Abstract:
A fuel filter housing and fuel heater combination for a fuel-water separator includes, as part of the fuel filter housing, a heater-receiving bore and a notch, opening into the heater-receiving bore. The notch is constructed and arranged with a ramp portion extending axially into the fuel filter housing. The fuel heater is constructed and arranged for inserting into the bore and includes a flange that is attached to the housing for securing the fuel heater in position. The fuel heater includes a protrusion that inserts into the notch and is seated against the ramp portion when the fuel heater is fully installed. O-ring seal swelling may cause the fuel heater to be locked into the bore and the protrusion cooperates with the ramp portion by way of a camming action to facilitate removal of the fuel heater from the bore under such conditions.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates in general to fuel heater elements and the structural design features that are associated with installation and removal of the fuel heater element from a housing. More specifically, the present invention relates to a rod-shaped heater for a fuel-water separator that includes a cam removal feature. As disclosed herein, the cam removal feature includes a cooperation between the fuel heater and a portion of the fuel-water separator housing that facilitates removal of the heater from the housing. 
     In the field of diesel engine technology, it is not uncommon for diesel fuel to require heating in order to reduce the chances that the fuel will assume a gel-like consistency that would in turn be difficult to deliver and process. Often, a suitable heater is assembled as part of a fuel-water separator to try and eliminate this potential problem. As the fuel is filtered, water and particulate are separated and collected for removal. Since such a filter/separator may be used in low temperature conditions, though not continuously, the fuel heater is controlled by a thermostat that monitors the fuel temperature and is set to activate at a preset temperature, such as 35° F. When the fuel heater is energized, it generates a beat increase to the interior of the housing. This in turn liquefies any gelled fuel, allowing the fuel to flow freely. 
     While there are a variety of heater designs that are currently available or have been offered for use in fuel-water separators, a couple of the more common styles can be improved upon and are improved upon by the present invention. One such prior style is a ring heater that is installed into the filter/separator housing and is captured by its manner of insertion and attachment and/or by use of the closing lid. Ring heaters of the type described are relatively complex in construction and necessitate a fairly complex cooperating configuration within the filter housing. There may be added complexity, depending on the selected configuration and the interconnect with the thermostat and the electrical power connector. 
     One attempt to simplify the complexity of the ring heater is represented by the second prior style that can best be described as a rod heater. This descriptive name comes from the generally cylindrical shape of the fuel heater. This style of heater is typically threaded into a receiving bore in the fuel-water separator. Since there is fuel inside of the housing and since there is an internal pressure, it is important to adequately seal the interface between the heater and the separator housing. If a plastic housing is used, concerns have been raised as to whether sufficient tightening torque can be applied by way of the threaded engagement to adequately seal the threaded interface. 
     Another concern with a threaded engagement between the rod heater and the separator housing is the ability to establish the desired orientation for the electrical connector on the fuel heater relative to the housing. Over tightening or under tightening of the threaded engagement will cause the rotational position or orientation of the electrical connector to change. The starting point of the threaded engagement can also affect the orientation of the electrical connector. As such, the fuel heater may not be rotated into the preferred location for electrical connection to the heater wires from the wiring harness of the corresponding engine. It would therefore be an improvement if the heater could be installed in the housing with an automatic alignment capability. The present invention provides this improvement without relying on a threaded engagement between the heater and the fuel-water separator housing. 
     One of the realities of installing a rod heater into a fuel-water separator housing is the need to include a seal, such as an elastomeric O-ring seal, for establishing a sealed interface between the heater and the housing. Over time, the O-ring seal swells in size and becomes even tighter, tighter to the extent that it is difficult to break the O-ring seal free in order for removal of the heater. The effect of this O-ring seal swelling is to wedge the fuel heater into the separator housing to the point that the heater appears to be stuck and, as a result, not easily removed from the housing. 
     The present invention addresses this concern in a novel and unobvious way by creating a cooperating cam engagement between the fuel heater and the fuel-water separator housing. This cam action translates rotational motion of the fuel heater relative to the housing into an axial force to help break away the tightly wedged O-ring seal. Once the wedged seal is broken free, the fuel heater can be easily removed without the need for any special removal tool and without the risk of damaging the fuel heater. The fuel heater can be removed by hand and this provides yet another benefit attributable to the present invention. 
