The Roller Bearing Engine: A Cost Effective Contribution to CO2-Reduction

Abstract

The investigations and developments described in this article substantiate the potential for reduction of fuel consumption and the general feasibility of a roller bearing crank train in an internal combustion engine. An improvement of fuel consumption of 5.4% (NEDC) resulting from reduced friction was proven on the basis of a given 1.6L 4-cylinder plain bearing engine converted to roller bearings. By means of subsequent calculations and simulations, the parameters for optimisation of the engine acoustics and durability were identified. Based on these findings, an advanced test engine was set up. Measurements with this generation 2 roller bearing engine demonstrate the expected significant improvement of NVH behaviour. In parallel to the investigations with the generation 2 prototype which had to be a compromise with regard to robustness due to the requirement for a quickly realisable and feasible application, a completely new roller bearing bottom-end concept (generation 3) was developed. This new design meets the main requirements of optimal roller bearings while also taking the boundary conditions for high-volume production into account. The essential attributes of this generation 3 roller bearing crank train concept are the single-piece conrod and main-bearing pedestals which are threaded onto a crankshaft with detachable counterweights. The extra cost of EUR 50.- to 70.- for these roller bearing engine concepts is on a low level compared to the achieved reduction in fuel consumption.

Micro-Pitting and Wear Assessment of PAO vs Mineral-Based Engine Oil Operating under Mixed Lubrication Conditions: Effects of Lambda, Roughness Lay and Sliding Direction

“…Typically, the total engine friction is responsible for more than 10 percent of fuel energy losses in passenger cars [1]. By replacing sliding bearings with rolling element bearings, the engine efficiency can be improved up to 5 percent or more and, therefore, can directly reduce CO 2 emissions [2][3][4]. However, in order to successfully employ rolling element bearings, further investigations are required for a smooth and durable operation.…”

“…Example of wear measurement from Test 1 showing the cross-section of a wear track. This results in wear damage, = 231 µm 2 , after normalization , = 284 µm 2 , which correspond to the normalized loss of material in volume, , = 0.018 mm3 .…”

Tribological characterization of potential crankshaft bearing steels for roller bearing engines

“…3 However, there is still great potential to reduce the frictional losses in ICEs by, for example, replacing traditionally used sliding bearings with rolling element bearings, which offer a 5 percent or more improvement in energy efficiency. [4][5][6] In this case, the inner raceway for the rolling elements is found directly on the crankshaft and the outer raceway features a cracked/split outer ring. Both the rolling elements and the outer ring are made from a traditionally used bearing steel grade, i.e.…”