Measurement and modelling of a linear electromagnetic actuator driven camless valve train for spark ignition IC engines under full load condition

Camless engine valve train for gasoline engines particularly port injection engines offer major improvements over traditional system with fixed valve timing and lift, in terms of efficiency, maximum torque and power, and emissions. Electromagnetic driven valve actuators are very promising in this context, but there are significant control problems. The use of displacement sensor could add extra cost to the camless engine. In this work, a moving coil actuator driven valve train was designed and prototyped and a 1D single-cylinder internal combustion engine model was built to investigate the benefit of without throttle by adopting such camless valve train using Ricardo WAVE under full load operating conditions. A novel low-cost sensor named linear actuator position sensor (LAPS) based on flux linkage change on search coil was constructed in LabVIEW by using current, voltage and proximity sensors to detect the valve lift. The measurement of valve lift and current was reported to prove the feasibility of the camless valve train. The valve lift was used for the single-cylinder engine model and the simulation shows that the peak overall engine efficiency using camless valve train reaches 38.2% and the peak torque increases by 5 Nm compared conventional throttled engine under full load operating conditions. The LAPS model was validated by the experimental valve lift and the high accuracy indicates that the LAPS can be adopted for future development of camless valve train for spark ignition IC engines.     

Development of a new fully flexible hydraulic variable valve actuation system for engines using rotary spool valves

In this paper, a new hydraulic variable valve actuation (VVA) system is proposed and designed. The VVA system can significantly improve the engine performance in terms of the power density, volumetric efficiency, emission, and fuel consumption. In this system, each engine valve is actuated by a hydraulic cylinder which is charged and discharged using two rotary spool valves. The rotary spool valves are rotated by the engine crankshaft while their phases are controlled by hydraulic or electric phase shifters. Similar to camless valvetrains, the new engine valve system is capable of flexible engine valve timing and lift at any engine speed without the drawbacks of existing camless valvetrains including high control complexity, low reliability, and slow actuator response. The mathematical model of the system is derived and verified by comparing simulation and experimental results. Two feedback controllers are designed and implemented for precise valve opening and closing timing and valve lift control. Experiments are performed to validate the mathematical model and evaluate the proposed system's performance. The results show excellent system repeatability and controllability at different operating conditions.     

Improvement of valve seating performance of engine’s electromagnetic valvetrain

The camless valvetrain is considered to be a promising solution to improve the engine performance. Most of the camless valvetrains suffer the problem of high impacts at valve seating, which restricts its mass production. This paper focuses on the valve seating performance of an electromagnetic valvetrain (EMVT) with moving coil linear actuator. The EMVT has inherent advantages to achieve low valve seating velocity. The seating performance of EMVT is evaluated by two indicators: seating velocity and holding force. To limit the seating velocity, the valve is controlled to track a desired trajectory based on inverse system method at seating process. The holding force is also properly controlled base on PID current control to ensure the cylinder sealed. The valve seating performance is validated on an experimental setup. The results show that excellent valve seating performance has been achieved.     

On-line cylinder fault diagnostics for internal combustion engines

The ability to continuously monitor internal combustion engines for the existence and location of faults can improve engine reliability and reduce operating costs. The diagnostics method is based on recording the engine speed fluctuations at the flywheel and at the front end of the engine over one combustion cycle. From the speed fluctuations, the cylinder-to-cylinder variations of the net engine torque are computed. The performance deterioration of an individual cylinder is detected as a drop of computed torque. The diagnostic hardware consists of a digital engine speed data acquisition system and an embedded controller and is suited for in-vehicle installation. The method, suited for any multicylinder engine, detects the location and severity of faults during normal engine operation. Adjustments for individual engines of the same class are not required     

Valve timing and valve lift control mechanism for engines

A new type engine valve control system has been presented, in which both the valve lift and valve timing are controlled directly by electric motors. A mechanism of the valve timing control system is made of planetary gears. The outer gear is the timing pulley which has a timing belt driven by the crankshaft of an engine. Two planetary gears are inside of the pulley. The gears engage with the inner gear of the pulley. The center of the disc, which has centers of the planetary gear, is connected to the camshaft. Then, the crank rotation is transmitted to the camshaft, and rotations of sun gear are added to the rotations of camshaft. This means that when rotation angle of the sun gear is controlled, the phase between the inlet valve and the exhaust valve can be controlled. The lift control system is made of linear slider and ball screw. The cam shape of this system is three-dimensional. The height of the cam varies along the axis of the shaft. When the ball screw rotates, the camshaft slides in the axial direction, so that the lift of the cam varies. The control method is presented for the mechanism, in which valve phase and the lift are controlled continuously. Experimental tests have been carried out for the system.     

