ELECTROMECHANICAL ACTUATOR FOR ACTIVE SUSPENSION OF A RAIL VEHICLE

ELECTROMECHANICAL ACTUATOR FOR ACTIVE SUSPENSION OF A RAIL VEHICLE

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263 ELECTROMECHANICAL ACTUATOR FOR ACTIVE SUSPENSION OF A RAIL VEHICLE Kjellqvist P., Ostlund S., Carlsson F. Royal Institute of Technology, Sweden ABSTRACT An active lateral suspension of rail vehicles significantly increases passenger comfort. It also improves efficiency of the rail operation since a wider car body can be used. The paper describes the design of an electromechanical lateral suspension based on a permanent magnet machine and a roller screw. Both mechanical and electrical characteristics are examined and the feasibility of the system is shown. INTRODUCTION The use of wider car bodies is an important parameter in order to increase the efficiency of rail traffic operations, Ostlund (1). A wider car body (3.3-3.5 m), that allows comfortable 2+3 seating in second class, substantially lowers cost per seat for capital, maintenance and operation. The concept of wider car bodies is being exploited in Sweden and is considered as an attractive and efficient alternative of several railway operators. This need is not only apparent for extra-ordinary wide car bodies, but also when an ordinary train cross section has to fit close structure gauges on different railways; well-known examples are the strict application of UIC SOS and British standards. A wide car body makes it necessary to limit lateral motions of the cii~ body suspension to a minimum. However, to achieve an acceptable ride quality of fast trains, the passive suspensions of today require some SO- 70 mm of lateral play in each direction. If the lateral motions in these suspensions could be reduced with, roughly, SO % the width of the car body could be increased by SO-70 mm. In critical cases there is consequently need for a device which are able to limit the lateral travel of the suspension, while it is also able to give a good suspension from track irregularities. Such an active device used for limitation of lateral motions is often called a Hold Off Device (HOD). Pneumatic and hydraulic devices are known, but are used just to a limited degree on special trains. A pneumatic HOD is quite slow and requires an extra- ordinary high-pressure air supply. Introduction of hydraulics is generally not desirable on trains, even on new tilting trains the actuators now are under transition to electrical devices. Electrical actuators do not need any extra hydraulic or pneumatic supply and are expected to be easy to maintain. However, up till now there is no electrical device suitable for active suspensions in HOD applications. This paper examines the characteristics of a possible electromechanical actuator for a Hold-Off Device application. The characteristics are also expected to allow operation as an active lateral suspension of a rail car. At fnst the mechanical requirements of the actuator are described. It is followed by a preliminary electric design that shows the feasibility of the device.
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This note was uploaded on 05/08/2011 for the course MECHANICAL 203 taught by Professor Krishna during the Spring '11 term at Akademia Ekonomiczna w Poznaniu.

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ELECTROMECHANICAL ACTUATOR FOR ACTIVE SUSPENSION OF A RAIL VEHICLE

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