| High-speed electromagnetic valve(HSEV)is the key control component of electronic fuel injection system(EFIS).Its strong electromagnetic force and rapid response characteristics directly affect the control accuracy of the fuel injection and the flexible injection law.It is difficult for the traditional HSEV to solve the contradiction between its limited design space and driving force,low power consumption and driving force,and high response speed and low power consumption.It restricts the development of EFIS.Hence,in this thesis,a novel HSEV with the permanent magnet and electromagnetic composite magnetic circuit is proposed,having the low power consumption,the strong electromagnetic force and the high response characteristics.However,its actual development and application still have the following problems: first,the lack of numerical simulation models for the novel HSEV make it impossible to carry out simulation analysis of its static and dynamic characteristics;second,not having fully grasped the electromagnetic force output characteristics of the novel HSEV and the mechanism of its characteristic structure makes it difficult to optimize the design;third,not having fully revealed the magnetic field transients of the novel HSEV and the influence rules of the energy conversion on its dynamic characteristics results in the difficulty in optimally controlling the novel HSEV;fourth,HSEV is the coupling systems of electricity,magnetism,machinery and fluid field with interactions between fields,and the introduction of permanent magnet and electromagnetic composite magnetic circuit makes the system more complex,these lead to the difficulty in realizing the multi-objective and multi-parameter optimization of the novel HSEV.Therefore,the research work of this thesis focus on the following aspects:(1)Research on the numerical simulation model for the novel HSEV.First of all,the structure and working principle of the novel HSEV were elucidated,and its principle prototype was designed.Then,the static simulation model of the novel HSEV was developed by using the magnetic-network topology analysis method.In the static model,the calculation accuracy for the magnetic reluctance of the variable cross-section unit was improved by using the continuous characteristic function between the magnetic permeability and the magnetic flux of soft magnetic materials,and the flux leakage and fringing flux of the system were taken into account.Simultaneously the dynamic simulation model of the novel HSEV was established by applying the field-circuit coupling step-by-step finite element method.In the dynamic model,the coupled effect of electricity,magnetism,machinery and fluid field,and the hysteresis and eddy effects were taken into consideration;besides,a detailed modeling of the drive circuit was included.In the end,a sample of the novel HSEV was prototyped,and the simulation models were validated through experiments.The maximum error of the static simulation model was 6.5%,and the maximum error of the dynamic simulation model was 4.3%.The results show that the simulation models of the novel HSEV have high accuracy,and provides a favorable tool for the study of its static and dynamic characteristics.(2)Research on the static characteristics of the novel HSEV.In order to reveal the electromagnetic force output characteristics of the novel HSEV,the variation laws of force-current and force-displacement between the novel and traditional HSEV were analyzed and compared.The result shows that the novel HSEV has a wider range of working stroke and stronger electromagnetic force for output.In order to fully understand the mechanism of the characteristic structure of the novel HSEV,the influence of its characteristic structural parameters on the electromagnetic force was studied,and the mechanism of the characteristic structure was revealed.Considering the interaction between the system parameters under the permanent magnet and electromagnetic composite magnetic circuit,the electromagnetic force response surface model was constructed by using the response surface method.And the key parameters affecting the electromagnetic force and the significant interaction factors were obtained.At the same time,the mechanism of the interaction significant factors and the relationships between it and the electromagnetic force were revealed,and the optimal matching principle between interaction parameters was obtained.(3)Research on dynamic characteristics of the novel HSEV.In order to reveal the influence of magnetic field transient and energy conversion on the dynamic characteristics of the novel HSEV,the dynamic characteristics of the composite magnetic field excited by permanent magnet and electromagnetic coil were analyzed,and the transient law of the composite magnetic field was revealed.The research on the energy change and conversion of the system under the complex magnetic field was carried out,and the energy change and conversion law of the working process of the novel HSEV was revealed,in addition,the optimization strategy of HSEV was obtained.The influence of driving parameters,core material and assembly parameters on the dynamic response characteristics of the novel HSEV was further analyzed from the point of view of energy.It is founded that the parameters such as the peak excitation voltage,the peak current,the first order maintenance current and the first order maintenance current time affect the opening response time but also the closing response time,which makes it more difficult to optimize and match the driving control parameters;at the same time,the results show that the difference of the magnetic field should be minimized between the moments when the armature of HSEV has just reached the maximum displacement and when the power is off,so as to reduce the inconsistency of the closing response time of HSEV under the different injection pulse widths and reduce the nonlinearity degree of fuel injection control.(4)Multi-objective optimization research of the novel HSEV.In order to realize the multi-objective and multi-parameter optimization of the novel HSEV in the environment of multiple physical coupling and parameters interactions,a multi-objective optimization method based on the sequential combination approximation model with parameters tuning was proposed.And the multi-objective optimization mathematical model of the novel HSEV which makes the minimum the opening and closing response time and the heat loss of HSEV as the target,and selects the driving parameters,structural parameters and assembly parameters as design variables was developed.Based on genetic algorithm,the pareto solution set and the optimized solution by the maximum distance method were obtained,which makes the opening response speed and the closing response speed increased by 38% and 44.5% respectively,and makes the heat loss reduced by 27.7%.This research provides the theoretical support to design and optimize HSEV with low power consumption,strong electromagnetic force and high dynamic response for EFIS.It is of great theoretical and practical significance for improving the performance of EFIS. |
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