Abstract:
A personal air sampling pump assembly includes a motor having a reciprocating piston for operating a diaphragm assembly. The diaphragm includes a valve head including a fluid inlet and a fluid outlet and a fluid chamber defining a fluid path between the inlet and outlet. A first and second diaphragm sealing engaging the valve head and enclosing the fluid chamber. The first diaphragm includes a piston diaphragm membrane portion coupled to the piston for reciprocating with the piston and wherein reciprocation of the piston causes a change in air pressure within the fluid chamber to cause air to move from the fluid inlet toward the fluid outlet. Both the first and second diaphragms include a damper membrane portion, which cooperate to reduce an amplitude of pulsation in the airflow at the fluid inlet and fluid outlet.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a non-provisional application claiming priority from U.S. Provisional Application Ser. No. 62/153,167, filed Apr. 27, 2015, and incorporated herein by reference in its entirety. 
     
    
     FIELD OF THE DISCLOSURE 
       [0002]    The present description relates generally to a diaphragm air pump and more particularly to a personal air sampling pump assembly. 
       BACKGROUND OF RELATED ART 
       [0003]    Personal air sampling pumps and controls are generally known. For instance, U.S. Pat. No. 3,814,552 describes a personal air sampling pump including a solenoid driven rubber diaphragm and rubber flapper check valves to control inlet and outlet flow. The diaphragm has a flexible annulus and a rigid central section and is used with independently timed drive pulses for essentially constant flow with varying load. 
         [0004]    Similarly, U.S. Pat. No. 4,063,824 describes a constant flow air sampling pump including a variable drive pump that is connected to a filter and that is driven by an electric motor and is controlled by a feedback circuit of an integrator and an amplifier to maintain a constant flow of air through a dosimeter. The dosimeter is worn by an individual and at the termination of a period of time, such as a work day, the filter is removed and the collected contents are analyzed by conventional techniques such as gas chromatography to determine a level of exposure of the individual using the dosimeter. 
         [0005]    Still further, U.S. Pat. No. 4,091,674 describes an electronically timed, positive displacement air sampling pump for use with air sample collecting devices in various environmental conditions. The device provides for average flow rate, independently metered total volume, operating time register and an audible “rate fault” alarm. 
         [0006]    U.S. Pat. No. 5,107,713, describes a microprocessor controlled air sampling pump that utilizes a PWM controlled DC electric motor for regulating air flow generated by a diaphragm-type air pump. The control system regulates air flow as a function of the RPM of the motor by establishing a table of values which relate motor RPM to air flow rates. The control system maintains RPM at the desired value but includes a control loop which senses deviations in RPM and adjusts the PWM signals to the motor to regulate RPM. 
         [0007]    While the identified devices may generally work for their noted purposes, there is an identifiable need for an improved personal air sampler as disclosed herein. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a front perspective view of one example of a personal air sampling pump assembly in accordance with the present disclosure. 
           [0009]      FIG. 2  is a side elevational view of the example personal air sampling pump assembly of  FIG. 1 . 
           [0010]      FIG. 3  is a cross sectional view of the example personal air sampling pump assembly of  FIG. 1  taken along line  3 - 3 . 
           [0011]      FIG. 4  is a side elevational view of the example personal air sampling pump assembly of  FIG. 1  with a portion of the housing removed. 
           [0012]      FIG. 5  is a perspective view of the example personal air sampling pump assembly of  FIG. 1  with additional components removed to show additional details of the motor and piston assembly. 
           [0013]      FIG. 6  is a side elevational view of the example personal air sampling pump assembly of  FIG. 1  showing the motor and pistons coupled to the first elastomeric diaphragms. 
           [0014]      FIG. 7A  is a perspective view of a valve chest with an inlet pulsation damper for use with the example personal air sampling pump assembly of  FIG. 1 . 
           [0015]      FIG. 7B  is a reverse perspective the valve chest with an inlet pulsation damper of  FIG. 7A . 