Modeling of an Electromechanical Engine Valve Actuator Based on a Hybrid Analytical--FEM Approach

The use of an electromechanical valve actuator (EMVA) formed by two magnets and two balanced springs is a promising tool to implement innovative engine management strategies. This actuator needs to be properly controlled to reduce impact velocities during engine valve operations, but the use of a position sensor for each valve is not possible for cost reasons. It is therefore essential to find sensorless solutions based on increasingly predictive models of such a mechatronic actuator. To address this task, in this paper, we present an in-depth lumped parameter model of an EMVA based on a hybrid analytical--finite-element method (FEM) approach. The idea is to develop a model of EMVA embedding the well-known predictive behavior of FEM models. All FEM data are then fitted to a smooth curve that renders unknown magnetic quantities in analytical form. In this regard, we select a single-wise function that is able to describe global magnetic quantities as the flux linkage and force both for linear and saturation working regions of the materials. The model intrinsically describes all mutual effects between two magnets. The goodness of the dynamic behavior of the model is finally tested on a series of transient FEM simulations of the actuator in different working conditions.      

微小型高压力流体电磁控制阀

用于航空航天领域微流量控制系统中的微小型阀 ,需要具有耐高压、低泄漏、高频响和高控制精度等综合性能。本文提出了一种可控高压力微流体的常闭微小型阀的设计方案用于满足该系统需要 ,其特点在于采用以较小的致动力控制较高的流体压力的结构原理 ,并以弹性材料薄膜作为阀芯的支承结构件同时作为密封件。该阀由其本体结构和外置致动器两部分构成 ,其本体结构的设计在制作工艺上适合进一步的微小型化 ,外置致动器的设计具有较大灵活性。初步研制了采用电磁致动的小型常闭阀样机既可控气体又可控液体的特性。实验测试其工作压力范围为 0～5atm ,阀的驱动响应时间小于 5ms,流量控制分辨率达到 9μL/ pulse ,无泄露     

Individual A/F Estimation and Control With the Fuel–Gas Ratio for Multicylinder IC Engines

In internal combustion engines with multicylinders, balancing the air–fuel ratio (A/F) for individual cylinders is an important issue for providing high-quality torque generation and reducing emissions. This paper addresses the individual A/F control problem for a six-cylinder engine with a single sensor. First, a modeling method to estimate the individual fuel–gas ratio, which immediately provides the A/F, is proposed, and using the estimation model, an adaptive generalized predictive control approach to balancing the individual cylinder characteristics is presented, which targets the static engine-operation mode. The effectiveness of the presented model is validated based on the experimental results, and a comparison with existing models is given based on the experiments. Finally, control performance with the proposed individual A/F control approach is demonstrated with the experiments conducted on a six-cylinder engine test bench.      

Microprocessor-Based Control of Engine Valve Timing

One of the most interesting ways of improving the lowspeed performance of spark-ignition engines is the variation of the valve timing in order to reduce mechanical losses.     

Design and experimental implementation of an electromagnetic engine valve drive

In conventional internal combustion engines, engine valve displacements are fixed relative to crankshaft position. If these valves were actuated as a variable function of crankshaft angle, significant improvements in fuel economy could be achieved. To this end, a new type of electromagnetic valve drive system (EMVD) for internal combustion engines was more recently proposed. This EMVD incorporates a disk cam with a very desirable nonlinear profile which that functions as a nonlinear mechanical transformer. Modeling and simulation results showed significant advantages of this EMVD over previously designed electromagnetic engine valve drives. In this articles, we describe an experimental implementation of the proposed EMVD, which was developed to confirm these benefits. The EMVD apparatus was designed, constructed, and integrated into a computer-controlled experimental test stand. The experimental results confirm the benefits of using a nonlinear mechanical transformer in a motordriven engine-valve spring system, as seen in the small average power consumption and low valve seating velocity. In addition, a valve transition time sufficient for 6000-rpm engine operation was achieved. The results also suggest ways to improve the EMVD apparatus in the future.     

