Abstract
The camless electromagnetic valve train (EMVT), as a fully flexible variable valve train, has enormous potential for improving engine performances. In this paper, a new valve strategy based on the electromagnetic intake valve train (EMIV) is proposed to achieve variable cylinder deactivation (VCD) on a four-cylinder gasoline engine. The 1D engine model was constructed in GT-Power according to test data. In order to analyze the VCD operation with the proposed valve strategy, the 1D model was validated using a 3D code. The effects of the proposed valve strategy were investigated from the perspective of energy loss of the transition period, the mass fraction of oxygen in the exhaust pipe, and the minimum in-cylinder pressure of the active cycle. On the premise of avoiding high exhaust oxygen and oil suction, the intake valve timing can be determined with the variation features of energy losses. It was found that at 1200 and 1600 rpm, fuel economy was improved by 12.5–16.6% and 9.7–14.6%, respectively, under VCD in conjunction with the early intake valve closing (EIVC) strategy when the brake mean effective pressure (BMEP) ranged from 0.3 MPa to 0.2 MPa.
Highlights
Since throttle can restrict the air from flowing into the cylinders, pumping mean effective pressure (PMEP) is high at part load conditions for throttled internal combustion engines
The results showed that after combining the Cylinder deactivation (CDA) with late intake valve closing (LIVC), the pumping loss decreased by 58.9–65.6% and 24.5–35.3% at 2000 rpm and
The above discussions are focused on low engine speed
Summary
Since throttle can restrict the air from flowing into the cylinders, pumping mean effective pressure (PMEP) is high at part load conditions for throttled internal combustion engines. Cylinder deactivation (CDA) has been demonstrated to be a reliable technology for improving fuel economy in gasoline engines under low load conditions at low and middle speed. When some of the cylinders are deactivated, the remaining firing cylinders require more air and fuel to maintain the same BMEP level. The throttle angle is increased and the pumping losses are reduced due to higher intake manifold pressure [1,2], and combustion is generally more complete with larger air-fuel charge motion. The air spring losses are very low [2,3]; approximately 0.02 bar indicated mean effective pressure (IMEP)
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