As heavy duty diesel engines evolve, manufacturers are using more exhaust gas recirculation (EGR) in the combustion process. Our 48V TVS EGR pump improves engine efficiency by enabling the use of a high efficiency wastegate turbocharger, matched to the engine for fuel economy and performance, rather than utilizing a variable geometry turbo for driving EGR.
The TVS EGR pump is driven by a 48-volt electric motor, making it completely independent from engine speed and significantly more controllable than pump-less EGR systems. TVS technology enables EGR flow in operating regions where it wasn’t possible to drive flow before and provides more accurate EGR flow rate control for better combustion and emissions management.
The TVS EGR pump leverages our experience with superchargers and positive displacement pumps. While the two are similar, a supercharger generates a high boost with average pressure ratios of 2.0 to 3.0 for many applications; an EGR pump uses a shorter rotor assembly and lower twist to produce flow just slightly above the intake pressure, or a pressure ratio of 1.05 to 1.50.
The setup allows the turbocharger to be optimized for maximum efficiency boosting without being compromised by the need to drive the EGR, which allows customers to utilize a highly efficient and lower-cost fixed geometry turbo (FGT) in place of variable geometry turbocharger (VGT) technology. In an engine designed with an efficient FGT, pumping work is decreased, enabling better fuel economy.
In addition, the pump allows engine manufacturers to eliminate a number of expensive components, including the turbocharger’s variable geometry turbine and actuator, the EGR valve, and potentially the EGR flow meter. Because the pump is a positive-displacement device, the engine controller can use the pump speed signal as well as other Controller Area Network (CAN) sensor data to accurately calculate EGR mass flow rate.
The pump’s fast response and independence from engine speed and load enable a wide range of EGR calibration over the entire engine operating map and can provide more precise flow rate control, especially during engine transients. With TVS EGR pump’s full-authority flow rate control, engine manufacturers will be able to meet new emissions regulations with fewer compromises to fuel economy.
Additionally, because the pump can maintain any desired EGR flow rate, it can play an important role in emerging diesel engine efficiency strategies such as Miller Cycle operation, which leverages late intake valve closing for added fuel efficiency, and other key operating functions.
This new EGR pump leverages the precision air control of our TVS technology to allow a high volume of exhaust gas recirculation to dilute the air mixture with low pumping loss, while also lowering in-cylinder temperatures.