           [0016]      FIG. 8A  is a perspective view of a two example valve head and pulsation damper assemblies for use with the example personal air sampling pump assembly of  FIG. 1 . 
           [0017]      FIG. 8B  is a reverse perspective view of the two valve head and pulsation damper assemblies of  FIG. 8A . 
           [0018]      FIG. 9  is a perspective view of an example motor housing for use with the example personal air sampling pump assembly of  FIG. 1 . 
           [0019]      FIG. 10  is a perspective view of the motor housing of  FIG. 9  coupled to the valve head and pulsation damper assemblies of  FIGS. 8A and 8B . 
           [0020]      FIG. 11  is a transparent perspective view of the example personal air sampling pump assembly of  FIG. 1  showing an example fluid flow path. 
           [0021]      FIG. 12  is an alternative perspective view of  FIG. 11  additionally showing the example fluid flow path. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    The following description of example methods and apparatus is not intended to limit the scope of the description to the precise form or forms detailed herein. Instead the following description is intended to be illustrative so that others may follow its teachings. 
         [0023]    The present disclosure is generally directed toward a rotary diaphragm air pump that integrates the function of piston head diaphragms, airflow flow pulsation dampers and sealing gaskets within a single compact housing assembly. In general, the layered design arrangement disclosed may reduce manufacturing cost, the number of component parts used to effect operation, and/or the overall product size. The present design may reduce assembly time and may create a ‘fail-safe’ assembly procedure that typically does not require the use of adhesives or sealants. As a result of the integrated design, a relatively optimal flow performance can be achieved with minimal flow pulsations. 
         [0024]    In the personal air sampling pump application where particulate material may be collected onto a filter medium, low pulsation of the inlet airflow is oftentimes desired to prevent vibration of the collection filter and subsequent loss of the deposited material. A smooth airflow is also highly desired to ensure the correct performance of size-selective inlet devices such as cyclones. Furthermore, in at least some examples, the pulsation performance of the presently disclosed personal air sampling pump complies with the requirements of international Air Sampling Pump Standards such as ISO13137. 
         [0025]    Referring now to  FIGS. 1-10 , an example of a personal air sampling pump assembly  10  is illustrated. It will be understood that in the present disclose, the terms fluid, air, gas, etc. may be equivalently utilized, and the operating principles of the present disclosure should not be limited to any specific gas, fluid, or mixture unless specifically stated otherwise. The example pump assembly  10  generally defines a housing comprising a motor housing  11 , a first valve head and pulsation damper assembly  12  and a second valve head and pulsation damper assembly  14 . In this example, the pump assembly  10  further includes an outlet assembly  16  fluidly coupled to the first valve head and pulsation damper assembly  12  via an outlet  17 . The outlet assembly  16  may include a device or other suitable structure that for the purpose of outlet flow rate sensing. It will be understood that the outlet assembly may include and/or may be coupled to any suitable device to provide “further processing” on the outlet fluid including, for example, monitoring for toxins, radiation, etc. In operation, a motor  18  is used to drive an oscillatory linear motion of an articulated pump piston assembly  20  mounted within the motor housing  11 . In this example, the articulated pump piston assembly  20  includes a dual piston setup  20   a ,  20   b , with each of the pistons  20   a ,  20   b  coupled to drive an associated piston diaphragm. In particular, in this example, the oscillating motion of the piston and the piston diaphragm is used to pump air through a valve the valve head and pulsation damper assemblies  12 ,  14  as best viewed in  FIGS. 4, 7A, 7B . 
         [0026]    In one example, operation of the motor  18  may be controlled by a closed loop flow control system as disclosed in copending U.S. application Ser. No. 14/688,370, entitled “Air Sampler With Closed Loop Flow Control System,” filed Apr. 16, 2015, and incorporated herein by reference in its entirety. 
