The pressure level of pneumatic devices is not only above atmospheric pressure but also below atmospheric. In particular, devices operating at low pressure and middle pressure vacuums are essential. However, vacuum pressure systems are not energy saving because of their low energy efficiency.
This study proposes a new type of positive and negative pressure source with an unload circuit. This new pump could generate positive pressure from the exhaust side and vacuum pressure from the intake side. However, if it generates both pressures simultaneously, the load of the pump increases. This circuit is equipped with an unload mechanism that can control the level of the positive and vacuum pressures by control valves. As a result, the energy consumption at low level when pressure is produced using this system is smaller than that using the usual two pumps separately. The proposed system has advantages in energy efficiency and space availability.

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In this study, a newly designed electro-magnetic proportional actuator composed of an armature and stator with multi convex teeth to control oil hydraulic valves was constructed and tested. Each of the convex teeth forms a magnetic pole, and when multiple magnetic poles produce a force simultaneously, a large thrust force is generated in the actuator. The dimensions of this actuator is60mm square, by101mm length. As a result of measurement of characteristics of this actuator, it became clear that its thrust force was constant within1mm of the armature stroke, producing about300N at electric power consumption of15W.
When the rise in the coil temperature of the actuator was measured, it became clear that the allowable maximum electric power consumption was 15W when the outer surface of the actuator is open to the atmosphere. Thrust force of this actuator is about 2.5 times as large as that of conventional proportional solenoids and linear motors of the same size and power consumption. In addition, the actuator has the potential to generate three times or more thrust force compared with conventional-proportional solenoids and linear motors by increasing the winding number of the coil and examining the shapes and sizes of the convex teeth and magnetic circuit.

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This paper presents an alternative method for obtaining the flow rate characteristics of all types of pneumatic components. The proposed method determines flow rate characteristics by measuring pressure response in an Isothermal Chamber during discharge into the atmosphere. Expansive flow rate expression is used to satisfy various pneumatic components including valve, silencer, speed controller, etc. The paper also establishes a practical calculation technique for flow rate characteristics. Measurement results show the effectiveness of the proposed method. In addition, the proposed method is able to achieve a shorter measurement time and less air consumption than the ISO discharge method. The proposed method has the same precision as the ISO discharge method but it offers higher productivity.

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To accurately calculate the transient response in laminar flow, it is necessary to use frequency-dependent friction considering the velocity distribution. We developed a high speed and accurate computing method for simulating the friction in transient laminar pipe flow in the method of characteristics. This method consists of approximating W. Zielke's weighing function as a sum of impulse responses of first order lag systems. This method is normally well-understood. However, it is not usually applied to other calculating methods except the method of characteristics. Because the method of characteristics has a limit to its unique relation between discrete time and space, it is difficult to apply it to complicated pipe systems that include branches. In this paper, we propose application of the high speed and accurate calculating method of frequency-dependent friction to the CIP method. This proposed method has a higher flexibility than the method of characteristics in terms of the relation between discrete time and space. We measured transient response in the single, series, branch and complex pipelines. The results of the numerical calculation agree well with that of the experiment. These results show the effectiveness of the proposed method.

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