1 . Abstract

As a rapid mass transportation operating under extreme conditions such as high speed, heavy load, and long distance, Shinkansen trains are required to meet the highest standards of safety, comfort, environment and maintenance. The bogie is a single system. The reliability of each component of the system is directly linked to safety. Among the many components of the system, we put priority on improving the reliability of the bogie frame, which is a welded component, and the bearing of the gear box. Together with the improved bogie frame and gear, small and light driving motor is installed on the bogie, which reduced overall weight of the bogie. For the bogie frame, reliability is improved by reducing the number of welds. Also, its side beams are used as integrated air tanks by taking advantage of the structural feature. As a result, the number of air tanks on the train is reduced and contributed to the weight reduction of the rolling stock. Also, by making the bogie frame into a tank, soundness of the welded bogie frame can be confirmed by checking air leakage. A double helical gear unit is used for the first time for Shinkansen in service. A cylindrical roller is adopted for its gear bearing. By doing so, we were able to eliminate a task for clearance adjustment while improving reliability. With introduction of these new technologies, brake pads are made thicker, and the axle bearings are enlarged for longer life. In addition, a compact and lightweight full active suspension system which can be driven by AC100V is installed. By this application, vibration of the car body is reduced significantly, especially when Shinkansen is running through the tunnel section. The developed bogie shown in Figure1, has been installed in the latest Shinkansen N700S since July 2020.

２．Technologies of N700S bogie

2.1 Improved bogie frame

The bogie frame is a welded component consisting mainly of side beams and cross beams. The structure of the side beams is changed from ‘Monaka’ type to hat type to reduce the number of weld lines and thus reducing weight. For the ‘Monaka’ structure, frame stiffness is maintained by the internal reinforcing plates. In the hat structure, a U-shape component is welded to a lower plate. Stiffness of the frame is maintained by increasing thickness for part of the lower plate where high strength is needed. The internal reinforcing plates are no longer required because of side beam toughness improvement. The central part of the side beam is configured as an integrated air tank, thus making it possible to reduce the number of tanks mounted on the car.

2.2 Improved gear unit

Conventional helical gears generate force in the direction of the axle due to the gear rotation torque and the force is received by bearings. The double helical gear device consists of two helical gears facing each other in the direction of the axle and the axial force generated by the driving torque is canceled by them. As a result, the load on the bearing is reduced and the life of the bearing is extended.　In addition, cylindrical roller bearing is adopted for gear device. By this application, the clearance adjustment task can be eliminated from maintenance while improving reliability.

2.3 Improved induction motor

By adopting low-loss and high-heat-resistant SiC device in the converter-inverter system, the number of induction motor poles is increased from 4 to 6. Also, by optimizing the structure of rotor and stator, downsizing of induction motor is realized.

2.4 Improvement of ride comfort

We developed a full-active suspension system which has a compact structure with a small driving motor and hydraulic pump attached to the conventional semi-active suspension. A small motor driven by AC100V is installed, thereby reducing the size and weight of the system.

3.Conclusion

This technology contributes to ensuring safety and stability of railway transportation and improving passenger comfort. We hope that this will promote the use of railways, revitalize the economy by stimulating business and tourism demands, and contribute to decarbonization.

Seiji Kanamori
Central Japan Railway Company (1-1, Minamiiba, Naka-ku, Hamamatsu, Shizuoka, 432-8037）

Kei Sakanoue
Central Japan Railway Company (1545-33, Ohyama, Komaki, Aichi, 485-0801)

Masahito Adachi
Central Japan Railway Company (1545-33, Ohyama, Komaki, Aichi, 485-0801)

Tomohiro Otsuka
Central Japan Railway Company (1-3-4, Meieki, Nakamura-ku, Nagoya, Aichi, 453-8520)

Hirokazu Kato
Central Japan Railway Company (1545-33, Ohyama, Komaki, Aichi, 485-0801)