On the 18th, the concept model of China's future double-deck high-speed rail EMUs, developed by the Chinese Academy of Sciences, was disclosed by the media and attracted attention. What is the current R&D situation of double-deck high-speed rail EMUs in the world? What technology is the most economical and safe?
On the same day, in an interview with a reporter from Science and Technology Daily, Professor Zhang Weihua of Southwest Jiaotong University said that the next generation of high-speed trains in Germany and France advocate the use of double-deck EMU technology, with the aim of improving passenger capacity, providing transport capacity and improving economy.
"As far as speed is concerned, as long as the design and technical problems such as low gravity center and large capacity are solved, the single-deck speed can run at 350 kilometers per hour, and the double-deck speed should be no problem." Zhang Weihua said.
When the train runs at high speed, the centrifugal force will cause instability when turning at high speed, which is also the most critical problem in the development of double-deck high-speed EMUs.
Zhang Weihua believes that as long as the car's weight center is low and the lateral component of centrifugal force and super-high gravity of curve is offset at the prescribed equilibrium speed, the safety will not only be no problem, but also be better.
How to achieve low center of gravity and large capacity? "Germany's next generation of high-speed trains hope to use independent rotating wheel technology to make the whole train achieve low floor, so as to maintain a good double-deck space." Zhang Weihua said.
The so-called independent rotating wheel is to install two wheels on the axle through rolling bearings. The wheel can rotate freely relative to the axle, while the axle does not need to rotate.
"Compared with the rigid wheelset of the track vehicle, the shaking head and lateral movement of the independent rotating wheelset are no longer coupled, thus realizing the decoupling of the left and right wheels. There is no longitudinal creep force in theory, so there will be no snake instability." Zhang Weihua explained that there is no limit on the critical speed of snaking, so that vehicles with independent wheels can achieve higher running speed. At the same time, because the axle does not rotate when running, it can cancel the public axle or make the axle concave to reduce the height of the floor.
In addition to the low floor technology, Zhang Weihua believes that it also includes the overall technology of car body layout, including the layout of passenger rooms and seats (or sleepers), the boarding problem of the original equipment under the car, and the large capacity car body technology (structure design and manufacture) besides the low floor.
According to the open data, the technology of double-deck EMU has been mature in the traditional powerful high-speed railway country. For example, France's TGV Duplex EMU, after a long period of operation and many improvements, can increase passenger traffic by 50%, continuous running speed can reach 320 km, can be regarded as the king of double-deck high-speed EMU.
Japan had a double-decker high-speed EMU 20 years ago. Shinkansen E4 series cars were put on line in 1997 with a speed of 240 kilometers per hour, 16 carriages and 1 634 passengers. They are the most passenger-carrying high-speed vehicles in the world. At present, China's 16-section long-marshalled "Fuxing" EMUs have a fixed number of 1133 members each. Just before the Spring Festival, 17 long-marshaled "Fuxing" EMUs were issued, each with a fixed number of 1283 passengers.
The development of double-deck high-speed railway EMUs in China is also under way. In November 2018, the power-dispersed aluminum alloy double-deck high-speed EMU developed by Zhongcha locomotive and locomotive made its first public appearance. With streamlined headstock and modular design concept, the vehicle can achieve 4/6/8 sections of marshalling. There are 820 seats in 8 sections of marshalling vehicle, with a maximum passenger capacity of 1708.
According to reports, the double-deck EMU is aimed at the international market, based on the technology platform of 160 kilometers per hour. The core components of the car body and bogie are designed and validated according to the standard of the high-speed EMU. The technology can be upgraded according to different requirements, reaching speeds of more than 160 kilometers per hour. At the same time, the vehicle adopts lightweight design, compound braking control, safety, energy saving and environmental protection.
"Although it is a double-deck EMU, its vehicle limit is the same as that of a single-deck EMU." Zhang Weihua said that the existing lines and contact networks are applicable.
Source: Science and Technology Daily