Abstract:
An aromatherapy air pump is damped and largely isolated against acoustic and mechanical transmission of vibrations in three dimensions by a combination of containment within multiple, nested housings and standoffs provided by elastomeric supports having anisotropic geometry. An elastomeric liner as well as unstable legs, physical separations, and hermetic seals combine to provide sound reduction for noise and vibration emanating from the pump and its drive motor.

Description:
BACKGROUND 
     1. The Field of the Invention 
     This invention relates to air pumps and, more particularly to novel systems and methods for reducing sound and vibration from air pumps used in aroma therapy. 
     2. The Background Art 
     Various mechanisms for treating an environment with moisture, medicaments, and the like have been developed using boilers, heaters, fans, and so forth. Aroma therapy involves evaporation, distribution, or other entrainment of volatiles, essential oils, or the like into breathing air, an atmosphere of a room, or other enclosed space. Applicant has previously developed various mechanisms for distributing atomized liquids into the atmosphere. Likewise, various systems for heating or dissolving aromatic or oil-based materials in a solvent to promote evaporation into the atmosphere have also been relied upon in the art. Meanwhile, various medical devices provide humidification of a space such as a “steam tent” or the like. 
     However, in aroma therapy, it would be an advance in the art to accommodate space, aesthetics, weight, stability, simplicity of use, ease of use, storage, and the like. Accordingly, it would be an advance in the art to provide an integrated system having suitable weight for stability, a sufficiently small size so excessive footprint and volume are not occupied on a dresser, table, or a night stand, and otherwise rendering a system easily located on furniture within a room. Likewise, it would be an advance in the art to provide an aesthetically pleasing shape integrating all of the functions required for driving an atomizer of, perfume, essential oils, or other material desired to be distributed within an ambient environment. 
     It would be an advance in the art to provide an air pump for use in aroma therapy that is virtually silent. Reducing sound by several decibels is very difficult because of the fundamental nature of a vibrating motor driving a diaphragm pump. Accordingly, it would be a substantial advance in the art to create a mechanism for damping, isolating, or both, the mechanical vibration and acoustic vibration within air through a mechanical and fluid systems in order to provide a virtually silent pump. It would also be an advance in the art to provide a pump having long life, inexpensive components, easily replaceable parts, few moving parts, few wearing parts, economical maintenance, and simple assembly and operation. 
     BRIEF SUMMARY OF THE INVENTION 
     In view of the foregoing, in accordance with the invention as embodied and broadly described herein, a method and apparatus are disclosed in one embodiment of the present invention as including a system having a housing for a pump driven by an oscillating motor to draw liquids from a reservoir and distribute them through an eductor into the atmosphere. 
     The method may include adjusting an electronic controller to control at least one of a duration of operation and a duration of a delay between periods of operation of the pump. Operating the pump pressurizes ambient air into a flow that may be through other equipment such as an aquarium or an atomizer. 
     In some embodiments, the duty cycle may be controlled by controlling the ratio of the duration of operation to the duration of the delay plus the duration of operation. A method may provide a housing, a motor being disposed inside the housing and electrically powered to drive the pump. 
     In some embodiments, the pump comprises a pump body fitted with a valve plate captured in a pinch slot to support pressure between the pump body and valve plate. Seals positioned about openings passing the flow into and out of the pump may minimize pressure exposure of the structure of the pump. This is an improvement over conventional gaskets by being sized to fit within from about one to about three diameters, typically about two diameters, of the aperture corresponding to each seal. 
     The method may include the pump disposed within the housing, driven by a motor, and comprising a diaphragm compressing air and providing a flow thereof at a pressure greater than ambient pressure. The motor may have a coil and a magnet operably connected to reciprocate an armature magnet back and forth to move the diaphragm. 
     A control system operably connected to the coil may control electricity flowing to the coil, including voltage, current, off and on conditions, and so forth. The control system may include an actuator adjustable by a user to selectively and arbitrarily control the duration of delivery of electrical energy to the coil. A user may selectively and arbitrarily control a delay between adjacent periods of continuous delivery of electrical energy to the coil. A user may also arbitrarily control the duration of delivery of electrical energy to the coil and a delay between adjacent periods of continuous delivery of electrical energy to the coil. 
