Abstract:
A thermocouple mounting assembly is provided. A plurality of retainers includes portions that are interengageable, some portions carried by a body and some portions carried by a thermocouple assembly to effect releasable mounting of a thermocouple assembly to a body. The retainers are constructed and shaped to provide for their formation by a molding process such as die-casting or investment casting, eliminating or substantially eliminating the need for machining of the retainer components. Preferably, there is an audible sound, e.g., click, present to signify when the retainers are interengaged.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     Thermocouple mounting devices are well known in the industry. One common type of mounting device is a bayonet mount. This type of mounting device utilizes a cap with one or more L-shaped slots. The cap is mounted to the thermocouple. The cap is received over an end of a shank, which has at least one radially outwardly extending pin that is received within the L-shaped slot. The shank is generally mounted to an object that is to monitor temperature. Spring tension is applied to maintain that the cap and the shank are interlocked. A second type of connection is a screw in device, that is simply a threaded shank which includes the thermocouple extend therethrough. The shank is threadably received in a threaded receptacle or well. Wrench flats may be provided at one end of the shank for use of a wrench to position the thermocouple in connection with a contact surface found in the receptacle.  
         [0002]     A third type of thermocouple mounting device can be found in U.S. Pat. No. 6,010,327 which issued to Katchka on Jan. 4, 2000, that shows a push-in snap securement device that has radially projecting fingers interengageable with a shoulder inside a receptacle. A spring is provided to maintain contact between a portion of the thermocouple and an electrical contact. In this case, the thermocouple sensor end is at the opposite end of the electrical contact end of the thermocouple assembly.  
         [0003]     While generally effective, such known thermocouple mounts have significant drawbacks. They require a combination of various parts which increase costs and necessitates additional labor to make an assembly or to effect mounting of the thermocouple. Thermocouple mounts also, at times, requires a certain level of dimensional precision in order to ensure proper operation which can also increase costs, both for the product itself and the additional labor to effect proper assembly and testing to ensure proper operation.  
         [0004]     When used with fuel control units, for example, the female receptacle is complex and expensive to manufacture as disclosed in U.S. Pat. No. 6,010,327. Fuel control units are used to control the flow of fuel to burners, e.g., those found in gas water heaters and furnaces. Usually, such receptacles are made of relatively soft material and are easily damaged by cross threading, a tightening tool, dropping, and the like. While the push in-type thermocouple coupling device disclosed in U.S. Pat. No. 6,010,327 is effective, it is relatively expensive and difficult to affect a repair of the thermocouple system. Screw in-type thermocouple mounts may also be damaged on the wrench flats during installation and are at times difficult to loosen which may also damage the shank particularly when the shank is made of a soft material. However, screw in-type shanks reduce the probability of accidental dislodgement of the thermocouple mounts from its desired monitoring position. When the thermocouple mounts extend out of the bottom of the unit when installed, repair is difficult because of the upside down orientation. Machining of a thermocouple retainer such as that shown in U.S. Pat. No. 6,010,327 is complex and expensive.  
         [0005]     There is a need for a reliable thermocouple mounting device that is less complex to manufacture and utilize. The present invention is directed to overcoming one or more of the problems set forth above.  
       SUMMARY OF INVENTION  
       [0006]     A thermocouple mounting assembly is provided. The mounting assembly includes a first retainer for mounting to a body such as a fuel control unit. The first retainer has an internal chamber and first and second ends with openings therein. The first end opening provides access to the chamber to provide exposure for a thermocouple portion to contact or be positioned adjacent to a member for operation of the thermocouple control system. A second end opening provides access to the chamber for a second retainer to extend through and to releasably secure a thermocouple portion within the chamber. The interior of the chamber contains a securement device to cooperatively interengage with a second securement device on the second retainer to form a bayonet mounting arrangement between the first and second retainers with the interengaging portions being shielded from external contact. The bayonet mounting arrangement releasably secures a thermocouple portion within the chamber. The bayonet mounting arrangement is constructed to prevent accidental disengagement of the second retainer from the first retainer. Preferably the mounting assembly and retainer components are molded and not machined to significantly reduce manufacturing costs.  
