Many kinds of nozzle-flapper type pneumatic pressure control proportional valves are in use. This paper describes the results of experiments and theoretical analyses regarding the characteristics of the valve pneumatic circuit. It was found that the characteristics of the output pressure versus the nozzle flapper clearance has a switching point as a relay. As it has a direct relation with valve linearity, this phenomenon has been studied experimentally and theoretically for various valve parameters. A way for choosing the optimum nozzle-flapper clearance is suggested from the results presented in this paper.

View full abstract

In pneumatic systems, the condensation of water resulting from variations in air temperature leads to a reduction in lubrication, erosion and freezing of the components, and which leads to trouble. With growing demand for improving the characteristics and reliability of a pneumatic system, more attention has been given to this problem. Therefore, in a previous study (1st report), we investigated the features of the condensation, the conditions of generation and the influencing factors by numerical simulation using a homogeneous condensation theory. In this paper, the condensation of water in a pneumatic system is investigated. First, the surface tension coefficient, which has a great influence on results of simulation regarding the generation of condensation is evaluated using the measurements of the degree of supersaturation when the condensation occurs. Next, the critical curves for the condensation which depends on the initial conditions (initial temperature, pressure and humidity of the air in the container) are found, and the validity of the homogeneous condensation theory is demonstrated by comparing the results with the simulated ones.

View full abstract

A difference of 2% or more in efficiency as determined by the usual mechanical testing method and thermodynamic method without heat transfer from the pump casing was demonstrated in the previous study.Heat accumulation in the glass wool fixed on the inner wall of the heat insulation box made of foam-styrol plate enclosing the test pump casing and thermometer setting block at the pump inlet and outlet may have been the reason for this.
The present experimental apparatus was improved ; the glass wool was removed, and a large insulation box covering the pump casing together with the thermometer setting block was made so as to control air temperature in the vicinity of the pump casing. Efficiency assessed by the present method was virtually the same as that by the mechanical testing method.
Air temperature surrounding the thermometer setting block affected oil temperature measured by the sensor in the block. The effect of air temperature near the stem of the thermometer was thus investigated, and the actual oil temperature at the pump inlet and outlet was determined. The effect of air temperature surrounding the inlet block on oil temperature distribution was also found. The oil temperature in the inlet rubber hose was not affected significantly by air temperature surrounding the hose.

View full abstract

A plastic hermetic seal (PHS) was developed which is practical used up to operating pressure 35MPa.
This PHS was experimentally confirmed to have superior pressure endurance and high reliability compared with conventional glass hermetic seals.
By elasto-plastic analysis, deformation of metal flow and subsequent plastic compressive force were analyzed which determine the performance of PHS. The effects of thickness of base metal and clearance of plastic and base metal were clarified.
Also, an approximate evaluation equation of the extraction force of PHS was developed and compared with actual values.
Many kinds of environmental tests of PHS were conducted. This PHS was proven to have a pressure endurance of 500-600 PMa and long time endurance for oil immersion at temperatures up to 100°C.

View full abstract

This paper describes a voice-controlled support instrument with voice recognition LSIs and a computer to support nurses. Because the technique of voice recognition is in its infancy, use conditions are limited, such as only an isolated word is recognized in some recognition methods, without high recognition rate, etc. In this paper, it was attempted to achieve recognition results by a majority decision method using plural voice recognition LSIs to improve the recognition rate. And it is devised that the voice recognition system can recognize plural control commands in succession. In order to provide support friendly like human, making the bolster move like the motions of human body with respect to smoothness by the voice command, a soft control method is planned. And it was confirmed that the support car's bolster can move accordingly by experiments.

View full abstract