Patent Publication Number: US-6708949-B2

Title: Split damper housing

Description:
FIELD AND BACKGROUND OF THE INVENTION 
     The present invention relates to the control of gas flow. 
     More particularly, the invention provides a two-part housing for a damper element, typically useful in air-conditioning ducts, the design of the housing providing manufacturing and installation advantages. 
     Gas flow in furnace chimneys, cooking and water heating appliances used in food preparation, in ventilation vents and air conditioning ducts often require some form of flow control. A simple baffle plate, hinged about its mid point, has been found to operate satisfactorily in most applications. The baffle plate may be controlled by had, be electrically operated but manually controlled, or control and operation can be completely automatic. 
     Where the baffle plate housing is small it can conveniently be made in one piece, as can be seen for example in the “HONEYWELL” automatic furnace vent damper. This unit is intended to reduce room heat losses when the gas furnace is off. The damper has an aluminum cast housing, is available to fit flue diameters between 4″ to 6″ and has a 5 watt motor automatically actuated, 
     In air conditioning systems ducts are typically larger, and a die to manufacture a complete housing would be large, complex and expensive relative to the number of units being produced. 
     Current practice is to construct dampers using two flange-like metal housings which are riveted together. The installation technician needs to take this bulky unit to the site where work is to be carried out. Manufacturing costs for the housing are high. 
     In many countries intense competition prevails between manufacturers, and also between installers of air conditioning systems, wherefore any possible cost reduction of a major component can provide a significant advantage. 
     In U.S. Pat. No. 4,175,593 Sack discloses plastic cable ducting wherein the duct wall is slit along the length thereof. Opposed to the slit, the wall is weakened to form an integral hinge. The dusting is used to cover an existing laid cable. The duct thus forms a hollow cylinder which has a complete lengthwise split. While the Sack patent is unconnected to air ducts, the principle of axial splitting, as opposed to splitting in a perpendicular direction is demonstrated as an economic method of providing access to the inside of a conduit. 
     OBJECTS OF THE INVENTION 
     It is therefore one of the objects of the present invention to obviate the disadvantages of prior art gas duct damper housings and to provide a housing split lengthwise, parallel to its axis, which housing can be manufactured without including high die costs. 
     It is a further object of the present invention to provide a housing which can form a compact package before assembly, and which can be easily and quickly assembled on site without the use of tools. 
     SUMMARY OF THE INVENTION 
     The present invention achieves the above objects by providing a plastic damper housing for a gas duct particularly useful in air conditioning systems, said housing providing support bearings for damper plate hinge shafts, and comprising an assembly of two identical moldings each shaped substantially as an open-ended half hollow cylinder, each half hollow cylinder being provided along a first axial edge with at least one male interconnection element and on a second opposite edge with at least one corresponding female interconnection element. 
     In a preferred embodiment of the present invention there is provided a plastic damper housing wherein each said half hollow cylinder is further provided with a guide and retention element for supporting therein a base-plate of an actuating device. 
     In a most preferred embodiment of the present invention there is provided a motor-powered gas damper for use in combination with an air-conditioning system, said damper being located inside a split plastic damper housing as described above. 
     Yet further embodiments of the invention will be described hereinafter. 
     It is well known that in plastic molding, dies to manufacture large components become more expensive than similar dies for a small component, the cost increase and weight increase of the die being more than proportional to size of the molding to be produced therefrom. This results from the need to increase all three dimensions of the die to mold the larger component. 
     The economics of tooling is also dependent on the number of items to be processed. Thus with regard to plastic castings, a larger number of smaller moldings is far preferable to a smaller number of larger moldings. 
     By careful design, and by retaining symmetry about the half-length of the component, it has been found possible to produce a half-housing, including rail supports for an electric drive unit, that can be assembled to an identical half-housing when rotated 180 degrees relative to the first unit. This has been achieved even for embodiments provided with a motor support rail on one side. 
     During storage and transport to the installation site the two half-housings nest together and form a reasonably compact package. 
     Interconnection of the two half-housings, including the damper element held therebetween can be effected on site without the use of any tool. Time required is about 20 seconds. 
    
