Stable operation process control method for free piston engine

Abstract

The invention discloses a stable operation process control method for a free piston engine. The control method comprises the following steps of: monitoring a pressure signal and a displacement signalin a free piston engine cylinder in real time; utilizing an iterative learning algorithm to control a compression stroke end point by a controller according to a cylinder pressure signal and the displacement signal; when the engine works in expanding stroke, estimating energy generated by current cyclic combustion by the controller according to in-cylinder combustion peak value pressure; giving power generation amount of a current circulating stroke motor according to the estimated current cyclic combustion energy, thereby guaranteeing that a piston assembly can move to a predetermined position to start next cycle under influences of a random combustion cyclical fluctuation. The control method disclosed by the invention can overcome inherent combustion cyclical fluctuation of a gasoline internal combustion engine, so that continuous and stable operation of the free piston engine is guaranteed.

Description

technical field [0001] The invention belongs to the technical field of piston engines, in particular to a method for controlling the stable operation process of a free piston engine. Background technique [0002] As a new type of energy power device, the free piston engine has great development potential and can be used in various power occasions such as hybrid vehicles and extended-range electric vehicles, and has a broad market potential. [0003] Free-piston engines usually have three structures: single-piston, double-piston, and opposed-piston. The main part is composed of an internal combustion engine and an electric motor. [0004] The specific structure of a single-piston free-piston engine is as follows: figure 1 As shown, its mechanical structure is generally composed of a scavenging chamber 6 , a piston assembly 7 , a combustion chamber 8 , an ignition coil 9 and an internal combustion engine part of an injector 10 , a motor part 5 and a return device 4 . [0005...

AI Technical Summary

Problems solved by technology

Due to the energy storage device such as a flywheel and the constraints of the crank-link mechanism in a conventional internal combustion engine, the movement of the piston is relatively fixed, and these disturbances cannot affect the movement of the piston.

However, the free-piston engine cancels the crank-connecting rod and flywheel structure, and the movement of the piston is relatively free, which is easily disturbed by the combustion fluctuations in the cylinder cycle, causing the movement of the free-piston engine to be unstable, and it is difficult to achieve continuous and stable operation.

At present, the difficulty in stable operation due to cyclic combustion fluctuations is one of the main difficulties leading to the large-scale commercial application of free-piston engines

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