Variable valve timing allows improvements of internal combustion engines and can be achieved by camless actuation technology. In this paper we consider an electromechanical valve (EMV) actuator. One of the main problems in the EMV actuator is the noise and wear associated with high contact velocities during the closing and opening of the valve. The contact velocity of the actuator parts can be ...

In conventional internal combustion (IC) engines, engine valve displacements are fixed relative to crankshaft position. If these valves are actuated as a variable function of crankshaft angle, significant improvements in fuel economy can be achieved. Existing electromagnetically actuated variable-valve-timing (VVT) systems characteristically use springs to provide the large inertial power to mo...

The timing of the valves of a hydraulic motor plays an important role in determining the throttling energy. To reduce this dominating energy loss, the timing of the valves must allow the fluid in the chamber to be precompressed and decompressed such that there is minimal pressure differential across the transitioning valve. The optimal valve timing to achieve precompression and decompression is...

ABSTRACT Stringent NOx and particulate emission constraints require high levels of exhaust gas recirculation. In this paper we model and analyze a Variable Valve Timing methodology that in steady-state achieves large levels of internal Exhaust Gas Recirculation (iEGR) or residual charge in Compression Ignition Direct Injection (CIDI) engines. Current external Exhaust Gas Recirculation (eEGR) te...

Research has shown that variable valve timing (VVT) can improve significantly the performance of internal combustion (IC) engines, including higher fuel efficiencies, lower emissions, and larger torque outputs at each point of the engine map. To achieve independent and continuous VVT for each valve, an electromechanical valve drive (EMV) system with a custom-designed limited-angle actuator was ...

At partial load, traditional automotive gasoline engines have high pumping losses due to the throttling of intake charge for load control. Variable Valve Timing (VVT) and introduction externally cooled EGR could reduce but only with a very limited effect. On other hand, in medium full range, engine cannot utilize compression ratio limitations knocking. A variable displacement, device which util...

In a 69 year old woman with a "sticking" Björk-Shiley mitral prosthesis, the diagnosis was suggested by both the two-dimensional and the Doppler ultrasound examinations. In particular, the findings of early diastolic paradoxic septal motion, intermittent delayed opening of the prosthetic disc and variable timing of the onset of mitral valve inflow were believed to be diagnostic of a sticking ti...