Abstract:
A pump has a motor pump unit enclosed by clam shell housing sections. The pump moves a working fluid through the housing to an outside load. Each section has intake walls defining a portion of an intake chamber and outlet walls defining a portion of an outlet chamber. The intake walls of each section seal against one another to define a sealed intake chamber which is in communication with the intake port of the pump unit, and the outlet walls of each section seal against one another to define a sealed outlet chamber which is in communication with the outlet port of the pump unit.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This claims the benefit of U.S. Provisional Patent Application No. 60/175,183 filed Jan. 10, 2000. 

   STATEMENT CONCERNING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not applicable. 
   FIELD OF THE INVENTION 
   This invention relates to housings or cabinets for pumps such as compressors or vacuum pumps. In particular, this invention concerns such a pump in which clam shell halves of the housing form seals at their abutting edges to define pressure or vacuum chambers or passageways within the housing. 
   BACKGROUND OF THE INVENTION 
   In many applications, a compressor or vacuum pump is housed inside a cabinet (a.k.a., housing), which may be of molded plastic. In the case of a compressor, the compressor needs intake air, which must be drawn in from outside of the housing and directed to the intake port of the pump, the pump compresses it, and delivers it to a pressurized exhaust port. Typically, tubing Is used to direct the output of the exhaust port to a port which is accessible by the user from outside of the housing. The intake air delivered to the pump usually must be filtered, so that only filtered air is delivered to the intake port, and tubing or passageways are required to communicate the filtered air to the intake port. 
   SUMMARY OF THE INVENTION 
   The invention provides an improvement to a pump having clam shell housing sections in which each said housing section has one or more walls which seal against one or more walls of the other housing section to define a sealed pressure or vacuum chamber within the walls when the housing sections are brought together. The walls come together to provide a seal all the way around the chamber, which may be an inlet chamber, an outlet chamber, or a pressurized (including depressurized) passageway, so that a pressure difference can be contained in the chamber, either positive or negative. Thereby, additional tubing or passageways in addition to the housing for routing the intake and outlet of the pump are obviated. 
   In a preferred form, the walls are overmolded with an elastomeric sealing material. The walls may seal against one another in end to end contact, or a wall may seal against the side surface of another wall. In the latter case, it is preferred that the sealing edge of the elastomeric sealing material be tapered to make a good seal, and the underlying edge of the wall may also be tapered to help reinforce the sealing material. Edge to side sealing is done with the exposed side of the sealing material facing the high pressure side, so that the pressure helps establish the seal. 
   The chamber may be in communication with either the intake or outlet port of the pump. At least one of the walls in each housing section may be formed with a half-circular recess in an edge of the wall so that the half circular recesses come together to seal around a circular intake or outlet port of the pump when the housing sections are brought together. A hole or tubular port may also be formed in one or more of the walls to create a means for entry of ambient air to the chamber, mainly for an intake chamber, or a port to which a tube could be connected, mainly for an outlet chamber. 
   The foregoing and other objects and advantages of the invention will appear in the detailed description which follows. In the description, reference is made to the accompanying drawings which illustrate a preferred embodiment of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a top perspective view of one clam shell half of a housing containing a compressor; 
       FIG. 2  is a top plan view of the clam shell half of  FIG. 1 ; 
       FIG. 3  is a bottom plan view showing the other clam shell half which mates with the clam shell half shown in  FIGS. 1 and 2 ; 
       FIG. 4  is a sectional view from the plane of the line  4 — 4  of  FIG. 2 , drawn with both clam shell halves assembled together; 
       FIG. 5  is a cross-sectional view from the plane of the line  5 — 5  of  FIG. 2 , drawn with the two clam shell halves assembled together; 
       FIG. 6  is a cross-sectional view from the plane of the line  6 — 6  of  FIG. 2 , drawn with the two clam shell halves assembled together; 
       FIG. 7  is a cross-sectional view from the plane of the line  7 — 7  of  FIG. 2 , drawn with the two clam shell halves assembled together; 
       FIG. 8  is a cross-sectional view from the plane of the  8 — 8  of  FIG. 2 , drawn with the two clam shell halves assembled together; 
       FIG. 9  is a cross-sectional view from the plane of the line  9 — 9  of  FIG. 2 , drawn with the two clam shell halves assembled together; and 
       FIG. 10  is a top cross-sectional view illustrating the air flow paths through the intake and exhaust chambers defined by the housing. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIGS. 1 and 2  illustrate one clam shell half  12  of a nebulizer housing and  FIG. 3  illustrates the other clam shell half  14 . The nebulizer includes a motor pump unit  16  which has an inlet port  18  and an exhaust port  20 . The inlet port  18  opens into and draws air from an intake chamber  22  and the exhaust port  20  opens into and expels pressurized air into an exhaust chamber  24 . Air is drawn into the intake chamber  22  through a hole  26  in one of the walls of the chamber  22 , and a filter (not shown) may be installed in or over the hole  26 . Air is exhausted from the exhaust chamber  24  through an outlet port  30  which is formed in one of the walls of the exhaust chamber  24  as shown in  FIGS. 9 and 10 . 
