Altair ProductDesign selects Parker Hannifin’s series hydraulic hybrid drive system for advanced transit bus demonstrator
Altair Engineering, Inc., has selected Parker Hannifin’s RunWise series hydraulic hybrid drive system (earlier post) for its BUSolutions project. The system will enable the new advanced bus platform to achieve 45-70% increased fuel economy over average diesel powertrains and more than double the fuel economy improvement of hybrid-electrics, contributing to an overall lower cost of ownership for transit authorities and reduced emissions.
The Runwise hybrid drive system is built around the company’s proprietary Power Drive Unit (PDU), C24 Variable Displacement Bent-Axis Hydraulic Pump/Motors, and Composite Bladder Accumulators—all designed specifically for high power, high start-and-stop applications. An onboard controller coordinates pumps, hydrostatic motors and accumulators to power the vehicle when in hydrostatic mode during start-and-stop operation.
Instead of solely using power from the engine, accumulated energy from the vehicle’s braking system is stored and used to power the vehicle each time it accelerates.
The RunWise Advanced Series Drive system features two-speed hydrostatic drive (low speed 0-25 mph and high speed 26-45 mph) for urban driving, combined with mechanical direct drive for efficient operation at highway speeds (46-60+ mph).
BUSolutions is a collaborative effort between public and private entities to research, develop and commercialize advanced transit bus systems that, compared with conventional buses, are significantly more fuel efficient, have lower operating and maintenance costs, are competitively priced, and can operate without updating the infrastructure of existing transit authorities.
We decided to use hydraulic hybrid technology for the bus since it recovers more than three times the brake energy and an overall 30 percent lower cost of ownership than any electric hybrid technology available today. Of all the hybrid hydraulic products evaluated, the Parker system was the clear choice because it uses well proven technologies in a system that has been tested and validated through extensive field trials. It also can easily integrate with other technologies in the bus platform and can be implemented quickly within the required timeline.—Tim Smith, director of design engineering for Altair ProductDesign
Fabrication of the first technology-demonstrator bus body structure was completed in April, and final assembly is well underway. Hybrid driveline system commissioning will be completed in mid-November, with a technology demonstration event planned for early December. Once complete, Altair will conduct testing to validate the reductions in fuel, maintenance and lifetime-operation costs. Any necessary improvements will be incorporated to ensure the design is production-ready, ensuring a smooth transition of the program into a commercialization phase.
Since BUSolutions launched in 2005, Altair has worked closely with local transit authorities, the Suburban Mobility Authority for Regional Transportation (SMART) and the Detroit Department of Transportation (DDOT), to ensure the newly designed bus platform will meet regulatory requirements and address the needs of bus drivers and riders.
Altair also established the BUSolutions Advisory Board to offer insight into broader community needs, as well as perspective on actual ridership issues and public-interface ergonomics. As a result, Altair ProductDesign successfully completed the bus structure engineering incorporating design principles that will enhance the rider experience.
Additionally, BUSolutions has strategically partnered with regional and global high-tech manufacturers that will help to incorporate state-of-the-art components and technologies from the transportation sector. Program sponsors include Arvin Meritor, Parker, PRAN, Sika Corporation, Meritor Wabco, Alcoa Wheel Products, Carrier Corporation, LAAD Industries, Pretoria Transit Interiors, Shaw Development, Tenneco, USSC Group and Williams Controls.