Design and performance evaluation of a rotary flow control valve for independent metering hydraulics.

Abstract

Off road heavy machinery is the second largest contributor to air pollution in terms of the levels of fossil fuel consumption after road cars. This is partly attributed to inefficient power hydraulic systems used to drive these machines’ tools or instruments. A relatively recent idea of an independent metering technology has become a major topics in improving efficiency, reducing fuel consumption and saving energy. Current research and development of independent metering applied to fluid power systems enables energy recuperation capabilities of hydraulics. However, actual industrial implementation cases are still rare, especially in application requiring high flow rates. Flow control valves are used in flow regulation and controlling of hydraulic actuators’ speed. The speed control occurs through throttling, which causes large power losses. Moreover, the substantial flow forces acting on the throttling parts of the valve in high flow rate regimes has resulted in the application of sophisticated multi-staged servo valves. An alternative one-stage design can resolve these issues, but such proposals and studies are still scarce in the literature. This research looks at new design ideas as the means to improve hydraulic valve performance and efficiency. The novelty is also to enable single staged valves to be used in high flow rate applications. The main approach is to simplify and perform a complete redesign of the valve geometrical structure to replace the existing spool and seat valve configuration. The novel design proposed in this thesis is based on a rotary tubular structure, which is less bulky and much lighter. The focus of this investigation has been on the study of the flow characteristics and fluid structure interaction of the new valve’s moving parts using a combination of theoretical, simulation-based and experimental studies. A prototype of the final design was manufactured and tested to validate the simulated data. Test results provided a good experimental validation of analytical and numerical models employed in this investigation. Detailed analysis of the performance of the new suggested valve proved its viability as a strong candidate to replace the existing in-efficient industry standard spool and seat valves. The metering characteristics of the new valve has demonstrated that alternatively designed one-staged flow control valves can create smaller pressure drops, hence, consume less power than the industry standard benchmark. The thesis presents the research, investigation and detailed analysis of a novel unconventional valve design suitable for the independent metering architecture. This research demonstrates the feasibility of the independent metering architecture for use in high flow rates applications. This research further consolidates the position of this new valve can have within the fluid power industry, further expands its range of application paving the way for industry adoption to replace old valves with a new and more efficient valve system.