Investigation and Implementation of Mechanically Actuated Valves for Digital Hydraulic Units

Tyler Helmus, Purdue University

Abstract

Pumps are ubiquitous in fluid power systems. As hydraulic systems get smarter and more versatile, the pump needs to follow suit. While the current state-of-the-art pumps are capable of high efficiency at maximum displacement, reducing the displacement results in significant reductions in efficiency. Work done previously with digital displacement strategies using electrically-controlled valves demonstrated an option to improve these characteristics of traditional pumping methods. However, the complex and costly valve controls needed to implement the system prove impractical in some situations. Additionally, the electrical valves used in this system have limited speed, consistency, and flow area. It was determined that a mechanically-actuated valve (MAV) system could be implemented to reduce the control complexity and cost while maintaining most of the benefits of digital displacement. The mechanical system consists of variable geometry cams to actuate the valves, allowing for greater consistency in actuation, proportional speed of actuation to pump speed, and larger valve flow areas. This system can achieve variable displacement digital hydraulic pumping with no electrical input or required sensors. The MAV concept was theoretically investigated, validated in simulation, and proven in the building and testing of a simple prototype unit. The MAV pump performed comparably to the previous prototype at full displacement and achieved a 10% higher efficiency at 50% displacement. Though this prototype was limited to flow-diverting pumping, this technology could be expanded to achieve four-quadrant operation. Considering the successful prototype testing and theoretical potential of this concept, further investigation is necessary to fully determine the capabilities of the MAV system.

Degree

M.S.E.

Advisors

Lumkes, Purdue University.

Subject Area

Mechanical engineering

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