Study On Suspension Constructs And Parameters Of Driving Equipment In Locomotives

With railway vehicle speed increasing in China, the some locomotives don't present very well in the dynamical behavior in the lateral direction. The key problems present should be attributed to the driving equipment suspensions in the locomotives. Although flexible driving equipment suspensions, namely, driving motors are suspended in the bogie frames with desirable flexibility, have been applied to advanced locomotives in many countries, the further studies on the suspension systems have not been carried out so far. Regarding the dynamical characters of structure of the suspension systems are still out of acquaintanceship in China. By and large, abroad 200km/h locomotives have been equipped with four axles (i.e. 2Bo). China is now facing a complicated technique challenge in development of 200km/h locomotive of six axles (i.e. 2Co), which is also one of the present pressing tasks to meet the need of fast development of railway systems in China. However, the key problem to be solved is to clear the characters of the flexible suspension parameters and the mechanism of the driving equipment in the project.This thesis established a simplified model consisting of 3 rigid bodies for the bogie with the flexible suspension driving equipment. Considering the different axles, structures and parameters for the bogie, the dynamical behavior of the bogies was analyzed in detail. Through the dynamics analysis, the mechanism of the flexible driving motor suspension was basically clarified. The natural frequencies of the drive are changed by altering its longitudinal and lateral stiffness in the bogie frame to avoid the wheelset hunting frequencies, thereby the dynamic mass and the inertia of the flexible suspension driving equipment are decoupled from the bogie frame and the wheel set, the inertial movement transfer between the driving system and the bogie frame or the wheelset is restrained.Based on a time domain nonlinear analysis method considering an input of the stochastic irregularity of track, a commercial software SIMPACK available for establishing complete models of locomotives was employed to validate the results obtained by the current model. The flexible driving suspension asks the longitudinal and lateral stiffness between the drive and the bogie frame ranged from 0.01 to 0.09 MN/m, so pendular way was adopted in the structure design of the driving suspension system. By means of the pendulum gravitational rebound stiffness as the equivalent stiffness, Its sufficient stiffness bound was offered in order to meet theneed of the flexible driving suspension even if the length of pendulum ranging from 0.2m to 0.7m.The dynamic behaviors of the locomotives with rigid and flexible driving motor suspensions were compared in the detailed dynamics analysis. It was found that when the locomotive runs on a tangent track or a curved track with large radius upwards of 140 km/h, using the flexible suspension can reduce the lateral wheel/rail forces much. The lateral riding quality of the locomotive and the work condition of the driving motor ameliorate. The locomotive dynamic behavior is lower sensitive to the track conditions and the concerned parameters variation. Especially in the running at higher speed, the locomotives with flexible motor suspension have the more advantages than that with relative rigid suspension for the driving motor.The dynamic behavior of serious of 200km/h locomotive with 2Co axles was investigated in detail. For such locomotives, the rigid and flexible motor suspensions with a "face to back" or "back to back" setting of motors were, respectively, considered. Through the investigation, it was found that the flexible suspension with "back to back" setting of motors has more advantages. Also it is pointed out that a suitable driving stop clearance has to be set to ensure good dynamic performance on sharp curved lines. In some special work situations, such as traction, braking and passing through periodical irregularity track etc, the influence of traction rods which act at the middle or two ends of the car body on the locomotive behavior were analyzed. The thesis suggested that the dynamic response of the locomotives should be investigated under an excitation of track irregularity with sensitive periods even though the locomotives pass through tangent tracks or curved tracks with large radii. Finally, this thesis discussed the motor suspension stiffness of an axle-mounted locomotive, the driving-braking-unit suspension stiffness and the coupling damper characteristic of a power car with the unit suspended between the car body and bogie frame. The trend of numerical results is in good agreement with the field test results.The numerical simulation of this thesis was carried out by means of SIMPACK. Many non-linear factors and operation conditions are of the locomotives were taken into consideration, the manifold locomotives with different suspension systems and their simplified models were analyzed and compared in detail. The results obtained will have some reference value and engineering meaning to the designs and analyses of Chinese locomotives.