Riding Comfort relating to Maglev Guideway

Transcription

1 Riding Comfort relating to Maglev Guideway Makoto UENO, Masao URABE Toru KAJIKAWA, Atsuhito YAMAMOTO Civil Engineering Div, Maglev System Development Dep. Railway Technical Research Institute Yaesu Chuoh-ku, Tokyo Japan Linear Express Development Div. Central Japan Railway Company Yaesu Chuoh-ku, Tokyo Japan Summary In the maglev system of Japan Railways, vehicles run through a U-shaped guideway composed of ground coils and concrete sidewalls. As for the system of ultra high-speed, long-wavelength guideway irregularities must be controlled to secure good riding quality. It is difficult to control the position of each ground coil strictly because they are discretely distributed on the surface of sidewalls. So we manage the position of each guideway unit as an effective countermeasure. We estimate the relation between irregularity of guideway unit-lengh and vehicle-vibration. Key words: Maglev, guideway irregularity, track maintenance, vehicle vibration, long wave-length 1. Introduction In the maglev system of Japan Railways, levitated vehicles running at a ultra high speed of 500km/h are guided by ground coils which are attached on the sidewalls. And because of the ultra high speed, long wave-length guideway irregularities must be controlled to secure the riding quality. We explain countermeasures which we have taken so far, and consider a maintenance method from the actual data of vehicle vibration and inspection data of guideway irregularities of the Yamanashi Maglev Test Line. 2. Configuration of Guideway In the maglev system of Japan Railways, vehicles run through a U-shaped guideway which consists of ground coils and concrete sidewalls. In levitated running, the vehicle runs guided by those ground coils. It is difficult to control the position of each ground coil strictly because they are discretely distributed. Three types of sidewalls are designed for the Yamanashi Maglev Test Line. They are the directattaching type, the panel type and the beam type. In the cases of the panel type and beam type, sidewalls are made of precast-concrete produced at a wayside factory, and ground coils are attached precisely on the sidewalls at the same factory. It is more effective to adjust the sidewall position than to adjust the position of each ground coil for the management of the long wave guideway irregularities. In both types, sidewalls

2 are separated from the infrastructure so that their position can be aligned even if the infrastructure was moved. The standard length of a sidewall unit is 12.6m. 3. Management of unit and survey datum point In order to ensure the satisfactory riding quality, the irregularity of guideway must be secured in less than 6 mm on the 150m wave-length at the Yamanashi Maglev Test Line. For this purpose, datum points are set by a highly accurate survey, on the guideway floor along the centerline at intervals of 12.6m which is equal to the length of sidewall unit. In the panel type and the beam type guideways, the position of each sidewall is adjusted based on these survey datum points set up in advance. Therefore, sidewalls are automatically controlled for long wave-length irregularities. Allowable errors in setting datum points and sidewall are shown in Table.1. Table.1 Allowable errors of guideway construction Item of error Allowable value Survey of datum point 2 mm Irregularity of line 4 mm for each side wall 4. The guideway inspection car Guideway irregularities must be inspected to keep the satisfactory riding quality. A guideway inspection car inspects guideway irregularities. The inspection car uses electromagnetic coil-displacement-sensors, optical- displacement-sensors and laser gyro equipment. The displacements detected by various displacement sensors are indicated relatively to the carbody. Irregularities inherent to the guideway are obtained by coordinate transfer operation. _In addition, inspection of 150m wave-length irregularities is required. For this reason, the transfer method by a Finite Impulse Response (FIR) filter is used for long wave-length irregularity inspection. _ 5. Angular bent in the curve section and vehicle vibration The Maglev guideway composed of sidewalls on which ground coils are attached does not take the form of continuous line unlike the conventional railways. In the curve section, therefore, the angular bent occurs every unit and the unit-length guideway lateral-irregularity appears. We investigated the influence of unit-length irregularities on the lateral vibration of actual running vehicles. Fig.1 shows the frequency components of lateral irregularities of ground coils detected by the inspection car, in the curve section of 8,000m radius.

