Abstract:
A pilot assembly includes a two part pilot housing and an orifice member mounted between the two housing parts. One housing part is fixable to a mount in a gas burning device and has a through passage. The orifice member is received in the passage. At least a portion of the other housing part is received in the passage to fix the orifice member in the passage.

Description:
This application is a Continuation of Ser. No. 09/244,301 filed Feb. 3, 1999, now U.S. Pat. No. 6,027,335. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to pilot assemblies, and, more particularly to pilot assemblies of the type having a changeable pilot orifice member. 
     BACKGROUND OF THE INVENTION 
     Gaseous fuel (hereafter for simplicity, gas) burning devices, such as conventional hot water heaters and gas fireplaces, typically burn natural gas or propane. Pilot assemblies are conventionally mounted in, and used to light, such gas burning devices. A conventional pilot assembly includes a pilot which continuously burns gas at a low rate to provide a pilot flame. The pilot flame in turn lights an adjacent main burner when gas is supplied to the main burner. 
     As a convenient example of a conventional environment for such a pilot assembly, a conventional gas fireplace GF (FIG. 7) includes a floor  8 , a fireplace box  9  extending upwardly from the floor  8 , and conventional fireplace hardware  10  mounted in the fireplace box  9 . The box  9  encloses sufficient volume for the fireplace hardware  10  and fireplace flames. The fireplace hardware  10  includes a grate  11  (in broken lines) standing on the floor  8 , imitation noncombustible logs  12  (in broken lines) resting on the grate  11 , a main burner  13  mounted to the floor  8  in substantially hidden relation behind the grate  11  and logs  12 , and a pilot assembly  15 . The main burner has plural gas flame producing nozzles  14 , some adjacent the pilot assembly  15 . 
     A typical conventional pilot assembly  15  (FIG. 8) includes a horizontal mounting bracket  17  fixed by any conventional means, not shown, with respect to the main burner  13 . The pilot assembly  15  is substantially hidden behind the main burner  13 . The assembly  15  includes a pilot  19 , an ignitor  21 , a thermocouple  22 , and a thermopile generator  23 , which are fixed on, and extend vertically through, the mounting bracket  17  in side-by-side relation. 
     The pilot  19  (FIG. 8) includes a one piece housing  27  extending vertically through and fixed to the central portion of the bracket  17 . A semirigid, metal, gas supply tube  28  connects the bottom of the pilot housing  27  through a conventional pilot valve V to a conventional gas source GS. A typical pilot valve V is spring biased closed (to block gas flow to the pilot  19 ), but can be opened manually and can be held open electrically (to allow gas flow to the pilot). FIG. 8 schematically shows a suitable conventional pilot valve V comprising a spring biased closed valve core C 1  interposed between the gas source GS and pilot supply tube  28 , and a manual opener (e.g. push button) B 1  and electromagnetic hold-open (e.g. solenoid) E 1  actuable to respectively open and hold-open the valve core C 1  against its spring S 1 . 
     The upper end of the pilot housing  27  normally emits a pilot flame (not shown) fueled by gas supplied through the open valve V and tube  28 . A pilot flame target  31  is fixed atop the housing  27  to direct the pilot flame laterally (to the right and left and forward out to the page in FIG. 8) along paths from the target  31 . The top of the ignitor  21  (FIG. 8) is adjacent one side (the left side in FIG. 8) of the target  31 , for igniting gas flow therefrom to establish the pilot flame of pilot  19 . The tops of the thermocouple  22  and thermopile generator  23  closely flank the target  31  (FIG.  8 ), so as to be in the pilot flame path from opposite sides of the target  31  and with the ignitor  21  snugly spaced between the thermocouple  22  and target  31 . The front of the flame target  31  is adjacent ones of the gas outlet nozzles of the main burner  13 , such that the forward directed flame pilot flame component ignites the main burner  13 . 
     An electrically insulated wire  24  (FIG. 8) electrically couples the bottom of the ignitor  21  to the output of a conventional ignitor voltage source, here for example a conventional, manually actuable, push button, piezo-electric voltage source PZ, grounded to the bracket  17 . Given a supply of gas through the pilot valve V to the pilot  19 , manual actuation of the piezo voltage source discharges an electrical spark between the tops of the ignitor  21  and pilot  19 , thereby igniting the pilot gas flow and starting the pilot flame. 
