Two-Step Variable Valve Actuation for Fuel Economy, Emissions, and Performance

Sellnau, Mark; Rask, Eric

doi:10.4271/2003-01-0029

Cited by 74 publications

(28 citation statements)

References 35 publications

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“…Valve strategy of proportional flow control mode The simulation of a set of valve profiles for both intake and exhaust valves based on various control voltages is presented in Figure 17. Figure 17 depicts that the valve lift, timing and valve overlap can be adjustable through the proportional flow control system, and hence it forms a reasonable valve strategy which matches with the general valve profiles for throttleless four-stroke spark ignition engines (Allen and Law, 2002), resulting in reduction of pumping loss (Sellnau and Rask, 2003). It shows that the dual-mode EHFVVT system has the potential to eliminate the traditional throttle valves in the gasoline engines.…”

Section: Simulation Of Valve Strategies For Fully Variable Valvementioning

confidence: 95%

Modeling and simulation of a dual-mode electrohydraulic fully variable valve train for four-stroke engines

Wong

Tam

2008

Int.J Automot. Technol.

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In modern four-stroke automotive engine technology, variable valve timing and lift control offer potential benefits for making a high-performance engine. In this paper, a novel design named dual-mode electrohydraulic fully variable valve train (EHFVVT) for both engine intake and exhaust valves is introduced. The system is mainly controlled by either proportional flow control valves or proportional pressure relief valves, and hence two different families of valve displacement patterns can be achieved. The construction of the mathematical model of the valve train system and its dynamic analysis are also presented in this paper. Experimental and simulation results show that the dual-mode electrohydraulic variable valve train can achieve fully variable valve timing and lift control, and has the potential to eliminate the traditional throttle valve in the gasoline engines. With the proposed system, the engine performance at various speeds and loads will be significantly improved. NOMENCLATURE A 1 : cross-section area of the master cylinder piston (m 2 ) A 2 : cross-section area of the valve cylinder piston (m 2 ) A c : cross-section area of check valve orifice (m 2 ) A r : cross area of pressure relief valve orifice (m 2 ) C d : discharge coefficient of valve orifice C tp1 : leakage coefficient of the master cylinder (m 3 / s·Pa) C tp2 : leakage coefficient of the valve cylinder (m 3 /s·Pa) D : tappet displacement (m) d : hydraulic pipe diameter (m) d p : poppet valve diameter (m) F st1max : maximum static friction force on the master cylinder piston (N) F st2max : maximum static friction force on the valve cylinder piston (N) F co1 : sliding friction on the master cylinder piston (N) F co2 : sliding friction on the valve cylinder piston (N) F r1 : friction force on the master cylinder piston (N) F r2 : friction force on the valve cylinder piston (N) ΔF 1 : resultant force on the master cylinder piston (N) ΔF 2 : resultant force on the valve cylinder piston (N) F : load on poppet valve (N) F 0 : preload in disk-spring stack (N) F pre : preload in valve spring (N) g : acceleration of gravity=9.81 m/s 2 K g : stiffness of valve spring (N/m) K 1 : stiffness of disk-spring stack (N/m) K : gain of proportional flow control valve (m/V) K' : gain of proportional pressure relief valve (Pa/V) l 2 : length of hydraulic pipe (m) m 1 : mass of the master cylinder piston (Kg) m 2 : mass of the valve cylinder piston (Kg) P o : set pressure (Pa) P 1 : operating pressure in the master cylinder (Pa) P 2 : operating pressure in the valve cylinder (Pa) P L : residual gas pressure in combustion chamber (Pa) ΔP : pressure drop along the pipe to the valve cylinder (Pa) Q 1 : hydraulic flow generated by the master cylinder (L/min) Q 2 : hydraulic flow into the valve cylinder (L/min) Re : reynolds number r : base circle radius of input cam (m) u : proportional valve control signal (V) V 1 : initial volume of the master cylinder (m 3 ) V 2 : initial volume of the valve cylinder (m 3 ) v 2 : flow velocity in the pipe to the valve cylinder (m/ ...

