Development of Intercooler Hose for Future Engine 2020-01-0236
Turbocharged diesel engines with an intercooler are widely used in modern heavy-duty commercial vehicles to achieve both cost performance and durability. These engines have low CO2 emissions due to their high thermal efficiency, and are essential to the movement of people and goods. Given the high compression ratio and supercharging requirements of diesel engines, further improvements in thermal efficiency require enhancing the performance of existing intercooler hoses. Intercooler hoses made of fluororubber (FKM) and silicone rubber (VMQ) have high heat resistance and durability. However, future diesel engines will be subject to more severe operating conditions. This research identified the deterioration in the mechanical properties of FKM in hot environments as an issue to resolve for intercooler hoses in future engines. Specific improvement efforts focused on the low heat resistance of crosslinking points inside FKM. The current crosslinking method cannot be changed because of its excellent acid resistance. Therefore, the formation of new networks distinct from the crosslinking network was induced, and the improvement in physical properties was confirmed. The gelation of a carbon black reinforcing agent was used to form the new networks. Changing the types of polymers, blending, and mixing conditions allowed the development of a new FKM that meets the targets. A prototype hose was made using the newly developed FKM, and a hose bench test was conducted. There were no problems with the trial production hose after the bench test. This research made the following points clear. First, the material properties of the FKM when heated are insufficient to meet the environmental requirements of future engines. Second, efforts to improve mechanical strength when heated while maintain environmental resistance achieved the development targets by applying carbon gel to reinforce the network.