High-speed on / off valve (HSV) has been widely concerned in the field of hydraulic engineering, mainly focusing on improving its dynamic characteristic. However, relatively little attention is paid to the adjustment of HSV switching characteristic, which limits the applications of HSVs in some specific systems. Therefore, an advanced pulsewidth modulation (PWM) control algorithm is proposed in this article to change the dynamic behaviors of the experimental HSV and makes it adjustable in a wider scope to adapt to more applications. Applying the voltages of opening preduty ratio and holding duty ratio, the opening initial current and closing initial current can be generated, respectively. Combining with the voltages of opening duty ratio and closing duty ratio, the opening and closing dynamic behaviors can be fully controlled and adjusted in a wide range. The effectiveness of the proposed algorithm is proved by numerical analysis and experimental studies. Results show that the opening delay time can be controlled in a range of 0.2–18.3 ms and the closing delay time can be adjusted in a range of 0.1–6.8 ms, while the opening moving time can be adjusted from 1.9 to 14.1 ms and the closing moving time can be adjusted from 1.8 to 6.1 ms. Consequently, the total opening time and total closing time can be controlled in the ranges of 2.1–32.1 ms and 1.9–12.9 ms, respectively. Compared with the conventional single voltage control strategy, the advance PWM control algorithm is verified to be a promising method to improve or even adjust the dynamic behaviors of HSVs and adapt to more complex working conditions.

Two-stage directional valves usually employ proportional pilot control technology, which has the disadvantages of dead zones, leakage, and the large moving

In hydraulic area, independent metering control (IMC) technology is an effective approach to improve system efficiency and control flexibility. In addition, digital hydraulic technology (DHT) has been verified as a reasonable method to optimize system dynamic performance. Integrating these two technologies into one component can combine their advantages together. However, few works focused on it. In this paper, a twin spools valve with switching technology-controlled pilot stage (TSVSP) is presented, which applied DHT into its pilot stage while appending IMC into its main stage. Based on this prototype valve, a series of numerical and experiment analysis of its IMC performance with both simulated load and excavator boom cylinder are carried out. Results showed fast and robust performance of pressure and flow compound control with acceptable fluctuation phenomenon caused by switching technology. Rising time of flow response in excavator cylinder can be controlled within 200 ms, meanwhile, the recovery time of rod chamber pressure under suddenly changed condition is optimized within 250 ms. IMC system based on TSVSP can improve both dynamic performance and robust characteristics of the target actuator so it is practical in valve-cylinder system and can be applied in mobile machineries.

A high-speed on/off valve (HSV) is generally the core component of a digital hydraulic transmission system. Therefore, its dynamic characteristics often restrict the overall performance of the digital hydraulic system. Most of the current studies focus on the optimization on the dynamic characteristics or the energy characteristics, few studies have comprehensively considered the two characteristics of the valve together. In this paper, a pre-existing control algorithm (PECA) is proposed to improve the dynamic characteristics of the HSV, and simultaneously optimize the power losses of the HSV to improve its energy conversion efficiency. The results show that, compared with the traditional single-voltage driven strategy, the opening time of the PECA decreases by 29.4%, the closing time decreases by 59.6%, and the energy conversion rate increases by 7.9%.