Potential of an Innovative, Fully Variable Valvetrain

Maas, Gerhard; Neukirchner, Heiko; Dingel, Oliver; Predelli, Oliver

doi:10.4271/2004-01-1393

Cited by 8 publications

(3 citation statements)

References 3 publications

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“…11,12 However, most of them cannot provide fully variable valve timing, and too many parts are involved in the valve movement, which makes the mechanism too complex, and mechanical energy loss is big under high speeds. 13 The electromagnetic variable valve mechanism 14,15 is mainly controlled by a solenoid valve. The main problems of this mechanism are the low response speed of electromagnet which limits the mechanism's maximum speed and precisely controllable valve movement and hysteresis.…”

Section: Introductionmentioning

confidence: 99%

Simulation and experimental research of hydraulic pressure and intake valve lift on a fully hydraulic variable valve system for a spark-ignition engine

Chen

Chang

Xie

et al. 2018

Advances in Mechanical Engineering

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A fully hydraulic variable valve system based on spark-ignition engine BJ486EQ is introduced in this article, which can provide fully variable valve lifts, valve timing, and valve opening duration. A simulation model of fully hydraulic variable valve system is established, which is verified through experimental intake valve lift and hydraulic pressure. It is found that pressure fluctuation in hydraulic system of fully hydraulic variable valve system becomes greater with the increase in engine speed, which even leads to ''lift distortion.'' The cam profile of fully hydraulic variable valve system and the structure of the throttling valve which is used to reduce valve seating speed are optimized by simulation. The lift distortion and rebound do not occur in the optimized fully hydraulic variable valve system, which is indicated by the results of simulation and experiments when the engine speed is 5000 r/min, and valve seating characteristics become stable and soft.

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Section: Introductionmentioning

confidence: 99%

Simulation and experimental research of hydraulic pressure and intake valve lift on a fully hydraulic variable valve system for a spark-ignition engine

Chen

Chang

Xie

et al. 2018

Advances in Mechanical Engineering

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“…3 Additionally, these systems add a complex structure with more cams required to control the valve timings. 4,5 Also, not much improvement in the fuel consumption and emission of engines has been obtained by these VVT techniques. Compared with the traditional camshaft-based VVT, an electromagnetic valvetrain (EMV) system has a simple non-camshaft structure and a wide valve-timing operating range.…”

Section: Introductionmentioning

confidence: 99%

Actuator control for a new hybrid electromagnetic valvetrain in spark ignition engines

Shiao

Dat

2013

Proceedings of the Institution of Mechanical Engineers, Part D:

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Valve timings of a spark ignition engine have been limited to a narrow range of alternatives within the constraints of the fuel economy, the emissions and the dynamic performance. Variable valve timing shows promise as a new key technology for improving the fuel consumption and emissions of spark ignition engines. Several techniques have been developed to perform variable valve timing, and the method with the most potential, called a hybrid electromagnetic valvetrain actuator, is an electromagnetic valvetrain with a permanent magnet and electromagnetic coils installed together. In this study, a novel hybrid electromagnetic valvetrain with a permanent magnet and electromagnetic coils, which significantly differs from existing electromagnetic valvetrains, was designed to overcome the drawbacks of conventional electromagnetic valvetrains that have been introduced previously. This new hybrid electromagnetic valvetrain is characterized by a simple structure, simple actuation and an ultra-low actuating power. Magnetic simulation was applied to analyse the magnetic flux density of the electromagnetic valvetrain and to optimize the design parameters. Dynamic simulation results show that the proposed hybrid electromagnetic valvetrain with soft-landing control can fully satisfy the valve dynamics in spark ignition engines. Additionally, the utilization of a permanent magnet and an optimal actuating current to catch and release valves has many advantages in energy consumption for valve catching and releasing when compared with other electromagnetic valvetrains.

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“…Even though some research grade mechanical valve trains (Pierik and Burkhard, 2000;Flierl et al, 2005;Sellnau et al, 2006) are able to support fully variable valve timing & lift control, they usually offer one family of valve lift curves, hence the engine can only be optimized at specific operating conditions (Milovanovic et al, 2005). Overall speaking, the general disadvantages of the mechanical variable valve actuators are complex (Maas et al, 2004) and bulky cylinder head, resulting in high engine center of gravity (CG). All of the mechanical variable valve systems are also limited in their flexibility of output valve profiles and strategies due to mechanical constraints (Milovanovic et al, 2005).…”

mentioning

confidence: 98%

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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Potential of an Innovative, Fully Variable Valvetrain

Cited by 8 publications

References 3 publications

Simulation and experimental research of hydraulic pressure and intake valve lift on a fully hydraulic variable valve system for a spark-ignition engine

Simulation and experimental research of hydraulic pressure and intake valve lift on a fully hydraulic variable valve system for a spark-ignition engine

Actuator control for a new hybrid electromagnetic valvetrain in spark ignition engines

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

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