Abstract:
A generally cylindrical restrictor insert for containing an axially movable, apertured restrictive member, housed in a flow control distributor housing of an orifice expansion device used for bi-directionally-flowing pressurized fluid, with a housing passageway being closed off via an annular adaptor flange also having an internal filter, the restrictor insert having a central axial through bore with a plurality of adjoining bore portions defining a central bore cavity, the restrictor insert also having a leading portion, with a frusto-conical front end surface, and intermediate and trailing portions, the latter having a shoulder portion and an annular end face, the restrictive member being located and axially freely movable within a distributor housing central bore cavity, with the restrictor insert, in turn being located, via slip-fit insertion, in a distributor housing central passageway. The use of a restrictor insert permits interchangeable use of differing restrictive members within a common distributor housing.

Description:
CROSS-REFERENCE TO RELATED CASES 
   The present application claims the benefit of the filing date of U.S. Provisional Application Ser. No. 60/554,096, filed Mar. 18, 2004, the disclosure of which is incorporated herein by reference. 

   BACKGROUND OF THE INVENTION 
   Orifice piston expansion devices are utilized for metering the flow of pressurized fluid, such as refrigerant medium, along two or more fluid flow paths within a refrigeration or cooling system, such as between the condenser and evaporator coils of a heat pump or other such devices that include a reversible refrigeration cycle. More particularly, existing restrictive members, such as various types of pistons are used, within flow control distributor housings, to perform the required metering and bypass functions, which are well known in the art. Such existing expansion devices and pistons are shown and described, in U.S. Pat. No. 4,896,696, to Bradley et al. and in even more detail in U.S. Pat. No. 5,894,741 to Durham et al., which is also assigned to the assignee of the present invention. Such prior art flow control distributor housings were designed to generally receive only one style of such restrictive members or pistons. 
   In addition to the above-noted references, the patent literature includes a large number of orifice expansion devices or the like and included in this art are: U.S. Pat. No. 5,265,438 to Knowles et al.; U.S. Pat. No. 5,893,273 to Casiraghi; U.S. Pat. No. 6,363,965 B1 to Carmack et al.; U.S. Pat. No. 6,367,283 B1 to Ederle; and U.S. Pat. No. 6,560,987 B2 to Kreger et al. While the noted Kreger et al. patent discloses a cartridge for a restrictor, this cartridge only provides a seat for a bullet nose type of restrictor and will not accommodate the remaining piston styles. In addition, and importantly so, the cartridge is subsequently brazed in place and, consequently, not replaceable. It is deemed that none of the prior art structures, set forth in the noted references, pertain to the orifice expansion device, the improved orifice expansion device and the restrictor insert, of the present invention. 
   FIELD OF THE INVENTION 
   The present invention pertains to orifice expansion devices used in, for example in refrigeration and cooling systems, for conveying bi-directionally movable pressurized fluid. Specifically, this invention pertains to a cylindrical restrictor insert that permits the interchangeable use of differing restrictive members within a common distributor housing. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded sectional view of an orifice piston expansion device that utilizes the restrictor insert of the present invention; 
       FIG. 2  is a sectional view showing the orifice piston expansion device of  FIG. 1  in an assembled condition (without the fastening member), with the movable piston being positioned in the metering direction; and 
       FIG. 3  is a sectional view, similar to that of  FIG. 2 , but with the movable piston being positioned in the free-flow direction. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring now to the several drawings, illustrated in  FIG. 1 , in an exploded view, is an orifice expansion device, generally indicated at  10 , that utilizes the restrictor insert  14  of the present invention. Expansion device  10  is basically comprised of a flow control distributor housing  12 , the restrictor insert  14 , a restrictor or piston  16 , an adaptor  18  and a fastening member  20 . Since the basic structure, mode of operation and function of expansion device  10  are well known in the art, in the interest of brevity, only those portions thereof that are necessary for a complete understanding of this invention will be described in detail hereinafter. Each of the noted components, except for restrictor insert  14 , is known in the art and explained in greater detail in previously cited U.S. Pat. No. 5,894,741, to Durham et al. 
