Undesired Rota­tion­al Vibra­tions in Com­bus­tion Engines

Rota­tion­al and tor­sion­al vi­bra­tions in the focus

Rota­tion­al or tor­sion­al vi­bra­tions de­note vi­bra­tion states of a sys­tem around its ro­ta­tion­al de­gree of free­dom, i.e. lin­ear elast­ic vi­bra­tion states around its own body axis. Since a com­bus­tion en­gine rep­res­ents a com­plex struc­ture or multi-mass sys­tem con­sist­ing of sev­er­al hun­dred in­di­vidu­al parts, the pre­ven­tion of ro­ta­tion­al vi­bra­tions is at­trib­uted an es­sen­tial role. This is be­cause vi­bra­tions have a neg­at­ive ef­fect on the op­er­at­ing be­ha­vi­or of the en­gine. In ad­di­tion to in­creased ef­fi­ciency, re­li­ab­il­ity and longev­ity are key factors in the de­vel­op­ment of en­gines and testi­fy to their high qual­ity.

Long-Term Loads in Engines

Poten­tial dam­age due to tor­sion­al vi­bra­tions

As a res­ult of the trans­lat­ory move­ment of the pis­ton stroke, the crank­shaft is set in ro­ta­tion, which in turn in­tro­duces its ro­ta­tion­al en­ergy into down­stream shafts. However, the in­con­stant force trans­mis­sion of the acyc­lic­al lift­ing pro­cess pro­motes the oc­cur­rence of ro­ta­tion­al and tor­sion­al vi­bra­tions in the crank­shaft. The forced ro­ta­tion­al vi­bra­tions rep­res­ent a po­ten­tial source of dam­age if the ex­cit­a­tion fre­quency is close to the nat­ur­al fre­quency of the shaft and thus pro­duces high amp­litudes. Over a longer peri­od of time with many os­cil­lat­ing back­lashes, ro­ta­tion­al vi­bra­tions pro­mote dam­age to shafts and down­stream com­pon­ents such as gear­boxes.

High Pre­ci­sion Meas­ure­ment and Ana­lys­is Tech­no­logy

Our solu­tion for ro­ta­tion­al vi­bra­tions in en­gines

A meas­ure­ment and ana­lys­is sys­tem that iden­ti­fies and ana­lyzes dan­ger­ous ro­ta­tion­al vi­bra­tion con­di­tions. The IfTA sys­tems in con­junc­tion with the award-win­ning AT2 input mod­ule and the ana­lys­is soft­ware IfTA TrendView­er meet these chal­lenges. The cus­tom­iz­able sys­tems en­able angle-re­lated eval­u­ations of tor­sion­al vi­bra­tions in real time. The res­ult­ing in­sights into the nat­ur­al fre­quen­cies of the tor­sion­al vi­bra­tions of the sys­tem provide the basis for fur­ther im­prove­ments.

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