Rebreather system

Abstract

A semi-closed rebreather that uses a “normal open” type of solenoid valve to control the flow of replenishment gas supplied to the rebreather circuit by at least one replenishment gas cylinder. In the absence of energy, the rebreather system takes the open condition, thereby allowing a replenishment gas flow with a maximum flow rate predetermined during the initial design or adjustment step.

The invention claimed is: 
     
         1 . A rebreather system comprising:
 a mouthpiece;   a first breathing bag for exhaled breathing gas mixture in communication with said mouthpiece through a hose;   a second breathing bag for the exhaled breathing gas mixture from which carbon dioxide has been removed, said second breathing bag also being in communication with the mouthpiece through a hose;   a canister removing the carbon dioxide from the exhaled breathing gas mixture interposed between said first and said second breathing bags;   a tank for a predetermined amount of a replenishment gas mixture replenishing oxygen level in the breathing gas mixture, where said replenishment gas mixture is stored at high pressure;   a tube supplying the replenishment gas mixture from the tank to the second breathing bag, a pressure controlled supply unit supplying a predetermined amount of the replenishment gas mixture being provided in said tube, said supply unit being servo-controlled;   one or more sensors or combination of sensors selected among the group consisting of: pressure gauge sensor, oxygen level sensor, carbon dioxide level sensor, depletion sensor for the canister removing carbon dioxide, and filling level sensor for the tank with the replenishment gas mixture; and   an electronic control unit that receives measurement signals from said one or more sensors or combination of sensors and that generates, as a function thereof, signals controlling said supply unit,   wherein said supply unit comprises a servo-controlled supply valve of a normally open type, said servo-controlled supply valve, in absence of a control actuation signal, automatically and firmly taking a condition enabling the replenishment gas mixture to be supplied.   
     
     
         2 . The rebreather system according to  claim 1 , further comprising a flow rate regulator for a flow of replenishment gas mixture replenishing an oxygen concentration level in the breathing gas mixture. 
     
     
         3 . The rebreather system according to  claim 1 ,
 wherein the electronic control unit is a the processor and executes a control program, by which said electronic control unit and the one or more sensors or combination of sensors are set to detect at least one or more of the following values or combinations of the following values: breathing gas pressure, oxygen level in one or both of the first breathing bag or second breathing bag, carbon dioxide level in the first breathing bag and/or second breathing bag, depletion level of the carbon dioxide canister, level of the replenishment gas mixture in the tank, or pressure of the replenishment gas in the tank, and   wherein the control program sets the control unit to determine the amount of the replenishment gas mixture be supplied in a circuit necessary to replenish a predetermined oxygen level in the breathing gas mixture and to generate control signals for the supply unit corresponding to an actuation of said supply unit for feeding said amount of the replenishment gas to be supplied in the circuit necessary to replenish a predetermined oxygen level in the breathing gas mixture.   
     
     
         4 . The rebreather system according to  claim 1 , wherein, in combination with the electronic control unit, an interface is provided displaying one or more measurement data and/or other quantities determined by the one or more sensors or combination of sensors, or as a function of values measured by said one or more sensors and/or alphanumeric or graphical messages or information. 
     
     
         5 . The rebreather system according to  claim 4 , wherein said interface comprises one display monitor controlled by a graphics processing unit that directly executes a graphics display program or is controlled by the control unit to be set for a graphic representation displaying one or more measurement data and/or other quantities determined by the one or more sensors or combination of sensors, or as a function of values measured by one or more of said one or more sensors or combination of sensors, or said alphanumeric or graphical messages or information. 
     
     
         6 . The rebreather system according to  claim 1 , wherein said electronic control unit is provided as an alternative or in combination with an interface for connection with a command and/or data input system that is connected thereto both by cable or wireless connection and/or with a port for the connection to peripherals storing and/or transmitting programs or other data libraries. 
     
     
         7 . The rebreather system according to  claim 1 , further comprising an exhaust valve for a predetermined amount of the breathing gas mixture for maintaining a predetermined pressure of the breathing gas mixture. 
     
     
         8 . The rebreather system according to  claim 7 , wherein said exhaust valve is configured to be activated or deactivated by a command of the electronic control unit. 
     
     
         9 . The rebreather system according to  claim 1 , wherein the electronic control unit is provided with a functional diagnostics automatic sub-system, which, in case of detection of one or more non-correct operating conditions of the electronic control unit and/or of one or more peripherals connected to said electronic control unit sets the supply valve in an opening condition stopping automatically irreversibly or vitally an input of the control signal of the supply valve that maintains the supply valve in a closed condition. 
     
     
         10 . The rebreather system according to  claim 1 , wherein the gas mixture replenishing oxygen is a mixture of oxygen and of at least one additional physiologically inert gas, a content of the oxygen in said mixture ranging from 22% to 60% with respect to a non-breathable gas component. 
     
     
         11 . The rebreather system according to  claim 1 , further comprising at least one second tank for a replenishment gas having an oxygen content higher than 60%, said second tank being connectable to the breathing loop of the rebreather alternately to the a tank for a predetermined amount of a replenishment gas mixture replenishing oxygen level in the breathing gas mixture.