Ram Deploys Unique Air-cooled Motor-Generator System

Earlier today, we found out that the 2019 Ram 1500 will be offered with a mild hybrid option dubbed eTorque. Official fuel economy figures are not out yet, but FCA estimates the hybrid system should show around a 10 percent improvement over current figures. The system employs a motor-generator driven off the crankshaft that is similar to the GM BAS system in some ways.

The novel part of the Ram system is that it does not require liquid cooling on the V8 version and is instead air-cooled, which should reduce costs significantly.

The motor-generator is mounted in front of the intake manifold on the eight-cylinder version and runs off the crankshaft via an eight-rib belt that is similar to something you might find on a supercharged engine. The traditional belt tensioner is replaced by a high pressure unit that is very similar to the one used on the GM BAS system and will likely require a hold-down tool for belt removal. The 48-volt system feeds power to a small 0.3 kWh NMC battery pack mounted on the back wall of the cab.

One major benefit of this type of system is that it fits in the same space as a traditional alternator, so packaging is not significantly affected. Air-cooling takes it a step further, since it eliminates coolant lines that would have to be snaked around the engine, and it reduces costs at the same time, allowing for a wider range of deployment. The motor electronics appear to be contained fully on top of the motor and covered by an aluminum heatsink; the only external connection is a single harness that runs back to the battery box.

The air-cooled motor was developed by Magneti Marelli, according to a patent application filed in November. The application states that the system employs a shaft-mounted fan that is internal to the motor case, which works in conjunction with the heatsink mounted on top without requiring the deployment of a liquid cooling system. In some versions of the system, two internal fans are deployed so that one cools the motor section while the other cools the power electronics mounted on top.

Although a power figure for the motor was not shared, we can deduce that is less than 12 kw (16 horsepower) based on the description on the Magneti Marelli page (which states that MM motors above 12 kw use water cooling, while all of the air-cooled motors are rated for less than that). This also means the motor on the V6 version is likely more powerful, as it does employ a liquid cooling system.

I expect the V6 version will see a larger benefit while the V8 version will be easier and cheaper to maintain down the road. Both version should offer some improvement and we look forward to seeing the official ratings soon.

[Images: Bozi Tatarevic/TTAC, U.S. Patent and Trademark Office]