A novel MR-conditional cam-based automatic prostate biopsy device

Biopsy is the most commonly used method for diagnosing prostate cancer, in which a biopsy gun is used to obtain the tissue samples. The outstanding performance of magnetic resonance imaging (MRI) for soft tissue can provide better medical guidance for prostate biopsy. This paper reports an automatic biopsy device that can be used in the MRI environment and that is expected to be used together with the MR conditional robotic prostate biopsy system. This paper proposes a compact cam-based automatic biopsy device that can perform all actions required for prostate biopsy sampling procedure using a single actuator. Its design concept, implementation, required force analysis, sampling performance evaluation, and MR compatibility evaluation are also provided. The experimental evaluation showed that the tissue sampling process can be easily and completely performed using the proposed automatic biopsy device, and that its sampling performance is comparable to that of the existing commercially available manual biopsy gun. MR compatibility test showed that an 18.7% reduction in the signal-to-noise ratio when the device was operating.     

压电叠堆电静液作动器Simscape模型与实验研究

将海德福斯螺纹插装换向阀集成到压电叠堆电静液作动器中,形成一体化集成式双向运动的压电叠堆电静液作动器。基于压电叠堆电静液作动器的物理系统,采用Simscape搭建压电叠堆电静液作动器系统模型。对比了在不同蓄能器偏压、不同电压峰值条件作用下,压电叠堆电静液作动器的实验输出流量与仿真输出流量;以及换向阀换向周期为4s时,压电叠堆电静液作动器的实验输出位移与仿真输出位移,验证了搭建的Simscape模型的准确性。在系统模型得到验证的基础上,分析发现阀片的回流现象是造成压电叠堆电静液作动器在高频驱动时输出流量衰减的原因。     

New polarized electromagnetic actuators as integrated mechatronic components — design and application

This paper presents an overview over the computer-aided design process of mechatronic devices and systems, especially the design of electrodynamic and electromagnetic drives using modern high-energy permanent magnetic materials like NdFeB and SmCo. This paper also presents some examples of such actuators. The first example is a miniaturized pneumatic valve for industrial applications. This valve has an integrated bi-stable polarized solenoid actuator. The second example is a polarized electromagnetic valve manufactured by modern batch technologies using photo-structurable glass material. The valve seat and the actuator coils are realized using this glass material. The third example is a gripping device with compliant mechanism and planar moving coil actuator.     

压电阀中的微位移放大机构

压电陶瓷材料具有优良的力学性能和响应特性,将其作为智能执行器应用于液压阀中,是持续多年的研究热点。但压电驱动器输出仅为微米级,难以直接满足液压阀的使用要求,因此需要设计相应的微位移放大机构。首先,重点介绍了柔性铰链放大机构及其在压电阀中的典型应用,根据原理可分为杠杆、三角、桥式等放大形式;其次,归纳了基于液压放大和晶片放大机构的两类压电阀的代表性结构和性能特点;最后,分析对比了三类放大机构应用于压电阀中的优缺点。结果表明,铰链放大结构简单,再现性好;液压放大占用空间小,频带宽,倍数高;晶片放大频响高,只适用于伺服和先导控制。     

Evolutionary design and optimization of aircraft engine controllers

We present methods to automatically identify and optimize controllers for large-scale complex dynamic systems; in particular, aircraft gas turbine engines. We show how the optimization of different elements within the overall controller can be addressed in an efficient fashion. These elements include local actuator gains, control modifiers, and control schedules. An evolutionary algorithm (EA) is utilized to realize multiobjective optimization on a local as well as a global level, depending on the optimization task at hand. The fitness function comprises performance metrics that incorporate stall margins, exhaust gas temperature, fan-speed tracking error, and local tracking errors. Less attention has been given in the literature to the application of optimization techniques to aircraft engine control systems design, where the controls design and optimization is performed using a full-order engine model and full control systems structures that do not oversimplify the inherent complexities in these highly complex nonlinear dynamic systems. This paper attempts to close that gap.     

