Driveline Configuration Research Articles

Torque and Center of Combustion Evaluation Through a Torsional Model of the Powertrain

The continuous development of modern internal combustion engine (ICE) management systems is mainly aimed at combustion control improvement. Nowadays, performing an efficient combustion control is crucial for drivability improvement, efficiency increase (critical for spark ignited engines), and pollutant emissions reduction (critical in compression ignited engines). The most important quantities used for combustion control are engine load (indicated mean effective pressure (IMEP) or torque delivered by the engine) and center of combustion, i.e., the angular position in which 50% of fuel burned within the engine cycle is reached. Both quantities can be directly evaluated starting from in-cylinder pressure measurement, which could be performed using the newly developed piezoresistive pressure sensors for on-board applications. However, the use of additional sensors would increase the cost of the whole engine management system. Due to these reasons, over the past years, a methodology that allows evaluating both engine load and the center of combustion with no extra cost has been developed. This approach is based on engine speed fluctuation measurement, which can be performed using the same speed sensor already mounted on-board. The methodology is general and can be applied to different engine–driveline systems with different architectures and combustion orders. Furthermore, it is compatible with on-board requirements, since the evaluation of only one specific harmonic component of interest is required (depending on the engine–driveline configuration under investigation). In order to clarify all the issues related to the application of the presented approach, it has been applied to some different engines, both compression ignited and spark ignited, taking also into account the case of combustion not evenly spaced. For all the analyzed configurations, the results obtained using the estimation algorithm seemed to be adequate to feedback a closed-loop methodology for optimal combustion control.

Longitudinal force distribution using quadratically constrained linear programming

In this paper, a new method is presented for the optimisation of force distribution for combined traction/braking and cornering. In order to provide a general, simple and flexible problem formulation, the optimisation is addressed as a quadratically constrained linear programming (QCLP) problem. Apart from fast numerical solutions, different driveline configurations can be included in the QCLP problem in a very straightforward fashion. The optimisation of the distribution of the individual wheel forces using the quasi-steady-state assumption is known to be useful for the study of the influence of particular driveline configurations on the combined lateral and longitudinal grip envelope of a particular vehicle–driveline configuration. The addition of the QCLP problem formulation makes another powerful tool available to the vehicle dynamics analyst to perform such studies.

Optimization of Magnetic Parameters in Thin Films DRO Storage Elements

The digit current margins of a DRO magnetic film memory are determined by the disturb and writing or restoring thresholds. In an actual memory these thresholds will vary with both the film parameters and the drive line configuration. The effect of the magnetic parameters of the storage elements on these thresholds is determined by measuring the digit current margins of storage element arrays of varied magnetic parameters in a test apparatus simulating the memory operations and drive line configuration. A figure of merit calculated from these margin measurements is introduced and is used to determine the optimum film parameter values. To illustrate the effectiveness of the technique, data obtained during the experimental determination of optimum array coercivity are presented and the resultant figure of merit is discussed. Results indicate that array coercivities of 2.5 to 2.6 Oe yield maximum digit current margins. Interpretation of results of restore current measurements in terms of skew and dispersion currents is also presented.