Abstract:
A packing method and system for measuring multiple measurands including bi-directional flow comprises of sampling ports arranged within a flow tube in a symmetrical pattern. The ports are arranged symmetrically with respect to the X and Y centerlines of the flow tube. In addition, the ports are also arranged symmetrical to the restrictor to minimize the amount of turbulent flow within the flow tube.

Description:
TECHNICAL FIELD 
       [0001]    Embodiments are generally related to methods and systems for manufacturing and packaging combinational flow sensors. Embodiments are also related to combinational flow sensors for measuring multiple measurands including bi-directional flow. 
       BACKGROUND OF THE INVENTION 
       [0002]    Flow rate control mechanisms are used in a variety of flow systems as a means for controlling the amount of fluid, gas or liquid, traveling through the system. In large-scale processing systems, for example, flow control may be used to affect chemical reactions by ensuring that proper feed stocks, such as catalysts and reacting agents, enter a processing unit at a desired rate of flow. Additionally, flow control mechanisms may be used to regulate flow rates in systems such as ventilators and respirators where, for example, it may be desirable to maintain a sufficient flow of breathable air or provide sufficient anesthetizing gas to a patient in preparation for surgery. 
         [0003]    Typically, flow rate control occurs through the use of control circuitry responsive to measurements obtained from carefully placed flow sensors. One such flow sensor is a thermal anemometer with a conductive wire extending radially across a flow channel and known as a hot-wire anemometer. These anemometers are connected to constant current sources, which cause the temperature of the wire to increase proportionally with an increase in current. In operation, as a fluid flows through the flow channel and, thus, past the anemometer, the wire cools due to convection effects. This cooling affects the resistance of the wire, which is measured and used to derive the flow rate of the fluid. Another form of thermal anemometer flow sensor is a microstructure sensor, either a micro bridge, micro-membrane, or micro-brick, disposed at a wall of a flow channel. In this form, the sensors ostensibly measure the flow rate by sampling the fluid along the wall of the flow channel. In either application, the thermal anemometer flow sensor can be disposed in the flow channel for measuring rate of flow. 
         [0004]    There are numerous drawbacks to these and other known flow sensors. The flow restriction mechanisms arranged inside a flow channel can create a pressure drop across the sampling ports that facilitate fluid flow into a sensing channel. This pressure drop, or pressure differential, is dependent on restrictor geometry and ingresses with flow rate. Furthermore, the fluid in the flow channel may possess an increasingly turbulent flow as the flow rate of fluid increases (i.e., an increasing non-uniform pressure and velocity across a given plane orthogonal to the direction of flow). 
         [0005]    When combining flow sensors with other sensing measurands, it is critical not to create turbulent flow, because such flow can in turn decrease the accuracy of the flow measurement. Therefore, to overcome the forgoing shortcomings, it is desirable to provide for a suitable packing method and/or system for measuring multiple measurands including bi-directional flow. 
       BRIEF SUMMARY 
       [0006]    The following summary is provided to facilitate an understanding of some of the innovative features unique to the embodiments disclosed and is not intended to be a full description. A full appreciation of the various aspects of the embodiments can be gained by taking the entire specification, claims, drawings, and abstract as a whole. 
         [0007]    It is, therefore, one aspect of the present invention to provide for an improved combinational flow sensor system and method. 
         [0008]    It is another aspect of the present invention to provide for a method for fabricating combinational flow sensors for measuring multiple measurands including bi-directional flow. 
         [0009]    The aforementioned aspects and other objectives and advantages can now be achieved as described herein. A method configuring for measuring multiple measurands including bi-directional flow is disclosed. In general, measurand sampling ports can be arranged within a flow tube in a symmetrical pattern. The ports are arranged symmetrically with respect to the X and Y centerlines of a flow tube. In addition, the ports are also arranged symmetrical to a flow restriction mechanism in order to minimize the amount of turbulent flow within the flow tube. In addition, the ports can be arranged symmetrical to the flow restriction mechanism (i.e., if used). The housing can be constructed such that it isolates and compartmentalizes the measurand sensing elements from one another on a circuit board. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The accompanying figures, in which like reference numerals refer to identical or functionally-similar elements throughout the separate views and which are incorporated in and form a part of the specification, further illustrate the embodiments and, together with the detailed description, serve to explain the embodiments disclosed herein. 
