COM­PLEX SPEED MEA­SURE­MENT TASK WITH INDI­VID­U­AL­LY DEVEL­OPED SEN­SORS

Engi­neers are con­stant­ly faced with new chal­lenges when it comes to speed mea­sure­ments under dif­fi­cult envi­ron­men­tal con­di­tions. One exam­ple is the mea­sure­ment on the roller tap­pet or bear­ing to deter­mine caus­es of wear and tear: Which sen­sor tech­nol­o­gy is suit­able due to the tight space and extreme con­di­tions such as high tem­per­a­ture and oily envi­ron­ment? And how can mean­ing­ful results be achieved? The fol­low­ing case study describes how the engi­neer­ing team of Rotec Engi­neer­ing, devel­oped a cus­tomized minia­ture sen­sor for speed record­ing on the roller tap­pet and derives rec­om­men­da­tions for action using suit­able mea­sure­ment and analy­sis soft­ware.

WHERE CAN TOR­SION­AL VIBRA­TIONS BECOME CRIT­I­CAL IN THE E‑POWERTRAIN?

The switch to elec­tro­mo­bil­i­ty is pick­ing up speed. There are already 10.9 mil­lion e‑cars on the road world­wide (2020) and this num­ber will rise to 34 mil­lion by 2030 (Cere­sana fore­cast). In the devel­op­ment of e‑drive trains, the focus is on elec­tric stor­age capac­i­ty, weight and size of the trac­tion machine, durable pow­er­train com­po­nents, ride com­fort and thus qui­et dri­ving. Stan­dard NVH analy­sis sys­tems use air­borne and struc­ture-borne sound sig­nals to study the gen­er­at­ed noise, vibra­tion, and their trans­mis­sion paths, but usu­al­ly ignore the mech­a­nism of how these effects are gen­er­at­ed. How can noise exci­ta­tion be bet­ter stud­ied, where can tor­sion­al vibra­tions become crit­i­cal as well as dynam­ic loads, and what para­me­ters should be col­lect­ed?

IMPROVED APPROACH­ES TO THE MEA­SURE­MENT AND ANALY­SIS OF TOR­SION­AL VIBRA­TION ANALY­SIS

A pri­ma­ry goal of NVH engi­neer­ing is the iden­ti­fi­ca­tio­nand con­trol of noise and vibra­tion sources. In recen­tyears the tor­sion­al vibra­tion behav­iour of engine and pow­er­train com­po­nents has gained in sig­nif­i­cance. This paper dis­cuss­es sev­er­al aspects of mea­sur­ing and analysing tor­sion­al vibra­tion and relat­ed data. Sev­er­al tor­sion­al vibra­tion mea­sure­ment tech­niques are pre­sent­ed, togeth­er with remarks on pre­cau­tions against pos­si­ble sources of error, and the order of accu­ra­cy to be expect­ed of the test results. Two appli­ca­tions requir­ing mul­ti­chan­nel mea­sure­ment and analy­sis are out­lined.

MEA­SURE­MENT AND ANALY­SIS OF TOR­SION­AL VIBRA­TIONS IN AUTO­MO­TIVE DEVEL­OP­MENT

Tor­sion­al and rota­tion­al vibra­tions are mechan­i­cal vibra­tions caused by time-alter­nat­ing torques which are super­im­posed on the oth­er­wise steady run­ning speed of a rotat­ing shaft. In auto­mo­tive engi­neer­ing tor­sion­al vibra­tion is pri­mar­i­ly caused by the fluc­tu­a­tions in engine pow­er out­put. This results in crank­shaft angu­lar veloc­i­ty fluc­tu­a­tions which cause twist­ing and untwist­ing of the shaft. The effects of tor­sion­al vibra­tion are ampli­fied by tor­sion­al res­o­nance which occurs when a shaft‘s nat­ur­al fre­quen­cy coin­cides with its tor­sion­al fre­quen­cy. Exces­sive tor­sion­al vibra­tions can result in unwant­ed noise, pow­er­train com­po­nent wear and, in severe cas­es, bro­ken shafts. To iden­ti­fy such effects in advance and adopt mea­sures to avoid them before ex-ces­sive dam­age has occurred, the devel­op­ment engi­neer requires ded­i­cat­ed, state-of-the-art mea­sur­ing equip­ment incor­po­rat­ing appli­ca­tion-spe­cif­ic soft­ware to sim­pli­fy mea­sure­ment set­up and pro­vide quick analy­sis.

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WHERE CAN TORSIONAL VIBRATIONS
BECOME CRITICAL AND CAUSE NOISE IN THE E-POWERTRAIN?

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