Abstract
To this point, requirements imposed on the transmission have been introduced that are satisfied via multiple gears and appropriate gear ratio change. In Sect. 2.1, this chapter describes the various phases of a shift sequence and compares the ideal shift sequence with shift sequences that are not acceptable in terms of quality. The shift-related torque changes as well as the engine excitations and torque variations cause the powertrain to vibrate. In Sect. 2.2, the occurring vibrations and eigen frequencies are discussed, as are measures for reducing these vibration occurrences.
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Notes
- 1.
In this regard the parameters of the gear-specific simulation models vary in accordance with Fig. 2.1 for automatic transmissions upstream and downstream of the friction elements, for dual clutch transmissions the left side remains unchanged.
- 2.
In addition to the requirement for sufficient dynamics of the actuation system, the signal processing that must identify the states “clutch released” and “gear selected” is of utmost significance.
- 3.
For applications in sports cars and commercial vehicles, a fast shift nonetheless is required relative to traction force reduction, usually the synchronizer units are dispensed with dog clutches and the clutch is not completely released.
- 4.
The designation, eigen angular frequency is more correct in ω0 = 2πf, f is the frequency.
- 5.
Due to the interactions of stiffness, inertia, and damping of the components of the transmission, the influence of a gear ratio change, for example, is not restricted to the gear in question.
- 6.
In case of resonance, the numeric solution procedures without damping are unstable.
- 7.
If the minimum of excitation were to coincide with one resonance, most likely it would not be possible to identify the eigen mode.
- 8.
A frequent problem is the transfer of a transmission or powertrain into a new powertrain or vehicle configuration, in which new vibration problems or acoustic phenomena are observed, which must be analyzed and remedied with great effort.
- 9.
The authors are not aware of any series production designs in vehicle transmissions, however, such measures are frequently used for gear sets in combustion engines [140].
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© 2015 Springer International Publishing Switzerland
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Fischer, R., Küçükay, F., Jürgens, G., Najork, R., Pollak, B. (2015). Shift Dynamics and Shift Comfort. In: The Automotive Transmission Book. Powertrain. Springer, Cham. https://doi.org/10.1007/978-3-319-05263-2_2
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DOI: https://doi.org/10.1007/978-3-319-05263-2_2
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