Advanced Control Technology for Braking Systems in Railway Vehicles

摘要

The safety guarantee maintenance is the appointed task for means of transport and other methods of on-ground transportation. The brakes are security requirements even in trains, which "should be stopped" once started. A mass of about 40 ton per car and a mass approaching 700 tons in a formation running on the Shinkansen 1 line, where running speed amounting to about 300 km/h maximum apply large loads of moving energy on brakes of rolling stock. Mechanical possibilities of safely withstand such loads and reliable operations when they are necessary are properties required for a fail-safe operation of rolling stocks. Such security properties of trains are provided by a mechanical brake unit, which uses friction force generated by compressing a brake shoe against car wheels. However, passengers traveling on a train suffer by the sensation of the force pulling them forward during the stopping at railway stations, which is certainly uncomfortable. When a strap or other supports are not used, even cases of falling down may occur. The coefficient of friction between a brake shoe and a car wheel increases accordingly to the reduction of the velocity, which is one of reasons behind the uncomfortable sensation by passengers at a sudden deceleration because their body does not comply with the motion. A brake unit installed close to a car wheel under the train floor is strongly affected by rain and snow. On a rainy day, the operation of the same brakes by a train driver requires a longer distance of running required for deceleration, which is extremely sensitive from the safety point of view. As it is well known, this is because the coefficient of friction changes under wet conditions. In that case, problems related to the nonlinearity and the uncertainty of friction properties when the train brakes are applied previously could be solved by the skill of the train driver, but later on, with an increased necessity of alleviation of the load on the train driver because of a wide scatter in hot and cold conditions occurring during the driving operation, it was planned to improve the "quality of deceleration," that is, the output of the brake system and to determine them as basic properties of trains. Under such a background, the author introduced a "new" braking theory to be used as a technique for the control of brakes and constructed a brake system capable of coping with friction characteristics to improve the "quality" of braking, including the comfort of train passengers. A short description of the effort is presented in this works.