           [0011]      FIG. 1  illustrates a trimetric exploded view of a combinational sensor system, which can be implemented in accordance with a preferred embodiment; 
           [0012]      FIG. 2  illustrates a trimetric exploded view of a combinational sensor system depicting arrangement of a pressure sensor, an ASIC, a humidity sensor and an airflow sensor over a bypass flow tube, which can be implemented in accordance with a preferred embodiment; 
           [0013]      FIG. 3  illustrates a cross sectional view of a combinational sensor system showing the arrangement of a pressure sensor, an ASIC and a humidity sensor, which can be implemented in accordance with a preferred embodiment; 
           [0014]      FIG. 4  illustrates a cross sectional view of a combinational sensor system showing the arrangement of an airflow sensor, which can be implemented in accordance with a preferred embodiment; 
           [0015]      FIG. 5  illustrates a cross sectional view of a combinational sensor system showing the arrangement of a pressure sensor, an ASIC, a humidity sensor and an airflow sensor, which can be implemented in accordance with a preferred embodiment; 
           [0016]      FIG. 6  illustrates a high level flow diagram of operations depicting a method for fabricating a combinational sensor with a flow restriction mechanism, in accordance with a preferred embodiment; and 
           [0017]      FIG. 7  illustrates a high level flow diagram of operations depicting a method for fabricating a combinational sensor without a flow restriction mechanism, in accordance with a preferred without a flow restriction mechanism. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    The particular values and configurations discussed in these non-limiting examples can be varied and are cited merely to illustrate at least one embodiment and are not intended to limit the scope thereof. 
         [0019]      FIG. 1  illustrates a trimetric exploded view of a combinational sensor system  100 , which can be implemented in accordance with a preferred embodiment. A lid  102  can be disposed against the rear side of a circuit board  108 . The lid  102  protects the pressure sensor  106 , ASIC  112 , humidity sensor  110  and airflow sensor  114  from environmental effects and clamps the pressure sensor  106 , ASIC  112 , humidity sensor  110 , airflow sensor  114  and a flow tube  130  against a housing  118 . The pressure sensor cover  104  further protects the pressure sensor  106  from external effects. The pressure sensor  106  and humidity sensors  110  are arranged on pressure compartment  117  and humidity sensor compartment  116  respectively. The housing  118  is constructed such that it isolates and compartmentalizes the pressure sensor  106 , ASIC  112 , humidity sensor  110  and airflow sensor  114  from one another on a circuit board  108 . 
         [0020]    Clamping can be achieved utilizing an adhesive bond. Notches  122  can be provided on the lid  102  and may be disposed to snap in place over pegs  132  of the housing  118 . The lid  102  can be snapped into place over the pegs  132  and an adhesive bond may be utilize to connect the components. The lid  102  can be configured from resins similar to those utilized to configure the other sensor components. Additionally, the lid  102  also has an upper connection portion  140  which forms an electrical receptacle with a lower connection portion  129  of the housing  118  both of which houses a wire lead  124  when the lid  102  is snapped in place to form an electrical receptacle for connecting the lead  124  to external circuitry. 
         [0021]      FIG. 2  illustrates a trimetric exploded view of a combinational sensor system  100  depicting arrangement of a pressure sensor, an ASIC, a humidity sensor and an airflow sensor over a bypass flow tube, which can be implemented in accordance with a preferred embodiment. Note that in  FIGS. 1-2 , identical or similar parts or elements are generally indicated by identical reference numerals. For example, lid  102 , upper connection portion  140 , lower connection portion  129 , notches  122 , wire leads  124 , circuit board  108 , pressure sensor cover  104 , pressure sensor  106 , humidity sensor  110 , ASIC  112  and airflow sensor  114 , bypass flow tube  130 , housing  118 , pressure sensor compartment  117 , humidity sensor compartment  116  and legs  132  depicted in  FIG. 1  also appear in the system  100  configuration illustrated in  FIG. 2 . The pressure sensor  106 , humidity sensor  110 , ASIC  112  and airflow sensor  114  as depicted in  FIG. 1  are arranged on the bypass flow tube  130 . 
         [0022]      FIG. 3  illustrates a cross sectional view of a combinational sensor system  100  showing arrangement of a pressure sensor, an ASIC and a humidity sensor, which can be implemented in accordance with a preferred embodiment. Note that in  FIG. 1  and  FIG. 3 , identical or similar parts or elements are generally indicated by identical reference numerals. For example circuit board  108 , lid  102 , pressure sensor cover  104 , pressure sensor  106 , ASIC  112 , flow tube  130 , humidity sensor  110  and sensing channel  301  depicted in  FIG. 1  also appears in  FIG. 3 . 
         [0023]    The sampling ports  302  and  304  are arranged symmetrically with respect to the X and Y centerlines of a flow tube  130 . In addition, the ports  302  and  304  are also arranged symmetrical to a flow restriction mechanism  306  in order to minimize the amount of turbulent flow within the flow tube  130 . The cross sectional view shows the arrangement of pressure sensor  106 , ASIC  112  and humidity sensor  110  as depicted in  FIG.1  in the sensing channel  301  and also shows the arrangement of the flow restriction mechanism  306  in the flow channel  305 . Note that the flow restriction mechanism can be, for example a device such as a flow restrictor or another device such as a venturi or pitot tube for use in tapping into and sensing flow, as indicated herein. Thus, the flow restriction mechanism described herein is not limited to the configuration of a flow restrictor, but may be implemented as venture or pitot tube or other type of device, depending upon design considerations. 
