曳引機振動量測系統之建立及其資料分析

Abstract

本文根據國際標準組織－曳引機駕駛者全身振動測量方法（ISO 5008）之規範，建立一套曳引機座椅振動加速度之量測系統，本系統同樣適用於其他田間操作機械之振動加速度之量測。座椅量測系統是利用加速規、放大器、紀錄器等儀器在實地操作實驗，紀錄振動加速度值之後，將實驗資料帶回實驗室利用頻譜儀進行1/3倍頻頻譜分析，最後用轉檔軟體將訊號轉換成美國國家標準資訊交換碼（ASCII）儲存於個人電腦，進行數據運算及統計，再與國際標準組織－全身振動量評估標準（ISO 2361-1）比較分析。 實驗結果顯示，以減少座椅振動的效果而言，在各種車況下，記憶膠棉墊、天然乳膠墊及複合乳膠墊三種坐墊比較起來，以記憶膠棉墊的表現最優，天然乳膠墊次之，複合乳膠墊表現最差。曳引機行進速度和座椅振動加速度值，並沒有直接關係，唯有在行進速度較低時，振動加速度值略為偏高。 在振動頻譜分析上，以振動頻率16Hz~31.5Hz的加速度較大，主要的原因來自於曳引機的引擎所造成。在前後、左右、上下三方向的振動加速度比較起來，以上下方向的加速度為最大，左右方向的加速度次之，前後方向的加速度為最小。實驗結果和國際標準組織－全身振動量評估標準（ISO 2361-1）比較起來，上下方向的振動量值超過四小時連續操作時間界限，建議曳引機駕駛者操作不宜連續超過4小時。

In this study, a system is developed to measure and analyze the tractor seat vibration according to the International Organization for Standardization： Agricultural wheeled tractors and field machinery－Measurement of whole-body vibration of the operator (ISO 5008). The measuring system in field includes an accelerometer, a charge amplifier, and a data recorder. The recorded data was analyzed by an 1/3－octave frequency FFT analyzer and transferred into ASCII codes by AD-1459 file converter, then the data collected were compared to the International Organization for Standardization：Mechanical vibration and shock－Evaluation of human exposure to whole body vibration (ISO 2631-1). Three different cushions were used to examine this study and the results show that the reduction of acceleration by memory collodion is the best. The correlation between the acceleration of vibration and forward speed of tractor is weak. In vibration analysis, the vibration of 16Hz to 31.5Hz is larger. The vibration in buttom to head is the largest, right to left is the second, while back to chest is the smallest. Vibration of tractor was compared to explore the limits of ISO 2361-1, it is suggested that tractor drivers not to operate the tractor for more than four hours.