         [0007]     These are merely some of the innumerable aspects of the present invention and should not be deemed an all-inclusive listing of the innumerable aspects associated with the present invention. These and other aspects will become apparent to those skilled in the art in light of the following disclosure and accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0008]     For a better understanding of the present invention, reference may be made to the accompanying drawings in which:  
         [0009]      FIG. 1  is a fragmentary side elevation view of a fuel control unit with portions broken away to show details of portions of the internal construction;  
         [0010]      FIG. 2  is an enlarged perspective view of one retainer of a thermocouple mounting assembly;  
         [0011]      FIG. 3  is a fragmentary perspective view of the retainer of  FIG. 2  with portions broken away to show internal structure;  
         [0012]      FIG. 4  is a perspective view of the thermocouple mounting assembly with portions broken away to show internal details of the mounting assembly and portions of the fuel control unit shown in  FIG. 1 ;  
         [0013]      FIG. 5  is an enlarged fragmentary perspective view of a second retainer and portion of a thermocouple;  
         [0014]      FIG. 6  is a schematic of a thermocouple control system; and  
         [0015]      FIG. 7  is a perspective view of a fuel control unit with portions broken away to show internal details. 
     
    
       [0016]     Like numerals throughout the various figures designate the same or similar parts.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0017]     In the following detailed description, numerous specific aspects are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures and components have not been described in detail so as to obscure the present invention.  
         [0018]     A thermocouple mounting assembly that is adapted for mounting to a body  3  is generally indicated by numeral  1 . The mounting assembly  1  includes retainers indicated by numerals  5  and  6 . The thermocouple assembly  7  is adapted to be mounted to the body  3  by interengagement of portions of the retainers  5  and  6  forming a shielded bayonet mounting arrangement. The thermocouple mounting assembly  1 , including retainer  5  and/or retainer  6 , is preferably molded. This can include any of a wide variety of metal molding processes, including but is not limited to, die casting and investment casting.  
         [0019]     The body  3  can be any suitable device which needs to be coupled with a thermocouple assembly  7  for either sensing of the temperature of a portion thereof or to provide an output signal or current from the thermocouple assembly  7 . In the illustrated embodiment, the body  3  is part of a fuel control unit designated generally  9 . A suitable fuel control unit is disclosed in U.S. Pat. No. 6,010,327, the disclosure of which is incorporated herein by reference. The illustrated fuel control unit  9  includes a housing  10  with an inlet port  11  for selectively providing a feed of fuel preferably of a hydrocarbon type such as natural gas, fuel oil or the like to an outlet port  14  and on to a downstream device such as a burner with a pilot. A valve mechanism  13  in the body  3  is operable, upon command, to selectively allow fuel to flow through the outlet  14  (indicated in two (2) places) and then onto a burner or the like. The valve mechanism  13  is biased to a normally closed position and may be manually opened by a push down to start mechanism, designated generally by numeral  16 , as are known in the art. A resilient member such a coil spring  17  may be used to bias the valve mechanism  13  to its normally closed position.  
         [0020]     A suitable mechanism, designated generally by numeral  19 , is provided to move the valve mechanism  13 , upon suitable command, to an open position and to release the valve mechanism  13  to return to its normally closed position also upon command. In the illustrated structure, the suitable mechanism  19  includes an electromagnet  20  selectively powered by a coil  21 . The coil  21  is powered by the thermocouple assembly  7  when enough heat or temperature is sensed or received by a thermocouple sensing end  22  for the thermocouple assembly  7 , which will generate enough current to power the coil  21  to move the valve mechanism  13  to its open position.  
         [0021]     When the output of the thermocouple sensing end  22 , which includes a bimetallic joint in a protective housing  25 , is insufficient to power the coil  21  sufficiently, the coil spring  17  overcomes the magnetic attraction force induced by the coil  21  allowing the valve mechanism  13  to move its closed position. In the illustrated structure, the thermocouple assembly  7 , includes a contact end  23 , which is in electrical contact with a contact assembly  24  which provides a circuit to the electromagnet  20  only if, for example, the water in a water heater is not hot enough as determined by a set point on a thermostat. The thermocouple assembly  7 , in the case of use on a fuel control unit, is part of a safety circuit that must be activated to indicate that the pilot light  60 , as shown in  FIG. 6 , is lit before the valve mechanism  13  can open allowing fuel to flow to the burner.  