     A control system may provide infinitely variable adjustment between extremes (max and min values), to be set by a user arbitrarily selecting duration of operation, duration of deactivation between periods of operation of the motor, or both. 
     In some embodiments, a user may select a first time period corresponding to operation of the pump, arbitrarily selected between a first minimum time and a first maximum time, and selecting by a user a second time period corresponding to a delay in operation of the pump. The delay may be arbitrarily selected between a second minimum time and a second maximum time. 
     Typically, an apparatus may be constructed to contain a housing, a pump disposed within the housing (typically of a type having a diaphragm compressing air drawn from the ambient), and a magnetic electric motor driving the pump. The motor may be an oscillating type, having a coil and a first magnet (electromagnet) connected to reciprocate an electric field. The electromagnet drives a permanent magnet back and forth to oscillate the diaphragm. The pump may have two diaphragms in symmetric arrangement to reduce vibration. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing features of the present invention will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only typical embodiments of the invention and are, therefore, not to be considered limiting of its scope, the invention will be described with additional specificity and detail through use of the accompanying drawings in which: 
         FIG. 1  is an exploded view of one embodiment of a quite pump apparatus in accordance with the invention; 
         FIG. 2  is a cross-sectional, side, elevation view of one embodiment of an apparatus with certain items rendered schematically to show their arrangement; 
         FIG. 3  is an exploded view of a pump for use in an apparatus and method in accordance with the invention as disclosed in  FIGS. 1-2 ; 
         FIG. 4  is an exploded view of the inner housing of the apparatus of  FIGS. 1-2  with its liner and other vibration isolation mechanisms; 
         FIG. 5  is an exploded view of the end cap for the inner housing having the motor magnet potted therein and illustrating an exploded view of the mounting and filter hardware as well as isolation feet for this portion of the inner housing and motor support; and 
         FIG. 6  is a cross-sectional, side, elevation view of the apparatus of  FIG. 1  assembled and illustrating the flow of air therethrough. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     It will be readily understood that the components of the present invention, as generally described and illustrated in the drawings herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the system and method of the present invention, as represented in the drawings, is not intended to limit the scope of the invention, as claimed, but is merely representative of various embodiments of the invention. The illustrated embodiments of the invention will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. 
     Referring to  FIG. 1 , a system  10  or apparatus  10  may provide a supply of air virtually silently to drive various types of life support or breathable air. For example, a system  10  in accordance with the invention may supply air to an aroma therapy atomizer, aquarium, or the like. In general, an apparatus  10  may include an outer housing  12 . The outer housing  12  may be divided into two portions in order to be able to receive other components therewithin. 
     In the illustrated embodiment, the outer housing contains electronics  14  or control systems  14  to control the volume, duration, and delay times between delivery of a supply of pressurized air. In the illustrated embodiment, an inner housing assembly  16  or inner housing  16  further provides isolation to separate a motor  18  or the larger and fixed components thereof from a pump  20  within the inner housing  16 . 
     Mechanical isolation of the inner housing  16  from the outer housing  12  is provided by use of elastomeric components, damping, and decoupling of supports and by supports between the inner housing  16  or the outer housing  12 . Selective positioning of required connections minimizes mechanical advantage and connection between various components. 
     Moreover, the inner housing  16  is substantially sealed as to any gaps that might pass acoustic vibrations. The exception to the sealing is the path of air actually being inducted and pressurized before being pumped out for use. Even that stream or flow of air is selectively isolated from certain components, passed through tortuous and narrow passages, to filter acoustics while exposed to other components, according to particular needs. 
     Referring to  FIG. 2 , an upper shell  22  of the outer housing  12  is positioned opposite a lower shell  24  of the housing  12 . In the illustrated embodiment, feet  26  are formed of an elastomer selected for its softness and thus damping of vibration. In this way, the outer housing  12 , may be isolated further from its environment, such as a supporting surface, table, dresser, or the like. 
     The damping ability of the feet  26  in an axial direction (e.g., vertically, for example) may be substantial according to the selection of the elastomer from which the feet  26  are formed. Meanwhile, both the softness of the elastomer and the length or extent of each of the feet  26  also tends to provide radial isolation against any transmission of mechanical vibration therebetween. 