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Section: Simulation Of Valve Strategies For Fully Variable Valvementioning

confidence: 95%

Modeling and simulation of a dual-mode electrohydraulic fully variable valve train for four-stroke engines

Wong

Tam

2008

Int.J Automot. Technol.

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“…There are three main categories of VVA: pure mechanical [6], [8], [10], electro-hydraulic [1], and electromechanical [4], [9]- [12]. The various mechanical actuators are mainly improved designs based on the current valvetrain.…”

Section: Background and Motivationmentioning

confidence: 99%

“…This is due to the fixed valve timing with respect to crank shaft angle independent of different operation conditions. But research has shown that variable valve timing (VVT) can achieve higher fuel efficiency, lower emissions, higher torque output, and throttleless engine control [1]- [6].…”

Section: Introductionmentioning

confidence: 99%

Nonlinear System Modeling, Optimal Cam Design, and Advanced System Control for an Electromechanical Engine Valve Drive

Qiu

Perreault

Keim

et al. 2012

IEEE/ASME Trans. Mechatron.

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Abstract-A cam-based, shear force actuated electromechanical valve drive system offering variable valve timing in internal combustion engines was previously proposed and demonstrated. To transform this concept into a competitive commercial product, several major challenges need to addressed, including the reduction of power consumption, transition time, and size. As shown in this paper, by using nonlinear system modeling, optimizing cam design, and exploring different control strategies, the power consumption has been reduced from 140 W to 49 W (65%), the transition time has been decreased from 3.3 ms to 2.7 ms (18%), and the actuator torque requirement has been cut from 1.33 N-m to 0.30 N-m (77%).Index Terms-Open-loop control, optimal cam design, nonlinear friction model, variable valve timing.

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“…The variable valve timing (VVT) changes camshaft phase of intake valve with respect to exhaust valve while variable valve lift (VVL) provides different valve displacements. The VVT controls valve independent of crank angle thus results in reduction in CO2 emission by 20%, an improvement of 15% in fuel economy, an improved torque output of 10% and HC (Hydrocarbon) emission at cold start is reduced by 50% [1][2][3][4][5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

“…The main streaming actuators commercialized are Toyota VVT-i, Honda VTEC, Hitachi VEL, Nissan Neo VVL, Mitsubishi MIVEC and Mazda S-VT. 2 The present VVT systems lack continuous timing change, added the complexity to the engine and foremost engine torque output improvement is less [3]. In recent year fully flexible double solenoid valve actuator (DSVA) is prototyped but not yet commercialized due to inherent problem of acoustic noise, high power consumption, complexity, control and mechanical wear.…”

Section: Introductionmentioning

confidence: 99%

Design and Simulation of Hybrid Double Solenoid Valve Actuator

Aslam¹,

Li²,

Wang³

et al. 2017

dtetr

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Abstract. This paper proposes a novel hybrid valve actuator (HVA) with permanent magnet (PM) and electromagnet (EM) magnetomotive force (MMF) for variable valve timing camless engine. Traditional double solenoid valve actuator (DSVA) has inherent problem of high power consumption, as armature is at equilibrium position away from electromagnet therefore to move armature to open/close position and for keeping armature latched to EM. Hybrid PM/EM valve actuator is proposed in this study. The finite element analysis is performed with Ansys Maxwell on static characteristics of traditional DSVA and HVA on bases of actuator holding force. The equivalent model of static analysis is introduced into Ansys Simplorer for dynamic analysis. The simulation results depict reduce power consumption and transition time of proposed HDSVA over DSVA.

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Two-Step Variable Valve Actuation for Fuel Economy, Emissions, and Performance

Cited by 74 publications

References 35 publications

Modeling and simulation of a dual-mode electrohydraulic fully variable valve train for four-stroke engines

Modeling and simulation of a dual-mode electrohydraulic fully variable valve train for four-stroke engines

Nonlinear System Modeling, Optimal Cam Design, and Advanced System Control for an Electromechanical Engine Valve Drive

Design and Simulation of Hybrid Double Solenoid Valve Actuator

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