The possibility to enhance the stability and robustness of electrohydraulic brake(EHB)systems is considered a subject of great importance in the automotive field.In such a context,the present study focuses on an actua...The possibility to enhance the stability and robustness of electrohydraulic brake(EHB)systems is considered a subject of great importance in the automotive field.In such a context,the present study focuses on an actuator with a four-way sliding valve and a hydraulic cylinder.A 4-order nonlinear mathematical model is introduced accordingly.Through the linearization of the feedback law of the high order EHB model,a sliding mode control method is proposed for the hydraulic pressure.The hydraulic pressure tracking controls are simulated and analyzed by MATLAB/Simulink soft considering separately different conditions,i.e.,a sine wave,a square wave and a square wave with superimposed sine disturbance.The results show that the proposed strategy can track the target within 0.25 s,and the mean observed error is less than 1.2 bar.Moreover,with such a strategy,faster response and less overshoot are possible,which should be regarded as significant advantages.展开更多
A method of setting up a pressure-stroke characteristic of the working liquid in hydraulic drawing is studied. A pressure-stroke characteristic and software for controlling its forming process are also developed. An...A method of setting up a pressure-stroke characteristic of the working liquid in hydraulic drawing is studied. A pressure-stroke characteristic and software for controlling its forming process are also developed. And a set of pressure controlling devices with PLC as a central processor are designed. It can be got from the relevant experiments that the pressure-stroke characteristic is correct and its control for forming process is available.展开更多
Water-assisted injection molding（WAIM）, an innovative process to mold plastic parts with hollow sections, is characterized with intermittent, periodic process and large pressure and flow rate variation. Energy savin...Water-assisted injection molding（WAIM）, an innovative process to mold plastic parts with hollow sections, is characterized with intermittent, periodic process and large pressure and flow rate variation. Energy savings and injection pressure control can not be .attained based on conventional valve control system. Moreover, the injection water can not be supplied directly by water hydraulic proportional control system. Poor efficiency and control performance are presented by current trial systems, which pressurize injection water by compressed air. In this paper, a novel water hydraulic system is developed applying an accumulator for energy saving. And a new differential pressure control method is proposed by using pressure cylinder and water hydraulic proportional pressure relief valve for back pressure control. Aiming at design of linear controller for injection water pressure regulation, a linear load model is approximately built through computational fluid dynamics（CFD） simulation on two-phase flow cavity filling process with variable temperature and viscosity, and a linear model of pressure control system is built with the load model and linearization of water hydraulic components. According to the simulation, model based feedback is brought forward to compensate the pressure decrease during accumulator discharge and eliminate the derivative element of the system. Meanwhile, the steady-state error can be reduced and the capacity of resisting disturbance can be enhanced, by closed-loop control of load pressure with integral compensation. Through the developed experimental system in the State Key Lab of Fluid Power Transmission and Control, Zhejiang University, China, the static characteristic of the water hydraulic proportional relief valve was tested and output pressure control of the system in Acrylonitrile Butadiene Styrene（ABS） parts molding experiments was also studied. The experiment results show that the dead band and hysteresis of the water hydraulic proportional pressure relief valve are large, but the control precision and linearity can be improved with feed-forward compensation. With the experimental results of injection water pressure control, the applicability of this WAIM system and the effect of its linear controller are verified. The novel proposed process of WAIM pressure control and study on characteristics of control system contribute to the application of water hydraulic proportional control and WAIM technology.展开更多
Multi-level pressure source system is a novel hydraulic system with distinct advantage of energy saving. In order to balance each pressure level of the multi-level pressure source system, a pump motor energy transfer ...Multi-level pressure source system is a novel hydraulic system with distinct advantage of energy saving. In order to balance each pressure level of the multi-level pressure source system, a pump motor energy transfer unit is usually equipped. However, the pump motor energy transfer has the characteristics of poor starting and low response, which cause long time of pressure adjustment and large pressure jitter when the transformer is switched to system suddenly and the motor-side pressure has pressure impact when rail of the pump-side is switched. To address these problems, this paper proposes a compound control strategy of feedforward compensation control with Fuzzy-PID to improve the controllability of the multi-level pressure source system. A test rig of the pump motor energy transfer unit is built and the controllability of compound controller and PID controller are compared. The experiment results show that, compared with the traditional PID, the adjustment time and the pressure impact are reduced by 20% and 25% with the proposed compound control strategy. Therefore, the presented compound control strategy can be used to improve starting performance and robustness of the pump motor energy transfer unit control system.展开更多