     In the illustrated embodiment, a seal  28  may be formed as a gasket, ‘O’ ring, or the like. Typically, the gasket  28  may be selected from various elastomers and shaped to provide a substantially hermetic seal between the upper shell  22  and lower shell  24  of the housing  12 . An outlet  30  provides a controlled penetration between the outer housing  12  and the environment. Nevertheless, the outlet  30  in one currently contemplated embodiment is isolated from the other components contained within the outer housing  12  by a long, flexible tube that wraps inside the housing  12  in order to avoid supporting any mechanical connection of force or movement between the outlet  30  fixed to the housing  12 , and any of the contained components therewithin. 
     Likewise, another penetration is made to support a fitting  32  supporting entrance of an electrical power cord. The length and flexibility of the cord  33 , and its contained components, along with the selection of the softness of the elastomer from which the fitting  32  is fabricated provide for a tight, interference fit between the outer housing  12  and the fitting  32 . For example, fasteners securing the upper shell  22  to the lower shell  24  capture the fitting  32  therebetween and can distort it elastomericaly in order to confirm a tight, hermetic seal therebetween. 
     The inlet  34  may be engineered as the only aperture  34  through which air may enter into the outer housing  12 . All other penetrations are typically sealed against passage of air and transmission of sound therethrough. Meanwhile, openings such as the inlet  34  are provided highly circuitous paths of small dimension (e.g., from about one hundredth to about one quarter inch hydraulic diameter) in order to attenuate, absorb, and otherwise disrupt and redirect any acoustic waves that might escape from the apparatus  10  therethrough. 
     In the illustrated embodiment, the inlet  34  feeds air into a filter  36  or filter medium  36 . Thereafter, air is released through a passage from the area of the filter  36  into the interior of the outer housing  12 . The keeper  38  securing the filter medium  36  or filter  36  in position may be vented in various locations to provide passage of air from the inlet  34  into the interior of the housing  12 . 
     As a practical matter, the difficulty of isolating vibration from mechanical reactions as well as acoustic (sound) waves from the moving components of the apparatus  10  is complicated by the fact that any use of energy, particularly motors, will generate heat. That heat must be dissipated. When it is dissipated, it must be transferred away into some medium such as the ambient air or it may destroy the electrical and electronic components generating that heat. 
     Accordingly, the need to transfer heat away from electrically active componentry stands in opposition to enclosing and isolating those same components in order to reduce or eliminate acoustic and mechanical vibrational interactions that may cause undesirable noise, chatter, or the like between the apparatus  10  and its environment, including its supporting surface. Thus, the inlet  34  provides cooling air for the motor  18  and the electronics  14  inside the outer housing  12 . 
     Continuing to refer to  FIGS. 1-2 , a control assembly  40  or printed circuit board  40  equipped with the proper circuitry and controls may provide three principle control abilities. A flow control  41  typically controls the power to the motor  18 . By control of power, the net throughput of air, measured by mass flow rate or volumetric flow rate may be controlled. 
     Meanwhile, a control  42  or controller  42  controls the duration of operation of the motor  18  driving the pump  20 . For example, the duration control  42  may provide an infinitely variable selection of time from zero to any other number selected. In certain presently contemplated embodiments, a minimum time may be provided for the duration control, such as a minimum of 1 minute. Otherwise, the control  42  might have no dead space and might oscillate between an on and off condition indefinitely if improperly adjusted. 
     Likewise, as a practical matter for typical applications, a duration of from about 10 to about 60 minutes is typically a maximum time an individual may choose to have the pump  20  and motor  18  operating at one session. Similarly, delays of the same amounts may be selected. In one presently contemplated embodiment, times may set at from between 1 second and 60 minutes. Typically, it has been found suitable to permit or to select controls  42 ,  43  that may be set at any location on a continuously variable and infinitely variable scale between about 1 minute and 20 minutes. 
     The controller  43  or delay control  43  provides a user the ability to set arbitrarily and selectively the specific amount of time delay between adjacent durations of operation. For example, the duty cycle of a motor  18  and pump  20  may be controlled by the ratio of total duration of operation divided by the total time of delay plus that duration of operation. Thus, a duty cycle may be described as a fraction of the total elapsed time that the motor  18  and pump  20  are in actual operation. Various knobs  44   a ,  44   b ,  44   c  may control or provide actuation by a user for the flow control  41 , duration control  42 , and delay control  43 , respectively. Here, knob  44   b  is identical to, and removed by the cross sectional cut from in front of, knob  44   c  in  FIG. 2 . 