         [0024]      FIG. 4  illustrates a cross sectional view of a combinational sensor system  100  showing the arrangement of an airflow sensor, which can be implemented in accordance with a preferred embodiment Note that in  FIGS. 1-4 , identical or similar parts or elements are generally indicated by identical reference numerals. For example, circuit board  108 , lid  102 , airflow sensor  114 , flow channel  305 , sensing channel  301  and flow restriction mechanism  306  depicted in  FIGS. 1-3  also appear in  FIG. 4 . 
         [0025]      FIG. 5  illustrates a cross sectional view of a combinational sensor system  100  showing the arrangement of a pressure sensor, an ASIC, a humidity sensor and an airflow sensor, which can be implemented in accordance with a preferred embodiment. Note that in  FIG. 1  and  FIG. 5 , identical or similar parts or elements are generally indicated by identical reference numerals. For example, the housing  118 , notches  122 , pressure sensor  106 , ASIC  112 , pegs  132 , pressure sensor cover  104 , circuit board  108  and airflow sensor  114  depicted in  FIG. 1  also appears in  FIG. 5 . 
         [0026]      FIG. 6  illustrates a high level flow diagram  600  of operations depicting a method for packaging a combinational sensor system  100  with flow restriction mechanism  306  depicted in  FIG. 3 , in accordance with a preferred embodiment. As indicated at block  610 , the pressure sensor  106 , humidity sensor  110 , ASIC  112  and airflow sensor  114  depicted in  FIG. 1  are arranged apart from one another on a circuit board  108  depicted in  FIG. 1 . The housing  118  depicted in  FIG. 1  can be constructed such that it isolates and compartmentalizes the pressure sensor  106 , humidity sensor  110 , ASIC  112  and airflow sensor  114  depicted in  FIG. 1  from one another on the circuit board  108  depicted in  FIG. 1 . 
         [0027]    At block  620  the flow restriction mechanism  306  is disposed in the flow channel  305  as depicted in  FIG. 3  for creating a pressure drop in flow channel  305 . The combinational sensor system  100  depicted in  FIG. 1  having the pressure sensor  106 , humidity sensor  110 , ASIC  112  and airflow sensor  114  can be disposed in the sensing channel  301  depicted in  FIG. 3  as illustrated at block  630 . As depicted at block  640  the sampling ports  302  and  304  depicted in  FIG. 3  are arranged symmetrically with respect to X and Y central lines of flow tube  130  depicted in  FIG. 1 . In addition at block  650  the ports  302  and  304  depicted in  FIG. 3  are also arranged symmetrical to flow restriction mechanism  306  depicted in  FIG. 3 . Finally, as described at block  660 , the housing  118  depicted in  FIG. 1  can be fastened to the pressure sensor  106 , humidity sensor  110 , ASIC  112  and airflow sensor  114  as depicted in  FIG.1 , and flow channel  305  and the sensing channel  301  as depicted in  FIG. 3 . 
         [0028]      FIG. 7  illustrates a high level flow diagram  700  of operations depicting a method for packaging a combinational sensor system  100  without a flow restriction mechanism  306  as depicted in  FIG. 3 , in accordance with an alternative embodiment. As depicted at block  710 , the pressure sensor  106 , humidity sensor  110 , ASIC  112  and airflow sensor  114  depicted in  FIG. 1  are arranged apart from one another on a circuit board  108  depicted in  FIG. 1 . The housing  118  depicted in  FIG. 1  can be constructed such that it isolates and compartmentalizes the pressure sensor  106 , humidity sensor  110 , ASIC  112  and airflow sensor  114  depicted in  FIG. 1  from one another on the circuit board  108  depicted in  FIG. 1 . The flow sensor module  100  depicted in  FIG. 1  contains the pressure sensor  106 , humidity sensor  110 , ASIC  112  and airflow sensor  114  depicted in  FIG. 1 , and are disposed in the sensing channel  301  depicted in  FIG. 3  as indicated at block  720 . As depicted at block  730 , the sampling ports  302  and  304  depicted in  FIG. 3  can be arranged symmetrically with respect to X and Y central lines of the flow tube  130  depicted in  FIG. 1 . Finally, as described at block  740 , the housing  118  depicted in  FIG. 1  can be fastened respectively to the flow channel  305  depicted in  FIG. 2 , the pressure sensor  106 , humidity sensor  110 , ASIC  112  and airflow sensor  114  depicted in  FIG. 1  and the sensing channel  301  as depicted in  FIG. 3 . 
         [0029]    It will be appreciated that variations of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Also that various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.