     A relatively stiff wire  25  extends from the bottom of the thermocouple  22  to the control input of the electromagnetic hold-open E 1  of pilot valve V. The thermocouple  22 , when heated by the pilot flame from pilot  19 , supplies a voltage (typically in the range of millivolts) to the solenoid E 1  to maintain the valve V open and so maintain gas flow to the pilot and keep the pilot flame on. If the pilot flame becomes extinguished, the thermocouple  22  cools, its voltage output drops, and the solenoid E 1  relaxes and the spring S 1  closes the valve V and shuts off gas flow to the pilot  19 . 
     The bottom of thermopile generator  23  (FIG. 8) connects through a heat shielded, relatively stiff, electrically insulated wire pair  26  to a main gas safety valve MV interposed between the conventional gas source GS and the main burner  13 . The thermopile generator  23  responds to pilot flame heat to electrically open the main valve MV to supply gas from the gas source GS to the main burner  13  and responds to lack of pilot flame heat to close the valve Mv and thus shut off gas flow to the main burner  13 . The main safety valve MV may be a conventional solenoid valve (like pilot V but without the manual opener B 1 ) comprising a valve core C 2  spring biased closed by a spring S 2  and openable by a solenoid E 2 . 
     Typically, a manual control MC, in the form of a manually adjustable valve, is in series with the main safety valve MV, between the gas source GS and main burner MB, to allow the human operator of the fireplace GF to turn on and off, and vary the flame height of, the main burner MB. 
     The top and bottom ends of the one-piece pilot housing  27  (FIG. 9) are spaced above and below the bracket  17 . The housing  27  has a radially inwardly stepped, upper housing portion  45 . The housing  27  also has a stepped axial through passage  29 . The passage  29  has a substantially cylindrical top portion  42 , an enlarged-diameter midportion  43  and a further enlarged-diameter, bottom opening, internally threaded recess  44 . The portions  42  and  43  are separated by a tapered annular step  46 . The midportion  43  and recess  44  are separated by an annular step  47 , the upper portion of which is tapered upward and inward. The open top  48  of the passage  29  acts as the ignited gas/air mixture (flame) outlet nozzle of the pilot  19 . 
     The pilot flame target  31  comprises a semi-circular base  38  which is fixed, by any convenient means, such as welding, to the upper housing portion  45 . The target  31  has an inverted trough-like, pilot flame deflector  39  fixedly upstanding from the base  38  and spaced above the pilot flame nozzle  48  for deflecting the pilot flame laterally (to the left and right in FIG. 9) toward the ignitor  21 , thermocouple  22  and thermopile generator  23  and forwardly (out of the page in FIG. 9) toward the main burner  13 . 
     At least one air supply aperture  32  opens radially through the peripheral wall of the housing  27  and into the midportion  43  of the passage  29 . The aperture  32  may be above the bracket  17  as here shown, or below it. 
     An inverted cup-shaped, pilot orifice-containing member  33  includes a substantially cylindrical peripheral wall  35 , a horizontal top end wall  36 , a central orifice  34  preferably centered in the end wall  36 , and a radially outwardly and downwardly flared bottom flange  40 . The orifice member  33  is assembled in the pilot housing  27  by upward insertion through the threaded bottom recess  44 . When so installed, as seen in FIG. 9, the top end wall  36 , with its orifice  34 , is located closely below the air aperture  32 , the peripheral wall  35  is in snug sliding engagement with the lower portion of the passage midportion  43 , and the bottom flange  40  snugly abuts the tapered step  47 . 
     The pilot gas supply tube  28  has an upper end fixedly tipped by a ferrule  37  (FIG. 9) that is tapered at its upper and lower ends  51  and  52 . 
     A spool-like, annular fitting  41  (FIG. 9) is snugly but axially and rotatably slidably sleeved on the gas supply conduit  28  below the ferrule  37 . The fitting  41  adjacent its lower end has a wrench-engageable (here hexagonal) rim  53 . The fitting  41  is externally threaded at  54  adjacent its upper end and has a central throughbore  55 . The upper end of the fitting throughbore  55  is tapered at  56 . The gas supply tube  28  is fixed to the bottom of the housing  27  by inserting the ferrule  37  into the housing bottom recess  44  until it rests against the tapered bottom flange  40  of the orifice member  33 . The fitting  41  is then threaded into the threaded bottom recess  44  of the housing  27 . Threadedly tightening the fitting  41  axially presses it, fitting taper  56  to ferrule taper  52 , against the bottom of the ferrule  37  and in turn presses the ferrule  37  axially upward so that its upper taper  51  forcibly presses the bottom flange  40  against the tapered step  47  of the housing  27 . This locks in place the orifice member  33  in the housing  27  and prevents leakage of gas, such that all gas from the gas supply tube  28  must pass up through the orifice  34  and mix with air from the aperture  32 , and such that the resultant gas/air mixture must pass upwardly through the passage top portion  42  and out the nozzle  48  for ignition and production of the pilot flame. 