     Referring to  FIG. 3 , while continuing to refer generally to  FIGS. 1-2  the apparatus  10  may enclose within the inner housing  16  a pump  20 . The pump  20  may provide air discharged through an outlet  45 . 
     Referring to  FIG. 3 , the pump  20  may include a pump body  46  or body  46  central thereto. The body  46  may have formed therein a passage  48 , here illustrated as it emerges from two faces of the body  46 . The passage  48  provides an inlet for air coming from within the housing  12  into the pump  20 . Likewise, a passage  50  originates from a face of the body  46 , and eventually exits through the outlet  45  of the pump  20 . 
     In the illustrated embodiment, a slot  52  or pinch slot  52  receives a valve body  56  therein, thus providing support along a large portion of the periphery of the valve body  56 . Thus, the passages  48 ,  50  are operably connected to compression chambers  53  in the respective valve bodies  56 . A retainer  55  may secure the pump body  46  to the inner housing  16  through apertures  90 . The tapered face  58  of each valve body  56  illustrates that each is formed with an angle  59 . Thus, the pinch slot  52  may more easily capture but then tightly secure the valve body  56  once it is fully inserted into the pinch slot  52 . 
     Covering, and associated with the apertures in the pump body  56  corresponding to the passages  48 ,  50  in the pump body, are reeds  60  or flappers  60  secured by keepers  62 . (The generic reference may be used herein to represent all of the specific examples, such as a generic  60  for specifics  60   a ,  60   b , here illustrated, and  102  for  102   a ,  102   b  hereinbelow) The reeds  60  act as one-way valves, each permitting flow in one direction and resisting flow in the opposite direction. Accordingly, each of the compression chambers  53  may draw air in through the passage  48 , then seal off the passage  48  with the reed  60 . Accordingly, the passage  50  may be sealed off against back flow, but opened to be accessible by the reed  60   b  opposite the reed  60   a . Actually, the reeds  60   a ,  60   b  are not exactly opposite one another but rather, each is on an opposite side of the valve body  56 , acts in an opposite direction, and services an aperture for one of the passages  48 ,  50 . 
     Typically, a diaphragm  64  may be formed in a single piece to secure about the chamber  53 . Thus, a diaphragm  64  may form a sealing and a closure for the chamber  53 . Each diaphragm  64 , of which there may be a single diaphragm  64 , or multiple diaphragms  64 , may be secured to the pump  20  by fasteners to a swing arm  66 . The swing arm  66  itself may include a yoke  65  secured to a hinge  68 . Meanwhile, opposite the yoke  65  a magnet  67  secured to the swing arm  66  operates as an armature  67  in conjunction with the drive mechanism. 
     The yoke  65 , capturing a hinge  68 , such as a resilient tubing may provide a comparatively wear-free, damping, long-lived attachment mechanism. The hinges  68  recessed into the retainer  54  provide a pivot access for each of the swing arms  66  about the yokes  65  thereof. 
     Various seals  70  may be provided to both limit and secure passage of air through the pump  20 . For example, a seal  70  may be formed as an ‘O’ ring fitted into a slot  72  or groove  72 . Accordingly, the seal  70  provides securement of the flow of air from the passage  50  into the valve body  56 . Likewise a seal  74  may be configured to fit in a groove  76  or slot  76  sealing the passage of air between the passage  48  and the valve body  56 . Thus, the seals  70 ,  74  fit between the valve bodies at the grooves  72 ,  76 , and against the faces  78  of the pump body to effect their seal. 
     The diaphragms  64  operate by the oscillation of the armatures  67  driving the swing arms  66  to pivot about their yokes  65  and hinges  68 . Accordingly, the armatures  67  pivot in an almost linear fashion, driven by electromagnetic forces. 
     The reeds  60   a ,  60   b  provide substantially instantaneous valving in accordance with the pressure within and without the chamber  53 . Thus, air is drawn into the chamber  53  by the diaphragm  64  as it moves away from the valve body  56 . Similarly, air is pushed back from the diaphragm through the valve body  53  and into the passage  50  by the diaphragm  64  under the control of the reeds  60   b.    
