The Transforming Transmissions

The Transforming Transmissions

Decoding Technology October 2019 Transforming Transmissions

Transmissions are the prime pathways of power transfer and their efficiency influences the energy management architecture in an automobile

Techniques of transmitting energy from the engine to the wheels have been changing with the change in mobility prime movers. The conventional transmissions have different variants starting from the basic manual, the auto-shift manual, dual-clutch, the semi-automatic, automatic and so on. The components, sub systems, materials for weight efficiency and operational control architectures are varied and improved to be more efficient with better response times. The clutch, its materials and power-transferring mechanisms have innovative solutions that have changed the game in power transmission of vehicles.

Fast forward to e-mobility and hybrids, as well as other prime movers. The philosophy of transmission design and development has changed completely. In hybrids, with an electric motor sandwiched between the rear face of the engine block and the transmission, mobility engineers have to manage heat transfer, manage the control architecture for a smooth engagement, and ensure that power transfer is seamless to the driver to avoid jerky shifts to occupants. Though it may look trivial, it is to be ensured that the microns of spacing between electric motor and clutch, and the co-centricity of engine crank shaft, rotor and the transmission are within the alignment variance. This ensures avoidance of powertrain bending and breakage during transmitting power to the wheels. There are multiple techniques for thermal management in 3 different heat transfer modes that have to be balanced to ensure longevity of the stator and rotor of the traction motor. The knack is to select the best technique for the right hybrid application through digital engineering.

In e-mobility, the concept of transmission has entirely changed. Traction motors integrated within the wheels in certain type of hybrids literally have a water downed transmission mechanism. Other EV configurations do not have any trace of conventional type of transmissions. Does that mean that the transmissions and the relevant technologies will disappear soon? Of course not, the multitude of powertrains will ensure that the variety of transmissions co-exist.

Conducting a Life Cycle Analysis in a vehicle to calculate the carbon footprint has indicated that transmissions play a major role in reducing the carbon footprint. As such, in conventional powertrain vehicles lower the carbon footprint better it is for the consumer. Consumers today seek vehicles that give them a better carbon credit so they are less burdened with taxes. With this changing paradigm, transmissions design and development need newer insights and an approach that is away from the usual. LCA also indicates that EVs have a lower influence from transmissions on the carbon footprint. As such, in the new generation of powertrains the end to end carbon footprint of a vehicle is significantly lower.

From a manufacturing complexity, current generation of conventional transmissions are simpler. This is holistically due to the design, materials, tools and methods, and the programmed delivery through logistics. The percentage wastage toady is lower than it was a decade ago. Further, the lubricants in transmission that enhance gear efficiency and longevity have changed due to newer carbon molecules and biotechnology innovations. The greener aspects of transmissions have evolved for better, at least 18% better than a decade ago.

Eventually, it is more than transmitting power to the wheels; it has to be seamless to the driver, and have lower impact on carbon footprint. Transmissions, conventional or otherwise, continue to play a significant role in enhancing fuel efficiency of vehicles. Keeping a focus on reducing weight, thermal management and the energy loss to a minimum is a winning model for the mobility fraternity and that is sustainable.