Abstract:
A breathing system includes a container to store a gas under pressure, wherein the gas includes air or oxygen. The container includes an outlet through which the gas exits the container. The breathing system further includes a generator system including a generator in operative connection with the container outlet such that energy is supplied to the generator by the pressurized gas. The generator converts the energy supplied by the pressurized gas to electrical energy. The system further includes a fluid path in connection with the generator through which pressurized gas passes after providing energy to the generator and a respiration facepiece in fluid connection with the fluid path.

Description:
FIELD OF THE INVENTION 
   The present invention relates generally to devices, systems and methods for generating electricity from gas stored in a container under pressure, and especially, to devices systems and methods for generating electricity from pressurized air delivered to a self-contained breathing apparatus. 
   BACKGROUND OF THE INVENTION 
   A generator and a motor are essentially the same device mechanically. The term applied to a particular device depends on whether (i) electricity is input into the device to cause rotation of an armature (a motor) or (ii) energy is produced by the device by spinning an armature by an input torque (a generator). Generators (both DC and AC) use magnets to transform mechanical energy into electrical energy via magnetic induction. Generators have a main magnetic field, which can be produced by a permanent magnet or by a coil called a field winding located in the stator or the rotor. Conductors make up the armature winding (coil) which is usually on the rotor. When the rotor rotates the conductors cut or pass through the field. The moving of the conductors through the magnetic field causes induction to take place and a voltage to be generated in the coil. Each end of this coil can, for example, be connected to a metal band called a slip ring. Small brushes made up of carbon on metal pick up the voltage off the rings and transport it to the generator&#39;s terminals. DC generators are sometimes referred to as dynamos. 
   Many different type of energy have been used to rotate the armature of a generator. For example, generators have been powered by manual power, wind power, water power, and steam power (from, for example, the burning of fossil fuels). Additionally, U.S. Pat. Nos. 4,678,922 and 5,801,454 disclose air tools (for example, buffers, sanders, grinders and polishers, which include an air motor) including a generator which produces electricity from the flow of the pressurized air. The generator is integrated with the air motor of the air tool. The air tools can be provided with a light that is powered by the integral generator. The air tools can also include batteries and battery charging circuitry to store excess energy. In such air or pneumatic tools, pressurized/compressed air is typically provided from a powered compressor to the air tool solely to provide power to the air tool. The air (at a lower pressure) is then vented to the atmosphere without further use. 
   In a number of uses of gases, the gas is pressurized for storage in a relatively small volume (for example, in a gas cylinder as known in the art). Such container-stored gases are often used for purposes other than for storing mechanical energy in the form of a pressurized gas. For example, in a self-contained breathing apparatus (SCBA), a cylinder of compressed air is in fluid connection with a mask worn by the user. The compressed gas cylinder provides a source of breathable air/oxygen to the user of the SCBA for respiration in a hazardous environment. Similarly a self-contained underwater breathing apparatus (SCUBA) provides a source of breathable air/oxygen to a user of the SCUBA while under water. 
   It is common for a user of SCBA or SCUBA (or a user of a compressed gas container for other than respiration) to also use electrically powered items. For example, a firefighter equipped with a SCBA might also be equipped with a light source, a Personal Alert Safety System (PASS), and/or a thermal imaging camera such as disclosed in U.S. Pat. No. 6,486,473. As it is impractical to connect such devices to a power outlet via electrical wiring, such devices are typically equipped with batteries. The use of batteries adds extra weight and bulk to such devices. In general, the greater the power required and/or the longer the battery must provide power, the larger the battery must be and the more weight and bulk that is added to an individual (who may be already heavily laden with protective clothing and firefighting tools in the case of a firefighter). 
   To reduce or eliminate that above and other problems, it is desirable to develop alternative energy sources to provide electrical power. 