     SUMMARY OF THE INVENTION 
     The combination of a fuel filter housing and a fuel heater according to one embodiment of the present invention includes a heater-receiving bore and a notch opening into the bore as part of the fuel filter housing. The fuel heater is constructed and arranged for inserting into the heater-receiving bore and for being attached to the fuel filter housing. The fuel heater includes a protrusion that is constructed and arranged for engaging the notch such that turning the fuel heater causes the protrusion to cooperate with a ramp portion of the notch in order to facilitate removal of the fuel heater from the heater-receiving bore by a camming action. 
     One object of the present invention is to provide an improved installation interface between a fuel filter housing and a fuel heater to facilitate removal of the fuel heater from the fuel filter housing. 
     Related objects and advantages of the present invention will be apparent from the following description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a fuel heater installed into a fuel-water separator housing according to the present invention. 
     FIG. 2 is a partial, perspective view of the FIG. 1 fuel-water separator housing showing a heater-receiving bore. 
     FIG. 3 is a diagrammatic, perspective view of the FIG. 1 fuel heater. 
     FIG. 4 is an enlarged detail of a cam protrusion comprising a portion of the FIG. 3 fuel heater. 
     FIG. 5 is a perspective view of the initial step of installing the FIG. 3 fuel heater into the FIG. 2 heater-receiving bore. 
     FIG. 6 is a perspective view of a subsequent step of installing the FIG. 3 fuel heater into the FIG. 2 heater-receiving bore. 
     FIG. 7 is a diagrammatic view of a fuel-water separator housing notch that opens into the heater-receiving bore. 
     FIG. 8 is a diagrammatic view of the cooperating relationship between the FIG. 7 notch and the FIG. 4 protrusion. 
     FIG. 9 is a diagrammatic view of the cooperating relationship between the FIG. 7 notch and the FIG. 4 protrusion. 
     FIG. 10 is a diagrammatic view of an alternative fuel-water separator housing notch that opens into the heater-receiving bore. 
     FIG. 11 is a diagrammatic view of the cooperating relationship between the FIG. 10 notch and the FIG. 4 protrusion. 
     FIG. 12 is a diagrammatic view of the cooperating relationship between the FIG. 10 notch and the FIG. 4 protrusion. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates. 
     Referring to FIG. 1, there is illustrated a portion of a fuel-water separator  20  with a fuel heater  21  installed into a heater bore  22  that is defined by the wall of separator housing  23 . The boss  24  that surrounds bore  22  includes two mounting holes  25  that are constructed and arranged to receive threaded fasteners (not illustrated) that cooperate with fuel heater  21  to securely retain fuel heater  21  in bore  22 . The mounting holes can be internally threaded or self-tapping screws can be used for the referenced threaded fasteners. The fuel heater  21  includes a mounting flange  26  that is configured with clearance slots  26 a for receiving the threaded fasteners. Alternatively, the flange  26  can be constructed and arranged with clearance holes. 
     Referring now to FIG. 2, the inside surface  30  of bore  22  defines a notch  31  according to the present invention. Notch  31  opens into bore  22  and has a circumferential extent of not more than 90° relative to said heater receiving bore and cooperates with an oblong protrusion  32  that is constructed and arranged as part of the fuel heater  21 , according to the present invention, to facilitate removal of fuel heater  21  from the bore  22  of housing  23 , by a camming action. 
     Fuel heater  21  is illustrated in FIG.  3  and the protrusion  32  is illustrated in enlarged detail in FIG.  4 . It is intended for fuel heater  21  to be considered as a conventional fuel heater as far as its general shape, mechanical structure, and its electrical construction and properties. The only modification of this otherwise conventional fuel heater  21  is the addition of protrusion  32 . Protrusion  32  extends axially along a line that is parallel with the longitudinal axis of the fuel heater  21  and has a circumferential extent of not more than 90° relative to said fuel heater body. Fuel heater  21  includes mounting flange  26  and an O-ring seal  33  that is positioned around fuel heater  21  at a location along the length of fuel heater  21  so as to establish a liquid-tight interface between fuel heater  21  and the separator housing  23 . 
