A Study on a New Independent Metering Valve for Hydraulic Boom Excavator

Abstract

Nowadays, hydraulic excavators are an indispensable part of the construction industry; however, conventional hydraulic excavators consume a great deal of fossil fuel and release a large amount of pollution emissions into the environment. This causes many unwanted costs, therefore, effective solutions are required to solve the above-mentioned problems. In this paper, a new independent metering system is proposed to improve energy-saving and reduce costs of a conventional system. In detail, a directional valve is used to control movement and three electro-hydraulic poppet valves are integrated to adjust the flow rate at the inlet and outlet ports of the boom cylinder. In addition, a control strategy based on the coordination between the speed of the pump and the opening area of the spool valve is designed to improve the performance of the system. Specifically, the valves are controlled based on the strategy that the meter-in valve is opened fully to reduce throttling losses and that the meter-out valve is controlled to reduce leakage. The speed of the pump is adjusted according to the feedback position signal. To demonstrate the effectiveness of the new configuration, a real test bench of the boom system was built under laboratory conditions. From the experimental results, the new independent metering valve system not only works with a high tracking precision, but it also reduces energy consumption. Compared with a conventional independent metering system, the fuel economy of the proposed structure can achieve a reduction of approximately 6.5%.

Research on Design and Control Strategy of Novel Independent Metering System

“…The energy saving and response characteristics of the system were proved by experimental research. Nguyen et al [5] investigated the use of three 2/2 proportional valves and a 4/3 directional valve to build an independent metering system. Taking the boom of the excavator as the carrier, compared with the traditional independent metering system, its energy saving can be improved by 6.5%.…”

Working Performance Improvement of a Novel Independent Metering Valve System by Using a Neural Network-Fractional Order-Proportional-Integral-Derivative Controller

“…Due to the high energy-saving efficiency demonstrated in previous studies [45,46], the NIMV system continues to be used to investigate the effectiveness of the proposed controller. Figure 1 displays the NIMV system consisting of the following components: an electric motor (1) that drives the main pump (2) to supply the oil for the system, the NIMV circuit (5) with three proportional valves (K sa , K sb , K ab ) and a directional control valve (K d ), a relief valve (3) for protecting the system from excessive pressure, a check valve (4) to protect the pump from system return pressure, a boom cylinder (6), and the controller (7).…”

“…where η E is the energy consumption efficiency. In addition, the energy saving of the proposed method compared with another control approach, such as PID and FOPID, is calculated as follows [45]:…”

“…Specifically, the neural network was used to tune five parameters in the FOPID controller under the effect of external factors such as noise, leakage, and throttling loss. In addition, the proposed controller was applied to the NIMV, which utilized three proportional valves and a directional valve to control the boom cylinder (the NIMV system has been demonstrated to not only better track precision and energy saving but also work similarly to the IMV system in our previous studies [45,46]). The primary contributions of this study are outlined as follows:…”

High Tracking Control for a New Independent Metering Valve System Using Velocity-Load Feedforward and Position Feedback Methods

“…However, the IMV system has two problems that make it meet an obstacle for applying in practice. Firstly, the cost of the proportional valve causes a high cost for the system [23]. Secondly, controlling four valves is particularly challenging because of various types of nonlinearities in hydraulic systems [24].…”