Читать книгу Hydraulic Fluid Power - Andrea Vacca - Страница 12

Hydraulic control systems are used across many engineering applications to provide motion and force control of mechanical systems. With respect to competing technologies for transmitting mechanical power (i.e. mechanical drives or electrical drives), hydraulic drives offer favorable characteristics from both the power to weight ratio and control perspectives. State‐of‐art hydraulic systems can be up to 1 order of magnitude lighter than electric systems with the same power (or torque) level. Also, compared with mechanical drives, hydraulic systems offer a greater layout flexibility thanks to the versatile design of the piping or hose system that connects the hydraulic components. Hydraulic drive technology also easily offers solutions for advanced actuator control, in terms of output velocity and force, motion reversals, and safety functions. These mentioned features are particularly advantageous in applications involving the transmission of large amounts of power. For this reason, hydraulics is a consolidated technology in many heavy‐duty applications, in manufacturing industry (hydraulic presses, molding machines, machining robots, etc.), and in mobile applications (construction, agriculture, aerospace, military, and marine). Recent progress in component miniaturization and interfacing with electronic controls have also brought hydraulic systems into emerging fields such as biomedical engineering (surgery robots, patient transfer and rehabilitation devices, etc.).

However, compared with other technologies for power transmission and motion control, hydraulics has some significant drawbacks, the most important one being the inevitable presence of energy losses. Depending on the application, other disadvantages might affect hydraulic systems, such as the high influence of temperature on the system behavior, the possible insurgence of leakages, and the limited duration of the working fluid, due to aging or contamination.

From the considerations made above, it appears clear how a “best technology” for transmitting mechanical power does not exist in absolute. The most suitable technology for a given application is usually the result of a compromise between initial and operating costs, functionality, durability, reliability, and safety. Consequently, it is very important for a designer to be fully aware of the possible technological alternatives that can be available for the system under evaluation from the early design stages. Too often a designer chooses the technology for which she/he has more experience, without considering alternatives. Due to the chronic lack in fluid power education in engineering schools, hydraulic control technology is seldom the preferred designer's choice. This book aims to fill this gap by educating current and future generations of designers on the potentials of hydraulic control technology.