For the first time ever a combined delegation of Punch Powertrain and Stellantis performed an extensive large scale joint winter testing programme for the DT2 transmission. The delegation consisted of approximately 75 people in total of whom 13 people were Punch Powertrain employees from various areas of expertise. The Punch team included validation engineers, controls engineers and calibration engineers (from both PPS and PPE departments). The mix of different competences of the delegation members resulted in fruitful test execution and successful knowledge transferral between the different teams, specifically with respect to controls and vehicle integration.
Previously, Punch Powertrain already ran successful winter (and summer tests) on their innovative transmissions. With this wintertest event the complete powertrain was tested inside the customer’s vehicles in extreme conditions. The scale of this combined testing programme is a first and enabled both companies to perform their validation plan. In addition to the predefined tests, the Punch engineers were also able to provide support to Stellantis and solve transmission or vehicle issues as they emerged. The close collaboration between the two companies ensured a smooth and agile follow-up.
During the four-week operation twenty vehicles were put to the test under extreme conditions. In order to simulate the worst case scenarios, the vehicles were cooled overnight to minus 35° Celsius in climatic chambers.
Due to the operational scope and the involvement of the large number of specialists from both Punch and Stellantis, the teams were able to perform extensive tests and maintain a close line of communication throughout the process. The limited timeframe required a thrustful cooperation, and with efficient planning the teams succeeded in combining different tests which facilitated and expedited the research.
Testing various scenarios
During the trip a certain number of tests needed to be performed according to a validation plan. This plan serves both internal, customer and legal requirements. The initial part of the test consists of basic functionality assessments, along with standard manoeuvres that are monitored under various driving conditions. The purpose of the functional tests is to verify that the transmission’s functions and machine learning capabilities also operate properly under freezing conditions. The extremely cold temperatures have an impact on the physical parameters of the transmission. For example, the oil can change in viscosity which requires a different clutch operation to guarantee the shifting experience remains the same regardless of the temperature. The tests also include hardware validation such as transmission warm-up, park lock and oil pumps. To improve the driveability there are tests performed related to clutch, shift, and hybrid performance. Functional safety tests are another critical component of the validation plan. In addition to these standard tests, safety critical failure scenarios are also put under scrutiny. Faults are injected to the transmission system on purpose to simulate defects. This can include hardware failure, or communication interruptions with the vehicle or powertrain.
The vehicles need to be tested for all possible conditions and against all possible errors, not just under regular driving conditions. It’s also imperative to check how the transmission responds to ABS or ESP activation. The features are not only tested against extreme temperature circumstances but also against a range of road surface conditions.
During the trip, the Punch team held daily stand-up meetings to review the performances and to further anticipate upcoming test scenarios, in addition to regular meetings with the Punch team at the offices in Sint-Truiden and Eindhoven. Stellantis also performed daily meetings with the Punch team to ensure a transparent communication flow.
Future alliance to ensure a successful market launch
With the fruitful results of the trip, Stellantis and Punch Powertrain are looking forward to embarking on similar testing sessions in the near future. The next mission is scheduled in five weeks, (mid-April) and an extensive testing programme is being set-up for the summer in Spain. It is crucial that the same cooperation level can be maintained until the start of production.