     When the fuel heater  21  is properly inserted into heater bore  22 , flange  26  is adjacent the outer surface  37  of boss  24  and the O-ring seal  33  is in contact with the cooperating sealing surface of the separator housing  23 . As the threaded fasteners are tightened into position, the fuel heater  21  becomes fully inserted, the O-ring seal  33  is compressed into liquid-tight contact, and flange  26  is drawn up tight against outer surface  37 . As this is occurring, the protrusion  32  is drawn into contact with a ramp portion of notch  31 . 
     Over time, with continued use of the fuel-water separator  20 , the O-ring seal  33  swells and creates interference that actually locks or wedges the fuel heater  21  in the heater bore  22 . As a result, any attempt to remove fuel heater  21  from bore  22  encounters added difficulty due to the interference created by the swelling of the O-ring seal  33 . In effect, the fuel heater is locked in position relative to separator housing  23 . In order to remove the fuel heater  21  from separator housing  23 , this locked condition needs to be broken. It would be preferable to be able to break the fuel heater  21  free from the separator housing  23  without the need for special tools. This is where the present invention is employed and it provides an improvement in the area of fuel heater removal. 
     With reference once again to FIG. 2, it will be seen that notch  31  is recessed down into the defining sidewall of boss  24 . The referenced ramp portion  38  has a first section  38   a  with a convex curvature and a base section  38   b  that is generally flat. The ramp portion  38  extends from the outer surface  37  to its inwardly most portion which is base section  38   b . In practice, the curved section  38   a  can be convex, as diagrammatically illustrated in FIGS. 7,  8 , and  9 , or concave, as diagrammatically illustrated in FIGS. 10,  11 , and  12 . The FIG.  2  and FIGS. 7-9 configurations are consistent with each other. With respect to FIGS. 10,  11  and  12 , the intent is to show a second option (concave) for first section  38   a . This alternative is identified as notch  31 ′ and ramp portion  38 ′. The axial depth of notch  31  is set by ramp portion  38 . The radial depth of notch  31  is set by wall  39  and the construction of notch  31  is completed by wall  40  that is substantially flat and parallel with the bore axis of heater bore  22 . The overall shape and geometry of notch  31  can be seen in FIG.  2  and its cooperation with protrusion  32  (part of fuel heater  21 ) is diagrammatically illustrated in FIGS. 8 and 9. 
     Referring now to FIGS. 1,  5 , and  6 , the procedure for installing fuel heater  21  into housing bore  22  is illustrated. Beginning with fuel-water separator housing  23  and bore  22 , fuel heater  21  (see FIG. 3) is selected and the heating end  43  is inserted into bore  22 . Protrusion  32  is aligned with notch  31  and the installation procedure continues with the continued advancement of fuel heater  21  into separator housing  23 . As flange  26  is advanced close to outer surface  37 , it will be seen whether protrusion  32  is sufficiently close to notch  31  to be received within the notch. In order to fully insert the fuel heater  21  into housing  23 , including proper compression of the O-ring seal  33 , the protrusion  32  must be positioned up against wall  40  since this represents the location of the greatest or maximum axial depth of notch  31  and in turn the positioning of protrusion  32 . If the fuel heater is not turned relative to bore  22  so that the protrusion lines up with the greatest axial depth location of notch  31 , the protrusion  32  will presumably abut up against another part of ramp portion  38  that is axially outwardly relative to the maximum axial depth of notch  31 . However, with continued advancement of the fuel heater  21  into the housing, the protrusion  32  is caused to slide down the first section  38   a  of ramp portion  38 , allowing the fuel heater  21  to turn slightly in a clockwise direction so as to cooperate with the travel of the protrusion. The rounded tip of protrusion  32  facilitates the sliding action of the protrusion  32  against the ramp portion  38 . In addition, as the fuel heater  21  turns so as to assume the desired position of protrusion  32  within notch  31 , the clearance slots  26   a  are caused to line up with the boss mounting holes  25 . 
     With protrusion  32  bottomed out against the base section  38   b  of ramp portion  38  at a location adjacent wall  40 , the fuel heater  21  is properly oriented relative to separator housing  23 . This proper orientation includes the correct positioning of electrical connector  44  for connection to the wires of the vehicle wiring harness for powering the fuel heater  21 . The proper orientation and positioning of fuel heater  21  relative to boss  24  includes the correct positioning of the two flange slots  26   a  relative to the two mounting holes  25  for receiving the selected mounting hardware, in this case, externally-threaded fasteners. 