   Part of each chamber  22  and  24  is formed by the clam shell half  12  and the other part of each chamber  22  and  24  is formed by the clam shell half  14 . Together, walls of the clam shell halves  12  and  14  create the chambers  22  and  24 , and the chambers  22  and  24  are sealed against the respective ports  18  and  20  so that the chambers  22  and  24  are sealed except at the respective ports  18 ,  26 , and  20 ,  30 . 
   The walls of the clam shell halves  12  and  14  which make up the chambers  22 ,  24  are thin walled molded plastic sections which in each half are integrally molded with the other walls of the half. The clam shell halves  12  and  14  would typically be made of a relatively hard and stiff plastic material such as high impact polystyrene. The walls which make up the chambers  22  and  24  would have a typical thickness of 0.090 inches. The edges of the walls that make up the chambers  22 ,  24 , where they abut all the way around the respective chamber  22 ,  24 , come together to seal the interiors of the chambers  22 ,  24  against a pressure difference. However, for the exhaust chamber  24 , along wall  34 , the edges do not abut, although a wall  36  of the clam shell half  14  abuts the side surface of wall  34 . 
   So that the abutments of the walls of the clam shell half  14  with the walls of the clam shell half  12  may be sufficient so as to create a seal against a pressure difference between the chambers  22  and  24  and atmospheric pressure, at each interface between the walls of the halves  12  and  14 , the interfacing surfaces are coated with a relatively soft, e.g. 50 to 60 durometer, thermoplastic elastomer or thermoplastic rubber (TPR) such as Santoprene. This is preferably overmolded onto the edges of the walls that create the seals for the chambers  22 ,  24 . This can be done in a two-shot injection molding process, either in which the harder plastic which makes up the majority of the halves  12  and  14  is first molded in one mold, and then the halves  12  and  14  are put in separate molds to overmold the relatively softer elastomeric material, or in which the harder plastic is molded in one mold in one shot and then cores of the mold are retracted to make room for a shot of the relatively softer material over the edges of the walls that form the chambers  22  and  24 . 
   As shown in  FIG. 9 , in the case of the seal between the walls  34  and  36 , a single TPR gasket  40  is molded onto the edge of the wall  36  and has a tapered configuration so as to generally match the curvature of the surface of the wall  34  and thereby create a seal between the wall  36 , to which the gasket  40  is attached, and the wall  34  which abuts the gasket  40 . On the other side of the chamber  24 , a gasket  44  is overmolded onto the edge of wall  46  and a gasket  48  is overmolded onto the edge of wall  50 . The gaskets  44  and  48  abut each other to create a seal between them, and thereby create a seal between the walls  46  and  50 . A gasketed interface is provided all the way around each chamber  22  and  24 . Thereby, the only inlet to chamber  22  is hole  26  and the only outlet is port  18 , and the only inlet to chamber  24  is port  20  and the only outlet is port  30 . In normal operation, chamber  22  is subjected to quite low pressure differences, being an intake chamber, with the only pressure difference being created by a filter which may be installed in hole  26 , but chamber  24  may be subjected to pressures on the order of about 15 psi. 
     FIGS. 5 and 6  illustrate how seals are created around the ports  18  and  20  of the motor pump unit  16 . Semi-circles are formed in the walls of the two halves  12  and  14  which, when the edges of the semi-circular openings are overmolded with the relatively soft gasket material, closely mate with the outside diameters of the ports  18  and  20  so as to cradle the ports. As an enhancement to the invention, rather than gaskets such as the gasket  44  and  48  meeting along a flat surface, one of the gaskets  44 ,  48  may be formed with a pointed edge and the other gasket  44 ,  48  may be formed flat, or with a V-shaped groove to receive the pointed edge to create a form fit, to thereby create a more reliable seal. 
     FIGS. 7 and 8  illustrate seals that are created for the intake chamber  22 . The above description for the seals of the exhaust chamber  24  applies to the exhaust chamber  22  as well, although with different walls and gasket edges meeting. In  FIG. 7 , mating overmolded gaskets are identified by reference numbers  60 ;  62  and  64 ;  66 . In  FIG. 8 , mating overmolded gaskets are identified by reference numbers  68 ,  70 . In  FIG. 8 , a relatively tall wall  52  has gasket material  56  at its end, which is tapered, and the gasket material  56  is also tapered to press up against the side of wall  34  of the half  12 . The tapering of the end of the wall  52  helps stiffen the gasket  56  against bending to improve the seal against the curved surface of the wall  34  which is created by pressing the gasket  56  against it. 
   The two cabinet halves  12 ,  14  are held together by any suitable means, such as snap fits, fasteners through holes  80 , a combination of snap fits and fasteners, or any other suitable means. 
   Many modifications and variations to the preferred embodiment described will be apparent to those skilled in the art which will still embody the invention. For example, a sealed passageway incorporating the invention could be made in any shape. Therefore the invention should not be limited to the preferred embodiment described.