         [0022]     In a preferred embodiment, the retainer  5  is adapted for removable mounting to the body  3 . However, it is to be understood that the retainer  5  could be an integral part of the body  3 . In the illustrated embodiment, as seen in  FIGS. 2, 3 , the retainer  5  has a sidewall  27 , an end wall  28  and an open end  29  that is opposite of the end wall  28 . The retainer  5  includes an internal chamber  30  that opens on the open end  29  and is partially defined by an interior surface  31  of the sidewall  27 . The end wall  28  has a through opening  32  for receipt of a portion of the thermocouple assembly  7  therethrough.  
         [0023]     A means is provided for cooperative interengagement to releasably secure the retainer  6  and a portion of the thermocouple assembly  7  within the retainer  5 , as more fully described below. In a preferred embodiment, the through opening  32  has a generally cylindrical portion  33  and at least one and preferably two side projecting portions  34 . On the inside surface of the end wall  28 , there is provided at least one and preferably two cams  35  that includes a level end surface portion  36 , i.e., generally normal to a plane transversely through the longitudinal axis of the internal chamber  30  and adjacent to a respective two side projecting portion  34 , as well as projecting inwardly from the sidewall  27 . The cam  35  also includes an inclined portion  39  which inclines in a direction generally from the end wall  28  toward the open end  29  and projects inwardly from the sidewall  27 . An ear stop  37  is associated with at least one of the cams  35  to limit the rotation of the retainer  6  in the retainer  5  by interengagement between portions thereof as later described. The side surfaces defining the internal chamber  30  are all characterized by having an absence of a component facing generally toward the end wall  28 , i.e., generally parallel to the longitudinal axis of the internal chamber  30  or outwardly flaring. That is, the interior surface  31  would be either cylindrical or flaring outwardly toward the open end  29  but not inwardly for the extraction of a mold plug utilized in a preferred method of formation of the retainer  5 . Preferably, there are no undercuts or other surface defining elements that would have any substantial portion facing toward the end wall  28  which would lock a mold plug to the retainer  5 .  
         [0024]     The end wall  28  or inclined portion  39  of sidewall  27  is preferably provided with a tool engaging portion to assist in attaching the retainer  5  to the body  3 . In the illustrated embodiment, spanner wrench pin recesses  40  are located in the end wall  28 . The inclined portion  39  may be threaded as indicated at numeral  41  for threaded engagement with an interior threaded matching surface  43  forming a well  42 . The spanner wrench pin recesses  40  and sidewall  27  are designed so as to provide the ability to form the retainer  5  by molding. A preferred material for the retainer  5  is an aluminum or magnesium alloy. Preferably, the material of the body  3  and the retainer  5  are compatible to prevent galvanic currents from being generated and resulting corrosion at the threaded connection of thread engagement  41  and the interior threaded matching surface  43 , as shown in  FIGS. 1, 2  and  3 .  
         [0025]     Referring now to  FIGS. 1, 4  and  5 , the retainer  6  includes a shank  44  that preferably has a generally cylindrical portion  45  with an end face  46 . A resilient member  47 , e.g., coil spring, can be mounted on a tubular portion  48  of thermocouple assembly  7  for a purpose to be later described. The shank  44  is also moveably mounted on the tubular portion  48 . In the illustrated structure, the thermocouple assembly  7  also has the electrical contact end  23  and a generally radially extending flange  50 . The resilient member  47  is captured between the end face  46  of the retainer  6  and the radially extending flange  50  and when the retainer  6  is mounted to the retainer  5 , it urges the contact end  23  into contact with a contact assembly  24  or a portion of the body  3 . The shank  44  is sized and shaped to be received within the cylindrical portion  33  for longitudinal and rotational movement therein. The shank  44  has outwardly extending projections such as ears  52  that are sized, shaped and positioned to be received through the two side projecting portions  34 .  