     However, different fuel gases differ in energy content and so require different sized orifices  34  to supply gas at different flow rates for maintaining the desired size pilot flame. Manufacturers, retailers, and repair persons must thus inventory different pilot assemblies  15  (FIG. 8) for different gaseous fuels, or must change the orifice member  33  (FIG. 9) in a given assembly if a different fuel gas than originally contemplated is to be used. Unfortunately, inventorying different pilot assemblies  15 , and more importantly appliances incorporating them, is space consuming and expensive. 
     Also, unfortunately, in such prior pilot assemblies  15  (FIG.  8 ), changing the orifice member  33  (FIG. 9) is difficult and time consuming because access to the orifice member  33  is difficult before, and particularly after, prior pilot assembly  15  is installed in a gas burning device, for example a fireplace or water heater. More particularly, to remove the existing pilot orifice member  33 , the fitting  41  and gas supply tube  28  must be removed from the bottom of the pilot  19 . However, access to the fitting  41  is usually, at least partially, blocked, e.g. by the bracket  17  and main burner  13 , if not additionally by user device structure, such as the nonflammable logs  12 , grate  11  or a fireplace box  9  (FIG.  7 ). Further, the stiffness of the gas supply tube  28  requires either that it be bent (thus risking kinking and disabling) away from the pilot  19 , or that the bracket  17  be disconnected from supporting structure of a user device and that the relatively stiff electrical conductor members  25 ,  26  also be disconnected to enable access to the bottom of the pilot  19 . 
     Accordingly, objects of the present invention include providing a pilot assembly having more efficient access to the pilot orifice member, and easing converting the pilot from one gaseous fuel to another. 
     SUMMARY OF THE INVENTION 
     The objects and purposes of the present invention, including those set forth above, are met, according to one form of the present invention, by providing a pilot assembly which includes two pilot housing parts, and a pilot orifice member mounted between the two pilot housing parts. One pilot housing part is fixed to a gas supply. The second pilot housing part is removably fixed to the one pilot housing part. In another embodiment of the present invention, the pilot orifice member is accessible from above a bracket by removing an upper housing part upwardly from a cover housing part. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings, 
     FIG. 1 is an elevational view of a pilot assembly embodying the invention; 
     FIG. 2 is a cross sectional view of the pilot of FIG. 1; 
     FIG. 3 is a cross sectional view of the lower housing member of the pilot of FIG. 2; 
     FIG. 4 is a cross sectional view of the upper housing member of the pilot of FIG. 2; 
     FIG. 5 is an elevational view of a modified pilot assembly embodying the invention; 
     FIG. 6 is a cross sectional view of the pilot of FIG. 5; 
     FIG. 7 is a front view of a typical conventional fireplace, equipped with a prior art pilot assembly, and with the fireplace box, grate, and nonflammable logs shown in broken line; 
     FIG. 8 is a front view of the prior art pilot assembly of FIG. 7; 
     FIG. 9 is a cross sectional view of the prior art pilot of FIG. 8; and 
     FIG. 10 is a cross sectional view of the housing of the FIG. 9 pilot. 
    
    
     Certain terminology will be used in the following description for convenience in reference only and will not be limiting unless explicitly recited in the claims. The words “up”, “down”, “top”, “bottom” will designate directions in the drawings to which reference is made. Such terminology will include derivatives and words of similar meaning. 
     DETAILED DESCRIPTION 
     FIGS. 1-4 disclose a pilot assembly  49  embodying the present invention. While the present invention may be embodied in other structures, for convenience in present disclosure the pilot assembly  49  of FIGS. 1-4 is described below as an improvement on, and hence modification of, the prior art pilot assembly  15  above discussed as to FIGS. 7-10. Thus, for convenient reference, parts of the inventive pilot assembly  49  (FIGS. 1-4) substantially corresponding to parts of the prior art pilot assembly  15  will be referred to by the same reference numerals, with the suffix “A” added. Thus, the FIGS. 1-4 pilot assembly may be similar to that shown in FIGS. 7-10 except as follows. 
