Stellantis, a major global automaker with significant operations in Canada, may be shifting focus to adapt planetary gear hybrid systems—currently utilised in vehicles like the Chrysler Pacifica Hybrid plug-in hybrid minivan—to more rugged vehicles, according to a recent patent filing.
The Chrysler Pacifica Hybrid employs a planetary power-split system to manage its 3.6-litre V-6 engine and dual electric motors, which also function as generators for propulsion. However, a patent filed with the United States Patent and Trademark Office (USPTO) in July 2023, and published on February 6, suggests that Stellantis recognises these systems aren't perfect for every application.
The filing highlights issues that arise when combining planetary-gear systems with the transfer cases typical in mechanical four-wheel-drive systems. These problems include rough shifts between high and low range, difficulty engaging low-range gears when the vehicle is stationary, and challenges synchronising shifts in low range. Such issues may explain why Stellantis opted for a different plug-in hybrid system in models like the Jeep Wrangler 4xe and Grand Cherokee 4xe. These SUVs maintain mechanical four-wheel-drive systems akin to their non-hybrid versions, paired with 8-speed automatic transmissions. In this configuration, one electric motor integrates with the transmission, while a smaller motor-generator attaches to the engine's crankshaft.
To address these challenges, Stellantis proposes a hybrid solution that combines a 2-speed transfer case from traditional four-wheel-drive systems with a planetary-gear power split configuration. The patent details the use of a disconnect device to uncouple the engine and electric motors from the driveline, employing motor torque to synchronise the input and output shaft speeds of the transfer case.
This innovative approach could be particularly beneficial for future Jeep hybrid and plug-in hybrid models, aiming to preserve their off-road capabilities while potentially enhancing fuel efficiency beyond the current 4xe system. The existing 4xe plug-in hybrids have seen strong sales, and there are indications that Jeep is exploring hybrid models without charge ports to offer alongside them in the U.S. market.
For Canadian drivers, this development could mean more efficient and capable hybrid SUVs in the near future. While specific Canadian pricing and availability details aren't provided, it's worth noting that vehicles like the Jeep Wrangler and Grand Cherokee are already popular in Canada. Potential buyers should also stay informed about provincial rebates and federal iZEV incentives, which can significantly affect the overall cost of new hybrid and electric vehicles.
As Stellantis continues to innovate, Canadian enthusiasts may soon have access to rugged, efficient hybrid vehicles that combine the best of both worlds: off-road performance and improved fuel economy.