非対称シリンダを有する電気油圧サーボモータの周波数特性 ＩＩ 実験解析

Abstract

In a previous study, the authors derived the basic equations for an electrohydraulic servomechanism with a nonsymmetrical cylinder and obtained numerical results. On the other hand, an approximate solution was developed by assuming that the load pressure is nearly constant during the half period. In this paper, the experimental analysis was carried out using a servomechanism with a nonsymmetrical cylinder. The electrohydraulic servovalve used was the 3F-60L-30 type manufactured by Tokyo Seimitsu Sokki Co., Ltd., whose rated flow rate is 60 L/min and rated maximum current is 30 mA. Source pressure was kept at 10 MPa, and input frequency was varied over a range of 2-30 Hz. The experiments were carried out at currents of 5, 10, 15 mA and with cylinder area ratios of 1.0, 0.76, 0.48.0.195. Three kinds of loads were used: The mass of the inertial load was 50 kg and was borne by the angle flat cage type bearing with very little friction. A viscous load was created by laminar flow resistance through a capillary tube, whose coefficient was 9.8 N·s/cm. The coefficients of the elastic load were 490 and 754 N/cm. Experimental results were compared with the approximate solutions obtained in the 1st report, and a good agreement was obtained. The following conclusions are drawn from this study: The approximate equations are very useful in predicting the frequency characteristics and the input shift. Consequently, it would be possible to eliminate the nonlinearlity of the system by inserting a minor feedback loop and modifying the input current to the servovalve with the input shift.