The resistance torque of a piston stage II com- pressor generates strenuous fluctuations in a rotational period, and this can lead to negative influences on the working performance of the compressor. To restrain the s...The resistance torque of a piston stage II com- pressor generates strenuous fluctuations in a rotational period, and this can lead to negative influences on the working performance of the compressor. To restrain the strenuous fluctuations in the piston stage II compressor, a variable duty-cycle control method based on the resistance torque is proposed. A dynamic model of a stage II com- pressor is set up, and the resistance torque and other characteristic parameters are acquired as the control tar- gets. Then, a variable duty-cycle control method is applied to track the resistance torque, thereby improving the working performance of the compressor. Simulated results show that the compressor, driven by the proposed method, requires lower current, while the rotating speed and the output torque remain comparable to the traditional vari- able-frequency control methods. A variable duty-cycle control system is developed, and the experimental results prove that the proposed method can help reduce the specific power, input power, and working noise of the compressor to 0.97 kW.m-3.min-1, 0.09 kW and 3.10 dB, respectively, under the same conditions of discharge pressure of 2.00 MPa and a discharge volume of 0.095 m3/rain. The proposed variable duty-cycle control method tracks the resistance torque dynamically, and improves the working performance of a Stage II Compressor. The pro- posed variable duty-cycle control method can be applied to other compressors, and can provide theoretical guidance for the compressor.展开更多
The paper presents the methodology and results of measurement designed to determine the effect of the rolling element separator （cage） at the frictional moment in ball bearings, The measurement was carried out on fo...The paper presents the methodology and results of measurement designed to determine the effect of the rolling element separator （cage） at the frictional moment in ball bearings, The measurement was carried out on four groups on bearing with different cages. Measurements were carried out on torque-meter STPM, a device that has been designed and manufactured at Kielce University of Technology. The measurement results showed that the type of cage used in ball bearings has a significant impact on the frictional moment. In addition, the results also confirm that the size of the curvature ratio and the accuracy of the races shape have a significant impact on the frictional moment.展开更多
基金Supported by National Natural Science Foundation of China(Grant No.51275452)Zhejiang Provincical Natural Science Foundation of China(Grant No.LY14E050021)Commonweal Technology Project of Science and Technology Department of Zhejiang Province,China(Grant No.2015C31071)
文摘The resistance torque of a piston stage II com- pressor generates strenuous fluctuations in a rotational period, and this can lead to negative influences on the working performance of the compressor. To restrain the strenuous fluctuations in the piston stage II compressor, a variable duty-cycle control method based on the resistance torque is proposed. A dynamic model of a stage II com- pressor is set up, and the resistance torque and other characteristic parameters are acquired as the control tar- gets. Then, a variable duty-cycle control method is applied to track the resistance torque, thereby improving the working performance of the compressor. Simulated results show that the compressor, driven by the proposed method, requires lower current, while the rotating speed and the output torque remain comparable to the traditional vari- able-frequency control methods. A variable duty-cycle control system is developed, and the experimental results prove that the proposed method can help reduce the specific power, input power, and working noise of the compressor to 0.97 kW.m-3.min-1, 0.09 kW and 3.10 dB, respectively, under the same conditions of discharge pressure of 2.00 MPa and a discharge volume of 0.095 m3/rain. The proposed variable duty-cycle control method tracks the resistance torque dynamically, and improves the working performance of a Stage II Compressor. The pro- posed variable duty-cycle control method can be applied to other compressors, and can provide theoretical guidance for the compressor.
文摘The paper presents the methodology and results of measurement designed to determine the effect of the rolling element separator （cage） at the frictional moment in ball bearings, The measurement was carried out on four groups on bearing with different cages. Measurements were carried out on torque-meter STPM, a device that has been designed and manufactured at Kielce University of Technology. The measurement results showed that the type of cage used in ball bearings has a significant impact on the frictional moment. In addition, the results also confirm that the size of the curvature ratio and the accuracy of the races shape have a significant impact on the frictional moment.
