حالت های شکست در هیدرولیک های منطقه ای برای ماشین آلات ساختمانی Modes of Failure in Zonal Hydraulics for Construction Machinery

I. INTRODUCTION Hydraulics is a traditional application science widely used in industrial, aeronautical, and off-road mobile applications due to its superior power density and mature technology. Construction machinery examples are illustrated in Figure 1. Recently, hydraulic technology has mainly developed incrementally. However, the field of construction machinery will benefit from a new architecture with improved efficiency and high performance level during lifetime; in order to achieve this, built-in functionalities, such as fault tolerance and predictive maintenance are required. Fault tolerance is a demanding topic in case of off-road and construction machinery. According to [1], 15 % of failures are concentrated in sensors and 10 % in valves, as there are no 100 % fault-tolerant commercial valves in case of off-road machinery. In [2], the failure rate in hydraulic circuits was studied with four different mobile working machines during three years. The authors in [2] found that the hydraulic valves failed 69 times, pumps 34 times, hydraulic motors 237 times, cylinders 318 times and hoses 90 times in 106 hours. Failures were caused by contamination, wearing, external damages, material error, maintenance error or excess load. The off -road machine cases are not so critical compared to airspace, oceanic and other extreme applications, however, faults still create unpleasant financial losses and significant time delays in manufacturing or other performing tasks. Therefore, valves and sensors are critical components in conventional systems, independent from the type of application. Many applications can benefit from valveless systems, such as pump-controlled systems with “smart” use of electric drive. Therefore, failure modes of zonal hydraulics systems are investigated by means of review of the current literature. First, this paper introduces zonal hydraulic concepts in detail, demonstrates examples of pump-controlled systems, highlighting the effects of the components. Secondly, the review was designed to cover hydraulic and electric system components. As a result, conclusions are drawn considering designed pump-controlled systems and their benefits for the construction machinery.