Aramco? Isn’t that the Saudi Arabian Oil Company—aka “the world’s largest oil producer”? What is it doing designing a Dedicated Hybrid Engine (DHE) powertrain? Well, it’s heavily vested in keeping combustion engines relevant, and with hybrids attracting more buyers than battery-electric vehicles in some regions, a better hybrid “mousetrap” could be just the thing to keep folks queuing up at gas pumps indefinitely.
Also note this DHE isn’t Aramco’s only dog in the hybrid fight. Remember Horse Powertrain, the joint venture formed when Renault and Geely/Volvo spun off their combustion-engine operations? Those companies each hold 45 percent of the new JV, and Aramco owns the remaining 10 percent.
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Horse specializes in turnkey engines or range-extenders that allow companies to quickly and easily hybridize a combustion platform or add a range-extender to an existing battery-electric model. Aramco’s DHE looks to answer the question, “If you were designing the ideal new hybrid powertrain from scratch, what would it look like?”
Hybrid Synergy Drive for 2030?
An engine connecting to a motor-generator via planetary gears sounds very Toyota. First big difference: DHE features one such motor-generator-planetary setup at each end of the crankshaft. Second big difference: The engine itself is radically re-envisioned with laser focus on thermodynamic efficiency and cost reduction, leveraging a strong-hybrid duty cycle that seldom demands low-rpm torque or high-rpm power from the engine, but instead can run for extended periods occupying an “efficiency island” in the load/speed operation graph.
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The Engine
The initial proof-of-concept features a 1,599cc inline three-cylinder engine. To keep it notably compact, it’s a cam-in-block pushrod design. To keep it simple, it features a monoblock casting with no separate cylinder head and uses just two valves per cylinder with no variable timing or lift. To minimize friction, there are no journal bearings—the crank, camshaft, and connecting rods all ride on roller bearings, and the crank is offset 12 millimeters from the cylinder-bore centers to reduce piston side loading. There’s also no accessory drive; all auxiliaries including the water pump operate electrically on demand.