光谱扫描装置的运动分析

由于传动机构的刚度有限,扫描装置驱动元件的运动和扫描镜的运动是不一致的.为揭示两者的运动规律,建立了扫描装置的动力模型,该模型考虑了传动机构刚度和系统阻尼的影响.通过对模型的振型分析,得出扫描装置的运动方程,并用Matlab仿真实验对分析结果进行了验证.分析结果表明:驱动元件转子的运动和扫描镜的运动都可视为两种运动分量的合成:一种是两者作为一个刚体的运动,另一种是两者各自独立的运动.分析得到的结论为系统控制和性能评估提供了理论依据.     

Diagnosis of multiple sensor and actuator failures in automotiveengines

Unlike cases where only a single failure occurs, fault detection and isolation of multiple sensor and actuator failures for engines are difficult to achieve because of the interactive effects of the failed components. If faults all appear either in sensors only or in actuators only, many existing residual generators which provide decoupled residual signals can be employed directly to obtain proper fault detection and isolation. However, when both sensor and actuator failures occur at the same time, their mutual effects on residuals make fault isolation particularly difficult. Under such circumstances, further decision logic is required. In the paper, the authors propose a hexadecimal decision table to relate all possible failure patterns to the residual code. The residual code is obtained through simple threshold testing of the residuals, which are the output of a general scheme of residual generators. The proposed diagnostic system incorporating the hexadecimal decision table has been successfully applied to automotive engine sensors and actuators in both simulation and experimental analyses. Enhancement of the present diagnostic performance by implementing an additional sensor is also described     

Control strategies for heavy-duty diesel engine emissions

Emission standards for heavy-duty diesel engines have become significantly more stringent throughout the last 20 years and continue towards zero emissions levels in the future. Modern direct-injected diesels include well-developed combustion systems that have electronically controlled injection systems and robust turbochargers. These technological advancements enable heavy-duty engine manufacturers to meet emission standards through an adjustment in injection timing by using a small array of sensors in concert with the engine control module (ECM). Standards targeted for 2002 and 2007 will require the inclusion of external devices and associated sensors that will create additional degrees of freedom for the ECM and thus a larger sensor array in comparison to current diesel engines. This article outlines the potential impact of these emission standards on control strategies for heavy-duty engines and the associated sensors under "warmed up" conditions     

Nonlinear adaptive torque control of electro-hydraulic load system with external active motion disturbance

This paper develops a high performance nonlinear adaptive control method for electro-hydraulic load simulator (EHLS). The tracking performance of EHLS is mainly affected by the following factors: actuator’s active motion disturbance, flow nonlinear and parametric uncertainties, etc. Most previous studies on EHLS pay too much attention on actuator’s active motion disturbance, while deemphasize the other two factors. This paper concerns EHLS as a motion loading system. Besides actuator’s motion disturbance, both the nonlinear characteristics and parametric uncertainties of the loading system are addressed by the present controller. First, the nonlinear model of EHLS is developed, and then a Lyapunov-based control algorithm augmented with parameters update law is developed using back-stepping design method. The stability of the developed control algorithm is proven via Lyapunov analysis. Both the co-simulation and experiment are performed to validate the effectiveness of the developed algorithm.     

Two-parameter robust repetitive control with application to a novel dual-stage actuator for noncircular Machining

This work presents a robust repetitive controller design for a novel dual-stage actuator system. The dual-stage actuator, which consists of an electrohydraulic actuator for 25-mm-gross motion and a piezoelectric actuator for 40-/spl mu/m fine motion, is designed for noncircular machining application. The controller is designed through a sequence of two single-input-single-output (SISO) designs by exploiting the triangular structure of the two by two actuator system dynamics. The tracking error from the first stage electrohydraulic actuator is used as reference for the second stage piezoelectric actuator. In this master-slave control arrangement, the overall sensitivity function is the product of two sensitivity functions from each actuator's servo loop. Thus, performance is improved at the frequencies where the sensitivity values are already well less than one. In the real-time control implementation, the effects of finite word length are analyzed and addressed via controller order reduction and realization. In an experiment of tracking an automotive cam profile at the rate of 10 cycles per second (600 rpm), the proposed dual-stage servo system generated tracking error of 4-/spl mu/m peak-to-valley and 0.80-/spl mu/m root-mean-square (RMS) value, showing a substantial improvement over the 16 micron peak-to-valley and 2.64-/spl mu/m RMS errors generated by the electrohydraulic servo system alone.