The invention relates to a
breathing machine oxygen concentration control method. The
breathing machine oxygen concentration control method comprises steps of obtaining the target
oxygen flow velocity of a
breathing machine, controlling the opening degree of a
proportioning valve to be in a critical
valve opening state, obtaining the monitored oxygen flow velocity on the opening degree, calculating a target current value based on the target oxygen flow velocity and the monitored oxygen flow velocity, adjusting the opening degree of the
proportioning valve based on the target current value, obtaining the monitored oxygen flow velocity on the adjusted opening degree, determining whether the target oxygen flow velocity is consistent with the monitored oxygen flow velocity or not, calculating a target current value based on the target oxygen flow velocity and the monitored oxygen flow velocity when the target oxygen flow velocity is not consistent with the monitored oxygen flow velocity, otherwise, maintaining the opening degree of the
proportioning valve. Under a non-
constant pressure, the oxygen concentration can be controlled. In addition, the invention also provides a breathing machine oxygen concentration control device and
system, by employing the breathing machine oxygen concentration
control system without a pressure-reducing valve, the size and weight of the breathing machine oxygen concentration control device are reduced, and the breathing machine oxygen concentration control device and
system are applied to breathing machines which are high in portability.