Measured to control serious coal-gas outburst in coal seam were analyzed by theory and experimented in test site.A new technique to distress the coal-bed and drain methane,called hydraulic slotting,was described in de...Measured to control serious coal-gas outburst in coal seam were analyzed by theory and experimented in test site.A new technique to distress the coal-bed and drain methane,called hydraulic slotting,was described in detail,and the mechanism of hydrau- lic slotting was put forward and analyzed.The characteristic parameter of hydraulic slotting was given in Jiaozuo mining area and the characteristic of validity,adaptability and secu- rity was evaluated.The results show that the stress surrounding the strata and the gas in coal seam is released efficiently and thoroughly while new techniques are taken,as slot- ting at heading face by high pressure large diameter jet.The resistance to coal and gas outbursts is increased dramatically once the area of slotting is increased to a certain size. In the process of driving 2 000 m tunnel by hydraulic slotting excavation,coal and gas outburst never occurre.The technique could be used to prevent and control potential coal-gas outburst in the proceeding of tunnel driving,and the speed tunneling could be as high as more than 2 times.展开更多
Aiming at the problem of large energy consumption in hydraulic control system with large load and variable working conditions,based on the multi-level pressure switching control system(MPSCS),a multi-level pressure sw...Aiming at the problem of large energy consumption in hydraulic control system with large load and variable working conditions,based on the multi-level pressure switching control system(MPSCS),a multi-level pressure switching control system based on independent metering control is proposed combined with the independent metering control technology.The configuration principle of the system is given,the mathematical model of this system is established,and the control strategy of the system under 4 different working quadrants is put forward.Finally,the control performance and energy saving characteristics of the system are tested.The test results show that the switching of high and low pressure power supply has a certain effect on the response of step position and ramp position under impedance working condition.The displacement curves show slow climbing or abrupt change of ramp position,and the position accuracy is less than 1 mm.The multi-level pressure switching control system based on independent metering control can recover and store energy under the transcendence working conditions.The control accuracy is about 1 mm,and the energy recovery rate is about 70%~80%.展开更多
When a valve is suddenly closed in fluid transport pipelines,a pressure surge or shock is created along the pipeline due to the momentum change.This phenomenon,called hydraulic shock,can cause major damage to the pipe...When a valve is suddenly closed in fluid transport pipelines,a pressure surge or shock is created along the pipeline due to the momentum change.This phenomenon,called hydraulic shock,can cause major damage to the pipelines.In this paper,we introduce a hyperbolic partial differential equation(PDE)system to describe the fluid flow in the pipeline and propose an optimal boundary control problem for pressure suppression during the valve closure.The boundary control in this system is related to the valve actuation located at the pipeline terminus through a valve closing model.To solve this optimal boundary control problem,we use the method of lines and orthogonal collocation to obtain a spatial-temporal discretization model based on the original pipeline transmission PDE system.Then,the optimal boundary control problem is reduced to a nonlinear programming(NLP)problem that can be solved using nonlinear optimization techniques such as sequential quadratic programming(SQP).Finally,we conclude the paper with simulation results demonstrating that the full parameterization(FP)method eliminates pressure shock effectively and costs less computation time compared with the control vector parameterization(CVP)method.展开更多
蜗壳式离心泵作为流体输送的核心设备,压力脉动及水利性能对泵的稳定性、噪声、寿命等有重大影响。结合曲率控制前缘的设计方法,按增长率1.19%、0.47%、0.32%设计,建立前缘轴长比为0.96、2.11、3.11、4.11的蜗壳式离心泵,以SSTκ-ω模...蜗壳式离心泵作为流体输送的核心设备,压力脉动及水利性能对泵的稳定性、噪声、寿命等有重大影响。结合曲率控制前缘的设计方法,按增长率1.19%、0.47%、0.32%设计,建立前缘轴长比为0.96、2.11、3.11、4.11的蜗壳式离心泵,以SSTκ-ω模型定常计算结果为初始条件,进行κ-εRNG模型非定常分析,通过频域图分析蜗壳式离心泵压力脉动,并通过矢量云图分析水力性能。结果表明:设计的模型最佳流量为35 m 3/h,设计效率与模拟效率误差仅为2%;前缘轴长比不同,流道内压力扩散有差异;前缘轴长比为3.11时出口压力脉动偏低,低频区更易产生压力脉动;前缘轴长比为0.96时,压力脉动范围偏小,适用于一定流量范围内扬程变化较大的工况。展开更多
基金supported by the National Natural Science Foundation of China[grant number 51565011]the Foundation of Educational Department of Jiangxi Province[grant number GJJ180302].