     Referring to  FIG. 4 , while referring generally to  FIGS. 1-3 , the inner housing  16  may include a comparatively harder structural component such as a shell  80 . The shell  80  may be provided with an edge  81  to receive a closure. Prior to closure of the shell  80 , a liner  82  may be inserted therewithin. In the illustrated embodiment, the liner  82  is formed of a comparatively soft elastomer selected for its ability to dampen sound and vibration rather than transmitting it therethrough or therealong. 
     For example, the wall  83  of the liner  82  may be comparatively thin, thus in combination with the soft elastomeric properties of the material thereof may substantially reduce or eliminate any vibration or transmission of vibration along the surface thereof. Meanwhile, by selecting hardness (e.g., softness) for the elastomer from which the liner  82  is molded or otherwise formed, the liner may substantially dampen any vibration or acoustic vibration passing through the wall thereof. 
     In one embodiment, the liner  82  may be spaced a distance away from the shell  80  in order to provide an air gap therebetween. In the illustrated embodiment, the lip  84  of the liner  82  fits inside the shell  80 . Meanwhile, no continuous source of substantial contact is made between the wall  82  and the shell  80 , except near the relief  85 . The relief  85  is formed in the liner  82  in order to accommodate certain manufacturing components. 
     For assembling the apparatus  10 , a method may include insertion of the liner  82  into the shell  80  of the inner housing  16 . The shell  80  may be provided with an edge to capture the lip  84 . In one embodiment, a recess or groove inside a shoulder within the interior of the shell  80  captures the lip  84  and secures it, urging it against the outer most contact with the interior surface of the shell  80 . 
     Meanwhile, inserting the liner  82  a sufficient distance into the shell  80  permits alignment of an aperture  86  in the liner  82  with an aperture  87  in the shell  80 . Each of the liner  82  and the shell  80  may include both upper and lower apertures  86 ,  87 , respectively. Upon alignment of the apertures  86 ,  87 , a fastener  88  may pas through both apertures  86 ,  87  to secure the pump  20  therewithin. 
     As a practical matter, the fasteners  88  may provide a mechanical coupling between the pump  20  and the shell  80 . Thus, a principal purpose of the shell  80  in the illustrated embodiment is to provide acoustic isolation, of the pump from its environment, notwithstanding vibrational or mechanical vibration isolation is not occur as effectively between the pump and the shell  80 . Rather, the inner housing  16  is mechanically isolated by other mechanisms to be described hereinbelow. 
     An additional aperture  89  may receive fasteners from the pump. The aperture  89  may be aligned with the aperture  90  to pass a clip  55  from the pump  20  therethrough to register and temporarily secure the pump  20  or align the pump  20  in registration with the shell  80 . Thereafter, an aperture  92  may be aligned with an aperture  93  in order to receive a fastener  94  securing the shell  80  to the pump  20 . Thus, the pump is held rigidly to the shell  80  with the soft elastomer of the liner  82  between a pump  20  and the shell  80  to damp vibrations. Meanwhile, the pump  20  is suspended by three fasteners  88 ,  94  providing a secure, 3-point connection in order to minimize misalignment and chatter between the pump  20  and the shell  80 . 
     The aperture  96  is sized to form an interference fit with the outlet  45  of the pump  20 . The outlet  45  has a diameter larger than that of the aperture  96 . Accordingly, the elastomeric material of the liner  82  stretches to fit around the outlet  45 , thus making an effective acoustic and hermetic seal between the pump  20  and the remaining interior of the outer housing  12 . Because each of the fasteners  88 ,  94  may be tightened to compress the liner  82  between the fastener  88 ,  94  and the pump  20 , the apertures  86 ,  92  may provide clearance fits, which may then be closed by compression according to Poisson&#39;s principle controlling distortion of materials. 
     The outlet  45  feeds air from the pump  20  directly into a chamber  98  or plenum  98 . The chamber  98  may be provided with one or more ports  100 . In the illustrated embodiment, the port  100   a  opens downward, while the port  100   b  opens upward. Meanwhile, seals  102   a ,  102   b  seal each port  100   a ,  100   b , respectively. In the illustrated embodiment, an adaptor or fixture  104  sometimes referred to as a barbed fitting may fit into the port  100   a  to receive a connecting line for conducting air from the pump  20  to a delivery point. 
