Page 134 - Gear Technology Solutions

Figure 20 shows the results of the motion transmission error for side gear torques
of 10Nm, 40Nm and 200Nm. The solid blue graph shows the transmission errors
®
of the Coniflex Pro differential, and the dotted red graph shows the results of the
forged differential.

The blue graph in the diagram on top for 10Nm mirrors the motion
transmission graph in Figure 14 rather well and has a maximal amplitude of
95mrad. The red graph of the forged version has a maximal amplitude of
950mrad, which is 10 times the value of the cut gears. It can also be noticed
that the red graph appears to be triangular, with sharp edges at the transition
point between tooth pairs. The blue graph is smoothly rounded which results in
a quieter load transfer from one tooth pair to the next. The noise of a
transmission is most audible at low or zero load which applies for zero to
40Nm in the case of this example.

In the center graph of Figure 20 a side gear torque of 40Nm was applied. The
cut differential (blue graph) shows a maximum transmission error of 155mrad.
For the forged counterpart, the maximal transmission error is 740mrad which is
still about 5 times the amount of the cut differential. With increasing loads, the
flank surfaces and the teeth deform which creates additional transmission error
and the difference between different tooth geometry appear to be diminished.
However, in case of high loads, the load sharing advantage of the Ease-Off
optimized differential is still present. In the case of low loads, the flank
geometry only generates the motion graph. For high loads, the load sharing,
which is a result of the flank geometry, generates the motion graph.

In the case of the bottom graphic in Figure 20, 200Nm side gear torque has
been applied. The blue graph of the cut gearset now reaches 590mrad
transmission error, where the red graph of the forged version has 950mrad
transmission error amplitude which is still 61% above the level of the cut
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Coniflex Pro gearset. Although the noise emission is not a concern with this high
load, the difference of 61% in transmission error amplitude still presents a
significant advantage in the excitation of vibration and noise and in addition shows
that the load sharing of the cut gearset has a favorable influence.

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