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Research Papers

Transmission of Engine Harmonics to Synchronizer Mechanisms in Dual Clutch Transmissions

[+] Author and Article Information
Paul D. Walker

School of Electrical, Mechanical and
Mechatronic Systems,
University of Technology-Sydney,
15 Broadway,
Ultimo, New South Wales 2007, Australia
e-mail: Paul.Walker@uts.edu.au

Nong Zhang

School of Electrical, Mechanical and
Mechatronic Systems,
University of Technology-Sydney,
15 Broadway,
Ultimo, New South Wales 2007, Australia

Contributed by the Technical Committee on Vibration and Sound of ASME for publication in the JOURNAL OF VIBRATION AND ACOUSTICS. Manuscript received January 16, 2014; final manuscript received May 6, 2014; published online August 8, 2014. Assoc. Editor: Prof. Philippe Velex.

J. Vib. Acoust 136(5), 051009 (Aug 08, 2014) (8 pages) Paper No: VIB-14-1015; doi: 10.1115/1.4028079 History: Received January 16, 2014; Revised May 06, 2014

Synchronizer mechanisms play an important role in the selection and engagement of gears in manual, automated manual, and dual clutch transmissions (DCTs). These mechanisms rely heavily on the balancing of torque loads in cone clutches, dog gears, and from losses in the gearbox to ensure repeatable and reliable actuation, with excessive wear on friction and contact surfaces, leading to degradation of actuation and potential mechanism failure. DCTs, in particular, provide a unique operating environment for synchronizers, most notably is its actuation with the engine still driving the wheels during normal driving conditions. Thus, the consideration of increased transmitted vibrations through the powertrain must be evaluated to study the impact of these vibrations on the synchronizer. To conduct this investigation, this paper develops a detailed multibody dynamic model of a typical automotive powertrain equipped with a DCT. This includes engine models with torque harmonics that capture the instantaneous torque variations from piston firing in the engine. As the main consideration of this paper is the influence of engine harmonics, the semidefinite powertrain model is simplified to a fixed-free system and the response of the synchronizer mechanism to harmonic torque inputs is analyzed. Parametric analysis of the system is conducted to analyze the influence of variables—including gear ratio, torsional damper, system damping, and engine configuration—on the dynamic response of the mechanism. Results demonstrate the influence of each of these variables on synchronizer dynamics in the steady state, with stiffness of torsional damper having the strongest influence on forced vibration. Additionally, results vary significantly between single and dual lay-shaft transmissions.

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References

Figures

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Fig. 1

Typical single lay-shaft DCT powertrain layout

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Fig. 2

Cross section of a typical synchronizer [2]

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Fig. 4

Single lay-shaft format of the DCT powertrain

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Fig. 5

Dual lay-shaft format of the DCT powertrain

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Fig. 6

Instantaneous engine torque as a percent of mean torque

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Fig. 7

Steady state response of element 4 with (a) four cylinder engine harmonics, (b) six cylinder engine harmonics, and (c) eight cylinder engine harmonics

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Fig. 8

Natural frequency of simplified single lay-shaft model in (a) and (b), and dual lay-shaft model in (c) and (d)

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Fig. 9

Steady state response of element 4 with different gear ratios (a) first gear, (b) second gear, (c) third gear, (d) fourth gear, (e) fifth gear, and (f) sixth gear

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Fig. 10

Steady state response of element 4 with stiffness (a) K1 = 500 N·m/rad, (b) K1 = 1000 N·m/rad, (c) K1 = 10,000 N·m/rad, and (d) K1 = 50,000 N·m/rad

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Fig. 11

Steady state response of element 4 with damping (a) C1 = 0 N·ms/rad, (b) C1 = 1 N·ms/rad, (c) C1 = 2 N·ms/rad, (d) C1 = 5 N·ms/rad, and (e) C1 = 10 N·ms/rad

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Fig. 12

Nonlinear torsional damper models

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Fig. 13

Steady state response of element 4 torsional damper models: (a) alternative 1, (b) alternative 2, (c) alternative 3, and (d) alternative 4

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