         [0027]    Referring to  FIG. 3 , in this example, the valve head and pulsation damper assembly  14  forms a second air chamber, while the valve head and pulsation damper assembly  12  forms a first air chamber. Together, the pistons  20   a ,  20   b , and the assemblies  12 ,  14 , respectively form a piston diaphragm assembly. Each of the valve head and pulsation damper assemblies  14 ,  12  generally includes a housing or head, including for instance, a first valve head  112  and a second valve head  112 . Each of the first head  112  and second head  114  includes a first elastomeric element  24 ,  26  that is coupled to one of the pistons  20   a ,  20   b , and that seals one side of the associated head  112 ,  114 . A second set of elastomeric elements  30 ,  32  are located on an opposite side of each of the valve heads  112 ,  114  to seal the second side of the valve head. Each of the valve heads  112 ,  114 , may additionally be sealed via a cover plate  40 ,  42  securely fastened to the associated head  112 ,  114  via any suitable method, including via a plurality of fasteners, such as threaded fasteners  120 . It will be appreciated that  FIGS. 7A and 7B  illustrate one example of the valve head and pulsation damper  12 . The example assembly  12  includes the valve head  112 , with elastomeric elements  26 ,  30  sealing coupled to either side of the valve head  112 . The valve head  112  includes an inlet  19  in addition to the outlet  17 . As will be described in detail herein, the valve head  112  and the elastomeric element  26  includes a plurality of apertures  140 ,  142  to allow fluid communication between the valve heads  112 ,  114  through a first conduit  160  and a second conduit  162  formed in the motor housing  11 . 
         [0028]    Referring to  FIGS. 8A, 8B , and  FIGS. 3 and 4 , each of the valve heads  114 ,  112 , defines various air chambers  112   a ,  112   b ,  112   c , and  114   a ,  114   b ,  114   c , respectively. In the illustrated example, the various air chambers  112   a ,  112   b ,  112   c , and  114   a ,  114   b ,  114   c  are fluidly coupled via a plurality of apertures  150 . Each of the apertures  150  may include a check valve  152 , which are each hidden in  FIGS. 8A, 8B , but are visible in  FIGS. 3 and 4 . As is known in the art, the check valves  152  may be utilized to provide for a single airflow direction and to prevent air from flowing in a non-desired direction. 
         [0029]    Accordingly, in this example construction, the inlet  19  is fluidly coupled to the air chamber  112   a  and also to the conduit  160 . The air chamber  112   a  is fluidly coupled to the air chamber  112   b  through a first set of apertures  150   a  and one of the check valves  152 . The air chamber  112   b  is subsequently fluidly coupled to the air chamber  112   c  though a second set of apertures  150   b  and another one of the check valves  152 . The conduit  162  is similarly fluidly coupled to the air chamber  112   c . Finally, the air chamber  112   c  is fluidly coupled to the outlet  17 . 
         [0030]    Referring to the valve head  114 , the air chamber  114   c  is fluidly coupled to the conduit  160  to receive air from the valve head  112 . An outlet  117  is provided in the valve head  114  and in this instance may be coupled to a pressure sensor (not shown) to monitor the pressure of the device  10 . It will be appreciated that the outlet  117  may be coupled to any device, conduit, sensor, or other suitable device as desired. The air chamber  114   c  is coupled to the air chamber  114   b  through a third set of apertures  150   c  including another one of the check valves  152 . Next, the air chamber  114   b  is coupled to the air chamber  114   a  and the conduit  162  through a fourth set of apertures  10   d  including a further one of the check valves  152 . As noted above, the conduit  162  is fluidly coupled to the air chamber  112   c  through the motor housing  11 . 
