BMW’s ex­haus­tive test­ing

DEMM Engineering & Manufacturing - - CONTENTS -

“Flir has been pro­vid­ing ther­mal imaging cam­eras for ther­mal in­spec­tion to the BMW plant in Din­golf­ing since 1997,” says Robert Halbrit­ter of Flir Sys­tems’ sales part­ner and in­te­gra­tor, TOPA GMbH.

For most of the time, BMW has pri­mar­ily used the cam­eras for elec­trother­mog­ra­phy of switch cab­i­nets and rooms. Hot com­po­nents in­di­cated a prob­lem and were then re­placed. This is the still the case to­day. But now BMW is us­ing ther­mal imaging cam­eras for qual­ity con­trol too.

New ve­hi­cles are sub­jected to a num­ber of in­di­vid­ual and au­to­mated qual­ity con­trol mea­sures in­clud­ing anal­y­sis in one of 10 sep­a­rate roller dy­namome­ters.

The en­tire process just takes a few min­utes, dur­ing which each cor­rect func­tion has to be con­firmed ei­ther au­to­mat­i­cally or by an in­spec­tor who sits in the ve­hi­cle mon­i­tor­ing dis­played in­spec­tion data.

While cost and time-ef­fi­cient test­ing is the com­mon goal, iden­ti­fy­ing the op­ti­mum pro­ce­dure for each in­spec­tion task needs in­di­vid­ual con­sid­er­a­tion. This is the case, for ex­am­ple, when test­ing the ex­haust flaps on a car’s dual ex­haust sys­tem.

Twin tail pipes are a fea­ture of the high per­for­mance BMW ve­hi­cles with eight-cylin­der en­gines. On the BMW M5 model the re­quire­ment is dif­fer­ent again, as the ex­haust flap on the sec­ond tailpipe is only ac­ti­vated at a spec­i­fied RPM.

The rea­son for this may be at first sur­pris­ing as it’s all about acous­tic de­sign, the sound of a pow­er­ful en­gine should be im­pres­sive. There­fore a BMW M5 only opens the sec­ond tailpipe ex­haust flap when it is re­ally needed. Of course this fea­ture has to be in­spected, which is more com­pli­cated than it ap­pears.

To check the ef­fi­ciency of this op­er­a­tion, ther­mal imaging cam­eras – a dif­fer­ent brand to Flir – were ini­tially spec­i­fied for each dy­namome­ter rig. Their pur­pose was to vi­su­alise the ther­mal pro­file of the re­spec­tive tailpipes in the dual pipe ex­haust sys­tem.

Each sys­tem com­prised two ther­mal imaging cam­eras, mounted to in­spect the left and right tail pipes from above and the side. The so­lu­tion was not only ex­pen­sive, but costs also in­creased with time as the cam­eras re­quired fre­quent re­pair over eight years of use.

Halbrit­ter rec­om­mended a sin­gle, fix-mounted Flir A310 with a 45° lens for each dy­namome­ter.

The ad­van­tage: that which was pre­vi­ously in­spected us­ing two cam­eras mounted on the sides could now be vi­su­alised us­ing a sin­gle cen­trally po­si­tioned Flir cam­era.

This is pos­si­ble as the field of view of the Flir A310 with 45° wide-an­gle lens is ca­pa­ble of show­ing the en­tire end of the ve­hi­cle from a dis­tance of ap­prox­i­mately two-me­tres. As a re­sult, com­pre­hen­sive in­spec­tion could be con­ducted by just 10 cam­eras, one for each dy­namome­ter, in­stead of the 20 units re­quired by the pre­vi­ous sys­tem.

The Flir A310 gen­er­ates an ana­logue ther­mal imaging video

sig­nal with a frame rate of 30Hz. This model is par­tic­u­larly suited to record­ing ex­haust flow as it is sim­ple to in­te­grate and pro­vides easy ac­cess to PAL video.

Christoph Hörnlen is re­spon­si­ble for fixed ther­mal imaging cam­eras for au­to­ma­tion ap­pli­ca­tions at Flir Sys­tems GmbH.

“The Flir A310 has a dig­i­tal out­put for alarms and for con­trol­ling ex­ter­nal de­vices,” he says. “Ad­di­tion­ally the data can be trans­mit­ted via TCP IP or Eth­er­net and the Flir A315 even supports the GigE Vi­sion stan­dard as well as the GeniCam pro­to­col.”

The per­for­mance of the ex­haust sys­tem is checked on a mon­i­tor in front of the ve­hi­cle that dis­plays a ther­mal im­age. From this the in­spec­tor can see if the ex­haust flap is func­tion­ing prop­erly from changes in the ther­mal pro­file.­quiry #D140230

Left: BMW M5 cars made at a Ger­man car plant are be­ing tested with the help of Flir ther­mal imaging cam­eras. Right: A ther­mal imaging cam­era from Flir shows ve­hi­cle in­spec­tors whether one or both ex­haust sys­tems are work­ing.

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