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工程设计学报
Chinese Journal of Engineering Design  2024, Vol. 31 Issue (6): 766-775    DOI: 10.3785/j.issn.1006-754X.2024.14.04
【Special Column】Achievement Exhibition of "2024’Science and Technology Festival for Construction Machinery Industry "-Innovative Technologies and Their Applications     
Research on flow characteristics of fluid pulse width modulation bidirectional variable mechanism
Xiuwen XU1(),Yan REN1(),Lizhong LU2,Jian RUAN2
1.College of Mechanical and Electrical Engineering, Wenzhou University, Wenzhou 325035, China
2.College of Mechanical Engineering, Zhejiang University of Technology, Hangzhou 310023, China
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Abstract  

The method of variable-speed driving variable pump is mostly adopted for the bidirectional flow changes of hydraulic system. However, the structure of variable mechanism is relatively complicated, and frequent bidirectional variable regulation will lead to low dynamic response speed. Therefore, a new mechanism for flow regulation of fixed displacement pump was proposed to realize bidirectional variable function. The duty cycle of fluid pulse width modulation was changed by the axial movement of the spool of bidirectional variable mechanism. The product of the rotating speed of the spool relative to the valve sleeve and the number of valve port on the spool determined the frequency of fluid pulse width modulation. The flow characteristics of the bidirectional variable mechanism were analyzed by simulation and test. The results showed that the bidirectional variable mechanism could achieve bidirectional flow control with duty cycle of 0 to 100%, ane there was only 1.8% deviation between the simulation and test results. The research results provide a new flow control method for hydraulic pump with fixed speed design to use under variable speed working condition.

Key words： bidirectional variable mechanism      bidirectional variable flow regulation      fluid pulse width modulation      flow characteristic     
Received: 16 April 2024      Published: 31 December 2024
CLC:  TH 137.5  
Corresponding Authors: Yan REN     E-mail: xgs180m@126.com;rentingting211@wzu.edu.cn
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Xiuwen XU
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Jian RUAN
Cite this article:

Xiuwen XU,Yan REN,Lizhong LU,Jian RUAN. Research on flow characteristics of fluid pulse width modulation bidirectional variable mechanism. Chinese Journal of Engineering Design, 2024, 31(6): 766-775.

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https://www.zjujournals.com/gcsjxb/10.3785/j.issn.1006-754X.2024.14.04     OR     https://www.zjujournals.com/gcsjxb/Y2024/V31/I6/766


流体脉宽调制双向变量机构流量特性研究

液压系统流量双向变化大多采用变转速驱动变量泵的方法，但变量机构的结构较复杂，且频繁双向变量调节会导致动态响应速度较慢。因此，提出了适用于定量泵流量调节的新机构，以实现双向变量功能。通过双向变量机构阀芯的轴向移动改变流体脉宽调制占空比，阀芯相对阀套的转速与阀芯上过流窗口数的乘积决定了流体脉宽调制的频率。对双向变量机构的流量特性进行了仿真和试验分析，结果表明：双向变量机构能够实现占空比为0~100%的双向流量控制，且仿真结果与试验结果之间仅有1.8%的误差。研究结果为固定转速设计的液压泵在变转速工况下的使用提供了一种新的流量控制方式。


关键词： 双向变量机构,  双向变量流量调节,  流体脉宽调制,  流量特性 
Fig.1 Schematic of principle of fluid pulse width modulation
Fig.2 Structureof bidirectional variable mechanism
Fig.3 Structure of spool and valve sleeve
Fig.4 Schematic of operation principle of bidirectional variable mechanism
Fig.5 Schematic of change of flow area at valve port
Fig.6 Schematic of change of flow direction
Fig.7 Schematic of flow area at valve port
Fig.8 Schematic of change of flow area at valve port with d∈[-b+c, -b+c+a]
Fig.9 Schematic of change of flow area at valve port with d∈[-b+c+a, c]
Fig.10 Schematic of change of flow area at valve port with d∈[-b+c+2a, b+c-a]
Fig.11 Flow area at valve port at load port side
Fig.12 AMESim simulation model of valve-controlled hydraulic motor system of bidirectional variable mechanism
参数数值
液压油密度/(kg·m-3)870
阀口流量系数0.67
阀口所在轴肩半径/mm15
油液弹性模量/Pa8×108
液压泵排量/(L/min)60
液压泵转速/(r/min)1 000
阀芯转速/(r/min)3 000
回油背压/MPa1
Table 1 Simulation parameters of bidirectional variable mechanism flow characteristic
Fig.13 Simulation curve of duty cycle-spool axial displacement
Fig.14 Simulation curves of output flow of bidirectional variable mechanism under different loads
Fig.15 Simulation curves of steady state output flow of bidirectional variable mechanism under different loads
Fig.16 Related equipment of test bench
Fig.17 Physical map of spool and valve sleeve
Fig.18 Schematic of test principle of bidirectional variable mechanism
Fig.19 Pressure waveform at load port side under different duty cycle
Fig.20 Flow characteristic curves of bidirectional variable mechanism without load
Fig.21 Flow characteristic curves of bidirectional variable mechanism without load of 600 N·m
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