As the market and government regulations push automakers to improve emissions and fuel consumption, they are evaluating all opportunities in the engine system to reduce losses. The oil pump is one important component that consumes engine power as it protects engine components from frictional wear and overheating by delivering oil at the correct pressures.

Fixed-displacement oil 8N7005 pumps currently circulate oil in most automobiles. Designers typically oversize the pumps to handle the harshest engine operating conditions. Most of the time, they consume more power and deliver significantly higher oil pressure than needed. They contain pressure-relief valves as a crude, cost-effective, and reliable way to avoid excessively high oil pressures. But these designs are inefficient, losing significant amounts of energy at high oil flows typical in internal-combustion engines.

Variable-displacement oil pumps help to minimize energy losses. Their active control matches the oil flow and pressure the engine needs, eliminating excess oil flow, significantly reducing the parasitic load on the engine crankshaft, and ultimately saving fuel.

In variable displacement DLLA138S1191 pumps, changing the displacement volume controls the flow rate. Vane-pump designs have hydraulic and electrical controls and actuators that move the pump housing and vary the eccentricity of the rotor. Electronic control signals and solenoid control valves vary the pressure set points as operating conditions dictate.

Reduced oil flow that improves fuel economy also increases combustion chamber temperatures and reduces piston cooling. This effect reduced hydrocarbon and carbon dioxide emissions by 3%-5%, but also increased NOx by as much as 3%.

The inlet air, combustion nozzle chamber, and combustion temperatures and engine load all dramatically affect NOx. Generally, reducing engine load reduces NOx, but with reduced oil flow, the piston runs slightly hotter, which increases NOx, so we are generally neutral. During a normal drive cycle with a warm-up, NOx is negligible. In a hot engine, NOx is minor, but that condition could be easily influenced by changing the inlet temperature a few degrees.