机械毕业设计英文外文翻译247基于制动试验台的虚拟仪器与变频技术

附录

VIRTUAL INSTRUMENT AND FREQUENCY CONVERSION

TECHNOLOGY-BASED BRAKE TEST SYSTEM

Brake is widely useful and very important safety assuring equipment. The aim of Brake test system，which is based on visual instrument and frequency changing technology，is to integrative measure and analyze the performance and quality of the brake.This paper mainly introduces the principle，composing，function and features of the brake test system. And from the point of view of the principle of Visual Instrument （VI）technology，a test system，based on the VI and frequency changing technologies and consist of frequency changing drive and control sub-system and measuring sub-one，is constructed. With the test system the performances and braking course could be auto controlled and measured to the brakes which includes disc and drum ones. And the measuring and control software is programmed with the LabVIEW published by American NI Corporation，USA.Then data real time acquisition，processing，displaying and recording will be realized. The test system also has the functions of voltage adjusting，rotating speed control，load regulating，JC value setting，temperature

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measuring，and braking route and time memorizing and analyzing. It will be very important for meaning and exciting boosting effect to advance quality and capabilities of the brakes and the security of equipments and system which have adopt the brakes.

1 Operating principles

According to the principle of work and power，the change of kinetic energy in the moving of objects equals to the full power of the force act on the object in that process.The energy obtained by brake to be tested：

Therefore，it is feasible to use combined inertial flywheels to simulate rotating inertia of crane hoist and its transmission components to test the performance and quality of the brake. According to the moment of momentum theorem：

T b·t =J i·ω （1）

When T b is fixed，t b can be controlled through combinations between Ji and ω differently. Brake drum or plate，which will be measured，and combined inertial flywheels for loading on are driven to rotate by AC frequency conversion motor （or DC one，which will not be

dealt with in this article carefully）. According to the principles

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shown in the formula （1），we can simulate actual processes of brakes fitted on lifting and transport machineries，engineering ones，mining ones and construction ones by changing the technical specification duty JC，the flywheel's inertial moment Ji and motor's rotational speed ni.When detected brakes work in simulation cycle and brake repeated，infrared thermoscopes and torque sensors，and other sensors will record braking shown in the heat，braking torque，braking time and brake speed parameters.

2The composition and structure of the brake test system

This test system is intended to achieve the performances of drum and disc brakes and has following functions：

（1）Brake replacement

According to different type of brakes the corresponding base will be chosen and brake position could be adjusted using electric slide test-bed；

（2）Multi-level loading

We can simulate the actual loading on brakes in a crane with different combined flywheels. The test system adopts manual hydraulic system composed by a three-position four-way

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