   SUMMARY OF THE INVENTION 
   In one aspect, the present invention provides a breathing system, including a container to store a gas under pressure, wherein the gas includes oxygen. The container includes an outlet through which the gas exits the container. The breathing system further includes a generator system including a generator in operative connection with the container outlet such that energy is supplied to the generator by the pressurized gas. The generator converts the energy supplied by the pressurized gas to electrical energy. The system further includes a fluid path in connection with the generator through which pressurized gas passes after providing energy to the generator and a respiration facepiece in fluid connection with the fluid path. 
   The generator system can include a housing including an inlet in fluid connection with the cylinder outlet and an outlet in fluid connection with the fluid path. The generator system can further include a mechanism for rotating a shaft of the generator. The mechanism can, for example, be a turbine in fluid connection with the housing inlet. The mechanism can also be a vane in operative connection with the housing inlet. 
   The generator system can further include a feedthrough connector on the housing to transmit electricity from the generator to outside of the housing. Moreover, the generator system can further include an energy storage mechanism. The generator can also include a voltage regulating mechanism. In one embodiment, the generator system is positioned within the gas cylinder. 
   In a further aspect, the present invention provides a gas container for holding a pressurized gas. The gas container includes an outlet through which pressurized gas can exit the gas cylinder and a generator system within the gas cylinder. The generator system includes a generator in operative connection with the container outlet such that energy is supplied to the generator by the pressurized gas before it exits the container outlet. The generator converts the energy supplied by the pressurized gas to electrical energy. 
   In another aspect, the present invention provides a system, including a container to store a gas under pressure. The container includes an outlet through which the gas exits the container. The system further includes a generator system including a generator in operative connection with the container outlet such that energy is supplied to the generator by the pressurized gas. The generator converts the energy supplied by the pressurized gas to electrical energy. The system also includes a fluid path in connection with the generator through which pressurized gas passes after providing energy to the generator. 
   In still another aspect, the present invention provides a system, including a container to store the gas under pressure and a generator system in operative connection with the container. The generator system includes a generator positioned within a housing. The housing includes an inlet in fluid connection with the cylinder outlet and an electrical outlet. Energy is supplied to the generator by flow of the pressurized gas through the housing inlet. The generator converts at least a portion of the energy supplied by the pressurized gas to electrical energy. The system further includes a fluid path in connection with the housing outlet through which pressurized gas passes after providing energy to the generator. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  illustrates a cutaway perspective view of one embodiment of a generator system of the present invention. 
       FIG. 2  illustrates an exploded or disassembled perspective view of the generator system of  FIG. 1 . 
       FIG. 3  illustrates a perspective view of the generator system of  FIG. 1 . 
       FIG. 4  illustrates a perspective view of a respiration system/SCBA including the generator system of  FIG. 1 . 
       FIG. 5  is a schematic diagram of the respiration system of  FIG. 5 . 
       FIG. 6  illustrates an embodiment of circuitry for use in connection with the generator systems of the present invention including an energy storage system and a voltage regulator. 
       FIG. 7  illustrates a plot of the generator/dynamo voltage output of the generator system of  FIG. 1  as a function of turbine speed. This characteristic is measured at the open circuit condition at the generator terminals 
       FIG. 8  illustrates the power output of the generator/dynamo as a function of pressure drop across the turbine for with a 15-LED bank load. 
       FIG. 9  illustrates the voltage output curve as a function of pressure drop across the turbine for the voltage regulator circuitry of  FIG. 6 . 
       FIG. 10  illustrates the regulated output of the generator/dynamo as a function of pressure drop across the turbine with a 15-LED bank load. 
       FIG. 11  illustrates the results of a breathing study of the respiration system of  FIG. 5  in which facepiece pressure is plotted as a function of time. 
       FIG. 12  illustrates a cutaway perspective view of another embodiment of a generator system of the present invention. 
       FIG. 13  illustrates an exploded or disassembled view of the generator system of  FIG. 5 . 
