Abstract:
A valve comprises an inlet portion configured to couple to a source of a fluid, and a body portion in fluidic communication with the inlet portion. The body portion defines a modulated flow path and a constant flow path adjacent to the modulated flow path.

Description:
BACKGROUND 
   The present invention relates to a valve. More particularly, the present invention relates to a fluidic or air valve defining at least a first flow path with a modulating device such as a disk or flapper and a second, unmodulated flow path. 
   One method of suppressing fire and explosions in an aircraft fuel tank is to provide a non-explosive atmosphere within the fuel tank by replacing potentially combustible air in a fuel tank ullage (i.e., the space within the fuel tank unoccupied by fuel) with an inerting gas, such as nitrogen-enriched air (NEA). An onboard inerting system is often used to supply NEA (or another inerting gas) into the tank ullage when the demand arises (e.g., in order to increase the pressure inside the ullage in response to changing atmospheric conditions or to otherwise maintain the oxygen content in the ullage at or below a desirable level). The inerting system can typically include a nitrogen generating system (NGS) that separates nitrogen from high pressure air generated by a single compressor, or series of compressors within the system. Ram air (i.e., air from outside the aircraft), independent of the high pressure air circuit, is the heat sink source to cool the hot compressed air generated by the compressors. Both ram air and compressor air flows thru a heat exchanger to exchange heat. 
   In one type of NGS, ram air is fed to the NGS through a single inlet duct. A component&#39;s modulating valve controls flow of ram air to the NGS, such as a plurality of heat exchangers. The NGS output level typically depends on the amount of inert air required to fill the fuel tank ullage to maintain an inert environment. The modulating valve helps to achieve various NGS nitrogen gas output levels by controlling the amount of ram air that is directed to the heat exchangers to cool the heat of compressed air from the compressors. The amount of heat transfer is dependent upon flow thru the compressors to accommodate the NGS desired output. 
   It has been found that in at least one particular NGS, a dedicated constant flow of ram air is desirable for multiple purposes, such as cooling a compressor motor and/or because at least one of the plurality of heat exchangers requires a constant flow of air. Given the space constraints in many aircraft, it may be undesirable to modify the NGS system to include more than one inlet duct to provide for modulating and constant ram flows to the heat exchanger. As a result, both the constant flow and modulated flow of ram air must be provided through a single inlet duct leading to the valve. There is a need for a valve design that provides multiple out flows, including at least one constant out flow, without requiring substantial modification of current NGS inlet duct dimensions. 
   BRIEF SUMMARY 
   The present invention is a valve defining at least two adjacent flow paths, where the fluid flow rate through one flow path is modulated and the fluid flow rate through the other flow path is constant. The two flow paths share one inlet duct. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
       FIG. 1  is a perspective view of a nitrogen generating system, which includes an air inlet valve in accordance with the present invention. 
       FIG. 2  is a perspective view of the inlet valve and heat exchanger of the system of  FIG. 1 . 
       FIG. 3  is a perspective view of the air inlet valve of  FIG. 1  and with the valve modulating disk in an open position. 
       FIG. 4  shows an embodiment with a curved separator. 
   

   DETAILED DESCRIPTION 
   The present invention is a valve defining at least a first modulated or variable flow path and a second, unmodulated or bypass flow path. While the inventive valve is described below in reference to a nitrogen generating system (NGS) for an aircraft, it should be understood that a valve in accordance with the present invention is suitable for any application in which it is desirable to implement a valve with at least two flow paths that share a common inlet portion. 
     FIG. 1  shows nitrogen generating system (NGS)  10 , which includes inlet air valve  12 , heat exchanger  14 , motor  16 , first compressor  18 , and second compressor  20 . Valve  12  is mounted to the inlet header of heat exchanger  14 , and includes valve body  30 , baffle  32 , modulating valve disk  34 , actuator  36 , and shaft  38 . Valve  12  provides dual flow paths for ram air into heat exchanger  14 . Bypass path B is shown to the right of baffle or separator  32 , while variable path V (shown to the left of separator  32 ) has a variable opening controlled by modulating valve disk  34 . The position of disk  34 , and therefore the flow through variable path V, is controlled by actuator  36 , which rotates shaft  38 , on which disk  34  is mounted. 
