7.　Auxiliary Machinery & Outfitting Works

　

In the section of auxiliary machinery & outfitting works in 1998, the world's smallest turbo-compressor in the world, the noise reduction of swash plate type axial piston pumps, the dynamic simulators for an absorption refrigerator and so on were studied and developed.

The further details of these are as follows.

　

7.1　Development of the Smallest Turbo-Compressor in the world¹⁾

Ishikawajima-Harima Heavy Industries Co., Ltd. has marketed the super small turbo-compressor, Tx150, based on a new design concept, and has now developed a smaller type with a capacity of 75kW, Tx-mini, which has the world's smallest capacity of a standard type. The main specifications of Tx-mini series are shown in the Table 7.1.

　

Table 7.1 Specifications of Tx-mini series

notice: There are 2 types of Tx-mini with delivery pressure 0.59 MPa and 0.88 MPa as optional series.

　

This standard typed compressor Tx-mini was not only minimized according to the main design concept of the Tx150 but also improved all the more. The minimized impeller has been designed to maintain the high efficiency of the compressor by the use of the computational fluid dynamics analysis. The high performance 3-dimension typed impeller is made of a titanium alloy. The minimization of the impeller required the rotor speed of 109000rpm. Therefore, the new bearings and gears has been specially designed and made to withstand the speed and to be very reliable. As a result, the Tx-mini achieves the low vibration and the stable operation even at the high speed revolution. The Tx-mini has adopted the following system for this high speed revolution of the rotor. As the inverter starter raises a frequency of the electric power source from 50 or 60Hz to 120Hz, a high speed 2 poles 3 phases' induction motor rotates at 7200rpm. This inverter has been developed specially for the compressor. The motor rotates the rotor with the impellers at 109000rpm through the single stage multiplying gear. (See Fig.7.1) By the use of the frequency control by this inverter starter, the revolution control of the rotor becomes easy in spite of the change of the motor power caused by the change of atmospheric temperature. Therefore this system has higher efficiency than the current system that controlled the inlet vane.

　

(a) Single-stage multiplying gear method using inverter starter (Adopted)

(b) Double-stage multiplying gear method (Idea only)

Fig. 7.1 Stepup speed method for gears

　

So far the screw compressors and the reciprocating compressors have been used mainly in thus small capacity region. This turbo compressor appears there. It is able to make easily the compressed air without lubricating oil. We can select the best compressor widely for each purpose of use.

　

7.2　Study on Noise Reduction of Swash Plate Type Axial Piston Pumps²⁾

Mitsubishi Heavy Industries, Ltd. has studied a theoretical procedure for predicting the pump noise spectrum in the preliminary design stage. This method consists of the following three steps. (1) Simulation analysis of the exciting force due to the pressure. (2) Estimation of the vibration and noise properties of the pump case using FEM. (3) Finding the pump noise spectrum by combining the exciting forces and vibroacoustic characteristics of the structure. Through this method they have made the noise reduction typed pump.

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