文摘The possibility to enhance the stability and robustness of electrohydraulic brake(EHB)systems is considered a subject of great importance in the automotive field.In such a context,the present study focuses on an actuator with a four-way sliding valve and a hydraulic cylinder.A 4-order nonlinear mathematical model is introduced accordingly.Through the linearization of the feedback law of the high order EHB model,a sliding mode control method is proposed for the hydraulic pressure.The hydraulic pressure tracking controls are simulated and analyzed by MATLAB/Simulink soft considering separately different conditions,i.e.,a sine wave,a square wave and a square wave with superimposed sine disturbance.The results show that the proposed strategy can track the target within 0.25 s,and the mean observed error is less than 1.2 bar.Moreover,with such a strategy,faster response and less overshoot are possible,which should be regarded as significant advantages.
基金This project is supported by Provincial Natural ScienceFoundation of Shanxi. Selected form Proceedings of 2000the First Inte
文摘A method of setting up a pressure-stroke characteristic of the working liquid in hydraulic drawing is studied. A pressure-stroke characteristic and software for controlling its forming process are also developed. And a set of pressure controlling devices with PLC as a central processor are designed. It can be got from the relevant experiments that the pressure-stroke characteristic is correct and its control for forming process is available.
基金supported by National Basic Research Program of China (973 Program, Grant No. 2006CB705405)National Natural Science Foundation of China (Grant No. 50775199)Zhejiang Provincial Science and Technology Plan Program of China (Grant No. 2007C21057)
文摘Water-assisted injection molding（WAIM）, an innovative process to mold plastic parts with hollow sections, is characterized with intermittent, periodic process and large pressure and flow rate variation. Energy savings and injection pressure control can not be .attained based on conventional valve control system. Moreover, the injection water can not be supplied directly by water hydraulic proportional control system. Poor efficiency and control performance are presented by current trial systems, which pressurize injection water by compressed air. In this paper, a novel water hydraulic system is developed applying an accumulator for energy saving. And a new differential pressure control method is proposed by using pressure cylinder and water hydraulic proportional pressure relief valve for back pressure control. Aiming at design of linear controller for injection water pressure regulation, a linear load model is approximately built through computational fluid dynamics（CFD） simulation on two-phase flow cavity filling process with variable temperature and viscosity, and a linear model of pressure control system is built with the load model and linearization of water hydraulic components. According to the simulation, model based feedback is brought forward to compensate the pressure decrease during accumulator discharge and eliminate the derivative element of the system. Meanwhile, the steady-state error can be reduced and the capacity of resisting disturbance can be enhanced, by closed-loop control of load pressure with integral compensation. Through the developed experimental system in the State Key Lab of Fluid Power Transmission and Control, Zhejiang University, China, the static characteristic of the water hydraulic proportional relief valve was tested and output pressure control of the system in Acrylonitrile Butadiene Styrene（ABS） parts molding experiments was also studied. The experiment results show that the dead band and hysteresis of the water hydraulic proportional pressure relief valve are large, but the control precision and linearity can be improved with feed-forward compensation. With the experimental results of injection water pressure control, the applicability of this WAIM system and the effect of its linear controller are verified. The novel proposed process of WAIM pressure control and study on characteristics of control system contribute to the application of water hydraulic proportional control and WAIM technology.
基金Supported by the National Natural Science Foundation of China(No.51575471)the Key Project of Science and Technology Plan of Higher Education of Hebei Education Department(No.ZD2017077)
文摘Multi-level pressure source system is a novel hydraulic system with distinct advantage of energy saving. In order to balance each pressure level of the multi-level pressure source system, a pump motor energy transfer unit is usually equipped. However, the pump motor energy transfer has the characteristics of poor starting and low response, which cause long time of pressure adjustment and large pressure jitter when the transformer is switched to system suddenly and the motor-side pressure has pressure impact when rail of the pump-side is switched. To address these problems, this paper proposes a compound control strategy of feedforward compensation control with Fuzzy-PID to improve the controllability of the multi-level pressure source system. A test rig of the pump motor energy transfer unit is built and the controllability of compound controller and PID controller are compared. The experiment results show that, compared with the traditional PID, the adjustment time and the pressure impact are reduced by 20% and 25% with the proposed compound control strategy. Therefore, the presented compound control strategy can be used to improve starting performance and robustness of the pump motor energy transfer unit control system.
