拖拉机方向盘手传振动评价与驾驶员手臂振动传递特性

Evaluation of hand-transmitted vibration of tractor steering wheel and characteristics of vibration transmission of different percentiles driver arm

为探究拖拉机方向盘手传振动传递规律,减少拖拉机驾驶员手传振动暴露量,预防手臂振动病发生,本研究以某拖拉机方向盘与驾驶员手臂系统为研究对象,采用ISO 5349评价体系对拖拉机在2种不同路况下的手传振动进行综合评价,并对不同百分位驾驶员手臂系统进行振动传递特性分析。结果显示,该拖拉机的日振动暴露量为4.257 m/s^(2),超过国标GB Z 2.2—2007《作场所有害因素职业接触限值第2部分:物理因素》规定的日振动暴露量限值(3.5 m/s^(2)),具有引发手臂振动病的较高风险;方向盘轴向振动远大于切向和径向振动,是引发手传振动的主要因素;径向的振动从手背经过手腕传递到小臂时被大量吸收,切向的振动从小臂经过肘关节传递到大臂时被大量吸收;驾驶员体型越小,各轴向手背测点的振动传递率越大,随着体型的增大,低频范围(20 Hz以下)的振动从手背传递到小臂过程中有明显的增大。研究结果表明,工程实际中小体型驾驶员要注意手掌的振动防护,而大体型驾驶员更应注重手腕部分的振动防护;对驾驶员手腕应主要加强径向的防护,对肘关节主要加强切向的防护。

There are problems including intense vibration and unclear vibration transmission characteristics during manipulating the steering wheel by the tractor operators.The ISO 5349 evaluation method was used to evaluate the hand-transmitted vibration of the steering wheel system under two different conditions and analyze the characteristics of vibration transmission of operators’arm systems at different percentages.The results showed that the daily vibration exposure of the tractor was 4.257 m/s^(2),which exceeded the limit of daily vibration exposure of 3.5 m/s^(2) specified in the national standard,and had a high risk of causing hand-arm vibration disease.The steering wheel vibration in the axial direction was greatly higher than that in the tangential and radial directions,which was the main factor causing hand-transmitted vibration.The radial vibration was largely absorbed during the transmission from the hand back to the forearm,while the tangential vibration was greatly absorbed in the transmission from the forearm to the upper arm.Moreover,the smaller the operator’s physical size,the greater the vibration transmission rate at the hand back.The significant increase in vibration from the hand back to forearm was found under the frequency of 20 Hz.Therefore,smaller operators in engineering practice should pay attention to the vibration protection at the palms,while larger ones are suggested to focus on the vibration protection at the wrists.In addition,the radial protection should be mainly strengthened for the driver’s wrist,and the tangential protection should be mainly strengthened for the elbow joint.