珀金斯發(fā)動(dòng)機(jī)扭振分析(TVA)介紹

珀金斯發(fā)動(dòng)機(jī)扭振分析(TVA)介紹

1、什么是扭振分析

  扭振是關(guān)于傳動(dòng)系統(tǒng)激勵(lì)頻率對(duì)固有頻率影響程度的計(jì)算,反映了系統(tǒng)是否存在諧振(共振)的危險(xiǎn)程度；主要與系統(tǒng)各組成件的轉(zhuǎn)動(dòng)慣量和扭轉(zhuǎn)剛度 有關(guān),即與設(shè)備的結(jié)構(gòu)尺寸有關(guān)。

  任何旋轉(zhuǎn)系統(tǒng)都會(huì)產(chǎn)生扭轉(zhuǎn)振動(dòng)，特別是單軸承或雙軸承交流發(fā)電機(jī)，研究其全套裝置的扭振特性是非常比要的。

  2、為什么要扭振分析

    扭振分析是裝備發(fā)動(dòng)機(jī)設(shè)備出廠前的必要步驟，也是A&I分析的重要組成部分。

在發(fā)動(dòng)機(jī)運(yùn)行速度的某些范圍內(nèi)，這些振動(dòng)可足以使曲軸、飛輪螺栓、大齒輪的帶齒等斷裂。在發(fā)生上述危害的任何地方的速度范圍內(nèi)的點(diǎn)，稱之為“臨界速度”。

  該扭轉(zhuǎn)振動(dòng)分析的目的是計(jì)算出量級(jí)和擾動(dòng)力頻率的臨界轉(zhuǎn)速點(diǎn)，并確保破壞臨界速度超出了引擎運(yùn)行范圍，且非常明顯地使其在+10％到-5％的同步速度范圍內(nèi)。有一些臨界轉(zhuǎn)速可能在從啟動(dòng)到同步轉(zhuǎn)速的95%范圍內(nèi)，但是這些都可能被視為“安全”，臨界轉(zhuǎn)速立刻通過(guò)，因?yàn)椤芭R界轉(zhuǎn)速”1秒左右立刻通過(guò)。

  但是，如果該應(yīng)用需求為“全速”范圍，那么所有的臨界轉(zhuǎn)速必須控制在安全范圍內(nèi)。

在四沖程循環(huán)中，每個(gè)汽缸瞬間氣壓發(fā)生著變化，那么任何點(diǎn)上的扭矩也在發(fā)生著變化。這將導(dǎo)致曲軸在其均值旋轉(zhuǎn)位置附近出現(xiàn)“搖晃”的情況。

  當(dāng)扭矩組件與軸的自然頻率同相時(shí)會(huì)發(fā)生共振；嚴(yán)重情況下，將會(huì)導(dǎo)致曲軸斷裂

  3.如何進(jìn)行扭振分析

  ISO 8528 指定確保扭振兼容性為發(fā)電機(jī)組制造的責(zé)任，珀金斯發(fā)動(dòng)機(jī)裝備時(shí)刻通過(guò)以下方式進(jìn)行扭振分析

       <1> 所需資料：曲軸、皮帶輪等旋轉(zhuǎn)零部件的慣量及軸的尺寸和剛性；

       <2> 可以通過(guò)OCD流程進(jìn)行申請(qǐng)PERKINS發(fā)動(dòng)機(jī)的TVA計(jì)算，但需收費(fèi)；

       <3>  OEM希望自己進(jìn)行TVA計(jì)算，PERKINS可以提供計(jì)算所需要的發(fā)動(dòng)機(jī)數(shù)據(jù)；如圖

  PERKINS 規(guī)定：沒(méi)有通過(guò)TVA計(jì)算的PERKINS發(fā)動(dòng)機(jī)安裝是不允許的；否則由安裝引發(fā)的任何問(wèn)題和故障PERKINS不承擔(dān)任何保修。

Perkins engine torsional vibration analysis (TVA) Introduction
Perkins engine torsional vibration analysis (TVA) Introduction
1, What is torsional vibration analysis
  Driveline torsional vibration excitation frequency is about the degree of influence on the natural frequency is calculated to reflect the existence of the system resonance (resonance) the degree of risk; primarily composed of members of each of inertia and torsional stiffness of the system concerned, that's about the size of the equipment and structure .
  Any rotation system will produce torsional vibration, especially single or double bearing alternator, research torsional vibration characteristics is its full device than want.
  2, why should torsional vibration analysis
    Torsional Vibration analysis is a necessary step before leaving the factory equipped engine equipment is an important part of A & I analysis.
Within a certain range of engine operating speed, which may be sufficient to make the vibration of the crankshaft, flywheel bolts, toothed gear or the like breaking. Point anywhere within the speed range of the hazard occurrence, called "critical speed."
  The purpose of the torsional vibration analysis is to calculate the magnitude of the critical point and the rotation speed of the power frequency interference and ensure destruction of critical engine speed exceeds the operating range, and it is obvious to -5% to +10% of the synchronous speed in the range of . Some may be critical speed within the range from the start to 95% of synchronous speed, but these are likely to be considered "safe", through the critical speed immediately, because the "critical speed" of about 1 second through immediately.
  However, if the application needs to "full" range, then all the critical speed must be controlled within a safe range.
In the four-stroke cycle, each cylinder pressure is changing moment, then torque at any point is changing. This would lead to "wobble" in the case of crankshaft rotation around its mean position.
  When the natural frequency of the shaft torque component in phase with the resonance occurs; severe cases, will lead to the crankshaft fracture
  3 How to torsional vibration analysis
  ISO 8528 designated responsibility for ensuring the compatibility of torsional vibration generators manufactured by Perkins Engines equipped moment torsional vibration analysis in the following manner
       <1> required information: the size and rigid crankshaft pulley and other rotating parts inertia and axes;
       <2> can apply PERKINS engines process TVA calculated by OCD, but for a fee;
       <3> OEM TVA wants to be calculated, PERKINS can provide the required computing engine data; Figure