In conventional internal combustion engines, engine valve displacements are fixed relative to crankshaft position. If these valves were actuated as a variable function of crankshaft angle, significant improvements in fuel economy could be achieved. To this end, a new type of electromagnetic valve drive system (EMVD) for internal combustion engines was more recently proposed. This EMVD incorporates a disk cam with a very desirable nonlinear profile which that functions as a nonlinear mechanical transformer. Modeling and simulation results showed significant advantages of this EMVD over previously designed electromagnetic engine valve drives. In this articles, we describe an experimental implementation of the proposed EMVD, which was developed to confirm these benefits. The EMVD apparatus was designed, constructed, and integrated into a computer-controlled experimental test stand. The experimental results confirm the benefits of using a nonlinear mechanical transformer in a motordriven engine-valve spring system, as seen in the small average power consumption and low valve seating velocity. In addition, a valve transition time sufficient for 6000-rpm engine operation was achieved. The results also suggest ways to improve the EMVD apparatus in the future.

Abstract-This paper discusses mechanical design considerations that are particular to conventionally (i.e., radially) laminated rotors of interior permanent-magnet synchronous machines. Focus is placed on applications where the radial forces due to high-speed operation are the major mechanically limiting design factor. Proper design of the lamination bridges, or ribs, at the rotor outer diameter is explained in terms of the both material considerations and electromagnetic performance impact. The tradeoff of complexity versus performance associated with using strengthening ribs in the magnet cavities is discussed. The sensitivity of the mechanical design limitations to the rotor-shaft mounting mechanism is also highlighted. These effects are then analyzed using finite-element analysis for a 150-N m/6-kW integrated starter/alternator designed for operation up to 6000 r/min with an annular rotor to accommodate a torque converter or clutch assembly. This example demonstrates that it is possible to significantly improve the rotor's structural integrity using the techniques described in this paper with only a very modest impact on the projected machine drive cost.Index Terms-Electrical steel, finite-element analysis (FEA), high speed, interior permanent-magnet (IPM) synchronous machine, laminations, magnetic saturation.

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Abstract-This paper discusses mechanical design considerations that are particular to conventionally (i.e., radially) laminated rotors of interior permanent-magnet synchronous machines. Focus is placed on applications where the radial forces due to high-speed operation are the major mechanically limiting design factor. Proper design of the lamination bridges, or ribs, at the rotor outer diameter is explained in terms of the both material considerations and electromagnetic performance impact. The tradeoff of complexity versus performance associated with using strengthening ribs in the magnet cavities is discussed. The sensitivity of the mechanical design limitations to the rotor-shaft mounting mechanism is also highlighted. These effects are then analyzed using finite-element analysis for a 150-N m/6-kW integrated starter/alternator designed for operation up to 6000 r/min with an annular rotor to accommodate a torque converter or clutch assembly. This example demonstrates that it is possible to significantly improve the rotor's structural integrity using the techniques described in this paper with only a very modest impact on the projected machine drive cost.Index Terms-Electrical steel, finite-element analysis (FEA), high speed, interior permanent-magnet (IPM) synchronous machine, laminations, magnetic saturation.

No abstract