Page 74 - ATZ11 November 2019 Professional

RESEARCH GEARBOXES

0.5

0.4
Efficiency [-]

0.3

480 rpm 1260 rpm 2700 rpm
0.2
0.5 0.75 1 1.25 1.5 1.75 2 2.25 2.5 FIGURE 6 Influence of rotation
speed and torque on the efficiency
Output torque [Nm]
of a window regulator drive unit
(© UAS South Westphalia)

be extended by a minimum of one temperature measuring point ations of the speed measurements are only dependening on the
in the gearbox. sensor quality and the digitizing error. Furthermore, it has been
If the operating conditions are controlled, the maximum total shown that the operating parameters such as speed, torque, tem-
deviations of an efficiency measurement can be calculated from perature and lubrication condition have an elementary influence
the relative deviations of the individual measured variables. on the efficiency and must be controlled as good as possible.
According to DIN 1319, the single deviations of quantities which
affect the total variance by multiplication can be summarized REFERENCES
according to Eq. 2 [6]: [1] Rieg, F.; Steinhilper, R: Handbuch Konstruktion. München: Carl-Hanser-
Verlag, 2018
[2] Prüftechnik Alignment System GmbHs: Wellenausrichten. Handbuch für
________________
2
2
Eq. 2 f Total = √ f + f + f + f Techniker und Ingenieure. 1 st edition, Ismaning, 2005
2
2
[3] Pohl, M.: Physik für alle. 1 st edition, Weinheim: Wiley-VCH Verlag, 2014
T_In n_In T_Out n_Out
[4] Nönnig, R.; Heß, D.; Hoffmann, R.: Justieruntersuchungen zum Ausrichten
von optischen und mechanischen Achsen. TU Ilmenau, 1999
A deviation of 1 % each for input and output torque and for input
[5] Niemann, G.; Winter, H.: Maschinenelemente. Volume 3, 2 nd edition, Berlin/
and output speed leads to the following relative total deviation, Heidelberg/New York: Springer-Verlag, 2004
Eq. 3: [6] DIN Deutsches Institut für Normung e. V.: DIN 1319 Teil 3. Grundlagen der
Meßtechnik. Teil 3: Auswertung von Messungen einer einzelnen Meßgröße
Meßunsicherheit. Berlin: Beuth-Verlag, 1996
_____________________
2
+ 0. 01
2
Eq. 3 f Total = √0. 01 + 0. 01 2 + 0. 01 2 = 0.02 ⇒ 2 %
6 SUMMARY
As the presented system illustrates, modular test systems enable
an economic analysis of the mechanical parameters of gearboxes
and electrical drive units. This results of a multiple use and stan-
dardized operation of cost-intensive components such as sensors,
measuring amplifiers, controlled drives and brakes. In addition, a
standardized alignment sliding carrier system can easily limit posi-
tion errors of the different axis and positively influence reproduc-
ibility and maximum measuring deviations. Only the torque spec-
trum is limited by a standardized measuring sliding carrier, but
covers the range of gearboxes for comfort functions in passenger
cars (0.001 to 25 Nm).
The analysis of the maximal measuring errors pointed out that
it is always necessary to estimate the deviations related to the
actual measured value. In most cases the deviation related to the
nominal value of a sensor is given, but especially for low range
measurements much smaller than the real value.
In case of gear efficiency measurements, special regards have
to be taken on the deviations related to the torque. This is because
there is a large number of effecting variables. In contrast, the devi-
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