         [0031]    As will be appreciated, each of the elastomeric membranes  24 ,  26 ,  28 ,  30  serves to perform multiple functions and, in this example as illustrated in  FIG. 4 , generally includes a piston diaphragm portion  24   a ,  26   a , and a pulsation damper membrane portion  24   b ,  26   b , respectively. In particular, for each assembly  14 ,  12 , the layered construction includes multiple elastomeric diaphragms separated by a valve head as described above. Each of the first elastomeric elements is generally considered an elastomeric piston diaphragm molding. As shown in  FIG. 7A , the example elastomeric element  26  provides a sealing gasket between the motor housing  11  (removed in  FIG. 7A ) and the valve head  112 , and includes a pump diaphragm membrane  170  which is coupled to one of the pistons  20 , and a flexible damper membrane  172 . Meanwhile, as illustrated in  FIG. 7B , the example elastomeric element  30  similarly provides a sealing gasket between the cover plate  40  (removed in  FIG. 7B ) and the valve head  112 , and includes a flexible damper membrane  180 . 
         [0032]    Although not illustrated in  FIGS. 7A and 7B , the construction of the valve head and pulsation damper assembly  14  may be similar to the construction described in relation to the illustrated valve head and pulsation damper assembly  12 , or may be any suitable design. Furthermore, the layered construction of the present disclosure may be applicable to a single acting (i.e., a single piston diaphragm assembly) or a double action pump design as disclosed herein. 
         [0033]    As illustrated, the elastomeric elements  26 ,  30  may include a plurality of raised line features such as the raised line future  182 , on the surface of the respective elements  11 ,  112 ,  114 ,  40 , and  42  to locally increase the compressive force applied to the membrane and to aid in sealing the entire assembly. 
         [0034]    The pulsation damper membrane portions  24   b ,  26   b  are generally formed from the combination of the flexible elastomeric damper membranes  26 ,  30  and the enclosed air chamber  112   c  formed within the valve head  112 . The combination of the elastic structure and the associated cavity volume reduces the amplitude of pulsations in the pump&#39;s inlet and outlet airflow. In addition, as shown in  FIG. 4 , the damper membrane portions  24   b ,  26   b , may optionally include a spring  190 , such as a coil spring, or other suitable mechanism to alter the spring characteristics of the membranes  26 ,  30  and the damper response. Further, the flow pulsation dampener portion  24   b ,  26   b  generally reduces the level of pulsations induced by the actions of the diaphragm. In a typical personal sampling pump, the magnitude of pulsations in the air flow velocity leads to changes in the performance characteristics of size selective sampling heads such as cyclones. 
         [0035]    As will be appreciated by one of ordinary skill in the art, the action of the reciprocating piston  20  against the piston diaphragm portion  24   a ,  26   a  may be used to create a positive or negative air pressure pumping effect as desired. The piston diaphragm portion  24   a ,  26   a  are used to move a volume of gas or air, and the elastomeric membranes  24 ,  26 ,  28 ,  30  are stretched across the valve heads  112 ,  114  and not physically bonded thereto. In operation, the motor  20  including eccentric connecting rods create oscillatory pumping motion in the elastomeric membranes  24 ,  26 . 
         [0036]    The movement caused by the piston diaphragm assemblies is used to move a volume of fluid, gas, or air as illustrated in  FIGS. 11 and 12 . In general, air enters into the assembly  10  at the inlet  19  and flows one of two fluid paths  200 ,  202  as shown. In the first path  200 , the air enters the inlet  19  and travels through the three air chambers  112   a ,  112   b ,  112   c , under influence of air pressure caused by the operation of the piston diaphragms portions  24   a ,  26   a , and exits the assembly  10  at the outlet  17 , where it may travel through the outlet assembly  16  for flow sensing and/or other suitable processing, or through any other suitable device. At the same time, at least a portion of the air entering at the inlet  19  may travel via the second air path  202  into the conduit  160  and into the air chambers  114   a ,  114   b ,  114   c . As noted above, a portion of the air may be bled through the outlet  117  for any suitable purpose, including for instance, for pressure sensing. The air may then return to the valve head  112  and specifically the air chamber  112   c  through the conduit  162 , where the air may similarly exit through the outlet  17 . 
         [0037]    Although certain example methods and apparatus have been described herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all methods, apparatus, and articles of manufacture fairly falling within the scope of the appended claims either literally or under the doctrine of equivalents.