Papers by Author: Jian Ruan

Abstract: The mechanical part of the 2D servo valve is mainly a hydraulic servo screw mechanism, by which the rotary motion of the spool is turned to linear sliding. A step motor is utilized to rotate the spool and functions as the electrical-to-mechanical transformer. For studying the different influences of 2D valve's pilot circular and full arch structure on its dynamic characteristics of servo screw mechanism, a step response and sine response experiment device was designed, and the experiments were done. The experimental results show that the full arch structure type step response time is about 1.6 ms (abbreviation of millisecond), the circular type about 3ms, proved that the full bow structure can significantly improve the dynamic characteristic of servo screw mechanism, it is also be proved by sinusoidal frequency response experiments.

Abstract: Conical valve’s spool-seat contact pairs is consisted of two surfaces of different curvature radius, and form closed circular contact line. It can be considered as the model of elastic hemi-space contact by the Hertz Theory. The numerical simulation and experiment show: The model is suitable for the analysis of conical valve’s spool-seat contact pairs. The conical valve’ sealing performance is very credible and its performance is very good. Maximum stress is smaller than allowable stress of the seat’s material. The consistency of experiment and simulation proves the validity and practicability of the hemi-space contact model of the valve’s spool-seat contact pairs.

Abstract: A new type of squeeze film damper (SFD) is designed to reduce spool’s impact and vibration which happen in the two-stage larger flow rate high-speed on/off valve with the 450 L/min flow rate and 8ms turn-off time, the valve’s sealing performance、reliability and service life improve largely, and the valve’s response speed doesn’t drop. The simulated and experimental results show: The damper has optimum buffering performance when oil film thickness is 0.1mm, and the spool closing process approach ideal state. The valve will has a great potential application in the powerful occasions because of it's perfect performance: larger flow rate、fast response and novel damper.

Abstract: A double degree of freedom valve was designed. It has the functions of the radial direction rotary motion and the axial translation motion. In the electro-hydraulic vibrator, 2D valves are used to control hydraulic cylinder to achieve high-frequency vibration. The vibration frequency and amplitude are controlled by the speed and axial displacement in the spool valve core respectively. The vibration-exciting force signals and the displacement signals are obtained by adapting card under Delphi development. The real excited waveforms are analyzed, compared and studied.

Abstract: Since conventional electro-mechanical converter of 2D digital valve had limitations of large inertia and low dynamic response, a novel low inertia rotary electromagnet with coreless rotor structure was proposed. The axial magnetic flux generated by permanent magnet and the radial magnetic flux generated by excitation coils were superimposed and then electromagnetic torque was produced to drive rotor to track the input signal simultaneously. Based on the approach of 3D finite element electromagnetic field simulation, the influence of key structure and operating parameters such as excitation ampere turns, working air gap, tooth height, tooth width and wall thickness of coreless rotor on torque-angle characteristic was discussed. The result obtained provides a certain reference value on the structural optimization of electro-mechanical converter of 2D digital valve.

Abstract: A scheme of the separate control technique of electro-hydraulic vibrator is proposed, in which symmetrical hydraulic cylinder is controlled by a parallel mechanism of a two-dimensional valve (named as 2D valve) and a parallel servo valve. The working frequency and vibration amplitude of the electro-hydraulic vibrator are dominated by the rotary speed and the sliding displacement of the spool of the 2D valve respectively, and the vibration central piston is controlled by the sliding displacement of the spool of the parallel servo valve. This paper analyzes the relationship between vibration characteristic values and control parameters using the analytic method based on the hydrodynamic control theory. The experimental system is built to verify that the theoretical analysis is consistent with measured results.

Abstract: For precisely controlling the bias position of an electro-hydraulic vibration exciter, a scheme of a parallel mechanism of a two-dimensional valve (2D valve) and a servo valve is proposed. In the low frequency section, the mathematical model of the electro-hydraulic vibration exciter is simplified reasonably. A vibration central position is first analytically derived by assuming that 2D valve connected with parallel valve is equivalent to a single slide valve with neutral positive opening and the time-average flow rate through them is identical. And then the analytic solutions to excited waveforms superimposed on the bias position are further obtained. Finally, the experimental system is built to verify the theoretical analysis. The results reveal that this approximate analytical solution could describe excited waveform of bias control on electro-hydraulic vibration exciter. When the opening area of 2D valve is a constant, the bias position follows a linear relation with the throttling areas of the parallel valve which is no more than the maximum position. The excited waveform is close to the sinusoidal waveform. At the same opening area of the parallel valve, the bias position is reduced as the area coefficient of 2D valve increases. The proposed scheme not only ensures the frequency and the amplitude to be controlled independently but also the bias position to be adjusted precisely.

Abstract: In grinding viscous materials, such as stainless steel, aluminum and many polymeric materials, the application of a dither on the workpieces proves to be an effective way to enhance the quality of surface finish. A linear stepper motor is utilized for this purpose. By means of the PWM control to the adjacent phase coils, the linear stepper can drive the sliding table to make reciprocating motion and also to produce a desired dither signal, while the grinding is undertaken to the attached workpiece. In this paper, a linear stepper motor is introduced to drive the sliding table and a modulated control strategy is used to control the linear stepper continuously, which also generates an additional dither on the sliding table and the attached workpiece. The dither amplitude can be adjusted by means of the modulated frequency. Experiments are designed to measure the practical dither signals and to verify the effectiveness of improving surface finish quality using a dither. It is demonstrated by both theoretical and experimental results that by means of proposed table drive, a rather wide band of dither signal can be acquired and can meet the most demand of viscous material grinding.