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Mea­sure­ments on the valve train / of valve train dynam­ics

Prob­lem: Increased pol­lu­tant emis­sions

Goal: Effi­cient and pow­er­ful com­bus­tion engine

The devel­op­ment of effi­cient and pow­er­ful com­bus­tion engines is one of the main goals of auto­mo­tive devel­op­ment. In this con­text, valve tim­ing is a deci­sive ele­ment in the opti­miza­tion of ther­mo­dy­nam­ics and thus in the effi­cien­cy of com­bus­tion engines.

The analy­sis of valve tim­ing is car­ried out based on the mea­sured, ana­log vari­ables valve lift or valve speed in rela­tion to the camshaft posi­tion. Here, the focus is par­tic­u­lar­ly on the dynam­ic open­ing and clos­ing behav­ior of the valve (e.g. clos­ing veloc­i­ty) as a func­tion of the engine speed.

MEA­SURE­MENT ON THE MOTORED CYLIN­DER HEAD AND FIRED ENGINE

To be able to reli­ably assess the open­ing and clos­ing behav­ior, mea­sure­ments and cal­cu­la­tions of the three mea­sured vari­ables valve lift, valve speed and valve accel­er­a­tion are nec­es­sary. Two dif­fer­ent mea­sur­ing meth­ods can be used for this pur­pose: mea­sure­ment on the motored cylin­der head using a laser vibrom­e­ter and in fired oper­a­tion using mag­ne­to resis­tive (MR) sen­sor tech­nol­o­gy. The mea­sured vari­able valve lift can be deter­mined both on the motored cylin­der head and in fired oper­a­tion using MR sen­sors. For this pur­pose, the speed sig­nals and angu­lar posi­tions at the camshaft dri­ve sys­tem are record­ed. In the first step, the tor­sion­al vibra­tion behav­ior of the camshafts can be derived from this. The mea­sured data from speeds and valve lift can then be eval­u­at­ed in the valve train soft­ware mod­ule. This allows vari­ables such as valve speed and accel­er­a­tion, open­ing and clos­ing behav­ior, lift loss, res­o­nance, and stress behav­ior to be auto­mat­i­cal­ly eval­u­at­ed and graph­i­cal­ly dis­played

ADVAN­TAGES OF VALVE TRAIN TESTS ON THE FIRED ENGINE

Mea­sure­ments on the fired engine have advan­tages over those on the towed cylin­der head. For exam­ple, you can also inves­ti­gate the effects of the gas forces under real tor­sion­al vibra­tion and ther­mal expan­sion behav­iour of the camshafts or the cylin­der head on the fired engine. These effects are becom­ing more and more impor­tant with increas­ing charg­ing and exhaust gas back­pres­sures (par­ti­cle fil­ters).

Anoth­er advan­tage is that the costs for the con­struc­tion of a some­times very com­plex test part car­ri­er can be saved.

SOFT­WARE MOD­ULE FOR AUTO­MAT­ED EVAL­U­A­TION OF DYNAM­IC PARA­ME­TERS

The man­u­al eval­u­a­tion of dynam­ic para­me­ters, such as the valve touch­down speed or the time of dynam­ic open­ing and clos­ing, is very labo­ri­ous with a large num­ber of dif­fer­ent oper­at­ing points and takes up a lot of your work­ing time.

The soft­ware mod­ule “Valve Train” was devel­oped with the aim of per­form­ing these eval­u­a­tions auto­mat­i­cal­ly. This not only reduces the eval­u­a­tion time, but also the size of the test matrix and, accord­ing­ly, the util­i­sa­tion time of the test bench. Instead of per­form­ing mea­sure­ments at con­stant, dis­crete speeds, you can now per­form speed ramps.

With the soft­ware mod­ule, the fol­low­ing para­me­ters, among oth­ers, can be eval­u­at­ed: Angu­lar posi­tion of dynam­ic open­ing and clos­ing, touch­down speed, stroke loss, lift-off, valve bounce, mechan­i­cal load on the com­po­nents (sur­face pres­sure dur­ing cup dri­ve), stroke area and valve over­lap.

The soft­ware eval­u­ates pro­gres­sions of sev­er­al sig­nals (stroke, speed and accel­er­a­tion) and auto­mat­i­cal­ly dis­plays them com­pa­ra­bly for each cycle with the cor­re­spond­ing result para­me­ters. For some analy­ses, addi­tion­al eval­u­a­tion meth­ods are stored that are ready-made for the spe­cialised user (e.g. touch­down speed).

In addi­tion to the mul­ti­tude of analy­sis options, you can auto­mat­i­cal­ly record cycles with sig­nal errors and remove them from the eval­u­a­tions.

The appli­ca­tion of the mea­sure­ment tech­nol­o­gy as well as on-site mea­sure­ments, analy­sis and eval­u­a­tion can be com­plete­ly pro­vid­ed and car­ried out by ROTEC ENGI­NEER­ING.

ROTEC ENGI­NEER­ING car­ries out tests on elec­tric as well as hydraulic camshaft phasers. Thus, inter­ac­tions between valve actu­a­tion and tim­ing are record­ed or the func­tion­al behav­iour of the camshaft phasers is explic­it­ly analysed.

Mea­sure­ment on
motored cylin­der head

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  • Mea­sure­ment of valve stroke and valve speed with laser vibrom­e­ter
  • Camshaft posi­tion mea­sure­ment with rotary encoder
  • Clas­sic mea­sur­ing method with high-pre­ci­sion mea­sure­ment sig­nals

Mea­sure­ment on
fired engine

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  • Valve stroke mea­sure­ment with pre­pared valve stem and MR sen­sor tech­nol­o­gy
  • Devi­a­tion from the laser vibrom­e­ter < 20 µm
  • Spe­cial soft­ware solu­tion for cal­cu­lat­ing the stroke sig­nals from the sen­sor sig­nals (SIN, COS)

Asso­ci­at­ed
Prod­ucts

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