William F. Resh

Dynamic Modeling of a Variable Displacement Vane Pump Within an Engine Oil Circuit

Automakers and the car-buying public maintain a strong and continuing interest in enhanced vehicle efficiency. Ideally, adaptively controlled oil pumps supply only enough flow within an engine to satisfy its performance requirements. Any extra flow wastes energy. In order to better understand how to improve engine and engine oil circuit efficiency, and to assess pump stability, a detailed dynamic model of a variable displacement vane pump (VDVP) is developed. This detailed pump model is mated to a simplified engine oil circuit model. This marriage allows for a detailed prediction of pump response under various simulated engine operating conditions. The VDVP modeled here adapts its pump chamber volumes according to 1) the feedback oil pressure provided from the engine oil circuit and 2) according to the sizing and installed compression loading of an internal spring. Many phenomena such as internal leakage from one pump chamber volume to another, variable oil conditions such as aeration and viscosity, as well as variations in choice for the internal spring rate and preload can be investigated for their effects on oil pump behavior and performance within the simplified oil circuit.Copyright

COMPUTER AIDED ENGINEERING IN ENGINE DESIGN.

This paper discusses computer aided engineering (CAE) in engine design and the improvements that led to the increased role that CAE has in todays engine design process. Improvements in the areas of tools, organ- isation, program activity, supplier involvement, and communication have helped to increase the role of CAE. The role that CAE has today is helping to improve the competitiveness of engine manufacturers.

Computer Aided Simulations in Machining Applications

Computer applications have been widely used to assist product design. The successes and sophistication of computer aided engineering (CAE) techniques are respectfully recognized in this field. CAE applications in the manufacturing area however are still developing, although the manufacturing community is increasingly starting to pay attentions to computer simulations in its daily workings. This paper will briefly introduce some of these applications and promote awareness of computer simulations in manufacturing area. It contains four main sections: finite element analysis (FEA) in machining fixture design, FEA applications in component assembly, machining process simulations and machining vibrations in the milling operation. Each section comes with a practical case study, potential benefits are identified and conclusions are presented by using an integrated design and analysis approach. It is hoped that implications of computer simulations would enhance product quality, shorten the product development cycle, and make the manufacturing processes more robust.

FEA applications in milling chatter stability analysis

Regenerative chatter is a major hurdle to the productivity and quality of machining operations. This is because of the undesirable surface finish, excessive tool wear and deteriorated dimensional accuracy. Machining chatter analysis techniques examine the stability of a closed-loop model of machining forces and tool-workpiece system. This model is based on mathematical manipulations of machining forces and the dynamic responses of machining tooling. Almost all techniques derive the dynamic responses from physical test. In this paper, a novel approach of milling chatter stability analysis is introduced by using FEA applications to obtain the dynamic responses of the machine tool. The accuracy of this methodology is validated by machine shop tests.