   Flow control distributor housing  12 , which is of a generally cylindrical shape and which may be configured to include an intermediate hexagonal flats section  24 , for engagement with wrench or the like, also includes a forward distributor end  26  and a rearward coupling end  28 . Forward distributor end  26  is structured to terminate in an angled nozzle face  30 , while rearward end  28  is externally threaded for connection to adaptor  18 . Nozzle face  30  is provided with at least a single port opening  32  for admitting refrigerant medium flow through device  10 . Housing  12  further includes a central fluid passageway  36  extending along a central longitudinal axis  38 , from a forward passageway end  40  to an open rear passageway end  42 . Forward passageway  40  is coupled in fluid communication with each of port openings  32  via individual associated ducts  34 . 
   For effecting a fluid tight seal with restrictor insert  14 , an annular frusto-conical valve seat  46  merges into passageway  36 , intermediate forward and rear ends  40  and  42 , respectively. The small diameter end of valve seat  46  merges into passageway  36  while the large diameter end thereof merges into an annular shoulder  48  which also forms the inner end of a chamber  50  having a cylindrical outer surface  52 . Rearward coupling end  28  includes an annular end face  54  having a step portion  56 , the small diameter end of which normally intersects open rear passageway end  42 . 
   Turning now to restrictor insert  14 , which is of generally cylindrical shape, includes a central, longitudinal, through bore  60  comprised of a cylindrical front or first bore portion  62 , of a predetermined first diameter bore, coupled to a cylindrical intermediate or second bore portion  64 , of a predetermined second diameter bore, via a frusto-conical joinder bore portion  66 , and a cylindrical rear or third bore portion  68 , of a third predetermined diameter bore. Restrictor insert  14  also includes a cylindrical central portion  72 , having a cylindrical outer peripheral surface  74 , a leading or front portion  76  having multiple annular steps  78 ,  80 , as well as a leading frusto-conical front end surface  84 , separated from step  80  via a peripheral groove  82  which serves to locate a seal member  94  preferably comprised of a PTFE material or the like. Restrictor insert  14  additionally includes a trailing or rear portion  86  having an annular outer shoulder step or surface portion  88  that is joined to an annular end surface  92  via an intermediate conical portion  90 . The trailing end of inner cylindrical surface  52  of chamber  50  forms the inner diameter portion of annular end surface  92 . 
   Continuing now with restrictive member, restrictor, or piston  16 , which is shown for illustrative purposes only, is generally cylindrical in shape and is provided with a central, longitudinal through bore  100 . Typical piston  16  includes an annular front end portion  102  that includes a frusto-conical or curved front end surface  104 , with a radius  105 , the former, in turn, merging into a cylindrical rear portion  106  having an annular rear end portion or surface  108 . A typical prior art restrictor or piston of this type, referred to in the industry as a “bullet-nose” piston, is shown and described in U.S. Pat. No. 4,896,696 to Bradley et al. If desired, the cylindrical peripheral outer surface  110  of rear portion  106  can also be provided with a plurality of axially aligned flutes or channels (not shown) in a manner well known in the art and shown and described in previously noted U.S. Pat. No. 5,894,741 to Durham et al. 
   Turning now to adaptor  18 , it is conventionally provided with a forward flange end  118 , over which is received the known internally threaded nut or other conventional fastening member  20 , for a threaded connection with coupling end  28  of flow control distributor housing  12 , and a rearward tubular end  120 , which is generally configured (not shown) for a brazed, soldered, sweat or other connection with a further tube, conduit or other refrigerant medium supply line in a manner well known in the art. Mounted within adaptor  18 , at a peripheral inner cylindrical surface  122  of flange end  118 , is a screen or other in-line filter member  124  adapted for separating particulate contaminants from the refrigerant medium flow. As will be discussed in more detail later, screen annular end face  126  serves as an abutment surface for piston annular end portion  108 , when piston  16  is in the  FIG. 3  free-flow direction of the refrigerant medium within orifice expansion device  10 . 