   As shown in  FIG. 1 , heat exchanger  14  includes intercooler  40  and main heat exchanger  42 . Intercooler  40  is divided into two sections: intercooler section  40   a , which is dedicated to cooling motor  16 ; and intercooler section  40   b , which cools air from first compressor  18 . Separator  32  is a vertical wall that extends into heat exchanger  14  to separate incoming ram air to intercooler  40 . Separator  32  defines a constant flow opening for ram air to flow through section  40   a  of intercooler  40 . The opposite side of separator  32  provides for ram air flow to enter intercooler section  40   b  through the variable opening of valve  12  controlled by disk  34 . The variable flow of ram air also is delivered to main heat exchanger  42 , and is used to cool air from second compressor  20 . Heat exchanger  14  includes compressor air inlets  44  and  46 , air outlet  48 , air outlet  50 , heat exchanger outlet  52 , ram air outlet  54  (shown in  FIG. 2 ), and mount  56 . 
   Motor  16  drives first compressor  18  and second compressor  20 . Motor  16  includes air inlet  60  for receiving cooling air from outlet  48  of heat exchanger  14 . 
   First compressor  18  includes inlet  62  and outlet  64 . Air from outlet  64  of first compressor  18  is delivered to inlet  44  of heat exchanger  14 . 
   Second compressor  20  includes inlet  66  and outlet  68 . As shown in  FIG. 1 , second compressor inlet  66  receives air from outlet  50  of heat exchanger  14 . Air from second compressor outlet  68  is delivered to inlet  46  of heat exchanger  14 . 
   In operation, air is drawn through inlet  62  into first compressor  18 . Air flows out of outlet  64  of compressor  18  to inlet  44  of heat exchanger  14 . The first compressor air flows through intercooler section  40   a  to outlet  48 , where it is delivered to air inlet  60  of motor  16 . The air passing through intercooler section  40   a  is cooled by ram air which has flowed through the open bypass section of valve  12 . 
   A portion of the air delivered from first compressor  18  to inlet  44  flows through intercooler section  40   b  to outlet  50 , and then is supplied to inlet  66  of second compressor  20 . The air flowing through intercooler  40   b  from first compressor  18  is cooled by a variable flow of ram air that is modulated by disc  34 . 
   Output air from second compressor  20  is delivered through outlet  68  to inlet  46 . The second compressor air flows through main heat exchanger  42  to heat exchanger outlet  52 . 
     FIG. 2  shows valve  12  and heat exchanger  14  separate from the other components of NGS  10 . Valve  12  provides two separate passageways for ram air: unmodulated or bypass passage B and modulated or variable passage V. Bypass passage B allows a portion of ram air received at the inlet end of valve  12  to pass directly to intercooler  40   a.    
   Variable flow passage V controls the flow of air to intercooler  40   b  and main heat exchanger  42 . The amount of air flowing through passage V is controlled by the position of disc  34 . Actuator  36  rotates shaft  38  to position disc  34  in passage V. Disc  34 , in combination with actuator  36  and shaft  38 , operates as a butterfly valve assembly, which rotates around centerline CL of shaft  38 . In  FIG. 2 , disc  34  is shown in a closed position, thereby blocking airflow through passage V. In  FIG. 3 , disc  34  is shown in an open position, so that a portion of the ram air delivered to valve  12  can pass through passage V to intercooler section  40   b  and main heat exchanger  42 . 
   Valve  12  provides multiple flow paths that share a single inlet. Bypass passage B provides a constant airflow, while variable passage V provides a variable airflow, depending upon the position of valve disc  34 . Although both passage B and V are shown as having a D-shaped opening, other shapes can also be used. For example,  FIG. 4  shows an embodiment in which separator  32  is curved and bypass passage B is crescent shaped. Similarly, although the butterfly-type valve is shown in variable passage V, other types of flow modulating valves may be positioned within passage V. Examples include a ball valve, a gate valve, a spool valve, and a flapper valve. 
   Although inlet valve  12  is described as being used to introduce ram air into NGS  10 , it should be understood that an inlet valve in accordance with the principles of the present invention may be used in conjunction with other fluids, such as liquids, as well as other assemblies. Furthermore, the inlet valve may be formed of any suitable material, such as, but not limited to, metals, polyvinyl chloride, and other plastic materials. 
   The terminology used herein is for the purpose of description, not limitation. Specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as bases for teaching one skilled in the art to variously employ the present invention. Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.