3 Amplitude Unit-length Bogie lateral acceleration Body lateral acceleration Frequency [Hz] Fig.1 Lateral irregularities of grand coils Amplitude Non-filtering Filtering Frequency [Hz] Fig.2 Frequency of vehicle lateral vibration The component of unit-length 12.6m is distinguished. Fig.2 shows the frequency components of the lateral acceleration of bogie and the lateral acceleration of body, when the vehicles run on the curve section at a speed of 500km/h. The frequency of 11Hz, equivalent to the guideway wave-length 12.6m at a speed of 500km/h, is distinguished in the bogie acceleration but not in the body acceleration. So it is clear that the unit-length irregularity does not affect the riding comfort.

4 Unit-length Amplitude 0.08=1/12.6m ,2 Space frequency [1/m] Fig.3 Frequency of lateral acceleration of body On the other hand, the frequency of approximately 6 Hz is dominant in the bogie acceleration. It is surmised that frequency of approximately 6 Hz is the natural frequency of the bogie in the lateral direction. Fig.3 compares the frequency component of body acceleration filtered by the riding comfort filter and that not filtered. In the body acceleration on which filtering has been executed, the component of approximately 6 Hz decreases and those of 1_3Hz are distinguished. The components of 1_3Hz are close to the natural frequency of the body in the lateral direction, which are equivalent to the guideway wave-length of 50m_150m at the speed of 500km/h. So it is important to control guideway irregularities composed of 50m_150m wave-length. In other words, the alignment of the irregularities of which wave-length are 4_12 times as long as the unit length must be performed, in particular. 6. Consideration about the management of guideway irregularities The inspection of 150m wave-length irregularities can be executed by the guideway inspection car. By using these data, the position of sidewall can be changed as required in each unit. In the maglev system of Japan Railways, levitated vehicles run on the guideway without touching the ground coils, and sidewalls are strongly fixed on the roadbed. So guideway irregularities scarcely occur by the frequent running of levitated vehicles. However, readjusting the position of sidewalls is necessary in such cases as the earthquake occurs. So it is important to observe the transition of guideway irregularities by the inspection car periodically. In the case of ultra high speed running, the vehicle vibration is affected by aerodynamic pressure variation, especially in tunnel. Therefore, we must distinguish the vehicle vibration caused by guideway irregularities and those caused by aerodynamic pressure variation. 7. Conclusions It is difficult to directly control long wave-length irregularities of ground coils. W e solved this problem by taking the next two measures. As the first measure, we produced sidewalls of precast-concrete at a wayside factory and attached ground coils precisely on the sidewalls at the same factory. As the second measure, we set datum points at the center of the guideway accurately at intervals of sidewall unit, and adjusted each sidewall position based on those datum points. By the above control of the unit,

5 we were able to attain the target to limit irregularities to 6mm or less on 150m wavelength. It is understood that control of 50_150m wave-length irregularities is important from the evaluation of vehicle vibration data as well. It is important to observe long wave-length irregularities periodically because the infrastructure would be moved by the earthquake. The guideway inspection car was developed to cope with the above. It is possible to readjust the position of sidewalls based on datum points, obtaining the shifting quantities from the data of the inspection car. On the other hand, in the case of running at ultra high speed of 500km/h, the vehicle vibration is affected by aerodynamic pressure variation. So it is necessary to distinguish the vehicles vibration caused by guideway irregularities and those caused by aerodynamic pressure variation. BIBLIOGRAPHY 1) A.Furukawa, H.Gotoh, T.Itoh, S.Hashimoto, M.Hotta, M.Miyamoto: Construction Technology of Maglev Guideway on the Yamanashi Maglev Test Line, Proc. WCRR 97, Florence, Italy, Novenber ) K.Takeshita: Development of Maglev Guideway Inspection Cat, Proc. WCRR 97, Florence, Italy, Novenber ) K.Sakamoto, T.Noda, T.Itoh, M.Oishi: Technological Development of the Guideway in the JR Maglev System, Maglev 95, Hanover, November ) K.Sakamoto, A.Furukawa: Construction Technology of Beam Type Maglev Guideway, Quarterly Report of RTRI, Vol.37, No.2, September ) A.Furukawa, S.Hashimoto: Relationship Between Maglev Irregularity and Riding Quality, Quarterly Report of RTRI, Vol.35, No.3, August 1994.