With the increasing regulatory stringency on emission reduction and efficiency improvement, the automotive industry has experienced a significant shift in the hardware platform. Among technology candidates, hybrid technology is still considered one of the most viable approaches to meet the regulation requirement (both emission and efficiency) at an affordable cost to both the customer and the manufacturer. New engine operating characteristics are expected in hybrid applications which would potentially result in different performance requirements for the engine oil. Therefore, it is crucial to understand those characteristics of a hybrid powertrain, from which the insights of fluid requirements can be derived.
A hybrid vehicle test study was conducted to evaluate the engine operation of different kinds of hybrid platforms. The hybrid operation has been well characterized by thoroughly analyzing parameters on each engine. The temperature profile from each hybrid powertrain was evaluated and used to illustrate the impact of the driving cycle on fluid properties. It was found that the driving cycle is a very effective tool to deepen technical understanding of the interactive operation between the internal combustion (IC) engine and electric motor in a hybrid powertrain. This interactive operation will ultimately determine the engine performance and fluid working environment.
Based on the acquired knowledge and insights from the vehicle testing, a controlled engine study was conducted to understand the impact of different operating parameters on fuel and water dilution under various engine operating conditions. Oil analysis results indicate that oil samples generated from the engine tests contain a wide range of water and fuel dilution levels, representative of the oil samples found in a real-world application. In addition, performance testing conducted on the oil samples provided greater understanding of hybrid engine operation on fluid performance requirements.