     The inventive pilot assembly  49  (FIG. 1) includes an improved pilot  50 . The pilot  50  (FIG. 2) includes a two-part housing  64  comprising a substantially tubular upper housing member  66  and a substantially tubular lower housing member  68 . 
     The lower housing member  68  (FIGS. 2 and 3) comprises an elongate, generally cylindrical peripheral wall  71  whose exterior surface  72  is radially inwardly stepped at  73  to narrow the upper end portion  79 . The step  73  seats against the bottom of the mounting bracket  17 A. The lower housing member upper end portion  79  is fixed to the mounting bracket  17 A by any conventional means, for example staking, welding, etc. The major length of the lower housing member  68  depends downwardly from the mounting bracket  17 A and ends at  81 . A diametral, preferably integral wall  76  divides the lower housing passage  74  into upper and lower internally threaded, recesses  77 ,  78 . The diametral wall  76  includes a coaxial boss  97  protruding upwardly into the upper recess  77 . An annular gap  96  radially spaces the boss  97  from the interior surface of the peripheral wall  71 . The boss  97  has an upwardly inwardly tapered peripheral wall  98 . The diametral wall  76  is axially perforated by a reduced diameter gas flow hole  94  coaxially connecting the greater diameter upper and lower recesses  77 ,  78 . 
     The lower recess  78  (FIG. 3) is stepped radially outward and downward. Starting downward from the diametral wall  76 , the lower recess  78  includes an inner, downward flared, tapered step  80 ; an increased diameter, cylindrical wall  83 ; an outer tapered step  84 ; and an internally threaded, substantially cylindrical mouth  82 . 
     The ferrule  37 A (FIG.  2 ), gas supply tube  28 A and fitting  41 A are all received in the mouth  82  of lower recess  78 . Tightly threading the fitting  41 A into the threaded mouth  82  gas sealingly seats the ferrule upper tapered surface  51 A against the tapered step  84 . 
     The upper housing member  66  (FIGS. 2 and 4) comprises an elongate, hollow, generally tubular wall  105  having upper and lower end portions  107  and  108 , axially flanking a midportion  106 . The midportion  106  has a wrench engageable (e.g. hexagonal) outer surface. The lower end portion  108  is externally threaded at  111 . The upper and lower end portions  107 ,  108  are stepped radially inward from the periphery of the midportion  106 . The upper housing member  66  includes a coaxially extending through passageway  113  having a downward facing, tapered annular midstep  115  and a convexly radiused bottom step  116 . An air supply aperture  117  opens radially through the peripheral portion of the upper housing member  66  just below the midstep  115  and above the lower end portion  108 . 
     The pilot  50  (FIG. 2) is assembled as follows. The lower housing member  68  is inserted upwardly snugly into a hole  124  in bracket  17 A until the stop  73  abuts the underside of the bracket. The member  68  is fixed pendently to the bracket  17 A by any convenient means (e.g. peening, welding, etc.). 
     The gas supply tube  28 A, ferrule  37 A and fitting  41 A are then upwardly inserted in the lower recess  78 . Threadedly tightening the fitting  41 A in the threaded mount  82  sealingly wedges the tapered upper end  51 A of the ferrule  37 A against the tapered step  84  of the lower housing member  68 . 
     Then, the orifice member  33 A is centered in the upper recess  77  of the lower housing member  68  with its flared lip  101  coaxially fitted on the tapered peripheral wall  98  of the boss  97 . 
     Then, the upper housing member  66  is sleeved over the orifice member  33 A and threaded into the upper recess  77  of the lower housing member  68  until the lip  101  is tightly and sealingly sandwiched between the tapered wall  98  of the lower housing member  68  and the tapered bottom step  116  of the upper housing member  66 . The tapers of the wall  98 , step  116  and lip  101  are substantially equal to provide a circumferentially complete axially extended gas seal therebetween. 
     To convert the pilot  50  to a different fuel gas, the upper housing member  66  and orifice member  33 A are upwardly removed from the lower housing member  68 , a new orifice member  33 A of different, suitable orifice  34 A diameter is inserted and the upper housing member  66  is replaced on the lower housing member  68 . Advantageously, this can be done from entirely above the bracket  17 A and there is no need of access below the bracket  17 A or removal of the gas supply tube  28 A (or electrical members  24 ,  25  or  26 ) or dismantling of bracket  17 A or adjacent user structure (e.g. FIG. 7 fireplace structure). 