       FIG. 14  illustrates another embodiment of a generator system of the present invention in which the generator system is formed inside a pressurized gas container. 
       FIG. 15  illustrates an embodiment of a generator system of the present invention incorporating a first stage regulator that can be used within a pressurized gas container as illustrated in  FIG. 14 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIGS. 1 through 4  illustrate an embodiment of a generator system  10  of the present invention which includes a housing having a generally cylindrical housing section  20 . The housing also includes a first end section  32  and a second end section  24 . An inlet port  30  is provided through which pressurized gas (for example, compressed air from a cylinder  210  illustrated in  FIG. 4 ) enters housing  20 . Inlet port  30  is in fluid connection with tubing  40  via a connector  42 . Tubing  40  is also in fluid connection with an air turbine or air motor  50  via a connector  44 . An example of a turbine suitable for use in the present invention is Model MMF 0700 available from Micro Motors, Inc. of Santa Ana, Calif. Air turbine  40  includes a shaft  52  which is caused to rotate by the pressurized gas flowing through air turbine  50 . The pressurized or compressed gas which causes rotation of shaft  52  exits turbine  50  into housing  20 , which is preferably sealed (other than inlet port  30  and an outlet port  90  discussed below) to prevent loss of air to the surrounding environment. 
   Turbine  50  is connected to generator  70  via a coupling  60 , which connects shaft  52  to shaft  72  of generator  70 . An example of a suitable generator for use in the present invention is the model RE 35 DC motor (rated at 90-watts) available from Maxon Precision Motors of Burlingame, Calif. In the embodiment of  FIGS. 1 through 4 , turbine  50  and generator  70  are in operative connection with, and held in position by, a hub or frame  80 . In one embodiment, coupling  60  was a flexible coupling to accommodate misalignment of shaft  52  with shaft  72 . 
   The fields of generator  70  depend upon the current from the armature of the generator for magnetization. Because the current developed by the generator increases in direct proportion to its speed, the fields become stronger as the speed increases and, correspondingly, the armature generates more current. A regulator can be provided to prevent excessive current or voltage overload. Such a regulator can either function to regulate voltage or to regulate current. In general, a voltage regulator regulates the voltage in the electrical system and prevents excessive voltage, which can cause damage to the electrical units of the system and/or overcharge a battery. A current regulator is a current limiter, which prevents the generator output from increasing beyond the rated output of the generator. In the embodiment of  FIGS. 1 through 5 , a voltage regulator (see  FIG. 5 ) was included to limit the voltage produced by generator  70  to approximately 7 volts. 
   Generator  70  includes terminals  74   a  and  74   b  through which electrical energy can be transmitted to electrical components or loads outside of housing  20 . Generator system  10  can, for example, include at least one feedthrough connector  100  (which is preferably in sealed connection with housing  20 ) to transmit electrical energy outside of housing  20 . An example of a feedthrough connector suitable for use in the present invention is the SO8-SS-150-2P-PC24-6-6 threaded feedthrough connector available from Pave Technology Co. of Dayton, Ohio. Feedthrough connector  100  includes two pairs of wires. One pair of wires can be used to transmit electricity through housing  20  from generator  70 , while, for example, the second pair can be connected to a pressure transducer (not shown) within housing to provide a reading of pressure within housing  20 . Additional or alternative sensors or other electrical components can be provided within housing  20  and signals communicated through one or more feedthrough connectors. 
   As illustrated in  FIG. 4 , generator system  10  is readily incorporated into a respiration system, SCBA or SCUBA. In that regard,  FIG. 4  illustrates an individual wearing a respiration system/SCBA  200  including compressed air cylinder  210 . The pressure of the air in the cylinder  210  can, for example, be in the range of approximately 2200 to 4500 psi. A control valve  220  is provided to open and close the outlet from cylinder  210 . Gauge  230  provides an indication of the pressure of the air within cylinder  210 . Cylinder  210  is in fluid connection with a first-stage regulator  240 . In the studies of the present invention, first-stage regulator  240  was used to drop the pressure of air entering inlet  30  (which is in fluid connection with first-stage regulator  240 ) of generator system  10  to approximately 80 psi. Outlet  90  of generator system  10  is in fluid connection with a second-stage regulator  260  which was used to drop the pressure of the air entering facepiece  300  to approximately 1.5 inches of water (approximately 0.054 psig). 
