Variable Valve Actuation and Diesel Engine Retarding Performance

Hu, Haoran; Israel, Mark A.; Vorih, Joseph M.

doi:10.4271/970342

Cited by 12 publications

(5 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A detailed derivation is found in Appendix A. 4. By the assumption mentioned above, we obtain that both enthalpy flows are related by…”

Section: Early Evomentioning

confidence: 91%

See 1 more Smart Citation

A method to quantify the advantages of a variable valve train for CI engines

Moretto,

Hänggi,

Omanovic

et al. 2023

International Journal of Engine Research

View full text Add to dashboard Cite

Today’s CI engines are subject to strict regulations of pollutant emissions and ambitious fuel consumption targets. Therefore, the interaction between the engine and the exhaust aftertreatment system (ATS) has become increasingly important. Numerous studies have shown that a variable valve train (VVT) improves the interaction between engine and ATS. However, most of these studies either quantify the advantage on a specific engine or only present complex CFD models, such that the results are not easily transferable to different engines. Thus, engine manufacturers cannot directly use these results to assess the advantage of various VVT strategies for their engines. In this paper, we propose a cycle-discrete cylinder model based on first principles which allows to simulate various VVT strategies. In contrast to present methods based on CFD, the proposed cylinder model can be realized with the equations presented. Furthermore, the model is identified with measurement data of an engine without a VVT. A separate engine, which is retrofitted with a fully VVT, is used to validate the proposed modeling approach. Using the identified model in combination with a mean-value model of the air path, we are able to simulate the effects of early intake valve closing, early exhaust valve opening, and cylinder deactivation for a complete CI engine that has no VVT installed. The model is then used to highlight the advantage of a VVT for two scenarios at part-load operation. At cold start, where the temperature of the ATS must be increased quickly, variable valve timing achieves higher enthalpy flows to the ATS while also lowering engine-out NOx emissions when compared to a standard engine strategy. If the ATS is at the operating temperature, cylinder deactivation achieves significantly higher enthalpy flows which prevents the ATS from cooling down. In addition, cylinder deactivation also lowers fuel consumption and engine-out NOx emissions.

show abstract

“…A detailed derivation is found in Appendix A. 4. By the assumption mentioned above, we obtain that both enthalpy flows are related by…”

Section: Early Evomentioning

confidence: 91%

“…[1][2][3] In addition, a VVT can also be used for engine braking. 1,4 Second, numerous authors assess the trade-off between engine efficiency and engine-out emissions. The most prominent example is the use of early intake valve closing (IVC), which improves engine brake efficiency due to reduced pumping loss.…”

Section: Introductionmentioning

confidence: 99%

A method to quantify the advantages of a variable valve train for CI engines

Moretto,

Hänggi,

Omanovic

et al. 2023

International Journal of Engine Research

View full text Add to dashboard Cite

show abstract

“…Further since is continuous in , then is uniformly continuous in . Moreover, from (14). The Barbalat's lemma can now be applied to show that as .…”

Section: Speed-gradient Methodologymentioning

confidence: 99%

“…It allows smooth braking torque variations for a given speed, and thus, full integration with the conventional friction brakes. Due to the expected benefits, many engine manufacturers are intensively pursuing the development of appropriate hardware [14]. In this type of compression braking, the valves are activated by variable exhaust camshaft phasing actuators so that is why continuously variable BVO is possible.…”

Section: Variable Compression Braking Mechanismmentioning

confidence: 99%

Speed gradient approach to longitudinal control of heavy-duty vehicles equipped with variable compression brake

Druzhinina

Stefanopoulou

Moklegaard

2002

IEEE Trans. Contr. Syst. Technol.

View full text Add to dashboard Cite

This paper considers a longitudinal speed control problem for heavy-duty vehicles equipped with variable compression brake. The use of compression brake reduces the wear of the conventional friction brakes, and it is, thus, a preferred way of controlling the vehicle speed during a steady descent or noncritical braking maneuvers. To perform more aggressive (critical) braking maneuvers or control vehicle speed during large changes in the grade, the compression brake must be coordinated with gear ratio adjustments and friction brakes. In this paper we develop nonlinear controllers that accomplish both noncritical and critical maneuvers. We also show how distance constraints from other vehicles in traffic may be included. The design technique is based on the speed-gradient (SG) approach, whereby the control action is chosen in the maximum descent direction for a scalar goal function. The nominal goal function is selected to address the speed regulation objective and, then, it is appropriately modified by barrier functions to handle the critical maneuver requirements. Two ways to handle the uncertainty in the road grade are discussed: through the use of an integral action of the SG controller for constant (but unknown) grades, and through the use of an added differential action for varying grades.

show abstract

“…The continuously variable braking torque can be achieved through controlling a brake valve opening using a variable valve timing actuator [5]. We have previously studied the effects of continuously varying valve timing on vehicle response in [2,3,8,91.…”

Section: Introductionmentioning

confidence: 99%

Speed control experiments for commercial heavy vehicles with coordinated friction and engine compression brakes

Druzhinina

Stefanopoulou

2002

Proceedings of the 2002 American Control Conference (IEEE Cat. No.CH37301)

View full text Add to dashboard Cite

In this paper we describe the development and experimental validation of a simple coordination scheme between friction and engine compression brakes for a Class 8 Freightliner truck used as a development platform in the California PATH program. The coordination scheme is tuned to minimize the use of friction brakes while maintaining the speed tracking performance of the closed-loop braking controller that utilizes the friction (service) brakes only. Through the coordination scheme, a PID controller command is interpreted~as a braking torque demand and split into a friction brake command and compression brake command. The split is based on the models for the compression braking torque and friction braking torque developed and identified from "field' experiments performed in Crow's Landing. The results of closedloop experiments show that the integration of the compression brake into the speed control framework reduces the usage and wear of the conventional friction brakes.

show abstract

Variable Valve Actuation and Diesel Engine Retarding Performance

Cited by 12 publications

References 12 publications

A method to quantify the advantages of a variable valve train for CI engines

A method to quantify the advantages of a variable valve train for CI engines

Speed gradient approach to longitudinal control of heavy-duty vehicles equipped with variable compression brake

Speed control experiments for commercial heavy vehicles with coordinated friction and engine compression brakes

Contact Info

Product

Resources

About