     MODIFICATION 
     A typical modified inventive pilot assembly  150  (FIGS. 5 and 6) may be used in water heaters. For convenient reference parts of the pilot assembly  150  substantially corresponding to parts of the pilot assembly  49  of FIG. 1 will be referred to by the same reference numerals with the suffix “B” added. The FIGS. 5 and 6 pilot assembly is preferably similar to that of FIGS. 1-4 except as follows. 
     The modified pilot assembly  150  (FIGS. 5 and 6) includes a bracket  17 B, which fixedly mounts an ignitor  21 B and a pilot  152 . 
     The pilot  152  has a lower housing member  68 B (FIG. 6) fixed to and depending from the bracket  17 B. The lower body member  68 B differs from the member  68  (FIG. 3) primarily in that its peripheral wall  71 B is longer, axially between the threads  77 B and the boss  97 B, than the peripheral wall  71 . 
     The pilot  152  includes an upper housing member  154 . 
     The upper housing member  154  (FIG. 6) has an elongate, generally tubular peripheral wall  155  having upper and lower end portions  157  and  159  flanking a midportion  160 . The upper end portion  157  has a wrench engageable (e.g. hexagonal) outer surface portion  156 . The midportion  160  has a threaded outer surface  158 . The member  154  has a coaxial through passage  163 . The passage  163  is generally of hour glass shape and includes an upper, enlarged diameter, target receiving recess  164 , a lower, enlarged diameter recess  166 , and a reduced diameter intermediate portion  167  connected by tapered steps  165  and  169  to the upper and lower recesses  164  and  166 . The lower recess  166  has a downward facing, tapered step  168  at its lower end. 
     An inverted, cup shaped orifice member  170  includes a top end wall  172 , a stepped peripheral wall  174  depending from end wall  172 , and a stepped flared skirt  179  depending from the peripheral wall  174 . The top end wall includes a central orifice  173 . The peripheral wall  174  includes an upper wall portion  176 , which has a diameter less than the intermediate passage portion  167  and extends downwardly partly into the intermediate passage portion  167 , and a lower wall portion  178  of diameter slightly greater than the upper wall portion  176 . The skirt  179 , in descending order, includes an upper, downward facing, frustoconical step  181 , an upper cylindrical part  183 , a lower, downward facing frustoconical step  184 , and a lower cylindrical part  186 . 
     A bidirectional target  190  (FIG. 6) includes a semicylindrical mounting base  191 . The base  191  is fixed in the target receiving recess  164  by any conventional means, for example by welding. 
     The pilot  152  is preferably assembled as follows. First, the gas supply tube  28 B, ferrule  37 B, lower housing member  68 B and bracket  17 B may be assembled together in the manner shown in FIG.  6  and generally as discussed above with respect to corresponding elements  28 A,  37 A,  68  and  17 A of FIGS. 1 through 4. 
     Then, the orifice member  170  (FIG. 6) is centered in the upper recess  77 B of the lower housing member  68 B with its tapered stop  168  coaxially fitted on the tapered peripheral wall  98 B of the boss  97 B. 
     Then, the upper housing member  154  is sleeved over the orifice member  170  and threaded into the upper recess  77 B of the lower housing member  68 B until it stops. As a result, the upper housing member snugly radially backs the orifice member lower peripheral wall portion  178 . Also, the boss tapered peripheral wall  98 B and opposed upper housing member tapered step  168  tightly and sealingly sandwich the orifice member lower frustoconical part  184  (such elements  98 B,  168  and  184  having substantially identical tapers to facilitate sealing). Further, the orifice member upper peripheral wall portion  176  extends loosely up into the target mounting base  191 , ending just above the top of the upper housing member  154 . 
     Thus, gas exits the orifice  173  directly into the target  190  (not into the housing as in the FIG. 1-4 embodiment), whereat the gas ignites into the pilot flame. 
     Advantageously, the pilot assembly  50 ,  150  allows removal and replacement of the orifice member  33 A,  170  from above the mounting bracket  17 A,  17 B by providing a two part pilot, in which the upper housing member  66 ,  154  can be respectively removed from above the mounting bracket  17 A,  17 B to allow replacement of the orifice member  33 A,  170  from above. 
     Although particular preferred embodiments of the invention have been disclosed in detail for illustrative purposes, it will be understood that variations and modifications of the disclosed apparatus, including the rearrangement of parts, lie within the scope of the present invention.