Gear change hydraulic actuator system
Designed for electronic twin-clutch gear change in a high-performance vehicle, the original gear change hydraulic actuator system was machined from two aluminium blocks and assembled using bolts. The hydraulic pathways were conventionally drilled and plugged, creating multiple right-angle bends. The brief was to review the part and redesign it to take advantage of the benefits of additive manufacturing.
The gear change hydraulic actuator was redesigned with the twin objectives of reducing its mass and improving the flow of fluid through the part.
Mass reduction: The side of the actuator housing was re-designed to minimise mass and make it easy to build using DMLS. The side for the solenoid housing of the device was kept as the original machined part, with the weight saving benefit being gained from machining the reverse side of the base plate used to build the actuator housing and removing unnecessary fastening points thus also simplifying the manufacture.
Fluid pathway improvement: Curved fluid pathways were designed to remove flow restrictions that occur at right-angled bends. However, in order to avoid having to support the internal walls of the fluid pathways during the DMLS build process the cross-section of the pipes was also changed to include a ‘peak’. This resulted in a smoother channel for the liquid to pass through, thus miminising the risk of cavitation.
The actuator housing side of the design optimised assembly has a theoretical mass that is 28% of the original. Therefore, the actual steel demonstration part built via DMLS is about the same mass as the equivalent original machined aluminium part. And an expected improvement in the flow rate of hydraulic fluid of between 1.5 and 2.5, as determined in a study for Red Bull Racing*.
This case study has proven that it is possible to produce a higher performing part using additive manufacturing (AM). Furthermore, as the AM technology continues to develop it is becoming apparent that the cost of producing parts in metal could soon be cheaper than certain traditional methods for low volume manufacture.
* Research undertaken by David E Cooper et al, University of Warwick, and presented at TCT Live conference, October 2009, “Assessment of Laser Sintered Titanium for Hydraulic Systems at Red Bull Racing”