This paper reports a novel driving method for particle-excitation flow control valve. The valve that we have designed in previous reports can control air flow continuously with small size and light weight. Because the valve conditions air flow, using particle excitation by piezo vibration, the valve has potential for high response. However, in previous model, the vibration direction is opposite to air flow direction and a large scale vibration is necessary to open the valve. In this report, to decrease necessary vibration scale, we design novel driving mechanism using torsional vibration. The method generates vibration that is perpendicular to air flow by torsional vibration. First, we explain the designed mechanism and calculate the vibration scale to open the valve. And we design a prototype that can generate torsional vibration to check the mechanism. Additionally, we measure the vibration scale at valve opening condition in experiment and compare calculated and experimental results. Through this study, we show the advantage of the mechanism.
For agricultural tractor, these two performances have been very important; high efficiency and maneuverability because the operator has increasingly required the fewer fuel consumption and easier and more precise control of the tractor. Generally speaking, hydro-mechanical transmission (HMT) is well known for the high efficiency level and the step-less variable speed. However, HMT is hydraulic powered system then hydraulic noise may more often occur than the pure mechanical transmission.
Therefore, this paper shows how to predict the sound pressure level with only using the design parameters of HMT and transmission assembly parts. 1-D hydraulic circuit simulation model and 3-D FEM model of HMT have been developed, and the simulated results of the sound pressure level has been calculated. Moreover, the calculated sound pressure level has been validated by the actual measured data and the cause of prediction error has been found. These all results suggest the possibility that the hydraulic noise can be reduced in an optimal way at the design process, without any prototype testing.
One of the positioning methods in vertical direction of machine tools, a hybrid electric-pneumatic ultra-precision vertical positioning device has been developed and utilized. In this method, because the weight of the stage is supported by the pneumatic pressure of the balancing cylinder, the linear motor can drive the stage motion without so much affected by the weight of the stage. Therefore, lower electric energy consumption, less heat generation, higher power and speed, can be expected with the linear motor. However, hybrid electric-pneumatic ultra-precision vertical positioning device has a drawback. When the tool change occurs, the total weight of the stage changes. Then the pressure in the balancing cylinder should be adjusted accordingly. But the pressure adjustment takes a bit of time with the conventional method that uses a diaphragm type pressure regulator. In this paper, in order to enhance the performance of the hybrid electric-pneumatic ultra-precision vertical positioning device, a new pressure adjustment method in the balancing cylinder when the tool change occurred is proposed. The proposed method utilizes a feed-forward control and a high precision quick response pneumatic regulator (HPQR) that was developed in our previous research. By the experimental results using a hybrid electric-pneumatic ultra-precision vertical positioning device, the validity of the proposed control method is evaluated and its superiority is indicated.
Using isothermal discharge is a new experimental approach to determine the flow-rate characteristics of compressible fluids, which has been registered as JIS B 8390-2 by Japanese Industrial Standards Committee. However, it is not clarified yet that to what extent the ambient atmospheric pressure affects the sonic conductance and critical pressure ratio measured by this method. In this study, a chamber with a sufficiently large capacity was attached to the downstream outlet, and a pseudo atmospheric pressure control device with an ejector was used to adjust the downstream pressure. Experiments were carried out with different values of downstream pressure lower than the ambient atmosphere. It was observed that the sonic conductance keeps constant in the choke range and is not influenced by the downstream pressure. Moreover, the variation in the critical pressure ratio is not significant under the experiment conditions.