HOW A TURBOCHARGER WORKS
A significant difference between a turbocharged diesel engine and a traditional naturally aspirated gasoline engine is the air entering a diesel engine is compressed before the fuel is injected. This is where the turbo charger is critical to the power output and efficiency of the diesel engine.
It is the job of the turbo charger to compress more air flowing into the engine’s cylinder. When air is compressed the oxygen molecules are packed closer together. This increase in air means that more fuel can be added for the same size naturally aspirated engine. This then generates increased mechanical power and overall efficiency improvement of the combustion process. Therefore, the engine size can be reduced for a turbocharged engine leading to better packaging, weight saving benefits and overall improved fuel economy.
How Does a Turbocharger Work?
A turbo charger is made up of two main sections: the turbine and the compressor. The turbine consists of the turbine wheel (1) and the turbine housing (2). It is the job of the turbine housing to guide the exhaust gas (3) into the turbine wheel. The energy from the exhaust gas turns the turbine wheel, and the gas then exits the turbine housing through an exhaust outlet area (4).
The compressor also consists of two parts: the compressor wheel (5) and the compressor housing (6). The compressor’s mode of action is opposite that of the turbine. The compressor wheel is attached to the turbine by a forged steel shaft (7), and as the turbine turns the compressor wheel, the high-velocity spinning draws in air and compresses it. The compressor housing then converts the high-velocity, low-pressure air stream into a high-pressure, low-velocity air stream through a process called diffusion. The compressed air (8) is pushed into the engine, allowing the engine to burn more fuel to produce more power.
Better Fuel Efficiency Through a Better Oil Pump
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 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.
Providing Customized Oil Flow
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 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.
Automobile OEMs adopted these types of pumps in 2011, applying them in engines for high-end vehicles in Europe. Although research has evaluated the fuel-economy benefits of reduced oil flow from a torque-reduction perspective, the industry lacked information about its control, use, and thermal interactions with other engine systems.
As part of an industry- and university-consortium project partially funded by the UK Technology Strategy Board, researchers at the University of Bath, Bath, UK, and Ford Motor Company, Detroit, MI, thermally tested variable-displacement oil pumps to gain insight about performance and oil pumping speed. The group evaluated vane and rotor pump designs in an active 2.4-L diesel engine on an engine stand at many different operating conditions and found that fuel economy benefits warrant the pump expense.
Understanding Oil Coolers
When engine output rises beyond a certain threshold per liter of displacement, an oil cooler becomes more important, critical even. There is a lot to the selection and installation of an oil cooler, so to find out more, we caught up with Zac Beals, a technical sales representative with Setrab USA, a Swedish company that specializes in a full range of heat exchangers and radiators for OEM applications, and oil cooling for motorsport. There are right and wrong ways to add an oil-cooling system, based on application and a number of other factors, but there are two key tenets to follow when adding an oil-cooling system: get expert help and don’t skimp on materials.