基金National Nature Science Foundation of China(50534070)International Science and Technology Cooperation and Communion Key Project of Ministry Science and Technology of China(2005DFA61030)+1 种基金Natural Science Foundation of Henan Province(200510460014)Coal Mine Gas and Fire Prevention and Control Key Laboratory Foundation of Henan Province(HKLGF200708)
文摘Measured to control serious coal-gas outburst in coal seam were analyzed by theory and experimented in test site.A new technique to distress the coal-bed and drain methane,called hydraulic slotting,was described in detail,and the mechanism of hydrau- lic slotting was put forward and analyzed.The characteristic parameter of hydraulic slotting was given in Jiaozuo mining area and the characteristic of validity,adaptability and secu- rity was evaluated.The results show that the stress surrounding the strata and the gas in coal seam is released efficiently and thoroughly while new techniques are taken,as slot- ting at heading face by high pressure large diameter jet.The resistance to coal and gas outbursts is increased dramatically once the area of slotting is increased to a certain size. In the process of driving 2 000 m tunnel by hydraulic slotting excavation,coal and gas outburst never occurre.The technique could be used to prevent and control potential coal-gas outburst in the proceeding of tunnel driving,and the speed tunneling could be as high as more than 2 times.
基金the National Natural Science Foundation of China(No.51575471)the Natural Science Foundation of Hebei Province(No.E2018203028).
文摘Aiming at the problem of large energy consumption in hydraulic control system with large load and variable working conditions,based on the multi-level pressure switching control system(MPSCS),a multi-level pressure switching control system based on independent metering control is proposed combined with the independent metering control technology.The configuration principle of the system is given,the mathematical model of this system is established,and the control strategy of the system under 4 different working quadrants is put forward.Finally,the control performance and energy saving characteristics of the system are tested.The test results show that the switching of high and low pressure power supply has a certain effect on the response of step position and ramp position under impedance working condition.The displacement curves show slow climbing or abrupt change of ramp position,and the position accuracy is less than 1 mm.The multi-level pressure switching control system based on independent metering control can recover and store energy under the transcendence working conditions.The control accuracy is about 1 mm,and the energy recovery rate is about 70%~80%.
基金partially supported by the National Natural Science Foundation of China(61703217,61703114)the K.C.Wong Magna Fund in Ningbo University,the Open Project of Key Laboratory of Industrial Internet of Things and Networked Control(2018FF02)the Open Research Project of the State Key Laboratory of Industrial Control Technology,Zhejiang University,China(ICT1900313)
文摘When a valve is suddenly closed in fluid transport pipelines,a pressure surge or shock is created along the pipeline due to the momentum change.This phenomenon,called hydraulic shock,can cause major damage to the pipelines.In this paper,we introduce a hyperbolic partial differential equation(PDE)system to describe the fluid flow in the pipeline and propose an optimal boundary control problem for pressure suppression during the valve closure.The boundary control in this system is related to the valve actuation located at the pipeline terminus through a valve closing model.To solve this optimal boundary control problem,we use the method of lines and orthogonal collocation to obtain a spatial-temporal discretization model based on the original pipeline transmission PDE system.Then,the optimal boundary control problem is reduced to a nonlinear programming(NLP)problem that can be solved using nonlinear optimization techniques such as sequential quadratic programming(SQP).Finally,we conclude the paper with simulation results demonstrating that the full parameterization(FP)method eliminates pressure shock effectively and costs less computation time compared with the control vector parameterization(CVP)method.
文摘蜗壳式离心泵作为流体输送的核心设备,压力脉动及水利性能对泵的稳定性、噪声、寿命等有重大影响。结合曲率控制前缘的设计方法,按增长率1.19%、0.47%、0.32%设计,建立前缘轴长比为0.96、2.11、3.11、4.11的蜗壳式离心泵,以SSTκ-ω模型定常计算结果为初始条件,进行κ-εRNG模型非定常分析,通过频域图分析蜗壳式离心泵压力脉动,并通过矢量云图分析水力性能。结果表明:设计的模型最佳流量为35 m 3/h,设计效率与模拟效率误差仅为2%;前缘轴长比不同,流道内压力扩散有差异;前缘轴长比为3.11时出口压力脉动偏低,低频区更易产生压力脉动;前缘轴长比为0.96时,压力脉动范围偏小,适用于一定流量范围内扬程变化较大的工况。
