LEAK TESTING OF COMPONENTSElectric Drive Motors
DESCRIPTION OF TECHNICAL CHALLENGE
The market for electric vehicles is growing rapidly. More and more electric drive
motors are being developed for this particular application. Electric drive motors
can either be part of an integrated electric drive system (with power control andtransmission) or standalone units.
Electric drive motors are typically exposed to water either from the environment or
during high pressure water cleaning in car wash stations. Thus, they need to fulfill
ingress protection requirements of IP67 up to IP69K. This leads to leak raterequirements of 10-3 mbar l/s (for plastic or steel housings) and 10-5 mbar l/s foraluminium housings.
More and more motors also use active water cooling for the motor to be held at aconstant temperature for maximum efficiency. The cooling liquid is typically awater / glycol mixture. It is crucial that the water jacket of an electric motor istested for leakage to avoid water leaking into the electric parts of the motor andcausing short circuits. The typical leak rate requirement for leaks in the watercooling circuit are in the 10-3 mbar l/s range. Water must not leak out of any
potential leak channels.

Electric drive motors (DM) need to betested for protection against water ingress
as well as for leaks form the cooling water
jacket.

Water cooling circuits should not be tested by air leak testing / pressure decay
testing as any components in the water cooling circuit are designed for rapid heattransfer. This causes the parts to change temperature very quickly. Air leak testing/ pressure decay testing is very sensitive to temperature changes. An increase intemperature during the testing time will mask potential leaks, a decrease intemperature will cause a virtual leak to be detected - a false alarm in the testingsystem.

THE INFICON SOLUTION
Testing of drive motor housing for ingress protection – steel orplastic housing
If made from steel or plastic, the housing of the motor can be tested via
accumulation leak detection. The housing is evacuated and backfilled with helium
or a forming gas (a 5% hydrogen in nitrogen mixture) as tracer gas at approx. 5bar (or whatever maximum pressure the housing may endure) and sealed. The
filled housing is then placed in an accumulation chamber and the tracer gas
concentration in the accumulation chamber is monitored by an LDS3000 AQ leakdetector. If a leak is present, the concentration in the accumulation chamber willrise over time and the rate of rise is a measure for the leak rate of the part. After
testing the tracer gas is reclaimed from the part and the part is vented. The
reclaimed tracer gas may be used for the next testing cycle.

In accumulation testing, the motor housing
is filled with helium, placed in anaccumulation chamber and the rise inhelium concentration in the chamber isdetected by an LDS3000 AQ leakdetector.

LEAK TESTING OF COMPONENTS
ELECTRIC MOTORS
Testing of drive motor housing for ingress protection – aluminium
housing
If made from aluminium, the motor housing must be tested via vacuum chamberleak detection. The housing is again evacuated and backfilled with helium at approx.
2 - 3 bar (or whatever maximum pressure the housing may endure) and sealed. The
filled housing is then placed in a vacuum chamber. The vacuum chamber is also
evacuated to very low pressure and a LDS3000 vacuum leak detector is connectedto the chamber. Any helium escaping form the test part will be detected by theLDS3000 and a leak rate for the part is displayed. After testing the helium is also
reclaimed from the part and the part is vented. The reclaimed Helium may be used
for the next testing cycle.
Testing of the water cooling jacket - steel or plastic housing
For testing the water jacket of the housing, the water jacket cavity is filled with tracergas (helium or forming gas = 5% hydrogen in nitrogen) at approx. 2 - 3 bar (orwhatever maximum pressure the material may endure) and the inlet and outlet of
the water cooling channel are sealed. The housing is then placed in an
accumulation chamber and the tracer gas concentration in the accumulationchamber is monitored by a LDS3000 AQ leak detector. If a leak is present, theconcentration in the accumulation chamber will rise over time and the rate of rise isa measure for the leak rate of the part. After testing the tracer gas is reclaimed fromthe part and the part is vented. The reclaimed tracer gas may be used for the next
testing cycle.
Testing of the water cooling jacket - aluminium housing
If made from aluminium, the water jacket cavity is filled with helium at approx. 2 - 3bar (or whatever maximum pressure the material may endure) and the inlet andoutlet of the water cooling channel are sealed. The part is then placed in a vacuumchamber. The vacuum chamber is also evacuated to very low pressure and a
LDS3000 vacuum leak detector is connected to the chamber. Any helium escaping
form the water jacket will be detected by the LDS3000 and a leak rate for the part isdisplayed. After testing the helium is reclaimed from the part and the part is vented.
The reclaimed Helium may be used for the next testing cycle.

BENEFITS OF LEAK TESTING WITH TRACER GAS•Highly sensitive testing to find small leaks•

Short cycle times in testing guarantee high throughput•

Highly reliable results of testing as independant of temperature and humidity•

Robust leak testing equipment with high uptime

For more information, please visit us atwww.inficonautomotive.com or call your nearest sales representative.

www.inficon.co mreachus@i nficon.com

Due to our continuing program of product improvements, specifications are subject to change without notice.
miaq00en-a (1904)©2019 INFICON

In vacuum chamber testing, the drive
motor is filled with helium, placed in a
vacuum chamber and any helium
excaping from a leak is detected by theLDS3000 leak detector.