Study on An Application of Digital-Hydraulic Pressure Reducing Circuit to Pilot-Pressure Supply Circuit of Construction Machinery

<p>In recent years, construction machinery has become increasingly electronically controlled. As a result, the number of electronic-hydraulic components such as proportional solenoid valves in hydraulic circuits of construction machinery has increased, and consumption flow of a pilot hydraulic pressure source to drive these components has continued to increase. The pilot hydraulic source consumes approximately 2 to 3% of engine horsepower in a typical excavator operation, and more energy-efficient methods are desired.</p><p>Digital hydraulic pressure reducing circuits are an example of Switched Inertance Hydraulic Converters (SIHC) and have the potential to achieve high energy efficiency because they utilize an inertia of the hydraulic oil in an inertia pipe to reduce pressure without using a throttle like a conventional pressure reducing valve.</p><p>In this study, the digital hydraulic pressure reducing circuit is applied to the pilot hydraulic pressure source that supplies pilot hydraulic pressure by reducing the hydraulic pressure of the main circuit that drives work equipment, etc. A high-speed switching valve is a key component of the digital hydraulic pressure reducing circuit.</p><p>The authors assumed a servo valve as a high-speed switching valve in consideration of its accessibility in experiments. However, there are issues in contamination resistance, vibration resistance, cost, etc., to install the servo valve in construction machinery. The authors have developed a new rotary valve that solves these problems and has the potential to meet the high pressure requirements of the main circuit of construction machinery. This paper describes the structure of the valve and the results of analysis and stand-alone experiments. Furthermore, we report on the effects of the proposed rotary valve on the controllability and pressure reduction efficiency of the pilot pressure circuit of construction machinery when the rotary valve is applied to the pilot pressure circuit.</p>