Now the internal combustion engine mini-tiller has become the main and indispensable agricultural machinery in vast hilly and mountainous areas of Southwest China.However,its intense vibration may pose a big threat to...Now the internal combustion engine mini-tiller has become the main and indispensable agricultural machinery in vast hilly and mountainous areas of Southwest China.However,its intense vibration may pose a big threat to operators.As a countermeasure to the tiller vibration,a new type of electric mini-tiller powered with a group of lithium battery and a brushless DC motor was developed.The vibration signals at the handle of the tiller were tested under 6 conditions as follows:the tiller was under states of static and working in the field,at slow,medium and rapid speed,respectively.The signals were processed by means of the time domain eigenvalue analysis and the frequency spectrum analysis.The results show that with the electric motor rated speed increased from 95 to 140 r/min under static conditions,the RMS values increased 122.54%,and with the forward speed increased from 0.30 to 0.80 m/s under working conditions,the RMS values increased 201.78%.When the tiller was working,the first order vibration frequencies were 25.99 Hz,26.99 Hz and 28.99 Hz at slow,medium and rapid speed respectively,all not within 37.50-65.00 Hz,the sensitive range of human hands to the vibration frequency.In addition,according to the results of hand transmitted vibration analysis,it can be found that compared with operating the internal combustion engine mini-tiller under the same working condition,the onset of vibration-induced white finger can be delayed for 3.70 years to 10.20 years by operation of the new electric tiller.展开更多
Intense vibration happens at the handle of the mini-tillers that abundantly used in mountainous and hilly areas of southwest China.It is absolutely essential to probe into the vibration characteristics and factors why...Intense vibration happens at the handle of the mini-tillers that abundantly used in mountainous and hilly areas of southwest China.It is absolutely essential to probe into the vibration characteristics and factors why handle of the tiller vibrates violently.Therefore,the vibration acceleration signals of a mini-tiller’s handle and engine cover were tested under the following four conditions:the engine being idle,racing at medium and high speeds,and the tiller working in the field with high engine speed.The signals were processed by means of the time domain eigenvalue analysis and the frequency spectrum analysis.The results showed that when the tiller was under static condition,with increase of the engine speed,the handle vibration decreased in the vertical direction,increased in the fore-and-aft direction and had marginal changes in the left-to-right direction.When the tiller worked at high engine speed,the handle vibrated most violently in the fore-and-aft direction,while the vibrations at the engine cover and handle decreased substantially in each direction,compared with the static conditions.Rotary blades cutting soil increased the damping of the whole machine so as to reduce the vibration at the handle and the engine cover,but the handle vibration was still violent.When the tiller worked,that soil absorbing energies of some frequencies led to the first order unbalanced inertia force of the engine becoming the main reason why handle vibrated intensely.展开更多
基金supported by the Special Projects of Generic Key Technology Innovation in Chongqing's Major Industries(csct2015zdcy-ztzx80003)the Scientific Research Innovation Projects for Graduate Student of Chongqing(CYB17071).
文摘Now the internal combustion engine mini-tiller has become the main and indispensable agricultural machinery in vast hilly and mountainous areas of Southwest China.However,its intense vibration may pose a big threat to operators.As a countermeasure to the tiller vibration,a new type of electric mini-tiller powered with a group of lithium battery and a brushless DC motor was developed.The vibration signals at the handle of the tiller were tested under 6 conditions as follows:the tiller was under states of static and working in the field,at slow,medium and rapid speed,respectively.The signals were processed by means of the time domain eigenvalue analysis and the frequency spectrum analysis.The results show that with the electric motor rated speed increased from 95 to 140 r/min under static conditions,the RMS values increased 122.54%,and with the forward speed increased from 0.30 to 0.80 m/s under working conditions,the RMS values increased 201.78%.When the tiller was working,the first order vibration frequencies were 25.99 Hz,26.99 Hz and 28.99 Hz at slow,medium and rapid speed respectively,all not within 37.50-65.00 Hz,the sensitive range of human hands to the vibration frequency.In addition,according to the results of hand transmitted vibration analysis,it can be found that compared with operating the internal combustion engine mini-tiller under the same working condition,the onset of vibration-induced white finger can be delayed for 3.70 years to 10.20 years by operation of the new electric tiller.
基金the Natural Science Foundation of China(No.31271610).
文摘Intense vibration happens at the handle of the mini-tillers that abundantly used in mountainous and hilly areas of southwest China.It is absolutely essential to probe into the vibration characteristics and factors why handle of the tiller vibrates violently.Therefore,the vibration acceleration signals of a mini-tiller’s handle and engine cover were tested under the following four conditions:the engine being idle,racing at medium and high speeds,and the tiller working in the field with high engine speed.The signals were processed by means of the time domain eigenvalue analysis and the frequency spectrum analysis.The results showed that when the tiller was under static condition,with increase of the engine speed,the handle vibration decreased in the vertical direction,increased in the fore-and-aft direction and had marginal changes in the left-to-right direction.When the tiller worked at high engine speed,the handle vibrated most violently in the fore-and-aft direction,while the vibrations at the engine cover and handle decreased substantially in each direction,compared with the static conditions.Rotary blades cutting soil increased the damping of the whole machine so as to reduce the vibration at the handle and the engine cover,but the handle vibration was still violent.When the tiller worked,that soil absorbing energies of some frequencies led to the first order unbalanced inertia force of the engine becoming the main reason why handle vibrated intensely.