         [0026]     An upper portion of the retainer  6  is provided with means for assisting in turning the shank  44  when the ears  52  are in the internal chamber  30  to releasably mount the retainer  6  to the retainer  5 . As shown, the means includes a series of wrench flats  54  with four or six being a suitable number. Wings such as found on wing nuts may also be used in place of the wrench flats  54 . However, the use of exposed projections from the shank  44  could result in accidental dislodgment or decoupling of the retainer  6  from the retainer  5 . Preferably, the means to assist turning the retainer  6  does not project outwardly or significantly outwardly from the shank  44 . The ears  52  have cam engaging surfaces or shoulders  56  that are shaped and positioned to engage a respective cam  35  to retain the retainer  6  releasably mounted to the retainer  5  and a portion of the thermocouple assembly  7  positioned at a desired location. The length of the level end surface portion  36  is such as to allow from about 10° to about 20° of rotation of the retainer  6  relative to the retainer  5  before the ears  52  each engage the respective inclined portion  39 .  
         [0027]     In the illustrated embodiment as shown in  FIG. 6 , the contact end  23  is held in engagement with a contact assembly  24  which is a portion of an electrical control circuit  59  when the burner (not shown) is needed to provide heat. Thus, the thermocouple assembly  7  indicates that a pilot light  60  is lit while the electrical control circuit  59  also provides a signal that heat is needed and when the complete circuit is made the electromagnet  20  is energized urging the valve mechanism  13  to open. When adequate heat has been supplied, the electrical control circuit  59  provides an open circuit deenergizing the electromagnet  20 . The electromagnet  20  may also be deenergized if the pilot flame  60  heating the thermocouple assembly  7  is out. A heat sensitive switch  58  may also be provided that provides an indication, e.g., indicates that the water requires heat.  
         [0028]     Referring now to  FIGS. 4 and 7 , a thermocouple assembly  7  may be coupled to the body  3  by first installing the retainer  5  to the body as by effecting the threaded engagement between the threaded engagement  41  and the interior threaded matching surface  43 . The retainer  6  is then installed to effect contact between the contact end  23  and the contact assembly  24  by inserting the lower portion of the retainer  6  into the through opening  32  through the generally cylindrical portion  33  and directing the ears  52  into and through the two side projecting portions  34 . By rotation of the retainer  6  relative to the retainer  5  the ears  52  are moved into engagement with the level end surface portions  36  of the cams  35 . The retainer may be installed with an initial installation step, by hand, by moving the ears  52  onto the level end surface portions  36 , where the force of the resilient member  47  will retain the retainer  6  in the retainer  5 . The installer may then obtain a wrench to effect complete installation by further turning of retainer  6 . This construction is particularly effective in an upside down installation as seen in  FIG. 1 . The resilient member  47  will be compressed to ensure releasable engagement between the retainer  6  with the retainer  5 . Ear retaining indentations  61  may also be provided in the cams  35  to mechanically interengage with the ears  52  to help resist relative rotation to effect disengagement of the retainer  6  from the retainer  5 . When the retainer  6  is installed and at the end of relative rotation which is about 90° of rotation, the ears  52  move into the ear retaining indentations  61  generating an audible sound like a snap or click to inform the installer that installation is complete. As can be seen, almost all components of the retainer  6  are positioned in the retainer  5  and thus shielded to help prevent accidental disengagement of the retainer  6  from the retainer  5 . Contrary to a typical bayonet thermocouple mounting device, the male portion (ears  52 ) of the mounting assembly  1  is mounted to the thermocouple assembly  7  while the female portion (internal chamber  30  and cams  35 ) of the mounting assembly  1  is mounted to the body  3 .  
         [0029]     Thus, there has been shown and described several embodiments of a novel invention. As is evident from the foregoing description, certain aspects of the present invention are not limited by the particular details of the examples illustrated herein, and it is therefore contemplated that other modifications and applications, or equivalents thereof, will occur to those skilled in the art. The terms “have,” “having,” “includes” and “including” and similar terms as used in the foregoing specification are used in the sense of “optional” or “may include” and not as “required.” Many changes, modifications, variations and other uses and applications of the present construction will, however, become apparent to those skilled in the art after considering the specification and the accompanying drawings. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims that follow.