   As described above, a self contained breathing apparatus or SCBA is a device or system used to enable breathing in environments which are immediately dangerous to life and health. For example, firefighters wear an SCBA when fighting a fire. The second stage regulator of an SCBA system typically has an inlet valve which controls the flow of air through the regulator in response to the respiration of the user. Such respiration-controlled regulator assemblies are disclosed, for example, in U.S. Pat. Nos. 4,821,767 and 5,016,627, the disclosures of which are incorporated herein by reference. 
   Typically, a diaphragm divides the regulator assembly into an inner chamber having a pressure corresponding to the pressure within facepiece of the SCBA and an outer chamber having a pressure corresponding to the surrounding environment, which is typically ambient pressure. The diaphragm is coupled to an actuating mechanism which opens and closes the inlet valve. The user&#39;s respiration creates a pressure differential between the inner and outer chambers of the regulator assembly which, in turn, causes displacement of the diaphragm thereby controlling (that is, opening and closing) the inlet valve mechanism. As a result, such regulators are often called pressure demand regulators. 
   The facepiece of the SCBA is preferably maintained at a positive pressure as compared to the surrounding environmental pressure to prevent toxic gases and vapors in the environment from entering the facepiece. This positive pressure can, for example, be facilitated by biasing the diaphragm with a spring or other biasing element. 
   Because the inlet valve mechanism of the second-stage regulator is controlled by respiration of the user, there is no flow of air through the turbine during an exhalation cycle of the user. Energy storage circuitry as illustrated in  FIG. 6  provides a mechanism to continue to satisfy power requirements during an exhalation cycle, when turbine  50  and generator  70  are idle. Additionally, battery charging circuitry and batteries can be provided to enable long term storage of excess energy. 
   In  FIG. 4 , the user of respiration system/SCBA  200  is wearing a harness  400  that supports a compressed air container or cylinder  210  in a cylinder support  420 . Generator system  10  is also attached to harness  400  via a bracket  430 . Wires  110 , in electrical connection with feedthrough connector  100  of generator system  10  are connected to, for example, one or both of representative loads  510  (for example, a 15-LED bank) and  520  (for example, a DRAGONFLY® Personal Alert Safety System (PASS), available from Mine Safety Appliances Company of Pittsburgh Pa.). PASS devices are discussed, for example, in U.S. Pat. Nos. 6,198,396, 5,781,118 and 4,688,025, assigned to the assignee of the present invention, the disclosure of which are incorporated herein by reference. 
     FIG. 7  illustrates a plot of the voltage output of generator  70  (a Maxon RE 35 DC motor in the studies of the present invention) of  FIG. 1  as a function of the speed of turbine  50 . The current output of generator  70  as a function of pressure drop across the turbine with 15-LED bank load  510  in electrical connection with generator  70  is illustrated in  FIG. 8 .  FIG. 9  illustrates the voltage output curve as a function of pressure drop across the turbine for the voltage regulator circuitry of  FIG. 6 . Once again, the voltage was limited at approximately 7 volts.  FIG. 10  illustrates that a steady state average continuous power output of approximately 2 watts was obtained from generator  70  with 15-LED bank load  510  in electrical connection therewith. 
   It was shown that both 15-LED bank  510  and PASS device  520  could be powered by generator system  10  during respiration while complying with the National Institute for Occupational Safety and Health (NIOSH) breathing protocol using the FIREHAWK® MMR SCBA available from Mine Safety Appliances Company of Pittsburgh, Pa. In that regard,  FIG. 11  illustrates the results of a breathing study of the SCBA of  FIG. 5  in which facepiece pressure is plotted as a function of time. The minimum positive facepiece pressure was approximately 0.3 in of H 2 O, while the maximum positive facepiece pressure was approximately 2.4 in of H 2 O. 
