压电激振球阀的优化及流量控制研究

发布时间：2018-07-02 09:40

本文选题：压电球阀 + 高频驱动　；参考：《南京理工大学》2011年硕士论文

【摘要】：传统的电气比例阀都以比例电磁铁作为驱动器,响应慢、控制精度低、工作带宽窄,而采用强力高速电磁铁驱动,虽然也可以提高其响应速度,但是由于受到电磁力、安装空间、运动惯性的影响,难以进一步提高电磁阀的响应速度,无法满足一些要求更高响应速度的场合。针对传统电磁式比例流量阀的不足,将压电驱动器与气动节流阀的有机结合,研制一种新型压电振子流量控制阀,使其具有快速响应、精确控制等特性,以满足自动化控制的一些新需求已是十分迫切。本文在分析了原有的预紧-限位型数字压电球阀的基础上,改进设计了实验控制系统以及相关机械结构,并在此基础上对小球抛动机制和球阀流量谐振特性进行了详细的理论与试验研究,并对其流量进行比例控制的研究,论文的研究内容主要有： (1)在分析原压电球阀实验控制系统的前提下,研究设计了一套满足快速、高频,高效控制需求的实验控制系统：采用高频信号发生器代替计算机对压电驱动电源进行控制,减少了信号延迟,实现了高频率范围(1—10kHz)的频率连续调节试验,满足了压电球阀快速、高频的控制需求；采用高功率PI压电驱动电源代替了原先的HPV压电驱动电源,在新实验系统下,压电阀的截止压差达到了0.5MPa以上,输出流量也可以达到43L/min。 (2)在压电阀的工作性能指标达到了工业运用标准的基础上,对该压电阀在结构功能上进行了相关的优化设计,主要包括：设计了套筒式限位机构,实现了压电阀的任意位置工作功能,使其更能适应各种复杂的工业生产环境；另外还设计了软管引出式通流管路,很好地解决了阀的泄漏问题,泄漏量也由原来的与输出流量相当的数十升每分钟,有效控制到了0.1L/min以下,使新阀在工作性能上较以往有了相当大地提高,进一步完善了压电球阀的工作性能。 (3)通过试验研究压电晶体的振动幅值和小球的抛动性能及输出流量与驱动电源频率之间关系,首次发现了压电球阀的谐振特性,即在系统谐振频率(6000Hz左右)下,不论是小球的抛起高度,还是球阀的流量输出都得到突增；另外还建立了压电球阀的动力学模型,从理论上分析了小球高频抛动过程中的运动机制,剖析了压电阀谐振特性的产生机理。 (4)基于PWM控制方法,对阀的输出流量分别进行了开环和闭环控制,稳态精度控制在了1 L/min以下,验证了PWM控制方法在该阀流量控制上可行性,为后续更高精度的控制方法和控制算法的研究提供了理论依据。综上所述,所研制的压电激振球阀不仅结构原理简单,体积较小,可实现快速大流量输出,并且通过PWM控制方法达到一定的稳态控制精度,验证了激振原理的压电球阀比例流量控制的可行性。
[Abstract]:The traditional electric proportional valves all use proportional electromagnet as the driver. The response is slow, the control precision is low, the working band is narrow, and the powerful high-speed electromagnet is used to drive it, although it can also improve its response speed, but because of the electromagnetic force, It is difficult to further improve the response speed of solenoid valve because of the influence of motion inertia and installation space, and can not meet the need of higher response speed. Aiming at the shortage of the traditional electromagnetic proportional flow valve, a new type of piezoelectric vibrator flow control valve is developed by combining the piezoelectric actuator with the pneumatic throttle valve, which has the characteristics of quick response and accurate control. It is very urgent to meet some new requirements of automatic control. Based on the analysis of the pressure-limited digital piezoelectric ball valve, the experimental control system and the related mechanical structure are improved and designed in this paper. On the basis of this, the mechanism of ball throwing and the flow resonance characteristics of ball valve are studied in detail in theory and experiment, and the proportional control of the flow rate is studied. The main contents of this paper are as follows: (1) on the premise of analyzing the experimental control system of piezoelectric ball valve, a set of fast and high frequency control system is designed. Experimental control system with high efficiency control requirements: the high frequency signal generator is used instead of the computer to control the piezoelectric drive power supply, which reduces the signal delay and realizes the continuous frequency regulation experiment in the high frequency range (1-10 kHz). The high power Pi piezoelectric drive power supply is used to replace the original HPV piezoelectric drive power supply. Under the new experimental system, the cut-off pressure difference of the piezoelectric valve is more than 0.5 MPA. The output flow rate can also reach 43L / min. (2) on the basis of the performance index of the piezoelectric valve has reached the industrial application standard, the structure and function of the piezoelectric valve have been optimized. The main contents are as follows: the sleeve type limiting mechanism is designed to realize the function of piezoelectric valve at any position, which makes it more suitable for various complex industrial production environments, and also designs the hose outlet flow line, The leakage of the valve has been solved very well, and the leakage has been controlled to less than 0.1 L / min from the original dozens of liters per minute equivalent to the output flow rate, which has greatly improved the new valve's working performance. The working performance of the piezoelectric ball valve is further improved. (3) the resonant characteristics of the piezoelectric ball valve are found for the first time by studying the relationship between the vibration amplitude of the piezoelectric crystal and the throwing performance of the ball, the output flow rate and the frequency of the driving power supply. That is, at the resonant frequency of the system (about 6, 000 Hz), both the throwing height of the ball and the flow output of the ball valve are suddenly increased, and the dynamic model of the piezoelectric ball valve is also established. In this paper, the motion mechanism of the ball in the process of high frequency throwing is analyzed theoretically, and the mechanism of the resonant characteristics of the piezoelectric valve is analyzed. (4) based on the PWM control method, the output flow rate of the valve is controlled by open loop control and closed loop control, respectively. The steady-state precision control is less than 1 L / min, which verifies the feasibility of PWM control method in the flow control of the valve, and provides a theoretical basis for the further study of higher precision control methods and control algorithms. To sum up, the piezoelectric exciting ball valve developed not only has simple structure and small volume, but also can realize fast and large flow output, and achieve a certain steady-state control precision by PWM control method. The feasibility of proportional flow control of piezoelectric ball valve based on excitation principle is verified.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TH134

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