The “Two-in-One” Engine - Porsche's Variable Valve System (VVS)

Brüstle, Claus; Schwarzenthal, Dietmar

doi:10.4271/980766

Cited by 14 publications

(3 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…By either early or late intake valve closing, the Miller cycle can decouple the expansion ratio and the compression ratio of the engine so that the effective compression is significantly lower than the 2 of 26 geometric compression ratio [2,3]. In 1998, Porsche developed the VarioCam Plus system that combines the best features of shifting the timing phases and changes of cam profile [4]. This system applied in the 911 Turbo uses a hydraulic camshaft phaser with helical teeth instead of changing the chain length.…”

Section: Introductionmentioning

confidence: 99%

Study of the Miller Cycle on a Turbocharged DI Gasoline Engine Regarding Fuel Economy Improvement at Part Load

et al. 2020

View full text Add to dashboard Cite

This contribution is focused on the fuel economy improvement of the Miller cycle under part-load characteristics on a supercharged DI (Direct Injection) gasoline engine. Firstly, based on the engine bench test, the effects with the Miller cycle application under 3000 rpm were studied. The results show that the Miller cycle has different extents of improvement on pumping loss, combustion and friction loss. For low, medium and high loads, the brake thermal efficiency of the baseline engine is increased by 2.8%, 2.5% and 2.6%, respectively. Besides, the baseline variable valve timing (VVT) is optimized by the test. Subsequently, the 1D CFD (Computational Fluid Dynamics) model of the Miller cycle engine after the test optimization at the working condition of 3000 rpm and BMEP (Brake Mean Effective Pressure) = 10 bar was established, and the influence of the combined change of intake and exhaust valve timing on Miller cycle was studied by simulation. The results show that as the effect of the Miller cycle deepens, the engine’s knocking tendency decreases, so the ignition timing can be further advanced, and the economy of the engine can be improved. Compared with the brake thermal efficiency of the baseline engine, the final result after simulation optimization is increased from 34.6% to 35.6%, which is an improvement of 2.9%.

show abstract

Section: Introductionmentioning

confidence: 99%

Study of the Miller Cycle on a Turbocharged DI Gasoline Engine Regarding Fuel Economy Improvement at Part Load

et al. 2020

View full text Add to dashboard Cite

show abstract

“…The cam profile switching can be realized using the device described by Lee et al 21 or the cam-switching mechanism reported by Inoue et al 23 and Brüstle and Schwarzenthal. 24 Recently, our group developed a new cam-profile-switching device, as shown in Figure 2. Prototype testing showed that it can realize two-stroke and four-stroke mode switching and it can be adopted in the proposed concept.…”

Section: Pneumatic Hybrid System Conceptmentioning

confidence: 99%

Research on a pneumatic hybrid engine with regenerative braking and compressed-air-assisted cranking

Wang

et al. 2015

Proceedings of the Institution of Mechanical Engineers, Part D:

View full text Add to dashboard Cite

With the aim of improving the energy efficiency of conventional vehicles, this paper proposes a pneumatic hybrid engine concept, which features regenerative braking and compressed-air-assisted cranking functions. In the regenerative braking mode, the engine works as a two-stroke compressor and converts the kinematic energy of the vehicle into compressed air. In the two-stroke air motor mode, a throttle valve in the intake manifold is used to block the ambient air, and an electropneumatic solenoid valve is employed to control the compressed-air injection. The compressor mode is modelled on the basis of thermodynamics and gas dynamics theories and is improved according to the bench test results of a single-cylinder engine converted from a two-cylinder diesel engine. Transient engine cranking tests are also conducted and are discussed. Urban driving-cycle simulation results show that the fuel consumption of a light-duty vehicle with a pneumatic hybrid system can be reduced by 8%.

show abstract

“…In the case under consideration, it was assumed that the time should be comparable to that resulting from the Vibe function, i.e., taking into account the angle of rotation of the crankshaft. Ignoring the detonation combustion situations occurring, for example, in HCCI engines[9,11], the combustion time of which is too short (0.05 ms to 0.2 ms), it can be approximated that in the current combustion systems of engines with GI the burning time is between 0.4ms and 3ms, which is mainly due to the load and the combustion system used, which is approximated by the Vibe function[5]. The time from the theoretical analysis is shorter, 50 to 60%, than the empirical results presented in Figures14-16, because the analysis did not take into account the heat transfer and the effect of slowing down the combustion process for faster volumetric work by the ACC system.The ACC system, which is a viable technical solution, performs an additional volume change using the so-called additional piston with a very low weight (approximately 130 g) and pneumatic support.…”

mentioning

confidence: 99%

The Use of the Fourier Series to Analyze the Shaping of Thermodynamic Processes in Heat Engines

et al. 2021

View full text Add to dashboard Cite

The article presents the application of the Fourier series to theoretical considerations on the method of maximum temperature control in thermodynamic cycles of internal combustion engines equipped with an additional independent kinematic system. The analysis assumes that the processes are zero-dimensional and the gases consumed in the engine cycles are perfect, simplifying the considerations for temperature control as a function of the two variables, pressure and volume, of which the volume as a geometric quantity can be completely controlled. In view of this fact, a predetermined temperature curve was assumed, ultimately reducing the considerations of specific volume changes, that is to say a kinematic system that could implement these changes. Moreover, in the analysis of volume changes, a cycle not used so far in the description of internal combustion engines was used. In the next step, the cycle was modified using the popular Vibe function, which was replaced in the theoretical cycle by two isochoric and isothermal transformations. Heat exchange was completely omitted in the considerations, in that it is of secondary importance, ultimately bringing the temperature function to the function of one variable, the angle of rotation of the crankshaft. Then, the kinematics was divided into the kinematics of the crank-piston system and the additional system, which was approximated with five words from the Fourier series, which in the technique correspond, for example, to the system of oscillators. At the end of the article we have explained one of the ways of actual technical implementation using a single nonlinear oscillator, the so-called ACC system equivalent to a few words from the mentioned Fourier series.

show abstract

The “Two-in-One” Engine - Porsche's Variable Valve System (VVS)

Cited by 14 publications

References 0 publications

Study of the Miller Cycle on a Turbocharged DI Gasoline Engine Regarding Fuel Economy Improvement at Part Load

Study of the Miller Cycle on a Turbocharged DI Gasoline Engine Regarding Fuel Economy Improvement at Part Load

Research on a pneumatic hybrid engine with regenerative braking and compressed-air-assisted cranking

The Use of the Fourier Series to Analyze the Shaping of Thermodynamic Processes in Heat Engines

Contact Info

Product

Resources

About