     Meanwhile, in the illustrated embodiment, a plug  106  closes off the port  100   b . The ports  100   a ,  100   b  may be configured as desired with a fitting  104  or a plug  106 . Meanwhile, the seals  102   a ,  102   b  provide air-tight sealing by a mechanism such as gaskets, ‘O’-rings, or the like. 
     Legs  108  provide substantially complete radial isolation of mechanical vibrations between the shell  80  and the outer housing  12 . According to the softness (alternative of hardness) of the elastomeric material from which the legs  108  are formed, an additional degree of axial (e.g., vertical) isolation is also provided between the shell  80  and the outer housing  12 . 
     In the illustrated embodiment, the legs  108  each contain a collar  109  or collar portion  109  that may be fitted with an interference fit in a corresponding aperture (not shown) in the shell  80 . The leg  108  may be stretched to insert the collar  109  into the aperture, into which the resilience of the leg  108  will shorten the length thereof and expand the diameter of the collar  109  to provide the interference fit. 
     Meanwhile, a neck  110  or neck portion  110  provides an extremely small diameter that is substantially radially unstable. Thus, the softness selected for the elastomeric material of the leg  108  may be further enhanced by the small diameter of the neck  110 . Accordingly, a foot  111  resting on the lower shell  24  of the outer housing  12  can support substantially no lateral (radial) forces to be transmitted between the shell  80  and the outer housing  12 . Meanwhile, the softness of the elastomer of the leg  108  provides additional isolation in an axial direction to both dampen and isolate vibrations generated by the pump and transmitted to the shell  80  from transmitting to the outer housing  12 . 
     Above the collar  109  a keeper  112  provides securement of the leg  108  within an aperture (not shown) in the shell  80 . The diameter of the keeper  112  may be reduced by stretching the length of the leg  111 , thus providing for insertion of the collar  109  through an aperture. Thereafter, upon release of the extension force the length of the leg  108  will return to an equilibrium position leaving the keeper  112  and the remainder of the leg  108  to capture the shell  80  on either end of the collar  109 . 
     In general, the liner  82  and the legs  108  may be formed of polymers having elastomeric properties suitable for isolation and damping of mechanical vibration. Likewise, any acoustic vibration transmitted to the shell  80  may be damped thereby to an extent designed by selection of the materials. Meanwhile, the use of an extended length of conduit or tubing formed of soft polymer or elastomer and connected to the fitting  104  will also provide substantial vibration isolation from any mechanical vibration or force that might otherwise be transmitted between the shell  80  and the outer housing  12 . 
     Referring to  FIGS. 5-6 , while continuing to refer generally to  FIGS. 1-4 , an end plate  120  forms the completion of the enclosure of the inner housing  16 . In one embodiment, the end plate  120  may include a coupler  122  or coupler portion  122  inserted inside the open end of the shell  80 . The coupler  122  terminates at a face  124  sealed and impervious to any transmission of mass, particularly air. The coupler  122  thus presses the face  124  against the lip  84  of the liner  82 . Accordingly, the coupler  122  serves as a keeper  122  holding the lip  84  into its slot within the shell  80 . 
     The lip  84 , being made of the same material as the remainder of the liner  82 , thus provides the mechanical damping of vibrations between the coupler and the shell  80 . Perhaps more importantly, the lip  84  thus provides a gasket sealing the interior of the liner  82  against the face  124 . Every opening in the liner  82  may be sealed by compression, an interference fit, or the like. Accordingly, with the exception of the path of pumped air into and out of the pump is substantially sealed against any movement of gas or sound waves (e.g., air) therethrough. 
     A rim  126  on the end plate  120  may be homogeneously molded with the end plate. In one embodiment, the entire end plate  120  including the coupler  122 , rim  126 , and the coil  127  and coil  128  assembled may be potted together. The end plate  120  may be cast, or may be formed as a partial casting to be potted later with the magnet assembly  129  (e.g., coil  127  and coil  128 ) potted therein. Thus, the end plate  120  may be homogeneously molded as a single piece containing both the coupler  122  and rim  126  and potting the magnet  129  of the motor  130  therewithin. 
