Pneumatic Regenerative Engine Braking Technology for Buses and Commercial Vehicles

As an alternative to the electric hybrid powertrain, air-hybrid engine concepts have the potential to achieve regenerative braking and air-assisted engine operations for low-carbon vehicle applications. Over the last few years, systematic studies have been carried out by the authors on a number of air-hybrid engine concepts. This paper presents the modelling and experimental results of air-hybrid engine operation enabled by fully variable valve actuation (FVVA). The principle and key operating features of such an air-hybrid engine will be presented first. This is followed by a detailed theoretical analysis of the two-stroke compression and expansion operations enabled by the FVVA system. Finally, experimental results will be presented with regard to the actual performance of a single-cylinder engine operating in the compression mode and expansion mode through the Lotus active valve train system.

Section: Discussionmentioning

confidence: 99%

Theoretical and experimental studies of air-hybrid engine operation with fully variable valve actuation

Zhao

Psanis

et al. 2011

“…As shown in Fig. 16, the air tank pressure has limited effect on the torque variation of the engine during the transient load 25 increase process since the torque difference between each tank pressure is less than 2%. The explanation is that the total intake flow mass of the engine has limited influence on the transient performance of the engine.…”

Section: Analysis Under Transient Conditionsmentioning

confidence: 99%

“…The simulation showed that the pneumatic hybridisation could recover about 10% of total energy under different conditions. Lee et al 23–25 studied a cost-effective mild hybrid pneumatic engine concept for buses and commercial vehicles. The simulation showed that the fuel mass consumed during the New European Driving Cycle (NEDC) was 677 g for a standard vehicle and 631.2 g for a hybrid pneumatic vehicle, indicating a fuel saving effect of 6.8%.…”

Section: Introductionmentioning

confidence: 99%

Study of a hybrid pneumatic-combustion engine under steady-state and transient conditions for transport application

Fang

et al. 2019

In this study, a new form of hybrid pneumatic combustion engine based on compressed air injection boosting is proposed. The hybrid pneumatic combustion engine regenerates the wasted energy during engine brake to improve the engine performance achieving better fuel economy. The mathematic model of the hybrid pneumatic combustion engine including a supercharged engine and the compressed air tank has been established. The steady-state and transient performance of the engine are analysed. Results show that the air injection boosting system can effectively improve the steady-state performance. Under the speed of 1900 r/min and 100% load, the engine torque and power can be increased from 1039 N m, 206.9 kW to 1057 N m, 210 kW by adopting air injection boosting with the injection pressure of 0.5 MPa. Effects of air injection parameters are also studied, showing that better performance can be achieved under higher air tank pressure and larger injection hole diameter. In addition, a transient analysis is completed under the speed of 1100 r/min. The result shows that when air injection boosting is used, the responding time of the engine to an instant load increase can be potentially reduced from 5.5 to 3.5 s under the injection pressure and duration of 0.5 MPa and 3 s. Meanwhile, the tank pressure has limited influence on the transient performance of the engine.

“…Lee et al 13 worked on a novel cost-effective air hybrid powertrain concept for buses and commercial vehicles. The concept is simple because it requires only a few modifications to the intake of the engine by adding two one-way valves and an air tank.…”

Section: State Of Art Reviewmentioning

confidence: 99%

Required time response of a variable valve actuator equiping a hybrid pneumatic–combustion engine

Basbous

Younès

Ilinca

et al. 2012

This work is a part of a research program that aims to modify a conventional internal combustion engine and turn it into a hybrid pneumatic–combustion engine. The hybrid pneumatic–combustion engine should be able to convert mechanical energy into compressed air and convert compressed air back into mechanical energy. The potential application for the concept is any use of the internal combustion engine where the load oscillates between a negative and a positive value, such as automobiles and hybrid wind diesel systems for remote area power generation. In the first application, during vehicle decelerations, an excess of power occurs, and a negative load could be applied to the engine, whereas during vehicle accelerations, a positive load is applied. In the second application, if the generated wind power is higher than consumption demand, then the load applied to the engine could be negative, and if the generated wind power is lower than consumption demand, then the load is positive. In previous work, we exposed an optimization followed by a fuel-saving evaluation of a new hybrid pneumatic–combustion engine concept that uses a variable valve actuator system. The optimization of the valve actuation was based on ideal thermodynamic cycle modeling, assuming therefore an instant response of the variable valve actuator system. In the present work, a more realistic analysis of the system is provided by taking into consideration the dynamic response of the variable valve actuator system. Variable valve actuators have been widely studied for optimizing performance and fuel consumption of the internal combustion engine, especially in spark-ignition engines. For these engines, it is possible to reduce the pumping losses and to optimize the engine filling by controlling the intake and exhaust valve opening and closing angles, as well as their lifts. However, the variation of valve actuation crank angles required in a conventional internal combustion engine is significantly smaller than the one required in the hybrid pneumatic–combustion engine. This paper describes, through simulation, how the valve time response affects the performance of the hybrid pneumatic–combustion engine and recommends a required valve time response.