? What futuristic technology it has? What kind of new ride experience it will bring about?
A 13% weight saving realized by carbon fiber technology
Compared with traditional metro vehicle, the most important features of the new generation metro vehicle are lighter weight and better energy efficiency.
Light weight, i.e. save the weight as much as possible, is the main way to achieve better energy efficiency. As a new material, carbon fiber composite is known as the best lightweight material and has several advantages including high strength and low weight, presenting an excellent solution for producing lightweight trains.
According to Ding Sansan, deputy chief engineer of CRRC Sifang, the new generation metro vehicle incorporates advanced carbon fiber technology: the carbody, the bogie frame, the driver’s cab, the equipment cabinet and the equipment body are all made of carbon fiber composite materials. It is a metro vehicle with large-scale application of carbon fiber composite materials. In particular, key technical difficulties in structural design and molding of large complicated parts made of carbon fiber are solved, and this facilitates the full application of carbon fiber composite materials in the main bearing structures such as carbody, bogie frame and driver's cab.
The weight of the vehicle is significantly reduced with advantage of carbon fiber. Compared with traditional metal materials such as steel and aluminum alloy, the new generation carbon fiber composite metro vehicle is much lighter. To be specific, there is a over 30% decrease in the weight of carbody, driver’s cab and equipment cabinet respectively, a 40% decrease in bogie frame and a 13% decrease in the complete vehicle.
“Although the manufacturing cost of carbon fiber composite material is higher than traditional metal material, the former is much lighter and has obvious advantage in energy-saving, and it also has some excellent performances in fatigue resistance, tolerance to different weather conditions and corrosion resistance, which can effectively ensure the metro vehicle is free from failures due to fatigue and corrosion in 30-year of service life, thus the maintenance work is reduced and the entire life cycle cost is decreased,” Ding Sansan said, a lighter vehicle also reduces impact to the metro line.
In addition to carbon fiber lightweight technology, the new generation metro vehicle is provided with a new energy-efficient traction system to achieve better energy efficiency. By upgrading the asynchronous motors employed by traditional metro vehicles to the direct drive technology of the permanent magnet synchronous motors and adopting silicon carbide converter device, the traction efficiency of the vehicle is greatly improved.
It is estimated that the new generation metro vehicle can comprehensively save more than 15% of energy.
Flexible composition of metro vehicles
Compared with traditional metro vehicle, the new generation metro vehicle is more adaptable in terms of operation organization and can adapt to more complex operation conditions.
At present, all the metro trains in China are in fixed composition, and the formation of cars cannot be changed. The new generation metro vehicle is adopted with flexible composition for the first time. Two coupled cars are regarded as the minimum composition unit, and based on this, the metro vehicle is applicable in a flexible “2+N”-car composition depending on the traffic needs. This means that the metro train can be composed of 2 to 12 cars, and it takes less than 5 minutes to change the composition.
According to what Ding Sansan said, passenger flow for metro operation varies greatly in a day: morning and evening peak hours see large passenger flow while the mid-day handles a relatively small number of passengers. The flexible composition enables the new metro train to use more cars for peak hours and fewer cars for small passenger flow, and this is beneficial to cost-effective operation, energy efficiency and service improvement.
Compared with traditional metro vehicle, the new generation metro vehicle is tolerant to tougher conditions, which means that it can run smoothly in complex environmental conditions such as high temperature, high humidity, low temperature (-40℃) and high altitude (2500 m).
Given the fact that the metro lines feature many curves and small radius, the vehicle is provided with active radial system on bogie for the first time that can control the wheelset to roll on the radial position of the curve when the metro vehicle is detected to approach a curve section. This greatly improves the performance of the vehicle to negotiate a curve, especially the small-radius curves, and the minimum radius can be as small as 80 meters, which is much better than traditional metro vehicle; wheel wear is also substantially reduced, saving maintenance costs.
The vehicle can also run without external power supply. Power battery as the energy storage system can provide traction power for the vehicle to travel for 15 km. This facilitates emergency operation in case of power failure as well as vehicle operation in the neutral sections along the route and in depots.
High running stability, more riding comfort
The new generation metro vehicle incorporates advanced vibration and noise reduction technology to make the journey more comfortable.
When a metro vehicle is running, it will vibrate due to track irregularity, and the vibration should be reduced through the suspension system on the bogie. The suspension system of traditional metro vehicle cannot be adjusted, which is called passive suspension.
The new metro vehicle is designed of a full-active suspension system for the first time: vibration of the vehicle during operation can be immediately detected and damping of the suspension system will be subject to dynamic adjustment. In this sense, the suspension system can always suppress vibration to the best, realizing high riding quality.
It is also quieter inside the vehicle. As the noise reduction design is optimized, the noise level in the passenger saloon is only 68 dB when the vehicle is running, 3 dB lower than traditional metro vehicle.
According to what Ding Sansan said, like high-speed trains, the new generation metro vehicle is adopted with air-tight design and a sealed carbody for the first time. Passengers will not feel pressure on their eardrums due to pressure fluctuations in the saloon.
An “Intelligent Train”: watching videos on window
Benefiting from the modern intelligent technology, the new generation metro vehicle is also an “intelligent train”.
Intelligent services can be found in each detail of the vehicle. The passenger saloon is just like a touchscreen computer. To be specific, the car window acts as a super Pad to provide various graphics, texts and videos. Passengers can watch news, browse the Web, buy tickets, watch videos and live TV shows on the window. All these services are easily accessed by passenger’s finger touch on the window. Mirrors in the saloon also support touch technology and are provided with Internet access. Air conditioners in the saloon can automatically choose the appropriate temperature and humidity according to the actual weather and dressing index, making passengers feel more comfortable. The lighting system keeps track of the light environment of the saloon and automatically adjusts the brightness and color temperature. In addition, multimedia curved screen, self-cleaning seat and hearing aid system for hearing-impaired passengers are also provided. All these intelligent services will bring a new travelling experience to passengers.
For the new generation metro vehicle, the maximum operation speed is 140 km/h. The vehicle is adopted the driverless technology, which means that the metro vehicle is under fully automatic control on the whole journey, including vehicle starting, acceleration, deceleration, stopping, door opening and closing, and returning to the station.
Maintenance for operation is also more intelligent. For the vehicle, a powerful intelligent sensing system is established, where more than 1,100 monitoring points are set to sense the status of the train in real time. Automatic warning and remote maintenance are available in case of abnormal operation conditions. Meanwhile, with the help of the intelligent sensing system, the vehicle can be promptly arranged for maintenance when it is in sub-healthy status, and the line condition can also be detected and properly maintained, making the metro vehicles run safer and more reliable.
It is reported that type test and trial operation the new generation carbon fiber metro will be started in the next step.
