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Multiple gear dog clutch transmission control optimization

Performance targets of a dog clutch are:

  • Low space requirements and weight
  • Lower production costs compared to similar systems
  • High efficiency
  • Low drag torque

The electro-mechanical actuation of a dog clutch is a very cost effective and efficient solution but includes a certain list of risks. Generally switching gears is only possible in a defined rotational speed range. This corridor is mainly determined by the geometry of the engaging teeth. Leaving the defined speed range may cause increased noise, even blocking or rejecting of the claw can happen and this can lead to a shift failure. A fault in the actuation could cause a significant acceleration, braking torque or in extreme situation a deadlock of the whole power train. According to ISO 26262 these faults must be secured with ASIL C or ASIL-D.
This increases the performance requirements for the used sensors. It also causes the need of a precise
positioning of the claw in end positions and in the neutral position also called middle position.
A dog clutch contact model built with AMESim effectively allows a practical interpretation of the relevant
parameters and gives an overview of the whole system using simulation. With these reviews an interpretation of the gear shift quality and safety-critical situations can be performed before hardware prototypes are built. Combining a multiple speed gearbox with electro-mechanical dog clutch will also provoke advanced requirements to the mechanical and the electrical system.
A system-related disadvantage may be the interruption of traction during a shift. During simulation special
attention must also be on the external influences on the system, such as drag torques and vibrations in the power train, which may affect the robustness and quality of the shifts significantly. When all external factors are clear, a special software algorithm can be developed and verified by using simulation and optimization (MiL, SiL, HiL). This avoids and identifies possible error conditions or risks in the design- and interpretation phase to saving working time and money. Read more abtout this topic in the attached article, which is based on calculations, simulations and experimental results of test benches and vehicles and thus demonstrates the potential for optimization using the methods described.

Downloads auf dieser Seite Beschreibung
 13-06-19_VDI Vortrag_Kern.pdf  Technical paper, International Congress Drivetrains for Vehicles 2013 
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