Measuring and testing – Dynamometers – Responsive to force
Patent
1993-11-15
1995-07-25
Chilcot, Jr., Richard E.
Measuring and testing
Dynamometers
Responsive to force
7386259, G01L 100
Patent
active
054351910
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a natural frequency measurement apparatus and a tension measurement apparatus using the same. More specifically, the present invention relates to an apparatus for measuring a natural frequency indicative of the state of an object to be measured and also a tension measurement apparatus for calculating the tension of an object to be measured, such as a belt or like, supported between two points based on the measured natural frequency thereof.
BACKGROUND OF THE INVENTION
Belt system has been used widely for transmitting rotational forces and also transporting articles. In such belt system, if a tension of a belt passing round pulleys is not set to a predetermined value, it results in a failure of efficient transmission of torque from one pulley to another or failure of transporting of articles in a stable state. Further, if the belt is not given a tension matched to its own characteristics, its lifetime is shortened to increase the frequency of its replacement.
To solve the above problems, a suitable method of measuring the belt tension is necessary. As a belt tension measurement method, it is known that a natural frequency of a belt passing round pulleys is detected by giving vibrations to the belt and is utilized to calculate the belt tension based on a predetermined formula of calculation. Usually, the natural frequency noted above is measured by surveying a distribution of frequencies by using a displacement measuring apparatus and a frequency analyzer.
However, since the prior art natural frequency measurement apparatus uses a displacement measurement apparatus and a frequency analyzer, the natural frequency measurement apparatus and the tension measurement apparatus for detecting the tension of the object according to the natural frequency thereof are complicated and inevitably large in scale.
An object of the invention is to provide an apparatus for measuring the natural frequency of an object and/or a tension measurement apparatus for detecting the tension of the object such as a belt by utilizing the measured natural frequency, the apparatus having simplified structures.
SUMMARY OF THE INVENTION
The invention has the following features (a) to (d). vibrations of an object to be measured (in general, non-contact vibration detection means), period measurement means for measuring the period of a vibration waveform detected by the microphone for each cycle of the waveform, means for detecting a wave group consisting of successive waves, the measured period variation of which are within a predetermined tolerance, and natural vibration data calculation means for calculating either the period or the frequency of a representative waveform in the detected waveform group. stretched between two points such as pulleys, and the measurement apparatus further comprises means for calculating the tension of the body according to the period or frequency calculated by the above natural vibration data calculation means and using a predetermined calculation formula. object to be measured, means for measuring the frequency of the vibration waveform detected by the microphone for each cycle, means for detecting a waveform group consisting of successive waveforms, the measured frequency variation of which is in a predetermined range, and means for selecting a representative frequency of the waveform group. stretched between two pulleys, and the apparatus further comprises means for calculating the tension of the body according to the representative frequency of the waveform group and by using a predetermined calculation formula.
When a belt or like object stretched between two points is given a shock for vibration, it is initially vibrated in an irregular waveform containing various harmonic components and shock components. With the lapse of time, however, it becomes vibrating with a regular waveform natural to it, and a basic waveform at a natural frequency mainly remains.
The present invention is predicated in experimental confirmation of such phenomena, and with the above f
REFERENCES:
patent: 4565099 (1986-01-01), Arnold
patent: 4692615 (1987-09-01), Mensah et al.
patent: 4928538 (1990-05-01), Burdess et al.
patent: 5251491 (1993-10-01), Nakaoka et al.
Biegel R. L.
Chilcot Jr. Richard E.
Kawach Kenkyusho Co., Ltd.
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