Industrialised for Production.
For a concept car BMW Automotive needed a hybrid transmission for a special vehicle layout.
The combustion engine, the asynchronous-machine as well as the pinion shafts were outlined.
The topology of the single gear steps and its functionalities were developed and defined together.
Because of the available installation space an individual shaft arrangement needed to be worked out.
As a result a hybrid transmission with 3 gears for the combustion and 2 gears for the electric engine with a total of max. 4.800 Nm torque at the drive shafts was realised.
This torque – amazing!
Together with the development department the requirements for the new transmission were defined:
A generous torque, short and sporty shift travels for the combustion and electric engine, a small installation space, integral functional components, increased demands with regards to the gear noise with a specific load collective for the vehicle testing.
In accordance with these requirements special tooth profiles needed to be calculated to ensure a smooth running for less noise, Furthermore a bearing concept and the respective shaft dimensioning were calculated..
For the concept of the gearbox housing the immediate peripherals such as the mountings and the attachments for all necessary functional system set a particular challenge for the package.
The production of all detailed transmission components, as well as the mounting of the whole drive unit into the vehicle had to be defined in advance.
Gears with a toothing quality 5 as specified in ISO 1328 set a particular challenge for the prototyping of sample gears.
Every single production step has to be considered in advance in the design and needed to be clearly defined in the production drawing.
The definition of all materials including all steps of heat treatment according to quality standards is key for a perfect functionality of the first prototypes.
The clarification of all interfaces in the reduced installation space is one of the biggest challenges when designing a new gearbox.
All single internal function modules with their appropriate oil system are wrapped by the complex gearbox housing.
Actuators silently activate the requested gear for driving. Together with the correct installation of the gearbox to the vehicle an almost noiseless new driving experience is provided.
Already in this first project phase a cost-optimised detailed design for all subsequent serial production steps of each single part is considered.
Regardless of whether forging technology or pressure die-casting with all its production steps is used – HC-Concept stand for functional implementations with innovative solutions.
The proof of concept starts by building the first prototype transmissions.
Engineers and mechanics assemble together the first modules and subject them to a severe functionality control.
Only if all above-mentioned tests prove positive the mounting of the entire hybrid transmission with all attachments can start.
The desired functionalities are now tested on our test benches with different boundary conditions.
The prototype is now dismantled again for inspection. The gear patterns help us analysing any faults that occur in the test and we develop specific micro tooth optimisation to improve the system.
Long lasting endurance tests with varying loads then confirm the flawless functionality of the new transmission.
We look forward to an implementation of the new transmission concept and the proof of concept by road testing.