HOERBIGER Antriebstechnik GmbH uses the gear shift simulator to test the impact of design changes on the shift comfort early on in the development process – without any prototypes.

Testing the impact of design changes on the shift comfort immediately

The task at hand

Simulating gearbox, transmission, synchronizers and powertrain in real-time

HOERBIGER’s history dates back to the year 1895 – today, the company has more than 6,700 employees and is a leading global player in the areas of compressor and automation technologies and powertrain engineering. HOERBIGER’s business unit for drive technology develops synchronizers for manual and dual clutch transmissions amongst others using ITI software for offline simulations. For the adjustment and optimization of synchronizer devices during the development phase, various parameters, such as complex, interacting geometries of locking and meshing teeth, are being altered to simulate the impact on the final product. So far, it has only been possible to determine resulting effects and experience the gear shifting behavior realistically through a physical prototype. Requirements for new products in regards to haptics are usually agreed on through verbal communication. Their interpretation, however, remains a highly subjective matter.

Since judgment about a vehicle is also influenced by the gear shifting behavior, it is of great importance to define those requirements on an objective, reproducible basis and to get a realistic impression of the final gear shifting behaviour early on. The objective was to develop an HiL simulator with a physical gear stick that could mimic the gearbox, internal and external shift mechanisms, the synchronizer and the powertrain within a single real-time simulation. The simulator was supposed to handle shifting gears with all that is to it as if it was in a real car. HOERBIGER was hoping to be able to immediately assess the impact of design measures on the gear shifting behavior already at the beginning of the development process without the need for a prototype. By using a real-time system, parameters and geometries were supposed to be editable on the fly.

The solution

The realtime shifting simulator

ITI’s expertise and SimulationX have proven to be most suitable for modeling and simulating the complex construction attached to the gear stick. An existing model was stripped down for that purpose retaining its real-time capabilities and characteristics. Despite the reduction, all components relevant to the gear shifting behavior, such as synchronization with friction cones, locking and meshing teeth, gearbox with internal and external shift mechanisms and the powertrain, are taken into account. Geometries of locking and meshing teeth can be defined in line with the construction. The gear shift simulator has a modular structure consisting of an operator PC, real-time hardware with a user interface and the gear stick. SimulationX handles the entire communication between all components of the model while it can be altered or extended to be then applied to the real-time hardware via C-code export. The simulator can be parameterized on the fly through the user interface, and measured values as well as characteristic curves can be saved and loaded providing a flexible and easy way of adapting the simulator to new scenarios.

The entire program with the multi-physics model runs on the real-time hardware which in turn is the basis for evaluating the operator’s actions while current counterforces are calculated through the model and transferred onto the gear stick. With SimulationX at the heart of that modular test bench, HOERBIGER Antriebstechnik GmbH has a lot of leeway for future adaptations. Standard interfaces guarantee a seamless transfer of data while the toolchain as a whole remains uninterrupted for an effortless workflow in the analysis and processing of results from tests and offline simulations.

The benefits

Realistic shifting operations

In discussions about the requirements of transmission synchronization, opinions between clients, contractors, development and testing engineers often differ a great deal. Moreover, it is not possible to replicate the exact behavior of real manual transmissions for multiple operations by different people. Changes in geometries, parameters or environmental factors can only be scrutinized in protracted procedures. Therein lies the essential advantage of a gear shift simulator: the gear shifting behavior can be defined exactly, and the impact of constructional changes can be assessed directly – without the need for a time and cost consuming prototype. Just like in reality, faulty configurations make it difficult or even impossible for the multi-physics model to execute shifting operations. The simulator responds in such a realistic manner that the operator could not tell the difference from a real system. These capabilities make it easy to replicate shifting operations, provoke malfunctions and alter environmental influences quickly. During parameter studies, results are accessible instantly.

HOERBIGER Antriebstechnik GmbH uses the simulator for the following tasks:

  • defining the gear shifting behavior on an objective basis
  • running case studies with various variants and analysing parameter effects of constructional factors
  • replicating haptic values from either simulated results or measured values taken from real systems

This project contributes to HOERBIGER’s ongoing commitment to verification and quality control – both in production and development.

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