     When it is desired to remove fuel heater  21  from housing  23 , the first step is to remove the two threaded fasteners (not illustrated) that secure flange  26  to outer surface  37 . While it might be expected that this would be all that is needed, the swelling of the O-ring seal  33  causes the fuel heater  21  to be “stuck” in the heater bore  22 . It thus becomes necessary to break loose the O-ring seal  33  and it would be an improvement to prior methods that use removal tools, some of which may have a specialized form, to be able to remove the fuel heater  21  by hand. This is where the present invention, with its cooperating protrusion  32  and notch  31 , is used. With the present invention, all that has to be done in order to break the fuel heater  21  free is to turn (rotate) the fuel heater  21  in a counter clockwise direction, based upon the orientation of the fuel heater  21  in FIG.  1 . The manual torque applied (by hand) to the outside diameter of the fuel heater  21  causes the protrusion  32  to slide across the surface of first section  38   a  of ramp portion  38  from a starting location adjacent wall  40  upwardly toward outer surface  37 . Since the axial depth of ramp portion  38  is less as the counter clockwise rotation continues, the manual torque is converted into an axial force exerted through the protrusion against the ramp portion  38 . This axial force helps to break free the fuel heater  21  and acts in pushing the fuel heater  21  out of heater bore  22 . What results is a camming action using the cooperating relationship between the protrusion  32  and notch  31 , specifically the ramp portion  38 , to help the fuel heater  21  break free of any stuck or “frozen” condition due to the swelling of the O-ring seal  33 . Once the fuel heater  21  breaks free, it can be easily removed from the fuel-water separator housing  23 . The entire removal procedure is done by hand, without the need for any tools, special or conventional. 
     While the illustrated notch  31  has a circumferential arc length that is approximately about 30 degrees, this arc length can be increased which would result in a longer, more gradual ramp incline on portion  38 . A 90 degree arc length for notch  31  would result in a quarter turn design for breaking free the fuel heater  21  from any stuck or wedged condition within bore  22  due to the swelling of O-ring seal  33 . A 180 degree arc length would result in a half-turn design. An arc length of between 30 degrees and 90 degrees is likely preferred, but almost any are length will work in accordance with the present invention. 
     Another design consideration and option is to vary the axial depth of notch  31 . While the functional and structural characteristics of fuel heater  21  have to be considered, the only obvious effect of a deeper notch is the need to lengthen the protrusion so that once the heater is fully seated into the heater bore  22 , the protrusion  32  continues to ride on the ramp portion  38 . As would be understood, the curvature of first section  38   a  of ramp portion  38  is a function of the overall are length of the notch as well as the axial depth of the notch relative to outer surface  37 . 
     Another design variation that is contemplated for the present invention is to add a second notch and a second protrusion. This second cooperation combination of notch and protrusion would be spaced apart from the first cooperation combination. Preferably the spacing is envisioned to be less than 180 degrees so that the fuel heater  21  cannot be installed upside down, i.e., inverted 180 degrees from its designed orientation (see FIG.  1 ). A spacing of approximately about 120 degrees would avoid the 180 degree issue and avoid any interference with a location of either of the two mounting holes  25 . 
     A still further design variation contemplated by the present invention is to reverse the notch and the protrusion. Rather than placing the protrusion as part of the fuel heater, the protrusion could be included as part of the separator housing and design a cooperating notch into the fuel heater. Accordingly, the present invention specifically contemplates a cooperating relationship between the fuel heater and the separator housing that employs a camming action resulting from the turning or rotation of the fuel heater in a counter clockwise direction. Accordingly, the present invention can be described in the context of a fuel heater having a first camming member and a separator housing having a second camming member where these two camming members cooperate in order to facilitate removal of the fuel heater from the separator housing. 
     A still further design variation contemplated for the present invention involves changing the overall size and shape of the protrusion. Although the design illustrated includes a generally rectangular solid form with a rounded or radiused tip, other sizes and shapes may be suitable and are intended to be encompassed by the present invention. 
     While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiment has been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.