    
     DESCRIPTION OF DRAWINGS 
     The invention will now be described further with reference to the accompanying drawings, which represent by example preferred embodiments of the invention. Structural details are shown only as far as necessary for a fundamental understanding thereof. The described examples, together with the drawings, will make apparent to those skilled in the art how further forms of the invention may be realized. 
     In the Drawings: 
     FIG. 1 is a perspective view of a preferred embodiment of the housing according to the invention, shown before final assembly; 
     FIG. 2 is a perspective view of a similar housing, provided with multiple interconnection elements; 
     FIG. 3 is a detail view of a joint between the two half-housings which resists inadvertent disassembly; 
     FIG. 4 is a perspective view of an assembled embodiment provided with motor support rails; 
       
     FIG. 5 is a perspective view of a motor-powered gas damper, the motor being shown not yet inserted in its rails; and 
     FIG. 6 is a perspective view of the housing with a manual actuator. 
    
    
     FULL DISCLOSURE OF INVENTION 
     There is seen in FIG. 1 a plastic damper housing  10  for a gas duct which is particularly useful in air conditioning systems. 
     The housing  10  provides support bearings  12  for the ends of the damper plate  14  hinge shaft  16 . Bearings  12  allow tilting the damper plate  14  from fully closed as shown, to fully open when the damper plate is horizontal. 
     The housing  10  comprises an assembly of two identical plastic moldings each shaped substantially as an open-ended half hollow cylinder  18 . Each half hollow cylinder  18  supports along a first axial edge  20  a male interconnection element  22 . The second opposite edge  24  has a corresponding female interconnection element  26 . The half-cylinder  18  in the present embodiment, and all further embodiments, is symmetrical in so far as it can be rotated 180 degrees about a vertical central axis after which the interconnection elements  22 ,  26  are again suitably oriented for assembly of the two halves  18 . 
     Before assembly, and for purposes of storage and transport, the half hollow cylinders  18  can be stacked one substantially inside the other to make a compact package. 
     The two halves  18  are assembled simply by resting the damper plate  14  in the lower half  18  with its hinge shaft  16  being revolvably supported in the bearings  12 . The two cylinder halves  18  can then be pressed together. 
     In the present embodiment the damper plate may be hand operated by connecting an appropriate mechanism to the shaft head  28 . 
     With reference to the rest of the figures, similar reference numerals have been used to identify similar parts. 
     Referring now to FIG. 2, there is seen a plastic damper housing  30  similar to  10  seen in FIG.  1 . However each axial edge  32 ,  34  of the half hollow cylinder  36  is provided with two pairs of in-line male  40  and female  42  interconnection elements separated by half of bearing  12  for the damper plate hinge shaft  16 . Thus each axial edge  32 ,  34  carries four interconnection elements  40 ,  42 , only two of which are visible in the figure. 
     A male element  40  is proximate to a first end  43  of the half hollow cylinder  36  on a first axial edge  32 . A female element  42  on the second opposite axial edge  34  is also proximate to end  42 . The interconnecting elements  40 ,  42  are positioned to maintain the symmetry stated with regard to FIG.  1 . Thus on assembly a total of eight male/female element pairs interconnect to form the complete housing  30 , 
     FIG. 3 illustrates a detail of interconnecting elements  44 ,  46 . The plastic damper half-housing  48  carries at least one male interconnection element  44  wherein the outer extremity thereof  50  has a step projection  52 . 
     The corresponding female interconnection element  46  is provided with a side aperture  56  allowing the step projection  52  to snap therein on assembly for producing a housing  54  secured against inadvertent disassembly. 
     Seen in FIG. 4 is a plastic damper housing  58  suitable for supporting an electric motor ( 66  seen in FIG.  5 ). 
     Each half hollow cylinder  60  is provided with a guide and retention element  62  which forms one of two supporting rails for the base-plate  68  of the motor. 
     At first sight it would appear that two dies (left hand, right hand) would be required to make the upper and lower half cylinder. However due to symmetry a pair of identical half-cylinder moldings  60  emanating from a single die can be and are used to form the housing  58 . 
     Referring now to FIG. 5, there is depicted a motor-powered gas damper  70  for use in combination with an air-conditioning system. For illustrative purposes the motor  66  is shown adjacent to but not yet inserted into retention element  62 . The motor includes a speed reducer (not seen). A projecting drive tongue  72  will engage the damper shaft head  28  when the motor  66  is in its intended position. 
     The gas damper housing is the split housing  58  seen in FIG.  4 . 
     FIG. 6 illustrates a further embodiment where on base-plate  68  Mere is mounted a manual mechanism  74  which is operated by knob  76 . The turning of knob  76  clockwise or anti-clockwise pivots damper plate  14 . 
     The scope of the described invention is intended to include all embodiments coming within the meaning of the following claims. The foregoing examples illustrate useful forms of the invention, but are not to be considered as limiting its scope, as those skilled in the art will readily be aware that additional variants and modifications of the invention can be formulated without departing from the meaning of the following claims.