SYSTEMS AND METHODS FOR TRANSIENT CONTROL OF A FREE-PISTON ENGINE

摘要

A free-piston (“FP”) engine is a type of internal combustion engine with no crankshaft, so that its piston trajectory is no longer constrained by the mechanical linkage. FP engines have a high potential in terms of energy saving given their simple structure, high modularity and high efficiency, among other attributes. One of the technical barriers that affect FP engine technology is a lack of precise piston trajectory control. For example, the presence of a transient period after a single combustion event can prevent the engine from continuous firing. The present subject matter provides a control scheme that can utilize a reference and control signal shifting technique to modify the tracking error and the control signal to reduce the transient period.

主权项

1. A free-piston engine, comprising:
a controller configured to:
compare an actual piston trajectory of an oscillating piston to a reference trajectory,locate a first local extremum for the actual piston trajectory, the extremum corresponding to a first actual reversal point for the oscillating piston,record a first time instant corresponding to the first local extremum,detect a first combustion event by comparing the first time instant to a first reference time index, the reference time index corresponding to a first reference reversal point corresponding to the first actual reversal point, andapply a first reference shift to the reference trajectory upon detecting the first combustion event, the first reference shift corresponding to the difference between the first time instant and the first reference time index; an engine cylinder for slidably receiving the piston; and a force transducer coupled to the piston, wherein the controller is coupled to the force transducer and configured to control the force transducer to influence the piston oscillation such that the actual piston trajectory approximates the reference trajectory.