New Method to Achieve High Hydraulic Pressure and Improved Gear Pump Performance in Active Height Control (AHC) System

Vehicle weight reduction is becoming more and more important as increasingly stringent fuel economy regulations are introduced around the world. This development improved the hydraulic gear pump performance of the next-generation Active Height Control (AHC) suspension and achieved significant weight reduction of 5 kg by eliminating the auxiliary pump accumulator. To realize the necessary high-pressure with a high flow rate, the sealing performance of the pump at the tips of the gear teeth is very important. This was achieved by developing “breaking-in” technology that shaves away the aluminum housing using the gear teeth and creates zero clearance between the teeth tips and the housing. To reduce the frictional loss torque of the pump, which was identified as an issue of this technology, it was necessary to completely shave away the initial clearance in the breaking-in process. The mechanism for the state where the aluminum housing had not been completely shaved away was explained by focusing on the tooth tip stress during the breaking-in process. As a result, the design requirements were clarified. This technology was incorporated into the product design and manufacturing process. The developed technology was adopted for mass production after incorporating it into the product design and manufacturing process and confirming that it improved performance without increasing cost.