   Adaptor flange end  118  includes a further inner peripheral cylindrical surface  128  of a diameter slightly greater than that of the maximum outside diameter of piston  16  so as to permit free axial sliding movement of piston rear end portion  106  toward and away from screen end face  126 . In addition, flange end  118  also includes a cylindrical portion  130 , adapted to mate with an interior surface  58  of housing end face  54 , while a flange end annular end face  132  is adapted to abut housing annular end face  54 , upon the assembly of adaptor  18  to housing  12 , as best seen in  FIGS. 2 and 3 . An inner annular end face  136  can function as a rear abutment surface that limits any axial movement of restrictor insert  14 , in one direction, within housing chamber  50 , as will be detailed later. 
   In terms of the assembly of orifice expansion device  10 , as best seen in  FIG. 1 , restrictor insert  14  is adapted to be axially inserted into housing chamber  50  until restrictor insert leading frusto-conical front end surface  84 , together with seal member  96 , makes physical contact with housing frusto-conical valve seat  46 . Then, restrictor or piston  16  is inserted into a central bore cavity  70 , defined by piston bore portions  64 ,  66  and  68 , until there is physical contact between bore portion  66  and restrictor front end radius portion  105 . Thereafter, adaptor flange end  118 , specifically cylindrical portion  130  thereof, is mated with housing interior surface  58  until there is physical contact, in the manner already described, in terms of abutment between housing end face step portion  56  and adaptor flange annular end face  132 , whereupon nut  28  is threaded upon housing cavity end  28 , thereby completing the mechanical assembly of orifice expansion device  10 . 
   In terms of the operation of device  10 , restrictive insert  14 , when installed as described, has only limited axial movement capabilities within housing cavity  50 , but piston  16  is capable of cycling, within insert  14 , depending upon the direction of flow of the refrigerant medium, so as to alternately perform the required metering and bypass functions which are well known in the art. Specifically, piston  16 , which is shown in  FIG. 2  as being positioned in the metering direction, wherein its front end portion  102  abuts restrictor insert joinder bore portion  66 , permits refrigerant medium flow from right to left, via through bore  100  only, in a metering function or operational phase. Thus, piston  16 , which is moved fully to the left, within insert  14 , provides a metering function in one axial direction. 
   When the refrigerant medium flows from left to right, piston  16  is displaced, within restrictor insert  14 , to the right, until its end portion  108  abuts screen end face  126 , as illustrated in  FIG. 3 , thus establishing free-flow since the refrigerant medium not only flows via piston through bore  100 , but also around and over the outer periphery of piston  16  and through the axial flutes, if so provided, in a manner well known in the art. Thus, at this time, it should be well understood that, while retention insert  14  may have but limited axial movement within housing  12 , piston  16 , is able to axially cycle freely within insert  14  to perform the noted metering and bypass functions. Insert  14  can be comprised of any refrigerant medium-compatible material and preferably consists of a brass alloy, if machined, or a nylon material, if molded. 
   The utilization of a separate, distinct, restrictor insert  14  allows independent coil manufacturers and installers to use any of the known types of restrictors or pistons  16  in the same or a common flow control distributor housing  12 . Thus, for example, the three-fluted or five-fluted pistons, set forth in U.S. Pat. No. 5,894,741 to Durham et al., as well as the “bullet-nose” pistons, set forth in U.S. Pat. No. 4,896,696 to Bradley et al., can be used interchangeably. While restrictor insert  16  is illustrated as having a predetermined, specific axial extent, this can be adjusted, e.g., decreased if needed, so as to function successfully in other flow control housings. Therefore, while in the past, flow control distributor housings  12  were specifically designed and manufactured to accommodate but one style of piston  16 , the present invention promotes ready interchangeability thus not only increasing choices, decreasing required part proliferation, inventories and costs, but also permitting a convenient, cost-effective, way of replacing or substituting pistons  16 , if so desired. In the prior art structures the entire orifice expansion device had to be replaced. 
   It is deemed that one of ordinary skill in the art will readily recognize that the present invention fills remaining needs in this art and will be able to affect various changes, substitutions of equivalents and various other aspects of the invention as described herein. Thus, it is intended that the protection granted hereon be limited only by the scope of the appended claims and their equivalents.