Evaluation of the Effect of Chassis Dynamometer Load Setting on CO2 Emissions and Energy Demand of a Full Hybrid Vehicle

Among the solutions that make it possible to reduce CO2 emissions in the transport sector, particularly in urban traffic conditions, are hybrid vehicles. The share of driving performed in electric mode for hybrid vehicles is highly dependent on motion resistance. There are different methods for determining the motion resistance function during chassis dynamometer testing, leading to different test results. Therefore, the main objective of this study was to determine the effect of the chassis dynamometer load function on the energy demand and CO2 emissions of a full-hybrid passenger car. Emissions tests according to the New European Driving Cycle (NEDC) were carried out on a chassis dynamometer for three different methods of determining the car’s resistance to motion. The study showed that adopting the motion resistance function according to different methods, results in differences in CO2 emissions up to about 35% for the entire cycle. Therefore, the authors suggest that in the case of tests carried out with chassis dynamometers, it is necessary to also provide information on the chassis dynamometer loading function adopted for the tests.

Energy Management Strategy for Hybrid Multimode Powertrains: Influence of Inertial Properties and Road Inclination

Multimode hybrid powertrains have captured the attention of automotive OEMs for their flexible nature and ability to provide better and optimized efficiency levels. However, the presence of multiple actuators, with different efficiency and dynamic characteristics, increases the problem complexity for minimizing the overall power losses in each powertrain operating condition. The paper aims at providing a methodology to select the powertrain mode and set the reference torques and angular speeds for each actuator, based on the power-weighted efficiency concept. The power-weighted efficiency is formulated to normalize the efficiency contribution from each power source and to include the inertial properties of the powertrain components as well as the vehicle motion resistance forces. The approach, valid for a wide category of multimode powertrain architectures, is then applied to the specific case of a two-mode hybrid system where the engagement of one of the two clutches enables an Input Split or Compound Split operative mode. The simulation results obtained with the procedure prove to be promising in avoiding excessive accelerations, drift of powertrain components, and in managing the power flow for uphill and downhill vehicle conditions.

The Impact of the Human Body Position Changes During Wheelchair Propelling On Motion Resistance Force

Purpose - The aim of this research was to analyse the impact of the human body position changes caused by propelling a wheelchair with the pushrim propulsion on the value of motion resistance force. Material and methods - The research was carried out in the group of six persons propelling a wheelchair whose frame was inclined, in respect to the horizontal plain, under the angle of 0°, 7° and 14°. The area of the position variability of the human body centre of gravity and the coefficients of wheelchair rolling resistance have been determined in the research. Results -The results obtained, depending on the wheelchair inclination angle, ranged from 9.82 N to 22.81 N. In addition, it has been determined that the percentage increase in rolling resistance force, with the body position proper for the initial propulsion phase, in relation to the body position for the final propulsion phase, amounted to: 35.6% for the inclination angle of 0°, 43.2% for the inclination angle of 7°, and 48.3% for the inclination angle of 14°. Conclusion - the research done demonstrated the impact of the centre of gravity position change on the change of motion resistance. Thus, the research supplemented knowledge with a new parameter which, like a surface type and wheel type, affects motion resistances.

Fatigue damage healing model based on dislocation reverse-back under unconstraint vibration condition for copper film

In this investigation, it is found that the generated elastic stress during the unconstraint vibration treatment process can act as the dislocation driving stress on the dislocation in the micro-scale. When the sum of the dislocation driving stress, the image stress and the back stress exceeds the motion resistance of the dislocations in a pile-up, the dislocations begin to reverse back, and the pile-up disappear. Based on this principle, a fatigue damage-healing model under unconstraint vibration condition was proposed. The verified results showed that the damaged copper film can be effectively healed by the vibration guided by the model calculation.