   In addition to the above studies, generator system  10  was used to power an EVOLUTION® 5000 thermal imaging camera on bypass flow (that is, continuous flow of air from cylinder  210 ), delivering approximately 6 watts of power. Similarly, generator system  10  was also used to power a 6-cell MAGLITE® Flashlight on bypass flow, delivering approximately 6 watts of power. 
   As clear to one skilled in the art, the power output from generator  70  can be increased by spinning shaft  72  more quickly. The output from generator  70  can, for example, be increased by increasing the pressure drop across turbine  50 . To maximize pressure at inlet  30 , inlet  30  can be directly connected to cylinder  210  without an intervening regulator. Generator system  10  can itself act as a regulator in the fluid path of SCBA  200 . 
   Depending upon the size of the outlet orifice of turbine  50 , problems can arise in providing sufficient air to facepiece  300 , particularly at high respiration rates. The free internal volume of housing  20  can reduce this effect by acting as an air capacitor or accumulator. Moreover, a bypass valve can be provided so that air bypasses turbine  50  in cases of heavy air demand (for example, during rapid respiration). 
     FIGS. 12 and 13  illustrate an embodiment of a generator system  10 ′ of the present invention in which a shaft  52 ′ (see  FIG. 13 ) of a generator  70 ′ is caused to rotate by a propeller or vane  50 ′. In that regard, pressurized air enters housing  20  via inlet  30 ′ to cause rotation of vane  50 ′, which is in operative connection with shaft  72 ′. Air exits housing  20 ′ via outlet  90 ′ which is in fluid connection with a facepiece (not shown). A feedthrough connector  100 ′, similar in design and operation to feedthrough connector  100  is provided to transmit electricity produced by generator  70  outside of housing  20 ′. 
   The generator systems of the present invention have not been optimized for size, power output, air delivery etc. For example, decreasing the size of the generator system can be achieved by altering the positions of the turbine and the generator. The sizes, shapes and geometries of the components of the generator systems of the present invention can be readily altered. Moreover, a generator system  10 ″ of the present invention can be placed within a compressed gas cylinder  210 ″ as illustrated in  FIG. 14 . In this embodiment, inlet  30 ″ of generator system  10 ″ is in fluid connection with the internal volume of cylinder  210 ″, while outlet  90 ″ is in fluid connection with outlet  212 ″ of cylinder  210 ″.  FIG. 15  illustrates an embodiment of a generator system of the present invention incorporating a first stage regulator that can be used within a pressurized gas container as illustrated in  FIG. 14 . In the embodiment of  FIGS. 14 and 15 , air (or other gas) from the gas cylinder can enter the generator system inlet at 4500 psig and exit the generator system (for example, for respiration) at a pressure of 80 psig. In many other respects, the operation of the generator system of  FIG. 15  is similar to the operation of generator system  10  described above. 
   Although the generator systems of the present invention have been described in connection with use in an SCBA (or indeed the underwater equivalent, a SCUBA), one skilled in the art understands that the generator systems of the present invention can be used in connection with any type of compressed fluid which is to be delivered to another device or system. The generator systems of the present invention have little if any effect upon the nature of the fluid to be delivered and thus do not effect its final use, whether for consumption during respiration, consumption as a fuel etc. 
   The foregoing description and accompanying drawings set forth preferred embodiments of the invention at the present time. Various modifications, additions and alternative designs will, of course, become apparent to those skilled in the art in light of the foregoing teachings without departing from the scope of the invention. The scope of the invention is indicated by the following claims rather than by the foregoing description. All changes and variations that fall within the meaning and range of equivalency of the claims are to be embraced within their scope.