NVH Optimization of Range Extender Engines by Electric Torque Profile Shaping
Range extender operation in an electric vehicle should be imperceptible to the driver from a noise/vibration standpoint. Rolling torque compensation allows virtually vibration-free range extender engine operation by utilizing a balanced counter-rotating inertia that is geared to the cranktrain. The combustion process results in engine torque fluctuations that could cause gear rattle in such a system due to a combination of torque reversal and lash in the geared connection. This brief paper addresses the problem of gear rattle in a rolling torque compensation system. First, a preloaded split gear is introduced as a potential mechanical solution to eliminate the clearance in the gear contact zone. In addition, an approach for a mechatronic solution involving active shaping of the generator torque is introduced. This methodology includes measurement of the combustion engine torque via cylinder pressure indication data, calculation of allowable torque limits, and the determination of a generator torque profile to address gear rattle. A multicriteria cost function is introduced to determine the optimal torque within the established constraints. Variations of the cost function are investigated with respect to their impact on efficiency and range extender acoustics.
Potential of Real-Time Cylinder Pressure Analysis by Using Field Programmable Gate Arrays
In this paper, a Field Programmable Gate Array (FPGA) was used to implement a real-time cylinder pressure analysis. The goal of the project was to improve the accuracy of calculated heat release and center of combustion calculations to enhance the precision of engine control functions. Compared to today’s real-time pressure analysis systems, several additional physical effects were taken into account for this objective. The wall heat transfer was calculated based on the approach published by Hohenberg. A chemical equilibrium with six substances was assumed for the mixture composition and a real-time calculation method was developed. Furthermore, a two-zone model was adapted and implemented for this realtime analysis. The validation of the results and the rating of the improvement in precision were based on GT-SUITE simulation results as an offline reference tool. Compared to state-of-the-art analysis systems, it was possible to reduce the average error of the center of combustion position from 1.6° to 0.5° crank angle (CA) by taking the investigated effects into account. Moreover, it was possible to significantly reduce the time required for the calculation from one complete combustion cycle to 0.2°CA at an engine speed of 3,000 rpm by using a continuous calculation method on the FPGA. This led to an additional improvement of the ability to control the engine, especially under highly dynamic operation conditions.
A peptide muscarinic toxin from the Green Mamba venom shows agonist-like action in an inhibitory avoidance learning task.
A peptide, muscarinic toxin 2 (MTX2), isolated from Dendroaspis angusticeps venom was previously shown to displace the specific binding of [3H]pirenzepine, a muscarinic M1 receptor ligand, from rat brain synaptosomal membranes. We have tested MTX2 for muscarinic agonist or antagonist actions in an inhibitory avoidance task in rats. Infusion of the muscarinic receptor antagonist scopolamine into the hippocampus of rats immediately after the training period produced amnesia, whereas the muscarinic agonist oxotremorine increased retention. When MTX2 was injected into the hippocampus of rats after the inhibitory avoidance task, it caused memory facilitation, which could be suppressed by the concomitant infusion of scopolamine. Hence, in this test, MTX2 showed muscarinic receptor agonist-like actions, which are probably mediated by the M1 subtype of muscarinic acetylcholine receptors.