     In the illustrated embodiment, the face  124  may be spaced away from all parts of the magnet  129 . Accordingly, both the coil  127  and the core  128  may be spaced away from the face  124  in order to provide a complete, integral seal thereby. Meanwhile, the coupler  122  may be provided with a detent of some type such as a groove, boss, rise, clip, barb, or the like to engage a corresponding portion of the shell  80  in order to secure the coupler  122  inside the shell  80 . 
     A portion of the motor  130 , the magnets  67  are illustrated in  FIG. 3 . The magnets  67  operate near but without contacting the face  124 . Thus, the magnets  67  may interact with the magnetic core  128  of the motor  130  without actually contacting any part thereof mechanically. 
     Fasteners  131  inserted through relief locations within the core  128  may secure the motor  30  to the mount  132 . The mount  132  in the illustrated embodiment serves multiple functions. For example, the mount  132  provides a housing  134  to contain a filter  135  or filter medium  135 . That is, sometimes it is proper to speak of a filter as both the housing  134  and the contained filtering media  135 . A keeper  136  or lid  136  may snap into the housing  134  to secure the filter  135  therewithin. 
     In addition to the filter housing  134 , a mount  132  provides legs  138  to support the motor  130  within the inner housing  16 . In order to maintain the mechanical isolation of a inner housing  16  with respect to the outer housing  12 , the legs  135  may be provided with isolating feet  140 . 
     In the illustrated embodiment, the feet  140  are formed in a convoluted shape such that an inner portion thereof receives a leg  138 , while the outer portion thereof is offset both radially and axially to extend beyond the inner portion. Thus, radial motion of the leg  138  is isolated by the convoluted shape of the foot  140 . Meanwhile, axial movement due to vibration of the leg  138  is actually taken up and absorbed, by the convolution in the foot  140 . In certain embodiments, the selection of any elastomeric material to form feet  140  may provide sufficient thickness and softness to absorb a substantial portion of any mechanical vibration presented by the leg  138 . 
     It may be seen from the foregoing that the inner housing  16  remains mechanically isolated from the outer housing  12 . Restraints formed in the outer housing  12  to contain the feet  140  against radial and axial motion will not constrain substantially the leg  138  captured therein. Thus, as explained, the leg  138  may translate axially and radially without requiring movement of the portion of the outermost perimeter of the foot  140 . 
     It may be seen that the feet  140 , along with the leg  108  positioned at the opposite end of the inner housing  16  provide isolation and damping in three dimensions and nearly perfect isolation in at least two. 
     The filter housing  134  contains inlet apertures  142  or apertures  142  receiving air from inside the outer housing  12 . Since the filter housing  134  is located outside the shell  80  and its enclosing end plate  120  or cap  120  air must pass near or around the coil  127  and core  128  of the magnet  129  to gain access to the apertures  142 . Thereafter, the air must pass down through the apertures  142  and around the rim surrounding each. Thereafter, the air must pass through the filter medium  135 , up over rims (see  FIG. 6 ) on the hidden side of the lid  136 . 
     Various slots in the rims of the lid  136  may provide preferential release of air to enforce these more circuitous paths towards the nearest wall, and thus through a greater extent of the filter media  135 , instead of the most direct route from the aperture  142  to the outlet  146 . The outlet  146  is connected by a passageway  147  in the filter housing  134 . Air may then pass from the outlet  146  into the cavity  150  of the shell  80 . The cavity  150  is contained within both the liner  82  and the shell  80 . 
     As can be seen, the path of air provides a draw bringing air from within the surrounding environment into the outer housing  12  through an inlet  34 . From within the interior of the outer housing  12 , air is drawn from a location near the motor  130 , and particularly the coil  127  and core  128  thereof to enter the inlet  142  of the filter housing  134 . After passing through the filter media  135  and through the outlet  146 , the air is free to circulate within the cavity  150  of the inner housing  16 . From a location at or near the top of the cavity  150 , the passage  48  draws in the air into the pump as described hereinabove. Meanwhile, the pump body receives air from the chambers  53  into the passage  50  for discharge through the outlet  45 . From the outlet  45 , air passes into the chamber  98 , which passes the pressurized air out through the fixture  104  into a connecting line to be discharged to the environment. The connecting line (not shown) is formed of a sufficiently soft elastomer of a sufficient length to isolate the inner housing  16  from the outlet  30  and thus the outer housing  12 . 
     The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative, and not restrictive. The scope of the invention is, therefore, indicated by the appended claims, rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.